A complex of Wnt/planar cell polarity signaling components Vangl1 and Fzd7 drives glioblastoma multiforme malignant properties

Targeting common oncogenic drivers of glioblastoma multiforme (GBM) in patients has remained largely ineffective, raising the possibility that alternative pathways may contribute to tumor aggressiveness. Here we demonstrate that Vangl1 and Fzd7, components of the non-canonical Wnt planar cell polarity (Wnt/PCP) signaling pathway, promote GBM malignancy by driving cellular proliferation, migration, and invasiveness, and engage Rho GTPases to promote cytoskeletal rearrangements and actin dynamics in migrating GBM cells. Mechanistically, we uncover the existence of a novel Vangl1/Fzd7 complex at the leading edge of migrating GBM cells and propose that this complex is critical for the recruitment of downstream effectors to promote tumor progression. Moreover, we observe that depletion of FZD7 results in a striking suppression of tumor growth and latency and extends overall survival in an intracranial mouse xenograft model. Our observations support a novel mechanism by which Wnt/PCP components Vangl1 and Fzd7 form a complex at the leading edge of migratory GBM cells to engage downstream effectors that promote actin cytoskeletal rearrangements dynamics. Our findings suggest that interference with Wnt/PCP pathway function may offer a novel therapeutic strategy for patients diagnosed with GBM

How to Be in the World, Not of It: The Rhetoric of Place, Time, and Subjectivity in Independent Christian Cinema

This thesis project explores three prominent films developed as part of the Christian independent film industry between 1970 and 2014. Drawing on Sara Ahmed’s work in affect theory, I identify how certain films resonated with the U.S. Evangelical subculture during times of cultural shift and, thus, strengthened affective orientations among members of the Evangelical community who consumed them. Released in 1970, The Cross and the Switchblade strengthens fears of urban decay to encourage evangelism and social reform in a conservative response to the Civil Rights movement and the perception of rising urban crime. At the turn of the century, The Omega Code (1999) assured Christians that though the Religious Right was failing, true Christians would always succeed in the end if they trusted in God’s divine timeline. Finally, God’s Not Dead (2014) validated feelings of Christian persecution and a need to unite Christians under a single totalizing identity. Throughout the thesis, I consistently return to the phrase, “in the world, not of the world,” arguing that the affective and rhetorical arguments in each of these films offer a different interpretation of the edict within their specific historical context. Keywords: Christian Cinema, Affect, Film, Religio

Elucidation of Key Signaling Components in Development and Cancer: Wnt/Planar Cell Polarity Contribution to Glioblastoma Multiforme Aggressiveness and the Role of Mucin-4 in Mammary Gland Development and Breast Cancer Metastasis

Tumorigenesis is a multistep process wherein normal cells lose their original cellular properties and gain malignant characteristics to initiate the formation of tumors. The means by which cells are transformed and acquire tumorigenic properties is complex, and largely context- and tissue-dependent. However, a reoccurring theme in cancer is that tumor cells can both hijack and reactivate developmental pathways or repurpose and exploit constitutively expressed proteins critical to tissue homeostasis, to drive their aggressive properties. Critically, understanding the function of these key signaling components during development and in normal tissues, and how they are aberrantly engaged by tumors, could provide insight into promising therapeutic approaches to benefit patients. This dissertation features the current research of two distinct signal transduction components critical to development and cancer progression: (1) the contribution of Wnt/Planar cell polarity (PCP) signaling to glioblastoma multiforme (GBM) aggressiveness, and (2) the role of Mucin-4 (Muc4) in mammary branching morphogenesis. Discussion of each finding is preceded by a review of the literature highlighting our current knowledge of Wnt/PCP signaling or Muc4 in development and disease. Wnt/PCP signaling is a branch of noncanonical Wnt signaling critical to the establishment of tissue polarity during embryonic development. Recent studies have implicated Wnt/PCP signaling components in driving the progression of several solid tumor types. However, many of the mechanistic details underlying how these components are engaged in tumor cells remain elusive. Here, we identify a critical role for Wnt/PCP components Vangl1 and Fzd7 in mediating GBM progression. Vangl1 and Fzd7 regulate GBM cell proliferation, migration, and invasion, and engage downstream Rho GTPases to mediate actin dynamics. Vangl1 and Fzd7 colocalize and interact within cellular protrusions in migrating GBM cells, where they may engage downstream effectors to yield biological outcomes. Further, loss of FZD7 significantly affects GBM tumor growth and survival in vivo, suggesting that targeting of this pathway could provide clinical benefit to patients diagnosed with GBM. Muc4 is a large cell surface glycoprotein that functions to lubricate and protect epithelial and vascular surfaces. Muc4 has been widely studied in a variety of tumor types, but it is most well-characterized in breast cancer, where it drives breast cancer progression and metastasis. However, little is known about the function of Muc4 in the normal mammary gland and its role during mammary gland development. Here, using a genetically engineered Muc4 knockout mouse, we identify a role for Muc4 in regulating mammary branching morphogenesis. Muc4 is expressed throughout the mammary epithelium and is critical to proper mammary branching during adolescent development. Our understanding of the mechanisms by which Muc4 is involved in these processes could provide insight to additional roles for Muc4 in mediating breast cancer metastasis

