Genetic alterations and expression of inhibitor of growth 1 in human sporadic colorectal cancer

AIM： To explore the effect and significance of inhibitor of growth 1 （ING1） gene in carcinogenesis and progression of human sporadic colorectal cancer. METHODS： mRNA expression, mutation, and loss of heterozygosity （LOH） of ING1 gene in 35 specimens of sporadic colorectal cancer tissues and the matched normal mucous membrane tissues were detected by semi-quantitative reverse transcriptase-polymerase chain reaction （RT-PCR）, PCR-single strain conformation polymorphism （PCR-SSCP） and PCR-simple sequence length polymorphism （PCR-SSLP） using microsatellite markers, respectively. RESULTS： The average ratios of light intensities of p33^ING1b and p47^ING1a mRNA expression in the cancerous tissues were significantly lower than those in normal tissues. The difference between the two mRNA splices was not significant in the matched tissues. In addition, the ratios of light intensities of p33^ING1b and p47^ING1a mRNA expression in the cancerous tissues of Dukes＇ stages C and D were significantly lower than those in cancerous tissues of Dukes＇ stages A and B. However, no mutation of ING1 gene was detected in all 35 cases; only 4 cases of LOH （11.4%） were found. CONCLUSION： p33^ING1b and p47^ING1a mRNA expressions are closely related with the carcinogenesis and progression of human sporadic colorectal cancer. No mutation of ING1 gene is found, and there are only few LOH in sporadic colorectal cancers. These might not be the main reasons for the down regulation of ING1 expression. Its low expression may happen in transcription or post-transcription.

Down-regulation of miR-622 in gastric cancer promotes cellular invasion and tumor metastasis by targeting ING1 gene

AIM:To evaluate the biological and clinical characteristics of miR-622 in gastric cancer. METHODS:We analyzed the expression of miR-622 in 57 pair matched gastric neoplastic and adjacent non-neoplastic tissues by quantitative real-time polymerase chain reaction. Functional analysis of miR-622 expression was assessed in vitro in gastric cancer cell lines with miR-622 precursor and inhibitor. The roles of miR-622 in tumorigenesis and tumor metastasis were analyzed using a stable miR-622 expression plasmid in nude mice. A luciferase reporter assay was used to assess the effect of miR-622 on inhibitor of growth family,member 1 (ING1) expression. RESULTS:Expression of miR-622 was down-regulated in gastric cancer. MiR-622 was found involved in differentia-tion and lymphatic metastasis in human gastric cancer. Ectopic expression of miR-622 promoted invasion,tumorigenesis and metastasis of gastric cancer cells both in vitro and in vivo. ING1 is a direct target of miR-622. CONCLUSION:These findings help clarify the molecular mechanisms involved in gastric cancer metastasis and indicate that miR-622 modulation may be a bona fide treatment of gastric cancer.