Differential effects of somatostatin and its analog on protein tyrosine kinases activity in the rat pituitary and the murine colonic tumors.

The effects of the native somatostatin-14 (SST-14) and of its analog octreotide (OCT) on the activity of protein tyrosine kinases (PTK) in the normal rat anterior pituitary gland, diethylstilbestrol (DES)-induced rat pituitary tumor and murine colonic cancer Colon 38 were studied in vitro. PTK activity was estimated in tissue homogenates using gamma-[32P]ATP and poly (Glu80, Tyr20) as a substrate. It was found that both SST-14 and OCT suppressed the PTK activity in all examined tissues. The suppressive effect was more pronounced in DES-induced pituitary tumor than in normal anterior pituitary gland, and in the former, OCT was more effective than SST-14. In contrast, SST-14 stronger suppressed PTK activity in colonic cancer than OCT. We hypothesize that SST-14 acts on PTK activity in colonic cancer mainly via SSTR-1 subtype of somatostatin receptors.

[1]  A. Kulig,et al.  The effect of somatostatin analog octreotide on diethylstilbestrol-induced prolactin secretion, cell proliferation and vascular changes in the rat anterior pituitary gland. , 1997, Histology and histopathology.

[2]  H. Niznik,et al.  The somatostatin receptor family. , 1995, Life sciences.

[3]  D. Hoyer,et al.  Classification and nomenclature of somatostatin receptors. , 1995, Trends in pharmacological sciences.

[4]  G. Bell,et al.  Stimulation of tyrosine phosphatase and inhibition of cell proliferation by somatostatin analogues: mediation by human somatostatin receptor subtypes SSTR1 and SSTR2. , 1994, Proceedings of the National Academy of Sciences of the United States of America.

[5]  E. Krenning,et al.  The role of somatostatin and its analogs in the diagnosis and treatment of tumors. , 1991, Endocrine reviews.

[6]  A. Schally,et al.  Somatostatin analogues inhibit growth of pancreatic cancer by stimulating tyrosine phosphatase. , 1989, Proceedings of the National Academy of Sciences of the United States of America.

[7]  P. Greengard,et al.  Protein Tyrosine Kinase Activity and Its Endogenous Substrates in Rat Brain: A Subcellular and Regional Survey , 1988, Journal of neurochemistry.

[8]  A. Schally,et al.  Stimulation by somatostatin of dephosphorylation of membrane proteins in pancreatic cancer MIA PaCa‐2 cell line , 1985, FEBS letters.

[9]  S. Ohnishi,et al.  A simplified method of quantitating protein using the biuret and phenol reagents. , 1978, Analytical biochemistry.

[10]  M. Pawlikowski,et al.  Differential effects of somatostatin analogues on proliferation of murine colonic cancer cells in vitro. , 1997, Cytobios.

[11]  M. Pawlikowski,et al.  Inhibition of rat pituitary tumor cell proliferation by benzodiazepines in vitro. , 1994, Neuroendocrinology.