Notch signaling pathway suppresses mRNA expression of hexokinase 2 under nutrient-poor conditions in U87-MG glioma cells.

Control of nutrient homeostasis plays a central role in cell proliferation/survival during embryonic development and tumor growth. Activation of the Notch signaling pathway, a major contributor to cell-cell interactions, is a potential mechanism for cell adaptation to nutrient-poor conditions. Our previous study also demonstrated that during embryogenesis when nutrients such as glutamine and growth factors are potentially maintained at lower levels, Notch signaling suppresses mRNA expression of hexokinase 2 (hk2), which is a glycolysis-associated gene, in the central nervous system. However, whether and how the genetic regulation of HK2 via Notch signaling contributes to cellular adaptability to nutrient-poor environments remains unknown. In this study, we performed gene expression analysis using a U87-MG human glioma cell line and revealed that under conditions where both glutamine and serum were absent, Notch signaling was activated and HK2 expression was downregulated by Notch signaling. We also found that Notch-mediated HK2 suppression was triggered in a Notch ligand-selective manner. Furthermore, HK2 was shown to inhibit cell proliferation of U87-MG gliomas, which might depend on Notch signaling activity. Together, our findings suggest the involvement of Notch-mediated HK2 suppression in an adaptive mechanism of U87-MG glioma cells to nutrient-poor conditions.