Table 2.

MicroRNAs as oncogenes and tumor suppressors in brain tumors. Abbreviations: miRNA = microRNA; B‐CLL = B cell chronic lymphocytic leukemia; DLBCL = diffuse large B cell lymphoma.

MiRNA	Putative function	Deregulation in tumors	Molecular mechanism and regulation	Diagnostic and prognostic markers
Has_let‐7 family	Tumor suppressor	Let‐7 members generally display reduced expression in lung, breast, gastric, colon cancers and pituitary adenomas	Let‐7 overexpression represses cell proliferation and let‐7f promotes angiogenesis; Let‐7b is up‐regulated at the transcriptional level by MYCN in primary neuroblastoma	Let‐7a‐2 low expression correlates with poor survival in lung cancer patients; Loss of let‐7 expression identifies a less differentiated class of cancers
Hsa_miR‐16‐1 ‐15a cluster	Tumor suppressor	Reduced expression in CLL, DLBCLs, multiple myeloma, pituitary adenoma, prostate and pancreatic cancers	Exogenous restoration in leukemia cells induces apoptosis by directly targeting BCL2, while in solid cancer cells miR‐16 negatively regulates cellular growth and cell cycle progression by down‐regulating G0/G1 proteins (CDK6, CDC27, CARD10 and C10orf46)	MiR‐15a and miR‐16 discriminate between good and bad prognosis in CLL patients
Hsa_miR‐21	Oncogenic	Elevated levels in glioblastoma primary tumors and cell lines, in breast and cervical carcinomas, uterine leiomyosarcoma, and DLBCL	Controls cell proliferation and apoptosis by regulating BCL2 expression in breast cancer cells; MiR‐21 knockdown in glioblastoma cells increases apoptosis; Induces invasion, intravasation and metastasis by targeting PDCD4 in colorectal cancers. Regulated at the transcriptional level by STAT3	High expression is associated with longer relapse free survival in DLBCL
Hsa_miR‐181 family	Oncogenic	Overexpression in breast, pancreas, prostate cancers	Regulated at the transcriptional level by MYCN	Low expression in aggressive CLL with 11q deletions
Hsa_miR‐221‐222 cluster	Oncogenic	Highly expressed in CLL, thyroid papillary carcinoma and glioblastoma	Directly target p27 and promotes cancer cell proliferation; Positive transcriptional regulation of miR‐221 by MYCN in primary neuroblastoma	High expression of miR‐221 correlates with a bad prognosis in CLL patients

Gene names as in NCBI at http://www.ncbi.nlm.nih.gov/sites/entrez

MicroRNA name according to mirBASE at http://microrna.sanger.ac.uk/sequences/.