In-Depth Endogenous Phosphopeptidomics of Serum with Zirconium(IV)-Grafted Mesoporous Silica Enrichment

Detection of endogenous peptides, especially those with modifications (such as phosphorylation) in biofluids, can serve as an indicator of intracellular pathophysiology. Although great progress has been made in phosphoproteomics in recent years, endogenous phosphopeptidomics has largely lagged behind. One main hurdle in endogenous phosphopeptidomics analysis is the coexistence of proteins and highly abundant nonmodified peptides in complex matrices. In this study, we developed an approach using zirconium(IV)-grafted mesoporous beads to enrich phosphopeptides, followed by analysis with a high resolution nanoRPLC-MS/MS system. The bifunctional material was first tested with digests of standard phosphoproteins and HeLa cell lysates, with excellent enrichment performance achieved. Given the size exclusion nature, the beads were directly applied for endogenous phosphopeptidomic analysis of serum samples from pancreatic ductal adenocarcinoma (PDAC) patients and controls. In total, 329 endogenous phosphopeptides (containing 113 high confidence sites) were identified across samples, by far the largest endogenous phosphopeptide data set cataloged to date. In addition, the method was readily applied for phosphoproteomics of the same set of samples, with 172 phosphopeptides identified and significant changes in dozens of phosphopeptides observed. Given the simplicity and robustness of the proposed method, we envision that it can be readily used for comprehensive phosphorylation studies of serum and other biofluid samples.

Design and Preparation of Novel Nitro-Oxide-Grafted Nanospheres with Enhanced Hydrogen Bonding Interaction for O-GlcNAc Analysis

As an essential modification, O-linked β-N-acetylglucosamine (O-GlcNAc) modulates the functions of many proteins. However, site-specific characterization of O-GlcNAcylated proteins remains challenging. Herein, an innovative material grafted with nitro-oxide (N→O) groups was designed for high affinity enrichment for O-GlcNAc peptides from native proteins. By testing with synthetic O-GlcNAc peptides and standard proteins, the synthesized material exhibited high affinity and selectivity. Based on the material prepared, we developed a workflow for site-specific analysis of O-GlcNAcylated proteins in complex samples. We performed O-GlcNAc proteomics with the PANC-1 cell line, a representative model for pancreatic ductal adenocarcinoma. In total 364 O-GlcNAc peptides from 267 proteins were identified from PANC-1 cells. Among them, 183 proteins were newly found to be O-GlcNAcylated in humans (with 197 O-GlcNAc sites newly reported). The materials and methods can be facilely applied for site-specific O-GlcNAc proteomics in other complex samples.

Abstract 2516: Loss of cadherin 11 in pancreatic cancer induces altered immune cell infiltration

Pancreatic ductal adenocarcinoma (PDAC) is one of the top five deadliest forms of cancer with very few treatment options. The 5-year survival rate for PDAC is 10% following diagnosis. Preclinical murine models have been developed that leverage key driver mutations and have significantly contributed to our understanding of PDAC. One such genetically engineered mouse model (GEMM) that has emerged as an important tool is the KPC mouse (LSL-KrasG12D/+;LSL-Trp53R172H/+; p48-Cre) that spontaneously develops pancreatic tumors at ~14-16 weeks of age. Cadherin-11 (Cdh11), a cell-to-cell adhesion molecule has been suggested to play a role in development of the desmoplastic stroma in PDAC, that leads to difficulties in drug accessibility and has been hypothesized to contribute to chemotherapeutic resistance and correlate with poor prognosis. However, the mechanisms by which Cdh11 deficiency in the stromal microenvironment of PDAC-bearing KPC mice influences tumor infiltrating immune cells, has yet to be fully understood. Single-cell RNA sequencing (scRNAseq) of the immune (CD45+) compartment of tumor bearing Cdh11 proficient (KPC/Cdh11+/+), tumor bearing Cdh11 deficient (KPC/Cdh11+/-), non-tumor bearing Cdh11 deficient (Cdh11+/-) and wildtype (Cdh11+/+) mice was performed. We observed a sharp decrease in the presence of myeloid/monocyte lineage cells (CD14+) in KPC/Cdh11+/- tumors and also an increase in T, B and plasma cells, compared to KPC/Cdh11+/+ tumors. Genes upregulated in infiltrating T- and NK cells specific to a Cdh11 deficient background include Cd8a, Nkg7, Maf. Additionally, genes found to be upregulated in B cell clusters in Cdh11 deficient mice include those related to B cell differentiation/activation such as Lgals1, Id2, Itgb1, Rgs1. The increase in B and T cell infiltration was specific to the Cdh11 deficient background, since both pancreata from KPC/Cdh11+/+and Cdh11+/- mice had elevated levels of infiltration. Immunohistochemical validation of these findings has confirmed these changes in tumor infiltrating immune cells. Additionally of note, an increase in antibody-producing plasma cells was observed specifically in a Cdh11 deficient background. Igkc, an immunoglobulin found to be enriched in plasma cells was highly expressed in this group of immune cells. We also observed that KPC/Cdh11+/-had significantly more Igkc expressing cells than KPC/Cdh11+/+. Future work is needed to clearly define the role of Cdh11 in modulating B, T and plasma cell behavior and subsequent contributions to PDAC outcome. This study received funding by LDRD 19-SI-003. This work was conducted under the auspices of the USDOE by LLNL (DE-AC52-07NA27344), LLNL-ABS-820889. This work was supported by AACR-AstraZeneca Fellowship in Immunooncology Research, grant 17-40-12-PERA; The Ruesch Center for the Cure of Gastrointestinal Cancers grant award; NIH R01 CA170653; and NIH Cancer Center Support Grant P30 CA051008.

Citation Format: Kelly A. Martin, Aimy Sebastian, Nicholas Hum, Ivana Peran, Stephen Byers, Elizabeth Wheeler, Matthew Coleman, Gabriela Loots. Loss of cadherin 11 in pancreatic cancer induces altered immune cell infiltration [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 2516.

Coupling suspension trapping-based sample preparation and data-independent acquisition mass spectrometry for sensitive exosomal proteomic analysis

It has been a challenge to analyze minute amounts of proteomic samples in a facile and robust manner. Herein, we developed a quantitative proteomics workflow by integrating suspension trapping (S-Trap)-based sample preparation and label-free data-independent acquisition (DIA) mass spectrometry and then applied it for the analysis of microgram and even nanogram amounts of exosome samples. S-Trap-based sample preparation outperformed the traditional in-solution digestion-based approach and the commonly used filter-aided sample preparation (FASP)-based approach with regard to the number of proteins and peptides identified. Moreover, S-Trap-based sample preparation coupled with DIA mass spectrometry also showed the highest reproducibility for protein quantification. In addition, this approach allowed for identification and quantification of exosome proteins with low starting amounts (down to 50 ~ 200 ng). Finally, the proposed method was successfully applied to label-free quantification of exosomal proteins extracted from MDA-MB-231 breast cancer cells and MCF-10A non-tumorigenic epithelial breast cells. Prospectively, we envision the integrated S-Trap sample preparation coupled with DIA quantification strategy as a promising alternative for highly efficient and sensitive analysis of trace amounts of proteomic samples (e.g., exosomal samples).

