Concurrent PEDF deficiency and Kras mutation induce invasive pancreatic cancer and adipose-rich stroma in mice

BACKGROUND AND AIMS

Pigment epithelium-derived factor (PEDF), a non-inhibitory SERPIN with potent antiangiogenic activity, has been recently implicated in metabolism and adipogenesis, both of which are known to influence pancreatic cancer progression. Increased pancreatic fat in human pancreatic tumour correlates with greater tumour dissemination while PEDF deficiency in mice promotes pancreatic hyperplasia and visceral obesity. Oncogenic Ras, the most common mutation in pancreatic ductal adenocarcinoma (PDAC), has similarly been shown to promote adipogenesis and premalignant lesions.

METHODS

In order to determine whether concurrent loss of PEDF is sufficient to promote adipogenesis and tumorigenesis in the pancreas, the authors ablated PEDF in an EL-Kras(G12D) mouse model of non-invasive cystic papillary neoplasms.

RESULTS

EL-Kras(G12D)/PEDF deficient mice developed invasive PDAC associated with enhanced matrix metalloproteinase (MMP)-2 and MMP-9 expression and increased peripancreatic fat with adipocyte hypertrophy and intrapancreatic adipocyte infiltration (pancreatic steatosis). In support of increased adipogenesis, the stroma of the pancreas of EL-Kras(G12D)/PEDF deficient mice demonstrated higher tissue levels of two lipid droplet associated proteins, tail-interacting protein 47 (TIP47, perilipin 3) and adipose differentiation-related protein (ADRP, Pperilipin 2), while adipose triglyceride lipase, a key factor in lipolysis, was decreased. In patients with PDAC, both tissue and serum levels of PEDF were decreased, stromal TIP47 expression was higher and the tissue VEGF to PEDF ratio was increased (p<0.05).

CONCLUSIONS

These data highlight the importance of lipid metabolism in the tumour microenvironment and identify PEDF as a critical negative regulator of both adiposity and tumour invasion in the pancreas.

Activated hepatic stellate cells: negative regulators of hepatocyte proliferation in liver diseases

Tissue homeostasis requires an effective, limited wound-healing response to injury. In chronic disease, failure to regenerate parenchymal tissue leads to the replacement of lost cellular mass with a fibrotic matrix. The mechanisms that dictate the balance of cell regeneration and fibrogenesis are not well understood. Here we report that fibrogenic hepatic stellate cells (HSCs) in the liver are negative regulators of hepatocyte regeneration. This negative regulatory function requires stimulation of the 5-hydroxytryptamine 2B receptor (5-HT_2B) on HSCs by serotonin, which activates expression of transforming growth factor β1 (TGF-β1), a powerful suppressor of hepatocyte proliferation, through signaling by mitogen-activated protein kinase 1 (ERK) and the transcription factor JunD. Selective antagonism of 5-HT_2B enhanced hepatocyte growth in models of acute and chronic liver injury. We also observed similar effects in mice lacking 5-HT_2B or JunD or upon selective depletion of HSCs in wild-type mice. Antagonism of 5-HT_2B attenuated fibrogenesis and improved liver function in disease models in which fibrosis was pre-established and progressive. Pharmacological targeting of 5-HT_2B is clinically safe in humans and may be therapeutic in chronic liver disease.

Fabrication of uniform and high resolution copper nanowire using intermediate self-assembled monolayers through direct AFM lithography

Electrochemical AFM lithography was used to directly fabricate copper nanowires. The copper ions were strongly reduced by a negative sample bias at the point where the AFM tip was localized, and copper metal wires were successfully fabricated following the direction of the electrical field of the bias. A TDA⋅HCl self-assembled monolayer (SAM) was found to play an important role as an intermediate layer for enhancing the capability of high resolution and complete development after the AFM lithographic process. The physical and electrical properties of the wires were analyzed by AFM, EFM, SEM, TEM and I-V measurement. The fabricated copper has promising potential for applications such as masks and interconnectors for nanoelectronic devices.

Analgesic properties of loperamide differ following systemic and local administration to rats after spinal nerve injury

BACKGROUND

The analgesic properties and mechanisms of loperamide hydrochloride, a peripherally acting opioid receptor agonist, in neuropathic pain warrant further investigation.

METHODS

We examined the effects of systemic or local administration of loperamide on heat and mechanical hyperalgesia in rats after an L5 spinal nerve ligation (SNL).

