Loss of heterozygosity involving the APC and MCC genetic loci occurs in the majority of human esophageal cancers

Family History of Colorectal or Esophageal Cancer in Barrett's Esophagus and Potentially Explanatory Genetic Variants

We aimed to estimate the effects of a family history of colorectal cancer (CRC) or esophageal cancer on the risk of Barrett's esophagus (BE) and identify variants in cancer genes that may explain the association.

Wnt/β-Catenin Signaling in Oral Carcinogenesis

Oral carcinogenesis is a complex and multifactorial process that involves cumulative genetic and molecular alterations, leading to uncontrolled cell proliferation, impaired DNA repair and defective cell death. At the early stages, the onset of potentially malignant lesions in the oral mucosa, or oral dysplasia, is associated with higher rates of malignant progression towards carcinoma in situ and invasive carcinoma. Efforts have been made to get insights about signaling pathways that are deregulated in oral dysplasia, as these could be translated into novel markers and might represent promising therapeutic targets. In this context, recent evidence underscored the relevance of the Wnt/β-catenin signaling pathway in oral dysplasia, as this pathway is progressively "switched on" through the different grades of dysplasia (mild, moderate and severe dysplasia), with the consequent nuclear translocation of β-catenin and expression of target genes associated with the maintenance of representative traits of oral dysplasia, namely cell proliferation and viability. Intriguingly, recent studies provide an unanticipated connection between active β-catenin signaling and deregulated endosome trafficking in oral dysplasia, highlighting the relevance of endocytic components in oral carcinogenesis. This review summarizes evidence about the role of the Wnt/β-catenin signaling pathway and the underlying mechanisms that account for its aberrant activation in oral carcinogenesis.

Specific DNA methylation markers in the diagnosis and prognosis of esophageal cancer

The early diagnosis and accurate prognosis prediction of esophageal cancer is an essential part of improving survival. However, these diseases lack effective and specific markers. A total of 1,744 samples of HumanMethylation450 data were integrated to identify and validate specific methylation markers for esophageal adenocarcinoma (EAC) and esophageal squamous cell carcinoma (ESCC) as well as for Barrett's esophagus (BE) using The Cancer Genome Atlas and the Gene Expression Omnibus. The diagnostic and prognostic methylation classifiers were constructed by moderated t-statistics and the least absolute shrinkage and selection operator method. The diagnostic methylation classifier using 12 CpG sites was constructed in training set (377 samples) that could effectively discriminate samples of BE, EAC, and ESCC from normal tissue (AUC = 0.992), which achieved highly predictive ability in both internal (187 samples, AUC = 0.990) and external validation (184 samples, AUC = 0.978). The prognostic methylation classifier with 3 CpG and 2 CpG sites for EAC and ESCC respectively, could accurately estimate the prognosis of an individual patient and improved the predictive ability of the tumor node metastasis staging system. Overall, our study systematically analyzed large-scale methylation data and provided promising markers for the diagnosis and prognosis of esophageal cancer.

Modeling Wnt signaling by CRISPR-Cas9 genome editing recapitulates neoplasia in human Barrett epithelial organoids

Primary organoid cultures generated from patient biopsies comprise a novel improved platform for disease modeling, being genetically stable and closely recapitulating in vivo scenarios. Barrett esophagus (BE) is the major risk factor for esophageal adenocarcinoma. There has been a dearth of long-term in vitro expansion models of BE neoplastic transformation. We generated a long-term virus-free organoid expansion model of BE neoplasia from patient biopsies. Both wild-type and paired APC-knockout (APC^KO) BE organoids genome-edited by CRISPR-Cas9 showed characteristic goblet cell differentiation. Autonomous Wnt activation was confirmed in APC^KO organoids by overexpression of Wnt target genes and nuclear-translocated β-catenin expression after withdrawal of Wnt-3A and R-spondin-1. Wnt-activated organoids demonstrated histologic atypia, higher proliferative and replicative activity, reduced apoptosis, and prolonged culturability. Wnt-activated organoids also showed sustained protrusive migration ability accompanied by disrupted basement membrane reorganization and integrity. This CRISPR-Cas9 editing human-derived organoid model recapitulates the critical role of aberrant Wnt/β-catenin signaling activation in BE neoplastic transformation. This system can be used to study other 'driver' pathway alterations in BE-associated neoplasia, avoiding signaling noise present in immortalized or cancer-derived cell lines.

Modeling Wnt signaling by CRISPR-Cas9 genome editing recapitulates neoplasia in human Barrett epithelial organoids

Primary organoid cultures generated from patient biopsies comprise a novel improved platform for disease modeling, being genetically stable and closely recapitulating in vivo scenarios. Barrett esophagus (BE) is the major risk factor for esophageal adenocarcinoma. There has been a dearth of long-term in vitro expansion models of BE neoplastic transformation. We generated a long-term virus-free organoid expansion model of BE neoplasia from patient biopsies. Both wild-type and paired APC-knockout (APC^KO) BE organoids genome-edited by CRISPR-Cas9 showed characteristic goblet cell differentiation. Autonomous Wnt activation was confirmed in APC^KO organoids by overexpression of Wnt target genes and nuclear-translocated β-catenin expression after withdrawal of Wnt-3A and R-spondin-1. Wnt-activated organoids demonstrated histologic atypia, higher proliferative and replicative activity, reduced apoptosis, and prolonged culturability. Wnt-activated organoids also showed sustained protrusive migration ability accompanied by disrupted basement membrane reorganization and integrity. This CRISPR-Cas9 editing human-derived organoid model recapitulates the critical role of aberrant Wnt/β-catenin signaling activation in BE neoplastic transformation. This system can be used to study other 'driver' pathway alterations in BE-associated neoplasia, avoiding signaling noise present in immortalized or cancer-derived cell lines.

Genetic Events Responsible for Colorectal Tumorigenesis: Achievements and Challenges

Colorectal carcinogenesis is a multistep process that is accompanied by accumulation of changes in proto-oncogenes and tumor-suppressor genes. APC/MCC, RAS, DCC, p53 mutations and/or allelic losses, hyperexpression of c-MYC and RB genes, as well as other genomic alterations appear at characteristic stages of tumor development and are observed in most neoplasms. However, consideration of each of these abnormalities leaves many unanswered questions. The striking data on recurrent amplification of the RB tumor-suppressor gene as well as suppressive activities of protein kinase C and activated RAS genes, at least in some colon carcinoma cell lines, suggest the unusual effects of some signalling pathways in colonic epithelial cells. The results obtained to date indicate that distinct sets of genetic changes may underlie the development of colorectal tumors.

