MicroRNA­16/VEGFR2/p38/NF­κB signaling pathway regulates cell growth of human pituitary neoplasms.

The association of microRNA (miRNA) with tumor has gradually become an active medical research field, since its discovery in 1993. The aim of the present study was to clarify how microRNA­16 expression affects the proliferation and survival of pituitary tumor, revealing its potential mechanism. MicroRNA­16 expression of pituitary tumor patients was observably declined, compared with the normal group. A high expression of microRNA­16 showed longer survival in pituitary tumor patients, compared to a low expression of microRNA­16 in pituitary tumor patients. MicroRNA­16 upregulation effectively decreased cell proliferation and induced apoptosis in HP75 cells. MicroRNA­16 overexpression effectively induced p27, Bax protein expression and caspase­3/8 activities, and suppressed phosphorylation-(p)-p38, NF­κB, MMP­9 and VEGFR2 protein expression in HP75 cells. After VEGFR2 suppression, the effects of microRNA­16 overexpression on cell proliferation and apoptosis were significantly inhibited in HP75 cells. Moreover, the effects of microRNA­16 overexpression on p27, Bax protein expression and caspase­3/8 activities were significantly decreased in HP75 cells after p38 suppression. VEGFR2 or NF­κB suppression reduced the effects of microRNA­16 overexpression on p­p38, NF­κB, MMP­9 and VEGFR2 protein expression inhibition in HP75 cells. Our results suggest that microRNA­16 expression affects the proliferation and angiogenesis of pituitary cancer through the VEGFR2/p38/NF­κB signaling pathway.

TPX2 overexpression in medullary thyroid carcinoma mediates TT cell proliferation.

TPX2 (targeting protein for xenopus kinesin-like protein 2), a microtubule-associated protein, plays an important role in the formation of the mitotic spindle. Abnormal expression of TPX2 in various types of malignant tumors has been reported, but less is known for medullary thyroid cancer (MTC). We investigated the expression of TPX2 in human MTC tissues and its potential use as a therapeutic target. Immunohistochemical analysis of TPX2 expression was performed for 32 cases of MTC and 8 cases of normal thyroid. TPX2 expression was found to be significantly higher in MTC compared to normal thyroid tissues (P < 0.05), and to be associated with tumor size, lymph node metastasis, and advanced disease stage. The cellular effects of TPX2 knockdown, including cell proliferation, apoptosis, cell cycle diffusions, and mitotic gene expression were investigated using small interfering RNA (siRNA). TPX2-siRNA caused G1 and G2-phase cell cycle arrest, inhibited cell proliferation, and induced apoptosis. TPX2-siRNA also downregulated Aurora-A and cyclinB1 protein expression in MTC cells and enhanced the expression of p53 protein (P < 0.05). These results suggest that TPX2 may be of potential use as a new marker for MTC prognosis and therapy.

CCNG2 suppressor biological effects on thyroid cancer cell through promotion of CDK2 degradation.

This study aimed to analyze the expression and clinical significance of cyclin G2 (CCNG2) in thyroid carcinoma and the biological effects of CCNG2 overexpression in a cell line. Immunohistochemistry and Western blotting were used to analyze CCNG2 protein expression in 63 cases of thyroid cancer and normal tissues to allow the relationship with clinical factors to be assessed. CCNG2 lentiviral and empty vectors were transfected into the thyroid cancer K1 cell line. Reverse transcription-polymerase chain reaction (RT-PCR) and Western blotting were applied to detect the mRNA and protein levels of CCNG2. MTT assay and cell cycle were also conducted to assess the influence of up-regulated expression of CCNG2 on K1 cell biology. The level of CCNG2 protein expression was found to be significantly lower in thyroid cancer tissue than normal tissues (P<0.05). Western blot: The relative amount of CCNG2 protein in thyroid cancer tissue was respectively found to be significantly lower than in normal tissues (P<0.05), correlating with lymph node metastasis, clinic stage and histological grade (P<0.05), but not gender, age or tumor size (P>0.05). Loss of CCNG2 expression correlated significantly with poor overall survival time on Kaplan-Meier analysis (P<0.05). The results for biological functions showed that K1 cell transfected CCNG2 had a lower survival fraction, a greater percentage in the G0/G1 phases, and lower cyclin-dependent kinase 2 (CDK2) protein expression compared with K1 cells non-transfected with CCNG2 (P<0.05). CCNG2 expression decreased in thyroid cancer and correlated significantly lymph node metastasis, clinic stage, histological grade and poor overall survival, suggesting that CCNG2 may play important roles as a negative regulator in thyroid cancer K1 cells by promoting degradation of CDK2.

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.