Role of the androgen receptor in breast cancer and preclinical analysis of enzalutamide.

INTRODUCTION: The androgen receptor (AR) is widely expressed in breast cancers and has been proposed as a therapeutic target in estrogen receptor alpha (ER) negative breast cancers that retain AR. However, controversy exists regarding the role of AR, particularly in ER + tumors. Enzalutamide, an AR inhibitor that impairs nuclear localization of AR, was used to elucidate the role of AR in preclinical models of ER positive and negative breast cancer. METHODS: We examined nuclear AR to ER protein ratios in primary breast cancers in relation to response to endocrine therapy. The effects of AR inhibition with enzalutamide were examined in vitro and in preclinical models of ER positive and negative breast cancer that express AR. RESULTS: In a cohort of 192 women with ER + breast cancers, a high ratio of AR:ER (≥2.0) indicated an over four fold increased risk for failure while on tamoxifen (HR = 4.43). The AR:ER ratio had an independent effect on risk for failure above ER % staining alone. AR:ER ratio is also an independent predictor of disease-free survival (HR = 4.04, 95% CI: 1.68, 9.69; p = 0.002) and disease specific survival (HR = 2.75, 95% CI: 1.11, 6.86; p = 0.03). Both enzalutamide and bicalutamide inhibited 5-alpha-dihydrotestosterone (DHT)-mediated proliferation of breast cancer lines in vitro; however, enzalutamide uniquely inhibited estradiol (E2)-mediated proliferation of ER+/AR + breast cancer cells. In MCF7 xenografts (ER+/AR+) enzalutamide inhibited E2-driven tumor growth as effectively as tamoxifen by decreasing proliferation. Enzalutamide also inhibited DHT- driven tumor growth in both ER positive (MCF7) and negative (MDA-MB-453) xenografts, but did so by increasing apoptosis. CONCLUSIONS: AR to ER ratio may influence breast cancer response to traditional endocrine therapy. Enzalutamide elicits different effects on E2-mediated breast cancer cell proliferation than bicalutamide. This preclinical study supports the initiation of clinical studies evaluating enzalutamide for treatment of AR+ tumors regardless of ER status, since it blocks both androgen- and estrogen- mediated tumor growth.

P38alpha-selective mitogen-activated protein kinase inhibitor for improvement of cultured human islet recovery.

OBJECTIVES: We investigated whether the recovery of cultured human islets is improved through the addition of a p38alpha-selective mitogen-activated protein kinase inhibitor, SD-282, to clinically used serum-free culture medium. METHODS: Immediately after isolation, islets were cultured for 24 hours in medium alone (control) or medium containing dimethyl sulfoxide, 0.1 microM SD-282, or 0.3 microM SD-282. Cytokine expression, apoptotic beta-cell percentage, and islet function were assessed postculture. RESULTS: Expression of p38 and phosphorylated p38 in islets increased during culture. Interleukin 6 mRNA expression in cultured islets, as well as IL-6, IL-8, and granulocyte-macrophage colony-stimulating factor released into the medium, was significantly reduced by adding SD-282. The apoptotic beta-cell percentage was significantly lower in islets cultured with 0.1 microM SD-282, but not 0.3 microM, as compared with the control. Stimulation indices measured in vitro were higher but without significance (P = 0.06); the function of transplanted islets in diabetic NOD-scid mice was also better in 0.1-microM SD-282 group as compared with control. CONCLUSIONS: Better islet function was obtained by adding 0.1 microM SD-282 to the serum-free culture medium. This improvement was associated with suppression of cytokine production and prevention of beta-cell apoptosis. However, this beneficial effect was diminished at a higher concentration.

Topical alpha-selective p38 MAP kinase inhibition reduces acute skin inflammation in guinea pig.

