Abstract B14: Cisplatin induced activation of the epidermal growth factor receptor as a mechanism for epigenetic silencing in ovarian cancer cell platinum resistance

The 5-year survival rate for women diagnosed with ovarian cancer remains dismally unchanged at 44%. Resistance to platinum compounds in ovarian cancer imparts a major obstacle to increasing patient survival. The epidermal growth factor receptor (EGFR) plays a role in the regulation of growth and differentiation in normal cells, and proliferation in malignant cells. It is known that disregulation of the EGFR pathway, including prolonged receptor activation, is associated with platinum resistance in cellular models and our lab revealed a novel mechanism by which constitutive EGFR activation regulates DNA methyltransferase (DNMT) activity and DNA methylation. Platinum resistance is associated with epigenetic downregulation (via DNA methylation) of genes involved in platinum drug response, particularly genes important for drug uptake. Given the established link between platinum resistance and alterations to DNA methylation, our studies investigated the effects of acute cisplatin treatment on EGFR activation and DNMT activity. We hypothesized that acquired chemoresistance resulting from cisplatin treatment is initially triggered by cisplatin-induced EGFR activation and subsequent alterations to DNMT activity. We show activation of EGFR upon treatment of OVCA433 cells with cisplatin. Functional EGFR activation following cisplatin treatment was also observed by evaluating activation of downstream targets, Jak2 and Akt. Hence, cisplatin facilitates activation of EGFR and its downstream signaling pathways. Moreover, there was also a significant increase in DNMT activity in cisplatin treated cells when compared to untreated passage controls. These observations unmask a potential mechanism by which initial exposure to cisplatin can activate EGFR signaling and cause epigenetic alterations that may contribute to the development of platinum resistance. By understanding the underlying mechanism for development of platinum resistance and discovering targets of methylation, we may be able to enhance sensitivity to platinum based chemotherapeutics. Citation Format: Michaela Lee Granados, Laurie G. Hudson, Sabrina Leigh Samudio-Ruiz. Cisplatin induced activation of the epidermal growth factor receptor as a mechanism for epigenetic silencing in ovarian cancer cell platinum resistance. [abstract]. In: Proceedings of the AACR Precision Medicine Series: Drug Sensitivity and Resistance: Improving Cancer Therapy; Jun 18-21, 2014; Orlando, FL. Philadelphia (PA): AACR; Clin Cancer Res 2015;21(4 Suppl): Abstract nr B14.