MIR-433 Predicts poor response to chemotherapy in ovarian cancer patients by the induction of cellular senescence

Weiner-Gorzel K., D. Sharpe, M Milewska, C. Beggan, N. Faheem, A. McGoldrick, V. Toh, S. Madden, P. Fitzpatrick, M. Murphy, J. McCaffrey , M. Harrison, E. Kay, M. R. Kell, A. McCann, F. Furlong

Research output: Contribution to conferenceAbstractpeer-review

Abstract

Annually, ovarian cancer (OC) affects 240,000 women worldwide and is the most lethal gynaecological malignancy. Such mortality is predominantly associated with the development of an intrinsic and acquired resistance to chemotherapy, the lack of targeted therapies and the lack of biomarkers predicting response to standard treatment.

Our clinical data demonstrates that increased miR-433 expression in primary high grade serous OC (HGSOCs) is significantly associated with poor PFS (n=46, p=0.024). Interestingly, the IHC analysis of two miR-433 targets: MAD2 [1] and HDAC6 shows that low IHC levels of both proteins is also significantly associated with worse outcome (p=0.002 and 0.002 respectively; n=43). Additionally, the analysis of miR 433 in the publicly available TCGA dataset corroborates that high miR-433 is significantly correlated with worse OS for patients presenting with OC (n=558 and p=0.027). In vito, in a panel of OC cell lines, higher miR-433 and lower MAD2 and HDAC6 levels were associated with resistance to paclitaxel.

To further investigate the role of miR-433 in the cellular response to chemotherapy, we generated an OC cell line stably expressing miR-433 or miR-control. MTT viability assays and Western Blot analyses established that miR-433 cells were more resistant to paclitaxel treatment (50nM) compared to miR-controls. Importantly, we have shown for the first time that miR 433 induced senescence resulting in a chracteristic flattened morphology and down-regulation of phosphorylated Retinoblastoma (p Rb), a molecular marker of senescence. Surprisingly, miR 433 induced senescence was independent from two well recognised senescent drivers: namely p53/p21 and p16. To explore this further we performed an in silico analysis of seven microRNA platforms which indicated that miR 433 potentially targets Cyclin-dependent kinase CDK6, which promotes sustained phosphorylation of Rb and thus cell cycle progression. In vitro, the overexpression of pre-miR-433 resulted in diminished CDK6 expression demonstrating a novel interaction between miR-433 and CDK6.

In conclusion, this study demonstrates that high miR-433 expression predicts poor outcome in OC patients by putatively rendering OC cells resistant to paclitaxel treatment through the induction of cellular senescence identifying this microRNA as a potential marker of chemoresponse.
Original languageEnglish
Publication statusPublished - 27 Feb 2014
EventIrish Association for Cancer Research Annual Meeting - Galway, Ireland
Duration: 27 Feb 201428 Feb 2014

Conference

ConferenceIrish Association for Cancer Research Annual Meeting
CountryIreland
CityGalway
Period27/02/201428/02/2014

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