Targeted mRNA Therapy for Ornithine Transcarbamylase Deficiency.

We describe a novel, two-nanoparticle mRNA delivery system and show that it is highly effective as a means of intracellular enzyme replacement therapy (i-ERT) using a murine model of ornithine transcarbamylase deficiency (OTCD). Our Hybrid mRNA Technology delivery system (HMT) comprises an inert lipid nanoparticle that protects the mRNA from nucleases in the blood as it distributes to the liver and a polymer micelle that targets hepatocytes and triggers endosomal release of mRNA. This results in high-level synthesis of the desired protein specifically in the liver. HMT delivery of human OTC mRNA normalizes plasma ammonia and urinary orotic acid levels, and leads to a prolonged survival benefit in the murine OTCD model. HMT represents a unique, non-viral mRNA delivery method that allows multi-dose, systemic administration for treatment of single-gene inherited metabolic diseases.

Targeting Bcr-Abl by combining allosteric with ATP-binding-site inhibitors.

In an effort to find new pharmacological modalities to overcome resistance to ATP-binding-site inhibitors of Bcr-Abl, we recently reported the discovery of GNF-2, a selective allosteric Bcr-Abl inhibitor. Here, using solution NMR, X-ray crystallography, mutagenesis and hydrogen exchange mass spectrometry, we show that GNF-2 binds to the myristate-binding site of Abl, leading to changes in the structural dynamics of the ATP-binding site. GNF-5, an analogue of GNF-2 with improved pharmacokinetic properties, when used in combination with the ATP-competitive inhibitors imatinib or nilotinib, suppressed the emergence of resistance mutations in vitro, displayed additive inhibitory activity in biochemical and cellular assays against T315I mutant human Bcr-Abl and displayed in vivo efficacy against this recalcitrant mutant in a murine bone-marrow transplantation model. These results show that therapeutically relevant inhibition of Bcr-Abl activity can be achieved with inhibitors that bind to the myristate-binding site and that combining allosteric and ATP-competitive inhibitors can overcome resistance to either agent alone.

Targeting Wnt-driven cancer through the inhibition of Porcupine by LGK974.

Wnt signaling is one of the key oncogenic pathways in multiple cancers, and targeting this pathway is an attractive therapeutic approach. However, therapeutic success has been limited because of the lack of therapeutic agents for targets in the Wnt pathway and the lack of a defined patient population that would be sensitive to a Wnt inhibitor. We developed a screen for small molecules that block Wnt secretion. This effort led to the discovery of LGK974, a potent and specific small-molecule Porcupine (PORCN) inhibitor. PORCN is a membrane-bound O-acyltransferase that is required for and dedicated to palmitoylation of Wnt ligands, a necessary step in the processing of Wnt ligand secretion. We show that LGK974 potently inhibits Wnt signaling in vitro and in vivo, including reduction of the Wnt-dependent LRP6 phosphorylation and the expression of Wnt target genes, such as AXIN2. LGK974 is potent and efficacious in multiple tumor models at well-tolerated doses in vivo, including murine and rat mechanistic breast cancer models driven by MMTV-Wnt1 and a human head and neck squamous cell carcinoma model (HN30). We also show that head and neck cancer cell lines with loss-of-function mutations in the Notch signaling pathway have a high response rate to LGK974. Together, these findings provide both a strategy and tools for targeting Wnt-driven cancers through the inhibition of PORCN.

Smad7-induced beta-catenin degradation alters epidermal appendage development.

To assess whether Smad signaling affects skin development, we generated transgenic mice in which a Smad antagonist, Smad7, was induced in keratinocytes, including epidermal stem cells. Smad7 transgene induction perturbed hair follicle morphogenesis and differentiation, but accelerated sebaceous gland morphogenesis. Further analysis revealed that independent of its role in anti-Smad signaling, Smad7 bound beta-catenin and induced beta-catenin degradation by recruiting an E3 ligase, Smurf2, to the Smad7/beta-catenin complex. Consequently, Wnt/beta-catenin signaling was suppressed in Smad7 transgenic hair follicles. Coexpression of the Smurf2 and Smad7 transgenes exacerbated Smad7-induced abnormalities in hair follicles and sebaceous glands. Conversely, when endogenous Smad7 was knocked down, keratinocytes exhibited increased beta-catenin protein and enhanced Wnt signaling. Our data reveal a mechanism for Smad7 in antagonizing Wnt/beta-catenin signaling, thereby shifting the skin differentiation program from forming hair follicles to sebaceous glands.

