Impact of MAPK Cascade Pathway and P53 Pathway upon Liver Transplant

Summary： The change and the role of MAPK cascade pathway and P53 pathway after liver transplantation were explored. Thirty-four punctured donor liver specimens and 10 normal liver specimens were classified as group A （no rejection, n=10）, group B （mild/moderate acute rejection, n=10）, group C （serious acute rejection, n=8）, group D （chronic rejection/fibrosis, n=6） and group E （control, n= 10）. By using immunohistochemistry, the expression levels of mitogen activated protein kinase （MAPK）, Ras and P53 proteins, and by in situ hybridization, MAPK and ras mRNA expression levels were detected. The results showed that the expression levels of MAPK and Ras proteins were increased by turns in groups A, B and C, and decreased by turns in groups D and E. The protein expression of P53 was higher in the treated groups. The expression of Ras, HSP70 mRNA was identical as that of protein. It is suggested that the MAPK cascade pathway and P53 pathway can protect the hepatocytes by different mechanisms after liver transplantation. MAPKs cascade pathway repairs hepatocyte injury or accelerates hepatocytes into proliferation or differentiation. P53 pathway blocks cell cycle within G1 phase to make hepatocyte repair or apoptosis to reduce disorder differentiation.

The study on DNA methylation of p53-Bax mitochondrial apoptosis pathway in cholangiocarcinoma

Objective： To study the methylation status of several genes on p53-Bax mitochondrial apoptosis pathway and clinical significance in cholangiocarcinoma. Methods： Promoter hypermethylation of DAPK, p14 and ASC genes were detected by methylation-specific PCR. p53 gene status （exon 5-8） were examined by automated sequencing, combined with the clinical documents of patients by statistics analysis. Results： （1） We found 66.7% of 36 cases cholangiocarcinoma had methylation of at least one tumor suppressor gene. The frequency of tumor suppressor gene methylation in cholangiocarcinoma was： p14 （24%）, DAPK （30.6%）, TMSI/ASC （36.1%）. The frequency of tumor suppressor gene methylation in tissues near cancer was： DAPK （5.6%）, TMS1/ASC （8.3%）. （2） p53 gene mutations were found in 22 of 36 patients （61.1%）. （3） There were no statistically relationship among the methylation of DAPK, p14 and ASC genes. There were negative relationship differences between the methylation of p14 and p53 gene mutation （P 〈 0.05）. （4） p53 gene mutation combined with the methylation of tumor suppressor were 14 cases （38.9%）. There were statistically differences on extent of pathologic biology, differentiation and invasion （P 〈 0.05）. Conclusion： Our study indicated that methylation of p53-Bax mitochondrial apoptosis pathway in cholangiocarcinoma was a common epigenetic event. Although the methylation of ASC, DAPK genes was low, it might be significance for early diagnosis, p53 gene mutation combined with the methylation of tumor suppressor might be relationship with pathologic biology, it trended to more malignancy.

Pien Tze Huang Inhibits Proliferation of Colorectal Cancer Cells through Suppressing PNO1 Expression and Activating p53/p21 Signaling Pathway

ObjectiveTo explore the regulatory effect of Pien Tze Huang (PZH) on targeting partner of NOB1 (PNO1) and it’s down-stream mediators in colorectal cancer (CRC) cells.MethodsQuantitative polymerase chain reaction was performed to determine mRNA levels of PNO1, TP53, and CDKN1A. Western blotting was performed to determine protein levels of PNO1, p53, and p21. HCT-8 cells were transduced with a lentivirus over-expressing PNO1. Colony formation assay was used to detect cell survival in PNO1 overexpression of HCT-8 cells after PZH treatment. Cell-cycle distribution, cell viability and cell apoptosis were performed to identify the effect of PNO1 overexpression on cell proliferation and apoptosis of HCT-8 cells after PZH treatment. Xenograft BALB/c nude mice bearing HCT116 cells transduced with sh-PNO1 or sh-Ctrl lentivirus were evaluated. Western blot assay was performed to detect PNO1, p53, p21 and PCNA expression in tumor sections. Terminal deoxynucleotidyl transferase dUTP nick end labling (TUNEL) assay was used to determine the apoptotic cells in tissues.ResultsPZH treatment decreased cell viability, down-regulated PNO1 expression, and up-regulated p53 and p21 expressions in HCT-8 cells (P<0.05). PNO1 overexpression attenuated the effects of PZH treatment, including the expression of p53 and p21, cell growth, cell viability, cell cycle arrest and cell apoptosis in vitro (P<0.05). PNO1 knockdown eliminated the effects of PZH treatment on tumor growth, inhibiting cell proliferation inhibition and apoptosis induction in vivo (P<0.05). Similarly, PNO1 knockdown attenuated the effects of PZH treatment on the down-regulation of PNO1 and up-regulation of p53 and p21 in vivo (P<0.05).ConclusionThe mechanism by which PZH induces its CRC anti-proliferative effect is at least in part by regulating the expression of PNO1 and its downstream targets p53 and p21.

