Clinical implications of chromosomal abnormalities in gastric adenocarcinomas

Detection of genetic alterations in gastric cancer patients from Saudi Arabia using comparative genomic hybridization (CGH)

Background

The present study was conducted to discover genetic imbalances such as DNA copy number variations (CNVs) associated with gastric cancer (GC) and to examine their association with different genes involved in the process of gastric carcinogenesis in Saudi population.

Methods

Formalin-fixed paraffin-embedded (FFPE) tissues samples from 33 gastric cancer patients and 15 normal gastric samples were collected. Early and late stages GC samples were genotyped and CNVs were assessed by using Illumina HumanOmni1-Quad v.1.0 BeadChip.

Results

Copy number gains were more frequent than losses throughout all GC samples compared to normal tissue samples. The mean number of the altered chromosome per case was 64 for gains and 40 for losses, and the median aberration length was 679115bp for gains and 375889bp for losses. We identified 7 high copy gain, 52 gains, 14 losses, 32 homozygous losses, and 10 copy neutral LOHs (loss of heterozygosities). Copy number gains were frequently detected at 1p36.32, 1q12, 1q22, 2p11.1, 4q23-q25, 5p12-p11, 6p21.33, 9q12-q21.11, 12q11-q12, 14q32.33, 16p13.3, 17p13.1, 17q25.3, 19q13.32, and losses at 1p36.23, 1p36.32, 1p32.1, 1q44, 3q25.2, 6p22.1, 6p21.33, 8p11.22, 10q22.1, 12p11.22, 14q32.12 and 16q24.2. We also identified 2 monosomy at chromosome 14 and 22, 52 partially trisomy and 22 whole chromosome 4 neutral loss of heterozygosities at 13q14.2-q21.33, 5p15.2-p15.1, 5q11.2-q13.2, 5q33.1-q34 and 3p14.2-q13.12. Furthermore, 11 gains and 2 losses at 1p36.32 were detected for 11 different GC samples and this region has not been reported before in other populations. Statistical analysis confirms significant association of H. pylori infection with T4 stage of GC as compare to control and other stages.

Conclusions

We found that high frequency of copy number gains and losses at 1p36.23, 1p32.1, 1p36.32, 3q25.2, 6p21.33 and 16q24.2 may be common events in gastric cancer. While novel CNVs at 1p36.32 harbouring PRDM16, TP73 and TP73-AS1 genes showed 11 gains and 2 losses for 11 different GC cases and this region is not reported yet in Database of Genomic Variants may be specific to Saudi population.

Characterization of human gastric adenocarcinoma cell lines established from peritoneal ascites

The three cell lines, designated as gastric cancer (GC)1401, GC1415 and GC1436 were derived from peritoneal effusions from patients with gastric adenocarcinoma. Cell lines were established in tissue culture and in immunodeficient, non-obese diabetic/severe combined immunodeficiency (NOD/SCID) mice. All cell lines were cultured in Dulbecco's modified Eagle's medium supplemented with 5% fetal bovine serum. These cell lines were grown as an adherent monolayer with doubling time ranging between 25 h (GC1436 cell line) and 30–34 h (GC1401 and GC1415, respectively). All cells showed morphological features of epithelial-like cells, forming sheets of polygonal cells. Chromosomal analysis showed that the modal numbers ranged from 52 (GC1401), 51–56 (GC1415) and 106 (GC1436). High heterogeneity, resulting from several structural and numerical chromosomal abnormalities were evident in all cell lines. The surface marker expression suggested a tumor origin of the cells, and indicated the intestinal phenotype of a GC (CD10⁺, MUC1). All three cell lines were tumorigenic but not metastatic, in vivo, in NOD/SCID mice. The lack of metastatic potential was suggested by the lack of aldehyde dehydrogenase 1A1 activity. In conclusion, these newly established GC cell lines widen the feasibility of the functional studies on biology of GC as well as drug testing for potential therapeutic purposes.

NKX6.3 Regulates Reactive Oxygen Species Production by Suppressing NF-kB and DNMT1 Activities in Gastric Epithelial Cells

NKX6.3 plays an important role in gastric epithelial differentiation and also acts as a gastric tumor suppressor. The specific aim of this study was to determine whether NKX6.3 contributes to gastric mucosal barrier function by regulating reactive oxygen species (ROS) production. NKX6.3 reduced ROS production and regulated expression of anti-oxidant genes, including Hace1. In addition, NKX6.3 reduced DNMT1 expression and activity by down-regulating NF-kB family gene transcription. Silencing of Hace1 recovered ROS production, whereas knock-down of DNMT1 and NF-kB reduced ROS production and induced Hace1 expression by hypomethylating its promoter region. In addition, NKX6.3 inhibited CagA effects on cell growth, ROS production, and NF-kB and DNMT1 activity. In gastric mucosae and cancers, NKX6.3 and Hace1 expression was significantly reduced. The NKX6.3 expression was positively correlated with Hace1 and Nrf2 genes, but negatively correlated with DNMT1. Hypermethylation of Hace1 gene was observed only in gastric mucosae with H. pylori, atrophy and intestinal metaplasia. Thus, these results suggest that NKX6.3 inhibits ROS production by inducing the expression of Hace1 via down-regulating NF-kB and DNMT1 activity in gastric epithelial cells.

CAS (CSE1L) signaling pathway in tumor progression and its potential as a biomarker and target for targeted therapy

CSE1L (chromosome segregation 1-like protein), also named as CAS (cellular apoptosis susceptibility protein), is highly expressed in most cancer types. CSE1L/CAS is a multiple functional protein that plays roles in apoptosis, cell survival, chromosome assembly, nucleocytoplasmic transport, microvesicle formation, and cancer metastasis; some of the functions are explicitly correlated. CSE1L is also a cancer serum biomarker. The phosphorylation of CAS is regulated by the extracellular signal-regulated kinase (ERK). The RAS/RAF/MAPK/ERK signaling pathways are the essential targets of most targeted cancer drugs, thus serum phosphorylated CSE1L may be a potential biomarker for monitoring drug resistance in targeted therapy. CSE1L can regulate Ras-induced ERK phosphorylation. CSE1L also regulates the expression and phosphorylation of CREB (cAMP response element binding protein) and MITF (microphthalmia-associated transcription factor) and is thus involved in the melanogenesis and progression of melanoma. CAS is an exosome/microvesicle membrane protein. Tumor cells consistently secrete microvesicles and tumor-derived microvesicles may be accumulated around tumors. Therefore, microvesicle membrane CSE1L may be a potential target for the development of high-efficacy antibody-drug conjugates (ADCs) for cancer therapy. This review will focus on CSE1L expression in cancers, its relationship to Ras/ERK and cAMP/PKA signaling pathways in melanoma development, its potential for the development of ADCs and tumor imaging reagents, and secretory phosphorylated CSE1L for monitoring the emergence of drug resistance in targeted cancer therapy.

