PROTEOMIC PROFILE MODIFICATIONS INDUCED IN MALIGNANT MELANOMA CELLS BY THE CURCUMIN ANALOGUE COMPOUND D6

Malignant melanoma (MM) is one of the most aggressive cancers that affect humans for which, in the advanced stages, there is no effective therapy: search for new compounds able to control it is therefore essential. We have already demonstrated that an hydroxylated biphenyl compound ((3E,3'E)-4.4'-(5,5',6,6'-tetramethoxy-[1,1'-biphenyl]-3,3'-diyl) bis(but-3-en-2-one)), called D6, structural analogue of curcumin, showed a strong antitumor activity on MM cells (about ten times more than curcumin itself) both in vitro and in vivo. The mechanisms of action of this compound are not clear yet, but it inhibits cancer cells growth and induces apoptosis through the mitochondrial intrinsic pathway. In order to investigate the modifications of protein expression following the treatment of MM cells with D6 we performed a proteomic analysis on a primary MM cell line (LB24Dagi) treated or not with 10 ?M D6. GeLC-MS/MS techniques (in-gel tryptic digestion followed by liquid chromatography-tandem mass spectrometry) were performed to extract and identify all the proteins characterizing the proteome profile for each sample. Upon data analysis, a total of 984 different proteins were identified with high confidence. A comparison between the proteomic profiles of D6 treated and untreated samples was carried out according to spectral counting protein abundance estimation, and 62 proteins were detected as differentially expressed (27 over-expressed and 35 under-expressed in the D6 treated samples). Observing the top ten up-regulated molecules in the D6 treated cells we noted that most of them belong to the Heat Shock Protein (HSP) family while, among the top ten down-regulated molecules, the majority are involved in the protein translation machinery. HSPs have a protective function in stress conditions but they also have an essential role in the apoptosis regulation that is one of the mechanisms by which D6 cause cell growth inhibition. A pathway analysis is now ongoing by using the Ingenuity Pathway Analysis (IPA) software in order to shed light on the molecular pathways involved in the D6 antitumoral activity.