Scientists have discovered that some Chinese people carry a gene variant that protects them against cancer. A variant of the same gene, caspase-8 (CASP8), was discovered earlier this year to afford some Western women protection from breast cancer. In US men, caspase-8 is involved in cell-signaling regulation by the androgen receptor and may play a role in prostate cancer.

In the latest issue of the journal Nature Genetics, scientists say they had studied the DNA of nearly 10,000 Chinese people over 6 1/2 years and had found that the gene variant appeared far more frequently in those who were cancer-free.

“We have identified a variant of the CASP8 gene that appears to be associated with lower risk of lung, oesophageal, gastric, colorectal, cervical and breast cancers in Chinese people,” Dongxin Lin of the Chinese Academy of Medical Sciences in Beijing wrote in an e-mail to Reuters.

It is well known that the gene caspase-8 (CASP8) regulates cell death. Programmed cell death, or apoptosis, is important because it prevents cells from dividing and spreading uncontrollably, a process that can result in cancer.

So far the researchers have looked for this gene variant in the DNA of 5,000 patients with with lung, oesophageal, colorectal, cervical, stomach and breast cancer, and 4,972 others who were cancer-free in various cancer institutes in Beijing.

The gene variant showed up in 25 per cent of those who were cancer-free, and in 20 per cent of those who had cancer.

Explaining how this gene variant might have benefited its carriers, Dr. Lin said: “Carriers may have lower apoptotic cell death of T lymphocytes (white blood cells) when they fight with malignant or premalignant cells.”

“The immune status is very important in cancer development, and genetic variation in the immune system is associated with predisposition to cancer,” Dr. Lin said.

The discovery may help identify high-risk individuals.

“The genetic variant we identified might (serve) as a genetic marker in identifying high-risk individuals, which is an important step in targeted prevention and early detection of human cancer,” Dr. Lin said.

SourceToronto Globe and Mail April 22.
Nature Genetics, April 2007.

This research opens a new, genetic perspective on worldwide cancer prevention in an era of industrial pollution, pre- and post-industrial stress and crumbling of evolved environmental health protectors like the Chinese traditional diet. As recent news reports indicate, severe industrial pollution of air, land and water plus smoking seem to be driving up cancer rates in China. Elsewhere researchers are finding gene variants which boost the protective effects of certain foods including soy and fatty fish. Swedish researchers have found a gene variant which protects men who eat marine fatty acids from prostate cancer. Salmon, Prostate Cancer and a COX-2 gene variant April 4th, 2007. Earlier this year a large population study found that a gene variant that protecvts against breast cancer is present in 13 percent of women of white European ancestry protection from breast cancer from a variant of the caspase-8 gene. And a study at M. D. Anderson suggests that in men, caspase-8 “has a novel function beyond its known role in the mediation of apoptosis,” namely, in transcriptional regulation by the androgen receptor, which “is critical for male sexual development and prostate cancer.”

The case made in the 90’s for a miracle effect from the Chinese diet is ripe for revision. Part rural paradise-lost, part genetically unexplored, the world of The China Study (Amazon.com), now much smoggier, is increasingly under the microscope.

Links:
China’s “Cancer Villages” Pay Heavy Price for Economic Progress
Published on Tuesday, May 9, 2006 by Agence France Presse