Stool Of Colorectal Cancer Patients Research Articles

A new evaluation of the rearranged non-coding control region of JC virus in patients with colorectal cancer

HighlightsA significant proportion of 35/60 (58.33%) tumor tissue and 42/60 (70%) urine samples of the CRC patients were found to be positive for JCV DNA (P = 0.25). The parallel analysis of tumor and urine samples for JCV DNA further supports the potential for non-invasive screening tools.screening JCV DNA in peripheral blood mononuclear cells (PBMCs) and stool of CRC patients may further support the potential for non-invasive screening tools.The study offers new insights into rearranged NCCR variants isolated from colorectal cancer (CRC) patients’ tissue.The screening and analysis of the rrNCCR region of JCV DNA in CRC patients’ stool may indicate the pathogenesis of the JCV virus in CRC development.The presence of JCV LTAg in tumor tissue is significantly higher than in normal tissue (p = < 0.002), suggesting JCV’s role in cancer development during the latency phase.

Intestinal metabolite xylulose inhibits colorectal cancer by inducing apoptosis through the MAPK signalling pathway

BackgroundThe intestinal metabolites are involved in the initiation, progression and metastasis of colorectal cancer (CRC). They are a potential source of agents for cancer therapy. Our previous study identified altered faecal metabolites between CRC patients and healthy volunteers. However, no specific metabolite was clearly illustrated for CRC therapy. ResultsWe found that the level of xylulose was lower in the stools of CRC patients than in those of healthy volunteers. Xylulose inhibited cell growth without affecting the cell cycle by inducing apoptosis in CRC cells, which was evidenced by increased expression of the proapoptotic proteins C-PARP and C-Caspase3 and decreased expression of the antiapoptotic protein BCL-2 in CRC cells. Mechanistically, xylulose reduced the activity of the MAPK signalling pathway, represented by reduced phosphorylation of JNK, ERK, and P38. Furthermore, an ALI model was used to show the tumour killing ability of xylulose on human CRC spheres, as well as human colorectal adenoma (AD) spheres. ConclusionXylulose inhibits CRC growth by inducing apoptosis through attenuation of the MAPK signalling pathway. These results suggest that xylulose may serve as an effective agent for CRC therapy.

Development of fecal microbial diagnostic marker sets of colorectal cancer using natural language processing method.

Cancer screening and early detection greatly increase the chances of successful treatment. However, most cancer types lack effective early screening biomarkers. In recent years, natural language processing (NLP)-based text-mining methods have proven effective in searching the scientific literature and identifying promising associations between potential biomarkers and disease, but unfortunately few are widely used. In this study, we used an NLP-enabled text-mining system, MarkerGenie, to identify potential stool bacterial markers for early detection and screening of colorectal cancer. After filtering markers based on text-mining results, we validated bacterial markers using multiplex digital droplet polymerase chain reaction (ddPCR). Classifiers were built based on ddPCR results, and sensitivity, specificity, and area under the curve (AUC) were used to evaluate the performance. A total of 7 of the 14 bacterial markers showed significantly increased abundance in the stools of colorectal cancer patients. A five-bacteria classifier for colorectal cancer diagnosis was built, and achieved an AUC of 0.852, with a sensitivity of 0.692 and specificity of 0.935. When combined with the fecal immunochemical test (FIT), our classifier achieved an AUC of 0.959 and increased the sensitivity of FIT (0.929 vs. 0.872) at a specificity of 0.900. Our study provides a valuable case example of the use of NLP-based marker mining for biomarker identification.

The Diagnostic Value of Stool-Based MicroRNA-135b in the Early Detection of Colorectal Cancer and the Potent Neuro Function of MiR-146a

