National Cancer Centre Researchers Make New Discovery On An Enzyme Function.
Monday, 7 March 2005

Singapore, 7 March 2005 - An 18-month research into the function of one of the enzymes in the human body by a research team at the National Cancer Centre Singapore (NCCS) has thrown up some startling discovery on the function of the enzyme, Telomerase. The findings, which are published as a cover story by a leading scientific publication, will help doctors to refocus on the manner in which they approach the treatment of certain cancers.

Led by Dr Kanaga Sabapathy, Principal Investigator and Associate Professor of the Division of Cellular and Molecular Research, NCCS, their discovery can help to explain why in certain cancers the treatment by chemotherapy did not get the desired results. This is because the enzyme, Telomerase, opposes the reactivity of chemotherapy, thus rendering the treatment inept to treat cancers patients.

Essentially, Telomerase is an enzyme that protects Telomeres, a protective cap at the tail-end of each chromosome, and hence ensures that Telomere length is maintained during replication. Chromosomes are "packages" of genetic information which are passed from parent to their children and are found in the nucleus of the cells. They serve as the blue print of all life functions. In order to age and grow old, our bodies must replicate their cells. However, the length of chromosomes become shorter over time as the Telomerase activity weakens upon continuous division/ replication of a cell. When the Telomere becomes too short, the chromosome reaches a 'critical length' and can no longer replicate. This is when a cell becomes 'old' and dies by a process called "apoptosis".

An enzyme is a protein that initiates biochemical reactions in the body. It also acts as a catalyst that promotes reactions repeatedly, without itself being altered in the process.

While Telomerase is hardly detectable in differentiated cells, however, it is highly expressed in stem cells, thereby ensuring that the chromosomes are replicated effectively in the stem cells. During the 18 months, Dr Sabapathy and his team at NCCS spent looking into the fundamental functions of Telomerase in a mouse embryonic stem cells.

What the team of three researchers found was that not only does Telomerase confers resistance to apoptosis, it also stymies positive effects of chemotherapy treatment. This laboratory finding is indeed a critical point to the known fact that Telomerase is essential in protecting the tail-end of chromosomes. It has been observed that Telomerase is highly active in human cancer cells than that in normal body cells. As such, it causes cancer cells to proliferate indefinitely and appears to be associated with cell immortalization.

Thus if Telomerase does indeed impede chemotherapy treatment, it explains why the treatment on some patients have not resulted in the desired results.

While the current findings is the result of a laboratory experiment, Dr Sabapathy who has honed his expertise in cultivating embryonic stem cells during his post-doctorate training in Vienna, Austria, hopes to get clinical data to further substantiate his research work so that it will spur other researchers in this field to come up with better treatments for cancer.

As for the clinical data, he would require at least 100 patients with highly expressed telomerase and another 100 patients with mildly expressed Telomerase in a specific cancer to carry out the study. The Journal of Cell Science, which is one of the key journals in the field, covers the complete range of topics in cell biology and is of key interest to developmental biologists, molecular biologists and geneticists.


For more details, photos and media interviews on the above, please click [here].