Detection of mutations associated with colorectal cancer in DNA from whole-gut lavage fluid

Biomarker Profile of Colorectal Cancer: Current Findings and Future Perspective

OBJECTIVE

Breakthroughs in omics technology have led to a deeper understanding of the fundamental molecular changes that play a critical role in the development and progression of cancer. This review delves into the hidden molecular drivers of colorectal cancer (CRC), offering potential for clinical translation through novel biomarkers and personalized therapies.

METHODS

We summarizes recent studies utilizing various omics approaches, including genomics, transcriptomics, proteomics, epigenomics, metabolomics and data integration with computational algorithms, to investigate CRC.

RESULTS

Integrating multi-omics data in colorectal cancer research unlocks hidden biological insights, revealing new pathways and mechanisms. This powerful approach not only identifies potential biomarkers for personalized prognosis, diagnosis, and treatment, but also predicts patient response to specific therapies, while computational tools illuminate the landscape by deciphering complex datasets.

CONCLUSIONS

Future research should prioritize validating promising biomarkers and seamlessly translating them into clinical practice, ultimately propelling personalized CRC management to new heights.

Isolation and Characterization of Extracellular Vesicles in Human Bowel Lavage Fluid

Colorectal cancer (CRC) is the third most common cancer worldwide and is detected in late stages because of a lack of early and specific biomarkers. Tumors can release extracellular vesicles (EVs), which participate in different functions, such as carrying nucleic acids to target cells; promoting angiogenesis, invasion, and metastasis; and preparing an adequate tumor microenvironment. Finally, bowel lavage fluid (BLF) is a rarely used sample that is obtained during colonoscopy. It presents low variability and protein degradation, is easy to handle, and is representative of EVs from tumor cells due to proximity of the sample collection. This sample has potential as a research tool and possible biomarker source for CRC prognosis and monitoring. In this study, EVs were isolated from human BLF by ultracentrifugation, then characterized by transmission electron microscopy and atomic force microscopy. EV concentration was determined by nanoparticle tracking analysis, and tetraspanins were determined by Western blot, confirming correct EV isolation. RNA, DNA, and proteins were isolated from these EVs; RNA was used in real-time PCR, and proteins were used in an immunoblotting analysis, indicating that EV cargo is optimal for use and study. These results indicate that EVs from BLF can be a useful tool for CRC study and could be a source of biomarkers for the diagnosis and monitoring of CRC.

Use of Omics Technologies for the Detection of Colorectal Cancer Biomarkers

Colorectal cancer (CRC) is one of the most frequently diagnosed cancers with high mortality rates, especially when detected at later stages. Early detection of CRC can substantially raise the 5-year survival rate of patients, and different efforts are being put into developing enhanced CRC screening programs. Currently, the faecal immunochemical test with a follow-up colonoscopy is being implemented for CRC screening. However, there is still a medical need to describe biomarkers that help with CRC detection and monitor CRC patients. The use of omics techniques holds promise to detect new biomarkers for CRC. In this review, we discuss the use of omics in different types of samples, including breath, urine, stool, blood, bowel lavage fluid, or tumour tissue, and highlight some of the biomarkers that have been recently described with omics data. Finally, we also review the use of extracellular vesicles as an improved and promising instrument for biomarker detection.

Rectal effluent as a research tool

Studies of localized secretions are generally superior to those of blood because they contain higher concentrations of molecules specific to the organ of interest. A common method used to analyze localized secretions is lavage. The flow of fluid over the lining of a cavity picks up both cells and soluble factors, and the effluent can be collected for study. Gastrointestinal (GI) lavage is easily and noninvasively performed by the administration of gut lavage solutions such as those routinely given to patients prior to colonoscopy, with GI lavage fluid being the copious, watery rectal effluent subsequently induced. Residual effluent is currently suctioned from the colon and discarded during colonoscopy. With millions of routine colonoscopies performed per year, GI lavage fluid is a rich and largely untapped resource for basic and clinical research. Rectal effluent can also be easily collected in a toilet receptacle without need for a colonoscopy. Rectal effluent generated in this manner has been used to study diarrheal disease, mucosal immunology, inflammatory bowel disease, celiac disease, and cancer. It is often referred to as gut lavage, colon lavage, GI lavage, or whole gut lavage fluid, which makes it challenging to locate previous studies in the literature and there are currently no comprehensive reviews of its use as a research tool. This review attempts to fill this void by discussing previous applications of rectal effluent in research and the methods that have been developed for its collection, stabilization, and analysis.