RESULTS

 (1) Systemic loperamide (0.3-10 mg/kg, subcutaneous in the back) dose dependently reversed heat hyperalgesia in SNL rats, but did not produce thermal analgesia. Systemic loperamide (3 mg/kg) did not induce thermal antinociception in naïve rats; (2) systemic loperamide-induced anti-heat hyperalgesia was blocked by pretreatment with intraperitoneal naloxone methiodide (5 mg/kg), but not by intraperitoneal naltrindole (5 mg/kg) or intrathecal naltrexone (20 μg/10 μL); (3) local administration of loperamide (150 μg), but not vehicle, into plantar or dorsal hind paw tissue induced thermal analgesia in SNL rats and thermal antinociception in naïve rats; (4) the analgesic effect of intraplantar loperamide (150 μg/15 μL) in SNL rats at 45 min, but not 10 min, post-injection was blocked by pretreatment with an intraplantar injection of naltrexone (75 μg/10 μL); (5) systemic (3.0 mg/kg) and local (150 μg) loperamide reduced the exaggerated duration of hind paw elevation to noxious pinprick stimuli in SNL rats. Intraplantar injection of loperamide also decreased the frequency of pinprick-evoked response in naïve rats.

CONCLUSIONS

These findings suggest that both systemic and local administration of loperamide induce an opioid receptor-dependent inhibition of heat and mechanical hyperalgesia in nerve-injured rats, but that local paw administration of loperamide also induces thermal and mechanical antinociception.

P5-19-05: Age-Related Changes in the Pharmacokinetics (pK), Response, and Toxicity of Weekly nab-Paclitaxel in Patients with Metastatic Breast Cancer (MBC)

Background: Although cancer is a disease of aging, few studies have evaluated the association between patient age and the pK or pharmacodynamics (pD) of cancer therapeutics. The goals of this study were 1) to evaluate the age-related changes in the pK and pD of weekly nab-paclitaxel in patients with MBC; 2) to determine response rate; and 3) to explore the relationship of age with pK and pD parameters (i.e., dose reductions, dose delays and grade ≥ 3 toxicities). Patients and Methods: Forty patients with MBC, receiving 1st or 2nd line chemotherapy, entered an IRB approved protocol to evaluate the age-related changes in the pK of weekly nab-paclitaxel administered at 100 mg/m2 IV for 3 weeks followed by a 1-week break. Patients were accrued from 4 age strata &lt;50, 50–60, 60–70, and &gt;70 years of age. Blood samples were collected for pK analysis with the first dose of nab-paclitaxel. Response was assessed every 2 cycles. Toxicity was graded using the NCI Common Toxicity Criteria for Adverse Events (v 3.0) and was adjudicated as attributable to nab-paclitaxel if it was possibly, probably, or definitely related. Linear regression analysis was used to examine the strength of the relationship between patient age and natural logarithm of 24 hour area under the curve (AUC). Two-sided two-sample t-tests were used to assess if there was a difference in mean age based on the presence of pD variables (i.e., dose reductions, dose delays and grade ≥ 3 toxicities). The significance level was set to 0.05.

Results: Of the 40 patients who entered the study, 39 (98%) were evaluable with a mean age of 60 (SD=13.4; min=30; max=81). Patients were accrued in the following age cohorts: &lt;50 (n= 10; 26%), 50–60 (n= 5; 13%), 60–70 (n= 15; 38%), and &gt;70 (n= 9; 23%) years of age. The median number of courses completed was 4 (min=1, max=21). The response rate was: 0% (n=0) CR, 31% (n=12) PR, 38% (n=15) SD. Grade 3 toxicity was experienced by 26% (n=10). We observed 8% (n=3) grade 3 hematological toxicities [neutrophils (n=1; 3%), leukocytes (n=2; 5%)] and 18% (n=7) grade 3 non-hematological toxicities [nausea and hypophosphatemia (n=1; 3%), diarrhea and infection without neutropenia (n=1; 3%), fatigue (n=2; 5%), hyponatremia (n=1; 3%), and infections without neutropenia (n=2; 5%)]. There were no cases of grade 4 or 5 toxicity. Grade 2 sensory neuropathy was experienced by 8% (n=3; no cases in the 70+ age cohort). Dose reductions or course delays were experienced by 62% (n=24) and 21% (n=8), respectively. There was a borderline significant positive association between age and natural logarithm of total nab-paclitaxel 24 hour AUC (coef=.01; se=.006; p=0.055; n=36). There were no differences in the mean ages based on the presence of grade 3 or higher toxicity (p =0.75), need for dose reductions (p=0.48), or need for dose delays (p=0.61).

