title: Iso-suillin from Suillus flavus Induces Apoptosis in Human Small Cell Lung Cancer H446 Cell Line.
abstract: BACKGROUND
  The suillin isoform iso-suillin is a natural substance isolated from a petroleum ether extract of the fruiting bodies of the mushroom Suillus flavus. Previous studies have found its inhibition effect on some cancer cells, and we aimed to study its effects on human small cell lung cancer H446 cell line.
  
  
  METHODS
  Cell viability was measured by 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2-H-tetrazolium bromide assay. Cellular morphological changes (apoptosis and necrosis) were evaluated using an electron microscope and Hoechst 33258 staining detected by the inverted microscope. Flow cytometry was used to detect cell apoptosis, cell cycle distribution, and mitochondrial membrane potential. Protein expression was determined by Western blotting analysis.
  
  
  RESULTS
  Here, we describe the ability of iso-suillin to inhibit the growth of H446 cells in time- and dose-dependent way. Iso-suillin had no obvious impact on normal human lymphocyte proliferation at low concentrations (9.09, 18.17, or 36.35 μmol/L) but promoted lymphocyte proliferation at a high concentration (72.70 μmol/L). After treatment of different concentrations of iso-suillin (6.82, 13.63, or 20.45 μmol/L), the apoptosis rate of H446 cells increased with increasing concentrations of iso-suillin (16.70%, 35.54%, and 49.20%, respectively, all P < 0.05 compared with the control), and the expression of related apoptotic proteins in the mitochondrial pathway including cytochrome c and caspase-9 were up-regulated compared with the control (all P < 0.05). On the contrary, Bcl-2/Bax ratio was down-regulated compared with the control. Besides, the expression of pro-apoptotic proteins in the death receptor apoptosis pathway, including Fas-associating protein with a novel death domain and caspase-8, and the expression of caspase-3, a downstream regulatory protein of apoptosis, were also increased compared with the control (all P < 0.05). Inhibitors of caspase-9 and caspase-8 reversed the apoptosis process in H446 cells to varying degrees.
  
  
  CONCLUSIONS
  These results suggest that iso-suillin could induce H446 cell apoptosis through the mitochondrial pathway and the death-receptor pathway. Therefore, iso-suillin might have a potential application as a novel drug for lung cancer treatment.
authors.affiliation: Department of Cell Biology, Basic Medical College, Hebei Medical University, Shijiazhuang, Hebei 050017, China.
authors.forename: Jun-Xia
authors.initials: JX
authors.lastname: Zhao
authors.affiliation: Department of Biochemistry and Molecular Biology, College of Life Sciences, Hebei Normal University, Shijiazhuang, Hebei 050024, China.
authors.forename: Qing-Shuang
authors.initials: QS
authors.lastname: Zhang
authors.affiliation: Department of Bioengineering, College of Biology Science and Engineering, Hebei University of Economics and Business, Shijiazhuang, Hebei 050061, China.
authors.forename: Ying
authors.initials: Y
authors.lastname: Chen
authors.affiliation: Department of Cell Biology, Basic Medical College, Hebei Medical University, Shijiazhuang, Hebei 050017, China.
authors.forename: Sheng-Jie
authors.initials: SJ
authors.lastname: Yao
authors.affiliation: Department of Cell Biology, Basic Medical College, Hebei Medical University, Shijiazhuang, Hebei 050017, China.
authors.forename: Yong-Xin
authors.initials: YX
authors.lastname: Yan
authors.affiliation: Department of Biochemistry and Molecular Biology, College of Life Sciences, Hebei Normal University, Shijiazhuang, Hebei 050024, China.
authors.forename: Ying
authors.initials: Y
authors.lastname: Wang
authors.affiliation: Department of Biochemistry and Molecular Biology, College of Life Sciences, Hebei Normal University, Shijiazhuang, Hebei 050024, China.
authors.forename: Jin-Xiu
authors.initials: JX
authors.lastname: Zhang
authors.affiliation: Department of Biochemistry and Molecular Biology, College of Life Sciences, Hebei Normal University, Shijiazhuang, Hebei 050024, China.
authors.forename: Li-An
authors.initials: LA
authors.lastname: Wang
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000187:drug effects; D053148:Caspase 3 / Q000378:metabolism; D053181:Caspase 8 / Q000378:metabolism; D053453:Caspase 9 / Q000378:metabolism; D045744:Cell Line, Tumor; D002470:Cell Survival / Q000187:drug effects; D045304:Cytochromes c / Q000378:metabolism; D004224:Diterpenes / Q000494:pharmacology*; D005434:Flow Cytometry; D006801:Humans; D051379:Mice; D010636:Phenols / Q000494:pharmacology*; D055752:Small Cell Lung Carcinoma
chemical_list: D004224:Diterpenes; D010636:Phenols; C061636:suillin; D045304:Cytochromes c; D053148:Caspase 3; D053181:Caspase 8; D053453:Caspase 9