ONCOLOGY LETTERS 14: 3207-3214, 2017

Expression of miR-146a in patients with ovarian cancer and its clinical significance MIŁOSZ WILCZYŃSKI1, EWELINA ŻYTKO2, BOŻENA SZYMAŃSKA3, MONIKA DZIENIECKA4, MAREK NOWAK2, JUSTYNA DANIELSKA5, GRZEGORZ STACHOWIAK2 and JACEK R. WILCZYŃSKI2 Departments of 1Operative Gynecology, Endoscopy and Gynecologic Oncology, and 2Gynecology and Oncological Gynecology, Polish Mother's Memorial Hospital Research Institute, 93‑338 Lodz; 3 Central Scientific Laboratory CoreLab, Medical University of Lodz, 92‑215 Lodz; 4 Department of Pathology, Polish Mother's Memorial Hospital Research Institute, 93‑388 Lodz; 5 Radiotherapy Department, Medical University of Lodz, 93‑509 Lodz, Poland Received October 14, 2016; Accepted April 7, 2017 DOI: 10.3892/ol.2017.6477 Abstract. The aim of the present retrospective study was to compare microRNA (miR)‑146a expression levels in primary tumors and omental metastases of 48 patients, who had undergone surgery for advanced ovarian serous cancer. Possible correlations between miR‑146a expression level and clinicopathological features were investigated, including chemosensitivity and survival. miR‑146a was evaluated in formalin‑fixed, paraffin‑embedded samples. miR‑146a expression level in primary tumors was demonstrated to be increased in comparison with normal ovary tissues (P=0.02) and metastases (P=0.01). A negative correlation was demonstrated between miR‑146a expression in primary tumors and serum levels of cancer antigen 125 (R=‑0.37; P=0.03) and Risk of Malignancy Algorithm index (R=‑0.79; P=0.0007). Overall survival positively correlated with miR‑146a expression in primary tumor tissue samples (R=0.38; P=0.01). Probability of survival was decreased in patients with low miR‑146a expression levels in primary tumor tissues (hazard ratio=0.21; P=0.003). Lower levels of miR‑146a in primary tumor tissue samples were correlated with a shorter progression‑free

Correspondence to: Dr Miłosz Wilczyński, Department of Operative Gynecology, Endoscopy and Gynecologic Oncology, Polish Mother's Memorial Hospital Research Institute, 281/289 Rzgowska Street, 93‑338 Lodz, Poland E‑mail: [email protected]

Abbreviations: Tregs, T regulatory cells; NFκ B, nuclear factor‑κ B; RANTES, regulated on activation, normal T‑cell expressed and secreted; CXCR4‑C‑X‑C; chemokine receptor type 4; FIGO, International Federation of Gynecology and Obstetrics; CA125, cancer antigen 125; HE4, serum human epidydimis antigen‑4; FFPE, formalin‑fixed, paraffin‑embedded; PFS, progression‑free survival; OS, overall survival; AUC, area under the curve

Key words: microRNA‑146a, ovarian cancer, cancer antigen 125, risk of malignancy algorithm, survival, chemoresistance

