MIR22HG (MIR22 host gene), also known as C17orf91, MGC14376, MIRN22, hsa-mir-22, and miR-22 is a human gene that encodes a noncoding RNA (ncRNA).This RNA molecule is not translated into a protein but nonetheless may have important functions.
MIR22HG ncRNA is greater than 200 nucleotides in length and therefore informally classified as a long non-coding RNA, i.e. lncRNA. The MIR22HG gene is located at band 13.3 on the short (or "p") arm of chromosome 17. It is expressed in each of the 27 human tissues tested.
Function
Many lncRNAs regulate diverse processes including cellular metabolism, proliferation, movement, differentiation (i.e. change of a cell from one type to another, usually more mature, cell type), apoptosis (i.e. programmed cell death), and the expression of various genes through chromatin remodeling, genomic imprinting, modulating the actions of other RNAs, and various other ways. The normal actions and functions of the MIR22HG gene are complex and have not been fully elucidated, but its primary function may be as a tumor suppressor gene. It is involved in the regulation of several signaling pathways including Wnt/β-catenin, epithelial-mesenchymal transition (EMT), notch, and STAT3.
Clinical significance
When overexpressed, it acts as a tumor suppressor gene in many cancer types but in a few cancer types it acts as an oncogene, i.e. a tumor promotor gene: MIR22HG gene's impact on various cancers is strictly dependent on the type of cancer in which it operates.
The roles or the MIR22HG gene in cancers have generally been evaluated by: a) next-generation sequencing to quantify the levels of MIR22HG RNA in cancer samples, samples of nearby normal tissue of the same type as the cancer, and cultured cancer cells of the same type as the cancers; b) comparing MIR22HG lncRNA levels in patients with the same cancer to the severity (e.g. aggressiveness, recurrence rate, and survival rate) of their cancers; c) determining the potential mechanisms for the MIR22HG lncRNA's actions, generally by defining the effects of varying the levels of this lncRNA on various cancer-promoting or cancer-inhibiting cell signaling pathways in cultured cancer cells; and d) determining the activity of these cell signaling pathways in cancer tissues. These studies are important because they established the levels of MIR22HG lncRNA as prognosis indicators and suggest that this lncRNA and the implicated cancerous signaling pathways are therapeutic targets for treating these cancers.
Tumor-suppression
Some of the cancer types that have been associated with the MIR22HG gene and its lncRNA product acting to suppress the cancer are: