Table 1.

Summary of miRNAs with known functional role in prostate cancer development and differential regulation in serum

MicroRNA	Function	Up/Downregulated in Serum	Relevant disease stage	Findings from existing studies
MiR-20a	Attenuates the pro-apoptotic action of E2F1-3 [16]	Upregulated [73, 78]	Localised and Metastatic	Distinguishes low/intermediate/high risk localised disease in combination with MiR-21, MiR-145, MiR-221 [78]
MiR-21	Inhibits apoptosis by targeting PDCD4 and PTEN [13, 14]. Can stimulate androgen-independent growth [37]	Upregulated [67, 69, 78]	Localised and Castrate-resistant	Improves diagnostic accuracy of PSA when combined with miR-141 [67] Distinguishes low/intermediate/high risk localised disease [78] Predictive of response to Docetaxel in castrate-resistant disease [50].
MiR-107	Granulin production [27]	Upregulated [73]	Localised	Upregulated in cancer vs. benign in serum microvesicles and urine [73]
MiR-125b	Suppresses p14(ARF) to modulate both p-53 dependent and independent apoptosis [9].	Upregulated [6]	Not elucidated	Distinguishes cancer from control [6]
MiR-143	Suppresses KRAS expression, inhibiting the MAPK pathway. Regulates EMT [29]	Upregulated [6]	Not elucidated	Distinguishes cancer from control [6]
Mir-141	Expression is controlled by androgens [41]. Limited to epithelium [6].	Upregulated [65, 67, 68, 73, 79]	Advanced/Metastatic disease	Distinguishes metastatic and localised disease [70, 76] Predicts biochemical recurrence following radical prostatectomy
MiR-145	Inhibits proliferation, migration, and invasion. Downregulates FSCN1. Inhibits EMT [34].	Downregulated [34, 78]	Localised and metastatic	Correlated with higher Gleason grade, PSA, and bony metastasis [34] Distinguishes low/intermediate/high risk localised disease [78]
MiR-221	Favours androgen-dependent growth. Downregulation may be linked to castrate-resistant state [43, 80].	Upregulated [67, 78] (although downregulation in tissue also reported [81]	Localised and metastatic	Distinguishes low/intermediate/high risk localised disease in combination with MiR-21, MiR-145, MiR-221 [54]
MiR-331-3p	Down-regulation increases ERBB-2 expression. Associated with androgen-independent growth [45]	Downregulated [73]	Not elucidated	Distinguishes cancer from control [73]
Mir-375	Stimulates proliferation via downregulation of Sec23a [82]	Upregulated [70, 73, 76]	Localised and metastatic	Distinguishes metastatic and localised disease [70, 73, 76]