survival (P=0.04) and platinum‑resistance of metastases (P=0.006). In conclusion, miR‑146a may be a prognostic marker for serous ovarian cancer. Introduction Ovarian cancer is one of the most fatal types of female neoplasms. Despite the availability of extensive management of the disease, the number of patients who survive ≥5 years following diagnosis remains low (1). Ultra‑radical surgery, platinum‑ and taxane‑based chemotherapy and immunotherapy are all improvements. However, the impact of these treatments on overall survival (OS) remains unsatisfactory (2). One of the main concerns is the low efficacy of chemotherapy due to the primary tumor platinum‑refractoriness or acquired chemoresistance during the course of adjuvant treatment (3). It is not possible to predict which patients, subject to standard chemotherapeutic regimen, would respond to the therapy. Inefficient response to the treatment leads to tumor progression or recurrence. Therefore, identification of markers for potentially chemoinsensitive tumors may aid in modifying and individualizing treatments prior to the recognition of chemorefractoriness or chemoresistance. MicroRNAs (miRNA/miR), small non‑coding RNAs involved in post‑transcriptional gene regulation, may be candidates for potential markers (4). miR‑146a has been described as a modulator of differentiation and function of innate and adaptive immunity. In human T cells, miR‑146a is expressed abundantly in memory T cells, and its expression is critical for function of T regulatory cells (Tregs). miR‑146a was also demonstrated to upregulate the macrophage inflammatory response (5,6). The molecular function of miR‑146a in the immune response involves negative regulation of the signal transduction pathway, which leads to activation of nuclear factor‑κ B (NFκ B), disruption of downstream T lymphocyte receptor‑4 signaling pathway, and modulation of chemokine interleukin‑8, RANTES (regulated on activation, normal T‑cell expressed and secreted) and CXC chemokine receptor type 4 expression (6). The association between miR‑146a and the immune response may have a potential impact in solid tumors.

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Furthermore, it was demonstrated that miR‑146a is involved in the regulation of various RNAs encoding a number of proteins involved in cell differentiation, proliferation and migration (7). Consequently, aberrant disturbed miR‑146a expression level was observed in numerous types of malignancies, including thyroid, breast, gastric, prostate, pancreatic and ovarian cancer (8‑10). miR‑146a polymorphism may increase the risk of developing various types of cancer. For example, the G/C polymorphism in the pre‑miR‑146a sequence was associated with a decrease or an increase of miRNA‑146a expression levels, depending on the cancer type. The change in miRNA‑146a expression modified the risk of papillary thyroid, hepatocellular, gastric cancer and glioma (6,8,9). The G/C polymorphism (SNP no. rs2910164) may induce the onset of breast and ovarian cancers in breast cancer 1/2 (BRCA1/2) positive cases (11). The level of miR‑146a expression may depend on the type of tumor and the aggressiveness of the tumor. Increased expression levels of miR‑146a were reported in papillary thyroid and cervical cancer compared with normal tissues (12,13). However, in highly metastatic breast cancer cell lines, the expression of miR‑146a was downregulated and exogenous miR‑146a expression impaired the invasion and migratory capacity of cancer cells. Breast cancer metastasis suppressor‑1, which affects multiple steps of the metastasizing process, may partially function by upregulating miR‑146a expression in breast cancer cells (14). A study by Boldin et al investigating miR‑146a‑knock‑out mice confirmed human studies and demonstrated that the lack of miR‑146a expression favors development of hematologic neoplasms (15). Chang et al (16) suggested that downregulation of miR‑146a may contribute to the Myc‑mediated tumorigenesis. These observations strongly suggested that miR‑146a may serve a role as a tumor suppressor. Various miRs were revealed to be either upregulated or downregulated in patients with ovarian cancer (17,18). The expression of miR‑30a‑3p was increased in well‑differentiated tumors compared with poorly differentiated tumors (19). Detection of high levels of plasma miR‑205 and low Let‑7f expression levels combined with high serum cancer antigen 125 (CA125) levels improved the accuracy of ovarian cancer detection (20). Let‑7f was identified as a predictive factor for ovarian cancer prognosis (20). A predictive model based on the serum expression levels of miR‑200b/miR‑200c was able to discriminate between normal controls and age‑matched patients with high‑grade serous ovarian cancer (21). A number of other miRs were studied, and the levels of these miRs were correlated with the hazard ratio for patient survival or tumor recurrence (22). In vitro and in vivo studies have suggested that the pattern of miR expression may have an impact on the chemosensitivity of ovarian tumors (23‑26). Vang et al (27) performed a study on a small group of patients with advanced ovarian serous cancer: The study revealed dysregulation of miR‑146a and miR‑150 in omental metastases and suggested their possible role in increased platinum tolerance (27). The aim of this retrospective study was to compare expression levels of miR‑146a in primary tumor tissues and omental metastases from patients who underwent surgery for advanced ovarian serous cancer. The second aim of the present study