Background: Detecting microRNA (miRNA) in stool is a non-invasive approach for colorectal cancer (CRC) screening. This study aims to assess the diagnostic performance of stool-based microRNA-135b in detection of colorectal cancer and the role of miR-146a. Methods: To identify eligible studies that are well suited for diagnostic value of miR-135b in stool of colorectal cancer patients, we have evaluated 3 papers after systematic literature search of public database. The sensitivity and specificity were used to plot the summary receiver operator characteristic (SROC) curve and calculate the area under the SROC curve (AUC). The between-study heterogeneity was evaluated by Q test and I2 statistics. Importantly, we have also identified microRNA (miRNA) gene expression patterns by expression profiling. Moreover, we execute the pathway analysis to find the function of miR-146a. Results: A total of 3 studies from 19 articles were included for the meta-analysis according to the inclusion criteria. The overall analysis showed that microRNA-135b has a relatively good diagnostic performance in colorectal cancer, with a sensitivity of 0.685, a specificity of 0.813 and a partial AUC of 0.658. In stool samples, level of microRNA-135b was 2.21 fold change higher in subjects with CRC (P &lt; 0.0001). Moreover, our study proved that miR-146a involved in the neuro and immune function. Interpretation: In conclusion, stool-based microRNA-135b shows a moderate level of overall diagnostic accuracy in diagnosis of CRC, which may present as auxiliary means for the diagnosis of colorectal cancer compare with colonoscopy. Further large-scale prospective studies are necessary to validate their potential applicability (miR-135b and miR-146a) combined with FBT methods in human cancer diagnosis.

A Fecal MicroRNA Signature by Small RNA Sequencing Accurately Distinguishes Colorectal Cancers: Results From a Multicenter Study

Fecal tests currently used for colorectal cancer (CRC) screening show limited accuracy in detecting early tumors or precancerous lesions. In this respect, we comprehensively evaluated stool microRNA (miRNA) profiles as biomarkers for noninvasive CRC diagnosis. A total of 1273 small RNA sequencing experiments were performed in multiple biospecimens. In a cross-sectional study, miRNA profiles were investigated in fecal samples from an Italian and a Czech cohort (155 CRCs, 87 adenomas, 96 other intestinal diseases, 141 colonoscopy-negative controls). A predictive miRNA signature for cancer detection was defined by a machine learning strategy and tested in additional fecal samples from 141 CRC patients and 80 healthy volunteers. miRNA profiles were compared with those of 132 tumors/adenomas paired with adjacent mucosa, 210 plasma extracellular vesicle samples, and 185 fecal immunochemical test leftover samples. Twenty-five miRNAs showed altered levels in the stool of CRC patients in both cohorts (adjusted P < .05). A 5-miRNA signature, including miR-149-3p, miR-607-5p, miR-1246, miR-4488, and miR-6777-5p, distinguished patients from control individuals (area under the curve [AUC], 0.86; 95% confidence interval [CI], 0.79-0.94) and was validated in an independent cohort (AUC, 0.96; 95% CI, 0.92-1.00). The signature classified control individuals from patients with low-/high-stage tumors and advanced adenomas (AUC, 0.82; 95% CI, 0.71-0.97). Tissue miRNA profiles mirrored those of stool samples, and fecal profiles of different gastrointestinal diseases highlighted miRNAs specifically dysregulated in CRC. miRNA profiles in fecal immunochemical test leftover samples showed good correlation with those of stool collected in preservative buffer, and their alterations could be detected in adenoma or CRC patients. Our comprehensive fecal miRNome analysis identified a signature accurately discriminating cancer aimed at improving noninvasive diagnosis and screening strategies.

The 8q24 region hosts miRNAs altered in biospecimens of colorectal and bladder cancer patients.

The 8q24 locus is enriched in cancer-associated polymorphisms and, despite containing relatively few protein-coding genes, it hosts the MYC oncogene and other genetic elements connected to tumorigenesis, including microRNAs (miRNAs). Research on miRNAs may provide insights into the transcriptomic regulation of this multiple cancer-associated region. We profiled all miRNAs located in the 8q24 region in 120 colorectal cancer (CRC) patients and 80 controls. miRNA profiling was performed on cancer/non-malignant adjacent mucosa, stool, and plasma extracellular vesicles (EVs), and the results validated with The Cancer Genome Atlas (TCGA) data. To verify if the 8q24-annotated miRNAs altered in CRC were dysregulated in other cancers and biofluids, we evaluated their levels in bladder cancer (BC) cases from the TCGA dataset and in urine and plasma EVs from a set of BC cases and healthy controls. Among the detected mature miRNAs in the region, 12 were altered between CRC and adjacent mucosa (adj. p< 0.05). Five and four miRNAs were confirmed as dysregulated in the CRC and BC TCGA dataset, respectively. A co-expression analysis of tumor/adjacent tissue data from the CRC group revealed a correlation between the dysregulated miRNAs and CRC-related genes (PVT1 and MYC) annotated in 8q24 region. miR-30d-5p and miR-151a-3p, altered in CRC tissue, were also dysregulated in stool of CRC patients and urine of BC cases, respectively. Functional enrichment of dysregulated miRNA target genes highlighted terms related to TP53-mediated cell cycle control. Altered expression of 8q24-annotated miRNAs may be relevant for the initiation and/or progression of cancer.

