Analysis of PTHRP binding and signal transduction mechanisms in benign and malignant squamous cells.
Analysis of PTHRP binding and signal transduction mechanisms in benign and malignant squamous cells.
复制标题
良性和恶性鳞状细胞中 PTHRP 结合和信号转导机制的分析。
DOI：
10.1152/ajpendo.1992.262.5.e599
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发表时间：
1992
期刊：
影响因子：
--
通讯作者：
Stewart,AF
中科院分区：
文献类型：
--
作者：
Orloff,JJ;Ganz,MB;Ribaudo,AE;Burtis,WJ;Reiss,M;Milstone,LM;Stewart,AF
我们探讨了甲状旁腺相关蛋白（PTHRP）在恶性鳞状细胞癌细胞（SqCC）和其非恶性对应物人表皮角质形成细胞（HK）中的潜在自分泌作用。Tyr 36人PTHRP-（1-36）NH 2（125 I-[Tyr 36]hPTHRP-（1-36）NH 2）的特异性结合在75%的CRT-SqCC系中被鉴定。相比之下，在小鼠角质形成细胞系BALB-MK或五种不同的HK系上未检测到结合。虽然每个SqCC和角质形成细胞系分泌免疫反应PTHRP到其培养基中，有PTHRP的浓度和结合位点的数量之间没有相关性。[Tyr 36]hPTHRP-（1-36）NH 2抑制结合在所有SqCC细胞系中产生的半数最大抑制浓度值约为100 nM。SqCC细胞的亲和交联揭示了具有相似亲和力（约100 nM）的98-和70-kDa结合蛋白。Fura-2负载的SqCC细胞暴露于PTHRP和PTH导致细胞内钙的等效、剂量依赖性瞬时增加[半数最大有效浓度（EC 50）= 0.08 nM]。PTHRP还增加HK中的细胞内钙（EC 50 = 0.05 nM）。在SqCC或HK中均未引起对PTHRP或PTH的腺苷3 '，5'-环磷酸（cAMP）反应，尽管两者中均存在活跃的异丙肾上腺素反应。我们的结论是，高容量低亲和力的PTHRP结合位点是可检测的大多数SqCC线，但不是在香港。这些低亲和力结合位点不太可能代表受体。敏感的细胞内钙反应表明，在SqCC以及HK上存在额外的高亲和力受体。然而，PTHRP或PTH刺激环化酶活性细胞中cAMP产生的失败表明这些不是经典的PTH受体。（250字处删节）
We have explored a potential autocrine role for parathyroid hormone-related protein (PTHRP) in malignant squamous carcinoma cells (SqCC) and their nonmalignant counterpart, human epidermal keratinocytes (HK). Specific binding of Tyr36 human PTHRP-(1-36)NH2 (125I-[Tyr36]hPTHRP-(1-36)NH2) was identified in 75% of unselected SqCC lines. In contrast, no binding was detected on the mouse keratinocyte line BALB-MK or on five different HK lines. Although each SqCC and keratinocyte line secreted immunoreactive PTHRP into its medium, there was no correlation between PTHRP concentration and number of binding sites. Inhibition of binding by [Tyr36]hPTHRP-(1-36)NH2 yielded half-maximal inhibitory concentration values of approximately 100 nM in all SqCC lines. Affinity cross-linking of SqCC cells revealed 98- and 70-kDa binding proteins with similar affinity (approximately 100 nM). Exposure of fura-2-loaded SqCC cells to PTHRP and PTH resulted in equivalent, dose-dependent transient increases in intracellular calcium [half-maximal effective concentration (EC50) = 0.08 nM]. PTHRP also increased intracellular calcium in HK (EC50 = 0.05 nM). No adenosine 3',5'-cyclic monophosphate (cAMP) response to PTHRP or PTH was elicited in either SqCC or HK, despite brisk isoproterenol responses in both. We conclude that high-capacity low-affinity binding sites for PTHRP are detectable in the majority of SqCC lines but not in HK. These low-affinity binding sites are unlikely to represent receptors. The sensitive intracellular calcium response suggests the additional presence of high-affinity receptors on SqCC as well as on HK. However, the failure of PTHRP or PTH to stimulate cAMP production in otherwise cyclase-competent cells suggests that these are not classical PTH receptors.(ABSTRACT TRUNCATED AT 250 WORDS)