胃动素及其前体mRNA在正常人甲状腺和甲状腺肿瘤组织中表达的研究

Expression of motilin and its precursor mRNA in normal parenchyma, benign and malignant tumors of human thyroid

目的探讨胃动素和胃动素前体mRNA基因在正常人甲状腺的表达，比较人甲状腺胃动素前体mRNA基因序列与人小肠胃动素前体mRNA基因序列的异同；观察胃动素活性肽和胃动素前体mRNA在甲状腺肿瘤中的表达，并比较它们在良、恶性甲状腺肿瘤表达的异同及临床意义。方法采用RT-PCR、Southern杂交和分子克隆等技术，克隆并测定人甲状腺和人小肠黏膜内胃动素前体mRNA基因序列；采用荧光免疫组织化学双染技术、Western印迹和即时荧光定量PCR（real-time PCR），观察胃动素和胃动素前体mRNA在正常甲状腺和甲状腺良、恶性肿瘤组织中表达的异同。结果（1）正常人甲状腺组织有胃动素和胃动素前体mRNA的表达，且胃动素和降钙素共表达于同一细胞，即甲状腺C细胞；（2）人甲状腺组织内胃动素前体mRNA基因序列与基因库报道的人小肠胃动素前体mRNA基因序列（BC112314，NCBI，美国）完全相同；（3）免疫荧光组织化学、Western印迹以及real-time PCR结果均显示，正常人甲状腺和甲状腺肿瘤组织内均有胃动素和胃动素前体mRNA的表达，其中甲状腺髓样癌和嗜酸性腺瘤胃动素及其前体mRNA的表达高于正常甲状腺组织（均P〈0．05）；但甲状腺乳头状癌和滤泡癌胃动素和胃动素前体mRNA的表达则明显降低（均P〈0．05）；而结节性甲状腺肿与正常甲状腺组织相比胃动素和胃动素前体mRNA的表达差异均无统计学意义（P〉0．05）。结论人甲状腺组织有胃动素和胃动素前体mRNA的表达，且胃动素主要表达于甲状腺C细胞；人甲状腺组织胃动素前体mRNA基因序列与人小肠胃动素前体mRNA基因序列完全相同；甲状腺髓样癌和嗜酸性腺瘤内胃动素及其前体mRNA的表达明显增高，而甲状腺乳头状癌和滤泡癌内胃动素及其前体mRNA的表达明显降低。提示胃动素可能通过影响甲状腺滤泡旁细胞的分泌活动参与其生理活动的调节，胃动素可能与临床甲状腺髓样癌和甲状腺嗜酸性腺瘤疾病的发生和发展有关。

Objective To investigate the expression of motilin and its precursor mRNA in normal human thyroid. To compare the expression differences of motilin and it precursor mRNA between normal thyroid and intestines. To study the expression of motilin and its precursor mRNA in human thyroid tumors and their clinical implications. Methods RT-PCR, Southern blot and molecular cloning were used to detect motilin transcript expression in human thyroid and mucous membrane of small intestine. Real-time PCR and immunohistochemical techniques were used to quantify motilin precursor mRNA and motilin peptide in thyroid tissue samples including adenoma, medullary carcinoma, follicular carcinoma, papillary carcinoma and nodular goiter. Results （ 1 ） The expression of motilin and its precursor mRNA in normal human thyroid was primarily in the thyroid C cells. （2） RT-PCR and Southern blot showed that motilin mRNA expressed in human thyroid was identical to that expressed in duodenum with identical sequence deposited in NCBI Genbank of America. （3） Immunohistochemistry, Western blot research and real-time PCR studies showed that motilin and its precursor mRNA were expressed in normal and tumor tissues of human thyroid. Thyroid tumors （acidophilic adenoma, medullary carcinoma, follicular carcinoma, papillary carcinoma and nodular goiter） showed intense and diffuse immunostaining for motilin peptide. Moreover, the expression of motilin and its precursor mRNA in thyroid medullar carcinoma and acidophilic adenoma were significantly higher than those of normal thyroid tissue （ P 〈 0. 05 ）. The expression in thyroid follicular and papillary carcinomas were significantly lower than those of normal thyroid tissue （ P 〈 0. 05 ）. There was no difference of the expression between nodular goiter and normal thyroid tissue （ P 〉 0. 05 ）. Conclusion Motilin peptide and its precursor mRNA are expressed in C cells of human thyroid. The sequence of motilin is identical to that expressed in duodenum from NCBI Genbank of America. The expressions of both motilin and its precursor mRNA in thyroid medullary carcinoma and acidophilic adenoma are significantly increased. In contrast, their expressions in thyroid follicular and papillary carcinomas are significantly decreased. Motilin may regulate physiological functions of the thyroid through parafollicular cells. Motilin may be involved in the pathogenesis of medullary carcinoma and acidophihc adenoma of the thyroid.