Fecal cyclooxygenase 2 plus matrix metalloproteinase 7 mRNA assays as a marker for colorectal cancer screening

REducing Colonoscopies in patients without significant bowEl DiseasE: the RECEDE Study - protocol for a prospective diagnostic accuracy study

INTRODUCTION

Demand for colonoscopies and CT colonography (CTC) is exceeding capacity in National Health Service Trusts. In many patients colonoscopies and CTCs show no significant bowel disease (SBD). Faecal Immunochemical Testing (FIT) is being introduced to prioritise patients for colonoscopies but is insufficient to identify non-SBD patients meaning colonoscopy and CTC demand remains high. The REducing Colonoscopies in patients without significant bowEl DiseasE (RECEDE) study aims to test urine volatile organic compound (VOC) analysis alongside FIT to improve detection of SBD and to reduce the number of colonoscopies and CTCs.

METHODS AND ANALYSIS

This is a multicentre, prospective diagnostic accuracy study evaluating whether stool FIT plus urine VOC compared with stool FIT alone improves detection of SBD in patients referred for colonoscopy or CTC due to persistent lower gastrointestinal symptoms. To ensure SBD is not missed, the dual test requires a high sensitivity, set at 97% with 95% CI width of 5%. Our assumption is that to achieve this sensitivity requires 200 participants with SBD. Further assuming 19% of all participants will have SBD and 55% of all participants will return both stool and urine samples we will recruit 1915 participants. The thresholds for FIT and VOC results diagnosing SBD have been pre-set. If either FIT or VOC exceeds the respective threshold, the participant will be classed as having suspected SBD. As an exploratory analysis we will be testing different thresholds. The reference comparator will be a complete colonoscopy or CTC. Secondary outcomes will look at optimising the FIT and VOC thresholds for SBD detection. An economic evaluation, using a denovo decision analytic model, will be carried out determine the costs, benefits and overall cost-effectiveness of FIT +VOC vs FIT followed by colonoscopy.

ETHICS AND DISSEMINATION

Ethical approval was obtained by Liverpool Central Research Ethics Committee (20/NW/0346).

TRIAL REGISTRATION NUMBER

RECEDE is registered on Clinicaltrials.gov NCT04516785 & ISRCTN14982373. This protocol was written and published before results of the trial were available.

piRNA-823 Is a Unique Potential Diagnostic Non-Invasive Biomarker in Colorectal Cancer Patients

Early detection of colorectal cancer (CRC) is the most important factor in deciding its prognosis, so the need to develop an accurate screening test is a must. P-element induced wimpy testis (PIWI) RNA-823 (piR-823) is one of the first piRNAs recognized to be linked to malignancy. We aimed to investigate the expression levels of piR-823 in both serum and tissues of colorectal cancer patients and the ability to use its serum level as a non-invasive diagnostic biomarker to detect colorectal cancer. We determined piR-823 expression levels in 84 serum samples of CRC patients, 75 serum samples of healthy controls, and biological specimens obtained from the 84 patients with colorectal cancer from both the tumor tissues and the normal neighboring tissues using quantitative real-time reverse transcriptase-PCR. We showed that piR-823 had significantly higher serum and tissue expression levels in CRC patients compared to the controls. We observed a significant positive correlation between piR-823 serum levels and the staging of CRC, with significantly higher levels exhibiting advanced stages of CRC (III and IV). This translates into poorer differentiation and lymph node metastasis. The receiver operating characteristic curve (ROC curve) test showed 83.3% sensitivity and 89.3% specificity at a cut-off value of >5.98-fold change, with an area under the curve of 0.933 (p < 0.0001) concerning the ability of piR-823 in diagnosing patients with colorectal carcinoma. piR-823 expression is upregulated in colorectal cancer patients’ serum and tissues, and it can be used as a diagnostic noninvasive biomarker for CRC.

Multitarget Stool mRNA Test for Detecting Colorectal Cancer Lesions Including Advanced Adenomas

Current approved non-invasive screening methods for colorectal cancer (CRC) include FIT and DNA-FIT testing, but their efficacy for detecting precancerous lesions that are susceptible to progressing to CRC such as advanced adenomas (AA) remains limited, thus requiring further options to improve the detection of CRC lesions at earlier stages. One of these is host mRNA stool testing. The aims of the present study were to identify specific stool mRNA targets that can predict AA and to investigate their stability under a clinical-like setting. A panel of mRNA targets was tested on stool samples obtained from 102 patients including 78 CRC stage I-III and 24 AA as well as 32 healthy controls. Area under the receiver operating characteristic (ROC) curves were calculated to establish sensitivities and specificities for individual and combined targets. Stability experiments were performed on freshly obtained specimens. Six of the tested targets were found to be specifically increased in the stools of patients with CRC and three in the stools of both AA and CRC patients. After optimization for the choice of the 5 best markers for AA and CRC, ROC curve analysis revealed overall sensitivities of 75% and 89% for AA and CRC, respectively, for a ≥95% specificity, and up to 75% and 95% for AA and CRC, respectively, when combined with the FIT score. Targets were found to be stable in the stools up to 3 days at room temperature. In conclusion, these studies show that the detection of host mRNA in the stools is a valid approach for the screening of colorectal cancerous lesions at all stages and is applicable to a clinical-like setup.

Graphene Oxide-Based Suppression of Nonspecificity in Loop-Mediated Isothermal Amplification Enabling the Sensitive Detection of Cyclooxygenase-2 mRNA in Colorectal Cancer

Cyclooxygenase-2 (COX2) mRNA represents a key biomarker for identifying subjects with colorectal cancer (CRC), while there is still no rapid and sensitive detection method for COX2 mRNA. Loop-mediated isothermal amplification (LAMP) is extensively developed for the amplification of nucleic acids; however, its application is frequently hindered by serious nonspecific amplification. Herein, this work reported a graphene oxide (GO)-based LAMP method to enable the one-step detection of COX2 mRNA in cancer cells and serum samples. We found that GO greatly enhanced the specificity of LAMP through decreasing nonspecific hybridization and the fluorescence background signal because of the simultaneous adsorption of single-stranded primers and DNA staining dyes on GO. The detection limit of developed GO-based LAMP was 2 orders of magnitude more sensitive compared to that of classical LAMP. Then a GO-based reverse transcription (RT)-LAMP strategy was further developed and applied to detect COX2 mRNA in CRC cancer cells and serum samples with high specificity. The GO-based LAMP platform with advantages of low cost, simplicity, high specificity, and sensitivity holds considerable potential for real-time fluorescence monitoring of nucleic acid amplification in a wide range of fields.

