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Supplementary Data figures and tables Fig. S1. Genomic characterization of CR cells. Fig. S2. Karyotype analysis of CR cells. Fig. S3. Drug sensitivity profiles of CR cells. Fig. S4. Population doubling times of Parental and nab-paclitaxel resistant cells. Fig. S5. Nab-paclitaxel sensitivity of CR spheroids. Fig. S6. Dependency of CR cells on KRAS. Fig. S7. CR-based PDX tumors in mice. Fig. S8. Reverse Phase Proteomic analysis of Parental and nab-paclitaxel resistant cells. Fig. S9. Modulation of c-Myc and the effects on nab-paclitaxel sensitivity. Fig. S10. SMAP2 Responses. Table S1. Patient data Table S2. Gene mutations associated with nab-paclitaxel resistance

Single-cell RNA sequencing (scRNA-seq) is highly dependent on cellular composition of a tissue of interest. For soft tissues, isolation of individual cells from the extracellular matrix (ECM) while retaining viability and minimizing degradation within subpopulations is well established. In contrast, articular cartilage is comprised of sparsely positioned chondrocytes embedded within a dense ECM high in glycosaminoglycans, proteoglycans, and many fibrous proteins such as collagens, elastin, fibronectin, and laminins. This densely packed ECM makes it difficult to isolate viable chondrocytes for further single-cell analysis. This protocol highlights a successful technique optimized for isolating chondrocytes from the articulated joints of rodent animal models using a series of enzymatic digestions and chondrocyte enrichment using a double negative selection process through florescence-activated cell sorting (FACS).

NANT2011-11 evaluatedThe cohort included 99 patients who had at least one biomarker available for analysis. Significant modulation in most biomarkers between baseline, 72 hours, and 96 hours followingPeripheral blood biomarkers relevant to radiation exposure demonstrate significant modulation after 131I-MIBG and concomitant radiation sensitizers impact extent of modulation. Biomarkers related to hematopoietic damage and apoptosis were associated with hematologic toxicity.

Rift Valley fever virus (RVFV) is a highly pathogenic mosquito-borne virus capable of causing hepatitis, encephalitis, blindness, hemorrhagic syndrome, and death in humans and livestock. Upon aerosol infection with RVFV, the brain is a major site of viral replication and tissue damage, yet pathogenesis in this organ has been understudied. Here, we investigated the immune response in the brain of RVFV infected mice. In response to infection, microglia initiate robust transcriptional upregulation of antiviral immune genes, as well as increased levels of activation markers and cytokine secretion that is dependent on mitochondrial antiviral-signaling protein (MAVS) and independent of toll-like receptors 3 and 7. In vivo, Mavs-/- mice displayed enhanced susceptibility to RVFV as determined by increased brain viral burden and higher mortality. Single-cell RNA sequence analysis identified microglia-specific defects in type I interferon and interferon responsive gene expression in Mavs-/- mice, as well as dysregulated lymphocyte infiltration. The results of this study provide a crucial step towards understanding the precise molecular mechanisms by which RVFV infection is controlled in the brain and will help inform the development of vaccines and antiviral therapies that are effective in preventing encephalitis.Author SummaryRift Valley fever virus causes severe disease in humans and livestock and in some cases can be fatal. There is concern about the use of Rift Valley fever virus as a bioweapon since it can be transmitted through the air, and there are no vaccines or antiviral treatments. Airborne transmission of the virus causes severe inflammation of the brain, yet little is known about the immune response against the virus in this organ. Here, we investigated the immune response in the brain to Rift Valley fever virus following intranasal infection. We determined that microglia, the resident immune cells of the brain, initiate a robust response to Rift Valley fever virus infection and identified a key immune pathway that is critical for the ability of microglia to respond to infection. When this immune pathway is rendered non-functional, mice have a dysregulated response to infection in the brain. This study provides insight into how the immune response can control Rift Valley fever virus infection of the brain.