Distinct mechanisms of TGF-beta1-mediated epithelial-to-mesenchymal transition and metastasis during skin carcinogenesis.

In the present study, we demonstrated that human skin cancers frequently overexpress TGF-beta1 but exhibit decreased expression of the TGF-beta type II receptor (TGF-(beta)RII). To understand how this combination affects cancer prognosis, we generated a transgenic mouse model that allowed inducible expression of TGF-beta(1) in keratinocytes expressing a dominant negative TGF-(beta)RII (Delta(beta)RII) in the epidermis. Without Delta(beta)RII expression, TGF-beta1 transgene induction in late-stage, chemically induced papillomas failed to inhibit tumor growth but increased metastasis and epithelial-to-mesenchymal transition (EMT), i.e., formation of spindle cell carcinomas. Interestingly, Delta(beta)RII expression abrogated TGF-beta1-mediated EMT and was accompanied by restoration of membrane-associated E-cadherin/catenin complex in TGF-beta1/Delta(beta)RII compound tumors. Furthermore, expression of molecules thought to mediate TGF-beta1-induced EMT was attenuated in TGF-beta1/Delta(beta)RII-transgenic tumors. However, TGF-beta1/Delta(beta)RII-transgenic tumors progressed to metastasis without losing expression of the membrane-associated E-cadherin/catenin complex and at a rate higher than those observed in nontransgenic, TGF-beta1-transgenic, or Delta(beta)RII-transgenic mice. Abrogation of Smad activation by Delta(beta)RII correlated with the blockade of EMT. However, Delta(beta)RII did not alter TGF-beta1-mediated expression of RhoA/Rac and MAPK, which contributed to increased metastasis. Our study provides evidence that TGF-beta1 induces EMT and invasion via distinct mechanisms. TGF-beta1-mediated EMT requires functional TGF-(beta)RII, whereas TGF-beta1-mediated tumor invasion cooperates with reduced TGF-(beta)RII signaling in tumor epithelia.

Elevation of transforming growth factor beta (TGFbeta) and its downstream mediators in subcutaneous foreign body capsule tissue.

Foreign body encapsulation represents a chronic fibrotic response and has been a major obstacle that reduces the useful life of implanted biomedical devices. The precise mechanism underlying such an encapsulation is still unknown. We hypothesized that, considering its central role in many other fibrotic conditions, transforming growth factor beta (TGFbeta) may play an important role during the formation of foreign body capsule (FBC). In the present study, we implanted mock sensors in rats subcutaneously and excised FBC samples at day 7, 21, and 48-55 postimplantation. The most abundant TGFbeta isoform in all tissues was TGFbeta1, which was expressed minimally in control tissue. The expression of both TGFbeta1 RNA and protein was significantly increased in FBC tissues at all time points, with the highest level in day 7 FBC. The number of cells stained for phosphorylated Smad2, an indication of activated TGFbeta signaling, paralleled the expression of TGFbeta. A similar dynamic change was also observed in the numbers of FBC myofibroblasts, which in response to TGFbeta, differentiate from quiescent fibroblasts and synthesize collagen. Type I collagen, the most prominent downstream target of TGFbeta in fibrosis, was found in abundance in the FBC, especially during the latter time periods. We suggest that TGFbeta plays an important role in the FBC formation. Inhibition of TGFbeta signaling could be a promising strategy in the prevention of FBC formation, thereby extending the useful life of subcutaneous implants.

Roles of TGFbeta signaling in epidermal/appendage development.

