A new study led by University of California (UC) Santa Cruz researchers has found that a protein associated with cancer cells is a powerful suppressor of the biological clock that drives the daily ("circadian") rhythms of cells throughout the body. The discovery, published online on April 30, 2015 in Molecular Cell, adds to a growing body of evidence suggesting a link between cancer and disruption of circadian rhythms, while offering new insights into the molecular mechanisms of the biological clock. The article is titled “Cancer/Testis Antigen PASD1 Silences the Circadian Clock.” The ticking of the biological clock drives fluctuations in gene activity and protein levels that give rise to daily cycles in virtually every aspect of physiology in humans and other animals. A master clock in the brain, tuned to the daily cycle of light and dark, sends out signals that synchronize the molecular clocks ticking away in almost every cell and tissue of the body. Disruption of the clock has been associated with a variety of health problems, including diabetes, heart disease, and cancer. According to Dr. Carrie Partch, a Professor of Chemistry and Biochemistry at UC Santa Cruz and corresponding author of the Molecular Cell paper, the connection between clock disruption and cancer is still unclear. "The clock is not always disrupted in cancer cells, but studies have shown that disrupting circadian rhythms in mice causes tumors to grow faster, and one of the things the clock does is set restrictions on when cells can divide," she said. The new study focused on a protein called PASD1 that Dr. Partch's collaborators at the University of Oxford had found was expressed in a broad range of cancer cells, including melanoma, lung cancer, and breast cancer.
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