was to investigate an association between miR‑146a expression levels and clinicopathological features, including chemosensitivity and survival. Materials and methods Patient collection. The present study was approved by the Ethics Committee of the Polish Mother's Memorial Hospital Research Institute (Lodz, Poland; grant no. 37/2014). Written informed consent was obtained from all patients prior to enrolment in the present study. A total of 48 patients with advanced ovarian cancer, who underwent cytoreductive abdominal surgery between March 2006 and December 2010, were included in the present study. The inclusion criteria were serous tumor histology and stage III/IV according to the International Federation of Gynecology and Obstetrics (FIGO) clinical staging system (28). Total hysterectomy with bilateral salpingo‑oophorectomy, omentectomy and appendectomy was performed in all cases, supplemented with partial resection of infiltrated intestine or bowel, peritonectomy or splenectomy for the purposes of optimal cytoreduction. Systemic or sampling lymphadenectomy was performed only in cases when optimal cytoreduction was achieved or in the presence of bulky nodes. Adjuvant treatment with platinum‑taxane regimen, six standard courses of carboplatin 5‑7.5 area under the curve (AUC) and paclitaxel 175 mg/m 2 and modified according to the patient's general status, was introduced in all cases. Clinical information was acquired from medical records. Serum CA125 levels and Risk of Malignancy Algorithm (ROMA) index calculated based on the levels of serum CA125, serum human epidydimis antigen‑4 (HE4) and pre‑menopausal or menopausal status were acquired prior to cytoreductive surgery. Platinum‑sensitive tumors where identified when there was no relapse ≥6 months following completion of the chemotherapy. Resistant patients were defined as patients with primary chemo‑refractory tumors (progression despite treatment with a first‑line chemotherapy). Platinum‑resistance was also diagnosed when relapse occurred ≤6 months following completion of chemotherapy. A total of 27 patients were identified to be chemosensitive and 21 patients were recognized as chemoresistant. Clinical characterizations of chemosensitive and chemoresistant patients are presented in Table I. Sample collection. miR‑146a expression was evaluated in tissues obtained from archival formalin‑fixed (tissues were fixed with 10% formalin for 24‑48 h at room temperature) paraffin‑embedded (FFPE) serous ovarian cancer samples. Other histological types of ovarian cancer were excluded from the present study. All archival FFPE samples were re‑evaluated by an experienced pathologist. Following confirmation of the cancer type, the areas of cancerous tissues were carefully selected and micro‑dissected from the samples in order to avoid areas of extensive necrosis and to minimalize the risk of contamination with noncancerous tissues. From each patient, two samples were obtained, with one sample from primary ovarian tumor and another sample from omental metastasis. The reference group consisted of 48 normal ovarian tissue samples that were retrieved from peri‑menopausal women during hysterectomy with bilateral salpingo‑oophorectomy

ONCOLOGY LETTERS 14: 3207-3214, 2017

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Table I. Clinicopathological characteristics and outcomes of patients in the platinum‑sensitive and platinum‑resistant groups.