DNA quantification of exfoliated colonocytes as a novel screening tool for colorectal cancer

AIMS

Colorectal cancer (CRC) sheds viable cells in the mucocelluar layer overlaying the colonic mucosa which travels distally alongside the faecal stream. These cells can be retrieved from the surface of the rectal mucosa. DNA quantification of these cells may be a marker of CRC, assessment of which was aim of this study.

METHODS

A prospective double-blinded study of 467 consecutive patients referred with symptoms suggestive of CRC. Cells were collected from the surface of the rectal mucosa and total DNA quantified. DNA scores were compared with outcome after subjects had completed bowel investigations. Analysis of receiver operating characteristic (ROC) curves was performed to determine the optimum cut-off point for a positive result.

RESULTS

107 of the 467 patients were excluded due to; excessive faecal contamination of samples (n = 84); declined investigations (n = 17); inappropriate referral (n = 5); unfit (n = 1). 263 patients had lower GI endoscopy; 89 CT colonography and 8 barium enema. The diagnosis were; CRC (n = 23), inflammatory bowel disease (IBD) (n = 7), adenomatous polyps (AP) (n = 20) and no significant abnormality detected (n = 310). ROC analysis revealed that sensitivities at a specificity of 60% for detecting CRC were 91.3%; for CRC and IBD 86.7%; and for CRC, IBD and AP 72.0%.

CONCLUSION

In symptomatic patients DNA quantification of cells retrieved from the surface of the rectal mucosa is sensitive for the detection of CRC. Although faecal contamination is a limitation of this technique, refinement and application of other molecular tests hold promise for a better non invasive method for the detection of CRC.

Adduction of human p53 gene by fecal water: an in vitro biomarker of mutagenesis in the human large bowel

A polymerase arrest assay was designed to determine sites of adduction in the human p53 gene induced by incubation with fecal water. Significant formation of adducts was observed on p53 DNA after a 2-h incubation in fecal water from 10 of 17 samples studied. Large sample-to-sample variation was observed. The major sites of polymerase termination occurred at nucleotides 3' to guanine residues. Adduct sites coincided with colorectal cancer p53 mutation "hotspots," highlighting the potential carcinogenicity of fecal material.

Screening for p53 and K-ras mutations in whole-gut lavage in chronic inflammatory bowel disease

OBJECTIVES

Molecular screening for frequently mutated genes may increase the likelihood of identifying cancer risk groups, such as patients with longstanding inflammatory bowel disease. This study investigated the prevalence and time course of p53 and K-ras mutations in colonic lavage fluid of patients with inflammatory bowel disease.

METHODS

Colonic lavage fluid from 190 patients with ulcerative colitis (73), Crohn's disease (58) or controls (49 non-tumour, 10 colorectal cancer) was studied by oligomer-specific hybridization for K-ras mutations and single-strand conformation polymorphism (SSCP) for p53 mutations. Follow-up investigations were carried out after 1-3 years.

RESULTS

Mutations were most frequent in carcinomas (5/10, 50%) and rare in non-tumour controls (1/49, 2.0%). They were found in Crohn's colitis in 15.4%, in extensive ulcerative colitis in 18.6%, in left-sided ulcerative colitis in 13.3%, and in distal ulcerative colitis in 6.7% (P > 0.05). There was a positive association with disease duration (> or =11 years, P < 0.05). Follow-up investigations detected the same mutation in four patients and revealed new mutations in three patients.

CONCLUSIONS

In our large series of patients with inflammatory bowel disease, K-ras and p53 mutations could be detected with reasonable frequency and confirmed at follow-up in at least some patients. Our data encourage the use of molecular screening for the detection of malignant precursor lesions in at-risk patients.

Gene mutation as a target for early detection in cancer diagnosis

The increasing number of genetic aberrations implicated in the development of human cancer has prompted a search to detect them at the earliest possible stage of their formation. Of the many such genetic changes identified thus far, relatively few meet the standard for markers in early diagnosis and prognosis, namely that the genetic modifications occur during the early onset phase of cancer development. Parallel to the increasing number of such genes is the growing availability of technologies using more powerful and cost-efficient methods that enable mass screening for genetic alterations. The purpose of this review is to summarize the currently available genes that can serve as markers for early detection of cancers and methods that allow their detection.