Cellular and pharmacogenetics foundation of synergistic interaction of pemetrexed and gemcitabine in human non-small-cell lung cancer cells.
Gemcitabine and pemetrexed are effective agents in the treatment of non-small-cell lung cancer (NSCLC), and the present study investigates cellular and genetic aspects of their interaction against A549, Calu-1, and Calu-6 cells. Cells were treated with pemetrexed and gemcitabine, and their interaction was assessed using the combination index. The role of drug metabolism in gemcitabine cytotoxicity was examined with inhibitors of deoxycytidine kinase (dCK), 5'-nucleotidase, and cytidine deaminase, whereas the role of pemetrexed targets, thymidylate synthase (TS), dihydrofolate reductase (DHFR), and glycinamide ribonucleotide formyltransferase (GARFT) in drug chemosensitivity was analyzed in cytotoxicity rescue studies. The effect of gemcitabine and pemetrexed on Akt phosphorylation was investigated with enzyme-linked immunosorbent assay, whereas quantitative polymerase chain reaction (PCR) was used to study target gene-expression profiles and its modulation by each drug. Synergistic cytotoxicity was demonstrated, and pemetrexed significantly decreased the amount of phosphorylated Akt, enhanced apoptosis, and increased the expression of dCK in A549 and Calu-6 cells, as well as the expression of the human nucleoside equilibrative transporter 1 (hENT1) in all cell lines. PCR demonstrated a correlation between dCK expression and gemcitabine sensitivity, whereas expression of TS, DHFR, and GARFT was predictive of pemetrexed chemosensitivity. These data demonstrated that 1) gemcitabine and pemetrexed synergistically interact against NSCLC cells through the suppression of Akt phosphorylation and induction of apoptosis; 2) the gene expression profile of critical genes may predict for drug chemosensitivity; and 3) pemetrexed enhances dCK and hENT1 expression, thus suggesting the role of gene-expression modulation for rational development of chemotherapy combinations.
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CHEMICAL CHEMICAL CHEMICAL CHEMICAL CHEMICAL CHEMICAL CHEMICAL CHEMICAL CHEMICAL CHEMICAL CHEMICAL CHEMICAL CHEMICAL CHEMICAL CHEMICAL CHEMICAL CHEMICAL CHEMICAL CHEMICAL CHEMICAL GENE-N GENE-Y GENE-Y GENE-Y GENE-Y GENE-Y GENE-Y GENE-Y GENE-N GENE-Y GENE-Y GENE-Y GENE-Y GENE-Y GENE-Y GENE-Y GENE-Y GENE-Y GENE-Y GENE-Y GENE-Y GENE-N
Gemcitabine pemetrexed nucleoside gemcitabine pemetrexed gemcitabine pemetrexed pemetrexed pemetrexed pemetrexed gemcitabine gemcitabine deoxycytidine cytidine thymidylate dihydrofolate glycinamide ribonucleotide gemcitabine pemetrexed gemcitabine phosphorylated Akt dCK human nucleoside equilibrative transporter 1 hENT1 dCK TS DHFR GARFT Akt dCK hENT1 deoxycytidine kinase dCK 5'-nucleotidase cytidine deaminase thymidylate synthase TS dihydrofolate reductase DHFR glycinamide ribonucleotide formyltransferase GARFT Akt