Discussion: There is a borderline statistically significant relationship between age and 24 hour AUC but no differences in mean age based on pD variables (i.e., dose reductions, dose delays and grade ≥ 3 toxicities) were identified. The treatment is well-tolerated across all age groups.

Citation Information: Cancer Res 2011;71(24 Suppl):Abstract nr P5-19-05.

A phase I/II prospective, single arm trial of gefitinib, trastuzumab, and docetaxel in patients with stage IV HER-2 positive metastatic breast cancer

Inhibition of the HER-2 pathway via the monoclonal antibody trastuzumab has had a major impact in treatment of HER-2 positive breast cancer, but de novo or acquired resistance may reduce its effectiveness. The known interplay between the epidermal growth factor receptor (EGFR) and HER-2 receptors and pathways creates a rationale for combined anti-EGFR and anti-HER-2 therapy in HER-2 positive metastatic breast cancer (MBC), and toxicities associated with the use of multiple chemotherapeutic agents together with biological therapies may also be reduced. We conducted a prospective, single arm, phase I/II trial to determine the efficacy and toxicity of the combination of trastuzumab with the EGFR inhibitor gefitinib and docetaxel, in patients with HER-2 positive MBC. The maximum tolerated dose (MTD) was determined in the phase I portion. The primary end point of the phase II portion was progression-free survival (PFS). Immunohistochemical analysis of biomarker expression of the PKA-related proteins cAMP response element-binding protein (CREB), phospho-CREB and DARPP-32 (dopamine and cAMP-regulated phosphoprotein of 32 kDa) plus t-DARPP (the truncated isoform of DARPP-32); PTEN; p-p70 S6K; and EGFR was conducted on tissue from metastatic sites. Nine patients were treated in the phase I portion of the study and 22 in the phase II portion. The MTD was gefitinib 250 mg on days 2-14, trastuzumab 6 mg/kg, and docetaxel 60 mg/m(2) every 21 days. For the 29 patients treated at the MTD, median PFS was 12.7 months, with complete and partial response rates of 18 and 46%, and a stable disease rate of 29%. No statistically significant correlation was found between response and expression of any biomarkers. We conclude that the combination of gefitinib, trastuzumab, and docetaxel is feasible and effective. Expression of the biomarkers examined did not predict outcome in this sample of HER-2 overexpressing metastatic breast cancer.

Pigment epithelium-derived factor regulates early pancreatic fibrotic responses and suppresses the profibrotic cytokine thrombospondin-1

Pigment epithelium-derived factor (PEDF) is important for maintaining the normal extracellular matrix. We hypothesized that the initiation of pancreatic fibrosis is dependent on the loss of PEDF. Pancreatic PEDF expression was assessed in wild-type mice fed either a control or ethanol diet using an intragastric feeding model. Pancreatitis responses were elicited with either a single episode or a repetitive cerulein-induced (50 μg/kg, 6 hourly i.p. injections) protocol in wild-type and PEDF-null mice. Quantitative real-time PCR and immunoblotting were performed to assess fibrogenic responses. In wild-type animals, PEDF expression increased with pancreatitis and was more pronounced in mice fed ethanol. Compared with wild-type mice, α-smooth muscle actin staining and expression levels of fibrogenic markers (eg, transforming growth factor-β1, platelet-derived growth factor, collagen I, and thrombospondin-1) were higher in PEDF-null mice at baseline. Sirius red staining revealed more fibrosis in PEDF-null versus wild-type pancreas 1 week after pancreatitis. Differences in tissue fibrosis resolved with longer recovery periods. PEDF overexpression suppressed thrombospondin-1 levels in vitro. Ethanol feeding and experimental pancreatitis increased PEDF expression in wild-type mice. PEDF-null mice, however, demonstrated enhanced early fibrotic responses compared with wild-type mice with pancreatitis. These findings indicate that PEDF acts as a compensatory antifibrotic cytokine in pancreatitis.

