Table 4.

Studies on clinical utility of exosomal mRNAs, lncRNAs and circRNAs as biomarkers in lung cancer.

Molecule	Sample	Number of Subjects	Isolation Methods	Characterization Methods	Utility	Comments	Authors
TP63, KRT5, CEACAM6 and SFTPB mRNAs	Serum	54 AC + 16 SCC	Ultracentrifugation	TEM/NTA/WB	Histological classification	17 miRNAs to be analyzed were selected previously from TCGA database as differentially expressed between AC and SCC. ACTB and SLC25A6 were used as internal references	Cao et al. [136]
eIF4E RNA	Serum	99 NSCLC + 40 C	Precipitation	TEM/NTA/WB	Diagnosis Prognosis: stage, distant metastases, OS and PFS	eIF4E data extracted from TCGA database	Dong et al. [137]
PD-L1 (1) and IFN-γ (1,2) mRNA	EDTA Plasma	38 NSCLC	Membrane affinity spin columns	-	(1) Response to treatment (2) PFS	Quantification by ddPCR with ACTB as internal control	Del Re et al. [138]
MALAT-1	Serum	77 NSCLC + 30 C	Precipitation	TEM/NTA/WB	Diagnosis Prognosis (Lymph node metastasis, TNM stage)	Quantification by RT-PCR. GAPDH was used for normalization	Zhang et al. [90]
linc01125	Serum	277 NSCLC + 187 C + 5 P + 59 T + 58 COPD	Precipitation	-	Diagnosis Prognosis (stage, OS)	RNA-Seq for lncRNA profile and subsequent quantification of linc01125 by RT-PCR with spiked in controls	Xian et al. [139]
FECR	Serum	35 with limited SCLC and 26 with extensive SCLC +55 C	Affinity Chromatography	TEM/WB	Diagnosis Prognosis (survival) Response to chemotherapy	RT-PCR with β-actin as control	Li et al. [140]
circ_0014235 and circ_0025580	Plasma	30 SCC + 30 C	Precipitation	-	Diagnosis Prognosis (TNM stage and tumor size)	circRNA sequencing and confirmation with RT-PCR with GAPDH as internal control	Wang et al. [141]
circRNA_0056616	EDTA plasma	90 AC (42 with lymph node metastasis and 48 without)	Precipitation	TEM/WB	Lymph node metastasis predictor	RT-PCR. Normalization as Wang’s methods	He et al. [142]
circSATB2	Serum	83 NSCLC + 95 C	Ultracentrifugation	TEM/NTA/WB	Diagnosis Prognosis (metastasis detection)	RT-PCR. GAPDH and U6 were used as internal references and cel-miR-39 as an external reference	Zhang et al. [143]
circ_0047921, and circ_0007761 (1) circ_0056285 (1,2)	Serum	Screening set: 30 NSCLC + 45 C Training set: 120 NSCLC + 165 C Validation set 1: 62 NSCLC + 95 C Validation set 2: 63 NSCL + 58 COPD + 46 T	Precipitation	TEM/NTA/WB/FC	(1) Diagnosis (including early stage) (2) Prognosis: state of progression and lymph-node metastases	1701 circRNAs initially identified by RNA-seq, 17 of them were differentially expressed and 8 of them were validated by RT-PCR with GAPDH and ACTB as spiked-in controls	Xian et al. [144]

Abbreviations: AC: adenocarcinoma; C: controls; circRNA: circular RNA; COPD: chronic obstructive pulmonary disease; ddPCR: droplet digital PCR; EV: extracellular vesicles; FC: flow cytometry; LC: lung cancer; miRNA: microRNA; NSCLC: non-small cell lung cancer; NTA: nanoparticle tracking analysis; OS: overall survival; P: pneumonia; PFS: progression-free survival; RT-PCR: real-time polymerase chain reaction; SCC: squamous carcinoma; SCLC: small cell lung cancer; T: tuberculosis; TCGA: The Cancer Genome Atlas; TEM: transmission electron microscopy; TNM: tumor-node-metastasis; WB: Western blot.