Association of E-cadherin and β-catenin with metastasis in nasopharyngeal carcinoma

Background This study was designed to detect methylation of E-cadherin gene promoter and gene mutation of β-catenin in exon 3 and their expression of protein and mRNA in primary tumor and lymph node metastatic tumor of nasopharyngeal carcinoma (NPC), and investigate the mechanism of invasion and metastasis of neoplastic cells in NPC. Methods Fourty-two fresh biopsy samples were taken from untreated NPC patients at the Affiliated Hospital of Sun Yat-sen Medical College, Sun Yat-sen University, Guangzhou, China during the period of 1999 -2002. Among them 21 were taken from primary tumors and the other 21 from lymph node metastatic tumors. The gene promoter methylation of E-cadherin was detected by methylation-specific PCR (MSP). The mutation in exon 3 of β-catenin was detected by direct sequencing analysis. RT-PCR, Western blot and immunohistochemical staining were used to detect the mRNA and protein expression patterns in both primary and metastatic tumors of NPC. Results Down-regulated expression of E-cadherin in metastatic tumor was compared with that in primary tumor. Reduced expression of E-cadherin was found to be correlated with lymph node metastatic tumor of NPC ( P = 0. 004) ; but there was no obvious correlation between primary and metastatic tumors in the expression of β-catenin (P = 0. 698). The mRNA expression level of Ecadherin in metastatic tumors decreased significantly compared with that in primary tumors. However, little change was observed in the mRNA level of β-catenin in different tumor tissues. Only 4 samples (19. 1%) displayed gene promoter methylation of E-cadherin in primary tumor and 10 samples (47. 6%) showed methylated form of E-cadherin. The gene promoter methylation of E-cadherin was more common in metastatic tumor than in primary tumor of NPC ( P =0. 024). Only 2 (4. 76% ) of the 42 samples showed mutations in exon 3 of β-catenin at 41 (T41A, ACC→GCC) and codon 47(S47T, AGT→ACT). The cytoplasmic and nuclear expression of β-catenin in tumor was not found in any samples of NPC. Conclusions The results suggest that the downregulation of E-cadherin results from the gene promoter aberrant methylation of E-cadherin and that the methylation of E-cadherin plays an important role in invasion and metastasis of tumor cells in NPC. However, β-catenin mutation is an infrequent event in NPC, and β-catenin is not a critical factor influencing the invasion and metastasis of tumor cells in NPC.     

Relationship between the Expression of RASSF1A Protein and Promoter Hypermethylation of RASSF1A Gene in Bladder Tumor

To investigate the relationship between the expression of RASSF1A protein and promoter hypermethylation of RASSF1A gene, RASSF1A protein expression was measured by Western blotting in 10 specimens of normal bladder tissues and 23 specimens of bladder transitional cell carcinoma （BTCC）. The promoter methylation in BTCC and normal bladder tissues was detected by methylation-specific PCR （MSP）. The results showed that the expression level of RASSF1A protein was significantly lower in BTCC tissues than that in normal bladder tissues. However, it was not correlated with its clinical stages and pathological grades. The frequency of promoter methylation of RASSF1A gene was higher in BTCC tissues than that in normal bladder tissues. In 14 patients with the aberrant promoter methylation, 13 showed loss or low expression of RASSF 1A protein. It is concluded that RASSF1A gene promoter methylation may contribute to the low level or loss of RASSF1A protein expression, the inactivation of RASSF1A gene and the genesis of BTCC. But, it may bear no correlation with its clinical stages and pathological grades.     

RASSF2A Promoter Methylation in Hepatitis B Virus-related Hepatocellular Carcinogenesis and Its Correlation with Elevated Serum α-Fetoprotein Level

Loss of the RASSF2A expression induced by methylation-mediated silencing has been reported in several human cancers, but the methylation status of RASSF2A in hepatocellular carcinoma （HCC） is rarely studied so far. In this study, we investigated the RASSF2A expression and its methylation status in a cohort of 45 hepatitis B virus-associated HCC tissues and their adjacent non-carcinoma tissues by using RT-PCR and MS-PCR. Promoter methylation of RASSF2A was found in 31 （68.9%） out of 45 HCC tissues and 12 （40%） out of 30 adjacent normal tissues, respectively （P〈0.05）. The methylation status of PASSF2A was closely associated with the loss of RASSF2A expression and elevated serum α-fetoprotein level, but not significantly with clinical stage, hepatic fibrosis and K-ras mutation. It was concluded that aberrant methylation of the RASSF2A gene with the subsequent loss of RASSF2A expression plays an important role in the pathogenesis of HCC.     

