IDENTIFICATION OF 2 DISTINCT DELETED REGIONS ON CHROMOSOME-13 IN PROSTATE-CANCER

Aberrations of 13q occur frequently in prostate cancer and this chromo some contains two known tumor suppressor genes, BRCA2 and Rb1. This st udy analysed 13q LOH, DNA ploidy, BRCA2 mutation and pRb expression in prostate cancers, In total, 13q deletions were found in 18 of 36 tumo rs but did not correlate with histological grade, stage or DNA ploidy. Two smallest regions of overlapping deletions were defined: one flank ed by D13S218 and D13S153; the other flanked by D13S31 and D13S137. BR CA2 was less frequently deleted ,whereas Rb1 did have a high frequency of deletion. None of the two genes was located in any of these two re gions, Furthermore, BRCA2 mutation was not found in the five tumors wh ere deletions had involved the BRCA2 locus, Neither did the Rb1 deleti on correlate with absent pRb expression. In addition, tetraploidy was found in 14 out of 25 tumors analysed and correlated with aberrant pRb expression. Our results indicate that 13q deletion is an early non-ra ndom event, Tumor suppressor genes other than BRCA2 or Rb1 may be the target of 13q deletions. Aberrant pRb expression was not reflect the t yro-hit Rb1 inactivation but may be involved in the tetraploidization of prostate cancer cells.