The Correlative Research Between BRAF^V600EMutation And MiRNAs Expression In Papillary Thyroid Carcinoma

Objective:Papillary thyroid carcinoma (PTC) is the most common type of thyroid carcinoma. Both BRAFv600E mutation and miRNAs dysregulation play a critical regulatory role in PTC. In the study, we examined the status of BRAF and the expression of miR-146b, miR-221and miR-222in PTC, in order to analyse their relationship with clinicopathological features, identify a possible association between them and evaluate the feasibility of BRAF mutation and miRNAs expression as a potential diagnostic tool in PTCMethods:All specimens were obtained at Tianjin cancer hospital operating room by core needle biopsy and open biopsy from May2013to August2013. There are49cases of PTCs and17paired normal controls. BRAFV600E mutation was detected by polymerase chain reaction (PCR) and DNA sequencing assays. miR-146b, miR-221and miR-222expression was quantified by real-time polymerase chain reaction (RT-PCR) with TaqMan(?) MiRNA Assay. Clinical data was retrospectively reviewed and evaluated with BRAF mutation and miRNAs dysregulation by SPSS19.0statistical software. P<0.05was considered statistically significant.Results:1. The presence of BRAFV600E mutation was only found in PTCs with the mutation ratio of57.1%and not detected in normal thyroid tissue. Compared with BRAF wild type, BRAFV600E mutation of PTCs presented higher rate of extrathyroidal invasion and lymph node metastasis, which both in central and lateral lymph node. But statistical data did not show any correlation between BRAFV600E mutation and other clinicopathologic parameters in PTCs (P>0.05)2. There was a significant difference at the expression levels of miR-146b, miR-221and miR-222between49PTCs and17paired normal controls (P＜0.05) The median of the three miRNAs relative quantification2-ΔΔCT are16.2,11.2and7.1. Statistical data did not show any correlation between miR-146b expression and the clinicopathologic parameters of PTCs. The expression of miR-221and miR-222were significantly higher in the patients group with extrathyroidal invasion. Only miR-221expression has a significant difference among lymph node metastasis and risk of recurrence. There were no other associations between the expression of miR-221and miR-222with other clinicopathological parameters.The three miRNAs expression levels in28BRAFV600E mutation PTCs were significantly higher than21PTCs without BRAF mutation (P＜0.05).3. Detection of BRAFv600E mutation had a sensitivity (Se) of57.1%, specificity (Sp) of100%, positive predictive value (PPV) of100%, negative predictive value (NPV) of70.8%and overall accuracy of89.4%when applied to the validation set. The expression levels of all three miRNAs have the ability to distinguish PTCs and normal controls. miR-146b identified the tumor for89.4%Se,100%Sp,70.8%NPV,100%PPV, and89.4%accuracy. miR-221identified the tumor for89.8%Se,100%Sp,77.3%NPV,100%PPV, and92.4%accuracy. miR-222identified the tumor for87.8%Se,100%Sp,73.9%NPV,100%PPV, and90.9%accuracy.Conclusion:1. The presence of BRAFv600E mutation was only found in PTCs. BRAFV600E mutation of PTCs presented higher rate of extrathyroidal invasion and lymph node metastasis, which means BRAFV600E mutation may be related to the high invasive ability of the tumor.2. There was a significant difference at the expression levels of miR-146b, miR-221and miR-222between PTCs and normal controls. Statistical data did not show any correlation between miR-146b expression and the clinicopathologic parameters of PTCs. miR-221expression has a significant difference among extrathyroidal invasion, lymph node metastasis and risk of recurrence. The expression of miR-222was higher in the patients group with extrathyroidal invasion. Three miRNAs expression levels were significantly higher in PTC patients with BRAFV600E mutation. Expression of miRNAs in PTC is associated with BRAF mutation and clinicopathological features. 3. Detection of BRAFV600E mutation had a lower Se, but had a higher Sp. The expression levels of miR-146b, miR-221and miR-222have the ability to distinguish PTCs and normal controls. BRAFV600E mutation and miRNAs expression have certain clinical application values.