Engineered mesenchymal stem cells with enhanced tropism and paracrine secretion of cytokines and growth factors to treat traumatic brain injury

Traumatic brain injury (TBI) is the leading cause of death and disability worldwide. Mesenchymal stem cells (MSCs) are promising for the treatment of various diseases and injuries. Many strategies have been applied to attract MSCs to injury site after systemic infusion. In this study, we evidenced that the CXC chemokine receptor 4 (CXCR4)-SDF1α (stromal cell-derived factor 1α) axis in engineered MSCs serves not only to attract MSC migration to TBI but also to activate Akt kinase signaling pathway in MSCs to promote paracrine secretion of cytokines and growth factors. This leads to enhanced vasculogenesis and neuroprotection at the boundary of TBI for improved blood supply, recovery of axon connectivity, and behavioral ability and results in positive feedback loop to enhance additional MSC tropism to injury. These findings indicate a new aspect of SDF1α in mediating CXCR4 engineered MSCs for brain trauma homing and recovery. This potential mechanism may be applicable to other injuries, where CXCR4-SDF1α interaction is highly associated.

The head and neck cancer cell oncogenome: a platform for the development of precision molecular therapies

The recent elucidation of the genomic landscape of head and neck squamous cell carcinoma (HNSCC) has provided a unique opportunity to develop selective cancer treatment options. These efforts will require the establishment of relevant HNSCC models for preclinical testing. Here, we performed full exome and transcriptome sequencing of a large panel of HNSCC-derived cells from different anatomical locations and human papillomavirus (HPV) infection status. These cells exhibit typical mutations in TP53, FAT1, CDK2NA, CASP8, and NOTCH1, and copy number variations (CNVs) and mutations in PIK3CA, HRAS, and PTEN that reflect the widespread activation of the PI3K-mTOR pathway. SMAD4 alterations were observed that may explain the decreased tumor suppressive effect of TGF-β in HNSCC. Surprisingly, we identified HPV⁺ HNSCC cells harboring TP53 mutations, and documented aberrant TP53 expression in a subset of HPV⁺ HNSCC cases. This analysis also revealed that most HNSCC cells harbor multiple mutations and CNVs in epigenetic modifiers (e.g., EP300, CREBP, MLL1, MLL2, MLL3, KDM6A, and KDM6B) that may contribute to HNSCC initiation and progression. These genetically-defined experimental HNSCC cellular systems, together with the identification of novel actionable molecular targets, may now facilitate the pre-clinical evaluation of emerging therapeutic agents in tumors exhibiting each precise genomic alteration.

Abstract 3249: Recurrent 3p21 deletion in head and neck squamous cell carcinoma identifies SEMA3F as an anti-lymphangiogenic metastasis suppressor gene

Head and neck squamous cell carcinomas (HNSCC) often metastasize to locoregional lymph nodes, and lymph node involvement represents one of the most important prognostic factors of poor clinical outcome. HNSCC are remarkably lymphangiogenic and represent a clear example of a cancer that utilizes the lymphatic vasculature for malignant dissemination; however, the molecular mechanisms underlying lymphangiogenesis in HNSCC is still poorly understood. Of interest, we found that an axon guidance molecule, Semaphorin 3F (SEMA3F), is among the top 1% underexpressed genes in HNSCC, and that genomic loss of SEMA3F correlates with increased metastasis and decreased survival. SEMA3F acts on its co-receptors, plexins and neuropilins, among which neuropilin-2 (NRP2) is highly expressed in lymphatic endothelial cells (LECs) but not in oral epithelium and most HNSCCs. We show that recombinant SEMA3F promotes LEC collapse and potently inhibits lymphangiogenesis in vivo. By reconstituting all possible plexin and neuropilin combinations, we found that SEMA3F acts through multiple receptors, but predominantly requires NRP2 to signal in LECs. Using orthotopic HNSCC metastasis mouse models, we provide direct evidence that SEMA3F re-expression diminishes lymphangiogenesis and lymph node metastasis. Furthermore, analysis of a large tissue collection revealed that SEMA3F is progressively lost during HNSCC progression, concomitant with increased tumor lymphangiogenesis. SEMA3F is localized to 3p21, an early and frequently deleted locus in HNSCC and many other prevalent human malignancies. Thus, SEMA3F may represent an antilymphangiogenic metastasis suppressor gene widely lost during cancer progression, hence serving as a prognostic biomarker and an attractive target for therapeutic intervention to halt metastasis.

