Colorectal cancer screening: prospects for molecular stool analysis

Identifying N-Glycan Biomarkers in Colorectal Cancer by Mass Spectrometry

Colorectal cancer (CRC) is one of the most prevalent cancers worldwide. Delineating biological markers (biomarkers) for early detection, when treatment is most effective, is key to prevention and long-term survival of patients. Development of reliable biomarkers requires an increased understanding of the CRC biology and the underlying molecular and cellular mechanisms of the disease. With recent advances in new technologies and approaches, tremendous efforts have been put in proteomics and genomics fields to deliver detailed analysis of the two major biomolecules, genes and proteins, to gain a more complete understanding of cellular systems at both genomic and proteomic levels, allowing a mechanistic understanding of the human diseases, including cancer, and opening avenues for identification of novel gene and protein based prognostic and therapeutic markers. Although the importance of glycosylation in modulating protein function has long been appreciated, glycan analysis has been complicated by the diversity of the glycan structures and the large number of potential glycosylation combinations. Driven by recent technological advances, LC-MS/MS based glycomics is gaining momentum in cancer research and holds considerable potential to deliver new glycan-based markers. In our laboratory, we investigated alterations in N-glycosylation associated with CRC malignancy in a panel of CRC cell lines and CRC patient tissues. In an initial study, LC-MS/MS-based N-glycomics were utilized to map the N-glycome landscape associated with a panel of CRC cell lines (LIM1215, LIM1899, and LIM2405). These studies were subsequently extended to paired tumor and nontumorigenic CRC tissues to validate the findings in the cell line. Our studies in both CRC cell lines and tissues identified a strong representation of high mannose and α2,6-linked sialylated complex N-glycans, which corroborate findings from previous studies in CRC and other cancers. In addition, certain unique glycan determinants such as bisecting β1,4-GlcNAcylation and α2,3-sialylation, identified in the metastatic (LIM1215) and aggressive (LIM2405) CRC cell lines, respectively, were shown to be associated with epidermal growth factor receptor (EGFR) expression status. In this Account, we will describe the mass spectrometry based N-glycomics approach utilized in our laboratory to accurately profile the cell- and tissue-specific N-glycomes associated with CRC. We will highlight altered N-glycosylation observed by our studies, consistent with findings from other cancer studies, and discuss how the observed alterations can provide insights into CRC pathogenesis, opening new avenues to identify novel disease-associated glycan markers.

Alu-based cell-free DNA: a novel biomarker for screening of gastric cancer

Gastric cancer (GC) is the fourth most common cancer and the second major cause of cancer-related deaths worldwide. In our previous study, a novel and sensitive method for quantifying cell-free DNA (CFD) in human blood was established and tested for its ability to predict patients with tumor. We want to investigate CFD expression in the sera of GC patients in an attempt to explore the clinical significance of CFD in improving the early screening of GC and monitoring GC progression by the branched DNA (bDNA)-based Alu assay. The concentration of CFD was quantitated by bDNA-based Alu assay. CEA, CA19-9, C72-4 and CA50 concentrations were determined by ABBOTT ARCHITECT I2000 SR. We found the CFD concentrations have significant differences between GC patients, benign gastric disease (BGD) patients and healthy controls (P < 0.05). CFD were weakly correlated with CEA (r = −0.197, P < 0.05) or CA50 (r = 0.206, P < 0.05), and no correlation with CA19-9 (r = −0.061, P > 0.05) or CA72-4 (r = 0.011, P > 0.05). In addition, CFD concentrations were significantly higher in stage I GC patients than BGD patients and healthy controls (P < 0.05), but there was no significant difference in CEA, CA19-9 and CA50 among the three traditional tumor markers (P > 0.05). Our analysis showed that CFD was more sensitive than CEA, CA19-9, CA72-4 or CA50 in early screening of GC. Compared with CEA, CA19-9, CA72-4 and CA50, CFD may prove to be a better biomarker for the screening of GC, thus providing a sensitive biomarker for screening and monitoring progression of GC.

Driver Gene Mutations in Stools of Colorectal Carcinoma Patients Detected by Targeted Next-Generation Sequencing

Detection of driver gene mutations in stool DNA represents a promising noninvasive approach for screening colorectal cancer (CRC). Amplicon-based next-generation sequencing (NGS) is a good option to study mutations in many cancer genes simultaneously and from a low amount of DNA. Our aim was to assess the feasibility of identifying mutations in 22 cancer driver genes with Ion Torrent technology in stool DNA from a series of 65 CRC patients. The assay was successful in 80% of stool DNA samples. NGS results showed 83 mutations in cancer driver genes, 29 hotspot and 54 novel mutations. One to five genes were mutated in 75% of cases. TP53, KRAS, FBXW7, and SMAD4 were the top mutated genes, consistent with previous studies. Of samples with mutations, 54% presented concomitant mutations in different genes. Phosphatidylinositol 3-kinase/mitogen-activated protein kinase pathway genes were mutated in 70% of samples, with 58% having alterations in KRAS, NRAS, or BRAF. Because mutations in these genes can compromise the efficacy of epidermal growth factor receptor blockade in CRC patients, identifying mutations that confer resistance to some targeted treatments may be useful to guide therapeutic decisions. In conclusion, the data presented herein show that NGS procedures on stool DNA represent a promising tool to detect genetic mutations that could be used in the future for diagnosis, monitoring, or treating CRC.

Relationship Between Chronic Inflammation and the Stage and Histopathological Size of Colorectal Carcinoma

Objectives:

The association of inflammatory reactions with almost all types of cancer supports the concept that inflammation is a critical component of tumor progression. The present study aimed to evaluate the relationship of serum markers of chronic inflammation with the stage of and histopathological size of colorectal carcinoma (CRC).

Methods:

This cross-sectional study included 90 patients of both sexes, mean age 66.2 (range 47-78) years, with clinically and histologically confirmed CRC, who were admitted to the Clinic for abdominal surgery UCCS for surgical treatment of CRC. The patients according to the stage of disease were divided into three groups (stage II–IV). The control group consisted of 30 subjects with no signs of malignancy and acute inflammatory diseases. Staging of CRC was done according to the TNM classification. In each patient, the preoperative blood samples were taken for determination of the parameters of inflammation: the erythrocyte sedimentation rate, white blood cells, C-reactive protein (CRP), fibrinogen and alpha 2 globulins.

Results:

It was confirmed that increasing markers of inflammation followed increasing stages of colorectal cancer, depth of tumor invasion and the occurrence of metastatic disease. CRP is a biomarker that consistently and significantly increases from the second to the fourth stage of colorectal cancer (7.2 (2.3-14.6) mg/L vs. 21.85 (12.3-41) mg/L vs. 38.6 (21.5-79) mg/L; p<0.01) and significantly correlates positively with the stage of CRC (r= 0.783, p<0.001), and the tumor size (r=0.249, p<0.05).

Conclusion:

The study results point to an increase in the degree of chronic inflammation throughout the progression of colorectal cancer. The most consistent marker of chronic inflammation that accompanies the progression of colorectal carcinoma is CRP.

BRAF mutation may have different prognostic implications in early- and late-stage colorectal cancer

The prognostic implication of BRAF mutant colorectal cancer remains paradoxical. Records of BRAF mutant and wild-type colorectal cancer patients at all stages were reviewed. Clinicopathologic features, including microsatellite instability, CpG islands methylator phenotype, and overall survival, of these patients were analyzed. Between 2005 and 2013, 428 colorectal cancer patients were enrolled in this study. The overall survival between BRAF mutant and wild-type patients with early-stage (stages I and II) colorectal cancer differed nonsignificantly (P = 0.99). By contrast, in late-stage (stages III and IV) patients, the median overall survival of BRAF mutant patients (N = 25) was significantly poorer than that of BRAF wild-type (N = 207) patients (BRAF mutant: 21.3 months (95% confidence interval [CI] 7.1-35.5); BRAF wild-type: 53.5 months (95% CI 37.5-69.5), P < 0.0001). In early-stage patients, we found that BRAF mutation was significantly associated with CpG island methylator phenotype-positive (P < 0.001), and microsatellite instability-high status (P = 0.0013). Conversely, in late-stage patients, BRAF mutation was significantly associated with CpG island methylator phenotype-positive (P = 0.0015) and the right-side colon (P = 0.014). BRAF mutation may have different prognostic implications in early- and late-stage colorectal cancer.