P53 Gene Mutation and Expression of MDM2, P53, P16 Protein and their Relationship in Human Glioma

To investigate the effect of P53 protein accumulation and p53 gene mutation in the pathogenesis of glioma and to study the role of MDM2, P53 and P16 protein in glioma formation and progression and their relationship with each other, LSAB immunohistochemical staining method and non-isotopic PCR-SSCP techniques were used to detect the expression of MDM2, P53 and P16 protein and p53 gene mutation in 48 cases of gliomas. The results showed that the positive expression rate of MDM2, P53 and the negative rate of P16 was 22.9 %, 41.7 % and 60.4 %, respectively. The latter two in high grade （grade Ⅲ , Ⅳ） gliomas had a significantly higher rate than in the low grade （grade Ⅱ ） gliomas. Moreover, the co-expression of MDM2 and P53 protein was confirmed in only 1 of 48 cases. No significant difference was found in the rate of the expression of MDM2 between high grade and low grade gliomas （P〉0.1） . PCR-SSCP results showed that mutation of 5 --8 exons of p53 gene was detected in 17 out of 48 cases （35.42 %） . Mutation was detected in 16 of 20 cases of positive p53 expression, and another one was detected in 28 cases of negative expression cases. The correlation between p53 mutation and p53 immunopositivity was observed in 89.6 % of the cases. P53 gene mutation and the level of MDM2, P53 and PI6 protein were not related to age, gender of the patients, tumor location and size. It is concluded that the mutation of p53 and deletion of p16 might play important roles in the tumorigenesis of gliomas and it was significantly associated with the grade of tumor differentiation. P53 protein accumulation can indirectly reflect p53 mutation. MDM2 amplification and overexpression might be an early event in the growth of human gliomas.     

bcl 10 gene mutation in hepatocellular carcinoma

Objective To detect the mutation frequency of the bcl 10 gene in the early and advanced st ages of hepatocellular carcinoma (HCC).Methods Genome DNA samples were extracted from 46 cases of fresh HCC tumor tissues and t heir non-tumor adjacent tissues. Polymerase chain reaction-single strand conf ormation polymorphism method was used to detect point mutations of t he three exons of the bcl 10 gene. For each individual exon, six random samples from those showing abnormal DNA bands were sequenced to verify those mutations . The relationship between serum alpha-fetoprotein (AFP) level and bcl 10 muta tion, between the tumor size and bcl 10 mutation was also analyzed.Results Among the 46 samples, 26 cases (56.5%) were found to have mutations in exon 1, 5 out of the 6 cases were shown to have 5744 C→G mutation by sequencing; 25 cas es (54.3%) were found to have mutations in exon 2, 4 out of the 6 cases were sh own to have 11 311 T deletion mutation by sequencing. Twenty-one cases (4 5.7%) were found to have mutations in exon 3, all of the 6 cases selected for sequenc ing were shown to have 14 116 C→T mutation. Statistical analysis showed t hat ne ither serum alpha-fetoprotein level nor the size of hepatocellular carcino ma has a significant relationship with bcl 10 mutation.Conclusion The bcl 10 gene has a high mutation frequency in liver cancer.     

Expression of β-catenin in renal cell carcinoma

Objective To investigate the expression of β-catenin and its mRNA in renal cell carcinoma.Methods Twenty-six cases with renal cell carcinoma (RCC) were studied by immunohistoche mistry, Western blot and RT-PCR.Results We found the expression of β-catenis is higher in cancer tissues than in norma l kidney tissues and the level of β-catenin is associated with the tumor stage . Its expression in tumor of pT3 and pT4 is obviously higher than pT1 and pT2 ( P<0.01). That is to say, there was an overexpression of β-catenin protei n in RCC and its level was related to the tumor stage, but the expression of β -catenin mRNA had no difference between tumor tissue and normal tissue.Conclusion β-catenin may be related to the occurrence and progress of RCC.     

