FUNCTIONAL ANALYSIS OF P63-YB1 INTERACTION IN NORMAL AND TRANSFORMED EPITHELIAL CELLS: DEVELOPMENT OF NOVEL MOLECULAR TOOLS FOR SQUAMOUS CANCER DIAGNOSIS AND THERAPY

Abstract

Skin homeostasis is dependent on a tightly coordinated network of signaling pathways, resulting in a spatial and temporal balance of proliferation, growth arrest, differentiation, senescence and apoptosis. The knowledge of mechanisms that regulate keratinocyte growth and proliferation is attractive for several biotechnological fields, such as cosmetics, tissue engineering and skin regeneration. DNp63alfa, as critical pro-proliferative factor and marker of epidermal stemness, is essential for morphogenesis of organs/tissues developing by epithelial-mesenchimal interactions such as the epidermis, teeth, hair and glands (Mills, 1999). Using a proteomic approach my research group had identified YB-1 as a DNp63alfa molecular partner (Amoresano, 2010). Y Box Binding protein 1 (YB-1) is a transcription/translation factor involved in a wide variety of cellular functions, including cell proliferation and migration, DNA repair, multidrug resistance and stress response to extracellular signals (Lyabin, 2014). My PhD project was aimed to advance in the characterization of the functional interplay between DNp63alfa and Y-box binding 1 proteins using in cell approaches to elucidate their roles in skin proliferation. First, I have validated DNp63alfa-YB-1 interaction in distinct cell contexts and demonstrated that this interaction causes accumulation of YB-1 into the nuclear compartment and influences its localization-dependent functions (Di Costanzo, 2012). Then, I extended our knowledge on the YB-1 and DNp63alfa functional interplay demonstrating that, being able to sustain DNp63alfa gene expression, YB-1 is part of a complex molecular network linking DNp63alfa to the PI3K/AKT/PTEN pathway and that establishment of a positive feedback loop, coupling induction of DNp63alfa expression with PI3K/AKT activation, may be a relevant step in the progression of squamous carcinogenesis (Troiano, 2015). During my PhD program, I have spent six months at the Blizard Institute - Queen Mary University of London collaborating with Professor Bergamaschi's team. Based on my experience on squamous carcinoma I explored if p63 and YB-1 are also involved in melanoma pathogenesis and/or progression. Although my data are still preliminary, they show that DNp63alfa controls YB-1 protein integrity and nuclear localization also in melanoma cells and their functional cross-talk plays a role in melanoma cell survival. Finally, thanks to the collaboration with Prof. Piera Quesada's team, I had the opportunity to perform experiments aimed to investigate on the role of p53 family members in the response of cancer cells to Topoisomerase I and poly(ADP-ribose)polymerase (PARP1) inhibitors. My results point to a role for p63 in the cell response to treatment with TOP I and PARP-1 inhibitors. Highlighting the different outcome (i.e cell cycle arrest vs apoptosis) of PARP-1 activation/inhibition, my studies give right of the use of PARP inhibitor as chemotherapic adjuvant and/or in monotherapy also in TAp63/DNp63alfa proficient cancer cells (Montariello, 2013; Montariello, 2015).