Mass Spectrometry-Based N-Glycomics of Colorectal Cancer

Colorectal cancer (CRC) is one of the most prevalent cancers worldwide. An increased molecular understanding of the CRC pathology is warranted to gain insights into the underlying molecular and cellular mechanisms of the disease. Altered protein glycosylation patterns are associated with most diseases including malignant transformation. Recent advances in mass spectrometry and bioinformatics have accelerated glycomics research and present a new paradigm for cancer biomarker discovery. Mass spectrometry (MS)-based glycoproteomics and glycomics, therefore, hold considerable promise to improve the discovery of novel biomarkers with utility in disease diagnosis and therapy. This review focuses on the emerging field of glycomics to present a comprehensive review of advances in technologies and their application in studies aimed at discovering novel glycan-based biomarkers. We will also discuss some of the challenges associated with using glycans as biomarkers.

Eicosanoid pathway in colorectal cancer: Recent updates

Enzymatic metabolism of the 20C polyunsaturated fatty acid (PUFA) arachidonic acid (AA) occurs via the cyclooxygenase (COX) and lipoxygenase (LOX) pathways, and leads to the production of various bioactive lipids termed eicosanoids. These eicosanoids have a variety of functions, including stimulation of homeostatic responses in the cardiovascular system, induction and resolution of inflammation, and modulation of immune responses against diseases associated with chronic inflammation, such as cancer. Because chronic inflammation is essential for the development of colorectal cancer (CRC), it is not surprising that many eicosanoids are implicated in CRC. Oftentimes, these autacoids work in an antagonistic and highly temporal manner in inflammation; therefore, inhibition of the pro-inflammatory COX-2 or 5-LOX enzymes may subsequently inhibit the formation of their essential products, or shunt substrates from one pathway to another, leading to undesirable side-effects. A better understanding of these different enzymes and their products is essential not only for understanding the importance of eicosanoids, but also for designing more effective drugs that solely target the inflammatory molecules found in both chronic inflammation and cancer. In this review, we have evaluated the cancer promoting and anti-cancer roles of different eicosanoids in CRC, and highlighted the most recent literature which describes how those molecules affect not only tumor tissue, but also the tumor microenvironment. Additionally, we have attempted to delineate the roles that eicosanoids with opposing functions play in neoplastic transformation in CRC through their effects on proliferation, apoptosis, motility, metastasis, and angiogenesis.

Colorectal cancer

Colorectal cancer had a low incidence several decades ago. However, it has become a predominant cancer and now accounts for approximately 10% of cancer-related mortality in western countries. The 'rise' of colorectal cancer in developed countries can be attributed to the increasingly ageing population, unfavourable modern dietary habits and an increase in risk factors, such as smoking, low physical exercise and obesity. New treatments for primary and metastatic colorectal cancer have emerged, providing additional options for patients; these treatments include laparoscopic surgery for primary disease, more-aggressive resection of metastatic disease (such as liver and pulmonary metastases), radiotherapy for rectal cancer, and neoadjuvant and palliative chemotherapies. However, these new treatment options have had limited impact on cure rates and long-term survival. For these reasons, and the recognition that colorectal cancer is long preceded by a polypoid precursor, screening programmes have gained momentum. This Primer provides an overview of the current state of the art of knowledge on the epidemiology and mechanisms of colorectal cancer, as well as on diagnosis and treatment.

Cdk8 deletion in the Apc(Min) murine tumour model represses EZH2 activity and accelerates tumourigenesis

CDK8 is a dissociable kinase module of the Mediator complex and has been shown to play an important role in transcriptional regulation in organisms as diverse as yeast and humans. Recent studies suggest that CDK8 functions as an oncoprotein in melanoma and colon cancer. Importantly, these studies were conducted using in vitro cell line models and the role of CDK8 in tumourigenesis in vivo has not been explored. We have generated a mouse with a Cdk8 conditional knockout allele and examined the consequences of Cdk8 loss on normal tissue homeostasis and tumour development in vivo. Cdk8 deletion in the young adult mouse did not induce any gross or histopathological abnormalities, implying that Cdk8 is largely dispensable for somatic cellular homeostasis. In contrast, Cdk8 deletion in the Apc(Min) intestinal tumour model shortened the animals' survival and increased tumour burden. Although Cdk8 deletion did not affect tumour initiation, intestinal tumour size and growth rate were significantly increased in Cdk8-null animals. Transcriptome analysis performed on Cdk8-null intestinal cells revealed up-regulation of genes that are governed by the Polycomb group (PcG) complex. In support of these findings, Cdk8-null intestinal cells and tumours displayed a reduction in histone H3K27 trimethylation, both globally and at the promoters of a number of PcG-regulated genes involved in oncogenic signalling. Together, our findings uncover a tumour suppressor function for CDK8 in vivo and suggest that the role of CDK8 activity in driving oncogenesis is context-specific. Sequencing data were deposited at GEO (Accession No. GSE71385).

Anthocyanin-containing purple-fleshed potatoes suppress colon tumorigenesis via elimination of colon cancer stem cells

Cancer stem cells (CSCs) are shown to be responsible for initiation and progression of tumors in a variety of cancers. We previously showed that anthocyanin-containing baked purple-fleshed potato (PP) extracts (PA) suppressed early and advanced human colon cancer cell proliferation and induced apoptosis, but their effect on colon CSCs is not known. Considering the evidence of bioactive compounds, such as anthocyanins, against cancers, there is a critical need to study anticancer activity of PP, a global food crop, against colon CSCs. Thus, isolated colon CSCs (positive for CD44, CD133 and ALDH1b1 markers) with functioning p53 and shRNA-attenuated p53 were treated with PA at 5.0 μg/ml. Effects of baked PP (20% wt/wt) against colon CSCs were also tested in vivo in mice with azoxymethane-induced colon tumorigenesis. Effects of PA/PP were compared to positive control sulindac. In vitro, PA suppressed proliferation and elevated apoptosis in a p53-independent manner in colon CSCs. PA, but not sulindac, suppressed levels of Wnt pathway effector β-catenin (a critical regulator of CSC proliferation) and its downstream proteins (c-Myc and cyclin D1) and elevated Bax and cytochrome c, proteins-mediating mitochondrial apoptosis. In vivo, PP reduced the number of crypts containing cells with nuclear β-catenin (an indicator of colon CSCs) via induction of apoptosis and suppressed tumor incidence similar to that of sulindac. Combined, our data suggest that PP may contribute to reduced colon CSCs number and tumor incidence in vivo via suppression of Wnt/β-catenin signaling and elevation of mitochondria-mediated apoptosis.

