Expression of methylthioadenosine phosphorylase cDNA in p16(-), MTAP(-) malignant cells: Restoration of methylthioadenosine phosphorylase-dependent salvage pathways and alterations of sensitivity to inhibitors of purine de novo synthesis
Expression of methylthioadenosine phosphorylase cDNA in p16(-), MTAP(-) malignant cells: Restoration of methylthioadenosine phosphorylase-dependent salvage pathways and alterations of sensitivity to inhibitors of purine de novo synthesis
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DOI：
10.1124/mol.52.5.903
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发表时间：
1997-11-01
影响因子：
3.6
通讯作者：
Savarese, TM
中科院分区：
文献类型：
--
作者：
Chen, ZH;Olopade, OI;Savarese, TM
5'-脱氧-5'-甲硫腺苷磷酸化酶 (MTAP) 参与将多胺合成副产物 5'-脱氧-5'-甲硫腺苷的腺嘌呤和甲硫基部分分别回收为腺嘌呤核苷酸和甲硫氨酸。编码 MTAP 的基因 MTAP 经常与肿瘤抑制基因 p16 一起在染色体 9p21 区域纯合缺失的恶性细胞中共同缺失。 p16(-)、MTAP(-) 恶性细胞已被证明比 p16(+)、MTAP(+) 细胞更容易受到抗叶酸剂（如甲氨蝶呤）的嘌呤从头抑制作用的影响。为了了解其潜在机制，我们通过转染 MTAP cDNA，将 MTAP 活性重新引入两个 p16(-)、MTAP(-) 细胞模型系统（MiaPaCa-2 和 PANC-1 人胰腺癌细胞系）中。结果发现，用 MTAP cDNA 转染 (i) 恢复了 MTAP 依赖性腺嘌呤和甲硫氨酸补救途径，(ii) 降低了嘌呤从头合成率（比野生型或假转染的对应物低 18-47%），以及 (iii) 降低了细胞对甲氨蝶呤和甲氨蝶呤的抗嘌呤相关生长抑制作用的敏感性。 重氮丝氨酸。这些数据支持这样的假设：MTAP依赖性腺嘌呤补救途径的运行使得MTAP(+)细胞对从头嘌呤合成的依赖性降低，因此比MTAP(-)恶性细胞更不易受药物(例如抗叶酸剂)生长抑制作用的影响，其作用机制部分涉及从头嘌呤途径。这些发现为某些抗叶酸药物可能对 MTAP 缺乏的恶性肿瘤具有相对选择性的作用提供了理论基础。
5'-Deoxy-5'-methylthioadenosine phosphorylase (MTAP) is involved in the salvage of adenine and methylthio moieties of 5'-deoxy-5'-methylthioadenosine, a byproduct of polyamine synthesis, to adenine nucleotides and methionine, respectively. The gene encoding MTAP, MTAP, is frequently codeleted along with the tumor suppressor gene p16 in malignant cells bearing homozygous deletions in the chromosome 9p21 region. p16(-), MTAP(-) malignant cells have been shown to be more susceptible to the purine de novo inhibitory actions of antifolates such as methotrexate than are p16(+), MTAP(+) cells. To understand the underlying mechanism, we reintroduced MTAP activity into two p16(-), MTAP(-) cell model systems, the MiaPaCa-2 and PANC-1 human pancreatic carcinoma cell lines, by transfection with MTAP cDNA. It was found that transfection with MTAP cDNA (i) restored both the MTAP-dependent adenine and methionine salvage pathways, (ii) decreased the rates of purine de novo synthesis (18-47% lower than the wild-type or sham-transfected counterparts), and (iii) decreased cellular sensitivity to the antipurine-related growth-inhibitory actions of methotrexate and azaserine. These data support the hypothesis that operation of the MTAP-dependent adenine salvage pathway renders MTAP(+) cells less dependent on de novo purine synthesis and hence less susceptible than MTAP(-) malignant cells to the growth-inhibitory actions of agents (e.g. antifolates) whose mechanism of action in part involves the de novo purine pathway. These findings provide a theoretical basis for the relatively selective action certain antifolates may have against MTAP-deficient malignancies.