Epigenetic Silencing of IRF7 and/or IRF5 in Lung Cancer Cells Leads to Increased Sensitivity to Oncolytic Viruses

Defective IFN signaling results in loss of innate immunity and sensitizes cells to enhanced cytolytic killing after Vesticular Stomatitis Virus (VSV) infection. Examination of the innate immunity status of normal human bronchial epithelial cells Beas2B and 7 lung cancer cells revealed that the abrogation of IFN signaling in cancer cells is associated with greater sensitivity to VSV infection. The disruption of the IFN pathway in lung cancer cell lines and primary tumor tissues is caused by epigenetic silencing of critical interferon responsive transcription factors IRF7 and/or IRF5. Although 5-aza-2′-deoxycytidine treatment fails to reactivate IRF7 and IRF5 expression or protect cells from VSV infection, manipulating IFN signaling by altering IRF expression changes the viral susceptibility of these cells. Lung cancer cells can be partially protected from viral killing using IRF5+IRF7 overexpression, whereas IFN pathway disruption by transfection of siRNAs to IRF5+IRF7 increases cells' vulnerability to viral infection. Therefore, IRF5 and IRF7 are key transcription factors in IFN pathway that determine viral sensitivity of lung cancer cells; the epigenetically impaired IFN pathway in lung cancer tissues provides potential biomarkers for successful selective killing of cancer cells by oncolytic viral therapy

Pegylated IFN-α sensitizes melanoma cells to chemotherapy and causes premature senescence in endothelial cells by IRF-1-mediated signaling

Pegylated interferon-α2b (pIFN-α) is an integral part of the drug regimen currently employed against melanoma. Interferon regulatory factor-1 (IRF-1) has an important role in the transcriptional regulation of the IFN response, cell cycle and apoptosis. We have studied pIFN-α-induced responses when combined with the chemotherapy agent, vinblastine (VBL), in tumor and endothelial cell lines and the connection to IRF-1 signaling. Levels of IRF-1/IRF-2 protein expression were found to be decreased in tumor versus normal tissues. pIFN-α induced IRF-1 signaling in human melanoma (M14) and endothelial (EA.hy926) cells and enhanced cell death when combined with VBL. Upon combined IFN-α and VBL treatment, p21 expression, poly (ADP-ribose) polymerase cleavage and activated Bak levels were increased in M14 cells. An increase in p21 and cyclin D1 expression occurred in EA.hy926 cells after 6 h of treatment with pIFN-α, which dissipated by 24 h. This biphasic response, characteristic of cellular senescence, was more pronounced upon combined treatment. Exposure of the EA.hy926 cells to pIFN-α was associated with an enlarged, multinucleated, β-galactosidase-positive senescent phenotype. The overall therapeutic mechanism of IFN-α combined with chemotherapy may be due to both direct tumor cell death via IRF-1 signaling and by premature senescence of endothelial cells and subsequent effects on angiogenesis in the tumor microenvironment

Lgl2 Executes Its Function as a Tumor Suppressor by Regulating ErbB Signaling in the Zebrafish Epidermis

Changes in tissue homeostasis, acquisition of invasive cell characteristics, and tumor formation can often be linked to the loss of epithelial cell polarity. In carcinogenesis, the grade of neoplasia correlates with impaired cell polarity. In Drosophila, lethal giant larvae (lgl), discs large (dlg), and scribble, which are components of the epithelial apico-basal cell polarity machinery, act as tumor suppressors, and orthologs of this evolutionary conserved pathway are lost in human carcinoma with high frequency. However, a mechanistic link between neoplasia and vertebrate orthologs of these tumor-suppressor genes remains to be fully explored at the organismal level. Here, we show that the pen/lgl2 mutant phenotype shares two key cellular and molecular features of mammalian malignancy: cell autonomous epidermal neoplasia and epithelial-to-mesenchymal-transition (EMT) of basal epidermal cells including the differential expression of several regulators of EMT. Further, we found that epidermal neoplasia and EMT in pen/lgl2 mutant epidermal cells is promoted by ErbB signalling, a pathway of high significance in human carcinomas. Intriguingly, EMT in the pen/lgl2 mutant is facilitated specifically by ErbB2 mediated E-cadherin mislocalization and not via canonical snail–dependent down-regulation of E-cadherin expression. Our data reveal that pen/lgl2 functions as a tumor suppressor gene in vertebrates, establishing zebrafish pen/lgl2 mutants as a valuable cancer model

Interleukin-12p40 Modulates Human Metapneumovirus-Induced Pulmonary Disease in an Acute Mouse Model of Infection

The mechanisms that regulate the host immune response induced by human metapneumovirus (hMPV), a newly-recognized member of the Paramyxoviridae family, are largely unknown. Cytokines play an important role in modulating inflammatory responses during viral infections. IL-12p40, a known important mediator in limiting lung inflammation, is induced by hMPV and its production is sustained after the resolution phase of infection suggesting that this cytokine plays a role in the immune response against hMPV. In this work, we demonstrated that in mice deficient in IL-12p40, hMPV infection induced an exacerbated pulmonary inflammatory response and mucus production, altered cytokine response, and decreased lung function. However, hMPV infection in these mice does not have an effect on viral replication. These results identify an important regulatory role of IL-12p40 in hMPV infection

CCN3 modulates bone turnover and is a novel regulator of skeletal metastasis

The CCN family of proteins is composed of six secreted proteins (CCN1-6), which are grouped together based on their structural similarity. These matricellular proteins are involved in a large spectrum of biological processes, ranging from development to disease. In this review, we focus on CCN3, a founding member of this family, and its role in regulating cells within the bone microenvironment. CCN3 impairs normal osteoblast differentiation through multiple mechanisms, which include the neutralization of pro-osteoblastogenic stimuli such as BMP and Wnt family signals or the activation of pathways that suppress osteoblastogenesis, such as Notch. In contrast, CCN3 is known to promote chondrocyte differentiation. Given these functions, it is not surprising that CCN3 has been implicated in the progression of primary bone cancers such as osteosarcoma, Ewing’s sarcoma and chondrosarcoma. More recently, emerging evidence suggests that CCN3 may also influence the ability of metastatic cancers to colonize and grow in bone

Ste20-Related Proline/Alanine-Rich Kinase (SPAK) Regulated Transcriptionally by Hyperosmolarity Is Involved in Intestinal Barrier Function

The Ste20-related protein proline/alanine-rich kinase (SPAK) plays important roles in cellular functions such as cell differentiation and regulation of chloride transport, but its roles in pathogenesis of intestinal inflammation remain largely unknown. Here we report significantly increased SPAK expression levels in hyperosmotic environments, such as mucosal biopsy samples from patients with Crohn's disease, as well as colon tissues of C57BL/6 mice and Caco2-BBE cells treated with hyperosmotic medium. NF-κB and Sp1-binding sites in the SPAK TATA-less promoter are essential for SPAK mRNA transcription. Hyperosmolarity increases the ability of NF-κB and Sp1 to bind to their binding sites. Knock-down of either NF-κB or Sp1 by siRNA reduces the hyperosmolarity-induced SPAK expression levels. Furthermore, expression of NF-κB, but not Sp1, was upregulated by hyperosmolarity in vivo and in vitro. Nuclear run-on assays showed that hyperosmolarity increases SPAK expression levels at the transcriptional level, without affecting SPAK mRNA stability. Knockdown of SPAK expression by siRNA or overexpression of SPAK in cells and transgenic mice shows that SPAK is involved in intestinal permeability in vitro and in vivo. Together, our data suggest that SPAK, the transcription of which is regulated by hyperosmolarity, plays an important role in epithelial barrier function