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Zinc finger protein 521 (EHZF/ZNF521) is a multi-functional transcription co-factor containing 30 zinc fingers and an amino-terminal motif that binds to the nucleosome remodelling and histone deacetylase (NuRD) complex. ZNF521 is believed to be a relevant player in the regulation of the homeostasis of the hematopoietic stem/progenitor cell compartment, however the underlying molecular mechanisms are still largely unknown. Here, we show that this protein plays an important role in the control of B-cell development by inhibiting the activity of early B-cell factor-1 (EBF1), a master factor in B-lineage specification. In particular, our data demonstrate that: (1) ZNF521 binds to EBF1 via its carboxyl-terminal portion and this interaction is required for EBF1 inhibition; (2) NuRD complex recruitment by ZNF521 is not essential for the inhibition of transactivation of EBF1-dependent promoters; (3) ZNF521 represses EBF1 target genes in a human B-lymphoid molecular context; and (4) RNAi-mediated silencing of ZNF521/Zfp521 in primary human and murine hematopoietic progenitors strongly enhances the generation of B-lymphocytes in vitro. Taken together, our data indicate that ZNF521 can antagonize B-cell development and lend support to the notion that it may contribute to conserve the multipotency of primitive lympho-myeloid progenitors by preventing or delaying their EBF1-driven commitment toward the B-cell lineage.

The interleukin-2 is a cytokine that is essential for lymphocytic survival and function. Ectopic expression of the IL-2 receptor in epithelial tissues has been reported previously, although the functional significance of this expression is still being investigated. We provided novel structural and functional information on the expression of the IL-2 receptor in kidney cancer cells and in other normal and neoplastic human epithelial tissues. In A-498 kidney cancer cells, we showed that IL-2 binding to its own receptor triggers a signal transduction pathway leading to the inhibition of proliferation and apoptosis. We found that the inhibition of proliferation is associated with Erk1/2 dephosphorylation, whereas the survival signals appear to be mediated by Sgk1 activation. This investigation focuses on the IL-2 induced regulation of Sgk1 and describes a role of the IL-2 receptor and Sgk1 in the regulation of epithelial tumor cell death and survival.

The stem cell-associated transcription co-factor ZNF521 has been implicated in the control of hematopoietic, osteo-adipogenic and neural progenitor cells. ZNF521 is highly expressed in cerebellum and in particular in the neonatal external granule layer that contains candidate medulloblastoma cells-of-origin, and in the majority of human medulloblastomas. Here we have explored its involvement in the control of human and murine medulloblastoma cells.The effect of ZNF521 on growth and tumorigenic potential of human medulloblastoma cell lines as well as primary Ptc1−/+ mouse medulloblastoma cells was investigated in a variety of in vitro and in vivo assays, by modulating its expression using lentiviral vectors carrying the ZNF521 cDNA, or shRNAs that silence its expression.Enforced overexpression of ZNF521 in DAOY medulloblastoma cells significantly increased their proliferation, growth as spheroids and ability to generate clones in single-cell cultures and semisolid media, and enhanced their migratory ability in wound-healing assays. Importantly, ZNF521-expressing cells displayed a greatly enhanced tumorigenic potential in nude mice. All these activities required the ZNF521 N-terminal motif that recruits the nucleosome remodeling and histone deacetylase complex, which might therefore represent an appealing therapeutic target. Conversely, silencing of ZNF521 in human UW228 medulloblastoma cells that display high baseline expression decreased their proliferation, clonogenicity, sphere formation and wound-healing ability. Similarly, Zfp521 silencing in mouse Ptc1−/+ medulloblastoma cells drastically reduced their growth and tumorigenic potential.Our data strongly support the notion that ZNF521, through the recruitment of the NuRD complex, contributes to the clonogenic growth, migration and tumorigenicity of medulloblastoma cells.

High-mobility group A (HMGA) proteins are non-histone nuclear proteins that bind DNA and several transcription factors. They are involved in the regulation of chromatin structure and function. HMGA protein expression is low in normal adult tissues, but abundant during embryonic development and in several human tumours. Rearrangements of the HMGA genes have been frequently detected in human benign tumours of mesenchymal origin, e.g. lipomas, lung hamartomas and uterine leiomiomas. HMGA proteins have been implicated in the control of cell growth and differentiation of the pre-adipocytic cell line 3T3-L1. In an attempt to better understand the role of HMGA1 proteins in haematological neoplasias and in the differentiation of haematopietic cells, we have investigated their expression in human leukaemias and in leukaemic cell lines induced to terminal differentiation. Here we report HMGA1 overexpression in most fresh human leukaemias of different origin and in several leukaemic cell lines. Moreover, differentiation of three cell lines towards the megakaryocytic phenotype was associated with HMGA1 protein induction, whereas induction of erythroid and monocytic differentiation generally resulted in reduced HMGA1 expression.

Background: Uterine and ovarian carcinosarcomas (CS) are rare cancers with poor prognosis. Sacituzumab-govitecan (SG) is a new class of antibody-drug-conjugate (ADC) targeting the human-trophoblast-cell-surface marker (Trop-2) conjugated with the active metabolite of irinotecan (SN-38). We evaluated the efficacy of SG against biologically aggressive CS.Methods: Trop-2 expression was evaluated in 10 formalin-fixed-paraffinedembedded (FFPE) CS by immunohistochemistry and 9 primary CS cell-lines by flowcytometry. One Trop-2 low/negative (SARARK14) and two Trop-2 positive (SARARK4, SARARK9) cell-lines were tested in cell-viability assays . The in vivo antitumor activity of SG was tested in xenografts models (ie, SARARK9) with strong Trop-2 expression.Results: Strong/diffuse staining was seen in 30% (3/10) of FFPE tumors and 33% (3/9) of primary CS cell lines. Trop-2 positive cell-lines (SARARK4, SARARK9) showed higher sensitivity to SG in vitro when compared to Trop-2 low/negative (SARARK14) cell lines. In xenografts, twice-weekly intravenous administration of SG for three weeks showed a significant tumor growth inhibition when compared to control, to ADC control and to the naked AB (p=0.004, p=0.007 and p=0.0007, respectively). SG significantly improved overall survival at 90 days when compared to control groups (p<0.0001).Conclusion: SG may represent a novel class of active drugs for carcinosarcomas patients overexpressing Trop-2.

Mesenchymal stem cells (MSCs) are multipotent progenitors present in the bone marrow stroma and in subcutaneous abdominal fat, an abundant and easily accessible source of MSCs with the ability to differentiate along multiple lineage pathways. The stem cell-associated transcription co-factor Zinc Finger Protein 521 (ZNF521/zfp521) has been implicated in the control of the homeostasis of hematopoietic, neural and osteo-adipogenic progenitors. Here we document through the analysis of a panel of human adipose-derived stem cells (hADSCs), that ZNF521 strongly inhibits the generation of mature adipocytes. Enforced overexpression of ZNF521 in these cells resulted in a significant delay and reduction in adipocyte differentiation upon exposure to inducers of adipogenesis. Of particular relevance, ZNF521 was able to inhibit the expression of ZNF423, recently identified as an essential commitment factor necessary for the generation of pre-adipocytes. Conversely, silencing of ZNF521 was found to significantly enhance the adipogenic differentiation of hADSCs. Inhibition of adipogenesis by ZNF521 was at least in part due to inhibition of EBF1. Taken together, these results confirm a role for ZNF521 as a key negative regulator of adipocyte differentiation of hADSCs.