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The negative health consequences of acute ultraviolet (UV) exposure are evident, with reports of 30,000 emergency room visits annually to treat the effects of sunburn in the United States alone. The acute effects of sunburn include erythema, edema, severe pain, and chronic overexposure to UV radiation, leading to skin cancer. Whereas the pain associated with the acute effects of sunburn may be relieved by current interventions, existing post-sunburn treatments are not capable of reversing the cumulative and long-term pathological effects of UV exposure, an unmet clinical need. Here we show that activation of the vascular endothelial growth factor (VEGF) pathway is a direct and immediate consequence of acute UV exposure, and activation of VEGF signaling is necessary for initiating the acute pathological effects of sunburn. In UV-exposed human subjects, VEGF signaling is activated within hours. Topical delivery of VEGF pathway inhibitors, targeted against the ligand VEGF-A (gold nanoparticles conjugated with anti-VEGF antibodies) and small-molecule antagonists of VEGF receptor signaling, prevent the development of erythema and edema in UV-exposed mice. These findings collectively suggest targeting VEGF signaling may reduce the subsequent inflammation and pathology associated with UV-induced skin damage, revealing a new postexposure therapeutic window to potentially inhibit the known detrimental effects of UV on human skin. It is essential to emphasize that these preclinical studies must not be construed as suggesting in any way the use of VEGF inhibitors as a sunburn treatment in humans because warranted future clinical studies and appropriate agency approval are essential in that regard.

While molecular targeted therapies have improved prognoses of advanced stage lung adenocarcinoma expressing oncogenic driver mutations, acquired therapeutic resistance continues to be a major problem. Epidermal growth factor receptor (EGFR) activating mutations are among the most common targetable genetic alterations in lung adenocarcinoma, and EGFR tyrosine kinase inhibitors (TKIs) are recommended first-line therapy for EGFR mutation positive cancer patients. Unfortunately, most patients develop resistance to EGFR TKIs and rapid disease progression occurs. A better mechanistic understanding of therapy refractory cancer progression is necessary to develop new therapeutic approaches to predict and prevent acquired resistance to EGFR TKIs. Here, we identify a new mechanism of ERBB3-mediated resistance to EGFR TKIs in human lung adenocarcinoma. Specifically, we show that dopamine and cyclic AMP-regulated phosphoprotein, Mr 32000 (DARPP-32) physically recruits ERBB3 to EGFR to mediate a switch from EGFR homodimers to EGFR:ERBB3 heterodimers to bypass EGFR TKI-mediated inhibition to potentiate ERBB3-dependent activation of oncogenic AKT and ERK signaling that drives therapy refractory tumor cell survival. In a cohort of paired tumor specimens derived from 30 lung adenocarcinoma patients before and after the development of EGFR TKI refractory disease progression, we reveal that DARPP-32 as well as kinase-activated EGFR and ERBB3 proteins are overexpressed upon acquired EGFR TKI resistance. In vivo studies suggest that ablation of DARPP-32 protein activity sensitizes gefitinib-resistant lung tumor xenografts to EGFR TKI treatment, while DARPP-32 overexpression increases gefitinib-refractory lung cancer progression in gefitinib-sensitive lung tumors orthotopically xenografted into mice. Taken together, our findings introduce a DARPP-32-mediated, ERBB3-dependent mechanism used by lung tumor cells to evade EGFR TKI-induced cell death, potentially paving the way for the development of new therapies to prevent or overcome therapy-refractory lung adenocarcinoma progression.

