癌蛋白质组的研究进展

癌症的发生是由于某些蛋白质的表达或变化引起的一系列的细胞无控制增殖的过程。癌蛋白质组学在研究癌症的发生发展、诊断治疗、药物筛选中起着越来越重要的作用。本文介绍了癌蛋白质组学研究进展。主要内容包括:常用的研究技术,癌发生发展的蛋白质网络作用机制,作为癌早期诊断的蛋白质分子标记的鉴定,癌症治疗新靶点的发现和治疗策略的制定等。

Construction and Expression of Tp0453 Recombinant Protein of Treponema pallidum and Development of Indirect ELISA for Diagnosinq Syphilis

Objectives： To clone and express Tp0453 outer membrane protein of Treponema pallidum, and to evaluate its significance in the serodiagnosis of syphilis. Methods： The immuno-dominant epitope of Tp0453 gene was amplified from the complete genome of T.pallidum by polymerase chain reactions （PCR）, subcloned into the expression vector Pqe32 to generate recombinant plasmid Pqe32/Tp0453, and was then expressed in E. coli M15. The fusion protein was purified with Ni-NTA affinity purification. Indirect ELISA was developed to detect human serum IgG antibody to T. pallidum. Results： The recombinant Tp0453 protein was successfully expressed and purified. The recombinant protein had a molecular weight of approximately 32KDa.Indirect ELISA to the recombinant protein was developed.Sixty control sera were tested by ELISA and yielded a sensitivity of 100% （30/30） and a specificity of 100% （30/30）. While testing for T. pallidum in human sera, the sensitivity and specificity of ELISA were 96.8% and 100%, respectively, when compared with TPPA test results. The concordance of results between the ELISA test and the TPPA test was 98.2%. Conclusion： The recombinant Tp0453 outer membrane protein elicited a strong immunoreaction to anti-T.pallidum IgG antibody and has great potential use in ELISA for the serodiagnosis of syphilis.

Cloning and Prokaryotic Expression of P23 Major Surface Protein Gene from Theileria sergenti

[Objective] The aim was to study cloning and prokaryotic expression of P23 major surface protein gene of Theileria sergenti. [Method] A pair of specific primers was designed according to the sequence of P23 major surface protein of T. sergenti (D84447).The P23 gene was amplified by PCR from genomic DNA of T. sergenti and cloned into pMD18-T vector to construct recombinant clonal vector pMD18-P23. Positive clones were identified by PCR screening and restriction digestion. A recombinant expression plasmid pGEX-4T-P23 was constructed by subcloning the cloned P23 gene into the linearized pGEX-4T-1 vector and transformed into E. coli BL21. After introduction by IPTG,the expressed fusion protein was identified by SDS-PAGE and Western-blotting. [Result] The cloned gene has a total length of 507 bp. Sequencing result showed that the nucleotide sequence of the cloned P23 gene shared 99.4% identity with that of P23 published in GenBank (D84447). The expressed fusion protein was 46 ku in molecular mass. Induction opportunity of zhours after culture inoculation was the best,the induction time of 6 h was the best,and induction temperature of 34 ℃ was the best as well,IPTG of 1 mmol/L had little effect on the expression. Western-blotting indicated that recombinant protein was recognized by specific antibody. [Conclusion] This study would lay a foundation for further research on the prevention and diagnose of T. sergenti.

Significance of KiSS-1 and S100A4 in the process of metastasis of gastric carcinoma

