title: Somatostatin receptor subtype mRNA expression in human colorectal cancer and normal colonic mucosae.
abstract: Somatostatin analogues may be useful novel agents in the systemic treatment of advanced colorectal cancer, as somatostatin inhibits proliferation in a wide variety of cell types. Here, we report the expression profiles of somatostatin receptor mRNAs in 32 pairs of malignant and normal colonic epithelia. Receptor subtype 2 (hSSTR2) mRNA was detected throughout nearly 90% of both malignant and normal tissue by reverse transcription-polymerase chain reaction (RT-PCR) and in situ hybridization. Subtype 5 (hSSTR5) mRNA was detected in 46% and 45% of tumour and mucosal samples respectively, but in 75% (9/12) of early-stage tumours (tubulovillous adenomas, Dukes' A and B) compared with 31% (5/16) of late-stage tumours (Dukes' C and 'D' tumours), 0.05>P>0.025 (chi2 with Yates' correction). There was also reduced expression of hSSTR5 in samples of metastatic tumour (11%, 1/9) compared with all tumour samples (56%, 18/32) 0.025>P>0.01 (chi2 with Yates' correction). Other hSSTRs (1, 3 and 4) were expressed infrequently. Thus, hSSTR2 expression is retained after malignant transformation in colonic epithelium and, although it may potentially be a target for antiproliferative therapy, its ubiquitous expression militates against this. hSSTR5 warrants investigation as a tumour suppressor.
authors.affiliation: University Department of Surgery, Southampton General Hospital, Hampshire, UK.
authors.forename: S A
authors.initials: SA
authors.lastname: Laws
authors.forename: A C
authors.initials: AC
authors.lastname: Gough
authors.forename: A A
authors.initials: AA
authors.lastname: Evans
authors.forename: M A
authors.initials: MA
authors.lastname: Bains
authors.forename: J N
authors.initials: JN
authors.lastname: Primrose
mesh_terms: D000368:Aged; D003106:Colon / Q000378:metabolism*; D015179:Colorectal Neoplasms / Q000378:metabolism* / Q000473:pathology; D017931:DNA Primers; D005260:Female; D006801:Humans; D007413:Intestinal Mucosa / Q000378:metabolism*; D008297:Male; D008875:Middle Aged; D009362:Neoplasm Metastasis; D009367:Neoplasm Staging; D016133:Polymerase Chain Reaction; D012333:RNA, Messenger / Q000096:biosynthesis; D017481:Receptors, Somatostatin / Q000096:biosynthesis* / Q000235:genetics; D012016:Reference Values; D014158:Transcription, Genetic
chemical_list: D017931:DNA Primers; D012333:RNA, Messenger; D017481:Receptors, Somatostatin