BACKGROUND Cancerous inhibitor of protein phosphatase 2A(CIP2A)is a newly discovered oncogene.It is an active cell proliferation regulatory factor that inhibits tumor apoptosis in gastric cancer(GC)cells.CIP2A is func...BACKGROUND Cancerous inhibitor of protein phosphatase 2A(CIP2A)is a newly discovered oncogene.It is an active cell proliferation regulatory factor that inhibits tumor apoptosis in gastric cancer(GC)cells.CIP2A is functionally related to chemoresistance in various types of tumors according to recent studies.The underlying mechanism,however,is unknown.Further,the primary treatment regimen for GC is oxaliplatin-based chemotherapy.Nonetheless,it often fails due to chemoresistance of GC cells to oxaliplatin.AIM The goal of this study was to examine CIP2A expression and its association with oxaliplatin resistance in human GC cells.METHODS Immunohistochemistry was used to examine CIP2A expression in GC tissues and adjacent normal tissues.CIP2A expression in GC cell lines was reduced using small interfering RNA.After confirming the silencing efficiency,3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide tetrazolium and flow cytometry assays were used to evaluate cell proliferation and apoptosis caused by oxaliplatin treatment.Further,the key genes and protein changes were verified using realtime quantitative reverse transcription PCR and Western blotting,respectively,before and after intervention.For bioinformatics analysis,we used the R software and Bioconductor project.For statistical analysis,we used GraphPad Prism 6.0 and the Statistical Package for the Social Sciences software version 20.0(IBM,Armonk,United States).RESULTS A high level of CIP2A expression was associated with tumor size,T stage,lymph node metastasis,Tumor Node Metastasis stage,and a poor prognosis.Further,CIP2A expression was higher in GC cells than in normal human gastric epithelial cells.Using small interfering RNA against CIP2A,we discovered that CIP2A knockdown inhibited cell proliferation and significantly increased GC cell sensitivity to oxaliplatin.Moreover,CIP2A knockdown enhanced oxaliplatin-induced apoptosis in GC cells.Hence,high CIP2A levels in GC may be a factor in chemoresistance to oxaliplatin.In human GC cells,CIP2A regulated protein kinase B phosphorylation,and chemical inhibition of the protein kinase B signaling pathway was significantly associated with increased sensitivity to oxaliplatin.Therefore,the protein kinase B signaling pathway was correlated with CIP2Aenhanced chemoresistance of human GC cells to oxaliplatin.CONCLUSION CIP2A expression could be a novel therapeutic strategy for chemoresistance in GC.展开更多
AIM:To explore the alteration of tyrosine phosphatase SHP-2 protein expression in gastric cancer and to assess its prognostic values.METHODS:Three hundred and five consecutive cases of gastric cancer were enrolled int...AIM:To explore the alteration of tyrosine phosphatase SHP-2 protein expression in gastric cancer and to assess its prognostic values.METHODS:Three hundred and five consecutive cases of gastric cancer were enrolled into this study.SHP-2 expression was carried out in 305 gastric cancer specimens,of which 83 were paired adjacent normal gastric mucus samples,using a tissue microarray immunohistochemical method.Correlations were analyzed between expression levels of SHP-2 protein and tumor parameters or clinical outcomes.Serum anti-Helicobacter pylori(H.pylori) immunoglobulin G was detected with enzyme-linked immunosorbent assay.Cox proportional hazards model was used to evaluate prognostic values by compassion of the expression levels of SHP-2 and disease-specific survivals in patients.RESULTS:SHP-2 staining was found diffuse mainly in the cytoplasm and the weak staining was also observed in the nucleus in gastric mucosa cells.Thirty-two point five percent of normal epithelial specimen and 62.6% of gastric cancer specimen were identified to stain with SHP-2 antibody positively(P < 0.001).Though SHP-2 staining intensities were stronger in the H.pylori(+) group than in the H.pylori(-) group,no statistically significant difference was found in the expression levels of SHP-2 between H.pylori(+) and H.pylori(-) gastric cancer(P = 0.40).The SHP-2 expression in gastric cancer was not significantly associated with cancer stages,lymph node metastases,and distant metastasis of the tumors(P = 0.34,P = 0.17,P = 0.52).Multivariate analysis demonstrated no correlation between SHP-2 expression and disease-free survival(P = 0.86).CONCLUSION:Increased expression of SHP-2 protein in gastric cancer specimen suggesting the aberrant upregulation of SHP-2 protein might play an important role in the gastric carcinogenesis.展开更多
