WASHINGTON — The main chemical in marijuana appears to aid in the destruction of brain cancer cells, offering hope for future anti-cancer therapies, researchers in Spain wrote in a study released Thursday. The authors from the Complutense University in Madrid, working with scientists from other universities, found that the active component of marijuana, tetrahydrocannabinol (THC), causes cancer cells to undergo a process called autophagy — the breakdown that occurs when the cell essentially self-digests. The research, which appears in the April edition of US-published Journal of Clinical Investigation, demonstrates that THC and related ‘cannabinoids’ appear to be ‘a new family of potential antitumoral agent.’ The authors wrote that the chemical may prove useful in the development of future ‘antitumoral agents.’ The scientists conducted their research on mice, first stimulating the growth of cancer in the lab animals, then injecting them with a daily dose of THC near the site of their tumors. The researchers also analyzed the tumors of two patients in an experimental trial looking at the effects of THC on a highly aggressive form of brain tumor, and saw findings ‘in line with the preclinical evidence’ first observed in the laboratory mice.