Identification of H ferritin-dependent and independent genes in K562 differentiating cells by targeted gene silencing and expression profiling.

Ferritin is best known as the key molecule in intracellular iron storage, and is involved in several metabolic processes such as cell proliferation, differentiation and neoplastic transformation. We have recently demonstrated that the shRNA silencing of the ferritin heavy subunit (FHC) in a melanoma cell line is accompanied by a consistent modification of gene expression pattern leading to a reduced potential in terms of proliferation, invasiveness, and adhesion ability of the silenced cells. In this study we sought to define the repertoire of genes whose expression might be affected by FHC during the hemin-induced differentiation of the erythromyeloid cell line K562. To this aim, gene expression profiling was performed in four different sets of cells: i) wild type K562; ii) sh-RNA FHC-silenced K562; iii) hemin-treated wild-type K562; and iv) hemin-treated FHC-silenced K562. Statistical analysis of the gene expression data, performed by two-factor ANOVA, identified three distinct classes of transcripts: a) Class 1, including 657 mRNAs whose expression is modified exclusively during hemin-induced differentiation of K562 cells, independently from the FHC relative amounts; b) Class 2, containing a set of 70 mRNAs which are consistently modified by hemin and FHC-silencing; and c) Class 3, including 128 transcripts modified by FHC-silencing but not by hemin. Our data indicate that FHC may function as a modulator of gene expression during erythroid differentiation and add new findings to the knowledge of the complex gene network modulated during erythroid differentiation.