Identification of MSX1 and DCLK1 as mRNA Biomarkers for Colorectal Cancer Detection Through DNA Methylation Information

In silico identification of novel biomarkers for key players in transition from normal colon tissue to adenomatous polyps

Adenomatous polyps of the colon are the most common neoplastic polyps. Although most of adenomatous polyps do not show malign transformation, majority of colorectal carcinomas originate from neoplastic polyps. Therefore, understanding of this transformation process would help in both preventive therapies and evaluation of malignancy risks. This study uncovers alterations in gene expressions as potential biomarkers that are revealed by integration of several network-based approaches. In silico analysis performed on a unified microarray cohort, which is covering 150 normal colon and adenomatous polyp samples. Significant gene modules were obtained by a weighted gene co-expression network analysis. Gene modules with similar profiles were mapped to a colon tissue specific functional interaction network. Several clustering algorithms run on the colon-specific network and the most significant sub-modules between the clusters were identified. The biomarkers were selected by filtering differentially expressed genes which also involve in significant biological processes and pathways. Biomarkers were also validated on two independent datasets based on their differential gene expressions. To the best of our knowledge, such a cascaded network analysis pipeline was implemented for the first time on a large collection of normal colon and polyp samples. We identified significant increases in TLR4 and MSX1 expressions as well as decrease in chemokine profiles with mostly pro-tumoral activities. These biomarkers might appear as both preventive targets and biomarkers for risk evaluation. As a result, this research proposes novel molecular markers that might be alternative to endoscopic approaches for diagnosis of adenomatous polyps.

Hypermethylation of PDX1, EN2, and MSX1 predicts the prognosis of colorectal cancer

Despite numerous observations regarding the relationship between DNA methylation changes and cancer progression, only a few genes have been verified as diagnostic biomarkers of colorectal cancer (CRC). To more practically detect methylation changes, we performed targeted bisulfite sequencing. Through co-analysis of RNA-seq, we identified cohort-specific DNA methylation markers: CpG islands of the intragenic regions of PDX1, EN2, and MSX1. We validated that these genes have oncogenic features in CRC and that their expression levels are increased in correlation with the hypermethylation of intragenic regions. The reliable depth of the targeted bisulfite sequencing data enabled us to design highly optimized quantitative methylation-specific PCR primer sets that can successfully detect subtle changes in the methylation levels of candidate regions. Furthermore, these methylation levels can divide CRC patients into two groups denoting good and poor prognoses. In this study, we present a streamlined workflow for screening clinically significant differentially methylated regions. Our discovery of methylation markers in the PDX1, EN2, and MSX1 genes suggests their promising performance as prognostic markers and their clinical application in CRC patients.

An experimental strategy for detecting patterns of DNA modification reveals gene-specific alterations associated with worse outcomes in colorectal cancer patients. Many genomic regions undergo a process of chemical modification called methylation, which can strongly affect the expression of nearby genes. Many cancers exhibit abnormal methylation, and South Korean researchers led by Tae-You Kim of Seoul National University and Lark Kyun Kim of Yonsei University College of Medicine, Seoul, have developed a strategy for identifying such tumor-specific modifications. They identified a trio of genes that undergo excessive methylation in colorectal cancer, and show that this ‘signature’ is associated with more advanced metastatic tumors and shorter overall survival. The results from this study could give clinicians an additional diagnostic tool, and highlight the potential utility of performing such methylation profiling in other cancer types.

A Novel Glycolysis and Hypoxia Combined Gene Signature Predicts the Prognosis and Affects Immune Infiltration of Patients with Colon Cancer

Purpose

We aimed to characterize the expression patterns of glycolysis and hypoxia genes in colon cancers as well as their value in prognosis and immune microenvironment.