Inducible Nitric Oxide Synthase in the Carcinogenesis of Gastrointestinal Cancers

SIGNIFICANCE

Gastrointestinal (GI) cancer taken together constitutes one of the most common cancers worldwide with a broad range of etiological mechanisms. In this review, we have examined the impact of nitric oxide (NO) on the etiology of colon, colorectal, gastric, esophageal, and liver cancers. Recent Advances: Despite differences in etiology, initiation, and progression, chronic inflammation has been shown to be a common element within these cancers showing interactions of numerous pathways. NO generated at the inflammatory site contributes to the initiation and progression of disease. The amount of NO generated, time, and site vary and are an important determinant of the biological effects initiated. Among the nitric oxide synthase enzymes, the inducible isoform has the most diverse range, participating in numerous carcinogenic processes. There is emerging evidence showing that inducible nitric oxide synthase (NOS2) plays a central role in the process of tumor initiation and/or development.

CRITICAL ISSUES

Redox inflammation through NOS2 and cyclooxygenase-2 participates in driving the mechanisms of initiation and progression in GI cancers.

FUTURE DIRECTIONS

Understanding the underlying mechanism involved in NOS2 activation can provide new insights into important prevention and treatment strategies. Antioxid. Redox Signal. 26, 1059-1077.

Decreased expression of CDH1 or CTNNB1 affects poor prognosis of patients with esophageal cancer

Background

E-cadherin/CDH1 is one of the proteins involved in cell adhesion, and it is known that decreased expression of E-cadherin induces lymph node metastasis in esophageal cancer. Beta catenin/CTNNB1, which is an important component of the Wnt signaling pathway, binds to E-cadherin at the cell membrane, where the complex of these two proteins functions in the stabilization of cell adhesion. However, its role in the pathogenesis of esophageal cancer is still unknown.

Methods

This study included 86 patients with esophageal cancer who underwent surgery between 1998 and 2007. The expression of the E-cadherin/CDH1 gene product (E-cadherin/CDH1) and that of the beta catenin/CTNNB1 protein in the cell membrane were analyzed by immunohistochemistry. We examined the correlations among CDH1 or CTNNB1 expression, clinicopathological factors, and the prognosis of patients with ESCC.

Results

CDH1 and CTNNB1 were expressed in 52.3 % (45/86) and 36.0 % (31/86) of tumor samples, respectively. Both CDH1 and CTNNB1 were co-expressed in 22.1 % (19/86) of esophageal cancer tissues. CDH1 expression correlated with the p-stage (stages I–II vs stages III–IV, p = 0.032), T factor (T1–2 vs T3–4, p = 0.0088), and lymphatic invasion (p = 0.019). However, CDH1 expression did not correlate with the N factor or the blood vessel invasion. CTNNB1 expression correlated with the T factor (T1–2 vs T3–4, p = 0.0015), p-stage (stages I–II vs stages III–IV, p = 0.030), and lymphatic invasion (p = 0.007). The CDH1(+)/CTNNB1(+) phenotype was inversely correlated with the T factor, N factor, p-stage, lymphatic invasion, and blood vessel invasion. Furthermore, patients whose tumors were double-positive for CDH1 and CTNNB1 had a significantly higher survival rate than those whose tumors were negative for CDH1 or CTNNB1 (log-rank test, p = 0.0192). The T factor and N factor had a strong negative correlation with double-positive tumors. These were both independent prognostic factors, as was the double-positive phenotype. A univariate analysis indicated that the T factor, the N factor, and CDH1 and CTNNB1 co-expression were significant variables that predicted survival (hazard ratio, 2.387; 95 % confidence interval, 1.115–5.102; p = 0.025).

Conclusions

Decreased expression of CDH1 or CTNNB1 in the cell membranes of cancer cells is associated with poor survival of patients with esophageal cancer.

Nuclear expression of TCF4/TCF7L2 is correlated with poor prognosis in patients with esophageal squamous cell carcinoma

The prognosis for patients with esophageal cancer remains poor. Therefore, the identification of novel target molecules for the treatment of esophageal cancer is necessary. Here, we investigated the clinicopathological significance of transcription factor 4/transcription factor 7-like 2 (TCF4/TCF7L2) in resectable esophageal squamous cell carcinoma (ESCC), because TCF4/TCF7L2 expression has not been studied in esophageal cancer previously.

This study included 79 patients with esophageal cancer who underwent surgery between 1998 and 2005. The expression of the TCF4/TCF7L2 protein in the nucleus of esophageal cancer cells was analyzed using immunohistochemistry. We examined the correlation between TCF4/TCF7L2 expression, clinicopathological factors, and prognosis in patients with ESCC.

TCF4/TCF7L2 was expressed in 57 % (45/79) of patients. TCF4/TCF7L2 expression was correlated with T factor (T1 vs. T2-4, p = 0.001), stage (I vs. II-IV, p =0.0058), Ly factor (p =0.038), and V factor (p =0.038) and did not correlate with age, gender or N factor. Furthermore, patients who were positive for TCF4/TCF7L2 had a significantly lower survival rate than those who were negative for TCF4/TCF7L2 (log-rank test, p = 0.0040). TCF4/TCF7L2 expression significantly affected the survival of patients with ESCC. Positive expression of TCF4/TCF7L2 was correlated with a poor prognosis after a curative operation in patients with ESCC.

GADD45A expression is correlated with patient prognosis in esophageal cancer

The prognosis of patients with esophageal cancer remains poor, and the tumor-node-metastasis classification system is not sufficient for predicting patient prognoses. Therefore, the identification of novel predictive markers for esophageal cancer is required. The present study investigated the clinicopathological significance of growth arrest and DNA damage-inducible 45α (GADD45A) and p53 in resectable esophageal squamous cell carcinoma (ESCC). The study consisted of 62 patients with esophageal cancer who underwent surgery between 2001 and 2007. The expression of the GADD45A gene product (GADD45A) and the p53 protein was analyzed by immunohistochemistry. The correlations among GADD45A expression, clinicopathological factors and prognosis were then analyzed in the patients with ESCC. GADD45A and p53 were expressed in 56.5% (35/62) and 48.4% (30/62) of patients, respectively. The expression of GADD45A did not show a marked correlation with that of p53. However, GADD45A expression correlated with pathological stage (stage 0-I vs. stages II-IV; P=0.014) and did not correlate with the tumor (T) or node (N) status. Furthermore, patients who were positive for GADD45A exhibited a significantly higher survival rate than those who were negative for GADD45A (log-rank test, P=0.009). Multivariate analysis indicated that T status, N status and GADD45A expression were significant variables predicting survival (hazard ratio, 2.486; 95% confidence interval, 1.168-5.290; P=0.018). Overall, GADD45A expression significantly affected the survival of patients with ESCC, and the reduced expression of GADD45A was correlated with a poor prognosis following curative surgery in these patients.