Background There is a need to develop novel therapies which could be beneficial to patients with prostate cancer (CaP) including those who are predisposed to poor outcome, such as African-Americans. This study investigates the role of ROBO1-pathway in predicting outcome and race-based disparity in patients with CaP. Methods and results Aided by RNA sequencing-based DECIPHER-testing and immunohistochemical (IHC) analysis of tumors we show that ROBO1 is lost during the progressive stages of CaP, a prevalent feature in African-Americans. We show that the loss of ROBO1 predicts high-risk of recurrence, metastasis and poor outcome of androgen-deprivation therapy in radical prostatectomy-treated patients. These data identified an aggressive ROBO1deficient /DOCK1+ve sub-class of CaP. Combined genetic and IHC data showed that ROBO1 loss is accompanied by DOCK1/Rac1 elevation in grade-III/IV primary-tumors and Mets. We observed that the hypermethylation of ROBO1-promoter contributes to loss of expression that is highly prevalent in African-Americans. Because of limitations in restoring ROBO1 function, we asked if targeting the DOCK1 could be an ideal strategy to inhibit progression or treat ROBO1deficient metastatic-CaP. We tested the pharmacological efficacy of CPYPP, a selective inhibitor of DOCK1 under in vitro and in vivo conditions. Using ROBO1-ve and ROBO1+ve CaP models, we determined the median effective concentration of CPYPP for growth. DOCK1-inhibitor treatment significantly decreased the (a) Rac1-GTP/β-catenin activity, (b) transmigration of ROBO1deficient cells across endothelial lining, and (c) metastatic spread of ROBO1deficient cells through the vasculature of transgenicfl Zebrafish model. Conclusion We suggest that ROBO1 status forms as predictive biomarker of outcome in high-risk populations such as African-Americans and DOCK1-targeting therapy has a clinical potential for treating metastatic-CaP.

Background Small cell lung cancer (SCLC) is the most aggressive form of lung cancer, and new molecular insights are necessary for prognostic and therapeutic advances. Methods Dopamine and cAMP-regulated phosphoprotein, Mr 32000 (DARPP-32) and its N-terminally truncated splice variant, t-DARPP, were stably overexpressed or ablated in human DMS-53 and H1048 SCLC cells. Functional assays and immunoblotting were used to assess how DARPP-32 isoforms regulate SCLC cell growth, proliferation, and apoptosis. DARPP-32-modulated SCLC cells were orthotopically injected into the lungs of SCID mice to evaluate how DARPP-32 and t-DARPP regulate neuroendocrine tumour growth. Immunostaining for DARPP-32 proteins was performed in SCLC patient-derived specimens. Bioinformatics analysis and subsequent transcription assays were used to determine the mechanistic basis of DARPP-32-regulated SCLC growth. Results We demonstrate in mice that DARPP-32 and t-DARPP promote SCLC growth through increased Akt/Erk-mediated proliferation and anti-apoptotic signalling. DARPP-32 isoforms are overexpressed in SCLC patient-derived tumour tissue, but undetectable in physiologically normal lung. Achaete-scute homologue 1 (ASCL1) transcriptionally activates DARPP-32 isoforms in human SCLC cells. Conclusions We reveal new regulatory mechanisms of SCLC oncogenesis that suggest DARPP-32 isoforms may represent a negative prognostic indicator for SCLC and serve as a potential target for the development of new therapies.

Summary Vascular endothelial cell growth factor (VEGF) is a key regulator of vascular permeability. Herein we aim to understand how acute and chronic exposures of VEGF induce different levels of vascular permeability. We demonstrate that chronic VEGF exposure leads to decreased phosphorylation of VEGFR2 and c-Src as well as steady increases of nitric oxide (NO) as compared to that of acute exposure. Utilizing heat-inducible VEGF transgenic zebrafish (Danio rerio) and establishing an algorithm incorporating segmentation techniques for quantification, we monitored acute and chronic VEGF-induced vascular hyperpermeability in real time. Importantly, dimethylarginine dimethylaminohydrolase-1 (DDAH1), an enzyme essential for NO generation, was shown to play essential roles in both acute and chronic vascular permeability in cultured human cells, zebrafish model, and Miles assay. Taken together, our data reveal acute and chronic VEGF exposures induce divergent signaling pathways and identify DDAH1 as a critical player and potentially a therapeutic target of vascular hyperpermeability-mediated pathogenesis., Graphical abstract, Highlights • Chronic VEGF exposure induces a different signaling pattern in endothelial cells • A novel algorithm can precisely quantify the vascular permeability in zebrafish model • DDAH1 acts as a novel mediator of VEGF-induced vascular hyperpermeability, Cardiovascular medicine; Molecular genetics