Citation Format: Colleen L. Doçi, Constantinos M. Mikelis, Michail S. Lionakis, Alfredo A. Molinolo, J Silvio Gutkind. Recurrent 3p21 deletion in head and neck squamous cell carcinoma identifies SEMA3F as an anti-lymphangiogenic metastasis suppressor gene. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 3249. doi:10.1158/1538-7445.AM2015-3249

Abstract 2059: Novel roles for GNA13 and RHOA as tumor suppressor genes

G-protein coupled receptors (GPCRs) and G-proteins are critical signal transduction molecules that regulate cell survival, proliferation, motility and differentiation. However, mutations and disruptions in the expression or function of these molecules have been linked to growth, progression and metastasis of various cancers. Recently, major efforts in the area of genome-wide sequencing of tumors have unveiled numerous previously uncharacterized mutations in G-proteins and GPCRs, which could have significant implications to cancer initiation and progression. In particular, mutations in the gene encoding the G-protein G13 (GNA13) and/or its downstream effector, RhoA, have been identified in B cell lymphomas (particularly Burkitt's lymphoma and Diffuse Large B cell Lymphoma), T cell lymphomas, and Head and Neck Squamous Cell Carcinomas (HNSCCs). Our analyses indicate that these mutations are highly statistically significant over background cancer gene mutation rate, and mutations in GNA13 alone occur in ∼10-15% of patients with Burkitt's lymphoma and Diffuse Large B cell Lymphoma. Surprisingly, although G13 and RhoA have previously been linked to cellular transformation and metastatic potential of epithelial cancers, our data suggests that the mutations in GNA13 and/or RHOA in these B cell lymphomas and HNSCC are inhibitory in nature. Furthermore, our results indicate a tumor suppressive function for wild-type GNA13 and RHOA in in vivo cancer models. Overall, our data suggest a novel function tumor suppressive function for the G13/RhoA axis in multiple human malignancies.

Citation Format: Morgan O'hayre, Asuka Inoue, Katiuchia Sales, Irina Kufareva, Juan Luis Callejas Valera, Fukun Guo, Constantinos Mikelis, Giovanni DiPasquale, Kira Finkel, Junken Aoki, Yi Zheng, Thomas H. Bugge, J. Silvio Gutkind. Novel roles for GNA13 and RHOA as tumor suppressor genes. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 2059. doi:10.1158/1538-7445.AM2015-2059

Polymeric Nanovehicle Regulated Spatiotemporal Real-Time Imaging of the Differentiation Dynamics of Transplanted Neural Stem Cells after Traumatic Brain Injury

Recent advances in neural stem cell (NSC) transplantation have led to an inspiring progress in alleviating central nervous system (CNS) damages and restoring brain functions from diseases or injuries. One challenge of NSC transplantation is directed differentiation of transplanted NSCs into desired neuronal subtypes, such as neurons, to compensate the adverse impact of brain injury; another challenge lies in the lack of tools to noninvasively monitor the dynamics of NSC differentiation after transplantation in vivo. In this study, we developed a polymer nanovehicle for morphogen sustained release to overcome the drawbacks of conventional methods to realize the long-term directed NSC differentiation in vivo. Moreover, we constructed a bicistronic vector with a unique neuron specific gene tubb3 promoter to drive reporter gene expression for real-time imaging of NSC differentiation and migration. The developed uniform nanovehicle showed efficient NSC uptake and achieved a controlled release of morphogen in cytosol to consistently stimulate NSC differentiation into neurons at a sustainably effective concentration. The spatiotemporal imaging results showed a multiplexed migration, proliferation, differentiation, and apoptosis orchestra of transplanted NSCs regulated by nanovehicles in TBI mice. The imaging results also uncovered the peak time of NSC differentiation in vivo. Although we observed only a handful of NSCs ultimately migrated to the TBI area and differentiated into neurons, those neurons were functional, ameliorating the detrimental impact of TBI. The imaging findings enabled by the nanovehicle and the neuron specific bicistronic vector provide additional understanding of the in vivo behaviors of transplanted NSCs in neuronal regenerative medicine.

Heterotrimeric G-protein alpha-12 (Gα12) subunit promotes oral cancer metastasis

Oral squamous cell carcinoma (OSCC) has a propensity to spread to the cervical lymph nodes (LN). The presence of cervical LN metastases severely impacts patient survival, whereby the two-year survival for oral cancer patients with involved LN is ~30% compared to over 80% in patients with non-involved LN. Elucidation of key molecular mechanisms underlying OSCC metastasis may afford an opportunity to target specific genes, to prevent the spread of OSCC and to improve patient survival. In this study, we demonstrated that expression of the heterotrimeric G-protein alpha-12 (Gα12) is highly up-regulated in primary tumors and LN of OSCC patients, as assessed by quantitative polymerase chain reaction (qPCR) and immunohistochemistry (IHC). We also found that exogenous expression of the constitutively activated-form of Gα12 promoted cell migration and invasion in OSCC cell lines. Correspondingly, inhibition of Gα12 expression by shRNA consistently inhibited OSCC cell migration and invasion in vitro. Further, the inhibition of G12 signaling by regulator of G-protein signaling (RGS) inhibited Gα12-mediated RhoA activation, which in turn resulted in reduced LN metastases in a tongue-orthotopic xenograft mouse model of oral cancer. This study provides a rationale for future development and evaluation of drug candidates targeting Gα12-related pathways for metastasis prevention.

