New Drug Development and Clinical Pharmacology

Targeting the WNT Signaling Pathway in Cancer Therapeutics DAVID TAI,a KEITH WELLS,b JOHN ARCAROLI,b CHAD VANDERBILT,c DARA L. AISNER,c WELLS A. MESSERSMITH,b CHRISTOPHER H. LIEUb a

Division of Medical Oncology, National Cancer Centre Singapore, Singapore, Singapore; bDivision of Medical Oncology and cDepartment of Pathology, University of Colorado Denver, Aurora, Colorado, USA Disclosures of potential conflicts of interest may be found at the end of this article.

Key Words. WNT x Signal transduction x Drug development x b-Catenin x Frizzled

ABSTRACT The WNT signaling cascade is integral in numerous biological processes including embryonic development, cell cycle regulation, inflammation, and cancer. Hyperactivation of WNT signaling secondary to alterations to varying nodes of the pathway have been identified in multiple tumor types. These alterations converge into increased tumorigenicity, sustained

proliferation, and enhanced metastatic potential. This review seeks to evaluate the evidence supporting the WNTpathway in cancer, the therapeutic strategies in modulating this pathway, and potential challenges in drug development. The Oncologist 2015;20:1189–1198

Implications for Practice: The WNT signaling cascade is integral in numerous biological processes, including cell cycle regulation and cancer. Alterations in WNT signaling have been identified in numerous tumor types, and in recent years, numerous WNT pathway modulators have been tested in preclinical studies.These agents are now being investigated in the clinical arena, and this review describes the WNT pathway and therapeutics currently in development.

INTRODUCTION The WNT signaling cascade is a central regulatory pathway in controlling key functions of normal and malignant epithelial cells and has become an important new target for cancer drug development. Despite its complexity, it is worth laying forth the pathway’s multiple components and detailing the points of interest in cancer therapeutics. The pathway is composed of a group of signal transduction elements that regulate gene transcription, cytoskeletal changes, and calcium flux within epithelial cells. This cascade is integral to embryonic development, cell cycle regulation, inflammation, and cancer [1, 2]. The pathway is driven by WNT ligands (WNT), which are a family of 19 glycoproteins that signal through both canonical (b-catenin dependent) and noncanonical (b-catenin independent) mechanisms, as depicted in Figure 1 [3]. We now know that WNT and its downstream effectors, when deregulated, promote cancer initiation, growth, and metastasis. Alterations in this pathway have been implicated in the development of breast cancer, colorectal cancer, melanoma, prostate cancer, lung cancer, and other tumor types. WNT signaling is required for regulation of growth, differentiation, and cell death in normal epithelial cells. The complex regulatory pathway begins when WNT ligands bind to multiple transmembrane receptors, including 10 members of the frizzled (FZD) family of G-protein-coupled receptors,

receptor tyrosine kinases (RTKs) ROR1 and ROR2, and RTKlike protein kinases triggering downstream activation [4, 5]. In the b-catenin-dependent pathway, absence of WNT stimulation leads to phosphorylation and degradation of b-catenin by a destruction complex containing adenomatous polyposis coli (APC), glycogen synthase kinase 3b (GSK3b), and Axin. Destruction of b-catenin results in expression of b-catenin-repressed target genes c-Myc, cyclin D1, and survivin. A critical regulator of b-catenin destruction is the protein Axin. Overexpression of Axin induces b-catenin degradation in cell lines expressing truncated APC [6, 7].The levels of Axin are in turn controlled by tankyrases, members of the PARP-family of poly-ADP-ribosylation enzymes that destabilize Axin, resulting in activation of WNT signaling [8]. Binding of WNT (e.g., WNT 1 and WNT 3) to its known receptors or coreceptors (LRP5 or LRP6) results in activation of dishevelled (DVL) protein. Activated DVL inhibits the destruction complex, resulting in accumulation of cytoplasmic b-catenin that thenentersthenucleus.Intranuclearb-cateninactsasacoactivator of T cell transcription factor (TCF) and lymphoid enhancer factormediated gene transcription, causing changes to cell proliferation, survival, and differentiation. Beyond the destruction complex, negative regulators of the WNTpathway include secreted dickkopf (Dkk), soluble frizzled-related proteins, and WNT inhibitory factor [9, 10]. Porcupine (PORCN), a membrane bound O-acyltransferase

Correspondence: Christopher H. Lieu, M.D., University of Colorado Denver, 12801 E. 17th Avenue, MS 8117, Aurora, Colorado 80045, USA. Telephone: 303-724-6390; E-Mail: [email protected] Received February 11, 2015; accepted for publication June 23, 2015; published Online First on August 25, 2015. ©AlphaMed Press 1083-7159/2015/$20.00/0 http://dx.doi.org/10.1634/theoncologist.2015-0057

The Oncologist 2015;20:1189–1198 www.TheOncologist.com

©AlphaMed Press 2015

Targeting the WNT Signaling Pathway

1190

that is required for WNT palmitoylation, secretion, and biological activity, acts as a positive regulator of the pathway. WNT also modulates its downstream effects via noncanonical WNT pathways: the planar cell polarity signaling pathway and calcium-dependent and small-GTPase-dependent signaling pathways [11]. Both the b-catenin-dependent and -independent pathways are implicated in tumorigenesis and cancer progression, albeit with some pleiotropy.This review will focus primarily on the canonical pathway.

WNT PATHWAY DYSREGULATION IN CANCER The importance of aberrant WNTsignaling in tumorigenesis was first discovered during tumor induction in a mouse model following proviral insertion at the WNT locus [12]. Activated WNTsignaling has also been implicated in proliferation, survival, and ability to metastasize in various cancers cell types. In addition, numerous studies indicate that this pathway is crucial for maintenance of highly tumorigenic cancer-initiating cells. Activation of WNTsignaling can be achieved through either mutational or nonmutational alterations. Thwarting this signaling cascade has led to inhibition of tumor growth in preclinical models, prompting clinical development of WNT inhibitors.

Mutational Alterations in WNT Pathway Activating mutations involve three major components of the WNT cascade: degradation complex, b-catenin, and TCF. Loss-offunction mutations characterize the negative regulators of the WNT pathway (degradation complex comprising APC, AXIN, and WTX), whereas gain-of-function mutations are observed for b-catenin and TCF transcription factor (positive regulators).WNT pathway-inactivating mutations remain to be seen in cancer. Colorectal cancer (CRC) epitomizes the mutational aberrations of hyperactivated WNTsignaling.Truncating mutations of the APC gene have been linked to both hereditary (familial adenomatous polyposis [FAP]) and sporadic CRC. Downregulation of transcription activation mediated by b-catenin and TCF is crucial to APC’s suppressive effect, and this regulation can be abrogated by mutations involving either APC or b-catenin [13]. Patients with FAP typically develop innumerable polyps in the colon at a young age, and progression to CRC is the rule [14]. Alterations in Axin, a negative regulator of the WNT pathway, have also been described in CRC. Most AXIN1 mutations in CRC occur between exons 1 and 5, which code for protein regions in which the APC, GSK3b, and b-catenin binding domains are located. Mutations in AXIN2 have been associated with colorectal cancer with defective mismatch repair by activating b-catenin/TCF signaling and typically involve one base deletion or insertion in exon 7 [15]. These mutations lead to elimination of the DIX domain, at which DVL binds and negatively regulates Axin activity [16]. Axin has been found to regulate the efficiency of the b-catenin destruction complex in a concentration-dependent manner [17]. Intriguingly, overexpression of Axin1 causes b-catenin degradation, even in cell lines with truncated APC [7].

shown to be dysregulated in numerous cancers [18–21], and comprehensive reviews have addressed WNT dysregulation in cancer in detail [1, 22, 23]. Table 1 gives a detailed description of WNT pathway alterations involving various tumor types.

