title: HSPA9 overexpression inhibits apoptin-induced apoptosis in the HepG2 cell line.
abstract: Apoptin, a small protein derived from chicken anemia virus, possesses the capacity to specifically kill tumor cells while leaving normal cells intact. Previous studies have indicated that the subcellular localization of apoptin appears to be crucial for this tumor-selective activity. Apoptin resides in the cytoplasm of normal cells; however, in cancer cells it translocates into the nucleus. In the present study, purified prokaryotic native His-apoptin served as a bait for capturing apoptin-associated proteins in both a hepatoma carcinoma cell line (HepG2) and a human fetal liver cell line (L-02). The captured proteins obtained from a pull-down assay were separated by two-dimensional gel electrophoresis. Mass spectrometry was employed to detect the effect of HSPA9 overexpression (one of the interacting proteins with apoptin in vitro) and downregulation of HSPA9 on HepG2 cells. The data revealed that HSPA9 overexpression resulted in partial distribution of apoptin in the cytoplasm. Notably, HSPA9 overexpression markedly decreased the apoptosis rate of HepG2 cells from 41.2 to 31.7%, while the downregulation of HSPA9 using small interfering RNA significantly enhanced the apoptosis of HepG2 cells. Our results suggest new insights into the localization mechanism of apoptin which is tightly associated with HSPA9 overexpression and its crucial role in cellular apoptosis both in a tumor cell line (HepG2) and a normal cell line (L-02). These findings shed new light on the elucidation of the underlying mechanism of anticancer action of apoptin.
authors.affiliation: Clinical Laboratory of Yanan Hospital of Kunming, and Department of Biochemistry and Molecular Biology, Kunming Medical University, Kunming 650051, PR China.
authors.forename: Chuanmei
authors.initials: C
authors.lastname: Peng
authors.forename: Pu
authors.initials: P
authors.lastname: Yang
authors.forename: Yingbo
authors.initials: Y
authors.lastname: Cui
authors.forename: Ming
authors.initials: M
authors.lastname: He
authors.forename: Leilei
authors.initials: L
authors.lastname: Liang
authors.forename: Yong
authors.initials: Y
authors.lastname: Di
mesh_terms: D000970:Antineoplastic Agents / Q000378:metabolism / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects*; D036022:Capsid Proteins / Q000378:metabolism / Q000494:pharmacology*; D015870:Gene Expression; D055785:Gene Knockdown Techniques; D018840:HSP70 Heat-Shock Proteins / Q000235:genetics / Q000378:metabolism*; D056945:Hep G2 Cells; D006801:Humans; D024101:Mitochondrial Proteins / Q000235:genetics / Q000378:metabolism*; D011485:Protein Binding; D025941:Protein Interaction Mapping; D034741:RNA, Small Interfering / Q000235:genetics
chemical_list: D000970:Antineoplastic Agents; D036022:Capsid Proteins; D018840:HSP70 Heat-Shock Proteins; C492001:HSPA9 protein, human; D024101:Mitochondrial Proteins; D034741:RNA, Small Interfering; C091717:VP3 protein, Chicken anemia virus