Exitron splicing (EIS) creates a cryptic intron (called an exitron) within a protein-coding exon to increase proteome diversity. EIS is poorly characterized, but emerging evidence suggests a role for EIS in cancer. Through a systematic investigation of EIS across 33 cancers from 9,599 tumor transcriptomes, we discovered that EIS affected 63% of human coding genes and that 95% of those events were tumor specific. Notably, we observed a mutually exclusive pattern between EIS and somatic mutations in their affected genes. Functionally, we discovered that EIS altered known and novel cancer driver genes for causing gain- or loss-of-function, which promotes tumor progression. Importantly, we identified EIS-derived neoepitopes that bind to major histocompatibility complex (MHC) class I or II. Analysis of clinical data from a clear cell renal cell carcinoma cohort revealed an association between EIS-derived neoantigen load and checkpoint inhibitor response. Our findings establish the importance of considering EIS alterations when nominating cancer driver events and neoantigens.

Small cell lung cancer (SCLC) is the most aggressive form of lung cancer, and new molecular insights are necessary for prognostic and therapeutic advances. Here we demonstrate in orthotopic mouse models that dopamine and cAMP-regulated phosphoprotein, Mr 32000 (DARPP-32) and its N-terminally truncated splice variant t-DARPP promote SCLC growth through increased proliferation, Akt/Erk-mediated survival and anti-apoptotic signaling. DARPP-32 and t-DARPP proteins are overexpressed in SCLC patient-derived tumor tissue, but virtually undetectable in physiologically normal lung. RNA sequencing analysis reveals a subset of SCLC patients with high tumoral t-DARPP expression and upregulated Notch signaling genes, including achaete-scute homologue 1 (ASCL1). We show that DARPP-32 isoforms are transcriptionally activated by ASCL1 in human SCLC cells. Taken together, we demonstrate new regulatory mechanisms of SCLC oncogenesis that suggest DARPP-32 isoforms may represent a negative prognostic indicator for SCLC and serve as a potential target for the development of new therapies.

Lung cancer is the leading cause of cancer death among both men and women in the United States. Small cell lung cancer (SCLC) results in over 30,000 deaths of Americans annually and comprises 15-17% incidences of lung cancer. SCLC is the most aggressive form of lung cancer due to its rapid doubling time and early widespread metastasis. Most SCLC patients present with advanced disease, respond to initial systemic chemotherapy, and then treatment refractory progression usually occurs within one year due to acquired drug resistance. Consequently, the median survival time of SCLC patients is only 9 to 20 months and merely 7% of SCLC patients survive beyond five years. A better molecular understanding of SCLC is necessary to develop much needed new treatment strategies. For the first time, we demonstrate that dopamine and cAMP-regulated phosphoprotein, Mr 32000 (DARPP-32) and its splice variant t-DARPP stimulate tumors of neuroendocrine origin, and we show DARPP-32 proteins are aberrantly overexpressed in human SCLC. Upregulation of t-DARPP protein in a subset of SCLC patients positively correlates with overexpression of genes associated with Notch signaling, including achaete-scute homologue 1 (ASCL1). We reveal that DARPP-32 isoforms are transcriptionally activated by ASCL1 in human SCLC cells. To determine whether DARPP-32 drives SCLC growth in vivo, we utilized an orthotopic lung cancer xenograft mouse model. Mice challenged with DARPP-32-ablated DMS-53 cells show a substantial decrease in lung tumor growth relative to controls. Correspondingly, we demonstrate increased tumor growth in mice harboring lung tumors formed by administration of DMS-53 or H1048 cells overexpressing DARPP-32 and t-DARPP proteins. Mechanistically, we describe how DARPP-32 isoforms promote SCLC growth through increased proliferation, Akt/Erk-mediated survival, and anti-apoptotic signaling. Taken together, we define new regulatory mechanisms of SCLC oncogenesis that suggest DARPP-32 isoforms may represent a negative prognostic indicator for SCLC and serve as a potential target for the development of new therapies. Citation Format: Sk. Kayum Alam, Li Wang, Yanan Ren, Christina E. Hernandez, Farhad Kosari, Anja C. Roden, Rendong Yang, Luke H. Hoeppner. New molecular mechanisms of small cell lung cancer growth [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 5956.

