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871.
B S Vinod J Antony H H Nair V T Puliyappadamba M Saikia S Shyam Narayanan A Bevin R John Anto 《Cell death & disease》2013,4(2):e505
5-Fluorouracil (5-FU) is the first rationally designed antimetabolite, which achieves its therapeutic efficacy through inhibition of the enzyme thymidylate synthase (TS), which is essential for the synthesis and repair of DNA. However, prolonged exposure to 5-FU induces TS overexpression, which leads to 5-FU resistance in cancer cells. Several studies have identified curcumin as a potent chemosensitizer against chemoresistance induced by various chemotherapeutic drugs. In this study, we report for the first time, with mechanism-based evidences, that curcumin can effectively chemosensitize breast cancer cells to 5-FU, thereby reducing the toxicity and drug resistance. We found that 10 μM 5-FU and 10 μM curcumin induces a synergistic cytotoxic effect in different breast cancer cells, independent of their receptor status, through the enhancement of apoptosis. Curcumin was found to sensitize the breast cancer cells to 5-FU through TS-dependent downregulation of nuclear factor-κB (NF-κB), and this observation was confirmed by silencing TS and inactivating NF-κB, both of which reduced the chemosensitizing efficacy of curcumin. Silencing of TS suppressed 5-FU-induced NF-κB activation, whereas inactivation of NF-κB did not affect 5-FU-induced TS upregulation, confirming that TS is upstream of NF-κB and regulates the activation of NF-κB in 5-FU-induced signaling pathway. Although Akt/PI3kinase and mitogen-activated protein kinase pathways are activated by 5-FU and downregulated by curcumin, they do not have any role in regulating the synergism. As curcumin is a pharmacologically safe and cost-effective compound, its use in combination with 5-FU may improve the therapeutic index of 5-FU, if corroborated by in vivo studies and clinical trials. 相似文献
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The influence of epidermal growth factor on DNA and protein synthesis by human gingival fibroblasts was studied. Synchronized cells treated with epidermal growth factor synthesized considerably greater amounts of DNA relative to 10% fetal calf serum and the peak of synthesis ocurred 6 h later than with serum. Epidermal growth factor caused a dose-dependent stimulation of protein synthesis (proline incorporation). Collagen synthesis remained unaffected and, as a result, the proportion of collagen synthesized decreased with increasing epidermal growth factor concentration. Aspirin and indomethacin did not abrogate these effects, indicating that prostaglandins may not be involved. 相似文献