Analysis of differentially expressed proteins in cancerous and normal colonic tissues

AIM: To identify and analyze the differentially expressed proteins in normal and cancerous tissues of four patients suffering from colon cancer. METHODS: Colon tissues (normal and cancerous) were homogenized and the proteins were extracted using three protein extraction buffers. The extraction buffers were used in an orderly sequence of increasing extraction strength for proteins with hydrophobic properties. The protein extracts were separated using the SDS-PAGE method and the images were captured and analyzed using Quantity One software. The target protein bands were subjected to in-gel digestion with trypsin and finally analyzed using an ESI-ion trap mass spectrometer. RESULTS: A total of 50 differentially expressed proteins in colonic cancerous and normal tissues were identified. CONCLUSION: Many of the identified proteins have been reported to be involved in the progression of similar or other types of cancers. However, some of the identified proteins have not been reported before. In addition, a number of hypothetical proteins were also identified.     

Neural cell adhesion molecule-180 expression as a prognostic criterion in colorectal carcinoma： Feasible or not？

AIM： To evaluate the frequency of neural cell adhesion molecule （NCAM）-180 expression in fresh tumor tissue samples and to discuss the prognostic value of NCAM-180 in routine clinical practice.
METHODS： Twenty-six patients （16 men, 10 women） with colorectal cancer were included in the study. Fresh tumor tissue samples and macroscopically healthy proximal margins of each specimen were subjected to flow-cytometric analysis for NCAM-180 expression.
RESULTS： Flow-cytometric analysis determined NCAM-180 expression in whole tissue samples of macroscopically healthy colorectal tissues. However, NCAM-180 expression was positive in only one case （3.84%） with well-differentiated Stage Ⅱ disease who experienced no active disease at 30 months follow-up.
CONCLUSION： As a consequence of the limited number of cases in our series, it might not be possible to make a generalisation, nevertheless the routine use of NCAM-180 expression as a prognostic marker for colorectal carcinoma seems to be unfeasible and not cost-effective in clinical practice due to its very low incidence.     

Up-regulation of mitochondrial chaperone TRAP1 in ulcerative colitis associated colorectal cancer

AIM:To characterize tumor necrosis factor receptorassociated protein 1(TRAP1)expression in the progression of ulcerative colitis(UC)-associated colorectal cancer.METHODS:Chronic UC is an inflammatory bowel disease that predisposes to colorectal cancer.Immunohistochemical analysis was used to evaluate TRAP1expression on tissue microarrays containing colonic tissues from 42 UC progressors(patients with cancer or dysplasia)and 38 non-progressors(dysplasia/cancer free patients).Statistical analyses of the TRAP1immunohistochemistry staining were performed using Graph Pad Prism.Differences in the TRAP1 level between non-progressors and progressors were tested for statistical significance using the Mann-Whitney test.Receiver operating characteristic curve method was used to quantify marker performance in distinguishing diseased cases from controls.RESULTS:TRAP1 was up-regulated in the colon tissues from UC progressors,but not in the colon tissues from UC non-progressors.Moreover,up-regulation of TRAP1 preceded the neoplastic changes:it was present in both the dysplastic and non-dysplastic tissues of UC progressors.When TRAP1 staining in rectal tissue was used as a diagnostic marker,it could distinguish progressors from non-progressors with 59%sensitivity and 80%specificity.Our study further showed that the increase of TRAP1 expression positively correlated with the degree of inflammation in the colorectal cancer tissues,which could be related to the increased oxidation present in the colonic mucosa from UC progressors.We then investigated the cellular proteome changes underlying oxidative stress,and found that oxidative stress could induce up-regulation of TRAP1 along with several other negative modulators of apoptosis.CONCLUSION:These results suggest that oxidative stress in long standing UC could lead to the increase of cytoprotective protein TRAP1,which in turn could promote cancer progression by preventing or protecting the oxidative damaged epithelial cells from undergoing apoptosis.TRAP1 could be a potential diagnostic marker for UC associated colorectal cancer.     