Purpose: Metastasis is the major cause of mortality in prostate cancer patients. Factors such as genetic makeup and race play critical role in the outcome of therapies. This study was conducted to investigate the relevance of BMI1 in metastatic prostate cancer disease in Caucasian and African-Americans. Experimental Design: We employed race-specific prostate cancer models, clinical specimens, clinical data mining, gene-microarray, transcription-reporter assay, chromatin-immunoprecipitation (ChIP), IHC, transgenic-(tgfl/fl) zebrafish, and mouse metastasis models. Results: BMI1 expression was observed to be elevated in metastatic tumors (lymph nodes, lungs, bones, liver) of Caucasian and African-American prostate cancer patients. The comparative analysis of stage III/IV tumors showed an increased BMI1 expression in African-Americans than Caucasians. TCGA and NIH/GEO clinical data corroborated to our findings. We show that BMI1 expression (i) positively correlates to metastatic (MYC, VEGF, cyclin D1) and (ii) negative correlates to tumor suppressor (INKF4A/p16, PTEN) levels in tumors. The correlation was prominent in African-American tumors. We show that BMI1 regulates the transcriptional activation of MYC, VEGF, INKF4A/p16, and PTEN. We show the effect of pharmacological inhibition of BMI1 on the metastatic genome and invasiveness of tumor cells. Next, we show the anti-metastatic efficacy of BMI1-inhibitor in transgenic zebrafish and mouse metastasis models. Docetaxel as monotherapy has poor outcome on the growth of metastatic tumors. BMI1 inhibitor as an adjuvant improved the taxane therapy in race-based in vitro and in vivo models. Conclusions: BMI1, a major driver of metastasis, represents a promising therapeutic target for treating advanced prostate cancer in patients (including those belonging to high-risk group).

Lung cancer is the leading cause of cancer-related death worldwide. Here we demonstrate that elevated expression of dopamine and cyclic adenosine monophosphate-regulated phosphoprotein, Mr 32000 (DARPP-32), and its truncated splice variant t-DARPP promote lung tumor growth, while abrogation of DARPP-32 expression in human non-small-cell lung cancer (NSCLC) cells reduces tumor growth in orthotopic mouse models. We observe a physical interaction between DARPP-32 and inhibitory kappa B kinase-α (IKKα) that promotes NSCLC cell migration through non-canonical nuclear factor kappa-light-chain-enhancer of activated B cells 2 (NF-κB2) signaling. Bioinformatics analysis of 513 lung adenocarcinoma patients reveals that elevated t-DARPP isoform expression is associated with poor overall survival. Histopathological investigation of 62 human lung adenocarcinoma tissues also shows that t-DARPP expression is elevated with increasing tumor (T) stage. Our data suggest that DARPP-32 isoforms serve as a negative prognostic marker associated with increasing stages of NSCLC and may represent a novel therapeutic target. Sk. Kayum Alam et al. show that DARPP-32 isoforms, mediators of dopamine signaling, promote lung tumor growth through non-canonical NF-κB signaling. This study suggests a possibility of using DARPP-32 isoforms as a prognostic marker for lung cancer.