Certain skin pathologies, including psoriasis, are thought to be immune-mediated inflammatory diseases. Available literature clearly indicates the involvement of inflammatory cells (neutrophils, T cells, and macrophages), their cytokines, and the p38 mitogen-activated protein kinase (MAPK) signaling pathway in the pathophysiology of psoriasis. Neutrophils play an important role in the formation of acute inflammatory changes in psoriasis. Acute inflammation or acute flares in psoriasis remain poorly addressed in clinical medicine. In this communication, we first establish a simple and reproducible model for studying neutrophil-mediated acute skin inflammation. Using the hairless guinea pig, due to the similarity of skin architecture to that of human, acute inflammation was induced with an intradermal injection of 50 µg/mL lipopolysaccharide (LPS) in 50 µL solution. Myeloperoxidase (MPO) activity was measured by MPO-positive neutrophils and shown to increase for 24-hours post-injection. Simultaneously, the level of phosphorylated p38 MAPK was documented for 48-hours post-LPS injection in the skin. Next, we used this model to examine the therapeutic potential of an α-selective p38 MAPK inhibitor, SCIO-469. A comparison of topical application of SCIO-469 at 5 mg/mL or 15 mg/mL to vehicle revealed that SCIO-469 dose-dependently reduces acute skin inflammation and that this effect is statistically significant at the higher dose. Further examination of tissues that received this dose also revealed statistically significant reduction of MPO activity, phosphorylated p38 MAPK, interleukin-6, and cyclooxygenase-2. These data suggest that the α-selective p38 MAPK inhibitor, SCIO-469, acts as a topical anti-inflammatory agent via the p38 MAPK pathway to reduce neutrophil induced acute inflammation in the skin. These observations suggest that α-selective p38 MAPK inhibition may be an effective therapeutic strategy to manage acute skin inflammation.

Analgesic effects of p38 kinase inhibitor treatment on bone fracture healing.

Traditional and COX-2 selective non-steroidal anti-inflammatory drug (NSAID) treatment inhibits fracture healing in animal models. This indicates that either the inflammatory phase following a bone fracture is necessary for efficient or sufficient bone regeneration to heal the fracture or COX-2 may have a specific function during bone regeneration unrelated to inflammation. These observations also indicate that NSAID use during fracture healing may be contra-indicated. Thus, identification of different analgesics for fracture pain or other orthopaedic surgical procedures would be of significant clinical benefit. Inhibitors of p38 kinase also have significant analgesic properties. However, p38 kinase is a critical regulator of inflammation. To assess the potential use of p38 kinase inhibition as a therapeutic strategy to manage fracture pain, the analgesic properties of SCIO-469, a p38alpha kinase inhibitor, were assessed in a rat fracture model and compared to other common analgesics. In addition, the effects of SCIO-469 treatment on ultimate fracture healing outcomes were measured by radiography and torsional mechanical testing. The data indicate that SCIO-469 was an effective analgesic. No adverse events related to fracture healing were observed in rats treated with SCIO-469. Immunohistochemistry showed that p38 kinase is activated primarily in the first days following a fracture. These observations suggest that p38alpha kinase inhibition may be an effective therapeutic strategy to manage orthopaedic-related pain. These observations also indicate that COX-2 has a specific function during bone regeneration other than promoting inflammation.

p38 MAPK inhibition reduces diabetes-induced impairment of wound healing.

In healthy tissue, a wound initiates an inflammatory response characterized by the presence of a hematoma, infiltration of inflammatory cells into the wound and, eventually, wound healing. In pathological conditions like diabetes mellitus, wound healing is impaired by the presence of chronic nonresolving inflammation. p38 mitogen-activated protein kinase (MAPK) inhibitors have demonstrated anti-inflammatory effects, primarily by inhibiting the expression of inflammatory cytokines and regulating cellular traffic into wounds. The db/db mouse model of type 2 diabetes was used to characterize the time course of expression of activated p38 during impaired wound healing. The p38α-selective inhibitor, SCIO-469, was applied topically and effects on p38 activation and on wound healing were evaluated. A topical dressing used clinically, Promogran™, was used as a comparator. In this study, we established that p38 is phosphorylated on Days 1 to 7 post-wounding in db/db mice. Further, we demonstrated that SCIO-469, at a dose of 10 µg/wound, had a positive effect on wound contraction, granulation tissue formation, and re-epithelialization, and also increased wound maturity during healing. These effects were similar to or greater than those observed with Promogran™. These results suggest a novel approach to prophylactic and therapeutic management of chronic wounds associated with diabetes or other conditions in which healing is impaired.