Non-small cell lung cancer (NSCLC) patients exhibit minimal symptoms until late-stage disease, resulting in approximately 80% of patients being diagnosed at advanced stages when the response to therapy is low. Effective pre-clinical models are needed to accurately reflect NSCLC disease progression and improve basic NSCLC research. This work characterizes two genetically engineered mouse models (GEMM) that reflect human NSCLC. These mouse lines utilize a cre recombinase system to induce the expression of two oncogenic mutations (KrasG12D, Trp53fl) in club cells or alveolar epithelial cells based on cell type-specific promoters (Scgb1a1, Sftpc), thereby inducing NSCLC in mice. Furthermore, these mice harbor tumor cell-specific transgenes (GFP, MetRS) for cancer tracking. The MetRS transgene allows tumor cells to incorporate azide-bearing methionine analogs (ANL) into newly synthesized proteins which can then be detected via fluorescent noncanonical amino acid tagging (FUNCAT). Cancer mutations were induced at 6 weeks of age and lung samples were collected for histological analysis at early, mid, and late time points. Histological analysis of the club cell model revealed that hyperplasias are most abundant at the early time point and develop into invasive carcinomas within the bronchioles and alveoli at later time points. Histological scoring of this model showed that tumor burden increased from 28% to 61% of the total lung area after 15 weeks. The alveolar cell model progressed rapidly and exhibited adenocarcinomas and squamous cell carcinomas throughout disease progression. Histological scoring of this model revealed that tumor burden rapidly increased from 55% to 89% of total lung area after 5 weeks. FUNCAT analysis demonstrated that the incorporation of ANL within tumor-bearing mice was cancer-cell-specific. These findings suggest that the GEMM models accurately represent human NSCLC based on their cellular profile, morphology, and localization within the lung. The results also confirm that the tumor cells, and not the normal cells/tissues, are able to incorporate ANL into their proteins via the MetRS transgene. These models have the potential to identify biomarkers of NSCLC progression to improve patient prognosis. *This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344. LLNL-ABS-839507. Citation Format: Nicole F. Leon, David Baliu-Rodriguez, Deepa K. Murugesh, Aimy Sebastian, Gabriela G. Loots, Nicholas R. Hum. Histological characterization of two genetically engineered mouse models of non-small cell lung cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 9.

Brain-on-a-chip systems are designed to simulate brain activity using traditional in vitro cell culture on an engineered platform. It is a noninvasive tool to screen new drugs, evaluate toxicants, and elucidate disease mechanisms. However, successful recapitulation of brain function on these systems is dependent on the complexity of the cell culture. In this study, we increased cellular complexity of traditional (simple) neuronal cultures by co-culturing with astrocytes and oligodendrocyte precursor cells (complex culture). We evaluated and compared neuronal activity (e.g., network formation and maturation), cellular composition in long-term culture, and the transcriptome of the two cultures. Compared to simple cultures, neurons from complex co-cultures exhibited earlier synapse and network development and maturation, which was supported by localized synaptophysin expression, up-regulation of genes involved in mature neuronal processes, and synchronized neural network activity. Also, mature oligodendrocytes and reactive astrocytes were only detected in complex cultures upon transcriptomic analysis of age-matched cultures. Functionally, the GABA antagonist bicuculline had a greater influence on bursting activity in complex versus simple cultures. Collectively, the cellular complexity of brain-on-a-chip systems intrinsically develops cell type-specific phenotypes relevant to the brain while accelerating the maturation of neuronal networks, important features underdeveloped in traditional cultures.

Despite the success of T cell checkpoint therapies, breast cancers rarely express these immunotherapy markers and are believed to be largely "immune cold" with limited inflammation and immune activation. The reason for this limited immune activation remains poorly understood. We sought to determine whether extracellular matrix substrate could contribute to this limited immune activation. Specifically, we asked whether extracellular matrix could alter T cell cytotoxicity against malignant mammary gland carcinoma cells (MCC) in a setup designed to promote maximal T cell efficacy (i.e., rich media with abundant IL2, high ratio of T cells to MCC). We observed that T cell clearance of MCC varied from 0% in collagen 4 or 6 conditions to almost 100% in fibronectin or vitronectin. Transcriptomics revealed that T cell function was defective in MCC/T cell cocultures on collagen 4 (Col4), potentially corresponding to greater expression of cytokines MCC cultured in this environment. In contrast, transcriptomics revealed an effective, exhausted phenotype on vitronectin. The observation that Col4 induces T cell suppression suggests that targeting tumor-ECM interactions may permit new approaches for utilizing immunotherapy in tumors which do not provoke a strong immune response.

