Growth arrest-specific gene 2 suppresses hepatocarcinogenesis by intervention of cell cycle and p53-dependent apoptosis

BACKGROUND Growth arrest-specific gene 2(GAS2)plays a role in modulating in reversible growth arrest cell cycle,apoptosis,and cell survival.GAS2 protein is universally expressed in most normal tissues,particularly in the liver,but is depleted in some tumor tissues.However,the functional mechanisms of GAS2 in hepatocellular carcinoma(HCC)are not fully defined.AIM To investigate the function and mechanism of GAS2 in HCC.METHODS GAS2 expression in clinic liver and HCC specimens was analyzed by real-time PCR and western blotting.Cell proliferation was analyzed by counting,MTS,and colony formation assays.Cell cycle analysis was performed by flow cytometry.Cell apoptosis was investigated by Annexin V apoptosis assay and western blotting.RESULTS GAS2 protein expression was lower in HCC than in normal tissues.Overexpression of GAS2 inhibited the proliferation of HCC cells with wide-type p53,while knockdown of GAS2 promoted the proliferation of hepatocytes(P<0.05).Furthermore,GAS2 overexpression impeded the G1-to-S cell cycle transition and arrested more G1 cells,particularly the elevation of sub G1(P<0.01).Apoptosis induced by GAS2 was dependent on p53,which was increased by etoposide addition.The expression of p53 and apoptosis markers was further enhanced when GAS2 was upregulated,but became diminished upon downregulation of GAS2.In the clinic specimen,GAS2 was downregulated in more than 60%of HCCs.The average fold changes of GAS2 expression in tumor tissues were significantly lower than those in paired non-tumor tissues(P<0.05).CONCLUSION GAS2 plays a vital role in HCC cell proliferation and apoptosis,possibly by regulating the cell cycle and p53-dependent apoptosis pathway.

Network pharmacology analysis combined with experimental verification of the molecular mechanism of Xihuang pill in treating liver cancer

Background:Xihuang pill is a kind of traditional Chinese medicine,which has been widely used in the treatment of kinds of cancer.However,there is still a lack of systematic understanding of the molecular mechanism of Xihuang pill in the treatment of liver cancer.In this work,we aim to explore the molecular mechanism of Xihuang pill in treating liver cancer.Methods:The functional components in Xihuang pill were collected from Traditional Chinese Medicine Database and Analysis Platform.The target genes of these components were also collected using Traditional Chinese Medicine Database and Analysis Platform.The target genes of liver cancer were predicted using GeneCards database.The intersecting genes were then analyzed with Venn diagrams.Kyoto Encyclopedia of Genes and Genomes and Database for Annotation,Visualization,and Integrated Discovery were used to analyze the pathway.Then,cell counting kit-8 was used to measure the half-maximal inhibitory concentration of Xihuang pills.The living dead cell staining method was used to observe the survival of cells.HepG2 cell apoptosis was tested by flow cytometry with fluorescein isothiocyanate/propidium iodide double staining method,and then the mitochondrial damage was also detected by flow cytometry.The expression of target genes was detected by quantitative real-time polymerase chain reaction.Results:A total of 130 compounds and 198 genes were identified as potential active ingredients and putative liver cancer‑related targets.We obtained 1,899 disease targets and 297 transcriptome targets from the database.Six drug-disease intersecting genes,CCNB1,BIRC5,TOP2A,ESR1,IGF2 and IGFBP3 were obtained.They are enrichment in apoptosis,PI3K-AKT signaling pathway,MAPK signaling pathway,pathways in cancer and p53 signaling pathway.Besides,it was found that the apoptosis rate of the HepG2 cells in Xihuang pill treated group was significantly higher than that of the control group.And the apoptosis rate gradually increased in a dose dependent manner of Xihuang pill treatment.Xihuang pill also induced the mitochondrial membrane potential damage.Compared with the control group,the expression level of CCNB1 and BIRC5 was induced,while the expression level of IGF2 was reduced after Xihuang pill treatment.Conclusion:Xihuang pill may act on six proteins(CCNB1,BIRC5,TOP2A,ESR1,IGF2 and IGFBP3)and cover multiple pathways to form a therapeutic network to treat liver cancer.

