Stem cell factor modulates HIF-1α levels and diminishes 5-FU sensitivity in 5-FU resistant pancreatic cells by altering the anabolic glucose metabolism.

Abstract

Resistance to chemotherapy in cancer leads to poor therapeutic outcomes and also leads to challenges in treatment. The present work evaluated the mechanism involved in the resistance of 5-flurouracil (5-FU) in pancreatic cancer. At least 14 different pancreatic cancer (PC) cell lines were used for the study. For in vivo study female nude mice were selected. Patient-derived tumor xenograft samples were obtained from patients. The study involved, study for glucose uptake, fluorescence-activated cell sorting for glucose transporter, 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide for cell survival, Picto-micrography for clonogenic assay, glutamine uptake assay, extracellular acidification and oxygen consumption rate, carbon dioxide release assay and lactate assay were also done. In addition to this, quantitative real-time polymerase chain reaction analysis for expression of genes, chromatin immunoprecipitation assay, western blot for protein expression, and immunohistochemical analysis in tumor sections, the tumors were studied by imaging for hypoxia and localization of TKT and CTPS-2. Also, patient-derived xenograft tumors were engrafted in nude mice, followed by a glucose uptake assay. We reported that elevated glycolytic flux causes dependence on glucose in cancer cells and, at the same time, increases pyrimidine biosynthesis. It was also found that stem cell factor-mediated stabilization of hypoxia-inducible factor-1a (HIF-1α) modulates the resistance in PC. Targeting HIF-1α in combination with 5-FU, strongly reduced the tumor burden. The study concludes that stem cell factor modulates HIF-1α and decreases the sensitivity in 5-FU resistant pancreatic cancer cells by targeting glucose metabolism. Deceased expression levels of CTPS-2 and TKT, which are regulators of pyrimidine biosynthesis could better the chance of survival in patients of pancreatic cancer receiving treatment of 5-FU.