Sulindac inhibits tumor growth !...

We know that, Sulindac(structure), is useful in the treatment of acute or  chronic inflammatory conditions. Sulindac is a prodrug, derived from sulfinylindene, that is converted in the body to the active NSAID. More specifically, the agent is converted by liver enzymes to a sulfide that is excreted in the bile and then reabsorbed from the intestine. This is thought to help maintain constant blood levels with reduced gastrointestinal side effects. Some studies have shown sulindac to be relatively less irritating to the stomach than other NSAID's except for drugs of the COX-2 inhibitor class. The exact mechanism of its NSAID properties is unknown, but it is thought to act on enzymes COX-1 and COX-2, inhibiting prostaglandin synthesis.

Now researchers from Sanford-Burnham Medical Research Institute (Sanford-Burnham) and their colleagues have figured out how  Sulindac, inhibits tumor growth. The study reveals that Sulindac shuts down cancer cell growth and initiates cell death by binding to nuclear receptor RXRα, a protein that receives a signal and carries it into the nucleus to turn genes on or off. 

As per the claim by the researchers, RXRα normally suppresses tumors, but many types of cancer cells produce a truncated form of this nuclear receptor that does just the opposite. This study showed that shortened RXRα enhances tumor growth by stimulating other proteins that help cancer cells survive. Luckily, the researchers also found that Sulindac can be used to combat this deviant RXRα by switching off its pro-survival function and turning on apoptosis, a process that tells cells to self-destruct.  The interesting part of their research lies in the fact that, they were able to overcome the limitation (cardiovascular side effects associated with Sulindac and other NSAIDs), the researchers tweaked Sulindac, creating a new version of the drug now called K-80003 that both decreases negative consequences and increases binding to truncated RXRα..

"Depending on the conditions, the same protein, such as RXRα, can either kill cancer cells or promote their growth," Dr. Zhang said. "The addition of K-80003 shifts that balance by blocking survival pathways and sensitizing cancer cells to triggers of apoptosis."

Ref :  http://www.cell.com/cancer-cell/retrieve/pii/S1535610810001595