The transforming growth factor beta (TGFbeta) superfamily encompasses a number of structurally related proteins that can be divided into several subfamilies including TGFbetas, activins/inhibins and bone morphogenetic proteins (BMPs). The Smads are major intracellular mediators in transducing the signals of TGFbeta superfamily members, and are abundantly expressed in the developing epidermis and epidermal appendages. Moreover, the phenotypes of transgenic/knockout mice with altered components of the TGFbeta superfamily signaling pathway suggest that TGFbeta superfamily signaling is required for epidermal/appendage development. TGFbeta superfamily members are involved in most events during epidermal/appendage development through the TGFbeta signal transduction pathway and through cross talk with other signaling pathways. Future studies will be instrumental in defining the precise roles for TGFbeta superfamily signaling in epidermal/appendage development.

Smad3 knockout mice exhibit a resistance to skin chemical carcinogenesis.

It has been shown that Smad3 exerts both tumor-suppressive and -promoting roles. To evaluate the role of Smad3 in skin carcinogenesis in vivo, we applied a chemical skin carcinogenesis protocol to Smad3 knockout mice (Smad3(-/-) and Smad3(+/-)) and wild-type littermates (Smad3(+/+)). Smad3(-/-) mice exhibited reduced papilloma formation in comparison with Smad3(+/+) mice and did not develop any squamous cell carcinomas. Further analysis revealed that Smad3 knockout mice were resistant to 12-O-tetradecanoylphorbol-13-acetate (TPA)-induced epidermal hyperproliferation. Concurrently, increased apoptosis was observed in TPA-treated Smad3(-/-) skin and papillomas when compared with those of wild-type mice. Expression levels of activator protein-1 family members (c-jun, junB, junD, and c-fos) and transforming growth factor (TGF)-alpha were significantly lower in TPA-treated Smad3(-/-) skin, cultured keratinocytes, and papillomas, as compared with Smad3(+/+) controls. Smad3(-/-) papillomas also exhibited reduced leukocyte infiltration, particularly a reduction of tumor-associated macrophage infiltration, in comparison with Smad3(+/+) papillomas. All of these molecular and cellular alterations also occurred to a lesser extent in Smad3(+/-) mice as compared with Smad3(+/+) mice, suggesting a Smad3 gene dosage effect. Given that TGF-beta1 is a well-documented TPA-responsive gene and also has a potent chemotactic effect on macrophages, our study suggests that Smad3 may be required for TPA-mediated tumor promotion through inducing TGF-beta1-responsive genes, which are required for tumor promotion, and through mediating TGF-beta1-induced macrophage infiltration.

Overexpression of transforming growth factor beta1 in head and neck epithelia results in inflammation, angiogenesis, and epithelial hyperproliferation.

In the present study, we show that transforming growth factor beta1 (TGF-beta1) was frequently overexpressed in human head and neck squamous cell carcinomas (HNSCCs) and adjacent tissues in comparison with normal head and neck tissues. To determine the role of TGF-beta1 overexpression in HNSCC carcinogenesis, we generated transgenic mice in which TGF-beta1 transgene expression can be induced in head and neck epithelia. TGF-beta1 transgene induction in head and neck epithelia, at levels similar to those in human HNSCCs, caused severe inflammation and angiogenesis. Consequently, TGF-beta1-transgenic epithelia exhibited hyperproliferation. These phenotypes correlated with enhanced Smad signaling in transgenic epithelia and stroma. Our study suggests that TGF-beta1 overexpression at early stages of HNSCC formation provides a tumor promoting microenvironment.

Synthesis, structure-activity relationships, and in vivo efficacy of the novel potent and selective anaplastic lymphoma kinase (ALK) inhibitor 5-chloro-N2-(2-isopropoxy-5-methyl-4-(piperidin-4-yl)phenyl)-N4-(2-(isopropylsulfonyl)phenyl)pyrimidine-2,4-diamine (LDK378) currently in phase 1 and phase 2 clinical trials.

The synthesis, preclinical profile, and in vivo efficacy in rat xenograft models of the novel and selective anaplastic lymphoma kinase inhibitor 15b (LDK378) are described. In this initial report, preliminary structure-activity relationships (SARs) are described as well as the rational design strategy employed to overcome the development deficiencies of the first generation ALK inhibitor 4 (TAE684). Compound 15b is currently in phase 1 and phase 2 clinical trials with substantial antitumor activity being observed in ALK-positive cancer patients.

