Functional Phenotype Of MicroRNA324-5p In Papillary Thyroid Carcinoma And Its Role In Cervical Lymph Node Metastasis Prediction On The Basis Of Ultrasound

ObjectiveUltrasound is the first choice of cervical lymph node metastasis(CLNM)detection which is crucial for therapeutic options of papillary thyroid cancer(PTC).However,its sensitivity is low,espesically in central compartment lymph node metastasis.MiR-324-5p is associated with the migration and invasion of different kinds of cancer.The aim of this study was to validate the expression and function of miR-324-5p in PTC and evaluate its role in predicting CLNM on the basis of ultrasound.MethodsQuantitative real-time polymerase chain reaction was performed for miR-324-5p detection and its correlation with clinicopathological and sonographic finding was analyzed.Factors relating to CLNM were also studied.MiR-324-5p expression was up or down regulated in KTC1 cell line by transfection,and its impact on tumor cell growth and metastasis was tested.Results1、41 subjects were categorized into CLNM(-)and CLNM(+)groups according to the pathological finding.MiR-324-5p was significantly overexpressed in CLNM(+)group(P=0.026)and patients with stage III-IV(P=0.030).The optimal cut-off value of miR-324-5p to distinguish CLNM was 0.59.Subgroup analysis revealed that subjects harbouring ‘US-CLNM(+)or miR-324-5p>0.59’ reached the highest accuracy of 78.05% and the most promising NPV of 100% with PPV of 71.88%.Nine CLNM cases missed diagnosed by US were all N1 a subjects and were all distinguished with the help of miR-324–5p.2、KTC1 was one kind of PTC cell line with low aggressivity.Upregulating miR-324-5p expression in KTC1 can inhibit apoptosis,increase cell proliferative indices and promote tumor cell proliferation,invasion and migration.3、The relative expression of miR-324-5p was not statistically different between CLNM(-)and CLNM(+)group in 143 FNA lavage fluid samples.Age was an independent protective factor of CLNM.Multifocality,TNM late stage,increasing transverse diameter of thyroid nodule,ultrasonic suspicious lymph nodes were independent risk factors of CLNM.4、In 66 unifocal intrathyroidal PTMC,including 4 subjects with late stage,miR-324-5p was significantly overexpressed in CLNM(+)group compared with CLNM(-)group(P=0.009).Setting 2.01 as the cutoff value in CLNM prediction,the sensitivity,specificity and accuracy was 58.33%,94.44% and 87.88% respectively.Six out of nine CLNM subjects missed diagnosed by ultrasound were identified by means of miR-324-5p>2.01.ConclusionsAge was an independent protective factor of CLNM.Multifocality,TNM late stage,increasing transverse diameter of thyroid nodule,ultrasonic suspicious lymph nodes were independent risk factors of CLNM.Upregulating miR-324-5p expression in KTC1 can promote tumor cell growth,invasion and migration.Most CLNM in unifocal intrathyroidal PTMC can be predicted by miR-324-5p detection in FNA lavage fluid,which made up for the deficiency of conventional ultrasound to some extent.