Department of Surgical Oncology, Gifu University Graduate School of Medicine, Gifu, Japan.
Pancreas. 2010 Nov;39(8):1284-92. doi: 10.1097/MPA.0b013e3181dec17d.
Thymidylate synthase (TS) inhibitors activate human equilibrative nucleoside transporter 1. We evaluated the contribution of TS expression to determine a treatment method providing an effect from gemcitabine (GEM).
The expression of 5-fluorouracil (5-FU) and GEM metabolic factors (5-FU: TS, dihydropyrimidine dehydrogenase, orotate phosphoribosyltransferase; GEM: human equilibrative nucleoside transporter 1, deoxycytidine kinase, cytidine deaminase, 5'-nucleotidase) were studied in 7 pancreatic cancer cell lines by Western blotting, and drug resistance was evaluated by 3-[4,5-dimethylthiazol]-2,5-dephenyl tetrazolium bromide assay. The expression of 5-FU factors was observed immunohistochemically in resected pancreatic cancer specimens.
Gemcitabine concentrations that inhibited colony formation by 50% correlated with TS protein expression (P = 0.0169). With a 5-FU non-growth-inhibiting dose, GEM concentrations that inhibited colony formation by 50% were significantly reduced by one fourth to one tenth. Knockout of TS expression by small interfering RNA decreased resistance to GEM in the cell lines (P = 0.0019). Immunohistochemically, TS expression related to disease-free survival time of patients treated with GEM (P = 0.0224). A high expression of 5-FU factors was detected: orotate phosphoribosyltransferase: differentiated cases (P = 0.0137), lower T factor (P = 0.0411); dihydropyrimidine dehydrogenase: nerve invasion (P = 0.0188), lymph node recurrence (P = 0.0253); TS, positive N factor (P = 0.0061).
The expression of TS provides an alternative source of substrate for DNA synthesis and positively correlates with GEM resistance and shortened patient survival.
胸苷酸合成酶（TS）抑制剂激活人平衡核苷转运蛋白 1。我们评估了 TS 表达的贡献，以确定一种提供吉西他滨（GEM）疗效的治疗方法。
通过 Western blot 研究了 7 种胰腺癌细胞系中 5-氟尿嘧啶（5-FU）和 GEM 代谢因子（5-FU：TS、二氢嘧啶脱氢酶、乳清酸磷酸核糖转移酶；GEM：人平衡核苷转运蛋白 1、脱氧胞苷激酶、胞苷脱氨酶、5'-核苷酸酶）的表达，并通过 3-[4,5-二甲基噻唑]-2,5-二苯基四唑溴盐测定评估药物耐药性。免疫组织化学观察了手术切除的胰腺癌标本中 5-FU 因子的表达。
抑制集落形成 50%的吉西他滨浓度与 TS 蛋白表达相关（P=0.0169）。在非生长抑制剂量的 5-FU 下，抑制集落形成 50%的 GEM 浓度减少了四分之一到十分之一。通过小干扰 RNA 敲低 TS 表达降低了细胞系对 GEM 的耐药性（P=0.0019）。免疫组织化学显示，TS 表达与接受 GEM 治疗的患者无病生存时间相关（P=0.0224）。检测到高表达的 5-FU 因子：乳清酸磷酸核糖转移酶：分化病例（P=0.0137），T 因子较低（P=0.0411）；二氢嘧啶脱氢酶：神经侵犯（P=0.0188），淋巴结复发（P=0.0253）；TS，阳性 N 因子（P=0.0061）。
TS 的表达为 DNA 合成提供了替代的底物来源，并与 GEM 耐药性和患者生存时间缩短呈正相关。