Quantitative proteomic analysis of paired colorectal cancer and non-tumorigenic tissues reveals signature proteins and perturbed pathways involved in CRC progression and metastasis

Modern proteomics has proven instrumental in our understanding of the molecular deregulations associated with the development and progression of cancer. Herein, we profile membrane-enriched proteome of tumor and adjacent normal tissues from eight CRC patients using label-free nanoLC-MS/MS-based quantitative proteomics and advanced pathway analysis. Of the 948 identified proteins, 184 proteins were differentially expressed (P<0.05, fold change>1.5) between the tumor and non-tumor tissue (69 up-regulated and 115 down-regulated in tumor tissues). The CRC tumor and non-tumor tissues clustered tightly in separate groups using hierarchical cluster analysis of the differentially expressed proteins, indicating a strong CRC-association of this proteome subset. Specifically, cancer associated proteins such as FN1, TNC, DEFA1, ITGB2, MLEC, CDH17, EZR and pathways including actin cytoskeleton and RhoGDI signaling were deregulated. Stage-specific proteome signatures were identified including up-regulated ribosomal proteins and down-regulated annexin proteins in early stage CRC. Finally, EGFR(+) CRC tissues showed an EGFR-dependent down-regulation of cell adhesion molecules, relative to EGFR(-) tissues. Taken together, this study provides a detailed map of the altered proteome and associated protein pathways in CRC, which enhances our mechanistic understanding of CRC biology and opens avenues for a knowledge-driven search for candidate CRC protein markers.

Improved amplification efficiency on stool samples by addition of spermidine and its use for non-invasive detection of colorectal cancer

Background

Using quantitative methylation-specific PCR (QM-MSP) is a promising method for colorectal cancer (CRC) diagnosis from stool samples. Difficulty in eliminating PCR inhibitors of this body fluid has been extensively reported. Here, spermidine is presented as PCR facilitator for the detection of stool DNA methylation biomarkers using QM-MSP. We examined its effectiveness with NPY, PENK and WIF1, three biomarkers which we have previously shown to be of relevance to CRC.

Results

We determined an optimal window for the amplification of the albumin (Alb) gene (100 ng of bisulfite-treated stool DNA added of 1 mM spermidine) at which we report that spermidine acts as a PCR facilitator (AE = 1680%) for SG RT-PCR. We show that the amplification of methylated PENK, NPY and WIF1 is considerably facilitated by QM-MSP as measured by an increase of CMI (Cumulative Methylation Index, i.e. the sum of the three methylation values) by a factor of 1.5 to 23 fold in individual samples, and of 10 fold in a pool of five samples.

Conclusions

We contend that spermidine greatly reduces the problems of PCR inhibition in stool samples. This observed feature, after validation on a larger sampling, could be used in the development of stool-based CRC diagnosis tests.

Electronic supplementary material

The online version of this article (doi:10.1186/s12896-015-0148-6) contains supplementary material, which is available to authorized users.

EPMA position paper in cancer: current overview and future perspectives

At present, a radical shift in cancer treatment is occurring in terms of predictive, preventive, and personalized medicine (PPPM). Individual patients will participate in more aspects of their healthcare. During the development of PPPM, many rapid, specific, and sensitive new methods for earlier detection of cancer will result in more efficient management of the patient and hence a better quality of life. Coordination of the various activities among different healthcare professionals in primary, secondary, and tertiary care requires well-defined competencies, implementation of training and educational programs, sharing of data, and harmonized guidelines. In this position paper, the current knowledge to understand cancer predisposition and risk factors, the cellular biology of cancer, predictive markers and treatment outcome, the improvement in technologies in screening and diagnosis, and provision of better drug development solutions are discussed in the context of a better implementation of personalized medicine. Recognition of the major risk factors for cancer initiation is the key for preventive strategies (EPMA J. 4(1):6, 2013). Of interest, cancer predisposing syndromes in particular the monogenic subtypes that lead to cancer progression are well defined and one should focus on implementation strategies to identify individuals at risk to allow preventive measures and early screening/diagnosis. Implementation of such measures is disturbed by improper use of the data, with breach of data protection as one of the risks to be heavily controlled. Population screening requires in depth cost-benefit analysis to justify healthcare costs, and the parameters screened should provide information that allow an actionable and deliverable solution, for better healthcare provision.

Developmental regulation and induction of cytochrome P450 2W1, an enzyme expressed in colon tumors

Cytochrome P450 2W1 (CYP2W1) is expressed predominantly in colorectal and also in hepatic tumors, whereas the levels are insignificant in the corresponding normal human adult tissues. CYP2W1 has been proposed as an attractive target for colorectal cancer (CRC) therapy by exploiting its ability to activate duocarmycin prodrugs to cytotoxic metabolites. However, its endogenous function, regulation and developmental pattern of expression remain unexplored. Here we report the CYP2W1 developmental expression in the murine and human gastrointestinal tissues. The gene expression in the colon and small intestine commence at early stages of embryonic life and is completely silenced shortly after the birth. Immunohistochemical analysis of human fetal colon revealed that CYP2W1 expression is restricted to the crypt cells. The silencing of CYP2W1 after birth correlates with the increased methylation of CpG-rich regions in both murine and human CYP2W1 genes. Analysis of CYP2W1 expression in the colon adenocarcinoma cell line HCC2998 revealed that the gene expression can be induced by e.g. the antitumor agent imatinib, linoleic acid and its derivatives. The imatinib mediated induction of CYP2W1 suggests an adjuvant therapy to treatment with duocarmycins that thus would involve induction of tumor CYP2W1 levels followed by the CYP2W1 activated duocarmycin prodrugs. Taken together these data strongly support further exploration of CYP2W1 as a specific drug target in CRC.

Chikusetsusaponin IVa methyl ester induces cell cycle arrest by the inhibition of nuclear translocation of β-catenin in HCT116 cells

We demonstrate that chikusetsusaponin IVa methyl ester (CME), a triterpenoid saponin from the root of Achyranthes japonica, has an anticancer activity. We investigate its molecular mechanism in depth in HCT116 cells. CME reduces the amount of β-catenin in nucleus and inhibits the binding of β-catenin to specific DNA sequences (TCF binding elements, TBE) in target gene promoters. Thus, CME appears to decrease the expression of cell cycle regulatory proteins such as Cyclin D1, as a representative target for β-catenin, as well as CDK2 and CDK4. As a result of the decrease of the cell cycle regulatory proteins, CME inhibits cell proliferation by arresting the cell cycle at the G0/G1 phase. Therefore, we suggest that CME as a novel Wnt/β-catenin inhibitor can be a putative agent for the treatment of colorectal cancers.

Glycosylation characteristics of colorectal cancer

Glycans on proteins and lipids are known to alter with malignant transformation. The study of these may contribute to the discovery of biomarkers and treatment targets as well as understanding of cancer biology. We here describe the change of glycosylation specifically defining colorectal cancer with view on N-glycans, O-glycans, and glycosphingolipid glycans in colorectal cancer cells and tissues as well as patient sera. Glycan alterations observed in colon cancer include increased β1,6-branching and correlating higher abundance of (poly-)N-acetyllactosamine extensions of N-glycans as well as an increase in (truncated) high-mannose type glycans, while bisected structures decrease. Colorectal cancer-associated O-glycan changes are predominated by reduced expression of core 3 and 4 glycans, whereas higher levels of core 1 glycans, (sialyl) T-antigen, (sialyl) Tn-antigen, and a generally higher density of O-glycans are observed. Specific changes for glycosphingolipid glycans are lower abundances of disialylated structures as well as globo-type glycosphingolipid glycans with exception of Gb3. In general, alterations affecting all discussed glycan types are increased sialylation, fucosylation as well as (sialyl) Lewis-type antigens and type-2 chain glycans. As a consequence, interactions with glycan-binding proteins can be affected and the biological function and cellular consequences of the altered glycosylation with regard to tumorigenesis, metastasis, modulation of immunity, and resistance to antitumor therapy will be discussed. Finally, analytical approaches aiding in the field of glycomics will be reviewed with focus on binding assays and mass spectrometry.

