Editorial
Molecularly targeted therapies for human hepatocellular carcinoma: Should we start from b-catenin inhibition? Diego F. Calvisi⇑ Institute of Pathology, University of Greifswald, Greifswald, Germany See Article, pages 380-387
Hepatocellular carcinoma (HCC) is one of the most frequent and lethal tumours worldwide, accounting for more than 600,000 deaths annually [1,2]. Curative options for HCC are limited to surgical resection and liver transplantation, which can be applied only to a small subset of patients due to the late diagnosis of the disease [1,2]. Treatments for unresectable HCC remain instead unsatisfactory and of marginal benefit for HCC patients [3]. The only FDA approved drug for HCC is sorafenib, a multikinase inhibitor, whose beneficial effects in terms of survival extension are rather limited in HCC patients [4]. These disappointing effects are presumably the consequences of the compensatory activation of alternative signalling cascades and/or the fact that sorafenib does not target the underlying mechanisms of hepatocarcinogenesis in these patients [4]. Thus, a deeper knowledge of the molecular pathogenesis of HCC is required for the development of new and more effective therapeutic strategies against this deadly disease. Despite the heterogeneous nature of human HCC, some crucial signalling pathways involved in hepatocarcinogenesis have been discovered. Among them, the evolutionary conserved Wnt/bcatenin cascade has emerged as a pivotal player in liver malignant transformation and tumour progression [5,6]. At the core of the latter pathway is the b-catenin (CTNNB1) gene, a component of submembranous plaques of both adherens junctions and desmosomes in mammalian cells. Physiologically, b-catenin is involved in two main functions: intercellular adhesion by association with E-cadherin, and transmission of the proliferative signal of the Wnt pathway [7,8]. In the absence of Wnt activation, the b-catenin protein is rapidly phosphorylated at its NH2terminus by the destruction complex, consisting of AXIN1, APC (adenomatous polyposis coli), GSK-3b (glycogen synthase kinase-3b), and CK1 (casein kinase 1) proteins [7,8]. Once phosphorylated, b-catenin is promptly primed for proteolysis through the ubiquitin/proteasome system. Mutations in members of the destruction complex or alternative mechanisms avoiding b-catenin phosphorylation lead to elevated free pools of b-catenin in
q
DOI of original article: http://dx.doi.org/10.1016/j.jhep.2014.10.021. Address: Institute of Pathology, Universitätsmedizin Greifswald, FriedrichLöffler-Str. 23e, 17489 Greifswald, Germany. Tel.: +49 3834 865719; fax: +49 3834 865704. E-mail address: [email protected]. ⇑
the cytoplasm, which consequently leads to translocation into the nucleus and interaction with transcription factors of the TCF/lymphoid enhancer factor family [7,8]. The newly formed b-catenin/TCF complex triggers the activation of a number of target genes involved in cell proliferation, survival, and migration in a tissue-specific manner [9]. A body of evidence, coming from rodent models and human HCC specimens, indicates an important role of the Wnt/b-catenin pathway in liver cancer. For instance, transgenic mouse models overexpressing either a stable mutant form of b-catenin or a constitutively activated, nonmutated form of b-catenin show signs of hepatomegaly, although they do not develop HCC [10,11]. Also, hepatic ablation of APC in mice leads to HCC development through activation of b-catenin signalling [12]. In addition, overexpression of mutant b-catenin cooperates with activated Ha-Ras and AKT1 or with the inactivated Sprouty homolog 2 (SPRY2) protein to induce liver tumour development in mice [13]. In human HCC, the Wnt/b-catenin cascade is activated in a relatively large subset of tumours, ranging from 15% to 45%, via either mutations in the b-catenin gene or alternative molecular mechanisms [5,14]. Taken together, these findings indicate that b-catenin might represent an attractive target in human liver cancer. To further substantiate the importance of b-catenin inhibition as a therapeutic modality for human HCC, Delgado et al. have determined the effect of suppressing mutant b-catenin in vivo [15]. For this purpose, the authors used a mouse model of liver cancer, driven by diethylnitrosamine and phenobarbital (DEN/ PB) administration and characterized by the development of liver tumours with a high rate (90%) of b-catenin mutations [16]. In this model, b-catenin locked nucleic acid (LNA) antisense treatment was employed, starting 7 months after initiation of the PB diet, when liver tumours are already present in DEN/PB-initiated mice. LNA oligonucleotides were injected every 48 h intraperitoneally at the dose of 15 mg/kg for 10 times [15]. Of note, while several glutamine synthase (a b-catenin specific target gene in the liver) positive tumour nodules were observed in the livers of DEN/PB mice, either untreated or treated with a scrambled control, administration of LNA, targeted against b-catenin, resulted in the disappearance of microscopic liver tumour nodules in mice, thus demonstrating a striking therapeutic effect of b-catenin suppression in this model [15]. The complete response to LNA treatment was further underscored in these mice by the serum