Integrated strain array for cellular mechanobiology studies

We have developed an integrated strain array for cell culture enabling high-throughput mechano-transduction studies. Biocompatible cell culture chambers were integrated with an acrylic pneumatic compartment and microprocessor-based control system. Each element of the array consists of a deformable membrane supported by a cylindrical pillar within a well. For user-prescribed waveforms, the annular region of the deformable membrane is pulled into the well around the pillar under vacuum, causing the pillar-supported region with cultured cells to be stretched biaxially. The optically clear device and pillar-based mechanism of operation enables imaging on standard laboratory microscopes. Straightforward fabrication utilizes off-the-shelf components, soft lithography techniques in polydimethylsiloxane, and laser ablation of acrylic sheets. Proof of compatibility with basic biological assays and standard imaging equipment were accomplished by straining C2C12 skeletal myoblast cells on the device for 6 hours. At higher strains, cells and actin stress fibers realign with a circumferential preference.

The vacuolar-ATPase modulates matrix metalloproteinase isoforms in human pancreatic cancer

The vacuolar-ATPase (v-ATPase) is a proton transporter found on many intracellular organelles and the plasma membrane (PM). The v-ATPase on PMs of cancer cells may contribute to their invasive properties in vitro. Its relevance to human cancer tissues remains unclear. We investigated whether the expression and cellular localization of v-ATPase corresponded to the stage of human pancreatic cancer, and its effect on matrix metalloproteinase (MMP) activation in vitro. The intensity of v-ATPase staining increased significantly across the range of pancreatic histology from normal ducts to pancreatic intraepithelial neoplasms (PanIN), and finally pancreatic ductal adenocarcinoma (PDAC). Low-grade PanIN lesions displayed polarized staining confined to the basal aspect of the cell in the majority (86%) of fields examined. High-grade PanIN lesions and PDAC showed intense and diffuse v-ATPase localization. In pancreatic cancer cells, PM-associated v-ATPase colocalized with cortactin, a component of the leading edge that helps direct MMP release. Blockade of the v-ATPase with concanamycin or short-hairpin RNA targeting the V₁E subunit reduced MMP-9 activity; this effect was greatest in cells with prominent PM-associated v-ATPase. In cells with detectable MMP-2 activities, however, treatment with concanamycin markedly increased MMP-2's most activated forms. V-ATPase blockade inhibited functional migration and invasion in those cells with predominantly MMP-9 activity. These results indicate that human PDAC specimens show loss of v-ATPase polarity and increased expression that correlates with increasing invasive potential. Thus, v-ATPase selectively modulates specific MMPs that may be linked to an invasive cancer phenotype.

Reticulon 4B (Nogo-B) is a novel regulator of hepatic fibrosis

Nogo-B, also known as Reticulon 4B, plays important roles in vascular injuries. Its function in the liver is not understood. The aim of this study was to characterize Nogo-B in liver fibrosis and cirrhosis. Nogo-B distribution was assessed in normal and cirrhotic human liver sections. We also determined the levels of liver fibrosis in wild-type (WT) and Nogo-A/B knockout (NGB KO) mice after sham operation or bile duct ligation (BDL). To investigate the mechanisms of Nogo-B's involvement in fibrosis, hepatic stellate cells were isolated from WT and NGB KO mice and transformed into myofibroblasts. Portal pressure was measured to test whether Nogo-B gene deletion could ameliorate portal hypertension. In normal livers, Nogo-B expression was found in nonparenchymal cells, whereas its expression in hepatocytes was minimal. Nogo-B staining was significantly elevated in cirrhotic livers. Fibrosis was significantly increased in WT mice 4 weeks after BDL compared with NGB KO mice. The absence of Nogo-B significantly reduced phosphorylation of Smad2 levels upon transforming growth factor β (TGF-β) stimulation. Reconstitution of the Nogo-B gene into NGB KO fibroblasts restored Smad2 phosphorylation. Four weeks after BDL, portal pressure was significantly increased in WT mice by 47%, compared with sham-operated controls (P = 0.03), whereas such an increase in portal pressure was not observed in NGB KO mice (P = NS).

CONCLUSION

Nogo-B regulates liver fibrosis, at least in part, by facilitating the TGFβ/Smad2 signaling pathway in myofibroblasts. Because absence of Nogo-B ameliorates liver fibrosis and portal hypertension, Nogo-B blockade may be a potential therapeutic target in fibrosis/cirrhosis.