Case-controlled identification of colorectal cancer based on proteomic profiles and the potential for screening

AIM

Colorectal cancer (CRC) screening programmes detect early cancers but unfortunately have limited sensitivity and specificity. Mass spectrometry-based determination of serum peptide and protein profiles provides a new approach for improved screening.

METHOD

Serum samples were obtained from 126 CRC patients before treatment and 277 control individuals. An additional group of samples from 50 CRC patients and 82 controls was used for validation. Peptide and protein enrichments were carried out using reverse-phase C18 and weak-cation exchange magnetic beads in an automated solid-phase extraction and spotting procedure. Profiles were acquired on a matrix-assisted laser desorption/ionization time-of-flight system. Discriminant rules using logistic regression were calibrated for the peptide and protein signatures separately, followed by combining the classifications to obtain double cross-validated predicted class probabilities. Results were validated on an identical patient set.

RESULTS

A discriminative power was found for patients with CRC representative for all histopathological stages compared with controls with an area under the curve of 0.95 in the test set (0.93 for the validation set) and with a high specificity (94-95%).

CONCLUSION

The study has shown that a serum peptide and protein biomarker signature can be used to distinguish CRC patients from healthy controls with high discriminative power. This relatively simple and cheap test is promising for CRC screening.

Anomalies in network bridges involved in bile Acid metabolism predict outcomes of colorectal cancer patients

Biomarkers prognostic for colorectal cancer (CRC) would be highly desirable in clinical practice. Proteins that regulate bile acid (BA) homeostasis, by linking metabolic sensors and metabolic enzymes, also called bridge proteins, may be reliable prognostic biomarkers for CRC. Based on a devised metric, "bridgeness," we identified bridge proteins involved in the regulation of BA homeostasis and identified their prognostic potentials. The expression patterns of these bridge proteins could distinguish between normal and diseased tissues, suggesting that these proteins are associated with CRC pathogenesis. Using a supervised classification system, we found that these bridge proteins were reproducibly prognostic, with high prognostic ability compared to other known markers.

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.

Analysis of DNA methylation in bowel lavage fluid for detection of colorectal cancer

Aberrant DNA methylation could potentially serve as a biomarker for colorectal neoplasms. In this study, we assessed the feasibility of using DNA methylation detected in bowel lavage fluid (BLF) for colorectal cancer screening. A total of 508 BLF specimens were collected from patients with colorectal cancer (n = 56), advanced adenoma (n = 53), minor polyp (n = 209), and healthy individuals (n = 190) undergoing colonoscopy. Methylation of 15 genes (miR-1-1, miR-9-1, miR-9-3, miR-34b/c, miR-124-1, miR-124-2, miR-124-3, miR-137, SFRP1, SFRP2, APC, DKK2, WIF1, LOC386758, and ZNF582) was then analyzed in MethyLight assays, after which receiver operating characteristic (ROC) curves were analyzed to assess the diagnostic performance of BLF methylation. Through analyzing BLF specimens in a training set (n = 345), we selected the three genes showing the greatest sensitivity for colorectal cancer detection (miR-124-3, 71.8%; LOC386758, 79.5%; and SFRP1, 74.4%). A scoring system based on the methylation of those three genes (M-score) achieved 82% sensitivity and 79% specificity, and the area under the ROC curve (AUC) was 0.834. The strong performance of this system was then validated in an independent test set (n = 153; AUC = 0.808). No significant correlation was found between M-score and the clinicopathologic features of the colorectal cancers. Our results demonstrate that DNA methylation in BLF specimens may be a useful biomarker for the detection of colorectal cancer.

ROS-mediated autophagy induced by dysregulation of lipid metabolism plays a protective role in colorectal cancer cells treated with gambogic acid

Gambogic acid (GA), the main active component of gamboge resin, has potent antitumor activity both in vivo and in vitro. However, the underlying molecular mechanisms remain unclear. In this study, we found that GA could initiate autophagy in colorectal cancer cells, and inhibition of the autophagy process accelerated the effect of proliferative inhibition and apoptotic cell death induced by GA, implying a protective role of autophagy. Two-dimensional electrophoresis-based proteomics showed that GA treatment altered the expression of multiple proteins involved in redox signaling and lipid metabolism. Functional studies revealed that GA-induced dysregulation of lipid metabolism could activate 5-lipoxygenase (5-LOX), resulting in intracellular ROS accumulation, followed by inhibition of Akt-mTOR signaling and autophagy initiation. Finally, results using a xenograft model suggested ROS-induced autophagy protect against the antitumor effect of GA. Taken together, these data showed new biological activities of GA against colorectal cancer underlying the protective role of ROS-induced autophagy. This study will provide valuable insights for future studies regarding the anticancer mechanisms of GA.

Clinical and histopathological correlations of fecal calprotectin release in colorectal carcinoma

AIM: To determine calprotectin release before and after colorectal cancer operation and compare it to tumor and histopathological parameters.

METHODS: The study was performed on patients with diagnosed colorectal cancer admitted for operation. Calprotectin was measured in a single stool sample before and three months after the operation using an enzyme-linked immunosorbent assay (ELISA). Calprotectin levels greater than or equal to 50 μg/g were considered positive. The compliance for collecting stool samples was assessed and the value of calprotectin was correlated to tumor and histopathological parameters of intra- and peri-tumoral inflammation. Surgical specimens were fixed in neutral buffered formalin and stained with hematoxylin and eosin. Staging was performed according to the Dukes classification system and the 7^th edition tumor node metastasis classification system. Intra- and peri-tumoral inflammation was graded according to the Klintrup criteria. Immunohistochemical quantification was performed for MPO, CD45R0, TIA-1, CD3, CD4, CD8, CD57, and granzyme B. Statistical significance was measured using Wilcoxon signed rank test, Kruskal Wallis test and Spearman’s rank correlation coefficient as appropriate.

RESULTS: Between March 2009 and May 2011, 80 patients with colorectal cancer (46 men and 34 women, with mean age of 71 ± 11.7 years old) were enrolled in the study. Twenty-six patients had rectal carcinoma, 29 had left-side tumors, 23 had right-side tumors, and 2 had bilateral carcinoma. In total, 71.2% of the patients had increased levels of calprotectin before the operation (median 205 μg/g, range 50-2405 μg/g) and experienced a significant decrease three months after the operation (46 μg/g, range 10-384 μg/g, P < 0001). The compliance for collecting stool samples was 89.5%. Patients with T3 and T4 tumors had significantly higher values than those with T1 and T2 cancers (P = 0.022). For all other tumor parameters (N, M, G, L, V, Pn) and location, no significant difference in calprotectin concentration was found. Furthermore, the calprotectin levels and histological grading of both peri- and intra-tumoral inflammation was not correlated. Additional testing with specific markers for lymphocytes and neutrophils also revealed no statistically significant correlation.

CONCLUSION: Fecal calprotectin decreases significantly after colorectal cancer operation. Its value depends exclusively on the individual T-stage, but not on other tumor or histopathological parameters.

