Table 1.

Key microRNAs involved in cancer

MicroRNA	Function	Genomic location	Mechanism	Targets	Cancer type	Mouse models	Clinical application
miR-17-92 cluster	Oncogene	13q22	Amplification and transcriptional activation	BIM, PTEN, CDKN1A and PRKAA1	Lymphoma, lung, breast, stomach, colon and pancreatic cancer	Cooperates with MYC to produce lymphoma. Overexpression induces lymphoproliferative disease	Inhibition and detection
miR-155	Oncogene	21q21	Transcriptional activation	SHIP1 and CEBPB	Chronic lymphocytic leukaemia, lymphoma, lung, breast and colon cancer	Overexpression induces pre-B-cell lymphoma and leukaemia	Inhibition and detection
miR-21	Oncogene	17q23	Transcriptional activation	PTEN, PDCD4 and TPM1	Chronic lymphocytic leukaemia, acute myeloid leukaemia, glioblastoma, pancreatic, breast, lung, prostate, colon and stomach cancer	Overexpression induces lymphoma	Inhibition and detection
miR- 15a/16-1	Tumour suppressor	13q31	Deletion, mutation and transcriptional repression	BCL2 and MCL1	Chronic lymphocytic leukaemia, prostate cancer and pituitary adenomas	Deletion causes chronic lymphocytic leukaemia	Expression with mimics and viral vectors
let-7 family	Tumour suppressor	11 copies (multiple locations)	Transcriptional repression	KRAS, MYC and HMGA2	Lung, colon, stomach, ovarian and breast cancer	Overexpression suppresses lung cancer	Expression with mimics and viral vectors
miR-34 family	Tumour suppressor	1p36 and 11q23	Epigenetic silencing, transcriptional repression and deletion	CDK4, CDK6, MYC and MET	Colon, lung, breast, kidney, bladder cancer, neuroblastoma and melanoma	No published studies	Expression with mimics and viral vectors
miR-29 family	Oncogene	7q32 and 1q30	Transcriptional activation	ZFP36	Breast cancer and indolent chronic lymphocytic leukaemia	Overexpression induces chronic lymphocytic leukaemia	No published studies
	Tumour suppressor		Deletion and transcriptional repression	DNMTs	Acute myeloid leukaemia, aggressive chronic lymphocytic leukaemia and lung cancer		No published studies

BCL2, B-cell lymphoma protein-2; BIM, BCL-2-interactiing mediator of cell death; CDKN1A, cyclin-dependent kinase inhibitor 1A; CEBPB, CCAAT/enhancer binding protein β; HMGA2, high mobility group AT-hook 2; CDK4, cyclin-dependent kinase 4; CDK6, cyclin-dependent kinase 6; DNMT, DNA methyltransferase; MCL1, myeloid cell leukaemia sequence 1; PTEN, phosphatase and tensin homologue; PRKAA1, protein kinase, AMP-activated, alpha 1 catalytic subunit; PDCD4, programmed cell death 4; SHIP1, Src homology 2 domain-containing inositol 5-phosphatase 1; TPM1, tropomyosin 1; ZFP36, zinc finger protein 36.