Ex-vivo evaluation of gene therapy vectors in human pancreatic （cancer） tissue slices

AIM： To culture human pancreatic tissue obtained from small resection specimens as a pre-clinical model for examining virus-host interactions.
METHODS： Human pancreatic tissue samples （malignant and normal） were obtained from surgical specimens and processed immediately to tissue slices. Tissue slices were cultured ex vivo for 1-6 d in an incubator using 95% 02. Slices were subsequently analyzed for viability and morphology. In addition the slices were incubated with different viral vectors expressing the reporter genes GFP or DsRed. Expression of these reporter genes was measured at 72 h after infection.
RESULTS： With the Krumdieck tissue slicer, uniform slices could be generated from pancreatic tissue but only upon embedding the tissue in 3% low melting agarose. Immunohistological examination showed the presence of all pancreatic cell types. Pancreatic normal and cancer tissue slices could be cultured for up to 6 d, while retaining viability and a moderate to good morphology. Reporter gene expression indicated that the slices could be infected and transduced efficiently by adenoviral vectors and by adeno associated viral vectors, whereas transduction with lentiviral vectors was limited. For the adenoviral vector, the transduction seemed limited to the peripheral layers of the explants.
CONCLUSION： The presented system allows reproducible processing of minimal amounts of pancreatic tissue into slices uniform in size, suitable for pre-clinical evaluation of gene therapy vectors.     

Differential expression of genes during aflatoxin B_1-induced hepatocarcinogenesis in tree shrews

AIM:Through exploring the regulation of gene expressionduring hepatocarcinogenesis induced by aflatoxin B_1 (AFB_1),to find out the responsible genes for hepatocellular carcinoma(HCC) and to further understand the underlying molecularmechanism.METHODS:Tree shrews (Tupaia belangerichinensis)weretreated with or without AFB_1 for about 90 weeks.Liverbiopsies were performed regularly during the animalexperiment.Eight shares of total RNA were respectivelyisolated from 2 HCC tissues,2 HCC-surrounding non-cancerous liver tissues,2 biopsied tissues at the early stage(30th week) of the experiment from the same animals asabove,1 mixed sample of three liver tissues biopsied at thebeginning (0th week) of the experiment,and another 1 mixedsample of two liver tissues from the untreated control animalsbiopsied at the 90th week of the experiment.The sampleswere then tested with the method of Atlas~(TM) cDNA microarrayassay.The levels of gene expression in these tissues takenat different time points during hepatocarcinogenesis werecompared.RESULTS:The profiles of differently expressed genes werequite different in different ways of comparison.At the sameperiod of hepatocarcinogenesis,the genes in the samefunction group usually had the same tendency for up-ordown-regulation.Among the checked 588 genes that wereknown to be related to human cancer,89 genes (15.1%)were recognized as“important genes”because they showedfrequent changes in different ways of comparison.Thedifferentially expressed genes during hepatocarcinogenesiscould be classified into four categories:genes up-regulatedin HCC tissue,genes with similar expressing levels in bothHCC and HCC-surrounding liver tissues which were higherthan that in the tissues prior to the development of HCC, genes down-regulated in HCC tissue,and genes up-regulatedprior to the development of HCC but down-regulated afterthe development of HCC.CONCLUSION:A considerable number of genes couldchange their expressing levels both in HCC and in HCC-surrounding non-cancerous liver tissues.A few modulargenes were up-regulated only in HCC but not in surroundingliver tissues,while some apoptosis-related genes weredown-regulated in HCC and up-regulated in surroundingliver tissues.To compare gene-expressing levels amongthe liver tissues taken at different time points duringhepatocarcinogenesis may be helpful to locate theresponsible gene (s) and understand the mechanism forAFB_1 induced liver cancer.     

Expression of p53, p16 and COX-2 in pancreatic cancer with tissue microarray

BACKGROUND: Pancreatic cancer development and progression is driven by the accumulation of genetic changes. In this study we constructed tissue microarray containing specimens from pancreatic cancer, adjacent non-cancer tissue and normal tissue to survey the expression of p53, p16 and cyclooxyganase-2 (COX-2). METHODS: Tissue microarray containing 337 specimens from different stages of pancreatic cancer, adjacent noncancer tissue and normal tissues was constructed, and the expression of p53, p16 and COX-2 was assayed by immunohistochemistry to consecutive formalin-fixed tissue microarray sections. RESULTS: The expression of p53, p16 and COX-2 was significantly higher in tumorous tissues than in non-tumorons ones. A significant relationship was observed between p53 and COX-2, or p16 and COX-2. But no obvious correlation was seen between p53 and p16 expressions. Logistic regression analysis showed p53 and COX-2 as dependent predictors in pancreatic carcinogenesis, and a reciprocal relationship to neoplastic progression between p53 and COX-2. CONCLUSION: Combination analysis of p53 and COX-2 may be useful in predicting pancreatic carcinogenesis.     