Fuz controls the morphogenesis and differentiation of hair follicles through the formation of primary cilia.

Planar cell polarity (PCP) signaling is essential in determining the polarity of cells within the plane of an epithelial sheet. Core PCP genes have been recently shown to control the global polarization of hair follicles in mice. Fuz, a homologue of the Drosophila PCP effector gene, fuzzy, is critical in ciliogenesis in vertebrates, and is required for the development of a wide range of organs in mice. Here, we report that disruption of the Fuz gene in mice severely blocked the development of hair follicles in the skin. In contrast to the loss of hair follicle polarization in mice deficient in core PCP genes, hair follicles in mice lacking the Fuz gene retained their typical anterior-posterior orientation. We show that disruption of Fuz impaired the formation of primary cilia and the hedgehog signaling pathway in the skin. In addition, using skin grafts and skin reconstitution assays we demonstrate that the expression of Fuz is required in both epidermal and dermal cells and that the formation of primary cilia is a cell-autonomous process that does not require cross talk between the epithelia and mesenchymal compartments during hair follicle formation.

A role for TGFbeta signaling in the pathogenesis of psoriasis.

Deregulation of transforming growth factor-beta (TGFbeta) signaling has been reported in human psoriasis. Our recent study using a keratin 5 promoter (K5.TGFbeta1(wt)) showed that transgenic mice expressing wild-type TGFbeta1 in the epidermis developed severe skin inflammation. Additional experimental data further support a direct role for TGFbeta1 overexpression in skin inflammation. First, we temporally induced TGFbeta1 expression in keratinocytes in our gene-switch TGFbeta1(wt) transgenic mice and found inflammation severity correlated with TGFbeta1(wt) transgene expression. Second, deletion of T cells in K5.TGFbeta1(wt) mice significantly delayed skin inflammation and associated epidermal hyperplasia/hyperkeratosis. Third, therapeutic approaches effective for human psoriasis, that is, Etanercept and Rosiglitazone, are effective in alleviating the symptoms observed in K5.TGFbeta1(wt) mice. Future studies will analyze specific mechanisms and identify key factors in TGFbeta1-induced skin inflammation. Our mouse models will provide a useful tool for understanding the molecular mechanisms of inflammatory skin disorders in which TGFbeta1 is overexpressed.

The role of Smads in skin development.

Smads are a group of signaling mediators and antagonists of the transforming growth factor-beta (TGF-beta) superfamily, responding but not limited to signaling from TGF-beta, Activin, and bone morphogenetic proteins (BMPs). As all of these three signaling pathways play important roles in skin development, we have been actively pursuing studies assessing the role of Smads in skin development. Our studies revealed that Smad-4 affects hair follicle differentiation primarily by mediating BMP signaling. Smad-7 significantly affects hair follicle development and differentiation by blocking the TGFbeta/Activin/BMP pathway and by inhibiting WNT/beta-catenin signaling via ubiquitin-mediated beta-catenin degradation. In contrast, other Smads may have redundant or dispensable functions in skin development. Here, we review the work that shows the emergence of Smad functions in skin development via traditional and novel signaling pathways.

Increased expression of Interleukin-13 and connective tissue growth factor, and their potential roles during foreign body encapsulation of subcutaneous implants.

The purpose of this study was to better understand whether interleukin-13 (IL-13) and connective tissue growth factor (CTGF) are highly expressed during foreign body encapsulation of subcutaneous devices. Mock biosensors were implanted into rats for three lengths of time (7-, 21- and 48-55 days) to address different stages of the foreign body response. Using quantitative real-time PCR and immunofluorescence, the expression of IL13, CTGF, collagen 1, decorin and fibronectin were measured in this tissue. IL-13, a product of Th2 cells, was highly expressed at all time points, with greatest expression at day 21. The IL-13 expression was paralleled by increased presence of T-cells at all time points. CTGF was also found to be more highly expressed in foreign body tissue than in controls. Collagen and decorin were highly expressed at the middle and later stages. Given the increased expression of IL-13 and CTGF in foreign body tissue, and their roles in other fibrotic disorders, these cytokines may well contribute to the formation of the foreign body capsule. Since the peak gene expression of IL-13 occurred later than the previously-reported TGFbeta expression peak, IL-13 is probably not the major stimulus to TGFbeta expression during foreign body encapsulation and may contribute to fibrosis independently.

