Telomere length and cancer
Researchers at the University of Pittsburgh, together with colleagues from Singapore, have demonstrated that excessive telomere length – repeated sequences of nucleotides shortening at each cell division at the ends of chromosomes – is associated with an increased risk of cancer.
The authors, working under the guidance of Professor Jian-Min Yuan, analyzed blood samples and health data from more than 28,000 Chinese residents who participated in the Singapore Chinese Health Study. The health status of the participants has been monitored since 1993, and by the end of 2015, 4,060 of them had been diagnosed with malignant diseases.
The study participants were divided into 5 groups depending on how much their telomere length exceeded the expected values. When adjusted for age, gender, education level and smoking, the probability of developing cancer for the group with the longest telomeres was 33% higher than for the group with the shortest telomeres.
In addition, for this group, the risk of lung cancer was increased by 66%, breast cancer by 39%, prostate cancer by 55% and colon cancer by 37%. The most pronounced association was found for pancreatic cancer, the risk of which was 2.6 times higher in 20% of participants with the longest telomeres compared with the risk for 20% of participants with the shortest telomeres. The only malignant disease, the risk of which decreased with increasing telomere length, was liver cancer.
For three diseases, the dependence of the risk of development on the length of telomeres was described by a "U-shaped" curve, that is, an increased risk was characteristic of both people with the longest and people with the shortest telomeres. Thus, for the group with the shortest telomeres, the risk of developing stomach cancer was 63% higher, bladder cancer – 72% and leukemia – 115% compared to the group of participants whose telomere length was in the middle part of the curve. Accordingly, for the group with the longest telomeres, the risk of developing stomach cancer was increased by 55%, bladder cancer – by 117% and leukemia – by 68%.
According to Professor Yuan, there is a very complex relationship between telomere length and the development of malignant tumors. The idea of conducting such a study had already arisen more than seven years ago, but at that time the laboratory took 3 months to estimate the length of telomeres in cells of only 100 samples, which did not allow making meaningful conclusions. Less than 10 years have passed since then, and the laboratory has already managed to process almost 30,000 samples in a year. The ultimate goal of the authors' work is to obtain information that will allow identifying people most at risk of developing cancer and timely preventive measures, as well as more private screening examinations of the risk group. Moreover, in the future, the results of their work may help in the development of therapeutic approaches that contribute to maintaining the optimal telomere length for the body.
The results of the work were presented at the annual congress of the American Association for Cancer Research, held on May 1-5, 2017 in Washington.
Evgeniya Ryabtseva
Portal "Eternal youth" http://vechnayamolodost.ru Based on the materials of the University of Pittsburgh: Telomere Length Predicts Cancer Risk, According to a Large Epidemiological Study.
11.04.2017