Journal of Hepatology 2015 vol. 62 j 257–259
Editorial decrease of leukocyte cell-derived chemotaxin 2 (LECT2), a validate biomarker of b-catenin signalling in mice [17]. At the cellular level, regression of b-catenin-positive tumours was paralleled by a decrease in cell proliferation and apoptosis induction of malignant hepatocytes. Subsequently, the authors investigated whether b-catenin inhibition could affect tumour growth in the DEN mouse HCC model [16], in which hepatocarcinogenesis is driven by Ha-Ras or B-Raf mutations and b-catenin is not activated. Strikingly, LNA directed against b-catenin did not affect tumour occurrence in this mouse model, implying the therapeutic efficacy of b-catenin suppression only in liver tumours with active b-catenin signalling (Fig. 1). In summary, the intriguing study by Delgado et al. shows for the first time that b-catenin is a druggable target in an in vivo mouse model of liver cancer. This observation has seminal implications for the therapy of human HCC. On the one hand, it strongly supports the hypothesis that therapeutic approaches, aimed at suppressing b-catenin activity, might be highly beneficial for the treatment of human liver cancer. On the other hand, the authors found that b-catenin suppression could be an effective anti-tumour strategy exclusively in HCC subsets in which the Wnt/b-catenin pathway plays a predominant role, while being ineffective in b-catenin-negative tumours. These data are in accordance with recent findings, showing that treatments with the multikinase inhibitor sorafenib or the c-Met inhibitor tivantinib are beneficial primarily in HCC cases with specific molecular signatures [18,19]. Furthermore, findings in the DEN/PB mouse models might help to explain the unsatisfactory results of recent clinical trials, such as the STORM and the EVOLVE-1 trial. The STORM trial was designed to evaluate the efficacy and safety of sorafenib treatment vs. placebo in the adjuvant treatment of HCC after potentially curative treatments (clinicalTrials.gov; identifier: NCT00692770), whereas the EVOLVE-1 trial was aimed at evaluating the efficacy of the rapamycin homolog everolimus in HCC patients in which sorafenib was either ineffective or not
A
B
DEN only
Anti-β-catenin LNA
DEN/PB
β-catenin+ liver tumors
properly tolerated [20]. It is highly likely that the failure of these therapeutic approaches resides, at least partly, in the inclusion of HCC cases into the trial that did not harbour the ‘‘appropriate’’ molecular alterations. Although the study by Delgado et al. has significantly improved our knowledge on the impact of b-catenin suppression in HCC development, many important questions on this topic remain to be addressed. For instance, while hepatocarcinogenesis in the DEN/PB model is addicted to b-catenin signalling, human b-catenin-positive HCCs are presumably characterized by heterogeneous molecular features, which might provide at least partial resistance to the anti-tumour effect of b-catenin depletion via compensatory activation of alternative oncogenic pathways. To clarify the latter issue, the treatment with specific LNA against b-catenin should be employed in mouse models in which activation of the b-catenin signalling is associated with other molecular alterations frequently occurring in human HCC, such as activation of the AKT or c-Met pathways or inactivation of the SPRY2 tumour suppressor gene. Mouse models harbouring these molecular features are already available [14], and might be of high help to determine whether the presence of additional oncogenic alterations is able to override the anti-neoplastic activity following b-catenin suppression. Furthermore, these or similar mouse models might be useful to evaluate the effectiveness of treatments in which b-catenin inhibition is coupled to other therapeutic approaches. Another crucial point that requires caution and must be fully addressed before b-catenin inhibition is established as a therapeutic strategy against human liver cancer is the consequence of b-catenin suppression in HCC patients in terms of potentially fatal side effects. Indeed, as b-catenin is vital to adherens junctions, its inhibition might be deleterious for patient survival. However, both in vitro and in vivo studies have shown that b-catenin loss is compensated by upregulation of c-catenin [6], suggesting that suppression of b-catenin might be well tolerated by patients.
