Colorectal Cancer Biomarkers: Where Are We Now?

Molecular biomarkers for an early diagnosis, effective treatment and prognosis of colorectal cancer: Current updates

Colorectal cancer (CRC) is the third most prevalent cancer in the world. Globally, it has been estimated that about 1.4 million new cases of colorectal cancer are diagnosed every year. CRC is a multifactorial disease that arises due to genetics as well as epigenetic alterations in a number of oncogenes, tumor suppressor genes, mismatch repair genes, as well as cell cycle regulating genes in colon mucosal cells. These molecular alterations have been considered as potential CRC biomarkers because they can provide the physicians with diagnostic, prognostic and treatment response information. The goal is to identify relevant, cheap and applicable biomarkers that contribute to patient management decisions, resulting in direct benefits to patients. In this review, we will outline the most currently available and developing tumor tools, and blood molecular biomarkers. Also, we will illustrate their diagnostic, therapeutic and prognostic applications.

Diagnostic value evaluation of trefoil factors family 3 for the early detection of colorectal cancer

AIM

The purpose of this study was to evaluate the diagnostic value of trefoil factor family 3 (TFF3) for the early detection of colorectal cancer (CC).

METHODS

Serum TFF3 and carcino-embryonic antigen (CEA) were detected in 527 individuals, including 115 healthy control (HC), 198 colorectal adenoma (CA), and 214 CC individuals in the training group.

RESULTS

Serum TFF3 showed no significant correlation with age, gender, or tumor location but showed significant correlation with the tumor stage. Serum TFF3 in the CC group was significantly higher than in the HC or CA group. The AUC values of TFF3 for discriminating between HC and CC and between CA and CC were 0.930 (0.903, 0.958) and 0.834 (0.796, 0.873). A multivariate model combining TFF3 and CEA was built. Compared to TFF3 or CEA alone, the multivariate model showed significant improvement (P < 0.001). For discriminating between HC and CC, HC and early stage CC, HC and advanced stage CC, CA and CC, CA and early stage CC, and CA and advanced stage CC in the training group, the sensitivities were 92.99%, 91.46%, 93.18%, 73.83%, 76.83%, and 81.82%, and the specificities were 91.30%, 91.30%, 93.91%, 88.38%, 77.27%, and 88.38%, respectively. After validation, the sensitivities were 89.39%, 85.71%, 90.79%, 72.73%, 71.43%, and 78.95%, and the specificities were 87.85%, 87.85%, 2.52%, 87.85%, 80.77%, and 87.50%, respectively.

CONCLUSION

The multivariate diagnostic model that included TFF3 and CEA showed significant improvement over the conventional biomarker CEA and might provide a potential method for the early detection of CC.

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.

Biomarkers Discovery for Colorectal Cancer: A Review on Tumor Endothelial Markers as Perspective Candidates

Colorectal cancer (CRC) is the third most common cancer in the world. The early detection of CRC, during the promotion/progression stages, is an enormous challenge for a successful outcome and remains a fundamental problem in clinical approach. Despite the continuous advancement in diagnostic and therapeutic methods, there is a need for discovery of sensitive and specific, noninvasive biomarkers. Tumor endothelial markers (TEMs) are associated with tumor-specific angiogenesis and are potentially useful to discriminate between tumor and normal endothelium. The most promising TEMs for oncogenic signaling in CRC appeared to be the TEM1, TEM5, TEM7, and TEM8. Overexpression of TEMs especially TEM1, TEM7, and TEM8 in colorectal tumor tissue compared to healthy tissue suggests their role in tumor blood vessels formation. Thus TEMs appear to be perspective candidates for early detection, monitoring, and treatment of CRC patients. This review provides an update on recent data on tumor endothelial markers and their possible use as biomarkers for screening, diagnosis, and therapy of colorectal cancer patients.

The role of testosterone in colorectal carcinoma: pathomechanisms and open questions

