EVALUATION AND SMALL MOLECULE MODULATION OF CIRCADIAN RHYTHMS IN CELLULAR MODELS OF CANCER

Circadian rhythms are innate biological time tracking systems that regulate protein expression to help organisms adapt to the time of day. These time-dependent mechanisms control multiple functions in the body, including sleep and wakefulness, body temperature, blood pressure, hormone production, digestive secretions, and immune activity. Alterations to circadian rhythms via shift-work, exposure to bright lights at night, or other conditions, can profoundly impact human health. Both epidemiological analyses and animal studies have revealed that disruptions to circadian rhythms contribute to a variety of malignancies, including cancer development and severity. This association can be rationalized by the critical roles of circadian-controlled genes in the cell cycle, DNA damage response, angiogenesis, and cell proliferation. However, prior molecular studies have only approximated the relationship between cancer and circadian rhythms via coarse evaluations of core clock genes and their overexpression or deletion. Here, chemical and biological methods are used to study the connection(s) between altered circadian rhythms and cancer. Luciferase reporters, whose expression is driven by the promoters of core clock genes, are used to track their unique oscillations in various cancer models. These reporter constructs have been introduced into breast cancer cell lines representing different stages and subtypes of the disease. Their resulting expression profiles are characterized via multiple computation algorithms. I have broadly found that the oscillations of two core clock genes, Bmal1 and Per2, are disrupted differently and affected to a greater extent with increasing disease malignancy. Further, I have modulated circadian rhythms in reporter models by using small molecule effectors. I assessed and compared their effects on oscillations and phenotypic characteristics. Molecules affecting rhythms to greater extents had enhanced influences on cellular characteristics, and the abilities of these molecules to affect oscillations was independent of whether they directly or indirectly target the core clock. Taken together, this study provides insights into the analyses of altered circadian rhythms in breast cancer and describes the influence of small molecule modulation of clocks on oncogenic behaviors