Cannabis Compound May Stop Metastatic Breast Cancer

Cannabis Compound May Stop Metastatic Breast Cancer
MONDAY, Nov. 19 (HealthDay News) -- A non-toxic, non-psychoactivecompound in marijuana may block the progress of metastatic breast cancer,according to a new study by researchers in California.
"This is a new way to treat a patient that is not toxic likechemotherapy or radiotherapy. It is a new approach for metastatic cancer,"said lead researcher Sean D. McAllister, an associate scientist at theCalifornia Pacific Medical Center Research Institute in San Francisco.
The compound found in cannabis, called cannabidiol (CBD), inhibits agene, Id-1, that researchers believe is responsible for the metastaticprocess that spreads cells from the original tumor throughout thebody.
Opting for a musical metaphor, senior researcher Pierre-Yves Desprezlikened Id-1 to "an [orchestra] conductor. In this case, you shoot theconductor, and the whole orchestra is going to stop. If you shoot theviolinist, the orchestra just continues to play."
In humans, the Id-1 gene is found only in metastatic cancer cells, saidDesprez, a staff scientist at the institute. Before birth, they arepresent and involved in the development of human embryos, but after birth,they go silent -- and should stay that way, he said.
But in metastatic cancer "when [the genes] wake up, they are very bad,"he said. "They push the cells to behave like embryonic cells and grow.They go crazy, they proliferate, they migrate." Desprez said, "We need tobe able to turn them off."
According to the study, CBD does exactly that.
"We are focusing on the latest stages of cancer," Desprez added. Thecancer cell itself is not the problem, because a tumor can be "removedeasily by surgery," he said. The problem is the development of metastaticcells which is "conducted" by Id-1.
McAllister and Desprez said they are not suggesting thatpatients with hormone-independent metastatic breast cancer smokemarijuana. For one thing, a sufficient amount of CBD could never beobtained in that way, they said.
The research that has been done on marijuana and its compounds,however, is helpful, McAllister, said. CBD has been around for a longtime, and researchers have found it is not psychoactive, and its "toxicityis very low," he added.
The new findings are published in the November issue of MolecularCancer Therapeutics.
If McAllister's and Desprez's work results in the development of acancer treatment, someone with metastatic cancer might be placed on CBDfor several years. That means low toxicity is important, McAllisterexplained.
McAllister also suggested that Id-1 is "so important in providing the[metastatic] mechanism in these cells in so many types of cancers" thatthey "provide us an opportunity potentially to target other types ofcancers."
The study's findings were "were a serendipitous discovery, in a way,"McAllister said. Desprez noted that he had been working on the Id-1 genefor 12 years. His lab had demonstrated that it was a key gene for invasivebreast cancer and tumor progression, and Desprez had found a way toinhibit it in mice, but not in humans.
Then, two years ago, McAllister -- an expert on cannabinoids -- andDesprez, a cancer researcher, started to work together. Through theircombined forces "what we found is actually what I was looking for for thelast 12 years," Desprez said.
Further study is needed before CBD can be conclusively identified as atreatment option, McAllister and Desprez said. "We need to involve a teamof physicians, because we are bench [basic] scientists," McAllistersaid.
One expert called the findings intriguing but preliminary.
"This is the first evidence that a cannabinoid can target theexpression of an important breast cancer metastasis gene," noted ManuelGuzman, a Spanish expert on cannabinoids and cancer. He described theCalifornia study as giving "preliminary insight into the question ofwhether CBD could be used clinically to treat metastatic breastcancer."
However, "all the experiments in the paper have been conducted incultured cells and none of them in any animal model of breast cancer,which would be one of the steps for further research," added Guzman, whois a professor of biochemistry and molecular biology at ComplutenseUniversity in Madrid.
Guzman also noted that "Id-1 is just one of many genes involved inbreast cancer metastasis" and that future research also needs to examinethe impact of CBD on these other metastasis genes.
More information
There's more on breast cancer at the U.S.National Cancer Institute.