Genetics and Genetic Biomarkers in Sporadic Colorectal Cancer

Temozolomide-associated hypermutation in gliomas

Low-grade gliomas cause considerable morbidity and most will recur after initial therapy. At recurrence, low-grade gliomas can undergo transformation to high-grade gliomas (grade III or grade IV), which are associated with worse prognosis. Temozolomide (TMZ) provides survival benefit in patients with glioblastomas, but its value in patients with low-grade gliomas is less clear. A subset of TMZ-treated, isocitrate dehydrogenase‒mutant, low-grade astrocytomas recur as more malignant tumors with thousands of de novo, coding mutations bearing a signature of TMZ-induced hypermutation. Preliminary studies raise the hypothesis that TMZ-induced hypermutation may contribute to malignant transformation, although with highly variable latency. On the other hand, hypermutated gliomas have radically altered genomes that present new opportunities for therapeutic intervention. In light of these findings and the immunotherapy clinical trials they inspired, how do patients and providers approach the risks and benefits of TMZ therapy? This review discusses what is known about the mechanisms and consequences of TMZ-induced hypermutation and outstanding questions regarding its clinical significance.

FBXW7 circular RNA regulates proliferation, migration and invasion of colorectal carcinoma through NEK2, mTOR, and PTEN signaling pathways in vitro and in vivo

Backgrounds

A number of circular RNAs (circRNAs) have been identified in various cancer including F-box and WD repeat domain containing 7 (FBXW7) circular RNA (circ-FBXW7), which can suppress glioma cell growth. However, the role of circ-FBXW7 in colorectal cancer (CRC) remains unclear. We aimed to investigate the effect and mechanisms of circ-FBXW7 on CRC progression.

Methods

The expression of circ-FBXW7 in CRC patients was detected by PCR. Stably knockdown of circ-FBXW7 (si circ-FBXW7) cell lines and overexpression of circ-FBXW7 (oe circ-FBXW7) cell lines were constructed by small interfering RNA method and plasmids transfection in CRC SW480 and SW620 cells. The functional experiments including cell proliferation, migration and invasion were carried out by cell counting kit-8 (CCK-8) assay, wound healing assay and trans well assay. The xenograft animal models were established to evaluate the effect and the underlying molecular mechanisms of circ-FBXW7 on CRC progression.

Results

CRC samples had a significantly lower level of circ-FBXW7 compared to normal tissue. si circ-FBXW7 notably promoted the proliferation, colony formation, cell migration and invasion of CRC cell in vitro. On contrast, circ-FBXW7 overexpressed significantly suppressed CRC cell proliferation, migration and invasion. Similarly, si circ-FBXW7 stimulated the tumor growth and circ-FBXW7 overexpression repressed the tumor progression in SW480 and SW620 tumor models, which suggested that circ-FBXW7 could serve as a target biomarker of CRC. Further study found that si circ-FBXW7 up-regulated the mRNA and protein expressions of NEK2 and mTOR, and diminished the PTEN expression. Whereas, overexpressed circ-FBXW7 induced the tumor suppression via reversing the expressions of NEK2, mTOR, and PTEN.

Conclusion

circ-FBXW7 plays a major role in controlling the progression of CRC through NEK2, mTOR, and PTEN signaling pathways and may be a potential therapeutic target for CRC treatment.

Graphical abstract

Circ-FBXW7 controls the progression of CRC through NEK2, mTOR, and PTEN signaling pathways and its overexpression inhibits colorectal cancer cell migration and invasion, suggesting the potential therapeutic target for CRC treatment.

Fecal DNA Testing for Colorectal Cancer Screening

Fecal (or stool) DNA examination is a noninvasive strategy recommended by several medical professional societies for colorectal cancer (CRC) screening in average-risk individuals. Fecal DNA tests assay stool for human DNA shed principally from the colon. Colonic lesions such as adenomatous and serrated polyps and cancers exfoliate cells containing neoplastically altered DNA that may be detected by sensitive assays that target specific genetic and epigenetic biomarkers to discriminate neoplastic lesions from non-neoplastic tissue. Cross-sectional validation studies confirmed initial case-control studies' assessment of performance of an optimized multitarget stool DNA (mt-sDNA) test, leading to approval by the US Food and Drug Administration in 2014. Compared to colonoscopy, mt-sDNA showed sensitivity of 92% for detection of CRC, much higher than the 74% sensitivity of another recommended noninvasive strategy, fecal immunochemical testing (FIT). Detections of advanced adenomas and sessile serrated polyps were higher with mt-sDNA than FIT (42% versus 24% and 42% versus 5%, respectively), but overall specificity for all lesions was lower (87% versus 95%). The mt-sDNA test increases patient life-years gained in CRC screening simulations, but its cost relative to other screening strategies needs to be reduced by 80-90% or its sensitivity for polyp detection enhanced to be cost effective. Noninvasive CRC screening strategies such as fecal DNA, however, have the potential to significantly increase national screening rates due to their noninvasive nature and convenience for patients.

LncRNA GLCC1 promotes colorectal carcinogenesis and glucose metabolism by stabilizing c-Myc

Long non-coding RNAs (lncRNAs) contribute to colorectal cancer (CRC). However, the role of lncRNAs in CRC metabolism, especially glucose metabolism remains largely unknown. In this study, we identify a lncRNA, GLCC1, which is significantly upregulated under glucose starvation in CRC cells, supporting cell survival and proliferation by enhancing glycolysis. Mechanistically, GLCC1 stabilizes c-Myc transcriptional factor from ubiquitination by direct interaction with HSP90 chaperon and further specifies the transcriptional modification pattern on c-Myc target genes, such as LDHA, consequently reprogram glycolytic metabolism for CRC proliferation. Clinically, GLCC1 is associated with tumorigenesis, tumor size and predicts poor prognosis. Thus, GLCC1 is mechanistically, functionally, and clinically oncogenic in colorectal cancer. Targeting GLCC1 and its pathway may be meaningful for treating patients with colorectal cancer.

The long noncoding RNA CTA-941F9.9 is frequently downregulated and may serve as a biomarker for carcinogenesis in colorectal cancer

BACKGROUND

Long noncoding RNAs (lncRNAs) participate in the carcinogenesis of many different cancers. This study aimed to detect expression of lncRNA CTA-941F9.9 in colorectal cancer tissues compared with matched nontumorous adjacent tissues (NATs). Moreover, we investigated whether this molecule is able to influence carcinogenesis in colorectal cancer (CRC).

METHODS

Colorectal cancer tissues and NATs from two cohorts of patients were examined. Quantitative PCR was performed to quantify levels of CTA-941F9.9 expression in these samples. The association between CTA-941F9.9 expression and clinicopathological features, including receiver operating characteristic (ROC) curves, was also analyzed to evaluate the diagnostic value of CTA-941F9.9 in CRC. Potential effects of lncRNA CTA-941F9.9 on CRC cells were assessed via autophagy, transwell assay, CCK8 assays, and flow cytometry.

RESULTS

Our experimental results showed lncRNA CTA-941F9.9 to be significantly downregulated in CRC tissues in both cohorts, with areas under the ROC curve (AUC) of 0.802 and 0.876. However, no significant correlations between CTA-941F9.9 expression levels and clinicopathological characteristics or patient outcomes were observed. We also found that CTA-941F9.9 promotes autophagy in CRC cell lines but no significant function of CTA-941F9.9 in regulating cancer cell proliferation or migration.

CONCLUSIONS

LncRNA CTA-941F9.9 is frequently downregulated in CRC compared with NATs and might play an important role in CRC carcinogenesis.

Relationship of telomere length in colorectal cancer patients with cancer phenotype and patient prognosis

BACKGROUND

Telomeres, repetitive DNA capping ends of eukaryotic chromosomes, are important in the maintenance of genomic integrity. Perturbed telomeres are common features of many human malignancies, including colorectal cancer.

METHODS

Telomere length (TL), measured by a Monochrome Multiplex Real-Time qPCR, was investigated in tumour tissues, adjacent mucosa, and blood from patients with colorectal cancer with different clinicopathological features and its impact on patient survival. TL was also measured in a limited number of liver metastases, non-cancerous liver tissues or corresponding tissues from the same patients.

