CNR ExploRA

Articolo in rivista, 2011, ENG, 10.1016/j.jnutbio.2010.08.004

Docosahexaenoic acid reverts resistance to UV-induced apoptosis in human keratinocytes: involvement of COX-2 and HuR

Simona Serini (a); Valentina Donato (b); Elisabetta Piccioni (a); Sonia Trombino (b); Giovanni Monego (c); Amelia Toesca (c); Idanna Innocenti (a); Mauro Missori (d); Marco De Spirito (e); Leonardo Celleno (f); Elena Fasano (a); Franco O. Ranelletti (g); Gabriella Calviello (a)

(a) Institute of General Pathology, School of Medicine, Catholic University, 1 - 00168 Rome, Italy (b) Department of Pharmaceutical Sciences, Calabria University, Arcavacata di Rende, Cosenza, Italy (c) Institute of Human Anatomy, Catholic University, Rome, Italy (d) ISC-CNR - Department, Tor Vergata, Rome, Italy (e) Institute of Physics, Catholic University, 1 - 00168 Rome, Italy (f) Institute of Dermatology, and Cosmetological Research Centre, Catholic University, 1 - 00168 Rome, Italy (g) Institute of Histology, Catholic University, 1 - 00168 Rome, Italy

The dramatic increase in the incidence of nonmelanoma skin cancer over the last decades has been related to the augmented exposure to ultraviolet (UV) radiation (UVR). It is known that apoptosis is induced as a protective mechanism after the acute irradiation of keratinocytes, whereas apoptotic resistance and carcinogenesis may follow the chronic exposure to UVR. We found that not all the human keratinocytes lines studied underwent apoptosis following acute exposure to UVR (10-60 mJ/cm2). Whereas UVR induced apoptosis in the HaCaT cells, NCTC 2544 and nr-HaCaT cells showed apoptosis resistance. The cytokeratin pattern of the apoptosis-resistant cells indicated that they possessed a degree of differentiation lower than that of HaCaT cells. They also showed an enhanced expression of cyclooxygenase-2 (COX-2), an early marker of carcinogenesis in various tissues, including skin. n-3 polyunsaturated fatty acids have drawn increasing interest as nutritional factors with the potential to reduce UVR carcinogenesis, and since they are apoptosis inducers and COX-2 inhibitors in cancer cells, we investigated the ability of n-3 polyunsaturated fatty acids to influence the resistance to UVR-induced apoptosis in keratinocytes. We observed that docosahexaenoic acid (DHA) reverted the resistance of nr-HaCaT cells to UVR-induced apoptosis, increasing the Bax/Bcl-2 ratio and caspase-3 activity, and reduced COX-2 levels by inhibiting the expression of the human antigen R (HuR), a known COX-2 mRNA stabilizer in keratinocytes. The transfection of nr-HaCaT cells with HuR siRNA mimicked the proapoptotic effect of DHA. Overall, our findings further support the role of DHA as a suitable anticarcinogenic factor against nonmelanoma skin cancers.

The Journal of nutritional biochemistry 22 (9), pp. 874–885