Abstract 2936: Molecular profiling of primary malignant pleuralmesothelioma histotypes cell lines reveals relationship between GDF15overexpression and cisplatin resistance both in in vitro and in vivo models

Abstract

Abstract Malignant pleural mesothelioma (MPM) development is mainly correlated with exposure to asbestos and appears to be a trend toward an increase in its incidence in the years to come. Although novel therapeutic strategies are under investigation, alone or in combination with conventional therapy, MPM remains a cancer with high medical need. With the aim to identify putative novel therapeutic targets/biomarkers expressed in specific MPM histotypes we investigated 9 different primary MPM cell lines at molecular, biochemical and pharmacological levels. A transcriptomic analysis has been conducted comparing the gene expression in epitheliod (E-MM473), sarcomatoid (S-MM432) and biphasic (B-MM487) primary cell lines. We found more than 1000 genes differentially regulated and statistically validated (p< = 0.05). The hierarchical clustering of the top 100 expressed genes revealed an histotype specific expression while few of them have a similar expression among the histotypes. 14 out of 100 genes were chosen based on their role in cell survival (hk1; gdf15; ifnar1/2; bmpr1/2; tgfrb; cdca8; birc5; plk1; srsf6; pin1; nox1; wt1). Their expression was confirmed via RT-PCR in all the 9 MPM cell lines (E-MM473, E-MM288, E-MM317, E-MM404, E-MM481; S-MM432, S-MM472; B-MM487, B-MM491) vs normal mesothelium cells (MET5A). Among the validated genes, gdf15 and hk1 expression strongly correlated with the epithelioid and bifasic histotype, respectively. The tumor relevance of these genes has been confirmed by siRNA interference in which hk1 and gdf15 transcript reduction significantly affected S-MM432 (>90%) and E-MM473/B-MM487 cell survival (>50%). GDF15 belongs to the TGF-β superfamily and its role in different pathologies including cancer is controversial (Breit et al., 2011). Its overexpression has been associated to tumor chemoresistance (Chung-Ying et al.,2007) including Cisplatin (Cis) (Li et al., 2015; Yang et al. 2014). To this end, we investigated if GDF15 protein levels in MPM cells exposed to Cis correlate with its citotoxicity. Interestingly GDF15 protein level, which is high in E-MM473, medium in B-M M432 and low in S-MM487, is inversely correlated with the cells sensitivity to the treatment (i.e. E-MM473 are 2-5 times more resistant) and GDF15 silencing increases Cis-induced cytotoxicity. To assess the relationship between GDF15 levels/ Cis resistance, efficacy of Cis (4mg/kg; q7dx3w;i.v.) on stably expressing luciferase E-MM473(highGDF15) and B-MM487 (lowGDF15), orthotopically xenografted in nude mice, were investigated. While, E-MM473 showed a poor response to the Cis (TGI 58%), an impressive tumor response (TGI 95%) was observed in treated B-MM487. Our results suggest and support the need of further clinical investigation to correlate GDF15 plasma level to the chemotherapy response in MPM patients. Citation Format: Claudio Pisano, Gianluca Carletta, Fulvio D’Angelo, Antonietta Esposito, Erminia Bianchino, Assunta Riccio, Michela Festa, Francesco Cardile, Emanuele Carchia, Walter D’Acunto, Giacomo Signorino, Mario B. Guglielmi, Pasquale De Luca. Molecular profiling of primary malignant pleuralmesothelioma histotypes cell lines reveals relationship between GDF15overexpression and cisplatin resistance both in in vitro and in vivo models. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 2936.