Dopamine receptor expression and function in corticotroph ectopic tumors

Abstract

BACKGROUND: Dopamine receptor (DR) expression and dopamine agonist (DA) effectiveness have never been demonstrated in neuroendocrine tumors associated with ectopic ACTH syndrome (EAS).

AIM: The aim of the current study was to evaluate DR and particularly D2 subtype expression in neuroendocrine tumors associated with EAS and to evaluate the in vivo effectiveness of the DA cabergoline in the treatment of EAS.

PATIENTS AND METHODS: Six ACTH-secreting neuroendocrine tumors, including four lung, one pancreatic, and one thymic carcinoid, were used for the evaluation of D2 expression by immunohistochemistry. DR subtypes and D2 isoforms and number were evaluated by RT-PCR in three cases of persistent EAS after surgery. These patients were treated with cabergoline at the dose of 3.5 mg/wk for 6 months. Clinical parameters, hormonal levels, and tumor size were monitored during the treatment period.

RESULTS: At immunohistochemistry, D2 was expressed in five (83.3%) tumors. At RT-PCR, D2 was confirmed in all three cases but at variable numbers, whereas D4 was expressed in two cases. D(2long) was expressed in all three cases, together with D(2short) in one case. A normalization of urinary cortisol levels was found in two patients (66.7%) after 3 months of treatment. However, treatment escape was demonstrated in one of these patients afterward.

CONCLUSION: The results of this study demonstrated that DR are expressed in neuroendocrine tumors associated with EAS and that cabergoline treatment could be effective in controlling cortisol excess in a subgroup of patients with EAS. Further studies on a larger number of patients are mandatory to confirm the usefulness of DA in EAS.

 

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See also:

- Official Web Site: The Di Bella Method;

- 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);

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

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

- Somatostatin, retinoids, melatonin, vitamin D, bromocriptine, and cyclophosphamide in advanced non-small-cell lung cancer patients with low performance status;

- Somatostatin, retinoids, melatonin, vitamin D, bromocriptine, and cyclophosphamide in chemotherapy-pretreated patients with advanced lung adenocarcinoma and low performance status;

- Observations on the Report of a case of pulmonary adenocarcinoma with lymph node, hepatic and osseus metastasis;

- 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;

- Oesophageal squamocellular carcinoma: a complete and objective response;

- Neuroblastoma: Complete objective response to biological treatment;

- Recurrent Glioblastoma Multiforme (grade IV – WHO 2007): a case of complete objective response achieved by means of the concomitant administration of Somatostatin and Octreotide – Retinoids – Vitamin E – Vitamin D3 – Vitamin C – Melatonin – D2 R agonists (Di Bella Method – DBM) associated with Temozolomide;

- The Di Bella Method DBM improved survival objective response and performance status in a retrospective observational clinical study on 23 tumours of the head and neck.