Since when is cancer not caused by mutation?

I feel a major rant about epigenetics coming on… must hold it back until a more convenient time. But I can’t refrain from commenting on just how wrong this is:

“We used to think that cancer was caused mainly by mutations of genes, but we now believe that epigenetic aberrations are responsible for more than half of cancer cases,” says Trygve Tollefsbol, who is a senior scientist at the University of Alabama at Birmingham’s Comprehensive Cancer Center.

“That’s an important change because genetic mutations are very difficult, if not impossible, to correct, while epigenetic marks are potentially reversible,” he explains.

– Nutrition Action HealthLetter, July/Aug 2013, p. 10

I’ve heard a lot of BS claims made in the name of epigenetics, but this one takes the cake. Can anyone point me to an instance of any cancer that does not involve mutations? And where is the evidence that “more than half of cancer cases” are not caused by mutations? Anyone?

(And if you haven’t read this, you should: Mark Ptashne, “Epigenetics: core misconcept” Proc Natl Acad Sci U S A. 2013 Apr 30;110(18):7101-3.)

NOTE: The article is not online yet, but comes from a big story on epigenetics in the July/Aug issue of the Nutrition Action Health Letter.

Advertisements

2 responses to “Since when is cancer not caused by mutation?

  1. Richard Sever

    You’re right to call BS on this – a ridiculous claim (for the record, I tend to agree with Ptashne on ‘epigenetics’). But isn’t it possible non-DNA changes are drivers in a small percentage of cancers, plus should we draw a distinction between mutations ‘causing’ versus ‘being involved’ in cancer? Epigenetic silencing of MMR enzymes, for example, could be the initial cause, leading to mutations that fuel cancer progression. Vogelstein touches on the issue in a recent Science review (http://www.sciencemag.org/content/339/6127/1546), mentioning that silencing of some tumor suppressors is more common than mutation. Could it be that epigenetic changes aren’t responsible for >50% of cancers but do cause >0%?

    • I’m with you on this – I guess I would phrase it this way: it’s likely that some non-mutational events create a highly favorable environment for some cells to accumulate driver mutations. Some of Kevin Struhl’s recent work suggests a mechanism for how something like that could happen. (Of course the appropriate caveat about the cell lines used in these experiments applies.

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s