Differential expression of full-length and a truncated Her-2/neu oncogene receptor in prostate cancer assessed using relative quantitative RT-PCR

Overexpression of the Her-2/neu protein has been associated with prostate c ancer progression. To understand at the molecular level the nature of this overexpression and its prognostic value in prostate cancer, we studied expr ession of the full-length and an alternative-splicing, truncated Her-2/neu mRNA in normal prostate and prostate cancer tissues using relative quantita tive reverse transcriptase-polymerase chain reaction. Expression of the ful l-length Her-2/neu mRNA was upregulated twofold to threefold in 14 of 39 pr ostate cancer tissues (36%) compared with normal tissues. Expression of the truncated Her-2/neu mRNA was threefold to fivefold higher in 15 of 39 pros tate cancer samples (39%) than in normal prostate. Although overexpression of both full-length and truncated Her-2/neu mRNAs in prostate cancer correl ated with higher histologic grade and higher Gleason score, the truncated H er-2/neu showed a much more significant correlation (P < 0.001) than did th e full-length mRNA (P < 0.04), The ratio of the full-length to the truncate d Her-2/neu mRNA levels was about 3.2 in normal prostate tissue and 1.5 in prostate cancer. This is the first report of expression of the truncated He r-2/neu mRNA in the prostate, and our data further confirm the biologic het erogeneity of prostate disease.