WNT Pathway Modulation Pharmacological modulation can be divided into compounds that modulate the ligand/receptor interface, stabilize the degradation complex, or interfere with b-catenin-dependent gene transcription. Figure 1 depicts the WNTsignaling pathway, annotated with therapeutic compounds at various nodes.

MODULATION OF THE LIGAND/RECEPTOR INTERFACE OMP-18R5 OMP-18R5 (vantictumab; OncoMed Pharmaceuticals, Redwood City, CA, http://www.oncomed.com) is a monoclonal antibody that interacts with 5 frizzled receptors, thus blocking the induction of WNT cascade by its ligand. This antibody exhibited synergism with standard of care chemotherapy causing tumor growth inhibition of xenografts derived from breast, colon, pancreas, and lung cell lines. Gene expression and quantitative polymerase chain reaction analysis demonstrated reduction of known b-catenin target genes consistent with WNT pathway blockade [24]. Experiments conducted on Ptf1a-Cre, LSL-KrasG12D, b –cateninf/f (KBC) mice, in which both alleles of b-catenin are floxed in the context of mutant KRAS, revealed that treatment with OMP-18R5 inhibited PanIN formation. In a phase I trial of refractory solid tumor patients, 29 patients were treated and maximum tolerated dose had not been reached. OMP-18R5 was well tolerated up to the current dose of 15 mg/kg every 3 weeks. Side effects included grade 1/2 fatigue, vomiting, abdominal pain, constipation, diarrhea, and nausea. One instance of dose-limiting grade 3 nausea and vomiting was reported at the second dose level. Marked increases in b C-terminal telopeptide (b-CTX), serum marker of bone turnover observed in a proportion of patients, coupled with grade 2 compression fractures after a fall in one patient, were notable observations. Prophylactic calcium carbonate/ vitamin D and administration of zolendronic acid as indicated were instituted. OMP-18R5 demonstrated decreased expression of WNT pathway target genes in pharmacodynamics studies involving hair follicles. Three patients with neuroendocrine tumors, all of whom had radiologic progressive disease prior to enrollment, experienced prolonged stable disease (.300 days) while on treatment [25] (ClinicalTrials.gov identifier NCT01345201). Combination studies incorporating OMP-18R5 with taxanes arecurrentlyunder wayintwo separatephaseIbstudiesinpatients with non-small cell lung carcinoma (ClinicalTrials.gov identifier NCT01973309) and non-Her2 advanced breast carcinoma (ClinicalTrials.gov identifier NCT01957007). A study evaluating combination nab-paclitaxel and gemcitabine with vantictumab in patients with untreated advanced pancreatic cancer is also actively enrolling (ClinicalTrials.gov identifier NCT02005315).

Nonmutational Alterations Constitutive activation of WNT/b-catenin signaling in cancer can occur via epigenetic silencing of extracellular WNT antagonists. Both canonical and noncanonical WNT have been

OMP-54F28 OMP-54F28 (OncoMed Pharmaceuticals) is a recombinant fusion protein combining human FZD8 receptor with the ligand

OTncologist he

©AlphaMed Press 2015

®

Tai, Wells, Arcaroli et al.

1191

Figure 1. Therapeutic targeting of the canonical WNT pathway. The WNT signaling pathway plays an essential role in regulating selfrenewal of the cancer stem cell population and tumorigenesis by enhancing cellular proliferation and survival.When WNT ligands are not present (left), b-catenin is phosphorylated, ubiquitinated, and marked for degradation by the destruction complex that is composed of Axin, adenomatous polyposis coli (APC), and glycogen synthase kinase 3b (GSK3b). This results in the association of the repression complex HDAC, Groucho, and TCF/LEF, which prevents WNT-dependent transcription. The binding of WNT ligand to the frizzled receptor (right) activates dishevelled (DVL).This leads to the inactivation of the destruction complex and subsequent translocation of b-catenin into the nucleus and to WNT-dependent transcription. Many different compounds are currently under preclinical (blue) and clinical (red) development that target many different components of the WNT pathway to inhibit WNT-dependent tumor growth. A detailed description of the inhibitors under development is shown in Table 2. Abbreviations: CBP, CREB binding protein; CK1, casein kinase 1; DKK, dickkopf-related protein; HDAC, histone deacetylase inhibitors; LEF, lymphoid enhancer factor; LRP, low-density lipoprotein receptor-related protein; TCF, T cell transcription factor; Ub, ubiquitin.

binding domain and human IgG1 Fc fragment. OMP-54F28 acts as a decoy receptor by sequestering WNT ligands. Testing in xenograft models showed that OMP-54F28 impeded the growth of numerous solid tumor types and selectively reduced cancer stem cells when administered alone, or in combination with chemotherapeutic agents [26]. Notably, in pancreas tumors, OMP-54F28 promotes a marked differentiation of tumor cells that is coupled with profound reductionin tumorigenic potential. A phase I study is ongoing and enrolling patients with advanced solid tumors (ClinicalTrials.gov identifier NCT01608867). As of June 2014, 25 patients had been treated in 7 doseescalation cohorts (0.5, 1, 2.5, 5, 10, 15, and 20 mg/kg every 3 weeks). No dose-limiting toxicities (DLTs) were observed at the highest dose level. Grade 1/2 toxicities included anorexia, fatigue, hypocalcemia, nausea, hypertension, peripheral edema, and vomiting. A single grade 3 anemia was noted. Of the 25 patients treated thus far, 6 patients experienced a doubling of b-CTX, a phenomenon also seen with OMP-18R5 [25]. Five of 5 patients reversed the increase in b-CTX with zoledronic acid. Three phase Ib clinical trials of OMP-54F28 are ongoing: one in pancreatic ductal adenocarcinoma (gemcitabine/ nab-paclitaxel with OMP-54F28, ClinicalTrials.gov identifier NCT02050178), one in hepatocellular carcinoma (sorafenib with OMP-54F28, ClinicalTrials.gov identifier NCT02069145), and one in ovarian cancer (carboplatin/paclitaxel with OMP54F28, ClinicalTrials.gov identifier NCT02092363).