Relationship between tumor suppressor gene p53 and tumors of adipose tissue

Objective　To investigate the relationship between p53 gene and tumors of adipose tissue at the level of protein and gene. Methods　Immunohistochemical LSAB, PCR-SSCP and DNA sequencing were used in 82 cases. Results　p53 protein is expressed only in liposarcomas, in which the positive staining rate was 48.08% (25/52). In different subtypes of liposarcomas, the positive staining rate in well differentiated liposarcomas was 30.00% (9/30), which is much lower than that of the poorly differentiated liposarcomas (P<0.005). Abnormality in the single-stranded DNA pattern was determined in 2 samples (pleomophic liposarcomas) by PCR-SSCP analysis. Missense mutations in exon 8 codon 268 of p53 gene (AAC→ATC) were detected by DNA sequencing. Another heterozygotic cosense mutation may exist at exon 6 codon 221 of p53 gene (GAG→GAA). Conclusions　The data suggest that the p53 protein has a relationship with development, differentiation and malignancy of liposarcoma. Detecting the level of p53 protein expression may be valuable in evaluating the level of differentiation and malignancy of liposarcoma. There appear point mutation on exon 8,6 of p53 gene.     

Expression of aspartyl beta-hydroxylase and its clinicopathological significance in hepatocellular carcinoma

The human aspartyl beta-hydroxylase is a highly conserved enzyme that hydroxylates epidermal growth factorlike domains in transformation-associated proteins. The aspartyl beta-hydroxylase gene is upregulated in many human malignancies. The purpose of this study was to investigate the expression of aspartyl beta-hydroxylase in hepatocellular carcinoma. Aspartyl beta-hydroxylase mRNA levels were measured in 161 hepatocellular carcinomas and paired nontumorous liver tissues by conventional and real-time RT-PCR. Immunohistochemical staining of aspartyl beta-hydroxylase was performed using EnVision Plus system. The results showed that aspartyl beta-hydroxylase was overexpressed in 150 of 161 hepatocellular carcinomas （93 %）, including 45 of 48 unifocal small hepatocellular carcinomas （94 % ）. Aspartyl beta-hydroxylase was highly expressed in hepatocellular carcinoma cells in contrast to its low level of expression in non-neoplastic liver cells. The protein expression level of aspartyl heta-hydroxylase in the hepatocellular carcinoma was parallel with the mRNA expression level （r=0. 659 4, P〈 0. 000 1）. A significantly higher tumor aspartyl beta-hydroxylase overexpression level was associated with the presence of intrahepatic metastasis and the progression of histological grades.     

Expression of Survivin, p53 and its relationship with apoptosis, proliferation in hepatocellular carcinoma（HCC）

Objective:To investigate the expression of Survivin p53 and its relationship with apoptosis、proliferation in hepatocellular carcinoma(HCC). Methods:The expression of Survivin, p53 and the proliferation of tumor cells marked by proliferation cell nuclear antigen (PCNA) in 42 cases of HCC were assessed by immunohistochemical method. TUNEL was used to detect apoptosis. Results:Survivin protein was expressed in 30 of 42 cases of HCC(71.4%) and in 4 of 34 cases of adjacent cirrhosis tissues(11.8%). Expression of Survivin protein was negative in 10 cases of normal tissues. Survivin protein positive expression rate in HCC was significantly higher than adjacent cirrhosis tissues and normal tissues(P < 0.001). The increased Survivin protein expression in cancer was significantly associated with histological grade(P = 0.003), p53 protein(P = 0.013), survival time(P < 0.05) and the ratio of proliferative index to apoptotic index(P < 0.01), but was not significantly correlated with age, sex, clinical stage, tumor size, metastasis, AFP, HBs-Ag(P > 0.05).Conclusion:There is a marked increased expression of Survivin in HCC, which may play an important role in breaking the balance of proliferation and apoptosis of HCC cells. The correlation between Survivin and p53 expression in HCC indicates that cooperation between Survivin and p53 plays a certain role in occurrence and /or development of HCC.     

Gene transfer of a β2-adrenergic receptor kinase inhibitor up-regulates the level of β2-adrenergic receptor and cAMP in the asthmatic murine lung

Objective: To investigate the effects of gene transfer of a β-adrenergic receptor(β-AR) kinase inhibitor(β ARKct)on pulmonary β2-adrenergic receptor and cAMP following β2-AR agonist treatment in asthmatic mice, and to analyze the relationship between the routes of gene delivery and the changes of β2AR and cAMP. Methods: BALB/c mice were sensitized and challenged by ovalbumin to establish the asthmatic model treated with βAR agonist ( salbutamol injected intramuscularly). The plasmid with the expression of βARKct was constructed and βARKct gene transfer was performed through intravenous injection or intratracheal instillation in asthmatic mice.The gene expression was measured with Western blot analysis, and the changes of pulmonary β-AR and cAMP evaluated by Radioimmunoassay. Results: The expression of tranfered βARKct gene was detectable in lungs and it was expressed more in the lungs of the mice receiving intratracheally plasmid than those receiving intravenously. The levels of βAR and cAMP were upregulated after using plasmid-βARKct to the asthmatic mice treated with β AR agonist. Conclusion: Our results indicated that there were down-regulation of βAR and cAMP in asthmatic mice treated with βAR agonist. Gene transfer of βARKct could inhibit the extent of the down-regulation of βAR and cAMP. The route of gene delivery could also affect the degree of up-regulation of βAR and cAMP. Gene transfer βARKct may provide a novel approach to the therapeutic strategy for asthma.     