Circulating PIWI-Interacting RNAs piR-5937 and piR-28876 Are Promising Diagnostic Biomarkers of Colon Cancer

Background: The early detection of colon cancer is one of the main prerequisites for successful treatment and mortality reduction. Circulating PIWI-interacting RNAs (piRNA) were recently identified as novel promising biomarkers. The purpose of the study was to assess the profiles of piRNAs in blood serum of colon cancer patients with the aim to identify those with high diagnostic potential.Methods: Blood serum samples from 403 colon cancer patients and 276 healthy donors were included in this 3-phase biomarker study. Large-scale piRNA expression profiling was performed using Illumina small RNA sequencing. The diagnostic potential of selected piRNAs was further validated on independent training and validation sets of samples using RT-qPCR.Results: In total, 31 piRNAs were found to be significantly deregulated in serum of cancer patients compared with healthy donors. Based on the levels of piR-5937 and piR-28876, it was possible to differentiate between cancer patients and healthy donors with high sensitivity and specificity. Moreover, both piRNAs exhibited satisfactory diagnostic performance also in patients with stage I disease and enabled detection of colon cancer with higher sensitivity than currently used biomarkers CEA and CA19-9. Finally, the expression of analyzed piRNAs in blood restored significantly 1 month after the surgical resection.Conclusions: Based on our findings, piRNAs are abundant in human blood serum. Furthermore, their levels in colon cancer have been observed to be significantly deregulated. However, their involvement in carcinogenesis must be further established.Impact: piRNAs could serve as promising noninvasive biomarkers for early detection of colon cancer. Cancer Epidemiol Biomarkers Prev; 27(9); 1019-28. ©2018 AACR.

Improving diagnosis, prognosis and prediction by using biomarkers in CRC patients (Review)

Colorectal cancer (CRC) is among the most common cancers. In fact, it is placed in the third place among the most diagnosed cancer in men, after lung and prostate cancer, and in the second one for the most diagnosed cancer in women, following breast cancer. Moreover, its high mortality rates classifies it among the leading causes of cancer‑related death worldwide. Thus, in order to help clinicians to optimize their practice, it is crucial to introduce more effective tools that will improve not only early diagnosis, but also prediction of the most likely progression of the disease and response to chemotherapy. In that way, they will be able to decrease both morbidity and mortality of their patients. In accordance with that, colon cancer research has described numerous biomarkers for diagnostic, prognostic and predictive purposes that either alone or as part of a panel would help improve patient's clinical management. This review aims to describe the most accepted biomarkers among those proposed for use in CRC divided based on the clinical specimen that is examined (tissue, faeces or blood) along with their restrictions. Lastly, new insight in CRC monitoring will be discussed presenting promising emerging biomarkers (telomerase activity, telomere length and micronuclei frequency).

Droplet digital PCR for quantification of ITGA6 in a stool mRNA assay for the detection of colorectal cancers

AIM

To investigate the use of droplet digital polymerase chain reaction (ddPCR) for detecting host mRNA markers in stools as a non-invasive test for colorectal cancer screening.

METHODS

ddPCR and quantitative PCR were compared side by side for their performance in the detection of ITGA6 and ITGA6A transcripts in stool samples obtained from patients with various types of colorectal lesions (advanced adenomas and stage II-IV colorectal cancers) and control (patients displaying no pathological findings) using duplex TaqMan reactions for both methods. ITGA6 and ITGA6A were chosen for this proof-of-concept study based on their relative medium and low abundance in stool samples, respectively, as established in a previous study.

RESULTS

We found that the ddPCR and qPCR methods performed equally well in this TaqMan duplex assay for the detection of ITGA6 and ITGA6A transcripts in stools of patients with colorectal lesions. For ITGA6, receiver operating characteristic (ROC) curve analysis showed comparable areas under the curve of 0.91 (P < 0.0001) and 0.89-0.90 (P < 0.0001) for the prediction of advanced adenomas and colorectal cancers, respectively. ITGA6A, which was detected at very low levels in control patients, was found to be significantly elevated (over 40 times) in stage II and III colorectal cancers (P < 0.0002). Comparison of the two sets of data revealed a strong correlation of the copy numbers obtained by ddPCR and qPCR for both ITGA6 and ITGA6A.

CONCLUSION

We found that ITGA6 and ITGA6A detection in stools of patients with colorectal cancers with ddPCR is comparable to that of qPCR using TaqMan assays.

Colorectal adenoma and carcinoma specific miRNA profiles in biopsy and their expression in plasma specimens

BACKGROUND

MiRNA expression markers are well characterized in colorectal cancer (CRC), but less is known about miRNA expression profiles in colorectal adenomas. Genome-wide miRNA and mRNA expression analyses were conducted through the colorectal adenoma dysplasia sequence. Furthermore, analysis of the expression levels of miRNAs in matched plasma samples was performed, focusing on biomarker candidates; miRNA and mRNA expression analyses were performed on colorectal biopsies and plasma samples (20 normals; 11 tubular and 9 tubulovillous adenomas; 20 colorectal carcinomas) by miRNA 3.0 and Human Transcriptome Array (Affymetrix) and validated by RT-qPCR. Microarray data were analyzed using Expression Console and mRNA targets were predicted using miRWALK 2.0.

RESULTS

Based on microarray analysis, 447 miRNAs were expressed in tissue and 320 in plasma. Twelve were upregulated (miR-31, 8-fold p < 0.001) and 11 were downregulated (miR-10b 3-fold p < 0.001) in neoplastic lesions compared to normal group. Eleven miRNAs showed altered expression between adenoma subtypes (miR-183 2.8-fold change, p < 0.007). Expression level of 24 miRNAs differed between adenoma and CRC groups (including miR-196a, 3.5-fold). Three miRNAs (miR-31, miR-4506, miR-452*) were differentially expressed in adenoma compared to normal both in tissue and plasma samples. miRNA expression data were confirmed by RT-PCR both in plasma and matched tissue samples.

CONCLUSIONS

MiRNAs showed characteristic expression changes during CRC development in tissue. miRNAs were also presented in plasma and positively correlated with matched tissue expression levels. The identified miRNA expression changes could be verified RT-PCR methods facilitating routine application.

Colorectal Carcinoma: A General Overview and Future Perspectives in Colorectal Cancer

Colorectal cancer (CRC) is the third most common cancer and the fourth most common cause of cancer-related death. Most cases of CRC are detected in Western countries, with its incidence increasing year by year. The probability of suffering from colorectal cancer is about 4%–5% and the risk for developing CRC is associated with personal features or habits such as age, chronic disease history and lifestyle. In this context, the gut microbiota has a relevant role, and dysbiosis situations can induce colonic carcinogenesis through a chronic inflammation mechanism. Some of the bacteria responsible for this multiphase process include Fusobacterium spp, Bacteroides fragilis and enteropathogenic Escherichia coli. CRC is caused by mutations that target oncogenes, tumour suppressor genes and genes related to DNA repair mechanisms. Depending on the origin of the mutation, colorectal carcinomas can be classified as sporadic (70%); inherited (5%) and familial (25%). The pathogenic mechanisms leading to this situation can be included in three types, namely chromosomal instability (CIN), microsatellite instability (MSI) and CpG island methylator phenotype (CIMP). Within these types of CRC, common mutations, chromosomal changes and translocations have been reported to affect important pathways (WNT, MAPK/PI3K, TGF-β, TP53), and mutations; in particular, genes such as c-MYC, KRAS, BRAF, PIK3CA, PTEN, SMAD2 and SMAD4 can be used as predictive markers for patient outcome. In addition to gene mutations, alterations in ncRNAs, such as lncRNA or miRNA, can also contribute to different steps of the carcinogenesis process and have a predictive value when used as biomarkers. In consequence, different panels of genes and mRNA are being developed to improve prognosis and treatment selection. The choice of first-line treatment in CRC follows a multimodal approach based on tumour-related characteristics and usually comprises surgical resection followed by chemotherapy combined with monoclonal antibodies or proteins against vascular endothelial growth factor (VEGF) and epidermal growth receptor (EGFR). Besides traditional chemotherapy, alternative therapies (such as agarose tumour macrobeads, anti-inflammatory drugs, probiotics, and gold-based drugs) are currently being studied to increase treatment effectiveness and reduce side effects.