Romosozumab, a humanized monoclonal antibody specific for sclerostin (SOST), has been approved for treatment of postmenopausal women with osteoporosis at a high risk for fracture. Previous work in sclerostin global knockout (Sost−/−) mice indicated alterations in immune cell development in the bone marrow (BM), which could be a possible side effect in romosozumab-treated patients. Here, we examined the effects of short-term sclerostin depletion in the BM on hematopoiesis in young mice receiving sclerostin antibody (Scl-Ab) treatment for 6 weeks, and the effects of long-term Sost deficiency on wild-type (WT) long-term hematopoietic stem cells transplanted into older cohorts of Sost−/− mice. Our analyses revealed an increased frequency of granulocytes in the BM of Scl-Ab-treated mice and WT→Sost−/− chimeras, indicating myeloid-biased differentiation in Sost-deficient BM microenvironments. This myeloid bias extended to extramedullary hematopoiesis in the spleen and was correlated with an increase in inflammatory cytokines TNFα, IL-1α, and MCP-1 in Sost−/− BM serum. Additionally, we observed alterations in erythrocyte differentiation in the BM and spleen of Sost−/− mice. Taken together, our current study indicates novel roles for Sost in the regulation of myelopoiesis and control of inflammation in the BM.

Mechanical stimulation is a key regulator of bone mass, maintenance, and turnover. Wnt signaling is a key regulator of mechanotransduction in bone, but the role of β-catenin-an intracellular signaling node in the canonical Wnt pathway-in disuse mechanotransduction is not defined. Using the β-catenin exon 3 flox (constitutively active [CA]) mouse model, in conjunction with a tamoxifen-inducible, osteocyte-selective Cre driver, we evaluated the effects of degradation-resistant β-catenin on bone properties during disuse. We hypothesized that if β-catenin plays an important role in Wnt-mediated osteoprotection, then artificial stabilization of β-catenin in osteocytes would protect the limbs from disuse-induced bone wasting. Two disuse models were tested: tail suspension, which models fluid shift, and botulinum-toxin (botox)-induced muscle paralysis, which models loss of muscle force. Tail suspension was associated with a significant loss of tibial bone mass and density, reduced architectural properties, and decreased bone formation indices in uninduced (control) mice, as assessed by dual-energy X-ray absorptiometry (DXA), micro-computed tomography (µCT), and histomorphometry. Activation of the βcatCA allele in tail-suspended mice resulted in little to no change in those properties; ie, these mice were protected from bone loss. Similar protective effects were observed among botox-treated mice when the βcatCA was activated. RNAseq analysis of altered gene regulation in tail-suspended mice yielded 35 genes, including Wnt11, Gli1, Nell1, Gdf5, and Pgf, which were significantly differentially regulated between tail-suspended β-catenin stabilized mice and tail-suspended nonstabilized mice. Our findings indicate that selectively targeting/blocking of β-catenin degradation in bone cells could have therapeutic implications in mechanically induced bone disease. © 2019 American Society for Bone and Mineral Research.

Lung cancer is the second most diagnosed type of cancer and is the leading cause of cancer-related deaths in both men and women. An estimated 235,760 new cases of lung cancer and 131,880 lung cancer deaths are expected this year accounting for 12% of new cancer cases and 22% of cancer deaths in the United States. Exosomes are secreted vesicles that contain selectively packaged biomaterials (protein, lipids, and RNA) and serve as a form of extracellular communication between cells in the tumor microenvironment. Previous studies have shown the effects of cancer-derived exosomes on specific cell types or gross tumor response in vivo yet, the competitive nature and dynamics of exosomal uptake in the tumor microenvironment remains largely unknown. This work seeks to identify molecular responses induced by cancer-derived exosomes on cells residing in the tumor microenvironment. In order to control tumor cell exposure to cancer-derived exosomes, heterogeneous ex vivo cultures derived from subcutaneous Lewis lung carcinoma (LLC) tumors in C57BL6 mice were exposed to fluorescently dyed LLC exosomes for up to 72 hours. Flow cytometric analysis was performed to identify preferential uptake of cancer exosomes into the stromal subpopulations of tumor cells. Increased uptake was observed throughout the duration of the exposure and preferential uptake was observed into neutrophils, macrophages, and endothelial cells while cancer cells, fibroblasts, and lymphocytes were underrepresented in the exosome uptaken population. Additionally, single cell RNA-sequencing was performed 24 hours post-exosomal exposure to identify transcriptional changes promoted by cancer exosome uptake. We found tumor-derived cancer cells to up-regulate transcripts associated with proliferation and down-regulated genes associated with interferon signaling in response to exosome uptake. These preliminary findings suggest that cancer-derived exosomes have targeted effects on specific cell types in the tumor microenvironment. Specifically in cancer cells, exosomal uptake can elicit protumor (cancer proliferation and immune suppression via decreased interferon signaling) effects that may serve as mediators of disease progression. An understanding of both cancer and host-derived exosomal response to disease progression may identify novel biomarkers and potential therapeutic targets previously undiscovered using canonical discovery methods. This study received funding from LLNL LDRD grant 21-LW-028. This work was conducted under the auspices of the USDOE by LLNL (DE-AC52-07NA27344). LLNL-ABS-829271 Citation Format: Nicholas R. Hum, Nicole F. Leon, Aimy Sebastian, Kelly A. Martin, Gabriela G. Loots. Molecular characterization of the effects of cancer-derived exosomes on murine lung cancer tumors [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 3136.