Oleanolic acid derivatives act as newer protein tyrosine phosphatase 1B （PTP-1B） inhibitors for type 2 diabetes mellitus （T2DM）. In order to understand the structural requirement of PTP-1B inhibitors, 52 oleanolic...Oleanolic acid derivatives act as newer protein tyrosine phosphatase 1B （PTP-1B） inhibitors for type 2 diabetes mellitus （T2DM）. In order to understand the structural requirement of PTP-1B inhibitors, 52 oleanolic acid derivatives were divided into a training set （34 compounds） and a test set （18 compounds）. The highly reliable and predictive 3D-QSAR models were constructed by CoMFA, CoMSIA and topomer CoMFA methods, respectively. The results showed that the cross validated coefficient （q2） and non-cross-validated coefficient （R2） were 0.554 and 0.999 in the CoMFA model, 0.675 and 0.971 in the CoMSIA model, and 0.628 and 0.939 in the topomer CoMFA model, which suggests that three models are robust and have good exterior predictive capabilities. Furthermore, ten novel inhibitors with much higher inhibitory potency were designed. Our design strategy was that （i） the electronegative substituents （Cl, -CH2OH, OH and -CH2Cl） were introduced into the double bond of ring C, （ii） the hydrogen bond acceptor groups （C≡N and N atom）, electronegative groups （C≡N, N atom, -COOH and -COOCH3） and bulky substituents （C6H5N） were connected to the C-3 position, which would result in generating potent and selective PTP-1B inhibitors. We expect that the results in this paper have the potential to facilitate the process of design and to develop new potent PTP-1B inhibitors.展开更多
This study investigated the expression and prognostic value of SHP-2 in cervical cancer caused by human papillomavirus (HPV) infection. Forty-five specimens from patients with cervical cancer (stageⅠ-Ⅲ), 32 specimen...This study investigated the expression and prognostic value of SHP-2 in cervical cancer caused by human papillomavirus (HPV) infection. Forty-five specimens from patients with cervical cancer (stageⅠ-Ⅲ), 32 specimens from patients with cervical intraepithelial neoplasia (CIN) (Ⅰ, Ⅱ) and 20 normal cervical samples from patients with hysteromyoma were collected in Department of Pathology for comparison. The expression levels of SHP-2 and IFN-β proteins were detected by using immunohistochemistry. The mRNA expression level of SHP-2 was detected by using quantitative real-time polymerase chain reaction (PCR). HPVs were detected by HPV GenoArray Test. The Spearman correlation was used to compare the expression level of SHP-2 in HPV infected cervical cancer vs non-HPV infected normal cervix. The level of SHP-2 protein expression in the cancer tissues (88.8%) was significantly higher than in CIN tissues (62.5%) and normal cervixes (45%) (P<0.05 and P<0.05, respectively). The SHP-2 mRNA levels in the cancer tissues were upregulated as compared with those in the normal cervixes (P<0.05). Twenty-one (46.7%) cervical cancers, 25 (78.1%) CINs and 17 (85%) normal cervixes showed IFN-β positive staining in cytoplasm. There was statistically significant difference in the expression rate of IFN-β between cervical cancer and normal cervix (χ2=8.378, P<0.05) as well as between cervical cancer and CIN (χ2=7.695, P<0.05). HPV16/18 infections could be found in normal cervixs (15%), CINs (68.7%) and cervical cancers (84.4%). There was a correlation between HPV infection and SHP-2 expression in cervical cancer (rs=0.653, P<0.05). SHP-2 may be a useful prognostic and diagnostic indicator for HPV infected cervical cancer. In cervical cancers, SHP-2 mRNA and protein overexpression was associated with IFN-β lower-expression.展开更多
