应用氟尿嘧啶治疗胃癌患者预后与其癌组织中尿嘧啶核苷磷酸化酶基因的高表达相关性研究

目的:分析尿嘧啶核苷磷酸化酶基因表达水平与胃癌、肺癌和结肠癌的预后相关性。方法:采用RT-PCR法检测了28例胃癌、14例肺癌和22例结肠癌组织及其远癌正常组织中尿嘧啶核苷磷酸化酶(UP)基因的表达。结果:对28例胃癌组织及其远癌正常组织检测发现,有20例UP基因的表达比正常组织增高,另8例UP基因的表达比正常组织低或二者相等。所有这些胃癌患者均在手术前、后接受了氟尿嘧啶的治疗。胃癌组织中UP基因表达增高的患者比UP基因表达正常或降低的患者有较好的生存率;相反,大多数的结肠癌(16例)和所有的肺癌患者未接受氟尿嘧啶的治疗,且大部分的结肠癌(12例)和肺癌(10例)样本显示癌组织中UP基因呈低表达。肺癌和结肠癌组织相对于其远癌正常组织中UP基因的不同表达与患者的生存率不相关。结论:胃癌组织相对于其远癌正常组织的UP基因的表达水平可作为判断接受氟尿嘧啶的治疗的胃癌患者预后的一个指标。     

Cytokines Induce Uridine Phosphorylase in Mouse Colon 26 Carcinoma Cells and Make the Cells More Susceptible to 5'-Deoxy-5-fluorouridine

The antiproliferative activity of 5-fluorouracil (5-FUra) and 5'-deoxy-5-fluorouridine (5'-dFUrd), used in combination with typical cytokines and growth factors, was investigated in mouse colon 26 carcinoma cells. Tumor necrosis factor α (TNFα), interleukin-1a (IL-1α), and interferon γ (IFNγ) at low doses showing < 50% inhibition of cell growth by themselves enhanced the susceptibility of the cells to the activity of 5'-dFUrd. In particular, a mixture of these cytokines greatly enhanced the activity of 5'-dFUrd and 5-FUra by up to 12.4- and 2.7-fold, respectively, whereas the activity of other cytostatics was only slightly changed (< 1.5-fold). Basic fibroblast growth factor also increased the susceptibility, but only to 5'-dFUrd. This preferential enhancement of the activity of 5'-dFUrd would be due to induction by the cytokines of uridine phosphorylase (Urd Pase), by which 5'-dFUrd is converted to 5-FUra. TNFα, IL-1α, IFNγ, and a mixture of these factors increased the enzyme activity by up to 3.7-fold in colon 26 cells. Consequently, the anabolism of 5'-dFUrd to fluoronucleotides and the incorporation of 5-FUra into RNA in colon 26 cells were increased by TNFα treatment. In addition, the increase by the cytokine mixture in the susceptibility to 5'-dFUrd was abolished by an inhibitor of Urd Pase, 2,2'-anhydro-5-ethyluridine. These results indicate that induction of Urd Pase activity by cytokines is a critical event that increases the susceptibility to 5'-dFUrd.     

Effect of 5-(phenylselenenyl)acyclouridine, an inhibitor of uridine phosphorylase, on plasma concentration of uridine released from 2′,3′,5′-tri-O-acetyluridine, a prodrug of uridine: relevance to uridine rescue in chemotherapy

Purpose: The purpose of this investigation was to study the effects of combining oral 5-(phenylselenenyl)acyclouridine (PSAU) with 2′,3′,5′-tri-O-acetyluridine (TAU) on the levels of plasma uridine in mice. PSAU is a new lipophilic and potent inhibitor of uridine phosphorylase (UrdPase, EC 2.4.2.3), the enzyme responsible for uridine catabolism. PSAU has 100% oral bioavailability and is a powerful enhancer of the bioavailability of oral uridine. TAU is a prodrug of uridine and a far superior source of uridine than uridine itself. Methods: Oral TAU was administered to mice alone or with PSAU. The plasma levels of uridine and its catabolites as well as PSAU were measured using HPLC and pharmacokinetic analysis was performed. Results: Oral administration of 2000 mg/kg TAU increased plasma uridine by over 250-fold with an area under the curve (AUC) of 754 μmol · h/l. Coadministration of PSAU at 30 and 120 mg/kg with TAU further improved the bioavailability of plasma uridine resulting from the administration of TAU alone by 1.7- and 3.9-fold, respectively, and reduced the C_max and AUC of plasma uracil. Conclusion: The exceptional effectiveness of PSAU plus TAU in elevating and sustaining a high plasma uridine concentration could be useful in the management of medical disorders that are remedied by administration of uridine, as well as the rescue or protection from host toxicities of various chemotherapeutic pyrimidine analogues. Received: 10 November 1999 / Accepted: 14 March 2000     

Intratumoral pyrimidine nucleoside phosphorylase (pynpase) activity predicts a selective effect of adjuvant 5’-deoxy-5-fluorouridine (5’ dfur) on breast cancer

