Gene links breast cancer to stress and body clock

A gene involved in suppressing tumours has been shown to link breast cancer to stress and an irregular body clock.

The findings, published in Cancer Cell International, have important implications for the health of nightshift workers and frequent international travellers, who likely have disrupted sleeping schedules, as this may make them more susceptible to developing breast cancer.

'Circadian disruption is an emerging driver of breast cancer, with epidemiological studies linking shift work and chronic jet lag to increased breast cancer risk,' the authors said.

The study's corresponding author, Dr Pia Bagamasbad, institute director of the University of the Philippines Diliman's National Institute of Molecular Biology and Biotechnology, and her student Weand Ybañez focused their study on the gene Krüppel-like factor 9 (KFL9) – a gene that reduces tumour growth – and its link to breast cancer risk and development.

The researchers found that KFL9 is less active in breast tumours than in normal breast tissue. Moreover, they found that the gene's activity is affected by stress and changes in the circadian rhythm, or the body's internal clock.

The circadian rhythm is a 24-hour cycle that is controlled by a 12-hour light-dark cycle. Maintaining a healthy circadian rhythm is essential to regulate normal bodily functions, such as the sleep cycle, digestion and hormone signalling.

Typically, under a healthy circadian rhythm, the activity of KFL9 follows an oscillating pattern in normal breast tissue. However, in aggressive breast cancer, or under the influence of stress hormones and disrupted circadian rhythm, this oscillating pattern is lost and the gene is unable to suppress tumour growth.

Although the researchers did not discover the KFL9 gene, their study, according to their knowledge, was the first to suggest that there is a direct link between the mechanism controlled by the KFL9 gene and breast cancer development.

Moreover, their findings further support the International Agency for Research on Cancer's 2019 classification of night shift work as another probable risk factor for cancer.

Additionally, since the KFL9 gene interferes with oestrogen signalling, disruptions in circadian rhythm further increase cisgender and transgender women's risk of developing breast cancer because of the higher amounts of oestrogen in their bodies.

'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,' explained Dr Bagamasbad regarding her study's findings.

She adds that there is a 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.'