Returning Circadian Rhythm to Normal Seen to Slow Cancer Growth

Altering the biological clock of cancer cells may impact tumor growth, according to a new study published by BMC Biology. These findings could lead to novel treatments that prevent cancer proliferation.

A majority of cells in the body have a biological clock that determines the rhythm of activities in the organs. Altered circadian rhythm was previously linked to cases of cancer for individuals who work the night shift.

“Misalignment between the external and internal time and circadian disruption, such as during shift work, has been associated with an increased cancer risk and promotes tumor growth,” the study authors wrote.

Certain cancers are thought to be driven by disruptions in circadian rhythm. This is the first time that researchers have targeted the biological clock in a cancer cells, which was observed to inhibit the tumor’s development.

"There were indications suggesting that the malfunctioning clock contributed to rapid tumour [sic] growth, but this had never been demonstrated,” said researcher Nicolas Cermakian, PhD. “Thanks to the use of a chemical or a thermic treatment, we succeeded in 'repairing' these cells' clock and restoring it to its normal functioning. In these conditions, tumour [sic] growth drops nearly in half.”

While the study was conducted in mice, the study authors said that their findings show a potential new approach to treating cancer in human patients.

"Activating the biological clock in tumours [sic] could become an innovative approach in slowing their growth or that of metastases. This would give people more time to use more conventional treatment modalities, such as surgery or chemotherapy,” Dr Cermakian said. “It now remains to be shown that we can target the clocks in human tumours [sic] the same way."

In the study, the investigators altered the internal clocks of skin and colon cancer cells to make them function normally, according to the study. This adjustment was tested in both mice and cell cultures.

The researchers discovered that cancer cells with normal circadian rhythm slowed tumor growth. After only 1 week, the tumor was two-thirds smaller than a tumor with unaltered cells, according to the study.

Although it is difficult to definitively determine which cancers may be susceptible to these alterations, a new treatment approach and research could lead to novel treatments.

“Because our observations extended to human colon cancer cells, this strategy might more generally become an innovative way to slow down cancer progression and thereby improve the outcome of established anti-cancer therapies,” the study authors concluded. “Slowing down tumor progression by improving circadian rhythmicity might critically delay cancer progression and/or metastasis. This could in turn increase treatment success with traditional chemotherapy or provide a broader time window for surgical resection of tumors.”