The classical photoactivated drug 8-methoxypsoralen and related compounds are effective without UV light irradiation against glioma cells

Currently, there is no effective therapy for high grade gliomas. 8-Methoxypsoralen (8-MOP) is a compound used in the treatment of skin diseases combined with UV light irradiation. In this work, rat glioma C6 cells, normal astrocytes and human glioblastoma GL-15 cells comprised an in vitro model to evaluate the antitumor activity of 8-MOP. We found that 8-MOP promoted a time- and concentration-dependent reduction of cell viability in tumor, but not in normal cells. This effect was more evident in log-phase growing culture, indicating antiproliferative activity, which was confirmed by colony formation assay. Long-term effect of 8-MOP at low concentration was also attested. The concentrations used in the tests (0.02-0.4 mM) were lower than plasmatic concentration found in patients. Despite the treatment leads to considerable morphological changes and apoptosis when used at high concentrations, 8-MOP did not promote cell cycle arrest, change in migration pattern neither necrosis. In addition, we evaluated the effect of 8-MOP in MDA-MB-231, CT-26 and SCC-3 cell lines, derived from other kind of primary tumors, and found that CT-26 cells did not respond to 8-MOP treatment, indicating that this compound does not act through a generic mechanism. Coumarin derivatives structurally related to 8-MOP were screened for its antitumor potential and presented different patterns of biological activity, and then it was possible to suggest the relevance of 8-MOP molecular structure for antiproliferative action. Therefore, 8-MOP, a drug with an outstanding record of safety, and related coumarins are good prototypes for development of a new class of anti-glioma drugs. (C) 2016 Elsevier Ltd. All rights reserved.