Overexpression of integrin-linked kinase (ILK) promotes migration and invasion of colorectal cancer cells by inducing epithelial-mesenchymal transition via NF-κB signaling

Integrin-linked kinase (ILK), a ubiquitously expressed and evolutionally conserved serine/threonine kinase, has been shown to be aberrantly overexpressed and activated in diversified types of human malignancies, including colorectal cancer (CRC). However, the potential role of ILK in cancer cell migration and invasion remains to be elucidated. In this study, we introduced the human ILK gene into a low ILK-expressing human CRC cell line SW480. Cell migration and invasion were evaluated by the wound healing assay and transwell invasion assay, respectively. The epithelial-mesenchymal transition (EMT)-related proteins were detected by Western blot analysis or immunofluorescence. We found that enforced overexpression of ILK in SW480 cells dramatically promoted their migratory and invasive ability in vitro. Furthermore, SW480 cells stably overexpressing ILK underwent EMT, as indicated by mesenchymal morphology, decreased expression of E-cadherin, and increased expression of vimentin, Snail, and Slug. Finally, the nuclear factor (NF)-κB inhibitor BAY 11-7028 or NF-κB p65 small interfering RNA significantly restored the reduced E-cadherin level in ILK-overexpressing cells, suggesting that ILK-mediated down-regulation of E-cadherin is dependent on NF-κB activation. Overall, our study demonstrates a pivotal role of ILK in EMT and metastasis, and suggests novel therapeutic opportunities for the treatment of CRC.

miRNA as markers for the diagnostic screening of colon cancer

Early screening for colon cancer (CC) allows for early stage diagnosis of the malignancy and potentially reduces disease mortality as the cancer is most likely curable at its earliest stages. Early detection would be desirable if accurate, practical and cost-effective diagnostic measures for this cancer were available. Mortality and morbidity from CC represent a major health problem involving a malignant disease that is theoretically preventable through screening. Current screening methods (e.g., the convenient and inexpensive immunological fecal occult blood test, FOBTi, obtained from patients' medical records) either lack sensitivity and require dietary restriction, which impedes compliance and use; are costly (e.g., colonoscopy), which decreases compliance; or could result in mortality. In comparison with the FOBT test, a non-invasive sensitive screen for which there is no requirement for dietary restriction would be a more convenient test. Colorectal cancer is the only cancer for which colonoscopy is recommended as a screening method. Although colonoscopy is a reliable screening tool, the invasive nature, abdominal pain, potential complications and high cost have hampered the application of this procedure worldwide. A screening approach using the stable miRNA molecules, which are relatively non-degradable when extracted from non-invasive stool and semi-invasive blood samples by commercially available kits and manipulated thereafter, would be preferable to a transcriptomic mRNA-, a mutation DNA-, an epigenetic- or a proteomic-based test. The approach uses reverse transcriptase, modified real-time quantitative PCR. Although exosomal RNA would be missed, using a restricted extraction of total RNA from stool or blood, a parallel test could also be carried out on RNA obtained from stool or plasma samples, and appropriate corrections for exsosomal loss can be made for accurate and quantitative test result. Eventually, a chip can be developed to facilitate diagnosis, as has been done for the quantification of genetically modified organisms in foods. The gold standard to which the molecular miRNA test is compared is colonoscopy, which can be obtained from patients' medical records. If performance criteria are met, as detailed herein, a miRNA test in human stool or blood samples based on high-throughput automated technologies and quantitative expression measurements commonly used in the diagnostic clinical laboratory should be advanced to the clinical setting, which will make a significant impact on CC prevention.

Dihydroartemisinin induces apoptosis in colorectal cancer cells through the mitochondria-dependent pathway

Dihydroartemisinin (DHA), a semisynthetic derivative of artemisinin isolated from the traditional Chinese herb Artemisia annua, has been shown to exhibit antitumor activity in various cancer cells, including colorectal cancer. However, the detailed mechanisms underlying its antitumor activity in colorectal cancer remain to be elucidated. In the present study, we investigated DHA-induced apoptosis in human colorectal cancer HCT-116 cells in vitro. The results showed that DHA treatment significantly reduced cell viability in a concentration- and time-dependent manner. Furthermore, DHA induced G1 cell cycle arrest, apoptotic cell death, and accumulation of reactive oxygen species (ROS). We also found that DHA decreased the mitochondrial membrane potential; activated the caspase-3, caspase-8, and caspase-9; and increased the ratio of Bax/Bcl-2. Meanwhile, the translocation of apoptotic inducing factor (AIF) and the release of cytochrome c from the mitochondria were observed. Strikingly, the free radical scavenger N-acetylcysteine or the caspase-3 inhibitor Ac-DEVD-CHO significantly prevented DHA-induced apoptotic cell death. Taken together, we concluded that DHA-triggered apoptosis in HCT-116 cells occurs through the ROS-mediated mitochondria-dependent pathway. Our data suggest that DHA has great potential to be developed as a novel therapeutic agent for the treatment of human colorectal cancer.

Significance of NF-κB p65 expression in ulcerative colitis and colorectal adenocarcinoma

AIM: To investigate the expression of nuclear factor κB (NF-κB) p65 protein in the colon mucosa of patients with ulcerative colitis (UC) or colorectal adenocarcinoma (CA) and healthy volunteers.

METHODS: Specimens were obtained from 12 healthy volunteers, 16 patients with UC and 18 patients with CA. Fresh colonic tissues were obtained by endoscopic punch biopsies. The diagnosis was confirmed pathologically. Reverse transcription-polymerase chain reaction and immunohistochemistry were used to examine the expression of NF-κB p65 at both mRNA and protein levels in the colon mucosa of different groups.

RESULTS: The expression rate of NF-κB p65 mRNA and protein was 0.10% ± 0.03% and 2.06%±0.70% in the normal colon mucosa, 0.96% ± 0.11% and 36.16% ± 6.99% in UC, and 0.42% ± 0.77% and 9.54% ± 2.77% in CA, respectively. The expression of NF-κB p65 was significantly higher in UC than in CA and normal mucosa (all P < 0.01). Although the expression of NF-κB p65 in CA was higher than that in normal colon mucosa at both mRNA and protein levels, the expression intensity was not as strong as that reported in the literature.

CONCLUSION: Increased expression of NF-κB p65 may play an important role in the pathogenesis of UC, and anti-NF-κB therapy should be examined further for use as a potential therapy. NF-κB p65 may also be involved in the pathogenesis of CA.

Replication proteins and human disease

In this article, we discuss the significance of DNA replication proteins in human disease. There is a broad range of mutations in genes encoding replication proteins, which result in several distinct clinical disorders that share common themes. One group of replication proteins, the MCMs, has emerged as effective biomarkers for early detection of a range of common cancers. They offer practical and theoretical advantages over other replication proteins and have been developed for widespread clinical use.

RSPO2-LGR5 signaling has tumour-suppressive activity in colorectal cancer

R-spondins are a family of secreted Wnt agonists. One of the family members, R-spondin 2 (RSPO2), has an important role in embryonic development, bone formation and myogenic differentiation; however, its role in human cancers remains largely unknown. Here we show that RSPO2 expression is downregulated in human colorectal cancers (CRCs) due to promoter hypermethylation, and that the RSPO2 reduction correlates with tumour differentiation, size and metastasis. Overexpression of RSPO2 suppresses CRC cell proliferation and tumorigenicity, whereas the depletion of RSPO2 enhances tumour cell growth. RSPO2 has an inhibitory effect on Wnt/β-catenin signaling in the CRC cells that show suppressed cell proliferation. In human CRC cells, the RSPO2-induced inhibition of Wnt signaling depends on leucine-rich repeat-containing G-protein-coupled receptor 5 (LGR5); RSPO2 interacts with LGR5 to stabilize the membrane-associated zinc and ring finger 3 (ZNRF3). Our data suggest that RSPO2 functions as a tumour suppressor in human CRCs, and these data reveal a RSPO2-induced, LGR5-dependent Wnt signaling-negative feedback loop that exerts a net growth-suppressive effect on CRC cells.

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.

