Somatostatin analogue RC-160 inhibits the growth of transplanted colon cancer in rats.
The effect of somatostatin analogue RC-160 on the growth of DHD/K12 rat colon cancer has been investigated in vivo as well as in vitro. Twenty syngeneic BDIX rats with s.c. implanted tumors were divided randomly into 2 groups. The rats from each group received a daily s.c. injection of either RC-160 (100 micrograms/kg/day) or injection vehicle as control for 37 days starting from the day of tumor inoculation. Tumor volumes were measured every 3-4 days. At the end of the treatment, the mean tumor volume was 504.5 +/- 97.0 mm3 in the control group and 177.8 +/- 60.5 mm3 in the RC-160 treated group (p less than 0.01). The tumor volume doubling time was calculated to be 11 days in the control group and 13.5 days in the RC-160 group, respectively. The tumor growth delay time was 18 days. Using bromodeoxyuridine labelling in vivo, the mean labelling index in the tumors was decreased by 35% (p less than 0.01) after RC-160 treatment. Total protein and total DNA contents in the tumors were decreased by 70.1% (p less than 0.05) and 68.7% (p less than 0.05), respectively. The data indicate that somatostatin analogue RC-160 inhibits the growth of DHD/K12 colon cancer in vivo. In 2 studies in vitro, DHD/K12 cells were cultured for 72 hr with RC-160 and natural somatostatin-14 (S-S-14) at concentrations ranging from 62.5 ng/ml to 2,000 ng/ml. Tumor-cell growth was measured spectrophotometrically by the crystal violet staining assay. No direct effect on tumor cell growth in vitro was observed with either RC-160 or S-S-14, possibly because of the loss of somatostatin receptors in previous passages of the DHD/K12 cell line.
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Cancer Research Unit, Faculty of Medicine, Free University of Brussels, Belgium.
Schally
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AV
Willems
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G
D000230:Adenocarcinoma / Q000188:drug therapy* / Q000378:metabolism; D000818:Animals; D000970:Antineoplastic Agents / Q000494:pharmacology*; D003110:Colonic Neoplasms / Q000188:drug therapy* / Q000378:metabolism; D004247:DNA / Q000187:drug effects; D004261:DNA Replication / Q000187:drug effects; D007279:Injections, Subcutaneous; D008297:Male; D009368:Neoplasm Transplantation; D011506:Proteins / Q000378:metabolism; D051381:Rats; D011919:Rats, Inbred Strains; D013004:Somatostatin / Q000031:analogs & derivatives* / Q000494:pharmacology; D014185:Transplantation, Isogeneic
D000970:Antineoplastic Agents; D011506:Proteins; C051458:vapreotide; D013004:Somatostatin; D004247:DNA