ABSTRACT
Objective@#To investigate the expression of TTK (tyrosine and threonine protein kinase) in the process of colorectal cancer (CRC) development and its relationship to prognosis in CRC patients.@*Methods@#Colitis-associated colon cancer model was induced by azoxymethane (AOM) and dextran sulfate sodium (DSS) in C57BL/6 mice. Mice at four different stages of colon cancer development were obtained, named AD1 (inflammation of the recovery), AD2 (mild dysplasia), AD3 (adenoma) and AD4 (adenocarcinoma), as well as negative control (no treatment). The expression of TTK was measured by real time fluorescent quantitative PCR (qPCR) and immunohistochemical staining in mouse colon tissues and 24 pairs of CRC specimens. The relationship between TTK and prognosis was analyzed in a set of CRC genome-wide gene expression microarray data that was obtained from Gene Expression Omnibus (GEO) of National Center for Biotechnology Information (NCBI).@*Results@#The genome-wide microarray data from mouse AOM-DSS model indicated that the expression of TTK mRNA was gradually elevated during the development of colon cancer. The subsequent qPCR results showed that TTK mRNA levels in negative control, AD1, AD2, AD3 and AD4 groups were 1.05±0.42, 1.10±0.03, 1.38±0.15, 1.33±0.17 and 2.12±0.22, respectively. And TTK expression in AD2, AD3 and AD4 groups were significantly higher than that in negative control (P<0.05). The protein expression of TTK showed by immunohistochemical staining had similar tendency as the results of TTK mRNA. Besides that, the TTK mRNA levels in tumor tissues (0.71±0.10) from 24 CRC patients were significantly higher than those in paired adjacent normal tissues (0.18±0.04; P<0.001). The positive expression rate of TTK protein in 5 pairs of CRC clinical samples was 80.0%, and it was significantly higher than that in adjacent normal tissues (30.8%, P=0.014). Furthermore, according to a public transcriptomic data (GSE17536), the high levels of TTK were associated with poor prognosis in CRC patients.@*Conclusions@#Elevated expression of TTK is related to colonic carcinogenesis in both of mouse model and human CRC samples. TTK is a poor prognostic factor in CRC.
ABSTRACT
<p><b>OBJECTIVE</b>To investigate the changes of miR-155 and its target genes in colitis-associated carcinogenesis.</p><p><b>METHODS</b>Colitis-associated colon cancer was induced by azoxymethane (AOM) and dextran sulfate sodium (DSS) in C57BL/6 mice. Mice of three different stages during the development of colon cancer were obtained, named AD1, AD2 and AD3, respectively. A control group of mice without any treatment and a DSS only group representing chronic inflammation without cancer were set up as well. Colon tissue was collected and expression of miR-155 in the colon tissues was measured by real-time fluorescent quantitative PCR. TargetScan and PicTar were used to predict potential target genes of miR-155, which were then preliminarily screened with our gene expression microarray database of AOM-DSS mouse model. Regular PCR was used to confirm the changes of the expression of these potential target genes in AOM-DSS mouse model.</p><p><b>RESULTS</b>Colitis-associated colon cancer was effectively induced by azoxymethane and dextran sulfate sodium in C57BL/6 mice. Histological examination revealed that the evolution process was sequentially from normal, mild dysplasia, moderate dysplasia, and severe dysplasia to adenocarcinoma in the AOM-DSS mouse model. The level of miR-155 was gradually elevated with the formation of colitis-associated colon cancer. There was no significant difference between the levels of miR-155 expression in the DSS group (0.005 6 ± 0.003 7) and control group (0.012 0 ± 0.005 1) (P > 0.05), but the level of miR-155 in the AD3 group (0.054 4 ± 0.027 0) was significantly higher than that of the DSS group (0.005 6 ± 0.003 7)(P < 0.01). No significant change of miR-155 expression was found in the DSS only group. The relative expression levels of miR-155 in the control group, DSS only group and AD3 group were 0.012 0 ± 0.005 1, 0.005 6 ± 0.003 7, 0.054 4 ± 0.027 0, respectively. Data analysis with the gene expression microarray showed that Tle4, Kcna1, Itk, Bcorl1, Cacna1c, Rspo2 and Foxo3 were potential target genes of miR-155 in the AOM-DSS mouse model. Changes of Kcna1 and Cacna1c in the AOM-DSS mouse model were validated to be consistent with the changes obtained with the gene expression microarray.</p><p><b>CONCLUSION</b>The up-regulation of miR-155 is related to colitis-associated carcinogenesis, but is irrelevant to chronic inflammation in the mouse model.</p>