Hernandezine induces multiple cancer cell death

概要

〔目的〕
Hernandezine (Her), a bisbenzylisoquinoline alkaloid, exerts anti-cancer effects on several cancer cell lines. However, the detailed mechanisms by which it promotes cell death and autophagy are largely unknown. Aimed to clarify the molecular mechanisms underlying Her- induced cancer cell death, focusing on the mechanisms by which it promotes autophagy.

〔方法並びに成績〕
I demonstrated that Her induces significant cell death in breast epithelial cancer (MCF-7), lung adenocarcinoma (A549), and gastric cancer (AGS) cell lines. Her therapy resulted in a loss of mitochondrial membrane potential (MMP), increased reactive oxygen species (ROS) generation, and PARP cleavage in MCF-7 cells. Pan-caspase inhibitor z-VAD-FMK, and necroptosis inhibitors necrostatin-1 (Nec-1) and necrosulfonamide (NSA), all inhibited cancer cell death, indicating that Her functions through multiple cell death pathways. Her increased the expression of MAP1LC3/LC3II and several mitophagy markers and blocked autophagic flux confirmed by the RFP-GFP-LC3 reporter assay. Her also increased SQSTM1/p62 and inhibited cathepsin D (CTSD) maturation, revealing lysosomal dysfunction impairs autophagic flux. Her inhibiting autophagosome and lysosome fusion was ruled out by the colocalization of LC3 with lysotracker or LAMP1. AMPK inhibitor Compound C (CC) inhibited LC3II and increased cleaved PARP. The ineffective 3-MA, a common early autophagy inhibitor, and the inhibition of LC3II and ATG16L1 by bafilomycin A1 (Baf A1) implied the involvement of the noncanonical autophagic pathway. Baf A1 and HCQ further enhanced cell death demonstrating autophagy production occurred in response to stress, but Her also disrupted autophagic flux, resulting in failed degradation. The results provide the first evidence that Her induces apoptosis and necroptosis, triggering protective autophagy, mitophagy and impairing autophagic flux.

〔総括〕
The results demonstrated that Her triggers several modes of cell death in cancer cells, including apoptosis and necroptosis. In addition, it promotes autophagy initiation, especially via the noncanonical autophagy pathway, causes the accumulation of dysfunctional autolysosomes, and interrupts mitophagy. The particular effects of autophagy induced by Her would apply to cancer cells that show resistance to common therapies. Moreover, Her can be used in combination with some autophagy inhibitors to enhance the effect. Thus, the results provide new insights into the anti-cancer effects of Her associated with autophagy and mitophagy and provide a basis for improving cancer prevention and therapeutic strategies.