Biomarkers of colorectal cancer: Recent advances and future challenges

RUNX1-induced upregulation of PTGS2 enhances cell growth, migration and invasion in colorectal cancer cells

Colorectal cancer (CRC) arises via the progressive accumulation of dysregulation in key genes including oncogenes and tumor-suppressor genes. Prostaglandin-endoperoxide synthase 2 (PTGS2, also called COX2) acts as an oncogenic driver in CRC. Here, we explored the upstream transcription factors (TFs) responsible for elevating PTGS2 expression in CRC cells. The results showed that PTGS2 silencing repressed cell growth, migration and invasion in HCT116 and SW480 CRC cells. The two fragments (499-981 bp) and (1053-1434 bp) were confirmed as the core TF binding profiles of the PTGS2 promoter. PTGS2 expression positively correlated with RUNX1 level in colon adenocarcinoma (COAD) samples using the TCGA-COAD dataset. Furthermore, RUNX1 acted as a positive regulator of PTGS2 expression by promoting transcriptional activation of the PTGS2 promoter via the 1086-1096 bp binding motif. In conclusion, our study demonstrates that PTGS2 upregulation induced by the TF RUNX1 promotes CRC cell growth, migration and invasion, providing an increased rationale for the use of PTGS2 inhibitors in CRC prevention and treatment.

The role of gut microbiota in the development of colorectal cancer: a review

PURPOSE

Colorectal cancer (CRC) is the cancer of the colon and rectum. Recent research has found a link between CRC and human gut microbiota. This review explores the effect of gut microbiota on colorectal carcinogenesis and the development of chemoresistance.

METHODS

A literature overview was performed to identify the gut microbiota species that showed altered abundance in CRC patients and the mechanisms by which some of them aid in the development of chemoresistance.

RESULTS

Types of gut microbiota present and methods of analyzing them were discussed. We observed that numerous microbiota showed altered abundance in CRC patients and could act as a biomarker for CRC diagnosis and treatment. Further, it was demonstrated that microbes also have a role in the development of chemoresistance by mechanisms like immune system activation, drug modification, and autophagy modulation. Finally, the key issue of the growing global problem of antimicrobial resistance and its relationship with CRC was highlighted.

CONCLUSION

This review discussed the role of gut microbiota dysbiosis on colorectal cancer progression and the development of chemoresistance.

Molecular Network of Colorectal Cancer and Current Therapeutic Options

Colorectal cancer (CRC), a leading cause of cancer-related mortalities globally, results from the accumulation of multiple genetic and epigenetic alterations in the normal colonic and rectum epithelium, leading to the progression from colorectal adenomas to invasive carcinomas. Almost half of CRC patients will develop metastases in the course of the disease and most patients with metastatic CRC are incurable. Particularly, the 5-year survival rate of patients with stage 4 CRC at diagnosis is less than 10%. Although genetic understanding of these CRC tumors and paired metastases has led to major advances in elucidating early driver genes responsible for carcinogenesis and metastasis, the pathophysiological contribution of transcriptional and epigenetic aberrations in this malignancy which influence many central signaling pathways have attracted attention recently. Therefore, treatments that could affect several different molecular pathways may have pivotal implications for their efficacy. In this review, we summarize our current knowledge on the molecular network of CRC, including cellular signaling pathways, CRC microenvironment modulation, epigenetic changes, and CRC biomarkers for diagnosis and predictive/prognostic use. We also provide an overview of opportunities for the treatment and prevention strategies in this field.

TMUB1 Correlated with Immune Infiltration Is a Prognostic Marker for Colorectal Cancer

BACKGROUND

Transmembrane and ubiquitin-like domain-containing protein 1 (TMUB1) is overexpressed in a large number of liver and esophageal tumors. However, only a few reports on the clinical significance of TMUB1 in colorectal cancer (CRC) exist.

METHODS

Here, we evaluated the clinical significance and potential biological role of TMUB1 using bioinformatics analysis. Univariate and multivariate analyses were performed to evaluate the relationship of TMUB1 with clinicopathological features. Gene set enrichment analysis (GSEA) was performed to identify the biological function of TMUB1, while any associations between the expression of TMUB1 and the infiltration of 24 immune cells were analyzed using simple-sample GSEA.

RESULTS

TMUB1 was significantly overexpressed in CRC tissues compared with normal controls. The high expression of TMUB1 in CRC was associated with T stage, neotype, and residual tumor. Moreover, TMUB1 was identified as an independent factor of poor disease-free survival (DFS) and short overall survival (OS). GSEA demonstrated that TMUB1 was related to hypoxia, angiogenesis, adipogenesis, inflammatory response, IL6-JAK-STAT3 signaling, apoptosis, mitotic spindle, and IL2-STAT5 signaling. The expression of TMUB1 negatively correlated with the abundance of T helper cells, Tcm cells, macrophages, and Th2 cells, whereas it positively correlated with the abundance of several immune cell types, including CD56bright and CD56dim NK cells.

CONCLUSIONS

The high expression of TMUB1 is closely related to a poor prognosis in patients with CRC. TMUB1 may be a potential prognostic biomarker and be used for therapeutic approaches in CRC.

Faecal Diagnostic Biomarkers for Colorectal Cancer

Simple Summary

Colorectal cancer (CRC) is a significant public health problem, being a major cause of cancer death worldwide. Hence, the identification of biomarkers able to support CRC detection is crucial. This work analyses a panel of six biomarkers, namely interleukin-6 (IL-6), tumour necrosis factor-alpha (TNF-α), matrix metalloproteinase (MMP)-2, MMP-9, haemoglobin (Hb) and M2-pyruvate kinase (M2-PK), in stool samples from patients with CRC, advanced adenomas, other lesions and healthy individuals. Our results indicate that the levels of Hb and M2-PK were increased in CRC patients in comparison to the controls. Moreover, the combination of these biomarkers increased the specificity or sensitivity for CRC detection and thus present potential for diagnosis of CRC.

Abstract

Background: Colorectal cancer (CRC) is a major cause of cancer-related death worldwide. Cancer progression, including invasion and metastasis, is a major cause of death among CRC patients. Current methods for CRC screening commonly consist of a combination of faecal immunochemical test (FIT) for stool occult blood detection and invasive procedures such as colonoscopy. Considering the slow progression of CRC, and that symptoms usually emerge at advanced stages, its early diagnostic can limit cancer’s spread and provide a successful treatment. Biomarkers have a high potential for the diagnosis of CRC in either blood or stool samples. Methods: In this study, we analysed the diagnostic value of six different biomarkers in stool samples of patients with CRC, advanced adenomas, other lesions and healthy individuals. We have also assessed the overall performance of the combination of these biomarkers for CRC detection. Results: The results indicate that haemoglobin (Hb) and M2-pyruvate kinase (M2-PK) levels were increased in CRC patients in comparison to the controls. Conversely, the concentrations of matrix metalloproteinase (MMP)-2, MMP-9, and tumour necrosis factor-alpha (TNF-α) were not significantly different between the tested groups. Conclusion: The combination of FIT-Hb with the M2-PK levels increased the specificity or sensitivity for CRC detection and thus present potential as faecal diagnostic biomarkers for CRC.