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.

Osteoarthritis (OA) is a painful and debilitating disease characterized by the chronic and progressive degradation of articular cartilage. Post-traumatic OA (PTOA) is a secondary form of OA that develops in ~50% of cases of severe articular injury. Inflammation and re-occurring injury have been implicated as contributing to the progression of PTOA after the initial injury. However, there is very little known about external factors prior to injury that could affect the risk of PTOA development. To examine how the gut microbiome affects PTOA development we used a chronic antibiotic treatment regimen starting at weaning for six weeks prior to ACL rupture, in mice. A six-weeks post-injury histological examination showed more robust cartilage staining on the antibiotic (AB)-treated mice than the untreated controls (VEH), suggesting slower disease progression in AB cohorts. Injured joints also showed an increase in the presence of anti-inflammatory M2 macrophages in the AB group. Molecularly, the phenotype correlated with a significantly lower expression of inflammatory genes Tlr5, Ccl8, Cxcl13, and Foxo6 in the injured joints of AB-treated animals. Our results indicate that a reduced state of inflammation at the time of injury and a lower expression of Wnt signaling modulatory protein, Rspo1, caused by AB treatment can slow down or improve PTOA outcomes.

Cancer-associated fibroblasts (CAFs) are a prominent stromal cell type in solid tumors and molecules secreted by CAFs play an important role in tumor progression and metastasis. CAFs coexist as heterogeneous populations with potentially different biological functions. Although CAFs are a major component of the breast cancer stroma, molecular and phenotypic heterogeneity of CAFs in breast cancer is poorly understood. In this study, we investigated CAF heterogeneity in triple-negative breast cancer (TNBC) using a syngeneic mouse model, BALB/c-derived 4T1 mammary tumors. Using single-cell RNA sequencing (scRNA-seq), we identified six CAF subpopulations in 4T1 tumors including: 1) myofibroblastic CAFs, enriched for &alpha, smooth muscle actin and several other contractile proteins, 2) &lsquo, inflammatory&rsquo, CAFs with elevated expression of inflammatory cytokines, and 3) a CAF subpopulation expressing major histocompatibility complex (MHC) class II proteins that are generally expressed in antigen-presenting cells. Comparison of 4T1-derived CAFs to CAFs from pancreatic cancer revealed that these three CAF subpopulations exist in both tumor types. Interestingly, cells with inflammatory and MHC class II-expressing CAF profiles were also detected in normal breast/pancreas tissue, suggesting that these phenotypes are not tumor microenvironment-induced. This work enhances our understanding of CAF heterogeneity, and specifically targeting these CAF subpopulations could be an effective therapeutic approach for treating highly aggressive TNBCs.

