Proteomic investigating the cooperative lethal effect of EGFR and MDM2 inhibitors on ovarian carcinoma.

With the concept of precision medicine, combining multiple molecular-targeting therapies has brought new approaches to current cancer treatments. Malfunction of the tumor suppressor protein, p53 is a universal hallmark in human cancers. Under normal conditions, p53 is degraded through an ubiquitin-proteosome pathway regulated by its negative regulator, MDM2. In contrast, cellular stress such as DNA damage will activate p53 to carry out DNA repair, cell cycle arrest, and apoptosis. In this study, we focused on ovarian carcinoma with high EGFR and MDM2 overexpression rate. We assessed the effects of combined inhibition by MDM2 (JNJ-26854165) and EGFR (gefitinib) inhibitors on various ovarian cell lines to determine the importance of these two molecular targets on cell proliferation. We then used a proteomic strategy to investigate the relationship between MDM2 and EGFR inhibition to explore the underlying mechanisms of how their combined signaling blockades work together to exert cooperative inhibition. Our results demonstrated that all four cell lines were sensitive to both individual and combined, MDM2 and EGFR inhibition. The proteomic analysis also showed that gefitinib/JNJ-treated CAOV3 cells exhibited downregulation of proteins involved in nucleotide biosynthesis such as nucleoside diphosphate kinase B (NME2). In conclusion, our study showed that the combined treatment with JNJ and gefitinib exerted synergistic inhibition on cell proliferation, thereby suggesting the potential application of combining MDM2 inhibitors with EGFR inhibitors for enhancing efficacy in ovarian cancer treatment.

PI3K inhibitor enhances the cytotoxic response to etoposide and cisplatin in a newly established neuroendocrine cervical carcinoma cell line.

BACKGROUND: Neuroendocrine cervical carcinoma (NECC) is a rare and aggressive subtype of cervical cancer. To date, no NECC cell-based model is available, which hinders the development of new therapeutic strategies for NECC. In this study, we derived a new NECC cell line from an ex vivo biopsy and used it to explore novel drug combination approach for NECC. RESULTS: The stable HM-1 cell line displayed high expression levels of the neuroendocrine marker, synaptophysin. HM-1 cell transplantation could induce tumor growth in nude mice. As expected, the combination of etoposide and cisplatin synergistically inhibited HM-1 cell proliferation. Strikingly, when etoposide and cisplatin were combined with PI3K inhibitor BEZ235, the growth of HM-1 cells was significantly reduced. Taken together, the data implied the combination of etoposide and cisplatin with BEZ235 not only inhibited HM-1 cell proliferation but also increased cell apoptosis. MATERIALS AND METHODS: A NECC tissue sample from a 75-year-old female patient was processed to derive a primary cell line annotated as HM-1. The features of HM-1 were analyzed to establish its characteristic profile. Next, HM-1 was treated with PI3K inhibitors, BKM120 and/or BEZ235, in combination with two well-known genotoxic drugs, etoposide and/or cisplatin, to evaluate which combination could serve as a more effective treatment approach. Their inhibiting effects on HM-1 were evaluated by cell viability, apoptosis, and target kinase expression. CONCLUSIONS: The newly established NECC cell line HM-1 could serve as a cell-based model for NECC research. The synergistic drug combination of PI3K inhibitor with genotoxic drugs might become a potential new treatment strategy against NECC.