Smad7 binds to the adaptors TAB2 and TAB3 to block recruitment of the kinase TAK1 to the adaptor TRAF2.

Transforming growth factor-beta1 (TGF-beta1) regulates inflammation and can inhibit activation of the transcription factor NF-kappaB in certain cell types. Here we show that the TGF-beta-induced signaling protein Smad7 bound to TAB2 and TAB3, which are adaptors that link the kinase TAK1 to 'upstream' regulators in the proinflammatory tumor necrosis factor (TNF) signaling pathway. Smad7 thereby promoted TGF-beta-mediated anti-inflammatory effects. The formation of Smad7-TAB2 and Smad7-TAB3 complexes resulted in the suppression of TNF signaling through the adaptors TRAF2, TAB2 and/or TAB3, and TAK1. Furthermore, expression of a transgene encoding Smad7 in mouse skin suppressed inflammation and NF-kappaB nuclear translocation substantially and disrupted the formation of endogenous TRAF2-TAK1-TAB2 and TRAF2-TAK1-TAB3 complexes. Thus, Smad7 is a critical mediator of TGF-beta signals that block proinflammatory TNF signals.

Loss of transforming growth factor-beta type II receptor promotes metastatic head-and-neck squamous cell carcinoma.

The prognosis of head-and-neck squamous cell carcinoma (HNSCC) has not been improved in the past 20 years. Validation of HNSCC biomarkers for targeted therapy has been hindered by a lack of animal models mimicking human HNSCC at both the pathological and molecular levels. Here we report that overexpression of K-ras or H-ras and loss of transforming growth factor-beta type II receptor (TGFbetaRII) are common events in human HNSCC. Activation of either K-ras or H-ras in combination with TGFbetaRII deletion from mouse head-and-neck epithelia caused HNSCC with complete penetrance, some of which progressed to metastases. These tumors displayed pathology indistinguishable from human HNSCCs and exhibited multiple molecular alterations commonly found in human HNSCCs. Additionally, elevated endogenous TGFbeta1 in these lesions contributed to inflammation and angiogenesis. Our data suggest that targeting common oncogenic pathways in tumor epithelia together with blocking the effect of TGFbeta1 on tumor stroma may provide a novel therapeutic strategy for HNSCC.

Signaling mechanism of TGF-beta1 in prevention of renal inflammation: role of Smad7.

TGF-beta has been shown to play a critical role in anti-inflammation; however, the signaling mechanisms of TGF-beta in anti-inflammatory response remains largely unclear. This study reported that mice that overexpress latent TGF-beta1 on skin are protected against renal inflammation in a model of obstructive kidney disease and investigated the signaling mechanism of TGF-beta1 in inhibition of renal inflammation in vivo and in vitro. Seven days after urinary obstruction, wild-type mice developed severe renal inflammation, including massive T cell and macrophage infiltration and marked upregulation of IL-1beta, TNF-alpha, and intercellular adhesion molecule-1 (all P < 0.001). Surprising, renal inflammation was prevented in transgenic mice. This was associated with an increase in latent TGF-beta1 in circulation (a 10-fold increase) and renal tissues (a 2.5-fold increase). Further studies showed that inhibition of renal inflammation in TGF-beta1 transgenic mice was also associated with a marked upregulation of renal Smad7 and IkappaBalpha and a suppression of NF-kappaB activation in the diseased kidney (all P < 0.01). These in vivo findings suggested the importance of TGF-beta-NF-kappaB cross-talk signaling pathway in regulating renal inflammation. This was tested in vitro in a doxycycline-regulated Smad7-expressing renal tubular cell line. Overexpression of Smad7 was able to upregulate IkappaBalpha directly in a time- and dose-dependent manner, thereby inhibiting NF-kappaB activation and NF-kappaB-driven inflammatory response. In conclusion, latent TGF-beta may have protective roles in renal inflammation. Smad7-mediated inhibition of NF-kappaB activation via the induction of IkBalpha may be the central mechanism by which latent TGF-beta prevents renal inflammation.

