Fukuda M, Ishii A, Yasutomo Y, Shimada N, Ishikawa N, Hanai N, Nagata N, Irimura T, Nicolson G L, Kimura N
Department of Molecular Biology, Tokyo Metropolitan Institute of Gerontology, Japan.
Int J Cancer. 1996 Feb 8;65(4):531-7. doi: 10.1002/(SICI)1097-0215(19960208)65:4<531::AID-IJC23>3.0.CO;2-B.
The nm23 gene [encoding nucleoside diphosphate kinase (NDPK)] may act as a metastasis suppressor in certain tumor cells. We investigated the role of NDPK isoforms (alpha and beta) in the metastatic processes, using rat mammary-adenocarcinoma cell lines of poor (MTC) and high (MTLn3) spontaneous metastatic potential respectively. In these cell lines, as in most rat tissues, the alpha isoform (nm23-H2 homolog) was more highly expressed than the beta isoform (nm23-H1 homolog) at the mRNA and protein levels. When examined by Northern- and Western-blot analyses, expression of the 2 isoforms was reduced in highly metastatic MTLn3 cells compared with poorly metastatic MTC cells. The reduced expression was also associated with diminished NDPK-enzyme activity in the cell extracts. Southern-blot and RT-PCR-SSCP analyses suggested that the 2 genes were not grossly altered or mutated in their translation regions. MTLn3 cell clones transfected with NDPKalpha or NDPKbeta cDNA were all tumorigenic when implanted into the mammary fat pad of syngeneic rats. Among those, only clones transfected with the NDPKalpha gene exhibited reduced lung metastasis in a spontaneous metastasis assay.
nm23基因[编码核苷二磷酸激酶（NDPK）]可能在某些肿瘤细胞中作为转移抑制因子发挥作用。我们分别使用具有低（MTC）和高（MTLn3）自发转移潜能的大鼠乳腺腺癌细胞系，研究了NDPK同工型（α和β）在转移过程中的作用。在这些细胞系中，与大多数大鼠组织一样，α同工型（nm23-H2同源物）在mRNA和蛋白质水平上的表达均高于β同工型（nm23-H1同源物）。通过Northern印迹和Western印迹分析检测发现，与低转移潜能的MTC细胞相比，高转移潜能的MTLn3细胞中这两种同工型的表达均降低。表达降低还与细胞提取物中NDPK酶活性的降低有关。Southern印迹和RT-PCR-SSCP分析表明，这两个基因在其翻译区域没有明显改变或突变。将NDPKα或NDPKβ cDNA转染的MTLn3细胞克隆植入同基因大鼠的乳腺脂肪垫后均具有致瘤性。其中，在自发转移实验中，只有转染NDPKα基因的克隆表现出肺转移减少。