WNT3A at serine 209. Acylation of S209 is essential for the both WNT secretion and extracellular interaction with frizzled receptors. LGK974 (Novartis, Basel, Switzerland, https://www. novartis.com), a potent and specific small molecule PORCN inhibitor, has been shown to reduce WNT-dependent LRP6 phosphorylation and expression of WNT target genes in preclinical models. LGK974 demonstrated antitumor response in in vivo breast, pancreas, and head and neck cancers [27]. Intriguingly, all LGK974-sensitive pancreatic cell lines carried a loss-of-function mutation in the ubiquitin E3 ligase ring finger 43 (RNF43) gene. Functionally, RNF43 is a negative regulator of WNT and inhibits the WNT signaling by reducing levels of membrane frizzledreceptors[28],andwhole-exomesequencingofcolorectal and endometrial cancers identified somatic mutations of RNF43 in more than 18% of colorectal and endometrial carcinomas [29]. Phase I evaluation of LGK974 is under way (ClinicalTrials.gov identifier NCT01351103), enrolling patients with melanoma, breast cancer (lobular or triple negative), and pancreatic cancer.

Notably, in pancreas tumors, OMP-54F28 promotes a marked differentiation of tumor cells that is coupled with profound reduction in tumorigenic potential.

ANTIBODIES DIRECTED AGAINST DICKKOPF-1 (DKK1)

LGK974

DKN-01

PORCN, a membrane bound O-acyltransferase, is a key enzyme in WNT biosynthesis. PORCN adds palmitate (acylates) to human

DKN-01 (HealthCare Pharmaceuticals, Cambridge, MA, http:// healthcarepharmaceuticals.com), a monoclonal antibody against

www.TheOncologist.com

©AlphaMed Press 2015

Targeting the WNT Signaling Pathway

1192

Table 1. WNT pathway alterations in various tumor types

Type of cancer

Mutations/other genetic eventsa

Percentage mutated, % (mutated samples/ samples tested)a

Gastrointestinal Colorectal adenocarcinoma

APC

46.9 (2221/4733)

TCF7L2

7.7 (58/747)

AMER1 AXIN1 CTNNB1

8.7 (71/811) 10.0 (37/917) 6.5 (318/4827)

Hepatocellular carcinoma

CTNNB1 AXIN1 APC

18.1 (673/3720) 8.6 (75/872) 1.4 (7/512)

Pancreas ductal carcinoma

APC CTNNB1 RNF43

4.8 (14/287) 1.6 (6/377) 1.5 3/198

Biliary tract Adenocarcinoma

AXIN1 CTNNB1 APC

12.2 (10/82) 3.4 (17/495) 2 (3/150)

Stomach adenocarcinoma

APC

14.0 (3/22)

Breast Breast carcinoma

CTNNB1

9.1 (2/22)

APC

2.2 (43/1945)

Aberrant mRNA splicing of LRP5

[61]

Epigenetic/other mechanisms in laboratory models (Fig. 1) Methyl-CpG binding repressor Mbd2 recruits corepressor complex to methylated DNA and is essential for tumorigenesis in ApcMin/1 mouse model. Deficiency in Mbd2 reduces adenoma formation. DACT3, a member of the FDO/DPR gene family, inhibits WNTsignaling by interacting with DVL proteins. DACT3 is repressed in colon cancers by histone modification; de-repression leads to inhibition of WNT signaling and promotion of apoptosis in CRC cell lines. The complex of leukemia-associated chromatin modifying complex (Mllt10/Af10) and its partner histone methyltransferase (Dot1L) is an essential coactivator of TCF-driven activation of WNT targets. Promoter hypermethylation of sFRP1 leads to loss of antagonism activity on WNT signaling. Demethylation with 5-aza-20-deoxycytidine restores sFRP1 expression and impairs HepG2 cell invasive potential. WNT3/4/5a upregulation reported in HBV-related HCC. Pharmacologic inhibitionof FZD7 displays antitumor activity in in vivo models. Downregulation of WIF-1 via hypermethylation, transcriptional profiling reveals elevated WNT7B expression of in pancreas adenocarcinoma cell lines with high levels of autonomous WNT/ b-catenin activation. Gene silencing and small molecule inhibitor IWP-2 blocks WNT ligand processing and secretion, leading to anchorageindependent growth. Genome wide methylation analysis reveals gene silencing involving SOX17, WNT3A, DKK2, SFRP1, SFRP2, and SFRP4. Promoter hypermethylation involving SFRP1, SFRP2, SFRP4, SFRP5, Wif-1, and DKK3 is significantly higher in gastric tumor tissues compared with adjacent noncancerous tissue.

DNA methylation involving WIF1, SFRP1-5, APC, and DKK1 implicated in development and progression of breastcancer.WNT2,WNT7b,WNT10b upregulated. SFRP-1 is typically absent in breast cancer due to hypermethylation. Overexpression of SFRP1 in human breast cancer MDA-MB-231 cells blocks canonical WNT signaling and reduces proliferation and metastasis.

Reference [53, 54]

[55]

[56]

[48, 57]

[50, 58]

[59]

[60]

[18, 53]

[19]

(continued)

OTncologist he

©AlphaMed Press 2015

®

Tai, Wells, Arcaroli et al.

1193

Table 1. (continued)

Type of cancer Genitourinary Endometrial carcinoma

Mutations/other genetic eventsa

Percentage mutated, % (mutated samples/ samples tested)a

CTNNB1

19.4 (298/1537)

Cervical carcinoma

CTNNB1

1.9 (4/212)

Ovarian carcinoma

CTNNB1 APC

6.4 (102/1599) 1.7 (15/867)

Prostatic adenocarcinoma

CTNNB1 TMPRSS2-ERG gene fusion

6.3 (102/1599) 50 [66]

Wilms tumor

CTNNB1 AMER1

18.9 (189/1002) 13 (132/1019)

CTNNB1 APC APC

17.9 (29/162) 4.4 (4/91) 12.8 (294/2295)

CTNNB1 APC

10.2 (8/78) 3.1 (2/65)

SS18-SSX gene fusion LRP5 copy number gain

[68] [69]

Endocrine/carcinoid Adrenal cortical carcinoma Pancreatic neuroendocrine tumor Small bowel carcinoid Mesenchymal neoplasm Bone and soft tissue

Melanoma

Hematologic Lymphoma/leukemia

APC CTNNB1

CREBBP/EP300

Multiple myeloma

0.9 (16/1787) 2.1 (51/2373)

[71]

Epigenetic/other mechanisms in laboratory models (Fig. 1) APC promoter 1A hypermethylation observed in 46.6%. WIF1 gene promoter is aberrantly methylated. Loss of SFRP4 is associated with more aggressive ovarian cancer phenotypes. Treatment with recombinant SFRP4 decreases transcription of b-catenin target genes and increasesE-cadherin. WNT inhibitor WIF1 gene is downregulated in prostate cancer cell lines through promoter hypermethylation. Restoration of WIF1 expression results in decreased motility and invasiveness of prostate cancer cells. Overexpression of WNT5A promotes aggressiveness in prostate cancer; knockdown reduces invasiveness of prostate cancer cells.

