Clinical significance of mannose-binding lectin expression in thyroid carcinoma tissues

Mannose-binding lectin (MBL) plays an important role in the host defence against pathogens and carcinogenesis. This study aimed to analyze differential expression of MBL protein in thyroid cancer tissues and then to investigate the effects of rhMBL in thyroid cancer cells. Tissue specimens from 45 thyroid carcinoma patients and 45 adenoma patients were recruited for immunohistochemical analysis of MBL expression. Cell viability, apoptosis, RT-PCR and Western blot assays were used to detect changes in tumor cell viability, apoptosis, and gene expression, respectively, after treatment of thyroid cancer cells with rhMBL. MBL was differentially expressed in papillary thyroid carcinoma, adenoma, and the distant normal tissues (0.322 ± 0.008, 0.227 ± 0.003, and 0.113 ± 0.003, respectively, P < 0.05). MBL expression was associated with the advanced disease stage, histological grade, or lymph node metastasis in cancer patients (P < 0.05). Moreover, rhMBL treatment of thyroid cancer cells reduced tumor cell viability but induced apoptosis in a dose- and time-dependent manner. rhMBL treatment also downregulated Bcl2 protein expression in thyroid cancer cells (P < 0.05). In addition, expression p53 protein was increased in thyroid cancer cells after rhMBL treatment (P < 0.05). The data from the current study demonstrate that MBL overexpression is associated with advanced thyroid carcinomas, and rhMBL treatment significantly reduced viability but induced apoptosis of thyroid cancer cell lines. Further studies will clarify whether overexpressed MBL in thyroid cancer tissues is functional.