Cytotoxic and antiproliferative effects of the nonsteroidal anti-inflammatory drug diclofenac in human tumour cell lines

Diclofenac is one of the most prescribed non-steroidal anti-inflammatory drugs (NSAIDs) for acute and chronic inflammatory conditions. Taking into consideration the extensive use of diclofenac, the crucial role of inflammation in tumorigenesis and data on the effects of NSAIDs on cancer cell lines, we investigated the cytotoxic potential of diclofenac on a panel of human cell lines originating from breast (MCF-7), cervical (HeLa) and colorectal cancer (HT-29). The cytotoxicity was assessed using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) dye reduction assay and the half maximal inhibitory concentrations (IC50) were determined. Diclofenac had higher potency against MCF-7 and HT-29 than against HeLa. The cellular and nuclear changes were examined by fluorescent microscopy using 4′,6′-diamino-2-phenylindole (DAPI) stain and acridine orange/ethidium bromide (AO/EB). The wound-healing scratch assay showed significant reduction in the migration capacity of all tested cancer cell lines. The observed antineoplastic activity implies that the anticancer potential of NSAIDs and diclofenac, in particular, necessitates further investigation.