Quantitative detection of SRY-Box 21 (SOX21) gene promoter methylation as a stool-based noninvasive biomarker for early diagnosis of colorectal cancer by MethyLight method.

In recent years, the study of potential epigenetic biomarkers in feces has been an attractive research approach for the noninvasive diagnosis of colorectal cancer (CRC). The aim of this study was to evaluate the stool-based DNA methylation potential of SRY-Box 21 (SOX21) gene promoter as an appropriate candidate biomarker for differentiating CRC patients and healthy individuals for the first time. The MethyLight method was performed to analyze the methylation status of SOX21 gene promoter in fecal samples from 40 patients with CRC and 40 healthy controls. In addition, the diagnostic efficiency of measuring the hypermethylated SOX21 gene in the feces to the fecal occult blood test (FOBT) was compared. The percentage of methylated reference (PMR) values in the stool of CRC patients (median 1.44) was higher than those of healthy individuals (median 0.00) (P < 0.001). A sensitivity of 72.5% and specificity of 100% were obtained for SOX21 gene promoter methylation status and 29 of the patients were considered as positive in methylation status. There was no significant association between PMR values and demographic/clinicopathological features (P > 0.05). The results of the present study demonstrated that the stool-based assay of SOX21 gene promoter methylation has a relatively high sensitivity and specificity and it may serve as a noninvasive biomarker for early detection of CRC. However, more studies with a wide range of samples are required to further confirm the role of hypermethylation of SOX21 in the early CRC diagnosis.

Serum and Stool miR-135b Levels as a Potential Diagnostic Biomarker for Colorectal Cancer

Background: By considering the high incidence and mortality rate of colorectal cancer (CRC), finding the noninvasive biomarker for detection of patients with cancer is the main purpose of more and more cancer studies. Methods: In this research, the expression level of miR-135b in serum and stool of patients with colorectal cancer was investigated as a diagnostic marker. Using the real-time PCR, the relative expression level of miR-135b in serum and stool in 40 patients with colorectal cancer, paired with 40 healthy controls, was determined. Then its sensitivity and specificity were rated, via ROC curves analysis. Results: Expression levels of miR-135b in serum and stool of CRC patients were 32.4 and 15.7 times higher in serum and stool, compared to that of healthy control respectively (P&lt;0.05). ROC curves analysis exhibited that serum miR-135b levels were powerful in detecting CRC patients from control subjects, with a sensitivity of 92.7% and a specificity of 89.7% (AUC: 0.929). In addition, stool miR-135b levels strongly distinguished CRC patients from control subjects with a sensitivity of 92.7% and a specificity of 87.2% (AUC: 0.919). Conclusions: The results of the current study indicate that serum and stool miR-135b expression levels seem to be used as a potential diagnostic biomarker for CRC patients. However further studies with large sample size are needed for approving the miR-135b as a noninvasive diagnostic biomarker of CRC.

Gut butyrate-producing organisms correlate to Placenta Specific 8 protein: Importance to colorectal cancer progression

Tumor metastasis or recurrence often occurs in patients with curative resection of colorectal cancer (CRC). Placental-specific 8 (PLAC8), which has increased expression in stool, may be associated with CRC recurrence. Insights into the role of PLAC8 in CRC recurrence and its clinical significance may support to develop strategies for preventing CRC recurrence and deterioration. Clinical tissues, cell and animal models were used to clarify the roles of PLAC8 in CRC tumorigenesis, invasion, and migration. Next-generation sequencing of 16S ribosomal DNA has been used to assess the gut microbiota in stool of CRC patients. We found that PLAC8 was upregulated in tissues from patients with late-stage CRC. In our in vitro studies, PLAC8 was dynamically regulated in mitotic cells. Overexpressed PLAC8 was nucleated at the centrosome during mitosis, and therefore, PLAC8 overexpression might increase cell growth and migration (all p < 0.05). The tumorigenic and invasive effects of PLAC8 on CRC cells were also confirmed in a xenograft mouse model. We further identified reduced levels of two butyrate-producing organisms, Butyricicoccus and Prevotella spp., in stools from CRC patients. We found that butyrate downregulated PLAC8 expression and induced apoptosis in PLAC8-overexpressing cells. Our data suggests that PLAC8 gene and protein expression and dysbiosis of gut microflora, especially in butyrate-producing microorganisms, may be indicators of CRC progression.

