Therapeutic Effect of 1,3‐Thiazin‐6‐One for the Treatment of Brain Cancer Through Increased Accumulation in the Brain Glioblastoma Cells

Abstract In the present study a library of five (2‐(amino)‐1,3‐thiazin‐6‐one) compounds was synthesized and investigated as against glioblastoma cells in vitro and in vivo in the mice model. The results revealed that all of the five 1,3‐thiazin‐6‐one compounds (4a, 4b, 4c, 4d and 4e) exhibited cytotoxicity against U87MG and 9 L brain cancer cell lines. Moreover, it was found that 9 L cells showed slightly higher sensitivity towards the compounds 4a, 4b, 4c, 4d and 4e compared to U87MG cells. It was observed that the compounds 4a, 4b, 4c, 4d and 4e showed a time‐dependent increase in uptake efficiency by U87MG and 9 L cells. Furthermore, the data revealed that uptake of the compounds and therefore internalization was maximum during initial 1 h of the treatment. Among the synthesized compounds, compound 4c containing trifluoromethyl moiety showed higher uptake efficiency compared to the compound 4a, 4b, 4d and 4e. Treatment of U87MG and 9 L cell tumor spheroids with compound 4c significantly ( P <0.05) inhibited the tumor growth compared to the control spheroids. In vivo data revealed that treatment with compound 4c led to a significant ( P <0.05) decrease in glioblastoma growth in mice in dose‐dependent manner. Growth of glioblastoma in mice was almost completely inhibited after 28 days of treatment with 2 mg/kg dose of compound 4c. Pharmacokinetic studies showed that compound 4c remained in circulation for longer duration in mice and its terminal half‐life was found to be 6.5 h. Treatment of U87MG and 9 L cells with compound 4c led to a prominent decrease in expression of CYR61 protein. In conclusion, findings of the present study suggest that compound 4c acts as a potential therapeutic agent for the treatment of advanced brain cancer through activation of Hippo pathway. Therefore, more studies need to be performed to investigate the detailed mechanism underlying the inhibitory effect of compound 4c against the glioblastoma.