Can We Devise A Clock To Predict Cancer Risk?

Using a mitotic ‘clock,’ researchers have shown that DNA changes in normal cells could be used to predict the risk of cancer.

AsianScientist (Nov. 8, 2016) – Researchers in China and the UK shown how DNA changes that accrue in normal cells as a result of lifetime cell divisions could be used to predict cancer risk. Details of their study were published in Genome Biology.

The rate at which cells in a given tissue divide is thought to determine the risk of that tissue turning cancerous. The research undertaken by Professor Andrew Teschendorff from CAS-MPG Partner Institute for Computational Biology, Shanghai and University College London, UK and colleagues used an in-silico mathematical approach to construct a ‘clock’ which approximates the number of lifetime cell divisions of cells in a tissue of an individual.

To measure the tick-rate of this mitotic clock, the researchers focused on a specific chemical modification of DNA, called DNA methylation, which accrues as a person ages. However, such a clock can’t be used for cancer risk prediction since different organs from the same person have different propensities to develop cancer, yet they all have the same chronological age.

By measuring DNA methylation at specific genomic loci, Teschendorff and his team were able to construct a different kind of clock, which does not predict chronological age, but predicts the underlying number of stem cell divisions in a tissue.

The authors demonstrate how the tick-rate of their mitotic clock is universally accelerated in cancer, including pre-cancerous lesions from the breast and lung. Importantly, the authors show how the tick-rate of this mitotic clock is increased in normal cells exposed to smoke carcinogens, thus linking exposure to a cancer risk factor with an increased mitotic rate mediated by inflammation.

According to the authors, one exciting possibility for the research is to estimate the tick-rate of this mitotic clock in cell-free DNA shed by precancerous cells in blood plasma.

The article can be found at: Yang et al. (2016) Correlation of an Epigenetic Mitotic Clock with Cancer Risk.


Source: Chinese Academy of Sciences; Photo: Pixabay.
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