Effects And Expression Of Cathepsin B And Its Gene Variants In Thyroid Tumor

Objective:Cathepsin B is associated with the occurrence and development of malignant tumors. The foreign research confirmed that cathepsin B is expressed at high levels in thyroid tumor. Our study aims to investigate the expression of cathepsin B in thyroid tumor and then study the relationship between its expression and thyroid tumors' clinical pathological factors, so that we can further study the etiology and pathogenesis of the thyroid tumors and then find a new gene target through block its expression at gene level.Methods:The study subjects were devided into three major groups:the thyroid carcinoma group, the thyroid adenoma group and the normal control group. The patients of the thyroid carcinoma group and the thyroid adenoma group were selected randomly from the Breast and Thyroid surgical department of the Affiliated Hospital of Jining Medical College and the First People's Hospital of Jining City. The patients all took operation during the period from October 2008 to June 2009. Each group included 30 cases.30 cases of normal samples were selected from the cortical tissue around the thyroid adenoma. Each group never received chemotherapy and radiotherapy. We recorded the patient's basic information such as the name, sex, age and the tumor size, amicula infiltration degree and lymph node metastasis condition of the thyroid carcinoma group. We collected the fresh samples taken from the operation within half an hour, then quickly placed in liquid nitrogen, and then stored in -80℃refrigerator within half an hour, all pathological types of the samples were confirmed by the experienced pathology after the operation. The fluorescence substracts activity assay was used to measure the enzyme activity. The Western blot method was used to measure the CTSB protein expression. The method of RT-PCR was used to measure the CTSB mRNA and its variants'expression. All data was analyzed by the statistic software of SPSS13.0, and p<0.05 was considered to be the statistical significance.Result:(1) The general information showed the average age of the thyroid carcinoma group, the thyroid adenoma group and the normal were 35.68±7.69, 32.52±6.87,32.52±6.87 respectively. The sex and age of each group hadn't show any statistical significance among these groups(p>0.05). (2)The fluorescent substrate method and Westernblot result showed that the cathepsin B activity and protein expression were significantly higher than that of the normal tissue, which showed a statistical significance(p<0.05), and the expression of the carcinoma group was significantly higher than that of the thyroid adenoma group(p<0.05). (3) The thyroid carcinoma group was grouped according to the name, sex, age, the tumor size, amicula infiltration degree and lymph node metastasis condition. The expression of CTSB protein in subgroup of amicula infiltration and lymph node metastasis were significantly higher than that in subgroup of non amicula infiltration and non lymph node metastasis. The expression of CTSB protein hadn't showed any statistical significance among the subgroup of different name, sex, age and the tumor size. (4)The RT-PCR results showed that the expression of CTSBmRNA in thyroid tumor group was significantly higher than that of the normal group, which showed a statistical significance (p<0.05), and the expression of the carcinoma group was significantly higher than that of the thyroid adenoma group (p<0.05), and we detected the expression of CTSB gene variants in the thyroid carcinoma group (5/30), while its expression in the thyroid adenoma group and the normal group was negative.Conclusion:(1) The CTSB enzyme activity, protein expression and gene expression in thyroid tumor were significantly higher than that of the normal tissue, and the expression of the carcinoma group was significantly higher than that of the thyroid adenoma group, confirming that CTSB is closely related to the occurrence of thyroid tumor. (2) The expression of CTSB protein and CTSBmRNA in subgroup of amicula infiltration and lymph node metastasis were significantly higher than that in subgroup of non amicula infiltration and non lymph node metastasis, confirming that CTSB is correlated to the invasion and metastasis of thyroid carcinoma. (3)The expression of CTSB gene variants might be involved in the carcinogenesis of the thyroid carcinoma.