Preventing UV-induced immunosuppression and skin carcinogenesis with R-carvedilol

Skin cancer, particularly non-melanoma skin cancer, is by far the most common malignancy in the US. Overexposure to ultraviolet (UV) radiation is a main factor causing skin cancer, via inducing DNA damage, inflammation, and immunosuppression. The β-adrenergic receptor (β-AR) antagonist (β-blocker) carvedilol, a commonly used drug for cardiovascular disorders, has shown promising activity in preventing UV-induced skin cancer in vitro and in vivo. However, as a highly potent β-blocker, systemic absorbtion of carvedilol may cause unwanted cardiovascular effects such as bradycardia and hypotention. To overcome this obstacle, two strategies are applied: (1) development of a skin targeting nanodelivery system, and (2) examination of the effects of the non-β-blocking R-carvedilol enantiomer, because carvedilol is a racemic mixture consisting of the β-blocking S- carvedilol and non-β-blocking R-carvedilol in 1:1 ratio. Preliminary data indicate that topical delivery of carvedilol loaded nano-transfersome was able to effectively prevent skin cancer without systemic absorption. Additional data indicate that β-blockade is dispensable for carvedilol's cancer preventive activity. Further preliminary studies indicate that R-carvedilol, although not a β-blocker, is effective in preventing UV-induced immunosuppression and skin carcinogenesis without affecting blood pressure. Importantly, both R- and S- carvedilol inhibit ryanodine receptors (RyRs) by reducing the opening time of this intracellular calcium channel, and further preliminary data suggest that reducing RyR opening activity represents a previously unexplored mechanism for skin cancer prevention. Thus, the overall objective of this application is to determine the molecular target for carvedilol-mediated chemoprevention and examine a novel nanodelivery system of R- carvedilol as an effective and safe approach for skin cancer prevention. Aim 1 is to test the hypothesis that carvedilol prevents cancer independently of β-blockade. Aim 2 is to test the hypothesis that reducing RyR activity mediates carvedilol's cancer preventative activity. Aim 3 is test the hypothesis that R-carvedilol can be formulated in nano-transfersome gel which can be safely and repeatedly applied to the skin without significant systemic absorption. Since carvedilol is an FDA-approved agent, we anticipate the outcomes from this project will be readily translated into a cancer preventive regimen for healthy human subjects or individuals with weakened immune system. Importantly, R-carvedilol, lacking β-blocking activity, is expected to prevent cancer without cardiovascular disturbance, and therefore should be an excellent drug for skin cancer chemoprevention.