Abstract P4-02-10: Pfkfb3 inhibition significantly decreases endocrine-resistant breast cancer growth and induces necroptotic cell death

Abstract

Abstract Estrogen receptor-positive breast cancers constitute the majority of newly diagnosed breast cancers in patients. While commonly treated with various approved endocrine therapy strategies, these cancers can unfortunately also develop resistance to such therapies, indicating a need to explore other avenues of treatment in endocrine-resistant breast cancer. Rapidly dividing cancer cells are known to have an increased energy demand and altered reprogramming of glucose metabolism, leading to a subsequent heavy reliance on glycolysis. A critical rate-limiting step in the glycolysis pathway, the conversion of fructose-6-phosphate to fructose-1,6-bisphosphate, is greatly influenced by an allosteric activator produced by the enzyme PFKFB3 (6-phosphofructo-2-kinase/fructose-2,6-biphosphatase 3), thus making PFKFB3 an essential regulator of glycolytic flux. Furthermore, PFKFB3 has been shown to be overexpressed in many human cancers, including breast cancer, as well as be upregulated by estrogen. Through the following work, we show that endocrine-resistant BC cell growth is strongly reduced by PFKFB3 targeting using different commercial PFKFB3 inhibitors, which can be further exacerbated by combination treatment with well-established endocrine therapies like fulvestrant in some cell lines. Moreover, we relatedly show that PFKFB3 inhibition reduced tumor size in mouse xenografts of endocrine-resistant BC cells. Endocrine-resistant cells also presented higher basal glucose uptake and greater reduction of glucose uptake in response to PFKFB3 inhibition than endocrine-sensitive cells, indicating that endocrine-resistant breast cancer cells may have a more significant reliance on glycolysis and PFKFB3 activity for their metabolic needs than sensitive cells. Additionally, PFKFB3 inhibition produced an increase in phosphorylation of the necroptotic markers RIPK1 (receptor-interacting kinase 1), and MLKL (Mixed Lineage Kinase Domain Like Pseudokinase), and pre-treatment with the necroptosis inhibitor necrostatin-1 was able to partially rescue cell death caused by PFKFB3 targeting, suggesting that necroptosis is a primary method of cell death induced by PFKFB3 inhibition. In summation, this study showcases the glycolytic enzyme PFKFB3 as an encouraging therapeutic target in endocrine-resistant breast cancer, and warrants further review as a monotherapy or in combination with current endocrine therapies. Citation Format: Brandon C Jones, Surojeet Sengupta, Catherine M Sevigny, Lu Jin, Paula R Pohlmann, Ayesha Shajahan-Haq, Robert Clarke. Pfkfb3 inhibition significantly decreases endocrine-resistant breast cancer growth and induces necroptotic cell death [abstract]. In: Proceedings of the 2021 San Antonio Breast Cancer Symposium; 2021 Dec 7-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2022;82(4 Suppl):Abstract nr P4-02-10.