H Ferritin Gene Silencing in a Human Metastatic Melanoma Cell Line: A Proteomic Analysis

Ferritin, the major intracellular iron-storage protein, is made of 24 subunits oftwo types, H and L. Besides regulating intracellular iron homeostasis, it hasbeen found that ferritin, in particular the H subunit (FHC), is involved indifferent biological events such as cell differentiation and pathologic states(i.e., neurodegeneration and cancer). This study is aimed at investigating thewhole-cell proteome of FHC-expressing and sh-RNA-silenced human metastaticmelanoma cells (MM07(m)) in the attempt to identify and classify the highestnumber of proteins directly or indirectly controlled by the FHC. We identifiedabout 200 differentially expressed proteins and classified them in clusters onthe basis of their functions, as proteins involved in metabolic processes, celladhesion, migration, and proliferation processes. Some of them have captured our attention because of their involvement in metabolic pathways related to tumorprogression and metastasis. In vitro assays confirmed that the FHC-silencedMM07(m) cells are characterized by a decreased growth activity, a reducedinvasiveness, and a reduced cell adhesion capability. Moreover, nude mice (CD1nu/nu), subcutaneously injected with FHC-silenced MM07(m) cells, showed aremarkable 4-fold reduction of their tumor growth capacity compared to those who received the FHC-unsilenced MM07(m) counterpart. In conclusion, these dataindicate that gene silencing technology, coupled to proteomic analysis, is apowerful tool for a better understanding of H ferritin signaling pathways andlend support to the hypothesis that specific targeting of this gene might be anattractive and potentially effective strategy for the management of metastaticmelanoma.