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Dugo M.,Functional Genomics and Bioinformatics | Nicolini G.,Unit of Immunobiology of Human Tumors | Tragni G.,Fondazione Istituto Nazionale Dei Tumori | Bersani I.,Unit of Immunobiology of Human Tumors | And 7 more authors.

Dysregulation of receptor tyrosine kinases (RTKs) contributes to several aspects of oncogenesis including drug resistance. In melanoma, distinct RTKs have been involved in BRAF inhibitors (BRAFi) resistance, yet the utility of RTKs expression pattern to identify intrinsically resistant tumors has not been assessed. Transcriptional profiling of RTKs and integration with a previous classification, reveals three robust subtypes in two independent datasets of melanoma cell lines and one cohort of melanoma samples. This classification was validated by Western blot in a panel of patient-derived melanoma cell lines. One of the subtypes identified here for the first time displayed the highest and lowest expression of EGFR and ERBB3, respectively, and included BRAF-mutant tumors all intrinsically resistant to BRAFi PLX4720, as assessed by analysis of the Cancer Cell Line Encyclopedia pharmacogenomic study and by in vitro growth inhibition assays. High levels of EGFR were detected, even before therapy, in tumor cells of one of three melanoma patients unresponsive to BRAFi. Use of different pharmacological inhibitors highlighted the relevance of PI3K/mTOR signaling for growth of this PLX4720-resistant subtype. Our results identify a specific molecular profile of melanomas intrinsically resistant to BRAFi and suggest the PI3K/ mTOR pathway as a potential therapeutic target for these tumors. Source

Micciche F.,Proteomics Laboratory | da Riva L.,Proteomics Laboratory | Fabbi M.,Laboratory of Immunological Therapy | Pilotti S.,Laboratory of Experimental Molecular Pathology | And 5 more authors.

Activated leukocyte cell adhesion molecule (ALCAM, CD166) is expressed in various tissues, cancers, and cancer-initiating cells. Alterations in expression of ALCAM have been reported in several human tumors, and cell adhesion functions have been proposed to explain its association with cancer. Here we documented high levels of ALCAM expression in human thyroid tumors and cell lines. Through proteomic characterization of ALCAM expression in the human papillary thyroid carcinoma cell line TPC-1, we identified the presence of a full-length membrane-associated isoform in cell lysate and of soluble ALCAM isoforms in conditioned medium. This finding is consistent with proteolytically shed ALCAM ectodomains. Nonspecific agents, such as phorbol myristate acetate (PMA) or ionomycin, provoked increased ectodomain shedding. Epidermal growth factor receptor stimulation also enhanced ALCAM secretion through an ADAM17/TACE-dependent pathway. ADAM17/TACE was expressed in the TPC-1 cell line, and ADAM17/TACE silencing by specific small interfering RNAs reduced ALCAM shedding. In addition, the CGS27023A inhibitor of ADAM17/TACE function reduced ALCAM release in a dose-dependent manner and inhibited cell migration in a wound-healing assay. We also provide evidence for the existence of novel O-glycosylated forms and of a novel 60-kDa soluble form of ALCAM, which is particularly abundant following cell stimulation by PMA. ALCAM expression in papillary and medullary thyroid cancer specimens and in the surrounding non-tumoral component was studied by western blot and immunohistochemistry, with results demonstrating that tumor cells overexpress ALCAM. These findings strongly suggest the possibility that ALCAM may have an important role in thyroid tumor biology. © 2011 Miccichè et al. Source

Titone R.,University of Piemonte Orientale | Morani F.,University of Piemonte Orientale | Follo C.,University of Piemonte Orientale | Vidoni C.,University of Piemonte Orientale | And 2 more authors.
BioMed Research International

