title: Co-silencing of Birc5 (survivin) and Hspa5 (Grp78) induces apoptosis             in hepatoma cells more efficiently than single gene interference.
abstract: Birc5 (previously known as survivin) is a cancer-specific protein. Due to the upregulation of its expression in various human malignancies and its key role in apoptosis, proliferation and angiogenesis, Birc5 has attracted attention as a target for anticancer therapies. In this study, when Birc5 was silenced in HepG2 cells, 29.7±3.3% cells underwent apoptosis as expected. It was found that the expression levels of glucose-regulated protein 78 (Hspa5, previously known as Grp78) was increased by almost 3-fold in Birc5-silenced HepG2 cells. Hspa5, a master regulator of the anti-apoptotic unfolded protein response signalling network, can also promote tumor proliferation, survival and metastasis. Hence, we hypothesized that the co-silencing of Birc5 and Hspa5 may exert a stronger apoptosis-inducing effect than single gene interference. To verify this, the expression levels of Birc5 and Hspa5 in human hepatocellular carcinoma tissues were determined. Immunohistochemical staining showed that the expression of Birc5 and Hspa5 was elevated in 28 out of 31 samples. Additionally, plasmid-based siRNA against Birc5 and/or Hspa5 were constructed and transfected into the human hepatocellular liver carcinoma cell line, HepG2. Compared with the HepG2 cells, in which Birc5 or Hspa5 were silenced alone, only 44.2±3.4% of the co-silenced cells proliferated, and 40.3±3.7% co-silenced cells underwent apoptosis (p<0.05). Furthermore, tumor formation from inoculated subcutaneous co-silenced cells in nude mice was inhibited significantly. The current study suggests that Birc5 and Hspa5 could be important survival factors for hepatoma carcinoma cells and that the simultaneous knockdown of Birc5 and Hspa5 is more effective in inducing apoptosis in HepG2 cells than the knockdown of Birc5 or Hspa5 alone. The co-silencing of Birc5 and Hspa5 could be warranted for cancer therapy.
authors.affiliation: Department of Immunology, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei, People's Republic of China.
authors.forename: Qiang
authors.initials: Q
authors.lastname: Wang
authors.forename: Rong
authors.initials: R
authors.lastname: Shu
authors.forename: Huijun
authors.initials: H
authors.lastname: He
authors.forename: Li
authors.initials: L
authors.lastname: Wang
authors.forename: Yuan
authors.initials: Y
authors.lastname: Ma
authors.forename: Huifen
authors.initials: H
authors.lastname: Zhu
authors.forename: Zhihua
authors.initials: Z
authors.lastname: Wang
authors.forename: Shuo
authors.initials: S
authors.lastname: Wang
authors.forename: Guanxin
authors.initials: G
authors.lastname: Shen
authors.forename: Ping
authors.initials: P
authors.lastname: Lei
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000235:genetics*; D006528:Carcinoma, Hepatocellular / Q000378:metabolism / Q000473:pathology*; D049109:Cell Proliferation; D000091342:Endoplasmic Reticulum Chaperone BiP; D015870:Gene Expression; D055785:Gene Knockdown Techniques; D006360:Heat-Shock Proteins / Q000235:genetics* / Q000378:metabolism; D056945:Hep G2 Cells; D006801:Humans; D051034:Inhibitor of Apoptosis Proteins / Q000235:genetics* / Q000378:metabolism; D008113:Liver Neoplasms / Q000378:metabolism / Q000473:pathology*; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D008819:Mice, Nude; D009368:Neoplasm Transplantation; D021381:Protein Transport; D034622:RNA Interference; D000077022:Survivin
chemical_list: C107489:BIRC5 protein, human; D000091342:Endoplasmic Reticulum Chaperone BiP; C000717247:HSPA5 protein, human; D006360:Heat-Shock Proteins; C000717248:Hspa5 protein, mouse; D051034:Inhibitor of Apoptosis Proteins; D000077022:Survivin