Expression of sst(3) and sst(5) was observed in 89 and 76% of tumours respectively with highly variable levels. sst(2) mRNA expression was higher in nonfunctional tumours (P < 0.009) and sst5 was higher in pancreatic than in intestinal tumours (P < 0.02).
VEGF and tumor vascularization were identified as novel targets for sst2-mediated antitumoral bystander effect. sst3 somatostatin receptor was upregulated in sst2-transfected tumors.
Moreover, they further indicate that the presence of sst1 and sst3 transcripts might be used as an additional criterion to distinguish between seminoma and nonseminoma tumors.
The comparison of SRIF receptor expression between normal tissue and seminoma tumors thus points to a selective loss of sst3 and sst4 mRNA expression in seminomas.