Correlations of dihydropyrimidine dehydrogenase, thymidine phosphorylase and thymidine kinase activities in strongly and weakly malignant cultured murine neuroblastoma cells

Abstract

The C-1300 neuroblastoma tumor which arises spontaneously in the A/J mouse has been maintained in this mouse strain. Two different cell populations have been recognized in cultured C-1300 mouse neuroblastoma (MNB): (1) round, "neuroblast-like" cells, growing in suspension (poorly attached), that have a highly malignant behavior when injected into the A/J mouse (T1 cells); and (2) flat, "epithelioid" cells that attach well to surfaces and show low malignancy towards the inoculated animals (T2 cells). The specific activities of the pyrimidine metabolizing enzymes thymidine phosphorylase (TP), dihydropyrimidine dehydrogenase (DPD) and thymidine kinase (TK) were examined in both MNB cell lines by a new radiochromatographic method. Enzymatic activities of TP and DPD in the cytosols of T2 (weakly malignant) cells were up to 15 times higher than those of T1 (strongly malignant) cells, whereas the mean TP/DPD activity ratio was 16 in either cell line. TP and DPD activity levels increased with time of growth in culture in T2 cells while no such increase was seen in the T1 cells. Maximal TK activity was similar in both cell lines but dropped more rapidly in the T2 cells as cell densities increased. The enzymatic activity levels of TP and DPD but not of TK correlated inversely with neoplastic expression of MNB cells. The observed patterns of pyrimidine metabolizing enzymes in MNB cells could result in an increased thymidine pool in T1 cells whenever TK activity is suppressed, whereas such conditions would favor the generation of thymine in the T2 cells.

Expression of angiogenic factors and tumor progression in human neuroblastoma

“…PD-ECGF/TP expression in NB tumor samples has not been reported. Williams et al have shown that PD-ECGF/TP enzymatic activity is much higher in weakly malignant than in strongly malignant murine NB cells (Williams and Tuchman 1989). Recent studies have indicated that PD-ECGF/TP expression in some cancers may be an independent prognostic factor rather than an index for angiogenesis (Yamamoto et al 2000).…”

Regulation of Dihydropyrimidine Dehydrogenase and Pyrimidine Nucleoside Phosphorylase Activities by Growth Factors and Subsequent Effects on 5‐Fluorouracil Sensitivity in Tumor Cells

“…[31][32][33] Queener et al 31) demonstrated that DPD activity in rat hepatomas decreased in parallel with the increase in tumor growth rate. In contrast, Williams and Tuchman 32) reported that DPD activity in mouse neuroblastoma cells increased during culture, whereas thymidine kinase activity decreased markedly.…”

“…[31][32][33] Queener et al 31) demonstrated that DPD activity in rat hepatomas decreased in parallel with the increase in tumor growth rate. In contrast, Williams and Tuchman 32) reported that DPD activity in mouse neuroblastoma cells increased during culture, whereas thymidine kinase activity decreased markedly. Takechi et al 33) observed time-dependent increases in DPD activity during the growth of human fibrosarcoma HT-1080 cells and human pancreatic carcinoma MIAPaCa-2 cells in cultures.…”

Involvement of a Substrate Cycle Between Thymidine and Thymidylate in the Regulation of DNA Precursor Pool in Ehrlich Ascites Tumour

“…The enzyme can also act at a reversal direction -conversion of dTdR to thymine. High activity of TP was found in tumour cells [15]. To test if the enzyme is involved in a substrate cycle, the substrate kinetics was determined as follows.…”

“…To obtain cytoplasmic fraction, lysates were prepared as earlier described [14]. The supernatant was immediately used for activity assay of TK1 [14] and TS [15,16], respectively. B) Determination of dTdR substrate kinetics of TK1.…”