Latent TGFbeta1 overexpression in keratinocytes results in a severe psoriasis-like skin disorder.

Transforming growth factor beta1 (TGFbeta1), a potent keratinocyte growth inhibitor, has been shown to be overexpressed in keratinocytes in certain inflammatory skin diseases and has been thought to counteract the effects of other growth factors at the site of inflammation. Surprisingly, our transgenic mice expressing wild-type TGFbeta1 in the epidermis using a keratin 5 promoter (K5.TGFbeta1(wt)) developed inflammatory skin lesions, with gross appearance of psoriasis-like plaques, generalized scaly erythema, and Koebner's phenomenon. These lesions were characterized by epidermal hyperproliferation, massive infiltration of neutrophils, T lymphocytes, and macrophages to the epidermis and superficial dermis, subcorneal microabscesses, basement membrane degradation, and angiogenesis. K5.TGFbeta1(wt) skin exhibited multiple molecular changes that typically occur in human Th1 inflammatory skin disorders, such as psoriasis. Further analyses revealed enhanced Smad signaling in transgenic epidermis and dermis. Our study suggests that certain pathological condition-induced TGFbeta1 overexpression in the skin may synergize with or induce molecules required for the development of Th1 inflammatory skin disorders.

Essential roles of BMPR-IA signaling in differentiation and growth of hair follicles and in skin tumorigenesis.

Hair differentiation and growth are controlled by complex reciprocal signaling between epithelial and mesenchymal cells. To better understand the requirement and molecular mechanism of BMP signaling in hair follicle development, we performed genetic analyses of bone morphogenetic protein receptor 1A (BMPR-IA) function during hair follicle development by using a conditional knockout approach. The conditional mutation of Bmpr1a in ventral limb ectoderm and its derivatives (epidermis and hair follicles) resulted in a lack of hair outgrowth from the affected skin regions. Mutant hair follicles exhibited abnormal morphology and lacked hair formation and pigment deposition during anagen. The timing of the hair cycle and the proliferation of hair matrix cells were also affected in the mutant follicles. We demonstrate that signaling via epithelial BMPR-IA is required for differentiation of both hair shaft and inner root sheath from hair matrix precursor cells in anagen hair follicles but is dispensable for embryonic hair follicle induction. Surprisingly, aberrant de novo hair follicle morphogenesis together with hair matrix cell hyperplasia was observed in the absence of BMPR-IA signaling within the affected skin of adult mutants. They developed hair follicle tumors from 3 months of age, indicating that inactivation of epidermal BMPR-IA signaling can lead to hair tumor formation. Taken together, our data provide genetic evidence that BMPR-IA signaling plays critical and multiple roles in controlling cell fate decisions or maintenance, proliferation, and differentiation during hair morphogenesis and growth, and implicate Bmpr1a as a tumor suppressor in skin tumorigenesis.

Overexpression of Smad7 results in severe pathological alterations in multiple epithelial tissues.

Biochemical studies have shown that Smad7 blocks signal transduction of transforming growth factor beta (TGFbeta); however, its in vivo functions are largely unknown. To determine the functions of Smad7, we have expressed Smad7 in transgenic mice, utilizing a keratin K5 promoter (K5.Smad7). K5.Smad7 mice exhibited pathological changes in multiple tissues and died within 10 days after birth. These mice were born with open eyelids and corneal defects, significantly delayed and aberrant hair follicle morphogenesis, and hyperproliferation in the epidermis and other stratified epithelia. Furthermore, K5.Smad7 mice developed severe thymic atrophy and massive thymocyte death, suggesting that Smad signaling in thymic epithelia is essential for thymocyte survival. Interestingly, in addition to a reduction in Smad phosphorylation, the protein levels of the receptors for TGFbeta, activin and bone morphogenetic protein were significantly decreased in the affected tissues of K5.Smad7 mice. Our study provides evidence that Smad7 is a potent in vivo inhibitor for signal transduction of the TGFbeta superfamily during development and maintenance of homeostasis of multiple epithelial tissues.