[Experimental study of the function of nuclear factor-κB-dependent epithelial to mesenchymal transition in pancreatic cancer cells under hypoxic conditions].

ABSTRACT

OBJECTIVE: To investigate the function of nuclear factor (NF)-κB in the epithelial to mesenchymal transition induced by hypoxia in pancreatic cancer cells. METHODS: For cultured pancreatic cancer cells (BxPC-3 and Panc-1) under hypoxic and normoxic conditions, the differences in the morphology were observed by optical microscope. The expression of markers of epithelial and mesenchymal phenotypes, E-cadherin, vimentin and N-cadherin, were determined by Western blot. NF-κB P65 activity was measured by electrophoretic mobility shift assay. Invasion and gemcitabine resistance of pancreatic cancer cells were evaluated in matrigel invasion assay and cell counting kit-8 assay. Both molecular and pharmacologic means of inhibiting NF-κB P65 were used in these hypoxic cells and then the above resulting phenotypes were compared with those of the control-treated cells. RESULTS: After cultured pancreatic cancer cells under hypoxic conditions for 48 h, normoxic cells exhibited a polygonal shape and formed tight clusters of cells, whereas hypoxic cells took on an elongated, fibroblastoid morphology associated with a more highly invasive character and resistance to gemcitabine; hypoxic cells exhibited an suppression of E-cadherin and increase in vimentin and N-cadherin expression. NF-κB P65 activity was elevated in hypoxic cells. On the contrary, on molecular or pharmacologic inhibition of NF-κB P65, hypoxic cells regained expression of E-cadherin, lost expression of N-cadherin, and reversed their highly invasive and drug resistant phenotype. CONCLUSIONS: Pancreatic cancer cells underwent epithelial to mesenchymal transition exposed to hypoxia, exhibited highly invasive and drug resistant phenotype. Inhibition of NF-κB P65 under hypoxic conditions, pancreatic cancer cells regained expression of E-cadherin, lost expression of N-cadherin, and reversed their highly invasive and drug resistant phenotype.