Cancer-Related Glycolytic Gene:Regulation and Targeting

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DESCRIPTION (provided by applicant): This application focuses on the regulation and targeting of the gene that encodes Type II hexokinase, a major player in the growth and pathogenesis of many cancers. This enzyme is essential for maintaining the most common biochemical signature of cancers, i.e., their capacity to metabolize glucose at high rates. Cancers expressing this phenotype are usually the most malignant, growing rapidly and frequently becoming metastatic. The overexpressed Type II hexokinase in such cells promotes their rapid growth and survival even under hypoxic conditions. Significantly, during the past progress period we provided evidence that epigenetic factors, i.e., demethylation and methylation may be important for respectively turning the Type II hexokinase gene on and off; that hypoxic conditions + glucose provide maximal activation; that much of the strength of the promoter lies in the region encompassing the transcription start site; and that antisense hexokinase RNA can inhibit markedly tumor cell growth in culture. Finally, using an animal model for liver cancer, we showed in a test study that the alkylating agent 3-bromopyruvic acid can arrest tumor growth by targeting directly (via intraarterial injection) both Type II hexokinase and mitochondrial ATP synthesis. This work has provided a strong foundation for the future Specific Aims of this project that are threefold: 1. Elucidate the molecular basis of those transformation-related epigenetic events that completely demethylate the CpG island encompassing the transcription start site and "switch on" the Type II hexokinase gene. 2. Identify the hypoxia sensitive element(s) within the CpG island of the Type II hexokinase gene and evaluate the effect of hypoxic stress both on the methylation pattern and on the expression of Type II hexokinase. 3. Assess the relative therapeutic efficacies of RNA and chemical based agents targeted to Type II hexokinase in a liver cancer/lung metastasis rabbit model. Considering that FDG-PET, now commonly used worldwide to detect cancer and monitor its treatment, is based largely on elevated expression levels of hexokinase, it would seem that numerous cancers in human patients may be markedly promoted by this enzyme. In this light, the basic work proposed here that focuses both on identifying the underlying mechanisms that silence and promote Type II hexokinase and in identifying novel agents that inhibit it, may help turn the tide on our losing war on cancer.