Reference [62] [63] [64]

[59, 65]

Promoter methylation of SFRP-1 and Axin2 or histone modifications of H3K9me2 (DKK1, DKK3, and WIF-1) detected.

[67]

Increased expression of multiple WNT ligands in up to 50% of human sarcomas. Downregulation of activated WNT signaling inhibits human sarcoma proliferation in vitro and in vivo. Promoter methylation leads to silencing of DKK1 and SFRP. Transcriptional silencing of APC by promoter hypermethylation present in 17% of melanoma biopsies. WNT3A mediates transcriptional changes leading to less proliferative cell fate.

[72]

Hypermethylation of gene promoters observed in six genes: SFRP1, SFRP2, SFRP5, SFRP4, DKK1, and DKK3 in AML. CGP049090 and PFK115-584 (small molecule inhibitors of the b-catenin/TCF/ LEF-1 interaction) induce apoptosis in AML cells. Production of DKK1, sFRP2, and sFRP3 by myeloma cells leads to the development of osteolytic lesions via suppression of osteoblast differentiation. BHQ880 (anti-DKK1 neutralizingantibody) inhibits growth of myeloma cells.

[66, 70]

[20]

[31]

(continued)

www.TheOncologist.com

©AlphaMed Press 2015

Targeting the WNT Signaling Pathway

1194

Table 1. (continued)

Type of cancer Lung, Head, and Neck Salivary gland carcinomas

Anaplastic thyroid carcinoma

Mutations/other genetic eventsa

Percentage mutated, % (mutated samples/ samples tested)a

AXIN1

5.2 (6/114)

AXIN1 APC

31.0 (18/58) 16.0 (4/25)

Lung

Epigenetic/other mechanisms in laboratory models (Fig. 1)

Reference

WNT/b-catenin signaling found to induce epigenetic changes that lead to salivary gland squamous cell carcinoma in animal models.

[72]

WNT inhibitory factor-1 is silenced by promoter hypermethylation in lung cancer.

[73]

Data derived from COSMIC database, accessed January 14, 2015. Data were accessed by utilizing the COSMIC database “Cancer Browser” feature and selecting for the specific malignancy. Individual genes were queried within each tumor type. Abbreviations: APC, adenomatous polyposis coli; CRC, colorectal cancer; DVL, dishevelled; HBV, hepatitis B virus; HCC, hepatocellular carcinoma; LEF, lymphoid enhancer factor; TCF, T cell transcription factor.

a

dickkopf WNT signaling pathway inhibitor 1 (DKK1), was evaluated in patients with multiple myeloma and advanced solid tumorsinphaseItesting(ClinicalTrials.govidentifierNCT01457417). Overexpression of protein DKK1 has been associated with multiple myeloma (MM). Production of DKK1 by myeloma cells leads to development of osteolytic lesions through direct suppression of osteoblast differentiation. Preclinical studies suggested an indirect antimyelomaeffectsecondarytoinhibitionofosteoclastogenesisby DKN-01 [30]. In addition, a phase I/II study combining DKN-01 with lenalidomide/dexamethasone is being evaluated in patients with relapsedorrefractorymultiplemyeloma(ClinicalTrials.govidentifier NCT01711671).

BHQ880 BHQ880 (Novartis) is a phage-derived monoclonal antibody against DKK1. Although BHQ880 had no direct effect on MM cell growth, it significantly inhibited growth of MM cells in the presence of bone marrow stromal cells in vitro [31]. Preliminary results from a phase II study (ClinicalTrials.gov identifier NCT01302886) have been reported [32]. Patients (n 5 25) with treatment-na¨ıve intermediate- and high-risk smoldering MM were enrolled. Patient received 10-mg/kg infusions of BHQ880 every 28 days. No grade 3 or 4 adverse events were reported. Significant adverse events in the study included arthralgia, fatigue, extremity pain, and pyrexia. No antitumor activity was noted in these preliminary results.

STABILIZATION OF DEGRADATION COMPLEX Tankyrase Inhibitors: G244-LM, G007-LK, XAV939, IWR-1, and JW55 Tankyrases act on poly-ADP-ribosylate AXIN proteins, the concentration-limiting component of the b-catenin destruction complex. Inhibitors of tankyrase stabilize AXIN, leading to enhancement of b-catenin destruction. Multiple tankyrase inhibitors have been developed including G244-LM, G007-LK, XAV939, IWR-1, and JW55. G244-LM, G007-LK, and XAV939 showed a decrease in WNT/b-catenin signaling in APC-mutant CRC cell lines [33, 34]. XAV939 and IWR-1 showed growth suppression in both human and murine lung cancer cell lines [35]. These agents are currently in preclinical testing, and phase I trials are being planned.

INTERFERENCE WITH b-CATENIN-DEPENDENT GENE TRANSCRIPTION PRI-724 To generate a transcriptionally active complex, b-catenin recruits transcriptional coactivators, cAMP response element binding (CREB) binding protein (CBP), or p300 after translocation into cell nucleus. PRI-724 (PRISM BioLab, Yokohama Kanagawa, Japan, http://www.prismbiolab.com), a small molecule inhibitor of the binding between b-catenin and CBP, leads to downregulation of genes responsible for symmetric nondifferentiated division. This also leads to a shift to greater b-catenin/p300 cooperativity that results in initiation of differentiation [36]. In preliminary results from phase I testing (ClinicalTrials. gov identifier NCT01302405) [36], 18 patients were given PRI724 over 7 days every 2 weeks, ranging from 40 to 1,280 mg/m2 per day. No maximum tolerated dose was identified in dose escalation. A single DLT in the form of grade 3 hyperbilirubinemia was encountered in a patient given 1,280 mg/m2 per day. Grade 1/2 side effects include diarrhea, hypophosphatemia, reversible elevated bilirubin, nausea, fatigue, anorexia, and thrombocytopenia. No objective responses were seen in this study. Reduction in survivin expression, a b-catenin target gene in circulating tumor cells after treatment with PRI-724, is consistent with a pharmacodynamic effect. Three clinical trials evaluating combinations of PRI-724 are ongoing: (a) phase I/II trial of PRI-724 with dasatinib in advanced myeloid malignancies (ClinicalTrials.gov identifier NCT01606579), (b) phase Ib trial of PRI-724 with gemcitabine for advanced pancreatic adenocarcinoma (ClinicalTrials.gov identifier NCT01764477) and, (c) phase Ib trial of PRI-724 with the mFOLFOX regimen in patients with advanced colon cancer (ClinicalTrials.gov identifier NCT01302405).