Protein phosphatases play essential roles as negative regulators of kinases and signaling cascades involved in cytoskeletal organization.Protein phosphatase 2A(PP2A)is highly conserved and is the predominant serine/th...Protein phosphatases play essential roles as negative regulators of kinases and signaling cascades involved in cytoskeletal organization.Protein phosphatase 2A(PP2A)is highly conserved and is the predominant serine/threonine phosphatase in the nervous system,constituting more than 70%of all neuronal phosphatases.PP2A is involved in diverse regulatory functions,including cell cycle progression,apoptosis,and DNA repair.Although PP2A has historically been identified as a tumor suppressor,inhibition of PP2A has paradoxically demonstrated potential as a therapeutic target for various cancers.LB100,a water-soluble,small-molecule competitive inhibitor of PP2A,has shown particular promise as a chemo-and radio-sensitizing agent.Preclinical success has led to a profusion of clinical trials on LB100 adjuvant therapies,including a phase I trial in extensive-stage small-cell lung cancer,a phase I/II trial in myelodysplastic syndrome,a phase II trial in recurrent glioblastoma,and a completed phase I trial assessing the safety of LB100 and docetaxel in various relapsed solid tumors.Herein,we review the development of LB100,the role of PP2A in cancer biology,and recent advances in targeting PP2A inhibition in immunotherapy.展开更多
Polycomb group proteins represent a global silencing system involved in development regulation.In specific,they regulate the transition from proliferation to differentiation,contributing to stem-cell maintenance and i...Polycomb group proteins represent a global silencing system involved in development regulation.In specific,they regulate the transition from proliferation to differentiation,contributing to stem-cell maintenance and inhibiting an inappropriate activation of differentiation programs.Enhancer of Zeste Homolog 2(EZH2) is the catalytic subunit of Polycomb repressive complex 2,which induces transcriptional inhibition through the tri-methylation of histone H3,an epigenetic change associated with gene silencing.EZH2 expression is high in precursor cells while its level decreases in differentiated cells.EZH2 is upregulated in various cancers with high levels associated with metastatic cancer and poor prognosis.Indeed,aberrant expression of EZH2 causes the inhibition of several tumor suppressors and differentiation genes,resulting in an uncontrolled proliferation and tumor formation.This editorial explores the role of Polycomb repressive complex 2 in cancer,focusing in particular on EZH2.The canonical function of EZH2 in gene silencing,the non-canonical activities as the methylation of other proteins and the role in gene transcriptional activation,were summarized.Moreover,mutations of EZH2,responsible for an increased methyltransferase activity in cancer,were recapitulated.Finally,various drugs able to inhibit EZH2 with different mechanism were described,specifically underscoring the effects in several cancers,in order to clarify the role of EZH2 and understand if EZH2 blockade could be a new strategy for developing specific therapies or a way to increase sensitivity of cancer cells to standard therapies.展开更多
Acute pancreatitis is an inflammation of the pancreas that may lead to systemic inflammatory response syndrome and death due to multiple organ failure. Acinar cells, together with leukocytes, trigger the inflammatory ...Acute pancreatitis is an inflammation of the pancreas that may lead to systemic inflammatory response syndrome and death due to multiple organ failure. Acinar cells, together with leukocytes, trigger the inflammatory cascade in response to local damage of the pancreas. Amplification of the inflammatory cascade requires up-regulation of proinflammatory cytokines and this process is mediated not only by nuclear factor κB but also by chromatinmodifying complexes and chromatin remodeling. Among the different families of histone acetyltransferases, the p300/CBP family seems to be particularly associated with the inflammatory process. cAMP activates gene expression via the cAMP-responsive element (CRE) and the transcription factor CRE-binding protein (CREB). CREB can be phosphorylated and activated by different kinases, such as protein kinase A and MAPK, and then it recruits the histone acetyltransferase co-activator