LncRNA HOTTIP promotes papillary thyroid carcinoma cell proliferation, invasion and migration by regulating miR-637.

Papillary thyroid carcinoma (PTC) is the most common thyroid malignancy. Besides, increasing evidence has demonstrated that long non-coding RNA (lncRNA) HOTTIP played a crucial role in cancer pathogenesis. MiR-637-mediated Akt1 was involved in cell growth, invasion and migration in various malignancies. This study was aimed to investigate the potential biological effect and regulatory mechanism of HOTTIP on cell proliferation, invasion and migration in PTC. Expression of HOTTIP, miR-637 and Akt1 were determined by quantitative RT-PCR (qRT-PCR) and western blotting in PTC tissues, normal tissues, PTC cells (TPC-1 and HTH83) or non-tumor thyroid cells (Nthy-ori 3-1). Cell proliferation, invasion and migration following HOTTIP knockdown were investigated in PTC cells. The target of HOTTIP was validated by RNA immunoprecipitation (RIP) and pull-down assay. Moreover, a xenograft model was performed. HOTTIP was upregulated in human PTC tissues and PTC cell lines. In addition, HOTTIP knockdown inhibited the proliferation, invasion and migration in vitro together with in vivo tumorigenesis of PTC cells. Additionally, HOTTIP knockdown downregulated Akt1 expression and suppressed cell proliferation, invasion and migration in PTC cells by regulating miR-637. In contrast, miR-637 inhibitor reversed above-mentioned tendencies caused by HOTTIP knockdown. HOTTIP is a potential oncogene in PTC and may serve as a therapeutic target for malignancies.