[Activation of phosphatidylinositol 3-kinase in human breast carcinoma].

Background & Objective: Phosphatidylinositol 3-kinase (PI3-K) has been implicated in the signaling pathways regulating cell growth by virtue of its activation in response to various mitogenic stimuli, but the role of PI3-K in human tumorigenesis has not yet to be defined. This study was designed to investigate the levels of both PI3-K protein and PI3-K mRNA and the activity of PI3-K in human breast tumors.

Methods: Western blot, immunoprecipitation, kinase activity assay, and RT-PCR were used to detect the expression and activity of PI3-K in 37 patients with breast cancers.

Results: Significantly increased expression of p85 subunit of PI3-K at levels of both protein and mRNA were found in 32 (86.49%) and 35(94.59%) out of the 37 breast tumors compared with adjacent normal tissue. Significantly higher level of the activity of PI3-kinase was observed in 25(67.57%) out of the 37 cases.

Conclusions: PI3-K was highly activated in breast tumor tissue compared with adjacent normal tissue, suggesting that PI3-K was involved in the signal transduction of breast tumorigenesis. It may be a potential target for new strategies for the treatment of the patients with breast cancers.