CREB-binding protein (CBP) and its homologue p300. The recruitment of CBP/p300 and changes in the level of histone acetylation are required for transcription activation. Transcriptional repression is also a dynamic and essential mechanism of down-regulation of genes for resolution of inflammation, which seems to be mediated mainly by protein phosphatases (PP1, PP2A and MKP1) and histone deacetylases(HDACs) .Class HDACs are key transcriptional regulators whose activities are controlled via phosphorylationdependent nucleo/cytoplasmic shuttling. PP2A is responsible for dephosphorylation of class HDACs, triggeringnuclear localization and repression of target genes, whereas phosphorylation triggers cytoplasmic localization leading to activation of target genes. The potential benefit from treatment with phosphodiesterase inhibitors and histone deacetylase inhibitors is discussed.展开更多
背景与目的:蛋白磷酸酶2A抑制剂-2(inhibitor 2 of protein phosphatase 2A,I2PP2A)在包括胃癌的多种肿瘤中过度表达,提示其可能在胃癌的发生中发挥重要作用。为进一步探讨I2PP2A的功能及其在胃癌发生中的作用,建立稳定抑制I2PP2A基因...背景与目的:蛋白磷酸酶2A抑制剂-2(inhibitor 2 of protein phosphatase 2A,I2PP2A)在包括胃癌的多种肿瘤中过度表达,提示其可能在胃癌的发生中发挥重要作用。为进一步探讨I2PP2A的功能及其在胃癌发生中的作用,建立稳定抑制I2PP2A基因表达的人胃癌BGC823细胞株。方法:筛选出I2PP2A基因的RNA干扰(RNA interference,RNAi)有效靶序列,合成靶序列的Oligo DNA并构建p GLV2_sh RNA_I2PP2A慢病毒载体,酶切和测序鉴定正确后,经病毒包装,感染BGC823细胞,经嘌呤霉素筛选稳定表达细胞株,通过实时定量PCR(real-time PCR,RT-PCR)和蛋白[质]印迹法(Western blot)鉴定I2PP2A的表达。结果:重组慢病毒质粒经测序鉴定正确;RT-PCR和Western blot证实干扰I2PP2A后,BGC823细胞株中I2PP2A表达水平明显降低,抑制率约为90%。结论:成功构建了I2PP2A sh RNA慢病毒表达载体,建立了稳定抑制I2PP2A基因表达的人胃癌BGC823细胞株,为进一步研究I2PP2A在胃癌发生中的作用提供了可靠的细胞模型。展开更多
基金Supported by This work was supported by the Natural Science Foundation of Gansu Province,China,No.17JR5RA272 and No.22JR5RA923the Research Fund Project of The First Hospital of Lanzhou University,No.ldyyyn2021-120,No.ldyyyn2020-98 and No.ldyyyn2021-30.
文摘BACKGROUND Cancerous inhibitor of protein phosphatase 2A(CIP2A)is a newly discovered oncogene.It is an active cell proliferation regulatory factor that inhibits tumor apoptosis in gastric cancer(GC)cells.CIP2A is functionally related to chemoresistance in various types of tumors according to recent studies.The underlying mechanism,however,is unknown.Further,the primary treatment regimen for GC is oxaliplatin-based chemotherapy.Nonetheless,it often fails due to chemoresistance of GC cells to oxaliplatin.AIM The goal of this study was to examine CIP2A expression and its association with oxaliplatin resistance in human GC cells.METHODS Immunohistochemistry was used to examine CIP2A expression in GC tissues and adjacent normal tissues.CIP2A expression in GC cell lines was reduced using small interfering RNA.After confirming the silencing efficiency,3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide tetrazolium and flow cytometry assays were used to evaluate cell proliferation and apoptosis caused by oxaliplatin treatment.Further,the key genes and protein changes were verified using realtime quantitative reverse transcription PCR and Western blotting,respectively,before and after intervention.For bioinformatics analysis,we used the R software and Bioconductor project.For statistical analysis,we used GraphPad Prism 6.0 and the Statistical Package for the Social Sciences software version 20.0(IBM,Armonk,United States).RESULTS A high level of CIP2A expression was associated with tumor size,T stage,lymph node metastasis,Tumor Node Metastasis stage,and a poor prognosis.Further,CIP2A expression was higher in GC cells than in normal human gastric epithelial cells.Using small interfering RNA against CIP2A,we discovered that CIP2A knockdown inhibited cell proliferation and significantly increased GC cell sensitivity to oxaliplatin.Moreover,CIP2A knockdown enhanced oxaliplatin-induced apoptosis in GC cells.Hence,high CIP2A levels in GC may be a factor in chemoresistance to oxaliplatin.In human GC cells,CIP2A regulated protein kinase B phosphorylation,and chemical inhibition of the protein kinase B signaling pathway was significantly associated with increased sensitivity to oxaliplatin.Therefore,the protein kinase B signaling pathway was correlated with CIP2Aenhanced chemoresistance of human GC cells to oxaliplatin.CONCLUSION CIP2A expression could be a novel therapeutic strategy for chemoresistance in GC.
