Mapping of metastasis suppressor genes for prostate cancer by microcell-mediated chromosome transfer

Aim:To identify the metastasis suppressor genes for prostate cancer.Methods:A copy of human chromosomeswas introduced into the highly metastatic Dunning R-3327 rat prostate cancer cells by the use of microcell-mediatedchromosome transfer.Relationships between the size of human chromosomes introduced into microcell hybrid clonesand the number of lung metastases produced by the clones were analyzed to determine which part of human chromo-somes contained the metastasis suppressor gene(s)for prostate cancer.To determine portions of human chromosomesintroduced,G-banding chromosomal analysis,fluorescence in sim hybridization analysis,and polymerase chain reac-tion analysis were performed.Results:Each of microcell hybrid clones containing human chromosomes 7,8,10,11,12,or 17 showed decreased ability to metastasize to the lung without any loss of tumorigenicity.This demonstratesthat these human chromosomes contain metastasis suppressor genes for prostate cancer.Spontaneous deletion of portionsof human chromosomes was observed in the human chromosome 7,10,11,12,and 17 studies.In the human chromo-some 8 study,irradiated microcell-mediated chromosome transfer was performed to enrich chromosomal arm deletionsof human chromosome 8.Molecular and cytogenetic analyses of microcell hybrid clones demonstrated that metastasissuppressor genes on human chromosomes were located on 7q21-22,7q31.2-32,8p21-12,10q11-22,11p13-11.2,12p11-q13,12q24-ter,and 17pter-q23.KAII and MKK4/SEKI were identified as metastasis suppressor genes from11p11.2 and 17p12,respectively.Conclusion:This assay system is useful to identify metastasis suppressor gene(s)for prostate cancer.

Expression and significance of tumor suppressor gene p16 in human ovarian neoplasm

To observe the relationship between tumor suppressor gene p16 expression and ovarian cancer occurrence and development. Metbods: Using ABC immunohistochemistry method, we investigated the expression of p16 in 72 cases of ovarian neoplasm. Results: The positive rates of p16 in malignant, benign, borderline tumors and normal ovarian tissue were 7. 89%, 60.00%, 66. 67% and 83. 33%, respectively (P<0.01). In the cases whose tumors were more malignant and poorly differentiated, and who relapsed and died, the positive stainings were not discovered. Conclusiou: p16 is well related with the occurrence and development of malignant ovarian tumor.

Alteration of tumor suppressor gene p16 and Rb in gastric cancinogesis

IM To study the alterations of tumor suppressor gene p16 and Rb in the carcinogenesis of the stomach. METHODS Different mucosal biopsies were endoscopically obtained, all samples were immediately fixed with 10% buffered formalin, embedded with paraffin and sectioned serielly. Alterations of p16 and Rb protein in 12 cases of superficial gastritis, 15 atrophic gastritis, 20 atypical hyperplasia and 40 cancerous tissues were detected by the immunohistochemical method (ABC). RESULTS Different degrees of nuclear immunostaining of p16 and Rb occurred on gastric epithelium in different stages of lesions. With the lesions progressing, the positive immunostaining rate of p16 protein had a decreasing tendency (833%→733%→300%→275%), and on the other hand, that of Rb protein had an increasing tendency (250%→467%→600%→675%). A negative correlationship was found between these two parameters in the gastric cancer. Of 40 cases of gastric cancer, a negative relationship was observed in 20 cases. In comparison with both positive (9 cases) and both negative tissues (11 cases), there was a significant difference (500%,225%,275%) (P<005).CONCLUSION Abnormal expression of p16 and Rb plays an important role in gastric carcinogenesis.

