Question

Hi, I need some clarification on the effect on telomerase, aging and cancer. Could telomerase therapy trigger cancerous growth?

Answer 1

Each time a chromosome is copied (i.e., DNA is replicated and a cell divides), the proteins that copy the DNA stop copying the DNA just before the end of the strand. This happens because they physically need to bind to the DNA on both sides of the nucleotide they are copying - they can't do this for the last few nucleotides on the end of the chromosome because there isn't enough space on the other side for them to grasp.

So each time DNA is copied, the ends of the chromosomes (telomeres) get shorter.

There is some evidence that this process, telomere shortening in successive rounds of cell division, is related to ageing. Telomeres are basically nonsense DNA - they don't code for any proteins. But eventually, when they get eaten through, the cell starts losing relevant (i.e., coding) DNA and that starts to affect the cell's biologic integrity.

Telomerase therapy aims to prevent this process. So yeah, it would prevent ageing.

In some cancers (which undergo rapid rounds of DNA replication and cell division more or less indefinitely), some cells keep their telomeres intact. So there is some evidence that using telomere therapy to maintain the cell's dividing potential (possibly stopping ageing) would put it in common with tumour cells.

That said, I wouldn't go for telomere therapy, even if it were well developed or widely available. With each round of cell division cells accumulate copy mistakes - mutations. When they accumulate too many mutations they become cancerous. Telomere shortening sort of imposes a natural limit on how many times a cell can undergo division, thus on how many mutations it can accumulate, and reduces their chances of accumulating enough to become cancerous.

Answer 2

telomerase enzyme also causes cancer cell to be immortal .