Growth hormone-releasing hormone induced transactivation of epidermal growth factor receptor in human triple-negative breast cancer cells
Abstract
Triple-negative breast cancer (TNBC) is a subset of breast cancers which is negative for expression of estrogen and progesterone receptors and human epidermal growth factor receptor-2 (HER2). Chemotherapy is currently the only form of treatment for women with TNBC.
Growth hormone-releasing hormone (GHRH) and epidermal growth factor (EGF) are autocrine/paracrine growth factors in breast cancer and a substantial proportion of TNBC expresses receptors for GHRH and EGF.
The aim of this study was to evaluate the interrelationship between both these signaling pathways in MDA-MB-468 human TNBC cells.
We evaluated by Western blot assays the effect of GHRH on transactivation of EGF receptor (EGFR) as well as the elements implicated.
We assessed the effect of GHRH on migration capability of MDA-MB-468 cells as well as the involvement of EGFR in this process by means of wound-healing assays.
Our findings demonstrate that in MDA-MB-468 cells the stimulatory activity of GHRH on tyrosine phosphorylation of EGFR is exerted by two different molecular mechanisms: i) through GHRH receptors, GHRH stimulates a ligand-independent activation of EGFR involving at least cAMP/PKA and Src family signaling pathways; ii) GHRH also stimulates a ligand-dependent activation of EGFR implicating an extracellular pathway with an important role for metalloproteinases.
The cross-talk between EGFR and GHRHR may be impeded by combining drugs acting upon GHRH receptors and EGFR family members.
This combination of GHRH receptors antagonists with inhibitors of EGFR signalling could enhance the efficacy of both types of agents as well as reduce their doses increasing therapeutic benefits in management of human breast cancer.
The Di Bella's Method: Use of Somatostatin/Octreotide analogues and/or derivatives (since 1977), Melatonin (1974), Retinoids (40mg per day Beta-Carotene, 10mg per day ATRA and 10mg per day Axerophthol palmitate), Estrogen therapy (Anastrozole 1 mg tab per day), pseudo-Metronomic Chemotherapy Cyclophosphamide and/or Hydroxyurea with Cabergoline and/or Bromocriptine (together with others chemical compounds) in (TN)Breast Cancer (the dosage and administration schedule must be individualised for each patient):
- Complete objective response to biological therapy of plurifocal breast carcinoma;
See also:
- Official Web Site: The Di Bella Method;
- 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, 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);
- Publication, 2020 Sep: Two neuroendocrine G protein-coupled receptor molecules, somatostatin and melatonin: Physiology of signal transduction and therapeutic perspectives (from Di Bella's Foundation);
- The Di Bella Method (A Fixed Part - Bromocriptine and/or Cabergoline);
- Prolactin inhibitors in oncology - In vitro, review and in vivo publications;
- The Di Bella Method (A Fixed Part - Calcium, 2 grams per day, orally);
The Di Bella's Method: Use of Somatostatin/Octreotide analogues and/or derivatives since 1977 associated with pseudo-Metronomic Chemotherapy Cyclophosphamide and/or Hydroxyurea - together with others chemical compounds: the dosage and administration schedule must be individualised for each patient - in several Oncological Pathologies:
- Pleural Mesothelioma: clinical records on 11 patients treated with Di Bella's Method;
- Malignant pleural mesothelioma, stage T3-T4. Consideration of a case study;
- Neuroblastoma: Complete objective response to biological treatment;
- Large B-cells Non-Hodgkin's Lymphoma, Stage IV-AE: a Case Report;
- Non-Hodgkin's Lymphoma, Stage III-B-E: a Case Report;
- Oesophageal squamocellular carcinoma: a complete and objective response;
- Pancreatic Adenocarcinoma: clinical records on 17 patients treated with Di Bella's Method;