Objective： To detect the expression of KISS-1 and S100A4 in the primary tumor tissues and lymphatic and visceral metastases and investigate its role in tumorigenesis and metastasis of gastric cancer. Methods： The protein expression of KISS-1 and S100A4 in lymphatic and visceral metastases from advanced gastric cancer specimens was mainly examined by immunohistochemical staining and tissues microarray. Results： Immunohistochemical staining revealed reduced expression of KISS-1 and up-regulated expression of S100A4 in lymph node and visceral metastases. Rates of KISS-1 expression in normal tissues, primary tumor tissues, lymph node and visceral metastases were 95.8%, 74.6%, 60.9% and 57.5%. $100A4 expression in associated cases was 43.6%, 71.8%, 70.3% and 90.0%, respectively. Significant differences in KISS-1 expression was significantly higher in normal tissues than that in primary tumor tissues （P〈0.001）. While significant differences of S100A4 expression could be seen between normal and cancer tissues （P〈0.001） and between visceral and primary tumors （P〈0.05）. Conclusion： Tumor metastasis results from gradual accumulation of abnormal genetic alterations. Down-regulation of KISS-1 and up-regulation of S100A4 play a critical role in metastasis of gastric carcinoma.

Gene cloning and prokaryotic expression of recombinant flagellin A from Vibrio parahaemolyticus

The Gram-negative Vibrio parahaemolyticus is a common pathogen in humans and marine animals. Bacteria flagellins play an important role during infection and induction of the host immune response. Thus, flagellin proteins are an ideal target for vaccines. We amplified the complete flagellin subunit gene （tTaA） from V. parahaemolyticus ATCC 17802. We then cloned and expressed the gene into Escherichia coli BL21 （DE3） cells. The gene coded for a protein that was 62.78 kDa. We purified and characterized the protein using Ni-NTA affinity chromatography and Anti-His antibody Western blotting, respectively. Our results provide a basis for further studies into the utility of the FlaA protein as a vaccine candidate against infection by Vibrio parahaemolyticus. In addition, the purified FlaA protein can he used for further functional and structural studies.

Expression of Bmi-1,P16,and CD44v6 in Uterine Cervical Carcinoma and Its Clinical Significance

Objective Bmi-1, a putative proto-oncogene, is a core member of the polycomb gene family, which is expressed in many human tumors. The p16 protein negatively regulated cell proliferation, whereas CD44v6 is associated with proliferation as an important protein. Additionally, CD44v6 is an important nuclear antigen closely correlated to tumor metastasis. Tlle present study aims to investigate the expression and significance of Bmi-1, p16, and CD44v6 in uterine cervical carcinoma （UCC）. Methods A total of 62 UCC, 30 cervical neoplasic, and 20 normal cervical mucosal tissues were used ill the current study. The expression of Bmi-1, p16, and CD44v6 in these tissues was determined using immunohistochemical assay. The relationships among the expression of these indices, the clinicopathologic features of UCC, and the survival rate of UCC patients were also discussed. The correlation between Bmi-1 protein expression and p16 or CD44v6 protein in UCC was analyzed. Results The expression of Bmi-l, p16, and CD44v6 was significantly high in cervical carcinoma compared with that in tlle cervical neoplasia and normal colorectal mucosa （P〈0.05）. The over-expression of Bmi-1 protein in UCC was apparently related to the distant metastasis （P〈0.01） and the tumor, nodes and metastasis-classification, i.e. the TNM staging, World Health Organization （P〈0.05）. Nevertheless, the positive expression of p16 protein in UCC was not significantly associated with the clinicopathologic features （P〉0.05）. The Kaplan-Meier survival analysis showed that the over-expression of Bmi-1 significantly decreased the survival rate of UCC patients （P〈0.05）. A strong correlation indicated that there was statistical significance between the expression of Bmi-1 and CD44V6 proteins in UCC （r=0.419, P=0.001）. Conclusions The over-expression of Bmi-1 and CD44v6 protein closely correlate to the tumorigenesis, metastasis, and prognosis of UCC. Bmi-I and CD44v6 may be used to predict the prognosis of cervical carcinoma. Bmi-1 may indirectly regulate the expression of CD44v6 in UCC patients. The positive expression of p16 protein is possibly associated with the tumorigenesis, but not with the metastasis or prognosis of UCC.

