松井 太衛

Abstract This study investigated the anti-tumor effects of andrographolide, a diterpene lactone derived from Andrographis paniculata, on T-cell acute lymphoblastic leukemia (T-ALL) cells. Andrographolide induced dose-dependent cytotoxicity and morphological changes in the T-ALL cell line Jurkat cells, including cell shrinkage and chromatin condensation. Mechanistically, andrographolide triggers apoptosis through reactive oxygen species (ROS) generation, mitochondrial membrane depolarization, and cytochrome c release. These effects were reversed by the ROS inhibitor N-acetyl-L-cysteine (NAC), indicating that andrographolide induces apoptosis through a ROS-dependent apoptotic pathway. In contrast, NAC treatment did not reverse cytarabine- and vincristine-induced apoptosis or the ROS-dependent apoptotic pathway in Jurkat cells. Intriguingly, andrographolide also induced ferroptosis, as evidenced by increased expression of the ferroptosis marker fatty acid-CoA ligase 4 and ultrastructural changes such as reduced mitochondrial area and disappearance of cristae. These effects were likewise reversed by NAC, further implicating ROS in the ferroptotic process. In MOLT-4 cells, where andrographolide suppressed viability, increased Annexin V positivity and ROS levels, and upregulated FACL4 expression in a NAC-sensitive manner. Unlike cytarabine and vincristine, andrographolide did not significantly alter cell cycle distribution. In conclusion, andrographolide induces both apoptosis and ferroptosis in T-ALL cells via ROS-dependent mechanisms that are distinct from those of conventional chemotherapeutic agents. These dual actions position andrographolide as a candidate for standalone or combination therapy in T-ALL.

OBJECTIVES: Agaritine (AGT) is a hydrazine-containing compound derived from the mushroom Agaricus blazei Murill. We previously reported the antitumor effect of AGT on hematological tumor cell lines and suggested that AGT induces apoptosis in U937 cells via caspase activation. However, the antitumor mechanism of AGT has not been fully understood. METHODS: Four hematological tumor cell lines (K562, HL60, THP-1, H929) were used in this study. The cells were incubated in the presence of 50 μM AGT for 24 h and analyzed for cell viability, annexin V positivity, caspase-3/7 activity, mitochondrial membrane depolarization, cell cycle, DNA fragmentation, and the expression of mitochondrial membrane-associated proteins (Bax and cytochrome c). RESULTS: In HL60, K562, and H929 cells, AGT reduced cell viability and increased annexin V- and dead cell-positive rates; however, it did not affect THP-1 cells. In K562 and HL60 cells, caspase-3/7 activity, mitochondrial membrane depolarization, and expression of mitochondrial membrane proteins, Bax and cytochrome c, were all increased by AGT. Cell cycle analysis showed that only K562 exhibited an increase in the proportion of cells in G2/M phase after the addition of AGT. DNA fragmentation was also observed after the addition of AGT. CONCLUSIONS: These results indicate that AGT induces apoptosis in K562 and HL60 cells, like U937 reported previously, but showed no effect on THP-1 cells. It was suggested that AGT-induced apoptosis involves the expression of Bax and cytochrome c via mitochondrial membrane depolarization.