Liver tumor regression & disappearance
Ha-ras+ or B-raf+ liver tumors
Anti-β-catenin LNA
No inhibition of liver tumor development
Fig. 1. Schematic representation of the protocol employed by Delgado et al. [15]. (A) Six-week old C3H/He male mice were injected intraperitoneally with the potent hepatocarcinogen diethylnitrosamine, followed 3 weeks later by initiation of a diet containing 0.05% phenobarbital (DEN/PB). These mice developed liver tumours harbouring b-catenin mutations (b-catenin+ liver tumours). Of note, liver tumour development was completely suppressed by treatment with locked nucleic acid (LNA; red blunted arrow) against b-catenin in these mice. (B) A second group of C3H/He male mice was subjected to the administration of DEN only. These mice developed liver tumours harbouring Ha-Ras or B-Raf mutations (Ha-Ras+ or B-Raf+ liver tumours) but not b-catenin mutations. In these mice, tumour development was unaffected by administration of LNA against b-catenin.
258
Journal of Hepatology 2015 vol. 62 j 257–259
JOURNAL OF HEPATOLOGY Finally, to optimize the effectiveness of anti-b-catenin targeted therapies in human HCC, reliable biomarkers, able to predict the patient’s response to a given drug, should be identified. In this regard, serum LECT2 has been recently envisioned has a reliable biomarker of b-catenin signalling activity in mice but not in humans [17]. Thus, additional studies, using large-scale genomic and proteomic approaches are needed to identify relevant biomarker(s) for effective targeted therapies in b-cateninpositive tumours. As b-catenin targets are tissue-specific, such large-scale studies will also be extremely helpful to discover the crucial effectors of b-catenin in the liver.
Conflict of interest The author declared that he does not have anything to disclose regarding funding or conflict of interest with respect to this manuscript. References [1] Jemal A, Bray F, Center MM, Ferlay J, Ward E, Forman D. Global cancer statistics. CA Cancer J Clin 2011;61:69–90. [2] Forner A, Llovet JM, Bruix J. Hepatocellular carcinoma. Lancet 2012;379: 1245–1255. [3] European Association for the Study of the Liver. EOfRaToC. EASL—EORTC Clinical Practice Guidelines: management of hepatocellular carcinoma. J Hepatol 2012;56:908–943. [4] Wrzesinski SH, Taddei TH, Strazzabosco M. Systemic therapy in hepatocellular carcinoma. Clin Liver Dis 2011;15:423–441. [5] de La Coste A, Romagnolo B, Billuart P, Renard CA, Buendia MA, Soubrane O, et al. Somatic mutations of the b-catenin gene are frequent in mouse and human hepatocellular carcinomas. Proc Natl Acad Sci U S A 1998;85: 8847–8851. [6] Nejak-Bowen KN, Monga SPS. Beta-catenin signaling, liver regeneration and hepatocellular cancer: sorting the good from the bad. Semin Cancer Biol 2011;21:44–58.
