An Overview: The Role of miRNA in the Development of Colorectal Cancer

This literature review examines the crucial role of microRNAs (miRNAs) in colorectal cancer (CRC), a significant cause of cancer-related deaths. It explores how miRNAs regulate gene expression, cellular homeostasis, and their impact on tumor suppression, oncogene activation, and cancer cell proliferation, metastasis, and invasion. The review highlights the potential of miRNAs as therapeutic targets, including the use of miRNA-based medications in clinical trials. It discusses the mechanisms of miRNA action, including their interaction with messenger RNAs and their role in various diseases. Additionally, the review addresses the use of non-coding RNAs (ncRNAs) and bioinformatics approaches, such as the TCGA database, to identify prognostic biomarkers for CRC. The study identifies specific miRNAs, such as miR-103a-3p, miR-143-5p, and miR-215, as potential prognostic markers for COAD, emphasizing the importance of understanding miRNA expression and its connection to CRC patient survival. The review concludes by emphasizing the need for further research into down-regulated miRNAs in CRC tumors to understand the pathogenesis of CRC.

Literature Review
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Literature review
Topic: Role OF miRNA in colorectal cancer.
Colorectal cancer (CRC) is considered the fourth directing reason for cancer-related
casualties around the. There are several reasons for CRC to prevail, but the primary reason is the
liver metastasis for mortality in CRC patients, arising in about 60% of patients with no helpful
therapies. MicroRNAs (miRNAs) are significant regulators for gene expression and cellular
homeostasis (Xio, et al., 2008). This review presents the sent of studies that were identified,
observed, and reviewed to provide an in-depth study on the role of miRNA in colorectal cancer
and specify the clinically related miRNA,s and evaluate their potential aim in targeting colorectal
cancer.
It has been noted by Ye, et al., (2019), the essential part of miRNAs in the pathogenesis
of cancer has been adequately reported that involves CRC and related disease. miRNAs are
realized as targets for genomic-based lesions, which are mostly inactivated tumor suppressors,
activated oncogenes, and cancer cells that result in epigenetic silencing, amplification, and
deletion. Besides that, miRNAs are recognized to manage the suppressor signaling pathways and
the oncogenic. More than that, it participates in the proliferation, metastasis, and growth invasion
of cancer cells. Several functional types of research have reported the anti-tumorigenic
properties of particular miRNAs presented in cancer cells, and their probability to be used as
unique anti-cancer molecules. Few of the miRNA-based medications have already been attained
to enter the phase 2 clinical trials. According to Danese, et al., (2017), nearly 30% of human
genes are under the supervision of small molecules known as microRNAs. These molecules
work to impede specific genes to modify into essential proteins and govern most necessary
procedures like cell development and division. However, their process to accomplish so is still
unclear. Presently various researchers have worked with the European Molecular Biology
Laboratory (EMBL) have formulated a recent technique that disclosed the procedure of effort for
microRNAs within a test tube.

