Assessment Of Long Noncoding RNA CCAT1 In Colorectal Cancer Patients

Colorectal cancer (CRC) is the third most commonly diagnosed cancer and the fourth leading cause of cancer mortality worldwide. Colorectal cancer is the 7th commonest cancer in Egypt, representing 3.47% of male cancers and 3% of female cancers. Cancer metastasis in the liver, which develops in 50% of CRC patients, represents the major cause of death in those patients .

CRC can be easily cured with surgery, if it is discovered and diagnosed early. Although in the recent years much progress has been achieved in screening for cancer, the prognosis of colorectal cancer is still poor. Colonoscopy is the standard screening method to detect early CRC .

Moreover, the other CRC screening tests (such as sigmoidoscopy, fecaloccult blood test (FOBT), tumor markers, fecal immunochemical test (FIT) and radiologic tests) have low sensitivity and specificity or high cost . Therefore, there is a great need for non-invasive and accurate biomarkers for detection of CRC.

Focusing into the physiological risk factors, genetic alterations may result from external influences like chemicals, radiation as well as pathogens (viruses) that disrupt the genome stability. Besides extensive studies on DNA damages in cell cycle regulation, past few decades evident the role of non-coding RNAs (ncRNAs) in the context of tumor biology. The existence of non-protein coding RNAs was known over years, where biological functions of these RNAs have been uncovered by progressive investigations. Non-coding RNAs have further classifications, among which the functions of micro RNAs (miRNAs) have been thoroughly explored. Thus, the concentration on the other type of ncRNA, the long non-coding RNAs (lncRNAs), is a yet emerging field in the research of cancer biology. A fraction of the genome comprises these lncRNAs who are actually poorly translated as compared to other protein coding counterparts.

LncRNAs are transcripts of longer than 200 bp.They have important roles in cellular processes like transcriptional regulation, chromosome remodeling, post-translational modifications and disruption in them may lead to disease conditions.

Colon cancer associated transcript-1 (CCAT1) is consistently upregulated in and is associated with pathogenesis of a number of malignancies, including gastric carcinoma, colon cancer, gallbladder cancer and hepatocellular carcinoma.

CCAT1 was identified initially in colon cancer Zhao (2016), who demonstrated that high expression of CCAT1 in CRC plasma may be used as predictive biomarker for screening of CRC.

The dysregulated expression of CCAT1 affects not only tumorigenesis, but also clinical manifestation, such as tumor size, lymph node metastasis, TNM stage, differentiation, invasion, patient survival and treatment outcome. This finding renders CCAT1 attractive as target for therapeutic intervention in cancer. The current available studies of the expression, clinical relevance, biological behavior and regulatory mechanism of CCAT1 in various cancers have been described. Also, the potential roles of CCAT1 in the diagnosis, prognostic evaluation and treatment of cancers have been discussed.