Antagonistic interactions between gemcitabine and 5-fluorouracil in the human pancreatic carcinoma cell line Capan-2.

Although the recently-developed Gemcitabine ( GEM) has renewed interest in clinical research in pancreatic carcinoma, it offers modest improvement of tumor-related symptoms and marginal survival advantage, even when combined with other currently-available chemotherapeutic agents such as 5-Fluorouracil (5-FU). We hypothesized that this disappointing result could be due to an interaction between the two drugs affecting cytotoxic activity. We measured in-vitro growth inhibition, cell cycle distribution, gene and protein expression of apoptosis regulators bcl-2, bcl-x and survivin, NF kappa B and telomerase activities of human pancreatic carcinoma cell line Capan-2 following exposure to GEM and 5-FU singly or combined, by MTT assay and median effect analysis, flow cytometry, real-time RT-PCR, Western blotting, electrophoretic mobility shift assay ( EMSA) and telomeric repeat amplification protocol ( TRAP) assay, respectively. We found cell growth to be inhibited by both drugs, decreasing the percentage of cells in S and G(2)/M phases and inducing apoptosis, dependent on the levels of bcl-2, bcl-x(L) and survivin expression in the case of 5-FU, but not for GEM. Moreover, while telomerase activity was reduced equally by both drugs, 5-FU but not GEM effectively downregulated NF kappa B binding activity. Intriguingly, a substantial antagonistic effect was noticed when GEM was combined with 5-FU in the concentration range tested, with the exception of the TRAP assay. These indications of an antagonistic interaction between GEM and 5-FU in some pancreatic cancer context urge further investigation of both genetic and non-genetic differences to identify the variables most relevant for optimal selection and dosing of treatment for the individual patient.