Phenotypic heterogeneity in cultured human head and neck squamous cell carcinoma lines with low-level methotrexate resistance.
Phenotypic heterogeneity in cultured human head and neck squamous cell carcinoma lines with low-level methotrexate resistance.
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发表时间：
1985-12
期刊：
影响因子：
11.2
通讯作者：
A. Rosowsky;J. Wright;C. Cucchi;J. Lippke;R. Tantravahi;T. Ervin;E. Frei
中科院分区：
文献类型：
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作者：
A. Rosowsky;J. Wright;C. Cucchi;J. Lippke;R. Tantravahi;T. Ervin;E. Frei
低水平甲氨蝶呤 (MTX) 耐药性（小于 20 倍）是通过逐渐选择压力诱导的，在从先前未接受过 MTX 治疗的患者活检中培养的 4 个人类头颈鳞状细胞癌细胞系中诱导了低水平甲氨蝶呤 (MTX) 耐药性（小于 20 倍）。每个亲本和抗性品系均针对 MTX 摄取和聚谷氨酰化、二氢叶酸还原酶 (DHFR) 含量和生长速率进行了表征。通过斑点印迹测定中的质粒互补DNA杂交来分析相对DHFR基因拷贝数和DHFR相关细胞质信使RNA的量，并将其与基因产物的量相关联。克隆抗性系并不是为了在体外模拟体内环境中可能存在的条件，其中肿瘤中可能存在多种抗性细胞亚群。该研究仅限于具有低水平耐药性的细胞，因为这些细胞可能是临床上最相关的类型。在四种抗性品系中，一种在 MTX 摄取和多谷氨酰化方面显示出严重缺陷，另一种是 DHFR 过量生产，在摄取和多谷氨酰化方面仅发生很小的变化，第三种同样是 DHFR 过量生产，但也显示出较低的 MTX 摄取，第四种除了生长速度外几乎没有改变。这些细胞体外耐药表型的多样性表明，接受 MTX 治疗的头颈癌患者的体内耐药性可能类似地涉及多种机制，并且使用 MTX 或其他抗叶酸剂的进一步治疗干预应考虑到这一点。
Low-level methotrexate (MTX) resistance (less than 20-fold) was induced by gradual selection pressure in four human head and neck squamous cell carcinoma lines established in culture from biopsies of patients not previously treated with MTX. Each parental and resistant line was characterized with respect to MTX uptake and polyglutamylation, dihydrofolate reductase (DHFR) content, and growth rate. Relative DHFR gene copy numbers and amounts of DHFR-related cytoplasmic messenger RNA were analyzed by plasmid complementary DNA hybridization in a dot blot assay and were correlated with the amount of gene product. The resistant lines were not cloned in order to simulate in vitro the conditions which might exist in an in vivo setting, where multiple resistant subpopulations of cells may be present in a tumor. The study was restricted to cells with low-level resistance since these are likely to be the clinically most relevant type. Of the four resistant lines characterized, one showed a severe defect in MTX uptake and polyglutamylation, another was a DHFR overproducer with only small changes in uptake and polyglutamylation, a third was likewise a DHFR overproducer but also showed lower MTX uptake, and the fourth was minimally altered except for growth rate. The diversity in resistance phenotype among these cells in vitro suggests that in vivo resistance in patients with head and neck carcinoma who are treated with MTX may similarly involve multiple mechanisms and that further therapeutic intervention using MTX or other antifolates should take this into account.