Enhanced death ligand-induced apoptosis in cutaneous SCC cells by treatment with diclofenac/hyaluronic acid correlates with downregulation of c-FLIP.
Actinic keratosis (AK) occurs on sun-exposed skin and may progress to invasive squamous cell carcinoma (SCC). As for its topical treatment, diclofenac/hyaluronic acid (HA) has been recently approved. The NSAID diclofenac is an inhibitor of COX-2; however, its mode of action in cutaneous epithelial cancer cells is largely unknown. Here, the effects of diclofenac/HA were investigated in relation to death ligand-mediated apoptosis (TNF-alpha, TRAIL, and CD95 activation). Whereas diclofenac/HA only moderately induced apoptosis by itself, it resulted in pronounced enhancement of death ligand-mediated apoptosis in sensitive SCC cell lines (3/4). Apoptosis was associated with activation of initiator caspases of the extrinsic pathway (caspase-8/caspase-10). Furthermore, death ligand and diclofenac/HA-mediated apoptosis were blocked by the same caspase inhibitors, indicating related pathways. The proapoptotic effects of diclofenac/HA appeared independent of the p53 pathway. Also, upregulation of death receptors appeared less important; however, strong downregulation of c-FLIP isoforms was seen after diclofenac/HA treatment. The crucial role of c-FLIP was proven through overexpression and knockdown experiments. Thus, induction of apoptosis appears to be highly characteristic of the mode of action of diclofenac/HA, and the therapeutic effect may be related to sensitization of neoplastic keratinocytes for death ligand-induced apoptosis.
Department of Dermatology and Allergy, HTCC Skin Cancer Center Charité, Charité-Universitätsmedizin Berlin, Berlin, Germany.
Lothar F
LF
Fecker
Eggert
E
Stockfleth
Frank K
FK
Braun
Paul M
PM
Rodust
Constanze
C
Schwarz
Anja
A
Köhler
Martin
M
Leverkus
Jürgen
J
Eberle
D000894:Anti-Inflammatory Agents, Non-Steroidal / Q000494:pharmacology; D017209:Apoptosis / Q000187:drug effects* / Q000502:physiology; D053446:CASP8 and FADD-Like Apoptosis Regulating Protein / Q000378:metabolism*; D002294:Carcinoma, Squamous Cell / Q000188:drug therapy* / Q000378:metabolism / Q000473:pathology; D020169:Caspases / Q000378:metabolism; D002461:Cell Line, Transformed; D045744:Cell Line, Tumor; D004008:Diclofenac / Q000494:pharmacology*; D015536:Down-Regulation / Q000187:drug effects / Q000502:physiology; D006801:Humans; D006820:Hyaluronic Acid / Q000494:pharmacology*; D019169:Jurkat Cells; D015603:Keratinocytes / Q000187:drug effects / Q000378:metabolism / Q000473:pathology; D008024:Ligands; D012878:Skin Neoplasms / Q000188:drug therapy* / Q000378:metabolism / Q000473:pathology; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism
D000894:Anti-Inflammatory Agents, Non-Steroidal; D053446:CASP8 and FADD-Like Apoptosis Regulating Protein; C506386:CFLAR protein, human; D008024:Ligands; D016159:Tumor Suppressor Protein p53; D004008:Diclofenac; D006820:Hyaluronic Acid; D020169:Caspases