Abstract 2741: Loss of Cadherin-11 in PDAC induces altered immune cell infiltration and remodels stromal landscape

Pancreatic ductal adenocarcinoma (PDAC) is one of the most lethal forms of cancer with very few treatment options. Less than 10 percent of patients diagnosed with PDAC survive 5 years post diagnosis. Mutations in CDKN2A, SMAD4, KRAS and P53 have been well linked to the development of PDAC. Preclinical murine models have been developed that leverage key driver mutations and have significantly contributed to our understanding of PDAC. One such genetically engineered mouse model (GEMM) that has emerged as an important tool in PDAC investigations is the KPC mouse (LSL-KrasG12D/+LSL-Trp53R172H/+Pdx-1-Cre) that spontaneously develops pancreatic tumors at ~14-16 weeks of age. Cadherin-11 (Cdh11), a cell-to-cell adhesion molecule, is highly expressed in desmoplastic stroma, a characteristic of PDAC, that leads to difficulties in drug accessibility and has been hypothesized to contribute to chemotherapeutic resistance. However, the mechanisms by which Cdh11 deficiency in the stromal microenvironment of PDAC-bearing mice (KPC) influences therapeutic outcomes, has yet to be fully understood. Single-cell RNA sequencing (scRNAseq) of both the non-immune (CD45-) and immune (CD45+) cellular compartments of tumor bearing (KPC/Cdh11+/+), tumor bearing Cdh11 deficient (KPC/Cdh11+/-), non-tumor bearing Cdh11 deficient (Cdh11-/+) and wildtype (KP) were performed. We observed changes in the abundance and types of infiltrating immune cells (T-cells, B-cells, myeloid lineage cells) of KPC/Cdh11+/- tumors when compared to tumors harvested from KPC/Cdh11+/+ mice. KPC/Cdh11+/+ pancreata had significantly more myeloid cells while KPC/Cdh11+/- tumors favored an increase in the numbers of infiltrating B- and T- cells. Genes upregulated in infiltrating T-cells specific to KPC/Cdh11+/+ mice include Spp1, Ifi30, Apoe, Ifitm3, Fn1. The increase in B and T cell infiltration was specific to the Cdh11-/+ deficient background, since both pancreata from KPC/Cdh11+/- and Cdh11-/+ mice had elevated levels of infiltration, compared to the KPC group. We also observed a decrease in the number of antigen-presenting cancer associated fibroblasts (apCAFs) in Cdh11-/+ and KPC/Cdh11+/- pancreata, denoted by the lack of CD74+ fibroblasts. Further validation of these findings will help to define the role of Cdh11-/+ in modulating B and T-cell behavior in addition to providing insight into Cdh11-/+ as a therapeutic target for PDAC through altering the tumor microenvironment.

Citation Format: Kelly A. Martin, Aimy Sebastian, Nicholas Hum, Ivana Peran, Stephen Byers, Elizabeth K. Wheeler, Matthew A. Coleman, Gabriela Loots. Loss of Cadherin-11 in PDAC induces altered immune cell infiltration and remodels stromal landscape [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 2741.

Predicting new drug indications for prostate cancer: The integration of an in silico proteochemometric network pharmacology platform with patient-derived primary prostate cells

BACKGROUND

Drug repurposing enables the discovery of potential cancer treatments using publically available data from over 4000 published Food and Drug Administration approved and experimental drugs. However, the ability to effectively evaluate the drug's efficacy remains a challenge. Impediments to broad applicability include inaccuracies in many of the computational drug-target algorithms and a lack of clinically relevant biologic modeling systems to validate the computational data for subsequent translation.

METHODS

We have integrated our computational proteochemometric systems network pharmacology platform, DrugGenEx-Net, with primary, continuous cultures of conditionally reprogrammed (CR) normal and prostate cancer (PCa) cells derived from treatment-naive patients with primary PCa.

RESULTS

Using the transcriptomic data from two matched pairs of benign and tumor-derived CR cells, we constructed drug networks to describe the biological perturbation associated with each prostate cell subtype at multiple levels of biological action. We prioritized the drugs by analyzing these networks for statistical coincidence with the drug action networks originating from known and predicted drug-protein targets. Prioritized drugs shared between the two patients' PCa cells included carfilzomib (CFZ), bortezomib (BTZ), sulforaphane, and phenethyl isothiocyanate. The effects of these compounds were then tested in the CR cells, in vitro. We observed that the IC50 values of the normal PCa CR cells for CFZ and BTZ were higher than their matched tumor CR cells. Transcriptomic analysis of CFZ-treated CR cells revealed that genes involved in cell proliferation, proteases, and downstream targets of serine proteases were inhibited while KLK7 and KLK8 were induced in the tumor-derived CR cells.

CONCLUSIONS

Given that the drugs in the database are extremely well-characterized and that the patient-derived cells are easily scalable for high throughput drug screening, this combined in vitro and in silico approach may significantly advance personalized PCa treatment and for other cancer applications.

Abstract 2757: Analysis of stromal myofibroblasts identifies secreted proteins that promote pancreatic ductal adenocarcinoma

Pancreatic ductal adenocarcinoma (PDAC) is one of the most incurable types of cancer. Cancer that develops in the acinar cells of the pancreas is typically not diagnosed until later stages, such as stage 3 or 4. As such, this form of cancer is particularly lethal with only 9% of patients reaching 5-year survival. PDAC is known to have a particularly dense extracellular matrix composed of fibroblasts, which have been previously shown to play an important role in promoting resistance to drug therapy. Characterization of the stromal networks involved in PDAC tumor development as well as protein markers of fibroblast subpopulations within the tumor stroma are critical to developing new fibroblast-targeted therapeutic approaches as well as understanding key signaling molecules that ultimately promote tumor progression and drug resistance. Single-cell RNA sequencing (scRNAseq) was utilized to analyze cancer-associated fibroblasts (CAFs) from KPC mouse-derived, MT3 subcutaneous murine allografts along with two fibroblast lines derived from human PDAC tumors: CRC-811 and IA-1340. Single cell gene expression profiling and subsequent analysis of MT3-derived CAFs resulted in the identification of three CAF subpopulations including a myofibroblast subpopulation that expressed high levels of smooth muscle actin (Acta2), which was also observed in both human samples. Fibroblast subpopulations enriched in Acta2 expression, expressed high levels of Wnt5a along with several other secreted factors including Tgfb1, Tgfb2 and Ctgf. Wnt5a is a secreted protein that activates non-canonical Wnt signaling pathways and is known to regulate normal developmental processes, including proliferation, differentiation, migration, adhesion and polarity. However Wnt5a is not natively expressed in MT3 cancer cells derived from syngeneic tumors, but potentially in the stroma. We hypothesize it is exclusively derived from fibroblasts. Previously it has been shown that Wnt5a inhibition suppressed gastric cancer metastasis, therefore further validation of the role of myofibroblast-derived Wnt5a on PDAC disease progression is warranted. This study received funding by LDRD 19-SI-003. This work was conducted under the auspices of the USDOE by LLNL (DE-AC52-07NA27344). IM Release Number: LLNL-ABS-798442.

Citation Format: Kelly A. Martin, Aimy Sebastian, Nicholas R. Hum, Stephen Byers, Elizabeth K. Wheeler, Matthew A. Coleman, Gabriela G. Loots. Analysis of stromal myofibroblasts identifies secreted proteins that promote pancreatic ductal adenocarcinoma [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 2757.

The Sustained Induction of c-MYC Drives Nab-Paclitaxel Resistance in Primary Pancreatic Ductal Carcinoma Cells

Pancreatic ductal adenocarcinoma (PDAC) is a highly aggressive disease with limited and, very often, ineffective medical and surgical therapeutic options. The treatment of patients with advanced unresectable PDAC is restricted to systemic chemotherapy, a therapeutic intervention to which most eventually develop resistance. Recently, nab-paclitaxel (n-PTX) has been added to the arsenal of first-line therapies, and the combination of gemcitabine and n-PTX has modestly prolonged median overall survival. However, patients almost invariably succumb to the disease, and little is known about the mechanisms underlying n-PTX resistance. Using the conditionally reprogrammed (CR) cell approach, we established and verified continuously growing cell cultures from treatment-naïve patients with PDAC. To study the mechanisms of primary drug resistance, nab-paclitaxel-resistant (n-PTX-R) cells were generated from primary cultures and drug resistance was verified in vivo, both in zebrafish and in athymic nude mouse xenograft models. Molecular analyses identified the sustained induction of c-MYC in the n-PTX-R cells. Depletion of c-MYC restored n-PTX sensitivity, as did treatment with either the MEK inhibitor, trametinib, or a small-molecule activator of protein phosphatase 2a. IMPLICATIONS: The strategies we have devised, including the patient-derived primary cells and the unique, drug-resistant isogenic cells, are rapid and easily applied in vitro and in vivo platforms to better understand the mechanisms of drug resistance and for defining effective therapeutic options on a patient by patient basis.