Comparative Analysis of Circulating Biomarkers for Patients Undergoing Resection of Colorectal Liver Metastases

Surgical tumor resection has evolved as a potentially curative therapy for patients with resectable colorectal liver metastases (CRLM). However, disease recurrence is common and the available preoperative stratification strategies are often imprecise to identify the ideal candidates for surgical treatment, resulting in a postoperative 5-year survival rate below 50%. Data on the prognostic value of CEA, CA19-9 and other common laboratory parameters after CRLM resection are scarce and partly inconclusive. Here, we analyzed the prognostic potential of circulating CEA and CA19-9 in comparison to other standard laboratory markers in resectable CRLM patients. Serum levels of tumor markers and other laboratory parameters were analyzed in 125 patients with CRLM undergoing tumor resection at a tertiary referral center. Results were correlated with clinical data and outcome. Both tumor markers were significantly elevated in CRLM patients compared to healthy controls. Interestingly, elevated levels of CEA, CA19-9 and C-reactive protein (CRP) were associated with an unfavorable prognosis after CRLM resection in Kaplan-Meier curve analysis. However, only CEA and not CA19-9 or CRP serum levels were an independent prognostic marker in multivariate Cox regression analysis. Our data demonstrate that circulating levels of CEA rather than CA19-9 might be a valuable addition to the existing preoperative stratification algorithms to identify patients with a poor prognosis after CRLM resection.

uc.77- Downregulation Promotes Colorectal Cancer Cell Proliferation by Inhibiting FBXW8-Mediated CDK4 Protein Degradation

Transcribed ultraconserved regions (T-UCRs) are a new type of long non-coding RNA, and the UCR has 481 segments longer than 200 base pairs that are 100% conserved between humans, rats, and mice. T-UCRs involved in colorectal cancer (CRC) have not been studied in detail. We performed T-UCR microarray analysis and found that uc.77- was significantly downregulated in CRC tissues and cell lines. Ectopic expression of uc.77- significantly inhibited the proliferation of CRC cells in vitro and the growth of xenograft tumors in nude mice in vivo. Mechanistic studies showed that uc.77- competed with FBXW8 mRNA for binding to microRNA (miR)-4676-5p through a competing endogenous RNA mechanism and inhibited the proliferation of CRC cells by negatively regulating CDK4. The present findings highlight the role of the uc.77-/miR-4676-5p/FBXW8 axis in CRC and identify uc.77- as a potential novel target for the treatment of CRC.

High expression of PLAC1 in colon cancer as a predictor of poor prognosis: A study based on TCGA data

Colon cancer is one of the most common diseases in the world with both a high incidence and high mortality. PLAC1 is activated and expressed in many cancers. We aim to explore the relationship between PLAC1 expression and prognosis in colon cancer patient. The RNA-Seq expression data and clinical information of colon cancer were downloaded from The Cancer Genome Atlas (TCGA) database. Differentially expressed PLAC1 was obtained by the Wilcoxon signed-rank test; the significance difference being that PLAC1 was more highly expressed in tumor rather than normal tissue (p < 0.01). Then patients were classified into high and low risk groups by different risk scores, and the Kaplan-Meier survival analysis showed that colon cancer patients with a high PLAC1 expression had a poorer prognosis than low PLAC1 expression patients (p = 0.0031). Next, in analyzing the clinical pathology associated with PLAC1 expression, logistic regression showed that PLAC1 was expressed high in stage (OR = 4.11 for I vs. IV), lymph nodes (OR = 1.73 for N0 vs. N1+), distant metastasis (OR = 2.8 for M0 vs. M1), and status (OR = 22.81 for normal vs. tumor). Univariate and multivariate cox analyses were employed to identify that PLAC1 could be regarded as an independent prognostic factor. Univariate cox analysis showed PLAC1 had a correlation to overall survival (OS) (HR: 0.46, 95% CI: 0.28-0.77, p = 0.003). Multivariate cox analysis revealed that PLAC1 (HR: 0.51, 95% CI: 0.30-0.86, p = 0.012) could be regarded as an Independent prognostic factor. We also used quantitative real-time polymerase chain reaction (qRT-PCR) to test if PLAC1 was differently expressed in cell lines. The qRT-PCR obtained the significant results that PLAC1 expressed high in colon cancer cell lines (p < 0.05). Finally, Gene Set Enrichment Analysis (GSEA) was utilized to show 14 enriched signaling pathways. Our study discovered that high expression of PLAC1 predicts poor prognosis in colon cancer patients, providing a new biomarker, which can assist physicians in finding new diagnostic and therapy methods for colon cancer.

NAP1L1: A Novel Human Colorectal Cancer Biomarker Derived From Animal Models of Apc Inactivation

Introduction

Colorectal cancer (CRC) is the second leading cause of cancer death worldwide and most deaths result from metastases. We have analyzed animal models in which Apc, a gene that is frequently mutated during the early stages of colorectal carcinogenesis, was inactivated and human samples to try to identify novel potential biomarkers for CRC.

Materials and Methods

We initially compared the proteomic and transcriptomic profiles of the small intestinal epithelium of transgenic mice in which Apc and/or Myc had been inactivated. We then studied the mRNA and immunohistochemical expression of one protein that we identified to show altered expression following Apc inactivation, nucleosome assembly protein 1–like 1 (NAP1L1) in human CRC samples and performed a prognostic correlation between biomarker expression and survival in CRC patients.

Results

Nap1l1 mRNA expression was increased in mouse small intestine following Apc deletion in a Myc dependant manner and was also increased in human CRC samples. Immunohistochemical NAP1L1 expression was decreased in human CRC samples relative to matched adjacent normal colonic tissue. In a separate cohort of 75 CRC patients, we found a strong correlation between NAP1L1 nuclear expression and overall survival in those patients who had stage III and IV cancers.

Conclusion

NAP1L1 expression is increased in the mouse small intestine following Apc inactivation and its expression is also altered in human CRC. Immunohistochemical NAP1L1 nuclear expression correlated with overall survival in a cohort of CRC patients. Further studies are now required to clarify the role of this protein in CRC.

One-Pot Synthesis of Novel Thiazoles as Potential Anti-Cancer Agents

Background

Thiazole and thiosemicarbazone derivatives are known to have potential anticancer activity with a mechanism of action related to inhibition of matrix metallo-proteinases, kinases and anti-apoptotic BCL2 family proteins.

Materials and Methods

A novel three series of 5-(1-(2-(thiazol-2-yl)hydrazono)ethyl)thiazole derivatives were prepared in a one-pot three-component reaction using 2-(2-benzylidene hydrazinyl)-4-methylthiazole as a starting precursor. MS, IR, ¹H-NMR and ¹³C-NMR were used to elucidate the structures of the synthesized compounds. Most of the synthesized products were evaluated for their in vitro anticancer screening against HCT-116, HT-29 and HepG2 using the MTT colorimetric assay.

