Nitric oxide induces apoptosis and autophagy; autophagy down-regulates NO synthesis in physalin A-treated A375-S2 human melanoma cells

• Published in: Food and chemical toxicology Vol. 71; pp. 128 - 135
• Main Authors: He, Hao, Feng, Yong-Sheng, Zang, Ling-He, Liu, Wei-Wei, Ding, Li-Qin, Chen, Li-Xia, Kang, Ning, Hayashi, Toshihiko, Tashiro, Shin-ichi, Onodera, Satoshi, Qiu, Feng, Ikejima, Takashi
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 01.09.2014; Elsevier
• Subjects: A375-S2 cells; Apoptosis; Apoptosis - physiology; Autophagy; Autophagy - physiology; Biological and medical sciences; Cell Line, Tumor; Down-Regulation; Food toxicology; Foods; Herbal medicine; Human; Humans; Inhibitors; Medical sciences; Melanoma - metabolism; Melanoma - pathology; mTOR; Negative feedback; Nitric oxide; Nitric Oxide - biosynthesis; Nitric Oxide - physiology; Physalin A; Physalis alkekengi; Reactive Oxygen Species - metabolism; Repressing; Toxicology; Withanolides - pharmacology; NO; DAF2-DA; DMSO; 3MA; Physalin A; PARP; MTT; ATCC; MDC; Autophagy; A375-S2 cells; NOS; MEM; FBS; RNS; Nitric oxide; ROS; DAF-2T; mTOR; iNOS; PI; 1400W; ICAD; Apoptosis; Human; Physalin; Cell death; Melanoma; Tumor; Biosynthesis
• ISSN: 0278-6915; 1873-6351
• DOI: 10.1016/j.fct.2014.06.007

[Display omitted] •Physalin A induced the expression of iNOS in A375-S2 cells.•NO generated by physalin A induced apoptosis and autophagy in the cells.•NO suppressed mTOR expression, which led to autophagy induction.•Autophagy and NO production form a negative feedback loop that eventually protects the cells from apoptosis. Physalin A is an active withanolide isolated from Physalis alkekengi var. franchetii, a traditional Chinese herbal medicine named Jindenglong, which has been used for the treatment of sore throat, hepatitis, eczema and tumors in China. Our previous study demonstrated that physalin A induced apoptosis and cyto-protective autophagy in A375-S2 human melanoma cells. Induction of reactive oxygen species (ROS) with physalin A triggered apoptosis. In this study, NO generated by physalin A induced apoptosis and autophagy in A375-S2 cells, since physalin A induced the expression of inducible nitric oxide synthase (iNOS) in the cells. Generation of NO partially promoted both apoptosis and autophagy in A375-S2 cells. NO suppressed mTOR expression, which led to autophagy induction. An autophagic inhibitor, 3-methyladenine (3MA) promoted NO production, while acceleration of autophagy with an autophagic agonist rapamycin repressed NO production, suggesting that autophagy and NO production form a negative feedback loop that eventually protects the cells from apoptosis. The results together with the previous study indicate apoptosis and autophagy induced by physalin A in A375-S2 cells; the autophagy, repressing production of reactive nitrogen species (RNS) and ROS, protects the cells from apoptosis.