Can cancer even be cured?
You’ve all heard the common
refrain, “Refrain from smoking lest you develop cancer”. These days, everything
we do can be a cause for cancer – eating spicy food, using air conditioners,
eating fried food, consuming liquor, passive smoking, being exposed to UV rays
and a host of other things as well. And the worst part is, even if you remained
a teetotaller, stayed indoors, ate only fruits and generally kept away from
popularly categorized carcinogens, you still could develop cancer.
I recently
read an article on endogenous retroviruses – something that we, as a race, have
been carrying for a few million years now (even before the dawn of “mankind” as
we know it). Basically these are sequences of DNA in our somatic and germ cells
(read body cells and sperms/ova) which were once infectious retroviruses that
plagued our primeval counterparts. For all those unaware of the mechanisms of
infection of retroviruses – they are viruses that are able to integrate their
genetic material into the genome of the host they infect (I will spare you the
excruciating details! :P). So philosophically speaking, your children are part
you, part your spouse and part virus. Now imagine this process extrapolated to
a million plus years. Throw in some natural selection and other evolutionary
pressures and we have now, upto 8% of our DNA as viral DNA.
How can we be sure
that the DNA was from viruses and not from our parents? Studies have been
conducted on the proteins that are transcribed by these long stretches of DNA
that generally do not code for anything in our bodies in vivo and it was found that we exhibit genotypes (but not
phenotypes, mostly) for viral proteins. Amazing? Scary? Unbelievable? It gets
worse. These stretches of viral DNA are able to jump from one location to
another within the DNA sequence itself. They seem to be “searching for a way
out” of the evolutionary conundrum. Their integration into the host genome
wasn’t meant to last so many generations of DNA replication over so many years.
Their parasitic behaviour forces them to look for a way out of this conundrum –
they need to be able to hijack the host’s cell machinery and make the cell
transcribe their proteins. Add to this the fact that most of our cells are just
waiting for an excuse to become neoplastic (cancerous). What’s stopping them is
some segments of your DNA called “tumour suppressor genes”.
Imagine now that a
retrovirus decides to replace this gene or disrupt it in the process of jumping
around your DNA. I don’t need to spell it out for you to develop a prognosis
(once that happens). And the probability of this occurrence isn’t zero.
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