Investigations on aberrant glycosylation of glycosphingolipids in colorectal cancer tissues using liquid chromatography and matrix-assisted laser desorption time-of-flight mass spectrometry (MALDI-TOF-MS)

Cancer is a leading cause of death and alterations of glycosylation are characteristic features of malignant cells. Colorectal cancer is one of the most common cancers and its exact causes and biology are not yet well understood. Here, we compared glycosylation profiles of colorectal tumor tissues and corresponding control tissues of 13 colorectal cancer patients to contribute to the understanding of this cancer. Using MALDI-TOF(/TOF)-MS and 2-dimensional LC-MS/MS we characterized enzymatically released and 2-aminobenzoic acid labeled glycans from glycosphingolipids. Multivariate data analysis revealed significant differences between tumor and corresponding control tissues. Main discriminators were obtained, which represent the overall alteration in glycosylation of glycosphingolipids during colorectal cancer progression, and these were found to be characterized by (1) increased fucosylation, (2) decreased acetylation, (3) decreased sulfation, (4) reduced expression of globo-type glycans, as well as (5) disialyl gangliosides. The findings of our current research confirm former reports, and in addition expand the knowledge of glycosphingolipid glycosylation in colorectal cancer by revealing new glycans with discriminative power and characteristic, cancer-associated glycosylation alterations. The obtained discriminating glycans can contribute to progress the discovery of biomarkers to improve diagnostics and patient treatment.

Multiplexed VeraCode bead-based serological immunoassay for colorectal cancer

Colorectal cancer (CRC) is the second leading cause of cancer deaths in the US and Western world. Despite increased screening and advances in treatment, the mortality rate (ca. 50,000/year) and high national health-care burden for CRC are likely to remain high unless an effective non-invasive screening test for CRC is instituted for a large segment of the population. Blood-based protein biomarkers hold great promise for early disease diagnosis and personalized medicine; yet robust and reproducible multiplexing platforms and methodologies have lagged behind their genomic counterparts. Here, we report the development of a novel, multiplexed, hybrid immunoassay for CRC that is formatted on barcoded VeraCode™ micro-beads, which have until now only been used for genomic assays. The method combines a sandwich immunoassay format for detection of serum protein biomarkers with an antigen assay for autoantibody detection. The serum protein biomarkers CEA and GDF15 as well as autoantibodies to the p53 tumor associated antigen (TAA) were used to exemplify the method. This multiplex biomarker panel was configured to run on Illumina's holographically barcoded VeraCode™ micro-bead platform, which is capable of measuring hundreds of analytes simultaneously in a single well from small volumes of blood (<50 μL) using a 96-well industry standard microtiter plate. This novel use of the VeraCode™ micro-bead platform translates into a potentially low volume, high throughput, multiplexed assay for CRC, for the purposes of biomarker validation, as well as patient screening, diagnostics and prognostics. In an evaluation of a 186 patient sera training set (CRC and normal), we obtained a diagnostic sensitivity of 54% and a specificity of 98%. We anticipate that by expanding and refining the biomarkers in this initial panel, and performing more extensive clinical validations, such an assay could ultimately provide a basis for CRC population screening to complement the more invasive, expensive and low throughput (but highly sensitive and specific) colonoscopy.

Low-mass-ion discriminant equation: a new concept for colorectal cancer screening

Blood metabolites can be detected as low-mass ions (LMIs) by mass spectrometry (MS). These LMIs may reflect the pathological changes in metabolism that occur as part of a disease state, such as cancer. We constructed a LMI discriminant equation (LOME) to investigate whether systematic LMI profiling might be applied to cancer screening. LMI information including m/z and mass peak intensity was obtained by five independent MALDI-MS analyses, using 1,127 sera collected from healthy individuals and cancer patients with colorectal cancer (CRC), breast cancer (BRC), gastric cancer (GC) and other types of cancer. Using a two-stage principal component analysis to determine weighting factors for individual LMIs and a two-stage LMI selection procedure, we selected a total of 104 and 23 major LMIs by the LOME algorithms for separating CRC from control and rest of cancer samples, respectively. CRC LOME demonstrated excellent discriminating power in a validation set (sensitivity/specificity: 93.21%/96.47%). Furthermore, in a fecal occult blood test (FOBT) of available validation samples, the discriminating power of CRC LOME was much stronger (sensitivity/specificity: 94.79%/97.96%) than that of the FOBT (sensitivity/specificity: 50.00%/100.0%), which is the standard CRC screening tool. The robust discriminating power of the LOME scheme was reconfirmed in screens for BRC (sensitivity/specificity: 92.45%/96.57%) and GC (sensitivity/specificity: 93.18%/98.85%). Our study demonstrates that LOMEs might be powerful noninvasive diagnostic tools with high sensitivity/specificity in cancer screening. The use of LOMEs could potentially enable screening for multiple diseases (including different types of cancer) from a single sampling of LMI information.

FGFR4 promotes stroma-induced epithelial-to-mesenchymal transition in colorectal cancer

Tumor cells evolve by interacting with the local microenvironment; however, the tumor-stroma interactions that govern tumor metastasis are poorly understood. In this study, proteomic analyses reveal that coculture with tumor-associated fibroblasts (TAF) induces significant overexpression of FGFR4, but not other FGFRs, in colorectal cancer cell lines. Mechanistic study shows that FGFR4 plays crucial roles in TAF-induced epithelial-to-mesenchymal transition (EMT) in colorectal cancer cell lines. Accumulated FGFR4 in cell membrane phosphorylates β-catenin, leading to translocation of β-catenin into the nucleus. Further, TAF-derived CCL2 and its downstream transcription factor, Ets-1, are prerequisites for TAF-induced FGFR4 upregulation. Furthermore, FGFR4-associated pathways are shown to be preferentially activated in colorectal tumor samples, and direct tumor metastasis in a mouse metastasis model. Our study shows a pivotal role of FGFR4 in tumor-stroma interactions during colorectal cancer metastasis, and suggests novel therapeutic opportunities for the treatment of colorectal cancer.

Clinical update: colon, rectal, and anal cancers

OBJECTIVES

To present an updated review of the incidence, risk factors, staging, diagnosis, and treatment of colon, rectal, and anal cancers, as well as nursing care associated with managing patients diagnosed with these malignancies.

DATA SOURCES

Published research reports, epidemiologic data, published patient management guidelines, and institution-based clinical tools.

CONCLUSION

While significant advances in the management of colon, rectal, and anal cancers in the past decade have extended patient survival, there remain some unanswered questions. Further clinical and molecular research will help individualize patient care, refining current therapeutic strategies and treatment decision-making aids while minimizing symptoms of disease and treatment.

IMPLICATIONS FOR NURSING PRACTICE

Nurses need to be familiar with risk factors, disease course, and current and emerging therapies to assist patients with treatment decision-making, and to anticipate and intervene in managing disease and treatment-induced problems. Early identification and management of distressing symptoms can help to avoid life-threatening effects and promote patient adherence to prescribed therapies; timely patient/family education may minimize anxiety and promote self-management.

Imaging a functional tumorigenic biomarker in the transformed epithelium

Proteases responsible for the increased peritumoral proteolysis associated with cancer represent functional biomarkers for monitoring tumorigenesis. One attractive extracellular biomarker is the transmembrane serine protease matriptase. Found on the surface of epithelial cells, the activity of matriptase is regulated by its cognate inhibitor hepatocyte growth factor activator inhibitor-1 (HAI-1). Quantitative mass spectrometry allowed us to show that, in selected cancers, HAI-1 expression decreases, leading to active matriptase. A preclinical probe specific for the measurement of emergent active matriptase was developed. Using an active-site-specific, recombinant human antibody for matriptase, we found that the selective targeting of active matriptase can be used to visualize the tumorigenic epithelium. Live-cell fluorescence imaging validated the selectivity of the antibody in vitro by showing that the probe localized only to cancer cell lines with active matriptase on the surface. Immunofluorescence with the antibody documented significant levels of active matriptase in 68% of primary and metastatic colon cancer sections from tissue microarrays. Labeling of the active form of matriptase in vivo was measured in human colon cancer xenografts and in a patient-derived xenograft model using near-infrared and single-photon emission computed tomography imaging. Tumor uptake of the radiolabeled antibody, (111)In-A11, by active matriptase was high in xenografts (28% injected dose per gram) and was blocked in vivo by the addition of a matriptase-specific variant of ecotin. These findings suggest, through a HAI-1-dependent mechanism, that emergent active matriptase is a functional biomarker of the transformed epithelium and that its proteolytic activity can be exploited to noninvasively evaluate tumorigenesis in vivo.

