Microarray analysis revealed dysregulation of multiple genes associated with chemoresistance to As2O3 and increased tumor aggressiveness in a newly established arsenic-resistant ovarian cancer cell line, OVCAR-3/AsR

The potential of arsenic trioxide (As2O3) for use as a novel therapy for ovarian cancer treatment has been increasingly recognized. In this study, we developed an arsenic-resistant OVCAR-3 subline (OVCAR-3/AsR) and aimed to identify the molecular mechanisms and signaling pathways contributing to the development of acquired arsenic chemoresistance in ovarian cancer. OVCAR-3/AsR cells were obtained following continual exposure of parental OVCAR-3 cells to low dose As2O3 for 12 months. Cytotoxicity of OVCAR-3/AsR cells to As2O3, paclitaxel and cisplatin was investigated. Cell apoptosis and cell cycle distribution following As2O3 treatment of OVCAR-3/AsR cells was also analyzed using flow cytometry. Subsequently, cDNA microarray analysis was performed from the RNA samples of OVCAR-3 and OVCAR-3/AsR cells in duplicate experiments. Microarray data were analyzed using Genespring® and Pathway Studio® Softwares. OVCAR-3/AsR cells showed 9-fold greater resistance to As2O3 and lack of collateral resistance to cisplatin and paclitaxel. Compared with parental OVCAR-3 cells, OVCAR-3/AsR had significantly lower apoptotic rates following As2O3 treatment. These cells were also arrested at both the S phase and G2/M phase of the cell cycle after exposure to high concentrations of As2O3. Gene expression profiling revealed significant differences in expression levels of 397 genes between OVCAR-3/AsR and OVCAR-3 cells. The differentially regulated transcripts genes have functional ontologies related to continued cancer cell growth, cell survival, tumor metastasis and tumor aggressiveness. Additionally, numerous gene targets of the nuclear factor erythroid 2-related factor 2 (NRF2) transcription factor showed elevated expression in OVCAR-3/AsR cells. Subsequent pathway analysis further revealed a gene network involving interleukin 1-alpha (IL1A) in mediating the arsenic-resistant phenotype. These results showed that changes in multiple genes and an increased in tumor aggressiveness occurred during the development of acquired chemoresistance to As2O3 in ovarian cancer cells. The functional relevance of these genetic changes should be validated in future studies.

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