Abstract 1283: Targeting c-MYC and MAPK pathway to overcome pancreatic cancer drug resistance

Background: Acquired resistance to systemic chemotherapy is the main complication in pancreatic ductal adenocarcinoma (PDAC) treatment. Although there are studies focused on gemcitabine resistance mechanisms, our understanding of the mechanisms of nab-paclitaxel (n-PTX) treatment failure remains extremely limited. To enhance the use of properly powered patient-derived platforms, we adopted the conditionally reprogrammed (CR) cell culture technique in order to develop both parental and nab-PTX-resistant cells. The CR approach allowed us to identify the critical role of c-MYC and ERK in the PDAC drug response. Small molecule activators of PP2A (SMAPS) have showed activity in inhibiting lung KRAS-mutant tumor growth. We used SMAPS as new therapeutic agents in PDAC, for its ability to alter c-MYC activity through PP2A dysregulation and enhance PDAC sensitivity to n-PTX.

Methods: Long-term cultures of PDAC CRs were established from treatment-naive PDAC patients’ biopsies, and used to generate drug-resistant cells. Zebrafish and mouse model were used to test the cells’ ability to form tumors and to verify the drug resistance in vivo. Molecular analyses were used to characterize the drug-resistant cells and to identify key pathways involved in the drug resistance evolution. Genomic and chemical alterations of the key proteins were used to confirm the involvement in the drug resistance mechanism. We regulated the expression of c-MYC and ERK using SMAPS as a new targeting agent and trametenib to verify the direct correlation between c-MYC and ERK and the drug resistance mechanism.

Results: Using the credentialed KRAS-mutant CR cultures, we generated n-PTX-resistant cell lines. The parental and nab-PTX resistant cells were subjected to subcutaneous injections in nude mice, and formed tumors in 2-3 weeks. Histological evaluation showed that the CRs self-assembled into ductal structures, surrounded by a desmoplastic stromal microenvironment that faithfully recapitulates human PDAC. Resistant profiles were verified both in mouse and Zebrafish model. RNA microarrays identified a sustained induction of a pro-inflammatory pathway leading to c-MYC overexpression. c-MYC silencing and overexpression confirmed the role of c-MYCin the evolution of nab-PTX resistance. Treatment of the resistant CRs with either trametenib or with SMAPS resulted in enhanced sensitivity to nab-PTX. We furtherverified that the enhanced sensitivity was commensurate with a reduction in p-Erk and c-Myc.

Conclusion: The CR methodology addresses the need for a reliable method for generating primary cell lines on a single patient basis. The ability to rapidly model in vitro, and verify in vivo, that the overexpression of c-MYC contributes to the development of n-PTX resistance is a significant advancement in the field. Our data showed that SMAPs or trametanib overcome a significant component of the n-PTX resistance providing new hope for refractory PDAC.

Citation Format: Erika Maria Parasido, George S. Avetian, Jonathan Brody, Jordan Winter, Eric Londin, Michael Pishvaian, Eric Glasgow, Stephen Byers, Goutham Narla, Christopher Albanese. Targeting c-MYC and MAPK pathway to overcome pancreatic cancer drug resistance [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 1283.

Tumor suppressor RARRES1 links tubulin deglutamylation to mitochondrial metabolism and cell survival

RARRES1, a retinoic acid regulated carboxypeptidase inhibitor associated with fatty acid metabolism, stem cell differentiation and tumorigenesis is among the most commonly methylated loci in multiple cancers but has no known mechanism of action. Here we show that RARRES1 interaction with cytoplasmic carboxypeptidase 2 (CCP2) inhibits tubulin deglutamylation, which in turn regulates the mitochondrial voltage dependent anion channel (VDAC1), mitochondrial membrane potential, AMPK activation, energy balance and metabolically reprograms cells and zebrafish to a more energetic and anabolic phenotype. Depletion of RARRES1 also increases expression of stem cell markers, promotes anoikis, anchorage independent growth and insensitivity to multiple apoptotic stimuli. As depletion of CCP2 or inhibition of VDAC1 reverses the effects of RARRES1 depletion on energy balance and cell survival we conclude that RARRES1 modulation of CCP2-modulated tubulin-mitochondrial VDAC1 interactions is a fundamental regulator of cancer and stem cell metabolism and survival.

Tumor suppressor RARRES1- A novel regulator of fatty acid metabolism in epithelial cells

Retinoic acid receptor responder 1 (RARRES1) is silenced in many cancers and is differentially expressed in metabolism associated diseases, such as hepatic steatosis, hyperinsulinemia and obesity. Here we report a novel function of RARRES1 in metabolic reprogramming of epithelial cells. Using non-targeted LC-MS, we discovered that RARRES1 depletion in epithelial cells caused a global increase in lipid synthesis. RARRES1-depleted cells rewire glucose metabolism by switching from aerobic glycolysis to glucose-dependent de novo lipogenesis (DNL). Treatment with fatty acid synthase (FASN) inhibitor, C75, reversed the effects of RARRES1 depletion. The increased DNL in RARRES1-depleted normal breast and prostate epithelial cells proved advantageous to the cells during starvation, as the increase in fatty acid availability lead to more oxidized fatty acids (FAO), which were used for mitochondrial respiration. Expression of RARRES1 in several common solid tumors is also contextually correlated with expression of fatty acid metabolism genes and fatty acid-regulated transcription factors. Pathway enrichment analysis led us to determine that RARRES1 is regulated by peroxisome proliferating activated receptor (PPAR) signaling. These findings open up a new avenue for metabolic reprogramming and identify RARRES1 as a potential target for cancers and other diseases with impaired fatty acid metabolism.

Characterization of the effects of defined, multidimensional culture conditions on conditionally reprogrammed primary human prostate cells

The inability to propagate human prostate epithelial cells indefinitely has historically presented a serious impediment to prostate cancer research. The conditionally reprogrammed cell (CRC) approach uses the combination of irradiated J2 mouse fibroblasts and a Rho kinase inhibitor such as Y27632 to support the continuous culture of cells derived from most epithelial tissues, including the prostate. Due to their rapid establishment and overall ease of use, CRCs are now widely used in a variety of basic and preclinical settings. In addition, CRCs were successfully used to clinically treat respiratory papillomatosis. Although both normal and tumor-derived prostate CRCs have been used to study the basic biology of prostate cancer and to test new therapies, certain limitations exist. We have previously reported that prostate CRCs form functional prostate glands when implanted under the mouse renal capsule. However in conventional culture, the prostate CRCs exist in an adult stem-like, transient amplifying state and consequently do not adequately recapitulate several important features of a differentiated prostate epithelium. To address these limitations, we previously described a transwell dish-based model that supported the culturing of prostate CRCs and the collection of cells and cell extracts for molecular and genetic analyses. Using normal and tumor-derived prostate CRCs, we describe the combined effects of the multi-dimensional transwell platform and defined culture media on prostate cellular proliferation, differentiation and signaling.