Role of p38 mitogen-activated protein kinase in ozone-induced airway hyperresponsiveness and inflammation.

Ozone is a potent oxidant and causes airway hyperresponsiveness and neutrophilia. To determine the role of p38 mitogen-activated protein kinase (MAPK) activation, we studied the effect of a p38alpha inhibitor SD-282 (Scios Inc, Fremont, CA USA) on ozone-induced airway hyperresponsiveness and neutrophilia. Balb/c mice received SD-282 (30 or 90 mg/kg i.p) or vehicle 1 h before exposure to either ozone (3 ppm, 3 h) or air. Three hours after exposure, lungs were analysed for cytokine levels and bronchoalveolar lavage was performed. Another set of mice were dosed 6 h after exposure and 1 h before assessing airway hyperresponsiveness. SD-282 (90 mg/kg) significantly inhibited ozone-induced airway hyperresponsiveness (-LogPC(150): SD-282: -1.73+/-0.14 vs. vehicle: -0.99+/-0.15, P<0.05). Bronchoalveolar lavage neutrophil numbers were time-dependently increased in vehicle-dosed, ozone-exposed mice, greatest at 20-24 h after exposure. SD-282 (30 and 90 mg/kg) significantly inhibited ozone induced neutrophil numbers at 3 h and 20-24 h after ozone SD-282 significantly inhibited ozone-induced increases in phosphorylated p38 MAPK expression, and in cyclooxygenase-2 (COX-2), interleukin-6 (IL-6) and IL-1beta but not MIP-1alpha gene expression. We conclude that p38 MAPK is involved in ozone-induced airway hyperresponsiveness and lung neutrophilia. Inhibition of p38 MAPK with small molecule kinase inhibitors may be a means of reducing ozone-induced inflammation and airway hyperresponsiveness.

Transforming growth factor-beta blockade down-regulates the renin-angiotensin system and modifies cardiac remodeling after myocardial infarction.

After myocardial infarction (MI), the heart may undergo progressive ventricular remodeling, resulting in a deterioration of cardiac function. TGF-beta is a key cytokine that both initiates and terminates tissue repair, and its sustained production underlies the development of tissue fibrosis, particularly after MI. We investigated the effects of a novel orally active specific inhibitor of the TGF-beta receptor 1 (SD-208) in an experimental model of MI. Mice underwent ligation of the left coronary artery to induce MI and were subsequently treated for 30 d after infarction with either SD-208 or a vehicle control. Blockade of TGF-beta signaling reduced mean arterial pressure in all groups. SD-208 treatment after MI resulted in a trend for reduced ventricular and renal gene expression of TGF-beta-activated kinase-1 (a downstream modulator of TGF-beta signaling) and a significant decrease in collagen 1, in association with a marked decrease in cardiac mass. Post-MI SD-208 treatment significantly reduced circulating levels of plasma renin activity as well as down-regulating the components of the cardiac and renal renin-angiotensin system (angiotensinogen, angiotensin converting enzyme, and angiotensin II type I receptor). Our findings indicate that blockade of the TGF-beta signaling pathway results in significant amelioration of deleterious cardiac remodeling after infarction.

Role of p38 mitogen activated protein kinase in a model of osteosarcoma-induced pain.

The focus of this work was to examine the potential role of p38 mitogen activated protein kinase (p38) in a mouse model of bone cancer (osteosarcoma) pain. To generate osteosarcoma and sham animals, osteosarcoma cells or medium were injected into the medullary canal of the femur. Initially, ipsilateral tactile allodynia was observed in both groups, but by 12 days post-surgery, thresholds in the sham group returned towards baseline while hypersensitivity in the osteosarcoma group lasted throughout the study. An increase in phosphorylated p38 was detected by western blotting in dorsal root ganglia (DRG) and spinal cord day 14 after surgery. Immunohistochemistry showed that p38 was phosphorylated in DRG and spinal dorsal horn neurons at this time point. Two doses of a selective p38 inhibitor, SCIO-469, were administered in the chow starting 5 days post-surgery and continued throughout the study. Treatment with SCIO-469 led to a decrease in osteosarcoma-induced clinical score but had no effect on the allodynia. Bone erosion and tumor growth were also examined but no significant reduction of bone erosion or tumor growth was observed in the SCIO-469 treated mice. These data suggest that the p38 signaling pathway does not play a major role in bone cancer-mediated pain.