Objective— Neuropilin-1 (NRP-1) is a multidomain membrane receptor involved in angiogenesis and development of neuronal circuits, however, the role of NRP-1 in cardiovascular pathophysiology remains elusive. Approach and Results— In this study, we first observed that deletion of NRP-1 induced peroxisome proliferator–activated receptor γ coactivator 1α in cardiomyocytes and vascular smooth muscle cells, which was accompanied by dysregulated cardiac mitochondrial accumulation and induction of cardiac hypertrophy- and stress-related markers. To investigate the role of NRP-1 in vivo, we generated mice lacking Nrp-1 in cardiomyocytes and vascular smooth muscle cells (SM22-α- Nrp-1 KO), which exhibited decreased survival rates, developed cardiomyopathy, and aggravated ischemia-induced heart failure. Mechanistically, we found that NRP-1 specifically controls peroxisome proliferator–activated receptor γ coactivator 1 α and peroxisome proliferator–activated receptor γ in cardiomyocytes through crosstalk with Notch1 and Smad2 signaling pathways, respectively. Moreover, SM22-α- Nrp-1 KO mice exhibited impaired physical activities and altered metabolite levels in serum, liver, and adipose tissues, as demonstrated by global metabolic profiling analysis. Conclusions— Our findings provide new insights into the cardioprotective role of NRP-1 and its influence on global metabolism.

Lung cancer is the leading cause of cancer-related death worldwide. In this study, we demonstrate that elevated expression of dopamine and cyclic adenosine monophosphate-regulated phosphoprotein, Mr 32000 (DARPP-32) and its truncated splice variant t-DARPP promotes lung tumor growth, while abrogation of DARPP-32 expression in human non-small cell lung cancer (NSCLC) cells reduces tumor growth in orthotopic mouse models. We observe a novel physical interaction between DARPP-32 and inhibitory kappa B kinase-α (IKKα) that promotes NSCLC cell migration through non-canonical nuclear factor kappa-light-chain-enhancer of activated B cells 2 (NF-κB2) signaling. Bioinformatics analysis of 513 lung adenocarcinoma patients reveals elevated t-DARPP isoform expression is associated with poor overall survival. Histopathological investigation of 62 human lung adenocarcinoma tissues also showed that t-DARPP expression is elevated with increasing tumor (T) stage. Our data suggest that DARPP-32 is a negative prognostic marker associated with increasing stages of NSCLC and may represent a novel therapeutic target.

Zebrafish have proven to be a valuable model to study human cancer biology with the ultimate aim of developing new therapies. Danio rerio are amenable to in vivo imaging, high-throughput drug screening, mutagenesis, and transgenesis, and they share histological and genetic similarities with Homo sapiens. The significance of zebrafish in the field of precision oncology is rapidly emerging. Indeed, modeling cancer in zebrafish has already been used to identify tumor biomarkers, define therapeutic targets and provide an in vivo platform for drug discovery. New zebrafish studies are starting to pave the way to direct individualized clinical applications. Patient-derived cancer cell xenograft models have demonstrated the feasibility of using zebrafish as a real-time avatar of prognosis and drug response to identify the most ideal therapy for an individual patient. Genetic cancer modeling in zebrafish, now facilitated by rapidly evolving genome editing techniques, represents another innovative approach to recapitulate human oncogenesis and develop individualized treatments. Utilizing zebrafish to design customizable precision therapies will improve the clinical outcome of patients afflicted with cancer.

We sought to determine whether Dopamine D2 Receptor (D2R) agonists inhibit lung tumor progression and identify subpopulations of lung cancer patients that benefit most from D2R agonist therapy. We demonstrate D2R agonists abrogate lung tumor progression in syngeneic (LLC1) and human xenograft (A549) orthotopic murine models through inhibition of tumor angiogenesis and reduction of tumor infiltrating myeloid derived suppressor cells. Pathological examination of human lung cancer tissue revealed a positive correlation between endothelial D2R expression and tumor stage. Lung cancer patients with a smoking history exhibited greater levels of D2R in lung endothelium. Our results suggest D2R agonists may represent a promising individualized therapy for lung cancer patients with high levels of endothelial D2R expression and a smoking history.