Multiple roles of RARRES1 in prostate cancer: Autophagy induction and angiogenesis inhibition

BACKGROUND

Prostate cancer (PCa) poses a major health concern in men worldwide. Retinoic Acid Receptor Responder (RARRES1)/ Tazarotene-induced gene-1 (TIG-1) is a putative tumor suppressor gene that exerts its tumor suppressor function via unknown mechanisms. Epigenetic silencing of RARRES1 leads to its loss in several types of cancer, including PCa. Determining the molecular mechanisms that mediate the tumor suppressor role of RARRES1 in PCa is the focus of our study.

FINDINGS

Our data indicates that RARRES1 over expression in PCa cell lines represses mitogen-activated protein kinase (MAPK) activation. RARRES1 expression induces the levels of autophagy-related genes, beclin, ATG3 and increases LC3B-II conversion. A significant induction of SIRT1 along with mTOR inhibition is noted on RARRES1 expression. Furthermore, RARRES1 over expression elevates the levels of the antioxidant enzyme, catalase. Our results also indicate that RARRES1 expression inhibits angiogenesis in endothelial cells.

CONCLUSIONS

In summary, the data presented here indicate that forced expression of RARRES1 in PCa cells (a) induces ER stress and autophagic response; (b) increases SIRT1 levels; and (c) higher levels of anti-oxidant enzymes. Our study also implicates the role of RARRES1 as a novel anti-angiogenic molecule. Overall this study reports the molecular players that RARRES1 modulates to serve as a tumor suppressor molecule. Future studies will help determine the in vivo mechanisms by which RARRES1 may serve as a target for therapeutic intervention both in cancer and in angiogenesis-related disorders.

Post-admission outcomes of participants in the PARAMEDIC trial: A cluster randomised trial of mechanical or manual chest compressions

BACKGROUND

The PARAMEDIC cluster randomised trial evaluated the LUCAS mechanical chest compression device, and did not find evidence that use of mechanical chest compression led to an improvement in survival at 30 days. This paper reports patient outcomes from admission to hospital to 12 months after randomisation.

METHODS

Information about hospital length of stay and intensive care management was obtained through linkage with Hospital Episode Statistics and the Intensive Care National Audit and Research Centre. Patients surviving to hospital discharge were approached to complete questionnaires (SF-12v2, EQ-5D, MMSE, HADS and PTSD-CL) at 90days and 12 months. The study is registered with Current Controlled Trials, number ISRCTN08233942.

RESULTS

377 patients in the LUCAS arm and 658 patients in the manual chest compression were admitted to hospital. Hospital and intensive care length of stay were similar. Long term follow-up assessments were limited by poor response rates (53.7% at 3 months and 55.6% at 12 months). Follow-up rates were lower in those with worse neurological function. Among respondents, long term health related quality of life outcomes and emotional well-being was similar between groups. Cognitive function, measured by MMSE, was marginally lower in the LUCAS arm mean 26.9 (SD 3.7) compared to control mean 28.0 (SD 2.3), adjusted mean difference -1.5 (95% CI -2.6 to -0.4).

CONCLUSION

There were no clinically important differences identified in outcomes at long term follow-up between those allocated to the mechanical chest compression compared to those receiving manual chest compression.

Abstract 812: Multiplatform modeling of pancreatic cancer using patient-derived cells: A new approach for defining drug resistance mechanisms

Background: Pancreatic adenocarcinoma (PA) is the fourth leading cause of cancer-related death in the USA. Current treatments utilize Gemcitabine alone or in combination with other drugs, such as nab-paclitaxel, however, a growing number of patients have shown resistance to these regimes. In order to enhance clinical response, it is important to better understand the mechanisms of drug resistance. To date, one of the main limitations in PA research has been the reliance on a few commercially available PA cell lines or a limited number of genetically engineered or PDX mouse models for in vitro and in vivo studies. It was therefore imperative to develop more accurate cellular models that better represent a given patient’s tumor. In our current study, we present the use of patient-derived primary PA cells as a model system for basic and translational research, and for personalized medicine.

Methods: Patients’ biopsies were collected after surgery, and long-term cultures of PA cells were established using the conditional reprogramming of cells (CRC) approach we developed. KRAS and p53 sequencing verified the PA origin of both the patient samples and the matched CRC lines. The IC50s for Gemcitabine and Abraxane were determined and used to establish drug resistant clones. Our two dimensional (2D) CRC cultures have shown to be adaptable to different platforms, such as 3D spheroid cultures as well as zebrafish- and mouse- PDX models.

Results: We established KRAS-mutant primary cell lines derived from patients’ PA samples. From two different parent cell lines we created five nab-paclitaxel and two Gemcitabine resistant clones. The clones were 3-1000 times less sensitive to the drugs as compared with the parent lines. Drug resistance ratios between parent and resistant clones were confirmed both in 3D cultures and our zebrafish PDX platform. The injection of both parent and resistant clones into NCI/nude mice induced tumor masses in 100% of the cases. Unlike the parent cell-derived tumors, the nab-paclitaxel clone-derived tumors exhibited a metastatic phenotype. Histological analyses of these PDX models recognized the presence of morphological features of human PA, including ductal acinar structures comprised of pleomorphic epithelial cells with extensive stromal desmoplasia surrounding the tumors, and thereby represent a fundamentally important advancement in the PDX modeling field.

Conclusion: Overall, the ease of culture, the genetic stability and the high-throughput ability to identify differences between patients sensitivity to FDA approved drugs confirm the power of this technology for on-demand in vitro use in PA research. The in-vivo approach demonstrated the accuracy of our model system in recapitulating the patient tumor. Our method now enables the high-resolution experiments necessary to better understand the resistance mechanisms that directly affect clinical outcomes

Citation Format: Erika Maria Parasido, Praathibha Sripadhan, George Avetian, Richard Schlegel, Jonathan Brody, Jordan Winter, Charles J. Yeo, Michael J. Pishvaian, Erik Glasgow, Stephen Byers, Christopher Albanese. Multiplatform modeling of pancreatic cancer using patient-derived cells: A new approach for defining drug resistance mechanisms [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 812. doi:10.1158/1538-7445.AM2017-812

Enabling Metabolomics Based Biomarker Discovery Studies Using Molecular Phenotyping of Exosome-Like Vesicles

Identification of sensitive and specific biomarkers with clinical and translational utility will require smart experimental strategies that would augment expanding the breadth and depth of molecular measurements within the constraints of currently available technologies. Exosomes represent an information rich matrix to discern novel disease mechanisms that are thought to contribute to pathologies such as dementia and cancer. Although proteomics and transcriptomic studies have been reported using Exosomes-Like Vesicles (ELVs) from different sources, exosomal metabolome characterization and its modulation in health and disease remains to be elucidated. Here we describe methodologies for UPLC-ESI-MS based small molecule profiling of ELVs from human plasma and cell culture media. In this study, we present evidence that indeed ELVs carry a rich metabolome that could not only augment the discovery of low abundance biomarkers but may also help explain the molecular basis of disease progression. This approach could be easily translated to other studies seeking to develop predictive biomarkers that can subsequently be used with simplified targeted approaches.

Evaluation of undergraduate psychiatry teaching in Malawi

In Malawi, mental health services account for only 2% of the health budget; there are just 4.5 full-time psychiatrists and 433 psychiatric beds. The Scotland Malawi Mental Health Education Project (SMMHEP) aims to provide sustainable support for psychiatric training for healthcare professionals and has increased the number of psychiatrists in the country. There has been a recent change in the educational programme in order to maximise clinical exposure and experience, particularly with the care of in-patients. The new programme has had a positive effect on students' attitudes towards psychiatry and their consideration of psychiatry as a career. This paper supports the ongoing work SMMHEP does in developing psychiatric services through education.

Abstract 590: RARRES1 is a modulator of angiogenesis and autophagy

Retinoic Acid Receptor Responder (RARRES1) is a putative tumor suppressor gene that exerts its tumor suppressor function via unknown mechanisms. Determining the molecular mechanisms involved in the function of RARRES1 in important biological processes, angiogenesis and autophagy, is the focus of our study and may delineate molecular targets for therapeutic intervention.