Expression of MUC1 and its significance in hepatocellular and cholangiocarcinoma tissue

AIM： To investigate the relation between MUC1 expression, distribution, and prognosis in hepatocellular and cholangiocarcinoma （HCC and CC） and cirrhotic liver tissues, and their significance in HCC and CC diagnosis. METHODS： Expression and distribution of MUC1 were examined by immunohistochemical assay with anti-MUC1 mAb in 59 samples of HCC and 37 samples of CC, 20 samples of cirrhotic liver tissues, and 10 samples of normal liver tissues, seeking possible associations between MUC1 positive expression, distribution in HCC and CC （primary liver cancer, PLC） cases and the studied clinical data. RESULTS： Immunohistochemical analysis of MUC1 expression showed that in the 96 PLC samples, 68 （70.8%） were strong positive, and 6 （6.2%） were weak positive. Only 4 in the 20 cirrhotic liver tissues were found to be weak positive, while no expression of MUC1 was detected in normal liver tissues. Apparently, the high expression rate of MUC1 in PLC tissues was statistically significant in comparison to that in cirrhotic and normal liver tissues. The expressed MUC1 protein, stained in dark brownish or brownish-yellow particles, chiefly localized on the cancer cell membranes or in cytoplasm. In the 68 strong positive samples, 40 were detected on cell membrane and the other 28 were in cytoplasm. In addition, follow-up studies of those PLC cases demonstrated that MUC1 expression on cell membrane or in cytoplasm was closely associated with PLC prognosis. The expression of HUC1 in PLC had little statistical significance in respect of the pathological types and sizes of the tumors, but a strong relationship regarding histological differentiation, metastasis of lymph nodes, portal canal emboli, and post-operational recurrence of the carcinomas. After 3 years of tumor excision, the metastasis rate in MUC1 positive expression group （67.6%） was much higher than that in MUC1 weak expression group （33.3%） and negative expression group （31.8%）, and thus the survival rate in MUC1-positive expression group was significantly different from that in weak and negative expression groups. CONCLUSION： Expression and localization of MUC1 proteins in primary liver carcinomas （PLCs） may act as prognostic markers, and MUC1 molecules might be helpful in differential diagnosis.

Construction of prokaryotic expression system of TGF-β1 epitope gene and identification of recombinant fusion protein immunity

AIM： To insert the constructed TGF-β1 epitope gene into the el loop of C-terminus of truncated hepatitis B core antigen to increase TGF-β1 antigenicity in its prokaryotic expression system and to identify immunity of the expressed recombinant protein in order to exploit the possibility for obtaining anti- TGF-β1 vaccine. METHODS： The TGF-β1 encoding epitope gene （the mature TGF-β1 from 78-109 amino acid residues, TGF-β1^32） was amplified by polymerase chain reaction from the recombinant pGEM-7z/ TGF-β1 ^32 vector. The HBcAg gene fragments （encoding HBcAg from 1-71 and 89-144 amino acid residues） were amplified from PYTAI- HBcAg vector. The recombinant vector pGEMEX-1 was used to insert HBcAg1-71, TGF-β1^32 and HBcAg89-144 into restrictive endonuclease enzyme and ligated with T4 Ugase. The fusion gene fragments HBc.Ag1-71-TGF-β1^32 HBcAg89-144 were recloned to pET28a（＋） and the DNA sequence was confirmed by the dideoxy chain termination method. The recombinant vector pET28a （＋）/ CTC was transformed and expressed in E. coli BL21 （DE3） under induction of IPTG. After purification with Ni^＋2 NTA agarose resins, the antigenicity of purified protein was detected by ELISA and Western blot and visualized under electron microscope. RESULTS： Enzyme digestion analysis and sequencing showed that TGF-β1 epitope gene was inserted into the el loop of C-terminus of truncated hepatitis B core antigen. SDS-PAGE analysis showed that relative molecular mass （Mr） of the expressed product by pET28a （＋）/CTC was Mr 24 600.The output of the target recombinant protein was approximately 34.8% of the total bacterial protein,mainly presented in the form of inclusion body. Western blotting and ELISA demonstrated that the fusion protein could combine with anti-TGF-β1 polyclonal IgG but not with anti-HBcAg. The purity of protein was about 90 % and the protein was in the form of self-assembling particles visualized under electron microscope. This fusion protein had good anti-TGF-β1 antigenicity and could be used as anti-TGF-β1 vaccine. CONCLUSION： A recombinant prokaryotic expression system with high expression efficiency of the target TGF-β1 epitope gene was successfully established. The fusion protein is in the form of self-assembling particles and HBcAg can increase the antigenicity of TGF-β1. The expressed TGF-β1 epitope gene shows good immunogenicity and antigenicity.