Inactivation of a Gα(s)-PKA tumour suppressor pathway in skin stem cells initiates basal-cell carcinogenesis

Genomic alterations in GNAS, the gene coding for the Gαs heterotrimeric G-protein, are associated with a large number human of diseases. Here, we explored the role of Gαs on stem cell fate decisions by using the mouse epidermis as a model system. Conditional epidermal deletion of Gnas or repression of PKA signaling caused a remarkable expansion of the stem cell compartment, resulting in rapid basal cell carcinoma formation. In contrast, inducible expression of active Gαs in the epidermis caused hair follicle stem cell exhaustion and hair loss. Mechanistically, we found that Gαs-PKA disruption promotes the cell autonomous Sonic Hedgehog pathway stimulation and Hippo signaling inhibition, resulting in the non-canonical activation of GLI and YAP1. Our study highlights an important tumor suppressive function of Gαs-PKA, limiting the proliferation of epithelial stem cells and maintaining proper hair follicle homeostasis. These findings can have broad implications in multiple pathophysiological conditions, including cancer.

Genetic Identification of SEMA3F as an Antilymphangiogenic Metastasis Suppressor Gene in Head and Neck Squamous Carcinoma

Head and neck squamous cell carcinomas (HNSCC) often metastasize to locoregional lymph nodes, and lymph node involvement represents one of the most important prognostic factors of poor clinical outcome. HNSCCs are remarkably lymphangiogenic and represent a clear example of a cancer that utilizes the lymphatic vasculature for malignant dissemination; however, the molecular mechanisms underlying lymphangiogenesis in HNSCC is still poorly understood. Of interest, we found that an axon guidance molecule, Semaphorin 3F (SEMA3F), is among the top 1% underexpressed genes in HNSCC, and that genomic loss of SEMA3F correlates with increased metastasis and decreased survival. SEMA3F acts on its coreceptors, plexins and neuropilins, among which neuropilin-2 (NRP2) is highly expressed in lymphatic endothelial cells (LEC) but not in oral epithelium and most HNSCCs. We show that recombinant SEMA3F promotes LEC collapse and potently inhibits lymphangiogenesis in vivo. By reconstituting all possible plexin and neuropilin combinations, we found that SEMA3F acts through multiple receptors, but predominantly requires NRP2 to signal in LECs. Using orthotopic HNSCC metastasis mouse models, we provide direct evidence that SEMA3F re-expression diminishes lymphangiogenesis and lymph node metastasis. Furthermore, analysis of a large tissue collection revealed that SEMA3F is progressively lost during HNSCC progression, concomitant with increased tumor lymphangiogenesis. SEMA3F is localized to 3p21, an early and frequently deleted locus in HNSCC and many other prevalent human malignancies. Thus, SEMA3F may represent an antilymphangiogenic metastasis suppressor gene widely lost during cancer progression, hence serving as a prognostic biomarker and an attractive target for therapeutic intervention to halt metastasis.

RhoA and ROCK mediate histamine-induced vascular leakage and anaphylactic shock

Histamine-induced vascular leakage is an integral component of many highly prevalent human diseases, including allergies, asthma, and anaphylaxis. Yet, how histamine induces the disruption of the endothelial barrier is not well defined. By using genetically modified animal models, pharmacologic inhibitors, and a synthetic biology approach, here we show that the small GTPase RhoA mediates histamine-induced vascular leakage. Histamine causes the rapid formation of focal adherens junctions, disrupting the endothelial barrier by acting on H1R Gα_q-coupled receptors, which is blunted in endothelial Gα_q/11 KO mice. Interfering with RhoA and ROCK function abolishes endothelial permeability, while phospholipase Cβ plays a limited role. Moreover, endothelial-specific RhoA gene deletion prevents vascular leakage and passive cutaneous anaphylaxis in vivo, and ROCK inhibitors protect from lethal systemic anaphylaxis. This study supports a key role for the RhoA signaling circuitry in vascular permeability, thereby identifying novel pharmacological targets for many human diseases characterized by aberrant vascular leakage.

