Dopamine receptor D3 is related to prognosis in human hepatocellular carcinoma and inhibits tumor growth

Abstract

Background: Dopamine receptors have been reported to play important roles in cancer progression. However, the role of dopamine receptor D3 (DRD3) in hepatocellular carcinoma (HCC) remains unclear.

Methods: The expression of DRD3 was detected by immunohistochemistry and real-time qPCR. The prognostic value of DRD3 in patients was investigated by analyzing selected databases, including cBioPortal and Kaplan-Meier plotter. Cell growth was tested by CCK8 assay, and Transwell assays were performed to assess cancer cell migration and invasion. The cAMP/ERK/CREB signaling pathway was evaluated by Western blot analysis and ELISA. An HCC xenograft model was established for in vivo experiments.

Results: DRD3 mRNA expression was significantly higher in nontumor tissues than in tumor tissues. Lower protein expression of DRD3 was related to poor recurrence-free survival (RFS) and overall survival (OS). Kaplan-Meier plotter analysis showed that higher expression of DRD3 mRNA was associated with better OS, RFS, disease-specific survival (DSS), and progression-free survival (PFS). cBioPortal analysis revealed that the alteration group, which harbored genetic mutations in DRD3, exhibited poor OS, RFS, DSS and PFS. According to CCK8 and Transwell assays, stable DRD3 overexpression cell line (ex-DRD3-SK-HEP-1) showed weaker proliferation, migration and invasion behaviors. PD128907, a DRD3 agonist, suppressed proliferation, migration and invasion in HCC cell lines, while U99194, a DRD3 antagonist, enhanced proliferation, migration and invasion in HCC cell lines. Western blot analysis and ELISA revealed that stable DRD3 knock-down cell line (sh-DRD3-PLC/PRF/5) and U99194 both increased the protein levels of cAMP, p-ERK and p-CREB; on the other hand, ex-DRD3-SK-HEP-1 and PD128907 decreased the protein levels of cAMP, p-ERK and p-CREB. SCH772984, an ERK antagonist, abolished the effect of U99194 on the malignant biological behaviors of HCC cells. In vivo, PD128907 suppressed tumor growth, and U99194 enhanced tumor growth.

Conclusion: Our results suggest that down-regulation of DRD3 is strongly involved in the progression of HCC, and DRD3 might be consider as an independent prognostic factor for HCC. Furthermore, DRD3 agonists may be a promising strategy for HCC therapy.

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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, 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);

- 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 Synergism of Somatostatin, Melatonin, Vitamins Prolactin and Estrogen Inhibitors Increased Survival, Objective Response and Performance Status In 297 Cases of Breast Cancer;

- 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;

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

- 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;

- 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;

- A retrospective observational study on cases of anaplastic brain tumors treated with the Di Bella Method: A rationale and effectiveness;

- 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;

- Neuroblastoma: Complete objective response to biological treatment.