Science Buddies: "Ask an Expert"

do spontaneously immortalized cells that AREN'T transformed or cancerous up regulate htert telomerase to become this or can they do some other gene that increases telomere lengths. could they even do it by alternative lengthening of telomeres.

Mutations that upregulate telomerase activity are the only way I know for a cell to become immortalized. Without telomere replacement, a cell loses DNA with every division and eventually will die. If a cell does not divide then it would not need telomerase. If the cell could remain alive then it would in a sense be immortal--just not able to reproduce. There is a set of genes that regulate cell division and if they are shut off then a cell remains in the resting state, G0. In cancer cells the normal arrest of growth in G0 has been disrupted by mutations and the cells continue to cycle through growth, mitosis and division. Shunting them into the programmed cell death, or apoptosis pathway, is one way to cause them to stop dividing and die.