Inhibition of the TGF-beta receptor I kinase promotes hematopoiesis in MDS.

MDS is characterized by ineffective hematopoiesis that leads to peripheral cytopenias. Development of effective treatments has been impeded by limited insight into pathogenic pathways governing dysplastic growth of hematopoietic progenitors. We demonstrate that smad2, a downstream mediator of transforming growth factor-beta (TGF-beta) receptor I kinase (TBRI) activation, is constitutively activated in MDS bone marrow (BM) precursors and is overexpressed in gene expression profiles of MDS CD34(+) cells, providing direct evidence of overactivation of TGF-beta pathway in this disease. Suppression of the TGF-beta signaling by lentiviral shRNA-mediated down-regulation of TBRI leads to in vitro enhancement of hematopoiesis in MDS progenitors. Pharmacologic inhibition of TBRI (alk5) kinase by a small molecule inhibitor, SD-208, inhibits smad2 activation in hematopoietic progenitors, suppresses TGF-beta-mediated gene activation in BM stromal cells, and reverses TGF-beta-mediated cell-cycle arrest in BM CD34(+) cells. Furthermore, SD-208 treatment alleviates anemia and stimulates hematopoiesis in vivo in a novel murine model of bone marrow failure generated by constitutive hepatic expression of TGF-beta1. Moreover, in vitro pharmacologic inhibition of TBRI kinase leads to enhancement of hematopoiesis in varied morphologic MDS subtypes. These data directly implicate TGF-beta signaling in the pathobiology of ineffective hematopoiesis and identify TBRI as a potential therapeutic target in low-risk MDS.

Pharmacological properties of SD-282 - an alpha-isoform selective inhibitor for p38 MAP kinase.

The effects of small-molecule p38 inhibitors in numerous models of different disease states have been published, including those of SD-282, an indole-5-carboxamide inhibitor. The aim of the present study was to evaluate the pharmacological activity of SD-282 on cytokine production in vitro as well as in 2 in vivo models of inflammation in order to illuminate the role of this particular inhibitor in diverse disease states. The results presented here provide further characterization of SD-282 and provide a context in which to interpret the activity of this p38 inhibitor in models of arthritis, pain, myocardial injury, sepsis and asthma; all of which have an inflammatory component. SD-282 represents a valuable tool to elucidate the role of p38 MAP kinase in multiple models of inflammation.

p38alpha-selective MAP kinase inhibitor reduces tumor growth in mouse xenograft models of multiple myeloma.

Multiple myeloma (MM) is a clonal plasma cell malignancy, which is currently incurable. Therefore, new mono- or combined therapy treatment regimens in the early and advanced phases of MM are urgently needed to combat this disease. Recently, p38 mitogen-activated protein kinase (MAPK) has been implicated as playing an important role in MM. Therefore, the effect of a p38alpha-selective MAPK inhibitor, SCIO-469 (indole-5-carboxamide, ATP-competitive inhibitor), or its structural analog, SD-282 (indole-5-carboxamide, ATP-competitive inhibitor) was examined in mouse xenograft models of MM using human RPMI-8226 or H-929 plasmacytoma inocula. Oral treatment with SCIO-469 (10, 30, 90 mg/kg) twice daily was initiated in mice with palpable tumors of RPMI-8226 origin, a condition that mimics early human myeloma disease. In mice with palpable tumors, 14 days of SCIO-469 treatment significantly reduced RPMI-8226 tumor growth in a dose-dependent manner. A significant dose-dependent reduction in RPMI-8226 tumor growth was also observed when SCIO-469 oral treatment at doses of 10, 30 and 90 mg/kg twice daily was initiated in mice with tumors of pronounced size, a condition that mimics advanced human myeloma disease. In a similar set of studies employing the SCIO-469 analogue SD-282 at 90 mg/kg/bid orally, histological assessment at the end of the study demonstrated a significant reduction in RPMI-8226 tumor growth and angiogenesis. SD-282 treatment was additionally shown to significantly reduced expression of heat-shock protein-27 (HSP-27) and phospho-p38 in the tumor cells. Furthermore, co-administration of SCIO-469 with dexamethasone elicited antitumor properties in dexamethasone-sensitive H-929 tumors at much lower than the typically effective doses of dexamethasone, suggesting its potential for combined therapy. In conclusion, p38 inhibitors reduced human myeloma cell growth in vivo both at early and advanced phases of the disease. The current study also provides evidence of potential for co-therapy with dexamethasone.

