Protein kinase Cα suppresses the expression of STC1 in MDA-MB-231 breast cancer cells.

Several protein kinase C (PKC) isoforms have been shown to influence different cellular processes that may contribute to the malignancy of breast cancer cells. To obtain insight into mechanisms mediating the PKC effects, global gene expression was analyzed in MDA-MB-231 breast cancer cells in which PKCα, PKCδ or PKCε had been down-regulated with siRNA. Gene set enrichment analyses revealed that hypoxia-induced genes were enriched among genes that increased in PKCα-down-regulated cells. The STC1 mRNA, encoding stanniocalcin 1, was particularly up-regulated following depletion of PKCα and was also induced by hypoxia. Both hypoxia and PKCα down-regulation also led to increased STC1 protein levels. The results demonstrate that PKCα suppresses the expression of STC1 in breast cancer cells.