Methods

The expression profiles were acquired from the Cancer Genome Atlas database. Enrichment of hypoxia and glycolysis gene sets in colon cancer was identified by gene set enrichment analysis. Then, a prognostic signature was built up after Cox regression analyses, and overall survival analysis validated the predictive ability. Immune status and infiltration in cancer tissues were explored using the single sample gene set enrichment analysis and CIBERSORT algorithm. A nomogram model integrating clinical variables and the gene signature was established and assessed.

Results

Altogether, 378 cancer and 39 control cases were enrolled. Three glycolysis gene sets and two hypoxia gene sets were enriched in colon cancer (P < 0.05). Five independent genes (ENO3, GPC1, P4HA1, SPAG4, and STC2) were significantly correlated with prognosis of colon cancer patients. Patients with higher risks had significantly better prognosis than those with lower risks (P = 0.002 and AUC = 0.750), which was also observed in the elderly, female and stage I–II subgroups (P < 0.05). In high-risk cases, proportion of NK cells resting increased (P < 0.05) while that of dendritic cells activated (P < 0.05), dendritic cells resting (P < 0.01) and monocytes (P < 0.01) decreased. Besides, expressions of 22 checkpoint genes were found abnormal in groups with different risks (P < 0.05). The predictive nomogram presented satisfactory performance with C-index of 0.771 (0.712–0.830). The area under ROC curve was 0.796 and 0.803 for 3- and 5-year survival prediction, respectively.

Conclusion

A glycolysis and hypoxia combined gene signature was a promising method to evaluate the prognosis and immune infiltration of colon cancer patients, which may provide a new tool for cancer management.

A narrative review of the roles of muscle segment homeobox transcription factor family in cancer

Deregulation of many homeobox genes has been observed in various cancers and has caused functional implications in the tumor progression. In this review, we will focus on the roles of the human muscle segment homeobox (MSX) transcription factor family in the process of tumorigenesis. The MSX transcription factors, through complex downstream regulation mechanisms, are promoters or inhibitors of diverse cancers by participating in cell proliferation, cell invasion, cell metastasis, cell apoptosis, cell differentiation, drug resistance of tumors, maintenance of tumor stemness, and tumor angiogenesis. Moreover, their upstream regulatory mechanisms in cancers may include: gene mutation and chromosome aberration; DNA methylation and chromatin modification; regulation by non-coding RNAs; regulation by other transcription factors and post-translational modification. These mechanisms may provide a better understanding of why MSX transcription factors are abnormally expressed in tumors. Notably, intermolecular interactions and post-translational modification can regulate the transcriptional activity of MSX transcription factors. It is also crucial to know what affects the transcriptional activity of MSX transcription factors in tumors for possible interventions in them in the future. This systematic summary of the regulatory patterns of the MSX transcription factor family may help to further understand the mechanisms involved in transcriptional regulation and also provide new therapeutic approaches for tumor progression.

DCLK1, a promising colorectal cancer stem cell marker, regulates tumor progression and invasion through miR-137 and miR-15a dependent manner

Cancer stem cells (CSCs) are thought to be a major player in tumor initiation, progression, and metastasis. Targeting CSCs for elimination presents a promising therapeutic strategy; however, this approach will require a stronger understanding of CSC biology and identification of CSC-specific markers. The present study was conducted to examine the correlation between DCLK1 and miR-137 and miR-15a levels in colorectal cancer. A total of 222 samples, including 181 colorectal cancer specimens, 24 adenomatosis, and 17 non-adenomatosis colonic polyps, were stained for DCLK1 expression using immunohistochemistry. Also, expression of miR-137 and miR-15a was assessed in colorectal cancer with high and low DCLK1 expression levels. Most colorectal cancer specimens (76%) showed strong expression of DCLK1, whereas only 21% of adenomatous and none of non-adenomatous colonic polyps showed strong DCLK1 expression. A significant difference in DCLK1 expression was found between colorectal cancer, adenomatous, and non-adenomatous colonic polyps (P < 0.001). Higher expression of DCLK1 was more frequently detected in colorectal cases with larger tumor size (P = 0.03), poor differentiation (P = 0.03), and lymph node involvement (P = 0.04). Comparison of miR-137 and miR-15a in colorectal cancer cases revealed a significant inverse correlation with DCLK1 expression (P = 0.03 and P = 0.04, respectively). DCLK1 may act as a candidate marker for colorectal cancer stem cells. The critical role of DCLK1 in colorectal cancer suggests that it may represent an early diagnostic marker and therapeutic target; however, further investigation is warranted.