Angiogenesis, the formation of new blood vessels from pre-existing vessels, is a vital requirement for the growth and metastasis of tumors. It constitutes a pivotal step in cancer progression. For the tumors to grow and have the propensity to metastasize they have to undergo the “angiogenic switch”. This switch depends on the dynamic balance between the pro-angiogenic factors (such as HIF-1α and VEGF) and the anti-angiogenic factors (such as thrombospondin, VEGI). Stimuli for angiogenesis include hypoxia, inflammation or genetic variations in tumor suppressors. We sought to determine if RARRES1 expression could modulate angiogenesis. Our results indicate that overexpression of RARRES1 in HUVECs severely impairs in vitro angiogenesis. The data also indicate reduced levels of angiogenic markers and signaling molecules, phospho-VEGF-R and phospho-p38 MAPK. The results demonstrate that RARRES1 expression significantly lowers H2O2-induced ROS production, a known inducer of angiogenesis.

Bioinformatics searches of RARRES1 revealed a potential MAPK binding site, the Erk-D domain and multiple PKC phosphorylation sites. PKC signaling (ERK phosphorylation) has been implicated in cellular autophagy. It is an evolutionarily conserved self-degradative process that plays a housekeeping role by eliminating damaged organelles and misfolded or aggregated proteins via the lysosomal degradation pathway. Deregulation of autophagy has been reported in various cancers. Interestingly, our data indicates that RARRES1 expression induces phospho-ERK in multiple cancer cell lines. We hypothesized that the increased phospho-ERK levels in RARRES1 expressing cells would result in autophagy induction. Our results demonstrate that RARRES1 expression induces the expression of autophagy markers, ATG3, beclin and LC-3β.

In summary, the data presented here indicate that (a) loss of RARRES1 results in increased ROS production and angiogenesis by p38 MAPK activation and (b) autophagy defects in RARRES1-deficient cancer cells facilitates tumor progression. Our study implicates that RARRES1 may be a novel anti-angiogenic molecule that induces autophagic response. Future studies will determine the mechanism between these important cell-biological processes and if RARRES1 may serve as a target for therapeutic intervention both in cancer and in angiogenesis-related disorders.

Citation Format: Arpita Roy, Okjin Jean Kim, Malathi Ramalinga, Solomon Lynch, Stephen Byers, Deepak Kumar. RARRES1 is a modulator of angiogenesis and autophagy. [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 590. doi:10.1158/1538-7445.AM2014-590

Soluble-E-cadherin activates HER and IAP family members in HER2+ and TNBC human breast cancers

Recent literature suggests that sEcad exerts pro-oncogenic effects, possibly acting as a ligand for the human epidermal growth factor family. Here we show that sEcad is a novel candidate protein for drug targeting since it is increased in human and mouse HER2-positive (HER2+) breast tumors, MMTV-PyMT bodily fluids and human cell culture systems. Mechanistically, we show that endogenous sEcad, and to a lesser extent membrane-bound E-cadherin, associates with HER1, HER2, and HER3 in human and MMTV-PyMT mouse HER2+ tumors and with HER1 in triple negative breast cancer (TNBC) specimens. Furthermore, addition of exogenous recombinant human E-cadherin/Fc chimeric protein (rhEcad/Fc; sEcad) to HER2+ MCF-7, SKBR3, and HER2-negative MDA-MB-231 TNBC cells, resulted in sEcad-HER receptor family interactions, activation of HER1-4 and downstream pro-survival signaling, including the MAPK-PI3K/Akt/mTOR pathways and IAP family members. Lastly, we demonstrate that sEcad exerts pro-oncogenic effects via HER signaling, and acts additively with the HER ligand EGF to promote HER2+ breast cancer proliferation and migration, as well as TNBC invasion. Because sEcad associates and activates many of the oncogenic pathways that tumors utilize for growth and survival and serum levels in patients correlates with clinical response, suggests that targeted therapy against sEcad in combination with other therapies may potentially offer a novel therapeutic strategy for the treatment of breast cancers.

Monoclonal antibody against the ectodomain of E-cadherin (DECMA-1) suppresses breast carcinogenesis: involvement of the HER/PI3K/Akt/mTOR and IAP pathways

PURPOSE

Although targeted therapies against HER2 have been one of the most successful therapeutic strategies for breast cancer, patients eventually developed acquired resistance from compensatory upregulation of alternate HERs and mitogen-activated protein kinase-phosphoinositide 3-kinase (PI3K)/Akt/mTOR signaling. As we and others have shown that the soluble ectodomain fragment of E-cadherin exerts prooncogenic effects via HER1/2-mediated binding and activation of downstream prosurvival pathways, we explored whether targeting this ectodomain [DECMA-1 monoclonal antibody (mAb)] was effective in the treatment of HER2-positive (HER2(+)) breast cancers.

EXPERIMENTAL DESIGN

MMTV-PyMT transgenic mice and HER2(+)/E-cadherin-positive MCF-7 and BT474 trastuzumab-resistant (TtzmR) cells were treated with the DECMA-1 mAb. Antitumor responses were assessed by bromodeoxyuridine incorporation, apoptosis, and necrosis. The underlying intracellular prooncogenic pathways were explored using subcellular fractionation, immunoprecipitation, fluorescence microscopy, and immunoblotting.

RESULTS

Treatment with DECMA-1 mAb significantly delayed tumor onset and attenuated tumor burden in MMTV-PyMT mice by reducing tumor cell proliferation and inducing apoptosis without any detectable cytotoxicity to mice or end-organs. In vitro treatment of MCF-7 and BT474 TtzmR cells reduced proliferation and induced cancer cell apoptosis. Importantly, this inhibition of breast tumorigenesis was due to concomitant downregulation, via ubiquitin-mediated degradation through the lysosome and proteasome pathways, of all HER family members, components of downstream PI3K/Akt/mTOR prosurvival signaling and suppression of inhibitor of apoptosis proteins.

CONCLUSIONS

Our results establish that the E-cadherin ectodomain-specific mAb DECMA-1 inhibits Ecad(+)/HER2(+) breast cancers by hindering tumor growth and inducing apoptosis via downregulation of key oncogenic pathways involved in trastuzumab resistance, thereby establishing a novel therapeutic platform for the treatment of HER2(+) breast cancers.

Evaluation of four point-of-care glucose meters in alpacas

PURPOSE

Hospitalized alpacas are often hyperglycemic requiring frequent blood glucose testing.

OBJECTIVES

To compare the performance of 4 brands of glucometers with a laboratory-based analyzer (LCA) over a range of glucose concentrations in alpacas.

ANIMALS

Four healthy male alpacas.

METHODS

A 2-treatment cross-over study was utilized. The alpacas were given 0.4 U/kg of regular insulin intravenously and then 500 mg/kg of dextrose intravenously with a 1 week washout period between treatments. Blood samples were collected from 10 minutes before until 6 hours after drug administration. Glucose concentrations were measured in whole blood and plasma samples on 4 glucometers, and serum glucose was measured on an LCA.

RESULTS

Glucometer performance varied depending on whether glucose concentrations were measured in plasma or whole blood. Based on error grid analysis, the Precision Xtra and One Touch Ultra 2 glucometers were clinically acceptable for testing whole blood samples, whereas the Accu-Chek Aviva and Nova StatStrip Xpress glucometers were clinically acceptable for testing plasma samples in comparison with serum glucose concentrations determined by the LCA. All glucometers had systematic and proportional biases that varied based on sample type.

CONCLUSIONS AND CLINICAL IMPORTANCE

Human-based glucometers in alpacas should be used cautiously, particularly at higher blood glucose concentrations. The blood sample type (plasma or whole blood) can alter meter performance when compared with serum glucose concentrations and potentially lead to errors in clinical decisions.