The expression and significance of feces cyclooxygensae-2 mRNA in colorectal cancer and colorectal adenomas

BACKGROUND/AIM

This study aims to explore the expression and significance of feces cyclooxygensae-2 (COX-2) mRNA in colorectal cancer and colorectal adenomas.

MATERIALS AND METHODS

The expression of feces COX-2 mRNA in colorectal cancer (n = 28), colorectal adenomas (n = 54), and normal control group (n = 11) were examined by reverse transcriptase polymerase chain reaction (RT-PCR). The positive rate of fecal occult blood test (FOBT) were detected in colorectal cancer (n = 30), colorectal adenomas (n = 56), and normal control group (n = 11); the sensitivity of the two methods was also compared.

RESULTS

The positive rate of feces COX-2 mRNA in colorectal cancer was 82.1% (25/28), which was significantly higher than colorectal adenomas 59.3% (32/54), and normal tissues 18.2% (2/11), the difference being significant between the three groups (χ2= 13.842,P= 0.001). The positive rate of FOBT in colorectal cancer was 73.3% (10/30), which was significantly higher than colorectal adenomas 10.7% (6/56) and normal tissues 9.1% (1/11), the difference being significant between these three groups (χ2= 7.525,P= 0.023). There was no significant association between feces COX-2 expression and various clinical pathological features of colorectal cancer and colorectal adenomas (P > 0.05). The sensitivity of the RT-PCR method is higher than FOBT, however, the specificity of FOBT is slightly higher than RT-PCR.

CONCLUSIONS

High expression of feces COX-2 mRNA in colorectal adenomas and colorectal cancer is a common event; it is an early event in the development of colorectal adenomas to colorectal cancer. Feces COX-2 mRNA has a high sensitivity for detect colorectal cancer; combination with FOBT will be the best alternative. Feces COX-2 can be potentially used in the early diagnosis and screening of colorectal cancer.

Expression of young HERV-H loci in the course of colorectal carcinoma and correlation with molecular subtypes

Background

Expression of the human endogenous retrovirus (HERV)-H family has been associated with colorectal carcinomas (CRC), yet no individual HERV-H locus expression has been thoroughly correlated with clinical data.

Here, we characterized HERV-H reactivations in clinical CRC samples by integrating expression profiles, molecular patterns and clinical data. Expression of relevant HERV-H sequences was analyzed by qRT-PCR on two well-defined clinical cohorts (n = 139 pairs of tumor and adjacent normal colon tissue) including samples from adenomas (n = 21) and liver metastases (n = 16). Correlations with clinical and molecular data were assessed.

Results

CRC specific HERV-H sequences were validated and found expressed throughout CRC disease progression. Correlations between HERV-H expression and lymph node invasion of tumor cells (p = 0.0006) as well as microsatellite instable tumors (p < 0.0001) were established. No association with regard to age, tumor localization, grading or common mutations became apparent. Interestingly, CRC expressed elements belonged to specific young HERV-H subfamilies and their 5′ LTR often presented active histone marks.

Conclusion

These results suggest a functional role of HERV-H sequences in colorectal carcinogenesis. The pronounced connection with microsatellite instability warrants a more detailed investigation. Thus, HERV-H sequences in addition to tumor specific mutations may represent clinically relevant, truly CRC specific markers for diagnostic, prognostic and therapeutic purposes.

Discovery of genes from feces correlated with colorectal cancer progression

Colorectal cancer (CRC) is considered to develop slowly via a progressive accumulation of genetic mutations. Markers of CRC may serve to provide the basis for decision-making, and may assist in cancer prevention, detection and prognostic prediction. DNA and messenger (m)RNA molecules that are present in human feces faithfully represent CRC manifestations. In the present study, exogenous mouse cells verified the feasibility of total fecal RNA as a marker of CRC. Furthermore, five significant genes encoding solute carrier family 15, member 4 (SLC15A4), cluster of differentiation (CD)44, 3-oxoacid CoA-transferase 1 (OXCT1), placenta-specific 8 (PLAC8) and growth arrest-specific 2 (GAS2), which are differentially expressed in the feces of CRC patients, were verified in different CRC cell lines using quantitative polymerase chain reaction. The present study demonstrated that the mRNA level of SLC15A4 was increased in the majority of CRC cell lines evaluated (SW1116, LS123, Caco-2 and T84). An increased level of CD44 mRNA was only detected in an early-stage CRC cell line, SW1116, whereas OXCT1 was expressed at higher levels in the metastatic CRC cell line CC-M3. In addition, two genes, PLAC8 and GAS2, were highly expressed in the recurrent CRC cell line SW620. Genes identified in the feces of CRC patients differed according to their clinical characteristics, and this differential expression was also detected in the corresponding CRC cell lines. In conclusion, feces represent a good marker of CRC and can be interpreted through the appropriate CRC cell lines.

Upregulation of the growth arrest-specific-2 in recurrent colorectal cancers, and its susceptibility to chemotherapy in a model cell system

Colorectal cancer (CRC) is one of the most common life-threatening malignances worldwide. CRC relapse markedly decreases the 5-year survival of patients following surgery. Aberrant expression of genes involved in pathways regulating the cell cycle, cell proliferation, or cell death are frequently reported in CRC tumorigenesis. We hypothesized that genes involved in CRC relapse might serve as prognostic indicators. We first evaluated the significance of gene sequences in the feces of patients with CRC relapse by consulting a public database. Tumorigenesis of target tissues was tested through tumor cell growth, cell cycle regulation, and chemotherapeutic efficacy. We found a highly significant correlation between CRC relapse and growth arrest-specific 2 (GAS2) gene expression. Based on cell models, the overexpressed GAS2 was associated with cellular growth rate, cell cycle regulation, and with chemotherapeutic sensitivity. Cell division was impaired by treating cells with 2-[4-(7-chloro-2-quinoxalinyloxy)phenoxy]-propionic acid (XK469), even when the cells were overexpressing GAS2. Thus, downregulation of GAS2 expression might control CRC relapse after curative resection. GAS2 could serve as a noninvasive marker from the feces of patients with prediagnosed CRC. Our findings suggest that GAS2 could have potential clinical applications for predicting early CRC relapse after radical resection, and that XK469 might impair tumor cell division by reducing GAS2 expression or blocking its cellular translocation. This will help in selecting the best therapeutic option, 5-fluorouracil in combination with XK469, for patients overexpressing GAS2 in CRC cells. Thus, GAS2 might act as a prognostic biomolecule and potential therapeutic target in patients with CRC relapse.