A Combined four-mRNA Signature Associated with Lymphatic Metastasis for Prognosis of Colorectal Cancer

Background: Colorectal cancer (CRC) is one of the most common malignant tumors in the world. Lymph node metastasis (LNM) is a common mode of metastasis of CRC. However, the combined mRNA biomarkers associated with LNM of CRC that can effectively predict CRC prognosis have not been reported yet.

Methods: To identify biomarkers that are associated with LNM, we collected data from the The Cancer Genome Atlas (TCGA) database. The edgeR package was searched to seek LNM-related genes by comparisons between cancer samples and normal colorectal tissues and between LNM and non-LNM (NLNM) of CRC. Univariate and multivariate regression analysis of genes in the intersection to build gene signature associated with independent prognosis of CRC, and then verified by Kaplan-Meier curve and log-rank test, receiver operating characteristic (ROC) curve was used to determine the efficiency of survival prediction of our four-mRNA signature. Finally, the potential molecular mechanisms and properties of these gene signature were also explored with functional and pathway enrichment analysis.

Results: 329 mRNAs were up-regulated in CRC tissues with LNM, and 8461 mRNAs were up-regulated in CRC tissues, the intersection is 100 mRNAs. After univariate and multivariate Cox regression analysis of 100 mRNAs, a novel four LNM related mRNAs (EPHA8, KRT85, GABRA3, and CLPSL1) were screened as independent prognostic indicators of CRC. Surprisingly, the four-mRNA signature can predict the prognosis of CRC patients independently of clinical factors andthe area under the curve (AUC) of the ROC is 0.730. The novel four-mRNA signature was used to identify high and low-risk groups. Stratified analysis indicated the risk score based on four-mRNA signature was an independent prognostic indicator for female, T3+T4, N1+N2 ,stage III+IV and patients with no new tumor event. Functional annotation of this risk model in high-risk patients revealed that pathways associated with neuroactive ligand-receptor interaction, estrogen signaling pathway, and steroid hormone biosynthesis.

Conclusions: By conducting TCGA data mining, our study demonstrated that a four-mRNA signature associated with LNM can be used as a combined biomarker for independent prognosis of CRC.

Increased DCLK1 correlates with the malignant status and poor outcome in malignant tumors: a meta-analysis

Doublecortin-like kinase 1 (DCLK1) has been found to be involved in malignant biological behavior of cancers and poor prognosis of cancer patients. The aim of this meta-analysis was to systematically clarify the relationships between expression level of DCLK1 and clinicopathological characteristics in tumors and assess its clinical value in cancer diagnosis and prognosis. 18 eligible studies with a total of 2660 patients were identified by searching the electronic bibliographic databases. Pooled results showed that DCLK1 was highly expressed in tissues from cancer patients compared to normal tissues (OR, 10.00), and overexpression of DCLK1 was significantly correlated with advanced clinical stage (OR, 2.48), positive lymph node metastasis (OR, 2.18), poorly differentiated cancers (OR, 1.83) and poor overall survival (HR, 2.15). The overall combined sensitivity and specificity for DCLK1 in distinguishing malignant tumors were 0.58 and 0.90, respectively. The mean diagnostic odds ratio was 12.70, and the corresponding area under the summary receiver operating characteristic curve was 0.78. In summary, our study indicated that DCLK1 could be a risk factor for development of malignant tumors and may serve as a promising diagnostic and prognostic biomarker for malignant tumors.