Autoinducer-2 of gut microbiota, a potential novel marker for human colorectal cancer, is associated with the activation of TNFSF9 signaling in macrophages

ABSTRACTObjectives: The interaction between the quorum sensing (QS) molecules of gut microbiota and the immunity of colorectal cancer (CRC) has not been investigated before.Methods: We measured the concentration of autoinducer-2 (AI-2) in samples of stool, colorectal tissue, saliva and serum of CRC patients, and compared this to AI-2 levels in colorectal adenoma (AD) and normal colon mucosa (NC). To explore the activated signaling pathways involved, we utilized AI-2 extracted from Fusobacterium nucleatum to stimulate macrophages and validated these in vitro findings in human CRC tissues.Results: The AI-2 concentration in both colorectal tissue and stool of CRC patients was significantly higher when compared to that in AD and NC (all P values < .01). The AI-2 concentration along with the progression of CRC in both tissues and stools was significantly increased (P= .045，P= .0003, respectively). After AI-2 stimulation, TNFSF9 was the most significantly increased protein in macrophage cells (P < .01). TNFSF9 expression was significantly higher in CRC tissues when compared to NCs (P< .0001), which was mainly derived from macrophages in the tumor microenvironment. Moreover, AI-2 level was positively associated with CD3 + T cell numbers (P= .0462), and negatively associated with CD4/CD8 ratio (P= .0113) within CRC tissues.Conclusions: We demonstrated for the first time that AI-2 may serve as a novel marker for screening CRC in the clinic. AI-2 was associated with tumor immunity in CRCs through tumor-associated macrophages and CD4/CD8 ratio in a TNFSF9-dependent manner.

Quantitative study of vimentin gene methylation in stool samples for colorectal cancer screening.

Due to importance of screening for colorectal cancer the present study was conducted and aimed at investigating the quantitative methylation of vimentin gene in stool, tumor tissue, and healthy tissue of patients with colorectal cancer (CRC) in comparison with healthy individuals. This is a case-control study in which we measures methylation of the vimentin in tumoral tissue, normal tissue and stool specimens were collected from forty-nine CRC patients as case group and stool and normal tissue specimens were collected from thirty healthy individuals as control group. There was no statistically significant difference in methylation of vimentin in normal tissue (P > 0.05) between the two groups. Moreover, the status of methylated or unmethylated vimentin gene in tumor and stool tissues in the case group was not significantly correlated with their mean age and sex (P > 0.05). This study showed that the specificity and sensitivity of vimentin methylation in stool of CRC patients are 100% and 60%, respectively. Furthermore, the methylation of vimentin in stool of CRC patients has a high-positive predictive value (100%). The results of this study suggested that methylation of the vimentin gene in the stool can be used as a specific marker for the detection and screening of CRC.

SFRP2 Promoter Methylation Analysis in Tumor Tissue, Stool, and Plasma DNA of Patients with Colorectal Cancer

Noninvasive method for early detection of human cancers is promising way to provide more quality health service to the population. The serum and stool of colorectal cancer patients often harbor increased free DNA levels, which can potentially be used for cancer detection. Because SFRP2 (secreted frizzled related protein 2) is considered a Wnt inhibitor whose CpGs were frequently hypermethylated in several human cancers, we investigated the frequency of aberrant SFRP2 promoter methylation in primary tumors and serum or stool samples of colorectal cancer patients by MS-PCR. We detected methylation of SFRP2 in 111 of 117 (94.9%) paraffin-embedded colorectal cancer tissues. Fifty-nine of the 68 (86.8%) available serum samples from these cases carried detectable amounts of the methylated SFRP2 promoter. Sixty-one of 68 (89.7%) available stool samples from the same cases carried positive methylation in the promoter region of SFRP2 gene. In contrast, no methylated SFRP2 promoter DNA was detected in serum and stool samples from 60 healthy controls. Only 2 cases of 68 healthy controls showed methylated SFRP2 promoter DNA in their colorectal tissue. But high frequency of methylated SFRP2 gene promoter has no correlation with the clinic-pathologic features. We concluded that SFRP2 methylation analysis appeared to be a noninvasive tumor marker in serum and/or stool DNA

Diagnostic Potential and Interactive Dynamics of the Colorectal Cancer Virome.

