The SMARCD Family of SWI/SNF Accessory Proteins Is Involved in the Transcriptional Regulation of Androgen Receptor-Driven Genes and Plays a Role in Various Essential Processes of Prostate Cancer.

Previous studies have demonstrated an involvement of chromatin-remodelling SWI/SNF complexes in the development of prostate cancer, suggesting both tumor suppressor and oncogenic activities. SMARCD1/BAF60A, SMARCD2/BAF60B, and SMARCD3/BAF60C are mutually exclusive accessory subunits that confer functional specificity and are components of all known SWI/SNF subtypes. To assess the role of SWI/SNF in prostate tumorigenesis, we studied the functions and functional relations of the SMARCD family members. Performing RNA-seq in LnCAP cells grown in the presence or absence of dihydrotestosterone, we found that the SMARCD proteins are involved in the regulation of numerous hormone-dependent AR-driven genes. Moreover, we demonstrated that all SMARCD proteins can regulate AR-downstream targets in androgen-depleted cells, suggesting an involvement in the progression to castration-resistance. However, our approach also revealed a regulatory role for SMARCD proteins through antagonization of AR-signalling. We further demonstrated that the SMARCD proteins are involved in several important cellular processes such as the maintenance of cellular morphology and cytokinesis. Taken together, our findings suggest that the SMARCD proteins play an important, yet paradoxical, role in prostate carcinogenesis. Our approach also unmasked the complex interplay of paralogue SWI/SNF proteins that must be considered for the development of safe and efficient therapies targeting SWI/SNF.

Comparing the efficacy of γ- and electron-irradiation of PBMCs to promote secretion of paracrine, regenerative factors.

Cell-free secretomes represent a promising new therapeutic avenue in regenerative medicine, and γ-irradiation of human peripheral blood mononuclear cells (PBMCs) has been shown to promote the release of paracrine factors with high regenerative potential. Recently, the use of alternative irradiation sources, such as artificially generated ß- or electron-irradiation, is encouraged by authorities. Since the effect of the less hazardous electron-radiation on the production and functions of paracrine factors has not been tested so far, we compared the effects of γ- and electron-irradiation on PBMCs and determined the efficacy of both radiation sources for producing regenerative secretomes. Exposure to 60 Gy γ-rays from a radioactive nuclide and 60 Gy electron-irradiation provided by a linear accelerator comparably induced cell death and DNA damage. The transcriptional landscapes of PBMCs exposed to either radiation source shared a high degree of similarity. Secretion patterns of proteins, lipids, and extracellular vesicles displayed similar profiles after γ- and electron-irradiation. Lastly, we detected comparable biological activities in functional assays reflecting the regenerative potential of the secretomes. Taken together, we were able to demonstrate that electron-irradiation is an effective, alternative radiation source for producing therapeutic, cell-free secretomes. Our study paves the way for future clinical trials employing secretomes generated with electron-irradiation in tissue-regenerative medicine.

Carbon monoxide induced PPARγ SUMOylation and UCP2 block inflammatory gene expression in macrophages.

Carbon monoxide (CO) dampens pro-inflammatory responses in a peroxisome proliferator-activated receptor-γ (PPARγ) and p38 mitogen-activated protein kinase (MAPK) dependent manner. Previously, we demonstrated that CO inhibits lipopolysaccharide (LPS)-induced expression of the proinflammatory early growth response-1 (Egr-1) transcription factor in macrophages via activation of PPARγ. Here, we further characterize the molecular mechanisms by which CO modulates the activity of PPARγ and Egr-1 repression. We demonstrate that CO enhances SUMOylation of PPARγ which we find was attributed to mitochondrial ROS generation. Ectopic expression of a SUMOylation-defective PPARγ-K365R mutant partially abolished CO-mediated suppression of LPS-induced Egr-1 promoter activity. Expression of a PPARγ-K77R mutant did not impair the effect of CO. In addition to PPARγ SUMOylation, CO-activated p38 MAPK was responsible for Egr-1 repression. Blocking both CO-induced PPARγ SUMOylation and p38 activation, completely reversed the effects of CO on inflammatory gene expression. In primary macrophages isolated form C57/BL6 male mice, we identify mitochondrial ROS formation by CO as the upstream trigger for the observed effects on Egr-1 in part through uncoupling protein 2 (UCP2). Macrophages derived from bone marrow isolated from Ucp2 gene Knock-Out C57/BL6 mice (Ucp2(-/-)), produced significantly less ROS with CO exposure versus wild-type macrophages. Moreover, absence of UCP2 resulted in a complete loss of CO mediated Egr-1 repression. Collectively, these results indentify p38 activation, PPARγ-SUMOylation and ROS formation via UCP2 as a cooperative system by which CO impacts the inflammatory response.

Transcriptome analysis of human cancer reveals a functional role of heme oxygenase-1 in tumor cell adhesion.

BACKGROUND: Heme Oxygenase-1 (HO-1) is expressed in many cancers and promotes growth and survival of neoplastic cells. Recently, HO-1 has been implicated in tumor cell invasion and metastasis. However, the molecular mechanisms underlying these biologic effects of HO-1 remain largely unknown. To identify a common mechanism of action of HO-1 in cancer, we determined the global effect of HO-1 on the transcriptome of multiple tumor entities and identified a universal HO-1-associated gene expression signature. RESULTS: Genome-wide expression profiling of Heme Oxygenase-1 expressing versus HO-1 silenced BeWo choriocarcinoma cells as well as a comparative meta-profiling of the preexisting expression database of 190 human tumors of 14 independent cancer types led to the identification of 14 genes, the expression of which correlated strongly and universally with that of HO-1 (P = 0.00002). These genes included regulators of cell plasticity and extracellular matrix (ECM) remodeling (MMP2, ADAM8, TGFB1, BGN, COL21A1, PXDN), signaling (CRIP2, MICB), amino acid transport and glycosylation (SLC7A1 and ST3GAL2), estrogen and phospholipid biosynthesis (AGPAT2 and HSD17B1), protein stabilization (IFI30), and phosphorylation (ALPPL2). We selected PXDN, an adhesion molecule involved in ECM formation, for further analysis and functional characterization. Immunofluorescence and Western blotting confirmed the positive correlation of expression of PXDN and HO-1 in BeWo cancer cells as well as co-localization of these two proteins in invasive extravillous trophoblast cells. Modulation of HO-1 expression in both loss-of and gain-of function cell models (BeWo and 607B melanoma cells, respectively) demonstrated a direct relationship of HO-1 expression with cell adhesion to Fibronectin and Laminin coated wells. The adhesion-promoting effects of HO-1 were dependent on PXDN expression, as loss of PXDN in HO-1 expressing BeWo and 607B cells led to reduced cell attachment to Laminin and Fibronectin coated wells. CONCLUSIONS: Collectively, our results show that HO-1 expression determines a distinct 'molecular signature' in cancer cells, which is enriched in genes associated with tumorigenesis. The protein network downstream of HO-1 modulates adhesion, signaling, transport, and other critical cellular functions of neoplastic cells and thus promotes tumor cell growth and dissemination.