RESULTS

TL in tumour tissues was shorter than in the adjacent mucosa (P < 0.0001). Shorter TL was observed in tumours with lower stage than in those with advanced stages (P = 0.001). TL was shorter in tumours at the proximal than at the distal sites of the colon (P < 0.0001). Shorter TL was also associated with microsatellite instability (P = 0.001) and mucinous tumour histology (P < 0.0001). Patients with a smaller TL ratio between tumour tissues and the adjacent mucosa were associated with increased overall survival (P = 0.022). Metastasised tumours had shorter telomeres than the adjacent non-cancerous liver tissues (P = 0.0005).

CONCLUSIONS

Overall, the results demonstrate differences in TL between tumours and the adjacent mucosa, between tumours located at different sites and association with patient survival.

Genetic Aberration Analysis in Thai Colorectal Adenoma and Early-Stage Adenocarcinoma Patients by Whole-Exome Sequencing

Colorectal adenomas are precursor lesions of colorectal adenocarcinoma. The transition from adenoma to carcinoma in patients with colorectal cancer (CRC) has been associated with an accumulation of genetic aberrations. However, criteria that can screen adenoma progression to adenocarcinoma are still lacking. This present study is the first attempt to identify genetic aberrations, such as the somatic mutations, copy number variations (CNVs), and high-frequency mutated genes, found in Thai patients. In this study, we identified the genomic abnormality of two sample groups. In the first group, five cases matched normal-colorectal adenoma-colorectal adenocarcinoma. In the second group, six cases matched normal-colorectal adenomas. For both groups, whole-exome sequencing was performed. We compared the genetic aberration of the two sample groups. In both normal tissues compared with colorectal adenoma and colorectal adenocarcinoma analyses, somatic mutations were observed in the tumor suppressor gene APC (Adenomatous polyposis coli) in eight out of ten patients. In the group of normal tissue comparison with colorectal adenoma tissue, somatic mutations were also detected in Catenin Beta 1 (CTNNB1), Family With Sequence Similarity 123B (FAM123B), F-Box And WD Repeat Domain Containing 7 (FBXW7), Sex-Determining Region Y-Box 9 (SOX9), Low-Density Lipoprotein Receptor-Related Protein 5 (LRP5), Frizzled Class Receptor 10 (FZD10), and AT-Rich Interaction Domain 1A (ARID1A) genes, which are involved in the Wingless-related integration site (Wnt) signaling pathway. In the normal tissue comparison with colorectal adenocarcinoma tissue, Kirsten retrovirus-associated DNA sequences (KRAS), Tumor Protein 53 (TP53), and Ataxia-Telangiectasia Mutated (ATM) genes are found in the receptor tyrosine kinase-RAS (RTK-RAS) signaling pathway and p53 signaling pathway, respectively. These results suggest that APC and TP53 may act as a potential screening marker for colorectal adenoma and early-stage CRC. This preliminary study may help identify patients with adenoma and early-stage CRC and may aid in establishing prevention and surveillance strategies to reduce the incidence of CRC.

NOTCH Signaling via WNT Regulates the Proliferation of Alternative, CCR2-Independent Tumor-Associated Macrophages in Hepatocellular Carcinoma

Tumor-associated macrophages (TAM) play pivotal roles in tumor progression and metastasis, but the contribution and regulation of different macrophage populations remain unclear. Here we show that Notch signaling plays distinct roles in regulating different TAM subsets in hepatocellular carcinoma (HCC). Myeloid-specific NOTCH blockade by conditional disruption of recombination signal binding protein Jκ (RBPj cKO) significantly delayed the growth of subcutaneously inoculated Lewis lung carcinoma (LLC), but accelerated orthotopically inoculated hepatic Hepa1-6 tumors in mice. In contrast to subcutaneous LLC, RBPj cKO significantly increased the number of TAMs in hepatic Hepa1-6 tumors despite impeded differentiation of monocyte-derived TAMs (moTAM). The dominating TAMs in orthotopic HCC manifested properties of Kupffer cells (KC) and hence are tentatively named KC-like TAMs (kclTAM). The increased proliferation of RBPj cKO kclTAMs was maintained even in Ccr2 ^-/- mice, in which moTAMs were genetically blocked. NOTCH signaling blockade accelerated proliferation of kclTAMs via enhanced β-catenin-dependent WNT signaling, which also downregulated IL12 and upregulated IL10 expression by kclTAMs likely through c-MYC. In addition, myeloid-specific RBPj cKO facilitated hepatic metastasis of colorectal cancer but suppressed lung metastasis in mice, suggesting that the phenotype of RBPj cKO in promoting tumor growth was liver-specific. In patient-derived HCC biopsies, NOTCH signaling negatively correlated with WNT activation in CD68⁺ macrophages, which positively correlated with advanced HCC stages. Therefore, NOTCH blockade impedes the differentiation of moTAMs, but upregulates Wnt/β-catenin signaling to promote the proliferation and protumor cytokine production of kclTAMs, facilitating HCC progression and hepatic metastasis of colorectal cancer. SIGNIFICANCE: These findings highlight the role of NOTCH and WNT signaling in regulating TAMs in hepatocellular carcinoma.

Competitive Endogenous RNA (ceRNA) Regulation Network of lncRNA-miRNA-mRNA in Colorectal Carcinogenesis

BACKGROUND

Competitive endogenous RNA (ceRNA) regulation suggested complex network of all transcript RNAs including long noncoding RNAs (lncRNAs), which can act as natural miRNA sponges to inhibit miRNA functions and modulate mRNA expression. Until now, the specific ceRNA regulatory mechanism of lncRNA-miRNA-mRNA in colorectal cancer (CRC) still remains unclear.

MATERIALS AND METHODS

RNA sequencing data of 478 colon adenocarcinoma cases and 41 controls as well as 166 rectum adenocarcinoma cases and 10 controls were obtained from The Cancer Genome Atlas (TCGA) to investigate the significant changes of lncRNAs, miRNAs and mRNAs in colorectal carcinogenesis. The target lncRNAs and mRNAs of miRNAs were predicted by miRWalk. Functional and enrichment analyses were conducted by DAVID database. The lncRNA-miRNA-mRNA interaction network was constructed using Cytoscape.

RESULTS

We constructed ceRNA regulatory networks including 22 up-regulated lncRNAs, 12 down-regulated miRNAs and 122 up-regulated mRNAs, as well as 8 down-regulated lncRNAs, 43 up-regulated miRNAs and 139 down-regulated mRNAs. The GO enrichment showed that up-regulated genes mainly enriched in biological process including organic anion transport, collagen catabolic process, wound healing, Wnt receptor signalling and in pathways of tyrosine metabolism, taurine and hypotaurine metabolism, melanogenesis and phenylalanine metabolism. For down-regulated genes, significant enrichment was found in biological process of metal ion homeostasis, transmission of nerve impulse, cell-cell signalling, transmembrane transport and in pathways of ABC transporters, neuroactive ligand-receptor interaction, retinol metabolism, nitrogen metabolism and steroid hormone biosynthesis.

CONCLUSION

We identified significantly altered lncRNAs, miRNAs and mRNAs in colorectal carcinogenesis, which might serve as potential biomarkers for tumorigenesis of CRC. In addition, the ceRNA regulatory network of lncRNA-miRNA-mRNA was constructed, which would elucidate novel molecular mechanisms involved in initiation and progression of CRC, thus providing promising clues for clinical diagnosis and therapy.

NUP153 overexpression suppresses the proliferation of colorectal cancer by negatively regulating Wnt/β-catenin signaling pathway and predicts good prognosis

BACKGROUND

Nucleoporin NUP153 (NUP153) is well known to be involved in the regulating of nuclear transport. Although NUP153 is associated with several cancers, its role in colorectal cancer (CRC) and the underlying mechanism are still unknown.

OBJECTIVE

The aim of this study was to access the effect of NUP153 on the prognosis of patients with CRC, and cancer cell proliferation.

METHODS

The expression levels of NUP153 in CRC tissues and matched normal colon tissues were examined by real-time quantitative PCR and immunohistochemistry. Then the association between NUP153 levels with clinical variables as well as survival time was investigated. Moreover, overexpression of NUP153 in HCT116 cells was established to study its influence on cell proliferation in vitro, and a xenograft model was performed to explore this effect in vivo.

