molecule of the day: benzopyrene

The molecule of the day is benzopyrene:

(PubChem)

It's a carcinogen found in tobacco smoke, among other things, and can be used to induce lung tumors in mice when injected into the peritoneal cavity (tummy), as in this paper, the star of today's Center for Metabolism and Obesity Research journal club.  One of the attendees described it as "that chickenwire compound".

I asked the presenter why, after injecting it into the peritoneal cavity, benzopyrene would cause tumors in the lung (after all, the paper uses a fancy aerosol device to deliver the 3-bromopyruvate (the chemical they were testing to see whether it prevented the tumors from forming), so why not use that to deliver the benzopyrene, too?  Wouldn't that be more relevant anyway for a carcinogen found in tobacco smoke?), and he thought that the authors were just looking at lung tumors and not really interested in any tumors that may or may not have formed in other parts of the body.  I guess intraperitoneal injection is the easiest way to deliver a drug to a mouse, and if it works to produce the desired lung tumors, then good enough?

Reading a bit more, I learned that benzopyrene is actually a "pro-carcinogen": after benzopyrene enters your body, you metabolize it into another molecule, 7,8-dihydroxy-9,10-epoxy-7,8,9,10-tetrahydrobenzo[a]pyrene:

which is the actual carcinogen.  It fits into the double helix of the DNA strand, which can cause the DNA to be copied incorrectly and introduce mutations, which can then cause cancer.