Selective p38α mitogen-activated protein kinase inhibitor attenuates lung inflammation and fibrosis in IL-13 transgenic mouse model of asthma.

p38 Mitogen-activated protein kinase (MAPK) plays a critical role in the activation of inflammatory cells. We investigated the anti-inflammatory effects of a p38α-selective MAPK inhibitor (SD-282) in a mouse transgenic (CC10:IL-13) asthma model. The CC-10-driven over-expression of IL-13 in the mouse lung/airway has been shown to result in a remarkable phenotype recatitulating many features of asthma and characterized by eosinophilic and mononuclear inflammation, with airway epithelial cell hypertrophy, mucus cell metaplasia, the hyperproduction of neutral and acidic mucus, the deposition of Charcot-Leyden-like crystal, and airway sub-epitheilial fibrosis. Here we show how activated p38 MAPK can be observed in the lungs at the onset of asthma ie, around 8 weeks of age in both female and male mice. We also show that administration of a p38α MAPK selective inhibitor, SD-282 at 30 or 90 mg/kg, twice a day for a period of four weeks beginning at the onset of asthma, significantly reduced the inflammation (p < 0.001); hyperplasia of airway epithelium (p < 0.05); goblet cell metaplasia and mucus hypersecretion (p < 0.001) and reduced lung remodeling and fibrosis (p < 0.01), alleviating the severity of lung damage as measured by a composite score (p < 0.05). Furthermore, SD-282 significantly reduced activated p38 MAPK in the lymphocytes and epithelial cells (p < 0.001). Simultaneously, identical studies were conducted with an anti-fibrotic TGFßR1 kinase inhibitor (SD-208) which demonstrated anti-fibrotic but not anti-inflammatory properties. These findings suggest that the p38α-selective MAPK inhibitor may have dual therapeutic potential in attenuating both the inflammatory component and the fibrotic component of asthma and other Th2-polarized inflammatory lung diseases.

p38alpha-selective mitogen-activated protein kinase inhibitor SD-282 reduces inflammation in a subchronic model of tobacco smoke-induced airway inflammation.

Chronic obstructive pulmonary disease (COPD) is characterized by pulmonary inflammation, which is relatively insensitive to inhaled corticosteroids. The extent of the pulmonary inflammation in COPD correlates with disease severity, and it is thought to play a significant role in disease progression. We have evaluated a selective p38alpha-selective mitogen-activated protein kinase (MAPK) inhibitor, indole-5-carboxamide (ATP-competitive inhibitor of p38 kinase) (SD-282), in an 11-day model of tobacco smoke (TS)-induced pulmonary inflammation in A/J mice, by using dexamethasone as a reference steroid. Two oral treatment paradigms were evaluated in this TS model: prophylactic with daily pretreatment before each daily exposure, and therapeutic with daily treatment for 6 days commencing after 5 days of smoke exposure. Bronchoalveolar lavage and histological evaluation of lung sections taken after exposure to TS revealed an inflammatory response composed of increased numbers of macrophages and neutrophils and enhanced mucin staining. Phospho-p38 staining in macrophages and type II epithelial cells after TS exposure was also observed. Given prophylactically or therapeutically, dexamethasone failed to inhibit any of the TS-induced inflammatory changes. By contrast, SD-282 inhibited TS-induced increases in macrophages and neutrophils. Furthermore, SD 282 reduced TS-induced increases in cyclooxygenase-2 and interleukin-6 levels, and phospho-p38 expression in the lungs. In conclusion, SD-282 markedly reduced TS-induced inflammatory responses when given prophylactically or therapeutically whereas dexamethasone was ineffective. This is the first evidence that a p38alpha-selective MAPK inhibitor can exert pulmonary anti-inflammatory activity in a TS exposure model when given in a therapeutic mode, establishing the potential of p38 MAPK inhibitors as a therapy for COPD.