Overexpression and mutations of tumor suppressor gene p53 in hepatocellular carcinoma

AIMS To examine the prevalance of p53 mutations in hepatocellular carcinoma (HCC) from Chongqing area and the relationship between the p53 mutations and clinicopathological features of HCC,as well as the risk factors. METHODS The overexpression and point mutations of tumor suppressor gene p53 in 38 cases of HCC were detected by a sensitive antigen retrieval fluid (ARF) immunohistochemical method and polymerase chain re- action(PCR)-restriction fragment length polymorphism (RFLP),and single strand conformation polymorphism (SSCP)-silver staining analysis. RESULTS The results showed that 16 of 38 HCCs had positive p53 protein (42.1%),7 HCCs had p53 mutation at 249 (18.4 % ) and 2 HCCS had point muta- tion within exon 7 other than 249. Among 9 cases of HCC with mutations,8 cases demonstrated positive p53 protein,its coincidental rate was 88.9%. The overexpression and mutations of p53 were significantly related to the differentiation and metastasis of HCCs. The frequency of p53 mutations was consistent with high prevalence of HBV and a moderate aflatoxin B1 (AFB1) exposure in our area. CONCLUSIONS The results suggest that AFB1 acts synergistically with HBV in the generation of p53 mutations. Furthermore,dietary exposure to AFB1 may mainly contribute to the tumor specific mutation at codon 249,while HBV may account for other scattered mutations in HCC.

Characterization of six tumorsuppressor genes and microsatellite instability in hepatocellular carcinomain southern African blacks

AIM To analyse cumulative loss of heterozygosity (LOH) of chromosomal regions and tumor suppressor genes in hepatocellular carcinomas (HCCs) from 20 southern African blacks. METHODS p53, RB1, BRCA1, BRCA2, WT1 and E cadherin genes were analysed for LOH, and p53 gene was also analysed for the codon 249 mutation, in tumor and adjacent non tumorous liver tissues using molecular techniques and 10 polymorphic microsatellite markers. RESULTS p53 codon 249 mutation was found in 25% of the subjects, as was expected, because many patients were from Mozambique, a country with high aflatoxin B 1 exposure. LOH was found at the RB1, BRCA2 and WT1 loci in 20%(4/*!20) of the HCCs, supporting a possible role of these genes in HCC. No LOH was evident in any of the remaining genes. Reports of mutations of p53 and RB1 genes in combination, described in other populations, were not confirmed in this study. Change in microsatellite repeat number was noted at 9/*!10 microsatellite loci in different HCCs, and changes at two or more loci were detected in 15%(3/*!20) of subjects. CONCLUSION We propose that microsatellite/genomic instability may play a role in the pathogenesis of a subset of HCCs in black Africans.

Effect of 5-Aza-2'-deoxycytidine on the P16 tumor suppressor gene in hepatocellular carcinoma cell line HepG2

INTRODUCTIONHepatocellular carcinoma (HCC) is one of the mostcommon human malignancies worldwide[1,2], and isclosely associated with infection of HBV and HCVand contamination of aflatoxin B1[3-6]. Althoughthe molecular mechanisms of hepatocarcinogenesisremain poorly understood, an increasing number ofgenetic abnormalities have been recognized[7-10],for example, the p16 gene[11,12] the p53gene[13-18], the E-cadherin gene[19], and the c-mycgene[20].

DNA methylation and carcinogenesis in digestive neoplasms

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STUDY ON METASTASIS ASSOCIATED GENE SCREENED BY MONOCLONAL ANTIBODY HIL

The cDNA expression libraries derived from a highly metastatic cell subline Anip-973 and from its parental cell line, low metastatic AGZY-83a were screened by monoclonal antibodies (MoAbs) seperately against these two cell lines. A positive clone(H4-D) from the Anip-973 cDNA library was isolated and its nucleotide sequence was determined. This clone contained 978 bp with an open reading frame of 318 bp encoding a polypeptide consisting of 106 amino acids. The H4-D cDNA sequence showed 85% homology with a human propionyl-CoA carboxylase α-chain. In Western bloting analysis, the MoAb H4 recognized 2 bands(15 KDa and 27 KDa) of Anip-973 cell membrane Protein. The mRNA expression of H4-D was higher in AniP-973 cells than that in AGZY-83a cells. The metastatic Potential of Anip-973 cells was markedly decreased after being pretreated with MoAb H4. The above findings indicated that H4-D has a certain relationship with the metastatic phenotype of AniP-973 cells.

