Genetic expressions alteration affect on lateral neck node metastasis of thyroid papillary microcarcinoma

Abstract

Background : Papillary thyroid cancer has a mild biological behavior, and especially the papillary thyroid microcarcinoma(PTMC) shows a very favorable prognosis. Cervical lymph node metastasis of PTMC is the most significant prognostic factor for locoregional recurrences. In this study, we compared gene expression patterns of PTMC associated with lateral neck-node metastasis versus PTMC lacking such metastasis, and we validated the functional evidences of over- or under-expressed genes sets that correlated with early extensive lymph-node metastasis.Methods and materialsWe performed oligonucleotide microarray analysis using Illumina HumanHT-12 v4.0 Expression Beadchip in eight PTMCs and paired normal thyroid tissues. Of these, three were PTMC without cervical lymph-node metastases (N0), and the others were PTMC with lateral neck-node metastasis (N1b) at initial diagnosis. Statistical significance of the differentially expressed genes was determined using independent T-test with two-sided p<0.05 and median-fold change cut-off of >1.5. Quantitative real-time PCR, Western blot analysis, and immunohistochemistry were used to confirm the microarray data. ResultsMicroarray analyses identified 146 probes corresponding to 131 genes whose expression differed significantly between the two PTMC groups. Significant upregulation was seen in 107 genes, and 24 genes showed downregulation in N1b PTMC when compared with N0. Differential gene expression analyzed by gene ontology profile implicated biological processes of signaling, multicellular organism processes, responses to stimuli, developmental processes, cell proliferation, death, locomotion, and biological regulation. Genes that are related to epithelial-to-mesenchymal transition (EMT) and stem-cell markers were significantly upregulated in N1b PTMCs. Quantitative real-time PCR of expression of genes including IL1RL1, ALDH1A3, FGFBP1, TM4SF1, PROM1, CAV1, CCL18, TGIF1, SMAD3, and CDCP1 confirmed the data from microarray hybridization. Results of Western blot analysis confirmed that expression of CAV1, TM4SF1, and IL1RL1 was increased in N1b relative to N0 PTMCs. Immunohistochemical studies indicated that ALDH1A3 and CAV1 were more frequently expressed in N1b than N0 PTMCs.ConclusionsGenes that play a role in EMT and thyroid cancer stem-cell-like properties are upregulated in early extensive lymphatic spread of PTMC.