基金Supported by National Natural Science Foundation of China,No. 81072369Natural Science Foundation of Jilin Province,China,No. 200905131
文摘AIM:To explore the alteration of tyrosine phosphatase SHP-2 protein expression in gastric cancer and to assess its prognostic values.METHODS:Three hundred and five consecutive cases of gastric cancer were enrolled into this study.SHP-2 expression was carried out in 305 gastric cancer specimens,of which 83 were paired adjacent normal gastric mucus samples,using a tissue microarray immunohistochemical method.Correlations were analyzed between expression levels of SHP-2 protein and tumor parameters or clinical outcomes.Serum anti-Helicobacter pylori(H.pylori) immunoglobulin G was detected with enzyme-linked immunosorbent assay.Cox proportional hazards model was used to evaluate prognostic values by compassion of the expression levels of SHP-2 and disease-specific survivals in patients.RESULTS:SHP-2 staining was found diffuse mainly in the cytoplasm and the weak staining was also observed in the nucleus in gastric mucosa cells.Thirty-two point five percent of normal epithelial specimen and 62.6% of gastric cancer specimen were identified to stain with SHP-2 antibody positively(P < 0.001).Though SHP-2 staining intensities were stronger in the H.pylori(+) group than in the H.pylori(-) group,no statistically significant difference was found in the expression levels of SHP-2 between H.pylori(+) and H.pylori(-) gastric cancer(P = 0.40).The SHP-2 expression in gastric cancer was not significantly associated with cancer stages,lymph node metastases,and distant metastasis of the tumors(P = 0.34,P = 0.17,P = 0.52).Multivariate analysis demonstrated no correlation between SHP-2 expression and disease-free survival(P = 0.86).CONCLUSION:Increased expression of SHP-2 protein in gastric cancer specimen suggesting the aberrant upregulation of SHP-2 protein might play an important role in the gastric carcinogenesis.
基金Supported by the Natural Science Foundation of Guangxi Province(Nos.2013GXNSFAA019019 and 2013GXNSFAA019041)
文摘Oleanolic acid derivatives act as newer protein tyrosine phosphatase 1B （PTP-1B） inhibitors for type 2 diabetes mellitus （T2DM）. In order to understand the structural requirement of PTP-1B inhibitors, 52 oleanolic acid derivatives were divided into a training set （34 compounds） and a test set （18 compounds）. The highly reliable and predictive 3D-QSAR models were constructed by CoMFA, CoMSIA and topomer CoMFA methods, respectively. The results showed that the cross validated coefficient （q2） and non-cross-validated coefficient （R2） were 0.554 and 0.999 in the CoMFA model, 0.675 and 0.971 in the CoMSIA model, and 0.628 and 0.939 in the topomer CoMFA model, which suggests that three models are robust and have good exterior predictive capabilities. Furthermore, ten novel inhibitors with much higher inhibitory potency were designed. Our design strategy was that （i） the electronegative substituents （Cl, -CH2OH, OH and -CH2Cl） were introduced into the double bond of ring C, （ii） the hydrogen bond acceptor groups （C≡N and N atom）, electronegative groups （C≡N, N atom, -COOH and -COOCH3） and bulky substituents （C6H5N） were connected to the C-3 position, which would result in generating potent and selective PTP-1B inhibitors. We expect that the results in this paper have the potential to facilitate the process of design and to develop new potent PTP-1B inhibitors.