Preconditioning propels the osteogenic potential of bone marrow aspirate., Cell-derived extracellular matrix (ECM) provides a niche to promote osteogenic differentiation, cell adhesion, survival, and trophic factor secretion. To determine whether osteogenic preconditioning would improve the bone-forming potential of unfractionated bone marrow aspirate (BMA), we perfused cells on ECM-coated scaffolds to generate naïve and preconditioned constructs, respectively. The composition of cells selected from BMA was distinct on each scaffold. Naïve constructs exhibited robust proangiogenic potential in vitro, while preconditioned scaffolds contained more mesenchymal stem/stromal cells (MSCs) and endothelial cells (ECs) and exhibited an osteogenic phenotype. Upon implantation into an orthotopic calvarial defect, BMA-derived ECs were present in vessels in preconditioned implants, resulting in robust perfusion and greater vessel density over the first 14 days compared to naïve implants. After 10 weeks, human ECs and differentiated MSCs were detected in de novo tissues derived from naïve and preconditioned scaffolds. These results demonstrate that bioreactor-based preconditioning augments the bone-forming potential of BMA.

Aging and injury are two major risk factors for osteoarthritis (OA). Yet, very little is known about how aging and injury interact and contribute to OA pathogenesis. In the present study, we examined age- and injury-related molecular changes in mouse knee joints that could contribute to OA. Using RNA-seq, first we profiled the knee joint transcriptome of 10-week-old, 62-week-old, and 95-week-old mice and found that the expression of several inflammatory-response related genes increased as a result of aging, whereas the expression of several genes involved in cartilage metabolism decreased with age. To determine how aging impacts post-traumatic arthritis (PTOA) development, the right knee joints of 10-week-old and 62-week-old mice were injured using a non-invasive tibial compression injury model and injury-induced structural and molecular changes were assessed. At six-week post-injury, 62-week-old mice displayed significantly more cartilage degeneration and osteophyte formation compared with young mice. Although both age groups elicited similar transcriptional responses to injury, 62-week-old mice had higher activation of inflammatory cytokines than 10-week-old mice, whereas cartilage/bone metabolism genes had higher expression in 10-week-old mice, suggesting that the differential expression of these genes might contribute to the differences in PTOA severity observed between these age groups.

Introduction: Emerging evidence suggests that tumor extracellular matrix (ECM) may play a role in tumor-immune interactions. Breast tumors with high immune infiltrates have a distinct ECM profile, and T cell exclusion has been linked to specific ECM signatures. Despite this evidence suggesting a link between immune infiltrates and tumor matrix, it remains unclear whether ECM can directly affect the ultimate step in tumor clearance by the immune system, T cell mediated cytotoxicity. Methods: We compared clearance of 4T1 mammary gland carcinoma cells (MCC) seeded on ECM arrays by T cells isolated from spleens of MHC mismatched strain of mice. Briefly, 4T1 were seeded at 10k/ml for 1 hour, cultured for 24 hours then cocultured with T cells for 2 hours before fixing and staining. For RNA sequencing, ECM proteins (Collagen 1 -Col1, Collagen 4- Col4, Fibronectin -Fn or Vitronectin- Vtn) were coated onto plates at 250ug/ml, then 4t1 were added for 24 hours, then T cells were added for 24 hours followed by RNA isolation and sequencing. Results: We compared number of cells per spot with and without T cells across all ECM combinations and found that co-culture with T cells reduced the average number of MCCs, but this difference did not reach statistical significance. Only in the following conditions did MCC number significantly decrease: Col1 alone, Col6 alone, Fn alone, Vtn alone and Col6+ Eln (Fig 2B). In Col4 containing conditions, MCC cell number increased in the presence of T cells. Intensity of CD274 (PD-L1) and the MHC class 1 protein H2-Kd varied with substrate (p This work was funded by LDRD 19-SI-003 under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under contract DE-AC52-07NA27344. LLNL-ABS-8235222 Citation Format: Claire Robertson, Aimy Sebastian, Aubree Hinckley, Naiomy Rios-Arce, William Hynes, Wei He, Nicholas Hum, Elizabeth Wheeler, Gabriela Loots, Matthew Coleman, Monica Moya. Extracellular matrix modulates T cell clearance of malignant cells in vitro [abstract]. In: Abstracts: AACR Virtual Special Conference: Tumor Immunology and Immunotherapy; 2021 Oct 5-6. Philadelphia (PA): AACR; Cancer Immunol Res 2022;10(1 Suppl):Abstract nr P043.