The mitochondrial citrate transporter, CIC, is essential for mitochondrial homeostasis

Dysregulation of the pathways that preserve mitochondrial integrity hallmarks many human diseases including diabetes, neurodegeration, aging and cancer. The mitochondrial citrate transporter gene, SLC25A1 or CIC, maps on chromosome 22q11.21, a region amplified in some tumors and deleted in developmental disorders known as velo-cardio-facial- and DiGeorge syndromes. We report here that in tumor cells CIC maintains mitochondrial integrity and bioenergetics, protects from mitochondrial damage and circumvents mitochondrial depletion via autophagy, hence promoting proliferation. CIC levels are increased in human cancers and its inhibition has anti-tumor activity, albeit with no toxicity on adult normal tissues. The knock-down of the CIC gene in zebrafish leads to mitochondria depletion and to proliferation defects that recapitulate features of human velo-cardio-facial syndrome, a phenotype rescued by blocking autophagy. Our findings reveal that CIC maintains mitochondrial homeostasis in metabolically active, high proliferating tissues and imply that this protein is a therapeutic target in cancer and likely, in other human diseases.

Development of a novel assay for human tyrosyl DNA phosphodiesterase 2

Tyrosyl DNA phosphodiesterase 2 (TDP2), a newly discovered enzyme that cleaves 5'-phosphotyrosyl bonds, is a potential target for chemotherapy. TDP2 possesses both 3'- and 5'-tyrosyl-DNA phosphodiesterase activity, which is generally measured in a gel-based assay using 3'- and 5'-phosphotyrosyl linkage at the 3' and 5' ends of an oligonucleotide. To understand the enzymatic mechanism of this novel enzyme, the gel-based assay is useful, but this technique is cumbersome for TDP2 inhibitor screening. For this reason, we have designed a novel assay using p-nitrophenyl-thymidine-5'-phosphate (T5PNP) as a substrate. This assay can be used in continuous colorimetric assays in a 96-well format. We compared the salt and pH effect on product formation with the colorimetric and gel-based assays and showed that they behave similarly. Steady-state kinetic studies showed that the 5' activity of TDP2 is 1000-fold more efficient than T5PNP. Tyrosyl DNA phosphodiesterase 1 (TDP1) and human AP-endonuclease 1 (APE1) could not hydrolyze T5PNP. Sodium orthovanadate, a known inhibitor of TDP2, inhibits product formation from T5PNP by TDP2 (IC(50)=40 mM). Our results suggest that this novel assay system with this new TDP2 substrate can be used for inhibitor screening in a high-throughput manner.

Neurological causes of diaphragmatic paralysis in 11 alpacas (Vicugna pacos)

Background: Diaphragmatic paralysis is a relatively uncommon medical condition in animals not reported in alpacas.

Objectives: Describe the signalment, physical examination, diagnostic testing, clinical, and histopathologic findings related to diaphragmatic paralysis in alpacas.

Animals: Eleven alpacas with spontaneous diaphragmatic paralysis.

Methods: A retrospective study examined medical records from a 10‐year period and identified 11 alpacas with confirmed diaphragmatic paralysis admitted to Washington State University and Colorado State University Veterinary Teaching Hospitals between September 2003 and October 2009.

Results: The 11 alpacas ranged in age from 2 to 12 months. Fluoroscopic imaging confirmed the presence of bilateral diaphragmatic paralysis in the 7 alpacas that were imaged. Arterial blood gas analyses showed hypercapnea, hypoxemia, and low oxygen saturation. Seven alpacas died or were euthanized between 2 and 60 days after onset of respiratory signs. Histopathologic examination of tissues found phrenic nerve degeneration in the 6 alpacas that were necropsied and additional long nerves examined demonstrated degeneration in 2 of these animals. Two animals had spinal cord lesions and 2 had diaphragm muscle abnormalities. No etiologic agent was identified in the alpacas.

Conclusions and Clinical Importance: The etiology for diaphragmatic paralysis in these alpacas is unknown. A variety of medical treatments did not appear to alter the outcome.

Novel anti-filamin-A antibody detects a secreted variant of filamin-A in plasma from patients with breast carcinoma and high-grade astrocytoma

Identification of tumor-derived proteins in the circulation may allow for early detection of cancer and evaluation of therapeutic responses. To identify circulating tumor-derived proteins, mice were immunized with concentrated culture medium conditioned by human breast cancer cells. Antibodies generated by hybridomas were screened against conditioned media from both normal epithelial cells and tumor cells. Antibody selectively reacting with tumor cell-conditioned media was further characterized. This led to the development of a monoclonal antibody (Alper-p280) that reacts with a newly identified 280-kDa secreted variant of human filamin-A. Circulating filamin-A was detected in patient plasma samples using Alper-p280 in an ELISA assay. Human plasma samples from 134 patients with brain, breast, or ovarian cancer, 15 patients with active arthritis, and 76 healthy controls were analyzed. Filamin-A protein levels in human cell lines and tissues were analyzed by western blotting, immunohistochemistry, and electron and confocal microscopy. Circulating filamin-A was detected in the plasma of 109 of 143 patients with breast cancer and primary brain tumors. Plasma levels of filamin-A showed 89.5% sensitivity (95% confidence interval [CI] = 0.67% to 0.99%) and 97.8% specificity (95% CI = 0.88% to 0.99%) for glioblastoma at a cut-off of 21.0 ng/mL. Plasma levels of filamin-A (>36.0 ng/mL) had 96.7% sensitivity (95% CI = 0.80% to 0.99%) and 67.8% specificity (95% CI = 0.54% to 0.79%) for metastatic breast cancer. Filamin-A levels were increased in malignant breast or brain tissues, but not in normal control tissues. Filamin-A localized to lysosomes in MDA.MB.231 breast cancer cells, but not in normal human mammary epithelial cells, suggesting that filamin-A may undergo cancer-specific processing. Plasma filamin-A appears to be a specific and sensitive marker for patients with high-grade astrocytoma or metastatic breast cancer. Additional novel cancer biomarkers have been identified and are being developed alongside Alper-p280 for use in diagnosis of breast carcinoma and high-grade astrocytoma, and for use in the evaluation of therapeutic responses.

Liver stem cells and hepatocellular carcinoma

Although the existence of cancer stem cells (CSCs) was first proposed over 40 years ago, only in the past decade have these cells been identified in hematological malignancies, and more recently in solid tumors that include liver, breast, prostate, brain, and colon. Constant proliferation of stem cells is a vital component in liver tissues. In these renewing tissues, mutations will most likely result in expansion of the altered stem cells, perpetuating and increasing the chances of additional mutations and tumor progression. However, many details about hepatocellular cancer stem cells that are important for early detection remain poorly understood, including the precise cell(s) of origin, molecular genetics, and the mechanisms responsible for the highly aggressive clinical picture of hepatocellular carcinoma (HCC). Exploration of the difference between CSCs from normal stem cells is crucial not only for the understanding of tumor biology but also for the development of specific therapies that effectively target these cells in patients. These ideas have drawn attention to control of stem cell proliferation by the transforming growth factor beta (TGF-beta), Notch, Wnt, and Hedgehog pathways. Recent evidence also suggests a key role for the TGF-beta signaling pathway in both hepatocellular cancer suppression and endoderm formation, suggesting a dual role for this pathway in tumor suppression as well as progression of differentiation from a stem or progenitor stage. This review provides a rationale for detecting and analyzing tumor stem cells as one of the most effective ways to treat cancers such as HCC.

