Allelic loss of the region of chromosome 1p35-pter is associated with progression of human gastric carcinoma

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.

Cloning and expression analysis of the gastric carcinoma-related gene, ELCOX3

Gastric cancer is a pathological process of an accumulation of multigene and multistage mutations. A new gene segment, MDSCBC11, has been previously obtained using a gene chip and is negatively associated with gastric cancer. The present study aimed to clone the full cDNA sequence of the MDSCBC11 segment and to detect its expression in gastric carcinomas and normal gastric mucosa. Multiple-tissue northern blots revealed that the new MDSCBC11-represented gene was expressed as two transcripts that were 0.8 kb and 1.5 kb in size. The cDNA sequence of the smaller transcript was 822 bp, created by 5′ rapid amplification of cDNA ends (RACE) and 3′ RACE methods. A bioinformatics analysis indicated that the deduced amino acid sequence of MDSCBC11 had a 99% homology with the cytochrome c oxidase III (COX3) gene in the mitochondria. A total of 46 cases of gastric carcinomas, adjacent gastric mucosa and normal gastric mucosa were individually collected, and the mRNA expression of the ELCOX3 gene was detected by RT-PCR. ELCOX3 mRNA was expressed in all 46 cases of the normal gastric mucosa. The expression levels of ELCOX3 mRNA in the gastric carcinomas were lower compared with that of the adjacent and normal gastric mucosa (P<0.05), with the percent of downregulation at 23.91% (11/46 cases). The downregulation of ELCOX3 gene expression was associated with the development of human gastric carcinomas.

Clinicopathological significance of loss of heterozygosity in intestinal- and solid-type gastric carcinomas: a comprehensive study using the crypt isolation technique

The clinicopathological significance of loss of heterozygosity (LOH) in gastric carcinoma remains poorly understood. We and other researchers have previously demonstrated that LOH is fairly common in intestinal- and solid-type gastric carcinomas, but rare in diffuse-type tumors. In this study, we investigated the relationship between clinicopathological variables and LOH status in intestinal- and solid-type gastric carcinomas. The crypt isolation technique was utilized to analyze LOH at 1p36, 3p14, 4p15, 5q21-22, 8p11-12, 9p21, 13q22, 17p13.1 18q21 and 22q13.31 in 113 intestinal- and solid-type gastric carcinomas using a polymerase chain reaction assay. Immunostaining with D2-40 and Elastica van Gieson staining were used to detect lymphatic invasion and vessel invasion, respectively. High LOH rates (49-71%) were observed in all chromosomal regions tested. 1p36 loss was significantly associated with advanced tumors and lymph node metastasis. 8p11-12 loss was significantly associated with lymph node metastasis, lymphatic invasion, and vessel invasion. 17p13.1 (TP53) loss was significantly associated with vessel invasion. 22q13.31 loss was significantly associated with advanced tumors, lymph node metastasis, lymphatic invasion, vessel invasion and late TNM stage. No significant associations were observed between LOH at other chromosomal regions and aggressive behaviors. In addition, significantly higher LOH rates at 1p36, 9p21, 18q21 and 22q13.31 were observed in cardiac tumors compared with noncardiac tumors. These results suggest that in intestinal- and solid-type gastric carcinomas, LOH on 3p14, 4p15, 5q21-22, 9p21, 13q22 and 18q21 is associated with carcinogenesis, while LOH on 1p36, 8p11-12, 17p31.1 and 22q13.31 is associated with tumor progression.

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.

Comparative study between DNA copy number aberrations determined by quantitative microsatellite analysis and clinical outcome in patients with stomach cancer

PURPOSE

We detected the relative DNA copy numbers (RCNs) at target loci in patients with stomach cancer with quantitative microsatellite analysis. We additionally clarified the relationship between DNA copy number aberrations and the clinical outcome of the patients.

