Table 2.

miRNAs and associated targets/regulators involved in BCa chemoresistance.

miRNA	Target/Regulator	Function	Reference
MiR-7-5p	ATG7	Upregulation of miR-7-5p inhibited invasive characteristics. Promotes chemosensitivity.	[36]
MiR-21	PTEN	Promotes chemoresistance to doxorubicin and proliferation in transitional cell carcinoma; inhibits doxorubicin-induced apoptosis.	[37]
MiR-22-3p	NET1	MiR-22-3p promotes chemoresistance. More cell viability, colony formation, and less apoptosis with upregulation of miR-22-3p via mimic.	[38]
MiR-23a	SFRP1 protein and Wnt signaling	Linked to chemoradiation response.	[39]
MiR-27a	SFRP1 protein and Wnt signaling, RUNX-1	Linked to chemoradiation response [39]. Rs11671784 SNP (wherein A is replaced with G) results in reduced chemosensitivity [40].	[39,40]
MiR-30a-3p	MMP2, MMP9	Combination of cisplatin and miR-30a-3p resulted in improved apoptosis and reduced cell viability. Upregulation of miR-30a-3p via mimic lessened migration and invasion.	[41]
MiR-31	ITGA5	MiR-31 promotes chemosensitivity to mitomycin-C and upregulation inhibits proliferation, migration, and invasion. Downregulation associated with higher risk of recurrence in noninvasive UBC.	[42]
MiR-34a	TCF1, LEF1, Cdk6, SRT-1 (sirtuin), CD44	Downregulated in BCa; promotes chemosensitivity to epirubicin [43] and to cisplatin [44,45]. Higher expression of miR-34a represses metastatic characteristics [43,45].	[43,44,45]
MiR-93	LASS2 (but no direct binding)	MiR-93 promotes chemoresistance.	[46]
MiR-98	LASS2	Expressed at higher levels in BCa. Upregulation via mimic resulted in increased proliferation, greater cisplatin and doxorubicin resistance, and repression of apoptosis.	[47]
MiR-101	COX2	MiR-101 promotes chemosensitivity to cisplatin.	[48]
MiR-101-3p	EZH2, affects MRP1 expression	MiR-101-3p promotes chemosensitivity.	[49]
MiR-129-5p	Wnt5a	Expression of miR-129-5p promotes response to gemcitabine.	[50]
MiR-130b	CYLD	Involved in promoting chemoresistance.	[51]
MiR-143	IGF-1R	MiR-143 promotes chemosensitivity. Upregulation of IGF-1R linked to reduced survival and recurrence.	[52]
MiR-193a-3p	LOXL4, HOXC9, PSEN1, ING5	MiR-193a-3p promotes chemoresistance (oxidative stress pathway) [53,54]. MiR-193a-3p reported to target PSEN1 gene and affect DNA damage response [55]. Interaction with ING5 also occurs through DNA damage response pathway [56].	[53,54,55,56]
MiR-193a-5p	AL-2α	MiR-193a-5p is involved in chemoresistance. Upregulation of miR-193a-5p linked to increased migration and resistance to cisplatin.	[57]
MiR-200b	IGFBP3, ICAM1, TNFSD10	MiR-200b promotes chemosensitivity. More broadly, miR-200 family members (miR-200b, miR-200a, and miR-429) were downregulated in cisplatin-resistant cell lines.	[58]
MiR-214	Netrin-1	Tumor suppressor activity; miR-214 upregulation resulted in reduced colony formation and invasion. MiR-214 promotes chemosensitivity.	[59]
MiR-218	Glut1	MiR-218 promotes chemosensitivity to cisplatin.	[60]
MiR-222	PPP2R2A	MiR-222 is implicated in chemoresistance. Acts through AKT/mTOR and autophagy pathways.	[61]
MiR-325	HAX-1	MiR-325 promotes chemosensitivity.	[62]
MiR-424	UNC5B and SIRT4	Promotes cisplatin resistance via downregulation of UNC5B and SIRT4.	[63]
MiR-455-5p	Regulated by HOXA-As3	Promotes sensitivity to cisplatin, reduces proliferation, and promotes apoptosis.	[64]
MiR-486-5p	Gene expression changes observed in caspase-9, caspase03, P53, SIRT1, OLFM4, SMAD2, Bcl-2, ROCK, CD44, MMP9	MiR-486-5p functions as tumor suppressor and promotes chemosensitivity.	[65]
miR-3682-3p	Regulated by BMI1 and regulates ABCB1	BMI1 inhibits miR-3682-3p transcription to induce chemoresistance. Elevated BMI1 is also associated with poorer RFS.	[66]