Epidemiology of upper gastrointestinal cancers in Iran： A Sub site analysis of 761 cases

AIM： To define the sub site distribution of upper gastrointestinal cancers in three provinces of Iran.
METHODS： The study was carried out in three provinces in Iran： Ardabil, Golestan, and Tehran. In Arbabil and Golestan, the data was collected from the sole referral center for gastrointestinal cancers and the local cancer registry. For Tehran province, data from two major private hospitals were used. All gastric and esophageal cancer patients diagnosed during the period from September 2000 and April 2002 were included in the study.
RESULTS： A total of 761 patients with upper gastrointestinal cancers were identified, 314 from Ardabil, 261 from Golestan, and 186 from Tehran. In Tehran, the relative rate of cancer increased from the upper esophagus to the distal stomach. In Golestan, the reverse pattern was observed. In Ardabil, the mid portion （distal esophagus and proximal stomach） was involved most frequently.
CONCLUSION： There were considerable variations in the sub site of upper gastrointestinal cancers in the three provinces studied, We cannot provide any explanation for this variation, Further research aimed at explaining the discrepancies in sub site distribution of upper gastrointestinal cancers may help identify important risk factors.     

Malignancy in adult celiac disease

Prior studies have suggested that the incidence of some neoplastic disorders, particularly malignant lymphoma and small intestinal adenocarcinoma, are increased in celiac disease. Earlier studies from the United Kingdom have also suggested a link between celiac disease and esophageal carcinoma, although this has not been confirmed in North America. The risk oF other gastrointestinal cancers seems to be limited. Gastric cancer does not appear to be detected more frequently, although direct endoscopic visualization of the upper gastrointestinal tract is now very common in patients with celiac disease. Colon cancer also appears to be limited in celiac disease, even in patients first diagnosed with celiac disease late in life. This has led to the hypothesis that untreated celiac disease may be protective, possibly owing to impaired absorption of fat or fat-soluble agents, including hydrocarbons and putative co-carcinogens implicated in the pathogenesis of colon cancer, which may be poorly absorbed and rapidly excreted.     

Role of nucleostemin in growth regulation of gastric cancer,liver cancer and other malignancies

AIM:To examine the role of nucleostemin in the growthregulation of gastric cancer,liver cancer and other cancers.METHODS:RT-PCR was used to clone the fragment ofnucleostemin cDNA from HEK 293 cells.Eighteen kinds ofmalignant tumor tissues including gastric adenocarcinomaand liver cancer tissues,3 kinds of benign tumor tissues,3kinds of benign hyperplastic tissues and normal tissueswere employed to examine nucleostemin gene expressionby RT-PCR,Slot blot,Northern blot and in situ hybridization.RESULTS:We successfully cloned a 570 bp fragment ofnucleostemin-cDNA from HEK-293 cells.All detectedmalignant tumor tissues,benign tumor tissues,and benignhyperplastic tissues had high levels of nucleosteminexpression.Nucleostemin was also expressed in humanplacenta tissue at a high level.In terminally differentiatednormal human adult kidney and mammary gland tissues,no nucleostemin expression could be detected.CONCLUSION:Nucleostemin can help regulate theproliferation of both cancer cells and stem cells.It mightplay an important role in the growth regulation of gastriccancer,liver cancer and other cancers.     

Copy number variations are progressively associated with the pathogenesis of colorectal cancer in ulcerative colitis

AIM: To evaluate the association of known copy number variations(CNVs) in ulcerative colitis(UC) progressing to colorectal cancer.METHODS: Microsatellite instability analysis using the National Cancer Institute's panel of markers, and CNV association studies using Agilent 2 × 105 k arrays were done in tissue samples from four patient groups with UC: those at low risk(LR) or high risk of developing colorectal cancer, those with premalignant dysplastic lesions, and those with colitis-associated colorectal cancer(CAC). DNA from tissue samples of these groups were independently hybridized on arrays and analyzed. The data obtained were further subjected to downstream bioinformatics enrichment analysis to examine the correlation with CAC progression.RESULTS: Microarray analysis highlighted a progressive increase in the total number of CNVs [LR(n = 178) vs CAC(n = 958), 5.3-fold], gains and losses [LR(n = 37 and 141) vs CAC(n = 495 and 463), 13.4- and 3.3-fold, respectively], size [LR(964.2 kb) vs CAC(10540 kb), 10.9-fold] and the number of genes in such regions [LR(n = 119) vs CAC(n = 455), 3.8-fold]. Chromosomewise analysis of CNVs also showed an increase in the number of CNVs across each chromosome. There were 38 genes common to all four groups in the study; 13 of these were common to cancer genes from the Genetic Disease Association dataset. The gene set enrichment analysis and ontology analysis highlighted many cancerassociated genes. All the samples in the different groupswere microsatellite stable.CONCLUSION: Increasing numbers of CNVs are associated with the progression of UC to CAC, and warrant further detailed exploration.     