Colorectal cancer (CRC) is the fourth commonest type of malignancy after breast, lung and prostate in the USA and accounts for approximately 49,190 deaths annually in USA alone. The 5-year survival rate of CRC has increased over the past decades, in part, due to greater awareness and the widespread implementation of national screening programmes. Recently, a number of studies reported that males have a higher risk of developing CRC due to the action of testosterone. Testosterone is an androgen that is responsible for the development of male secondary sex characteristics and for spermatogenesis. Studies on rats with mutated Apc tumour-suppressor gene subjected to either ovariectomy or orchidectomy exhibit different risks of CRC. Female rats subjected to ovariectomy are at higher risk of CRC, whereas orchidectomised male rats exhibit a lower risk of developing CRC. Sex hormones, in particular estrogen and testosterone, play a significant role in the development of CRC since the anti-neoplastic effect of estrogen lost during ovariectomy increases the risk of females developing CRC. Male mice exposed to testosterone after orchidectomy were also at greater risk than those who were orchidectomised but administered placebo only. Moreover, the recently established role of membrane androgen receptors in regression of CRC via non-genomic androgen-dependent action sets these receptors apart from intracellular androgen receptors (iARs) which themselves promote CRC development. In addition, testosterone-albumin conjugates are selective to membrane androgen receptors (mARs) and lead to apoptosis via caspase-3 activation. Akt kinases promote invasion of colon cancer cells when phosphorylated. These kinases are dephosphorylated upon activation of mARs, thereby reducing colon cancer cell motility and invasiveness. Testosterone similarly plays important roles in human CRC. Long cytosine-adenine-guanine (CAG) repeats in the gene for the androgen receptors have been associated with a poor 5-year survival compared to shorter CAG repeats. Very recently, the measurement of serum unbound testosterone has been suggested as a novel biomarker along with carcinoembryonic antigen in CRC. In conclusion, testosterone may promote the development of CRC via a number of pathways, which may place males at greater risk. Testosterone holds promise as a potential biomarker in CRC risk prediction; however, further studies are required to better define its role in colorectal neoplasia.

Identification of actin beta-like 2 (ACTBL2) as novel, upregulated protein in colorectal cancer

Early diagnosis of colorectal cancer (CRC) can be of value for increasing the survival rate of patients. Recently, proteomic strategies to identify markers for the diagnosis of cancer at an early stage have been employed with noteworthy results. To extend these studies, we utilized two dimensional gel electrophoresis and mass spectrometry for expression profiling of proteins extracted from the freshly frozen human colorectal cancer tissue specimens and the comparable regions of adjacent normal mucosa (serving as controls). Four gel spots were determined to be differentially stained between the tumor and the control samples on a consistent basis. Following mass spectrometric analysis of these spots, six proteins were identified; five of these had previously been reported to be associated with colorectal cancer. One protein actin beta-like 2 (ACTBL2), not linked with colorectal cancer in the earlier reports, was however found to be at higher abundance in colorectal tumor samples both by proteomics and immunohistochemistry analysis. Thus ACTBL2 association and differential upregulation in colorectal cancer is novel, and as such may contribute to our understanding of the colorectal carcinogenesis and potentially serve a function in developing markers for colorectal cancer.

BIOLOGICAL SIGNIFICANCE

Colorectal cancer (CRC) is a major cause of death world-wide and good markers for early detection are lacking. In this study we conducted a proteomic analysis of tumor vs. normal tissue. We corroborated the finding of a number of previously identified proteins associated with CRC and more importantly identified a novel protein, ACTBL2, which we demonstrated to be upregulated in CRC. As additional proteins associated with CRC are identified the potential for developing panels of markers may be realized with better outcomes in early cancer detection.

Colorectal cancer patients exhibit increased levels of galanin in serum and colon tissues

Galanin (GAL) is a 30-amino acid neuropeptide that is expressed in both the central and peripheral nervous system, including the enteric nervous system (ENS). Increased GAL concentrations have been identified in the blood of colorectal cancer (CRC) patients. The aim of the present study was to assess whether sections of the colon wall containing ENS plexuses or CRC tumor are associated with increased GAL concentrations. Blood samples were collected from 68 CRC patients and 39 healthy volunteers. In addition, samples of CRC tumors and colon wall tissue in close proximity to and distant from the neoplastic tissue were obtained from 22 CRC patients. The GAL concentration of sera and tissue homogenates obtained from three sections of the colon wall (mucosa with submucosa, muscularis externa and CRC tumor) was analyzed by ELISA. The localization of GAL was evaluated using immunohistochemistry and morphometry was used to measure the distribution of GAL-immunoreactive (GAL-Ir) myenteric plexuses in the vicinity of cancer invasion and in sections of the colon wall distant from the tumor. The GAL serum concentration of CRC patients was 2.4 times higher than that of the control group. The GAL concentration was highest in the homogenates of neoplastic tissue and mucosa obtained from the control (distant) section of the intestinal wall, followed by that in the mucosa and muscularis externa proximal to the tumor. The lowest GAL concentrations were identified within the muscular layer of the colon wall located distant from the tumor. Strong GAL immunoreactivity was identified in the cancer cells, intestinal epithelium and the submucosal and myenteric plexuses. Morphometric analysis revealed that the GAL-Ir myenteric plexuses in the vicinity of tumor infiltration were significantly smaller in size than those in the intact section of the large intestine. Furthermore, no associations were identified between the clinicopathological characteristics of CRC patients and GAL serum and tissue concentration. The increased GAL serum concentrations observed in CRC patients in comparison to healthy controls may result from GAL secretion by CRC tumors, however, other sources of GAL cannot be excluded. The atrophy of myenteric plexuses within close proximity to the tumor may affect the colon function of CRC patients. In conclusion, investigation into the presence of GAL in the colon wall and serum of CRC patients revealed that serum and tissue GAL levels may present useful potential biomarkers in CRC patients.