CWP232291 CWP232291 (JW Pharmaceutical, Seoul, Republic of Korea, http://www.jw-pharma.co.kr/pharma/en/intro/pharma.jsp) is a small molecule that binds Src associated with mitosis 68K protein (Sam68) and promotes apoptosis through inhibition of the antiapoptotic WNT driven gene survivin. CWP232291 has

OTncologist he

©AlphaMed Press 2015

®

Tai, Wells, Arcaroli et al. shown both in vitro and in vivo antitumor activity in multiple myeloma [37]. Phase I enrollment is under way for patients with acute myeloid leukemia, chronic myelomonocytic leukemia, and myelodysplastic syndrome (ClinicalTrials.gov identifier NCT0139846). Table 2 summarizes the compounds evaluated in early phase trials and preclinical settings.

CHALLENGES AHEAD Although it is clear that dysregulated WNT signaling plays an integral role in cancer pathogenesis, the ubiquitous nature of WNT signaling and its numerous effects significantly complicates WNTsignaling blockade. Although studies agree that that b-catenin mediates cell proliferation and growth in melanoma cell lines [38], its role in metastasis remains unresolved [39–41]. Some studies, for instance, have demonstrated that suppression of b-catenin is associated with disease progression [40, 42]; in contrast, other studies have reported that stabilization of the b-catenin may facilitate a metastatic phenotype in melanoma [41, 43]. In particular, Grossmann et al. showed that WNT5A-dependent b-catenin signaling facilitated metastasis in melanoma [43]. One reason for this discrepancy is that receptor expression may have different effects on signaling [44]. In cases in which ROR2 is the predominant coreceptor,WNT5A signals through FZD2 or FZD5 to degrade b-catenin. When the LRP6 coreceptor is dominant, WNT5A pairs with FZD4/LRP6 and stabilizes b-catenin. Given that opposing results have been described to yield a more metastatic phenotype, further studies are needed to understand the role of b-catenin at enhancing disease progressing in melanoma. The noncanonical WNT pathway has been implicated in metastasis in both pancreatic and castrate-resistant prostate cancers [45–47]; however, noncanonical WNT signaling pathways in cancer are still limited, and many studies have yet to be independently confirmed. It is unclear if aberrations in the WNT pathway are causative of poor clinical outcomes or simply correlative. Future studies will need to better delineate the context-dependent roles of WNT signaling in specific malignancies. Activating mutations, epigenetic events, and autocrine activation frequently coexist within the same tumor type, albeit with varying dependence. It is conceivable that pathway activation from different means would result in varying outcomes. The differing effects on mammary glands, for example, were evaluated using transgenic mice with stable expression of WNT1, MMTV-WNT1 and DN89 b-catenin, respectively. Interestingly, DN89 b-catenin mice induced a lobuloalveolar differentiation with limited ductal branching along the luminal cells, whereas MMTV-WNT1 mice caused mammary tumors with extensive ductal branching primarily affecting basally located cells [48]. Taken together, cellular heterogeneity, dynamic interactions with different nodes of the pathway, and cellular plasticity explain the divergent response and phenotype seen. It is imperative to have a greater understanding of individual tumor biology and to identify predictive biomarkers of efficacy for future clinical trials.

www.TheOncologist.com

1195

Necessary but Not Sufficient Although encouraging single-agent antitumor activity is seen with WNT pathway inhibition in preclinical models, the same has not been recapitulated thus far in early phase clinical trials. Efficacy data from two phase I studies evaluating vantictumab and PRI-724 have been reported [25, 36]. No significant tumor regression was observed in a combined patient population of 41. A plausible explanation is the extensive crosstalk between WNT and other signaling pathways. The cooperativity between WNT and Notch has been implicated in influencing proliferative effects on early intestinal precursors. Importantly, synergistic effects between both signaling pathways resulted in development of colonic adenoma [49]. Mechanistically,membrane-boundNotchbindstoactiveb-catenin in colon cancer cells and negatively regulates post-translational accumulation of active b-catenin. Treatment with a g-secretase inhibitor prevents cleavage of membrane-bound Notch, leading to abrogation of active b-catenin activity [50]. In the adult mouse bronchiolar epithelium,WNT/b-catenin signaling alone does not lead to lung oncogenesis; however, concurrent activation of WNT/b-catenin signaling and expression of constitutively active KRAS (p.G12D) led to a significant increase in overall tumor number and size and a more aggressive tumor phenotype compared with KRAS p.G12D alone [51]. In addition, a hyperactivated WNT pathway has been noted to confer resistance to PI3K/Akt inhibition in preclinical models of colon cancer. In contrast to xenografts derived from colon cancer cells with low concentration of b-catenin, xenografts with high concentration of b-catenin were resistant to PI3K/Akt inhibition. This resistance was reversed by XAV-939, a tankyrase inhibitor, when added to sphere cultures of patient-derived colon cancer cells that were insensitive to PI3K/Akt inhibition [52].

It is unclear if aberrations in the WNT pathway are causative of poor clinical outcomes or simply correlative. Management of Toxicities Hematopoietic, bone, and gastrointestinal toxicities are anticipated with abrogation of WNT signaling due to the importance of this pathway for self-renewal of normal stem/ progenitor cells in these systems. A single dose-limiting toxicity event of nausea and vomiting was reported in the phase I trial of OMP-18R5. Other grade 1/2 adverse events of significance included constitutional and gastrointestinal side effects. Notably, marked increase in b-CTX, serum marker of bone turnover, was observed in a proportion of patients, prompting institution of prophylactic measures. A similar adverse event profile was reported in the phase I trial of OMP-54F28. Although no maximum tolerated dose was identified in the dose-escalation study of PRI-724, a single DLT in the form of grade 3 hyperbilirubinemia was encountered. Other grade 1/2 adverse effects included constitutional, gastrointestinal, reversible cholestasis and thrombocytopenia [36]. Although the WNT-targeted compounds explored thus far have relatively acceptable side effect profiles as single agents, development of WNT inhibitors are ©AlphaMed Press 2015

Targeting the WNT Signaling Pathway

1196

Table 2. Agents in development targeting the WNT pathway Drug name

Mechanism of action

Phase of trial/cancer type

Trial identifier

Anti-RPL29 antibodies

Downregulates the WNT/b-catenin signaling pathway [74] Antibody to DKK1

Phase I/II multiple myeloma

NCT01302886 NCT00741377 NCT01337752

BHQ880

CGP04909 CWP232291 DKN-01 1 paclitaxel DKN-01 1 lenalidomide/ dexamethasone G007-LK; G244-LM ICG-001 IWR-1 JW55 LGK974 OMP-18R5 (anti-Fzd7: vantictumab) OMP-18R5 1 docetaxel OMP-18R5 1 paclitaxel OMP-18R5 1 nab-paclitaxel/ gemcitabine OMP-54F28 OMP-54F28 1 sorafenib

