Myhre L, Ekeland A, Gautvik K M
Acta Endocrinol (Copenh). 1982 Mar;99(3):397-403. doi: 10.1530/acta.0.0990397.
The immunoreactive and biological activities of calcitonin (CT) produced by transplanted rat medullary thyroid carcinomas (MCT) have been studied. Immunoreactive CT (iCT) in serum and in MCT tissues of rats carrying tumours of generations 5-8 was characterized by gel filtration on Sephadex G-100 followed by radioimmunological measurements using region specific antiserum. The hypocalcaemic effect of sera and tumour extracts was tested in a rat bioassay. Rats with transplanted MCT of the 5th and 6th generations had mainly (70-84%) circulating iCT species of molecular size comparable to intact hormone. However, in rats with tumours of the 7th and 8th generations corresponding circulating iCT forms comprised less than 52% of total immunoreactivity while 32-38% eluted earlier. In comparison, iCT corresponding to intact hormone represented 30-50% of total immunoreactivity in the tumour extracts and no differences were observed between the generations. Subcutaneous injections of sera from MCT rats and of tumour extracts reduced the serum levels of ionized calcium in test rats. The sera containing mainly intact iCT showed the strongest biological potency. We conclude that rat MCT transplanted under the kidney capsule is able to secrete biologically active CT. However, the heterogeneity of circulating iCT increases in rats with transplanted tumours of older generations, approaching the heterogeneity of stored hormone in the gland.
对移植的大鼠甲状腺髓样癌（MCT）所产生的降钙素（CT）的免疫反应性和生物活性进行了研究。通过在Sephadex G - 100上进行凝胶过滤，然后使用区域特异性抗血清进行放射免疫测定，对携带5 - 8代肿瘤的大鼠血清和MCT组织中的免疫反应性CT（iCT）进行了表征。在大鼠生物测定中测试了血清和肿瘤提取物的降钙作用。第5代和第6代移植MCT的大鼠，其循环中主要（70 - 84%）是分子大小与完整激素相当的iCT种类。然而，在第7代和第8代肿瘤的大鼠中，相应的循环iCT形式占总免疫反应性的比例不到52%，而32 - 38%的iCT洗脱较早。相比之下，肿瘤提取物中对应完整激素的iCT占总免疫反应性的30 - 50%，各代之间未观察到差异。皮下注射MCT大鼠的血清和肿瘤提取物可降低试验大鼠血清中离子钙的水平。主要含有完整iCT的血清显示出最强的生物活性。我们得出结论，移植到肾被膜下的大鼠MCT能够分泌具有生物活性的CT。然而，在移植了较老一代肿瘤的大鼠中，循环iCT的异质性增加，接近腺体中储存激素的异质性。