MAPK/ERK regulation of P53 in human epidermoid carcinoma cell line A431

Objective:To observe the impact of activation and inhibition of mitogen activated protein kinases(MAPK)/extracellular signalregulated protein kinase(ERK)signaling pathway on the proliferation and apoptosis of cutaneous squamous cell carcinoma(SCC).cells and investigate the interaction mechanism between MAPK/ERK signaling pathway and tumor suppressor gene P53 in SCC.Methods:Human A431 cells were cultured and divided into MAPK/ERK inhibition groups with low-,medium-and highconcentration of inhibitors(PD98059+DMSO),MAPK/ERK activation groups with low-,medium-and high-concentration of stimuli(IGF+PBS)and blank control group(DMSO).The cell proliferation in vitro was detected by MTT assay,with the cell apoptosis detected by flow cytometry(FCM)and the protein expression of P-ERK and P53 detected by western blot in each group.Results:The A431 cell proliferation was inhibited by different concentrations of PD98059 with a clear concentration-effect and time-effect relationship(p<.05);and the cell proliferation was promoted by the different concentrations of IGF with a clear concentration-effect and time-effect relationship(p<.05).The FCM results showed a significant increase in the apoptosis rate of A431 cells which were treated with PD98059,with a clear concentration-effect relationship(p<.05);while the apoptosis rate was decreased significantly after A431 cells were treated with IGF,also with a concentration-effect relationship(p<.05).The western blot results showed that the expression of P-ERK protein was decreased but the expression of P53 was increased after A431 cells were treated with PD98059.With the concentration of PD98059 going up,the decrease in P-ERK and the increase in P53 were more significant(p<.05);while the expression of P-ERK protein was increased but the expression of P53 was decreased after A431 cells were treated with IGF.With the concentration of IGF going up,the increase in P-ERK and the decrease in P53 were more significant(p<.05).According to Pearson correlation analysis,the expression of P53 was negatively correlated to that of P-ERK(p<.05).Conclusions:After MAPK/ERK signaling pathway was activated by IGF in A431 cells,the expression of pro-apoptotic factor P53 was decreased with the ability of cell proliferation enhanced and the ability of apoptosis reduced.However,after the inhibition of MAPK/ERK signaling pathway,the expression of pro-apoptotic factor P53 was increased with the ability of cell proliferation reduced and the ability of apoptosis increased.

Extract from Zanthoxylum piperitum Induces Apoptosis of AGS Gastric Cancer Cells through Akt/MDM2/p53 Signaling Pathway

Objective:To determine the effect of Zanthoxylum piperitum extracet(ZPE)on apoptosis and analyze anticancer substances in ZPE,changes in proteins related to apoptosis,and pathological changes in tumors in mouse.Methods:Fifteen 4-week-old female BALB/c nu/nu mice were divided into 3 groups depending on ZPE dose,with 5 in each group.AGS gastric carcinoma cells(1 x 10^(6) cells/200 jxL)were subcutaneously injected into the flank of each mouse.One week after the injection of AGS cells,ZPE was administered to the skin tissue[10 or 50 mg/(kg-d)]in the low-and high-dose groups,respectively for 20 days.Control animals were injected with vehicle only.After 3 weeks,the tumor was extracted and carried out for immunohistochemistry,the tendency of apoptosis and p53 in the body was checked using TdT-mediated dUTP nick-end labeling(TUNEL)assay.For 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide(MTT)assay,annexin V dead cell staining,cell cycle arrest and Western blotting,AGS gastric carcinoma cells were incubated with various concentrations of ZPE for 24 h.Cell survival rates were analyzed by MTT assays.Apoptosis was analyzed using annexin V dead cell staining and cell cycle arrest and measured using Muse cell analyzer.Results:High performance liquid chromatography(HPLC)analysis showed that ZPE contained organic sulfur compounds such as alliin and S-allylcysteine.MTT assay results revealed that ZPE(10-85»xg/mL)could effectively inhibit the growth of AGS gastric cancer cells at higher concentrations(P<0.05,P<0.01).The annexin V&dead cell staining assay and cell cycle arrest assay confirmed a dose-dependent increase in the apoptosis rate and G!phase in ZPE(10-70 jig/mL)groups.ZPE decreased the expression of anti-apoptotic proteins(p-Akt,p-MDM2,Bcl-2),while increased pro-apoptotic proteins(cleaved PARP,p53,pro-Caspase 3,Bax).TUNEL assays revealed an increase in cell apoptosis.Immunohistochemistry staining confirmed the involvement of p53.Conclusion:ZPE decreases AGS cell proliferation and induces apoptosis by inhibiting Akt and MDM2 expression.