SDF-1/CXCL12 induces directional cell migration and spontaneous metastasis via a CXCR4/Gαi/mTORC1 axis

Multiple human malignancies rely on C-X-C motif chemokine receptor type 4 (CXCR4) and its ligand, SDF-1/CXCL12 (stroma cell-derived factor 1/C-X-C motif chemokine 12), to metastasize. CXCR4 inhibitors promote the mobilization of bone marrow stem cells, limiting their clinical application for metastasis prevention. We investigated the CXCR4-initiated signaling circuitry to identify new potential therapeutic targets. We used HeLa human cancer cells expressing high levels of CXCR4 endogenously. We found that CXCL12 promotes their migration in Boyden chamber assays and single cell tracking. CXCL12 activated mTOR (mechanistic target of rapamycin) potently in a pertussis-sensitive fashion. Inhibition of mTOR complex 1 (mTORC1) by rapamycin [drug concentration causing 50% inhibition (IC50) = 5 nM] and mTORC1/mTORC2 by Torin2 (IC50 = 6 nM), or by knocking down key mTORC1/2 components, Raptor and Rictor, respectively, decreased directional cell migration toward CXCL12. We developed a CXCR4-mediated spontaneous metastasis model by implanting HeLa cells in the tongue of SCID-NOD mice, in which 80% of the animals develop lymph node metastasis. It is surprising that mTORC1 disruption by Raptor knockdown was sufficient to reduce tumor growth by 60% and spontaneous metastasis by 72%, which were nearly abolished by rapamycin. In contrast, disrupting mTORC2 had no effect in tumor growth or metastasis compared with control short hairpin RNAs. These data suggest that mTORC1 may represent a suitable therapeutic target in human malignancies using CXCR4 for their metastatic spread. .

Prevention of tumor growth driven by PIK3CA and HPV oncogenes by targeting mTOR signaling with metformin in oral squamous carcinomas expressing OCT3

Most squamous cell carcinomas of the head and neck (HNSCC) exhibit a persistent activation of the PI3K-mTOR signaling pathway. We have recently shown that metformin, an oral antidiabetic drug that is also used to treat lipodystrophy in HIV-infected (HIV(+)) individuals, diminishes mTOR activity and prevents the progression of chemically induced experimental HNSCC premalignant lesions. Here, we explored the preclinical activity of metformin in HNSCCs harboring PIK3CA mutations and HPV oncogenes, both representing frequent HNSCC alterations, aimed at developing effective targeted preventive strategies. The biochemical and biologic effects of metformin were evaluated in representative HNSCC cells expressing mutated PIK3CA or HPV oncogenes (HPV(+)). The oral delivery of metformin was optimized to achieve clinical relevant blood levels. Molecular determinants of metformin sensitivity were also investigated, and their expression levels were examined in a large collection of HNSCC cases. We found that metformin inhibits mTOR signaling and tumor growth in HNSCC cells expressing mutated PIK3CA and HPV oncogenes, and that these activities require the expression of organic cation transporter 3 (OCT3/SLC22A3), a metformin uptake transporter. Coexpression of OCT3 and the mTOR pathway activation marker pS6 were observed in most HNSCC cases, including those arising in HIV(+) patients. Activation of the PI3K-mTOR pathway is a widespread event in HNSCC, including HPV(-) and HPV(+) lesions arising in HIV(+) patients, all of which coexpress OCT3. These observations may provide a rationale for the clinical evaluation of metformin to halt HNSCC development from precancerous lesions, including in HIV(+) individuals at risk of developing HPV(-) associated cancers.

Fluorescent, bioactive protein nanoparticles (prodots) for rapid, improved cellular uptake

A simple and effective method for synthesizing highly fluorescent, protein-based nanoparticles (Prodots) and their facile uptake into the cytoplasm of cells is described here. Prodots made from bovine serum albumin (nBSA), glucose oxidase (nGO), horseradish peroxidase (nHRP), catalase (nCatalase), and lipase (nLipase) were found to be 15-50 nm wide and have been characterized by gel electrophoresis, transmission electron microscopy (TEM), circular dichroism (CD), fluorescence spectroscopy, dynamic light scattering (DLS), and optical microscopic methods. Data showed that the secondary structure of the protein in Prodots is retained to a significant extent and specific activities of nGO, nHRP, nCatalase, and nLipase were 80%, 70%, 65%, and 50% of their respective unmodified enzyme activities. Calorimetric studies indicated that the denaturation temperatures of nGO and nBSA increased while those of other Prodots remained nearly unchanged, and accelerated storage half-lives of Prodots at 60 °C increased by 4- to 8-fold. Exposure of nGO and nBSA+ nGO to cells indicated rapid uptake within 1-3 h, accompanied by significant blebbing of the plasma membrane, but no uptake has been noted in the absence of nGO. The presence of nGO/glucose in the media facilitated the uptake, and hydrogen peroxide induced membrane permeability could be responsible for this rapid uptake of Prodots. In control studies, FITC alone did not enter the cell, BSA-FITC was not internalized even in the presence of nGO, and there has been no uptake of nBSA-FITC in the absence of nGO. These are the very first examples of very rapid cellular uptake of fluorescent nanoparticles into cells, particularly nanoparticles made from pure proteins. The current approach is a simple and efficient method for the preparation of bioactive, fluorescent protein nanoparticles of controllable size for cellular imaging, and cell uptake is under the control of two separate chemical triggers.