Use of integrin alpha 6 transcripts in a stool mRNA assay for the detection of colorectal cancers at curable stages

OBJECTIVE

An important criterion for colorectal cancer (CRC) screening is the ability to detect lesions at a curable stage. In the present study, we have assessed the integrin α6 subunit transcript (ITGA6) as part of a stool assay for the detection of colorectal lesions.

RESULTS

In comparison with control samples, ITGA6 levels were found to be significantly increased at all stages (P < 0.01). Receiver operating characteristic analysis revealed areas under the curve of 0.89 for the prediction of CRC with 81% sensitivity and 88% specificity and of 0.90 for the prediction of advanced adenomas (Ad) with 75% sensitivity and 88% specificity. The ITGA6A variant was also found to be increased relative to ITGA6 in stage II and III CRCs. Combining ITGA6 with other selected transcripts and/or immunochemical fecal occult blood test (iFOBT) results further increased sensitivity and specificity for the detection of colorectal lesions.

PATIENTS AND METHODS

ITGA6 detection used alone and under various combinations including detection of other mRNA markers and iFOBT was assessed on stool samples obtained from 175 patients (91 CRCs, 24 Ad and 60 healthy controls).

CONCLUSIONS

These data confirm the usefulness and reliability of an mRNA stool assay for the detection of colorectal lesions. The validation of additional candidate genes and their analysis in multiplex qPCR represents a powerful and robust approach that can be combined with iFOBT results to improve the detection of colorectal lesions.

Molecular markers for colorectal cancer screening

Colorectal cancer (CRC), although a significant cause of morbidity and mortality worldwide, has seen a declining incidence and mortality in countries with programmatic screening. Faecal occult blood testing and endoscopic approaches are the predominant screening methods currently. The discovery of the adenoma-carcinoma sequence and a greater understanding of the genetic and epigenetic changes that drive the formation of CRC have contributed to innovative research to identify molecular markers for highly accurate, non-invasive screening tests for CRC. DNA, proteins, messenger RNA and micro-RNA have all been evaluated. The observation of tumour cell exfoliation into the mucocellular layer of the colonic epithelium and proven stability of DNA in a harsh stool environment make stool DNA a particularly promising marker. The development of a clinically useful stool DNA test has required numerous technical advances, including optimisation in DNA stabilisation, the development of assays with high analytical sensitivity, and the identification of specific and broadly informative molecular markers. A multitarget stool DNA test, which combines mutant and methylated DNA markers and a faecal immunochemical test, recently performed favourably in a large cross-sectional validation study and has been approved by the US Food and Drug Administration for the screening of asymptomatic, average-risk individuals. The ultimate way in which molecular marker screening assays will be used in clinical practice will require additional studies to determine optimal screening intervals, factors affecting compliance, management of false-positive results, and the use of these assays in high-risk populations, as well as other considerations.

Colorectal Cancer Biomarkers: Where Are We Now?

Colorectal cancer is one of the major causes of cancer-related death in the Western world. Patient survival is highly dependent on the tumor stage at the time of diagnosis. Reduced sensitivity to chemotherapy is still a major obstacle in effective treatment of advanced disease. Due to the fact that colorectal cancer is mostly asymptomatic until it progresses to advanced stages, the implementation of screening programs aimed at early detection is essential to reduce incidence and mortality rates. Current screening and diagnostic methods range from semi-invasive procedures such as colonoscopy to noninvasive stool-based tests. The combination of the absence of symptoms, the semi-invasive nature of currently used methods, and the suboptimal accuracy of fecal blood tests results in colorectal cancer diagnosis at advanced stages in a significant number of individuals. Alterations in gene expression leading to colorectal carcinogenesis are reflected in dysregulated levels of nucleic acids and proteins, which can be used for the development of novel, minimally invasive molecular biomarkers. The purpose of this review is to discuss the commercially available colorectal cancer molecular diagnostic methods as well as to highlight some of the new candidate predictive and prognostic molecular markers for tumor, stool, and blood samples.

An update on microRNAs as colorectal cancer biomarkers: where are we and what's next?

miRNAs are abundant classes of small, endogenous non-coding RNAs, which inhibit the expression of target gene via post-transcriptional regulation. In addition to an important functional role miRNAs play in carcinogenesis, emerging evidence has demonstrated their feasibility as robust cancer biomarkers. In particular, the recent discovery of miRNAs in the body fluids provides an attractive opportunity for the development of non-invasive biomarkers for the diagnosis, prognosis and predictive response to cancer therapy. Colorectal cancer (CRC) is one of the most common cancers worldwide, and accumulating data provides a compelling case for the potential exploitation of miRNAs as CRC-biomarkers. This review summarizes the current state of literature in the field, focusing on the clinical relevance of miRNAs as potential biomarkers for CRC treatment and discussing the forthcoming challenges to further advance this exciting field of 'academic research' into 'bedside clinical care' of patients suffering from CRC.

A predictive model combining fecal calgranulin B and fecal occult blood tests can improve the diagnosis of colorectal cancer

AIM

Current fecal screening tools for colorectal cancer (CRC), such as fecal occult blood tests (FOBT), are limited by their low sensitivity. Calgranulin B (CALB) was previously reported as a candidate fecal marker for CRC. This study investigated whether a combination of the FOBT and fecal CALB has increased sensitivity and specificity for a diagnosis of CRC.

MATERIALS AND METHODS

Patients with CRC (n = 175), and healthy individuals (controls; n = 151) were enrolled into the development (81 cases and 51 controls) and validation (94 cases and 100 controls) sets. Stool samples were collected before bowel preparation. CALB levels were determined by western blotting. FOBT and fecal CALB results were used to develop a predictive model based on logistic regression analysis. The benefit of adding CALB to a model with only FOBT was evaluated as an increased area under the receiver operating curve (AUC), partial AUC, and reclassification improvement (RI) in cases and controls, and net reclassification improvement (NRI).

RESULTS

Mean CALB level was significantly higher in CRC patients than in controls (P<0.001). CALB was not associated with tumor stage or cancer site, but positivity on the FOBT was significantly higher in advanced than in earlier tumor stages. At a specificity of 90%, the cross-validated AUC and sensitivity were 89.81% and 82.72%, respectively, in the development set, and 92.74% and 79.79%, respectively, in the validation set. The incremental benefit of adding CALB to the model, as shown by the increase in AUC, had a p-value of 0.0499. RI in cases and controls and NRI all revealed that adding CALB significantly improved the prediction model.