基金supported by a grant from the National Natu-ral Science Foundation of China(No.30973191)
文摘This study investigated the expression and prognostic value of SHP-2 in cervical cancer caused by human papillomavirus (HPV) infection. Forty-five specimens from patients with cervical cancer (stageⅠ-Ⅲ), 32 specimens from patients with cervical intraepithelial neoplasia (CIN) (Ⅰ, Ⅱ) and 20 normal cervical samples from patients with hysteromyoma were collected in Department of Pathology for comparison. The expression levels of SHP-2 and IFN-β proteins were detected by using immunohistochemistry. The mRNA expression level of SHP-2 was detected by using quantitative real-time polymerase chain reaction (PCR). HPVs were detected by HPV GenoArray Test. The Spearman correlation was used to compare the expression level of SHP-2 in HPV infected cervical cancer vs non-HPV infected normal cervix. The level of SHP-2 protein expression in the cancer tissues (88.8%) was significantly higher than in CIN tissues (62.5%) and normal cervixes (45%) (P<0.05 and P<0.05, respectively). The SHP-2 mRNA levels in the cancer tissues were upregulated as compared with those in the normal cervixes (P<0.05). Twenty-one (46.7%) cervical cancers, 25 (78.1%) CINs and 17 (85%) normal cervixes showed IFN-β positive staining in cytoplasm. There was statistically significant difference in the expression rate of IFN-β between cervical cancer and normal cervix (χ2=8.378, P<0.05) as well as between cervical cancer and CIN (χ2=7.695, P<0.05). HPV16/18 infections could be found in normal cervixs (15%), CINs (68.7%) and cervical cancers (84.4%). There was a correlation between HPV infection and SHP-2 expression in cervical cancer (rs=0.653, P<0.05). SHP-2 may be a useful prognostic and diagnostic indicator for HPV infected cervical cancer. In cervical cancers, SHP-2 mRNA and protein overexpression was associated with IFN-β lower-expression.
基金the NIH Medical Research Scholars Program, a public-private partnership supported jointly by the NIH and contributions to the Foundation for the NIH from the Doris Duke Charitable Foundationthe American Association for Dental Research+2 种基金the Colgate-Palmolive Companyprivate donorssupported partly by the Intramural Research Program at the National Cancer Institute at the NIH
文摘Protein phosphatases play essential roles as negative regulators of kinases and signaling cascades involved in cytoskeletal organization.Protein phosphatase 2A(PP2A)is highly conserved and is the predominant serine/threonine phosphatase in the nervous system,constituting more than 70%of all neuronal phosphatases.PP2A is involved in diverse regulatory functions,including cell cycle progression,apoptosis,and DNA repair.Although PP2A has historically been identified as a tumor suppressor,inhibition of PP2A has paradoxically demonstrated potential as a therapeutic target for various cancers.LB100,a water-soluble,small-molecule competitive inhibitor of PP2A,has shown particular promise as a chemo-and radio-sensitizing agent.Preclinical success has led to a profusion of clinical trials on LB100 adjuvant therapies,including a phase I trial in extensive-stage small-cell lung cancer,a phase I/II trial in myelodysplastic syndrome,a phase II trial in recurrent glioblastoma,and a completed phase I trial assessing the safety of LB100 and docetaxel in various relapsed solid tumors.Herein,we review the development of LB100,the role of PP2A in cancer biology,and recent advances in targeting PP2A inhibition in immunotherapy.