Expression and purification of recombinant human hemangiopoietin in Escherichia coli

Objective:To express the soluble recombinant hemangiopoietin protein in E.coli BL21(DE3).Methods:Using human fetal live cDNA as a template,a partial cDNA fragment of HAPO coding N-terminal region was subcloned into plasmids pTrc99,pQE60 and pET32c to construct different recombinant prokaryotic expression systems.After selecting,the soluble rhHAPO fusion protein was expressed stably in E.coli BL21(DE3) by vector pET32c-HAPO and further isolated by nickelnitrilotriacetic acid(NTA) affinity chromatography.After cleavage with enterokinase,the rhHAPO protein was applied to Fast Flow SP sepharose column.Results:The rhHAPO protein had a purity of more than 95% and a good bioactivity based on the cell adhesion assay in ECV304 cells.Conclusion:We have established a protein engineering system to produce rhHAPO which may provide the possibility for clinical application.

Chemometrics of differentially expressed proteins from colorectal cancer patients

AIM:To evaluate the usefulness of differentially expressed proteins from colorectal cancer (CRC) tissues for differentiating cancer and normal tissues.METHODS:A Proteomic approach was used to identify the differentially expressed proteins between CRC and normal tissues.The proteins were extracted using Tris buffer and thiourea lysis buffer (TLB) for extraction of aqueous soluble and membrane-associated proteins,respectively.Chemometrics,namely principal component analysis (PCA) and linear discriminant analysis (LDA),were used to assess the usefulness of these proteins for identifying the cancerous state of tissues.RESULTS:Differentially expressed proteins identified were 37 aqueous soluble proteins in Tris extracts and 24 membrane-associated proteins in TLB extracts.Based on the protein spots intensity on 2D-gel images,PCA by applying an eigenvalue > 1 was successfully used to reduce the number of principal components (PCs) into 12 and seven PCs for Tris and TLB extracts,respectively,and subsequently six PCs,respectively from both the extracts were used for LDA.The LDA classification for Tris extract showed 82.7% of original samples were correctly classified,whereas 82.7% were correctly classified for the cross-validated samples.The LDA for TLB extract showed that 78.8% of original samples and 71.2% of the cross-validated samples were correctly classified.CONCLUSION:The classification of CRC tissues by PCA and LDA provided a promising distinction between normal and cancer types.These methods can possibly be used for identification of potential biomarkers among the differentially expressed proteins identified.

Study on DNA Immunization by Recombinants Encoding Japanese Encephalitis Virus prME and E Proteins

To study the expression characteristic of Japanese encephalitis virus (JEV) prME and E proteins and the efficacy of DNA immunization by different recombinant plasmids containing JEV prME (2001 bp) and E (1500 bp) genes, two recombinants (pJME and pJE) containing JEV prME and E genes fused with FLAG were constructed and then transfected into HepG2 and COS-1 cells by liposome fusion. The expression feature of FLAG-prME (about 72 kDa) and FLAG-E (about 54 kDa) proteins in transfected cells were analyzed by Western blot and two antibody systems (anti-FLAG and anti-E). BALB/c mice were immunized with 100 μg of two kinds of recombinants by intramuscular injection, and JEV JaGAr-01 strains (10 5 PFU/100 μl)were given to BALB/c mice by intraperioneal injection 3 wk after twice DNA immunization by a lethal virus challenge. BALB/c mice were observed for 21 days after challenge. 80% plaque reduction neutralization test was performed to titrate neutralization antibody before and after viral challenge. It was found that the expression of proteins associated with pJME and pJE was determined in transfected cells with anti-FLAG and a new protein of 11 kDa was detected in HepG2 and COS-1 cells transfected with pJME. Only E (53 kDa) protein was identified as transfected with pJME using anti-E. Higher level of neutralization antibodies and the efficacy of protective immunity were induced with pJME immunization, and were similar to those induced by inactivated Japanese encephalitis vaccine, but were better than those induced with pJE. It concludes that the expression level from prM to E proteins of JEV is different in vitro, and the in vitro expression efficiency of pJME was better than that of pJE. FLAG-prME protein expressed by pJME could be cleaved by peptidase from host. The efficacy of DNA immunization is correlated to the expression characterization of related proteins expressed in vitro.

