Abstract
BACKGROUND: Platinum resistance development is a dynamic process that occurs during continuous chemotherapy and contributes to high mortality in ovarian cancer. Abnormal glycosylation has been reported in platinum resistance. Many studies on platinum resistance have been performed, but few of them have investigated platinum resistance-associated glycans based on N-glycomics. Moreover, glycomic alterations during platinum resistance development in ovarian cancer are rarely reported. Therefore, the objective of this study was to determine platinum resistance-related N-glycans in ovarian cancer cells during continuous exposure to cisplatin. These glycans might be involved in the mechanism of platinum resistance and serve as biomarkers to monitor its development. METHODS: This study mimicked the development of platinum resistance in ovarian cancer by continuously exposing A2780 cells to cisplatin. Cisplatin-resistant variants were confirmed by higher half maximal inhibitory concentration (IC(50)) values and increased P-glycoprotein (ABCB1, P-gp) expression compared to A2780 cells. Analysis of dynamic N-glycomic changes during the development of platinum resistance in cisplatin-resistant variants was performed with MALDI-time-of-flight (TOF)-MS combined with ethyl esterification derivatization, which were used to discriminate between α2,3- and α2,6-linkage N-acetylneuraminic acid. N-glycan alterations were further validated on a glycotransferase level via transcriptome sequencing and real-time PCR (RT-PCR). RESULTS: Compared to the A2780 cells, MS analysis indicated that α2,3-linked sialic structures and N-glycan gal-ratios were significantly higher, while fucosylated glycans were lower in three cisplatin-resistant variants. Transcriptome sequencing and RT-PCR showed that gene expression of ST3GAL6 and MGAT4A increased, while gene expression of FUT11, FUT1, GMDS, and B4GALT5 decreased in three cisplatin-resistant variants. CONCLUSIONS: Analysis of N-glycans and glycogene expression showed that α2,3-linked sialic structures might serve as biomarkers to monitor the development of platinum resistance and to guide individualized treatment of ovarian cancer patients.