Telomeres and Cancer
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20.5.08
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You are here: Home » Pathology Notes » Telomeres and Cancer
Cellular senescence describes the fact that normal cells continually divide but reach a stage (after fixed number of divisions) where they become arrested in a nondividing state. What determines this termination? Actually, at the ends of chromosomes there are specialised structures known as telomeres. Each time a cell divides, the telomeres shorten – and if they shorten beyond a certain limit – then the cell cannot divide any more. Germ cells can divide continually, so how are they able to do it? The enzyme telomerase prevents the shortening of the telomeres, therefore termination of cell division does not occur. So, when germ cells differentiate into their specialised variety – the telomerase enzymes become deactivated/absent – therefore are susceptible to cellular senescence.
How does all this relate to tumour growth?
Well, tumour growth can occur continually and rapidly. So the concept of cellular senescence does not work here.
How come, don’t tumour cells derive from normal host cells?
Yes they do – but tumour cells can reactivate telomerase – therefore can prevent telomere shortening.
Category: Pathology Notes
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