Westbrook V Anne, Schoppee Pamela D, Diekman Alan B, Klotz Kenneth L, Allietta Margaretta, Hogan Kevin T, Slingluff Craig L, Patterson James W, Frierson Henry F, Irvin William P, Flickinger Charles J, Coppola Michael A, Herr John C
Department of Cell Biology, Center for Research in Contraceptive and Reproductive Health, University of Virginia, Charlottesville, Virginia, USA.
Clin Cancer Res. 2004 Jan 1;10(1 Pt 1):101-12. doi: 10.1158/1078-0432.ccr-0647-3.
Members of the SPAN-X (sperm protein associated with the nucleus mapped to the X chromosome) family of cancer-testis antigens are promising targets for tumor immunotherapy because they are normally expressed exclusively during spermiogenesis on the adluminal side of the blood-testis barrier, an immune privileged compartment.
This study analyzed the human SPANX genomic organization, as well as SPAN-X mRNA and protein expression in somatic and cancer cells. The SPANX family consists of five genes, one of which is duplicated, all located in a gene cluster at Xq27.1. From the centromere, the arrangement of the five SPANX genes mapped on one contiguous sequence is SPANXB, -C, -A1, -A2, and -D. Reverse transcription-PCR analyses demonstrated expression of SPAN-X mRNA in melanoma and ovarian cell lines, and virtual Northern analysis established SPANX gene expression in numerous cancer cell lines. Immunoblot analysis using polyclonal antisera raised against recombinant SPAN-X confirmed the translation of SPAN-X proteins in melanoma and ovarian tumor cell lines. The immunoreactive proteins migrated between M(r) 15,000 and M(r) 20,000 similar to those observed in spermatozoa. Immunoperoxidase labeling of melanoma cells and tissue sections demonstrated SPAN-X protein localization in the nucleus, cytoplasm, or both. Ultrastructurally, in melanoma cells with nuclear SPAN-X, the protein was associated with the nuclear envelope, a localization similar to that observed in human spermatids and spermatozoa. Significantly, the incidence of SPAN-X-positive immunostaining was greatest in the more aggressive skin tumors, particularly in distant, nonlymphatic metastatic melanomas.
The data herein suggest that the SPAN-X protein may be a useful target in cancer immunotherapy.
癌-睾丸抗原SPAN-X（与定位于X染色体的细胞核相关的精子蛋白）家族成员是肿瘤免疫治疗的有前景的靶点，因为它们通常仅在精子发生过程中在血睾屏障的管腔侧表达，血睾屏障是一个免疫特惠区。
本研究分析了人SPANX的基因组结构，以及SPAN-X mRNA和蛋白质在体细胞和癌细胞中的表达。SPAN-X家族由五个基因组成，其中一个是重复的，所有基因都位于Xq27.1的一个基因簇中。从着丝粒开始，映射在一个连续序列上的五个SPANX基因的排列顺序是SPANXB、-C、-A1、-A2和-D。逆转录-PCR分析表明SPAN-X mRNA在黑色素瘤和卵巢癌细胞系中有表达，虚拟Northern分析确定了SPANX基因在众多癌细胞系中的表达。使用针对重组SPAN-X产生的多克隆抗血清进行的免疫印迹分析证实了SPAN-X蛋白在黑色素瘤和卵巢肿瘤细胞系中的翻译。免疫反应性蛋白的迁移分子量在15,000至20,000之间，与在精子中观察到的相似。黑色素瘤细胞和组织切片的免疫过氧化物酶标记显示SPAN-X蛋白定位于细胞核、细胞质或两者中。在超微结构上，在细胞核中有SPAN-X的黑色素瘤细胞中，该蛋白与核膜相关，这种定位类似于在人类精子细胞和精子中观察到的。值得注意的是，SPAN-X阳性免疫染色的发生率在侵袭性更强的皮肤肿瘤中最高，特别是在远处的非淋巴转移性黑色素瘤中。
本文数据表明SPAN-X蛋白可能是癌症免疫治疗中的一个有用靶点。