A p38 mitogen-activated protein kinase inhibitor arrests active alveolar bone loss in a rat periodontitis model.

BACKGROUND: Gram-negative bacterial species, such as Actinobacillus actinomycetemcomitans, contain lipopolysaccharide (LPS) that initiates the innate immune system, resulting in inflammatory alveolar bone loss. LPS activates Toll-like receptors on membrane surfaces, stimulating many intracellular signaling cascades, including the p38 mitogen-activated protein kinase (MAPK). Activation of p38 signaling mediates inflammatory cytokine expression, contributing toward osteoclastogenesis and bone loss. The aim of this study was to determine whether the novel, orally active p38 MAPK inhibitor SD282 could arrest progression of LPS-induced alveolar bone destruction in rats. METHODS: Three groups of female Sprague-Dawley rats received LPS injections to the palatal molar gingiva three times per week for 4 weeks to establish periodontitis. From weeks 5 through 8, two groups received the drug SD282 (N = 14) or 1% polyethylene glycol drug vehicle (N = 14) via oral gavage in addition to LPS injections. The third group continued to receive only LPS injections (N = 8). Microcomputed tomography was used to measure volumetric alveolar bone loss, expressed as bone volume fraction (BVF). Expression of interleukin (IL)-1 and -6 and tumor necrosis factor-alpha (TNF-alpha) was assessed by immunohistochemistry, and osteoclasts were enumerated by tartrate-resistant acid phosphatase staining. RESULTS: By 4 weeks, severe alveolar bone resorption was seen in LPS-injected animals. Administration of SD282 significantly blocked additional volumetric bone loss in the LPS-only versus LPS + SD282 groups (0.37 +/- 0.01 BVF versus 0.43 +/- 0.01 BVF; P < 0.01). Significant reductions in IL-1beta (P < 0.01 ), TNF-alpha (P < 0.05), and osteoclast formation (P < 0.01) occurred in the presence of SD282. CONCLUSIONS: An orally active p38 MAPK inhibitor reduced LPS-induced inflammatory cytokine expression, osteoclastogenesis, and alveolar bone loss in rats. Within the limits of the current study, SD282 arrested periodontal disease progression, thus highlighting the therapeutic potential of this novel class of inhibitors.

Inhibition of transforming growth factor beta signaling reduces pancreatic adenocarcinoma growth and invasiveness.

Transforming growth factor beta (TGFbeta) is a pleiotropic factor that regulates cell proliferation, angiogenesis, metastasis, and immune suppression. Dysregulation of the TGFbeta pathway in tumor cells often leads to resistance to the antiproliferative effects of TGFbeta while supporting other cellular processes that promote tumor invasiveness and growth. In the present study, SD-208, a 2,4-disubstituted pteridine, ATP-competitive inhibitor of the TGFbeta receptor I kinase (TGFbetaRI), was used to inhibit cellular activities and tumor progression of PANC-1, a human pancreatic tumor line. SD-208 blocked TGFbeta-dependent Smad2 phosphorylation and expression of TGFbeta-inducible proteins in cell culture. cDNA microarray analysis and functional gene clustering identified groups of TGFbeta-regulated genes involved in metastasis, angiogenesis, cell proliferation, survival, and apoptosis. These gene responses were inhibited by SD-208. Using a Boyden chamber motility assay, we demonstrated that SD-208 inhibited TGFbeta-stimulated invasion in vitro. An orthotopic xenograft mouse model revealed that SD-208 reduced primary tumor growth and decreased the incidence of metastasis in vivo. Our findings suggest mechanisms through which TGFbeta signaling may promote tumor progression in pancreatic adenocarcinoma. Moreover, they suggest that inhibition of TGFbetaRI with a small-molecule inhibitor may be effective as a therapeutic approach to treat human pancreatic cancer.

A p38alpha selective mitogen-activated protein kinase inhibitor prevents periodontal bone loss.