A systems genetics approach identifies CXCL14, ITGAX, and LPCAT2 as novel aggressive prostate cancer susceptibility genes

Although prostate cancer typically runs an indolent course, a subset of men develop aggressive, fatal forms of this disease. We hypothesize that germline variation modulates susceptibility to aggressive prostate cancer. The goal of this work is to identify susceptibility genes using the C57BL/6-Tg(TRAMP)8247Ng/J (TRAMP) mouse model of neuroendocrine prostate cancer. Quantitative trait locus (QTL) mapping was performed in transgene-positive (TRAMPxNOD/ShiLtJ) F2 intercross males (n = 228), which facilitated identification of 11 loci associated with aggressive disease development. Microarray data derived from 126 (TRAMPxNOD/ShiLtJ) F2 primary tumors were used to prioritize candidate genes within QTLs, with candidate genes deemed as being high priority when possessing both high levels of expression-trait correlation and a proximal expression QTL. This process enabled the identification of 35 aggressive prostate tumorigenesis candidate genes. The role of these genes in aggressive forms of human prostate cancer was investigated using two concurrent approaches. First, logistic regression analysis in two human prostate gene expression datasets revealed that expression levels of five genes (CXCL14, ITGAX, LPCAT2, RNASEH2A, and ZNF322) were positively correlated with aggressive prostate cancer and two genes (CCL19 and HIST1H1A) were protective for aggressive prostate cancer. Higher than average levels of expression of the five genes that were positively correlated with aggressive disease were consistently associated with patient outcome in both human prostate cancer tumor gene expression datasets. Second, three of these five genes (CXCL14, ITGAX, and LPCAT2) harbored polymorphisms associated with aggressive disease development in a human GWAS cohort consisting of 1,172 prostate cancer patients. This study is the first example of using a systems genetics approach to successfully identify novel susceptibility genes for aggressive prostate cancer. Such approaches will facilitate the identification of novel germline factors driving aggressive disease susceptibility and allow for new insights into these deadly forms of prostate cancer.

Prostate cancer is a remarkably common disease, and in 2014 it is estimated that it will account for 27% of new cancer cases in men in the US. However, less than 13% those diagnosed will succumb to prostate cancer, with most men dying from unrelated causes. The tests used to identify men at risk of fatal prostate cancer are inaccurate, which leads to overtreatment, unnecessary patient suffering, and represents a significant public health burden. Many studies have shown that hereditary genetic variation significantly alters susceptibility to fatal prostate cancer, although the identities of genes responsible for this are mostly unknown. Here, we used a mouse model of prostate cancer to identify such genes. We introduced hereditary genetic variation into this mouse model through breeding, and used a genetic mapping technique to identify 35 genes associated with aggressive disease. The levels of three of these genes were consistently abnormal in human prostate cancers with a more aggressive disease course. Additionally, hereditary differences in these same three genes were associated with markers of fatal prostate cancer in men. This approach has given us unique insights into how hereditary variation influences fatal forms of prostate cancer.

Abstract 4202: Deciphering the effects of GNA13 mutations in B-cell lymphomas

G-proteins and their cognate G-protein coupled receptors (GPCRs) are critical signal transduction molecules that regulate cell survival, proliferation, motility and differentiation. The aberrant expression or function of these molecules has been linked to growth, progression and metastasis of various cancers. Recent genome-wide sequencing efforts have unveiled numerous previously uncharacterized mutations in G-proteins and GPCRs, which could have significant implications to cancer initiation and progression. Of interest, recent analyses have demonstrated that there are frequent mutations in GNA13 in Burkitt's lymphoma and Diffuse Large B cell lymphomas (DLBCL) that are highly statistically significant over background cancer gene mutation rate, and occur in ∼10-13% of patients with these lymphomas. Mutations in the downstream target of G13, RhoA, are also present in several Burkitt's lymphoma tumors, highlighting that mutations in this G13-RhoA pathway may be key to the oncogenic potential of these B cell lymphomas. Although G13 activity has previously been linked cellular transformation and metastatic potential of epithelial cancers, our data suggests that the mutations in GNA13 in these B cell lymphomas are mostly inhibitory in nature. Thus, we have functionally characterized several mutations in GNA13 and RHOA found in Burkitt's lymphoma and DLBCL.

