The skin and hair as surrogate tissues for measuring the target effect of inhibitors of phosphoinositide-3-kinase signaling.

Background: The purpose of the study was to evaluate the use of phospho-Akt in mouse and human skin as a surrogate target for tumor phospho-Akt to measure the effect of antitumor inhibitors of phosphatidylinositol-3-kinase (PI-3-K)/Akt (protein kinase B) signaling.

Method: The expression of phosphoSer473-Akt was quantitatively assessed by Western blotting in human HT-29 colon, MCF-7 breast, A-549 non small cell lung tumor xenografts in mice, and by immunohistochemistry in mouse skin and human hair.

Results: The pattern of PI-3-K isoforms in human hair keratinocytes was similar to that in tumor but mouse hair keratinocytes showed a different pattern.