Biological function of a novel gene overexpressed in human hepatocellular carcinoma

Objective To clone the full-length of a differentially expressed cDNA fragment, LC27, and study its biological function tentatively. Methods Northern blot was used to analyze the expression pattern of LC27 in hepatocellular carcinoma, matched nontumor liver tissues, fetal liver and normal adult liver tissues, as well as BEL-7402 hepatocellular carcinoma cell line ESTs splicing and 5’ rapid amplification of cDNA ends (5’ RACE) were used to clone the full-length of LC27 cDNA.An antisense oligodeoxynucleotide approach was used to investigate the biological role of the gene in the proliferation of BEL-7402 cells. Results A 2186 bp novel cDNA with an open reading frame encoding a 283 amino acid protein was cloned.Analysis of the deduced amino acid sequence indicated that it is 38% (88/229) identical to human Golgi 4-transmembrane spanning transporter MTP.The gene and the encoded protein was termed hepatocellular carcinoma overexpressed transmembrane protein (hotp) and HOTP, respectively.Hotp mRNA was almost undetectable in normal adult liver and fetal liver tissues.However, it was significantly up-regulated in hepatocellular carcinoma and some matched nontumor liver tissues, as well as BEL-7402 cells.The proliferation of BEL-7402 cells was suppressed by an antisense oligodeoxynucleotide against hotp mRNA at a concentration of 50 μg/ml. Conclusion HOTP may be an integral membrane transporter protein.The overexpression of the gene in hepatocellular carcinoma may play an important role in hepatocarcinogenesis and disease progression.     

The Relationship of Insulin—receptor Gene Polymorphism to Ischemic Stroke？

Objective To investigate the role of mutation of insulin-receptor(INSR) gene in the development of ischemic stroke.Methods The base-variations at exon 17 and 20 of INSR gene,by means of PCR-SSCP were determined in 68 cases of atherothrombotic cerebral infarction (ACI),81 cases of lacunar infarction(LI) and 62 healthy controls(HC).Results There were 2 alleles of T and C at exon 17 of INSR gene.The prevalence of mutant of t allele in ACI patients was more common than that in the controls.the blood pressure and the parameters of lipid metabolism in the patients with mutant were higher than those in the controls with wild-type gene.However,the correlative analysis showed that the polymorphism of INSR gene was not related statistically to the blood pressure.No base-variation at exon 20 was found in the study.Conclusion The mutation at exon 17 of INSR gene,by promoting the development of atherosclerosis,may participate in the occurrence of ischemic stroke.     

Expression of Beclin1 in non small cell lung cancer and its clinical significance

Objective:To investigate the expression of autophagy related gene;Beclin1 in human non-small cell lung cancer(NSCLC)tissues.Methods:Protein expression of Beclin1 was determined by immunofluorescence staining and Western Blot,mRNA expression was analyzed by RT-PCR.Results:Immunofluorescence staining revealed that the level of Beclin1 expression in lung cancer was significantly lower than that in adjacent noncancerous tissues and normal tissues(expression rate 8.3%,P=0.000).The Beclin1 mRNA expression in lung cancer,adjacent noncancerous tissues and normal tissues was 1.372(±0.475)1.721(±0.521)and 1.553(±0.554)when F = 15.0,P < 0.01.Beclin1 protein expression in lung cancer,adjacent noncancerous tissues and normal tissues was 3.453(±0.852)5.423(±1.351)and 6.878(±0.997)F = 11.2,P < 0.01.Conclusion:The protein and mRNA expression of Beclin1 in lung cancer was much lower than those in and around cancer tissues and normal tissues,those differences having statistical significance.However in adjacent noncancerous tissues and normal tissues,the expression showed no difference.     