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.

DTL facilitates the Fanconi anemia pathway for ultraviolet-induced DNA repair in retinal pigment epithelial cells

The excessive energy of light,especially the invisible rays with lower wavelength,is basically absorbed by retinal pigment epithelium(RPE)and usually causes DNA damage.The molecular mechanism behind DNA damage repair response to this frequent stress in RPE is not clearly understood.In this study,we determined that the Fanconi anemia(FA)pathway was activated in human RPE ARPE-19 cells after ultraviolet(UV)B and C treatment.Moreover,immunoprecipitation(IP)of FANCD2 indicated that denticleless E3 ubiquitin protein ligase homolog(DTL)closely interacted with FANCD2.Knockdown of DTL weakened the activity of the FA pathway in ARPE-19 cells responding to UV treatment.Finally,the DTL promoter was incubated with a biotin-labeled probe and pulled down by streptavidin beads followed by the genomic DNA sonication.p53 was indicated by mass spectrum and further determined by chromatin IP assay.Taken together,our results demonstrated that DTL regulated by p53 could activate the FA pathway for UV-induced DNA damage repair in retinal pigment epithelial cells.

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.

Real-time in situ observation of P53-mediated cascade activation of apoptotic pathways with nucleic acid multicolor fluorescent probes based on symmetrical gold nanostars

T-2 toxin,one of the most dangerous natural pollutants,induces apoptosis through multiple pathways.Amongst,P53 mediated apoptosis pathway,an important collection of molecules,plays a key role in cell vital activity.Real-time monitoring of upstream and downstream activation relationships of P53 mRNA,Bax mRNA,and cytochrome c(Cyt c)in signaling pathways is of great significance for understanding the apoptotic machinery in human physiology.In this work,a novel nucleic acid multicolor fluorescent probe,based on silica-coated symmetric gold nanostars(S-AuNSs@SiO_(2)),was developed for highly sensitive in situ real-time imaging of P53 mRNA,Bax mRNA,and Cyt c during T-2 toxin-induced apoptosis.The nucleic acid chains modified with carboxyl groups were modified on the surface of S-AuNSs@SiO_(2)by amide reaction.The complementary chains of targeted mRNA and the aptamer of targeted Cyt c were modified with different fluorophores,respectively,and successfully hybridized on S-AuNSs@SiO_(2)surface.When targets were present,the fluorescent chains bound to the targets and detached from the material,resulting in the quenched fluorescence being revived.The probes based on S-AuNSs showed excellent performance is partly ascribed to the presence of 20 symmetric“hot spots”.Notably,the amide-bonded probe exhibited excellent anti-interference capability against biological agents(nucleases and biothiols).During the real-time fluorescence imaging of T-2 toxin-induced apoptosis,the corresponding fluorescence signals of P53 mRNA,Bax mRNA,and Cyt c were observed sequentially.Therefore,S-AuNSs@SiO_(2)probe not only provides a novel tool for real-time monitoring of apoptosis pathways cascade but also has considerable potential in disease diagnosis and pharmaceutical medical.

