Ishikawa Y, Kubota T, Otani Y, Watanabe M, Teramoto T, Kumai K, Takechi T, Okabe H, Fukushima M, Kitajima M
Department of Surgery, School of Medicine, Keio University, Tokyo, Japan.
Anticancer Res. 1999 Nov-Dec;19(6C):5635-40.
The measurement of thymidylate synthetase (TS) and dihydropyrimidine dehydrogenase (DPD) enzymatic activities and mRNA levels in tumors may be useful in predicting tumor sensitivity to 5-fluorouracil (5-FU). Forty-one patients with advanced gastric cancer gave informed consent and were enrolled in this study. Biopsy specimens of gastric cancer were obtained preoperatively through gastrofiberscopy and used to determine TS and DPD mRNA levels. We also measured TS and DPD enzymatic activities and mRNA levels in surgically resected gastric cancer samples, as well as in adjacent normal gastric mucosa. TS and DPD activities were measured using the TS-binding assay and a radioenzymatic assay, respectively, while mRNA levels were measured by semi-quantitative reverse transcription-PCR (RT-PCR) co-amplified with glyceraldehyde-3-phosphate dehydrogenase (GAPDH) as an internal standard. In resected tumor specimens, TS and DPD activities ranged from 7.1 to 176.6 fmol/mg protein and from 3.6 to 99.8 pmol/min/mg protein, respectively, while TS and DPD mRNA levels ranged from 0.50 to 21.12 and from 0.014 to 7:22, respectively. There were no significant correlations between TS/DPD levels and other clinicopathological factors, except for low DPD mRNA levels in undifferentiated carcinoma. Both TS activity and mRNA levels were significantly higher in tumor tissues compared to normal adjacent mucosa. In contrast, there was no significant difference between tumoral and non-tumoral DPD activity, although tumor tissue showed significantly lower DPD mRNA levels than non-tumoral tissue. High tumoral TS mRNA levels in preoperative biopsy specimens from patients with stage III/IV was associated with poor survival outcome after surgery compared with patients with low tumoral TS mRNA levels. In contrast, DPD levels had no influence on prognosis. We conclude that high tumoral TS levels and low tumoral DPD mRNA may indicate the selective cytotoxicity of 5-FU on gastric cancer, and that tumoral TS mRNA levels may be a prognostic factor for patients with stage III/IV gastric cancer.
测定肿瘤中的胸苷酸合成酶（TS）和二氢嘧啶脱氢酶（DPD）的酶活性及mRNA水平，可能有助于预测肿瘤对5-氟尿嘧啶（5-FU）的敏感性。41例晚期胃癌患者签署知情同意书后纳入本研究。术前通过纤维胃镜获取胃癌活检标本，用于测定TS和DPD的mRNA水平。我们还测定了手术切除的胃癌样本以及相邻正常胃黏膜中TS和DPD的酶活性及mRNA水平。TS活性采用TS结合试验测定，DPD活性采用放射酶法测定，而mRNA水平通过以甘油醛-3-磷酸脱氢酶（GAPDH）作为内参进行半定量逆转录聚合酶链反应（RT-PCR）测定。在切除的肿瘤标本中，TS和DPD活性分别为7.1至176.6 fmol/mg蛋白和3.6至99.8 pmol/min/mg蛋白，而TS和DPD的mRNA水平分别为0.50至21.12和0.014至7.22。除未分化癌中DPD mRNA水平较低外，TS/DPD水平与其他临床病理因素之间无显著相关性。与相邻正常黏膜相比，肿瘤组织中的TS活性和mRNA水平均显著升高。相反，肿瘤组织和非肿瘤组织的DPD活性无显著差异，尽管肿瘤组织的DPD mRNA水平显著低于非肿瘤组织。与肿瘤TS mRNA水平低的患者相比，III/IV期患者术前活检标本中肿瘤TS mRNA水平高与术后生存预后差相关。相反，DPD水平对预后无影响。我们得出结论，肿瘤TS水平高和肿瘤DPD mRNA水平低可能表明5-FU对胃癌具有选择性细胞毒性，并且肿瘤TS mRNA水平可能是III/IV期胃癌患者的一个预后因素。