CONCLUSION

A predictive model using a combination of FOBT and CALB may have greater sensitivity and specificity and AUC for predicting CRC than models using a single marker.

Biomarkers for early detection of colorectal cancer and polyps: systematic review

There is growing interest in early detection of colorectal cancer as current screening modalities lack compliance and specificity. This study systematically reviewed the literature to identify biomarkers for early detection of colorectal cancer and polyps. Literature searches were conducted for relevant papers since 2007. Human studies reporting on early detection of colorectal cancer and polyps using biomarkers were included. Methodologic quality was evaluated, and sensitivity, specificity, and the positive predictive value (PPV) were reported. The search strategy identified 3,348 abstracts. A total of 44 papers, examining 67 different tumor markers, were included. Overall sensitivities for colorectal cancer detection by fecal DNA markers ranged from 53% to 87%. Combining fecal DNA markers increased the sensitivity of colorectal cancer and adenoma detection. Canine scent detection had a sensitivity of detecting colorectal cancer of 99% and specificity of 97%. The PPV of immunochemical fecal occult blood test (iFOBT) is 1.26%, compared with 0.31% for the current screening method of guaiac fecal occult blood test (gFOBT). A panel of serum protein biomarkers provides a sensitivity and specificity above 85% for all stages of colorectal cancer, and a PPV of 0.72%. Combinations of fecal and serum biomarkers produce higher sensitivities, specificities, and PPVs for early detection of colorectal cancer and adenomas. Further research is required to validate these biomarkers in a well-structured population-based study.

Colorectal cancer: from prevention to personalized medicine

Colorectal cancer (CRC) is a very heterogeneous disease that is caused by the interaction of genetic and environmental factors. CRC develops through a gradual accumulation of genetic and epigenetic changes, leading to the transformation of normal colonic mucosa into invasive cancer. CRC is one of the most prevalent and incident cancers worldwide, as well as one of the most deadly. Approximately 1235108 people are diagnosed annually with CRC, and 609051 die from CRC annually. The World Health Organization estimates an increase of 77% in the number of newly diagnosed cases of CRC and an increase of 80% in deaths from CRC by 2030. The incidence of CRC can benefit from different strategies depending on its stage: health promotion through health education campaigns (when the disease is not yet present), the implementation of screening programs (for detection of the disease in its early stages), and the development of nearly personalized treatments according to both patient characteristics (age, sex) and the cancer itself (gene expression). Although there are different strategies for screening and although the number of such strategies is increasing due to the potential of emerging technologies in molecular marker application, not all strategies meet the criteria required for screening tests in population programs; the three most accepted tests are the fecal occult blood test (FOBT), colonoscopy and sigmoidoscopy. FOBT is the most used method for CRC screening worldwide and is also the primary choice in most population-based screening programs in Europe. Due to its non-invasive nature and low cost, it is one of the most accepted techniques by population. CRC is a very heterogeneous disease, and with a few exceptions (APC, p53, KRAS), most of the genes involved in CRC are observed in a small percentage of cases. The design of genetic and epigenetic marker panels that are able to provide maximum coverage in the diagnosis of colorectal neoplasia seems a reasonable strategy. In recent years, the use of DNA, RNA and protein markers in different biological samples has been explored as strategies for CRC diagnosis. Although there is not yet sufficient evidence to recommend the analysis of biomarkers such as DNA, RNA or proteins in the blood or stool, it is likely that given the quick progression of technology tools in molecular biology, increasingly sensitive and less expensive, these tools will gradually be employed in clinical practice and will likely be developed in mass.

Global fecal microRNA profiling in the identification of biomarkers for colorectal cancer screening among Asians

Fecal microRNAs (miRNAs) are increasingly explored as non-invasive markers of colorectal cancer (CRC). However, its holistic profile in Asian CRC patients remains elusive. In the present study, the global human fecal miRNAs in Asian Chinese CRC patients was assayed to elucidate novel diagnostic fecal markers. Additionally, the influence of blood in stool on fecal miRNA levels was investigated for the first time. Microarray analysis was applied to profile the fecal miRNAs extracted from CRC patients and healthy subjects. Concurrently, surgically resected tumor and matched normal mucosae were analyzed. Potential fecal miRNA markers were further confirmed using real-time PCR in 17 CRC patients and 28 healthy subjects. Global miRNA profiling uncovered 17 fecal markers (p<0.05) differentially regulated in CRC. Fecal miR-223 and miR-451 represented robust markers in distinguishing CRC patients from healthy subjects, as evident from areas under the receiver operator characteristic curves of 0.939 and 0.971, respectively. Blood in stool affected fecal miR-451, miR-223 and miR-135b levels to a varying extent and substantially impacted the interpretation of the clinical data. Notably, a discrete set of aberrant miRNAs occurred within the tumor, indicating the presence of contributors beyond the exfoliation of tumor cells to the fecal miRNA profile. In summary, the utility of a global miRNA screening approach was successfully demonstrated in elucidating diagnostic markers of CRC. In particular, fecal miR-223 and miR-451 hold promise in detecting CRC.

MMP-7 is upregulated by COX-2 and promotes proliferation and invasion of lung adenocarcinoma cells

Matrix metalloproteinases (MMPs) have been implicated in a variety of pathophysiological conditions, of which MMP-7 is expressed by tumor cells of epithelial and mesenchymal origin. However, the function of MMP-7 in human lung adenocarcinoma (LAC) is unclear. In the present study the expression of MMP-7 in LAC was examined by immunohistochemical assay using a tissue microarray procedure. A loss-of-function experiment was performed to explore the effects and molecular mechanisms of lentiviral vector-mediated MMP-7 siRNA (siMMP-7) on cell proliferation and invasive potential in LAC A549 cells, measured by MTT and Transwell assays, respectively. It was found that, the expression of MMP-7 protein in LAC was significantly increased compared with that in adjacent non-cancerous tissues (ANCT) (76.0% vs 44.0%, P<0.001), and positively correlated with lymph node metastases of the tumor (P=0.014). Furthermore, targeted inhibition of cyclooxygenase-2 (COX-2) by siRNA downregulated the expression of MMP-7 and inhibited invasion of LAC cells, and knockdown of MMP-7 suppressed tumor proliferation and invasion in LAC cells. Taken together, our findings indicate that increased expression of MMP-7 is associated with lymph node metastasis and upregulated by COX-2, and promotes the tumorigenesis of LAC, suggesting that MMP-7 may be a potential therapeutic target for the treatment of cancer.