RESULTS

We found that NUP153 was highly expressed in adjacent normal tissues than in cancer tissues, and elevated NUP153 expression was negatively associated with pathological grade (P= 0.015), T stage (P= 0.048) and distant metastasis (P= 0.006). Kaplan-Meier analysis revealed that patients with higher NUP153 expression had a longer overall survival (OS) (P= 0.01) and recurrence free disease (RFS) (P= 0.001). Logistic regression analysis further identified NUP153 as an independent prognostic safe factor for OS and recurrence. Moreover, NUP153 overexpression suppressed CRC cells proliferation and inhibited tumor growth in a xenograft model. Its mechanistic investigations showed that NUP153 overexpression inhibited β-catenin transcriptional activity and down-regulated the mRNA expression levels of Wnt downstream proteins-Axin2, cyclinD1, c-myc and lef-1.

CONCLUSIONS

NUP153 might be a promising prognostic factor, a potential tumor suppressor and therapeutic target in human CRC through an interaction with the Wnt/β-catenin signaling pathway.

Epigenetic Alternations of MicroRNAs and DNA Methylation Contribute to Liver Metastasis of Colorectal Cancer

BACKGROUND

Liver metastasis is a major cause of mortality in colorectal cancer (CRC). Epigenetic alternations could serve as biomarkers for cancer diagnosis and prognosis. In this study, we analyzed microarray data in order to identify core genes and pathways which contribute to liver metastasis in CRC under epigenetic regulations.

MATERIALS AND METHODS

Data of miRNAs (GSE35834, GSE81582), DNA methylation (GSE90709, GSE77955), and mRNA microarrays (GSE68468, GSE81558) were downloaded from GEO database. Differentially expressed genes (DEGs), differentially expressed miRNAs (DEMs), and differentially methylated genes (DMGs) were obtained by GEO2R. The target genes of DEMs were predicted by miRWalk. Functional and enrichment analyses were conducted by DAVID database. Protein-protein interaction (PPI) network was constructed in STRING and visualized using Cytoscape.

RESULTS

In liver metastasis, miR-143-3p, miR-10b-5p, miR-21-5p, and miR-518f-5p were down-regulated, while miR-122-5p, miR-885-5p, miR-210-3p, miR-130b-5p, miR-1275, miR-139-5p, miR-139-3p, and miR-1290 were up-regulated compared with primary CRC. DEGs targeted by altered miRNAs were enriched in pathways including complement, PPAR signaling, ECM-receptor interaction, spliceosome, and focal adhesion. In addition, aberrant DNA methylation-regulated genes showed enrichment in pathways of amino acid metabolism, calcium signaling, TGF-beta signaling, cell cycle, spliceosome, and Wnt signaling.

CONCLUSION

Our study identified a series of differentially expressed genes which are associated with epigenetic alternations of miRNAs and DNA methylation in colorectal liver metastasis. Up-regulated genes of SLC10A1, MAPT, SHANK2, PTH1R, and C2, as well as down-regulated genes of CAB39, CFLAR, CTSC, THBS1, and TRAPPC3 were associated with both miRNA and DNA methylation, which might become promising biomarker of colorectal liver metastasis in future.

Linking Nucleoporins, Mitosis, and Colon Cancer

Suppression of a nuclear pore protein Nup358/RanBP2 is linked to mitotic cell death, but the clinical relevance of this link is unknown. In a recent issue of Cell, Vecchione et al. (2016) show that in approximately 10% of BRAF-like colorectal cancer (CC) patients, Nup358/RanBP2 is critical for survival. Treatment with vinorelbine, a microtubule-depolymerizing drug that inhibits mitosis, might be a potential treatment for these CCs.

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.

LncRNAs with miRNAs in regulation of gastric, liver, and colorectal cancers: updates in recent years

Long noncoding RNA (lncRNA) is a kind of RNAi molecule composed of hundreds to thousands of nucleotides. There are several major types of functional lncRNAs which participate in some important cellular pathways. LncRNA-RNA interaction controls mRNA translation and degradation or serves as a microRNA (miRNA) sponge for silencing. LncRNA-protein interaction regulates protein activity in transcriptional activation and silencing. LncRNA guide, decoy, and scaffold regulate transcription regulators of enhancer or repressor region of the coding genes for alteration of expression. LncRNA plays a role in cellular responses including the following activities: regulation of chromatin structural modification and gene expression for epigenetic and cell function control, promotion of hematopoiesis and maturation of immunity, cell programming in stem cell and somatic cell development, modulation of pathogen infection, switching glycolysis and lipid metabolism, and initiation of autoimmune diseases. LncRNA, together with miRNA, are considered the critical elements in cancer development. It has been demonstrated that tumorigenesis could be driven by homeostatic imbalance of lncRNA/miRNA/cancer regulatory factors resulting in biochemical and physiological alterations inside the cells. Cancer-driven lncRNAs with other cellular RNAs, epigenetic modulators, or protein effectors may change gene expression level and affect the viability, immortality, and motility of the cells that facilitate cancer cell cycle rearrangement, angiogenesis, proliferation, and metastasis. Molecular medicine will be the future trend for development. LncRNA/miRNA could be one of the potential candidates in this category. Continuous studies in lncRNA functional discrepancy between cancer cells and normal cells and regional and rational genetic differences of lncRNA profiles are critical for clinical research which is beneficial for clinical practice.

Cancer epigenetics in solid organ tumours: A primer for surgical oncologists

Cancer is initiated through both genetic and epigenetic alterations. The end-effect of such changes to the DNA machinery is a set of uncontrolled mechanisms of cell division, invasion and, eventually, metastasis. Epigenetic changes are now increasingly appreciated as an essential driver to the cancer phenotype. The epigenetic regulation of cancer is complex and not yet fully understood, but application of epigenetics to clinical practice and in cancer research has the potential to improve cancer care. Epigenetics changes do not cause changes in the DNA base-pairs (and, hence, does not alter the genetic code per se) but rather occur through methylation of DNA, by histone modifications, and, through changes to chromatin structure to alter genetic expression. Epigenetic regulators are characterized as writers, readers or erasers by their mechanisms of action. The human epigenome is influenced from cradle to grave, with internal and external life-time exposure influencing the epigenetic marks that may act as modifiers or drivers of carcinogenesis. Preventive and public health strategies may follow from better understanding of the life-time influence of the epigenome. Epigenetics may be used to define risk, to investigate mechanisms of carcinogenesis, to identify biomarkers, and to identify novel therapeutic options. Epigenetic alterations are found across many solid cancers and are increasingly making clinical impact to cancer management. Novel epigenetic drugs may be used for a more tailored and specific response to treatment of cancers. We present a primer on epigenetics for surgical oncologists with examples from colorectal cancer, breast cancer, pancreatic cancer and hepatocellular carcinoma.

Role of diet and gut microbiota on colorectal cancer immunomodulation

Colorectal cancer (CRC) is one of the most commonly diagnosed cancers, and it is characterized by genetic and epigenetic alterations, as well as by inflammatory cell infiltration among malignant and stromal cells. However, this dynamic infiltration can be influenced by the microenvironment to promote tumor proliferation, survival and metastasis or cancer inhibition. In particular, the cancer microenvironment metabolites can regulate the inflammatory cells to induce a chronic inflammatory response that can be a predisposing condition for CRC retention. In addition, some nutritional components might contribute to a chronic inflammatory condition by regulating various immune and inflammatory pathways. Besides that, diet strongly modulates the gut microbiota composition, which has a key role in maintaining gut homeostasis and is associated with the modulation of host inflammatory and immune responses. Therefore, diet has a fundamental role in CRC initiation, progression and prevention. In particular, functional foods such as probiotics, prebiotics and symbiotics can have a potentially positive effect on health beyond basic nutrition and have anti-inflammatory effects. In this review, we discuss the influence of diet on gut microbiota composition, focusing on its role on gut inflammation and immunity. Finally, we describe the potential benefits of using probiotics and prebiotics to modulate the host inflammatory response, as well as its application in CRC prevention and treatment.