Aneusomy of chromosome 18 is associated with the development of colorectal carcinoma

Specific loss of heterozygosity of chromosome 18 has been observed frequently in advanced colorectal carcinoma and is closely associated with its development. We investigated the prevalence of numerical aberrations of chromosome 18 in 44 specimens of colorectal carcinomas, using fluorescence in situ hybridization. We also examined the relationships between aneusomy of chromosome 18 and the clinicopathological features of these tumors. Aneusomy of the specimens (monosomy and polysomy) was determined when the same aneusomic population was detected in more than 15% of the nuclei. The frequency of monosomy and polysomy of chromosome 18 in colorectal carcinomas was 43% (19/44) and 29% (12/44), respectively. The prevalence of monosomy and polysomy 18 was significantly higher in cancers with invasion exceeding category T2 compared with T1 (P<0.01), and with tumor size exceeding 20 mm in diameter compared with tumors less than 20 mm (P<0.05). However, the prevalence of aneusomy 18 was not associated with other clinico-pathological features. The mean survival period and the 5-year survival rate after operation in patients with aneusomy 18 was not different from findings for those with disomy 18. Our results indicate that aneusomy of chromosome 18 is associated with the development of colorectal carcinoma; however, it is not a useful indicator of postoperative prognosis.     

Quantitative detection of lung cancer cells by fluorescence in situ hybridization: comparison with conventional cytology

STUDY OBJECTIVE: The aim of this study was to clarify whether fluorescence in situ hybridization (FISH) can diagnose lung cancer in various clinical specimens in comparison with conventional cytology. DESIGN: Prospective study. SETTING: University hospital in a metropolitan area. PATIENTS: Fifty consecutive patients with abnormal chest radiography or CT scan findings were enrolled. The patients included 32 men and 18 women, with an average age of 64 years. The final definitive diagnosis was made by histologic examination, as follows: 38 primary lung cancers (24 adenocarcinomas, 8 squamous cell carcinomas, 2 large cell carcinomas, and 4 small cell carcinomas); 1 metastatic renal cell carcinoma; and 11 benign lesions. METHODS: Four types of clinical specimens were analyzed. Cells obtained by transbronchial brushing and transbronchial fine-needle aspiration using a fiberoptic bronchoscope under fluoroscopy, CT scan-guided percutaneous needle biopsy, and bronchial washings. On every examination, duplicate slides were made for analyses of conventional cytology and FISH. RESULTS: Classifications according to conventional cytology were as follows: class I, 4 patients; class II, 15 patients; class IIIa, 3 patients; class IIIb, 5 patients; and class V, 23 patients. A classification higher than class IIIb was considered to be positive for cancer. For cytology, we found no false-positive cases and 11 false-negative cases. The specificity was 100%, and the sensitivity was 71.8%. By FISH, 34 cases showed aberrant copy numbers in either chromosome 3 or 17. We found no false-positive cases and five false-negative cases. The specificity was 100%, and the sensitivity was 87.1%. CONCLUSION: The ability of FISH to detect aneusomic lung cancer cells is superior to conventional cytology for the diagnosis of lung cancer.     

Distinction between the Preneoplastic and Neoplastic State of Murine Mammary Glands

We have, using nuclear magnetic resonance spectroscopy, measured the relaxation times and diffusion coefficient of water protons in primary mammary adenocarcinomas of mice. In our biological model, three morphological stages were defined: (a) mammary gland tissue from pregnant mice, (b) preneoplastic nodules, and (c) neoplastic tissue. It was found that neoplastic tissues could be distinguished from normal and prenoeplastic tissue. Spin-spin and spin-lattice relaxation times and the diffusion coefficient of water protons are increased in the neoplastic tissue relative to mammary gland tissue from pregnant mice and preneoplastic nodule tissue.     