Non-invasive fecal metabonomic detection of colorectal cancer

Colorectal cancer (CRC) is a major cause of mortality in many developed countries. Effective screening strategies were called for to facilitate timely detection and to promote a better clinical outcome. In this study, the role of fecal metabonomics in the non-invasive detection of CRC was investigated. Gas chromatography/time-of-flight mass spectrometry (GC/TOFMS) was utilized for the metabolic profiling of feces obtained from 11 CRC patients and 10 healthy subjects. Concurrently, matched tumor and normal mucosae surgically excised from CRC patients were profiled. CRC patients were differentiated clearly from healthy subjects based on their fecal metabonomic profiles (orthogonal partial least squares discriminant analysis [OPLS-DA], 1 predictive and 3 Y-orthogonal components, R (2)X = 0.373, R (2)Y = 0.995, Q (2) [cumulative] = 0.215). The robustness of the OPLS-DA model was demonstrated by an area of 1 under the receiver operator characteristic curve. OPLS-DA revealed fecal marker metabolites (e.g., fructose, linoleic acid, and nicotinic acid) that provided novel insights into the tumorigenesis of CRC. Interestingly, a disparate set of CRC-related metabolic aberrations occurred at the tissue level, implying the contribution of processes beyond the direct shedding of tumor cells to the fecal metabotype. In summary, this work established proof-of-principle for GC/TOFMS-based fecal metabonomic detection of CRC and offered new perspectives on the underlying mechanisms.

New molecular diagnosis and screening methods for colorectal cancer using fecal protein, DNA and RNA

Several screening methods for reducing the mortality rate of colorectal cancer (CRC) have been reported in recent decades. Fecal occult blood tests (FOBTs) are widely used for CRC screening and immunochemical FOBTs perform better than guaiac FOBTs; however, the sensitivity and specificity of immunochemical FOBTs remain unsatisfactory. To resolve this problem, novel fecal molecular methods based on fecal protein, DNA and RNA analyses have been developed. Regarding fecal proteins, several marker proteins indicating intestinal bleeding and cancer cell-specific proteins have been investigated. Regarding fecal DNA, numerous gene mutation and gene methylation analyses have been reported. Consequently, fecal DNA analysis was recommended as a CRC screening method in 2008. In addition, gene expression analyses of CRC-specific genes and miRNAs in fecal RNA have been investigated over the last decade. This review article summarizes molecular methods using fecal samples for CRC screening, focusing on reports within the last 5 years.

Fecal miR-106a is a useful marker for colorectal cancer patients with false-negative results in immunochemical fecal occult blood test

BACKGROUND

Immunochemical fecal occult blood test (iFOBT) is widely used for colorectal cancer screening; however, its sensitivity is insufficient. We recently reported a fecal microRNA (miRNA) test (FmiRT) to detect colorectal cancer. In this study, we investigated a new colorectal cancer screening method combining iFOBT and FmiRT to improve the sensitivity compared with iFOBT alone.

METHODS

In total, 117 colorectal cancer patients and 107 healthy volunteers were enrolled. Ten-milligram fecal samples were collected and iFOBT was conducted. Fecal RNA was extracted from residuum of iFOBT and then the expression of 14 kinds of miRNA was analyzed for the FmiRT using real-time reverse transcription PCR.

RESULTS

Levels of fecal miR-106a expression in iFOBT+ patients and iFOBT- patients were significantly higher than in healthy volunteers (P = 0.001). The sensitivity and specificity of FmiRT using miR-106a were 34.2% and 97.2%, and those of iFOBT were 60.7% and 98.1%, respectively. The overall sensitivity and specificity of the new screening method combining iFOBT and FmiRT were 70.9% and 96.3%, respectively. One quarter of colorectal cancer patients with false-negative iFOBT seemed to be true positive upon adding FmiRT using fecal miR-106a.

CONCLUSIONS

Fecal miR-106a is a good molecular marker to identify colorectal cancer patients from among those with negative iFOBT results. FmiRT combined with iFOBT may improve the sensitivity to detect colorectal cancer.

IMPACT

We have shown the usefulness of fecal miR-106a to detect the colorectal cancer patients among those with negative iFOBT results.

Molecular biomarkers in esophageal, gastric, and colorectal adenocarcinoma

Cancers of the esophagus, stomach and colon contribute to a major health burden worldwide and over 20% of all cancer deaths. Biomarkers that should indicate pathogenic process and are measureable in an objective manner for these tumors are rare and not established in the clinical setting. In general biomarkers can be very useful for cancer management as they can improve clinical decision-making regarding diagnosis, surveillance, and therapy. Biomarkers can be different types of molecular entities (such as DNA, RNA or proteins), which can be detected, in different tissues or body fluids. However, more important is the type of biomarker itself, which allows diagnostic, prognostic or predictive analyses for different clinical problems. This review aims to systematically summarize the recent findings of genetic and epigenetic markers for gastrointestinal tumors within the last decade. While many biomarkers seem to be very promising, especially if used as panels, further development is urgently needed to address practical considerations of biomarkers in cancer treatment.

Noninvasive screening tests for colorectal cancer

BACKGROUND

Identifying an accurate, reliable, affordable, and acceptable noninvasive screening test for colorectal cancer (CRC) would greatly facilitate population screening.

METHODS

Published literature from 2000 through February 2012 on noninvasive CRC screening tests was identified, reviewed, and summarized.

RESULTS

The highest quality evidence for noninvasive screening exists for guaiac-based fecal occult blood tests (gFOBTs), for which the CRC-specific incidence and mortality reductions are modest. Fecal immunochemical tests (FITs) offer better sensitivity and comparable specificity. Cross-sectional studies comparing gFOBTs and FITs suggest that FITs provide higher detection of advanced neoplasia. Modeling studies favor FITs over gFOBTs with respect to effectiveness and cost-effectiveness. A myriad of studies report the performance of fecal-based and blood-based genetic and protein-based biomarkers; the studies differ in patient population assembled, marker selection, and assay methods. Several markers and panels of markers are promising, although nearly all studies focus on new markers and/or assay methods on small sets of referred patients rather than validating markers using optimal assays in a screening setting.

CONCLUSION

In the absence of long-term randomized trials, adoption of the noninvasive tests will require cross-sectional data on test characteristics obtained from the screening setting, where CRC prevalence is low and the full spectrum of colorectal findings exists, along with estimates of cumulative risks, benefits, and cost-effectiveness. Test adoption will ultimately depend on test characteristics, availability, affordability, and user appeal. There is no noninvasive substitute for the currently recommended screening tests. FITs should replace gFOBTs wherever gFOBTs are used for screening.

Exosome can prevent RNase from degrading microRNA in feces

BACKGROUND

Because the stability of miRNA in feces has not been clarified, we examined the stability of miRNA in feces.

METHODS

RNase was added into culture media of HT-29 cells and fecal homogenates. The relative quantifications of miRNA were analyzed by real-time RT-PCR.

RESULTS

Cellular miRNA or exosomal miRNA were protected from RNase by the cellular membrane or the exosome; meanwhile, free miRNA was degraded immediately and completely by RNase.

CONCLUSION

The present study revealed that exosome or cellular membrane could prevent RNase from degrading miRNA inside the exosome or cells even in a dreadful condition, as in feces.