Emodin induces apoptosis in human prostate cancer cell LNCaP

Aim： To elucidate effects and mechanisms of emodin in prostate cancer cells. Methods： Viability of emodin-treated LNCaP cells and PC-3 cells was measured by MTT assay. Following emodin treatments, DNA fragmentation was assayed by agarose gel electrophoresis. Apoptosis rate and the expression of Fas and FasL were assayed by flow cytometric analysis. The mRNA expression levels of androgen receptor （AR）, prostate-specific antigen （PSA）, p53, p21, Bcl-2, Bax, caspase-3, -8, -9 and Fas were detected by RT-PCR, and the protein expression levels of AR, p53 and p21 were detected by Western blot analysis. Results： In contrast to PC-3, emodin caused a marked increase in apoptosis and a decrease in cell proliferation in LNCaP cells. The expression of AR and PSA was decreased and the expression of p53 and p21 was increased as the emodin concentrations were increased. In the same time, emodin induced apoptosis of LNCaP cells through the upregulation of caspase-3 and -9, as well as the increase of Bax/Bcl-2 ratio. However, it did not involve modulation of Fas or caspase-8 protein expression. Conclusion： In prostate cancer cell line, LNCaP, emodin inhibites the proliferation by AR and p53-p21 pathways, and induces apoptosis via the mitochondrial pathway.

Oncolytic adenovirus SG600-IL24 selectively kills hepatocellular carcinoma cell lines

AIM: To investigate the effect of oncolytic adenovirus SG600-IL24 and replication-incompetent adenovirus Ad.IL-24 on hepatocellular carcinoma (HCC) cell lines and normal liver cell line. METHODS: HCC cell lines (HepG2, Hep3B and MHCC97L) and normal liver cell line (L02) with a different p53 status were infected with SG600-IL24 and Ad.IL-24, respectively. Melanoma differentiation-associated (MDA)-7/interleukin (IL)-24 mRNA and protein expressions in infected cells were detected by reverse transcription-polymerase chain reaction (RT-PCR), enzymelinked immunosorbent assay (ELISA), and Western blotting, respectively. Apoptosis of HCC cells and normal liver cells was detected by cytometric assay with Hoechst33258 staining. 3-(4,5-dimethylthiazol-2-yl)-2,5diphenyltetrazolium bromide (MTT) assay was used to investigate proliferation of HCC cells and normal liver cells, and cell cycle was assayed by flow cytometry. RESULTS: RT-PCR, ELISA and Western blotting showed that the exogenous MDA-7/IL-24 gene was highly expressed in cells infected with SG600-IL24. MTT indicated that SG600-IL24 could suppress the growth of HepG2, Hep3B, MHCC97L, with an inhibition rate of 75% ± 2.5%, 85% ± 2.0%, 72% ± 1.8%, respectively (P < 0.01), promote the apoptosis of HepG2, Hep3B, MHCC97L, with an apoptosis rate of 56.59% ± 4.0%, 78.36% ± 3.5%, 43.39% ± 2.5%, respectively (P < 0.01), and block the HCC cell lines in the G2/M phase with a blocking rate of 35.4% ± 4.2%, 47.3% ± 6.2%, 42% ± 5.0%, respectively (P < 0.01) but not the normal liver cell line in a p53-independent manner. CONCLUSION: SG600-IL24 can selectively suppress the proliferation and apoptosis of HCC cell lines in vitro but not normal liver cell line L02 in a p53-independent manner. Compared with Ad.IL-24, SG600-IL24 can significantly enhance the antitumor activity in HCC cell lines.

Huanglian decoction suppresses the growth of hepatocellular carcinoma cells by reducing CCNB1 expression

