Bioactive scaffolds with enhanced supramolecular motion promote recovery from spinal cord injury

[Figure: see text].

Obesity promotes resistance to anti-VEGF therapy in breast cancer by up-regulating IL-6 and potentially FGF-2

Anti-vascular endothelial growth factor (VEGF) therapy has failed to improve survival in patients with breast cancer (BC). Potential mechanisms of resistance to anti-VEGF therapy include the up-regulation of alternative angiogenic and proinflammatory factors. Obesity is associated with hypoxic adipose tissues, including those in the breast, resulting in increased production of some of the aforementioned factors. Hence, we hypothesized that obesity could contribute to anti-VEGF therapy's lack of efficacy. We found that BC patients with obesity harbored increased systemic concentrations of interleukin-6 (IL-6) and/or fibroblast growth factor 2 (FGF-2), and their tumor vasculature was less sensitive to anti-VEGF treatment. Mouse models revealed that obesity impairs the effects of anti-VEGF on angiogenesis, tumor growth, and metastasis. In one murine BC model, obesity was associated with increased IL-6 production from adipocytes and myeloid cells within tumors. IL-6 blockade abrogated the obesity-induced resistance to anti-VEGF therapy in primary and metastatic sites by directly affecting tumor cell proliferation, normalizing tumor vasculature, alleviating hypoxia, and reducing immunosuppression. Similarly, in a second mouse model, where obesity was associated with increased FGF-2, normalization of FGF-2 expression by metformin or specific FGF receptor inhibition decreased vessel density and restored tumor sensitivity to anti-VEGF therapy in obese mice. Collectively, our data indicate that obesity fuels BC resistance to anti-VEGF therapy via the production of inflammatory and angiogenic factors.

Abstract LB-057: Hypoxia regulation of antigen presentation machinery expression in breast cancer

Antigen presentation plays a major role in tumor cell recognition and targeting by immune cells, and is critical to the success of many cancer immunotherapies. How the abnormal tumor microenvironment affects tumor cell antigen presentation is unclear. Hypoxia is a prevalent feature of the tumor microenvironment. Here, we showed that the expression of major histocompatibility complex class I (MHCI) is associated with regions of hypoxia in human breast tumors. The association between hypoxia and MHCI is independent of the breast tumor hormone receptor and HER2 expression status. In vitro studies revealed that hypoxia directly regulates the expression levels of MHCI along with other components of the antigen presentation machinery. Multiple kinase regulators of MHCI expression are responsive to hypoxia. These results suggest that hypoxia effects on cancer cell antigen presentation may be a potential mechanism of tumor immune evasion and treatment resistance.

Citation Format: Mei Rosa Ng, Francesco Sabbatino, Mark Duquette, Kamila Naxerova, Mark Badeaux, Gino B. Ferraro, Shan M. Chin, Divya Bezwada, Elena F. Brachtel, Soldano Ferrone, Rakesh K. Jain. Hypoxia regulation of antigen presentation machinery expression in breast cancer [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 LB-057.

Obesity-Induced Inflammation and Desmoplasia Promote Pancreatic Cancer Progression and Resistance to Chemotherapy

It remains unclear how obesity worsens treatment outcomes in patients with pancreatic ductal adenocarcinoma (PDAC). In normal pancreas, obesity promotes inflammation and fibrosis. We found in mouse models of PDAC that obesity also promotes desmoplasia associated with accelerated tumor growth and impaired delivery/efficacy of chemotherapeutics through reduced perfusion. Genetic and pharmacologic inhibition of angiotensin-II type-1 receptor reverses obesity-augmented desmoplasia and tumor growth and improves response to chemotherapy. Augmented activation of pancreatic stellate cells (PSC) in obesity is induced by tumor-associated neutrophils (TAN) recruited by adipocyte-secreted IL1β. PSCs further secrete IL1β, and inactivation of PSCs reduces IL1β expression and TAN recruitment. Furthermore, depletion of TANs, IL1β inhibition, or inactivation of PSCs prevents obesity-accelerated tumor growth. In patients with pancreatic cancer, we confirmed that obesity is associated with increased desmoplasia and reduced response to chemotherapy. We conclude that cross-talk between adipocytes, TANs, and PSCs exacerbates desmoplasia and promotes tumor progression in obesity.

SIGNIFICANCE

Considering the current obesity pandemic, unraveling the mechanisms underlying obesity-induced cancer progression is an urgent need. We found that the aggravation of desmoplasia is a key mechanism of obesity-promoted PDAC progression. Importantly, we discovered that clinically available antifibrotic/inflammatory agents can improve the treatment response of PDAC in obese hosts. Cancer Discov; 6(8); 852-69. ©2016 AACR.See related commentary by Bronte and Tortora, p. 821This article is highlighted in the In This Issue feature, p. 803.

Abstract 898: Obesity-induced inflammation and desmoplasia promote pancreatic cancer progression and resistance to chemotherapy

INTRODUCTION: With the current epidemic of obesity, the majority of pancreatic cancer patients are overweight or obese at diagnosis. Importantly, obesity worsens treatment outcomes in pancreatic cancer patients. Therefore, understanding the mechanisms that underlie the poorer prognosis of obese cancer patients is of paramount importance. Obesity causes inflammation and fibrosis in the normal pancreas due to the accumulation of dysfunctional hypertrophic adipocytes. Importantly, desmoplasia - a fibroinflammatory microenvironment - is a hallmark of pancreatic ductal adenocarcinoma (PDAC), and we have shown that activation of pancreatic stellate cells (PSCs) via angiotensin-II type 1 receptor (AT1) pathway is a major contribution to tumor desmoplasia. Whether obesity affects desmoplasia in PDACs, and interferes with delivery and response of chemotherapeutics is currently unknown.

