Loss of HSulf-1 promotes defective autophagy and increased lipid droplet biogenesis in vitro and in vivo in ovarian cancer

5^th Asia-Pacific Summit on Cancer Therapy

July 20-22, 2015 Brisbane, Australia

Viji Shridhar1 , Debarshi Roy1, Susmita Mondal1, Ashwani Khurana1, Xiaoping He1, Edward Hammond2 and Keith Dredge2

Posters Accepted Abstracts: J Cancer Sci Ther

Abstract :

Dysregulation of autophagy and altered metabolic pathways are frequently observed in cancer. Due to these alterations, pharmacological targeting of these two pathways simultaneously could provide a viable therapeutic option. Although the association between these two pathways is well characterized in metabolic disorders, it is not well defined in ovarian cancer (OVCA). In this regard, we found that loss of endosulfatase HSulf-1, a known putative tumor suppressor suppresses LC3-GFP foci formation and promotes increased lipid droplet (LD) biogenesis suggesting that absence of HSulf-1 in OVCA affects both autophagy and lipid metabolism. While isogenic cells with genetic ablation of HSulf-1 (OV202Sh1/2 and TOV2223Sh1 cells) displayed LDs, the nontargeted control transduced (NTC) OV202 and TOV2223 cells had significantly less LDs. In contrast, Transmission Electron Micrographs (TEMs) showed that OV202 and TOV2223 NTC cells had significantly more autophagic vacuoles (AVs) compared to their isogenic ShRNA targeted cells. Conversely, ectopic expression of HSulf-1 in SKOV3 cells decreased the number of LDs and increased the number of AVs compared to vector transfected controls. Here we report that OV202Sh1 cells and HSulf-1 deficient OV2008 cells have increased p-cPLA2α (ser505) levels that are associated with biogenesis of large number of LDs with reduced AVs. Interestingly, pharmacological inhibition of cPLA2α with AACOCF3 in OV202Sh1 cells resulted in reduced LD biogenesis inhibited colony formation and reduced tumorigenesis in vivo. More importantly, treatment of HSulf-1 deficient cells with HS mimetic PG545 which can compensate for loss of HSulf-1, reduced LD biogenesis, promoted autophagy and inhibited tumor growth in vivo. Collectively, these results show a critical role of HSulf-1 in regulating both autophagy and LD biogenesis in ovarian cancer.