Liver stem cells and hepatocellular carcinoma

Although the existence of cancer stem cells (CSCs) was first proposed over 40 years ago, only in the past decade have these cells been identified in hematological malignancies, and more recently in solid tumors that include liver, breast, prostate, brain, and colon. Constant proliferation of stem cells is a vital component in liver tissues. In these renewing tissues, mutations will most likely result in expansion of the altered stem cells, perpetuating and increasing the chances of additional mutations and tumor progression. However, many details about hepatocellular cancer stem cells that are important for early detection remain poorly understood, including the precise cell(s) of origin, molecular genetics, and the mechanisms responsible for the highly aggressive clinical picture of hepatocellular carcinoma (HCC). Exploration of the difference between CSCs from normal stem cells is crucial not only for the understanding of tumor biology but also for the development of specific therapies that effectively target these cells in patients. These ideas have drawn attention to control of stem cell proliferation by the transforming growth factor beta (TGF-beta), Notch, Wnt, and Hedgehog pathways. Recent evidence also suggests a key role for the TGF-beta signaling pathway in both hepatocellular cancer suppression and endoderm formation, suggesting a dual role for this pathway in tumor suppression as well as progression of differentiation from a stem or progenitor stage. This review provides a rationale for detecting and analyzing tumor stem cells as one of the most effective ways to treat cancers such as HCC.

Hyaluronan synthesis and degradation in cartilage and bone

Hyaluronan (HA) is a large but simple glycosaminoglycan composed of repeating D-glucuronic acid, beta1-3 linked to N-acetyl-D-glucosamine beta1-4, found in body fluids and tissues, in both intra- and extracellular compartments. Despite its structural simplicity, HA has diverse functions in skeletal biology. In development, HA-rich matrices facilitate migration and condensation of mesenchymal cells, and HA participates in joint cavity formation and longitudinal bone growth. In adult cartilage, HA binding to aggrecan immobilises aggrecan, retaining it at the high concentrations required for compressive resilience. HA also appears to regulate bone remodelling by controlling osteoclast, osteoblast and osteocyte behaviour. The functions of HA depend on its intrinsic properties, which in turn rely on the degree of polymerisation by HA synthases, depolymerisation by hyaluronidases, and interactions with HA-binding proteins. HA synthesis and degradation are closely regulated in skeletal tissues and aberrant synthetic or degradative activity causes disease. The role and regulation of HA synthesis and degradation in cartilage, bone and skeletal development is discussed.

Eukaryotic initiation factor 6 selectively regulates Wnt signaling and beta-catenin protein synthesis

Eukaryotic initiation factor 6 (eIF6), an essential protein important in ribosome biosynthesis and assembly, was identified as an interacting partner of the beta-catenin C terminus in the yeast two-hybrid assay. Independent studies identified Drosophila eIF6 (DeIF6) in a genetic screen designed to detect new genes involved in the regulation of the Wnt/Wg (wingless) pathway. Ectopic expression of DeIF6 in wing discs results in a Wg phenotype. Expression of eIF6 in adenomatous polyposis coli (APC)-mutant colon cancer cells, which express high levels of active beta-catenin, showed that eIF6 selectively inhibits the Wnt pathway at the level of beta-catenin protein independently of proteasomal degradation. Incorporation of radiolabeled amino acids into beta-catenin was selectively decreased in cells that overexpressed eIF6. A similar inverse relationship of the two proteins was observed in the APC(min/+) mouse intestine, in which beta-catenin levels are very high. Taken together these data reveal a link between eIF6 and Wnt signaling, perhaps at the level of ribosome recycling on beta-catenin mRNA.

Cyclin D1 determines mitochondrial function in vivo

The cyclin D1 gene encodes a regulatory subunit of the holoenzyme that phosphorylates and inactivates the pRb tumor suppressor to promote nuclear DNA synthesis. cyclin D1 is overexpressed in human breast cancers and is sufficient for the development of murine mammary tumors. Herein, cyclin D1 is shown to perform a novel function, inhibiting mitochondrial function and size. Mitochondrial activity was enhanced by genetic deletion or antisense or small interfering RNA to cyclin D1. Global gene expression profiling and functional analysis of mammary epithelial cell-targeted cyclin D1 antisense transgenics demonstrated that cyclin D1 inhibits mitochondrial activity and aerobic glycolysis in vivo. Reciprocal regulation of these genes was observed in cyclin D1-induced mammary tumors. Cyclin D1 thus integrates nuclear DNA synthesis and mitochondrial function.

The effect of recombinant human osteogenic protein-1 on growth plate repair in a sheep model

Injuries to the growth plate in children can result in bone bridge formation, which ultimately lead to limb length and angular deformities. The histological and molecular changes associated with growth plate repair following the Langenskiöld procedure, a surgical technique used to remove impeding bone bridges, in conjunction with administration of recombinant human osteogenic protein-1 (rhOP-1) were examined using a sheep model. Following treatment with rhOP-1 there was an increase in the height of the growth plate immediately adjacent to the defect compared to untreated animals. The expression of type I collagen, osteopontin and decorin were observed in the growth plate adjacent to the defect in the untreated animals at day 56, but this response was accelerated in the rhOP-1 treated animals, with these molecules seen as early as day 7. Therefore, treatment with rhOP-1 initiated a complex response that was both chondrogenic and osteogenic in nature.

The p75NTR mediates a bifurcated signal transduction cascade through the NF kappa B and JNK pathways to inhibit cell survival

p75NTR is most abundantly expressed in the nervous system, but is also widely expressed in many other organs and tissues where it primarily functions as a negative regulator of cell survival. In the prostate, p75NTR functions as an inhibitory protein capable of slowing proliferation and inducing apoptosis. It has been shown that p75NTR is expressed in the normal prostate, progressively lost from malignant tumor cells in vivo, and largely absent from prostate cancer cell lines derived from metastases. Although the role of p75NTR in prostate cancer has been well established, the signal transduction pathway that mediates its inhibitory activity has only been partially elucidated. This study demonstrates that exogenous expression of p75NTR down-regulates, in a dose-dependent manner, a bifurcated signaling cascade that results in reduced expression of potent transcription effectors. This two-arm signal transduction cascade was directly linked to the upstream receptor by using dominant-negative deletion constructs of p75NTR that rescued tumor cells from p75NTR-induced loss of survival and promotion of apoptosis. Furthermore, the dominant negatives rescued alterations in the levels of signal transduction intermediates. Conversely, the use of kinase-inactive intermediates that are downstream of the receptor further reduced expression of involved transcription effectors and reduced survival of the cells. These results provide a definitive link between the proximate p75NTR and signal transduction intermediates leading to the transcription effectors NF kappa B and JNK, with associated growth suppression and induction of apoptosis.

Beta-catenin binds to the activation function 2 region of the androgen receptor and modulates the effects of the N-terminal domain and TIF2 on ligand-dependent transcription

Beta-catenin is a multifunctional molecule that is activated by signaling through WNT receptors. beta-Catenin can also enhance the transcriptional activity of some steroid hormone receptors such as the androgen receptor and retinoic acid receptor alpha. Androgens can affect nuclear translocation of beta-catenin and influence its subcellular distribution. Using mammalian two-hybrid binding assays, analysis of reporter gene transcription, and coimmunoprecipitation, we now show that beta-catenin binds to the androgen receptor ligand-binding domain (LBD) and modulates the transcriptional effects of TIF2 and the androgen receptor N-terminal domain (NTD). In functional assays, beta-catenin bound to androgen receptor only in the presence of ligand agonists, not antagonists. Beta-catenin binding to the androgen receptor LBD was independent of and cooperative with the androgen receptor NTD and the p160 coactivator TIF2, both of which bind to the activation function 2 (AF-2) region of the androgen receptor. Different mutations of androgen receptor helix 3 amino acids disrupted binding of androgen receptor NTD and beta-catenin. beta-Catenin, androgen receptor NTD, and TIF2 binding to the androgen receptor LBD were affected similarly by a subset of helix 12 mutations, but disruption of two sites on helix 12 affected only binding of beta-catenin and not of TIF2 or the androgen receptor NTD. Mutational disruption of each of five LXXLL peptide motifs in the beta-catenin armadillo repeats did not disrupt either binding to androgen receptor or transcriptional coactivation. ICAT, an inhibitor of T-cell factor 4 (TCF-4), and E-cadherin binding to beta-catenin also blocked binding of the androgen receptor LBD. We also demonstrated cross talk between the WNT and androgen receptor signaling pathways because excess androgen receptor could interfere with WNT signaling and excess TCF-4 inhibited the interaction of beta-catenin and androgen receptor. Taken together, the data show that beta-catenin can bind to the androgen receptor LBD and modulate the effects of the androgen receptor NTD and TIF2 on transcription.

