Downregulation of endothelin B receptor in human melanoma cell lines parallel to differentiation genes
Downregulation of endothelin B receptor in human melanoma cell lines parallel to differentiation genes
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DOI：
10.1046/j.1523-1747.1999.00598.x
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发表时间：
1999-06-01
影响因子：
6.5
通讯作者：
Orfanos, CE
中科院分区：
文献类型：
--
作者：
Eberle, J;Weitmann, S;Orfanos, CE
已有研究表明，正常人黑素细胞对信号肽内皮素的反应是通过促进黑素的增殖和形成。然而，关于正常黑素细胞和黑色素瘤细胞表达两种内皮素受体(EDNRA或EDNRB)中的哪一种，已有相互矛盾的发现。此外，目前尚不清楚恶性细胞在这方面是否与其正常前体细胞不同。筛选黑色素瘤下调基因的黑素细胞cDNA文库，鉴定EDNRB特异性克隆。Northern杂交证明，在培养的人皮肤黑素细胞和先天性黑素细胞痣细胞中普遍表达相应的mRNA。然而，在17个黑色素瘤细胞系中，有16个细胞株的EDNRB mRNA表达显著下调。Northern印迹显示，在17个良性黑素细胞培养物中有12个和17个黑色素瘤细胞系中有4个细胞株中有Ednra弱表达。套式逆转录聚合酶链式反应证明，几个黑色素瘤细胞株的Ednra表达完全阴性。基因组Southern杂交排除了基因缺失是内皮素受体表达缺失的原因，受体结合分析证实了黑素细胞培养每个细胞有1.6×10(5)个内皮素-1结合位点，黑色素瘤细胞株每个细胞有8.7×10(4)-400个结合位点。色素沉着基因酪氨酸酶、Trp-1和Trp-2的表达与EDNRB呈正相关，与Ednra表达呈负相关。因此，EDNRB而不是Ednra的表达在黑素细胞中是典型的，而EDNRB的下调似乎是黑色素瘤细胞的一个重要特征，可能与恶性程度或细胞凋亡有关。
Normal human melanocytes have been shown to respond to the signal peptide endothelin by increased proliferation and melanin formation. Contradictory findings, however, have been reported about which of the two endothelin receptors (EDNRA or EDNRB) is expressed in normal melanocytes and melanoma cells. Moreover it was not clear whether malignant cells differ from their normal precursors in this respect. Screening a melanocyte cDNA library for genes downregulated in melanomas identified clones specific for EDNRB. Northern blots proved that the corresponding mRNA is generally expressed in cultures of human cutaneous melanocytes and congenital melanocytic nevus cells. In 16 of 17 melanoma cell lines, however, the expression of EDNRB mRNA was strongly downregulated. EDNRA was only weakly expressed and detectable by northern blotting in 12 of 17 cultures of benign melanocytic cells and four of 17 melanoma cell lines. Nested reverse transcriptase-polymerase chain reaction proved several melanoma cell lines to be completely negative for EDNRA expression. Gene deletion as the cause of missing endothelin receptor expression was ruled out by genomic Southern blots, Receptor binding assays confirmed RNA data revealing 1.6 x 10(5) endothelin-1 binding sites per cell for a melanocyte culture and between 8.7 x 10(4) and 400 sites per cell for melanoma cell lines. Expression of pigmentation genes coding for tyrosinase, TRP-1 and TRP-2 correlated positively with that of EDNRB but negatively with EDNRA expression. EDNRB but not EDNRA expression is therefore typical for melanocytic cells, and downregulation of EDNRB seems to be an important characteristic of melanoma cells possibly related to malignancy or apoptosis.