In mammals, the majority of products of gene expression are non-coding ribonucleotide sequences. They include short and long RNA molecules with sizes ranging of tens to hundreds of nucleotides. Among them, the molecules with more than 200 nucleotides are called long non-coding RNAs or lncRNAs. While LncRNAs functions depend on their unique molecular structures, they play important roles in regulating gene expression at epigenetic, transcriptional and post-transcriptional levels. Interacting with other biological molecules such as DNA, RNA and protein, LncRNAs have been found to play important roles in normal cell physiological activities. Activation of transcription factors, guidance of ribonucleoprotein complexes, aggregation of partner proteins, regulation of alternative processing, cooperation in chromatin remodeling, facilitation of genomic imprinting, maintaining of multipotential state and control of nucleus/cytoplasm traffic are some of crucial approaches Implemented by LncRNAs. Modern technologies have been developed to identify lncRNA molecules, and many relevant databases have been designated to facilitate research and academic exchange of data concerning them. In this review article, signification, identification, classification, biological evolution, genomic position, configuration, expression, localization and remarkable functions of LncRNAs have been discussed.

In early 2012, the world of science saw a fascinating discovery called circular RNA as a transcription product of thousands of genes in mice and humans. These circular RNAs have recently been grouped as the encoding RNA in an independent group that their remarkable difference with other RNAs is that these RNAs are not linear, in which two ends connect with a covalent connection creating a loop-shaped structure. These molecules play a role in regulating the expression of genes in mammals, and also, unlike other RNAs, they are very stable. These RNAs are created quite differently by means of a mechanism called back splicing. In this mechanism, in a molecule of RNA, axons or lariat-shaped introns are bonded at two ends of '3 and '5 with a covalent bond, creating circular structures that, unlike other common RNAs in the cytoplasm, are very stable. The circular RNAs act as mRNA sponge and form a set of RNA and protein that engage in transcription regulation by binding to RNA-related proteins. This suggests that these RNAs regulate gene expression at the transcriptional level and then they react by miRNAs. In fact, those circular RNAs that play a role in regulating the function of miRNAs also play a role in the onset and progression of the cancer. In tumor tissues, circular RNAs are reduced in comparison with normal tissues, and this may be for reasons like error occurs in the back splicing mechanism, degradation by unregulated miRNAs or increased cell proliferation. Recently circular RNAs have been identified in exosomic studies and in the movement of chromosomes in cancers, and there is found that the incorrect and abnormal attachment of these types of RNAs is related to drug resistance. Although it is thought that circular RNAs are non-coding, some of them are translated into functional proteins. So far, there are many unknowns about circular RNAs and the mechanism for regulating the expression of genes by them, but there is a lot of evidence to convince us that they will soon be used as biomarkers to diagnose diseases and therapeutic targets for cancers.

Background: A group of cells that divide more than normal tissue is called a cancerous tumor. In most cases, colon cancer which are lumps of flesh originating from the inner lining of the colon staining from intestinal polyps. Elucidating the regulatory relationships between mRNA and lncRNA can contribute to the regulation pattern of gene expression in malignant colorectal cancer. In this study, the integration of weight gene co-expression network in malignant tumor was investigated by analyzing expression data from samples of normal and cancer patients. Materials and methods: The data used in this article included lncRNA and mRNA exosomal sequences extracted from Exorbase and GEO database. The weighted gene co-expression network was used to group genes and find gene groups that have a significant correlation. Results: In this study, the pathological importance of the groups was classified using the level of expression of the groups. Between the groups, the green group had the most correlation and significance, and for this reason, it is assumed that they have the top impact on the progression of cancer. Conclusion: Considering the key genes HSPA1B, PPP2R3B and HSPA1A suggested in this study by comparing healthy and sick people and identifying the difference in gene expression profile, a suitable biomarker can be identified to detect people with colorectal cancer.

MicroRNA (miRNA) is one of the non-codingRNA(ncRNA) molecules with 21-25-nucleotide length, playing an important role in gene control by transcriptional gene regulation, chromatin remodeling, genetic imprinting, and translation initiation. The deregulation of ncRNA can lead to several hematopoietic malignancies such as acute lymphoblastic leukemia (ALL). The study aimed to drawthe crucial features of miRNA in the pathogenesis of ALL. The findings showed that miRNA expression changes in ALL are typical and involve several signaling pathways. The variations in miRNA gene expression can lead to the incomplete expression of oncoprotein or tumor suppressor gene (TSG). It seems that ncRNAs play pivotal roles in the ALL pathogenesis. However, ncRNAs might be interested as potential diagnostic and prognostic biomarkers in ALL.

For 50 years, the term gene is synonymous with regions of the genome gene that coding by mRNAs and translate to protein. nonetheless, Genome wide Recent studies have revealed that regulating gene expression through degradation or translational inhibition of their point mRNAs and thus attend in a wide variety of physiological and pathological cellular processes including: development, cell proliferation, differentiation, and apoptosis pathways by thousands of regulatory non coding RNA such as lncRNAs and microRNAs. According to a recent survey, it is known this RNAs have vital role in regulation cellular pathways at transcriptional, posttranscriptional and epigenetic levels. These noncoding genes are often aberrantly expressed in a variety of human cancers. However, the biological functions of most ncRNAs remain largely in doubt. In this review, we proved that a remarkable part of the genetic etiology of cancer is imposed by noncoding regulatory sequences. The purpose of this review is aimed to give an outlook of using of noncoding RNA as diagnostic markers and therapeutic targets. These observations emphasized that the recognition of coding genes and Research continued evolution and function of non-coding RNAs for a comprehensive understanding human complex diseases like cancer are essential.

Gastric cancer has become the leading type of cancer on an international scale, with metastatic cancer being the leading cause of mortality associated with this illness. Consequently, methods for early detection have been established, mainly through the use of non-invasive biomarkers present in different bodily fluids. Exosomes are distinct extracellular vehicles that transport cellular signals over long distances via diverse contents. They may be readily seen in bodily fluids due to their secretion by gastric cancer cells or cells in the gastric cancer-tumor microenvironment. Given this context, multiple biological and functional features of human tumors, especially gastric cancer, are intricately connected to exosomal non-coding RNAs (ncRNAs). Exosomal microRNAs play a crucial role in several stages of gastric cancer progression, facilitating the transfer of genetic information between cancer cells and other cells. This process regulates tumor angiogenesis, growth, metastasis, immunological responses, and medication resistance. They engage with several regulatory complexes that have different enzymatic activities. These complexes then alter the chromatin landscapes, including changes to nucleosomes, DNA methylation, and alterations to histones. This research delves into the essential regulatory mechanisms of exosomes in gastric cancer. Furthermore, the existing understanding of the functions of exosomal miRNAs in this context was evaluated, aiming to confirm their potential significance in identifying biomarkers, elucidating their roles in immune evasion and drug resistance, and ultimately evaluating therapeutic strategies.