Methotrexate alters the fatty acid composition of NC adenocarcinoma cells in culture

Therapeutic potential of cyclooxygenase-3 inhibitors in the management of glioblastoma

In this study we investigated the expression of COX-1, COX-2 and COX-3 mRNA in C6 glioblastoma and normal brain tissues and the effects of acetaminophen, indomethacin or metamizole treatments on the development of C6 glioblastoma in relation with COX inhibition. Glioblastoma cells were inoculated intracerebrally into frontal lobe of adult male Wistar albino rats. 10 days after inoculation, rats were treated with 150 mg/kg acetaminophen, 10 mg/kg indomethacin or 150 mg/kg metamizole. The tumor size was measured histologically and total RNA was isolated from tumor or normal brain tissue and mRNA levels of COX isoforms were determined by qRT-PCR. Our results showed the presence of COX-1, COX-2 and COX-3 expressions in both C6 glioblastoma and normal brain tissues. In tumor tissues COX-3 expression was significantly higher than normal brain tissue (p < 0.05) while there was no significant difference in COX-1 and COX-2 expressions. Acetaminophen and indomethacin decreased the tumor size by 71 and 43 % by inhibiting COX-3 mRNA expression around 87 and 91 % respectively. For the first time our study proposes a possible relationship between COX-3 mRNA expression and C6 glioblastoma development. We also suggested that the inhibition of COX-3 enzyme may be responsible for decrease in tumor size in part, the mechanism by which acetaminophen and indomethacin decreased rat C6 glioblastoma growth. However, the molecular events responsible for COX-3 effects on tumor development are still unresolved as these drugs exert their anti-cancer effect via both COX-3 dependent and independent mechanisms.

The effect of folate on the methotrexate/indomethacin interaction in a murine cancer cell line

1. The effect of folate on the interaction between methotrexate (a folate analogue) and indomethacin has been examined in murine NC carcinoma cells. 2. Conditioning of NC cells to a physiological (20 nM) folate concentration after culture in a high folate concentration increased the response to methotrexate. The sensitivity of these conditioned cells to methotrexate related inversely to the folate concentration. 3. At 20 nM and 2 microM folate, indomethacin 1 micrograms ml-1 potentiated the cytotoxicity of methotrexate 4 and 8 ng ml-1 (both P < 0.03). 4. When NC cells were incubated with [3H]-methotrexate at 20 nM and 2 microM folate, there was a trend for increased tritium accumulation with indomethacin 0.36 micrograms ml-1 (1 microM; P < 0.01). 5. We conclude that the folate concentration can affect the sensitivity of NC cells to methotrexate, although the degree of potentiation of cytotoxicity by indomethacin remains similar.

Influence of indomethacin and difluoromethylornithine on human tumour growth in nude mice

Biopsy material from six human colorectal carcinomas was transplanted to 114 nude mice. A treatment protocol was established which included no treatment (control, C), indomethacin (I), difluoromethylornithine (D) or a combination of both (ID). The influence of the various drugs on tumour weight and protein kinase CK2 activity was monitored. CK2 activity was measured because in all tumours examined so far the enzyme activity was found to be enhanced several-fold when compared to the non-neoplastic tissue of the same patient. More than half of the investigated tumours showed a conspicuous reduction in weight after drug treatment, and I and the combination of D/I were significantly effective using the mixed model analysis. Furthermore, we have tried to discover whether there is a change in the subcellular localisation of protein kinase CK2 subunits associated with drug treatment. We analysed the tumours and the non-neoplastic control tissues by immunohistochemistry using antibodies directed against the CK2 subunits and against the proliferation marker Mib. In addition, we have also investigated the behaviour of the nucleolar protein B23 which has also been shown to be enhanced several-fold in rapidly proliferating tissue and which is also a substrate for CK2. The immunohistochemical data suggest that, irrespective of the drug treatment and the observed reduction in CK2 activity, the CK2 subunits remain localised in the nucleus.