Chairperson EUTROC- Mayo Conference-Berlin - Preliminary characterization of pharmacodynamic biomarkers for LR-peptide growth inhibition of ovarian cancer (OC) cell models.

Preliminary characterization of pharmacodynamic biomarkers for LR-peptide growth inhibition of ovarian cancer (OC) cell models. M.R.Amorosoa,b, G.Marvertib, F.Genovese, DS. Matassab, J.HEllemanc, E.Bernsc, F.Espositob*, MP Costib*. aDept. Biomedical Sciences and cDept. Life Science, Via Campi 287-183, University of Modena and Reggio Emilia, 41125, Modena, Italy; Dept. of Medical Oncology, Erasmus University Medical Center - Cancer Center, PO Box 2040, 3000 CA, Rotterdam, Netherlands. bDepartment of Molecular Medicine and Medical Biotechnologies, University of Naples Federico II, Via Pansini 5, Naples 80131, Italy. LR-peptide is an inhibitor of human Thymidylate synthase (TS) through the stabilization of its inactive form as shown in drug-protein interaction experiments (1). Our previous findings demonstrated an inhibition of ovarian cancer cell growth at 2-4 μM in four cis-platin sensitive and resistant ovarian cancer cell-lines, i.e. A2780 and A2780/CP, 2008 and C13. The level of inhibition caused by LR-peptide is similar to that of paclitaxel, a first line drug in OC therapy. Mass spectrometry differential proteomic studies were performed on A2780 OC cell models in which untreated cells were examined in comparison with LR-peptide treated cells (2). Bioinformatic analysis of the results led to the identification of at least 10 proteins that were modulated upon LR-peptide treatment. Among them TRAP1 an antiapoptotic mitochondrial HSP75 protein was observed. This result was the starting point for a deeper understanding of the role of the combined TRAP1/DHFR/hTS modulation in ovarian cancer cells. We first studied the role of TRAP1 alone in OC cell models. We treated a panel of ovarian cancer cells (including IGROV1 and COV504) with paclitaxel, whose cytotoxic activity involves the activation of ER (endoplasmic reticulum) stress pathways. TRAP1 shows a protective role from ER stress, as reported previously (3). We observed that upon 1-hour exposure to a sub-lethal concentration of paclitaxel, cells expressing higher TRAP1 levels (IGROV1) showed a weak activation of ER stress sensors. such as phospho PERK, phospho eIf2alpha and Grp78/BiP. COV504 cell line express lower level of TRAP1, are more sensitive to paclitaxel treatment, showing an hyperactivation of ER stress markers. Higher concentrations of paclitaxel for longer times led to apoptotic processes as confirmed by stronger activation of the ER-stress induced caspase 12, in COV cells than in IGROV cell line. These data confirm the protective role of TRAP1 against paclitaxel induced ER stress, offering a possible mechanism of drug resistance in ovarian cancer. 1.Cardinale D. et al., PNAS 2011. 2. Proceedings EPS32 Athen 2013 p_466 3. Amoroso MR, et al.Cell Death Differ. 2012 Acknowledgement This work has been supported by AIRC-DROC 10474 project to MPC.