Vangl as a Master Scaffold for Wnt/Planar Cell Polarity Signaling in Development and Disease

The establishment of polarity within tissues and dynamic cellular morphogenetic events are features common to both developing and adult tissues, and breakdown of these programs is associated with diverse human diseases. Wnt/Planar cell polarity (Wnt/PCP) signaling, a branch of non-canonical Wnt signaling, is critical to the establishment and maintenance of polarity in epithelial tissues as well as cell motility events critical to proper embryonic development. In epithelial tissues, Wnt/PCP-mediated planar polarity relies upon the asymmetric distribution of core proteins to establish polarity, but the requirement for this distribution in Wnt/PCP-mediated cell motility remains unclear. However, in both polarized tissues and migratory cells, the Wnt/PCP-specific transmembrane protein Vangl is required and appears to serve as a scaffold upon which the core pathway components as well as positive and negative regulators of Wnt/PCP signaling assemble. The current literature suggests that the multiple interaction domains of Vangl allow for the binding of diverse signaling partners for the establishment of context- and tissue-specific complexes. In this review we discuss the role of Vangl as a master scaffold for Wnt/PCP signaling in epithelial tissue polarity and cellular motility events in developing and adult tissues, and address how these programs are dysregulated in human disease

The role of membrane mucin MUC4 in breast cancer metastasis.

A major barrier to the emergence of distant metastases is the survival of circulating tumor cells (CTCs) within the vasculature. Lethal stressors, including shear forces from blood flow, anoikis arising from cellular detachment, and exposure to natural killer cells, combine to subvert the ability of primary tumor cells to survive and ultimately seed distant lesions. Further attenuation of this rate-limiting process via therapeutic intervention offers a very attractive opportunity for improving cancer patient outcomes, in turn prompting the need for a deeper understanding of the molecular and cellular mechanisms underlying CTC viability. MUC4 is a very large and heavily glycosylated protein expressed at the apical surfaces of the epithelia of a variety of tissues, is involved in cellular growth signaling and adhesiveness, and contributes to the protection and lubrication of cellular linings. Analysis of patient-matched breast tumor specimens has demonstrated that MUC4 protein levels are upregulated in metastatic lesions relative to primary tumor among all breast tumor subtypes, pointing to a possible selective advantage for MUC4 overexpression in metastasis. Analysis of a genetically engineered mouse model of HER2-positive breast cancer has demonstrated that metastatic efficiency is markedly suppressed with Muc4 deletion and Muc4-knockout tumor cells are poorly associated with platelets and white blood cells known to support CTC viability. In this review, we discuss the diverse roles of MUC4 in tumor progression and metastasis and propose that intervening in MUC4 intercellular interactions with binding partners on blood-borne aggregating cells could potentially thwart breast cancer metastatic efficiency

HER2 amplification in tumors activates PI3K/Akt signaling independent of HER3

Current evidence suggests that HER2-driven tumorigenesis requires HER3. This is likely due to the unique ability of HER3 to activate PI3K/Akt pathway signaling, which is not directly accessible to HER2. By genetic elimination of HER3 or shRNA knockdown of HER3 in HER2-amplified cancer cells, we find residual HER2-driven activation of PI3K/Akt pathway signaling that is driven by HER2 through direct and indirect mechanisms. Indirect mechanisms involved second messenger pathways, including Ras or Grb2. Direct binding of HER2 to PI3K occurred through p-Tyr1139, which has a weak affinity for PI3K but becomes significant at very high expression and phosphorylation. Mutation of Y1139 impaired the tumorigenic competency of HER2. Total elimination of HER3 expression in HCC1569 HER2-amplified cancer cells significantly impaired tumorigenicity only transiently, overcome by subsequent increases in HER2 expression and phosphorylation with binding and activation of PI3K. In contrast to activation of oncogenes by mutation, activation by overexpression was quantitative in nature: weak intrinsic activities were strengthened by overexpression, with additional gains observed through further increases in expression. Collectively, these data show that progressive functional gains by HER2 can increase its repertoire of activities such as the activation of PI3K and overcome its dependency on HER3.Significance: The intrinsic ability of HER2 to activate PI3K correlates with increased HER2 expression and can supplant the dependency upon HER3 for growth in HER2-amplified cancers. Cancer Res; 78(13); 3645-58. ©2018 AACR