Direct inhibitory effect of somatostatin on the growth of the human prostatic cancer cell line LNCaP: possible mechanism of action

Abstract

The effects of somatostatin-14 (S) on the proliferation of the human prostatic cancer cell line (LNCaP, lymph node carcinoma of the prostate) and on the amount of proteins secreted by these cells have been studied.

LNCaP cells were treated for 3 days with different doses of S.

The hormone significantly inhibits cell proliferation at doses comprised between 0.4 and 2 nmol, as indicated by a significant decrease in the incorporation of 3H-thymidine as well as in the uptake of [alpha-32P]dATP.

The direct antiproliferative effect of S is reversible, since cell proliferation returns to normal 4 days after withdrawal of the hormone from the medium. This action of S is not due to cytotoxic side-effects, since no changes in the incorporation of 35S-methionine are observed. Total RNA and protein synthesis do not appear to be modified by the hormone in vitro.

The hormone probably exerts its antiproliferative effect on LNCaP cells by stimulating phosphotyrosyl protein phosphatases, since the inhibition of growth induced by S (1 nmol) is reversed by sodium vanadate (2 and 4 mumol), a potent inhibitor of the process of tyrosine dephosphorilation.

In addition, S (1 nmol/L) induces a significant decrease in the amounts of proteins secreted by LNCaP cells.

Also the antisecretory action of S seems to be mediated by the activation of phosphotyrosyl protein phosphatases, since sodium vanadate is able to reverse the action of S on this parameter.

In conclusion, the present data suggest for the first time that S exerts a direct inhibitory effect on LNCaP cell proliferation and protein secretion, two effects probably mediated by the activation of phosphotyrosyl protein phosphatases.

 

 

About this publication.

 

See also:

- Somatostatin in oncology, the overlooked evidences;

- The Di Bella Method (DBM) in the treatment of prostate cancer: a preliminary retrospective study of 16 patients and a review of the literature;

- Pancreatic Adenocarcinoma: clinical records on 17 patients treated with Di Bella's Method;

- The Di Bella Method Increases by the 30% the survival rate for Pancreas tumors and for this reason should be proposed as first line therapy for this type of cancer;

- Evaluation of the safety and efficacy of the first-line treatment with somatostatin combined with melatonisn, retinoids, vitamin D3, and low doses of cyclophosphamide in 20 cases of breast cancer: a preliminary report;

- The Di Bella Method (DBM) improved survival, objective response and performance status in a retrospective observational clinical study on 122 cases of breast cancer;

- Complete objective response to biological therapy of plurifocal breast carcinoma.