Correlation of Beta-2 Adrenergic Receptor Expression in Tumor-Free Surgical Margin and at the Invasive Front of Oral Squamous Cell Carcinoma

Expression pattern and clinical significance of beta 2-adrenergic receptor in oral squamous cell carcinoma: an emerging prognostic indicator and future therapeutic target

PURPOSE

Beta 2-Adrenergic Receptor (β2-AR) is significantly overexpressed in various types of malignancies, which is associated with the worst prognosis. However, the role of β2-AR in oral cancer is not well identified. The present study aimed at investigating the β2-AR gene expression and its significance in relation with the clinicopathological features and overall survival of oral squamous cell carcinoma (OSCC) patients.

METHODS

Immunohistochemistry, western blot and quantitative real-time PCR techniques were used to analyze β2-AR protein and mRNA levels in a total of 65 histopathologically confirmed OSCC tissues (case group) and 65 normal tissues (control group) from the oral cavity.

RESULTS

Out of the total of 65 OSCC tissues, 41 tissues (63.1%) exhibited  high expression  for β2-AR protein. Percent positivity and relative density (mean ± SD) of protein were higher in the case group as compared to the control group (positivity 40.31 ± 3.01 vs. 20.46 ± 1.93, p < 0.001; density 2.77 ± 1.17 vs. 1.28 ± 0.37, p < 0.001). In addition, β2-AR mRNA level was also upregulated in patients compared to the controls (2.36 ± 1.30 vs. 1.09 ± 0.42, p < 0.001) and showed a positive correlation with immunostaining of protein in OSCC (r = 0.48, p = 0.011). High β2-AR protein expression was significantly associated with multiple risk habits (p = 0.045), histological differentiation (p = 0.013), clinical TNM stages (p = 0.014), and poor survival (p = 0.006) of patients. In the Cox proportional hazards model, β2-AR was identified as a prognostic biomarker of OSCC (p = 0.047).

CONCLUSION

β2-AR protein level is identified as an independent significant prognostic factor in patients with oral carcinoma.

Beta adrenergic receptor activation inhibits oral cancer migration and invasiveness

OBJECTIVE

The aim of this study was to verify β2-AR expression in oral squamous cell carcinoma cell lines (SCC-9 and SCC-25), and to investigate the role of this receptor in migration and invasion of these neoplastic cells.

DESIGN

SCC-9 and SCC-25 cells were investigated for gene and protein expression of β2-AR. Cell migration and invasion were analyzed by wound healing assay and transwell invasion camera system. Different concentrations (0.1, 1 and 10 μM) of norepinephrine were used to stimulate, and 1 μM propranolol was used to block the beta-adrenergic receptors on cancer cells. Differences in median values of SCC-9 and SCC-25 and β2-AR protein expression were analyzed by Friedman test and in case of significant differences; pairwise comparisons were performed using Bonferroni correction.

RESULTS

The results showed that the β2-AR gene and protein expression were observed in both oral cancer cell lines. The concentration of 10 μM of norepinephrine significantly inhibited (p ≤ 0.05) migration of SCC-9 and SCC-25 cell lines. Furthermore, there was a significant reduction (p ≤ 0.05) in the effect of norepinephrine on cell migration when the β2-AR was inhibited by propranolol. The blockade by propranolol showed a tendency to reverse the effect of norepinephrine on the invasiveness of SCC-9 and SCC-25.

CONCLUSIONS

The use of beta-adrenergic receptor agonists could become an adjuvant therapeutic target in the treatment of this malignancy.

Overexpression of β-Adrenergic Receptors and the Suppressive Effect of β2-Adrenergic Receptor Blockade in Oral Squamous Cell Carcinoma

PURPOSE

The purpose of this project was to investigate the expression of β-adrenergic receptors in oral squamous cell carcinoma (OSCC) and the tumor suppressive activity of β₂-adrenergic receptor (β₂-AR) blockade.

MATERIALS AND METHODS

Samples of 15 normal oral mucosal epithelial tissues, 60 surgically resected OSCC tissues, and 60 adjacent para-carcinoma tissues were collected. The expression of β₁-adrenergic receptor and β₂-AR was detected by real-time quantitative polymerase chain reaction and the Western blot test. SCC9 and Cal27 cell lines and primary OSCC cells also were included and treated with ICI-118,551 (MedChemExpress, Monmouth Junction, NJ), a selective β₂-AR blocker. In addition, the Cal27 cell line was treated with propranolol (a nonselective β-adrenergic receptor blocker) to verify the suppressive effect of β₂-AR blockade. For in vivo assays, Cal27 cells were subcutaneously injected in the tongue flank of nude mice. ICI-118,551 was orally administered to the mice in the treatment group daily. High-throughput sequencing was used to screen for changes in gene expression.

RESULTS

Real-time quantitative polymerase chain reaction and the Western blot test both showed that β₁-adrenergic receptor and β₂-AR were overexpressed in OSCC tissues and cells. A relationship was found between β₂-AR and a more advanced clinical stage, as well as preoperative lymphatic metastasis. After treatment with ICI-118,551 or propranolol, the capacities for proliferation, invasion, and metastasis of OSCC cells were significantly inhibited. Tumor size was significantly different between the ICI-118,551 and control groups. The survival time in the ICI-118,551 group also was prolonged significantly. Moreover, high-throughput sequencing identified 19 affected signaling pathways, including mitogen-activated protein kinase and PI3K-Akt. We confirmed a significant change to the expression of several genes closely related to the progression of cancer.

CONCLUSION

This study showed that β₂-AR is related to a more advanced clinical stage and preoperative lymphatic metastasis. Additionally, a β₂-AR blocker has a significant suppressive effect in OSCC.