Friday, June 28, 2013

Focus on: Telomeres and Cancer

Telomeres are the protective extensions on the end of chromosomes which shorten during the life of a cell each time it divides. Without these protective extensions the chromosome would lose genetic material and be susceptible to fusion with other chromosomes. Usually the shortening of the telomere is a signal to end the lifespan of a cell through senescence or cell death. However, in cancer cells; telomeres are shorter than in normal cells but are maintained at a constant short length by telomerase. Telomerase is an enzyme that adds length to the telomeres which allows the cells to continue to grow.

An image showing how telomerase elongates
telomeric DNA progressively

Fatma Uzbas
A research group from Japan was curious why cancer cells had shorter telomeres than normal cells. They published the results of there studies in the recent Molecular and Cellular Biology paper entitled 'Telomere length influences cancer cell differentiation in vivo'. In the paper they elongated the telomeres of human prostate cancer cells by enhancing telomerase activity. The result was cancer cells that had long rather than short telomeres. These cells retained the ability to form tumors, however, they had hallmarks of a more differentiated cell and lacked the expression of genes associated with poor prognosis cancers. The authors conclude short telomeres contribute to the malignancy of the tumor by affecting differentiation of the cancer cells and propose a potential role for telomeres in normal cell differentiation.