SMAC exhibits anti-tumor effects in ECA109 cells by regulating expression of inhibitor of apoptosis protein family

BACKGROUND The poor prognosis and rising incidence of esophageal cancer highlight the need for improved therapeutics that are essential prior to treatment.LCL161 is an SMAC(second mitochondrial activator of caspases)mimic and inhibitor of apoptosis protein(IAP)antagonist which exhibits anti-tumor effects and improves the chemical sensitivity of many cancers.AIM To ascertain the effects and mechanisms of the SMAC analog LCL161 on esophageal cancer cells.METHODS MTT assay and TUNEL assay were used to detect cell proliferation and apoptosis,respectively.Western blot analysis was used to study the molecular mechanisms of LCL161-induced death of ECA109 cells.RESULTS LCL161 decreased ECA109 cell proliferation in dose-and time-dependent manner and induced apoptosis of ECA109 cells in a dose-dependent manner.Also,LCL161 induced a significant decrease in the expression of the XIAP and significant increase in the expression of Caspase-3.In addition,Bax increased significantly with increasing concentrations of LCL161,and the relative expression of Bax was significantly different between groups.CONCLUSION These findings support the hypothesis that LCL161 can inhibit proliferation and induce apoptosis in esophageal cancer cells by regulating the expression of IAP family members,suggesting that it has potential to be an effective treatment for esophageal squamous cell carcinoma.

Expression of second mitochondria-derived activator of caspases, X-linked inhibitor of apoptosis protein, and caspase-3 in pituitary adenomas

Studies concerning correlations between pituitary adenomas and cell apoptosis have mainly focused on upstream apoptosis signaling, but seldom on downstream mediators. In the present study, second mitochondria-derived activator of caspases （Smac）, X-linked inhibitor of apoptosis protein （XIAP）, and caspase-3 protein were qualitatively analyzed using immunohistochemistry, and quantified by western blot. Smac, XIAP, and caspase-3 mRNA expressions were detected by reverse transcription-PCR. Results showed that XIAP protein and mRNA expressions were greater in the invasive pituitary adenoma group compared with the noninvasive pituitary adenoma group. However, Smac and caspase-3 protein and mRNA expressions were lower in the invasive pituitary adenoma group compared with the noninvasive pituitary adenoma group. In the invasive pituitary adenomas, Smac expression was positively correlated with caspase-3 protein and mRNA expression （Protein： r = 0.55, P 0.01; mRNA： r = 0.50, P 0.01）. Smac and caspase-3 expressions were negatively correlated with XIAP protein and mRNA expression （Protein： r = -0.56, -0.64, P 0.01; mRNA： r = -0.69, -0.67, P 0.01）. However, no significant differences in correlation among Smac, XIAP, and caspase-3 were detectable in noninvasive pituitary adenomas. These data indicated that high expression of XIAP and low expression of Smac and caspase-3 suppressed cell apoptosis and led to enhanced invasiveness of pituitary adenomas. Thus, Smac, XIAP, and caspase-3 may be useful markers in determining the invasive behavior of pituitary adenomas.

Baculoviral inhibitor of apoptosis protein repeatcontaining protein 3 delays early Wallerian degeneration after sciatic nerve injury

Wallerian degeneration is a complex biological process that occurs after nerve injury,and involves nerve degeneration and regeneration.Schwann cells play a crucial role in the cellular and molecular events of Wallerian degeneration of the peripheral nervous system.However,Wallerian degeneration regulating nerve injury and repair remains largely unknown,especially the early response.We have previously reported some key regulators of Wallerian degeneration after sciatic nerve injury.Baculoviral inhibitor of apoptosis protein repeat-containing protein 3(BIRC3)is an important factor that regulates apoptosis-inhibiting protein.In this study,we established rat models of right sciatic nerve injury.In vitro Schwann cell models were also established and subjected to gene transfection to inhibit and overexpress BIRC3.The data indicated that BIRC3 expression was significantly up-regulated after sciatic nerve injury.Both BIRC3 upregulation and downregulation affected the migration,proliferation and apoptosis of Schwan cells and affected the expression of related factors through activating c-fos and ERK signal pathway.Inhibition of BIRC3 delayed early Wallerian degeneration through inhibiting the apoptosis of Schwann cells after sciatic nerve injury.These findings suggest that BIRC3 plays an important role in peripheral nerve injury repair and regeneration.The study was approved by the Institutional Animal Care and Use Committee of Nantong University,China(approval No.2019-nsfc004)on March 1,2019.