Inactivation of NKX6.3 in the stomach leads to abnormal expression of CDX2 and SOX2 required for gastric-to-intestinal transdifferentiation

Intestinal metaplasia in gastric mucosa is considered a preneoplastic lesion that progresses to gastric cancer. However, the molecular networks underlying this lesion formation are largely unknown. NKX6.3 is known to be an important regulator in gastric mucosal epithelial differentiation. In this study, we characterized the effects of NKX6.3 that may contribute to gastric intestinal metaplasia. NKX6.3 expression was significantly reduced in gastric mucosae with intestinal metaplasia. The mRNA expression levels of both NKX6.3 and CDX2 predicted the intestinal metaplasia risk, with an area under the receiver operating characteristic curve value of 0.9414 and 0.9971, respectively. Notably, the NKX6.3 expression level was positively and inversely correlated with SOX2 and CDX2, respectively. In stable AGS(NKX6.3) and MKN1(NKX6.3) cells, NKX6.3 regulated the expression of CDX2 and SOX2 by directly binding to the promoter regions of both genes. Nuclear NKX6.3 expression was detected only in gastric epithelial cells without intestinal metaplasia. Furthermore, NKX6.3-induced TWSG1 bound to BMP4 and inhibited BMP4-binding activity to BMPR-II. These data suggest that NKX6.3 might function as a master regulator of gastric differentiation by affecting SOX2 and CDX2 expression and the NKX6.3 inactivation may result in intestinal metaplasia in gastric epithelial cells.

Gastrokine 1 inhibits the carcinogenic potentials of Helicobacter pylori CagA

Helicobacter pylori CagA directly injected by the bacterium into epithelial cells via a type IV secretion system, leads to cellular changes such as morphology, apoptosis, proliferation and cell motility, and stimulates gastric carcinogenesis. We investigated the effects of cytotoxin-associated gene A (CagA) and gastrokine 1 (GKN1) on cell proliferation, apoptosis, reactive oxygen species (ROS) production, epithelial-mesenchymal transition (EMT) and cell migration in CagA- or GKN1-transfected gastric epithelial cells and mucosal tissues from humans and mice infected with H.pylori. On the molecular level, H.pylori CagA induced increased cell proliferation, ROS production, antiapoptotic activity, cell migration and invasion. Moreover, CagA induced activation of NF-κB and PI3K/Akt signaling pathways and EMT-related proteins. In addition, H.pylori CagA reduced GKN1 gene copy number and expression in gastric cells and mucosal tissues of humans and mice. However, GKN1 overexpression successfully suppressed the carcinogenic effects of CagA through binding to CagA. These results suggest that GKN1 might be a target to inhibit the effects from H.pylori CagA.

The association between DNA copy number aberrations at chromosome 5q22 and gastric cancer

BACKGROUND

Gastric cancer is common cancer. Discovering novel genetic biomarkers might help to identify high-risk individuals. Copy number variation (CNV) has recently been shown to influence risk for several cancers. The aim of the present study was sought to test the association between copy number at a variant region and GC.

METHODS

A total of 110 gastric cancer patients and 325 healthy volunteers were enrolled in this study. We searched for a CNV and found a CNV (Variation 7468) containing part of the APC gene, the SRP19 gene and the REEP5 gene. We chose four probes targeting at APC-intron8, APC-exon9, SRP19 and REEP5 to interrogate this CNV. Specific Taqman probes labeled by different reporter fluorophores were used in a real-time PCR platform to obtain copy number. Both the original non-integer data and transformed integer data on copy number were used for analyses.

RESULTS

Gastric caner patients had a lower non-integer copy number than controls for the APC-exon9 probe (Adjusted p = 0.026) and SRP19 probe (Adjusted p = 0.002). The analysis of integer copy number yielded a similar pattern although less significant (Adjusted p = 0.07 for APC-exon9 probe and Adjusted p = 0.02 for SRP19 probe).

CONCLUSIONS

Losses of a CNV at 5q22, especially in the DNA region surrounding APC-exon 9, may be associated with a higher risk of gastric cancer.

Genome expression analysis by suppression subtractive hybridization identified overexpression of Humanin, a target gene in gastric cancer chemoresistance

BACKGROUND

In cancer cells, apoptosis is an important mechanism that influences the outcome of chemotherapy and the development of chemoresistance. To find the genes involved in chemoresistance and the development of gastric cancer, we used the suppression subtractive hybridization method to identify the genes that are overexpressed in gastric cancer tissues compared to normal gastric tissues.

RESULTS

In the suppression subtractive hybridization library we constructed, the most highly overexpressed genes were humanin isoforms. Humanin is a recently identified endogenous peptide that has anti-apoptotic activity and has been selected for further study due to its potential role in the chemoresistance of gastric cancer. Upregulation of humanin isoforms was also observed in clinical samples by using quantitative real-time PCR. Among the studied isoforms, humanin isoform 3, with an expression level of 4.166 ± 1.44 fold, was the most overexpressed isoform in GC.

CONCLUSIONS

The overexpression of humanin in gastric cancer suggests a role for chemoresistance and provides new insight into the biology of gastric cancer. We propose that humanin isoforms are novel targets for combating chemoresistance in gastric cancer.

Advances in biomarkers for esophageal cancer

Cancer of the esophagus is an aggressive disease with early lymphatic and hematogenous dissemination and at present often considered as one clinical entity because of their comparable increasing incidence, prognosis and optimal treatment options. However, it is still a matter of debate whether these malignancies have the same pathogenesis and genotype. Despite recent advances, treatment of upper gastrointestinal malignancies remains a significant challenge. Molecular pathology has revealed many molecular mechanisms of disease progression, which are related to prognosis. Better knowledge of molecular bases may lead to new paradigms, improved prognostication, early diagnosis and individually tailored therapeutic options. This review summarizes the rationale, preclinical evidence, retrospective clinical analyses and the interim clinical data pertaining HER2 therapy and many other molecular pathways.