Use of RNA isolated from feces as a promising tool for the early detection of colorectal cancer

Colorectal cancer is one of the most common forms of cancer worldwide. Early detection would allow patients to be treated surgically and halt the progression of the disease; however, the current methods of early detection are invasive (colonoscopy and sigmoidoscopy) or have low sensitivity (fecal occult blood test). The altered expression of genes in stool samples of patients with colorectal cancer can be determined by RT-PCR. This is a noninvasive and highly sensitive technique for colorectal cancer screening. According to information gathered in this review and our own experience, the use of fecal RNA to determine early alterations in gene expression due to malignancy appears to be a promising alternative to the current detection methods and owing to its low cost could be implemented in public health services.

Molecular tests for colorectal cancer screening

Detecting and removing high-risk adenomas and early colorectal cancer (CRC) can reduce mortality of this disease. The noninvasive fecal occult blood test (FOBT; guaiac-based or immunochemical) is widely used in screening programs and although effective, it leaves room for improvement in terms of test accuracy. Molecular tests are expected to be more sensitive, specific and informative than current detection tests, and are promising future tools for CRC screening. This review provides an overview of the performances of DNA, RNA, and protein markers for CRC detection in stool and blood. Most emphasis currently is on DNA and protein markers. Among DNA markers there is trend to move away from mutation markers in favor of methylation markers. The recent boost in proteomics research leads to many new candidate protein markers. Usually in small series, some markers show better performance than the present FOBT. Evaluation in large well-controlled randomized trials is the next step needed to take molecular markers for CRC screening to the next level and warrant implementation in a screening setting.

Noninvasive detection of inflammation-associated colon cancer in a mouse model

Helicobacter bilis-infected Smad3(-/-) mice represent an attractive model of inflammation-associated colon cancer. Most infected mice develop mucinous adenocarcinoma (MUC) by 6 weeks post inoculation (PI); however, approximately one third do not progress to MUC. The ability to predict the development of MUC in mice used in therapeutic studies would confer a considerable saving of time and money. In addition, the inadvertent use of mice without MUC may confound therapeutic studies by making treatments seem falsely efficacious. We assessed both magnetic resonance imaging (MRI) and fecal biomarkers in Helicobacter- and sham-inoculated mice as methods of noninvasively detecting MUC before the predicted onset of disease. Non-contrast-enhanced MRI was able to detect lesions in 58% of mice with histologically confirmed MUC; however, serial imaging sessions produced inconsistent results. MRI was also a labor- and time-intensive technique requiring anesthesia. Alternatively, inflammatory biomarkers isolated from feces at early time points were correlated to later histologic lesions. Fecal expression of interleukin 1β, macrophage inflammatory protein 1α, and regulated on activation, normal T-cell expressed, and secreted at 3 weeks PI correlated significantly with lesion severity at 9 weeks PI. For each biomarker, receiver-operator characteristic curves were also generated, and all three biomarkers performed well at 1 to 3 weeks PI, indicating that the development of MUC can be predicted based on the early expression of certain inflammatory mediators in feces.

Fecal Tests: From Blood to Molecular Markers

Detection of molecular markers for colorectal neoplasia in feces has the potential to improve performance of simple noninvasive screening tests for colorectal cancer. Most research has explored the value of DNA-based, RNA-based, and protein-based markers. In all cases there has been a trend to move from a single marker to a panel of markers to improve sensitivity. Unfortunately, no type of molecular marker has proved specific for neoplasia. DNA tests have been improved by combining mutation detection with assessment of DNA integrity plus epigenetic markers of neoplasia. RNA-based approaches are just beginning to explore the full power of transcriptomics. So far, no protein-based fecal test has proved better than fecal immunochemical tests for hemoglobin. Finally, no marker or panel of markers has yet been developed to the point where it has been evaluated in large unbiased population studies to assess performance across all stages of neoplasia and in all practical environments.

Relationship between Fecal Content of Fatty Acids and Cyclooxygenase mRNA Expression and Fatty Acid Composition in Duodenal Biopsies, Serum Lipoproteins, and Dietary Fat in Colectomized Familial Adenomatous Polyposis Patients

A few familial adenomatous polyposis studies have focused upon faecal sterols and bile acids but none has analysed the fecal content of fatty acids. We report here findings of an observational study on 29 colectomized familial adenomatous polyposis patients that describe the fecal content of fatty acids, and relate this to the proportions of fatty acids and levels of cyclooxygenase mRNA expression in duodenal biopsies, levels of serum lipoproteins, and diet. In the ileostomy group separately (n = 12), the fecal content of arachidonic acid was correlated negatively to the proportions of eicosapentaenoic acid and docosahexaenoic acid in duodenal biopsies. Total serum-cholesterol was negatively correlated to the fecal content of saturates and monounsaturates. The fecal palmitoleic acid/palmitic acid ratio was positively correlated to the levels of cyclooxygease-2 expression in duodenal biopsies.In the ileal-pouch-anal anastomosis group separately (n = 17), significant correlations were found between the fecal contents of oleic acid, linoleic acid, and alpha-linolenic acid, and the proportions of myristic acid, oleic acid and eicosaenoic acid in duodenal biopsies. Dietary monounsaturates were positively correlated to different fecal fatty acids. Future studies should focus on molecular mechanisms relevant to fatty acid metabolism, inflammation, and angiogenesis, in addition to nutrition.

Detection of fecal interferon-induced transmembrane protein messenger RNA for colorectal cancer screening

Interferon-induced transmembrane protein (IFITM) is reported to be frequently overexpressed in colorectal tumors. This study aimed to determine the usefulness of detecting fecal IFITM messenger RNA (mRNA) by real-time reverse-transcription polymerase chain reaction (RT-PCR) for colorectal cancer (CRC) screening. This pilot study included 21 patients with CRC and 23 healthy controls. Total RNA was isolated from the feces of the patients, and the expression levels of the mRNA of IFITM1, IFITM2 and IFITM3 were measured by real-time RT-PCR to detect CRC. Receiver operating characteristic curves of respective genes were generated, and the area under the curve (AUC), sensitivity and specificity were determined. When the 44 patients were analyzed, the AUCs of fecal IFITM1, IFITM2 and IFITM3 expression analysis were 0.82, 0.80 and 0.65, respectively. The sensitivities were 67% [14/21; 95% confidence interval (CI) 43-85%], 67% (14/21; 95% CI 43-85%) and 71% (15/21; 95% CI 48-89%), respectively; and the specificities were 96% (1/23; 95% CI 78-100%), 96% (1/23; 95% CI 78-100%) and 61% (9/23; 95% CI 39-80%), respectively. When IFITM1 and IFITM2 were combined, the sensitivity was 86% (18/21; 95% CI 64-97%) and the specificity was 96% (1/23; 95% CI 78-100%). The fecal expression analysis of IFITM1 and IFITM2 mRNA by real-time RT-PCR for CRC screening exhibited high specificities, and the sensitivity was further improved by combining IFITM1 and IFITM2.