β-catenin in oral cancer: an update on current knowledge

β-Catenin is a multiple function protein. These functions derive from its interactions with other cell proteins, both on the cell membrane, in the cytoplasm and in the nucleus. β-Catenin forms a complex with the adhesion molecule E-cadherin, promoting cell-cell adhesion and thereby preventing the cell dissociation that is required for cancer invasion and progression mechanisms. There is also a dynamic pool of cytoplasmic β-catenin that serves as connection between the extracellular microenvironment and the nucleus. Cytoplasmic β-catenin acts as a transcription factor for the nucleus in the canonical Wnt pathway, activating the transcription of various genes. Structural or functional alterations of β-catenin can promote cancer progression. This review addresses the current knowledge on the implications of β-catenin in the development of oral cancer.

None-endoscopic Screening for Esophageal Squamous Cell Carcinoma- A Review

Esophageal cancer (EC) is the eighth most common cancer and sixth most frequent cause of cancer mortality worldwide. Esophageal squamous cell carcinoma (ESCC) is the most common type of EC. ESCC develops by progression from premalignant lesions, which are called esophageal squamous dysplasia (ESD). Prevention is the most effective strategy for controlling this disease. Generally, two methods may be defined for ESCC prevention. The aim of the first preventive method is to prevent the initiation of ESD by avoiding the known risk factors, or primary prevention. Secondary prevention focuses on detection of the disease in its early curable stage, thus preventing its progression into advanced stages. Endoscopy with iodine staining and biopsy is the diagnostic choice for ESD. However it is invasive and expensive, and not accepted by asymptomatic ESD cases. Therefore, it is necessary to find a non-endoscopic screening method. Despite the large number of studies conducted worldwide, no approved method has been developed for ESCC screening. Regarding the multi-factorial nature of ESCC, it is proposed that the use of a combination of various criteria, such as cytological examination, risk factors, genetic alteration, and molecular markers may result in the development of a comprehensive and effective ESCC screening program.

Non-Invasive Detection of Esophageal Cancer using Genetic Changes in Circulating Cell-Free DNA

Cell free DNA (cfDNA) is a genetic biomarker that is present in serum or plasma in high concentration in many types of cancer. Identification of circulating cancer related DNA molecules in serum or plasma is a non-invasive tool for early diagnosis and prognosis in many cancer patients. For this review, study selection and data extraction were performed by the authors. Detection of point mutations, microsatellite alterations, DNA hypermethylations and losses of heterozygosity in circulating cell free DNA have been characterized in esophagus cancer. Application of circulating cell free DNA as a biomarker, provide the best opportunity for constructing non-invasive tests for early detection, prognosis and management of cancer patients, after therapy in many types of cancer.

The pathogenesis of Barrett's metaplasia and the progression to esophageal adenocarcinoma

The most important risk factor for the development of Barrett's esophagus is the reflux of both gastric and duodenal contents into the esophagus. The reason why Barrett's metaplasia develops only in a minority of patients suffering from gastroesophageal reflux disease remains unknown.The exact mechanism behind the transition of normal squamous epithelium into specialized columnar epithelium is also unclear. It is likely that stem cells are involved in this metaplastic change, as they are the only permanent residents of the epithelium. Several tumorigenic steps that lead to the underlying genetic instability, which is indispensable in the progression from columnar metaplasia to esophageal adenocarcinoma have been described. This review outlines the process of pathogenesis of Barrett's metaplasia and its progression to esophageal adenocarcinoma.

Vascular endothelial growth factor C (VEGF-C) in esophageal cancer correlates with lymph node metastasis and poor patient prognosis

Background

The diagnosis of lymph node metastasis in esophageal cancer by the presence and number of metastatic lymph nodes is an extremely important prognostic factor. In addition, the indication of non-surgical therapy is gaining more attention. Vascular endothelial growth factor C (VEGF-C) is potentially lymphangiogenic and selectively induces hyperplasia of the lymphatic vasculature. In this study, we investigated the expression of VEGF-C and whether it correlated with various clinico-pathologic findings.

Methods

KYSE series of esophageal cancer cell lines and 106 patients with primary esophageal squamous cell carcinomas who had undergone radical esophagectomy were analyzed. VEGF-C mRNA expression was determined by quantitative RT-PCR.

Results

High expression of VEGF-C was detected in most of the KYSE cell lines, especially KYSE410, yet, in an esophageal normal epithelium cell line, Het-1A, VEGF-C was not detected. In the clinical specimen, the expression of VEGF-C in the cancerous tissue was higher than in the corresponding noncancerous esophageal mucosa (p = 0.026). The expression of VEGF-C was found to be higher in Stage2B-4A tumors than in Stage0-2A tumors (p = 0.049). When the patients were divided into two groups according to their expression levels of VEGF-C (a group of 53 cases with high expression and a group of 53 cases with low expression), the patients with high VEGF-C expression had significantly shorter survival after surgery than the patients with low expression (p = 0.0065). Although univariate analysis showed that high expression of VEGF-C was a statistically significant prognostic factor, this was not shown in multivariate analysis. In the subgroup of patients with Tis and T1 tumors, the expression of VEGF-C was higher in N1 tumors than in N0 tumors (p = 0.029). The survival rate of patients from the high expression group (n = 10) was lower than that in the low expression group (n = 11), and all the patients in the low VEGF-C expression group survived.

Conclusions

The expression of VEGF-C correlates with lymph node metastasis and poor prognosis. In patients with Tis and T1 esophageal tumors, the expression of VEGF-C may be a good diagnostic factor for determining metastasis of the lymph node.

Cancer models, genomic instability and somatic cellular Darwinian evolution

The biology of cancer is critically reviewed and evidence adduced that its development can be modelled as a somatic cellular Darwinian evolutionary process. The evidence for involvement of genomic instability (GI) is also reviewed. A variety of quasi-mechanistic models of carcinogenesis are reviewed, all based on this somatic Darwinian evolutionary hypothesis; in particular, the multi-stage model of Armitage and Doll (Br. J. Cancer 1954:8;1-12), the two-mutation model of Moolgavkar, Venzon, and Knudson (MVK) (Math. Biosci. 1979:47;55-77), the generalized MVK model of Little (Biometrics 1995:51;1278-1291) and various generalizations of these incorporating effects of GI (Little and Wright Math. Biosci. 2003:183;111-134; Little et al. J. Theoret. Biol. 2008:254;229-238).