PAX2 protein induces expression of cyclin D1 through activating AP-1 protein and promotes proliferation of colon cancer cells

Paired box (PAX) 2, a transcription factor, plays a critical role in embryogenesis. When aberrantly expressed in adult tissues, it generally exhibits oncogenic properties. However, the underlying mechanisms remain unclear. We reported previously that the expression of PAX2 was up-regulated in human colon cancers. However, the role of PAX2 in colon cancer cells has yet to be determined. The aim of this study is to determine the function of PAX2 in colon cancer cells and to investigate the possible mechanisms underlain. We find that knockdown of PAX2 inhibits proliferation and xenograft growth of colon cancer cells. Inhibition of PAX2 results in a decreased expression of cyclin D1. Expression of cyclin D1 is found increased in human primary colon malignant tumors, and its expression is associated with that of PAX2. These data indicate that PAX2 is a positive regulator of expression of cyclin D1. We find that knockdown of PAX2 inhibits the activity of AP-1, a transcription factor that induces cyclin D1 expression, implying that PAX2 induces cyclin D1 through AP-1. PAX2 has little effect on expression of AP-1 members including c-Jun, c-Fos, and JunB. Our data show that PAX2 prevents JunB from binding c-Jun and enhances phosphorylation of c-Jun, which may elevate the activity of AP-1. Taken together, these results suggest that PAX2 promotes proliferation of colon cancer cells through AP-1.

Transcriptome profiling of the cancer, adjacent non-tumor and distant normal tissues from a colorectal cancer patient by deep sequencing

Colorectal cancer (CRC) is one of the most commonly diagnosed cancers in the world. A genome-wide screening of transcriptome dysregulation between cancer and normal tissue would provide insight into the molecular basis of CRC initiation and progression. Compared with microarray technology, which is commonly used to identify transcriptional changes, the recently developed RNA-seq technique has the ability to detect other abnormal regulations in the cancer transcriptome, such as alternative splicing, novel transcripts or gene fusion. In this study, we performed high-throughput transcriptome sequencing at ∼50× coverage on CRC, adjacent non-tumor and distant normal tissue. The results revealed cancer-specific, differentially expressed genes and differential alternative splicing, suggesting that the extracellular matrix and metabolic pathways are activated and the genes related to cell homeostasis are suppressed in CRC. In addition, one tumor-restricted gene fusion, PRTEN-NOTCH2, was also detected and experimentally confirmed. This study reveals some common features in tumor invasion and provides a comprehensive survey of the CRC transcriptome, which provides better insight into the complexity of regulatory changes during tumorigenesis.

N-glycosylation of colorectal cancer tissues: a liquid chromatography and mass spectrometry-based investigation

Colorectal cancer is the third most common cancer worldwide with an annual incidence of ∼1 million cases and an annual mortality rate of ∼655,000 individuals. There is an urgent need for identifying novel targets to develop more sensitive, reliable, and specific tests for early stage detection of colon cancer. Post-translational modifications are known to play an important role in cancer progression and immune surveillance of tumors. In the present study, we compared the N-glycan profiles from 13 colorectal cancer tumor tissues and corresponding control colon tissues. The N-glycans were enzymatically released, purified, and labeled with 2-aminobenzoic acid. Aliquots were profiled by hydrophilic interaction liquid chromatography (HILIC-HPLC) with fluorescence detection and by negative mode MALDI-TOF-MS. Using partial least squares discriminant analysis to investigate the N-glycosylation changes in colorectal cancer, an excellent separation and prediction ability were observed for both HILIC-HPLC and MALDI-TOF-MS data. For structure elucidation, information from positive mode ESI-ion trap-MS/MS and negative mode MALDI-TOF/TOF-MS was combined. Among the features with a high separation power, structures containing a bisecting GlcNAc were found to be decreased in the tumor, whereas sulfated glycans, paucimannosidic glycans, and glycans containing a sialylated Lewis type epitope were shown to be increased in tumor tissues. In addition, core-fucosylated high mannose N-glycans were detected in tumor samples. In conclusion, the combination of HILIC and MALDI-TOF-MS profiling of N-glycans with multivariate statistical analysis demonstrated its potential for identifying N-glycosylation changes in colorectal cancer tissues and provided new leads that might be used as candidate biomarkers.

Proximal fluid proteome profiling of mouse colon tumors reveals biomarkers for early diagnosis of human colorectal cancer

PURPOSE

Early detection of colorectal cancer (CRC) and its precursor lesions is an effective approach to reduce CRC mortality rates. This study aimed to identify novel protein biomarkers for the early diagnosis of CRC.

EXPERIMENTAL DESIGN

Proximal fluids are a rich source of candidate biomarkers as they contain high concentrations of tissue-derived proteins. The FabplCre;Apc(15lox/+) mouse model represents early-stage development of human sporadic CRC. Proximal fluids were collected from normal colon and colon tumors and subjected to in-depth proteome profiling by tandem mass spectrometry. Carcinoembryonic antigen (CEA) and CHI3L1 human serum protein levels were determined by ELISA.

RESULTS

Of the 2,172 proteins identified, quantitative comparison revealed 192 proteins that were significantly (P < 0.05) and abundantly (>5-fold) more excreted by tumors than by controls. Further selection for biomarkers with highest specificity and sensitivity yielded 52 candidates, including S100A9, MCM4, and four other proteins that have been proposed as candidate biomarkers for human CRC screening or surveillance, supporting the validity of our approach. For CHI3L1, we verified that protein levels were significantly increased in sera from patients with adenomas and advanced adenomas compared with control individuals, in contrast to the CRC biomarker CEA.

CONCLUSION

These data show that proximal fluid proteome profiling with a mouse tumor model is a powerful approach to identify candidate biomarkers for early diagnosis of human cancer, exemplified by increased CHI3L1 protein levels in sera from patients with CRC precursor lesions.

LINE-1 hypomethylation in familial and sporadic cancer

Increased and decreased methylation at specific sequences (hypermethylation and hypomethylation, respectively) is characteristic of tumor DNA compared to normal DNA and promotes carcinogenesis in multiple ways including genomic instability. Long interspersed element (LINE), an abundant class of retrotransposons, provides a surrogate marker for global hypomethylation. We developed methylation-specific multiplex ligation-dependent probe amplification assays to study LINE-1 methylation in cases of colorectal, gastric, and endometrial cancer (N = 276), stratified by patient category [sporadic; Lynch syndrome (LS); familial colorectal cancer type X (FCCX)] and microsatellite instability status. Within each patient group, LINE-1 showed lower methylation in tumor DNA relative to paired normal DNA and hypomethylation was statistically significant in most cases. Interestingly, normal colorectal mucosa samples from different patient groups displayed differences in LINE-1 methylation that mirrored differences between the respective tumor tissues, with a decreasing trend for LINE-1 methylation from patients with sporadic colorectal cancer to LS to FCCX. Despite the fact that the degree of LINE-1 methylation is generally tissue specific, normal colorectal mucosa, gastric mucosa, and endometrium from LS patients showed similar levels of LINE-1 methylation. Our results suggest that the degree of LINE-1 methylation may constitute a “field defect” that may predispose normal tissues for cancer development.