Results

The results indicated that compounds 4c, 4d and 8c showed growth inhibition activity against HCT-116 with IC₅₀ values of 3.80 ± 0.80, 3.65 ± 0.90 and 3.16 ± 0.90 μM, respectively, compared to harmine (IC₅₀ = 2.40 ± 0.12 μM) and cisplatin (IC₅₀ = 5.18 ± 0.94 μM) reference drugs. Also, compounds 8c, 4d and 4c showed promising IC₅₀ values of 3.47 ± 0.79, 4.13 ± 0.51 and 7.24 ± 0.62 μM, respectively, against the more resistant human colorectal cancer (HT-29) cell line compared with harmine (IC₅₀ = 4.59 ± 0.67 μM) and cisplatin (IC₅₀ = 11.68 ± 1.54 μM). On the other hand, compounds 4d, 4c, 8c and 11c were the most active (IC₅₀ values of 2.31± 0.43, 2.94 ± 0.62, 4.57 ± 0.85 and 9.86 ± 0.78 μM, respectively) against the hepatocellular carcinoma (HepG2) cell line compared with harmine (IC₅₀ = 2.54 ± 0.82 μM) and cisplatin (IC₅₀ = 41 ± 0.63 μM). The study also suggested that the mechanism of the anticancer action exerted by the most active compounds (4c, 4d and 8c) inside HCT-116 cells was apoptosis through the Bcl-2 family.

Conclusion

Thiazole scaffolds 4c, 4d and 8c showed anticancer activities in the micromolar range and are appropriate as a candidate for cancer treatment.

pH-Responsive Artesunate Polymer Prodrugs with Enhanced Ablation Effect on Rodent Xenograft Colon Cancer

Purpose

In this study, pH-sensitive poly(2-ethyl-2-oxazoline)-poly(lactic acid)-poly(β-amino ester) (PEOz-PLA-PBAE) triblock copolymers were synthesized and were conjugated with an antimalaria drug artesunate (ART), for inhibition of a colon cancer xenograft model.

Methods

The as-prepared polymer prodrugs are tended to self-assemble into polymeric micelles in aqueous milieu, with PEOz segment as hydrophilic shell and PLA-PBAE segment as hydrophobic core.

Results

The pH sensitivity of the as-prepared copolymers was confirmed by acid-base titration with pKb values around 6.5. The drug-conjugated polymer micelles showed high stability for at least 96 h in PBS and 37°C, respectively. The as-prepared copolymer prodrugs showed high drug loading content, with 9.57%±1.24% of drug loading for PEOz-PLA-PBAE-ART4. The conjugated ART could be released in a sustained and pH-dependent manner, with 92% of released drug at pH 6.0 and 57% of drug released at pH 7.4, respectively. In addition, in vitro experiments showed higher inhibitory effect of the prodrugs on rodent CT-26 cells than that of free ART. Animal studies also demonstrated the enhanced inhibitory efficacy of PEOz-PLA-PBAE-ART2 micelles on the growth of rodent xenograft tumor.

Conclusion

The pH-responsive artesunate polymer prodrugs are promising candidates for colon cancer adjuvant therapy.

Biomarkers in Colorectal Cancer: The Role of Translational Proteomics Research

Colorectal cancer is one of the most common cancers in the world, and it is one of the leading causes of cancer-related death. Despite recent progress in the development of screening programs and in the management of patients with colorectal cancer, there are still many gaps to fill, ranging from the prevention and early diagnosis to the determination of prognosis factors and treatment of metastatic disease, to establish a personalized approach. The genetic profile approach has been increasingly used in the decision-making process, especially in the choice of targeted therapies and in the prediction of drug response, but there are still few validated biomarkers of colorectal cancer for clinical practice. The discovery of non-invasive, sensitive, and specific biomarkers is an urgent need, and translational proteomics play a key role in this process, as they enable better comprehension of colorectal carcinogenesis, identification of potential markers, and subsequent validation. This review provides an overview of recent advances in the search for colorectal cancer biomarkers through proteomics studies according to biomarker function and clinical application.

In-Depth Characterization of Mass Spectrometry-Based Proteomic Profiles Revealed Novel Signature Proteins Associated with Liver Metastatic Colorectal Cancers

Liver metastasis is the most common form of metastatic colorectal cancers during the course of the disease. The global change in protein abundance in liver metastatic colorectal cancers and its role in metastasis establishment have not been comprehensively analyzed. In the present study, fresh-frozen tissue samples including normal colon/localized/liver metastatic CRCs from each recruited patient were analyzed by quantitative proteomics using a multiplexed TMT labeling strategy. Around 5000 protein groups were quantified from all samples. The proteomic profile of localized/metastatic CRCs varied greatly from that of normal colon tissues; differential proteins were mainly from extracellular regions and participate in immune activities, which is crucial for the chronic inflammation signaling pathways in the tumor microenvironment. Further statistical analysis revealed 47 proteins exhibiting statistical significance between localized and metastatic CRCs, of which FILI1P1 and PLG were identified for the first time in proteomic data, which were highly associated with liver metastasis in CRCs.

The Gene Master Regulators (GMR) Approach Provides Legitimate Targets for Personalized, Time-Sensitive Cancer Gene Therapy

The dynamic and never exactly repeatable tumor transcriptomic profile of people affected by the same form of cancer requires a personalized and time-sensitive approach of the gene therapy. The Gene Master Regulators (GMRs) were defined as genes whose highly controlled expression by the homeostatic mechanisms commands the cell phenotype by modulating major functional pathways through expression correlation with their genes. The Gene Commanding Height (GCH), a measure that combines the expression control and expression correlation with all other genes, is used to establish the gene hierarchy in each cell phenotype. We developed the experimental protocol, the mathematical algorithm and the computer software to identify the GMRs from transcriptomic data in surgically removed tumors, biopsies or blood from cancer patients. The GMR approach is illustrated with applications to our microarray data on human kidney, thyroid and prostate cancer samples, and on thyroid, prostate and blood cancer cell lines. We proved experimentally that each patient has his/her own GMRs, that cancer nuclei and surrounding normal tissue are governed by different GMRs, and that manipulating the expression has larger consequences for genes with higher GCH. Therefore, we launch the hypothesis that silencing the GMR may selectively kill the cancer cells from a tissue.

