Lysine-Specific Demethylase 1 Affects the Progression of Papillary Thyroid Carcinoma via HIF1α and microRNA-146a

Context Lysine-specific demethylase 1 (LSD1) stabilizes hypoxia-inducible factor 1α (HIF1α) to advance tumor progression, while HIF1α functions as a transcription factor to increase the expression of microRNA-146a (miR-146a). Objective We aim to investigate whether LSD1 affects the development of papillary thyroid carcinoma (PTC) via HIF1α and miR-146a. Design In vitro assays were performed with Nthy-ori 3-1, BHP5-16, BCPAP, K1, and BHP2-7 cell lines. In vivo assays were conducted with established xenograft tumors in nude mice. Setting This study was conducted at our lab. Patients and Materials PTC tissues and corresponding adjacent normal tissues were obtained from 45 patients hospitalized in Sun Yat-Sen Memorial Hospital. Assays were conducted using Nthy-ori 3-1, BHP5-16, BCPAP, K1, and BHP2-7 cell lines, as well as 50 male BALB/c nude mice. Intervention Cells were transfected with sh-LSD1, sh-GABPA, oe-LSD1, oe-HIF1α, miR-146a mimic, and miR-146a inhibitor. In addition, K1 cells expressing lv-oe-LSD1, lv-miR-146a inhibitor, lv-oe-LSD1 or miR-146a inhibitor were injected into the right side of the mice. LSD1 gene and protein expression patterns were analyzed in 45 clinical PTC tissue samples. Main Outcome Measure Expression of LSD1, HIF1α, miR-146a, and GA-binding protein transcription factor alpha (GABPA), as well as their effects on PTC. Results LSD1 was highly expressed in clinical PTC tissues. LSD1 stabilized HIF1α and inhibited the degradation of its ubiquitin proteasome. HIF1α was enriched in the promoter region of miR-146a, an upregulated miRNA in PTC. HIF1α increased miR-146a expression to promote PTC progression in vitro, which was achieved by inhibiting GABPA, a target gene of miR-146a. LSD1 upregulated miR-146a to enhance the development and metastasis of PTC in nude mice. Conclusion Our results show that LSD1 functions as an oncogene in PTC by upregulating HIF1α and miR-146a, elucidating an understanding of undefined mechanisms associated with tumor progression in PTC.