Regulation of beta-catenin function by the IkappaB kinases

Both the beta-catenin and the nuclear factor kappaB (NF-kappaB) proteins are important regulators of gene expression and cellular proliferation. Two kinases, IKKalpha and IKKbeta, are critical activators of the NF-kappaB pathway. Here we present evidence that these kinases are also important in the regulation of beta-catenin function. IKKalpha- and IKKbeta-deficient mouse embryo fibroblasts exhibited different patterns of beta-catenin cellular localization. IKKbeta decreases beta-catenin-dependent transcriptional activation, while IKKalpha increases beta-catenin-dependent transcriptional activity. IKKalpha and IKKbeta interact with and phosphorylate beta-catenin using both in vitro and in vivo assays. Our results suggest that differential interactions of beta-catenin with IKKalpha and IKKbeta may in part be responsible for regulating beta-catenin protein levels and cellular localization and integrating signaling events between the NF-kappaB and Wingless pathways.

Metaphyseal factors promote calcium incorporation in physeal chondrocyte cultures

Our hypothesis is that physiological mineralization within the mammalian growth plate is a consequence of communication between cartilage chondrocytes and cells within metaphyseal bone. To test this hypothesis, chondrocytes were isolated from the proliferative region of the fetal ovine physis and co-cultured with cells or conditioned medium from cells characteristic of those in metaphyseal bone. The mineralization potential of chondrocytes alone and in the presence of other cells or conditioned medium was determined by 45calcium incorporation. Co-culture of chondrocytes with a crude cell isolate from metaphyseal bone resulted in a stimulation of 45calcium incorporation of 93% above that observed in the individual cell populations alone. Conditioned medium from metaphyseal bone cultures also stimulated 45calcium incorporation. This response to conditioned medium was dose-dependent and stable to 90 degrees C. Vascular endothelial cells and conditioned medium from chondrocyte and osteoblast cultures did not stimulate 45calcium incorporation by physeal chondrocytes. Thus, cells found in the metaphyseal bone produce a soluble factor, which promote calcium incorporation by physeal chondrocytes. The source of this factor is not chondrocytic, osteoblastic, or endothelial in origin.

Automated assay for nicotinamide adenine dinucleotide (NAD+)

Sulfur mustard (HD), a vesicating chemical warfare compound, has been shown to deplete the nicotinamide adenine dinucleotide (NAD+) content in several cell systems and tissues. This NAD+ depletion has been proposed as an indicator of HD exposure and can be used to evaluate potential antivesicant compounds. To examine NAD+ levels, an automated method based on the alcohol dehydrogenase cycling assay of Jacobson and Jacobson and utilizing a Cobas FARA clinical analyzer has been developed. Automation of this assay led to smaller sample volumes and more efficient use of personnel and resources. The usefulness of this automated method was tested by evaluating the protection, if any, by the topical application of vitamin D or betamethasone against HD-induced NAD+ depletion in skin punches from the hairless guinea pig. The results showed that the samples exposed to HD exhibited significant decreases in NAD+ levels when compared with controls. However, neither vitamin D nor betamethasone demonstrated protection against HD-induced NAD+ depletion. In fact, betamethasone exacerbated the NAD+ depletion when compared with the HD exposed group. This assay appears to be useful for testing potential antivesicant compounds using both in vivo and in vitro exposure systems.

Spatial arrangement of physeal cartilage chondrocytes and the structure of the primary spongiosa

Using laser confocal microscopy and 5-chloromethyl-fluoresceindiacetate (CMFDA) loading of chondrocytes we have investigated the structure of the ovine physis during late fetal development and its relationship to the structure observed in the primary spongiosa. Chondrocytes within the ovine growth plate form nests that together span the growth plate. We propose that all growth plates may be composed of nests of cells, but that the length of the individual nests changes between growth plates and with gestational age. The continuous column of cells seen within some growth plates is a nest of cells that is in the process of being absorbed by the invading metaphyseal front. Scanning electron microscopy of the mineralized portion of the primary spongiosa revealed structures that were consistent with the hypothesis that the cartilage surrounding the nest structure gives rise to the structure in the primary spongiosa. Although mineralization does not occur between cells within a nest, bands of mineral form between nests in the lower hypertrophic region and around the end of the nest as it reaches the hypertrophic region. This pattern of mineralization around and between nest termini yields the complex three-dimensional network of mineralized trabeculae observed in the primary spongosia.

Quantitative histomorphometric analysis of the human growth plate from birth to adolescence

Longitudinal bone growth occurs via the transformation of growth plate cartilage into bone through a series of cell and matrix changes, termed endochondral ossification. In this study, we characterize the development of trabecular bone from growth plate cartilage in the human rib from birth to adolescence. The height of the proliferative and hypertrophic zones within the growth plate and the primary bone spongiosa decreased with increasing age, with the greatest change observed in the first year of postnatal life. Within these zones, an internal rearrangement of tissue structure occurred. The matrix volume fraction (either cartilage or bone) increased with age in each of the zones. A concomitant increase in cartilage septae thickness and bone trabecular thickness was observed. A decrease in cartilage septae number was seen in the proliferative zone and a decrease in bone trabeculae number was also observed in the primary spongiosa. However, no difference in cartilage septae number was noted in the hypertrophic zone, the region at which cartilage is transformed into bone. Together the proliferative and hypertrophic regions of the growth plate and the bone primary spongiosa appear to constitute the active growth region, with concomitant changes observed that result in longitudinal growth. In contrast, bone mineral volume in the secondary spongiosa was stable over the ages examined; however, trabecular architecture underwent consolidation as trabecular number decreased and trabecular thickness increased. The integration of the structural transformation from cartilage to bone is crucial in achieving the dual purposes of longitudinal growth and peak bone mass. The structure developed during childhood will have an important bearing on the response to bone-altering disease in later life.

Inference on a collapsed margin in disease mapping

This paper describes a method for estimating the risk from a disease over a set of contiguous geographical regions, when data on a potentially important covariate, such as race, are not available. Conditions under which the extra margin can be recovered are suggested. An application to prostate cancer mortality among the non-white population in the counties of the U.S.A. is discussed.

Beta-catenin affects androgen receptor transcriptional activity and ligand specificity

beta-Catenin is a multifunctional molecule with important roles in intercellular adhesion and signal transduction. We reported previously that beta-catenin is mutated in human prostate cancer. In this study, we investigated the role of beta-catenin mutations on androgen receptor (AR) signaling. beta-Catenin significantly enhanced androgen-stimulated transcriptional activation by the AR. beta-Catenin also increased AR transcriptional activation by androstenedione and estradiol and diminished the antagonism of bicalutamide. Coimmunoprecipitation of beta-catenin with AR from LNCaP prostate cancer cells showed that the two molecules are present in the same complex. The amount of beta-catenin in complex with AR was increased by androgen. These findings implicate beta-catenin in the regulation of AR function and support a role for beta-catenin mutations in the pathogenesis of prostate cancer.