Quantification of differentially expressed miRNAs. Reverse transcription was carried out using the Universal cDNA Synthesis kit (Exiqon A/S, Vedbaek, Denmark), according to the manufacturer's protocol A for individual assays. A total Platinum‑ Platinum‑ of 10 ng total RNA were used. The RT reaction was diluted Parameter sensitive resistant 80 times in nuclease‑free water, and 4 µl aliquots were subsequently used for PCR amplification with 5 µl ExiLENT SYBR® Case number (n) 27 21 Green Master mix (Exiqon A/S, Vedbaek, Denmark) and Mean age, years (range) 48 (24‑81) 54 (48‑75) 1 µl commercially available primers (Exiqon A/S, Vedbaek, FIGO stage Denmark): hsa‑miR‑146a‑5p LNA™ PCR primer set (cat. III (n) 23 20 no.  204688; target sequence, UAG​CAG​CAC​AUA​AUG​GUU​ UGU​G); SNORD48 (hsa) PCR primer set (cat. no. 203903; IV (n) 4 1 a target sequence,AGU​ G A​ U GA​ U GA​ C CC​ C AGG​ UAAC​ Tumor grade UCUG​AGUG​UGU​CGC​UGA​UGC​CAU​CAC​CGCAGC​GCU​ 1 (n) 2 2 CUGACC); and U6 snRNA (hsa, mmu, rno) PCR primer set 2 (n) 8 8 (cat. no  203907; target sequence,GUG​CUC​GCU​UCG​GCAG​ 3 (n) 17 11 CAC​AUA​UAC​UAA​A​AUU​GGA​ACG​AUA​CAG​AGA​AGAU​ Recurrence UAG​CAU​GGC​CCCU​GCG​CAAG​GAU​GAC​ACG​CAA​AUU​ No (n) 5 6 CGU​ GAA​ G CG​ U UC​ CAU​AUU ​ U UU). U6 small nuclear Yes (n) 22 15 RNA and small nuclear RNA, C/D box 48 were used as the internal controls. The reactions were incubated in a 96‑well Median PFS, months (range) 25 (12‑67) 4 (0‑11) Median OS, months (range) 33 (13‑70) 16 (2‑113) plate at 95˚C for 10 min, followed by 40 cycles of 95˚C for 15s and 60˚C for 1 min. All reactions were performed in dupliSurvival cate using a 7900HT Fast Real‑Time PCR System (Applied No (n) 3 9 Biosystems; Thermo Fisher Scientific, Inc., Waltham, MA, Yes (n) 24 12 USA). Relative expression level was determined using to the 2‑ΔΔCq method (29). PFS, progression‑free survival; OS, overall survival; FIGO, International Federation of Gynecology and Obstetrics. a(55).

due to benign uterine disease (uterine leiomyoma). All hysterectomy procedures were performed between January 2014 and December 2014. The mean age of patients was 47 years (range, 39‑56 years). Surgery was performed in the Polish Mother's Memorial Hospital Research Institute and informed consent was obtained from all of them. Total RNA isolation and miRNA expression analysis. Total RNA was extracted from FFPE tissues using the Roche High Pure miR Isolation kit (Roche Diagnostics GmbH, Mannheim, Germany), according to the manufacturer's instructions. In brief, the FFPE microsamples were processed in 2 ml Eppendorf tubes, deparaffinized with 100% xylene, washed in 100% ethanol and dried at 55˚C for ‑10 min. The dried tissue was resuspended in 100 µl Paraffin Tissue Lysis Buffer (included in the kit) and digested with proteinase K at 55˚C overnight. Subsequent steps of RNA purification on columns were performed according to the manufacturer's protocol (Roche Diagnostics GmbH). Briefly, 325 µl of binding buffer and 325 µl of binding enhancer was added and the mixture applied on the columns, centrifuged for 30 s at 13,000 x g and washed twice with 500 µl and 300 µl of wash buffer. An additional step of centrifugation for 1 min at 13,000 x g was performed to dry the filter fleece completely and RNA was eluted with 50 µl of Elution Buffer. The yield and quality (260/280 optical density ratios) of the RNA products were determined using a PicoDrop spectrophotometer (Picodrop Ltd., Hinxton, UK). The purified total RNA was immediately used for cDNA synthesis or stored at ‑80˚C until use.

Statistical analysis. Kaplan‑Meier survival curves were used to evaluate the association between the expression levels of miR‑146a and patient survival rate. The differences between the studied groups were determined by using the Mann‑Whitney U test or Kruskal‑Wallis. Spearman's rank correlation coefficient was used in order to determine the statistical dependence between two variables. Multivariate analysis was used to estimate correlations between ≥3 variables. P