Altered light-dark cycle and stress hormones may be risk factors for breast cancer, UP scientists find

Published: March 1, 2023

By: Timothy James M. Dimacali

NIMBB researchers have just discovered a gene called Krüppel-like factor 9 (KLF9) that links the effects of stress, regulation of the light-dark cycle, and breast cancer. (Image credit: Weand Ybañez)

New research from the University of the Philippines – Diliman College of Science (UPD-CS) has found a conclusive link between stress, altered light-dark cycles—such as in the cases of night shift workers and frequent international travelers—and breast cancer.

Molecular biologist Dr. Pia Bagamasbad and her student, Weand Ybañez, at the UPD-National Institute of Molecular Biology and Biotechnology (NIMBB) discovered a gene called Krüppel-like factor 9 (KLF9) that functions to suppress tumor growth and links the effects of stress, regulation of the light-dark cycle,  and breast cancer. In their study, the researchers found that KLF9 is downregulated in breast tumors compared to normal breast tissue,  and that KLF9 expression  is under the regulation of stress hormones and oscillates with the 12h light-dark cycle.

Normal body function involves a regular 24-hour pattern of biological activity, called the “circadian cycle,” which is mainly controlled by the 12-hour light-dark cycle that, in turn, regulates several bodily functions such as the sleep-wake cycle, digestion, and the release and suppression of various hormones at particular times of the day.

In normal breast tissue, the researchers found that KLF9 exhibits a cyclical oscillation pattern indicative of a normally-functioning circadian cycle. However, the regular oscillatory pattern of KLF9 expression is lost in highly aggressive breast cancer. Given that KLF9 functions to suppress the growth and spread of breast cancer cells, these findings are the first to provide evidence for KLF9 in the consequential link between stress hormones and alterations in the circadian cycle, such as in lack of sleep, towards breast cancer risk and progression.

The NIMBB research team underscored the  value of maintaining a regular circadian cycle  in their study, warning of the negative effects of disruptions in the regularity of the circadian rhythm : “Circadian disruption is an emerging driver of breast cancer, with epidemiological studies linking shift work and chronic jet lag to increased breast cancer risk,” they noted in their research paper, which was published just last February 23 in the journal, Cancer Cell International.

“These findings have potential far-reaching implications not just on our understanding of how cancer develops and spreads, and how it can be effectively managed, but more importantly emphasize the need for  policies  and interventions that can safeguard the overall health and wellness of women working in industries  involving disruption in the regular circadian cycle”, Dr. Bagamasbad said.

For more information on the NIMBB study, please contact Dr. Pia Bagamasbad at

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Ybañez, W. S., & Bagamasbad, P. D. (2023). Krüppel-like factor 9 (klf9) links hormone dysregulation and circadian disruption to breast cancer pathogenesis. Cancer Cell International, 23(1).