[7] Polakis P. The oncogenic activation of beta-catenin. Curr Opin Genet Dev 1999;9:15–21. [8] Gumbiner BM. Signal transduction by b-catenin. Curr Opin Cell Biol 1995;7:634–640. [9] Clevers H, Van de Wetering M. TCF/LEF factors earns their wings. Trends Genet 1997;13:485–489. [10] Cadoret A, Ovejero C, Saadi-Kheddouci S, Souil E, Fabre M, Romagnolo B, et al. Hepatomegaly in transgenic mice expressing an oncogenic form of beta-catenin. Cancer Res 2001;61:3245–3249. [11] Harada N, Oshima H, Katoh M, Tamai Y, Oshima M, Taketo MM. Hepatocarcinogenesis in mice with beta-catenin and Ha-ras gene mutations. Cancer Res 2004;64:48–54. [12] Colnot S, Decaens T, Niwa-Kawakita M, Godard C, Hamard G, Kahn A, et al. Livertargeted disruption of Apc in mice activates beta-catenin signaling and leads to hepatocellular carcinomas. Proc Natl Acad Sci U S A 2004;101:17216–17221. [13] Chen X, Calvisi DF. Hydrodynamic transfection for generation of novel mouse models for liver cancer research. Am J Pathol 2014;184:912–923. [14] Laurent-Puig P, Legoix P, Bluteau O, Belghiti J, Franco D, Binot F, et al. Genetic alterations associated with hepatocellular carcinomas define distinct pathways of hepatocarcinogenesis. Gastroenterology 2001;120:1763–1773. [15] Delgado E, Okabe H, Preziosi M, Russell JO, Feliciano Alvarado T, Oertel M, et al. Complete response of CTNNB1-mutated tumors to beta-catenin suppression by locked nucleic antisense in mouse hepatocarcinogenesis model. J Hepatol 2015;62:380–387. [16] Loeppen S, Schneider D, Gaunitz F, Gebhardt R, Kurek R, Buchmann A, et al. Overexpression of glutamine synthetase is associated with beta-cateninmutations in mouse liver tumors during promotion of hepatocarcinogenesis by phenobarbital. Cancer Res 2002;62:5685–5688. [17] Okabe H, Delgado E, Lee JM, Yang J, Kinoshita H, Hayashi H, et al. Role of leukocyte cell-derived chemotaxin 2 as a biomarker in hepatocellular carcinoma. PLoS One 2014;9:e98817. [18] Horwitz E, Stein I, Andreozzi M, Nemeth J, Shoham A, Pappo O, et al. Human and mouse VEGFA-amplified hepatocellular carcinomas are highly sensitive to sorafenib treatment. Cancer Discov 2014;4:730–743. [19] Santoro A, Rimassa L, Borbath I, Daniele B, Salvagni S, Van Laethem JL, et al. Tivantinib for second-line treatment of advanced hepatocellular carcinoma: a randomised, placebo-controlled phase 2 study. Lancet Oncol 2013;14: 55–63. [20] Zhu AX, Kudo M, Assenat E, Cattan S, Kang YK, Lim HY, et al. Effect of everolimus on survival in advanced hepatocellular carcinoma after failure of sorafenib: the EVOLVE-1 randomized clinical trial. JAMA 2014;312:57–67.
Journal of Hepatology 2015 vol. 62 j 257–259
259
Molecularly targeted therapies for human hepatocellular carcinoma: Should we start from b-catenin inhibition? Diego F. Calvisi⇑ Institute of Pathology, University of Greifswald, Greifswald, Germany See Article, pages 380-387
Hepatocellular carcinoma (HCC) is one of the most frequent and lethal tumours worldwide, accounting for more than 600,000 deaths annually [1,2]. Curative options for HCC are limited to surgical resection and liver transplantation, which can be applied only to a small subset of patients due to the late diagnosis of the disease [1,2]. Treatments for unresectable HCC remain instead unsatisfactory and of marginal benefit for HCC patients [3]. The only FDA approved drug for HCC is sorafenib, a multikinase inhibitor, whose beneficial effects in terms of survival extension are rather limited in HCC patients [4]. These disappointing effects are presumably the consequences of the compensatory activation of alternative signalling cascades and/or the fact that sorafenib does not target the underlying mechanisms of hepatocarcinogenesis in these patients [4]. Thus, a deeper knowledge of the molecular pathogenesis of HCC is required for the development of new and more effective therapeutic strategies against this deadly disease. Despite the heterogeneous nature of human HCC, some crucial signalling pathways involved in hepatocarcinogenesis have been discovered. Among them, the evolutionary conserved Wnt/bcatenin cascade has emerged as a pivotal player in liver malignant transformation and tumour progression [5,6]. At the core of the latter pathway is the b-catenin (CTNNB1) gene, a component of submembranous plaques of both adherens junctions and desmosomes in mammalian cells. Physiologically, b-catenin is involved in two main functions: intercellular adhesion by association with E-cadherin, and transmission of the proliferative signal of the Wnt pathway [7,8]. In the absence of Wnt activation, the b-catenin protein is rapidly phosphorylated at its NH2terminus by the destruction complex, consisting of AXIN1, APC (adenomatous polyposis coli), GSK-3b (glycogen synthase kinase-3b), and CK1 (casein kinase 1) proteins [7,8]. Once phosphorylated, b-catenin is promptly primed for proteolysis through the ubiquitin/proteasome system. Mutations in members of the destruction complex or alternative mechanisms avoiding b-catenin phosphorylation lead to elevated free pools of b-catenin in
