Δ9-Tetrahydrocannabinol inhibits cell cycle progression by downregulation of E2F1 in human glioblastoma multiforme cells

Background. The active components of Cannabis sativa L., Cannabinoids, traditionally used in the field of cancer for alleviation of pain, nausea, wasting and improvement of well-being have received renewed interest in recent years due to their diverse pharmacologic activities such as cell growth inhibition, anti-inflammatory activity and induction of tumor regression. Here we used several experimental approaches, which identified delta-9-tetrahydrocannabinol (Δ9-THC) as an essential mediator of cannabinoid antitumoral action. Methods and results. Administration of Δ9-THC to glioblastoma multiforme (GBM) cell lines results in a significant decrease in cell viability. Cell cycle analysis showed G0/1 arrest and did not reveal occurrence of apoptosis in the absence of any sub-G1 populations. Western blot analyses revealed a THC altered cellular content of proteins that regulate cell progression through the cell cycle. The cell content of E2F1 and Cyclin A, two proteins that promote cell cycle progression, wer...