6-Phosphofructo-2-Kinase Enhances Cytotoxicity Of The Egfr Inhibitor Erlotinib Via Regulation Of Cell Cycle In Non-Small Lung Cancer Cell Lines.

Abstract Lung tumor development and aggressiveness is largely driven by a multitude of oncogenes including the epidermal growth factor receptor (EGFR). Targeted EGFR inhibition with small-molecule tyrosine kinase inhibitors (EGFR-TKIs) such as erlotinib have initially improved progression-free survival in patients with EGFR-driven NSCLCs but failed to provide an overall survival benefit due to the development of resistance. Clinically, responses to EGFR-TKIs are evaluated by positron emission tomography using 2[18F]- fluoro-2-deoxy-glucose (18FDG-PET) as tumors consume significantly more glucose compared to adjacent normal tissue in vivo. 6-phosphofructo-2-kinase/fructose-2,6-bisphosphatase (PFKFB3), a known driver of glycolytic flux, plays a key role in the metabolic shift that occurs during tumor progression. The product of PFKFB3, F2,6BP, regulates glucose metabolism by activating PFK1, which in turn facilitates glycolysis. Increased glycolysis fulfills the elevated tumor demands for energetic and biosynthetic precursors needed for survival and proliferation - the functions that confer resistance to targeted therapies. Here, we interrogated the hypothesis that PFKFB3 inhibition increases the efficacy of EGFR-TKIs in NSCLCs with different EGFR mutation status in vitro. We treated multiple NSCLCs models (wild type EGFR: H522, H1437; and mutated EGFR: PC9, HCC827) with erlotinib and observed a significant inhibition of cell proliferation in vitro. Erlotinib treatment resulted in G1 arrest, decreased expression and phosphorylation of cyclin dependent kinases (CDKs), Rb and accumulation of p27 in all NSCLCs. Notably, PFKFB3 silencing in TKI-treated cells dramatically decreased cell viability, indicating that PFKFB3 expression is required to maintain cell viability of G1 arrested cells. Further, co-treatment with the PFKFB3 inhibitor PFK-158 increased cell death in all NSCLCs. We found that inhibition of PFKFB3 reduced TKI-induced G1 arrest and altered cell cycle progression, switching the effect of erlotinib from cytostatic to cytotoxic. Importantly, dual treatment caused only minor changes in glycolytic flux when compared to the effects of PFK-158 or erlotinib alone suggesting that glucose metabolism did not contribute to the observed effect. Taken together, our findings suggest that a non-metabolic function of PFKFB3 limits the usefulness of EGFR-TKI in vitro and that targeting of PFKFB3 can be a promising approach to improve clinical efficacy of FDA-approved EGFR-TKIs in lung cancer patients. Citation Format: Nadiia Lypova, Lilibeth Lanceta, Jason Chesney, Yoannis Imbert-Fernandez. 6-phosphofructo-2-kinase enhances cytotoxicity of the EGFR inhibitor erlotinib via regulation of cell cycle in non-small lung cancer cell lines [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 1052.