Characterization of hypercalcemia-producing factor produced by carcinomas by Northern blot hybridization.

恶性肿瘤相关性高钙血症是由恶性肿瘤产生的骨吸收因子引起的。我们报道了从高钙血症患者中建立的鳞状细胞癌细胞产生了一种有效的骨吸收因子，该因子没有PTH样活性。为了研究这种IL-1样活性是否为真正的IL-1-α，从肿瘤细胞（T3 M-1，EC-GI）中提取mRNA，进行北方印迹杂交分析。我们发现，两种细胞都能产生IL-1 α mRNA，但不产生IL-1 β mRNA。此外，我们还发现，两种细胞都能产生PTH相关蛋白（PTH-RP）mRNA，PTH-RP是一种最近发现的骨吸收因子，具有PTH样特性。我们发现，IL-1和PTH rP在体外协同刺激骨吸收，在体内也协同增加小鼠血清钙浓度。因此，我们证明了一些实体瘤产生两种以上的骨吸收因子，并且这两种因子协同地导致恶性肿瘤的体液性高钙血症。

Malignancy-associatied hypercalcemia is elicited by bone-resorbing factors produced by malignant tumors. We reported that squamous carcinoma cells established from patients with hypercalcemia produced a potent bone resorbing factor which has no PTH-like activity. The bone resorbing activity comigrated with thymocyte proliferation-stimulating activity and completely inhibited by anti-IL-1 alpha antibody but not by anti-IL-1 beta antibody.To investigate whether this IL-1-like activity is an authentic IL-1-alpha, mRNA was extracted from tumor cells (T3M-1, EC-GI) and subjected to Northern blot hybridization analysis. We have found that both cells produced constitutively IL-1 alpha mRNA but no IL-1beta mRNA.Furthermore, we identified that both cells produced mRNA for PTH-related protein (PTH-RP), a recently characterized bone-resorbing factor, which has PTH-like properties.We have found that IL-1 and PTH rP synergistically stimulate bone resorption in vitro and also synergistically increase serum calcium concentration in mice in vivo.Therefore, we demonstrated that some solid tumors produced more than two bone resorbing factors and that both factors are synergistically responsible for humoral hypercalcemia of malignancy.