In the oral microbial environment, Gram-negative bacterial derived lipopolysaccharide (LPS) can initiate inflammatory bone loss as seen in periodontal diseases. p38 Mitogen-activated protein kinase (MAPK) signaling is critical to inflammatory cytokine and LPS-induced cytokine expression, which may contribute toward periodontal bone loss. The purpose of this proof-of-principle study was to evaluate the ability of an orally active p38alpha MAPK inhibitor (SD-282) to reduce periopathogenic LPS-induced alveolar bone loss in an experimental rat model. Five groups of Sprague-Dawley rats received one of the following treatments: LPS injected to the palatal gingiva adjacent to the maxillary molars three times per week for 8 weeks, LPS plus two doses of SD-282 (15 or 45 mg/kg) twice daily by oral gavage, or control groups given drug vehicle (1% polyethylene glycol) or SD-282 (45 mg/kg) only. Baseline and 8-week alveolar bone loss was assessed by microcomputed tomography (microCT) and histological examination. LPS induced severe bone loss over this time period, whereas control groups were unchanged from baseline measurements. Both doses of SD-282 showed significant protection from LPS-induced bone loss. Bone area and volumetric analysis of maxillas by microCT indicated significant loss of bone volume with LPS treatment, which was blocked with the p38 inhibitor. Histological examination indicated significantly fewer tartate-resistant acid phosphatase-positive osteoclasts and a significant decrease in interleukin (IL)-6, IL-1beta, and tumor necrosis factor alpha expression in p38 inhibitor-treated groups compared with LPS groups by immunostaining. Results from this in vivo study suggest that orally active p38 MAPK inhibitors can reduce LPS-induced inflammatory cytokine production and osteoclast formation and protect against LPS-stimulated alveolar bone loss.

Antitumor activity of TGF-beta inhibitor is dependent on the microenvironment.

Pancreatic cancer is one of the deadliest forms of cancer and effective treatment remains a clinical challenge. Transforming growth factor-beta (TGF-beta) has important roles in primary tumor progression and in promoting metastasis, and has become an attractive target for therapy. Previously, we reported that treatment of pancreatic cancer cells in vitro with SD-208, a small molecule inhibitor of the TGF-beta receptor I kinase (TGF-betaRI), inhibited expression of genes associated with tumor progression and inhibited invasiveness in a cell-based assay. In a demonstration of efficacy of TGF-beta signaling inhibition in an in vivo model of pancreatic cancer, we showed significantly reduced primary tumor weight and decreased incidence of metastasis in the Panc-1 orthotopic xenograft model of established pancreatic cancer. In this report, we extend these in vivo findings to examine the mechanistic consequences of TGF-betaRI inhibition on Panc-1 primary tumors and their microenvironment in situ. In a longitudinal study of TGF-betaRI inhibition in the Panc-1 orthotopic model, we show that SD-208 treatment significantly reduced tumor growth measured as bioluminescence intensity throughout the study. Histological evaluation revealed that SD-208 treatment reduced proliferation and induced apoptosis in the primary tumors, and reduced fibrosis in the tumor microenvironment. An immune contribution (greater B-cell infiltration in SD-208-treated tumors) was also suggested by the histological analyses. SD-208 not only blocked direct TGF-beta signaling in Panc-1 primary tumors (reduced phospho SMAD2/3), but also down-regulated the expression of TGF-beta-regulated genes (PAI-1 and COL7A1). Taken together, our results indicate that a TGF-betaRI kinase inhibitor has a potential therapeutic benefit for pancreatic cancer patients.

Effect of transforming growth factor-beta receptor I kinase inhibitor 2,4-disubstituted pteridine (SD-208) in chronic allergic airway inflammation and remodeling.