Genome-wide analysis of genetic alterations in Barrett's adenocarcinoma using single nucleotide polymorphism arrays

We performed genome-wide analysis of copy-number changes and loss of heterozygosity (LOH) in Barrett's esophageal adenocarcinoma by single nucleotide polymorphism (SNP) microarrays to identify associated genomic alterations. DNA from 27 esophageal adenocarcinomas and 14 matching normal tissues was subjected to SNP microarrays. The data were analyzed using dChipSNP software. Copy-number changes occurring in at least 25% of the cases and LOH occurring in at least 19% were regarded as relevant changes. As a validation, fluorescence in situ hybridization (FISH) of 8q24.21 (CMYC) and 8p23.1 (SOX7) was performed. Previously described genomic alterations in esophageal adenocarcinomas could be confirmed by SNP microarrays, such as amplification on 8q (CMYC, confirmed by FISH) and 20q13 or deletion/LOH on 3p (FHIT) and 9p (CDKN2A). Moreover, frequent gains were detected on 2p23.3, 7q11.22, 13q31.1, 14q32.31, 17q23.2 and 20q13.2 harboring several novel candidate genes. The highest copy numbers were seen on 8p23.1, the location of SOX7, which could be demonstrated to be involved in amplification by FISH. A nuclear overexpression of the transcription factor SOX7 could be detected by immunohistochemistry in two amplified tumors. Copy-number losses were seen on 18q21.32 and 20p11.21, harboring interesting candidate genes, such as CDH20 and CST4. Finally, a novel LOH region could be identified on 6p in at least 19% of the cases. In conclusion, SNP microarrays are a valuable tool to detect DNA copy-number changes and LOH at a high resolution. Using this technique, we identified several novel genes and DNA regions associated with esophageal adenocarcinoma.

Qualitative analysis of Adenomatous Polyposis Coli promoter: hypermethylation, engagement and effects on survival of patients with esophageal cancer in a high risk region of the world, a potential molecular marker

Background

Squamous cell carcinoma of esophagus (SCCE) occurs at a high incidence rate in certain parts of the world. This feature necessitates that different aspects of the disease and in particular genetic characteristics be investigated in such regions. In addition, such investigations might lead to achievement of molecular markers helpful for early detection, successful treatment and follow up of the disease. Adenomatous Polyposis Coli (APC) promoter hypermethylation has been shown to be a suitable marker for both serum and solid tumors of adenocarcinoma of esophagus. We investigated the status of APC promoter hypermethylation in Iranian patients, compared the results with the former studies, and evaluated its applicability as a candidate molecular marker by examining association between survival of SCCE patients and APC promoter methylation.

Methods

For evaluating the status of APC promoter hypermethylation and its association with SCCE, a qualitative methylation specific PCR (MSP) was used. DNA was extracted and digested with an appropriate restriction enzyme, treated with sodium bisulfite in agarose beads and amplified in two-step PCR reaction by applying either methylated or unmethylated promoter specific primers. Universally methylated DNA and methylase treated blood DNA of healthy donors were used as positive controls as well. Survival of patients was followed up for two years after treatment and survival rate of patients with methylated APC promoter was compared with that of unmethylated patients.

Results

Assessment of APC promoter methylation revealed that normal tissues were unmethylated, while twenty out of forty five (44.4%) tumor tissues were hypermethylated either in one or both alleles of APC. Among the tissues in which methylation was detected, seven were hypermethylated in both alleles while the other thirteen were hypermethylated in one of the two alleles of APC. Analyzing two-year survival rate of patients with respect to promoter hypermethylation showed a lower rate of survival for patients with methylated APC promoter following their treatment. Further investigation into the association between promoter hypermethylation and tumor differentiation status indicated that patients with well differentiated tumors were more likely to develop promoter hypermethylation.

Conclusion

Observing similar level of APC promoter hypermethylation in patients with SCCE in this high risk region and comparing it with other parts of the world could support the hypothesis that a common molecular mechanism might be involved in tumorigenesis of SCCE. In addition, the higher rate of two-year survival for patients with unmethylated APC promoter as well as its relationship with tumor differentiation would suggest that this tumor suppressor could be an appropriate candidate molecular marker for evaluating tumor malignancy and predicting survival of patients subsequent to treatment.

Loss of heterozygosity of the APC gene in oral squamous cell carcinoma

The aim of this study was to investigate loss of heterozygosity (LOH) of the APC tumor suppressor gene loci, using restriction fragment length polymorphism-polymerase chain reaction (RFLP-PCR) in 40 cases of oral squamous cell carcinoma (OSCC). Observed informativity was 72.5% for APC exon 11 and 82.5% for APC exon 15. LOH at APC exon 11 was observed in 2 (6.9%) of 29 informative cases, and no LOH was observed for APC exon 15. Our results suggest that inactivation of the APC gene plays a minor role in the carcinogenesis of OSCC.

Frequent deletion and methylation in SH3GL2 and CDKN2A loci are associated with early- and late-onset breast carcinoma

BACKGROUND

This study attempts to understand the association of candidate tumour suppressor genes SH3GL2, CDKN2A (p16-p14) and CDKN2B (p15) in development of early-onset (group A) and late-onset (group B) breast carcinoma (BC).

METHODS

Deletion, methylation, and mutation of the candidate tumour suppressor genes (TSGs) were analysed in 47 group A and 59 group B samples. Immunohistochemical analysis was used to identify the expression status of SH3GL2 and p16. Clinicopathological correlation of the alterations was analysed by the chi-square and log-rank tests.

RESULTS

Higher frequency of overall alterations (46-62%) in SH3GL2 and p16-p14 than p15 (22-26%) indicated their importance in BC. Deletion frequencies were in the following order: group A: p14 (43%) > p16 (42%) > SH3GL2 (38%) > p15 (33%) and group B: p14 (36%) > p16 (33%) > SH3GL2 (31%) > p15 (14%) while, methylation frequencies were: group A: SH3GL2 (34%) > p16 (28%) > p14 (26%) > p15 (15%) and group B: SH3GL2 (36%) > p16 (31%) > p14 (29%) > p15 (15%). Infrequent mutation was observed only in CDKN2A common exon-2. Immunohistochemical analysis showed significant association between expression of SH3GL2 and p16 with their deletion (P = 0.01 and 0.02, respectively) and methylation status (P = 0.007 and 0.01, respectively). In group A, overall alterations of SH3GL2 showed significant association with CDKN2A locus with significant prognostic implications, whereas CDKN2A and CDKN2B loci were associated in both groups.

CONCLUSIONS

The molecular mechanisms involving CDKN2A inactivation seem to follow similar pathway in the pathogenesis of both age groups of BC while significant association of SH3GL2 with CDKN2A might play a synergistic role in the development of group A.

Epithelial metaplasia and the development of cancer

Metaplasia means the conversion, in postnatal life, of one cell type to another. Understanding the steps leading to metaplasia is important for two reasons. Firstly, it tells us something about the normal developmental biology of the tissues that interconvert. Secondly, metaplasia predisposes to certain forms of neoplasia. So understanding the molecular and cellular mechanisms underlying metaplasia will provide insights into clinical diagnosis and potential therapies. One of the best-described examples of metaplasia is Barrett's metaplasia or the appearance of intestinal-like columnar tissue in the oesophagus. Barrett's metaplasia develops as a result of gastro-oesophageal reflux and is considered the precursor lesion for oesophageal adenocarcinoma. While we know quite a bit about the molecular events associated with the development of oesophageal adenocarcinoma, our understanding of the initial events leading to Barrett's metaplasia is lacking. In the present review we will focus on examples of metaplasia that lead to neoplasia and discuss some of the underlying molecular and cellular mechanisms.

