AIM:NGX6,NAG-7 and BRD7 genes are tumor relatedgenes,which have been newly cloned by positionalcandidate cloning strategy.This study was designed toinvestigate the expression levels of NGX6,NAG-7 and BRD7genes in human gastric and colorectal cancer tissues,andtheir corresponding normal tissues,and to investigatewhether these genes play a role in the pathogenesis ofgastric and colorectal cancers.METHODS:Reverse transcription-polymerase chain reaction(RT-PCR),dot hybridization and Northern blot analysis wereused to compare the expression levels of NGX6,NAG-7 andBRD7 genes in 34 gastric cancer tissues and 34 colorectalcancer tissues with their corresponding normal tissues ofthe same patients,respectively.RESULTS:Among the 34 colorectal cancer specimens andthe 34 gastric cancer specimens,the expression of NGX6in 25 colorectal cancer tissues was absent or very weak(73.5 %) by RT-PCR analysis.The down-regulation rate ofNGX6 in colorectal cancer tissues was significantly higherthan that in corresponding normal tissues (26.5 %,9/34)(P<0.005).Moreover,the down-regulation of NGX6 wassignificantly correlated with lymph node and/or distancemetastases.Patients with lymph node and/or distancemetastasis had much higher down-regulation rate of NGX6than patients without metastases (93.8 % vs55.6 %,P<0.05).However no correlation was found between the expressionof NGX6 and pathologic type of colorectal cancer in thisstudy,and also the expression of NGX6 did not display anydifference between gastric cancer and corresponding normaltissues (58.8 % vs 70.6 %,P>0.25).Dot hybridization andNorthern 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 withtheir 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. AIM: NGX6, NAG-7 and BRD7 genes are tumor related genes, which have been newly cloned by positional codand 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 the 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 the 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 higherthan that in co The down-regulation of NGX6 wassignificantly correlated with lymph node and / or distance metastases. Patients with lymph node and / or distancemetastasis had much higher down-regulation rate (26.5%, 9/34) (P <0.005) of NGX6 patients without metastases (93.8% vs55.6%, P <0.05) .However no correlation was found between the expressionof 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 normaltissues (58.8% vs 70.6%, P> 0.25). Dot hybridization and Northern blot analysis confirmed the results of RT-PCR. Frtherrther, 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 gaIn 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.