Synthesis and in vitro evaluation of a novel thienopyrimidine with phototoxicity towards rat glioma F98 cells

Abstract

Glioblastoma multiforme is one of the most aggressive cancer forms in humans, and has low recovery rates after surgery, ionizing radiation and chemotherapy. Therefore, there is a high interest in the development of new treatment methods, as for instance photodynamic therapy (PDT). It is here presented results of the cytotoxic properties of the novel compound N1-(4-(4-(benzyl(methyl)amino)thieno[2,3-d]pyrimidin-6-yl)benzyl)-N2,N2-dimethylethane-1,2-diamine (1), which was found ten-fold more active on the rat glioma cell model F98 than the reference drug Temozolomide (TMZ). Further cell survival studies showed a profound increase in F98 cell death on UVA-radiation (330 nm, 0.5 mW/cm2). Photochemical internalization induced delivery of compound 1, but in contrast to the cytostatic drug Bleomycin, a higher cytotoxicity was not observed. Localization studies using fluorescence microscopy revealed that compound 1 readily internalized into the cytosol but did not enter the cell nucleus. The compound was shown to be a relatively weak epidermal growth factor receptor inhibitor, which is not likely to explain its cytotoxicity. However, the quantum efficiency for generation of singlet oxygen was 23%, suggesting generation of reactive oxygen species as one possible mechanism. Although more studies are needed to reveal detailed mode of action, compound 1 is a promising photosensitizer candidate for further development in tests of animal models.