FRIDAY, April 3 (HealthDay News) -- Treatment with the active ingredient of marijuana, Δ⁹-tetrahydrocannabinol (THC), can destroy human and mouse cancer cells by stimulating autophagy, the natural process leading to cell death, according to a report in the April 1 issue of the Journal of Clinical Investigation.

Maria Salazar, of Complutense University in Madrid, Spain, and colleagues cultured a human glioma cell line (U87MG) and mouse cancer cells, then treated the study cells with THC. The researchers examined treated and untreated cells under electron microscope for comparison. Immunostaining was performed to detect markers for endoplasmic reticulum stress response, a cellular process that stimulates autophagy and cell death. The researchers also examined biopsy tissue from two glioblastoma multiforme patients who were treated with THC.

The investigators found that the THC treatments induced ceramide accumulation, eukaryotic translation and phosphorylation that activated an endoplasmic reticulum stress response in the THC-treated cells, a pathway that led to autophagy. Cells displaying increased autophagy also were observed in the tumor samples obtained from the two THC-treated glioblastoma patients. Conversely, in cells in which the autophagy process was genetically inhibited or inhibited by drugs, the THC was ineffective, the report indicates.

"These findings describe a mechanism by which THC can promote the autophagic death of human and mouse cancer cells and provide evidence that cannabinoid administration may be an effective therapeutic strategy for targeting human cancers," the authors write.

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