Human viruses (those that infect human cells) have been associated with many cancers, largely due to their mutagenic and functionally manipulative abilities. Despite this, cancer microbiome studies have focused almost exclusively on bacteria instead of viruses. We began evaluating the cancer virome by focusing on colorectal cancer, a primary cause of morbidity and mortality throughout the world and a cancer linked to altered colonic bacterial community compositions but with an unknown association with the gut virome. We used 16S rRNA gene, whole shotgun metagenomic, and purified virus metagenomic sequencing of stool to evaluate the differences in human colorectal cancer virus and bacterial community composition. Through random forest modeling, we identified differences in the healthy and colorectal cancer viromes. The cancer-associated virome consisted primarily of temperate bacteriophages that were also predicted to be bacterium-virus community network hubs. These results provide foundational evidence that bacteriophage communities are associated with colorectal cancer and potentially impact cancer progression by altering the bacterial host communities.IMPORTANCE Colorectal cancer is a leading cause of cancer-related death in the United States and worldwide. Its risk and severity have been linked to colonic bacterial community composition. Although human-specific viruses have been linked to other cancers and diseases, little is known about colorectal cancer virus communities. We addressed this knowledge gap by identifying differences in colonic virus communities in the stool of colorectal cancer patients and how they compared to bacterial community differences. The results suggested an indirect role for the virome in impacting colorectal cancer by modulating the associated bacterial community. These findings both support the idea of a biological role for viruses in colorectal cancer and provide a new understanding of basic colorectal cancer etiology.

Study on the correlation between Ras related sequence family 2A gene methylation and colorectal cancer in feces

Objective To investigate the value of methylation of Ras related sequence family 2A (RASSF2A) gene methylation in the stool of patients with colorectal cancer in the clinical diagnosis of RASSF2A. Methods A modified COBRA method was used to analyze the methylation status of 102 RASSF2A gene promoter regions (region 1 and region 2) in two cases of colorectal cancer. 51 cases of healthy subjects as control group negative colonoscopy. At the same time, the relationship between the methylation of RASSF2A gene and clinical pathological factors. Results In the stools of patients with colorectal cancer extensive methylation, methylation and methyl of were 87% and 63% (64/102) 89/102 and 13% (13/102) and 6% (3/51) and 22% (11/51) and 78% (40/51) in the control group respectively. The detection rate of methylation in stool of colorectal cancer patients was significantly higher than that of healthy persons, and the rate of non methylation was significantly lower than that of the control group, the difference was statistically significant (P=0.000). There was no significant correlation between the methylation of RASSF2 gene and the gender, tumor stage, and the degree of invasion of colorectal cancer patients. Conclusion Methylation of RASSF2A gene is an early event in the progression of colorectal cancer. Methylation of RASSF2 gene in feces is expected to be a new approach to the early diagnosis of colorectal cancer. Key words: Ras related sequence family 2A gene; Methylation; Colorectal cancer

Antitumor effects of calgranulin B internalized in human colon cancer cells.

Calgranulin B is a small, calcium-binding protein expressed in neutrophils that is secreted into the tumor microenvironment in cancer cases. We previously showed that calgranulin B levels are increased in the stools of colorectal cancer patients. In patient tumor tissues, calgranulin B protein levels correlated with the presence of stromal inflammatory cells surrounding tumor cells, and calgranulin B promoter methylation was observed in both paired human tissues and colon cancer cell lines. Cell lines did not express calgranulin B, but in vitro studies showed that colon cancer cells internalized extracellular calgranulin B, while other types of cancer cells did not. Calgranulin B internalization led to reduced cell proliferation and increased apoptotic cell death. AKT and ERK signals were also increased after calgranulin B treatment, as were p53, β-catenin, E-cadherin and cleaved caspase-3 levels. Additionally, a human protein microarray identified aurora A kinase as a calgranulin B binding partner, and binding inhibited aurora A kinase activity in a dose-dependent manner. Our findings demonstrate the antitumor effects of calgranulin B in the inflammatory microenvironment and suggest that calgranulin B could be potentially efficacious in the treatment of colon cancer.