Wnt16 is a major Wnt ligand involved in the regulation of postnatal bone homeostasis. Previous studies have shown that Wnt16 promotes bone formation and inhibits bone resorption, suggesting that this molecule could be targeted for therapeutic interventions to treat bone thinning disorders such as osteoporosis. However, the molecular mechanisms by which Wnt16 regulates bone metabolism is not yet fully understood. To better understand the molecular mechanisms by which Wnt16 promotes bone formation and to identify the target genes regulated by Wnt16 in osteoblasts, we treated calvarial osteoblasts purified from C57Bl/6 mice with recombinant Wnt16 and profiled the gene expression changes by RNA-seq at 24 h post-treatment. We also compared gene expression profiles of Wnt16-treated osteoblasts to canonical Wnt3a- and non-canonical Wnt5a-treated osteoblasts. This study identified 576 genes differentially expressed in Wnt16-treated osteoblasts compared to sham-treated controls; these included several members of Wnt pathway (Wnt2b, Wnt7b, Wnt11, Axin2, Sfrp2, Sfrp4, Fzd5 etc.) and TGF-β/BMP signaling pathway (Bmp7, Inhba, Inhbb, Tgfb2 etc.). Wnt16 also regulated a large number of genes with known bone phenotypes. We also found that about 37% (215/576) of the Wnt16 targets overlapped with Wnt3a targets and ~15% (86/576) overlapped with Wnt5a targets, suggesting that Wnt16 activates both canonical and non-canonical Wnt signaling targets in osteoblasts. Transcription factor binding motif enrichment analysis in the promoter regions of Wnt16 targets identified noncanonical Wnt/JNK pathway activated transcription factors Fosl2 and Fosl1 as two of the most significantly enriched transcription factors associated with genes activated by Wnt16 while Mef2c was the most significantly enriched transcription factor associated with genes repressed by Wnt16. We also found that a large number of Mef2c targets overlapped with genes down-regulated by Wnt16 and Mef2c itself was transcriptionally repressed by Wnt16 suggesting that Mef2c plays a role in Wnt16-mediated transcriptional regulation.

Osteoarthritis (OA) is a debilitating and painful disease characterized by the progressive loss of articular cartilage. Post‐traumatic osteoarthritis (PTOA) is an injury‐induced type of OA that persists in an asymptomatic phase for years before it becomes diagnosed in ~50% of injured individuals. Although PTOA is not classified as an inflammatory disease, it has been suggested that inflammation could be a major driver of PTOA development. Here we examined whether a state of systemic inflammation induced by lipopolysaccharide (LPS) administration 5‐days before injury would modulate PTOA outcomes. RNA‐seq analysis at 1‐day post‐injury followed by micro‐computed tomography (μCT) and histology characterization at 6 weeks post‐injury revealed that LPS administration causes more severe PTOA phenotypes. These phenotypes included significantly higher loss of cartilage and subchondral bone volume. Gene expression analysis showed that LPS alone induced a large cohort of inflammatory genes previously shown to be elevated in synovial M1 macrophages of rheumatoid arthritis (RA) patients, suggesting that systemic LPS produces synovitis. This synovitis was sufficient to promote PTOA in MRL/MpJ mice, a strain previously shown to be resistant to PTOA. The synovium of LPS‐treated injured joints displayed an increase in cellularity, and immunohistological examination confirmed that this increase was in part attributable to an elevation in type 1 macrophages. LPS induced the expression of Tlr7 and Tlr8 in both injured and uninjured joints, genes known to be elevated in RA. We conclude that inflammation before injury is an important risk factor for the development of PTOA and that correlating patient serum endotoxin levels or their state of systemic inflammation with PTOA progression may help develop new, effective treatments to lower the rate of PTOA in injured individuals. © 2020 The Authors. Journal of Bone and Mineral Research published by American Society for Bone and Mineral Research.