Chromosome arm 20q gains and other genomic alterations in esophageal squamous cell carcinoma, as analyzed by comparative genomic hybridization and fluorescence in situ hybridization

BACKGROUND/AIMS: Our recent analysis of gastric cancers and colorectal cancers using comparative genomic hybridization revealed a novel, high frequent copy number increases the long arm of chromosome 20 in association with possible involvement of liver metastases and poor prognosis. This led to further comparative genomic hybridization analysis of chromosomal aberrations in primary tumors of esophageal squamous cell carcinoma. The aim of the study presented here was to analyze the chromosomal aberrations and to determine the numbers of copies of AIB1, BTAK, DcR3 and E2F1 as putative target genes on chromosome 20q as well as their expression and relation to clinicopathological features in 41 primary tumors of esophageal squamous cell carcinoma. METHODOLOGY: We used comparative genomic hybridization to screen 41 primary tumors of esophageal squamous cell carcinoma for changes in the number of copies of DNA sequences. To further characterize the gain of DNA sequences at 20q, we also performed fluorescence in situ hybridization analysis. We examined the relationship between these changes and clinicopathological factors. RESULTS: Gains in chromosome arm 20q were detected (34.1%) as well as a high level of gain in 20q12-13 (4.8%). AIB1 amplification was observed in 4.9% (2/41), BTAK amplification in 9.8% (4/41), DcR3 amplification was in 4.9% (2/41), and E2F1 amplification in 7.3% (3/41). The survival of patients with BTAK or E2F1 amplification was significantly lower than that of patients without these abnormalities. CONCLUSIONS: These findings provide evidence for a number of previously unknown genomic aberrations in esophageal squamous cell carcinoma, suggesting the existence of target regions relevant to its progression. Esophageal squamous cell carcinoma with 20q gain showed extensive lung metastases, pleural effusion and liver metastases and poorer prognosis compared to cases without 20q gain. Our results suggest that amplification of BTAK or E2F1 are likely to lead to an increase in the number of malignant phenotypes of esophageal squamous cell carcinoma and that these aberrations can be expected to be useful as markers of poor prognosis.     

Trisomy 3 in marginal zone B-cell lymphoma: a study based on cytogenetic analysis and fluorescence in situ hybridization

Trisomy 3 represents the most frequent and consistent chromosomal abnormality characterizing the recently defined entity marginal zone B-cell lymphoma (MZBCL). By cytogenetic analysis and/or fluorescence in situ hybridization (FISH) on interphase nuclei we found an increased copy number of chromosome 3 in 22/36 (61%) successfully analysed cases, including 8/12 cases with extranodal MZBCL, 8/13 cases with nodal MZBCL, and 6/11 patients with splenic MZBCL. Sensitivity of interphase cytogenetics was somewhat higher than that of conventional cytogenetic investigation. Structural chromosomal changes involving at least one chromosome 3 were seen in 11/20 cases with an increased copy number of chromosome 3: +del(3)(p13) was demonstrated in three cases, and was the sole chromosomal abnormality in one of them; +i(3)(q10) was seen in two other patients; and rearrangements involving various breakpoints on the long arm of chromosome 3 were found in the remaining cases. FISH on metaphase spreads confirmed these structural abnormalities and additionally showed two unexpected translocations involving chromosome 3. We conclude that: (1) trisomy 3 occurs in a high proportion of extranodal, nodal and splenic MZBCL; (2) FISH on interphase nuclei is an additional and sensitive tool in detecting an increased copy number of chromosome 3 in MZBCL; (3) additional structural abnormalities involving the long arm of chromosome 3 are frequent but non-recurrent and are perhaps secondary changes; and (4) abnormalities such as +del(3)(p13) and +i(3)(q10) suggest that genes located on the long arm of chromosome 3 are of particular importance in the pathogenesis of MZBCL.     

Aromatase overexpression and breast hyperplasia, an in vivo model--continued overexpression of aromatase is sufficient to maintain hyperplasia without circulating estrogens, and aromatase inhibitors abrogate these preneoplastic changes in mammary glands

To test directly the role of breast-tissue estrogen in initiation of breast cancer, we have developed the aromatase-transgenic mouse model and demonstrated for the first time that increased mammary estrogens resulting from the overexpression of aromatase in mammary glands lead to the induction of various preneoplastic and neoplastic changes that are similar to early breast cancer. Continued overexpression of aromatase that leads to increased breast-tissue estrogen contributes to a number of epigenetic changes in mammary tissue such as alteration in the regulation of genes involved in apoptosis, activation of genes involved in cell cycle and cell proliferation, and activation of a number of growth factors. Our current studies show aromatase overexpression is sufficient to induce and maintain early preneoplastic and neoplastic changes in female mice without circulating ovarian estrogen. Preneoplastic and neoplastic changes induced in mammary glands as a result of aromatase overexpression can be completely abrogated with the administration of the aromatase inhibitor, letrozole. Consistent with complete reduction in hyperplasia, we have also seen downregulation of estrogen receptor and a decrease in cell proliferation markers, suggesting aromatase-induced hyperplasia can be treated with aromatase inhibitors. Our studies demonstrate that aromatase overexpression alone, without circulating estrogen, is responsible for the induction of breast hyperplasia and these changes can be abrogated using aromatase inhibitors.     

