Yanlei Ma

Association Between Vitamin D and Risk of Colorectal Cancer: A Systematic Review of Prospective Studies

PURPOSE To conduct a systematic review of prospective studies assessing the association of vitamin D intake or blood levels of 25-hydroxyvitamin D [25(OH)D] with the risk of colorectal cancer using meta-analysis. METHODS Relevant studies were identified by a search of MEDLINE and EMBASE databases before October 2010 with no restrictions. We included prospective studies that reported relative risk (RR) estimates with 95% CIs for the association between vitamin D intake or blood 25(OH)D levels and the risk of colorectal, colon, or rectal cancer. Approximately 1,000,000 participants from several countries were included in this analysis. RESULTS Nine studies on vitamin D intake and nine studies on blood 25(OH)D levels were included in the meta-analysis. The pooled RRs of colorectal cancer for the highest versus lowest categories of vitamin D intake and blood 25(OH)D levels were 0.88 (95% CI, 0.80 to 0.96) and 0.67 (95% CI, 0.54 to 0.80), respectively. There was no heterogeneity among studies of vitamin D intake (P = .19) or among studies of blood 25(OH)D levels (P = .96). A 10 ng/mL increment in blood 25(OH)D level conferred an RR of 0.74 (95% CI, 0.63 to 0.89). CONCLUSION Vitamin D intake and blood 25(OH)D levels were inversely associated with the risk of colorectal cancer in this meta-analysis.

Obesity and Risk of Colorectal Cancer: A Systematic Review of Prospective Studies

Background Mounting evidence indicates that obesity may be associated with the risk of colorectal cancer (CRC). To conduct a systematic review of prospective studies assessing the association of obesity with the risk of CRC using meta-analysis. Methodology/Principal Findings Relevant studies were identified by a search of MEDLINE and EMBASE databases before January 2012, with no restrictions. We also reviewed reference lists from retrieved articles. We included prospective studies that reported relative risk (RR) estimates with 95% confidence intervals (CIs) for the association between general obesity [measured using body mass index (BMI)] or central obesity [measured using waist circumference (WC)] and the risk of colorectal, colon, or rectal cancer. Approximately 9, 000, 000 participants from several countries were included in this analysis. 41 studies on general obesity and 13 studies on central obesity were included in the meta-analysis. The pooled RRs of CRC for the obese vs. normal category of BMI were 1.334 (95% CI, 1.253–1.420), and the highest vs. lowest category of WC were 1.455 (95% CI, 1.327–1.596). There was heterogeneity among studies of BMI (P<0.001) but not among studies of WC (P = 0.323). Conclusions Both of general and central obesity were positively associated with the risk of CRC in this meta-analysis.

miR-150 as a potential biomarker associated with prognosis and therapeutic outcome in colorectal cancer

Background MicroRNAs (miRNA) have potential as prognostic biomarkers and therapeutic targets in cancer. A study was undertaken to investigate the association between miRNA expression patterns and the prognosis and therapeutic outcome of colorectal cancer (CRC). Methods miRNA expression profiling in tumour, adenoma and normal colorectal tissues was performed to identify tumour-related miRNAs in the course of colorectal malignant changes. Quantitative reverse transcription PCR (qRT-PCR) assays were used to measure tumour-related miRNA and to assess its association with survival and response to adjuvant chemotherapy in 239 patients. In addition, to validate the findings, associations of the tumour-related miRNA with clinical characteristics of CRC were analysed in 185 patients by in situ hybridisation (ISH) analysis. Results Only one miR-150 was found to show a decrease in expression levels in the three tissue groups (normal, adenoma and cancer tissue) in parallel with increasing carcinogenesis of the colorectal tissue. In both ISH and qRT-PCR analysis, tumour tissue had reduced levels of miR-150 expression compared with paired non-cancerous tissue, which indicated that the levels of miR-150 expression were associated with CRC. Moreover, patients whose tumours had low miR-150 expression had shorter survival and a worse response to adjuvant chemotherapy than patients whose tumours had high miRNA expression. Conclusions The miR-150 expression status of patients with CRC is associated with survival and response to adjuvant chemotherapy. It is suggested that miR-150 should be considered as a potential biomarker associated with the prognosis and therapeutic outcome in CRC.