Loss of MAL expression in precancerous lesions of the esophagus

BACKGROUND

We have identified a novel function of MAL (T-cell differentiation-related gene) as a candidate suppressor gene in esophageal cancer. As the role of MAL expression in esophageal carcinogenesis is as yet undetermined, MAL expression in a rat multi-step carcinogenic model and in precancerous lesions of the human esophagus was investigated. Microarray analysis between MAL-transfectant and control cells was also carried out to clarify how MAL confers its anti-tumor effects.

MATERIALS AND METHODS

(1) In the rat model, MAL expression levels in laser microdissected normal esophageal epithelium, dysplastic tissues and carcinoma tissues were examined by reverse transcription (RT)-PCR. (2) Immunostaining with MAL antibody was performed in 10 dysplastic lesions adjacent to cancer in six cases of esophageal cancer. (3) We established a MAL transfectant using a Tet-off vector in esophageal cancer cells and performed microarray analysis under MAL-positive and MAL-negative conditions.

RESULTS

(1) In the rat model, MAL mRNA expression was observed only in the normal samples. (2) MAL expression was observed distinctively in differentiated or keratinized normal tissues and was not observed in either dysplastic lesions or carcinoma tissue. (3) Up-regulated genes in MAL-positive cells included keratin 18 (transfectant/control = 2.94) and keratin 10 (t/c = 2.82).

CONCLUSION

MAL expression was lost in dysplastic lesions of the rat carcinoma model as well as the human esophagus. The up-regulated keratins revealed by microarray analysis and the strong staining of the differentiated normal tissues in immunohistochemical study support the role of MAL as a regulator of differentiation in esophageal epithelium.

Molecular prognostic factors in adenocarcinoma of the esophagus and gastroesophageal junction

OBJECTIVE

This review describes genetic and molecular changes related to adenocarcinoma of the esophagus and gastroesophageal junction (GEJ) with emphasis on prognostic value and possibilities for targeted therapy in clinical setting. Adenocarcinoma of the esophagus or GEJ is an aggressive disease with early lymphatic and hematogenous dissemination. Molecular pathology has revealed many molecular mechanisms of disease progression, which are related to prognosis. Some of these factors can be seen as prognostic factors per se. Better knowledge of molecular bases may lead to new paradigms, improved prognostication, early diagnosis and individually tailored therapeutic options.

METHODS

A review of recent English literature (1990-October 2005) concerning esophageal adenocarcinoma was performed. This review focuses on genetic and molecular changes as prognosticators of adenocarcinoma of the esophagus and GEJ.

RESULTS

A bewildering number of biomarkers have been described. Many genes and molecules have prognostic impact (cyclin D1, EGFR, Her-2/Neu, APC, TGF-beta, Endoglin, CTGF, P53, Bcl-2, NF-kappaB, Cox-2, E-cadherin, beta-catenin, uPA, MMP-1,3,7,9, TIMP, T( h )1/T( h )2 balance, CRP, PTHrP).

CONCLUSIONS

Adenocarcinomas of the esophagus and GEJ show multiple genetic alterations, which indicate that progression of cancer is a multistep complex process with many different alterations. Presumably, it is not one molecular factor that can predict the biological behavior of this cancer. The combination of diverse genetic alterations may better predict prognosis. In future, gene expression analysis with microarrays may reveal important prognostic information and the discovery of new genes and molecules associated with tumor progression and dissemination will enhance prognostication and offers adjuvant therapeutic options.

CpG island hypermethylation in progression of esophageal and gastric cancer

The upper gastrointestinal (GI) cancers have various carcinogenic pathways and precursor lesions, such as dysplasia for esophageal squamous cell carcinoma, Barrett esophagus for esophageal adenocarcinoma, and intestinal metaplasia for the intestinal-type of gastric cancer. Recently, many epigenetic events in carcinogenic pathways have been revealed, along with genomic and genetic alterations. This information has provided deeper insight into an understanding of the mechanisms of upper GI carcinogenesis. Moreover, detection methods of aberrant methylation have been applied to clinical fields to stratify high-risk groups, detect early cancer, and to predict clinical outcomes. In this review, a variety of information is summarized regarding gene hypermethylation in esophageal and gastric cancer.

Microsatellite analysis of the APC gene and immunoexpression of E-cadherin, catenin, and tubulin in esophageal squamous cell carcinoma

The histological features that accompany the development and progression of solid tumors are known to be controlled by a distinct cascade of molecular events. One such event is the inactivation of tumor suppressor genes, such as the adenomatous polyposis coli (APC) gene. Disruption of the cadherin-catenin cell adhesion complex also plays a role in the initial steps of cancer invasion and metastasis whereas alterations in cell structural molecules, such as tubulin, may contribute to the cancer phenotype. The understanding of the status of these molecules in ESSC may provide novel markers that could impact on management of the disease. The present study examined alterations in the microsatellite sequence of the APC gene via fluorescent-based polymerase chain reaction in 100 cases of primary esophageal squamous cell carcinoma. In addition, the expression of E-cadherin, alpha- and beta-catenin, and alpha- and beta-tubulin was analyzed using immunohistochemistry. These data were then statistically compared with each other as well as the relevant clinicopathologic data. Although the APC markers (D5S210, D5S346, D5S299, and D5S82) tested did show an overall high frequency of allelic imbalance/loss of heterozygosity (62.48%) and microsatellite instability (41.27%), they did not show prognostic significance in the study cohort and were not correlated with the immunohistochemical data. The tubulin proteins showed no significant change in expression in the tumor tissue The decreased immunoreactivity of E-cadherin was statistically correlated with the presence of lymph node metastases (P = .0180). Although alpha- and beta-catenin as well as E-cadherin showed no direct prognostic value, E-cadherin may warrant further investigation as an indirect prognostic indicator by allowing more accurate prediction of lymph node metastases.

Loss of heterozygosity of APC and CDH1 genes in laryngeal squamous cell carcinoma

The molecular mechanisms involved in the development and progression of laryngeal cancer, specifically squamous cell carcinoma, still need further investigation and elucidation. Twenty-two laryngeal squamous cell carcinomas were analyzed in our study regarding genetic changes of two tumor suppressor genes: Adenomatous polyposis coli (APC) and E-cadherin (CDH1). APC gene instability was tested by polymerase chain reaction (PCR)/loss of heterozygosity (LOH) using the restriction fragment length polymorphism (RFLP) method. The samples were also screened for mutations using the heteroduplex method. E-cadherin gene was analyzed by PCR amplification of tetranucleotide marker (D16S752) linked to E-cadherin gene. The results of our analysis showed three samples with LOH of the APC gene out of 15 heterozygous patients (20%). Only one LOH of the CDH1 gene (5.5%) out of 18 heterozygous patients was discovered. D16S752 marker did not reveal any replication error-positive samples. There were six samples showing heteroduplexes (33%) encompassed in APC's exon 11. Altogether, nine samples (41%) showed alterations of the APC gene. Our results suggest that alterations of APC gene may have a role in squamous cell carcinoma development. Detected LOH of the E-cadherin gene indicates that genetic changes of this gene are not very frequent, but that other components of the wnt signaling cascade may also be involved.

