To better understand the molecular mechanisms of paclitaxel resistance in ovarian carcinoma, we evaluated the expression of miRNAs using miRNA microarray between human ovarian carcinoma SKOV3 cells and paclitaxel resistant SKOV3-TR30 cells. Results showed that 69 miRNAs were upregulated while 102 miRNAs were downregulated in SKOV3-TR30 cells. Using real-time PCR, we further clarified that miR-17~92 was overexpressed in SKOV3-TR30 cells compared with that in SKOV3 cells. We then established stable virally transduced SKOV3-TR30-m-PTIP-Sponge all SKOV3-TR30 cells and its vector-only control SKOV3-TR30-m-PTIP-GFP cells. Real time-PCR revealed that SKOV3-TR30-m-PTIP-Sponge all cells expressed approximately 6.18-fold lower levels of miR-17~92 compared with the control group. Decreased expression of miR-17~92 resulted in cell cycle arrest in the G2/M phase and growth inhibition. After the transduction, the BIM protein level was increased in SKOV3-TR30 cells and luciferase reporter assays revealed that miR-17~92 binds directly to the 3'-UTR of BIM. Results of luciferase reporter assays accompanied with Western Blot showed that although miR-17~92 binds directly to the 3'-UTR of PTEN, the PTEN protein expression level was upregulated slightly while the result is of no statistical significance. Our results showed that miR-17~92 could be a causal factor of the downregulation of BIM in SKOV3-TR30 cells and thus induce the paclitaxel resistance in SKOV3-TR30 cells.
References
[1]
Jemal, A.; Siegel, R.; Xu, J.; Ward, E. Cancer statistics, 2010. CA Cancer J. Clin 2010, 60, 277–300.
[2]
Filipowicz, W.; Bhattacharyya, S.N.; Sonenberg, N. Mechanisms of posttranscriptional regulation by microRNAs: Are the answers in sight? Nat. Rev. Genet 2008, 9, 102–114.
[3]
Caldas, C.; Brenton, J.D. Sizing up miRNAs as cancer genes. Nat. Med 2005, 11, 712–714.
[4]
Calin, G.A.; Croce, C.M. MicroRNA signatures in human cancers. Nat. Rev. Cancer 2006, 6, 857–866.
[5]
Esquela-Kerscher, A.; Slack, F.J. Oncomirs-microRNAs with a role in cancer. Nat. Rev. Cancer 2006, 6, 259–269.
[6]
Cho, W.C. MicroRNAs: Potential biomarkers for cancer diagnosis prognosis and targets for therapy. Int. J. Biochem. Cell Biol 2010, 42, 1273–1281.
[7]
William, C.S.; Cho, W.C. MicroRNAs in cancer—from research to therapy. Biochem. Biophys. Acta 2010, 1805, 209–217.
Letai, A.; Bassik, M.C.; Walensky, L.D.; Sorcinelli, M.D.; Weiler, S.; Korsmeyer, S.J. Distinct BH3 domains either sensitize or activate mitochondrial apoptosis, serving as prototype cancer therapeutics. Cancer Cell 2002, 2, 183–192.
[10]
Ota, A.; Tagawa, H.; Karnan, S.; Tsuzuki, S.; Karpas, A.; Kira, S.; Yoshida, Y.; Seto, M. Identification and characterization of a novel gene, C13orf25, as a target for 13q31-q32 amplification in malignant lymphoma. Cancer Res 2004, 64, 3087–3095.
[11]
He, L.; Thomson, J.M.; Hemann, M.T.; Hernando-Monge, E.; Mu, D.; Goodson, S.; Powers, S.; Cordon-Cardo, C.; Lowe, S.W.; Hannon, G.J.; Hammond, S.M. A microRNA polycistron as a potential human oncogene. Nature 2005, 435, 828–833.
Willis, S.N.; Fletcher, J.I.; Kaufmann, T.; van Delft, M.F.; Chen, L.; Czabotar, P.E.; Ierino, H.; Lee, E.F.; Fairlie, W.D.; Bouillet, P.; et al. Apoptosis initiated when BH3 ligands engage multiple Bcl-2 homologs, not Bax or Bak. Science 2007, 315, 856–859.
[14]
Tanaka, M.; Grossman, H.B. In vivo gene therapy of human bladder cancer with PTEN suppresses tumor growth; down regulates phosphorylated Akt, and increases sensitivity to doxorubicin. Gene Ther 2003, 10, 1636–1642.
[15]
Wu, H.; Cao, Y.; Weng, D.; Xing, H.; Song, X.; Zhou, J.; Xu, G.; Lu, Y.; Wang, S.; Ma, D. Effect of tumor suppressor gene PTEN on the resistance to cisplatin in human ovarian carcinoma cell lines and related mechanisms. Cancer Lett 2008, 271, 260–271.
[16]
Gao, X.; Zhang, R.; Qu, X. MiR-15a, miR-16-1 and miR-17~92 cluster expression are linked to poor prognosis in multiple myeloma. Leuk. Res 2012, 36, 1505–1509.
[17]
Ouchida, M.; Kanzaki, H. Novel direct targets of miR-19a identified in breast cancer cells by a quantitative proteomic approach. PLoS One 2012, 7, e44095.
[18]
Baumhoer, D.; Zillmer, S.; Unger, K.; Rosemann, M.; Atkinson, M.J.; Irmler, M.; Beckers, J.; Siggelkow, H.; von Luettichau, I.; Jundt, G.; et al. MicroRNA profiling with correlation to gene expression revealed the oncogenic miR-17~92 cluster to be up-regulated in osteosarcoma. Cancer Genet 2012, 205, 212–219.
[19]
Ohyashiki, K.; Umezu, T.; Yoshizawa, S.; Ito, Y.; Ohyashiki, M.; Kawashima, H.; Tanaka, M.; Kuroda, M.; Ohyashiki, J.H. Clinical impact of down-regulated plasma miR-92a levels in non-hodgkin’s lymphoma. PLoS One 2011, 6, e16408.
