Chen Kevin G, Szakács Gergely, Annereau Jean-Philippe, Rouzaud Francois, Liang Xing-Jie, Valencia Julio C, Nagineni Chandrasekharam N, Hooks John J, Hearing Vincent J, Gottesman Michael M
Laboratory of Cell Biology, National Cancer Institute, National Institutes of Health, Bethesda, MD, USA.
Pigment Cell Res. 2005 Apr;18(2):102-12. doi: 10.1111/j.1600-0749.2005.00214.x.
ATP-binding cassette (ABC) transporters play a pivotal role in physiology and pathology. We identified and cloned two novel mRNA isoforms (ABCB 5alpha and ABCB 5beta) of the ABC transporter ABCB 5 in human melanoma cells. The deduced ABCB 5alpha protein appears to be an altered splice variant containing only a putative ABC, whereas the ABCB 5beta isoform shares approximately 70% similarity with ABCB1 (MDR1) and has a deduced topological arrangement similar to that of the whole carboxyl terminal half of the ABCB1 gene product, P-glycoprotein, including an intact ABC. Northern blot, real-time PCR, and conventional RT-PCR were used to verify the expression profiles of ABCB 5alpha/beta. We found that the melanomas included among the NCI-60 panel of cell lines preferentially expressed both ABCB 5alpha and ABCB 5beta. However, ABCB 5alpha/beta expression was undetectable in two amelanotic melanomas (M14 and LOX-IMVI). The expression profile of ABCB 5alpha/beta in all of the other melanomas of the panel was confirmed both by RT-PCR and by sequencing. Neither ABCB 5alpha nor ABCB 5beta expression was found in normal tissues such as liver, spleen, thymus, kidney, lung, colon, small intestines or placenta. ABCB 5alpha/beta mRNAs were also expressed in normal melanocytes and in retinal pigment epithelial cells, suggesting that ABCB 5alpha/beta expression is pigment cell-specific and might be involved in melanogenesis. Our findings indicate that expression of ABCB 5alpha/beta might possibly provide two novel molecular markers for differential diagnosis of melanomas and constitute potential molecular targets for therapy of melanomas.
ATP结合盒（ABC）转运蛋白在生理和病理过程中发挥着关键作用。我们在人黑色素瘤细胞中鉴定并克隆了ABC转运蛋白ABCB 5的两种新型mRNA亚型（ABCB 5α和ABCB 5β）。推导的ABCB 5α蛋白似乎是一种改变的剪接变体，仅包含一个假定的ABC，而ABCB 5β亚型与ABCB1（MDR1）具有约70%的相似性，并且推导的拓扑结构与ABCB1基因产物P-糖蛋白的整个羧基末端一半相似，包括一个完整的ABC。使用Northern印迹、实时PCR和常规RT-PCR来验证ABCB 5α/β的表达谱。我们发现，NCI-60细胞系面板中的黑色素瘤优先表达ABCB 5α和ABCB 5β。然而，在两种无色素性黑色素瘤（M14和LOX-IMVI）中未检测到ABCB 5α/β表达。通过RT-PCR和测序证实了该面板中所有其他黑色素瘤中ABCB 5α/β的表达谱。在肝脏、脾脏、胸腺、肾脏、肺、结肠、小肠或胎盘等正常组织中未发现ABCB 5α和ABCB 5β表达。ABCB 5α/β mRNA也在正常黑素细胞和视网膜色素上皮细胞中表达，这表明ABCB 5α/β表达是色素细胞特异性的，可能参与黑色素生成。我们的研究结果表明，ABCB 5α/β的表达可能为黑色素瘤的鉴别诊断提供两个新的分子标志物，并构成黑色素瘤治疗的潜在分子靶点。
