Telang, Sucheta

Metabolic alterations are increasingly recognized as important novel anti‐cancer targets. Among several regulators of metabolic alterations, fructose 2,6 bisphosphate (F2,6BP) is a critical glycolytic regulator. Inhibition of the active form of PFKFB3ser461 using a novel inhibitor, PFK158 resulted in reduced glucose uptake, ATP production, lactate release as well as induction of apoptosis in gynecologic cancer cells. Moreover, we found that PFK158 synergizes with carboplatin (CBPt) and paclitaxel (PTX) in the chemoresistant cell lines, C13 and HeyA8MDR but not in their chemosensitive counterparts, OV2008 and HeyA8, respectively. We determined that PFK158‐induced autophagic flux leads to lipophagy resulting in the downregulation of cPLA2, a lipid droplet (LD) associated protein. Immunofluorescence and co‐immunoprecipitation revealed colocalization of p62/SQSTM1 with cPLA2 in HeyA8MDR cells uncovering a novel pathway for the breakdown of LDs promoted by PFK158. Interestingly, treating the cells with the autophagic inhibitor bafilomycin A reversed the PFK158‐mediated synergy and lipophagy in chemoresistant cells. Finally, in a highly metastatic PTX‐resistant in vivo ovarian mouse model, a combination of PFK158 with CBPt significantly reduced tumor weight and ascites and reduced LDs in tumor tissue as seen by immunofluorescence and transmission electron microscopy compared to untreated mice. Since the majority of cancer patients will eventually recur and develop chemoresistance, our results suggest that PFK158 in combination with standard chemotherapy may have a direct clinical role in the treatment of recurrent cancer.

Abstract Metabolic alterations in cancer are increasingly being recognized as important novel targets. Among different regulators of altered metabolism, 6-PhosphoFructo-2-Kinase/Fructose-2,6-Bisphosphatases 3 (PFKFB3) a glycolytic enzyme required for tumorigenic growth, and produces fructose-2,6-bisphosphate (F2,6BP), is recognized as important regulator of glycolysis. We determined that the active form of PFKFB3ser471 was overexpressed in chemo-resistant ovarian cancer (OVCA) cell lines and resistant patient derived xenograft (PDX) models compared to their isogenic chemo-sensitive cell lines and sensitive PDX models. These results suggest that targeting PFKFB3 will have beneficial effects in patients with OVCA. PFK-158 is a potent and selective inhibitor of PFKFB3 that is currently being investigated in a Phase 1 study in patients with advanced solid malignancies. Here we report for the first time, PFK-158 dose-dependently inhibits cell proliferation and colony formation ability in both carboplatin and paclitaxel (PTX) resistant cell lines. PFK-158 markedly suppresses glycolysis by reducing glucose uptake, ATP production, lactate dehydrogenase activity and lactate secretion. Interestingly, both Chou-Talalay synergy analysis and apoptosis assay by annexin V-PI staining showed PFK-158 strongly synergies with both PTX and carboplatin in PTX and cisplatin resistant cell lines respectively. PFK-158 induced apoptosis through a significant increase in caspase-3/7 activation and PARP cleavage. Moreover, in a highly metastatic PTX-resistant in vivo model, combination of PFK-158 with carboplatin and PTX significantly reduced tumor weight, ascites and metastasis compared to untreated and PFK-158, carboplatin or PTX alone treated mice. Since the majority of OVCA patients recur with chemo-resistant disease, our results suggest that PFK-158 in combination with standard chemotherapy may have clinical utility in late stage ovarian cancer patients. Citation Format: Susmita Mondal, Debarshi Roy, Eleftheria Kalogera, Ashwani Khurana, Gilles H. Tapolsky, Sucheta Telang, Jason Chesney, Viji Shridhar. Inhibition of PFKFB3/glycolysis overcomes chemoresistance in ovarian cancers. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 2706. doi:10.1158/1538-7445.AM2015-2706