Epigallocatechin-3-Gallate Decreases Hypoxia-Inducible Factor-1 in Pancreatic Cancer Cells.

Abstract

Hypoxia-inducible factor-1 (HIF-1) is an [Formula: see text]/[Formula: see text] heterodimeric transcription factor. In normal mammalian cells, HIF-1[Formula: see text] is hydroxylated and degraded upon biosynthesis. However, HIF-1[Formula: see text] is frequently expressed in cancer and adds to cancer malignancy. In this study, we investigated whether green tea-derived epigallocatechin-3-gallate (EGCG) decreased HIF-1[Formula: see text] in pancreatic cancer cells. After MiaPaCa-2 and PANC-1 pancreatic cancer cells were exposed to EGCG in vitro, we performed a Western blot to determine native and hydroxylated HIF-1[Formula: see text], which was in turn used to assess HIF-1[Formula: see text] production. In order to assess HIF-1[Formula: see text] stability, we determined the HIF-1[Formula: see text] after MiaPaCa-2 and PANC-1 cells were switched from hypoxia to normoxia. We found that EGCG decreased both production and stability of HIF-1[Formula: see text]. Further, the EGCG-induced decrease in HIF-1[Formula: see text] reduced intracellular glucose transporter-1 and glycolytic enzymes and attenuated glycolysis, ATP production, and cell growth. Because EGCG is known to inhibit cancer-induced insulin receptor (IR) and insulin-like growth factor-1 receptor (IGF1R), we created three MiaPaCa-2 sublines whose IR, IGF1R, and HIF-1[Formula: see text] were decreased using RNA interference. From wild-type MiaPaCa-2 cells and these sublines, we found evidence that suggested that the EGCG-induced inhibition of HIF-1[Formula: see text] was both dependent on and independent of IR and IGF1R. In vivo, we transplanted wild-type MiaPaCa-2 cells in athymic mice and treated the mice with EGCG or vehicle. When the resulting tumors were analyzed, we found that EGCG decreased tumor-induced HIF-1[Formula: see text] and tumor growth. In conclusion, EGCG decreased HIF-1[Formula: see text] in pancreatic cancer cells and sabotaged the cells. The anticancer effects of EGCG were both dependent on and independent of IR and IGF1R.