Expression of nm23 gene in hepatocellular carcinoma tissue and its relation with metastasis

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Identification of differentially expressed genes in mouse hepatocarcinoma ascites cell line with low potential of lymphogenous metastasis

AIM: To identify genes differentially expressed in mouse hepatocarcinoma ascites cell line with low potential of lymphogenous metastasis. METHODS: A subtracted cDNA library of mouse hepatocarcinoma cell line with low potential of lympho- genous metastasis Hca-P and its synogenetic cell line Hca-F with high metastatic potential was constructed by suppression subtracted hybridization (SSH) method. The screened clones of the subtracted library were sequenced and GenBank homology search was performed. RESULTS: Fifteen differentially expressed cDNA fragments of Hca-P were obtained which revealed 8 known genes, 4 expressed sequence tags (ESTs) and 3 cDNAs showed no homology. CONCLUSION: Tumor metastasis is an incident involving multiple genes. SSH is a useful technique to detect differentially expressed genes and an effective method to clone novel genes.

Relationship between ras p53 gene RNA and protein expression and HCC metastasis

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Changes of p53 and Waf1p21 and cell proliferation in esophageal carcinogenesis

AIM To study the correlationship between the changes of p53, Waf1p21 and the cell proliferation determined by PCNA at different stages of human esophageal carcinogenesis. METHODS Biopsied and resected esophageal tissues from a high risk population for esophageal cancer in northern China were used in this study. All the specimens were fixed with 85% alcohol and further processed with routine histology. The avidin biotin peroxidase complex (ABC) method was used for the detection of p53, Waf1p21 and PCNA. RESULTS The strong nuclear staining for p53, Waf1p21 and PCNA was observed in the normal esophageal epithelium and the epithelia with different severities of lesions. As the lesions progressed to dysplasia (DYS) and to esophageal squamons cell carcinoma (SCC), the percentage of Waf1p21 immunoreactivity decreased. The number of Waf1p21 immunostaining positive cells increased slightly from normal to basal cell hyperplasia (BCH), but there was no further increase in DYS and in SCC. The total number of positive cells for Waf1p21 stain appeared to be lower than that of p53 in normal and BCH esophageal epithelia and much lower in DYS and SCC. The Waf1p21 positive immunostaining cells were located at the third and forth cell layers in half of the samples examined, which was 2～4 cell layers higher than that of PCNA and p53 in the same histological categories of normal, BCH and DYS. CLNCLUSION The low levels of Waf1p21 at the stage of DYS may be related to a functional loss of p53. Other mechanisms may also be responsible to the lack of Waf1p21 expression in DYS and SCC.

Behind the curtain of non-coding RNAs; long non-coding RNAs regulating hepatocarcinogenesis

Hepatocellular carcinoma(HCC) is one of the most common and aggressive cancers worldwide. HCC is the fifth common malignancy in the world and the second leading cause of cancer death in Asia. Long non-coding RNAs(lncRNAs) are RNAs with a length greater than 200 nucleotides that do not encode proteins. lncRNAs can regulate gene expression and protein synthesis in several ways by interacting with DNA, RNA and proteins in a sequence specific manner. They could regulate cellular and developmental processes through either gene inhibition or gene activation. Many studies have shown that dysregulation of lncRNAs is related to many human diseases such as cardiovascular diseases, genetic disorders, neurological diseases, immune mediated disorders and cancers. However, the study of lncRNAs is challenging as they are poorly conserved between species, their expression levels aren't as high as that of m RNAs and have great interpatient variations. The study of lncRNAs expression in cancers have been a breakthrough as it unveils potential biomarkers and drug targets for cancer therapy and helps understand the mechanism of pathogenesis. This review discusses many long non-coding RNAs and their contribution in HCC, their role in development, metastasis, and prognosis of HCC and how to regulate and target these lncRNAs as a therapeutic tool in HCC treatment in the future.

Genetic Fingerprint Concerned with Lymphatic Metastasis of Human Lung Squamous Cancer

