mir-22

In molecular biology mir-22 microRNA is a short RNA molecule. MicroRNAs are an abundant class of molecules, approximately 22 nucleotides in length, which can post-transcriptionally regulate gene expression by binding to the 3' UTR of mRNAs expressed in a cell.

mir-22
miR-22 microRNA secondary structure and sequence conservation
Identifiers
Symbolmir-22
RfamRF00653
miRBase familyMIPF0000053
NCBI Gene407004
HGNC31599
OMIM612077
Other data
RNA typemicroRNA
Domain(s)Eukaryota; Euteleostomi
PDB structuresPDBe

Origins

Mir-22 was originally identified in HeLa cells (an immortal cell line derived from cervical cancer cells), but was later found to be ubiquitously expressed in various tissues.[1] The gene encoding miR-22 is found on the short arm of chromosome 17, in a minimal loss of heterozygosity region. It is highly conserved across many vertebrate species, including chimp, mouse, rat, dog and horse. This level of conservation suggests functional importance. MiR-22 was previously identified as having a role in erythrocyte maturation.[2]

Role in cancer

The deregulation of many miRNAs has been shown to have a role in oncogenesis. Mir-22 was found to be over-expressed in prostate cancer but down-regulated in breast cancer, cholangiocarcinoma, multiple myeloma and hepatocellular carcinoma.[3] Mir-22 expression was associated with survival in multiple breast cancer datasets.[4]

Targets

Specifically, miR-22 can function as a tumour suppressor. One known target is histone deacetylase 4 (HDAC4), which is known to have a critical role in cancer development. Mir-22 also targets Myc Binding Protein (MYCBP).[5] This prevents transcription of c-Myc target genes by silencing c-MYCBP. However, c-Myc also inhibits expression of miR-22 in a positive feedback loop. When this spirals out of control, it can cause uncontrolled cell proliferation.[6]

Possible therapy

Expression of miR-22 can be induced by adding 12-O-Tetradecanoylphorbol-13-acetate (TPA) to HL-60 cells (leukaemia cell line).[7] The enforced expression causes the growth of cancer cells to slow down. This means that miR-22 could be a potential target for cancer therapies.

See also

References
  1. Xiong J, Yu D, Wei N, Fu H, Cai T, Huang Y, Wu C, Zheng X, Du Q, Lin D, Liang Z (2010). "An estrogen receptor alpha suppressor, microRNA-22, is downregulated in estrogen receptor alpha-positive human breast cancer cell lines and clinical samples". FEBS J. 277 (7): 1684–94. doi:10.1111/j.1742-4658.2010.07594.x. PMID 20180843. S2CID 8495747.
  2. Choong ML, Yang HH, McNiece I (April 2007). "MicroRNA expression profiling during human cord blood-derived CD34 cell erythropoiesis". Exp. Hematol. 35 (4): 551–64. doi:10.1016/j.exphem.2006.12.002. PMID 17379065.
  3. Zhang J, Yang Y, Yang T, Liu Y, Li A, Fu S, Wu M, Pan Z, Zhou W (2010). "microRNA-22, downregulated in hepatocellular carcinoma and correlated with prognosis, suppresses cell proliferation and tumourigenicity". Br J Cancer. 103 (8): 1215–20. doi:10.1038/sj.bjc.6605895. PMC 2967065. PMID 20842113.
  4. Lánczky, András; Nagy, Ádám; Bottai, Giulia; Munkácsy, Gyöngyi; Szabó, András; Santarpia, Libero; Győrffy, Balázs (2016-12-01). "miRpower: a web-tool to validate survival-associated miRNAs utilizing expression data from 2178 breast cancer patients". Breast Cancer Research and Treatment. 160 (3): 439–446. doi:10.1007/s10549-016-4013-7. ISSN 1573-7217. PMID 27744485. S2CID 11165696.
  5. Xiong J, Du Q, Liang Z (2010). "Tumor-suppressive microRNA-22 inhibits the transcription of E-box-containing c-Myc target genes by silencing c-Myc binding protein". Oncogene. 29 (35): 4980–8. doi:10.1038/onc.2010.241. PMID 20562918.
  6. Cole MD, McMahon SB (May 1999). "The Myc oncoprotein: a critical evaluation of transactivation and target gene regulation". Oncogene. 18 (19): 2916–24. doi:10.1038/sj.onc.1202748. PMID 10378688.
  7. Ting Y, Medina DJ, Strair RK, Schaar DG (2010). "Differentiation-associated miR-22 represses Max expression and inhibits cell cycle progression". Biochem Biophys Res Commun. 394 (3): 606–11. doi:10.1016/j.bbrc.2010.03.030. PMID 20214878.

Further reading
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