Droplet Digital PCR Based Androgen Receptor Variant 7 (AR-V7) Detection from Prostate Cancer Patient Blood Biopsies

Androgen receptor splice variant V7 (AR-V7) was recently identified as a valuable predictive biomarker in metastatic castrate-resistant prostate cancer. Here, we report a new, sensitive and accurate screen for AR-V7 mRNA expression directly from circulating tumor cells (CTCs): We combined EpCAM-based immunomagnetic CTC isolation using the IsoFlux microfluidic platform with droplet digital polymerase chain reaction (ddPCR) to analyze total AR and AR-V7 expression from prostate cancer patients CTCs. We demonstrate that AR-V7 is reliably detectable in enriched CTC samples with as little as five CTCs, even considering tumor heterogeneity, and confirm detection of AR-V7 in CTC samples from advanced prostate cancer (PCa) patients with AR-V7 detection limited to castrate resistant disease status in our sample set. Sensitive molecular analyses of circulating tumor cells (CTCs) or circulating tumor nucleic acids present exciting strategies to detect biomarkers, such as AR-V7 from non-invasive blood samples, so-called blood biopsies.

Gene Expression Analysis of Sporadic Early-Onset Rectal Adenocarcinoma

BACKGROUND

Overall declines in incidence of rectal cancer (RC) in patients older than 50 years have been mostly attributed to improvement in treatment modalities and introduction of age-based screening. Recent studies, however, have shown a rise in the incidence of RC in patients younger than 50 years. The etiology of early-onset (EO) RC is not well understood. The aim of this study is to elucidate the molecular features of (EO) RC and show its uniqueness compared to late-onset (LO) disease.

METHODS

Two cohorts of patients with sporadic RC were identified. Tumors and matching non-involved tissues from six (EO) RC patients (< 50 years) and six (LO) RC patients (>65 years) were obtained from Pathology archives. Deparaffinized tissues were macro-dissected from FFPE sections, RNA isolated and used for expression profiling of 770 cancer related genes representing 13 canonical pathways. Statistical analysis was performed using the Gene Expression R-script module within the nCounter software v2.6. A gene was considered to be above background if the average count for the target gene was greater than the average counts for the eight negative control genes and if the P value of the t-test was less than 0.05.

RESULTS

When we compared rectal tumors to non-involved rectal tissues, changes in expression levels of 171 genes were statistically significant in early-onset group and 151 genes in late-onset group. Further comparative gene expression analysis between early- and late-onset rectal tumors normalized to their matching non-involved tissues revealed that changes in expression of 65 genes were unique to early-onset rectal tumors with 16 genes being up- and 49 genes down-regulated using the cutoff criteria of expression levels difference >2 fold and p-value <0.01. At the pathway level, MAPK signaling was the most deregulated pathway in early-onset rectal tumors compared to PI3K-AKT signaling pathway being the most deregulated in late-onset rectal tumors.

CONCLUSIONS

Results of this study suggest that sporadic early-onset rectal cancer is characterized by distinct molecular events compared to late-onset disease.

Increased MACC1 levels in tissues and blood identify colon adenoma patients at high risk

Background

Colorectal cancer is a preventable disease if caught at early stages. This disease is highly aggressive and has a higher incidence in African Americans. Several biomarkers and mutations of aggressive tumor behavior have been defined such as metastasis-associated in colon cancer 1 (MACC1) that was associated with metastasis in colorectal cancer patients. Here, we aim to assess colon tissue MACC1 protein and circulating MACC1 transcripts in colon preneoplastic and neoplastic African American patients.

Methods

Patients’ tissue samples (n = 143) have been arranged on three tissue microarrays for normal (n = 26), adenoma (n = 68) and cancer (n = 49) samples. Immunohistochemistry was used to detect MACC1 expression. Blood samples (n = 93) from normal (n = 45), hyperplastic (n = 15) and tubular adenoma (n = 33) patients were used to assess MACC1 transcripts using qRT-PCR. Distribution of continuous variables was tested between different diagnoses with Kruskal–Wallis test. Categorical variables were tested by Chi square test. We assessed the prognostic ability of IHC staining by calculating area under receiver operating characteristics curve (ROC) for adenoma and cancer separately. Differences between groups in terms of MACC1 transcript levels in plasma were calculated by using non-parametric (exact) Wilcoxon-Mann–Whitney tests. We performed all calculations with SPSS, version 21.