Stool Microbiome and Metabolome Differences between Colorectal Cancer Patients and Healthy Adults

In this study we used stool profiling to identify intestinal bacteria and metabolites that are differentially represented in humans with colorectal cancer (CRC) compared to healthy controls to identify how microbial functions may influence CRC development. Stool samples were collected from healthy adults (n = 10) and colorectal cancer patients (n = 11) prior to colon resection surgery at the University of Colorado Health-Poudre Valley Hospital in Fort Collins, CO. The V4 region of the 16s rRNA gene was pyrosequenced and both short chain fatty acids and global stool metabolites were extracted and analyzed utilizing Gas Chromatography-Mass Spectrometry (GC-MS). There were no significant differences in the overall microbial community structure associated with the disease state, but several bacterial genera, particularly butyrate-producing species, were under-represented in the CRC samples, while a mucin-degrading species, Akkermansia muciniphila, was about 4-fold higher in CRC (p<0.01). Proportionately higher amounts of butyrate were seen in stool of healthy individuals while relative concentrations of acetate were higher in stools of CRC patients. GC-MS profiling revealed higher concentrations of amino acids in stool samples from CRC patients and higher poly and monounsaturated fatty acids and ursodeoxycholic acid, a conjugated bile acid in stool samples from healthy adults (p<0.01). Correlative analysis between the combined datasets revealed some potential relationships between stool metabolites and certain bacterial species. These associations could provide insight into microbial functions occurring in a cancer environment and will help direct future mechanistic studies. Using integrated “omics” approaches may prove a useful tool in identifying functional groups of gastrointestinal bacteria and their associated metabolites as novel therapeutic and chemopreventive targets.

Detection of DNA stool mutations in colorectal cancer patients.

e22074 Background: Colorectal cancer (CRC) is the third leading cause of cancer in the world. Noninvasive screening tests have higher compliance. Changes in tumoral cells are also found in the stools after cancer cell exfoliation. Aim: to detect mutations in the stools of CRC patients and compare to mutations found in CRC tissue Methods: Patients referred for colonoscopy were divided into 3 groups: control, cancer, and polyp. The DNA was extracted from tissue and stool and it was analysed by two microarrays, the KRAS/BRAF/PIK3CA Array and the RanplexCRC Array (Randox Laboratories Ltd). Both based on the simultaneous detection of 20 mutations in KRAS, BRAF and PIK3CA and 28 mutations in KRAS, BRAF, TP53 and APC respectively. Positive tissue sample mutations were confirmed by Sanger sequencing. Results: 90 stools and 112 tissue biopsies were studied. Analysis of tissue samples was initially performed using the KRAS/BRAF/PIK3CA Array. In total mutations were detected in 16(55%) CRC, 12(45%) polyp and 2(6%) control samples. Mutations were confirmed via Sanger sequencing (76%). In the stool the frequency were 17(35%) in CRC, 10(71%) in polyp and 1(4%) in the control. Inconclusive tests were higher among the controls (32.5%) and polyps (22%), being less frequent in the CRC patients (6%). Excluding the inconclusive tests, WT genes were common in the controls (96%). The most common mutation was within KRAS codon 12. Stools samples from 48 subjects were compared to the results obtained by the RanplexCRC Array and mutations were found in 50% of CRC. KRAS/BRAF/PIK3CA Array stool results had a correlation with RanplexCRC Array in 64% of CRC patients and in 47% of polyp patients. The average human DNA in the stools was 15ng/ul in CRC patients and 0.46ng/ul in the controls (p=0.0001). Conclusions: Both arrays had a good correlation and a sensitivity between 30-50% with a high specificity (95-100%). The KRAS/BRAF/PIK3CA Array is currently optimized and recommended for assessment of tissue samples. This initial set of data however does indicate its potential applicability to stool specimens. Inconclusive tests are likely as a result of limited human DNA content within stool control samples. FAPESP (Sao Paulo Research Foundation) project 09/16618-8.

Rapid detection of low-abundance K-ras mutation in stools of colorectal cancer patients using chip-based temperature gradient capillary electrophoresis