Microbiome and colorectal cancer: Roles in carcinogenesis and clinical potential

The gastrointestinal tract harbors most of the microbiota associated with humans. In recent years, there has been a surge of interest in assessing the relationships between the gut microbiota and several gut alterations, including colorectal cancer. Changes in the gut microbiota in patients suffering colorectal cancer suggest a possible role of host-microbe interactions in the origin and development of this malignancy and, at the same time, open the door for novel ways of preventing, diagnosing, or treating this disease. In this review we survey current knowledge on the healthy microbiome of the gut and how it is altered in colorectal cancer and other related disease conditions. In describing past studies we will critically assess technical limitations of different approaches and point to existing challenges in microbiome research. We will have a special focus on host-microbiome interaction mechanisms that may be important to explain how dysbiosis can lead to chronic inflammation and drive processes that influence carcinogenesis and tumor progression in colon cancer. Finally, we will discuss the potential of recent developments of novel microbiota-based therapeutics and diagnostic tools for colorectal cancer.

Exosome: Function and Role in Cancer Metastasis and Drug Resistance

As a kind of nanometric lipidic vesicles, exosomes have been presumed to play a leading role in the regulation of tumor microenvironment through exosomes-mediated transfer of proteins and genetic materials. Tumor-derived exosomes are recognized as a critical determinant of the tumor progression. Intriguingly, some current observations have identified that exosomes are essential for several intercellular exchanges of proteins, messenger RNAs, noncoding RNAs (including long noncoding RNAs and microRNAs) as well as to the process of cancer metastasis and drug resistance. Herein, we review the role of exosomes and their molecular cargos in cancer invasion and metastasis, summarize how they interact with antitumor agents, and highlight their translational implications.

Significance of PYK2 level as a prognosis predictor in patients with colon adenocarcinoma after surgical resection

Background

Proline-rich/Ca²⁺-activated tyrosine kinase 2 (PYK2) belongs to the non-receptor tyrosine kinase family, regulates downstream signaling via catalyzing protein phosphorylation. We aimed to investigate clinical significance and mechanisms of PYK2 in colon adenocarcinoma (CAC).

Methods

Real time quantitative PCR and immunohistochemistry staining was used to evaluate the expression of PYK2 in clinical CAC tissues. Its association with clinicopathologic characteristics was analyzed by Chi-square test. Kaplan-Meier univariate survival analysis and multivariate Cox regression analysis were used to identify clinical significance of PYK2 in the overall survival of CAC patients. Transfection of PYK2 were conducted to reveal the underlying mechanism in regulating CAC progression.

Results

We found that PYK2 was upregulated in CAC tissues compared with normal colon tissues on both RNA and protein levels. Higher tissue PYK2 expression level was closely associated with lymph node metastasis. Statistical analyses indicated PYK2 as an independent prognostic biomarker for CAC. Cellular studies demonstrated that PYK2 enhanced the capacities of tumor proliferation and invasion. Moreover, the phosphorylation level of AKT was positively correlated with PYK2 expression, subsequently modulate expression of c-Myc and Cyclin D1, suggesting that PYK2 may promote tumor progression through activating AKT signaling.

Conclusion

High PYK2 in CAC tissues indicate poor prognosis.

Histone-lysine N-methyltransferase SETD7 is a potential serum biomarker for colorectal cancer patients

Background

There is an urgent need for the identification of new, clinically useful biomarkers of CRC to enhance diagnostic and prognostic capabilities.

Methods

We performed proteomic profiling on serum samples from paired pre- and post-operative CRC patients, colorectal polyps patients and healthy controls using an approach combining magnetic bead-based weak cation exchange and matrix-assisted laser desorption ionization-time of flight mass spectrometry. We next performed liquid chromatography-electrospray ionization-tandem mass spectrometry to identify the proteins and selected potential biomarker based on bioinformatics analysis of the TCGA and GEO dataset. We examined SETD7 expression in serum and tissue samples by ELISA and immunohistochemistry respectively and explored the biological function of SETD7 in vitro.

Findings

85 differentially expressed peptides were identified. Five peptides showing the most significant changes in abundance across paired pre- and post-operation CRC patients, colorectal polyps patients and healthy controls were identified as peptide regions of FGA, MUC5AC and SETD7. Bioinformatics analysis suggested that the up-regulation of SETD7 in CRC is relatively specific. Validation studies showed that SETD7 expression increased from healthy controls to those with colorectal polyps and finally CRC patients, and decreased after surgery. The sensitivity and specificity of SETD7 were 92.17% and 81.08%, with a high diagnostic value (AUC = 0.9477). In addition, SETD7 expression was significantly correlated with tumor stage and microsatellite instability. Knockdown of SETD7 inhibited cancer cell proliferation, induced G1/S cell cycle arrest and increased apoptosis.

Interpretation

Our data indicate that SETD7 could serve as a potential diagnostic and prognostic biomarker for CRC.

Artesunate induces apoptosis and autophagy in HCT116 colon cancer cells, and autophagy inhibition enhances the artesunate‑induced apoptosis

The present study assessed the antitumor effect of artesunate (ART) in vitro and in vivo, as well as its underlying mechanism of action in HCT116 colon cancer cells. An MTT assay, DAPI staining, flow cytometry, western blotting, immunohistochemistry, transmission electron microscopy and TUNEL assay were performed to study the molecular mechanism underlying the antitumor effects of ART in HCT116 colon cancer cells. ART was observed to inhibit proliferation by inducing the apoptosis of HCT116 cells both in vitro and in vivo. Flow cytometry analysis demonstrated that treatment with 2 and 4 µg/ml ART for 48 h induced early apoptosis in 22.7 and 33.8% of cells, respectively. In the xenograft tumors of BALB/c nude mice, TUNEL-positive cells increased in the ART group compared with that in the normal saline group. Furthermore,the associated mitochondrial cleaved-caspase 3, poly-ADP ribose polymerase (PARP), caspase 9 and Bcl-2-associated X protein levels increased while B-cell lymphoma-2 (Bcl-2) decreased both in the cell and animal ART-treated group. ART-treated cells also exhibited autophagy induction, as evidenced by increased protein expression levels of light chain 3 (LC3) and beclin-1, and the presence of autophagosomes. Notably, pharmacological blockade of autophagy activation using hydroxychloroquine markedly enhanced ART-induced apoptosis and increased the protein levels of cleaved caspase 3 and PARP, while decreasing the levels of LC3 and beclin-1. These findings suggested that the ART-induced autophagy may have a cytoprotective effect by suppressing apoptosis. In conclusion, ART may be a potentially clinically useful anticancer drug for human colon cancer. In addition, co-treatment with ART and an autophagy inhibitor may be an effective anticancer therapy.

