Tumor metastasis-associated human MTA1 gene and its MTA1 protein product:: Role in epithelial cancer cell invasion, proliferation and nuclear regulation
Tumor metastasis-associated human MTA1 gene and its MTA1 protein product:: Role in epithelial cancer cell invasion, proliferation and nuclear regulation
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DOI：
10.1023/a:1022534217769
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发表时间：
2003-01-01
影响因子：
4
通讯作者：
Moustafa, A
中科院分区：
文献类型：
--
作者：
Nicolson, GL;Nawa, A;Moustafa, A
利用基于转移和非转移的大鼠乳腺癌细胞系的差异文库筛选技术，我们先前克隆并测序了转移相关基因MTA1。利用与大鼠MTA1基因的同源性，我们克隆了人MTA1基因，并发现它在各种人类细胞系(乳腺癌、卵巢癌、肺癌、胃癌和结直肠癌，但不包括黑色素瘤或肉瘤)和癌组织(乳腺癌、食道癌、结直肠癌、胃癌和胰腺癌)中过表达。我们发现人的MTA1基因和大鼠的MTA1基因非常相似(核苷酸和预测的氨基酸序列分别有88%和96%的相似性)。这两个基因都编码新的蛋白质，包括一个富含脯氨酸的区域(SH3结合基序)，一个可能的锌指基序，一个亮氨酸拉链基序和在基因调控蛋白中发现的5个拷贝的SPXX基序。经Southern印迹分析，MTA1基因高度保守，经Northern印迹分析，MTA1基因在几乎所有人类细胞系(黑色素瘤、乳腺癌细胞、子宫颈癌细胞、卵巢癌细胞和正常乳腺上皮细胞)中均有转录。然而，MTA1基因在正常乳腺上皮细胞中的表达水平与在快速生长的腺癌和不典型上皮细胞系中发现的50%相似。用反义硫代寡核苷酸抑制MTA1蛋白表达的实验结果显示，MTA1相对高表达的人乳腺癌细胞的生长和侵袭受到抑制。此外，MTA1蛋白定位在含有全长MTA1基因的哺乳动物表达载体转染的细胞的细胞核中。虽然有少量MTA1蛋白存在于细胞质中，但绝大多数MTA1蛋白定位于胞核。对重组MTA1和相关MTA2蛋白的检测表明，MTA1蛋白是一种组蛋白去乙酰基酶。它的行为也似乎类似于GATA元件转录因子，因为将GATA元件报告程序转染到MTA1表达的细胞中，导致报告程序的表达比低表达MTA1的细胞增加10-20倍。由于核小体重塑相关的组蛋白脱乙酰酶复合体(NuRD Complex)含有MTA1蛋白和MTA1相关蛋白(MTA2)，我们检测了NuRD复合体中MTA1蛋白的存在，发现该蛋白与组蛋白脱乙酰酶有关。这些结果表明，MTA1蛋白可能在细胞信号、染色体重塑和转录过程中发挥多种功能，这些过程在转移的上皮细胞的进展、侵袭和生长中起重要作用。
Using differential cDNA library screening techniques based on metastatic and nonmetastatic rat mammary adenocarcinoma cell lines, we previously cloned and sequenced the metastasis-associated gene mta1. Using homology to the rat mta1 gene, we cloned the human MTA1 gene and found it to be over-expressed in a variety of human cell lines (breast, ovarian, lung, gastric and colorectal cancer but not melanoma or sarcoma) and cancerous tissues (breast, esophageal, colorectal, gastric and pancreatic cancer). We found a close similarity between the human MTA1 and rat mta1 genes (88% and 96% identities of the nucleotide and predicted amino acid sequences, respectively). Both genes encode novel proteins that contain a proline rich region (SH3-binding motif), a putative zinc finger motif, a leucine zipper motif and 5 copies of the SPXX motif found in gene regulatory proteins. Using Southern blot analysis the MTA1 gene was highly conserved, and using Northern blot analysis MTA1 transcripts were found in virtually all human cell lines (melanoma, breast, cervix and ovarian carcinoma cells and normal breast epithelial cells). However, the expression level of the MTA1 gene in normal breast epithelial cells was similar to50% of that found in rapidly growing adenocarcinoma and atypical epithelial cell lines. Experimental inhibition of MTA1 protein expression using antisense phosphorothioate oligonucleotides resulted in inhibition of growth and invasion of human MDA-MB-231 breast cancer cells with relatively high MTA1 expression. Furthermore, the MTA1 protein was localized in the nuclei of cells transfected with a mammalian expression vector containing a full-length MTA1 gene. Although some MTA1 protein was found in the cytoplasm, the vast majority of MTA1 protein was localized in the nucleus. Examination of recombinate MTA1 and related MTA2 proteins suggests that MTA1 protein is a histone deacetylase. It also appears to behave like a GATA-element transcription factor, since transfection of a GATA-element reporter into MTA1-expressing cells resulted in 10-20-fold increase in reporter expression over poorly MTA1-expressing cells. Since it was reported that nucleosome remodeling histone deacetylase complex (NuRD complex) involved in chromatin remodeling contains MTA1 protein and a MTA1-related protein (MTA2), we examined NuRD complexes for the presence of MTA1 protein and found an association of this protein with histone deacetylase. The results suggest that the MTA1 protein may serve multiple functions in cellular signaling, chromosome remodeling and transcription processes that are important in the progression, invasion and growth of metastatic epithelial cells.