Expression of the MAGE-1 gene in human hepatocellular carcinomas

Objective To further investigate the expression of MAGE-1 gene in hepatocellular carcinom a (HCC). Methods The tumors and adjacent liver tissue from 45 HCC patients and liver tissue from 28 non-HCC patients (16 with liver cirrhosis and 12 with normal liver) were cha racterized by RT-PCR. A 421 bp PCR product from a cDNA fragment spanning exon s 1, 2 and 3 was sequenced. The HLA type was assayed by standard ELISA in 43 HC C patients.Results Thirty-two of 45 tumor tissues from HCC patients expressed MAGE-1 mRNA (71.1% ). In contrast, MAGE-1 mRNA was not detected in adjacent tissues. Three were found to have point mutations at 3 identical sites resulting in the substitutio n of two amino acid residues. The most frequent HLA types in 43 HCC patients we re: HLA-A2, 53.5%; A11, 25.6%; A24, 20.9%; A33, 20.9%; HLA-B13, 28.3% and B35, 23.2%. Expression of HLA-A33 (20.9%) was higher in HCC patients than t hat predicted in the normal Chinese population (8.8%). There was no discer nable correlation between MAGE-1 expression and α-FP level, tumor size and he patitis B or C virus infection. The identification of peptides which are restri cted by haploptypes other than A1 should increase the opportunity for peptide ba sed immunotherapy.Conclusions This study shows that MAGE-1 mRNA is highly expressed in HCC tumor tissue in Ch inese patients. Previously unreported point mutations in the MAGE-1 gene are d escribed and may also provide additional opportunities for immunotherapy.     

Silencing MTA1 by RNAi Reverses Adhesion,Migration and Invasiveness of Cervical Cancer Cells （SiHa） via Altered Expression of p53, and E-cadherin/β-catenin Complex

It has been reported that metastasis-associated gene 1 (Mta1) is overexpressed in many malignant tumors with high metastatic potential. In addition, some studies indicated that MTA1 participated in invasion, metastasis, and survival of cancer cells by regulating cell migration, adhesion and proliferation. But the role of MTA1 is unclear in vitro in the development of cervical cancer cells. This study investigated whether and how MTA1 mediated cell proliferation, migration, invasion and adhesion in cervical cancer. MTA1 expression level was detected by Western blot in two cervical cancer cell lines of different invasion potentials. The effects of MTA1 expression on SiHa cell apoptosis, cycle, proliferation, migration, invasion and adhesion were tested by flow cytometry, MTT, wound-healing assay, Transwell assay and adhesion assay, respectively. The expression levels of p53, E-cadherin, and β-catenin activity were evaluated in untreated and treated cells. The results showed that MTA1 protein expression was significantly higher in SiHa than in HeLa, which was correlated well with the potential of migration and invasion in both cell lines. Furthermore, the cell invasion, migration and adhesion capabilities were decreased after inhibition of MTA1 expression mediated by Mta1-siRNA transfection in SiHa. However, no significant differences were found in cell apoptosis, cycle, and proliferation. In addition, E-cadherin and p53 protein levels were significantly up-regulated, while β-catenin was significantly down-regulated in SiHa transfected with the siRNA. These results demonstrated that MTA1 played an important role in the migration and invasion of cervical cancer cells. It was speculated that the decreased migration and invasion capability by inhibiting the MTA1 expression in the SiHa cell line may be mediated through the altered expression of p53, and E-cadherin/β-catenin complex. MTA1 could serve as a potential therapeutic target in cervical cancer.     

Study of Mutation in Tyrosine Protein Kinase of Insulin Receptor Gene in Patients with Polycystic Ovarian Syndrome

Objective To explore the molecular mechanism of insulin resistance in the patients with polycystic ovarian syndrome (PCOS ) Methods Polymerase chain reaction, silver staining-single strand conformation polymorphism(PCR-SSCP ) and DNA direct sequencing were used to detect the mutation of insulin receptor (INSR) gene in exon 17～21 with the abdominal wall adipose tissue from 31 patients with PCOS (PCOS Group) and 30 patients with pure hysteromyoma in reproductive lift (Control Group).Results Twenty-two variant SSCP patterns in exon 17 of INSR gene were detected.Direct sequence analysis of exon 17showed that homozygous nonsense mutation was two alleles single nucleotide polymorphism (SNP) at the codon 1058 ( CAC→CAT). Exons 18～21 were not detected with any significantly mutation. The INSR gene His^1058C→T substitution collecting rate and insulin resistance were significantly higher in the PCOS group than in the control group (P=0. 0293, P＜0. 05, P＜0. 01).Conclusion It is suggested that the SNP in codon 1058 of the INSR gene might be related with the insulin resistance in PCOS patients, which has hereditary tendency.And the missense mutation,nonsense mutation and frameshi ft mutation at exons 18～21 in tyrosine protein kinase region of INSR gene for PCOS patients were not frequently observed.