BACKGROUND
Micro RNA’s (miRNAs) are small non- coding RNA’s which aid in cellular proliferation,
differentiation and apoptosis. They act as post transcriptional modifiers by binding to target
m RNA’s and deregulation of certain miRNA’s contributes to an increased expression of an
oncogene or tumour suppressor gene [1]. The possible ways of the mechanisms of miRNA
include Cap-40S initiation inhibition, 60S Ribosomal unit joining inhibition, elongation
inhibition, ribosome drop-off (premature termination),co-translational nascent protein
degradation, sequestration in P-bodies, mRNA decay (destabilisation), mRNA cleavage,
transcriptional inhibition through miRNA-mediated chromatin reorganization followed by
gene silencing [2]. Synergistic deregulation of multiple miRNAs and their protein coding
counterparts aids in tumorigenesis. MiRNA was originally discovered in Caenorhabditis
elegans, which is a free-living transparent nematode (roundworm), about 1 mm in length that
lives in temperate soil environments [3]. This present systematic review aims in evaluation of the role of miRNA21 as a potent diagnostic marker in tissue, serum and salivary samples of
Oral Potentially Malignant Disorders (OPMD) and Oral carcinoma.
MATERIALS AND METHOD
The search was done using the MeSH terms in the electronic data base namely PubMed data
base, Google scholar. A total of 82 articles were retrieved. On application of the inclusion
and exclusion criteria finally 16 studies were included in the Systematic Review.
RESULTS
A total of185 OPMD cases, 16 beningn neoplasms (7-Pleomorphic Adenomas, 9-Warthin’s
tumour), 270 malignant neoplasms, 117 healthy control cases, 20 disease control cases
(Recurrent Aphthous Stomatitis) were analysed for the expression of salivary, serum and
tissue miRNA21.After the analysis of all the included studies, thirteen studies were found in
tissue miRNA 21 of which eight studies were exclusively of tissue miRNA 21. Out of the
three studies for serum miRNA 21, only one study was found to be exclusively done on
serum miRNA 21. Likewise with three studies on salivary miRNA 21, only one study was
found to be exclusive for salivary miRNA 21. Quality assessment of the sixteen studies were
done using QUADAS 2 tool and further risk of bias chart and applicability concern were
obtained using Revman 5.3 software which proved that studies done by by, Cervigne et al
(2009), Danielsson et al (2012),Tseng et al (2017) , Wen HaoRen et al (2014) and Zahran et
al (2015) had low risk of bias while studies done by Cinpolat et al(2017), Hung et al(2016),
Volker Gassling et al (2017), Wang et al (2015) had moderate risk of bias. Studies done by
Coutinho-Camillo et al (2015), Gao et al (2017) and another study by Wen HaoRen et al
(2014) were unclear in their risk of bias and applicability concern. Studies done by Elisabeth
Nylander et al (2012), Zhu et al (2015), Patricia et al (2010), Zheng et al (2016) had high risk
of bias.
CONCLUSION
MiRNA 21 mainly targets the tumour suppressor genes and affects the process of
carcinogenesis. This systematic review proves that most of the included studies reveal an
upregulation of miRNA 21 in OPMD and OSCC and identification of miRNA 21 in saliva,
tissue and serum samples in OPMD can thus serve as an early diagnostic marker before it
progresses to carcinoma. Based on the statistical analysis of sensitivity, specificity, ROC it
was found that one study on tissue miRNA21 had ROC of 0.74,a study on serum miRNA 21
had ROC of 0.788 and study on salivary miRNA 21 revealed an ROC of 0.73.On taking into
account the ROC of the included studies it was found to be consistent with an average of
0.75 which indicates that serum, tissue and saliva all are consistent and they serve as optimal media for the identification of miRNA 21 and even other miRNAs in cases of
OPMD and OSCC. Since collection of saliva is a non invasive method compared to serum or
tissue, this systematic review proves that saliva is a surrogate marker for the identification of
miRNA 21 in OPMD and oral cancer.
Keywords: SalivarymiRNA 21, tissue miRNA 21, serum miRNA 21, Oral Potentially
Malignant Disorders
Publication date: 1/1/21
https://ijbpas.com/pdf/2021/January/MS_IJBPAS_2021_5287.pdf
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https://doi.org/10.31032/IJBPAS/2021/10.1.5287
