MicroRNA profiling in resistance ovarian cell lines

Although many genes associated with the development of resistance to chemotherapy are known, the mechanisms of their regulation are still poorly understood. One of the ways to regulate gene expression is regulation at mRNA level by small noncoding RNA particles – designated as a micro RNA (miRNA). Changes in miRNA expression were also observed in cell line studyes. Downregulation of miR-31 expression correlated with taxane resistance in ovarian cancer cell lines. In contrast upregulation of miR-98-5p was observed in cisplatin (CIS) -resistant cell lines. Changes in miRNAs expression were also noted in another cancers. miR-195 expression was downregulated in temozolomid-resistant glioma cells and miR-203 was downregulated in prostate cancer cells resistant to doxorubicin (DOX). The use of miRNA microarrays to analyse changes in miRNA gene expression is an effective molecular tool for the discovering new miRNA genes involved in drug resistance processes. The present study shows alterations in the miRNA expression levels in the CIS (W1CR), PAC (W1PR1 and W1PR2), DOX (W1DR), and topotecan (TOP) (W1TR) - resistant variants of W1 sensitive ovarian cancer cell line. The human primary ovarian cancer cell line W1 was established from tumour tissue of untreated 54-year old Caucasian female patient diagnosed for serous ovarian adenocarcinoma (G3, FIGO IIIc). Cells grow as a monolayer, present epithelial morphology and adherent growth model. Sublines resistant to cisplatin (W1CR), doxorubicin (W1DR), topotecan (W1TR) and paclitaxel (W1PR1 and W1PR2) were obtained by exposure of the W1 cell line to stepwise increasing drug concentrations. Final concentration of each drug was twofold greater than the concentration in the plasma 2 hours after intravenous administration. The cells were 8-, 10-, 20-, 641- and 967-folds resistant to their selective drugs, respectively, as determined by Cell Proliferation Kit I (MTT). All cell lines were maintained as monolayer in complete medium [RPMI-1640 medium supplemented with 10% (v/v) fetal bovine serum, 2 pMl-glutamine, penicillin (100 U/ml), streptomycin (100 U/ml) and amphotericin B (25 µg/ml)] at 37˚C in a 5% CO2 atmosphere.