The Molecular Mechanism of Paclitaxel-Resistance in Ovarian Clear Cell Carcinoma – from Dna Copy Number Alteration and Differential Expression of Genes Encoding Abc- and Slc-Transporters to Changes in Energy Demand and Metabolic Pathway

Compared to other types of epithelial ovarian carcinoma (EOC), the incidence of ovarian clear cell carcinoma (OCCC) is low globally but is higher in Japan and Taiwan, and the patients tend to have poor prognosis and higher resistance to platinum-taxel chemotherapy. OCCC has distinct gene signatures including mutation, copy number alteration, epigenetic modification and aberrant signal transduction. However, it is still unclear for the molecular mechanism of its higher chemo-resistance. We performed comparative genome hybridization and transcriptomic analysis on the OCCC ES2 cell line and two derived cells with higher paclitaxel resistance (ES2TR). A set of ABC-binding cassette (ABC-) and solute carrier (SLC-) transporter genes are found located in the genome area detected with paclitaxel-sensitivity relevant DNA copy number alteration or expresses differentially in a paclitaxel-responsive manner among these cells, suggesting that these genes may be the candidates related to paclitaxel resistance of OCCC. In addition, OCCC is known to possess reduced cell-proliferation but higher energy demand compared to other types of EOC, and our data obtained from Seahorse XFe analyzer revealed that ES2TR cells with higher paclitaxel-resistance seem to have higher oxygen consumption rate (OCR) compared to the original ES2. We therefore in this proposal, aim to clarify whether ABC- and SLC-transporter genes with DNA copy number alteration (CNA) and differentially expression pattern would prompt a unique change on energy demand and metabolic pathway, leading to cell survival from paclitaxel toxicity. The results of this study will provide new chemotherapeutic strategy for more precise clinical benefit in patients with this malignancy. Followings are the specific aims to be achieved in this proposal:1. Clarify the RNA and protein levels of identified genes encoding ATP-binding cassette (ABC)- and solute carrier (SLC)-transporter in immortalized normal epithelium OSE2a and OCCC ES2 and ES2-derived ES2TR120 and Es2TR300 cells, and the subcellular distribution of individual protein. Confirm the observation with other available OCCC cell lines. (the 1st year)2. Clarify the energy usage and metabolic pathway in ES2 vs. ES2TR cells and the correlation with expression level of ABC-/SLC- related genes; combining the systemic metabolomic analysis to reveal the metabolic pathway shift during OCCC acquiring paclitaxel resistance. (the 2nd year)三、Investigate the altered ABC-/SLC-transporter related signaling pathways and cell survival mechanisms underlying the higher paclitaxel-resistance of OCCC. (the 3nd year)