ABSTRACT
BACKGROUND: Thyroid cancer stem cells are essential to the recurrence and metastasis of thyroid carcinoma. Leukemia inhibitory factor receptor (LIFR) shows a downward trend in a variety of malignant tumors, and its overexpression can inhibit the recurrence and metastasis of malignant tumors. OBJECTIVE:To explore the effect of LIFR on the stemness maintenance and lung metastasis of thyroid cancer stem cells in vivo. METHODS: Primary thyroid cancer cells TCLM were isolated from the lung metastases of a metastatic thyroid cancer patient. Serum-free suspension culture was used to form tumor cell balls. Flow cytometry was used to screen CD133+phenotype of metastatic thyroid cancer stem cell subpopulation TCLM-S. The overexpressed recombinant lentiviral plasmid containing LIFR and its negative control containing the empty plasmid were infected into thyroid cancer stem cells TCLM-S at the ratio of virus/cell number=20, and screened with 2.0 mg/L puromycin to construct TCLM-SLIFRand TCLM-Scontrolstem cells which stably expressed LIFR and its control. Real-time quantitative PCR (qRT-PCR) was used to detect the expression of LIFR in TCLM-SLIFRand TCLM-Scontrolstem cells. Flow cytometry was used to detect the percentage of CD133+phenotype cell subsets, western blot assay was used to detect the expression of tumor stemness related factors SOX2, Oct4, Nanog and tumor invasion and metastasis related proteins E-cadherin, matrix metalloproteinase (MMP)-2, MMP-7 in TCLM-SLIFRand TCLM-Scontrol stem cells. TCLM-SLIFRand TCLM-Scontrolstem cells were respectively injected into BALB/c nude mice by tail vein, and the lung metastasis model of thyroid cancer stem cells was constructed. The effect of LIFR overexpression on lung metastasis was observed. RESULTS AND CONCLUSION: Compared with TCLM-Scontrolcells, the expression of LIFR in TCLM-SLIFRcells was significantly increased, the proportion of CD133+phenotype stem cell subsets was significantly decreased, the expression of SOX2, Oct4 and Nanog were significantly decreased, the expression of E-cadherin was significantly increased, and the expression of MMP-2 and MMP-7 was significantly decreased. Moreover, the number of lung metastasis in nude mice given TCLM-SLIFRcells was significantly decreased as compared with those given TCLM-Scontrol cells.To conclude,LIFR overexpression can decrease the stemness and ability of lung metastasis in vivo.