Rabbit Anti-Human SSTR3 (C-terminal) Polyclonal antibody

BACKGROUND. Despite the generally successful scintigraphic detection of endocrine tumors with [In-111]-DTPA-D-[Phe(1)]-octreotide (OctreoScan(R), Mallinckrodt Medical, Petten, The Netherlands), its intraoperative application awaits the development of suitable gamma detectors. This study describes a novel probe (H-probe2) and its ex vivo efficacy for the detection of midgut carcinoid tumors. METHODS. The probe measures 180 mm x 24 mm, and contains a bismuth germinate crystal connected to a photomultiplicator tube, a lead shield, and a tantalum collimator with an angled, 3-mm wide opening. It was characterized in a test bench utilizing solublilized In-111 and Tc-99m, and 8 fresh operative specimens containing 26 histologically verified midgut carcinoid tumors (2-40 mm) from patients exposed to OctreoScan(R). Measurements were made at 2.5-mm intervals over the entire specimens and presented three dimensionally. RESULTS. The test bench analysis supported efficient shielding, and a total collimation of 27 degrees for In-111 and 20 degrees for Tc-99m. In addition to 18 palpable tumors, 4 of 6 surgically occult tumors (2-3 mm in dimension) could be discovered with H-probe2. Small tumors in close apposition to a large tumor could not be separated. Wellcounter examination showed that tumors detected with the H-probe2 exhibited 1.7-84.1 times higher radionuclide uptake than the surrounding normal tissue. CONCLUSION. Ex vivo analysis of H-probe2 supported detection of tumors inaccessible to surgical palpation, but its clinical efficiency awaits intraoperative evaluation. (C) 1997 American Cancer Society.

The transcripts of five SRIH receptor subtypes (SSTR1, SSTR2, SSTR3, SSTR4, and SSTR5) were investigated by RT-PCR in epithelial cells (EC) and stromal cells (SC) from primary cultures of five normal human prostates and six prostate cancers. Primary cultures of prostate EC were established in serum-free keratinocyte medium with 5% FCS, epidermal growth factor, and bovine pituitary extract; SC were cultured in MEM with 10% FCS. Total RNA was extracted from EC and SC using a modified guanidine thiocyanate method. RT-PCR was performed after deoxyribonuclease treatment, using SSTR1-, SSTR2- SSTR3-, SSTR4-, and SSTR5-specific primers and adding glyceraldehyde-3-phosphate dehydrogenase-specific primers as internal control. A PCR product of the expected size of 334 bp, corresponding to SSTR1. was expressed only in EC from prostate cancer, whereas the expected 461-bp product of SSTR2 was found only in EC from normal prostate. SSTR3 messenger RNA was undetectable in not mal and cancer EC, whereas SSTR4 and SSTR5 were present in both cell types. SSTR1, SSTR2, SSTR3, SSTR4, and SSTR5 messenger RNAs were not expressed in SC from both normal and cancer prostates, The RT-PCR method clearly demonstrated SSTRs' expression in the human prostate EC in vitro with differences between normal and tumoral samples. Our results may explain the ineffectiveness of some SSTR2 selective SRIH analogues in the treatment of prostate cancer and suggest that the absence of SSTR2 could represent a growth advantage in prostate cancer.