The enhanced metastatic capacity of an in vivo selected Lewis lung tumor line (LLT-HH) was correlated with changes in cell-associated glycosaminoglycans (GAG) using ultrastructural cytochemistry, flow cytometry and biochemistry. The increase in highly sulphated GAG content on the cell membrane of LLT-HH cells compared to the parent LLT cells was demonstrated cytochemically. Using in vitro [3H]glucosamine labelling of GAG components it was shown that the LLT-HH cells were characterized by a high production of heparan sulphate while the parent LLT line had a high hyaluronic acid-chondroitin sulphate production. The high metastatic phenotype is accompanied by an altered production of cell-associated GAGs.

Animals↗

PubMedDate not supplied

Comparative study on Lewis lung tumour lines with 'low' and 'high' metastatic capacity. III. Glycosaminoglycan synthesis, transport and degradation in cell lines.

The glycosaminoglycans (GAGs) of low (LM) and highly metastatic (HM) cell lines of the Lewis lung tumour (3LL) were compared using [3H]glucosamine labelling techniques. The GAGs isolated from nuclei, cytoplasm, pericellular fractions and medium were analysed by cellulose acetate electrophoresis and by digestion with specific enzymes, and the following conclusions were drawn. 1. Increased cellular uptake and incorporation of [3H]glucosamine into glycoconjugates of the cytoplasm was a typical feature of the highly metastatic cell line after a 48-h labelling. However, there was no elevated radioactivity in glycolipids. 2. Radioactivity of the purified GAGs was two and three times higher in nuclear and cytoplasmic fractions of HM cells than in those of LM cells. There was much less difference between the two cell lines in the pericellular fractions. 3. A definite change from chondroitin sulphate to dermatan sulphate dominancy was recorded in each GAG fraction. Higher heparan sulphate labelling was observed in the cytoplasmic and pericellular GAGs of HM cultures. 4. In the post-labelling period about three times more GAG was present in the extracellular compartment of the HM cultures compared with the LM cultures. 5. In the LM cultures the total GAG-associated radioactivity decreased by 73 per cent in the 48-h chase period whereas in the HM cultures it decreased by only 30 per cent. This indicates a higher rate of GAG degradation in the LM cultures.

Biological Transport↗

PubMedDate not supplied

Enzymatic hydrolysis and biological activity of oligonucleotides containing 5-substituted pyrimidine bases.

Two series of alternating ODNs containing 5-n.alkyl-, alkenyl- and alkynyl-dU and -dC units have been prepared in order to study the kinetics of their hydrolysis by SV PDE and human serum, respectively. Both in (r5dUpdA)10 and (r5dCpdG)6 series the rate of hydrolysis decreased with increasing length of side-chain. Replacement of thymidines by 5-hexynyl-dU in different antisense oligomers resulted in considerably higher biological activity relative to that of the thymidine-containing counterparts.

Blood↗

PubMedDate not supplied

Chromatin alterations and gene function disorder in MC-29 virus-derived hepatoma.

The disorder of gene expression in hepatomas was studied by following certain metabolic alterations (enzyme stimulation, nucleic acid labeling) after glucocorticoid treatment and analyzing the site of action of glucocorticoids. Compared to normal liver, the MC-29 virus-derived transplantable hepatoma (VTH) responded abnormally to glucocorticoids, which failed to stimulate the activity of certain enzymes (glucose-6-phosphatase, aryl hydrocarbon hydroxylase) or to inhibit DNA synthesis. Since the binding capacity of the cytosol steroid receptor was the same in liver and VTH but the interaction between the steroid receptor and DNA was reduced in VTH, it was concluded that structural alterations of chromatin nonhistones--including processed steroid receptor--may be responsible for the lack of physiological responses to steroids in VTH. Furthermore, the increased proportion or repetitive sequences in VTH DNA may be a feature of the disorder of gene regulation in malignant cells.

Animals↗

PubMedDate not supplied

Putative role of dihydropyrimidine dehydrogenase in the toxic side effect of 5-fluorouracil in colorectal cancer patients.

Dihydropyrimidine dehydrogenase (DPD) is the first and rate limiting enzyme in the catabolism of 5-fluorouracil (5-FU). It has been reported from various laboratories that the plasma concentration of 5-FU was influenced by DPD activities in various normal human organs (e.g. liver or lymphocytes). Since the congenital deficiency in DPD caused severe, in some cases lethal, FU-related toxicity, it was decided to collect data about the DPD activity in colorectal cancer patients in order to investigate the possible correlation between the enzyme activity and appearance of the side effects of 5-FU. Assuming that DPD activity in lymphocytes represents the 5-FU catabolic capacity of the organism, DPD activity was determined in the lymphocytes of 48 patients with colorectal cancer after surgery during the therapeutic course with 5-FU and folinic acid. On the basis of the enzyme activity, patients were divided into three categories: low (DPD <5.03 pmol/min/10(6) lymphocytes); medium (DPD = 5.04-13.25 pmol/min/10(6) lymphocytes), and high (DPD > 13.26 pmol/min/10(6) lymphocytes) activity groups. By evaluating the toxic side effects during the 5-FU + folinic acid treatment, the following results were obtained. In the low DPD activity group, 9 of 11 patients had 5-FU-related side effects (mucositis, diarrhea, myelotoxicity, angina pectoris, hypertension). In 3 patients, no change of the therapy was needed, in 3 patients symptoms could be reversed by dose reduction of 5-FU while in 3 patients interruption of 5-FU therapy was needed. In the medium DPD activity group, mild toxicity (diarrhea, transitory hypertension) occurred in 5 of 29 and in the high activity group (diarrhea) in 1 of 8 patients, respectively. In these last two groups, no dose reduction of 5-FU was necessary. The present study furnished further evidence for the possible correlation between the 5-FU side effects and DPD function. Consequently, it is recommended to measure DPD activity prior to 5-FU based chemotherapy, which might be helpful in avoiding drug-related toxicity by adjusting the dose of 5-FU individually.

Adult↗

PubMedDate not supplied

Alterations in nucleoside monophosphate concentrations in 3LL tumours after combined treatment with tiazofurin and 5-hexyl-2'-deoxyuridine.

The IMP and GMP concentrations were compared after treatment with tiazofurin alone and in combination with 5-hexyl-2'-deoxyuridine (HUdR) in 3LL-HH adenocarcinoma in vivo. The elevation in IMP/GMP ratio, indicating guanylate depletion and increase of inosine-5'-monophosphate concentration, showed a dose dependence and was the highest at the 7th hour after treatment with tiazofurin. HUdR application alone caused only a modest change in the nucleotide concentration of LL-HH tumour. However, the rise of IMP but not the reduction of guanylate concentration induced by tiazofurin was remarkably mitigated by HUdR treatment, without affecting the antitumour potency of tiazofurin. Thus HUdR showed modifying activity on some of the tiazofurin-induced changes in nucleotide metabolism which appeared not to be associated with the antiproliferative activity of tiazofurin. It follows that reduced GMP concentration and not the elevation of IMP/GMP ratio could predict therapeutic responses to tiazofurin.

Animals↗