Molecular biomarkers in esophageal, gastric, and colorectal adenocarcinoma

Cancers of the esophagus, stomach and colon contribute to a major health burden worldwide and over 20% of all cancer deaths. Biomarkers that should indicate pathogenic process and are measureable in an objective manner for these tumors are rare and not established in the clinical setting. In general biomarkers can be very useful for cancer management as they can improve clinical decision-making regarding diagnosis, surveillance, and therapy. Biomarkers can be different types of molecular entities (such as DNA, RNA or proteins), which can be detected, in different tissues or body fluids. However, more important is the type of biomarker itself, which allows diagnostic, prognostic or predictive analyses for different clinical problems. This review aims to systematically summarize the recent findings of genetic and epigenetic markers for gastrointestinal tumors within the last decade. While many biomarkers seem to be very promising, especially if used as panels, further development is urgently needed to address practical considerations of biomarkers in cancer treatment.

Identification of genes with a correlation between copy number and expression in gastric cancer

Background

To elucidate gene expression associated with copy number changes, we performed a genome-wide copy number and expression microarray analysis of 25 pairs of gastric tissues.

Methods

We applied laser capture microdissection (LCM) to obtain samples for microarray experiments and profiled DNA copy number and gene expression using 244K CGH Microarray and Human Exon 1.0 ST Microarray.

Results

Obviously, gain at 8q was detected at the highest frequency (70%) and 20q at the second (63%). We also identified molecular genetic divergences for different TNM-stages or histological subtypes of gastric cancers. Interestingly, the C20orf11 amplification and gain at 20q13.33 almost separated moderately differentiated (MD) gastric cancers from poorly differentiated (PD) type. A set of 163 genes showing the correlations between gene copy number and expression was selected and the identified genes were able to discriminate matched adjacent noncancerous samples from gastric cancer samples in an unsupervised two-way hierarchical clustering. Quantitative RT-PCR analysis for 4 genes (C20orf11, XPO5, PUF60, and PLOD3) of the 163 genes validated the microarray results. Notably, some candidate genes (MCM4 and YWHAZ) and its adjacent genes such as PRKDC, UBE2V2, ANKRD46, ZNF706, and GRHL2, were concordantly deregulated by genomic aberrations.

Conclusions

Taken together, our results reveal diverse chromosomal region alterations for different TNM-stages or histological subtypes of gastric cancers, which is helpful in researching clinicopathological classification, and highlight several interesting genes as potential biomarkers for gastric cancer.

A WWOX-binding molecule, transmembrane protein 207, is related to the invasiveness of gastric signet-ring cell carcinoma

Using the PCR-based subtractive messenger RNA hybridization assay described in this paper, we isolated a hitherto uncharacterized gene, transmembrane protein 207 (TMEM207), which was selectively expressed in collagen gel-invading cultured signet-ring cell carcinoma KATO-III cells. TMEM207 has a C-terminal proline-rich PPxY motif, which binds to the WW domain-containing oxidoreductase, WWOX. Enforced expression of TMEM207 significantly increased Matrigel invasion activity of KATO-III cells in vitro without affecting cell growth. In contrast, expression of TMEM207 with mutations in the PPxY motif did not significantly increase Matrigel invasion activity of KATO-III cells. Immunohistochemical staining showed that TMEM207 was strongly expressed in 7 of 30 gastric signet-ring cell carcinoma tissue specimens. Notably, TMEM207 expression was associated with the depth of cancer invasion and the presence of lymph node metastasis. The results of co-immunoprecipitation followed by western immunoblotting showed that TMEM207 is bound to WWOX in a PPxY motif-dependent manner. Small interfering RNA-mediated downregulation of WWOX also significantly increased Matrigel invasion activity of KATO-III cells. Notably, exogenous expression of TMEM207 impaired the WWOX-mediated repression of Matrigel invasion activity of another cultured signet-ring cell carcinoma cell line, NUGC-4 cells. Recent studies have highlighted the fact that WWOX acts as a tumor suppressor factor in various malignant tumors, including gastric cancer. On the basis of these findings and the results of the present study, we think that overexpression of TMEM207 may facilitate invasive activity and metastasis of gastric signet-ring cell carcinoma, which possibly occur through binding to WWOX and attenuation of its function.

Her-2/neu testing and therapy in gastroesophageal adenocarcinoma

Despite ongoing advances in the treatment of gastroesophageal cancer, prognosis remains poor. The best promise to improve this poor survival is provided by new targeted agents. Of these, human epidermal growth factor receptor 2 (HER2) is currently in the spotlight. In this review, we provide an overview of recent developments in HER2 testing and results of clinical trials targeting HER2 in gastroesophageal adenocarcinoma. Based on the encouraging ToGA trial findings it is now expected that routine HER2 testing will be included in the diagnostic work-up of patients with advanced gastric cancer. With regard to this testing, overexpression of the HER2 protein seems to possess the best predictive properties. However, HER2 immunohistochemistry (IHC) is subject to assay and interobserver variability, so standardization and internal and external proficiency testing is an absolute prerequisite, especially as the IHC scoring system in gastric cancer is different from that of breast cancer. Further study is needed to investigate the clinical meaning of the significant heterogeneity observed in both gene amplification and protein overexpression in gastroesophageal cancer. Highly effective therapies for gastroesophageal cancer can only be accomplished by a multi-targeted approach, considering crosstalk between pathways and continuing to optimize chemotherapy.

Differential gene and protein expression in primary gastric carcinomas and their lymph node metastases as revealed by combined cDNA microarray and tissue microarray analysis

OBJECTIVE

To gain insight into the molecular events of lymph node metastasis of human gastric carcinoma.

METHODS

The gene expression profile of five matched primary gastric carcinomas and their lymph node metastases was analyzed by complementary DNA (cDNA) microarray. Differential genes were identified in the metastatic and corresponding primary tumor pairs. Among the differentially expressed genes, carbonic anhydrase II (CAII) and insulin-like growth factor binding protein 4 (IGFBP 4) genes were detected by RT-PCR. CTTN protein expression was examined by tissue microarray.

RESULTS

There was a high expression (over twofold) of 44 genes and a low expression (under twofold) of 32 genes in lymph node metastasis compared with primary gastric carcinoma, respectively. CAII mRNA was downregulated and IGFBP 4 mRNA was upregulated in paired lymph node metastases of gastric carcinomas. The overexpression of CTTN protein was related to the lymph node metastasis and the clinical stage of gastric carcinomas.