B-cell lymphoma 2 is associated with advanced tumor grade and clinical stage, and reduced overall survival in young Chinese patients with colorectal carcinoma

The development of biomarkers that accurately and reliably detect colorectal cancer is a promising approach for colorectal cancer screening. Therefore, the objective of the present study was to evaluate the protein expression of α-methylacyl-CoA racemase (P504S/AMACR), tumor protein p53 (p53), B-cell lymphoma 2 (Bcl-2) and Ki-67/mindbomb E3 ubiquitin protein ligase 1 (MIB-1) in a population of Chinese patients with colorectal carcinoma. Colorectal tumors with matched normal tissue margins were collected from 148 surgical patients, and the demographic and clinical characteristics were collected. Immunohistochemical staining and western blot analysis of P504S/AMACR, p53, Bcl-2 and Ki-67/MIB-1 were conducted. Statistical analyses were used to compare protein expression in the colorectal tumors and matched normal tissue margins and to identify any associations between them and various clinicopathological parameters. Survival analyses were performed using the Kaplan-Meier method. In the present study, immunohistochemistry and western blot analysis revealed significantly higher expression of all four proteins in colorectal tumors compared with matched normal tissue margins (P<0.001). Spearman's rank correlation analysis revealed that Bcl-2 expression was negatively correlated with pathological grade and Tumor-Node-Metastasis (TNM) stage (-0.827 and -0.388, respectively; P<0.05). Bcl-2 expression was revealed to be a significant prognostic indicator of colorectal carcinoma [relative risk (95% CI), 0.703 (0.552-0.895); P<0.05]. The log-rank test revealed a significant association between low Bcl-2 expression and reduced overall survival (P=0.039), as well as a significant association between older age (>55 years) and reduced overall survival (P<0.001) in Chinese patients with colorectal carcinoma. In conclusion, low expression of Bcl-2 is significantly correlated with advanced pathological grade and TNM stage and is a prognostic indicator of reduced overall survival in young Chinese patients with colorectal carcinoma.

Peiminine inhibits colorectal cancer cell proliferation by inducing apoptosis and autophagy and modulating key metabolic pathways

Peiminine, a compound extracted from the bulbs of Fritillaria thunbergii and traditionally used as a medication in China and other Asian countries, was reported to inhibit colorectal cancer cell proliferation and tumor growth by inducing autophagic cell death. However, its mechanism of anticancer action is not well understood, especially at the metabolic level, which was thought to primarily account for peiminine's efficacy against cancer. Using an established metabolomic profiling platform combining ultra-performance liquid chromatography/tandem mass spectrometry with gas chromatography/mass spectrometry, we identified metabolic alterations in colorectal cancer cell line HCT-116 after peiminine treatment. Among the identified 236 metabolites, the levels of 57 of them were significantly (p < 0.05) different between peiminine-treated and -untreated cells in which 45 metabolites were increased and the other 12 metabolites were decreased. Several of the affected metabolites, including glucose, glutamine, oleate (18:1n9), and lignocerate (24:0), may be involved in regulation of the phosphoinositide 3-kinase/Akt/mammalian target of rapamycin (mTOR) pathway and in the oxidative stress response upon peiminine exposure. Peiminine predominantly modulated the pathways responsible for metabolism of amino acids, carbohydrates, and lipids. Collectively, these results provide new insights into the mechanisms by which peiminine modulates metabolic pathways to inhibit colorectal cancer cell growth, supporting further exploration of peiminine as a potential new strategy for treating colorectal cancer.

Identification of Kininogen 1 as a Serum Protein Marker of Colorectal Adenoma in Patients with a Family History of Colorectal Cancer

The serum protein markers of colorectal adenoma in patients with a family history of colorectal cancer have been rarely reported. Serum samples from colorectal adenoma patients with or without a family history of colorectal cancer and healthy controls were profiled using Matrix-Assisted Laser Desorption/Ionization Time of Flight Mass Spectrometry (MALDI-TOF-MS). The model to distinguish colorectal adenoma patients with a family history of colorectal cancer from atypical hereditary colorectal families (CRA-H) and sporadic colorectal adenoma patients without a family history of colorectal cancer (CRA-S) was established with 85.0% accuracy. The model distinguishing CRA-H from healthy individuals was established with 90.0% specificity and 86.7% sensitivity. Additionally, five peaks (2202, 5821, 3260, 2480, and 2218) showing differential expression in advanced colorectal adenoma patients with a family history of colorectal cancer were selected. The protein Kininogen 1 (KNG1) was identified in colorectal adenoma patients and validated using Western Blotting. KNG1 may be a biomarker for colorectal adenoma patients with a family history of colorectal cancer.

MiR-490-3p Functions As a Tumor Suppressor by Inhibiting Oncogene VDAC1 Expression in Colorectal Cancer

Colorectal cancer (CRC) is one of the most common cancers worldwide, usually with poor prognosis because many CRC patients are diagnosed at an advanced stage. Therefore, novel potential diagnostic and prognostic biomarkers are urgently needed. MicroRNAs have been reported to regulate a variety of biological processes, such as cell proliferation, differentiation and apoptosis. Accumulating studies have demonstrated that miR-490-3p could regulate the development and progression of multiple cancers, but its clinical significance and molecular mechanism in CRC are still elusive. Here, we try to further elucidate the regulatory mechanism of miR-490-3p in CRC. In the present study, miR-490-3p expression level observably down-regulated in CRC tissues and cell lines, and miR-490-3p expression in CRC tissues was significantly associated with TNM stage, histological grade, tumor size and overall survival (OS). In addition, we observed miR-490-3p expression was also decreased in CRC plasmas and could act as a promising diagnostic biomarker for screening CRC. Further studies in vitro demonstrated Voltage Dependent Anion Channel 1 (VDAC1) which highly expressed in CRC tissues and cell lines is a direct target of miR-490-3p, and miR-490-3p could markedly inhibit CRC cells proliferation, metastasis, invasion and anti-apoptosis through suppressing VDAC1/AMPK/mTOR pathway. These results indicated that miR-490-3p functions as a tumor suppressor in CRC, and may be a novel potential diagnostic and prognostic biomarker for CRC.

The Immunome of Colon Cancer: Functional In Silico Analysis of Antigenic Proteins Deduced from IgG Microarray Profiling

Characterization of the colon cancer immunome and its autoantibody signature from differentially-reactive antigens (DIRAGs) could provide insights into aberrant cellular mechanisms or enriched networks associated with diseases. The purpose of this study was to characterize the antibody profile of plasma samples from 32 colorectal cancer (CRC) patients and 32 controls using proteins isolated from 15,417 human cDNA expression clones on microarrays. 671 unique DIRAGs were identified and 632 were more highly reactive in CRC samples. Bioinformatics analyses reveal that compared to control samples, the immunoproteomic IgG profiling of CRC samples is mainly associated with cell death, survival, and proliferation pathways, especially proteins involved in EIF2 and mTOR signaling. Ribosomal proteins (e.g., RPL7, RPL22, and RPL27A) and CRC-related genes such as APC, AXIN1, E2F4, MSH2, PMS2, and TP53 were highly enriched. In addition, differential pathways were observed between the CRC and control samples. Furthermore, 103 DIRAGs were reported in the SEREX antigen database, demonstrating our ability to identify known and new reactive antigens. We also found an overlap of 7 antigens with 48 “CRC genes.” These data indicate that immunomics profiling on protein microarrays is able to reveal the complexity of immune responses in cancerous diseases and faithfully reflects the underlying pathology.