Lung cancer is the deadliest and most frequently diagnosed type of tumor worldwide, with 1.6 million deaths reported annually. Non-small cell lung cancer (NSCLC) represents 85% of all lung cancer cases and carries a poor 5-year survival rate below 15%. Prognoses remain dismal due to the large number of patients diagnosed with advanced stage disease and the development of resistance to current therapies. A better understanding of acquired drug resistance will help to circumvent the progression of lung cancer and make significant strides in improving NSCLC patient treatment. Our recent work demonstrates that dopamine and cAMP-regulated phosphoprotein, Mr 32000 (DARPP-32) and its amino-terminally truncated splice variant (t-DARPP) promote lung tumor growth in orthotopic mouse models. IHC staining of 62 human lung adenocarcinoma tissues showed that t-DARPP expression is elevated with increasing tumor (T) staging score, which represents the size of the primary tumor and whether it has grown into nearby areas, as a metric of tumor progression and growth. Correspondingly, a computational biology analysis of 513 lung adenocarcinoma patients revealed upregulation of t-DARPP isoform expression correlates with advanced T stage and is associated with poor overall survival. We identified a novel physical interaction between DARPP-32 and inhibitory kappa B kinase-α (IKKα) that promotes NSCLC cell migration through activation of non-canonical NF-κB2 signaling. It has been shown that DARPP-32 overexpression inhibits gefitinib-induced apoptosis in gastric cancer and t-DARPP contributes to the trastuzumab resistance phenotype in breast cancer. Our recent findings suggest DARPP-32 and t-DARPP overexpression in NSCLC promotes resistance to specific molecular targeted inhibitors by enabling tumor cells to evade apoptosis via Akt- and Erk-dependent cell survival mechanisms. Current ongoing studies are focused on manipulating expression of DARPP-32 isoforms in lung tumor cells to prevent resistance to targeted therapies in NSCLC patients. Citation Format: SK Kayum Alam, Matteo Astone, Ping Liu, Li Wang, Abbygail M. Coyle, Erin N. Dankert, Dane K. Hoffman, Stephanie R. Hall, Wei Zhang, Rui Kuang, Anja C. Roden, Aaron S. Mansfield, Luke H. Hoeppner. Molecular mechanisms of non-small cell lung cancer growth and 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 873.

Metastasis, the leading cause of cancer death, requires tumor cell intravasation, migration through the bloodstream, arrest within capillaries, and extravasation to invade distant tissues. Few mechanistic details have been reported thus far regarding the extravasation process or re-entry of circulating tumor cells at metastatic sites. Here, we show that neuropilin-2 (NRP-2), a multifunctional nonkinase receptor for semaphorins, vascular endothelial growth factor (VEGF), and other growth factors, expressed on cancer cells interacts with α5 integrin on endothelial cells to mediate vascular extravasation and metastasis in zebrafish and murine xenograft models of clear cell renal cell carcinoma (RCC) and pancreatic adenocarcinoma. In tissue from patients with RCC, NRP-2 expression is positively correlated with tumor grade and is highest in metastatic tumors. In a prospectively acquired cohort of patients with pancreatic cancer, high NRP-2 expression cosegregated with poor prognosis. Through biochemical approaches as well as Atomic Force Microscopy (AFM), we describe a unique mechanism through which NRP-2 expressed on cancer cells interacts with α5 integrin on endothelial cells to mediate vascular adhesion and extravasation. Taken together, our studies reveal a clinically significant role of NRP-2 in cancer cell extravasation and promotion of metastasis. Cancer Res; 73(14); 4579–90. ©2013 AACR.

