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Giant cell tumors of bone (GCTB) are semi-malignant tumors associated with extensive osteolytic defects and massive bone destructions. They display a locally aggressive behavior and a very high recurrence rate. Recently, a single mutation has been identified in GCTB affecting the H3F3A gene coding for the histone variant H3.3 (H3.3-G34W). The aim of this study was to investigate whether H3.3-G34W is sufficient to drive tumorigenesis in GCTB. Initially, we confirmed the high frequency of this mutation in 94% of 84 analyzed tissue samples. Using a siRNA based approach we could selectively knockdown H3.3-G34W in primary neoplastic stromal cells isolated from tumor tissue (GCTSC). H3.3-G34W knockdown caused a significant inhibition of cell proliferation, migration and colony formation capacity in vitro. Xenotransplantation of GCTSCs onto the chorioallantoic membrane of fertilized chicken eggs further demonstrated a significant impact of H3.3-G34W knockdown on tumor engraftment and growth in vivo. Our data indicate that H3.3-G34W is sufficient to drive tumorigenesis in GCTB. Apart from the application of H3.3-G34W screening as diagnostic tool, our data suggest that H3.3-G4W represents a promising target for the development of new GCTB therapies. [ABSTRACT FROM AUTHOR]

Primary organoid cultures generated from patient biopsies comprise a novel improved platform for disease modeling, being genetically stable and closely recapitulating in vivo scenarios. Barrett esophagus (BE) is the major risk factor for esophageal adenocarcinoma. There has been a dearth of long-term in vitro expansion models of BE neoplastic transformation. We generated a long-term virus-free organoid expansion model of BE neoplasia from patient biopsies. Both wild-type and paired APC-knockout (APCKO) BE organoids genome-edited by CRISPR-Cas9 showed characteristic goblet cell differentiation. Autonomous Wnt activation was confirmed in APCKO organoids by overexpression of Wnt target genes and nuclear-translocated β-catenin expression after withdrawal of Wnt-3A and R-spondin-1. Wnt-activated organoids demonstrated histologic atypia, higher proliferative and replicative activity, reduced apoptosis, and prolonged culturability. Wnt-activated organoids also showed sustained protrusive migration ability accompanied by disrupted basement membrane reorganization and integrity. This CRISPR-Cas9 editing human-derived organoid model recapitulates the critical role of aberrant Wnt/β-catenin signaling activation in BE neoplastic transformation. This system can be used to study other 'driver' pathway alterations in BE-associated neoplasia, avoiding signaling noise present in immortalized or cancer-derived cell lines. [ABSTRACT FROM AUTHOR]

Although generally benign, giant cell tumors of bone (GCTB) display an aggressive behavior associated with significant bone destruction and lung metastasis in rare cases. This and the very high recurrence rate observed after surgical resection ranging from 20 to 55% necessitates the development of more effective treatment strategies. To identify valuable therapeutic targets, we screened a previously identified microRNA signature consisting of 23 microRNAs predominantly down-regulated in GCTB. We preselected eight candidate microRNAs and analyzed the impact of their restored expression on the neoplastic phenotype of GCTB stromal cells (GCTSC). A consistent and significant inhibition of cell proliferation, migration, colony formation and spheroid formation could be induced by transfection of primary GCTSC cell lines with miR-127-3p and miR-376a-3p, respectively. Genome wide expression analysis of miR-127-3p and miR-376a-3p transfected cells revealed four novel target genes for each microRNA. Luciferase reporter assays demonstrated direct interactions of miR-127-3p with COA1 and direct interaction of miR-376a-3p with GLE1 and PDIA6, suggesting a pivotal role of these genes in the molecular etiology of GTCB. Interestingly, both microRNAs are located within a chromosomal region frequently silenced in GCTB and many other types of cancers, indicating that these microRNAs and their target genes are valuable therapeutic targets for the treatment of GCTB and possibly other tumor entities. [ABSTRACT FROM AUTHOR]

