Hypomethylation-Associated Up-Regulation of <i>TCF3</i> Expression and Recurrence in Stage II and III Colorectal Cancer

<div><p>Background and Objectives</p><p>Transcription factor 3 (<i>TCF3</i>) implicates Wnt signaling pathway and regulates E-cadherin expression, which is involved in aggressiveness of tumors. This study aims to investigate the role of <i>TCF3</i> in predicting prognosis of patients with stage II and III colorectal cancer (CRC).</p><p>Methods</p><p>Real-Time quantitative PCR was performed in 64 fresh CRC tissues and 6 cell lines to examine <i>TCF3</i> mRNA expression. TCF3 protein expression dynamics were detected by immunohistochemistry of 118 paraffin-embedded specimens, and the clinical significance of TCF3 was assessed by clinical correlation and Kaplan-Meier analyses. Aberrant hypomethylation of <i>TCF3</i> promoter was also investigated using bisulfite sequencing and methylation specific PCR.</p><p>Results</p><p>The up-regulation of <i>TCF3</i> mRNA was frequently detected both in CRC tissues with recurrence and metastasis-derived cell lines. The expression level of TCF3 protein was significantly correlated with histological type (<i>P</i> = 0.038) and disease-free survival time (<i>P</i> = 0.002). Higher TCF3 expression indicated poor prognostic outcomes (<i>P</i><0.05, log-rank test). Multivariate analysis also showed strong TCF3 protein expression and perineural invasion were independent adverse prognosticators in CRC (<i>P</i> = 0.010, 0.000). Moreover, it was showed that promoter hypomethylation of <i>TCF3</i> is associated with its up-expression.</p><p>Conclusions</p><p>This study highlighted the prognostic value of <i>TCF3</i> in stage II and III CRC. The up-regulation of <i>TCF3</i>, which is mainly caused by promoter hypomethylation, is one of the molecular mechanisms involved in the development and progression of CRC.</p></div

Correlation TCF3 expression with recurrence in CRC.

<p>Fisher's exact test, <i>P</i> = 0.002.</p><p>Correlation TCF3 expression with recurrence in CRC.</p

Methylation-specific PCR (MSP) analysis of <i>TCF3</i> promoter region in 24 CRC without recurrence (a) and 23 with recurrence (b).

<p>M, methylated allele; U, unmethylated allele. (c) Inverse correlation between <i>TCF3</i> promoter methylation status and gene expression level by qPCR analysis of <i>TCF3</i> expression in the 47 CRC tissues. The bar represents the ratio of <i>TCF3</i> and <i>GAPDH</i> mRNA expression levels. <i>TCF3</i> expression levels correlated with the methylation status of the gene (<i>P</i> = 0.001, Mann-Whitney U test).</p

The flow chart of the included studies.

<p>The flow chart of the included studies.</p

Meta-Analysis of Cytochrome P-450 2C9 Polymorphism and Colorectal Cancer Risk

<div><h3>Background</h3><p>CYP2C9 encodes a member of the cytochrome P450 superfamily of enzymes which play a central role in activating and detoxifying many carcinogens and endogenous compounds thought to be involved in the development of colorectal cancer (CRC). In the past decade, the relationship between CYP2C9 common polymorphisms (R144C and I359L) and CRC has been reported in various ethnic groups; however, these studies have yielded contradictory results. To investigate this inconsistency, we performed this meta-analysis.</p> <h3>Methods</h3><p>Databases including Pubmed, EMBASE, Web of Science and China National Knowledge Infrastructure (CNKI) were searched to find relevant studies. Odds ratios (ORs) with 95% confidence intervals (CIs) were used to assess the strength of association.</p> <h3>Results</h3><p>A total of 13 articles involving 9,463 cases and 11,416 controls were included. Overall, the summary odds ratio of CRC was 0.98 (95% CI: 0.89−1.06) and 0.99 (95% CI: 0.87−1.14) for CYP2C9 144C and 359L alleles, respectively. No significant results were observed using dominant or recessive genetic model for these polymorphisms. In the stratified analyses according to ethnicity and sex, no evidence of any gene-disease association was obtained.</p> <h3>Conclusions</h3><p>This meta-analysis suggests that the CYP2C9 may not be associated with colorectal cancer development.</p> </div

Univariate and multivariate analyses of disease-free survival in stage II/III CRC.

<p>*Statistically significant, <i>P</i><0.05; CI, confidence interval.</p><p>Univariate and multivariate analyses of disease-free survival in stage II/III CRC.</p

Genomic architecture of the human <i>TCF3</i> gene.

<p>Location of the <i>TCF3</i> gene within human chromosome 19 (ch19p13.3). (a) Exon structure of the human <i>TCF3</i> gene. (b) Structure of the 5′ end of the <i>TCF3</i> gene. Graph of percent guanine (G) and cytosine (C) nucleotides across this region, location of the CpG dinucleotides within this region, and boundaries of the CpG island (shaded region). (c) Representative examples of the chromatograms of CpG sites obtained from bisulphite sequencing of the <i>TCF3</i> fragment in CRC without recurrence (d) and with recurrence (e, f).</p

Relationships between clinicopathologic features and TCF3 expression in colorectal cancer.

a<p><i>P</i> value are obtained from χ² test.</p><p>*Statistically significant, <i>P</i><0.05.</p><p>Relationships between clinicopathologic features and TCF3 expression in colorectal cancer.</p

Representatives of TCF3 expression in stage II and III CRC tissues detected by immunohistochemistry.

<p>Examples of the immunostaining of TCF3 at strong expression (a, b) and low expression (c, d) levels (magnification ×400).</p

Overexpression of TCF3 was associated with a poor survival rate in CRC.

<p>(a) Patients with high TCF3 expression (n = 44) showed a significantly poorer prognisis than those with low TCF3 expression (n = 74; <i>P</i><0.05; log-rank test). (b) Patients with perineural invasion (n = 17) showed significantly poorer prognisis than those without such invasion (n = 101; <i>P</i><0.05; log-rank test).</p