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Another study published by Wang, et al., (2019), indicates that microRNAs obstruct the
initiation of the translation process, which is the quickest and core step in the procedure that
spins genetic data stocked on messenger RNAs that turns into proteins. Also, the central dogma
in molecular biology explains that the DNA where genetic data is stored is transcribed via units
of messenger RNAs that are later translated into proteins. These MicroRNAs are tiny molecules
that have no link to encode the essential proteins by themselves; however, they get connected
and attached to messenger RNAs. They have functions and the purpose of working as locks for
messenger RNAs and precluding their translation process into proteins. However, their whole
process is still unknown, and this effect of protein synthesis impedes a long-standing mystery. It
has been difficult to immediately assess when and how microRNAs stuck the messenger RNAs
and impeded their functions.
As noted by Chang, et al., (2008), the new strategy to researching micro RNAs inactivity
in a test tube helps pave the way to related research of human and microRNAs. These
MicroRNAs are essential as they have a crucial role in several diseases like a viral disease,
cancer, and diabetes. The recent in vitro operation will not just assist in relieving the light on
various roles of microRNAs in infection but could also perform as a purpose for new techniques
in the discovery of drugs. Several Non-coding RNAs are abbreviated as ncRNAs; these are the
types of RNA that are not used in translation as they cannot be translated simply into protein.
ncRNAs were previously evaluated and known as junk RNA. But in the past decades, along with
the improvement in high-throughput sequencing technology, many researchers have known the
significant function of ncRNAs. These molecules of ncRNAs consist of available kinds of RNA
that include long non-coding RNAs (lncRNAs), ribosomal RNAs, transfer RNAs, and
microRNAs (miRNAs). Although the majority of the biological processes are conducted by
proteins present in organisms, ncRNAs furthermore play vital parts in several biological
methods.
Colon cancer (COAD) is a widespread malignant tumor that transpires at the intersection
of the sigmoid colon and rectum. COAD disease, in 2018, was ranked as second in the list of

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mortality and fourth position to be for incidence list. As noted by Siegel et al., 2017, the survival
rate for colon cancer patients for 5-year is about 65%. Until presently, the histological
characteristic is just the prognostic pointer for COAD. As per the histological characteristic, it
gets challenging to agree on to earn adjuvant chemotherapy, which occurs after surgery.
Accordingly, it is essential to uncover the biomarkers for prognosis in the case of COAD. Dave
et al., 2019 verified three miRNAs, namely miR-103a-3p, miR-143-5p, miR-215, which worked
as prognostic markers for COAD in sufferers. Later it was reported by Bobowicz et al., 2016 that
five other markers, which are miR-1296, miR-135b, miR-539, miR-572, miR-185, consist of
predictive values for colon cancer.
Later, Maierthaler et al., 2017, exhibited that the miR-122 and miR-200 groups have
prognostic importance in COAD. Nonetheless, experimentally inferring the prognostic
importance of miRNAs is not just time-wasting but also expensive. Thus, many computational
techniques have been formulated in bioinformatics, for instance, circRNA-disease association,
drug-side effect, lncRNA-miRNA interaction, and lncRNA-protein interaction predictions.
Accordingly, there is a severe desire to develop beneficial bioinformatics analysis to specify the
molecular tools associated with COAD from expanding experimental and clinical data.
According to Zhu, et al., (2019), one of the databases known as TCGA is an extensive
database that comprises epigenomic and systematic clinical information from huge specimens for
each type of cancer. The collected information by TCGA involves details regarding miRNAs
expression data, exon expression data, copy number segments, phenotype, DNA methylation,
and many more. Gene chips are used on a high output examination, which can distinguish
millions of gene expressions within one test. Accordingly, the TCGA database can enable
scientists to attain a large quantity of genetic evidence regarding types of cancer within a brief
time and empower modern targets for treatments and diagnosis and treatment of severe types of
cancer. Various lines of information suggest that few adaptations in miRNAs, like
overexpression, ectopia, and mutation, result in severe pathological substitutions. Such
consequences are attributable to the translation of messenger RNA into translatory proteins
governed by miRNA. Moreover, several sorts of miRNA exist and have a specific expression

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level in different cancers. Recently, Xu et al. (2016) indicated that four miRNAs were
considerably correlated with the overall survival for patients with COAD patients. Nevertheless,
few studies just analyzed the connection between the COAD patient survival and the expression
of miRNAs. It did not investigate the part for the target genes for miRNAs in COAD. Thus, the
miRNA data and mRNA of COAD from TCGA should be evaluated together to distinguish
current biomarkers for study. Since miRNA repression is a familiar characteristic of CRC
tumors, most researchers are determined to know the available position of down regulated
miRNAs in the pathogenesis of CRC; therefore, most subsequent studies are concentrating on
miRNAs that are down regulated in CRC tumors.

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