Table 4.

Representative circulating miRNAs reported to predict response to chemotherapy and/or surgery

Cancer type	miRNA dysregulation associated with poor response	Sample type	Significance	Reference
Breast	↑ miR-125b	Serum	Increased in patiens not responding to neoadjuvant chemotherapy	[91]
Breast	↑ miR-210	Plasma	Lower miR-210 plasma levels are associated with	[92]
			- complete response to trastuzumab (HER-2 targeted monoclonal antibody)
			- surgical removal of tumor
			- lack of tumor metastasis to lymph nodes
Colorectal (CRC)	↑ miR17-3p	Plasma	- Elevated in both CRC tissue and plasma	[93]
			- Lower level detected in post-operative plasma is associated with responsiveness to surgery
Colorectal (CRC)	↑ miR-29a	Serum	- Elevated in both CRC tissue and plasma	[93]
			- Help differentiate CRC from gastric cancer, inflammatory bowel disease and no tumor controls
			- Lower level detected in post-operative plasma is associated with responsiveness to surgery
Colorectal (CRC)	↑ miR-27b, miR-148a, miR-326	Plasma	Elevated in patients with metastatic CRC not responding to 5-fluouracil and oxaliplatin-based chemotherapy	[94]
Lung	↑ miR-21	Plasma	Increased; associated with resistance to platinum-based chemotherapy	[95]
Non-Hodgkin’s lymphoma (NHL)	↓ miR-92a	Plasma	- Remarkably lower in NHL patients (< 5%) than in healthy subjects	[96]
			- The very low plasma level of miR-92a increased in complete response phase but became lower again in the relapse phase
Prostate	↑ Prostate cancer secretary (PCS)-miRNAs	Plasma/serum	- It is not clear whether circulating miRNAs are actively released by live cancer cells or derived from dead cancer cells.	[97]
			- In vitro cytotoxic treatment of DU-145 cells enhanced the release of exosomes-associated PCS-miRNAs, with the exception of miR-485-3p, which is retained by surviving cancer cells.
			- The intracellular retention of miR-485-3p was shown to downregulate the transcriptional repressor NF-Y, thus allowing the overexpression of a few drug resistance genes (including TOP2A, MDR1, and cyclin B2 pro-survival genes)
Prostate	↑ miR-21	Serum	- Increased in hormone-refractory prostate cancer	[98]
			- Associated with resistance to docetaxel-based chemotherapy
Advanced renal cell carcinoma	↑ miR-192	Peripheral blood samples	- Models predicting poor and prolonged response to sunitinib were constructed	[99]
	↑ miR-193a-3p
			- Ontology analyses revealed relevance to cancer-related pathways (angiogenesis and apoptosis)
			- miRNA expression signatures may be used to identify patients who may benefit the most from 1st line therapy with sunitinib