Integrin-linked kinase regulates phosphatase and tensin homologue activity to promote tumorigenesis in neuroblastoma cells.

BACKGROUND: The phosphatidylinositol 3-kinase (PI3K), a critical intracellular pathway, is negatively regulated by phosphatase and tensin homologue (PTEN). Integrin-linked kinase (ILK) induces phosphorylation of Akt leading to an increase in cell survival. However, a potential interaction between ILK and PTEN activity in neuroblastoma cells is unknown. We sought to examine the relationship between ILK and PTEN in the PI3K/Akt signaling pathway in neuroblastoma tumorigenesis.
METHODS: The human neuroblastoma cell line, BE(2)-C, was transfected with small interfering or short hairpin RNA to silence ILK expression. A plasmid containing the ILK wild-type (ILK wt) gene was transfected to overexpress ILK. Cell proliferation was assessed, and anchorage independence was measured by soft agar assay. Insulin-like growth factor-1 was used to stimulate the PI3K/Akt pathway. Protein levels were determined by Western blotting.
RESULTS: Transient silencing of ILK produced correlative decreases in PTEN expression, cell proliferation, and soft agar colony formation. Conversely, stably transfected ILK knockdown cells showed an increase in phospho-Akt levels, leading to cell proliferation.
CONCLUSION: ILK plays an important role in the regulation of PI3K/Akt pathway via PTEN or an upstream effector of PTEN. The effects of ILK silencing on PTEN expression seem to be critically dependent on duration of ILK dysregulation.