CONCLUSION

This study showed that there is a low expression of genes relative to growth signal and immune response in lymph node metastases, and a high expression of genes relative to growth factor, cell cycle, cell motility and adhesion in lymph node metastases compared with primary gastric carcinomas. The expression of CTTN was related to the invasion and metastasis of gastric cancer.

Nature meets nurture: molecular genetics of gastric cancer

The immensity of genes and molecules implicated in gastric carcinogenesis is overwhelming and the relevant importance of some of these molecules is too often unclear. This review serves to bring us up-to-date with the latest findings as well as to look at the larger picture in terms of how to tackle the problem of solving this multi-piece puzzle. In this review, the environmental nurturing of intestinal cancer is discussed, beginning with epidemiology (known causative factors for inducing molecular change), an update of H. pylori research, including the role of inflammation and stem cells in premalignant lesions. The role of E-cadherin in the nature (genotype) of diffuse gastric cancer is highlighted, and finally the ever growing discipline of SNP analysis (including IL1B) is discussed.

Genomic organization and functional characterization of the promoter for the human suppressor of cytokine signaling 6 gene

In this study, we report the expression and genomic structure of the gene encoding human suppressor of cytokine signaling 6 (SOCS6), and the characterization of the functional promoter region. The human SOCS6 gene, spanning 40 kb on chromosome 18q22.2, is composed of two exons separated by an intron of 35 kb. Two transcripts are ubiquitously expressed, and both encode the full-length open reading frame of SOCS6. A primer extension assay revealed that the major transcription initiation site is located 469 bp upstream the ATG codon. Luciferase promoter analysis demonstrated that the 5'-flanking region is able to drive transcription, and the CpG-rich sequences near the transcription initiation site are important for the TATA-less SOCS6 promoter activity. Analogous to SOCS1 and SOCS3, which are down-regulated in several human cancers, SOCS6 is expressed at lower levels in carcinomas of stomach and colon. We demonstrated that hypermethylation of the SOCS6 promoter is one of the mechanisms for the epigenetic regulation of SOCS6 expression. Firstly, in vitro methylation of the reporter promoter plasmid significantly suppressed the promoter activity. Secondly, SOCS6 expression in vivo was enhanced by treating cells with a methyltransferase inhibitor. The SOCS6 gene from various species shares significant homology in amino acid sequences, transcription factor binding motifs in promoter regions and the two-exon genomic structure, suggesting that the SOCS6 gene is highly conserved.

Nature meets nurture: molecular genetics of gastric cancer

The immensity of genes and molecules implicated in gastric carcinogenesis is overwhelming and the relevant importance of some of these molecules is too often unclear. This review serves to bring us up-to-date with the latest findings as well as to look at the larger picture in terms of how to tackle the problem of solving this multi-piece puzzle. In this review, the environmental nurturing of intestinal cancer is discussed, beginning with epidemiology (known causative factors for inducing molecular change), an update of H. pylori research, including the role of inflammation and stem cells in premalignant lesions. The role of E-cadherin in the nature (genotype) of diffuse gastric cancer is highlighted, and finally the ever growing discipline of SNP analysis (including IL1B) is discussed.

Cytogenetic and molecular aspects of gastric cancer: clinical implications

Gastric cancer is of major importance world-wide being the second most common cause of cancer-related death in the world. According to Lauren's histological classification gastric cancer is divided in two groups, the better differentiated intestinal carcinomas and the poorly differentiated diffuse-type cancers. The genetic changes underlying the initiation and progression of gastric cancer are not well defined. Gastric carcinogenesis is a multistep process involving a number of genetic and epigenetic factors. Although it has been proposed that different genetic pathways exist for differentiated and undifferentiated carcinomas, the two histological subtypes of gastric cancer share some common genetic alterations. Currently, tumor histology and pathologic stage are the major prognostic variables used in the clinical practice for gastric cancer patients. However, it is known that tumors with similar morphology may differ in biological aggressiveness, prognosis and response to treatment. Molecular genetic analysis of gastric cancer revealed a number of associations of certain genetic changes with pathological features, tumor biological behavior and prognosis of gastric cancer patients, suggesting that these genetic abnormalities might play an important role in gastric tumorigenesis. Increasing evidence suggests that the molecular genetic changes could be helpful in the clinical setting, contributing to prognosis and management of patients. Regarding epigenetic events in gastric tumorigenesis, a number of methylating markers have been proposed for risk assessment, prognostic evaluation and as therapeutic targets. However, further research is required in order to systematically investigate the genetic changes in gastric cancer estimating also their usefulness in the clinical practice. A good understanding of the genetic changes underlying gastric carcinogenesis may provide new perspectives for prognosis and screening of high risk individuals. Some of the genetic alterations could definitely improve tumor classification and management of gastric cancer patients. Also, based on molecular data identified in gastric cancer novel therapeutics might help to improve the treatment of this disease.

DNA copy number profiles of gastric cancer precursor lesions

Background

Chromosomal instability (CIN) is the most prevalent type of genomic instability in gastric tumours, but its role in malignant transformation of the gastric mucosa is still obscure. In the present study, we set out to study whether two morphologically distinct categories of gastric cancer precursor lesions, i.e. intestinal-type and pyloric gland adenomas, would carry different patterns of DNA copy number changes, possibly reflecting distinct genetic pathways of gastric carcinogenesis in these two adenoma types.

Results

Using a 5K BAC array CGH platform, we showed that the most common aberrations shared by the 11 intestinal-type and 10 pyloric gland adenomas were gains of chromosomes 9 (29%), 11q (29%) and 20 (33%), and losses of chromosomes 13q (48%), 6(48%), 5(43%) and 10 (33%). The most frequent aberrations in intestinal-type gastric adenoma were gains on 11q, 9q and 8, and losses on chromosomes 5q, 6, 10 and 13, whereas in pyloric gland gastric adenomas these were gains on chromosome 20 and losses on 5q and 6. However, no significant differences were observed between the two adenoma types.

Conclusion

The results suggest that gains on chromosomes 8, 9q, 11q and 20, and losses on chromosomes 5q, 6, 10 and 13, likely represent early events in gastric carcinogenesis. The phenotypical entities, intestinal-type and pyloric gland adenomas, however, do not differ significantly (P = 0.8) at the level of DNA copy number changes.

