Hexokinase 2 is targetable for HK1 negative, HK2 positive tumors from a wide variety of tissues of origin

Abstract

Although absent in most adult tissues, hexokinase 2 (HK2) is expressed in a majority of tumors and contributes to increased glucose consumption and to in vivo tumor ¹⁸F-FDG PET signaling. Methods: Both HK2 knockdown and knockout approaches were used to investigate the role of HK2 in cancer cell proliferation, in vivo xenograft tumor progression and ¹⁸F-FDG tumor accumulation. BioProfiler analysis monitored cell culture glucose consumption and lactate production; ¹⁸F-FDG PET/CT monitored in vivo tumor glucose accumulation. Cancer Cell Line Encyclopedia data were analyzed for HK1 and HK2 expression. Results: Neither cell proliferation in culture nor xenograft tumor progression are inhibited by HK2 knockdown or knockout in cancer cells that express HK1 and HK2. However, cancer subsets from a variety of tissues of origin express only HK2, but not HK1. In contrast to HK1+HK2+ cancers, HK2 knockdown in HK1-HK2+ cancer cells results in inhibition of cell proliferation, colony formation and xenograft tumor progression. Moreover, HK1KOHK2+ cancer cells are susceptible to HK2 inhibition, in contrast to their isogenic HK1+HK2+ parental cells. Conclusion: HK1 and HK2 expression are redundant in tumors; either can provide sufficient aerobic glycolysis for tumor growth; despite a reduction in ¹⁸F-FDG PET signal. Therapeutic HK2 inhibition is likely to be restricted to HK1-HK2+ tumor subsets, but stratification of tumors that express HK2, but not HK1, should identify tumors treatable with emerging HK2 specific inhibitors.

Keywords: Glycolysis; Hexokinase 1; Hexokinase 2; Molecular Biology; Oncology: General; PET; Targeted Therapy; Warburg Effect.