q
DOI of original article: http://dx.doi.org/10.1016/j.jhep.2014.10.021. Address: Institute of Pathology, Universitätsmedizin Greifswald, FriedrichLöffler-Str. 23e, 17489 Greifswald, Germany. Tel.: +49 3834 865719; fax: +49 3834 865704. E-mail address: [email protected]. ⇑
the cytoplasm, which consequently leads to translocation into the nucleus and interaction with transcription factors of the TCF/lymphoid enhancer factor family [7,8]. The newly formed b-catenin/TCF complex triggers the activation of a number of target genes involved in cell proliferation, survival, and migration in a tissue-specific manner [9]. A body of evidence, coming from rodent models and human HCC specimens, indicates an important role of the Wnt/b-catenin pathway in liver cancer. For instance, transgenic mouse models overexpressing either a stable mutant form of b-catenin or a constitutively activated, nonmutated form of b-catenin show signs of hepatomegaly, although they do not develop HCC [10,11]. Also, hepatic ablation of APC in mice leads to HCC development through activation of b-catenin signalling [12]. In addition, overexpression of mutant b-catenin cooperates with activated Ha-Ras and AKT1 or with the inactivated Sprouty homolog 2 (SPRY2) protein to induce liver tumour development in mice [13]. In human HCC, the Wnt/b-catenin cascade is activated in a relatively large subset of tumours, ranging from 15% to 45%, via either mutations in the b-catenin gene or alternative molecular mechanisms [5,14]. Taken together, these findings indicate that b-catenin might represent an attractive target in human liver cancer. To further substantiate the importance of b-catenin inhibition as a therapeutic modality for human HCC, Delgado et al. have determined the effect of suppressing mutant b-catenin in vivo [15]. For this purpose, the authors used a mouse model of liver cancer, driven by diethylnitrosamine and phenobarbital (DEN/ PB) administration and characterized by the development of liver tumours with a high rate (90%) of b-catenin mutations [16]. In this model, b-catenin locked nucleic acid (LNA) antisense treatment was employed, starting 7 months after initiation of the PB diet, when liver tumours are already present in DEN/PB-initiated mice. LNA oligonucleotides were injected every 48 h intraperitoneally at the dose of 15 mg/kg for 10 times [15]. Of note, while several glutamine synthase (a b-catenin specific target gene in the liver) positive tumour nodules were observed in the livers of DEN/PB mice, either untreated or treated with a scrambled control, administration of LNA, targeted against b-catenin, resulted in the disappearance of microscopic liver tumour nodules in mice, thus demonstrating a striking therapeutic effect of b-catenin suppression in this model [15]. The complete response to LNA treatment was further underscored in these mice by the serum
Journal of Hepatology 2015 vol. 62 j 257–259
Editorial decrease of leukocyte cell-derived chemotaxin 2 (LECT2), a validate biomarker of b-catenin signalling in mice [17]. At the cellular level, regression of b-catenin-positive tumours was paralleled by a decrease in cell proliferation and apoptosis induction of malignant hepatocytes. Subsequently, the authors investigated whether b-catenin inhibition could affect tumour growth in the DEN mouse HCC model [16], in which hepatocarcinogenesis is driven by Ha-Ras or B-Raf mutations and b-catenin is not activated. Strikingly, LNA directed against b-catenin did not affect tumour occurrence in this mouse model, implying the therapeutic efficacy of b-catenin suppression only in liver tumours with active b-catenin signalling (Fig. 1). In summary, the intriguing study by Delgado et al. shows for the first time that b-catenin is a druggable target in an in vivo mouse model of liver cancer. This observation has seminal implications for the therapy of human HCC. On the one hand, it strongly supports the hypothesis that therapeutic approaches, aimed at suppressing b-catenin activity, might be highly beneficial for the treatment of human liver cancer. On the other hand, the authors found that b-catenin suppression could be an effective anti-tumour strategy exclusively in HCC subsets in which the Wnt/b-catenin pathway plays a predominant role, while being ineffective in b-catenin-negative tumours. These