Enzyme Activity in Invasive Tumors of Human Breast and Colon

Elevated levels of glycoprotein:sialyltransferase activity (EC 2.4.99.1; CMP-N-acetylneuraminate: D-galactosyl-glycoprotein N-acetylneuraminyltransferase) were found in human malignant neoplastic tissues compared to normal, benign, and "preneoplastic" tissues. This increase was not due to the cell density of the tissue. Elevated levels of certain proteases and glycosidases were also found. The increase in transferase activity may be associated with altered membrane synthesis in the neoplastic state; changes in the activity of degradative enzymes may be associated with tumor invasiveness and maintenance of the neoplastic state. Measurements on human tumors are possibly more directly relevant to cancer than those described for transformed fibroblastic cells in vitro.     

Quantitative analysis of numerical chromosome aberrations in various morphological types of colorectal carcinomas

Quantitative analysis by fluorescence in situ hybridization (FISH) on thin paraffin-embedded tissue sections, using specific probes for chromosomes 11, 17, and 18 was employed in various morphological types of early and advanced colorectal cancer to clarify tumor cytogenetics. The chromosome index (CI) was calculated as a quantitative measure of the chromosome copy number. Compared with the CI of normal epithelium, the CI of chromosome 11 in villous components of adenomas or polypoid early cancers was decreased, while the CI in flat type or advanced colorectal cancers, conversely, was increased (P<0.05). The CI of chromosome 17 in villous components of adenomas and all cancers was higher than that of normal epithelium (P<0.05), but the differences were not significant. In protruding advanced cancers, the CI of chromosome 18 was significantly decreased (P<0.01) compared to the CI of normal epithelium. There was no significant chromosomal heterogeneity between the superficial and the deepest layer in each cancer. In mucosa adjacent to sessile and flat type cancers, the CI of chromosome 17 was significantly higher than the CI in normal epithelium or adenomas (P<0.05). These results suggest that numerical chromosome aberrations are associated with the histological type of adenoma and the morphological diversity of cancer in the colorectum, and that chromosome 17 abnormality occurs in mucosa adjacent to sessile and flat cancers.     

Genomic imbalances in esophageal carcinoma cell lines involve Wnt pathway genes

AIM:To identify molecular markers shared across South African esophageal squamous cell carcinoma(ESCC) cell lines using cytogenetics,fluorescence in situ hybridization(FISH) and single nucleotide polymorphism(SNP) array copy number analysis.METHODS:We used conventional cytogenetics,FISH,and multicolor FISH to characterize the chromosomal rearrangements of five ESCC cell lines established in South Africa.The whole genome copy number profile was established from 250K SNP arrays,and data was analyzed with the ...     

Higher frequencies of numerical aberrations of chromosome 17 in primary gastric cancers are associated with lymph node metastasis

We investigated the correlation between the frequency of numerical aberrations of chromosome 17 and clinicopathological features of gastric cancer. The copy number of chromosome 17 was examined with fluorescence in-situ hybridization (FISH) in frozen specimens from 100 primary gastric cancers. Chromosomal numerical aberrations were diagnosed as chromosomal loss (single signal) or gain (triple or more signals), in each cell. The frequency of numerical aberrations of chromosome 17 correlated significantly with the depth of invasion (P < 0.01), lymph node metastasis (P < 0.0001), lymphatic invasion (P < 0.001), and venous invasion (P < 0.01). Numerical aberrations of chromosome 17 were associated with lymph node metastasis in 32 early gastric cancers. Multiple regression analysis identified the depth of invasion and numerical aberrations of chromosome 17 as independent significant determinants of lymph node metastasis. Our findings suggest that alterations in chromosome 17 may be linked with tumor progression in primary gastric cancer. Our results also indicate that numerical aberrations of chromosome 17 detected by FISH provide important information about the malignant potential (in particular, lymph node metastasis) of primary gastric cancer. (Received Feb. 22, 1998; accepted July 24, 1998)