Prevalence and prognostic relevance of BrafV600E mutation in colorectal carcinomas from Kashmir (North India) valley

Molecular studies have implicated mutant B-type Raf kinase (BRAFMut) of MAP-kinase signalling pathway in the pathogenesis of several cancers including colorectal cancer. Recently, the prognostic and therapeutic relevance of the most frequent BRAFV600E mutation also has been highlighted in colorectal carcinomas (CRC). Thus, the aim of this study was to investigate the prevalence of BRAFV600E mutation and to determine the correlation between this mutation and indicators of poor prognosis and outcome in patients with CRCs from Kashmir, North India. Here, we developed a highly sensitive technique, mutation allele-specific multiplex PCR (MASMP), for detection of BRAFV600E/BRAFc.1799T>A mutation, the results of which were confirmed by sequencing the product and compared to direct DNA sequencing. In total, BRAFV600E mutation status was analyzed in 57 colorectal tumour samples and an equal number of adjacent normal tissues. A high frequency of BRAFV600E mutation 21% (12/57) was identified in tumour tissues by MASMP compared to only 5.2% by direct DNA sequencing. Statistical analysis indicated that compared to BRAF-negative colorectal tumours, patients with BRAFV600E colorectal tumours were more likely to be >50 years old (61%) (P < 0.03). These tumours were more likely to be of clinical tumour stages III and IV (63%) (P < 0.04) with lymph node metastasis (52%) (P < 0.02) and characterised by a high-grade histology (63%) (P < 0.04). Colorectal patients harbouring BRAFV600E mutation experience more relapse/recurrence (52%) (P < 0.02). We, therefore, conclude that BRAFV600E mutation can be used as an indicator of poor prognosis to predict the outcome for CRC patients from Kashmir. MASMP proved to be a simple, sensitive and reliable technique for screening patients for BRAFV600E mutation. Testing for this mutation may be useful for selecting initial therapy mode and for follow-up monitoring in CRC patients.

Early diagnosis of colorectal cancer via plasma proteomic analysis of CRC and advanced adenomatous polyp

AIM

This paper aimed to identify new candidate biomarkers in blood for early diagnosis of CRC.

BACKGROUND

Colorectal cancer (CRC) is the third most widespread malignancies increasing globally. The high mortality rate associated with colorectal cancer is due to the delayed diagnosis in an advanced stage while the metastasis has occurred. For better clinical management and subsequently to reduce mortality of CRC, early detection biomarkers are in high demand.

METHODS

A 2D-PAGE separation of proteins was performed followed by tandem mass Spectrometry (MALDI-TOF-TOF) to discover potential plasma protein markers for CRC and AA (advanced adenomas). Furthermore, western blot method was used to confirm a part of the results in colorectal tissue samples.

RESULTS

The significantly altered proteins including HPR, HP, ALB, KRT1, APOA1, FGB, IGJ and C4A were down-regulated in polyp relative to normal, and CRC compare to polyp surprisingly, and inversely, ORM2 was up-regulated with the fold change ≥ 2 and p-value ≤ 0.05. We also surveyed APOA1, FGB, and C4A for further confirmation of their expression changes by western blotting. All three of them showed a decreasing trend from normal toward CRC tissue samples as it mentioned before, but just changes of FGB and C4A were significant.

CONCLUSION

The results demonstrated that plasma proteins can be less invasive markers for the detection of CRC. FGB and C4A can be considered as plasma potential biomarkers to early diagnosis of CRC patients and understanding the underlying procedures in tumorigenesis. Undoubtedly, the additional study must be conducted on large scale cohorts to verify the results.

Differences Regarding the Molecular Features and Gut Microbiota Between Right and Left Colon Cancer

For many years, developmental and physiological differences have been known to exist between anatomic segments of the colorectum. Because of different outcomes, prognoses, and clinical responses to chemotherapy, the distinction between right colon cancer (RCC) and left colon cancer (LCC) has gained attention. Furthermore, variations in the molecular features and gut microbiota between right and LCCs have recently been a hot research topic. CpG island methylator phenotype-high, microsatellite instability-high colorectal cancers are more likely to occur on the right side whereas tumors with chromosomal instability have been detected in approximately 75% of LCC patients and 30% of RCC patients. The mutation rates of oncogenes and tumor suppressor genes also differ between RCC and LCC patients. Biofilm is more abundant in RCC patients than LLC patients, as are Prevotella, Selenomonas, and Peptostreptococcus. Conversely, Fusobacterium, Escherichia/Shigella, and Leptotrichia are more abundant in LCC patients compared to RCC patients. Distinctive characteristics are apparent in terms of molecular features and gut microbiota between right and LCC. However, how or to what extent these differences influence diverging oncologic outcomes remains unclear. Further clinical and translational studies are needed to elucidate the causative relationship between primary tumor location and prognosis.

MORC2 promotes development of an aggressive colorectal cancer phenotype through inhibition of NDRG1

MORC2 (microrchidia family CW‐type zinc finger 2) is a newly identified chromatin remodeling protein that functions in diverse biological processes including gene transcription. NDRG1 is a metastasis suppressor and a prognostic biomarker for colorectal cancer (CRC). However, the relationship between MORC2 and NDRG1 transcriptional regulation and the roles of MORC2 in CRC remain elusive. Here, we showed that MORC2 downregulated NDRG1 mRNA, protein levels, and promoter activity in CRC cells. We also found that MORC2 bound to the −446 to −213 bp region of the NDRG1 promoter. Mechanistically, histone deacetylase sirtuin 1 (SIRT1) was involved in NDRG1 transcriptional regulation. MORC2 was able to interact with SIRT1 and inhibit NDRG1 promoter activity cumulatively with SIRT1. MORC2 overexpression led to a decrease of H3Ac and H4Ac of the NDRG1 promoter. Importantly, we showed that NDRG1 was essential in MORC2‐mediated promotion of CRC cell migration and invasion in vitro, as well as lung metastasis of CRC cells in vivo. Moreover, MORC2 expression correlated negatively with NDRG1 expression in CRC patients. High expression of MORC2 was significantly associated with lymph node metastasis (P = 0.019) and poor pTNM stage (P = 0.02) and the expression of MORC2 correlated with poor prognosis in colon cancer patients. Our findings thus contribute to the knowledge of the regulatory mechanism of MORC2 in downregulating NDRG1, and suggest MORC2 as a potential therapeutic target for CRC.

Alteration of tumor suppressor BMP5 in sporadic colorectal cancer: a genomic and transcriptomic profiling based study

Background

Although the genetic spectrum of human colorectal cancer (CRC) is mainly characterized by APC, KRAS and TP53 mutations, driver genes in tumor initiation have not been conclusively demonstrated. In this study, we aimed to identify novel markers for CRC.

Methods

We performed exome analysis of sporadic colorectal cancer (sCRC) coding regions to screen loss of function (LoF) mutation genes, and carried out systems-level approaches to confirm top rank gene in this study.

Results

We identified loss of BMP5 is an early event in CRC. Deep sequencing identified BMP5 was mutated in 7.7% (8/104) of sCRC samples, with 37.5% truncating mutation frequency. Notably, BMP5 negative expression and its prognostic value is uniquely significant in sCRC but not in other tumor types. Furthermore, BMP5 expression was positively correlated with E-cadherin in CRC patients and its dysregulation play a vital role in epithelial-mesenchymal transition (EMT), thus triggering tumor initiation and development. RNA sequencing identified, independent of BMP/Smads pathway, BMP5 signaled though Jak-Stat pathways to inhibit the activation of oncogene EPSTI1.

Conclusions

Our result support a novel concept that the importance of BMP5 in sCRC. The tumor suppressor role of BMP5 highlights its crucial role in CRC initiation and development.

Electronic supplementary material

The online version of this article (10.1186/s12943-018-0925-7) contains supplementary material, which is available to authorized users.

