High Expression of PhospholipaseD2 Induced by Hypoxia Promotes Proliferation of Colon Cancer Cells through Activating NF- κ Bp65 Signaling Pathway

Hypoxia is a typical feature of colon cancer occurrence and progression. We have reported that high expression and activity of PhospholipaseD2 (PLD2) induced by hypoxia in colon cancer cells. In order to further investigate the role of PLD2 in colon cancer under hypoxic conditions. MTT assay was used to detect the proliferation of human colon cancer cells (SW480 and SW620) under hypoxic conditions by decrease the PLD2 gene expression or inhibit the activity of PLD2. Expression level of p-P65/T-P65 and Cyclin D1 were detected in those cells treated as above through using western blot and RT-PCR analysis. Effect of NF-Bp65 inhibitor (BAY-117082) on the proliferation and expression level of Cyclin D1 and PLD2 of colon cancer cells under hypoxic conditions were further analysised. As a result, decreased the expression of PLD2 or inhibited the activity of PLD2 leaded to the proliferation of hypoxia colon cancer cells reduced, and along with the expression level of p-P65/T-P65 and Cyclin D1 reduced. However, inhibition the expression level of p-P65/T-P65 lead to the proliferation and expression of Cyclin D1 in those hypoxia colon cancer cells also reduced. In vivo growth decreased in response to PLD2 and NF-Bp65 inhibition. Our study indicates that high expression of PLD2 induced by hypoxia promotes the proliferation of colon cancer cells, and it may elevate the expression level of Cyclin D1 through activating NF-Bp65 signaling pathway. Inhibition of the PLD2 expression may provide a new clue for treatment for colon cancer.