Abstract 4074: The effects of the HIF pathway inhibitor NSC-134754 on glucose metabolism
Authors: Baker Lauren CJ , Chung Yuen-Li , Boult Jessica KR , Ashcroft Margaret A. , Robinson Simon P. 
Published: July 2012

The master regulator in hypoxic cell survival and adaptation is the hypoxia-inducible factor-1 (HIF-1) pathway. Altered HIF-1 regulated gene expression drives a tumour towards a more malignant phenotype. HIF-1 is thus a therapeutic target, and small molecule inhibitors such as NSC-134754 are being investigated. Glucose transporter 1 (GLUT-1) is an important downstream target of the HIF-1 pathway, with fundamental roles in intracellular glucose flux and availability. Given the intrinsic role of GLUT-1 in glucose metabolism, the ability of NSC-134754 to evoke a unique metabolic response in vitro and in vivo was investigated.

Human PC3LN5 prostate tumour cells were treated with 7.5µM NSC-134754 and incubated in a humidified hypoxic workstation (1.0% O2) for 24h. Western blot analysis demonstrated a reduction in GLUT-1 expression in treated cells compared to controls. GLUT-1 immunocytofluorescence confirmed control cells exhibited extensive membranous and diffuse cytoplasmic expression compared to treated cells.

Culture media and cell extracts were collected and metabolites analysed using 1H magnetic resonance spectroscopy (MRS). A significant decrease in glucose consumption (p&lt;0.01) and lactate production (p&lt;0.05) in NSC-134754 treated cells compared to control was determined. No significant differences in intracellular lactate concentration were found. However, treatment significantly increased intracellular glucose by &gt;3 fold compared to control cells (p&lt;0.01). Glutamine/glutamate metabolism was also significantly increased in NSC-134754 treated cells (p&lt;0.05).

Mice bearing established (∼1cm diameter) orthotopic PC3LN5 prostate tumours were treated with either 100mg/kg i.p. NSC-134754 (n=4) or vehicle alone (n=5) for 24h. Subsequent semi-quantitative immunohistochemical analyses revealed a significant 28 ± 2% decrease in GLUT-1 membrane expression in the treated tumours compared to controls (p&lt;0.01).

These data suggest that NSC-134754 has a profound effect on glucose metabolism in vitro and in vivo. Treatment of PC3LN5 cells for 24h in hypoxia significantly reduced the expression and distribution of GLUT-1, decreased glucose uptake and reduced lactate production. A reduction in glucose transport and lactate production have been shown to be indicators of response to therapy. The increased uptake and metabolism of glutamine/glutamate may reflect compensatory mechanisms for reduced glycolysis in order to sustain cellular bioenergetics. Interestingly, we have also shown that NSC-134754 increased intracellular glucose accumulation. Many glycolytic enzymes are known gene targets of HIF, thus a reduction in their availability (and hence glycolysis) could lead to glucose trapping. To our knowledge, this is a novel finding of a small molecule inhibitor of the HIF pathway. Increased intracellular glucose with decreased glucose uptake has been reported with other therapeutics in vitro.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 4074. doi:10.1158/1538-7445.AM2011-4074