Telomerase, Telomerase Inhibition, and Cancer

Interestingness: 3

By Ali Ahmed and Trygve O. Tollefsbol, in the Journal of Anti-Aging Medicine, December 2003, 6(4): 315-325. doi:10.1089/109454503323028911.

It didn't turn up to be as interesting as I first thought, but definitely new information regarding telomerase, mostly of the type that I'll forget by tomorrow (ie these genes upregulate this, these downregulate it). In factoid form: telomerase is present in normal human liver cells in an inactive form, c-Myc upregulates telomerase, Mad1 suppresses it.

Telomerase is probably a good thing to test for when looking for cancer since it's very commonly present, ranging from 50-90% of the tests, with the lower numbers mostly seeming from fluids from tests. It is quite rare for it to be expressed in non-cancer cells, outside of the immune system, and even when it is, the numbers are much higher in cancer cells. 

Some numbers from the paper: 90% of bladder cancers, 80% of prostate cancers, 69% of renal cancers, 82% of thyroid cancers, 95% of breast cancers.  Some studies seem to show a correlation between cancer stage and quantity of telomerase. They also mention correlation between telomerase levels in the tumour and mortality and/or recurrence.

It then talks about methods of downregulating telomerase: transfecting with a dominant negative hTERT gene, antisense on the RNA component of telomerase, and immune hammering of telomerase-positive cells. I didn't know dominant negative genes would be easy to make.  They express the usual concerns about what turning off telomerase would do to stem cells and germ cells, but say that both those types are likely to have much longer telomeres than cancer cells.