Abstract 1833: KLF4 regulates metabolic homeostasis in response to energy stress

Abstract

Kruppel-like factor 4 (KLF4) is a zinc finger-containing transcription factor with diverse regulatory functions in cellular growth, proliferation, differentiation, autophagy and genomic stability. Furthermore, KLF4 exerts a cell-cycle checkpoint effect in part by acting as a transcriptional activator of the cyclin-dependent kinase inhibitor, p21. Our lab has found that KLF4 regulates autophagy, mitophagy, and mitochondrial dynamics. Given the close relationship these processes have with cellular metabolism, we aimed to determine how KLF4 regulates glycolytic and oxidative metabolism. Using various assays, we find that cells lacking KLF4 have both oxidative and glycolytic impairments. Using western blotting, we find that when KLF4 is overexpressed in RKO human colorectal cancer cells, Hexokinase 2 (HK2), a rate determining enzyme in glycolysis, PKM2, a facilitator of lactate production, and MCT4, a lactic acid export protein and marker of glycolysis, are all significantly upregulated. In MEFs, we find that GLUT1, a glucose transport protein, has greater expression in WT than Klf4-null cells. Furthermore, we determined that KLF4 regulates aspects of the basal cell metabolism in a p21-dependent manner. Given that KLF4 has been found to act as an immediate early gene in response to certain stresses, and given the importance of fast metabolic shifts, we also look at how KLF4 influences short term metabolic stress responses. Since metabolic stress tests showed that WT MEFs have an increased glycolytic capacity, we investigate whether the cells have an increased ability to quickly intake glucose in response to particular stresses. Accordingly, we looked at GLUT1 expression and membrane localization with respect to KLF4. Immunostaining in RKO and MEFs suggests that KLF4 plays a role in localizing GLUT1 to the outer membrane, allowing for increased glucose intake. Taken together, our findings provide a rationale for the impaired metabolism of KLF4-null MEFs, where KLF4 plays a role responding to energy stress by modifying the localization of GLUT1, and regulating various metabolic enzymes both directly, and in a p21-dependent manner. Citation Format: William M. Rosencrans, Zachary H. Walsh, Andrew C. Blum, Engda G. Hagos. KLF4 regulates metabolic homeostasis in response to energy stress [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 1833.