BACKGROUND Hepatocellular carcinoma(HCC)is one of the most prevalent cancers in human populations worldwide.Huanglian decoction is one of the most important Chinese medicine formulas,with the potential to treat cancer.AIM To investigate the role and mechanism of Huanglian decoction on HCC cells.METHODS To identify differentially expressed genes(DEGs),we downloaded gene expression profile data from The Cancer Genome Atlas Liver Hepatocellular Carcinoma and Gene Expression Omnibus(GSE45436)databases.We obtained phytochemicals of the four herbs of Huanglian decoction from the Traditional Chinese Medicine Systems Pharmacology Database and Analysis Platform.We also established a regulatory network of DEGs and drug target genes and subsequently analyzed key genes using bioinformatics approaches.Furthermore,we conducted in vitro experiments to explore the effect of Huanglian decoction and to verify the predictions.In particular,the CCNB1 gene was knocked down to verify the primary target of this decoction.Through the identification of the expression levels of key proteins,we determined the primary mechanism of Huanglian decoction in HCC.RESULTS Based on the results of the network pharmacological analysis,we revealed 5 bioactive compounds in Huanglian decoction that act on HCC.In addition,a protein-protein interaction network analysis of the target genes of these five compounds as well as expression and prognosis analyses were performed in tumors.CCNB1 was confirmed to be the primary gene that may be highly expressed in tumors and was significantly associated with a worse prognosis.We also noted that CCNB1 may serve as an independent prognostic indicator in HCC.Moreover,in vitro experiments demonstrated that Huanglian decoction significantly inhibited the growth,migration,and invasiveness of HCC cells and induced cell apoptosis and G2/M phase arrest.Further analysis showed that the decoction may inhibit the growth of HCC cells by downregulating the CCNB1 expression level.After Huanglian decoction treatment,the expression levels of Bax,caspase 3,caspase 9,p21 and p53 in HCC cells were increased,while the expression of CDK1 and CCNB1 was significantly decreased.The p53 signaling pathway was also found to play an important role in this process.CONCLUSION Huanglian decoction has a significant inhibitory effect on HCC cells.CCNB1 is a potential therapeutic target in HCC.Further analysis showed that Huanglian decoction can inhibit HCC cell growth by downregulating the expression of CCNB1 to activate the p53 signaling pathway.

Oncogenic potential of IDH1R132C mutant incholangiocarcinoma development in mice

AIM: To investigate whether IDH1R132 C mutant in combination with loss of p53 and activated Notch signaling promotes intrahepatic cholangiocarcinoma(ICC) development.METHODS: We applied hydrodynamic injection and sleeping beauty mediated somatic integration to induce loss of p53(via sh P53), activation of Notch [via intracellular domain of Notch1(NICD)] and/or overexpression of IDH1R132 C mutant together with the sleeping beauty transposase into the mouse liver. Specifically, we co-expressed sh P53 and NICD(sh P53/NICD, n = 4), sh P53 and IDH1R132C(sh P53/IDH1R132 C, n = 3), NICD and IDH1R132C(NICD/IDH1R132 C, n = 4), as well as NICD, sh P53 and IDH1R132C(NICD/sh P53/IDH1R132 C, n = 9) in mice. Mice were monitored for liver tumor development and euthanized at various time points. Liver histology was analyzed by hematoxylin and eosin staining. Molecular features of NICD/sh P53/IDH1R132 C ICC tumor cells were characterized by Myc tag, Flag tag, Ki-67, p-Erk and p-AKT immunohistochemical staining. Desmoplastic reaction in tumor tissues was studied by Picro-Sirius red staining.RESULTS: We found that co-expression of sh P53/NICD, sh P53/IDH1R132 C or NICD/IDH1R132 C did not lead to liver tumor formation. In striking contrast, coexpression of NICD/sh P53/IDH1R132 C resulted in ICC development in mice(P < 0.01). The tumors could be identified as early as 12 wk post hydrodynamic injection. Tumors rapidly progressed, and by 18 wk post hydrodynamic injection, multiple cystic lesions could be identified on the liver surface. NICD/sh P53/IDH1R132 C liver tumors shared multiple histological features of human ICCs, including hyperplasia of irregular glands. Importantly, all tumor cells were positive for the biliary epithelial cell marker cytokeratin 19. Extensive collagen fibers could be visualized in tumor tissues using Sirus red staining, duplicating the desmoplastic reaction observed in human ICC. Tumors were highly proliferative and expressed ectopically injected genes. Together these studies supported that NICD/sh P53/IDH1R132 C liver tumors were indeed ICCs. Finally, no p-AKT or p-ERK positive staining was observed, suggesting that NICD/sh P53/IDH1R132 C driven ICC development was independent of AKT/m TOR and Ras/MAPK signaling cascades. CONCLUSION: We have generated a simple, nongermline murine ICC model with activated Notch, loss of p53 and IDH1R132 C mutant. The study supported the oncogenic potential of IDH1R132 C.