Gene expression profiling in human gastric mucosa infected with Helicobacter pylori

Pathogenic mechanisms associated with Helicobacter pylori infection enhance susceptibility of the gastric epithelium to carcinogenic conversion. We have characterized the gene expression profiles of gastric biopsies from 69 French Caucasian patients, of which 43 (62%) were infected with H. pylori. The bacterium was detected in 27 of the 42 antral biopsies examined and in 16 of the 27 fundic biopsies. Infected biopsies were selected for the presence of chronic active gastritis, in absence of metaplasia and dysplasia of the gastric mucosa. Infected antral and fundic biopsies exhibited distinct transcriptional responses. Altered responses were linked with: (1) the extent of polymorphonuclear leukocyte infiltration, (2) bacterial density, and (3) the presence of the virulence factors vacA, babA2, and cagA. Robust modulation of transcripts associated with Toll-like receptors, signal transduction, the immune response, apoptosis, and the cell cycle was consistent with expected responses to Gram-negative bacterial infection. Altered expression of interferon-regulated genes (IFITM1, IRF4, STAT6), indicative of major histocompatibility complex (MHC) II-mediated and Th1-specific responses, as well as altered expression of GATA6, have previously been described in precancerous states. Upregulation of genes abundantly expressed in cancer tissues (UBD, CXCL13, LY96, MAPK8, MMP7, RANKL, CCL18) or in stem cells (IFITM1 and WFDC2) may reveal a molecular switch towards a premalignant state in infected tissues. Tissue microarray analysis of a large number of biopsies, which were either positive or negative for the cag-A virulence factor, when compared to each other and to noninfected controls, confirmed observed gene alterations at the protein level, for eight key transcripts. This study provides 'proof-of-principle' data for identifying molecular mechanisms driving H. pylori-associated carcinogenesis before morphological evidence of changes along the neoplastic progression pathway.

Identification of genes with correlated patterns of variations in DNA copy number and gene expression level in gastric cancer

To identify DNA copy number changes that had a direct influence on mRNA expression in gastric cancer, cDNA microarray-based comparative genomic hybridization (aCGH) and gene expression profiling were performed using 17 K cDNA microarrays. A set of 158 genes showing Pearson correlation coefficients over 0.6 between DNA copy number changes and mRNA expression level variations was selected. In an independent gene expression profiling of 60 tissue samples, the 158 genes were able to distinguish most of the normal and tumor tissues in an unsupervised hierarchical clustering, suggesting that the differential expression patterns displayed by this specific group of genes are most likely based on the gene copy number changes. Furthermore, 43 statistically significant (P<0.01) genes were selected that correctly distinguished all of the tissue samples. The copy number changes detected by aCGH can be verified by fluorescence in situ hybridization and real-time polymerase chain reaction. The selected genes include those that were previously identified as being tumor suppressors or deleted in various tumors, including GATA binding protein 4 (GATA4), monoamine oxidase A (MAOA), cyclin C (CCNC), and oncogenes including malignant fibrous histiocytoma amplified sequence 1 (MFHAS1/MASL1), high mobility group AT-hook 2 (HMGA2), PPAR binding protein (PPARBP), growth factor receptor-bound protein 7 (GRB7), and TBC1 (tre-2, BUB2, cdc16) domain family, member 1 (TBC1D1).

Numerical aberrations of chromosome 8 detected by conventional cytogenetics and fluorescence in situ hybridization in individuals from northern Brazil with gastric adenocarcinoma

Gastric cancer is the third most frequent type of neoplasia and the second most important cause of cancer-related death in the world. In northern Brazil, the state of Pará shows a high incidence of this disease and the capital ranks among cities with the highest incidence of stomach cancer in the world. To evaluate chromosomal aberrations implicated in gastric carcinogenesis, we analyzed 16 samples of gastric adenocarcinoma by fluorescence in situ hybridization using a chromosome 8 alpha-satellite probe and by direct chromosomal analysis techniques. All lesions were classified as at advanced stages according to the recommendations of the Union Internationale Contre le Cancer (UICC). Trisomy 8 was the main finding of this study, observed in all cases. There was no significant difference between chromosome 8 ploidy and localization, stage, or histological type of adenocarcinoma in our sample. The high incidence of alterations we found in chromosome 8 may be a regional characteristic, related to the high incidence of this neoplasm in Pará state and a strong influence of external factors, such as eating habits. This aberration may comprise a cytogenetic subgroup of this neoplasm. Additional investigations are necessary to confirm the involvement of chromosome 8 and to identify genes in this chromosome related to gastric carcinogenesis.

Subcellular and Functional Proteomic Analysis of the Cellular Responses Induced by Helicobacter pylori

Helicobacter pylori infection is a crucial factor in the pathogenesis of several digestive disorders, including peptic ulcers, chronic gastritis, and gastric cancer. Moreover H. pylori induces disease-specific protein expression in gastric epithelial cells. The aim of the present study was to characterize proteins differentially expressed in H. pylori-infected gastric epithelial AGS cells. An in vitro model was established using a multiplicity of infection of 100 and evaluating the effectiveness of H. pylori infection by functional analyses. Changes in protein patterns were identified using a proteomic approach consisting of two-dimensional fluorescence difference gel electrophoresis and mass spectrometry. The expression of many proteins was found to be altered, and 28 of these were identified and classified as protein synthesis- and folding-related proteins, cytoskeleton proteins, metabolic enzymes, transcription- and translation-related proteins, angiogenesis/metastasis-related proteins, cell communication/signal transduction-related proteins, or others (oxygen-regulated protein and oncoprotein). The expression profiles of eight of these proteins, laminin gamma-1 chain precursor, valosin-containing protein, heat shock 70-kDa protein, mitochondrial matrix protein P1, FK506-binding protein 4, T-complex protein 1, enolase alpha, and 14-3-3 beta were further examined in cancerous and paired surrounding normal tissues by immunoblot assay and immunohistochemical staining to identify molecular targets that may be involved in the pathogenesis of H. pylori-induced gastric diseases. On the basis of our results, valosin-containing protein, mitochondrial matrix protein P1, T-complex protein 1, enolase alpha, and 14-3-3 beta may play a crucial role in H. pylori-induced gastric carcinogenesis by mediating antiapoptotic and proliferative responses.

