DNA from 45 primary prostate
tumors and corresponding normal tissues were analyzed to detect whether the alterations of
transforming growth factor beta receptor II (TGFbetaRII) and
insulin growth factor receptor II (IGFRII) are associated with
microsatellite instability (MSI). We identified that 25
tumors were microsatellite unstable (55%). The remaining 20
tumors are found to be microsatellite stable. Loss of heterozygosity (LOH) was also tested at various loci. Results indicate that in case of TGFbetaRII, the rate of frame-shift mutation depends on the number of
polyadenine [
poly(A)] tracts. Twelve percent of the
tumors had frame-shift alteration at BAT-RII locus which has 10
poly(A) repeats. Twenty percent of the
tumors had frame-shift at BAT-25 locus which has 25
poly(A) repeats. In addition, IGFRII gene was examined for the presence of mutation in the repetitive sequences. Seven of the 25
tumors showed deletion of a G within eight
poly(G) repeats. Besides these changes there were two
tumors which showed a novel insertion of A within this
poly(G) repeat making a change in 9 samples (R4, 36%). On the other hand, 4
tumors showed changes within the 5CT repeats. In addition, 3
tumors showed another novel insertion of C within the CT repeats.