Expressions of the Cell Cycle Relative Proteins in Esophageal Cancer Tissues

The aim of the research is to investigate the expression of the cell cycle relative proteins (P53, P16, Cyclin D1, and Ki67) in Esophageal Cancer (EC) patients of the Chaoshan area, China. In China, Chaoshan has the high incidence of EC. Different areas have shown different rate for expression of these proteins in EC. We investigated the expression of p53, p16, cyclinD1, and ki67 for the first time in Chaoshan. In this research, DNA was extracted from formalin fixed and paraffin embedded tissues of esophageal cancer (EC) patients. The expression level of proteins cycle was detected by using immunohistochemistry (IHC). And the data was checked by χ2 test or Fisher’s exact test of SPSS17.0. The positive immunohistochemical staining of p53, p16, cyclinD1, and ki67 were observed in 65.7% 39.2%, 69.1%, and 83.5% specimens respectively. There was a positive correlation between p53 positive staining and p16, cyclinD1, ki67 staining at p < 0.05. CyclinD1 has the high correlation with ki67 at p < 0.05. A significant inverse correlation was considered between the expression of p16 and cyclinD1 and there was no correlation observed between p16 and ki67. In Conclusion, this study demonstrated the high expression of p53, Cyclin D1 and Ki67 and low expression of P16 and the association of these cell cycle relative proteins in esophageal cancer are new data in Chaoshan area of China. Geographical distribution of EC on the molecular basis is revealed in this research.

p53 promotes AKT and SP1-dependent metabolism through the pentose phosphate pathway that inhibits apoptosis in response to Nutlin-3a

Nutlin-3a is a MDM2 antagonist and preclinical drug that activates p53. Cells with MDM2 gene amplification are especially prone to Nutlin-3a-induced apoptosis, though the basis for this is unclear. Glucose metabolism can inhibit apoptosis in response to Nutlin-3a through mechanisms that are incompletely understood. Glucose metabolism through the pentose phosphate pathway （PPP） produces NADPH that can protect cells from potentially lethal reactive oxygen species （ROS）. We compared apoptosis and glucose metabolism in cancer cells with and without MDM2 gene amplification treated with Nutlin-3a. Apoptosis in MDM2-amplified cells was associated with a reduction in glycolysis and the PPP, reduced NADPH, increased ROS, and depletion of the transcription factor SP1, which normally promotes PPP gene expression. In contrast, glycolysis and the PPP were maintained or increased in MDM2 non-amplified cells treated with Nutlin-3a. This was dependent on p53-mediated AKT activation and was associated with maintenance of SP1 and continued expression of PPP genes. Knockdown or inhibition of AKT, SP1, or the PPP sensitized MDM2-non-amplified cells to apoptosis. The data indicate that p53 promotes AKT and SP1-dependent activation of the PPP that protects cells from Nutlin-3a-induced apoptosis. These findings provide insight into how glucose metabolism reduces Nutlin-3a-induced apoptosis, and also provide a mechanism for the heightened sensitivity of MDM2-amplified cells to apoptosis in response to Nutlin-3a.

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.

Oncogenic Ras/PI3K/Her2 share a common pathway in promoting cancer metastasis via inhibiting expression of p53-related ΔNp63α

Subject Code:H16With the support by the National Natural Science Foundation of China,a collaborative study by the research groups led by Prof.Xiao Zhixiong(肖智雄)from the College of Life Science,Sichuan University demonstrates thatΔNp63αis a common inhibitory target in oncogenic PI3K/Ras/Her2-induced

Mapping the Binding Site of P53 on UBC9 by NMR Spectroscopy

Human UBC9 is a member of the E2 family of proteins. However, instead of conjugating to ubiquitin, it conjugates to a ubiquitin homologue SUMO-1 (also known as UBL1, GMP1, SMTP3, PICT-1 and sentrin). The SUMO-1 conjugation pathway is very similar to that of ubiquitin with regard to the primary sequences of the ubiquitin activating enzymes (E1), the three-dimensional structures of the ubiquitin conjugating enzymes (E2), and the chemistry of the overall conjugation pathway. The interaction of p53 and UBC9, the E2 of the SUMO-1 pathway, has been studied by nuclear magnetic resonance spectroscopy. A peptide corresponding to the nuclear localization domain of p53 specifically interacts with UBC9 and this interaction is likely to be important for conjugation of p53 with SUMO-1. The largest chemical shift changes on UBC9 occur at residues 94 and 129-135. This region is adjacent to the active site and has significant dynamic behavior on the μs-ms and ps-ns timescales. Correlation of chemical shift changes and mobility of these residues further suggest the importance of these residues in substrate recognition.

