SMAD5 gene expression, rearrangements, copy number, and amplification at fragile site FRA5C in human hepatocellular carcinoma.
SMAD5 gene expression, rearrangements, copy number, and amplification at fragile site FRA5C in human hepatocellular carcinoma.
复制标题
人肝细胞癌中 SMAD5 基因表达、重排、拷贝数和脆弱位点 FRA5C 的扩增。
DOI：
10.1016/s1476-5586(03)80041-6
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发表时间：
2003
期刊：
影响因子：
--
通讯作者：
Popescu,NicholasC
中科院分区：
文献类型：
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作者：
Zimonjic,DrazenB;Durkin,MarianE;Keck-Waggoner,CatherineL;Park,Sang-Won;Thorgeirsson,SnorriS;Popescu,NicholasC
转化生长因子（TGF）家族成员的信号传导通过细胞内蛋白质的Smad基团从细胞表面转导至细胞核。由于我们检测到5号染色体长臂的改变，我们检测了SMAD 5基因在人肝细胞癌（HCC）细胞系和原发性HCC中的状态。在16个细胞系中，9个细胞系的5号染色体发生了荧光原位杂交（FISH），8个细胞系的SMAD 5基因拷贝数相对于倍性水平增加。不平衡易位和缺失的断点经常发生在SMAD 5位点附近，但显然不会导致SMAD 5的丢失。在一个细胞系中，比较基因组杂交显示DNA拷贝数增加局限于5831区域，我们通过FISH检测到位于脆性位点FRA 5C内的SMAD 5基因的高水平扩增。半定量聚合酶链反应没有显示SMAD 5 DNA水平的变化，在15 17原发性肝癌标本。在17个HCC细胞系中，SMAD 5 mRNA水平通过基因剂量的增加或另一种机制维持或上调。总的来说，我们的结果表明SMAD 5经历拷贝数增加和表达增加，而不是表达丧失，因此表明该基因在HCC中不作为肿瘤抑制基因。SMAD 5高水平扩增和显著过表达的Hep-40肝癌细胞系可能有助于研究SMAD 5与其他基因的相互作用。
Signaling by the transforming growth factor (TGF)family members is transduced from the cell surface to the nucleus by the Smad group of intracellular proteins. Because we detected alterations on the long arm of chromosome 5, we examined the status of theSMAD5gene in human hepatocellular carcinoma (HCC) cell lines and primary HCC. In 16 cell lines, chromosome alterations of chromosome 5 were observed in nine cell lines by fluorescence in situ hybridization (FISH), an increase inSMAD5gene copy number relative to the ploidy level was found in eight lines. The breakpoints in unbalanced translocations and deletions frequently occurred near the SMAD5 locus, but apparently did not cause loss of SMAD5. In one cell line, where comparative genomic hybridization showed DNA copy number gain confined to the region 5831, we detected by FISH high-level amplification of theSMAD5gene located within the fragile site FRA5C. Semiquantitative polymerase chain reaction did not reveal changes in SMAD5 DNA levels in 15 of 17 primary HCC specimens. In 17 HCC cell lines, SMAD5 mRNA levels were either maintained or upregulated by an increase in gene dosage or another mechanism. Collectively, our results show that SMAD5 undergoes copy number gain and increased expression, rather than loss of expression, therefore suggest that this gene does not act as a tumorsuppressor gene in HCC. The Hep-40 HCC cell line with high-level amplification and significant overexpression of SMAD5 may be useful in studying the interaction of SMAD5 with other genes.