EXPERIMENTAL DESIGN

Fresh frozen samples were obtained from 30 patients who had undergone surgery for stomach cancer. Seven microsatellite loci in chromosomes 8q, 16q, and 20q and one gene-specific locus (ZNF217) were selected as the target loci. The DNA copy number was obtained relatively to a pooled reference consisting of six microsatellite primer sets selected from the regions where few aberrations have been reported in comparative genomic hybridization analysis. On the basis of the TaqMan PCR system, the internal probes used were carrying donor (6-carboxyfluorescein) and acceptor (6-carboxytetramethylrhodamine) fluorescent molecules complementary to CA repeats in the microsatellite markers and to one gene-specific oligomer in the gene-specific marker.

RESULTS

Chromosome 8q gain, 20q gain, and 16q loss were detected in 18 (60.0%), 8 (26.7%), and 13 (43.3%) cases, respectively. Gains in the RCNs of D8S1801 and D8S1724 were most frequently found (36.7%). There was a significant correlation between the loss of D16S3026 and reduced survival duration (P = 0.0158), and the simultaneous aberrations of D8S1801 gain and D16S3026 loss (double marker positive) was significantly associated with reduced survival duration (P = 0.0008). According to Cox proportional hazards model, the double marker positive was a significant and independent factor indicating an unfavorable prognostic factor (relative risk, 17.176; 95% confidence interval, 2.782-106.026; P = 0.0022).

CONCLUSION

RCN aberrations in tumor tissues determined by quantitative microsatellite analysis enable identification of the prognostic factors that correlate with clinical outcome of the patients with stomach cancer.

cDNA suppression subtraction library for screening down-regulated genes in gastric carcinoma

AIM: To establish cDNA suppression subtraction library with a high subtraction efficiency by counterpart normal gastric mucosa mixture mRNA subtracting gastric cancer cells mixture mRNA for screening down-regulated genes in gastric carcinoma.

METHODS: RNA of gastric cancer tissues and counterpart normal gastric mucosa were respectively isolated in five patients with gastric cancer, and their mRNA was purified. cDNA suppression subtraction library was established by counterpart normal gastric mucosa mixture mRNA (tester) subtracting gastric cancer tissues mixture mRNA (driver) of five patients with gastric carcinoma. The library plasmids were transformed into competent bacteria DH5a after ligation of the library cDNA fragments with T vectors. Library plasmids were extracted after picking colonies and shaking bacteria overnight. Its subtraction efficiency was confirmed by PCR and reverse hybridization of a nylon filter onto which the colonies of bacteria were transfered with probes of reverse transcription products cDNA of gastric cancer tissues mRNA and counterpart normal gastric mucosa mRNA labeled with α-³²P dCTP.

RESULTS: mRNA purified from total RNA of gastric cancer tissues and counterpart normal gastric mucosa in five patients with gastric carcinoma revealed a good quality. cDNA suppression subtraction library constructed for screening down-regulated genes in gastric carcinoma represented a high subtraction efficiency. 86% of differential expression in down-regulated genes between counterpart normal gastric mucosa and gastric carcinoma was confirmed.

CONCLUSION: cDNA suppression subtraction library with a high subtraction efficiency for screening down-regulated genes in gastric carcinoma is successfully established.

p29, a novel GCIP-interacting protein, localizes in the nucleus

GCIP, a newly identified cyclin D-interacting protein, was found to reduce the phosphorylation of retinoblastoma protein and inhibit E2F1-mediated transcriptional activity. To explore more GCIP interacting proteins, the yeast two-hybrid screening using GCIP as a bait protein was performed. One novel gene, p29, was demonstrated to associate with GCIP in the yeast two-hybrid method and in vitro GST pull-down assay. Multiple tissue Northern blot analysis showed that p29 was abundantly expressed in the heart, skeletal muscle, and kidney relative to other tissues. The transient expression of HA-tagged p29 in HeLa cells localized in the nucleus. Taken together, we have isolated a novel protein, p29, which may be involved in the functional regulation of GCIP.