Characterisation of the oxysterol metabolising enzyme pathway in mismatch repair proficient and deficient colorectal cancer

Oxysterols are oxidised derivatives of cholesterol, formed by the enzymatic activity of several cytochrome P450 enzymes and tumour-derived oxysterols have been implicated in tumour growth and survival. The aim of this study was to profile the expression of oxysterol metabolising enzymes in primary colorectal cancer and assess the association between expression and prognosis.

Immunohistochemistry was performed on a colorectal cancer tissue microarray containing 650 primary colorectal cancers using monoclonal antibodies to CYP2R1, CYP7B1, CYP8B1, CYP27A1, CYP39A1, CYP46A1 and CYP51A1, which we have developed. Unsupervised hierarchical cluster analysis was used to examine the overall relationship of oxysterol metabolising enzyme expression with outcome and based on this identify an oxysterol metabolising enzyme signature associated with prognosis.

Cluster analysis of the whole patient cohort identified a good prognosis group (mean survival=146 months 95% CI 127-165 months) that had a significantly better survival (δ²=12.984, p<0.001, HR=1.983, 95% CI 1.341-2.799) than the poor prognosis group (mean survival=107 months, 95% CI 98-123 months). For the mismatch repair proficient cohort, the good prognosis group had a significantly better survival (δ²=8.985, p=0.003, HR=1.845, 95% CI 1.227-2.774) than the poor prognosis group. Multi-variate analysis showed that cluster group was independently prognostically significant in both the whole patient cohort (p=0.02, HR=1.554, 95% CI 1.072-2.252) and the mismatch repair proficient group (p=0.04, HR=1.530, 95% CI 1.014-2.310).

Individual oxysterol metabolising enzymes are overexpressed in colorectal cancer and an oxysterol metabolising enzyme expression profile associated with prognosis has been identified in the whole patient cohort and in mismatch repair proficient colorectal cancers.

Effect of long non-coding RNA Gas5 on proliferation, migration, invasion and apoptosis of colorectal cancer HT-29 cell line

Objective

This study aims to investigate the effect of long non-coding RNA (lncRNA) Gas5 on proliferation, migration, invasion and apoptosis of colorectal cancer (CRC) HT-29 cell line.

Methods

CRC and normal tissues were collected and prepared from a total of 126 CRC patients, and normal intestinal epithelial cell line FHC and CRC cell lines (HCT-8, HT-29, HCT-116 and SW-480) were prepared. Gas5 expression was detected by quantitative reverse transcriptase-polymerase chain reaction. HT-29 cell line exhibiting the lowest Gas5 expression was selected for further experimentation and divided into blank, negative control and pcNDA-Gas5 groups. The cell counting kit-8 assay was used to test cell proliferation. Flow cytometry was applied to examine cell apoptosis. Transwell assay was performed to detect the migration and invasion of HT-29 cells. The mRNA and protein expression of factors in the classical proliferation (Akt/Erk) and apoptosis (caspase-9/caspase-3) pathways were detected.

Results

Gas5 expression was lower in CRC tissues compared to the adjacent normal tissues, and is also lower in CRC cell lines than FHC cell line. Gas5 expression was associated with tumor size and TNM staging. Gas5 expression, distant metastasis, tumor differentiation and TNM staging were independent CRC prognostic factors. The results showed that elevated Gas5 expression inhibited proliferation, migration and invasion, but promoted apoptosis of CRC cells. Meanwhile, elevated Gas5 expression inhibited mRNA expression of Akt and Erk and protein expression of p-Akt and p-Erk, which promoted Casp9 mRNA and pho-Casp9 protein expression but inhibited Casp3 mRNA and pho-Casp3 protein expression.

Conclusion

The findings indicated that overexpression of lncRNA Gas5 can inhibit the proliferation, migration and invasion but promote apoptosis of CRC cells.

The differential expression of omega-3 and omega-6 fatty acid metabolising enzymes in colorectal cancer and its prognostic significance

Background:

Colorectal cancer is a common malignancy and one of the leading causes of cancer-related deaths. The metabolism of omega fatty acids has been implicated in tumour growth and metastasis.

Methods:

This study has characterised the expression of omega fatty acid metabolising enzymes CYP4A11, CYP4F11, CYP4V2 and CYP4Z1 using monoclonal antibodies we have developed. Immunohistochemistry was performed on a tissue microarray containing 650 primary colorectal cancers, 285 lymph node metastasis and 50 normal colonic mucosa.

Results:

The differential expression of CYP4A11 and CYP4F11 showed a strong association with survival in both the whole patient cohort (hazard ratio (HR)=1.203, 95% CI=1.092–1.324, χ²=14.968, P=0.001) and in mismatch repair-proficient tumours (HR=1.276, 95% CI=1.095–1.488, χ²=9.988, P=0.007). Multivariate analysis revealed that the differential expression of CYP4A11 and CYP4F11 was independently prognostic in both the whole patient cohort (P=0.019) and in mismatch repair proficient tumours (P=0.046).

Conclusions:

A significant and independent association has been identified between overall survival and the differential expression of CYP4A11 and CYP4F11 in the whole patient cohort and in mismatch repair-proficient tumours.

Low-grade slightly elevated and polypoid colorectal adenomas display differential β-catenin-TCF/LEF activity, c-Myc, and cyclin D1 expression

AIM

To comparatively investigate the cellular and molecular characteristics of low-grade slightly elevated adenomas and polypoid adenomas.

METHODS

Colorectal tumors were collected from 24 patients with slightly elevated adenomas and 23 patients with polypoid adenomas. Five commonly mutated genes (APC, BRAF, KRAS, NRAS, and PIK3CA) were selected for mutational analysis. Paraffin-embedded tumor sections were used to calculate the apoptotic index (AI) and Ki-67 labeling index (KLI). Two pure colorectal epithelial cell lines were created by pooling the slightly elevated and polypoid tumors. Western blots, luciferase assays for β-catenin-T-cell factor protein/β-catenin-lymphoid enhancer factor (β-catenin-TCF/LEF)-driven transcriptional activity, and caspase activity assays were conducted on the two cell lines.

RESULTS

Slightly elevated lesions showed a significantly lower APC mutational frequency and a significantly higher KRAS mutational frequency (both P < 0.05). Slightly elevated lesions showed a significantly lower AI (P < 0.05). β-catenin and β-catenin-TCF/LEF-driven transcriptional activity was significantly upregulated in slightly elevated lesions (both P < 0.05). In slightly elevated lesions, c-Myc was significantly downregulated, while cyclin D1 was significantly upregulated (both P < 0.05). β-catenin-TCF/LEF-driven transcriptional activity was negatively correlated with c-Myc (ρ = -0.78). Slightly elevated lesions displayed significant Bcl-2 and Bcl-xL upregulation (both P < 0.05) along with significant decreases in caspase-9 and caspase-3 activity (both P < 0.05). c-Myc was negatively correlated with Bcl-2 and Bcl-xL (ρ = -0.74 and -0.78, respectively).

CONCLUSION

The lower apoptotic activity of low-grade slightly elevated adenomas can be partly attributed to upregulated β-catenin pathway activity and downregulated c-Myc expression.