Gastric and intestinal phenotypic cell marker expressions in gastric differentiated-type carcinomas: association with E-cadherin expression and chromosomal changes

Gastric and intestinal phenotypic cell markers are widely expressed in gastric carcinomas, irrespective of their histological type. In the present study, the relations between the phenotypic marker expression of the tumour, histological findings, expression of cell adhesion molecules, and the chromosomal changes in gastric differentiated-type carcinomas were examined. The phenotypic marker expression of the tumour was determined by the combination of the expression of the human gastric mucin (HGM), MUC6, MUC2 and CD10, and was evaluated in comparison with the expression of cell adhesion molecules, such as E-cadherin and beta-catenin, and chromosomal changes by comparative genomic hybridization (CGH) in 34 gastric differentiated-type carcinomas. Tumours were classified into the gastric- (G-), gastric and intestinal mixed- (GI-), intestinal- (I-), or unclassified- (UC-) phenotype according to the immunopositivity of staining for HGM, MUC6, MUC2, and CD10. G-phenotype tumours were significantly associated with a higher incidence of differentiated-type tumours mixed with undifferentiated-type component, compared with GI- and I-phenotype tumours (88.9 vs 33.3%, P=0.0498 and 88.9 vs 42.9%, P=0.0397; respectively). HGM-positive tumours were significantly associated with a higher incidence of tumours with abnormal expression of E-cadherin, compared with HGM-negative tumours (66.7 vs 21.1%, P=0.0135). GI-phenotype tumours were significantly associated with a higher incidence of tumours with abnormal expression of E-cadherin, compared with I-phenotype tumours (77.8 vs 21.4%, P=0.0131). HGM-negative tumours were significantly associated with higher frequencies of the gains of 19q13.2 and 19q13.3, compared with HGM-positive tumours (57.9 vs 20.0%, P=0.0382 and 63.2 vs 13.3%, P=0.0051; respectively). MUC6-positive tumours were significantly associated with higher frequencies of the gains of 20q13.2, compared with MUC6-negative tumours (71.4 vs 30.0%, P=0.0349). MUC2-positive tumours were significantly associated with the gain of 19p13.3, compared with MUC2-negative tumours (41.2 vs 5.9%, P=0.0391). I-phenotype tumours were significantly associated with higher frequencies of gains of 5p15.2 and 13q33-34, compared with G-phenotype tumours (66.7 vs 0%, P=0.0481, each) and also associated with higher frequencies of gain of 7p21, compared with GI-phenotype tumours (66.7 vs 0%, P=0.0481). Our present results show that gastric differentiated-type carcinomas have different characteristics according to the phenotypic marker expression of the tumour in terms of histological findings, E-cadherin expression and pattern of chromosomal changes.

Exclusion of RUNX3 as a tumour-suppressor gene in early-onset gastric carcinomas

Recent studies claim a critical role for RUNX3 in gastric epithelial homeostasis. However, conflicting results exist regarding RUNX3 expression in the stomach and its potential role as a tumour-suppressor gene (TSG) in gastric carcinogenesis. Our aim was to evaluate the role of RUNX3 in early-onset gastric carcinomas (EOGCs). We analysed 41 EOGCs for RUNX3 aberrations using loss of heterozygosity (LOH), fluorescence in situ hybridization (FISH) and immunohistochemistry (IHC) analyses. LOH of markers flanking RUNX3 was relatively common, indicating that loss of the gene may play a role in gastric carcinogenesis. However, FISH analysis of selected cases and a panel of 14 gastric carcinoma-derived cell lines showed widespread presence of multiple copies of centromere 1. While RUNX3 copy numbers were generally equal to or fewer than those of centromere 1, at least two copies were present in almost all cells analysed. Accordingly, a subpopulation of tumour cells in 12/37 cases showed RUNX3 protein expression. However, expression was not detected in the adjacent nontumorous mucosa of any case. Together, these observations indicate that chromosome 1 aberrations occur frequently in EOGCs and are reflected in the LOH and IHC patterns found. Our findings refute a role for RUNX3 as a TSG in EOGCs.

Proteomic identification of differentially-expressed genes in human gastric carcinomas

Although genetic alterations in proto-oncogenes, tumor-suppressor genes, cell cycle regulators, and cell growth factors have been implicated in the process of human gastric carcinogenesis, the principle carcinogenic mechanisms are not fully understood. In this study, we used a proteomic approach to search for genes that may be involved in gastric carcinogenesis and that might serve as diagnostic markers. We identified nine proteins with increased expression and 13 proteins with decreased expression in gastric carcinomas. The two most notable groups included proteins involved in mitotic checkpoint (MAD1L1 and EB1) and mitochondrial functions (CLPP, COX5A, and ECH1). This suggested that there are links between dysfunctions in these processes and gastric carcinogenesis. We also observed the differential expression of HSP27 and CYR61 proteins in gastric carcinoma, whose expression is known to be altered in other types of tumors. Furthermore, the study identified proteins whose function in gastric carcinomas was previously unsuspected and that may serve as new molecular markers for gastric carcinomas. Importantly, immunohistochemical analyses confirmed that the levels of expression of MAD1L1, HSP27, and CYR61 were altered in gastric carcinoma tissues. Therefore, our study suggested not only that the proteins identified in this study can be useful diagnostic markers but also that a proteomics-based approach is useful for developing a more complete picture of the pathogenesis and function of gastric carcinomas.

Analysis by comparative genomic hybridization of gastric cancer with peritoneal dissemination and/or positive peritoneal cytology

Peritoneal metastasis is an important prognostic factor in cases of gastric cancer. Although studies on comparative genomic hybridization (CGH) in gastric cancer have been reported, there are few reports on the peritoneal metastasis (P) and peritoneal cytology (CY) factors in this cancer. In this study, we analyzed the chromosomal changes in the primary tumor with a combination of laser microdissection analysis and CGH in an attempt to detect the unknown abnormal chromosomal regions. We analyzed 34 primary tumors, including 13 primary tumors with peritoneal metastasis (P1) and/or positive peritoneal cytology (CY1) using a combination of laser microdissection and CGH. The minimal overlapping regions in gains were assigned to 5p14 (46.2%), 7q21.3 (61.5%), 7q31 (46.2%), 7q36 (46.2%), 8q23 (53.8%), 15q26 (46.2%), 20q12 (61.5%), 20q13.1 (53.8%), and 20q13.2 (53.8%) in primary tumors with P1 and/or CY1. The minimal regions of losses that occurred most frequently were 4q34-q35 (23.1%) and 22q11.2 (23.1%). There were significant differences in the minimal regions of 5p14 (P=0.033), 7q21.3 (P < 0.0001), 7q31 (P=0.013), 7q36 (P=0.033), and 22q11.2 (P=0.048) between primary tumors with and without P1 and/or CY1. In this study, gain/amplification of 5p14, 7q21.3, 7q31, and 7q36, and loss of 22q11.2 were significant in gastric cancer cases with peritoneal dissemination and/or positive peritoneal cytology.

