The circadian clock regulates cisplatin-induced toxicity and tumor regression in melanoma mouse and human models
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Panshak P. Dakup1, Kenneth I. Porter1, Alexander A. Little1, Rajendra P. Gajula1, Hui Zhang1, Elena Skornyakov2,3, Michael G. Kemp4, Hans P.A. Van Dongen2,5 and Shobhan Gaddameedhi1,2
1Department of Pharmaceutical Sciences, College of Pharmacy, Washington State University, Spokane, WA, USA
2Sleep and Performance Research Center, Washington State University, Spokane, WA, USA
3Department of Physical Therapy, Eastern Washington University, Spokane, WA, USA
4Department of Pharmacology and Toxicology, Wright State University Boonshoft School of Medicine, Dayton, OH, USA
5Elson S. Floyd College of Medicine, Washington State University, Spokane, WA, USA
Shobhan Gaddameedhi, email: [email protected]
Keywords: circadian rhythm; DNA repair; cisplatin; toxicity; melanoma
Received: December 19, 2017 Accepted: February 10, 2018 Epub: February 20, 2018 Published: March 06, 2018
Cisplatin is one of the most commonly used chemotherapeutic drugs; however, toxicity and tumor resistance limit its use. Studies using murine models and human subjects have shown that the time of day of cisplatin treatment influences renal and blood toxicities. We hypothesized that the mechanisms responsible for these outcomes are driven by the circadian clock. We conducted experiments using wild-type and circadian disrupted Per1/2-/- mice treated with cisplatin at selected morning (AM) and evening (PM) times. Wild-type mice treated in the evening showed an enhanced rate of removal of cisplatin-DNA adducts and less toxicity than the morning-treated mice. This temporal variation in toxicity was lost in the Per1/2-/- clock-disrupted mice, suggesting that the time-of-day effect is linked to the circadian clock. Observations in blood cells from humans subjected to simulated day and night shift schedules corroborated this view. Per1/2-/- mice also exhibited a more robust immune response and slower tumor growth rate, indicating that the circadian clock also influences the immune response to melanoma tumors. Our findings indicate that cisplatin chronopharmacology involves the circadian clock control of DNA repair as well as immune responses, and thus affects both cisplatin toxicity and tumor growth. This has important implications for chronochemotherapy in cancer patients, and also suggests that influencing the circadian clock (e.g., through bright light treatment) may be explored as a tool to improve patient outcomes.
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