Expression of X-linked Inhibitor of Apoptosis Protein and Its Effect on Chemotherapeutic Sensitivity of Bladder Carcinoma

The expression of X-linked inhibitor of apoptosis protein (XIAP) gene and its effect on chemotherapeutic sensitivity in bladder carcinoma was explored. By using immunohistochemistry, the expression of XIAP was detected in 47 bladder carcinomas and 5 normal bladder tissues. The XIAP gene was transfected into bladder cancer cell line T24 by liposome and the positive clone was screened by G418. Cellular XIAP mRNA level was detected by RT-PCR. Low-dose mitocycin C was administered to induce the apoptosis of T24 cells. The in vitro growth of bladder carcinoma cells was analyzed by MTT colorimetry, and the apoptosis rate was assayed by TUNEL methods. It was found XIAP was moderately expressed in bladder carcinomas with the the positive rate being 78.73% (37/47), but the positive rate was not correlated with carcinoma stages and grades (P<0.05). XIAP mRNA level in transfected T24 cells was significantly increased by 3.8 times as compared with that in the cells not transfected with XIAP. After treatment with low-dose mitomycin C (0.005 and 0.05 mg/mL), the growth rate in XIAP no-transfected control group was increased by (11.60±0.25)% and (16.51±0.87)% (P<0.05), and the apoptosis rate was decreased by (10.1±0.2)% and (11.9±0.2%) (P<0.05) respectively as compared with XIAP transfected group. It was concluded that XIAP was expressed in most of bladder carcimoma samples. Overexpression of XIAP in T24 could significantly reduce the MMC-induced apoptosis of bladder carcinoma, suggesting its effect on the chemothera- peutic sensitivity of T24 cells.

circBIRC6 contributes to the development of non-small cell lung cancer via regulating microRNA-217/amyloid beta precursor protein binding protein 2 axis

Background:Circular RNAs(circRNAs)are considered to be important regulators in cancer biology.In this study,we focused on the effect of circRNA baculoviral inhibitor of apoptosis protein(IAP)repeat containing 6(circBIRC6)on non-small cell lung cancer(NSCLC)progression.Methods:The NSCLC and adjacent non-tumor tissues were collected at Shanghai Ninth People's Hospital.Quantitative real-time polymerase chain reaction was conducted for assessing the levels of circBIRC6,amyloid beta precursor protein binding protein 2(APPBP2)messenger RNA(mRNA),baculoviral IAP repeat containing 6 mRNA(BIRC6),and microRNA-217(miR-217).Western blot assay was adopted for measuring the protein levels of APPBP2,E-cadherin,N-cadherin,and vimentin.Colony formation assay,transwell assay,and flow cytometry analysis were utilized for evaluating cell colony formation,metastasis,and apoptosis.Dualluciferase reporter assay and RNA immunoprecipitation assay were carried out to determine the interaction between miR-217 and circBIRC6 and APPBP2 in NSCLC tissues.The murine xenograft model assay was used to investigate the function of circBIRC6 in tumor formation in vivo.Differences were analyzed via Student's t test or one-way analysis of variance.Pearson's correlation coefficient analysis was used to analyze linear correlation.Results:CircBIRC6 was overexpressed in NSCLC tissues and cells.Knockdown of circBIRC6 repressed the colony formation and metastasis and facilitated apoptosis of NSCLC cells in vitro and restrained tumorigenesis in vivo.Mechanically,circBIRC6 functioned as miR-217 sponge to promote APPBP2 expression in NSCLC cells.MiR-217 inhibition rescued circBIRC6 knockdown-mediated effects on NSCLC cell colony formation,metastasis,and apoptosis.Overexpression of miR-217 inhibited the malignant phenotypes of NSCLC cells,while the effects were abrogated by elevating APPBP2.Conclusion:CircBIRC6 aggravated NSCLC cell progression by elevating APPBP2 via sponging miR-217,which might provide a fresh perspective on NSCLC therapy.