Hypermethylated WNT10A and its clinical significance in colorectal cancer

Colorectal cancer (CRC) is a heterogeneous disease in which unique subtypes are characterized by distinct genetic and epigenetic alterations. DNA methylation, a well-documented epigenetic modification, is a promising biomarker for the diagnosis and prognosis of cancers, including CRC. WNT10A is a member of the Wnt family. It belongs to the Wnt signaling pathway and is involved in CRC. However, studies regarding the methylation and expression of WNT10A in CRC are limited. In the current study, we analyzed the methylation status of WNT10A in 146 patients with CRC and normal controls. These samples were classified into two groups. The first group was an initial discovery set (i.e., fresh tissue samples from 40 patients with CRC and adjacent normal control samples). The second group was an independent validation set (i.e., formalin-fixed and paraffin-embeded [FFPE] samples from 106 patients with CRC and cutting edge tissues). The results showed a higher level of WNT10A hypermethylation of in CRC samples than in controls (Fresh tissue cohort: P = 2.8E-5; FFPE cohort: P = 3.6E-4).This finding was verified by WNT10A methylation data from The Cancer Genome Atlas portal (TCGA) (P = 1.9E-83). Subgroup analysis of clinical characteristics showed a higher WNT10A methylation level in elder patients (aged > 60 y) (P = 0.037) and, patients with distant metastasis (P = 0.033), rectal cancer (P = 0.03), and mucinous adenocarcinoma (P = 0.02). Furthermore, TCGA RNAseq data demonstrated lower WNT10A expression in patients with CRC than in controls (P = 4.0E-3) and showed a negative correlation between expression and methylation (r = -0.37, P = 5.7E-13). Moreover, the efficiency of WNT10A methylation for CRC diagnosis was analyzed in both cohorts of the present study and the TCGA cohorts, which indicated the potential use of WNT10A methylation as a tool for diagnosis of CRC.

Gut Microbiota, Fusobacteria, and Colorectal Cancer

The gut microbiota has emerged as an environmental contributor to colorectal cancer (CRC) in both animal models and human studies. It is now generally accepted that bacteria are ubiquitous colonizers of all exposed human body surfaces, including the entire alimentary tract (5). Recently, the concept that a normal bacterial microbiota is essential for the development of inflammation-induced carcinoma has emerged from studies of well-known colonic bacterial microbiota. This review explores the evidence for a role of fusobacteria, an anaerobic gram-negative bacterium that has repeatedly been detected at colorectal tumor sites in higher abundance than surrounding histologically normal tissue. Mechanistic studies provide insight on the interplay between fusobacteria, other gut microbiota, barrier functions, and host responses. Studies have shown that fusobacteria activate host inflammatory responses designed to protect against pathogens that promote tumor growth. We discuss how future research identifying the pathophysiology underlying fusobacteria colon colonization during colorectal cancer may lead to new therapeutic targets for cancer. Furthermore, disease-protective strategies suppressing tumor development by targeting the local tumor environment via bacteria represent another exciting avenue for researchers and are highlighted in this review.

Overexpression of NELFCD promotes colorectal cancer cells proliferation, migration, and invasion

PURPOSE

Negative elongation factor complex member C/D (NELFCD), mapped to chromosome 20q13.32, has been found to be significantly overexpressed in colorectal cancer (CRC) by our previous research. However, whether its overexpression contributes to CRC development is unknown. We aimed to explore the biological and clinical roles of NELFCD in CRC.

MATERIALS AND METHODS

The expression of NELFCD was detected by qRT-PCR and Western blot. The biological function of NELFCD on CRC cell proliferation, migration, invasion, and apoptosis was detected by cell counting kit-8, plate colony formation assay, transwell migration and invasion assays, and flow cytometry in vitro and by murine xenograft tumor growth in vivo. Moreover, we evaluated the correction between its expression level and clinicopathologic parameters.

RESULTS

We found NELFCD was overexpressed in 50 pairs of CRC tissues in comparison to the adjacent nontumor tissues (P<0.05). Knockdown of NELFCD significantly impaired cell proliferation, migration and invasion abilities, facilitated cell apoptosis in vitro, and inhibited tumorigenesis of CRC cells in vivo. NELFCD levels were remarkably connected with tumor location in CRC patients.

CONCLUSION

NELFCD is overexpressed and plays an oncogenic role in CRC. Targeting NELFCD may provide a potential therapeutic option for NELFCD-amplified tumors.

Long noncoding RNA ENST00000455974 plays an oncogenic role through up-regulating JAG2 in human DNA mismatch repair-proficient colon cancer

DNA mismatch repair-proficient colon cancer is the most common type of colon cancer, but its initiation and progression are still unknown. Our previous study has revealed that a long noncoding RNA (lncRNA) ENST00000455974 was significantly associated with TNM stage and distant metastasis in patients with DNA mismatch repair-proficient (pMMR) colon cancer (CC). Here, firstly, we observed that ENST00000455974 was gradual increased across colon normal-adenoma-carcinoma-metastasis sequence by quantitative real-time PCR. Secondly, ENST00000455974 showed a better sensitivity and specificity than CEA and CA19-9 in the diagnosis of pMMR CC by drawing the receiver operating characteristic (ROC) curve. Thirdly, a higher level of ENST00000455974 was associated with a poorer patient survival. Furthermore, Knockdown of ENST00000455974 led to reduced proliferation and migration of colon cancer cells. Mechanistically, ENST00000455974 was mainly located in the nucleus of colon cancer cells and it promoted the growth and metastasis of pMMR CC cells through up-regulating JAG2.

Clinical and Genetic Factors to Inform Reducing Colorectal Cancer Disparitites in African Americans

Colorectal cancer (CRC) is the third most prevalent and second deadliest cancer in the U.S. with 140,250 cases and 50,630 deaths for 2018. Prevention of CRC through screening is effective. Among categorized races in the U.S., African Americans (AAs) show the highest incidence and death rates per 100,000 when compared to Non-Hispanic Whites (NHWs), American Indian/Alaskan Natives, Hispanics, and Asian/Pacific Islanders, with an overall AA:NHW ratio of 1.13 for incidence and 1.32 for mortality (2010-2014, seer.cancer.gov). The disparity for CRC incidence and worsened mortality among AAs is likely multifactorial and includes environmental (e.g., diet and intestinal microbiome composition, prevalence of obesity, use of aspirin, alcohol, and tobacco use), societal (e.g., socioeconomic status, insurance and access to care, and screening uptake and behaviors), and genetic (e.g., somatic driver mutations, race-specific variants in genes, and inflammation and immunological factors). Some of these parameters have been investigated, and interventions that address specific parameters have proven to be effective in lowering the disparity. For instance, there is strong evidence raising screening utilization rates among AAs to that of NHWs reduces CRC incidence to that of NHWs. Reducing the age to commence CRC screening in AA patients may further address incidence disparity, due to the earlier age onset of CRC. Identified genetic and epigenetic changes such as reduced MLH1 hypermethylation frequency, presence of inflammation-associated microsatellite alterations, and unique driver gene mutations (FLCN and EPHA6) among AA CRCs will afford more precise approaches toward CRC care, including the use of 5-fluorouracil and anti-PD-1.

The relationship between chemokines CCL2, CCL3, and CCL4 with the tumor microenvironment and tumor-associated macrophage markers in colorectal cancer

A complex network of chemokines can influence cancer progression with the recruitment and activation of hematopoietic cells, including macrophages to the supporting tumor stroma promoting carcinogenesis and metastasis. The aim of this study was to investigate the relation between tissue and plasma chemokine levels involved in macrophage recruitment with tumor-associated macrophage profile markers and clinicopathological features such as tumor-node-metastases stage, desmoplasia, tumor necrosis factor-α, and vascular endothelial growth factor plasma content. Plasma and tumor/healthy mucosa were obtained from Chilean patients undergoing colon cancer surgery. Chemokines were evaluated from tissue lysates (CCL2, CCL3, CCL4, CCL5, and CX3CL1) by Luminex. Statistical analysis was performed using Wilcoxon match-paired test ( p  < 0.05). Macrophage markers (CD68, CD163, and iNOS) were evaluated by immunohistochemistry samples derived from colorectal cancer patients. Correlation analysis between chemokines and macrophage markers and clinicopathological features were performed using Spearman's test. Plasmatic levels of chemokines and inflammatory mediators' vascular endothelial growth factor and tumor necrosis factor-α were evaluated by Luminex. Tumor levels of CCL2 (mean ± standard deviation = 530.1 ± 613.9 pg/mg), CCL3 (102.7 ± 106.0 pg/mg), and CCL4 (64.98 ± 48.09 pg/mg) were higher than those found in healthy tissue (182.1 ± 116.5, 26.79 ± 22.40, and 27.06 ± 23.69 pg/mg, respectively p < 0.05). The tumor characterization allowed us to identify a positive correlation between CCL4 and the pro-tumor macrophages marker CD163 ( p  = 0.0443), and a negative correlation of iNOS with desmoplastic reaction ( p  = 0.0467). Moreover, we identified that tumors with immature desmoplasia have a higher CD163 density compared to those with a mature/intermediated stromal tissue ( p  = 0.0288). Plasmatic CCL4 has shown a positive correlation with inflammatory mediators (tumor necrosis factor-α and vascular endothelial growth factor) that have previously been associated with poor prognosis in patients. In conclusion High expression of CCL4 in colon cancer could induce the infiltration of tumor-associated macrophages and specifically a pro-tumor macrophage profile (CD163⁺ cells). Moreover, plasmatic chemokines could be considered inflammatory mediators associated to CRC progression as well as tumor necrosis factor-α and vascular endothelial growth factor. These data reinforce the idea of chemokines as potential therapeutic targets or biomarker in CRC.

