Small molecule inhibitors of the host cell COX/AREG/EGFR/ERK pathway attenuate cytomegalovirus-induced pathogenesis

Abstract

As with other herpesviruses, human cytomegalovirus (hCMV) has the ability to establish lifelong persistence and latent infection following primary exposure, salivary glands (SMGs) being the primary site of both. In the immunocompromised patient, hCMV is a common cause of opportunistic infections, and subsequent morbidity and mortality. Elucidating the molecular pathogenesis of CMV-induced disease is critical to the development of more effective and safer drug therapies. In the present study, we used a novel mouse postnatal SMG organ culture model of mCMV-induced dysplasia to investigate a candidate signaling network suggested by our prior studies (COX-2/AREG/EGFR/ERK). The objective was to employ small molecule inhibitors to target several key steps in the autocrine loop, and in this way ameliorate pathology. Our results indicate that upregulation of ERK phosphorylation is necessary for initial mCMV-induced pathogenesis, and that ErbB receptor family phosphorylation and downstream signaling are highly relevant targets for drug discovery.

Cytomegalovirus-induced salivary gland pathology: AREG, FGF8, TNF-α, and IL-6 signal dysregulation and neoplasia

“…That human SG-MEC is a virally implicated pathology, is further supported by our finding that purified mouse CMV (mCMV) induces cellular pathology in an in vitro mouse SG organ model that displays a number of histologic and molecular characteristics similar to human MEC Melnick et al, 2011). Specifically, we have demonstrated that mCMV induces (1) mesenchymal-to-epithelial transformation (MET); (2) epithelial and mesenchymal hyperplasia, dysplasia and neoplasia; (3) loss of basement membrane zone components, reduced expression of epithelial-specific adherens junction proteins (E-cadherin, p120), and admixing of stromal-derived and epithelial-derived cells; (4) expression of CRTC1 protein, a protein found in SG MECs but not in normal SG tissue (Tirado et al, 2007); and (5) upregulation of the activated COX/AREG/EGFR/ERK signaling pathway.…”

“…Despite the well-documented overexpression of the EGFR → ERK signaling pathway in MEC (Akrish et al, 2009;Ito et al, 2009;Lujan et al, 2010), there has been limited to no success with inhibition of this pathway (Bell and Hanna, 2012;Gillespie et al, 2012), not unlike that seen with other malignancies (Engelman and Settleman, 2008). Using our previously described mouse model of CMV-induced SG dysplasia/neoplasia Melnick et al, 2011), we provide evidence that concurrent inhibition of ERK phosphorylation and inhibition of CMV replication obviates progressive pathogenesis and results in complete SG rescue (regression). These findings provide a mechanistic foundation for clinical trials that utilize similar concurrent treatment with extant FDA-approved drugs.…”

“…To this end, one has always to discern patterns of covarying molecular and histopathologic phenotypes, relating measurements and localization of transcripts and proteins (input) to a well-characterized pathologic phenotype (output). Here we utilize an in vitro 3D submandibular gland (SMG) organ culture strategy previously shown to induce cellular pathology resembling secretory gland neoplasia Melnick et al, 2006Melnick et al, , 2011.…”

HCMV infection triggers smooth muscle cell proliferation in a 3D human coronary in vitro model

“…A different activity of HCMV in seropositive patients may be the explanation for the contradicting results in clinical trials, comparing seropositivity of individuals with the occurrence of restenosis or atherosclerosis. Recently Melnick et al, [30] suggested that upregulation of ERK phosphorylation is necessary for initial HCMV induced pathogenesis. The presented models are suitable for further studies on stimulatory and inhibitory effects of HCMV-infection in human coronary cells.…”

The C11R Gene, Which Encodes the Vaccinia Virus Growth Factor, Is Partially Responsible for MVA-Induced NF-κB and ERK2 Activation

“…This exemplifies a sophisticated approach that poxviruses employ to differentially manipulate EGFR-triggered events for their benefit. Proper EGFR signal transduction is critical for the entry of several virus types into cells (14,36), and aberrant EGFR expression or signaling is associated with certain types of cancers (39). Thus, identifying how VACV modulates EGFR-mediated signal transduction pathways could likely yield new approaches and targets for antiviral or anticancer therapies.…”