Malek Zihlif
University of Jordan, Jordan
Title: Gene expression changes in metabolic and hypoxic related genes in response to long term hypoxia in MCF7 breast cancer cell line
Biography
Biography: Malek Zihlif
Abstract
Hypoxia is a feature of most tumors and consider as a negative prognostic and predictive factor because of its role in the chemoresistance, radioresistance, angiogenesis, invasiveness, metastasis and resistance to cell death. Around 40% of all breast cancer and half of the locally advanced breast cancers include regions aff ected by hypoxia. Th is study was designed to simulate real hypoxic conditions as much as possible with the aim of characterizing the gene expression changes in metabolic and hypoxic related genes in response to long term hypoxia in MCF7 breast cancer cell line. Th e MCF7 breast cancer cells
were exposed to hypoxia episodes (1% oxygen) in two diff erent patterns. Th e fi rst was to expose the cells to 8 hours of hypoxia every other day with a total of 60 eposides and the second was to expose the cells to 72 hours of hypoxia every week for a total of 20 weeks. RNA was extracted at diff erent intervals in the two patterns and gene expression level was determined for the targeted genes. Regarding the hypoxic pathway genes, marked changes were identifi ed aft er both patterns of hypoxia. Half of the genes (12 genes) that shown remarkable changes were common to both conditions. Th ose common genes include the insulin-like growth factor binding protein 3, tumor protein p53 and endothelin-1. However, there was a very interesting observation regarding the gene expression of a gene called the hepatocyte nuclear factor 4, alpha (HNF4A) gene that was the most up-regulated genes in both cases scoring 32 folds aft er 60 hypoxic shots and 14 folds aft er 10 shots of 72 hypoxic shots.
Such changes in HNF4 were confi rmed using western blotting. Regarding the metabolic pathway changes, again some changes were observed giving a clear indication for switch from using glucose pathway as a scours of power toward using a diff erent pathway called pentose phosphate pathway. In conclusion, a collective gene expression data on diff erent long term hypoxic pattern fi rstly proposed HNF4A as a potential biomarker in tumor hypoxia and a major player in MCF7 breast cancer cell response to chronic hypoxia and secondly, indicate a switch in the normal metabolic pathway toward a new adapted pentose
phosphate pathway.