4 ms·

However, people die of cancer (especially if untreated...) So does this mean that without this shortening of the telomeres, the incidence of cancer would be mu

However, people die of cancer (especially if untreated...) So does this mean that without this shortening of the telomeres, the incidence of cancer would be much larger? That the cancers that actually manifest are a small fraction of the potential cancers aborted by this defense mechanism?

maxander 11y ago
Indeed- and there's many other, separate defence mechanisms that also quash cancers before they become a problem. If a tumour has grown enough to threaten, it has evolved workarounds to at least several of these.
toufka 11y ago
Absolutely. You have 'rogue' cells that go on independent replication programs all the time. But there are a few checkpoints which are no-go if a cell passes them - they are immediately forced to die. These include, short telomeres, lack of proper DNA repair, and ability to respond to induced-suicide signals. In order for an otherwise 'cancerous' cells to be a problem, it really has to have developed processes that ignore ALL of these (few) checkpoints. The chance that the particular mutation in that cell includes a mutation to overcome ALL of those hurdles simultaneously in a single cell is the chance you develop (a harmful) cancer. A change to nearly any other gene will cause one of those checkpoints to kick in and force the cell to die. The DNA damage checkpoint is interesting all the way through public health policy in 2 cases: 1) The BRCA gene is a DNA repair protein. Women with a mutated brca gene are missing one of those 3 checkpoints. 2) HPV (for which we have a complete vaccine) is of a type of virus that is generally destroyed by your DNA-repair machinery. However HPV, being evolutionary wily, has a specific mechanism to shut down your own DNA repair machinery that would otherwise catch the foreign invader. Hence, HPV 'causes cancer' by deliberately disabling one of those checkpoints.
akiselev 11y ago
I can't name the research on this topic off of the top of my head, but yes to both questions. Cancer is a common occurence in all mammals and we have evolved many self defense mechanisms, including telomeres, to fight it as animals started living longer and longer. One of the most promising areas of oncology research is immunotherapy, for example, which guides your immune system to attack cancer cells that havent been recognized as targets.

maxander 11y ago

Indeed- and there's many other, separate defence mechanisms that also quash cancers before they become a problem. If a tumour has grown enough to threaten, it has evolved workarounds to at least several of these.

toufka 11y ago

Absolutely. You have 'rogue' cells that go on independent replication programs all the time. But there are a few checkpoints which are no-go if a cell passes them - they are immediately forced to die. These include, short telomeres, lack of proper DNA repair, and ability to respond to induced-suicide signals. In order for an otherwise 'cancerous' cells to be a problem, it really has to have developed processes that ignore ALL of these (few) checkpoints. The chance that the particular mutation in that cell includes a mutation to overcome ALL of those hurdles simultaneously in a single cell is the chance you develop (a harmful) cancer. A change to nearly any other gene will cause one of those checkpoints to kick in and force the cell to die. The DNA damage checkpoint is interesting all the way through public health policy in 2 cases: 1) The BRCA gene is a DNA repair protein. Women with a mutated brca gene are missing one of those 3 checkpoints. 2) HPV (for which we have a complete vaccine) is of a type of virus that is generally destroyed by your DNA-repair machinery. However HPV, being evolutionary wily, has a specific mechanism to shut down your own DNA repair machinery that would otherwise catch the foreign invader. Hence, HPV 'causes cancer' by deliberately disabling one of those checkpoints.

akiselev 11y ago

I can't name the research on this topic off of the top of my head, but yes to both questions. Cancer is a common occurence in all mammals and we have evolved many self defense mechanisms, including telomeres, to fight it as animals started living longer and longer. One of the most promising areas of oncology research is immunotherapy, for example, which guides your immune system to attack cancer cells that havent been recognized as targets.