Abstract 5087: Carvedilol prevents skin cancer independently of its antioxidant property

Abstract

Carvedilol is an FDA approved β-blocker traditionally prescribed for cardiovascular diseases. Our previous work demonstrated that carvedilol has preventive activity against ultraviolet radiation (UVR)-induced skin damage, inflammation, and carcinogenesis. However, the photoprotective mechanism for carvedilol remains unknown. Interestingly, not all β-blockers have cancer preventive activity, suggesting that targeting the β-adrenergic receptors may not be responsible for carvedilol’s anticancer activity. Since carvedilol has been shown as a potent antioxidant and such property is not shared by majority of other β-blockers (e.g., metoprolol), we hypothesized that the antioxidant property may be, in part, responsible for carvedilol’s protective activity against photocarcinogenesis. The nontumorous mouse epidermal JB6 P+ cells were subjected to various doses of UVR exposure and H2O2 treatment to identify the optimal doses to examine protective activity. UVR and H2O2dose-dependently reduced cell viability. 25mJ/cm2 UVR and 100 μM H2O2 reduced cell viability detected by Trypan blue exclusion assay to 58.1% and 60.6%, respectively. 25mJ/cm2 UVR and 300 μM H2O2 increased the formation of intracellular fluorescent 29,79-dichlorofluorescein (DCF) fluorescence, a marker of reactive oxidative species (ROS) detected by flow cytometry, to 5- and 4-fold compared to non-treated control, respectively. The cells were treated before or after UVR and H2O2 exposure with metoprolol, carvedilol or 4-hydroxycarbazole (4-OHC). 4-OHC is an intermediate compound for carvedilol synthesis that possesses an identical UV absorption profile as carvedilol. Additionally, the carbazole moiety is likely responsible for the antioxidant activity of carvedilol. Carvedilol, but not metoprolol and 4-OHC, was able to inhibit EGF-induced JB6 transformation in soft agar. Carvedilol, but not metoprolol and 4-OHC, also attenuated UVR and H2O2 induced cell death. Carvedilol, but not 4-OHC, inhibited UVR-induced NF-κB and AP-1 promoter activity. In addition, unlike carvedilol, 4-OHC failed to prevent chronic UVR induced skin carcinogenesis in SKH-1 mice. However, 4-OHC and carvedilol similarly attenuated UVR- and H2O2-induced ROS formation in JB6 P+ cells, while metoprolol had no effect. These results indicate that the photoprotective effects of carvedilol are primarily due to an unknown mechanism that is independent of β-adrenergic receptors and reactive oxygen species scavenging. Citation Format: Mengbing Chen, Sherry Liang, Bradley Andresen, Ying Huang. Carvedilol prevents skin cancer independently of its antioxidant property [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 5087.