背景与目的筛选肺鳞癌患者淋巴转移差异表达基因群。方法原发癌组织及区域淋巴结取自10例接受完全性肺癌切除手术的肺鳞癌患者。根据组织来源将标本分为三组:不伴淋巴转移的肺鳞癌组织(TxN-,n=5)、伴有淋巴转移的肺鳞癌组织(TxN+,n=5)及相应转移淋巴结中的肺鳞癌细胞(N+,n=5)。对各组进行激光显微切割以获得纯净癌细胞,T7RNA线性扩增获取足够量的RNA,实验通道和参照通道分别标记以后与含6000个已知人类基因或表达序列标签的cDNA基因芯片杂交,扫描荧光信号以后进行数据分析。结果共有37个基因可将TxN+组与TxN-组区分开,其中在TxN+组高表达的基因有8个,主要涉及蛋白合成、信号传导、伴侣蛋白和酶等。有29个基因在TxN-组高表达,这些基因主要编码细胞周期调节子、转导子、信号传导蛋白以及细胞凋亡调节蛋白。比较N+组与TxN+组却没有发现具有显著性的差异表达基因。结论肺鳞癌的淋巴转移表型的获得可能是早期事件。这些差异基因的发现有助于阐明肺鳞癌淋巴转移的分子机制和寻找新的治疗靶点。

KAI1/CD82 gene expression in benign prostatic hyperplasia and late-stage prostate cancer in Chinese

Aim: To evaluate KAII/CD82 expression in Chinese patients with benign prostatic hyperplasia (BPH) and late-stage carcinoma of prostate (CaP). Methods: Thirty Chinese patients with benign prostatic hyperplasia and 34 withCaP (adenocarcinoma clinical stage C and D) were analyzed by means of immunohistochemical methods. Results:The KAII/CD82 expression in BPH tissue was all positive, which was uniformly located on the glandular cell mem-brane at the cell-to-cell borders, but KAII/CD82 expression in metastasis CaP tissues was either significantly lower thanthat of BPH or negative, and the immunostaining pattern was not continuous. In late-stage CAP KAII/CD82 expressionwas correlated inversely to the pathological grade ( P < 0.05), but not to clinical stage ( P > 0.05). Conclusion:The authors believe that decreased and negative KAII/CD82 expression in late-stage CaP may be related to tumor pro-gression and metastasis, and appears to be a prognostic marker.

Alterations in metastatic properties of hepatocellular carcinoma cell following H-ras oncogene transfection

AIM: To demonstrate the relationship between H-ras oncogene and hepatocellular carcinoma (HCC) metastasis. METHODS: Activated H-ras oncogene was transfected into SMMC 7721, a cell line derived from human HCC, by calcium phosphate transfection method. Some metastasis-related parameters were detected in vitro, including adhesion assay, migration assay, expression of collagenase IV(c IV ase) and epidermal growth factor receptor (EGFR). RESULTS: The abilities of H-ras-transfected cell clones in adhesion to laminin (LN) or fibronectin (FN), migration, c IV ase secretion increased markedly, and the expression of EGFR elevated moderately. More importantly, these alterations were consistent positively with the expression of p21, the protein product of H-ras oncogene. CONCLUSION: H-ras oncogene could induce the metastatic phenotype of HCC cell in vitro to raise its metastatic potential.

The expression of c-src gene in the carcinogenesis process of human cardia adenocarcinoma

AIM To investigate the activation, expression of c src gene and its role in the carcinogenetic process of human cardia adenocarcinoma (CA). METHODS Fifty six cases of CA, 34 cases of normal, 36 cases of protiferative epithelia adjacent to carcinoma, and 20 cases of lymph node metastases of CA were studied for PP60 c src , the expression product of c src gene immunohistochemically by using the specific monoclonal antibody, Mab327. RESULTS The positive rates of PP60 c src in the normal epithelia, protiferative epithelia, CA and lymph node metastases were 29 4% (10/*!34), 94 4% (34/*!36), 71 4% (40/*!56) and 60 0% (12/*!20) , respectively, among them, the differences of the positive rates were statistically significant ( P <0 01) . The expression levels of PP60 c src in CA and proliferative epithelia were significantly higher than that in the normal epithelia ( P <0 01) . The PP60 c src positive rates in the papillary, tubular, poorly differentiated and mucous adenocarcinoma were 75 0% (6/*!8) , 81 8% (18/*!22) , 50 0% (10/*!20) and 100 0% (6/*!6) , respectively, whereas those of tubular and mucous adenocarcinomas were significantly higher than those of papillary and poorly differentiated adenocarcinomas ( P <0 05) , and the PP60 c src expression levels of tubular and mucous adenocarcinomas were also significantly higher than those of papillary and poorly differentiated adenocarcinomas ( P <0 01) . CONCLUSION The activation and expression of c src gene are associated with the initiation and development of human CA; the protein amount of PP60 c src increased during the process of carcinogenesis; and PP60 c src expression is also related to lymph node metastases.