Inhibits interaction of b-catenin and Tcf/Lef Preclinical transcription factors [75] Inhibits b-catenin induced transcription Phase I AML, CMML, MDS Humanized monoclonal antibody against DKK1 Phase I multiple myeloma or advanced solid tumors Humanized monoclonal antibody against DKK1 Phase I; Phase II relapsed or refractory multiple myeloma Inhibits tankyrase leading to Axin Preclinical stabilization [33] Inhibits b-catenin and CREB binding [72] Preclinical Inhibits tankyrase leading to Axin Preclinical stabilization [76] Inhibits tankyrase leading to Axin Preclinical stabilization [34] Prevents palmitoylation of WNT proteins by Phase I melanoma, breast, and Porcupine pancreas neoplasms Antibody against frizzled 7 Phase I advanced solid tumors

NCT01398462 NCT02013154 NCT01711671

NCT01351103 NCT01345201

Antibody against frizzled 7 Antibody against frizzled 7 Antibody against frizzled 7

Phase Ib non-small cell lung cancer NCT01957007 Phase Ib advanced breast cancer NCT01973309 Phase Ib advanced pancreatic cancer NCT02005315

Frizzled 8 decoy receptor Frizzled 8 decoy receptor

Phase I advanced solid tumors Phase Ib advanced hepatocellular carcinoma Phase Ib advanced ovarian cancer

OMP-54F28 1 paclitaxel/ Frizzled 8 decoy receptor carboplatin OMP-54F28 1 nab-paclitaxel/ Frizzled 8 decoy receptor gemcitabine PKF115-584 Inhibits interaction of b-catenin and Tcf/Lef transcription factors [75] PRI-724 Inhibits interaction CREB binding protein with b-catenin PRI-724 Inhibits interaction CREB binding protein with b-catenin PRI-724 1 gemcitabine Inhibits interaction CREB binding protein with b-catenin Rp-8-Br-cAMPS Inhibits Protein Kinase A and blocks PGE2induced b-catenin phosphorylation. Protein kinase A antagonist inhibits b-catenin nuclear translocation, c-Myc and COX-2 expression and tumor promotion in ApcMin/1 mice [77] XAV939 Inhibits tankyrase leading to Axin stabilization [78]

NCT01608867 NCT02069145 NCT02092363

Phase Ib advanced pancreatic cancer NCT02050178 Preclinical Phase Ia solid tumors; phase 1b dose escalation in CRC Phase I; phase II advanced myeloid malignancy Phase Ib advanced or metastatic pancreatic adenocarcinoma Preclinical

NCT01302405 NCT01606579 NCT01764477

Abbreviations: AML, acute myeloid leukemia; CMML, chronic myelomonocytic leukemia; CRC, colorectal cancer; MDS, myelodysplastic syndromes.

likely done in concert with other agents. Adverse events will undoubtedly be more pronounced with combination therapy.

CONCLUSION WNT signaling is frequently dysregulated in cancer and is a valid target in antitumor therapy. Multiple agents are currently being explored in preclinical and early phase clinical settings.

Some of the agents have thus far demonstrated abrogation of the pathway with acceptable toxicities but minimal preliminary antitumor activity as single agents; combination studies are ongoing. Pharmacodynamic analysis of serial tumor biopsies and surrogate normal tissue is ongoing in several studies. Multiple challenges remain including better understanding of this pathway and its relevance to individual tumor types,

OTncologist he

©AlphaMed Press 2015

®

Tai, Wells, Arcaroli et al.

1197

identification of predictive biomarkers to optimize the riskbenefit ratio, and derivation of rational partners for combination.

AUTHOR CONTRIBUTIONS Conception/Design: David Tai, Keith Wells, John Arcaroli, Chad Vanderbilt, Dara L. Aisner, Wells A. Messersmith, Christopher H. Lieu Provision of study material or patients: David Tai, Keith Wells, John Arcaroli, Chad Vanderbilt, Dara L. Aisner, Wells A. Messersmith, Christopher H. Lieu Collection and/or assembly of data: David Tai, Keith Wells, John Arcaroli, Chad Vanderbilt, Dara L. Aisner, Wells A. Messersmith, Christopher H. Lieu Data analysis and interpretation: David Tai, Keith Wells, John Arcaroli, Chad Vanderbilt, Dara L. Aisner, Wells A. Messersmith, Christopher H. Lieu

Manuscript writing: David Tai, Keith Wells, John Arcaroli, Chad Vanderbilt, Dara L. Aisner, Wells A. Messersmith, Christopher H. Lieu Final approval of manuscript: David Tai, Keith Wells, John Arcaroli, Chad Vanderbilt, Dara L. Aisner, Wells A. Messersmith, Christopher H. Lieu

DISCLOSURES Dara L. Aisner: Oxford Oncology, Casdin Capital (C/A), Clovis Oncology (H); Wells A. Messersmith: OncoMed (RF). The other authors indicated no financial relationships. (C/A) Consulting/advisory relationship; (RF) Research funding; (E) Employment; (ET) Expert testimony; (H) Honoraria received; (OI) Ownership interests; (IP) Intellectual property rights/ inventor/patent holder; (SAB) Scientific advisory board

REFERENCES 1. Clevers H. Wnt/b-catenin signaling in development and disease. Cell 2006;127:469–480. 2. De A. Wnt/Ca21 signaling pathway: A brief overview. Acta Biochim Biophys Sin (Shanghai) 2011;43:745–756. 3. Papkoff J, Brown AM, Varmus HE. The int-1 proto-oncogene products are glycoproteins that appear to enter the secretory pathway. Mol Cell Biol 1987;7:3978–3984. 4. Angers S, Moon RT. Proximal events in Wnt signal transduction. Nat Rev Mol Cell Biol 2009;10: 468–477. 5. Kohn AD, Moon RT. Wnt and calcium signaling: Beta-catenin-independent pathways. Cell Calcium 2005;38:439–446. 6. Behrens J, Jerchow B-A, W¨urtele M et al. Functional interaction of an axin homolog, conductin, with b-catenin, APC, and GSK3b. Science 1998;280:596–599. 7. Hart MJ, de los Santos R, Albert IN et al. Downregulation of b-catenin by human Axin and its association with the APC tumor suppressor, b-catenin and GSK3 b. Curr Biol 1998;8:573– 581. 8. Bao R, Christova T, Song S et al. Inhibition of tankyrases induces Axin stabilization and blocks Wnt signalling in breast cancer cells. PLoS One 2012;7: e48670. 9. Jones SE, Jomary C. Secreted Frizzled-related proteins: Searching for relationships and patterns. BioEssays 2002;24:811–820. 10. Malinauskas T, Aricescu AR, Lu W et al. Modular mechanism of Wnt signaling inhibition by Wnt inhibitory factor 1. Nat Struct Mol Biol 2011;18: 886–893. 11. Anastas JN, Moon RT. WNT signalling pathways as therapeutic targets in cancer. Nat Rev Cancer 2013;13:11–26.

17. Lee E, Salic A, Kr¨uger R et al. The roles of APC and Axin derived from experimental and theoretical analysis of the Wnt pathway. PLoS Biol 2003;1:E10.

31. Fulciniti M, Tassone P, Hideshima T et al. AntiDKK1 mAb (BHQ880) as a potential therapeutic agent for multiple myeloma. Blood 2009;114: 371–379.

