PTCSC3 Is Involved in Papillary Thyroid Carcinoma Development by Modulating S100A4 Gene Expression

Context: We previously showed that a long noncoding RNA gene, PTCSC3, located close to the variant rs944289 that predisposes to papillary thyroid carcinoma (PTC) might target the S100A4 gene. Objective: The aim was to investigate the impact of PTCSC3 on S100A4 expression and its role in cancer development. Design: S100A4 abundance was analyzed by quantitative PCR (qPCR) in unaffected and tumor tissue from n = 73 PTC patients. The expression of PTCSC3 and S100A4 was studied in BCPAP and TPC-1 cell lines with forced expression of PTCSC3 by qPCR. Expression of S100A4 target genes (VEGF and MMP-9) was studied in the BCPAP cell line with forced expression of PTCSC3 by qPCR, reverse transcriptase PCR, and Western blot. The impact of PTCSC3 on BCPAP motility and invasiveness was analyzed by the Transwell and Matrigel assays, respectively. Setting: This was a laboratory-based study using cells from clinical samples and thyroid cancer cell lines. Main Outcome and Measure: We aimed to find evidence for a link between the expression of PTCSC3 and thyroid carcinogenesis. Results: Expression data from PTC cell lines pinpointed S100A4 as the most significantly downregulated gene in the presence of PTCSC3. S100A4 was upregulated in tumor tissue (P = 9.33 x 10(-7)) while PTCSC3 was strongly downregulated (P = 2.2 x 10(-16)). S100A4 transcription was moderately correlated with PTCSC3 expression in unaffected thyroid tissue (r = 0.429, P = .0001), and strongly in unaffected tissue of patients with the risk allele of rs944289 (r = 0.685, P = 7.88 x 10(-5)). S100A4, VEGF, and MMP-9 were suppressed in the presence of PTCSC3 (P = .0051, P = .0090, and P = .0037, respectively). PTC cells expressing PTCSC3 showed reduction in motility and invasiveness (P = 4.52 x 10(-5) and P = 1.0 x 10(-4), respectively). Conclusions: PTCSC3 downregulates S100A4, leading to a reduction in cell motility and invasiveness. We propose that PTCSC3 impacts PTC predisposition and carcinogenesis through the S100A4 pathway.