Abstract LB-269: PFKP/PFKFB3 modulate metabolic switch and chemoresistance to cisplatin in ovarian cancer
Authors: Wang Jingjing , Siu Michelle KY , Jiang Yuxin , Leung Thomas HY , NGAN Hextan YS , Cheung Annie NY , Chan Karen KL 
Published: July 2017

Abstract
Background: Late diagnosis and occurrence of chemoresistance contribute ovarian cancer the most malignant gynaecological cancer. High lactate generation and low glucose oxidation, regardless of oxygen availability, termed as the Warburg effect, are commonly found in cancers. Phosphofructokinase-1 (PFK-1) irreversibly converts fructose-6-phosphate to fructose-1,6-bisphosphate, the first committed step in the Warburg effect. PFK1 can be activated by fructose-2,6-bisphosphate (F2,6BP), which in turn is generated and degraded by 6-phosphofructo-2-kinase/fructose-2,6-bisphosphatases (PFKFB). The platelet isoform of PFK (PFKP) and inducible PFKFB3 isoform modulate glycolysis and contribute to tumorigenesis in other human cancers, the precise mechanisms have yet to be elucidated. Moreover, PFKP and PFKFB3 in ovarian cancer remain to be characterized. We hypothesize that PFKP, which is regulated by mi106a-5p, along with PFKFB3 modulate cancer metabolic switch and chemoresistance to cisplatin in ovarian cancer. Methods: Expression of PFKP and PFKFB3 in ovarian cancer cell lines was investigated by qPCR and immunoblotting. Expression of PFKP in 123 ovarian cancer tissue samples was evaluated by immunohistochemistry. The correlation between PFKP and clinicopathological parameters was analyzed. Ectopic expression or knockdown of PFKP/PFKFB3/miR106a-5p and treatment with 3PO (a PFKFB3 inhibitor), followed by lactate assay and TUNEL assay or annexin V/propidium iodide staining after treatment with cisplatin were performed in ovarian cancer cell lines to detect the effects on cancer metabolic switch and chemoresistance to cisplatin respectively. Additionally, the related apoptosis signaling pathway was explored by RT2 profiler PCR array and immuoblotting. Results: We found up-regulation of PFKP in ovarian cancer cell lines and patient samples with significantly higher PFKP found in chemoresistant than chemosensitive cell lines and clinical samples. Higher PFKP was correlated to shorter overall and disease-free survival. Higher PFKFB3 was also detected in chemoresistant than chemosensitive cell lines. Functionally, knockdown of PFKP/PFKFB3 in ovarian cancer resistant cells decreased lactate level, sensitized cells to cisplatin treatment, which was accompanied by increased cleavage of PARP. 3PO also reduced lactate level and sensitized A2780CP cells to cisplatin treatment, along with altered c-IAP1, c-IAP2, survivin and CD70 expression, and increased cleavage of caspases-9/7 and PARP. Ectopic expression of miR106a-5p decreased PFKP expression, reduced lactate level and sensitized A2780CP cells to cisplatin treatment. Conclusion: Our findings suggest that PFKP/PFKFB3 may overcome chemoresistance in ovarian cancer cells through apoptosis related pathway. Results also show the potential use of PFKFB3 inhibitor as therapeutic targets either alone or in combination with cisplatin and PFKP as a novel prognostic marker for ovarian cancer.
Citation Format: Jingjing Wang, Michelle KY Siu, Yuxin Jiang, Thomas HY Leung, Hextan YS NGAN, Annie NY Cheung, Karen KL Chan. PFKP/PFKFB3 modulate metabolic switch and chemoresistance to cisplatin in ovarian cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr LB-269. doi:10.1158/1538-7445.AM2017-LB-269