Citation Format: Morgan L. O'Hayre, Irina Kufareva, Jose P. Vaqué, Miguel A. Piris, J. Silvio Gutkind. Deciphering the effects of GNA13 mutations in B-cell lymphomas. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 4202. doi:10.1158/1538-7445.AM2014-4202

Abstract 1260: CP-31398 prevents the progression of oral squamous cell carcinomas from carcinogen-induced premalignant lesions

Head and neck squamous cell carcinoma (HNSCC) is an aggressive disease with a poor prognosis if not detected and treated at the early stages. P53 inactivation represents one of the most frequent molecular events in HNSCC. Here we studied a p53-reactivating small molecule, CP-31398, to prevent progression of premalignant oral squamous lesions to malignant HNSCC. We treated a panel of HNSCC cell lines with CP-31398 which resulted in a dose-dependent inhibition of cell proliferation as assessed by [3H]-Thymidine incorporation and cell cycle analysis, including induction of apoptotic cell death. These alterations were associated with an increased expression of the cell cycle inhibitor CDKN1A (p21WAF1) upon CP-31398 treatment. Interestingly, p53 function restoration by CP-31398 caused a marked decrease in activity of the PI3K/Akt/mTOR pathway, which is most frequently deregulated in HNSCC, and whose inhibition results in decreased tumorigenicity in multiple preclinical models systems. Indeed, CP-31398 treatment increased the expression of Sestrin 1/2 and REDD1; three well established p53-regulated genes that exert inhibitory activity over mTOR. Next, we evaluated the chemopreventive efficacy of CP-31398 in a 4-Nitroquinoline oxide (4NQO)-induced HNSCC mouse model that we have recently developed, which closely resembles development and progression of human HNSCC, including the induction of tp53 mutations as revealed by DNA sequencing. C57BL/6 mice were given 4NQO in the drinking water for a period of 14 weeks, during which all the animals developed an array of potential oral premalignant lesions. Upon 4NQO removal, mice were randomized into two groups receiving a control diet or a diet containing 250 ppm of CP-31398 for 8 weeks, in which the development and progression of tongue lesions were documented. At the conclusion of the study, 22 weeks, all mice were euthanized and subjected to full autopsies and histopathological evaluations. While 100% of the animals in the control group developed SCCs at the end of the study, there was a 70% reduction in the number of SCCs in the CP-31398- treated group. These findings suggest that the early, widespread alterations, of p53 during HNSCC progression can make this tumor type particularly vulnerable to intervention strategies, restoring p53 function by direct acting, p53 rescue agents. Hence, a large number of at risk patients exhibiting potential oral premalignant lesions harboring p53 mutations could benefit from the treatment with p53-reactivating small molecules such as CP-31398, which can also restrict the uncontrolled activation of the mTOR pathway. Overall, we present evidence of a novel chemopreventive intervention approach that exploits the emerging crosstalk between p53 and the mTOR pathways, including pharmacologic activation of mutant p53, individually and together with mTOR inhibitors, halting HNSCC progression.

Citation Format: Lynn A. Vitale-Cross, Daniel Martin, Chinthalapally V. Rao, Levy Kopelovich, J. Silvio Gutkind. CP-31398 prevents the progression of oral squamous cell carcinomas from carcinogen-induced premalignant lesions. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 1260. doi:10.1158/1538-7445.AM2014-1260

Abstract 4050: A central role for mTORC1 in CXCR4-mediated directional migration and metastasis

Tumor cells can co-opt the promigratory activity of chemokines and their cognate G protein-coupled receptors to disseminate to regional lymph nodes and distant organs. Indeed, the migration to SDF-1 of tumor cells expressing its receptor, CXCR4, is implicated in lymphatic and organ-specific metastasis in multiple human malignancies. However, the critical role of CXCR4 in bone marrow stem cell retention has hampered the development of CXCR4 inhibitors for metastasis prevention. Therefore the study of CXCR4 downstream signaling circuitry may provide new opportunities for the treatment of many human malignancies that depend on CXCR4 for their metastatic spread. The PI3K/mTOR pathway represents a major player in normal and aberrant cell growth. Consistently, mTOR inhibitors targeting its complex 1 (mTORC1) alone or mTORC1/mTORC2 have already shown promising therapeutic responses in many tumor types. Our data show that mTOR is activated upon SDF-1 stimulation of CXCR4 on epithelial-derived cancer cells, and that the disruption of mTORC1 or mTORC2 abrogates CXCR4-mediated directional migration. To study the CXCR4/mTOR axis in vivo we developed a simple and robust model for CXCR4-mediated spontaneous metastasis. Surprisingly, disruption of mTORC1 alone was sufficient to decrease tumor cell proliferation, angiogenesis, lymphangiogenesis, and CXCR4-mediated metastasis, whereas mTORC2 impairment had no effect on tumor dissemination or growth in vivo. Taken together, our data suggest that mTORC1 blockade could inhibit the migration of CXCR4 expressing cancer cells to their secondary sites, while disrupting the establishment of a permissive tumor microenvironment thereby halting the spread of highly aggressive tumors that require CXCR4 to metastasize.