Expression, purification and activity assay of recombinant human thymidylate synthase

Thymidylate synthase （TS, E.C.2.1.1.45） catalyzes a critical reaction in the only pathway of de novo synthesis of thymidylate （dTMP） in human cells, and is an important target of chemotherapy. To evaluate the inhibitory activities of novel compounds to TS, a convenient method of activity assay using 6x His-tagged recombinant human TS （rhTS） was established and 49 novel synthetic folate analogues were screened to discover potential TS inhibitors. During the process, 4 novel compounds were found to effectively inhibit TS, while the IC 50 of a positive control raltitrexed was 3.4 μM in this assay.

Recombinant human heparin-binding neurite-promoting factor expressed with yeast stimulates neurites outgrowth

OBJECTIVES: Heparin-binding neurite-promoting factor (HBNF) is a heparin-binding protein primarily found in the brain, which can stimulate neurite outgrowth in vitro. We expressed recombinant human heparin-binding neurite-promoting factor (hrHBNF) using a yeast system, and observed its activity in stimulating neurite outgrowth in vitro. METHODS: cDNA encoding mature human HBNF was amplified from total RNA isolated from an 18-week aborted human fetal brain by RT-PCR method. After amplification, the HBNF cDNA gene was cloned into pPIC9K, a shuttle expression vector for yeast system. The positive clone of expression vector bearing HBNF cDNA gene was obtained by screening. Verified recombinant vector was then used to transform Pichia strain GS115 by electroporation. His(+) transformants were selected on minimal dextrose medium (MD) plates which were histidine free. His(+) yeast recombinants with multi-copy inserts were screened in vivo by their resistance to G418. PCR analysis was used to confirm the integration of the HBNF cDNA gene into the Pichia genome. Secreted expression of hrHBNF protein in culture medium was obtained when the positive clone containing the HBNF cDNA gene was induced by methanol. The hrHBNF product purified by gel chromatography was added to cultured rat pheochromocytoma (PC12) cells to observe its ability to stimulate neurite outgrowth. RESULTS: In the recombinant expression vector, the insert was sequenced to show exactly the sequence encoding human HBNF according to Genbank data. The HBNF cDNA gene was cloned downstream to the alpha-factor, and its open reading frame was in frame with the alpha-factor signal sequence in pPIC9K. SDS-PAGE showed that the molecular weight of the induced expression product was about 18 kDa, consistent with that of human HBNF reported in the literature. The protein product did promote neurite outgrowth in cultured rat pheochromocytoma (PC12) cells. CONCLUSION: Recombinant human heparin-binding neurite-promoting factor can be expressed with a yeast system, and its product possesses the biological activity to promote neurite outgrowth.

Science Letters:Proteomic analysis of differentially expressed proteins in mice with concanavalin A-induced hepatitis

Objective： To find new protein biomarkers for the detection and evaluation of liver injury and to analyze the relationship between such proteins and disease progression in concanavalin A （Con A）-induced hepatitis. Methods： Twenty-five mice were randomly divided into five groups： an untreated group, a control group injected with phosphate buffered saline （PBS）, and groups with Con A-induced hepatitis evaluated at 1, 3 and 6 h. Two-dimensional gel electrophoresis （2-DE） and mass spectrometry （MS） were used to identify differences in protein expression among groups. Quantitative real-time polymerase chain reaction （qRT-PCR） was performed to verify the results. Results： In mice with Con A-induced hepatitis, expression levels of four proteins were increased： RIKEN, fructose bisphosphatase 1 （fbp1）, ketohexokinase （khk）, and Chain A of class pi glutathione S-transferase. Changes in fbpl and khk were confirmed by qRT-PCR. Conclusion： Levels of two proteins, fbp1 and khk, are clearly up-regulated in mice with Con A-induced hepatitis.