A 15-lncRNA signature predicts survival and functions as a ceRNA in patients with colorectal cancer

Purpose

Colorectal cancer (CRC) is one of the most common malignant tumors worldwide. This study aimed to explore the prognostic value of lncRNAs in CRC.

Material and methods

We performed gene expression profiling to identify differentially expressed lncRNAs between 51 normal and 646 tumor tissues from The Cancer Genome Atlas database. Cox regression and robust likelihood-based survival models were used to find prognosis-related lncRNAs. A lncRNA signature was developed to predict the overall survival of patients with CRC. In addition, a receiver operating characteristic curve analysis was performed to identify the optimal cutoff with the best Youden index to divide patients into different groups based on risk level.

Results

Eighty survival-related lncRNAs were identified and a 15-lncRNA signature was developed on the basis of a risk score to comprehensively predict the overall survival of patients with CRC. The prognostic value of the 15-lncRNA risk score was validated using the internal testing set and total set. The risk indicator was shown to be an independent prognostic factor (hazard ratio =2.92; 95% CI: 1.73–4.94; P<0.001). Notably, all 15 lncRNAs (AC024581.1, FOXD3-AS1, AC012531.1, AC003101.2, LINC01219, AC083967.1, AL590483.1, AC105118.1, AC010789.1, AC067930.5, AC105219.2, LINC01354, LINC02474, LINC02257, and AC079612.1) were newly found to correlate with the prognosis of patients with CRC. Furthermore, the function of 15 lncRNAs was explored through the ceRNA network. These lncRNAs regulated coding genes that were involved in many key cancer pathways.

Conclusion

A 15-lncRNA expression signature was discovered as a prognostic indicator for patients with CRC, which may act as competing endogenous RNA (ceRNAs) to play a crucial role in the modulation of cancer-related pathways. These findings may allow a better understanding of the prognostic value of lncRNAs.

A genome-wide analysis of colorectal cancer in a child with Noonan syndrome

Noonan syndrome (NS) is a developmental syndrome caused by germline mutations in the Ras signaling pathway. No association has been shown between NS and pediatric colorectal cancer (CRC). We report the case of CRC in a pediatric patient with NS. The patient underwent whole genome sequencing. A germline SOS1 mutation c.1310T>C (p. Ile437Thr) confirmed NS diagnosis. No known hereditary cancer syndromes were identified. Tumor analysis revealed two mutations: a TP53 missense mutation c.481G>A (p. Ala161Tyr) and NCOR1 nonsense mutation c.6052C>T (p. Arg2018*). This report highlights the complexity of Ras signaling and the interplay between developmental syndromes and cancer.

Endothelial PAS domain protein 1 gene hypomethylation is associated with colorectal cancer in Han Chinese

Endothelial PAS domain-containing protein 1 (EPAS1) serves a role in angiogenesis, which is important for the development of tumors, including colorectal cancer (CRC). The current study aimed to estimate whether EPAS1 methylation was associated with CRC. A two-stage association study of EPAS1 methylation and CRC was conducted. In the first phase, EPAS1 methylation was evaluated in the tumor and adjacent non-tumor tissue samples from 41 patients with sporadic CRC in Jiangsu province, China. The diagnostic value of methylation of EPAS1 for CRC in the second phase was evaluated in 79 patients with sporadic CRC and 22 normal individuals in Zhejiang province, China. The methylation assay was performed using a quantitative methylation-specific polymerase chain reaction (qMSP) method. The percentage of methylated reference (PMR) was used to quantify the methylation level. The first-stage results indicated that EPAS1 promoter methylation was significantly lower in CRC tumor tissues compared with 5-cm-para-tumor tissues (median PMR, 0.59 vs. 1.22%; P=0.027) and 10-cm-para-tumor tissues (median PMR, 0.59 vs. 1.89%; P=0.001). In addition, the second-stage results indicated that EPAS1 promoter methylation was significantly lower in tumor tissues compared with 5-cm-para-tumor tissues (median PMR, 1.91 vs. 6.25%; P=3×10⁻⁷) and normal intestinal tissues from healthy controls (median PMR, 1.91 vs. 28.4%; P=5×10⁻⁷). Receiver Operating Characteristic curve analysis of the second-stage data indicated that the highest area under the curve of EPAS1 hypomethylation was 0.851 between Zhejiang CRC tissues and Zhejiang normal intestinal tissues (sensitivity, 95.5%; specificity, 60.8%).

PIWI-interacting RNA-54265 is oncogenic and a potential therapeutic target in colorectal adenocarcinoma

Although PIWI-interacting RNAs (piRNAs) have recently been linked to human diseases, their roles and functions in malignancies remain unclear. This study aimed to investigate the significance of some piRNAs in colorectal cancer (CRC). Methods: We first analyzed the expression profile of piRNAs in CRC using the TCGA and GEO databases. The top 20 highly expressed piRNAs were selected and tested in our CRC tumor and non-tumor tissue samples. We then examined the relevance of the significantly differentially expressed piRNA to the CRC outcomes in 218 patients receiving postoperative chemotherapy and 317 patients receiving neoadjuvant chemotherapy. A series of biochemical and molecular biological assays were conducted to elucidate the functional mechanism of a piRNA of interest in CRC. Furthermore, experiments with mice xenografts were performed to evaluate the therapeutic effect of an inhibitor specific to the piRNA. Results: We found that among the examined 20 piRNAs, only piRNA-54265 was overexpressed in CRC compared with non-tumor tissues and higher levels in tumor or in serum were significantly associated with poor survival in patients. Functional assays demonstrated that piRNA-54265 binds PIWIL2 protein and this is necessary for the formation of PIWIL2/STAT3/phosphorylated-SRC (p-SRC) complex, which activates STAT3 signaling and promotes proliferation, metastasis and chemoresistance of CRC cells. Treatment with a piRNA-54265 inhibitor significantly suppressed the growth and metastasis of implanted tumors in mice. Conclusion: These results indicate that piRNA-54265 is an oncogenic RNA in CRC and thus might be a therapeutic target.

MiR-452 promotes an aggressive colorectal cancer phenotype by regulating a Wnt/β-catenin positive feedback loop

Background

Aberrant activation of Wnt/β-catenin signaling pathway is considered to be an important issue in progression and metastasis of various human cancers, especially in colorectal cancer (CRC). MiR-452 could activate of Wnt/β-catenin signaling. But the mechanism remains unclear.

Methods

The expression of miR-452 in CRC and normal tissues was detected by real-time quantitative PCR. The effect of miR-452 on CRC growth and invasion was conducted by functional experiments in vitro and in vivo. Bioinformatics and cell luciferase function studies verified the direct regulation of miR-452 on the 3’-UTR of the GSK3β, which leads to the activation of Wnt/β-catenin signaling.

Results

MiR-452 was upregulated in CRC compared with normal tissues and was correlated with clinical significance. The luciferase reporter system studies affirmed the direct regulation of miR-452 on the 3’-UTR of the GSK3β, which activate the Wnt/β-catenin signaling. The ectopic upregulation of miR-452 significantly inhibited the expression of GSK3β and enhanced CRC proliferation and invasion in vitro and in vivo. Meanwhile, knockdown of miR-452 significantly recovered the expression of GSK3β and attenuated Wnt/β-catenin-mediated cell metastasis and proliferation. More important, T-cell factor/lymphoid enhancer factor (TCF/LEF) family of transcription factors, which are crucial downstream molecules of the Wnt/β-catenin signaling pathway was verified as a valid transcription factor of miR-452’s promoter.

Conclusions

Our findings first demonstrate that miR-452-GSK3β-LEF1/TCF4 positive feedback loop induce CRC proliferation and migration.

