Molecular Diagnostics Of Colorectal Cancer

Colorectal cancer (CRC) is a heterogeneous disease, and encompasses fundamentally differentmolecular phenotypes following various pathways of carcinogenesis. Molecular characteristicsmight predispose tumors to a worse prognosis and identification of those enables identifyingpatients with high risk of disease recurrence. One of the application of molecular pathology in CRCrefers to microsatellite instability (MSI). MSI-H is a hallmark alteration of HNPCC/Lynch syndromeassociatedtumors, but is also found in sporadic colon cancers. MSI-H has a significant impact ontumor biology. This is reflected by a more favorable prognosis. MicroRNAs involved in differentsignaling networks leading to colon cancer metastasis, mainly PTEN/PI3K, EGFR, TGF-beta, and p53signaling pathways of metastatic colon cancer. The alteration of miRNA profiles has been correlatedwith the transformation and metastasis of colon cancer. They could directly target genes playing acentral role in epithelial-mesenchymal-transition (EMT), a cellular transformation process thatallows cancer cells to acquire motility and invasiveness. One of the best known EMT-related miRNAsis the miR-200 family. Tumor specific methylation in circDNA is a potential target for thedevelopment of non-invasive, blood-based assays for cancer diagnosis. Following identification as apotential biomarker,SEPT9 gene promoter region was initially identified as being differentiallymethylated. Other methylation-based plasma biomarkers including the promoters of genesRASSF1A, APC and E-cadherin, and completely novel sequences such as CAHM, a long non-codingRNA gene. Tumor budding is thought to represent the morphological correlate of EMT in colorectalcancers and has been strongly linked to adverse clinicopathological features and poor overall anddisease-free patient survival. Colon cancer remains a leading cause of mortality worldwide despitethe well-characterized molecular events in the adenoma-to-carcinoma sequence. it is, therefore,apparent that, despite many strides in understanding the development and progression of CRC, alot remains largely unknown due to the multifactorial process of this disease.