Mutation analysis of the tumor suppressor genes p16^INKA and Mxi-1 in localized prostate cancer

The p16 gene product is a negative cell cycle regulator and has been shown to be inactivated in a number of primary tumors and cell lines. Overexpression of the myc-family genes has been shown to promote cellular transformation. Myc gene transcriptional activity is regulated by the stimulating and suppressive effects of the Max and Mxi-1 proteins, respectively. Since the role of both tumor suppressor genes in prostate cancer still has not yet been defined, prostate cancer tissue and cell lines were evaluated for genetic alterations. Five metastatic prostate cancer cell lines and 38 microdissected primary tumor specimens and adjacent normal tissue were analyzed for p16 and Mxi-1 gene structure by Southern Blot analysis, polymerase chain reaction (PCR) followed by single strand conformation polymorphism analysis (SSCP) and direct DNA sequencing of samples with aberrant mobility shifts. The prostate cancer cell line Du 145 revealed the previously described missense mutation (codon 84, GAC to TAC); while 3 primary prostate cancer samples demonstrated the same p16 polymorphism, but no significant missense mutations or deletions. With regard to the Mxi-1 gene none of the cell lines, but 5/32 (15.6%) primary tumors revealed an aberrant band shift PCR-SSCP. Direct DNA sequencing demonstrated a C to T base substitution for the HLH-region. Based on the low frequency of genetic alterations, inactivation of the tumor suppressor genes p16 and Mxi-1 by deletions or mutations in the protein coding region does not seem to play a major role in the tumor genesis of localized prostate cancer. © Georg Thieme Verlag Stuttgart.

Duke Scholars

Author Judd Wendell Moul Urology