Lung cancer is the leading cause of cancer-related death worldwide. In this study, we demonstrate that elevated expression of dopamine and cyclic adenosine monophosphate-regulated phosphoprotein, Mr 32000 (DARPP-32) and its truncated splice variant t-DARPP promotes lung tumor growth, while abrogation of DARPP-32 expression in human non-small cell lung cancer (NSCLC) cells reduces tumor growth in orthotopic mouse models. We observe a novel physical interaction between DARPP-32 and inhibitory kappa B kinase-α (IKKα) that promotes NSCLC cell migration through non-canonical nuclear factor kappa-light-chain-enhancer of activated B cells 2 (NF-κB2) signaling. Bioinformatics analysis of 513 lung adenocarcinoma patients reveals elevated t-DARPP isoform expression is associated with poor overall survival. Histopathological investigation of 62 human lung adenocarcinoma tissues also showed that t-DARPP expression is elevated with increasing tumor (T) stage. Our data suggest that DARPP-32 is a negative prognostic marker associated with increasing stages of NSCLC and may represent a novel therapeutic target. Citation Format: Sk. Kayum Alam, Matteo Astone, Ping Liu, Stephanie R. Hall, Abbygail M. Coyle, Erin N. Dankert, Dane K. Hoffman, Wei Zhang, Rui Kuang, Anja C. Roden, Aaron S. Mansfield, Luke H. Hoeppner. DARPP-32 and t-DARPP promote non-small cell lung cancer growth through regulation of IKKα-dependent cell migration and Akt/Erk-mediated cell survival [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 5161.

Bone is one of the few tissues in the body with the capacity to regenerate and repair itself. In most cases, fractures are completely repaired in a relatively short period of time; however, in a small percentage of cases, healing never occurs and non-union is the result. Fracture repair and bone regeneration require the localized re-activation of signaling cascades that are crucial for skeletal development. The Wnt/β-catenin signaling pathway is one such developmental pathway whose role in bone formation and regeneration has been recently appreciated. During the last decade, much has learned about how Wnt pathways regulate bone mass. Small molecules and biologics aimed at this pathway are now being tested as potential new anabolic agents. Here we review recent data demonstrating that Wnt pathways are active during fracture repair and that increasing the activities of Wnt pathway components accelerates bone regeneration.

Background: There is a need to develop new bone anabolic agents because current bone regeneration regimens have limitations. The Wingless-type MMTV integration site (Wnt) pathway has emerged as a regulator of bone formation and regeneration. Objective: To review the molecular basis for Wnt pathway modulation and discuss strategies that target it and improve bone mass. Methods: Data in peer-reviewed reports and meeting abstracts are discussed. Results/conclusions: Neutralizing inhibitors of Wnt signaling have emerged as promising strategies. Small-molecule inhibitors of glycogen synthase kinase 3β increase bone mass, lower adiposity and reduce fracture risk. Neutralizing antibodies to Dickkopf 1, secreted Frizzled-related protein 1 and sclerostin produce similar outcomes in animal models. These drugs are exciting breakthroughs but are not without risks. The challenges include tissue-specific targeting and consequently, long-term safety.

Tumor metastasis refers to spread of a tumor from site of its origin to distant organs and causes majority of cancer deaths. Although >30 metastasis suppressor genes (MSGs) that negatively regulate metastasis have been identified so far, two issues are poorly understood: first, which MSGs oppose metastasis in a tumor type, and second, which molecular function of MSG controls metastasis. Herein, integrative analyses of tumor-transcriptomes (n = 382), survival data (n = 530) and lymph node metastases (n = 100) in lung cancer patients identified non-metastatic 2 (NME2) as a key MSG from a pool of >30 metastasis suppressors. Subsequently, we generated a promoter-wide binding map for NME2 using chromatin immunoprecipitation with promoter microarrays (ChIP-chip), and transcriptome profiling. We discovered novel targets of NME2 which are involved in focal adhesion signaling. Importantly, we detected binding of NME2 in promoter of focal adhesion factor, vinculin. Reduced expression of NME2 led to enhanced transcription of vinculin. In comparison, NME1, a close homolog of NME2, did not bind to vinculin promoter nor regulate its expression. In line, enhanced metastasis of NME2-depleted lung cancer cells was found in zebrafish and nude mice tumor models. The metastatic potential of NME2-depleted cells was remarkably diminished upon selective RNA-i-mediated silencing of vinculin. Together, we demonstrate that reduced NME2 levels lead to transcriptional de-repression of vinculin and regulate lung cancer metastasis.