Transforming growth factor (TGF)-beta is a multifunctional regulator of cell growth and differentiation with both pro- and anti-inflammatory properties. We used an inhibitor of TGF-beta receptor I (TGF-betaRI) kinase, SD-208 (2,4-disubstituted pteridine, a ATP-competitive inhibitor of TGF-betaRI kinase), to determine the role of TGF-beta in airway allergic inflammation and remodeling. Brown-Norway rats sensitized and repeatedly exposed to ovalbumin (OVA) aerosol challenge were orally administered SD-208 twice daily, before each of six OVA exposures to determine the preventive effects, or only before each of the last three of six OVA exposures to investigate its reversal effects. SD-208 (60 mg/kg) reversed bronchial hyperresponsiveness (BHR) induced by repeated allergen exposure, but it did not prevent it. SD-208 prevented changes in serum total and OVA-specific IgE, but it did not reverse them. SD-208 had both a preventive and reversal effect on airway inflammation as measured by major basic protein-positive eosinophils and CD2(+) T-cell counts in mucosal airways, cell proliferation measured by 5-bromo-2'-deoxyuridine expression in airway smooth muscle (ASM) cells and epithelial cells, and goblet cell hyperplasia induced by repeated allergen challenges. There was a significant decrease in intracellular Smad2/3 expression. SD-208 did not significantly decrease the increased ASM thickness induced by allergen exposure. These findings support a proinflammatory and proremodeling role for TGF-beta in allergic airway inflammation. Inhibition of TGF-betaRI kinase activities by SD-208 may be a useful approach to the reversal of BHR and to the prevention and reversal of inflammatory and remodeling features of chronic asthma.

LDL and cAMP cooperate to regulate the functional expression of the LRP in rat ovarian granulosa cells.

Rat ovarian granulosa rely heavily on lipoprotein-derived cholesterol for steroidogenesis, which is principally supplied by the LDL receptor- and scavenger receptor class B type I (SR-BI)-mediated pathways. In this study, we characterized the hormonal and cholesterol regulation of another member of the LDL receptor superfamily, low density lipoprotein receptor-related protein (LRP), and its role in granulosa cell steroidogenesis. Coincubation of cultured granulosa cells with LDL and N6,O2'-dibutyryl adenosine 3',5'-cyclic monophosphate (Bt2cAMP) greatly increased the mRNA/protein levels of LRP. Bt2cAMP and Bt2cAMP plus human hLDL also enhanced SR-BI mRNA levels. However, there was no change in the expression of receptor-associated protein, a chaperone for LRP, or another lipoprotein receptor, LRP8/apoER2, in response to Bt2cAMP plus hLDL, whereas the mRNA expression of LDL receptor was reduced significantly. The induced LRP was fully functional, mediating increased uptake of its ligand, alpha2-macroglobulin. The level of binding of another LRP ligand, chylomicron remnants, did not increase, although the extent of remnant degradation that could be attributed to the LRP doubled in cells with increased levels of LRP. The addition of lipoprotein-type LRP ligands such as chylomicron remnants and VLDL to the incubation medium significantly increased the progestin production under both basal and stimulated conditions. In summary, our studies demonstrate a role for LRP in lipoprotein-supported ovarian granulosa cell steroidogenesis.

Importance of p38 mitogen-activated protein kinase pathway in allergic airway remodelling and bronchial hyperresponsiveness.

p38 mitogen-activated protein kinase (MAPK) plays an important role in the activation of inflammatory cells and in the proliferation of airway structural cells. We investigated the role of p38 MAPK by using a selective inhibitor of p38 alpha and beta isoforms, SD282, in a chronic model of 15 ovalbumin exposures in sensitised mice using two doses (30 and 90 mg/kg). Allergen exposure induced bronchial hyperresponsiveness to methacholine as measured by the concentration of methacholine needed to increase pulmonary resistance by 200% (PC200), eosinophilia in bronchoalveolar lavage fluid and increase in airway smooth muscle area and goblet cell hyperplasia. In addition, p38 MAPK activity as measured by phosphorylated p38 expression on Western blots was increased after allergen challenge, which was suppressed by SD282 at both doses. SD282 inhibited bronchial hyperresponsiveness, but had no effect on eosinophils in bronchoalveolar lavage fluid. It also reduced airway smooth muscle and goblet cell hyperplasia, but had no effect on serum immunoglobulin E. p38 MAPK is involved in the pathogenesis of bronchial hyperresponsiveness but not in eosinophilic inflammation or the allergic response; however, remodelling features such as airway smooth muscle or goblet cell hyperplasia are regulated through p38 MAPK. Furthermore, bronchial hyperresponsiveness induced by chronic allergen exposure may be related to the development of airway wall remodelling.