Drug resistance is a common cause of failure in cancer chemotherapy treatments. In this study, we used a pair of uterine sarcoma cancer lines, MES-SA, and the doxorubicin-resistant MES-SA/Dx5 as a model system to examine resistance-dependent cellular responses and to identify potential therapeutic targets. We used two-dimensional differential gel electrophoresis (2D-DIGE) and matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF/TOF MS) to examine the global protein expression changes induced by doxorubicin treatment and doxorubicin resistance. A proteomic study revealed that doxorubicin-exposure altered the expression of 87 proteins in MES-SA cells, while no significant response occurred in similarly treated MES-SA/Dx5 cells, associating these proteins with drug specific resistance. By contrast, 37 proteins showed differential expression between MES-SA and MES-SA/Dx5, indicating baseline resistance. Further studies have used RNA interference, cell viability analysis, and analysis of apoptosis against asparagine synthetase (ASNS) and membrane-associated progesterone receptor component 1 (mPR) proteins, to monitor and evaluate their potency on the formation of doxorubicin resistance. The proteomic approach allowed us to identify numerous proteins, including ASNS and mPR, involved in various drug-resistance-forming mechanisms. Our results provide useful diagnostic markers and therapeutic candidates for the treatment of doxorubicin-resistant uterine cancer.
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