18. Klarmann GJ, Decker A, Farrar WL. Epigenetic gene silencing in the Wnt pathway in breast cancer. Epigenetics 2008;3:59–63.

32. Munshi NC, Abonour R, Beck JT et al. Early evidence of anabolic bone activity of BHQ880, a fully human anti-DKK1 neutralizing antibody: Results of a phase 2 study in previously untreated patients with smoldering multiple myeloma at risk for progression [abstract 331]. Presented at: ASH annual meeting; December 8–12, 2012; Atlanta, GA.

19. Matsuda Y, Schlange T, Oakeley EJ et al. WNT signaling enhances breast cancer cell motility and blockade of the WNT pathway by sFRP1 suppresses MDA-MB-231 xenograft growth. Breast Cancer Res 2009;11:R32. ´ 20. Valencia A, Rom´an-Gomez J, Cervera J et al. Wnt signaling pathway is epigenetically regulated by methylation of Wnt antagonists in acute myeloid leukemia. Leukemia 2009;23:1658–1666. 21. Minke KS, Staib P, Puetter A et al. Small molecule inhibitors of WNT signaling effectively induce apoptosis in acute myeloid leukemia cells. Eur J Haematol 2009;82:165–175.

34. Waaler J, Machon O, Tumova L et al. A novel tankyrase inhibitor decreases canonical Wnt signaling in colon carcinoma cells and reduces tumor growth in conditional APC mutant mice. Cancer Res 2012;72:2822–2832.

22. Barker N, Clevers H. Mining the Wnt pathway for cancer therapeutics. Nat Rev Drug Discov 2006;5:997–1014.

35. Busch AM, Johnson KC, Stan RV et al. Evidence for tankyrases as antineoplastic targets in lung cancer. BMC Cancer 2013;13:211.

23. Katoh M, Katoh M.WNTsignaling pathway and stem cell signaling network. Clin Cancer Res 2007; 13:4042–4045.

36. El-Khoueiry AB, Ning Y, Yang D et al. A phase I first-in-human study of PRI-724 in patients (pts) with advanced solid tumors. J Clin Oncol 2013;31(suppl): 2501a.

24. Gurney A, Axelrod F, Bond CJ et al. Wnt pathway inhibition via the targeting of Frizzled receptors results in decreased growth and tumorigenicity of human tumors. Proc Natl Acad Sci USA 2012;109:11717–11722. 25. Smith DC, Rosen LS, Chugh R et al. First-inhuman evaluation of the human monoclonal antibody vantictumab (OMP-18r5; anti-Frizzled) targeting the WNT pathway in a phase I study for patients with advanced solid tumors. J Clin Oncol 2013;31(suppl):2540a.

12. Nusse R, van Ooyen A, Cox D et al. Mode of proviral activation of a putative mammary oncogene (int-1) on mouse chromosome 15. Nature 1984;307:131–136.

26. Jimeno A, Gordon M, Chugh R et al. A first-inhuman phase 1 study of anticancer stem cell agent OMP-54f28 (FZD8-Fc), decoy receptor for WNT ligands, in patients with advanced solid tumors. J Clin Oncol 2014;32(suppl):2505a.

13. Morin PJ, Sparks AB, Korinek V et al. Activation of beta-catenin-Tcf signaling in colon cancer by mutations in beta-catenin or APC. Science 1997; 275:1787–1790.

27. Blagodatski A, Poteryaev D, Katanaev VL. Targeting the Wnt pathways for therapies. Mol Cell Ther 2014;2:28.

14. Clements WM, Lowy AM, Groden J. Adenomatous polyposis coli/beta-catenin interaction and downstream targets: Altered gene expression in gastrointestinal tumors. Clin Colorectal Cancer 2003;3:113–120. 15. Liu W, Dong X, Mai M et al. Mutations in AXIN2 cause colorectal cancer with defective mismatch repair by activating b-catenin/TCF signalling. Nat Genet 2000;26:146–147. 16. Salahshor S,Woodgett JR.Thelinks between axin and carcinogenesis. J Clin Pathol 2005;58:225–236.

www.TheOncologist.com

33. Lau T, Chan E, Callow M et al. A novel tankyrase small-molecule inhibitor suppresses APC mutationdriven colorectal tumor growth. Cancer Res 2013; 73:3132–3144.

28. Jiang X, Hao HX, Growney JD et al. Inactivating mutations of RNF43 confer Wnt dependency in pancreatic ductal adenocarcinoma. Proc Natl Acad Sci USA 2013;110:12649–12654.

37. Cha JY, Jung J-E, Lee K-H et al. Anti-tumor activity of novel small molecule Wnt signaling inhibitor, CWP232291, in multiple myeloma [abstract 3038]. Presented at: ASH annual meeting; December 4–7, 2010; Orlando, FL. 38. Goodall J, Martinozzi S, Dexter TJ et al. Brn-2 expression controls melanoma proliferation and is directly regulated by beta-catenin. Mol Cell Biol 2004;24:2915–2922. 39. Arozarena I, Bischof H, Gilby D et al. In melanoma, beta-catenin is a suppressor of invasion. Oncogene 2011;30:4531–4543. 40. Maelandsmo GM, Holm R, Nesland JM et al. Reduced beta-catenin expression in the cytoplasm of advanced-stage superficial spreading malignant melanoma. Clin Cancer Res 2003;9: 3383–3388. 41. Damsky WE, Curley DP, Santhanakrishnan M et al. b-catenin signaling controls metastasis in Brafactivated Pten-deficient melanomas. Cancer Cell 2011;20:741–754.

29. Giannakis M, Hodis E, Jasmine Mu X et al. RNF43 is frequently mutated in colorectal and endometrial cancers. Nat Genet 2014;46:1264–1266.

42. Kageshita T, Hamby CV, Ishihara T et al. Loss of b-catenin expression associated with disease progression in malignant melanoma. Br J Dermatol 2001;145:210–216.

30. Pozzi S, Fulciniti M, Yan H et al. In vivo and in vitro effects of a novel anti-Dkk1 neutralizing antibody in multiple myeloma. Bone 2013;53: 487–496.

43. Grossmann AH, Yoo JH, Clancy J et al.The small GTPase ARF6 stimulates b-catenin transcriptional activity during WNT5A-mediated melanoma invasion and metastasis. Sci Signal 2013;6:ra14.