Mutations of the APC, beta-catenin, and axin 1 genes and cytoplasmic accumulation of beta-catenin in oral squamous cell carcinoma

PURPOSE

The Wnt pathway is involved in carcinogenesis and three regulatory genes of the Wnt pathway, APC, beta-catenin and Axin are mutated in some primary human cancers. Mutations in these genes can impair the down regulation of beta-catenin, which results in the stabilization of beta-catenin, accumulation of free beta-catenin and subsequent activation of the Wnt pathway. To clarify the genetic alterations of components of the Wnt pathway in oral squamous cell carcinoma (SCC), we examined mutations in the APC, beta-catenin and Axin genes and subcellular localization of beta-catenin.

METHODS

20 oral SCC tissues and four cell lines derived from oral SCC were used. Mutational analysis was performed by a single-strand conformation polymorphism (SSCP) method and direct sequencing analysis. The samples were also examined by immunohistochemical staining and immunoblot analysis.

RESULTS

In 3 of 4 cell lines, mutations were observed in the APC and Axin1 genes without amino acid substitutions. In a clinical sample, a mutation in the Axin1 gene was detected; a T insertion at codon 250 resulted in the formation of a stop codon at codon 259. In addition, cytoplasmic accumulation of beta-catenin was observed in 3 (75%) of 4 cell lines and 18 (90%) of 20 cancer tissue samples.

CONCLUSION

The Axin1 gene may be one of the mutational target in oral SCC. In addition, the cytoplasmic accumulation of beta-catenin is a common characteristic of oral SCC, but is not closely associated with mutational alterations in the APC, beta-catenin and Axin1 genes.

The molecular mechanisms of oesophageal cancer

Apoptosis is a process of programmed cell death, which is as essential as cell growth, for the maintenance of homeostasis. When these processes loose integration such as cancer, then uncontrolled cell growth occurs. Cancer of the oesophagus ranks as the ninth most common malignancy in the world, and recent evidence shows that its incidence is increasing. Prognosis of this disease is poor, with an overall 5-year survival rate of less than 10%. Unraveling the mechanisms or developing animal models for oesophageal carcinoma have thus far not been successful. It is believed that oesophageal cancer has an intricate molecular mechanism of evading apoptosis by the down-regulation of Bax, up-regulation of Bcl-2, Bcl-xl and Survivin, mutation of p53 and alteration in Fas expression. A great deal of research has been performed in order to determine the key genes that initiate and promote the growth of oesophageal cancer. This review focuses on apoptosis and candidate genes linked to the development of oesophageal cancer, which it is hoped may provide diagnostic and therapeutic tools, and potential therapeutic strategies for the management of this carcinoma.

Microsatellite analysis of the adenomatous polyposis coli (APC) gene and immunoexpression of beta catenin in nephroblastoma: a study including 83 cases treated with preoperative chemotherapy

AIMS

To determine whether microsatellite mutations of the adenomatous polyposis coli (APC) gene have pathological or prognostic significance in nephroblastomas and to correlate APC alterations with beta catenin immunoexpression.

METHODS

One hundred nephroblastomas were analysed, 83 of which received preoperative chemotherapy. Normal and tumour DNA was isolated using standard proteinase K digestion and phenol/chloroform extraction from paraffin wax embedded tissue. Polymerase chain reaction using four APC microsatellite markers-D5S210, D5S299, D5S82, and D5S346-was performed and the products analysed. Immunohistochemistry was performed using the LSAB kit with diaminobenzidine as chromogen. Results were correlated with clinicopathological data using the chi(2) test.

RESULTS

Allelic imbalance/loss of heterozygosity was more frequent than microsatellite instability, with 30% of cases showing allelic imbalance/ loss of heterozygosity and 16% showing microsatellite instability. Although there was a significant correlation between the results for individual markers and the clinicopathological data, the overall results do not support a prognostic role for APC in nephroblastoma. Expression of beta catenin was seen in 93% of cases. Staining was predominantly membranous, with epithelium, blastema, and stroma being immunoreactive. Cytoplasmic redistribution was seen in 58% of cases, but no nuclear staining was detected. No significant associations between beta catenin expression and the clinicopathological parameters were found. Kaplan-Meier survival plots showed that patients with loss of membranous staining and pronounced cytoplasmic staining (score, 3) had a significantly shorter survival (p = 0.04; median survival, 5.87 months).

CONCLUSION

Microsatellite analysis of APC and immunoexpression of beta catenin did not provide significant pathological or prognostic information in this cohort of nephroblastomas.

APC gene loss of heterozygosity, mutations, E1317Q, and I1307K germ-line variants in sporadic colon cancer in Croatia

Colorectal carcinomas are characterized by multiple genetic aberrations that occur during tumorigenesis. Several tumor suppressor genes associated with colorectal carcinoma have been identified: MCC, APC, p53, nm23-H1, DCC, DPC4. We examined 73 cases of sporadic human colon cancer and corresponding normal tissue samples to evaluate the loss of heterozygosity (LOH) at the APC gene loci. The purpose of this study was also to evaluate whether the LOH at the APC gene is associated with clinicopathological characteristics in sporadic colon cancer. We also investigated presence and the frequency of the most common APC gene mutations and APC E1317Q and I1307K germ-line variants in Croatian colorectal cancer patients. Five markers in all patients were found to be heterozygous and informative for LOH analysis. LOH at the APC locus was detected in 30.1% of tumors were examined. The majority of APC gene LOH was observed in Dukes' B (55.6%) and in the moderately differentiated tumors (42.9%). Only 1309 APC gene mutation was detected in our samples. In one tumor sample, a new sporadic mutation of the APC gene in codon 1374 was detected. APC E1317Q and I1307K germ-line variants were not detected in our population. But APC E1317Q sporadic mutation was found in one tumor sample.

Identification of a minimal deletion region on chromosome 5q in Chinese esophageal squamous cell carcinomas

The existence of unknown tumor suppressor gene(s) other than the APC gene has been hinted on 5q for esophageal squamous cell carcinoma (ESCC). In order to define minimal deletion intervals on 5q in ESCC and investigate the potential tumor suppressor gene(s), 9 microsatellite markers scattering the region from 5q22 to 5q35 were chosen for loss of heterozygosity (LOH) analysis in 50 primary ESCC from northern China. The results showed that six cases presented coexistence of LOH for three consecutive adjacent chosen markers, suggesting a minimal deletion region covering approximately 272 kb located on 5q23 from D5S1384 to D5S1505. It was a novel deletion region that was so far never reported in ESCC. Significant higher frequencies of LOH were observed in tumors with lower pathological grade at the locus D5S820 and with lymph node metastasis at the locus D5S408. The data suggested the possibility that one or more putative candidate tumor suppressor gene(s) on 5q23 might play an important role in the development and/or progression of ESCC.

