Expression of somatostatin receptor subtypes in breast carcinoma, carcinoid tumor, and renal cell carcinoma.

The presence of transcripts for somatostatin receptor (SSTR) subtypes 1, 2, 3, and 4 was probed by reverse transcription and polymerase chain reaction in ribonucleic acid isolated from 46 malignant and 9 nonmalignant breast tissues, 15 carcinoid tumor tissues, and 13 renal cell carcinoma tissues. The transcripts for SSTR2 were amplified in all but 2 tissue samples, whereas transcripts for SSTR1, SSTR3, and SSTR4 were detected sporadically. In renal cell tumors, SSTR3 transcripts were completely absent. In breast cancer tissue, SSTR subtypes were transcribed independently of patient age, menstrual status, diagnosis, histological grade, and levels of estrogen receptor and progesterone receptor. The probability of finding transcripts for SSTR subtypes, P, was ranked differently for the three types of tumor tissues. For breast cancer, P2 > P3 = P1 > P4; for carcinoid tumors, P2 > P1 > P3 = P4; and for renal cell tumors, P2 > P1 > P4 > P3.