Citation Format: Patricia Dillenburg-Pilla, Vyomesh Patel, Constantinos M. Mikelis, Carlos Rodrigo Zarate-Blades, Panomwat Amornphimoltham, Zhiyong Wang, Daniel Martin, Kantima Leelahavanichkul, Colleen L. Doçi, Robert T. Dorsam, Andrius Masedunskas, Nijiro Nohata , Roberto Weigert, Alfredo A. Molinolo, J. Silvio Gutkind . A central role for mTORC1 in CXCR4-mediated directional migration and metastasis. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 4050. doi:10.1158/1538-7445.AM2014-4050

Melanoma cell lysate induces CCR7 expression and in vivo migration to draining lymph nodes of therapeutic human dendritic cells

We have previously reported a novel method for the production of tumour-antigen-presenting cells (referred to as TAPCells) that are currently being used in cancer therapy, using an allogeneic melanoma-derived cell lysate (referred to as TRIMEL) as an antigen provider and activation factor. It was recently demonstrated that TAPCell-based immunotherapy induces T-cell-mediated immune responses resulting in improved long-term survival of stage IV melanoma patients. Clinically, dendritic cell (DC) migration from injected sites to lymph nodes is an important requirement for an effective anti-tumour immunization. This mobilization of DCs is mainly driven by the C-C chemokine receptor type 7 (CCR7), which is up-regulated on mature DCs. Using flow cytometry and immunohistochemistry, we investigated if TRIMEL was capable of inducing the expression of the CCR7 on TAPCells and enhancing their migration in vitro, as well as their in vivo relocation to lymph nodes in an ectopic xenograft animal model. Our results confirmed that TRIMEL induces a phenotypic maturation and increases the expression of surface CCR7 on melanoma patient-derived DCs, and also on the monocytic/macrophage cell line THP-1. Moreover, in vitro assays showed that TRIMEL-stimulated DCs and THP-1 cells were capable of migrating specifically in the presence of the CCR7 ligand CCL19. Finally, we demonstrated that TAPCells could migrate in vivo from the injection site into the draining lymph nodes. This work contributes to an increased understanding of the biology of DCs produced ex vivo allowing the design of new strategies for effective DC-based vaccines for treating aggressive melanomas.

Insights into β2-adrenergic receptor binding from structures of the N-terminal lobe of ARRDC3

ARRDC3 is one of six known human α-arrestins, and has been implicated in the downregulation of the β2-adrenergic receptor (β2AR). ARRDC3 consists of a two-lobed arrestin fold and a C-terminal tail containing two PPYX motifs. In the current model for receptor downregulation by ARRDC3, the arrestin fold portion is thought to bind the receptor, while the PPXY motifs recruit ubiquitin ligases of the NEDD4 family. Here we report the crystal structures of the N-terminal lobe of human ARRDC3 in two conformations, at 1.73 and 2.8 Å resolution, respectively. The structures reveal a large electropositive region that is capable of binding phosphate ions of crystallization. Residues within the basic patch were shown to be important for binding to β2AR, similar to the situation with β-arrestins. This highlights potential parallels in receptor recognition between α- and β-arrestins.

Kaposi sarcoma-associated herpesvirus promotes tumorigenesis by modulating the Hippo pathway

Kaposi sarcoma-associated herpesvirus (KSHV) is an oncogenic virus and the culprit behind the human disease Kaposi sarcoma (KS), an AIDS-defining malignancy. KSHV encodes a viral G-protein-coupled receptor (vGPCR) critical for the initiation and progression of KS. In this study, we identified that YAP/TAZ, two homologous oncoproteins inhibited by the Hippo tumor suppressor pathway, are activated in KSHV-infected cells in vitro, KS-like mouse tumors and clinical human KS specimens. The KSHV-encoded vGPCR acts through Gq/11 and G12/13 to inhibit the Hippo pathway kinases Lats1/2, promoting the activation of YAP/TAZ. Furthermore, depletion of YAP/TAZ blocks vGPCR-induced cell proliferation and tumorigenesis in a xenograft mouse model. The vGPCR-transformed cells are sensitive to pharmacologic inhibition of YAP. Our study establishes a pivotal role of the Hippo pathway in mediating the oncogenic activity of KSHV and development of KS, and also suggests a potential of using YAP inhibitors for KS intervention.