data are in accordance with recent findings, showing that treatments with the multikinase inhibitor sorafenib or the c-Met inhibitor tivantinib are beneficial primarily in HCC cases with specific molecular signatures [18,19]. Furthermore, findings in the DEN/PB mouse models might help to explain the unsatisfactory results of recent clinical trials, such as the STORM and the EVOLVE-1 trial. The STORM trial was designed to evaluate the efficacy and safety of sorafenib treatment vs. placebo in the adjuvant treatment of HCC after potentially curative treatments (clinicalTrials.gov; identifier: NCT00692770), whereas the EVOLVE-1 trial was aimed at evaluating the efficacy of the rapamycin homolog everolimus in HCC patients in which sorafenib was either ineffective or not
A
B
DEN only
Anti-β-catenin LNA
DEN/PB
β-catenin+ liver tumors
properly tolerated [20]. It is highly likely that the failure of these therapeutic approaches resides, at least partly, in the inclusion of HCC cases into the trial that did not harbour the ‘‘appropriate’’ molecular alterations. Although the study by Delgado et al. has significantly improved our knowledge on the impact of b-catenin suppression in HCC development, many important questions on this topic remain to be addressed. For instance, while hepatocarcinogenesis in the DEN/PB model is addicted to b-catenin signalling, human b-catenin-positive HCCs are presumably characterized by heterogeneous molecular features, which might provide at least partial resistance to the anti-tumour effect of b-catenin depletion via compensatory activation of alternative oncogenic pathways. To clarify the latter issue, the treatment with specific LNA against b-catenin should be employed in mouse models in which activation of the b-catenin signalling is associated with other molecular alterations frequently occurring in human HCC, such as activation of the AKT or c-Met pathways or inactivation of the SPRY2 tumour suppressor gene. Mouse models harbouring these molecular features are already available [14], and might be of high help to determine whether the presence of additional oncogenic alterations is able to override the anti-neoplastic activity following b-catenin suppression. Furthermore, these or similar mouse models might be useful to evaluate the effectiveness of treatments in which b-catenin inhibition is coupled to other therapeutic approaches. Another crucial point that requires caution and must be fully addressed before b-catenin inhibition is established as a therapeutic strategy against human liver cancer is the consequence of b-catenin suppression in HCC patients in terms of potentially fatal side effects. Indeed, as b-catenin is vital to adherens junctions, its inhibition might be deleterious for patient survival. However, both in vitro and in vivo studies have shown that b-catenin loss is compensated by upregulation of c-catenin [6], suggesting that suppression of b-catenin might be well tolerated by patients.
Liver tumor regression & disappearance
Ha-ras+ or B-raf+ liver tumors
Anti-β-catenin LNA
No inhibition of liver tumor development
Fig. 1. Schematic representation of the protocol employed by Delgado et al. [15]. (A) Six-week old C3H/He male mice were injected intraperitoneally with the potent hepatocarcinogen diethylnitrosamine, followed 3 weeks later by initiation of a diet containing 0.05% phenobarbital (DEN/PB). These mice developed liver tumours harbouring b-catenin mutations (b-catenin+ liver tumours). Of note, liver tumour development was completely suppressed by treatment with locked nucleic acid (LNA; red blunted arrow) against b-catenin in these mice. (B) A second group of C3H/He male mice was subjected to the administration of DEN only. These mice developed liver tumours harbouring Ha-Ras or B-Raf mutations (Ha-Ras+ or B-Raf+ liver tumours) but not b-catenin mutations. In these mice, tumour development was unaffected by administration of LNA against b-catenin.
258
Journal of Hepatology 2015 vol. 62 j 257–259
JOURNAL OF HEPATOLOGY Finally, to optimize the effectiveness of anti-b-catenin targeted therapies in human HCC, reliable biomarkers, able to predict the patient’s response to a given drug, should be identified. In this regard, serum LECT2 has been recently envisioned has a reliable biomarker of b-catenin signalling activity in mice but not in humans [17]. Thus, additional studies, using large-scale genomic and proteomic approaches are needed to identify relevant biomarker(s) for effective targeted therapies in b-cateninpositive tumours. As b-catenin targets are tissue-specific, such large-scale studies will also be extremely helpful to discover the crucial effectors of b-catenin in the liver.