Gene deregulation in gastric cancer

Despite its decreasing frequency in the Western world during recent decades, gastric cancer is still one of the leading causes of cancer-related deaths worldwide. Due to the oligosymptomatic course of early gastric cancer, most cases are diagnosed in the advanced stages of the disease. The curative potential of current standard treatment continues to be unsatisfactory, despite multimodal approaches involving surgery, chemotherapy and radiotherapy. Novel therapeutics including small molecules and monoclonal antibodies are being developed and have been partially introduced into clinical use in connection with neoplastic diseases such as chronic myeloid leukemia, non-Hodgkin's lymphoma and colorectal cancer. Thorough understanding of the changes in gene expression occurring during gastric carcinogenesis may help to develop targeted therapies and improve the treatment of this disease. Novel molecular biology techniques have generated a wealth of data on up- and down-regulation, activation and inhibition of specific pathways in gastric cancer. Here, we provide an overview of the different aspects of aberrant gene expression patterns in gastric cancer.

Differential expression of the eukaryotic release factor 3 (eRF3/GSPT1) according to gastric cancer histological types

BACKGROUND

There are now several lines of evidence to suggest that protein synthesis and translation factors are involved in the regulation of cell proliferation and cancer development.

AIMS

To investigate gene expression patterns of eukaryotic releasing factor 3 (eRF3) in gastric cancer.

METHODS

RNA was prepared from 25 gastric tumour biopsies and adjacent non-neoplastic mucosa. Real time TaqMan reverse transcription polymerase chain reaction (RT-PCR) was performed to measure the relative gene expression levels. DNA was isolated from tumour and normal tissues and gene dosage was determined by a quantitative real time PCR using SYBR Green dye.

RESULTS

Different histological types of gastric tumours were analysed and nine of the 25 tumours revealed eRF3/GSPT1 overexpression; moreover, eight of the 12 intestinal type carcinomas analysed overexpressed the gene, whereas eRF3/GSPT1 was overexpressed in only one of the 10 diffuse type carcinomas (Kruskal-Wallis Test; p < 0.05). No correlation was found between ploidy and transcript expression levels of eRF3/GSPT1. Overexpression of eRF3/GSPT1 was not associated with increased translation rates because the upregulation of eRF3/GSPT1 did not correlate with increased eRF1 levels.

CONCLUSIONS

Overexpression of eRF3/GSPT1 in intestinal type gastric tumours may lead to an increase in the translation efficiency of specific oncogenic transcripts. Alternatively, eRF3/GSPT1 may be involved in tumorigenesis as a result of its non-translational roles, namely (dis)regulating the cell cycle, apoptosis, or transcription.

Establishment and characterization of a human gastric carcinoma cell line TMC-1

Established cancer cell lines are useful in the study of various cancers. We established a human gastric carcinoma cell line TMC-1 derived from the lymph node of a moderately differentiated adenocarcinoma of the stomach. TMC-1 cells grew in vitro as a mixture of attached and suspension cells, and exhibited spindle or ovoid morphology. They had a population doubling time of 15 h, a plating efficiency of 61%, formed colonies in semisolid agar, secreted the tumor marker CA 19-9, and were tumorigenic in athymic nude mice. The cells expressed E-cadherin and beta-catenin. The karyotypic analysis demonstrated hyperdiploid features with a modal chromosome of 53. The cell had the deletion at chromosome 18q and gains at chromosome 2p13-25, 5p15, 5q21-35, 7, 8q24, 9q, 11, 12p, 14q24-32 and 20. Analysis by fluorescence in situ hybridization showed the deletion at 7qtel and duplication at 7q11.2 at the rearranged chromosome 7. Growth of TMC-1 cells was inhibited by 27-32% by interferon-alpha (2,000 U/ml) and by interferon-gamma with an IC50 of 125 U/ml. The cell line is tumorigenic in vivo, and its growth is moderately inhibited by interferon-alpha and interferon-gamma. It can be used to develop new modalities of human gastric cancer treatment.

Cyclin D3 Immunoreactivity Is an Independent Predictor of Survival in Laryngeal Squamous Cell Carcinoma

Purpose: To analyze the prevalence and clinical relevance of cyclin D3 abnormalities in laryngeal squamous cell carcinoma (LSCC).

Experimental Design: Cyclin D3 immunoreactivity was evaluated in 223 formalin-fixed and paraffin-embedded samples of LSCC patients with a mean follow-up of 62.8 ± 43.2 months. The occurrence of cyclin D3 extra signals was analyzed by fluorescence in situ hybridization in 47 randomly selected cases collected in a tissue microarray. Cyclin D1 immunoreactivity had been previously investigated in 133 cases.

Results: Cyclin D3 immunoreactivity and gene extra signals were found in 39.5% and 42.6% of the cases, respectively, and the concordance between immunohistochemical and fluorescence in situ hybridization results was 70.2% (P = 0.0085). Cyclin D3 immunoreactivity was significantly associated with a high risk of death. Multivariate analysis showed that high tumor grade, exophytic/ulcerating tumor type, low performance status, and cyclin D3 immunoreactivity were the only independent predictors of poor overall survival. In the 133 cases analyzed for both cyclin D1 and cyclin D3, patients with cyclin D1+/cyclin D3+ tumors experienced the worst prognosis, patients with cyclin D1−/cyclin D3− exhibited the most prolonged survival, and with cyclin D1−/cyclin D3+ or cyclin D1+/cyclin D3− tumors an intermediate course was associated.

Conclusions: Our data suggest that cyclin D3 immunoreactivity, possibly due to the occurrence of gene extra copies, may represent an adjunct in LSCC patients' prognostication and contribute to identify D-type cyclins as potential targets of newly developed therapies.

Helicobacter pylori infection activates FOS and stress-response genes and alters expression of genes in gastric cancer-specific loci

We studied human gene expression changes caused by Helicobacter pylori infection by using an in vitro model and 13k cDNA microarrays. A gastric cancer cell line was infected with H. pylori strain NCTC 11637. H. pylori infection was found to induce differential expression of genes in chromosomal locations known to contain frequent chromosomal aberrations and gene mutations specific to gastric cancer. Based on the results of time series experiments, the primary transcription target of the infection seemed to be FOS, the expression of which significantly increased after H. pylori infection. H. pylori infection also activated transcription of several stress-response genes. H. pylori infection may predispose the host cell to DNA damage in the chromosomal locations specific to gastric cancer by activating transcription and promoting histone removal from these sites, thus exposing its target DNA to mutations.