Biology of advanced uveal melanoma and next steps for clinical therapeutics

Uveal melanoma is the most common intraocular malignancy although it is a rare subset of all melanomas. Uveal melanoma has distinct biology relative to cutaneous melanoma, with widely divergent patient outcomes. Patients diagnosed with a primary uveal melanoma can be stratified for risk of metastasis by cytogenetics or gene expression profiling, with approximately half of patients developing metastatic disease, predominately hepatic in location, over a 15-yr period. Historically, no systemic therapy has been associated with a clear clinical benefit for patients with advanced disease, and median survival remains poor. Here, as a joint effort between the Melanoma Research Foundation's ocular melanoma initiative, CURE OM and the National Cancer Institute, the current understanding of the molecular and immunobiology of uveal melanoma is reviewed, and on-going laboratory research into the disease is highlighted. Finally, recent investigations relevant to clinical management via targeted and immunotherapies are reviewed, and next steps in the development of clinical therapeutics are discussed.

mTOR co-targeting in cetuximab resistance in head and neck cancers harboring PIK3CA and RAS mutations

Background

Cetuximab, a monoclonal blocking antibody against the epidermal growth factor receptor EGFR, has been approved for the treatment of squamous cell carcinomas of the head and neck (HNSCC). However, only few patients display long-term responses, prompting the search for cetuximab resistance mechanisms and new therapeutic options enhancing cetuximab effectiveness.

Methods

Cetuximab-sensitive HNSCC cells were retro-engineered to express PIK3CA and RAS oncogenes. These cells and HNSCC cells harboring endogenous PIK3CA and RAS oncogenes were xenografted into mice (n = 10 per group) and studied for their biochemical, antitumor, antiangiogenic, and antilymphangiogenic responses to cetuximab and mTOR targeting agents. All P values are two-sided.

Results

Cetuximab treatment of PIK3CA- and RAS-expressing HNSCC xenografts promoted an initial antitumor response, but all tumors relapsed within few weeks. In these tumors, cetuximab did not decrease the activity of mTOR, a downstream signaling target of EGFR, PIK3CA, and RAS. The combined administration of cetuximab and mTOR inhibitors exerted a remarkably increased antitumor activity, particularly in HNSCC cells that are resistant to cetuximab as a single agent. Indeed, cotargeting mTOR together with cetuximab caused a rapid tumor collapse of both PIK3CA- and RAS-expressing HNSCC xenografts (P < .001), concomitant with reduced proliferation (P < .001) and lymphangiogenesis (P < .001).

Conclusion

The presence of PIK3CA and RAS mutations and other alterations affecting the mTOR pathway activity in HNSCC could be exploited to predict the potential resistance to cetuximab, and to select the patients that may benefit the most from the concomitant administration of cetuximab and PI3K and/or mTOR inhibitors as a precision molecular therapeutic option for HNSCC patients.

Dermatomyositis paraneoplastic syndrome before symptomatic tonsillar squamous cell carcinoma: a case report

BACKGROUND

Paraneoplastic syndromes are systemic or organ-related functional tumor-associated changes that arise distant to the tumor.

METHODS AND RESULTS

We present a rare case of a 63-year-old man with dermatomyositis as a paraneoplastic syndrome developing more than a year before clinical manifestations of tonsillar squamous cell carcinoma (SCC). He subsequently developed stage T1N2bM0 IVA tonsillar SCC. He was treated on a research protocol with 3 weeks of neoadjuvant rapamycin therapy before right transoral lateral pharyngectomy and modified radical neck dissection with preservation of CN XI. His symptoms of dermatomyositis subsequently improved and he was weaned off immunosuppressive therapy.

CONCLUSION

To our knowledge, this is the first report of dermatomyositis as a paraneoplastic syndrome of tonsillar SCC in North America. We suggest that clinicians should monitor for signs of persistent or recurrent dermatomyositis symptoms as this may herald development or a return of the underlying malignancy.

Hippo-independent activation of YAP by the GNAQ uveal melanoma oncogene through a trio-regulated rho GTPase signaling circuitry

Mutually exclusive activating mutations in the GNAQ and GNA11 oncogenes, encoding heterotrimeric Gαq family members, have been identified in ∼ 83% and ∼ 6% of uveal and skin melanomas, respectively. However, the molecular events underlying these GNAQ-driven malignancies are not yet defined, thus limiting the ability to develop cancer-targeted therapies. Here, we focused on the transcriptional coactivator YAP, a critical component of the Hippo signaling pathway that controls organ size. We found that Gαq stimulates YAP through a Trio-Rho/Rac signaling circuitry promoting actin polymerization, independently of phospholipase Cβ and the canonical Hippo pathway. Furthermore, we show that Gαq promotes the YAP-dependent growth of uveal melanoma cells, thereby identifying YAP as a suitable therapeutic target in uveal melanoma, a GNAQ/GNA11-initiated human malignancy.