Cloning and characterisation of the RBCC728/TRIM36 zinc-binding protein from the tumor suppressor gene region at chromosome 5q22.3

DNA alterations at chromosome 5q22 occur frequently in different types of tumors including urological cancers. Previously, we narrowed a common target region between loci D5S659 and D5S2055 at chromosome 5q22.3 by microsatellite allelotyping. After constructing a BAC contig and shot-gun sequencing we identified a putative exon by the NIX software package. By PCR cloning using the putative exon (5qex5) specific primers and primers directed to the vector (lambdaZAPII) sequence of human brain and kidney cDNA libraries, we obtained a full-length cDNA of 4074 bp of the new gene RBCC728/TRIM36 (GenBank accession no.) with an ORF coding for a protein of 728 amino acids. The TRIM36, which is a new member of the tripartite motif (TRIM) gene family, shows a RING finger C3HC4 structure, two B-box, a coiled-coil, a fibronectin type III and a C-terminal domain of unknown function (SPRY). The TRIM36 has a weak homology to MID1. Immunohistochemistry of recombinant and native TRIM36 displays a cytoplasmic, slightly filamentous staining pattern in COS-7 cells. The TRIM36 is expressed in adult testis, brain, prostate, kidney, heart and lung. A variable level of TRIM36 expression was detected by Q-RT-PCR in conventional RCC, while the gene was consequently upregulated in PCs. We did not find mutation in the open reading frame of the TRIM36 in cancer cells. The overexpression of the TRIM36 in the vast majority of prostate cancer suggest that this gene might be involved in the prostate tumorigenesis.

Basaloid in contrast to nonbasaloid head and neck squamous cell carcinomas display aberrations especially in cell cycle control genes

BACKGROUND

At present, the differences between head and neck basaloid squamous cell carcinoma (BSCC) and nonbasaloid squamous cell carcinoma (SCC) are mostly on the basis of histologic and immunohistologic findings.

METHODS

In this study, we investigated 8 BSCCs and 59 SCCs for loss of heterozygosity (LOH) at chromosomes 5q, 9p, 9q, 10q, 11q, 13p, 17p, and 18q. In addition, we analyzed p16, PTEN, and CCND1 (cyclin D1) and investigated the HPV status. Immunohistochemically, the expression of MIB-1, p16, p53, and cyclin D1 was determined.

RESULTS

Aberrations in the BSCCs were especially frequent at 9p and in the CCND1 gene. In contrast, alterations at 10q occurred almost exclusively in conventional SCCs. Obvious differences could be determined concerning the HPV status: HPV-DNA was detected in all BSCCs but only in 17% of conventional SCCs.

CONCLUSIONS

Although the number of investigated BSCCs is rather low and did not allow statistical conclusions, our results focus on certain differences between the molecular pathogenesis of BSCCs and SCCs.

Loss of heterozygosity at APC and MCC genes of oral cancer and leukoplakia tissues from Indian tobacco chewers

BACKGROUND

Loss of heterozygosity (LOH) at tumor suppressor genes, such as adenomatous polyposis coli (APC) and mutated in colon cancer (MCC) genes, is one of the early events in carcinogenesis of oral tissue in Caucasian and Chinese patients. We wanted to check whether it is also true in Indian oral pre-cancer and cancer patients.

METHODS

Loss of heterozygosity at APC and MCC genes was investigated in 57 and 40 unrelated primary oral leukoplakia (a pre-cancerous lesion) and squamous cell carcinomas (SCC), respectively, by polymerase chain reaction.

RESULTS

In these samples, most of the leukoplakia patients had tobacco smoking habit whereas majority of cancer patients had tobacco chewing habit. LOH at APC gene was observed in 4 of 16 (25%) and 1 of 29 (3%) informative tumor and leukoplakia DNAs from tobacco chewers, respectively. LOH at MCC gene was not detected either in tumor or in leukoplakia DNAs.

CONCLUSION

This infrequent LOH at APC gene of pre-cancer and cancer tissues suggests that it may not be an early event in oral carcinogenesis in these patients.

Redistribution of β-catenin in response to EGF and lithium signalling in human oesophageal squamous carcinoma cell lines

BACKGROUND

The β-catenin link between membrane-bound cadherins and the actin cytoskeleton regulates cell adhesion and consequently metastasis. Abnormal stabilisation of β-catenin enhances its transcriptional activities. Factors affecting β-catenin's functions are important in understanding metastatic diseases such as oesophageal squamous cell carcinoma (SCC).

RESULTS

In human oesophageal SCCs β-catenin localises predominantly to the plasma membrane. The presence of free β-catenin in the cytoplasm/nucleus was low. This indicates that β-catenin's activities are skewed towards cell-cell adhesion in these oesophageal SCCs. Exposure to EGF or Li alone, produced a slight increase in membrane concentrations but only Li induced β-catenin stabilisation in the cytoplasm. In combination, EGF and Li decreased membrane-associated β-catenin, concomitantly increasing cytoplasmic concentrations. Convergence of these signalling pathways appears to induce a β-catenin shift from the membrane into the cytoplasm.

CONCLUSION

Therefore, although the adhesive role of β-catenin appears to be intact, exogenous signals increase the stability of free β-catenin thereby reducing cell-cell adhesion in these tumours.

Mutations of the adenomatous polyposis coli gene in areca quid and tobacco-associated oral squamous cell carcinomas in Taiwan

BACKGROUND

Adenomatous polyposis coli (APC) gene mutations have been demonstrated not only in colorectal tumors but also in a variety of human cancers.

METHODS

To elucidate the possible roles of APC gene mutations in oral squamous cell carcinomas (OSCCs), we examined 40 untreated human primary OSCCs using polymerase chain reaction-single strand conformation polymorphism (PCR-SSCP) and DNA sequencing assays.

RESULTS

By screening nearly one-half of the coding region (codons 279-1673, including the MCR) of the APC gene, five missense mutations and a 1-base pair deletion were detected in five (12.5%) tumors, resulting in five amino-acid substitutions or a truncation of the APC protein. All patients with APC mutations were both areca quid chewers and tobacco smokers (P = 0.049).

CONCLUSIONS

These results suggest that APC mutations may also contribute to the carcinogenesis of at least some OSCCs in Taiwan, especially for the users of areca quid and tobacco.