INACTIVATION OF THE CDKN2/pl6 GENE INDUCED BY METHYLATION AT 5'-CpG ISLAND AND ITS RELATION TO LUNG CANCER

Objectives: To investigate the methylation status of the CDKN2/pl6 gene 5′-CpG island, and study the relationship between the CDKN2/pl6 gene inactivation by methylation and lung cancer. Methods: Genomic DNA extracted from the specimens of lung cancer and normal lung tissue was digested with methylation-sensitive endonucleases, and Southern blotting was used to analyze the methylation status of the CDKN2/pl6 gene in 89 cases of lung cancer and 10 cases of normal lung tissue. Results: In 89 cases of lung cancer studied, the CDKN2/pl6 gene was shown to be methylated in 21 cases with the total methylation rate of 23.6% (21/89), in which there were 15 cases (16.9%) methylated atSmaI sites, 12 cases (13.5%) atSmaI sites and 6 cases at bothSmaI andSacII sites. The methylation of the CDKN2/pl6 gene occurred in 17 among 42 of pl6 protein negative cases of lung cancer with a rate of 40.5% (17/42), and in 3 among 47 of pl6 protein positive cases with a rate of 6.4% (3/47). The CDKN2/pl6 gene was not methylated in 10 cases of normal lung tissue. Conclusion: The aberrant methylation of the CDKN2/pl6 gene 5′-CpG island is probably an important mechanism of the gene inactivation, it may be involved in the genesis and progress of lung cancer.

HYPERMETHYLATION OF p14^(ARF) PROMOTER REGION AND EXPRESION OF p14^(ARF) GENE PRODUCT IN NON-SMALL CELL LUNG CANCER

Objective： This study was designed to investigate promoter methylation status and protein expression of p14^ARF gene in non-small cell lung cancer, and value the role of p14^ARF promoter methylation in carcinogenesis of non-small cell lung cancer. Methods： Promoter methylation status and protein expression of p14^ARF gene in 40 cases of non-small cell lung cancer were analyzed by methylation specific polymerase china reaction （MSP）, restriction enzyme-related polymerase chain reaction （RE-PCR） and immunohistochemistry （IHC）. Results： The positive rates of p14^ARF promoter methylation in tumor tissues and normal tissues adjacent to cancer were 17.5% （7/40） and 2.5% （1/40） respectively. There were statistically significant differences between them, P〈0.05. The results of RE-PCR were consistent with that of MSP. The expression rate of p14^ARF protein in tumor tissues was significantly lower than that in normal tissues adjacent to cancer, p〈0.01. Promoter methylation status and protein expression of p14^ARF gene in non-small cell lung cancer showed significantly an inverse correlation （r=-0.56, P〈0.01）, and both of them did not relate statistically with the clinicopathologic characteristics of patients such as histological classification, clinical stage, differentiation grade and lymph node involvement. Conclusion： Promoter methylation is a crucial mechanism of inactivation of p14^ARF gene. Promoter methylation of p14^ARF gene might he involved in carcinogenesis of non-small cell lung cancer, and is an early event in development process of non-small cell lung cancer. It might be used as a new target in gene treatments in the future.

IDENTIFICATION OF A NEW HUMAN nm23 GENE,nm23-H3b

Nm23 is a kind of effective tumor metastasis suppressor genes which included two types in human:nm23-H1 and nm23-H2. Amino acid identity between nm23-H1 and nm23-H2 was 88%.In this study,using a pair of primers to flank the part of coding sequence of nm 23,the 5'-translated sequence was amplified by polymerase chain reaction (PCR) from human normal liver genomic DNA.A 375-base pairs clone was charactertzed,which designated pnm23-H3b.The nm23-H3b nucleotide sequence between 40 bp and 70 bp is different from nm23-H1 and nm23-H2,and other sequences have 86%and 90%identical to nm23-H1 and nm23-H2,respectively.Southern blot containing BglⅡ-digested human liver genomic DNA hybridized to the entire nm23-H3b DNA and showed three bands at 10.5,7.9 and 4.0 Kb.These data demonstrate that the third human nm23 exists possibly.Therefore,nm23 may be considered a family of closely related genes.