Neolacto glycosphingolipids promote Doxorubicin, Epirubicin, and organoarsenic PENAO sensitivity and hypoxia-induced HIF-1a accumulation in ovarian cancer cells

Introduction/Aim: We investigate the yet unknown function of neolacto-glycosphingolipids GSLs (P1 and nLc4) on drug sensitivity and response to hypoxia, two major obstacles in cancer management. We used parental IGROV1 ovarian cancer cells and our previously generated knockout subline disrupted in B3GNT5 gene (B3GNT5-ko). B3GNT5 is the key enzyme in P1 and nLc4 biosynthesis. GSLs are located on the cell membranes and considered to be critically implicated in the pathogenesis of various diseases and cancer.

Material and methods: Gene disruption was achieved by CRISPR/Cas9 genome-editing of B3GNT5 and confirmed by genotyping and quantitative PCR; GSL expression determined by flow cytometry, drug sensitivity by MTT-assay, and apoptosis and hypoxia inducible factor (HIF-1a) induction in cobalt chloride-treated cells by Western-blotting.

Results: Parental IGROV1 cells expressed both neolacto P1 and nLc4. As anticipated, B3GNT5-ko cells were depleted in P1 and nLC4. Non-neolacto GSL remained unaffected. These neolacto-depleted B3GNT5-ko cells proliferated slower than their parentals. They were 4-fold resistant to Doxorubicin and Epirubicin and presented with decreased apoptosis. This resistance produced elevated MDR1-expression but was reversed upon MDR1-specific inhibitor CP-100356. Neolacto-depleted cells were also 2-fold resistant to organoarsenic PENAO, whereas no sensitivity difference was found for Paclitaxel, Docetaxel, Carboplatin, and Cisplatin. Neolacto-depleted cells showed reduced HIF-1a accumulation compared to their parentals.

Conclusion: Neolacto GSL promote sensitivity of IGROV1 ovarian cancer cells to anthracyclines and PENAO (but not taxanes and organic platinum compounds) and HIF-1a induction. This novel function of neolacto GSLs also demonstrates their importance in drug and hypoxia responses.