Abstract 215: CSE1L as a potential target to sensitize ovarian cancer cells to cisplatin

Proceedings: AACR 101st Annual Meeting 2010‐‐ Apr 17‐21, 2010; Washington, DC Human ovarian cancer is frequently (70% of cases) at advanced stage at presentation and requires multimodality treatment, consisting of cytoreductive surgery and chemotherapy based on platinum-drugs and taxanes. Patients are initially responsive to this treatment, but, in most cases, experience disease relapse because tumour cells acquire drug resistance. We demonstrated that the Hepatocyte Growth Factor (HGF) sensitizes to cisplatin (CDDP) and taxol an ovarian carcinoma cell line known to be resistant to platinum drugs: SK-OV-3, leading to an increased cancer cell death at very low drug doses both in vitro and in an animal model (Bardella et al., 2007; Rasola et al., 2004). This was an unexpected finding as HGF and its tyrosine kinase receptor, encoded by the MET oncogene, drives cell proliferation, survival and invasiveness during development and tumorigenesis. We also demonstrated that this effect is mediated by p38MAPK, which overwhelms the concomitant HGF activation of survival pathways, as the expression of a dominant negative form of p38MAPK abrogates the sensitization effect of HGF (Coltella et al., 2006). Using oligonucleotide microarrays, we studied the transcriptional responses of cell treated with CDDP in the presence or in the absence of HGF, and found that HGF pre-treatment modifies the transcriptional response to CDDP not only in SK-OV-3, but also in NIH-OVCAR-3, and TOV-21G ovarian cancer cells. The up- or down-modulation of the most differentially expressed genes found in common within these cell lines was reverted when the cells expressed a dominant negative form of p38MAPK, upholding once again the involvement of p38MAPK in this phenomenon. Among the top-ranked differentially expressed genes, which we identified, we focused functional studies on CSE1L/CAS. This gene is a nuclear transporter involved in both proliferation and apoptosis found to be amplified and over-expressed in ovarian cancer. Knocking down of CSE1L/CAS made ovarian cancer cells sensitized to low doses of cisplatin and triggered apoptosis while had no effect on other cancer and normal cell lines. In conclusion, we show that HGF and CDDP modulate transcription in ovarian cancer cells and that this transcriptional response is involved in apoptosis regulation. We also provide the proof-of-concept that the identified genes might be targeted to either increase the efficacy of chemotherapeutics or to revert chemotherapy resistance. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 215.