Abstract: Background and Aim: Lung cancer (LC) is a major cancer killer worldwide, and 5-yr
survival is extremely poor (≤15%), accentuating the need for more effective diagnostic and therapeutic
strategies. Studies have shown cell-free microRNAs (miRNAs) circulating in the serum and plasma
with specific expression in cancer, indicating the potential of using miRNAs as biomarkers for
cancer diagnosis and therapy. This study aimed to identify differentially-expressed two miRNAs in
the plasma of non-small cell lung cancer (NSCLC) patients that might be a clinically useful tool for
lung cancer early detection. miRNA-21 is one of the most abundant oncomirs. miRNA-23a functions
as an oncogene in several human cancers, however, its clinical value has not been investigated in
NSCLC.
Materials and Methods: A case-control study was conducted in Assiut University Hospital, Egypt,
from 2017 to 2018. Plasma samples were obtained from 45 NSCLC patients. The expression level of
miR-21 and miRNA-23a was detected by qRT-PCR and compared to 40 healthy control subjects.
The relation between both miRNAs and clinicopathological parameters was evaluated.
Results: The expression level of miR-21 and miRNA-23a was significantly up-regulated (36.9 ± 18.7
vs. 1.12 ± 0.84 and 24.7 ± 19.09 vs. 1.16 ± 0.45) in NSCLC compared to matched controls
(P<0.0001each). There was a significant difference in the level of plasma miRNA-21 and miRNA-
23a expression between the different grades of the disease (P = 0.032 and P = 0.001, respectively).
The plasma miRNA-21 and miRNA-23a levels in the lung cancer patients with distant metastasis (n
= 20) were significantly higher than those in the patients without metastasis (n = 25) (P<0.0001
each), the expression of miR-21 and miRNA-23a was significantly associated with tumor size (P =
0.001, P = 0.0001, respectively), but not significantly related to lymph node metastasis (P = 0.687
and 0.696, respectively). A positive correlation was observed between miRNA-21 and miRNA-23a (r
= 0.784, P<0.01), There was no significant difference in the plasma miRNA-21 and miRNA-23a levels
in the lung cancer patients with different histopathological types.
Conclusion: miR-21 and miR-23a might play an oncogenic role in LC and is a poor prognostic factor.
Switching off miRNA-21 and miRNA-23a may improve the treatment of LC. Our results must
be verified by large-scale prospective studies with standardized methodology.