RESUMO
PURPOSE: Beta-adrenergic signaling can influence cancer progression and the use of beta blockers as adjuvant drugs in oncologic patients has been suggested. However, the involvement of beta-adrenergic blockers in tumorigenesis is poorly understood. This study investigated the action of beta-adrenergic blocker propranolol on tumor onset using a preclinical model of chemically induced oral cancer. METHODS: Thirty-two male Wistar rats were subjected to daily subcutaneous injection of beta-blocker propranolol (10 mg/kg; SubQ), while another 32 rats received only a PBS injection (sham group). One week after starting propranolol treatment, all rats were submitted to chemical induction of oral carcinogenesis with 4-nitroquinoline-1-oxide (4NQO). After 16 weeks, they were assessed for occurrence of oral squamous cell carcinoma (OSCC), in addition to measurement of tumor volume and thickness, and tissue levels of cytokines IL-6, TNF-alpha and IL-10 in the tumor microenvironment. RESULTS: Propranolol treatment reduced the occurrence of OSCC by 31%, 95% CI ( - 127, 216). Beta-adrenergic blocker significantly decreased thickness of OSCC when compared with PBS. Rats treated with propranolol exhibited a lower tumor volume when compared with control rats, but this result did not reach statistical significance. Tumors from propranolol-treated rats exhibited reduced concentrations of pro-inflammatory cytokines IL-6 and TNF-α. There was no difference in the IL-10 levels between tumors from propranolol- and sham-treated rats. CONCLUSION: Beta-adrenergic signaling may be one of the mechanisms associated with chemically induced oral carcinogenesis.