Candidate microRNA biomarkers in human colorectal cancer: Systematic review profiling studies and experimental validation†

Colorectal cancer (CRC) is a major cause of cancer mortality worldwide. There is an urgent need to search for specific and sensitive biomarkers for early diagnosis of CRC. We carried out a comprehensive systematic review of published studies that compared the miRNA expression profiles between CRC tissue and paired neighboring noncancerous colorectal tissue to determine candidate miRNA biomarkers for CRC. A miRNA ranking system that takes the number of comparisons in agreement, total study sizes and direction of differential expression into the consideration was devised and used. One of the most up‐regulated miRNAs, miRNA‐106a, was consistently reported to be differentially expressed in six studies and the five most down‐regulated miRNAs, miR‐30a‐3p, miR‐139, miR‐145, miR‐125a and miR‐133a, were consistently reported to be differentially expressed in four studies. Moreover, we further validated five miRNAs in a clinical setting using qRT‐PCR, which demonstrated that miR‐106a expression was increased, whereas the expression of miR‐30a‐3p, miR‐145, miR‐125a and miR‐133a was decreased in the CRC tissues. Therefore, these miRNAs may be the candidates to develop a panel of biomarkers with sufficient sensitivity and specificity for the diagnosis of CRC in a clinical setting.

Proteomics Identification of Desmin as a Potential Oncofetal Diagnostic and Prognostic Biomarker in Colorectal Cancer

Colorectal cancer (CRC) is the third most common cancer worldwide and has poor prognosis. To identify the oncofetal proteins involved in CRC carcinogenesis, differentially expressed proteins among fetal colorectal tissues, CRC, and the paired tumor-adjacent normal colorectal tissues were investigated by a two-dimensional gel electrophoresis and MALDI-TOF/TOF-based proteomics approach. 42 protein spots were differentially expressed among these tissues, and 22 proteins were identified by MS analysis. Desmin and zinc finger protein 829 were found to be elevated in CRC tissue and fetal colorectal tissue compared with normal colorectal tissue. The elevated expression of desmin in CRC tissue and different developmental stages of fetus colon was confirmed by RT-PCR and Western blot analysis. Immunohistochemical analysis showed that the elevated expression of desmin was correlated with the severity and differentiation of CRC and decreased survival rate of CRC patients. Finally by developing a highly sensitive immunoassay, desmin could be detected in human serum and was significantly elevated in CRC patients compared with healthy volunteers. We propose that desmin be considered a potential oncofetal serum tumor marker for CRC that may have significance in the detection of patients with CRC.

SP1 mediates the link between methylation of the tumour suppressor miR-149 and outcome in colorectal cancer.

Although recent studies indicate that DNA methylation contributes to the down‐regulation of microRNAs (miRNAs) in colorectal cancer (CRC), this field remains largely unexplored. To identify methylation‐silenced miRNAs and clarify their role in CRC, we performed a microarray analysis and screened for miRNAs that were induced in CRC cells by 5‐aza‐2′‐deoxycytidine treatment or by the knockdown of DNA methyltransferases. The DNA methylation status of the candidate miRNA was analysed by bisulphite sequencing PCR and methylation‐specific PCR. We found that miRNA‐149 (miR‐149) was epigenetically silenced in CRC and down‐regulation of miR‐149 was associated with hypermethylation of the neighbouring CpG island (CGI). Quantitative RT‐PCR analysis demonstrated that the miR‐149 level was markedly reduced in 51.6% of the CRC tissues compared with matched non‐cancerous tissues. In addition, low expression of miR‐149 was associated with a greater depth of invasion (

SP1 mediates the link between methylation of the tumour suppressor miR-149 and outcome in colorectal cancerlSUPg†l/SUPg

\it{p} = 0.012

Elevated oncofoetal miR-17-5p expression regulates colorectal cancer progression by repressing its target gene P130

), lower 5‐year survival rate (

Human embryonic stem cells and metastatic colorectal cancer cells shared the common endogenous human microRNA-26b

\it{p} = 0.025

Circular RNA ciRS-7—A Promising Prognostic Biomarker and a Potential Therapeutic Target in Colorectal Cancer

), and was found to be an independent prognostic factor for overall survival (