Mutant K-ras provides an independent negative predictive marker for epidermal growth factor receptor (EGFR)-targeted therapy in colorectal cancers (CRCs). Rapid, sensitive, and cost-effective screening for K-ras status will overarch rational personalized medicine. Stool-based DNA testing offers unique advantages for CRC screening such as noninvasiveness, high specificity, and patient compliance, whereas complicated procedures and the low sensitivity of the present approaches have hampered its application on a wide scale. In this study, a chip-based temperature gradient capillary electrophoresis (TGCE) technique was applied to detect low-abundance K-ras mutations under a pooled experiment and analyze K-ras mutations in 30 paired stool samples and cancer tissues of CRC patients and 15 stool samples of healthy volunteers. The chip-based TGCE results showed that the successful analysis of K-ras status could be achieved within 6 min with an extremely low sample consumption of 14 nl. Detection is sensitive enough to reliably report 0.2% mutant CRC cells in a wild-type background, and 0.5 ng of template DNA was sufficient for chip-based TGCE. Of the 30 stool samples of CRC patients analyzed, 17 (57%) harbored K-ras mutations, and the lowest percentage of the detectable mutant K-ras in stool samples was 2%. The coincidence rate for K-ras mutations between stools and tissues obtained by the chip-based method reached 97% (29/30). One of the 15 stool samples of normal controls carried K-ras mutations, producing a specificity of 93%. Clone sequencing data entirely confirmed the results obtained by chip-based TGCE. The study demonstrates that chip-based TGCE is capable of rapidly screening low-abundance K-ras mutations with high sensitivity, reproducibility, simplicity, and significant savings of time and sample. Application of this method to genotype the K-ras gene in stools would provide a potential means for predicting the effectiveness of EGFR-targeted therapy in CRC patients using noninvasive approaches.

Clusterin in Stool: A New Biomarker for Colon Cancer Screening?

The identification of useful markers for early diagnosis of human colon cancer is a major goal still in progress. Clusterin is a pleiotropic protein with a broad range of functions. It has recently drawn much attention because of its association with cancer promotion and metastasis. It is involved in prosurvival and apoptosis processes that are carried out by two different isoforms. Secreted clusterin isoform (sCLU) is cytoprotective and its prosurvival function is the basis of the current phase I/II clinical trials against prostate, lung, and breast cancers. We have already shown that in colorectal cancer (CRC) there is an increased expression of sCLU. In this report, we investigated whether sCLU is released in the blood and stool of colon cancer patients in order to study sCLU as a potential diagnostic molecular marker for colon cancer screening. The quantitative expression of sCLU was determined by dot blot immunodosage in the serum and stool of CRC patients (n=63) and age-matched controls without clinical history of neoplasia, CRC, or systemic or bowel inflammatory disease (n=50). Unpaired t-tests and Mann-Whitney U-tests were used for continuous variables. The diagnostic performance of clusterin was appraised by means of receiver operating characteristic (ROC) curves. We found a significant increase of sCLU in the serum and stool of CRC patients (P=0.0002 and P<0.000, respectively) as compared with controls. ROC curves provided cutoff points showing a trade-off between sensitivity and specificity. With a cutoff point of 88.5 microg/ml, sCLU in blood showed a 55.6% sensitivity and 100% specificity, and with a cutoff point of 34.6 microg/g, the stool test reached 66.7% sensitivity and 84% specificity in discriminating between nonneoplastic and colorectal neoplastic lesions. Human cancer xenografts in nude mice indicated a positive correlation between increasing serum clusterin level and tumor size. This study highlights the potential of clusterin detection in stool to be a valuable tool to improve the effectiveness and efficiency of large-scale clinical cancer screening.

Evaluation of Calgranulin B in Stools from the Patients with Colorectal Cancer

Calprotectin (heterodimer of calgranulin A and B) has been previously studied as a candidate stool marker for detecting colorectal cancer. We assessed the clinical usefulness of calgranulin B as a stool marker for colorectal cancer in a pilot study of patients with colorectal cancer. We performed 2-DE-based proteomics to screen stool markers for colorectal cancer. We checked the calgranulin B in stools from 77 colorectal cancer patients and from 75 controls by western blot and enzyme-linked immunosorbent assay. We measured calgranulin A using the same methods, and stool hemoglobin by immunologic fecal occult blood test. Fecal calgranulin A did not show any difference, but stool calgranulin B of colorectal cancer patients was significantly higher than controls [50.6 ng/mg stool protein (SD, 34.8) vs. 20.2 ng/mg stool protein (SD,24.0), respectively, P < 0.001). At the cut off level 24.4 ng/mg stool protein, the sensitivity was somewhat higher than fecal occult blood test (72.0 percent vs. 62.3 percent) but the specificity was much lower than fecal occult blood test (77.1 percent vs. 98.7 percent). Calgranulin B was increased in stools of colorectal cancer patients but our results suggest that colorectal cancer screening by determination of stool calgranulin B would not be better than conventional fecal occult blood test.