Clinical significance of allelic loss of chromosome region 5q22.3 approximately q23.2 in nonpapillary renal cell carcinoma

To analyze the clinical significance of copy number gain and loss at chromosome region 5q21 approximately q23, 105 nonpapillary renal cell carcinomas (RCC) were examined by interphase cytogenetic analysis using the dual-color fluorescence in situ hybridization (FISH) technique. DNA probes for D5S23 (5p15.2), cCI5-243 (5q21.2 approximately q21.3), and cCI5-215 (5q22.3 approximately q23.2) were used, and the signals for cCI5-243 and cCI5-215 were compared with those for D5S23 as the numerical control. Aneusomy (three or more copies) of chromosome 5 was found in 22 tumors (21.0%). Aneusomy was significantly correlated with loss at 5q21 approximately q23, while disomy with gain at 5q21 approximately q23 (P<0.05). Aneusomy was also significantly related to poor disease-specific survival (P<0.01). Gain and loss at cCI5-243 were seen in 34 (32.4%) and 59 (56.2%) tumors, respectively, while gain and loss at cCI5-215 occurred in 55 (52.4%) and 45 (42.9%) cases, respectively. The frequency of gain at cCI5-215 was significantly correlated with a smaller tumor diameter (7 cm or less, P<0.05), while loss with a larger one (>7 cm, P<0.05). Both loss at cCI5-215 and aneusomy of chromosome 5 were significantly related to poor disease-specific survival (P<0.05). In conclusion, alterations of chromosome 5 (including allelic loss of 5q22.3 approximately q23.2) could be a useful genetic marker for predicting the patient prognosis of RCC.

Gene mutation as a target for early detection in cancer diagnosis

The increasing number of genetic aberrations implicated in the development of human cancer has prompted a search to detect them at the earliest possible stage of their formation. Of the many such genetic changes identified thus far, relatively few meet the standard for markers in early diagnosis and prognosis, namely that the genetic modifications occur during the early onset phase of cancer development. Parallel to the increasing number of such genes is the growing availability of technologies using more powerful and cost-efficient methods that enable mass screening for genetic alterations. The purpose of this review is to summarize the currently available genes that can serve as markers for early detection of cancers and methods that allow their detection.

Frequent loss of heterozygosity on multiple chromosomes in Chinese esophageal squamous cell carcinomas

Analysis of the loss of heterozygosity (LOH) detected by polymerase chain reaction techniques using 18 polymorphic markers localized to chromosomes 3p, 5, 17, and 18q in 40 Hong Kong Chinese esophageal squamous cell carcinoma (ESC) patients showed that multiple alterations on several chromosomes are involved in ESC development. The LOH rates detected for markers on chromosome 3 ranged from 44.0 to 85.7%, for chromosome 5 from 40.9 to 61.9%, for chromosome 17 from 40.0 to 100%, and for chromosome 18 from 38.9 to 58.3%. No significant association was observed between LOH and the clinical and histopathological parameters.

Telomere erosion is independent of microsatellite instability but related to loss of heterozygosity in gastric cancer

AIM: To correlate the length of the telomere to microsatellite instability (MSI) and loss of heterozygosity (LOH) of APC, MCC and DCC genes in gastric carcinomas.

METHODS: Telomeric restriction fragment (TRF) length of gastric cancer was measured with Southern blot. LOH of APC, MCC and DCC genes, microsatellite instability (MSI) and frameshift mutation of hMSH6, TGF-βRII and BAX genes were analyzed by PCR-based methods.

RESULTS: Sixty-eight cases of sporadic gastric carcinoma were studied for MSI using five microsatellite markers. MSI in at least one locus was detected in 17 (25%) of 68 tumors analyzed. Frameshift mutations of hMSH6, TGF-βRII and BAX were detected in 2, 6 and 3 of gastric carcinomas respectively showing high MSI (≥ 2 loci, n = 8), but none was found in those showing low MSI (only one locus, n = 9) or MSS (tumor lacking MSI or stable, n = 51). Thirty-five cases, including all high MSI and low MSI, were studied for TRF. The mean TRF length was not correlated with clinicopathological parameters. No association was observed between TRF length and MSI or frameshift mutation. On the contrary, LOH at the DCC locus was related to telomere shortening (P < 0.01). This tendency was also observed in APC and MCC genes, although there was no statistical significance.

CONCLUSION: The development of gastric cancer can arise through two different genetic pathways. In high MSI gastric cancers, defective mismatch repair allows mutations to accumulate and generate the high MSI phenotype. In gastric cancers showing either low MSI or MSS, multiple deletions may represent the LOH pathway. Telomere erosion is independent of high MSI phenotype but related to the LOH pathway in gastric cancer.

Genetic alterations and growth pattern in biliary duct carcinomas: loss of heterozygosity at chromosome 5q bears a close relation with polypoid growth

Biliary duct carcinomas (BDCs) are relatively rare and the carcinogenic mechanisms underlying their induction are poorly understood. There are two growth patterns, polypoid and non-polypoid infiltrative type, but little information is available concerning the relation between growth pattern and genetic alterations. A comparative study was therefore conducted to clarify if differences in genetic changes, including loss of heterozygosity (LOH) at 5q, 9p, 17p, and 18q, and K-ras mutations exist between polypoid and non-polypoid infiltrative type BDCs. LOH analysis was performed using microsatellite markers and K-ras point mutations were analysed by dot blot hybridisation. The incidences of changes for polypoid and non-polypoid infiltrative types were 73% and 26% on 5q, 63% and 59% on 9p, 55% and 50% on 17p, and 20% and 18% on 18q, and 25% and 27% for K-ras mutations. Most importantly, we found the frequency of 5qLOH to be significantly higher with polypoid growth than in the non-polypoid infiltrative type (p<0.05), especially in extrahepatic duct carcinomas (p<0.05). The incidences of other genetic alterations (LOH at 9p, 17p, and 18q, and K-ras mutations) showed similar rates with both tumour types. The present data suggest that 5qLOH may have a close relation with polypoid growth in BDCs.

Nuclear localization of beta-catenin is an important prognostic factor in hepatoblastoma

In this study, mutational and immunohistochemical analyses of beta-catenin were performed in 30 hepatoblastomas, to assess the prevalence of alterations of the Wnt pathway with respect to clinicopathological parameters and survival. Four missense mutations of beta-catenin (13.3%) were detected and there was strong immunoreactivity for beta-catenin in the cytoplasm and/or the nucleus in 97% of hepatoblastomas. Nuclear and cytoplasmic staining was demonstrated in 19 of 30 tumours (63%), while ten revealed only cytoplasmic staining. Statistically, this nuclear beta-catenin staining was significantly higher in the embryonal (Fisher exact test; p=0.00393) or undifferentiated type (p=0.00156) of hepatoblastoma than in the fetal type, but there was no difference between clinical stages I and II and clinical stages III and IV (p=0.175). Cumulative survival curves showed that nuclear beta-catenin staining (generalized Wilcoxon test; p=0.0088), undifferentiated histological type (p=0.0305), and clinical stages III and IV (p=0.0107) were significantly correlated with shorter survival time in these patients. Moreover, Cox multivariate analysis provides evidence that nuclear beta-catenin staining is the most important prognostic factor for survival (p=0.0090). It is therefore concluded that immunohistochemical analysis of beta-catenin might be a useful clinical tool for estimating the prognosis for patients with hepatoblastoma.