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

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

Biomarker discovery by proteomics-based approaches for early detection and personalized medicine in colorectal cancer

About one million people per year develop colorectal cancer (CRC) and approximately half of them die. The extent of the disease (i.e. local invasion at the time of diagnosis) is a key prognostic factor. The 5-year survival rate is almost 90% in the case of delimited CRC and 10% in the case of metastasized CRC. Hence, one of the great challenges in the battle against CRC is to improve early diagnosis strategies. Large-scale proteomic approaches are widely used in cancer research to search for novel biomarkers. Such biomarkers can help in improving the accuracy of the diagnosis and in the optimization of personalized therapy. Herein, we provide an overview of studies published in the last 5 years on CRC that led to the identification of protein biomarkers suitable for clinical application by using proteomic approaches. We discussed these findings according to biomarker application, including also the role of protein phosphorylation and cancer stem cells in biomarker discovery. Our review provides a cross section of scientific approaches and can furnish suggestions for future experimental strategies to be used as reference by scientists, clinicians and researchers interested in proteomics for biomarker discovery.

Protein content and functional characteristics of serum-purified exosomes from patients with colorectal cancer revealed by quantitative proteomics

Tumor cells of colorectal cancer (CRC) release exosomes into the circulation. These exosomes can mediate communication between cells and affect various tumor-related processes in their target cells. We present a quantitative proteomics analysis of the exosomes purified from serum of patients with CRC and normal volunteers; data are available via ProteomeXchange with identifier PXD003875. We identified 918 proteins with an overlap of 725 Gene IDs in the Exocarta proteins list. Compared with the serum-purified exosomes (SPEs) of normal volunteers, we found 36 proteins upregulated and 22 proteins downregulated in the SPEs of CRC patients. Bioinformatics analysis revealed that upregulated proteins are involved in processes that modulate the pretumorigenic microenvironment for metastasis. In contrast, differentially expressed proteins (DEPs) that play critical roles in tumor growth and cell survival were principally downregulated. Our study demonstrates that SPEs of CRC patients play a pivotal role in promoting the tumor invasiveness, but have minimal influence on putative alterations in tumor survival or proliferation. According to bioinformatics analysis, we speculate that the protein contents of exosomes might be associated with whether they are involved in premetastatic niche establishment or growth and survival of metastatic tumor cells. This information will be helpful in elucidating the pathophysiological functions of tumor-derived exosomes, and aid in the development of CRC diagnostics and therapeutics.

Progress and prospects for the discovery of biomarkers for gastric cancer: a focus on proteomics

INTRODUCTION

Patient outcomes from gastric cancer vary due to the complexity of stomach carcinogenesis. Recent research using proteomic technologies has targeted components of all of these systems in order to develop biomarkers to aid the early diagnosis of gastric cancer and to assist in prognostic stratification. Areas covered: This review is comprised of evidence obtained from literature searches from PubMed. It covers the evidence of diagnostic, prognostic, and predictive biomarkers for gastric cancer using proteomic technologies, and provides up-to-date references. Expert commentary: The proteomic technologies have not only enabled the screening of a large number of samples, but also enabled the identification of diagnostic, prognostic and predictive biomarkers for gastric cancer. While major challenges still remain, to date, proteomic studies in gastric cancer have provided a wealth of information in revealing proteome alterations associated with the disease.

Complementary Glycomic Analyses of Sera Derived from Colorectal Cancer Patients by MALDI-TOF-MS and Microchip Electrophoresis

Colorectal cancer is the fourth most prevalent cancer in the United States, yet there are no reliable noninvasive early screening methods available. Serum-based glycomic profiling has the necessary sensitivity and specificity to distinguish disease states and provide diagnostic potential for this deadly form of cancer. We applied microchip electrophoresis and MALDI-TOF-MS-based glycomic procedures to 20 control serum samples and 42 samples provided by patients diagnosed with colorectal cancer. Within the identified glycans, the position of fucose units was located to quantitate possible changes of fucosyl isomeric species associated with the pathological condition. MALDI-MS data revealed several fucosylated tri- and tetra-antennary glycans which were significantly elevated in their abundance levels in the cancer samples and distinguished the control samples from the colorectal cancer cohort in the comprehensive profiles. When compared to other cancers studied previously, some unique changes appear to be associated with colorectal cancer, being primarily associated with fucosyl isomers. Through MS and microchip electrophoresis-based glycomic methods, several potential biomarkers were identified to aid in the diagnosis and differentiation of colorectal cancer. With its unique capability to resolve isomers, microchip electrophoresis can yield complementary analytical information to MS-based profiling.

Integrative analysis of the colorectal cancer proteome: potential clinical impact

INTRODUCTION

Colorectal cancer (CRC) is one of the common types of cancer that affects a significant proportion of the population and is a major contributor to cancer related mortality. The relatively poor survival rate of CRC could be improved through the identification of clinically useful biomarkers. Areas covered: This review highlights the need for biomarkers and discusses recent proteomics discoveries in the aspects of CRC clinical practice including diagnosis, prognosis, therapy, screening and molecular pathological epidemiology (MPE). Studies have been evaluated in relation to biomarker target, methodology, sample selection, limitations, and potential impact. Finally, the progress in proteomic approaches is briefly discussed and the main difficulties facing the translation of proteomics biomarkers into the clinical practice are highlighted. Expert commentary: The establishment of specific guidelines, best practice recommendations and the improvement in proteomic strategies will significantly improve the prospects for developing clinically useful biomarkers.

Discovery of genes from feces correlated with colorectal cancer progression

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

Upregulation of spondin-2 predicts poor survival of colorectal carcinoma patients

Colorectal cancer (CRC) is the third and second most common cancer in males and females worldwide, respectively. Spondin-2 is a conserved secreted extracellular matrix protein and a candidate cancer biomarker. Here we found that Spondin-2 mRNA was upregulated in CRC tissues using quantitative RT-PCR and data-mining of public Oncomine microarray datasets. Spondin-2 protein was increased in CRC tissues, as revealed by immunohistochemistry analyses of two tissue microarrays containing 180 cases. Spondin-2 gene expression was significantly associated with CRC stage, T stage, M stage and Dukes stage, while its protein was associated with age and M stage. Kaplan-Meier analysis revealed that the upregulated Spondin-2 mRNA and protein predicted poor prognosis of CRC patients. Univariate and multivariate Cox regression analyses indicated that grade, recurrence, N stage and high Spondin-2 were independent predictors of overall survival of CRC patients. ELISA revealed that plasma Spondin-2 was upregulated in CRC and dropped after surgery. Receiver operating characteristic curve analysis demonstrated that plasma Spondin-2 has superior predictive performance for CRC with an area under the curve of 0.959 and the best sensitivity/specificity of 100%/90%. Furthermore, ectopic expression of Spondin-2 enhanced colon cancer cell proliferation. Spondin-2 could be an independent diagnostic and prognostic biomarker of colon cancer.