Purpose Glucocorticoids, such as prednisone, hydrocortisone, and dexamethasone, are known to produce some clinical benefit for patients with hormone-refractory prostate cancer (HRPC). However, the underlying mechanisms by which glucocorticoids affect HRPC growth are not well established as yet. Here, we hypothesize that the therapeutic effect of glucocorticoids on HRPC can be attributed to a direct inhibition of angiogenesis through the glucocorticoid receptor by down-regulating two major angiogenic factors, vascular endothelial growth factor (VEGF) and interleukin-8 (IL-8). Experimental Design The effects of dexamethasone on VEGF and IL-8 expression and cell proliferation were examined using DU145, which expresses glucocorticoid receptor. The effects of dexamethasone on DU145 xenografts were determined by analyzing VEGF and IL-8 gene expression, microvessel density, and tumor volume. Results Dexamethasone significantly down-regulated VEGF and IL-8 gene expression by 50% (P Conclusion Glucocorticoids suppressed androgen-independent prostate cancer growth possibly due to the inhibition of tumor-associated angiogenesis by decreasing VEGF and IL-8 production directly through glucocorticoid receptor in vivo.

Despite the initial efficacy of androgen deprivation therapy, most patients with advanced prostate cancer eventually progress to hormone-refractory prostate cancer, for which there is no curative therapy. Previous studies from our laboratory and others have shown the antiproliferative and proapoptotic effects of 3,3′-diindolylmethane (DIM) in prostate cancer cells. However, the molecular mechanism of action of DIM has not been investigated in androgen receptor (AR)-positive hormone-responsive and -nonresponsive prostate cancer cells. Therefore, we investigated the effects of B-DIM, a formulated DIM with greater bioavailability, on AR, Akt, and nuclear factor κB (NF-κB) signaling in hormone-sensitive LNCaP (AR+) and hormone-insensitive C4-2B (AR+) prostate cancer cells. We found that B-DIM significantly inhibited cell proliferation and induced apoptosis in both cell lines. By Akt gene transfection, reverse transcription-PCR, Western blot analysis, and electrophoretic mobility shift assay, we found a potential crosstalk between Akt, NF-κB, and AR. Importantly, B-DIM significantly inhibited Akt activation, NF-κB DNA binding activity, AR phosphorylation, and the expressions of AR and prostate-specific antigen, suggesting that B-DIM could interrupt the crosstalk. Confocal studies revealed that B-DIM inhibited AR nuclear translocation, leading to the down-regulation of AR target genes. Moreover, B-DIM significantly inhibited C4-2B cell growth in a severe combined immunodeficiency-human model of experimental prostate cancer bone metastasis. These results suggest that B-DIM-induced cell proliferation inhibition and apoptosis induction are partly mediated through the down-regulation of AR, Akt, and NF-κB signaling. These observations provide a rationale for devising novel therapeutic approaches for the treatment of hormone-sensitive, but more importantly, hormone-refractory prostate cancer by using B-DIM alone or in combination with other therapeutics.

Background After development of hormone-refractory metastatic disease, prostate cancer is incurable. The recent history of chemotherapy has shown that with difficult disease targets, combinatorial therapy frequently offers the best chance of a cure. In this study we have examined the effects of a combination of zoledronic acid (ZOL), a new-generation bisphosphonate, and docetaxel on LuCaP 23.1, a prostate cancer xenograft that stimulates the osteoblastic reaction when grown in the bone environment. Methods Intra-tibial injections of LuCaP 23.1 cells were used to generate tumors in the bone environment, and animals were treated with ZOL, docetaxel, or a combination of these. Effects on bone and tumor were evaluated by measurements of bone mineral density and histomorphometrical analysis. Results ZOL decreased proliferation of LuCaP 23.1 in the bone environment, while docetaxel at a dose that effectively inhibited growth of subcutaneous tumors did not show any effects in the bone environment. The combination of the drugs significantly inhibited the growth of LuCaP 23.1 tumors in the bone. Conclusion In conclusion, the use of the osteolysis-inhibitory agent ZOL in combination with docetaxel inhibits growth of prostate tumors in bone and represents a potential treatment option.