AIM: To detect the loss of heterozygosity (LOH) and microsatellite instabilities (MSI) of fragile histidine triad (FHIT) gene in gastric carcinoma and to study their association with the clinical pathological characteristics of gastric carcinoma.

METHODS: LOH and MSI of FHIT gene were detected at four microsatellite loci D3Sl3H, D3S4l03, D3Sl48l and D3S1234 using PCR in matched normal and cancerous tissues from 50 patients with primary gastric cancer.

RESULTS: The average frequency of LOH and MSI of FHIT gene in gastric cancer was 32.4% and 26.4% respectively. LOH and MSI of FHIT gene in gastric cancer had no association with histological, Borrmann, and Lauren’s classification. LOH of FHIT gene in gastric cancer was related to invasive depth. The frequency of FHIT LOH in gastric cancer with serosa-penetration was obviously higher than that in gastric cancer without serosa-penetration (73.5% vs 37.5%, P < 0.05). MSI of FHIT gene in gastric cancer was associated with the lymph node metastasis. The frequency of MSI in gastric cancer without lymph node metastasis was significantly higher than that in gastric cancer with lymph node metastasis (66.7% vs 34.3%, P < 0.05).

CONCLUSION: LOH of FHIT gene is correlated with invasive depth of gastric carcinoma. MSI of FHIT gene is correlated with lymph node metastases. LOH and MSI of FHIT gene play an important role in carcinogenesis of gastric cancer.

• Gastric cancer
• FHIT gene
• Microsatellite instabilities

• Acid Anhydride Hydrolases/genetics
• Adenocarcinoma/genetics
• DNA, Neoplasm/genetics
• Gene Expression Regulation, Neoplastic
• Genomic Instability
• Humans
• Loss of Heterozygosity
• Lymphatic Metastasis/genetics
• Microsatellite Repeats/genetics
• Neoplasm Proteins/genetics
• Stomach Neoplasms/genetics

AIM: To detect the loss of heterozygosity (LOH) of fragile histidine triad (FHIT) gene in gastric cancer and precancerous lesions (dysplasia and intestinal metaplasia), and to analyze its role in the carcinogenesis of gastric cancer.

METHODS: The LOH at microsatellites loci D3S1234 and D3S1300 of FHIT gene were measured in samples of gastric cancer (n = 42), dysplasia (n = 44), intestinal metaplasia (n = 51) and their corresponding normal tissues by (polymerase chain reaction) PCR.

RESULTS: The rates of LOH at D3S1234 locus were 32.4%(11/34), 28.6%(10/35) and 10%(4/40) in gastric cancer, dysplasia and intestinal metaplasia respectively, and the ones at D3S1300 locus were 33.3%(12/36) , 32.4%(11/34) and 7.7% (3/39) respectively. The LOH rates at D3S1234 and D3S1300 loci in gastric cancer and atypical hyperplasia were higher than that of intestinal metaplasia (P<0.05, P<0.01 for D3S1234 and D3S1300 respectively). No significant difference of LOH rate was found between gastric cancer and dysplasia.

CONCLUSION: The loss of heterozygosity of FHIT gene may be an early event in the tumorigenesis of gastric cancer.

• Stomach neoplasms
• Gastric cancer
• Precancerous lesion
• Fragile histidine triad
• Loss of heterozygosity

AIM: NGX6, NAG-7 and BRD7 genes are tumor related genes, which have been newly cloned by positional candidate cloning strategy. This study was designed to investigate the expression levels of NGX6, NAG-7 and BRD7 genes in human gastric and colorectal cancer tissues, and their corresponding normal tissues, and to investigate whether these genes play a role in the pathogenesis of gastric and colorectal cancers.

METHODS: Reverse transcription-polymerase chain reaction (RT-PCR), dot hybridization and Northern blot analysis were used to compare the expression levels of NGX6, NAG-7 and BRD7 genes in 34 gastric cancer tissues and 34 colorectal cancer tissues with their corresponding normal tissues of the same patients, respectively.