Patients with anterior cruciate ligament (ACL) rupture are two times as likely to develop posttraumatic osteoarthritis (PTOA). Annually, there are ∼900,000 knee injuries in the United States, which account for ∼12% of all osteoarthritis (OA) cases. PTOA leads to reduced physical activity, deconditioning of the musculoskeletal system, and in severe cases requires joint replacement to restore function. Therefore, treatments that would prevent cartilage degradation post-injury would provide attractive alternatives to surgery. Sclerostin (Sost), a Wnt antagonist and a potent negative regulator of bone formation, has recently been implicated in regulating chondrocyte function in OA. To determine whether elevated levels of Sost play a protective role in PTOA, we examined the progression of OA using a noninvasive tibial compression overload model in SOST transgenic (SOSTTG ) and knockout (Sost-/- ) mice. Here we report that SOSTTG mice develop moderate OA and display significantly less advanced PTOA phenotype at 16 weeks post-injury compared with wild-type (WT) controls and Sost-/- . In addition, SOSTTG built ∼50% and ∼65% less osteophyte volume than WT and Sost-/- , respectively. Quantification of metalloproteinase (MMP) activity showed that SOSTTG had ∼2-fold less MMP activation than WT or Sost-/- , and this was supported by a significant reduction in MMP2/3 protein levels, suggesting that elevated levels of SOST inhibit the activity of proteolytic enzymes known to degrade articular cartilage matrix. Furthermore, intra-articular administration of recombinant Sost protein, immediately post-injury, also significantly decreased MMP activity levels relative to PBS-treated controls, and Sost activation in response to injury was TNFα and NF-κB dependent. These results provide in vivo evidence that sclerostin functions as a protective molecule immediately after joint injury to prevent cartilage degradation. © 2018 The Authors. Journal of Bone and Mineral Research Published by Wiley Periodicals Inc.

Sclerosteosis and van Buchem disease (VBD) are two rare autosomal recessive disorders that results from osteoblast hyperactivity, in which progressive bone overgrowth leads to very dense bones, distortion of the face, and entrapment of cranial nerves. Sclerosteosis is caused by loss-of-function mutations in the SOST gene which encodes a secreted glycoprotein, sclerostin. VBD is caused by a noncoding deletion that removes a SOST-specific regulatory element in bone. In bone, SOST is expressed predominantly by osteocytes and sclerostin suppresses bone formation by inhibiting the canonical Wnt signaling pathway. Here we describe how human genetics studies in sclerosteosis and VBD patients, in combination with the generation of transgenic and knockout mice, has led to a better understanding of the role of sclerostin in bone metabolism.

The advances in the development of preclinical models for various cancers have tremendously helped study of the biology and genetics of human cancers as well as for development of therapeutics. Recently, patient-derived organoids (PDOs) have emerged as a robust preclinical platform that can provide insight into the patient specific genetic mechanisms, cancer progression and drug susceptibility. We have developed a novel PDO platform by embedding patient-derived organoids in a 3D hydrogel suspension culture. Our previous studies have shown that, when cultured in hydrogel, spheroids derived from cancer cell lines demonstrated upregulated gene expression signatures in relation to migration and angiogenesis compared to cultures in media, suggesting a more hypoxic, nutrient deficient environment. Given that hypoxia and nutrient deficiency are important feathers of solid tumors, the hydrogel environment could provide a good platform for in vitro study of tumor development and resistance to treatment. In the current study, we embedded PDOs derived from liver metastasis of colorectal cancer into the 3D suspension hydrogel culture. The PDOs adapted well in the hydrogel gel environment. We assessed the response of PDOs in hydrogel to anticancer agents, and compared that to those cultured in media. The PDOs cultured in hydrogel showed significantly elevated resistance to the treatments. The IC50s of chemotherapeutic drugs 5-fluorouracil and oxaliplatin are increased by ~5-10 fold when cultured in hydrogel compared to those in media. Further studies through RNAseq analysis revealed differentially activated signaling pathways. In particular, the levels of the CXC ligand family chemokines are significantly up-regulated in the PDOs cultured in the hydrogel. The CXC ligand family chemokines are important immune stimulants that are known to play key role in the chemotaxis and tumor recruitment of immune cells including neutrophil, T-cell and B-cells. Interestingly, the elevated levels of CXC-ligands have been shown to relate to resistance of colorectal cancer against drug treatment such as 5-fluorouracil. Our hydrogel model could help elucidate the mechanisms behind such resistance. Future study will focus on evaluating how well the hydrogel PDO platform can recapitulate tumor microenvironment and its potential in screening for personalized medicine. Citation Format: He Wei, Eveliina Karelehto, Karen Dubbin, Aimy Sebastian, Robert Warren, Monica Moya, Gaby Loots, Elizabeth Wheeler, Matthew Coleman. Developing 3d hydrogel model for patient-derived organoids of metastatic colorectal cancer [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 2638.

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.