Nobiletin Affects Circadian Rhythms and Oncogenic Characteristics in a Cell-Dependent Manner

The natural product nobiletin is a small molecule, widely studied with regard to its therapeutic effects, including in models of cancer. Recently, nobiletin has also been shown to affect circadian rhythms via their enhancement, resulting in protection against metabolic syndrome. We hypothesized that nobiletin’s anti-oncogenic effects are correspondingly accompanied by modulation of circadian rhythms. Concurrently, we wished to determine whether the circadian and anti-oncogenic effects of nobiletin differed across cell culture models of cancer. In this study, we assessed nobiletin’s circadian and therapeutic characteristics to ascertain whether these effects depend on cell line, which here also vary in terms of baseline circadian rhythmicity. Three cell culture models where nobiletin’s anti-cancer effects have been studied previously were evaluated here: U2OS (bone osteosarcoma), which possesses robust circadian rhythms; MCF7 (breast adenocarcinoma), which has weak circadian rhythms; and MDA-MB-231 (breast adenocarcinoma), which is arrhythmic. We found that both circadian and anti-cancer effects following nobiletin treatment were subtle in the U2OS and MCF7 cells. On the other hand, changes were clear in MDA-MB-231s, where nobiletin rescued rhythmicity, and substantially reduced oncogenic features. Based on these results and those previously described, we posit that a positive correlation exists between nobiletin’s circadian and therapeutic effects.