Overexpression of lncRNA AFAP1-AS1 correlates with poor prognosis and promotes tumorigenesis in colorectal cancer

Accumulating evidence has shown that long non-coding RNAs (lncRNAs) are emerging as key molecules in human malignancies. The lncRNA actin filament associated protein 1 antisense RNA1 (AFAP1-AS1) was recently found deregulated in several cancers. However, its expression pattern, clinical performance and functional roles in colorectal cancer (CRC) had not been addressed. In this study, we found that AFAP1-AS1 was aberrantly over-expressed in CRC tissues and closely correlated with tumor size, TNM stage and distant metastasis. Kaplan-Meier analysis indicated that patients with high level of AFAP1-AS1 expression had poorer overall survival (OS) and disease-free survival (DFS). Univariate and multivariable Cox regression analyses further identified that up-regulated AFAP1-AS1 might act as an independent prognostic factor for CRC patients. Moreover, AFAP1-AS1 depletion resulted in the inhibition of CRC cell proliferation and colony formation. In addition, AFAP1-AS1 knockdown induced G0/G1 cell cycle arrest in CRC cells. Taken together, our findings indicate that AFAP1-AS1 is significantly up-regulated in CRC, which may act as an oncogene and correlate with tumor malignant progression and poor prognosis of CRC. This study may shed a new light on better understanding the pathogenesis of CRC. Moreover, AFAP1-AS1 also may be a promising diagnostic and therapeutic target for this deadly disease.

Mass spectrometry based translational proteomics for biomarker discovery and application in colorectal cancer

Colorectal cancer (CRC) is a leading cause of cancer-related death in the world. Clinically, early detection of the disease is the most effective approach to tackle this tough challenge. Discovery and development of reliable and effective diagnostic tools for the assessment of prognosis and prediction of response to drug therapy are urgently needed for personalized therapies and better treatment outcomes. Among many ongoing efforts in search for potential CRC biomarkers, MS-based translational proteomics provides a unique opportunity for the discovery and application of protein biomarkers toward better CRC early detection and treatment. This review updates most recent studies that use preclinical models and clinical materials for the identification of CRC-related protein markers. Some new advances in the development of CRC protein markers such as CRC stem cell related protein markers, SRM/MRM-MS and MS cytometry approaches are also discussed in order to address future directions and challenges from bench translational research to bedside clinical application of CRC biomarkers.

Empirical evaluation demonstrated importance of validating biomarkers for early detection of cancer in screening settings to limit the number of false-positive findings

OBJECTIVES

Search for biomarkers for early detection of cancer is a very active area of research, but most studies are done in clinical rather than screening settings. We aimed to empirically evaluate the role of study setting for early detection marker identification and validation.

STUDY DESIGN AND SETTING

A panel of 92 candidate cancer protein markers was measured in 35 clinically identified colorectal cancer patients and 35 colorectal cancer patients identified at screening colonoscopy. For each case group, we selected 38 controls without colorectal neoplasms at screening colonoscopy. Single-, two- and three-marker combinations discriminating cases and controls were identified in each setting and subsequently validated in the alternative setting.

RESULTS

In all scenarios, a higher number of predictive biomarkers were initially detected in the clinical setting, but a substantially lower proportion of identified biomarkers could subsequently be confirmed in the screening setting. Confirmation rates were 50.0%, 84.5%, and 74.2% for one-, two-, and three-marker algorithms identified in the screening setting and were 42.9%, 18.6%, and 25.7% for algorithms identified in the clinical setting.

CONCLUSION

Validation of early detection markers of cancer in a true screening setting is important to limit the number of false-positive findings.

A Comprehensive Study of Extramural Venous Invasion in Colorectal Cancer

Colorectal cancer is a common malignancy and a leading cause of cancer related death. Cancer staging following resection is key to determining any adjuvant therapy in those patients with high risk disease. In colorectal cancer, tumour stage and lymph node stage are the main pathological factors which have been considered to influence outcome. Increasing emphasis is now being placed on other factors, especially the presence of extramural venous invasion (EMVI). It is important to understand the relationship of EMVI with other pathological factors and to confirm that in an individual centre that EMVI is being detected at an appropriate rate and is of prognostic significance. This comprehensive study assesses the reporting and prognostic significance of EMVI in a single centre, using prospectively collected data from histopathology reports of a cohort of 2405 patients who underwent surgery for colorectal cancer over a nine year period. Overall, EMVI was reported in 27.9% of colorectal cancer excision specimens. In tumours (n = 1928) that had not received neoadjuvant therapy, the presence of EMVI varied significantly depending on tumour site (χ2 = 12.03, p<0.005), tumour stage (χ2 = 268.188, p<0.001), lymph node stage (χ2 = 294.368, p<0.001) and Dukes' stage (χ2 = 253.753, p<0.001). Multivariate analysis confirmed EMVI as a significant independent prognostic indicator (p<0.001). In conclusion, the presence of EMVI as an independent prognostic indicator is shown and is related to other pathological and prognostic factors. This study emphasises the requirement for the accurate identification of EMVI in colorectal cancer excision specimens and also understanding the relationship of EMVI with other prognostic factors.

The expression and prognostic significance of bcl-2-associated transcription factor 1 in rectal cancer following neoadjuvant therapy

AIMS

bcl-2-associated transcription factor 1 (BCLAF1) is a nuclear protein that binds to bcl-related proteins and can induce apoptosis and autophagy. The aim of this study was to investigate the expression of BCLAF1 in a series of rectal cancers following neoadjuvant therapy.

METHODS AND RESULTS

Immunohistochemistry was performed on a post-neoadjuvant therapy rectal cancer tissue microarray. It contained rectal cancers (n = 248), lymph node metastases (n = 76), and non-neoplastic rectal mucosal samples (n = 73). A monoclonal antibody against BCLAF1 that we have developed was used. Non-neoplastic rectal epithelium showed nuclear localization of BCLAF1 in both crypt and surface epithelial cells, whereas rectal cancers showed both nuclear and cytoplasmic BCLAF1 expression. Most rectal cancers showed moderate or strong nuclear immunoreactivity, but showed weak cytoplasmic immunoreactivity. Cytoplasmic BCLAF1 expression was increased in primary rectal cancers as compared with non-neoplastic rectal mucosa (P = 0.008). Negative and weak nuclear BCLAF1 expression was associated with a poor prognosis [hazard ratio (HR) 0.502, 95% confidence interval (CI) 0.269-0.939, χ(2) = 4.876, P = 0.027]. Nuclear BCLAF1 expression was independently prognostic in a multivariate model (HR 0.431, 95% CI 0.221-0.840, P = 0.013).

CONCLUSIONS

This study has shown that both cytoplasmic BCLAF1 expression and nuclear BCLAF1 expression are increased in post-neoadjuvant therapy rectal cancer, and that negative and weak nuclear BCLAF1 expression are independently associated with a poor prognosis.