©AlphaMed Press 2015

Targeting the WNT Signaling Pathway

1198 44. Webster MR,Weeraratna AT. A Wnt-er migration: Theconfusingroleofb-catenininmelanomametastasis. Sci Signal 2013;6:pe11. doi:10.1126/scisignal.2004114 45. Zheng D, Decker KF, Zhou T et al. Role of WNT7B-induced noncanonical pathway in advanced prostate cancer. Mol Cancer Res 2013;11:482–493. 46. Yu M, Ting DT, Stott SL et al. RNA sequencing of pancreatic circulating tumour cells implicates WNT signalling in metastasis. Nature 2012;487:510–513. 47. Lee GT, Kang DI, Ha YS et al. Prostate cancer bone metastases acquire resistance to androgen deprivation via WNT5A-mediated BMP-6 induction. Br J Cancer 2014;110:1634–1644. 48. Imbert A, Eelkema R, Jordan S et al. Delta N89 beta-catenin induces precocious development, differentiation, and neoplasia in mammary gland. J Cell Biol 2001;153:555–568. 49. Fre S, Pallavi SK, Huyghe M et al. Notch and Wnt signals cooperatively control cell proliferation and tumorigenesis in the intestine. Proc Natl Acad Sci USA 2009;106:6309–6314. 50. Kwon C, Cheng P, King IN et al. Notch posttranslationally regulates b-catenin protein in stem and progenitor cells. Nat Cell Biol 2011;13:1244–1251. 51. Pacheco-Pinedo EC, Durham AC, Stewart KM et al. Wnt/b-catenin signaling accelerates mouse lung tumorigenesis by imposing an embryonic distal progenitor phenotype on lung epithelium. J Clin Invest 2011;121:1935–1945. ´ 52. Tenbaum SP, Ordoñez-Mor´ an P, Puig I et al. b-catenin confers resistance to PI3K and AKT inhibitors and subverts FOXO3a to promote metastasis in colon cancer. Nat Med 2012;18:892–901. 53. Laird PW, Jackson-Grusby L, Fazeli A et al. Suppression of intestinal neoplasia by DNA hypomethylation. Cell 1995;81:197–205. 54. Sansom OJ, Berger J, Bishop SM et al. Deficiency of Mbd2 suppresses intestinal tumorigenesis. Nat Genet 2003;34:145–147.

57. Wu Y, Li J, Sun CY et al. Epigenetic inactivation of the canonical Wnt antagonist secreted frizzledrelated protein 1 in hepatocellular carcinoma cells. Neoplasma 2012;59:326–332.

68. Trautmann M, Sievers E, Aretz S et al. SS18-SSX fusion protein-induced Wnt/b-catenin signaling is a therapeutic target in synovial sarcoma. Oncogene 2014;33:5006–5016.

58. Taniguchi H, Yamamoto H, Hirata T et al. Frequent epigenetic inactivation of Wnt inhibitory factor-1 in human gastrointestinal cancers. Oncogene 2005;24:7946–7952.

69. Vijayakumar S, Liu G, Rus IA et al. Highfrequency canonical Wnt activation in multiple sarcoma subtypes drives proliferation through a TCF/b-catenin target gene, CDC25A. Cancer Cell 2011;19:601–612.

59. Goeppert B, Konermann C, Schmidt CR et al. Global alterations of DNA methylation in cholangiocarcinoma target the Wnt signaling pathway. Hepatology 2014;59:544–554. 60. Guo Y, Guo W, Chen Z et al. Hypermethylation and aberrant expression of Wnt-antagonist family genes in gastric cardia adenocarcinoma. Neoplasma 2011;58:110–117. 61. Bj¨orklund P, Svedlund J, Olsson AK et al. The internally truncated LRP5 receptor presents a therapeutic target in breast cancer. PLoS One 2009;4: e4243. 62. Moreno-Bueno G, Hardisson D, S´anchez C et al. Abnormalities of the APC/beta-catenin pathway in endometrial cancer. Oncogene 2002; 21:7981–7990. 63. Delmas AL, Riggs BM, Pardo CE et al. WIF1 is a frequent target for epigenetic silencing in squamous cell carcinoma of the cervix. Carcinogenesis 2011;32:1625–1633. 64. Ford CE, Jary E, Ma SS et al.The Wnt gatekeeper SFRP4 modulates EMT, cell migration and downstream Wnt signalling in serous ovarian cancer cells. PLoS One 2013;8:e54362. 65. Yee DS, Tang Y, Li X et al. The Wnt inhibitory factor 1 restoration in prostate cancer cells was associated with reduced tumor growth, decreased capacity of cell migration and invasion and a reversal of epithelial to mesenchymal transition. Mol Cancer 2010;9:162.

55. Jiang X, Tan J, Li J et al. DACT3 is an epigenetic regulator of Wnt/beta-catenin signaling in colorectal cancer and is a therapeutic target of histone modifications. Cancer Cell 2008;13:529–541.

66. Chow A, Amemiya Y, Sugar L et al. Wholetranscriptome analysis reveals established and novel associations with TMPRSS2:ERG fusion in prostate cancer. Anticancer Res 2012;32: 3629–3641.

56. Mahmoudi T, Boj SF, Hatzis P et al. The leukemia-associated Mllt10/Af10-Dot1l are Tcf4/ b-catenin coactivators essential for intestinal homeostasis. PLoS Biol 2010;8:e1000539.

67. Kim JT, Li J, Jang ER et al. Deregulation of Wnt/ b-catenin signaling through genetic or epigenetic alterations in human neuroendocrine tumors. Carcinogenesis 2013;34:953–961.

70. Biechele TL, Kulikauskas RM, Toroni RA et al. Wnt/b-catenin signaling and AXIN1 regulate apoptosis triggered by inhibition of the mutant kinase BRAFV600E in human melanoma. Sci Signal 2012;5: ra3. 71. Mullighan CG, Zhang J, Kasper LH et al. CREBBP mutations in relapsed acute lymphoblastic leukaemia. Nature 2011;471:235–239. 72. Emami KH, Nguyen C, Ma H et al. A small molecule inhibitor of beta-catenin/CREB-binding protein transcription. [published correction appears in Proc Natl Acad Sci USA 2004;101:16707]. Proc Natl Acad Sci USA 2004;101:12682–12687. 73. Mazieres J, He B, You L et al. Wnt inhibitory factor-1 is silenced by promoter hypermethylation in human lung cancer. Cancer Res 2004;64: 4717–4720. 74. Miyake Y, Matsushita H, Yamamoto K. Anti-60s ribosomal protein l29 antibody: New anticancer agent discovered from human sera. J Clin Oncol 2013;31(suppl):3071a. 75. Lepourcelet M, Chen YN, France DS et al. Small-molecule antagonists of the oncogenic Tcf/ beta-catenin protein complex. Cancer Cell 2004;5: 91–102. 76. Chen B, Dodge ME, Tang W et al. Small molecule-mediated disruption of Wnt-dependent signaling in tissue regeneration and cancer. Nat Chem Biol 2009;5:100–107. 77. Brudvik KW, Paulsen JE, Aandahl EM et al. Protein kinase A antagonist inhibits b-catenin nuclear translocation, c-Myc and COX-2 expression and tumor promotion in Apc(Min/1) mice. Mol Cancer 2011;10:149. 78. Huang SM, Mishina YM, Liu S et al. Tankyrase inhibition stabilizes axin and antagonizes Wnt signalling. Nature 2009;461:614–620.

OTncologist he

©AlphaMed Press 2015

®