文摘Polycomb group proteins represent a global silencing system involved in development regulation.In specific,they regulate the transition from proliferation to differentiation,contributing to stem-cell maintenance and inhibiting an inappropriate activation of differentiation programs.Enhancer of Zeste Homolog 2(EZH2) is the catalytic subunit of Polycomb repressive complex 2,which induces transcriptional inhibition through the tri-methylation of histone H3,an epigenetic change associated with gene silencing.EZH2 expression is high in precursor cells while its level decreases in differentiated cells.EZH2 is upregulated in various cancers with high levels associated with metastatic cancer and poor prognosis.Indeed,aberrant expression of EZH2 causes the inhibition of several tumor suppressors and differentiation genes,resulting in an uncontrolled proliferation and tumor formation.This editorial explores the role of Polycomb repressive complex 2 in cancer,focusing in particular on EZH2.The canonical function of EZH2 in gene silencing,the non-canonical activities as the methylation of other proteins and the role in gene transcriptional activation,were summarized.Moreover,mutations of EZH2,responsible for an increased methyltransferase activity in cancer,were recapitulated.Finally,various drugs able to inhibit EZH2 with different mechanism were described,specifically underscoring the effects in several cancers,in order to clarify the role of EZH2 and understand if EZH2 blockade could be a new strategy for developing specific therapies or a way to increase sensitivity of cancer cells to standard therapies.
基金Supported by Grants SAF2006-06963, SAF2009-09500 and Consolider CSD-2007-00020 to Sastre J BFU2007-63120 and CSD2006-49 to López-Rodas G
文摘Acute pancreatitis is an inflammation of the pancreas that may lead to systemic inflammatory response syndrome and death due to multiple organ failure. Acinar cells, together with leukocytes, trigger the inflammatory cascade in response to local damage of the pancreas. Amplification of the inflammatory cascade requires up-regulation of proinflammatory cytokines and this process is mediated not only by nuclear factor κB but also by chromatinmodifying complexes and chromatin remodeling. Among the different families of histone acetyltransferases, the p300/CBP family seems to be particularly associated with the inflammatory process. cAMP activates gene expression via the cAMP-responsive element (CRE) and the transcription factor CRE-binding protein (CREB). CREB can be phosphorylated and activated by different kinases, such as protein kinase A and MAPK, and then it recruits the histone acetyltransferase co-activator CREB-binding protein (CBP) and its homologue p300. The recruitment of CBP/p300 and changes in the level of histone acetylation are required for transcription activation. Transcriptional repression is also a dynamic and essential mechanism of down-regulation of genes for resolution of inflammation, which seems to be mediated mainly by protein phosphatases (PP1, PP2A and MKP1) and histone deacetylases(HDACs) .Class HDACs are key transcriptional regulators whose activities are controlled via phosphorylationdependent nucleo/cytoplasmic shuttling. PP2A is responsible for dephosphorylation of class HDACs, triggeringnuclear localization and repression of target genes, whereas phosphorylation triggers cytoplasmic localization leading to activation of target genes. The potential benefit from treatment with phosphodiesterase inhibitors and histone deacetylase inhibitors is discussed.
文摘背景与目的:蛋白磷酸酶2A抑制剂-2(inhibitor 2 of protein phosphatase 2A,I2PP2A)在包括胃癌的多种肿瘤中过度表达,提示其可能在胃癌的发生中发挥重要作用。为进一步探讨I2PP2A的功能及其在胃癌发生中的作用,建立稳定抑制I2PP2A基因表达的人胃癌BGC823细胞株。方法:筛选出I2PP2A基因的RNA干扰(RNA interference,RNAi)有效靶序列,合成靶序列的Oligo DNA并构建p GLV2_sh RNA_I2PP2A慢病毒载体,酶切和测序鉴定正确后,经病毒包装,感染BGC823细胞,经嘌呤霉素筛选稳定表达细胞株,通过实时定量PCR(real-time PCR,RT-PCR)和蛋白[质]印迹法(Western blot)鉴定I2PP2A的表达。结果:重组慢病毒质粒经测序鉴定正确;RT-PCR和Western blot证实干扰I2PP2A后,BGC823细胞株中I2PP2A表达水平明显降低,抑制率约为90%。结论:成功构建了I2PP2A sh RNA慢病毒表达载体,建立了稳定抑制I2PP2A基因表达的人胃癌BGC823细胞株,为进一步研究I2PP2A在胃癌发生中的作用提供了可靠的细胞模型。