Electronic supplementary material

The online version of this article (10.1186/s13046-018-0879-z) contains supplementary material, which is available to authorized users.

Elevated G-Protein Receptor 125 (GPR125) Expression Predicts Good Outcomes in Colorectal Cancer and Inhibits Wnt/β-Catenin Signaling Pathway

Background

G-protein receptor 125 (GPR125), as a transmembrane signal transducer, is involved in regulating cancer development. Although GPR125 is related with several cancers, its role in colorectal cancer (CRC) and the underlying mechanism are still unknown. Here, we investigated the clinical significance of GPR125 in CRC.

Material/Methods

We assessed the expression level of GPR125 in CRC tissues by analyzing 3 datasets in the Gene Expression Omnibus (GEO) database and in human samples. The correlation between GPR125 expression and clinicopathological features was further analyzed. Survival analysis was performed to assess the association between GPR125 expression and recurrence-free survival (RFS). Cox logistic regression analysis was used to analyze the role of GPR125 expression in overall survival (OS). Moreover, we activated the Wnt pathway in HCT116 cells to investigate their potential mechanism.

Results

Analysis of the GEO database showed that the expression of GPR125 was down-regulated in CRC tissues, consistent with our human samples experiments, and patients with higher GPR125 expression had a longer RFS. Also, we found that high GPR125 expression was associated with better tumor outcomes in clinical stage, metastasis, and KRAS status. Cox logistic regression analysis demonstrated that GPR125 was an independent prognostic factor for favorable outcome. Mechanistically, GPR125 overexpression inhibited the β-catenin transcriptional activity, and down-regulated the expression levels of the Wnt downstream proteins-Axin2, c-Myc, cylinD1, and lef-1.

Conclusions

GPR125 may be a potential prognosis-related anti-oncogene and its effects on inactivating Wnt/β-catenin signaling pathway might be a key link to inhibiting CRC formation.

Glycosyltransferase Gene Expression Identifies a Poor Prognostic Colorectal Cancer Subtype Associated with Mismatch Repair Deficiency and Incomplete Glycan Synthesis

Purpose: We aimed to discover glycosyltransferase gene (glycogene)-derived molecular subtypes of colorectal cancer associated with patient outcomes.Experimental Design: Transcriptomic and epigenomic datasets of nontumor, precancerous, cancerous tissues, and cell lines with somatic mutations, mismatch repair status, clinicopathologic and survival information were assembled (n = 4,223) and glycogene profiles were analyzed. IHC for a glycogene, GALNT6, was conducted in adenoma and carcinoma specimens (n = 403). The functional role and cell surface glycan profiles were further investigated by in vitro loss-of-function assays and lectin microarray analysis.Results: We initially developed and validated a 15-glycogene signature that can identify a poor-prognostic subtype, which closely related to deficient mismatch repair (dMMR) and GALNT6 downregulation. The association of decreased GALNT6 with dMMR was confirmed in multiple datasets of tumors and cell lines, and was further recapitulated by IHC, where approximately 15% tumors exhibited loss of GALNT6 protein. GALNT6 mRNA and protein was expressed in premalignant/preinvasive lesions but was subsequently downregulated in a subset of carcinomas, possibly through epigenetic silencing. Decreased GALNT6 was independently associated with poor prognosis in the IHC cohort and an additional microarray meta-cohort, by multivariate analyses, and its discriminative power of survival was particularly remarkable in stage III patients. GALNT6 silencing in SW480 cells promoted invasion, migration, chemoresistance, and increased cell surface expression of a cancer-associated truncated O-glycan, Tn-antigen.Conclusions: The 15-glycogene signature and the expression levels of GALNT6 mRNA and protein each serve as a novel prognostic biomarker, highlighting the role of dysregulated glycogenes in cancer-associated glycan synthesis and poor prognosis. Clin Cancer Res; 24(18); 4468-81. ©2018 AACR.

Dietary and the Risk of Sporadic Colorectal Cancer in China: A Case-control Study

BACKGROUND

High-fat diets have been considered a risk factor for sporadic colorectal cancer (CRC) in Western countries. However, data for this phenomenon are lacking in China. The purpose of this study was to comprehensively evaluate the association between diet and the risk for sporadic CRC in Shandong Province, China.

METHODS

In this case-control study, 317 patients with sporadic CRC and 317 controls were collected in Shandong Province, China. All the samples were collected on the basis of rigorous screening criteria. The data were analyzed using a χ² test, univariate or multivariate conditional logistic regression, and stratified analysis.

RESULTS

Multivariate logistic regression showed that the following are risk factors for sporadic CRC (all P<0.05): consumption of pork, fried food or barbecued meat; high Body Mass Index (BMI); alcohol abuse; psychosis; and the presence of a factory causing pollution near the home. Moreover, univariate analysis revealed the following qualities were also positively associated with CRC (all P<0.05): intake of animal oil, consuming brawn and kipper, smoking, exhibiting frequent anger, and poor sleep quality. Eating fresh fruit was inversely correlated with the incidence of CRC (P=0.012). Further stratified analysis demonstrated that BMI and the consumption of fried food, barbecued meat, or garlic were correlated with colon cancer. However, alcohol abuse and psychosis were related to an increased risk for rectal cancer.

CONCLUSION

Dietary factors are related to sporadic CRC in Shandong Province. Future interventions should focus on reducing the related risk factors while advocating for practice of the protective factors.

Serial mutational tracking in surgically resected locally advanced colorectal cancer with neoadjuvant chemotherapy

Background

We aim to investigate the utility of serial gene mutation tracking for locally advanced CRC in those who underwent curative resection following neoadjuvant chemotherapy.

Methods

We prospectively collected 10 locally advanced CRC cases for which curative resection was performed following preoperative neoadjuvant chemotherapy. Tissues from the primary tumour, distant metastatic tumours, and blood plasma were obtained during serial treatment. Comprehensive mutation analysis of 47 cancer-associated genes was performed using a pre-designed gene panel and next-generation sequencing.

Results

All cases showed a partial response to neoadjuvant chemotherapy, and pathological R0 resection was accomplished. In primary tumours, non-synonymous mutations were detected at between 1 and 14 sites before chemotherapy and at between 1 and 2 sites after. Founder mutations were precisely detected in blood plasma and metastatic tumours during longitudinal treatment.

Conclusions

Serial mutational analysis indicated that subclonal selection occurs during chemotherapy and that plasma can substitute for tumourous tissue in mutational analysis for drug selection and treatment decisions.

Fascin protein stabilization by miR-146a implicated in the process of a chronic inflammation-related colon carcinogenesis model

OBJECTIVE

In sporadic colon tumors, multistep process of well-known genetic alterations accelerates carcinogenesis; however, this does not appear to be the case in inflammation-related ones. We previously established a model of inflammation-related colon carcinogenesis using human colonic adenoma cells, and identified fascin as a driver gene of this process. We analyzed the microRNAs involved in the stable fascin expression in colon adenocarcinoma cells.

MATERIALS AND METHODS

miRNA microarray analysis was performed using FPCK-1-1 adenoma cells and its-derived FPCKpP₁-4 adenocarcinoma cells through chronic inflammation. To assess the involvement of miRNA in the inflammation-related carcinogenesis, sphere-forming ability, expression of colon cancer stemness markers, and stability of fascin protein via the proteasome using tough decoy RNA technique.

RESULTS

We found that 17 miRNAs including miR-146a were upregulated and 16 miRNAs were downregulated in FPCKpP₁-4 adenocarcinoma cells. We revealed that miR-146a in the adenocarcinoma cells brought about acquisition of sphere formation, cancer stemness, and inhibition of proteasomal degradation of the fascin protein.

CONCLUSIONS

We found that stable fascin expression is brought about via the inhibition of proteasome degradation by miR-146a in the process of a chronic inflammation-related colon carcinogenesis.

Genetic and epigenetic alterations of colorectal cancer

Colorectal cancer (CRC) arise from multi-step carcinogenesis due to genetic mutations and epigenetic modifications of human genome. Genetic mutations and epigenetic modifications were originally established as 2 independent mechanisms contributing to colorectal carcinogenesis. However, recent evidences demonstrate that there are interactions between these 2 mechanisms. Genetic mutations enable disruption of epigenetic controls while epigenetic modifications can initiate genomic instability and carcinogenesis. This review summarized genetic mutations and epigenetic modifications in colorectal carcinogenesis and molecular classification of CRC subtype based on genetic or epigenetic biomarkers for treatment response and prognosis. Molecular subtypes of CRC will permit the implementation of precision medicine with better outcome of management for CRC.