Autophagy is a highly conserved and lysosome-dependent degradation process which assists in cell survival and tissue homeostasis. Although previous reports have shown that deletion of the essential autophagy gene disturbs stem cell maintenance in some cell types such as hematopoietic and neural cells, it remains unclear how autophagy-deficiency influences hepatic progenitor cells (HPCs). Here we report that Atg5-deficiency in HPCs delays HPC-mediated rat liver regeneration in vivo. In vitro researches further demonstrate that loss of autophagy decreases the abilities of colony and spheroid formations, and disrupts the induction of hepatic differentiation in HPCs. Meanwhile, autophagy-deficiency increases the accumulations of damaged mitochondria and mitochondrial reactive oxygen species (mtROS) and suppresses homologous recombination (HR) pathway of DNA damage repair in HPCs. Moreover, in both diethylnitrosamine (DEN) and CCl4 models, autophagy-deficiency accelerates neoplastic transformation of HPCs. In conclusion, these findings demonstrate that autophagy contributes to stemness maintenance and reduces susceptibility to neoplastic transformation in HPCs. [ABSTRACT FROM AUTHOR]

Nm23H1 and H2 are prototypical metastasis suppressors with diverse functions, but recent studies suggest that they may also regulate tumorigenesis. Here, we employed both cellular and in vivo assays to examine the effect of Nm23H1 and H2 on tumorigenesis induced by oncogenic Ras and/or p53 deficiency. Co-expression of Nm23H1 but not H2 in NIH3T3 cells effectively suppressed neoplastic transformation and tumorigenesis induced by the oncogenic H-Ras G12V mutant. Overexpression of Nm23H1 but not H2 also inhibited tumorigenesis by human cervical cancer HeLa cells with p53 deficiency. However, in human non-small-cell lung carcinoma H1299 cells harboring N-Ras Q61K oncogenic mutation and p53 deletion, overexpression of Nm23H1 did not affect tumorigenesis in nude mice assays, while overexpression of Nm23H2 enhanced tumor growth with elevated expression of the c-Myc proto-oncogene. Collectively, these results suggest that Nm23H1 and H2 have differential abilities to modulate tumorigenesis. [ABSTRACT FROM AUTHOR]

Abstract: Glycogen synthase kinase 3β (GSK3β), a multifunctional serine/threonine kinase found in all eukaryotes, had been initially identified as a key regulator of insulin-dependent glycogen synthesis. It is now known that GSK3β functions in diverse cellular processes including proliferation, differentiation, motility and survival. Aberrant regulation of GSK3β has been implicated in a range of human pathologies including non-insulin-dependent diabetes mellitus, cardiovascular disease, some neurodegenerative diseases, and bipolar disorder. As a consequence, the therapeutic potential of GSK3β inhibitors has become an important area of investigation. However, GSK3β also participates in neoplastic transformation and tumor development. The role of GSK3β in tumorigenesis and cancer progression remains controversial; it may function as a “tumor suppressor” for certain types of tumors, but promotes growth and development for some others. GSK3β also mediates drug sensitivity/resistance in cancer chemotherapy. Therefore, although GSK3β is an attractive therapeutic target for a number of human diseases, its potential impact on tumorigenesis and cancer chemotherapy needs to be carefully evaluated. This mini-review discusses the role of GSK3β in tumorigenesis/cancer progression as well as its modulation of cancer chemotherapy. [Copyright &y& Elsevier]

Abstract: The signal transducer and activator of transcription-3 (Stat3) is persistently activated in many cancers such as cancer of the breast and is required for transformation by a number of oncogenes. Signaling through Stat3 is determined by a key phosphorylation at tyr-705. We previously demonstrated that cell-to-cell adhesion brought about through cell aggregation or confluence of cultured cells causes a dramatic increase in Stat3 tyr705 phosphorylation and consequently Stat3 activity in both normal and tumor cells. To examine the role of Stat3 at specific time-points relative to confluence, we used two different approaches of Stat3 inhibition: (1). Introduction of high levels of peptide analogues, which block the Stat3-SH2 domain, to inhibit Stat3 binding to and phosphorylation by growth factor receptors. (2). Treatment with two platinum compounds which bind the Stat3 protein and inhibit its activity without affecting its phosphorylation directly. The results demonstrate that Stat3 downregulation in vSrc transformed NIH3T3 cells or in breast cancer lines harboring activated Src induces apoptosis, which is evident at all densities but is more pronounced at post-confluence. In normal cells on the other hand, Stat3 inhibition at post-confluence caused apoptosis while in sparsely growing cells it induced merely a growth retardation. [Copyright &y& Elsevier]