Far from being immortal, most cancer cells seem unable to multiply limitlessly and spread throughout the body.
of St George鈥檚 University of London and colleagues found that only four of 37 skin cancer samples they examined displayed the supposed hallmark of cancer. 鈥淲e thought they鈥檇 all be immortal, but they weren鈥檛,鈥� she says.
By studying the molecular profiles of the cancer cells as they grew in the lab, the team found that many appeared to have hit a 鈥渢elomere crisis鈥� and stopped dividing. Telomeres are the caps that protect the ends of chromosomes and they shorten every time a cell divides. In a telomere crisis, the tips become so short that the cell mistakes them for DNA breaks and tries to repair them, generating freak cells that die or become dormant.
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The team found that the few cancer cells that are immortal activate telomerase reverse transcriptase (TERT), a part of the telomerase enzyme that rebuilds telomeres so they avoid a telomere crisis.
Normally, TERT is active only in sperm or egg cells, so looking for it in a tumour could tell doctors whether the cells are immortal and more likely to spread, helping them decide on the best treatment.
Cancer vaccine
Last week, Cancer Research UK launched a trial to stop pancreatic cancer spreading with a . The body鈥檚 immune system would recognise the TERT as foreign and mobilise to attack it, bringing all pancreatic cancer cells with active TERT into the firing line too.
A vaccine that acts in a similar way against acute myelogenous leukaemia is being tested by of Menlo Park, California, which has been developing anti-cancer treatments based on telomerase for some time.
Geron also has two major trials under way in breast cancer and non-small cell lung cancer to test imetelstat, a drug that blocks the activity of TERT.
Journal reference: .
