Epigenetically maintained SW13+ and SW13- subtypes have different oncogenic potential and convert with HDAC1 inhibition.

BACKGROUND: The BRM and BRG1 tumor suppressor genes are mutually exclusive ATPase subunits of the SWI/SNF chromatin remodeling complex. The human adrenal carcinoma SW13 cell line can switch between a subtype which expresses these subunits, SW13+, and one that expresses neither subunit, SW13-. Loss of BRM expression occurs post-transcriptionally and can be restored via histone deacetylase (HDAC) inhibition. However, most previously used HDAC inhibitors are toxic and broad-spectrum, providing little insight into the mechanism of the switch between subtypes. In this work, we explore the mechanisms of HDAC inhibition in promoting subtype switching and further characterize the oncogenic potential of the two epigenetically distinct SW13 subtypes. METHODS: SW13 subtype morphology, chemotaxis, growth rates, and gene expression were assessed by standard immunofluorescence, transwell, growth, and qPCR assays. Metastatic potential was measured by anchorage-independent growth and MMP activity. The efficacy of HDAC inhibitors in inducing subtype switching was determined by immunofluorescence and qPCR. Histone modifications were assessed by western blot. RESULTS: Treatment of SW13- cells with HDAC1 inhibitors most effectively promotes re-expression of BRM and VIM, characteristic of the SW13+ phenotype. During treatment, hyperacetylation of histone residues and hypertrimethylation of H3K4 is pronounced. Furthermore, histone modification enzymes, including HDACs and KDM5C, are differentially expressed during treatment but several features of this differential expression pattern differs from that seen in the SW13- and SW13+ subtypes. As the SW13- subtype is more proliferative while the SW13+ subtype is more metastatic, treatment with HDACi increases the metastatic potential of SW13 cells while restoring expression of the BRM tumor suppressor. CONCLUSIONS: When compared to the SW13- subtype, SW13+ cells have restored BRM expression, increased metastatic capacity, and significantly different expression of a variety of chromatin remodeling factors including those involved with histone acetylation and methylation. These data are consistent with a multistep mechanism of SW13- to SW13+ conversion and subtype stabilization: histone hypermodification results in the altered expression of chromatin remodeling factors and chromatin epigenetic enzymes and the re-expression of BRM which results in restoration of SWI/SNF complex function and leads to changes in chromatin structure and gene expression that stabilize the SW13+ phenotype.

Kidney Subcapsular Allograft Transplants as a Model to Test Virus-Derived Chemokine-Modulating Proteins as Therapeutics.

Solid tissue transplant is a growing medical need that is further complicated by a limited donor organ supply. Acute and chronic rejection occurs in nearly all transplants and reduces long-term graft survival, thus increasing the need for repeat transplantation. Viruses have evolved highly adapted responses designed to evade the host's immune defenses. Immunomodulatory proteins derived from viruses represent a novel class of potential therapeutics that are under investigation as biologics to attenuate immune-mediated rejection and damage. These immune-modulating proteins have the potential to reduce the need for traditional posttransplant immune suppressants and improve graft survival. The myxoma virus-derived protein M-T7 is a promising biologic that targets chemokine and glycosaminoglycan pathways central to kidney transplant rejection. Orthotopic transplantations in mice are prohibitively difficult and costly and require a highly trained microsurgeon to successfully perform the procedure. Here we describe a kidney-to-kidney subcapsular transplant model as a practical and simple method for studying transplant rejection, a model that requires fewer mice. One kidney can be used as a donor for transplants into six or more recipient mice. Using this model there is lower morbidity, pain, and mortality for the mice. Subcapsular kidney transplantation provides a first step approach to testing virus-derived proteins as new potential immune-modulating therapeutics to reduce transplant rejection and inflammation.

Hepatic and splenic immune response during acute vs. chronic Brucella melitensis infection using in situ microscopy.

Brucella melitensis is an intracellular bacteria causing disease in humans as an incidental host. The infection initiates as acute flu-like symptoms and may transform into a chronic cyclic infection. This cyclic infection may be partly due to the bacteria's ability to persist within antigen presenting cells and evade the CD8 + T cell response over long periods of time. This research aims to characterize the immune response of the acute and chronic forms of brucellosis in the murine liver and spleen. We also sought to determine if the exhaustion of the CD8 + T cells was a permanent or temporary change. This was accomplished by using adoptive transfer of acutely infected CD8 + T cells and chronically infected CD8 + T cells into a naïve host followed by re-infection. The histological examination presented supports the concept that exhausted T-cells can regain function through evidence of granulomatous inflammation after virulent challenge in a new host environment.