July 17, 2011
Antioxidant Inhibitor Kills Cancer Cells

Sam W. Lee and Anna Mandinova of Massachusetts General Hospital have accidentally discovered a compound that kills cancer cells by suppressing enzymes that detoxify free radicals.

A cancer cell may seem out of control, growing wildly and breaking all the rules of orderly cell life and death. But amid the seeming chaos there is a balance between a cancer cell's revved-up metabolism and skyrocketing levels of cellular stress. Just as a cancer cell depends on a hyperactive metabolism to fuel its rapid growth, it also depends on anti-oxidative enzymes to quench potentially toxic reactive oxygen species (ROS) generated by such high metabolic demand.

Scientists at the Broad Institute and Massachusetts General Hospital (MGH) have discovered a novel compound that blocks this response to oxidative stress selectively in cancer cells but spares normal cells, with an effectiveness that surpassed a chemotherapy drug currently used to treat breast cancer. Their findings, based on experiments in cell culture and in mice, appear online in Nature on July 13.

The plant-based compound piperlongumine (PL), derived from the fruit of a pepper plant found in southern India and southeast Asia, appears to kill cancer cells by jamming the machinery that dissipates high oxidative stress and the resulting ROS. Normal cells have low levels of ROS, in tune with their more modest metabolism, so they don't need high levels of the anti-oxidant enzymes that PL stymies once they pass a certain threshold.

Cancer cells generate a lot more toxic reactive oxygen species (ROS) because cancer cells grow at a fast rate. Cancer cells have faster rates of metabolism. So a drug that inhibits the cell's defenses against ROS will selectively cause much higher ROS concentration in cancer cells than in normal cells.

Since normal cells do not generate ROS in quantities that are immediately toxic the drug appears to be highly selective for cancer cells.

The scientists tested PL against cancer cells and normal cells engineered to develop cancer. In mice injected with human bladder, breast, lung, or melanoma cancer cells, PL inhibited tumor growth but showed no toxicity in normal mice. In a tougher test of mice that developed breast cancer spontaneously, PL blocked both tumor growth and metastasis. In contrast, the chemotherapy drug paclitaxel (Taxol) was less effective, even at high levels.

"This compound is selectively reducing the enzyme activity involved in oxidative stress balance in cancer cells, so the ROS level can go up above the threshold for cell death," said Lee, a Broad associate member and associate director of CBRC at MGH. "We hope we can use this compound as a starting point for the development of a drug so patients can benefit."

It'll probably be years before this drug (or drugs like it) get tried in humans in clinical trials. But since this compound is found in pepper plants it might be possible to get the compound outside of medical channels of distribution. If I had fatal cancer I would try to get some of it to try.


Share |      Randall Parker, 2011 July 17 11:04 PM  Biotech Cancer

PacRim Jim said at July 18, 2011 1:40 AM:

Hooray for accidental discoveries.
You can't teach that.
By the way, a Korean registered the domain name piperlongumine.com four days ago.

Phillep Harding said at July 18, 2011 2:19 PM:

Re Korea: Ain't that just ducky. Something new for the spammers. Ugh.

From the description, it sounds like it works best with the fast cancers, and maybe not so good with slow cancers, like prostate and pancreatic.

Rich66 said at July 19, 2011 1:07 PM:

"it has little effect on either rapidly or slowly dividing primary normal cells."

reads to me like it works on cancer cells but leaves normal cells alone.

The question is whether it was delivered orally (gavage) or injected.

someone can buy the article and report back ;)


John said at July 19, 2011 1:26 PM:

Sounds a lot like Laetrile (B17) - http://realityzone.com/worwitcan.html

Some say it's quackery, but I don't think so. The book is worth the read.

Mike Bell said at July 19, 2011 6:08 PM:

You have "cancel cells" instead of "cancer cells" in the beginning of the text.

Sean Murphy said at July 19, 2011 8:38 PM:

I wonder if anti-oxidants for people with cancer is a bad idea, It seems like the cancer cells could use the anti-oxidant to combat the ROS buildup due to their faster metabolism. This would explain some findings that beta carotene was not a good idea for smokers. They may have already had a population of cancer cells that could leverage the beta carotene to protect against ROS. See http://www.cancer.gov/clinicaltrials/results/summary/2004/final-caret1204 for example.

David Gobel said at July 20, 2011 1:00 PM:

rich66: The article states that it was delivered both peritoneally and orally and that both delivery methods were effective. The study was impressive from my pov both experimental design and results wise

orchus said at September 11, 2011 8:32 AM:

Piperlongumine (PL) is from fruit of Long pepper (Piper longum)
Long Pepper grows in North & South East India, Bangledash & Sri Lanka
Long Pepper used in Indian Ayurvedic medicine & Indian & African foods
Long pepper, tastes Sweet & Spicy
In Indian foods, long pepper is mainly used in pickles (achar)
Long Pepper is commonly used in Moroccan spice mixes & Ethiopian mutton
available at Indian grocery stores, labeled: pippali
Ayurvedic digestive: Trikatu (3 Spices)= Pippali, Black Pepper, Ginger


Martin Miller said at October 27, 2011 1:39 PM:

common pepper has a cancer fighting compound in it called piperine. wonder how closely related this chemical might be. hopefully there may be something on Pubmed.org that goes into more detail.

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