title: Platelet-derived growth factor C and calpain-3 are modulators of human melanoma cell invasiveness.
abstract: The molecular mechanisms responsible for the elevated metastatic potential of malignant melanoma are still not fully understood. In order to shed light on the molecules involved in the acquisition by melanoma of a highly aggressive phenotype, we compared the gene expression profiles of two cell clones derived from the human cutaneous metastatic melanoma cell line M14: a highly invasive clone (M14C2/MK18) and a clone (M14C2/C4) with low ability to invade the extracellular matrix (ECM). The highly invasive phenotype of M14C2/MK18 cells was correlated with overexpression of neuropilin-1, activation of a vascular endothelial growth factor (VEGF)-A/VEGFR-2 autocrine loop and secretion of matrix metalloprotease-2. Moreover, in an in vivo murine model, M14C2/MK18 cells displayed a higher growth rate as compared with M14C2/C4 cells, even though in vitro both clones possessed comparable proliferative potential. Microarray analysis in M14C2/MK18 cells showed a strong upregulation of platelet-derived growth factor (PDGF)-C, a cytokine that contributes to angiogenesis, and downregulation of calpain-3, a calcium-dependent thiol-protease that regulates specific signalling cascade components. Inhibition of PDGF-C with a specific antibody resulted in a significant decrease in ECM invasion by M14C2/MK18 cells, confirming the involvement of PDGF-C in melanoma cell invasiveness. Moreover, the PDGF-C transcript was found to be upregulated in a high percentage of human melanoma cell lines (17/20), whereas only low PDGF-C levels were detected in a few melanocytic cultures (2/6). By contrast, inhibition of calpain-3 activity in M14C2/C4 control cells, using a specific chemical inhibitor, markedly increased ECM invasion, strongly suggesting that downregulation of calpain-3 plays a role in the acquisition of a highly invasive phenotype. The results indicate that PDGF-C upregulation and calpain-3 downregulation are involved in the aggressiveness of malignant melanoma and suggest that modulators of these proteins or their downstream effectors may synergise with VEGF‑A therapies in combating tumour-associated angiogenesis and melanoma spread.
authors.affiliation: Laboratory of Molecular Oncology, 'Istituto Dermopatico dell'Immacolata'- IRCCS, Rome, Italy.
authors.forename: Federica
authors.initials: F
authors.lastname: Ruffini
authors.forename: Lucio
authors.initials: L
authors.lastname: Tentori
authors.forename: Annalisa Susanna
authors.initials: AS
authors.lastname: Dorio
authors.forename: Diego
authors.initials: D
authors.lastname: Arcelli
authors.forename: Giulia
authors.initials: G
authors.lastname: D'Amati
authors.forename: Stefania
authors.initials: S
authors.lastname: D'Atri
authors.forename: Grazia
authors.initials: G
authors.lastname: Graziani
authors.forename: Pedro Miguel
authors.initials: PM
authors.lastname: Lacal
mesh_terms: D000818:Animals; D002154:Calpain / Q000096:biosynthesis / Q000235:genetics*; D045744:Cell Line, Tumor; D005109:Extracellular Matrix / Q000235:genetics / Q000378:metabolism; D015972:Gene Expression Regulation, Neoplastic / Q000235:genetics; D006801:Humans; D008222:Lymphokines / Q000037:antagonists & inhibitors / Q000096:biosynthesis / Q000235:genetics*; D020778:Matrix Metalloproteinase 2 / Q000235:genetics; D008545:Melanoma / Q000235:genetics* / Q000473:pathology; D051379:Mice; D009124:Muscle Proteins / Q000096:biosynthesis / Q000235:genetics*; D009361:Neoplasm Invasiveness / Q000235:genetics*; D010982:Platelet-Derived Growth Factor / Q000037:antagonists & inhibitors / Q000096:biosynthesis / Q000235:genetics*; D015398:Signal Transduction / Q000235:genetics; D042461:Vascular Endothelial Growth Factor A / Q000235:genetics; D040301:Vascular Endothelial Growth Factor Receptor-2 / Q000235:genetics; D023041:Xenograft Model Antitumor Assays
chemical_list: D008222:Lymphokines; D009124:Muscle Proteins; D010982:Platelet-Derived Growth Factor; D042461:Vascular Endothelial Growth Factor A; C411423:platelet-derived growth factor C; D040301:Vascular Endothelial Growth Factor Receptor-2; C105884:CAPN3 protein, human; D002154:Calpain; D020778:Matrix Metalloproteinase 2