Oscillatory behavior of p53-Mdm2 system driven by transcriptional and translational time delays

Biological experiments clarify that p53-Mdm2 module is the core of tumor network and p53 oscillation plays an important role in determining the tumor cell fate.In this paper,we investigate the effect of time delay on the oscillatory behavior induced by Hopf bifurcation in p53-Mdm2 system.First,the stability of the unique positive equilibriurm point and the existence of Hopf bifurcation are investigated by using the time delay as the bifurcation parameter and by applying the bifurcation theory.Second,the explicit criteria determining the direction of Hopf bifurcation and the stability of bifurcating periodic solutions are developed based on the normal form theory and the center manifold theorem.In addition,the combination of numerical simulation results and theoretical calculation results indicates that time delays in p53-Mdm2 system are critical for p53 oscillations.The results may help us to better understand the biological functions of p53 pathway and provide clues for treatment of cancer.

Wip1 inhibits neutrophil extracellular traps to promote abscess formation in mice by directly dephosphorylating Coronin-1a

Neutrophil extracellular traps (NETs) participate in the rapid inhibition and clearance of pathogens during infection;however, the molecular regulation of NET formation remains poorly understood. In the current study, we found that inhibition of the wild-type p53-induced phosphatase 1 (Wip1) significantly suppressed the activity of Staphylococcus aureus (S. aureus) and accelerated abscess healing in S. aureus-induced abscess model mice by enhancing NET formation. A Wip1 inhibitor significantly enhanced NET formation in mouse and human neutrophils in vitro. High-resolution mass spectrometry and biochemical assays demonstrated that Coro1a is a substrate of Wip1. Further experiments also revealed that Wip1 preferentially and directly interacts with phosphorylated Coro1a than compared to unphosphorylated inactivated Coro1a. The phosphorylated Ser426 site of Coro1a and the 28–90 aa domain of Wip1 are essential for the direct interaction of Coro1a and Wip1 and for Wip1 dephosphorylation of p-Coro1a Ser426. Wip1 deletion or inhibition in neutrophils significantly upregulated the phosphorylation of Coro1a-Ser426, which activated phospholipase C and subsequently the calcium pathway, the latter of which promoted NET formation after infection or lipopolysaccharide stimulation. This study revealed Coro1a to be a novel substrate of Wip1 and showed that Wip1 is a negative regulator of NET formation during infection. These results support the potential application of Wip1 inhibitors to treat bacterial infections.

A novel inhibitor of MDM2 oncogene blocks metastasis of hepatocellular carcinoma and overcomes chemoresistance

Overexpression of the MDM2 oncogene and mutations in the p53 tumor suppressor commonly occur in hepatocellular carcinoma(HCC)and are associated with increased mortality due to this disease.Inhibiting MDM2 has been demonstrated to be a valid approach for the treatment of HCC.However,most of the MDM2 inhibitors evaluated to date have been designed to block the MDM2 and p53 binding,and have limited efficacy against tumors with mutant or deficient p53.In the present study,we developed a novel MDM2 inhibitor(termed SP141)that has direct effects on MDM2 and exerts anti-HCC activity independent of the p53 status of the cancer cells.We demonstrate that SP141 inhibits cell growth and prevents cell migration and invasion,independent of p53.Mechanistically,SP141 directly binds the MDM2 protein and promotes MDM2 degradation.The inhibition of MDM2 by SP141 also increases the sensitivity of HCC cells to sorafenib.In addition,in orthotopic and patient-derived xenograft models,SP141 inhibits MDM2 expression and suppresses tumor growth and metastasis,without any host toxicity.Furthermore,the inhibition of MDM2 by SP141 is essential for its anti-HCC activities.These results provide support for the further development of SP141 as a lead candidate for the treatment of HCC.