MicroRNA expression profiling of exfoliated colonocytes isolated from feces for colorectal cancer screening

To reduce the colorectal cancer (CRC) mortality rate, we have reported several CRC screening methods using colonocytes isolated from feces. Expression analysis of oncogenic microRNA (miRNA) in peripheral blood was recently reported for CRC detection. In the present study, we conducted miRNA expression analysis of exfoliated colonocytes isolated from feces for CRC screening. Two hundred six CRC patients and 134 healthy volunteers were enrolled in the study. miRNA expression of the miR-17-92 cluster, miR-21, and miR-135 in colonocytes isolated from feces as well as frozen tissues was analyzed by quantitative real-time PCR. The expression of the miR-17-92 cluster, miR-21, and miR-135 was significantly higher in CRC tissues compared with normal tissues. The exfoliated colonocytes of 197 CRC patients and 119 healthy volunteers were analyzed because of the presence of sufficient miRNA concentration. miR-21 expression did not differ significantly between CRC patients and healthy volunteers (P = 0.6). The expression of miR-17-92 cluster and miR-135 was significantly higher in CRC patients than in healthy volunteers (P < 0.0001). The overall sensitivity and specificity by using miRNA expression was 74.1% (146/197; 95% confidence interval, 67.4-80.1) and 79.0% (94/119; 95% confidence interval, 70.6-85.9), respectively. Sensitivity was dependent only on tumor location (P = 0.0001). miRNA was relatively well conserved in exfoliated colonocytes from feces both of CRC patients and healthy volunteers. miRNA expression analysis of the isolated colonocytes may be a useful method for CRC screening. Furthermore, oncogenic miRNA highly expressed in CRC should be investigated for CRC screening tests in the future.

[Advances in early diagnosis of colorectal cancer based on detection of RNAs in stool.]

Colorectal cancer (CRC) is one of the most malignant cancers in gastrointestinal tract. In China, there are increasing rates of morbidity and mortality for CRC. As the mortality is closely related to the stage of disease at time of diagnosis, early diagnosis of CRC is important. However, current techniques used for clinical diagnosis have limitations which made them difficult to achieve the early diagnosis. The detection of RNAs in stool is a newly developed noninvasive technique for early diagnosis of CRC at molecular levels. Compared with the techniques including colonoscopy, fecal occult-blood test and stool DNA-based mutation detection, diagnosis based on the detection of RNAs in stool has the advantages of low-cost and high sensitivity. Moreover, stool RNA-based techniques are able to analyze multiplexed gene expression simultaneously and monitor cancer progression dynamically. This paper introduced the feasibility of stool RNA analysis, and systematically reviewed the genes associated with stool RNA analysis, methods of RNA isolation from stool sample, and techniques for gene expression analysis in stool RNA. Finally, further applications of stool RNA-based techniques for early diagnosis of CRC were briefly discussed.

Molecular detection of colorectal neoplasia

A variety of noninvasive molecular approaches to colorectal cancer screening are emerging with potential to improve screening effectiveness and user-friendliness. These approaches are based on the sensitive assay of molecular markers in stool, blood, and urine samples. New methods, especially next generation stool-based tests, have been shown to detect both colorectal cancers and precancerous lesions with high accuracy. Validation of these technologies in average-risk populations are needed to establish their role for general colorectal cancer screening. This review addresses the biological rationale, technical advances, recent clinical performance data, and remaining issues with molecular screening for colorectal cancer.

PTGER2 overexpression in colorectal cancer is associated with microsatellite instability, independent of CpG island methylator phenotype

BACKGROUND

Prostaglandin-endoperoxide synthase 2 (PTGS2, the HUGO Gene Nomenclature Committee-approved official symbol for cycloxygenase-2, COX-2) and its enzymatic product prostaglandin E2 have critical roles in inflammation and carcinogenesis through the G protein-coupled receptor PTGER2 (EP2). The PTGS2 (COX-2) pathway is a promising target for cancer therapy and chemoprevention. PTGS2 (COX-2) expression in colon cancer has been inversely associated with survival as well as tumoral microsatellite instability (MSI) and the CpG island methylator phenotype (CIMP). However, the prognostic significance of PTGER2 expression or its relationship with MSI, CIMP, LINE-1 hypomethylation, or PTGS2 (COX-2) remains uncertain.

METHODS

Using the database of 516 colorectal cancers in two prospective cohort studies with clinical outcome data, we detected PTGER2 overexpression in 169 (33%) tumors by immunohistochemistry. We analyzed MSI using 10 microsatellite markers; CIMP by MethyLight (real-time methylation-specific PCR) on an eight-marker panel [CACNA1G, CDKN2A (p16), CRABP1, IGF2, MLH1, NEUROG1, RUNX3 and SOCS1]; BRAF, KRAS, PIK3CA, and methylation in LINE-1 by Pyrosequencing; and CTNNB1 (beta-catenin) and TP53 (p53) by immunohistochemistry.

RESULTS

PTGER2 overexpression was positively associated with the mucinous component (P = 0.0016), signet ring cells (P = 0.0024), CIMP-high (P = 0.0023), and MSI-high (P < 0.0001). In multivariate analysis, the significant relationship between PTGER2 and MSI-high persisted (adjusted odds ratio, 2.82; 95% confidence interval, 1.69-4.72; P < 0.0001). PTGER2 was not significantly associated with PTGS2 (COX-2), TP53, or CTNNB1 expression, patient survival, or prognosis.

CONCLUSION

PTGER2 overexpression is associated with MSI-high in colorectal cancer.

IMPACT

Our data imply potential roles of inflammatory reaction by PTGER2 upregulation in carcinogenic process to MSI-high colorectal cancer.

Factors that contribute to faecal cyclooxygenase-2 mRNA expression in subjects with colorectal cancer

Background:

We previously reported that a faecal cyclooxygenase-2 (COX-2) mRNA assay was useful for identifying colorectal cancer (CRC). This study sought to investigate the factors that contribute to faecal COX-2 mRNA expression in subjects with CRC.

Methods:

The study cohort comprised 78 patients with CRC and 36 control subjects. The expressions of COX-2, β-2-microglobulin (B2M), carcinoembryonic antigen (CEA), E-cadherin (E-cad), and CD45 mRNA in faeces and COX-2 mRNA expression in tissue were determined by quantitative real-time RT–PCR.

Results:

The level of faecal expression of COX-2 mRNA in CRC was significantly higher than that in controls. A significant correlation was found between faecal COX-2 mRNA expression and faecal B2M, CEA, E-cad, or CD45 mRNAs, markers of exfoliated total cells, colonocytes, and leukocytes, respectively. A significant correlation was found between the expression of COX-2 mRNA in faeces and tumour surface area, COX-2 mRNA expression in primary tumour. There was no difference in faecal COX-2 mRNA expression between proximal CRC and distal CRC.

Conclusion:

COX-2 mRNA expression in faeces seems to originate from tumour lesion and to be affected by factors such as the number of exfoliated cells, exfoliation of inflammatory cells, COX-2 mRNA expression in tumour, and tumour size.