RESULTS: Among the 34 colorectal cancer specimens and the 34 gastric cancer specimens, the expression of NGX6 in 25 colorectal cancer tissues was absent or very weak (73.5%) by RT-PCR analysis. The down-regulation rate of NGX6 in colorectal cancer tissues was significantly higher than that in corresponding normal tissues (26.5%,9/34) (P < 0.005). Moreover, the down-regulation of NGX6 was significantly correlated with lymph node and/or distance metastases. Patients with lymph node and/or distance metastasis had much higher down-regulation rate of NGX6 than patients without metastases (93.8% vs 55.6%, P < 0.05). However no correlation was found between the expression of NGX6 and pathologic type of colorectal cancer in this study, and also the expression of NGX6 did not display any difference between gastric cancer and corresponding normal tissues (58.8% vs 70.6%, P > 0.25). Dot hybridization and Northern blot analysis confirmed the results of RT-PCR. Furthermore, NAG-7 and BRD7 mRNA was not up- or down-regulated in gastric and colorectal cancers compared with their corresponding normal tissues in our study.

CONCLUSION: The down-regulation of NGX6 may be closely associated with tumorigenesis and metastasis of colorectal carcinoma. However, it may not contribute to the development and progression of gastric carcinoma. In addition, the expression levels of NAG-7, and BRD7 did not alter in gastric and colorectal cancers. This seems to suggest that NAG-7 and BRD7 genes may not play a role in gastric and colorectal carcinogenesis.

• Blotting, Northern
• Cell Cycle Proteins
• Chromosomal Proteins, Non-Histone/genetics
• Colorectal Neoplasms/genetics
• Gene Expression
• Humans
• Membrane Proteins/genetics
• Nuclear Proteins
• Nucleic Acid Hybridization/methods
• RNA, Long Noncoding
• RNA, Untranslated
• Reverse Transcriptase Polymerase Chain Reaction
• Stomach Neoplasms/genetics
• Tumor Suppressor Proteins/genetics

AIM: To investigate the effects of antisense human telomerase RNA (hTR) on the biologic behavior of human gastric cancer cell line: MKN-45 by gene transfection and its potential role in the gene therapy of gastric cancer.

METHODS: The hTR cDNA fragment was cloned from MKN-45 through RT-PCR and subcloned into eukaryotic expression vector (pEF6/V5-His-TOPO) in cis-direction or trans-direction by DNA recombinant methods. The constructed sense, antisense and empty vectors were transfected into MKN-45 cell lines separately by lipofectin-mediated DNA transfection technology. After drug selection, the expression of antisense hTR gene in stable transfectants and normal MKN-45 cells was detected by RT-PCR, the telomerase activity by TRAP, the apoptotic features by PI and Hoechst 33258 staining, the cell cycle distribution by flow cytometry and the population doubling time by cell counting. Comparison among the stable transfectants and normal MKN-45 cells was made.

RESULTS: The sense, antisense hTR eukaryotic expression vectors and empty vector were successfully constructed and proved to be the same as original design by restriction endonuclease analysis and sequencing. Then, they were successfully transfected into MKN-45 cell lines separately with lipofectin. The expression of antisense hTR gene was only detected in MKN-45 cells stably transfected with antisense hTR vector (named as MKN-45-ahTR) but not in the control cells. In MKN-45-ahTR, the telomerase activity was inhibited by 75%, the apoptotic rate was increased to 25.3%, the percentage of cells in the G0/G1 phase was increased to 65%, the proliferation index was decreased to 35% and the population doubling time was prolonged to 35.3 h. However, the telomerase activity, the apoptotic rate, the distribution of cell cycle, the proliferation index and the population doubling time were not different among the control cells.

CONCLUSION: Antisense hTR can significantly inhibit telomerase activity and proliferation of MKN-45 cells and induce cell apoptosis. Antisense gene therapy based on telomerase inhibition can be a potential therapeutic approach to the treatment of gastric cancer.

• Apoptosis/drug effects
• Cell Division/drug effects
• Gene Expression
• Genetic Vectors
• Humans
• RNA, Antisense/genetics
• RNA, Antisense/pharmacology
• Stomach Neoplasms/enzymology
• Stomach Neoplasms/pathology
• Stomach Neoplasms/therapy
• Telomerase/antagonists & inhibitors
• Telomerase/genetics
• Tumor Cells, Cultured