Autocrine/paracrine regulation of breast cancer cell proliferation by growth hormone releasing hormone via Ras, Raf, and mitogen-activated protein kinase

Abstract

Although GHRH has previously been shown to regulate proliferation of breast cancer cells and prevent apoptosis, the intracellular pathways mediating this effect have not been clarified.

Exogenous GHRH stimulated a dose-dependent proliferative response within 24 h in MDA-231, as well as in T47D cells and in MCF-7 cells transfected with the GHRH receptor.

The proliferation of MDA-MB-231 (MDA-231) cells was associated with an increase in tritiated thymidine uptake. In addition, phosphorylation of MAPK was rapidly stimulated by GHRH.

The phosphorylation of MAPK by GHRH was prevented by transfection of the cells with dominant-negative Ras or Raf or by pretreatment of cells with Raf kinase 1 inhibitor.

The inhibition of Ras and Raf, as well as the inhibition of MAPK phosphorylation by PD98059, also prevented GHRH-induced cell proliferation.

Finally, pretreatment of cells with the somatostatin analog, BIM23014, also prevented GHRH-induced MAPK phosphorylation and cell proliferation.

These results indicate that GHRH stimulates dose-dependent cell proliferation of MDA-231 breast cancer cells through a pathway that requires Ras, Raf, and MAPK phosphorylation. The results also provide support for a possible autocrine/paracrine antagonism between GHRH and somatostatin in the regulation of MDA-231 cell population maintenance.

Taken together, the studies provide further insight into the possible role of GHRH as a growth factor in breast cancer.

 

About this publication.

See also:

- Official Web Site: The Di Bella Method;

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- The Di Bella Method (A Fixed Part - Somatostatin, Octreotide, Sandostatin LAR, analogues and/or derivatives);

- Somatostatin in oncology, the overlooked evidences - In vitro, review and in vivo publications;

- Publication, 2018 Jul: Over-Expression of GH/GHR in Breast Cancer and Oncosuppressor Role of Somatostatin as a Physiological Inhibitor (from Di Bella's Foundation);

- Publication, 2018 Sep: The over-expression of GH/GHR in tumour tissues with respect to healthy ones confirms its oncogenic role and the consequent oncosuppressor role of its physiological inhibitor, somatostatin: a review of the literature (from Di Bella's Foundation);

- Publication, 2019 Aug: The Entrapment of Somatostatin in a Lipid Formulation: Retarded Release and Free Radical Reactivity (from Di Bella's Foundation);

- Publication, 2019 Sep: Effects of Somatostatin and Vitamin C on the Fatty Acid Profile of Breast Cancer Cell Membranes (from Di Bella's Foundation);

- Publication, 2019 Sep: Effects of somatostatin, curcumin, and quercetin on the fatty acid profile of breast cancer cell membranes (from Di Bella's Foundation);

- The Di Bella Method (A Fixed Part - Bromocriptine and/or Cabergoline);

- The Di Bella Method (A Fixed Part - Cyclophosphamide 50mg tablets and/or Hydroxyurea 500mg tablets, one or two per day);

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- Complete objective response, stable for 5 years, with the Di Bella Method, of multiple-metastatic carcinoma of the breast;

- Evaluation of the safety and efficacy of the first-line treatment with somatostatin combined with melatonin, 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;

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- Oesophageal squamocellular carcinoma: a complete and objective response;

- 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;

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

- Congenital fibrosarcoma in complete remission with Somatostatin, Retinoids, Vitamin D3, Vitamin E, Vitamin C, Melatonin, Calcium, Chondroitin sulfate associated with low doses of Cyclophosphamide in a 14-year Follow Up.