Shanzhou Xie, Shiqiang Luo, Aozhen Bi, Lizhou Shi, Ying Zhang, Fuqiang Yin, Xia Liu
We have established and characterized two novel murine OC chemoresistance models. The resistant phenotypes of ID8-T and ID8-C sublines are associated with a multifaceted adaptive signature involving enhanced drug efflux, evasion of cell cycle arrest and apoptosis, reduced ROS levels, and altered expression of proteins related to mitochondrial fission. These well-characterized syngeneic models provide valuable tools for future mechanistic and therapeutic studies aimed at overcoming chemotherapy resistance in OC.
INTRODUCTION: Acquired resistance to platinum-taxane chemotherapy is a major cause of treatment failure in ovarian cancer (OC). In vitro cell models are indispensable tools for investigating chemoresistance mechanisms, and the establishment of new resistant cell models contributes to a more comprehensive understanding of these mechanisms. Currently, syngeneic mouse cell models remain scarce.
METHODS: Paclitaxel- and carboplatin-resistant sublines (ID8-T and ID8-C) were established by intermittent drug exposure from parental ID8 cells. Cellular morphology was assessed by Giemsa staining. Cell viability was determined using CCK-8 and colony formation assays. Flow cytometry was employed to analyze cell cycle distribution and apoptosis rate. Intracellular drug concentration was quantified by high-performance liquid chromatography (HPLC). Reactive oxygen species (ROS) levels were detected with a fluorescent probe, and protein expression profiles were analyzed by Western blotting.
RESULTS: Both ID8-T and ID8-C exhibited significant resistance to their inducing agents, with resistance indices of 4.54 and 2.21, respectively, and demonstrated cross-resistance phenotype. They showed enhanced clonogenic survival and attenuated drug-induced cell cycle arrest and apoptosis. Mechanistically, resistant cells exhibited reduced intracellular drug accumulation, maintained lower ROS levels, and displayed altered expression of key regulatory proteins. These included sustained pro-survival signals (MCM2, STAT3, 4E-BP1), impaired apoptotic execution (reduced cleaved caspase-3/PARP/LaminA/C), upregulation of the drug efflux pump ABCB1, and dysregulated mitochondrial fission machinery (downregulated MFF).
CONCLUSION: We have established and characterized two novel murine OC chemoresistance models. The resistant phenotypes of ID8-T and ID8-C sublines are associated with a multifaceted adaptive signature involving enhanced drug efflux, evasion of cell cycle arrest and apoptosis, reduced ROS levels, and altered expression of proteins related to mitochondrial fission. These well-characterized syngeneic models provide valuable tools for future mechanistic and therapeutic studies aimed at overcoming chemotherapy resistance in OC.