Functional analysis of a miRNA‐like small RNA derived from Bombyx mori cytoplasmic polyhedrosis virus

Bombyx mori cytoplasmic polyhedrosis virus(BmCPV)is a major pathogen of the economic insect silkworm,Bombyx mori.Virus‐encoded microRNAs(miRNAs)have been proven to play important roles in host–pathogen interactions.In this study we identified a BmCPV‐derived miRNA‐like 21 nt small RNA,BmCPV‐miR‐1,from the small RNA deep sequencing of BmCPV‐infected silkworm larvae by stem‐loop quantitative real‐time PCR(qPCR)and investigated its functions with qPCR and lentiviral expression systems.Bombyx mori inhibitor of apoptosis protein(BmIAP)gene was predicted by both target prediction software miRanda and Targetscan to be one of its target genes with a binding site for BmCPV‐miR‐1 at the 5′untranslated region.It was found that the expression of BmCPV‐miR‐1 and its target gene BmIAP were both up‐regulated in BmCPV‐infected larvae.At the same time,it was confirmed that BmCPV‐miR‐1 could up‐regulate the expression of BmIAP gene in HEK293T cells with lentiviral expression systems and in BmN cells by transfecting mimics.Furthermore,BmCPV‐miR‐1 mimics could up‐regulate the expression level of BmIAP gene in midgut and fat body in the silkworm.In the midgut of BmCPV‐infected larvae,BmCPV‐miR‐1 mimics could be further up‐regulated and inhibitors could lower the virus‐mediated expression of BmIAP gene.With the viral genomic RNA segments S1 and S10 as indicators,BmCPV‐miR‐1 mimics could up‐regulate and inhibitors down‐regulate their replication in the infected silkworm.These results implied that BmCPV‐miR‐1 could inhibit cell apoptosis in the infected silkworm through up‐regulating BmIAP expression,providing the virus with a better cell circumstance for its replication.

Cloning of human XAF1 gene promoter and assay of its transcription activity in a variety of cell lines

To investigate the regulation of tumor sup-pressor XAF1 gene expression in digestive system cancers,we studied XAF1 gene promoter transcription activity and mRNA level in digestive system cancer cell lines(human hepatoma cell line HepG2,human colon cancer cell line LoVo,and human gastric cancer cell line AGS)and nontumor cell lines(human embryonic liver cell line L02(L02 cells)and human embryonic kidney 293 cells[HEK293 cells])as controls.1395-bp-promoter fragment of XAF1 gene was amplified by polymerase chain reaction(PCR)and cloned into pGL3-basic vector and pEGFP-1 vector to assay its promoter transcription activity.The plasmids were transfected into a variety of cell lines by lipofectamine 2000.The promoter transcription activity was determined by dual-luciferase report assay,and enhanced greenfluorescent protein(EGFP)-positive cells were detected byfluorescence microscope.The expression of XAF1 mRNA in HEK293 and L02 were significantly higher than that in any of the three digestive system cancer cell lines.The dual-luciferase reporter assay showed that the promoter transcription activity in digestive system tumor cell lines transfected with pGL3-XAF1p promoter was apparently lower than that of both HEK293 and L02 cells.Expression of greenfluorescent protein(GFP)under the control of XAF1 promoter in the three digestive system cancer cell lines was lower than that of both HEK293 and L02 cells.The activities of pGL3-XAF1p in the three digestive system cancer cell lines after treatment with heat stress were significantly lower than those in the unstressed cells.The results suggested that remarkably down-regulated XAF1 mRNA expression in digestive system cancer cell lines may be due to loss of transcription activity of XAF1 promoter.