Autophagy is a lysosomal-driven catabolic process that contributes to the preservation of cell homeostasis through the regular elimination of cellular damaged, aged, and redundant molecules and organelles. Autophagy plays dual opposite roles in cancer: on one hand it prevents carcinogenesis; on the other hand it confers an advantage to cancer cells to survive under prohibitive conditions. Autophagy has been implicated in ovarian cancer aggressiveness and in ovarian cancer cell chemoresistance and dormancy. Small noncoding microRNAs (miRNAs) regulate gene expression at posttranscriptional level, thus playing an important role in many aspects of cell pathophysiology, including cancerogenesis and cancer progression. Certain miRNAs have recently emerged as important epigenetic modulators of autophagy in cancer cells. The mRNA of several autophagy-related genes contains, in fact, the target sequence for miRNAs belonging to different families, with either oncosuppressive or oncogenic activities. MiRNA profiling studies have identified some miRNAs aberrantly expressed in ovarian cancer tissues that can impact autophagy. In addition, plasma and stroma cell-derived miRNAs in tumour-bearing patients can regulate the expression of relevant autophagy genes in cancer cells. The present review focuses on the potential implications of miRNAs regulating autophagy in ovarian cancer pathogenesis and progression. © 2014 Rossella Titone et al. Source

Sensi M.,Unit of Immunobiology of Human Tumors | Catani M.,Unit of Immunobiology of Human Tumors | Catani M.,Center for Regenerative Therapies | Castellano G.,Unit of Molecular Therapies | And 9 more authors.
Journal of Investigative Dermatology

Axl, a member of the TAM (Tyro3, Axl, Mer) family of receptor tyrosine kinases, displays an increasingly important role in carcinogenesis. Analysis of 58 cutaneous melanoma lines indicated that Axl was expressed in 38% of them, with significant overrepresentation in NRAS-compared with BRAF-mutated tumors. Axl activation could be induced by autocrine production of its ligand, Gas6, in a significant fraction of Axl-positive tumors. Pearson's correlation analysis on expression data from five data sets of melanoma lines identified several transcripts correlating positively or negatively with Axl. By functionally grouping genes, those inversely correlated were involved in melanocyte development and pigmentation, whereas those positively correlated were involved in motility, invasion, and microenvironment interactions. Accordingly, Axl-positive melanomas did not express microphthalmia transcription factor (MITF) and melanocyte differentiation antigens (MDAs) such as MART-1 and gp100 and possessed a greater in vitro invasive potential compared with Axl-negative ones. Motility, invasivity, and ability to heal a wound or to migrate across an endothelial barrier were inhibited in vitro by Axl knockdown. Pharmacological inhibition of Axl using the selective inhibitor R428 had comparable effects in reducing migration and invasion. These results suggest that targeted inhibition of Axl signaling in the subset of melanomas lacking MITF and MDAs may represent a novel therapeutic strategy. © 2011 The Society for Investigative Dermatology. Source

Rea K.,Unit of Molecular Therapies | Sensi M.,Unit of Immunobiology of Human Tumors | Anichini A.,Unit of Immunobiology of Human Tumors | Canevari S.,Unit of Molecular Therapies | Tomassetti A.,Unit of Molecular Therapies
Cell Death and Disease

FAK is a non-receptor tyrosine kinase contributing to migration and proliferation downstream of integrin and/or growth factor receptor signaling of normal and malignant cells. In addition to well-characterized tyrosine phosphorylations, FAK is phosphorylated on several serines, whose role is not yet clarified. We observed that phosphorylated FAK on serine 732 (P-FAKSer732) is present at variable levels in vitro, in several melanoma, ovarian and thyroid tumor cell lines and in vivo, in tumor cells present in fresh ovarian cancer ascites. In vitro P-FAKSer732 was barely detectable during interphase while its levels strongly increased in mitotic cells upon activation of the EGFR/MEK/ERK axis in an integrin-independent manner. P-FAKSer732 presence was crucial for the maintenance of the proliferation rate and its levels were inversely related to the levels of acetylated a-tubulin. P-FAKSer732 localized at the microtubules (MTs) of the spindle, biochemically associated with MTs and contributed to MT depolymerization. The lack of the phosphorylation on Ser732 as well as the inhibition of CDK5 activity by roscovitine impaired mitotic spindle assembly and correct chromosome alignment during mitosis. We also identified, for the first time, that the EGF-dependent EGFR activation led to increased P-FAKSer732 and polymerized MTs. Our data shed light on the multifunctional roles of FAK in neoplastic cells, being involved not only in integrin-dependent migratory signaling but also in integrin-independent MT dynamics and mitosis control. These findings provide a new potential target for inhibiting the growth of tumor cells in which the EGFR/MEK/ERK/CDK5 pathway is active. © 2013 Macmillan Publishers Limited. All rights reserved. Source

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