Results

In patient tissues, there was a statistically significant difference in MACC1 expression in normal vs. adenoma samples (p = 0.004) and normal vs. cancer samples (p < 0.001). There was however no major difference in MACC1 expression between adenoma vs. cancer cases or tubular adenomas vs tubulovillous adenomas. The area under the curve for both normal vs. adenoma and normal vs. cancer cases were 70 and 67 %, respectively. MACC1 expression was not correlated to age, gender or anatomical sample location. In patient plasma, MACC1 transcripts in adenoma patients were significantly higher than in plasma from normal patients (p = 0.014). However, the difference between normal and hyperplastic plasma MACC1 transcripts was not statistically significant.

Conclusion

Metastasis-associated in colon cancer 1 is expressed at early stages of colorectal oncogenesis within the affected colonic tissue in this patient cohort. The plasma transcripts can be used to stratify African American patients at risk for potential malignant colonic lesions.

Systems medicine in colorectal cancer: from a mathematical model toward a new type of clinical trial

Current colorectal cancer (CRC) treatment guidelines are primarily based on clinical features, such as cancer stage and grade. However, outcomes may be improved using molecular treatment guidelines. Potentially useful biomarkers include driver mutations and somatically inherited alterations, signaling proteins (their expression levels and (post) translational modifications), mRNAs, micro-RNAs and long noncoding RNAs. Moving to an integrated system is potentially very relevant. To implement such an integrated system: we focus on an important region of the signaling network, immediately above the G1-S restriction point, and discuss the reconstruction of a Molecular Interaction Map and interrogating it with a dynamic mathematical model. Extensive model pretraining achieved satisfactory, validated, performance. The model helps to propose future target combination priorities, and restricts drastically the number of drugs to be finally tested at a cellular, in vivo, and clinical-trial level. Our model allows for the inclusion of the unique molecular profiles of each individual patient's tumor. While existing clinical guidelines are well established, dynamic modeling may be used for future targeted combination therapies, which may progressively become part of clinical practice within the near future. WIREs Syst Biol Med 2016, 8:314-336. doi: 10.1002/wsbm.1342 For further resources related to this article, please visit the WIREs website.

A 2015 survey of established or potential epigenetic biomarkers for the accurate detection of human cancers

Context The silencing or activation of cancer-associated genes by epigenetic mechanisms can ultimately lead to the clonal expansion of cancer cells. Objective The aim of this review is to summarize all relevant epigenetic biomarkers that have been proposed to date for the diagnosis of some prevalent human cancers. Methods A Medline search for the terms epigenetic biomarkers, human cancers, DNA methylation, histone modifications and microRNAs was performed. Results One hundred fifty-seven relevant publications were found and reviewed. Conclusion To date, a significant number of potential epigenetic cancer biomarkers of human cancer have been investigated, and some have advanced to clinical implementation.

Developmental genes significantly afflicted by aberrant promoter methylation and somatic mutation predict overall survival of late-stage colorectal cancer

Carcinogenesis is an exceedingly complicated process, which involves multi-level dysregulations, including genomics (majorly caused by somatic mutation and copy number variation), DNA methylomics, and transcriptomics. Therefore, only looking into one molecular level of cancer is not sufficient to uncover the intricate underlying mechanisms. With the abundant resources of public available data in the Cancer Genome Atlas (TCGA) database, an integrative strategy was conducted to systematically analyze the aberrant patterns of colorectal cancer on the basis of DNA copy number, promoter methylation, somatic mutation and gene expression. In this study, paired samples in each genomic level were retrieved to identify differentially expressed genes with corresponding genetic or epigenetic dysregulations. Notably, the result of gene ontology enrichment analysis indicated that the differentially expressed genes with corresponding aberrant promoter methylation or somatic mutation were both functionally concentrated upon developmental process, suggesting the intimate association between development and carcinogenesis. Thus, by means of random walk with restart, 37 significant development-related genes were retrieved from a priori-knowledge based biological network. In five independent microarray datasets, Kaplan-Meier survival and Cox regression analyses both confirmed that the expression of these genes was significantly associated with overall survival of Stage III/IV colorectal cancer patients.

Immune Checkpoint Modulation in Colorectal Cancer: What's New and What to Expect

Colorectal cancer (CRC), as one of the most prevalent types of cancer worldwide, is still a leading cause of cancer related mortality. There is an urgent need for more efficient therapies in metastatic disease. Immunotherapy, a rapidly expanding field of oncology, is designed to boost the body's natural defenses to fight cancer. Of the many approaches currently under study to improve antitumor immune responses, immune checkpoint inhibition has thus far been proven to be the most effective. This review will outline the treatments that take advantage of our growing understanding of the role of the immune system in cancer, with a particular emphasis on immune checkpoint molecules, involved in CRC pathogenesis.