Expression of Hsp90 chaperone [corrected] proteins in human tumor tissue.

The activity of many oncogenic proteins depends on the molecular chaperone Hsp90. Recent studies indicate that tumorigenesis is associated with increased expression of chaperones, such as Hsp90. However, little is known about the isoform dependence and cochaperone contribution on tumor formation. Here we report the first systematic expression profiling for Hsp90alpha and Hsp90beta, the cochaperones Aha1, Cdc37, p23, Tpr2, and the Hsp90 dependent transcription factor HSF1 in a set of different tumor tissue samples. We find that in 10 out of 17 human tumors the expression level of at least one Hsp90 or Hsp90 cochaperone protein is significantly elevated. However, individual tumors show unique patterns of expression. Furthermore, Hsp90alpha and Hsp90beta expression levels are not related. Our results suggest that expression profiling of Hsp90alpha and Hsp90beta and its cochaperone proteins may be useful for cancer diagnosis and prognosis as well as for tailoring of drugs that interfere with the Hsp90 system in a tumor specific manner.