Science looks at marijuana; does it cure cancer?



We're a little late to this, but a June 19 story published in Science News takes a hard look at marijuana, and its possible medical benefits.

In-depth marijuana knowledge essentially began in 1964 when delta-9-tetrahydrocannabinol — THC — was first isolated. Later, studies revealed "the compound binds to a protein that pops up on the surface of nerve cells."

THC molecule
  • THC molecule

A bigger revelation came in 1992: Mammals make their own compound that binds to, and switches on, the CB1 receptor. Scientists named the compound anandamide. Researchers soon found its counterpart that binds mainly to the CB2 receptor, calling that one 2AG, for 2-arachidonyl glycerol. The body routinely makes these compounds, called endocannabinoids, and sends them into action as needed.

“At that point, this became a very, very respectable field,” says [biochemist and discoverer of THC Raphael] Mechoulam, now at Hebrew University of Jerusalem, who along with Pertwee and others reported the anandamide discovery in Science. “THC just mimics the effects of these compounds in our bodies,” Mechoulam says. Although the receptors are abundant, anandamide and 2AG are short-acting compounds, so their effects are fleeting.

With foundational knowledge in place, research has turned toward the plant's medicinal value. Besides its traditional uses to help pain, sleep easier and cope with nausea, anxiety and depression, research has recently shown success treating effects of multiple sclerosis (MS).

More than a dozen medical trials in the past decade have shown that treatments containing THC (and some that combine THC with another derivative called cannabidiol, or CBD) not only ease pain in MS patients but also alleviate other problems associated with the disease [such as burning leg pain, and muscle stiffness].

CBD molecule
  • CBD molecule

On its own, CBD has its own benefits: It's an anti-inflammatory and antioxidant, and as well as toning "down the psychoactive effect of THC without eliminating its medical properties. CBD also mutes the occasional anxiety and even paranoia that THC can induce."

Just one problem:

“CBD has essentially been bred out of North American black market drug strains,” [neurologist Ethan] Russo says. People growing cannabis for its recreational qualities have preferred plants high in THC, so people lighting up for medical purposes, whether to boost appetite in AIDS patients or alleviate cancer pain, may be missing a valuable cannabis component.

Though still not clinically proven in humans, marijuana may offer the biggest benefit of all: cancer treatment.

Biochemists Guillermo Velasco and Manuel Guzmán of Complutense University in Madrid have spent more than a decade establishing in lab-dish and animal tests that THC can kill cancer of the brain, skin and pancreas.

THC ignites programmed suicide in some cancerous cells, the researchers reported in 2009 in the Journal of Clinical Investigation. The team’s previous work showed that THC sabotages the process by which a tumor hastily forms a netting of blood vessels to nourish itself, and also keeps cancer cells from moving around.

THC achieves this wizardry by binding to protein receptors on a cancerous cell’s surface. Once attached, the THC induces the cell to make a fatty substance called ceramide, which prompts the cell to start devouring itself. “We see programmed cell death,” Velasco says. What’s more, noncancerous cells don’t make ceramide when they come into contact with THC. The healthy cells don’t die.

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