Label-free quantification of differentially expressed proteins in mouse liver cancer cells with high and low metastasis rates by a SWATH acquisition method

Label-free quantification is a valuable tool for the analysis of differentially expressed proteins identified by mass spectrometry methods.Herein,we used a new strategy:data-dependent acquisition mode identification combined with label-free quantification by SWATH acquisition mode,to study the differentially expressed proteins in mouse liver cancer metastasis cells.A total of 1528 protein groups were identified,among which 1159 protein groups were quantified and 249 protein groups were observed as differentially expressed proteins(86 proteins up-regulated and 163 down-regulated).This method provides a commendable solution for the identification and quantification of differentially expressed proteins in biological samples.

Effects of Zuogui Pill (左归丸) on Wnt Singal Transduction in Rats with Glucocorticoid-induced Osteoporosis

Objective: To reveal the mechanism of Zuogui Pill (左归丸) in treatment of glucocorticoid-induced osteoporosis from the angle of the Wnt signal transduction pathway and to provide further experimental evidence for expounding the scientific connotation of "the kidney dominating the bones" in TCM. Methods: Forty-two male Wistar rats were selected and randomly divided into three groups, control group (n=12), model group (n=15) and Zuogui Pill group (n=15). Form the beginning, The rats were injected dexamethasone for eight weeks to make the model of osteoporosis, and the Zuogui Pill were administered intragastrically to the rats of Zuogui Pill group for eight weeks. The relative morphological parameters were measured in the undecalcified tibial slices. And the protein expression levels of Wnt1, LRP-5 and β-catenin in rat tibial osteoblasts (OB) and bone marrow stromal cells (BMC) were detected by immunohistochemistry. Results: Compared with the control group, TBV% and TFS% decreased significantly, while TRS% increased significantly, and the protein expression of Wnt1, LRP-5 and β-catenin in OB and BMC decreased significantly in the model group. And compared with the model group, TBV% and TFS% increased significantly, and expression levels of Wnt1, LRP-5 and β-catenin proteins increased significantly in the Zuogui pill group. Conclusion: Zuogui Pill can prevent and treat glucocorticoid-induced osteoporosis in rats by up-regulating the expression of the key signal molecules Wnt1, LRP-5 and β-catenin in Wnt signal transduction pathway.

The influence of mitochondria in epigenetics revealed through naturally occurring fish cybrids

Epigenetic processes are important mechanisms for phenotypic changes that occur in response to the environment. As such, it is expected that the alteration of cytoplasmic composition （the immediate environment of nuclei） results in the modifica- tion of the methylome and the expression of the nuclear genome. Cytoplasmic hybrids （or cybrids） are an ideal model to study the influence of mitochondria on gene expression. In this study, we take advantage of the natural of two biotypes that have a similar nuclear genome type Chrosomus eos, but harbor mitochondria from different species （C. eos in wild type or C. neogaeus in cybrids） to assess the effects of mitochondria on DNA methylation profiles and protein expression of the nuclear ge- nome. Comparison between these biotypes is particularly relevant given their recent divergence and their low level of genetic dif- ferentiation. Variations of DNA methylation assessed on tissues from different embryonic origins revealed the distinct profiles of cybrid and wild type populations. Differences are more pronounced between wild type and cybrids than between populations of a given biotype. The proteome is also more different between biotypes than within a given biotype. These results indicate a strong influence of mitochondria on the nuclear genome, which remains detectable in different genetic and environmental contexts. These changes in the methylome and proteome of cybrids are expected to reflect the adjustments imposed by the coexistence of nuclear and mitochondrial genomes from different species [Current Zoology 58 （1）： 138-145, 2012].