BACKGROUND: Pyrimidine nucleoside phosphorylase (PyNPase) is the enzyme that converts 5'-deoxy-5-fluorouracil (5'DFUR) to 5-fluorouracil (5FU). Its activity in cancer tissue may correlate with the selective antitumor activity of 5'DFUR in breast cancer. METHODS: Two hundred and sixteen T2 breast cancer patients were treated consecutively with surgery followed by 5'DFUR (600 mg/body/day) + tamoxifen (20 mg/body/day) for 2 years. PyNPase activity in breast cancer tissue, determined by high-performance liquid chromatography, ranged from 4.2-626.0 micrograms FU/mg protein/hr (mean +/- SD, 203.5 +/- 122.4), and the examined patients were divided into two groups: group A (high PyNPase group), cases with the PyNPase activity equal to or more than the mean value of 203.5 micrograms FU/mg protein/hr, and group B (low PyNPase group), cases with activity less than the mean value. RESULTS: Although there was no difference in relapse-free survival (RFS) between groups A and B, among node-positive patients (n = 83) those in group A tended to have a longer RFS. When divided into subgroups according to estrogen receptor (ER) status, among node-positive and ER-positive tumors (n = 49), the RFS was significantly better in group A than in group B (p < 0.05). CONCLUSION: Intratumoral PyNPase activity might be of use as a predictor of the effect of adjuvant 5'DFUR on breast cancer.     

Comparative aspects of purine metabolism in some African trypanosomes

Some enzymes of purine salvage were detected in the cell-free preparations from bloodstream forms of African trypanosomes: Trypanosoma vivax; T. brucei and T. congolense. Extracts of trypanosomes cleave adenosine and inosine hydrolytically except in T. congolense where adenosine cleavage was mediated by a phosphorylase. All the trypanosomes apparently lacked adenosine deaminase. Adenine aminohydrolase was found only in T. vivax while adenosine monophosphate deaminase was detected in T. brucei and T. congolense. There was no detectable adenosine kinase activity in T. brucei. A pathway is proposed for the metabolism of purines in these trypanosomes.     

Role of growth hormone in regulation of polynucleotide-phosphorylase activity in rat liver

Hypophysectomy in rats is followed by a significant increase in polynucleotide-phosphorylase (PNPase) activity in ribosomal fractions of the liver. Injection of growth hormone into hypophysectomized animals leads to inhibition of PNPase activity. Within the dose range from 5 to 100 g the dose—effect curve is linear. The action of growth hormone is most marked 18h after a single injection.Laboratory of Enzymology, Academy of Medical Sciences of the USSR, and Laboratory of Biological Standardization of Hormones, Institute of Experimental Endocrinology and Hormone Chemistry, Academy of Medical Sciences of the USSR, Moscow. Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 89, No. 2, pp. 162–163, February, 1980.     

Activation of Phosphorylase by Anoxia and Dinitrophenol in Rabbit Colon Smooth Muscle: Relation to Release of Calcium from Mitochondria

Abstract: The effect of anoxia or 2,4-dinitrophenol (DNP) on the phosphorylase a activity and the calcium content in subcellular fractions from rabbit colon smooth muscle was studied. Anoxia for 15 min. as well as DNP (6.6 × 10^?5 M) for 5 min. increased the phosphorylase a activity. The calcium content in the mitochondrial subfraction, prepared from the anoxic- or DNP-treated intact muscle and determined by atomic absorption spectroscopy, was reduced. The calcium content in the nuclear and the microsomal fractions was not changed in preparations with a normal Ca-content. When the muscle was incubated for 60 min. in a Ca²⁺-free medium containing 2.0 mM EGTA, the calcium content in the mitochondrial fraction was reduced to 38 % of the control. This calcium level was still further reduced and the phosphorylase a activity was increased by DNP in this “Ca-poor” muscle. In these preparations the Ca-content of the microsomal + supernatant fraction increased. Only when the muscle was incubated, initially, in an anoxic medium containing 0.1 mM Ca²⁺ for 120 min. and, subsequently, in an oxygenated medium containing 0.1 mM Ca²⁺ for 20 min., DNP failed to activate phosphorylase and to decrease the calcium content in the mitochondrial fraction. These results indicate that mitochondrial Ca²⁺ release is one of the regulatory factors of the anoxic-induced glycogenolysis.     

中国与北欧乳癌组织TP、TS、DPD mRNA表达比较

目的:检测北欧和中国人乳癌患者TP、TS、DPD mRNA水平的差异。方法:应用定量RT-PCR法检测北欧乳癌患者中3种指标的表达,用半定量RT-PCR法检测中国乳癌患者中3种指标的表达。结果:仅中国标本TP mRNA水平显示肿瘤组织(0.44±0.23)高于正常组织(0.15±0.16),TP mRNA高表达率中国患者(56.67%)高于北欧患者(34.12%),60岁以下患者这种差异消失。TS、DPD mRNA高表达率在二地区无差异。结论:北欧和中国乳癌患者之间TP、TS、DPD mRNA表达无明显种族差异。