Conflict of interest The author declared that he does not have anything to disclose regarding funding or conflict of interest with respect to this manuscript. References [1] Jemal A, Bray F, Center MM, Ferlay J, Ward E, Forman D. Global cancer statistics. CA Cancer J Clin 2011;61:69–90. [2] Forner A, Llovet JM, Bruix J. Hepatocellular carcinoma. Lancet 2012;379: 1245–1255. [3] European Association for the Study of the Liver. EOfRaToC. EASL—EORTC Clinical Practice Guidelines: management of hepatocellular carcinoma. J Hepatol 2012;56:908–943. [4] Wrzesinski SH, Taddei TH, Strazzabosco M. Systemic therapy in hepatocellular carcinoma. Clin Liver Dis 2011;15:423–441. [5] de La Coste A, Romagnolo B, Billuart P, Renard CA, Buendia MA, Soubrane O, et al. Somatic mutations of the b-catenin gene are frequent in mouse and human hepatocellular carcinomas. Proc Natl Acad Sci U S A 1998;85: 8847–8851. [6] Nejak-Bowen KN, Monga SPS. Beta-catenin signaling, liver regeneration and hepatocellular cancer: sorting the good from the bad. Semin Cancer Biol 2011;21:44–58.
[7] Polakis P. The oncogenic activation of beta-catenin. Curr Opin Genet Dev 1999;9:15–21. [8] Gumbiner BM. Signal transduction by b-catenin. Curr Opin Cell Biol 1995;7:634–640. [9] Clevers H, Van de Wetering M. TCF/LEF factors earns their wings. Trends Genet 1997;13:485–489. [10] Cadoret A, Ovejero C, Saadi-Kheddouci S, Souil E, Fabre M, Romagnolo B, et al. Hepatomegaly in transgenic mice expressing an oncogenic form of beta-catenin. Cancer Res 2001;61:3245–3249. [11] Harada N, Oshima H, Katoh M, Tamai Y, Oshima M, Taketo MM. Hepatocarcinogenesis in mice with beta-catenin and Ha-ras gene mutations. Cancer Res 2004;64:48–54. [12] Colnot S, Decaens T, Niwa-Kawakita M, Godard C, Hamard G, Kahn A, et al. Livertargeted disruption of Apc in mice activates beta-catenin signaling and leads to hepatocellular carcinomas. Proc Natl Acad Sci U S A 2004;101:17216–17221. [13] Chen X, Calvisi DF. Hydrodynamic transfection for generation of novel mouse models for liver cancer research. Am J Pathol 2014;184:912–923. [14] Laurent-Puig P, Legoix P, Bluteau O, Belghiti J, Franco D, Binot F, et al. Genetic alterations associated with hepatocellular carcinomas define distinct pathways of hepatocarcinogenesis. Gastroenterology 2001;120:1763–1773. [15] Delgado E, Okabe H, Preziosi M, Russell JO, Feliciano Alvarado T, Oertel M, et al. Complete response of CTNNB1-mutated tumors to beta-catenin suppression by locked nucleic antisense in mouse hepatocarcinogenesis model. J Hepatol 2015;62:380–387. [16] Loeppen S, Schneider D, Gaunitz F, Gebhardt R, Kurek R, Buchmann A, et al. Overexpression of glutamine synthetase is associated with beta-cateninmutations in mouse liver tumors during promotion of hepatocarcinogenesis by phenobarbital. Cancer Res 2002;62:5685–5688. [17] Okabe H, Delgado E, Lee JM, Yang J, Kinoshita H, Hayashi H, et al. Role of leukocyte cell-derived chemotaxin 2 as a biomarker in hepatocellular carcinoma. PLoS One 2014;9:e98817. [18] Horwitz E, Stein I, Andreozzi M, Nemeth J, Shoham A, Pappo O, et al. Human and mouse VEGFA-amplified hepatocellular carcinomas are highly sensitive to sorafenib treatment. Cancer Discov 2014;4:730–743. [19] Santoro A, Rimassa L, Borbath I, Daniele B, Salvagni S, Van Laethem JL, et al. Tivantinib for second-line treatment of advanced hepatocellular carcinoma: a randomised, placebo-controlled phase 2 study. Lancet Oncol 2013;14: 55–63. [20] Zhu AX, Kudo M, Assenat E, Cattan S, Kang YK, Lim HY, et al. Effect of everolimus on survival in advanced hepatocellular carcinoma after failure of sorafenib: the EVOLVE-1 randomized clinical trial. JAMA 2014;312:57–67.
Journal of Hepatology 2015 vol. 62 j 257–259
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