Clinical significance of circulating tumor cells via combined whole exome sequencing in early stage cancer screening: A case report

A newly-developed platform, integrating subtraction enrichment and immunostaining-fluorescence in situ hybridization (SE-iFISH), was applied to analyze the clinical significance of circulating tumor cells (CTCs) for early screening of cancer in healthy people. The present case report describes one healthy individual who accepted a CTC peripheral blood test, and 8 CTCs/7.5 ml blood were detected. However, various conventional cancer biomarkers were all negative, including cervical cytological inspection, alpha-fetoprotein, cancer antigen (CA)-125, CA19-9, carcinoembryonic antigen (CEA), CA15-3 and human papilloma virus. To explore the origin of the CTCs, whole exome sequencing was used to analyze the CTC variation spectrum. A total of 42 mutations were associated with cancer according to analysis in COSMIC (http://cancer.sanger.ac.uk/cosmic). The results revealed a high risk of tumor in the colorectum, stomach and breast (13, 12 and 6 variations matched, respectively). In this individual, an intestinal polyp was discovered and removed by colonoscopy. The intestinal polyp was identified to be a hyperplastic polyp by pathological diagnosis. No lesions were discovered in the stomach and breast. No CTCs were detected in this patient's blood at 1 and 6 months after removal of the lesions. This case indicates that CTC detection by SE-iFISH has potential in early stage cancer screening, and the mutation spectrum of CTC assists the tracking of its sources.

Loss of N-WASP drives early progression in an Apc model of intestinal tumourigenesis

N-WASP (WASL) is a widely expressed cytoskeletal signalling and scaffold protein also implicated in regulation of Wnt signalling and homeostatic maintenance of skin epithelial architecture. N-WASP mediates invasion of cancer cells in vitro and its depletion reduces invasion and metastatic dissemination of breast cancer. Given this role in cancer invasion and universal expression in the gastrointestinal tract, we explored a role for N-WASP in the initiation and progression of colorectal cancer. While deletion of N-wasp is not detectably harmful in the murine intestinal tract, numbers of Paneth cells increased, indicating potential changes in the stem cell niche, and migration up the crypt-villus axis was enhanced. Loss of N-wasp promoted adenoma formation in an adenomatous polyposis coli (Apc) deletion model of intestinal tumourigenesis. Thus, we establish a tumour suppressive role of N-WASP in early intestinal carcinogenesis despite its later pro-invasive role in other cancers. Our study highlights that while the actin cytoskeletal machinery promotes invasion of cancer cells, it also maintains normal epithelial tissue function and thus may have tumour suppressive roles in pre-neoplastic tissues. © 2018 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of Pathological Society of Great Britain and Ireland.

Primary Tumor Location in Colorectal Cancer: Comparison of Right- and Left-Sided Colorectal Cancer Characteristics for the Interventional Radiologist

One area which has emerged as an important factor for predicting molecular profile and treatment outcomes in metastatic colorectal cancer (mCRC) is primary tumor location. The importance of molecular characteristics of colorectal cancer has been firmly established in terms of prognosis and treatment algorithms for many years. Recent studies have also suggested that molecular profiles are important in locoregional therapies as well, with some data suggesting changes in treatment algorithms based on tumor location. Therefore, it is important for interventional radiologists to understand the basic molecular characteristics and development pathways of mCRC. Here, these disease characteristics are reviewed and the differences in left- versus right-sided primary tumor location are explored.

FSTL1 interacts with VIM and promotes colorectal cancer metastasis via activating the focal adhesion signalling pathway

Follistatin-like protein 1 (FSTL1) has been reported to have both tumour-promoting and tumour-suppressive characters. However, the role of FSTL1 in colorectal cancer (CRC) remains unclear. Here we showed that FSTL1 expression was significantly up-regulated in CRC tissues compared with the paired normal tissues. In addition, the higher FSTL1 expression was associated with the infiltrating depth, lymph node metastasis and poor prognosis of CRC. Enhanced expression of FSTL1 distinctly increased cell migration and invasion in vitro, as well as promoting liver metastasis of CRC in vivo. Conversely, knockdown of FSTL1 expression significantly repressed invasion and metastasis of CRC. Mechanically, transcription factor Smad3 was involved in FSTL1 protein expression inducing by TGFβ1-Smad2/3 signalling. Furthermore, this effect of FSTL1 in promoting CRC progression was actualised via activating focal adhesions signalling pathway and regulating cytoskeleton rearrangement. We identified VIM, as an interactive protein of FSTL1, participated in FSTL1-mediated aggressive phenotype. We showed the role of FSTL1 in CRC and explored its transcription regulation and downstream signalling molecular mechanisms. In conclusion, our findings suggested that FSTL1 promoted CRC progression and metastasis, making it a novel target for diagnosis and prognostic evaluation of CRC.

Cetuximab improves AZD6244 antitumor activity in colorectal cancer HT29 cells in vitro and in nude mice by attenuating HER3/Akt pathway activation

The present study investigated the molecular mechanism by which the epidermal growth factor receptor (EGFR) inhibitor cetuximab enhances the antitumor activity of the mitogen-activated protein kinase kinase (MEK) inhibitor AZD6244 in colorectal cancer HT29 cells. HT29 cells were treated with AZD6244 plus cetuximab and then subjected to the following assays: Cell Counting kit-8, BrdU-incorporation, flow cytometric cell cycle distribution and apoptosis analysis, western blot analysis, and nude mouse xenografts. The combination of AZD6244 and cetuximab significantly reduced HT29 cell viability and proliferation compared with AZD6244 alone. The combination treatment reduced the IC₅₀ value from 108.12±10.05 to 28.45±1.92 nM. AZD6244 and cetuximab also induced cell cycle arrest at G1 phase and reduced S phase (88.53% vs. 93.39%, P=0.080; 8.73% vs. 4.24%, P=0.082, respectively). Combination of AZD6244 with cetuximab significantly induced tumor cells apoptosis (14.61% vs. 8.99%, P=0.046). Inhibition of EGFR activity using cetuximab partially abrogated the feedback-activation of phosphorylated receptor tyrosine-protein kinase erB-3 (p-HER3) and p-AKT serine/threonine kinase (AKT), as well as prevented reactivation of p-extracellular regulated kinase (ERK) conferred by AZD6244 treatment. Combination of AZD6244 and cetuximab also inhibited HT29 cell xenograft growth in nude mice and suppressed HER3 and p-AKT levels in xenografts. The EGFR inhibitor cetuximab enhanced the antitumor activity of the MEK inhibitor AZD6244 in colorectal cells in vitro and in vivo. Co-inhibition of MEK and EGFR may be a promising treatment strategy in colorectal cancers.

An improved method for culturing patient-derived colorectal cancer spheroids

Recent advances allowed culturing and examination of patient-derived colorectal cancer (PD-CRC) cells as organoids or spheroids. To be applied to practical personalized medicine, however, current methods still need to be strengthened for higher efficiency. Here we report an improved method to propagate PD-CRC tumor initiating cells (TICs) in spheroid culture. We established > 100 cancer spheroid lines derived from independent colorectal cancer patients employing a serum-containing medium with additional inhibitors, Y27632 and SB431542. Because colorectal cancer spheroids showed wide-range growth rates depending on the patient tumors, we searched for supplementary factors that accelerated proliferation of slow-growing CRC-TIC spheroids. To this end, we introduced a convenient growth-monitoring method using a luciferase reporter. We found that epidermal growth factor (EGF) and/or basic fibroblast growth factor (bFGF) were critical for steady propagation of a subset of CRC-TIC spheroids carrying the wild-type RAS and RAF genes. We also identified 5'-(N-ethyl-carboxamido)-adenosine (NECA), an adenosine receptor agonist, as an essential supplement for another subset of spheroids. Based on these results, we propose to optimize culture conditions for CRC-TIC spheroids by adjusting to the respective tumor samples. Our method provides a versatile tool that can be applied to personalized chemotherapy evaluation in prospective clinical studies.