Reduced expression of cell cycle regulator p18(INK4C) in human hepatocellular carcinoma

Cyclins, cyclin-dependent kinases (Cdks), and Cdk inhibitors (CdkIs) are frequently altered in human cancer. p18INK4C, a member of the INK4 family of CdkIs, is a potential tumor-suppressor gene product. However, the expression of p18INK4C in hepatocellular carcinoma (HCC) remains unknown. The aim of this study was to examine the expression of p18INK4C in various liver diseases including HCC and to assess its clinical significance in HCC. To that end, we examined the expression of p18INK4C by immunohistochemistry in various liver diseases, including 51 HCCs, and also studied the relationship between p18INK4C expression, the phosphorylation of retinoblastoma protein (pRb), and the activity level of Cdk4 and Cdk6. Immunohistochemical analysis revealed the frequent loss of p18INK4C expression in HCC, especially in poorly differentiated HCC. The loss of p18INK4C expression was shown to be associated with a poor prognosis compared with that associated with p18INK4C- positivity. Further, the kinase activity of Cdk4 was found to be higher in p18INK4C-negative HCCs than in p18INK4C- positive HCCs. However, the level of Cdk6 activity was similar in the 2 groups of HCCs. In p18INK4C- positive HCCs, p18INK4C dominantly interacted with Cdk4 rather than with Cdk6. pRb phosphorylated at serine(Ser) 780 was detected more frequently in p18INK4C - negative than in p18INK4C - positive HCCs. In conclusion, the loss of p18INK4C expression may play a role in the differentiation and development of HCC through the up-regulation of Cdk4 activity.

Molecular biology of sporadic gastric cancer: prognostic indicators and novel therapeutic approaches

Both the availability of multiple treatment modalities and novel therapeutic targets make the correct prognostic stratification and the identification of truly predictive factors an issue of major debate in gastric cancer. Along with "classic" prognostic factors such as those related to the diffusion of the tumour at diagnosis (i.e., depth of gastric wall infiltration, locoregional lymph nodes or distant metastases) or those concerning the pathologic characteristics of the tumour, other, innovative, factors should be considered if a better definition of the characteristics of the tumour is to be given. These biological factors are often derived from the genetic process, which is thought to represent a crucial step to gastric cancer (DNA copy number changes, microsatellite instability, thymidilate synthase, E-cadherin, beta-catenin, mucin antigen, p53, c-erb B-2, COX-2, matrix metalloproteinases, VEGFR and EGFR). Some of those putative prognostic indicators can also be considered predictive of response to therapy as they are a molecular target either to chemotherapeutics (i.e., thymidilate synthase that is targeted by 5FU) or to a new class of antineoplastic molecules (i.e., c-erb B-2 targeted by trastuzumab, COX-2 by NSAIDs, matrix metalloproteinases, EGFR and VEGFR by specific inhibitors).

Alterations of chromosomal copy number during progression of diffuse-type gastric carcinomas: metaphase- and array-based comparative genomic hybridization analyses of multiple samples from individual tumours

The application of comparative genomic hybridization (CGH) has led to the rapid accumulation of cytogenetic information on gastric carcinoma (GC), but there is little information on the time sequence of cytogenetic changes. In the present study, degenerate oligonucleotide-primed polymerase chain reaction (DOP-PCR) and CGH were applied to multiple samples microdissected from 19 diffuse-type GCs including eight early cancers. Recurrent gains were detected at 8q, 3q, 7q, and 8p, and loss at 17p (in more than 50% of the cancers), the frequencies of which were fairly similar between the samples with (SIG) and those without (POR) abundant signet ring cells. Earlier stemline changes (8q+, 8p+, 1q+, 17p-, etc), with breakpoints that were common to all the samples, were discriminated from later sideline changes (2q+, 11q+, 17q-, 21q-, etc) in individual tumours. The changes were generally common to early and advanced cancers, except for 7p+, 15q+, 3p-, and 18q-, which were largely sideline changes and more frequently detected in advanced cancers (p<0.05). Because the samples with 7p+ had a greater number of copy-number changes than those without 7p+ (p<0.01), 7p+ may play a role in tumour progression by acceleration of chromosomal instability. Fifteen different chromosomal loci with amplification were detected in ten cases, mostly as sideline changes in advanced cancers. By microarray-based CGH, KRAS, MDM2, and FGFR2 were confirmed in the amplicons at 12p, 12q, and 10q, and FES at 15q26, for the first time in GC. These results support the notion that SIG and POR are of a genetically single lineage in both early and advanced diffuse-type GC and that the majority of advanced cancers derive from early cancers through the accumulation of various sideline changes in addition to stemline changes.

Genetic lineage of poorly differentiated gastric carcinoma with a tubular component analysed by comparative genomic hybridization

Analysis of cell lineage is based on the use of genetic markers inherent to the lineage to be analysed. The breakpoints of unbalanced translocations, and the pattern of chromosomal loss/gain determined by comparative genomic hybridization (CGH), have been previously used to demonstrate lineages in diffuse-type gastric carcinoma. Signet ring cell carcinoma was shown to progress to poorly differentiated adenocarcinoma, and early diffuse-type gastric carcinoma to advanced diffuse-type gastric carcinoma. The present study focuses on poorly differentiated adenocarcinoma with a tubular component to clarify its derivation. CGH and array CGH were applied to DNA extracted from multiple portions of individual tumours and amplified by degenerate oligonucleotide-primed (DOP) PCR and the changes common to the samples in each tumour (stemline changes) were compared between the tumours with and those without a tubular component. Within individual tumours, the samples from the tubular component and those from the other components had common stemline changes and a very similar frequency pattern of chromosomal changes, indicating their common derivation. Frequent stemline changes were 8q+, 7p+, 3q+, 20q+, and 10p+, and these were different from those in the tumours without a tubular component. It was noticed that there were two subgroups in the tumours with a tubular component: one with 5p+, 6p+, 7p+, and 10p+, and the other without these changes. The latter had cytogenetic and clinicopathological features similar to those of the tumours without a tubular component. Analysis of the clonal evolution process by constructing dendrograms for each tumour gave results consistent with the notion that the latter subgroup may derive from signet ring cell carcinoma and the former from tubular adenocarcinoma.