The phosphoinositide 3-kinase inhibitor LY294002, decreases aminoacyl-tRNA synthetases, chaperones and glycolytic enzymes in human HT-29 colorectal cancer cells

The proposed anticancer drug LY294002, inhibits phosphoinositide-3 kinase (PI3K) that initiates a signalling pathway often activated in colorectal cancer (CRC). The effects of LY294002 (10 μM, 48 h) on the cytosolic, mitochondrial and nuclear proteomes of human HT-29 CRC cells have been determined using iTRAQ (isobaric tag for relative and absolute quantitation) and tandem mass spectrometry (MS/MS). Analysis of cells treated with LY294002 identified 26 differentially abundant proteins that indicate several mechanisms of action. The majority of protein changes were directly or indirectly associated with Myc and TNF-α, previously implicated in CRC progression. LY294002 decreased the levels of 6 aminoacyl-tRNA synthetases (average 0.39-fold) required for protein translation, 5 glycolytic enzymes (average 0.37-fold) required for ATP synthesis, and 3 chaperones required for protein folding. There was a 3.2-fold increase in lysozyme C involved in protein-glycoside hydrolysis. LY294002 increased cytosolic p53 with a concomitant decrease in nuclear p53, suggesting transfer of p53 to the cytosol where apoptosis might be initiated via the intrinsic mitochondrial pathway. Protein changes described here suggest that the anti-angiogenic effects of LY294002 may be related to p53; the mutational status of p53 in CRC may be an important determinant of the efficacy of PI3K inhibitors for treatment.

Fecal molecular markers for colorectal cancer screening

Despite multiple screening techniques, including colonoscopy, flexible sigmoidoscopy, radiological imaging, and fecal occult blood testing, colorectal cancer remains a leading cause of death. As these techniques improve, their sensitivity to detect malignant lesions is increasing; however, detection of precursor lesions remains problematic and has generated a lack of general acceptance for their widespread usage. Early detection by an accurate, noninvasive, cost-effective, simple-to-use screening technique is central to decreasing the incidence and mortality of this disease. Recent advances in the development of molecular markers in faecal specimens are encouraging for its use as a screening tool. Genetic mutations and epigenetic alterations that result from the carcinogenetic process can be detected by coprocytobiology in the colonocytes exfoliated from the lesion into the fecal matter. These markers have shown promising sensitivity and specificity in the detection of both malignant and premalignant lesions and are gaining popularity as a noninvasive technique that is representative of the entire colon. In this paper, we summarize the genetic and epigenetic fecal molecular markers that have been identified as potential targets in the screening of colorectal cancer.

Proteomics identification of ITGB3 as a key regulator in reactive oxygen species-induced migration and invasion of colorectal cancer cells

Colorectal cancer (CRC) is the third most commonly diagnosed cancer in males and second in females worldwide. Unfortunately 40-50% of patients already have metastatic disease at presentation when prognosis is poor with a 5-year survival of <10%. Reactive oxygen species (ROS) have been proposed to play a crucial role in tumor metastasis. We now show that higher levels of ROS accumulation are found in a colorectal cancer-derived metastatic cell line (SW620) compared with a cell line (SW480) derived from the primary lesion from the same patient. In addition, ROS accumulation can affect both the migratory and invasive capacity of SW480 and SW620 cells. To explore the molecular mechanism underlying ROS-induced migration and invasion in CRC, we have compared protein expression patterns between SW480 and SW620 cells using a two-dimensional electrophoresis-based proteomics strategy. A total of 63 altered proteins were identified from tandem MS analysis. Cluster analysis revealed dysregulated expression of multiple redox regulative or ROS responsive proteins, implicating their functional roles in colorectal cancer metastasis. Molecular and pathological validation demonstrated that altered expression of PGAM1, GRB2, DJ-1, ITGB3, SOD-1, and STMN1 was closely correlated with the metastatic potential of CRC. Functional studies showed that ROS markedly up-regulated expression of ITGB3, which in turn promoted an aggressive phenotype in SW480 cells, with concomitant up-regulated expression of STMN1. In contrast, knockdown of ITGB3 expression could mitigate the migratory and invasive potential of SW620 or H(2)O(2)-treated SW480 cells, accompanied by down-regulated expression of STMN1. The function of ITGB3 was dependent on the surface expression of integrin αvβ3 heterodimer. Furthermore, STMN1 expression and the PI3K-Akt-mTOR pathway were found to be involved in ROS-induced and ITGB3-mediated migration and invasion of colorectal cancer cells. Taken together, these studies suggest that ITGB3 plays an important role in ROS-induced migration and invasion in CRC.

Epigenetic alteration of DNA in mucosal wash fluid predicts invasiveness of colorectal tumors

Although conventional colonoscopy is considered the gold standard for detecting colorectal tumors, accurate staging is often difficult because advanced histology may be present in small colorectal lesions. We collected DNA present in mucosal wash fluid from patients undergoing colonoscopy and then assessed the methylation levels of four genes frequently methylated in colorectal cancers to detect invasive tumors. We found that methylation levels in wash fluid were significantly higher in patients with invasive than those with noninvasive tumors. Cytologic and K-ras mutation analyses suggested that mucosal wash fluid from invasive tumors contained greater numbers of tumor cells than wash fluid from noninvasive tumors. Among the four genes, levels of mir-34b/c methylation had the greatest correlation with the invasion and showed the largest area under the receiver operating characteristic curve (AUC = 0.796). Using cutoff points of mir-34b/c methylation determined by efficiency considerations, the sensitivity/specificity were 0.861/0.657 for the 13.0% (high sensitivity) and 0.765/0.833 for the 17.8% (well-balanced) cutoffs. In the validation test set, the AUC was also very high (0.915), the sensitivity/specificity were 0.870/0.875 for 13.0% and 0.565/0.958 for 17.8%. Using the diagnostic tree constructed by an objective algorithm, the diagnostic accuracy of the invasiveness of colorectal cancer was 91.3% for the training set and 85.1% for the test set. Our results suggest that analysis of the methylation of DNA in mucosal wash fluid may be a good molecular marker for predicting the invasiveness of colorectal tumors.

Colorectal cancer epidemiology: incidence, mortality, survival, and risk factors

In this article, the incidence, mortality, and survival rates for colorectal cancer are reviewed, with attention paid to regional variations and changes over time. A concise overview of known risk factors associated with colorectal cancer is provided, including familial and hereditary factors, as well as environmental lifestyle-related risk factors such as physical inactivity, obesity, smoking, and alcohol consumption.

Consensus pathways implicated in prognosis of colorectal cancer identified through systematic enrichment analysis of gene expression profiling studies

Background

A large number of gene expression profiling (GEP) studies on prognosis of colorectal cancer (CRC) has been performed, but no reliable gene signature for prediction of CRC prognosis has been found. Bioinformatic enrichment tools are a powerful approach to identify biological processes in high-throughput data analysis.

Principal Findings

We have for the first time collected the results from the 23 so far published independent GEP studies on CRC prognosis. In these 23 studies, 1475 unique, mapped genes were identified, from which 124 (8.4%) were reported in at least two studies, with 54 of them showing consisting direction in expression change between the single studies. Using these data, we attempted to overcome the lack of reproducibility observed in the genes reported in individual GEP studies by carrying out a pathway-based enrichment analysis. We used up to ten tools for overrepresentation analysis of Gene Ontology (GO) categories or Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways in each of the three gene lists (1475, 124 and 54 genes). This strategy, based on testing multiple tools, allowed us to identify the oxidative phosphorylation chain and the extracellular matrix receptor interaction categories, as well as a general category related to cell proliferation and apoptosis, as the only significantly and consistently overrepresented pathways in the three gene lists, which were reported by several enrichment tools.

Conclusions

Our pathway-based enrichment analysis of 23 independent gene expression profiling studies on prognosis of CRC identified significantly and consistently overrepresented prognostic categories for CRC. These overrepresented categories have been functionally clearly related with cancer progression, and deserve further investigation.