Hemistepsin a Induces Apoptosis of Hepatocellular Carcinoma Cells by Downregulating STAT3

Abstract

Hemistepta lyrata (Bunge) Bunge is a biennial medicinal plant possessing beneficial effects including anti-inflammation, and hemistepsin A (HsA) isolated from H. lyrata has been known as a hepatoprotective sesquiterpene lactone. In this report, we explored the cytotoxic effects of H. lyrata on hepatocellular carcinoma (HCC) cells and investigated the associated bioactive compounds and their relevant mechanisms. From the viability results of HCC cells treated with various H. lyrata extracts, HsA was identified as the major compound contributing to the H. lyrata-mediated cytotoxicity. HsA increased expression of cleaved PARP and cells with Sub-G1 phase, Annexin V binding, and TUNEL staining, which imply HsA induces apoptosis. In addition, HsA provoked oxidative stress by decreasing the reduced glutathione/oxidized glutathione ratio and accumulating reactive oxygen species and glutathione-protein adducts. Moreover, HsA inhibited the transactivation of signal transducer and activator of transcription 3 (STAT3) by its dephosphorylation at Y705 and glutathione conjugation. Stable expression of a constitutive active mutant of STAT3 prevented the reduction of cell viability by HsA. Finally, HsA enhanced the sensitivity of sorafenib-mediated cytotoxicity by exaggerating oxidative stress and Y705 dephosphorylation of STAT3. Therefore, HsA will be a promising candidate to induce apoptosis of HCC cells via downregulating STAT3 and sensitizing conventional chemotherapeutic agents.

Inhibition of Autophagy Promotes Hemistepsin A-Induced Apoptosis via Reactive Oxygen Species-Mediated AMPK-Dependent Signaling in Human Prostate Cancer Cells

“…Various studies have shown that autophagy is a potent mechanism for eliminating incorrect folded or aggregated proteins and maintaining the energy homeostasis to respond to stress [ 26 , 27 ]. Although the roles of crosstalk between apoptosis and autophagy have been studied [ 28 , 29 ], autophagy has been a widely used therapy for chemo-resistant cancer [ 30 , 31 , 32 , 33 ].…”

Progress of natural sesquiterpenoids in the treatment of hepatocellular carcinoma

“…Hemistepsin A exhibited anti-HCC effect by disrupting MMP, up-regulating p53, p21, cleaved caspase-3 and cleaved PARP and reduced the expressions of cyclin D, CDK6 and Bcl-2. In HepG2 cells, Hemistepsin A-induced apoptosis was associated with its downregulation effect of STAT3 ( 58 ). The expression of cleaved PARP cells in Sub-G1 phase were increased, indicating that hemistepsin A induced apoptosis.…”

Cystine and Methionine Deficiency Promotes Ferroptosis by Inducing B-Cell Translocation Gene 1

“…Levels of reduced glutathione (GSH) and oxidized glutathione (GSSG) were determined by GSH/GSSG-Glo TM Assay (Promega, Madison, WI, USA), as described previously [33].…”

“…Protein extraction using radioimmunoprecipitation buffer, sodium dodecyl sulfatepolyacrylamide gel electrophoresis, electrotransfer of proteins onto a nitrocellulose membrane, incubation of the membrane with appropriate antibodies, and chemiluminescence detection were conducted as described previously [33]. For surface sensing of translation (SUnSET) assay, HepG2 cells under CST/Met (−) were incubated with 1 µg/mL puromycin for 30 min, and puromycin-integrated polypeptides were detected using an anti-puromycin antibody.…”