EXPERIMENTAL DESIGN: Using both human samples and mouse models of PDAC - multiple syngeneic models of PDAC: PAN02, AK4.4, KPC, iKRAS in diet-induced and genetic obese mouse models -, we determined the effects of obesity on desmoplasia and inflammation/immune cell infiltration, tumor growth and delivery and response to chemotherapy.

RESULTS: We found that obesity aggravates desmoplasia in PDACs in both patient samples and multiple mouse models. In addition, tumors in obese mice presented with elevated levels of activated PSCs and fibrosis, as well as inflammatory cytokines and TANs,. These alterations in the tumor microenvironment in obesity associated with accelerated tumor growth, reduced tumor blood perfusion and increased hypoxia, and impaired delivery and efficacy of chemotherapeutics. Genetic ablation and pharmacological inhibition (losartan) of AT1 signaling reversed obesity-augmented desmoplasia and tumor growth, and improved the response to chemotherapy to the level observed in lean mice. We further discovered the underlying mechanisms: 1) obesity increases intra-tumor adipocytes and IL-1ß secretion by these cells; 2) increased IL-1ß induces TAN recruitment; 3) recruited TANs activate PSCs; and 4) activated PSCs enhance desmoplasia. Conversely, activated PSCs also secrete IL-1ß that recruits further TANs. Of clinical relevance, we found that metformin not only normalizes the abnormal systemic metabolism, but also reprogramms PSCs and immune cells and alleviates the fibroinflammatory microenvironment in pancreatic cancer in obesity/diabetes.. Importantly, the strategies described above were not effective in the normal weight setting.

CONCLUSION: Here we successfully demonstrated that targeting desmoplasia, including immunomodulation with anti-IL-1ß, or treatment with generic drugs such as losartan and metformin are potential strategies to potentiate treatments in PDAC patients with excess weight.

Citation Format: Joao Incio, Priya Suboj, Shan M. Chin, Chen Ivy, Mei Ng, Hadi Nia, Jelena Grahovac, Hao Liu, Shannon Kao, Suboj Babykutty, Yuhui Huang, Keehoon Jung, Nuh Rahbari, Xiaoxing Han, Vikash Chauhan, John Martin, Julia Kahn, Peigen Huang, Raquel Soares, Yves Boucher, Dai Fukumura, Rakesh Jain. Obesity-induced inflammation and desmoplasia promote pancreatic cancer progression and resistance to chemotherapy. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 898.

PlGF/VEGFR-1 Signaling Promotes Macrophage Polarization and Accelerated Tumor Progression in Obesity

PURPOSE

Obesity promotes pancreatic and breast cancer progression via mechanisms that are poorly understood. Although obesity is associated with increased systemic levels of placental growth factor (PlGF), the role of PlGF in obesity-induced tumor progression is not known. PlGF and its receptor VEGFR-1 have been shown to modulate tumor angiogenesis and promote tumor-associated macrophage (TAM) recruitment and activity. Here, we hypothesized that increased activity of PlGF/VEGFR-1 signaling mediates obesity-induced tumor progression by augmenting tumor angiogenesis and TAM recruitment/activity.

EXPERIMENTAL DESIGN

We established diet-induced obese mouse models of wild-type C57BL/6, VEGFR-1 tyrosine kinase (TK)-null, or PlGF-null mice, and evaluated the role of PlGF/VEGFR-1 signaling in pancreatic and breast cancer mouse models and in human samples.

RESULTS

We found that obesity increased TAM infiltration, tumor growth, and metastasis in pancreatic cancers, without affecting vessel density. Ablation of VEGFR-1 signaling prevented obesity-induced tumor progression and shifted the tumor immune environment toward an antitumor phenotype. Similar findings were observed in a breast cancer model. Obesity was associated with increased systemic PlGF, but not VEGF-A or VEGF-B, in pancreatic and breast cancer patients and in various mouse models of these cancers. Ablation of PlGF phenocopied the effects of VEGFR-1-TK deletion on tumors in obese mice. PlGF/VEGFR-1-TK deletion prevented weight gain in mice fed a high-fat diet, but exacerbated hyperinsulinemia. Addition of metformin not only normalized insulin levels but also enhanced antitumor immunity.

CONCLUSIONS

Targeting PlGF/VEGFR-1 signaling reprograms the tumor immune microenvironment and inhibits obesity-induced acceleration of tumor progression. Clin Cancer Res; 22(12); 2993-3004. ©2016 AACR.

Metformin Reduces Desmoplasia in Pancreatic Cancer by Reprogramming Stellate Cells and Tumor-Associated Macrophages

Background

Pancreatic ductal adenocarcinoma (PDAC) is a highly desmoplastic tumor with a dismal prognosis for most patients. Fibrosis and inflammation are hallmarks of tumor desmoplasia. We have previously demonstrated that preventing the activation of pancreatic stellate cells (PSCs) and alleviating desmoplasia are beneficial strategies in treating PDAC. Metformin is a widely used glucose-lowering drug. It is also frequently prescribed to diabetic pancreatic cancer patients and has been shown to associate with a better outcome. However, the underlying mechanisms of this benefit remain unclear. Metformin has been found to modulate the activity of stellate cells in other disease settings. In this study, we examine the effect of metformin on PSC activity, fibrosis and inflammation in PDACs.

Methods/Results

In overweight, diabetic PDAC patients and pre-clinical mouse models, treatment with metformin reduced levels of tumor extracellular matrix (ECM) components, in particular hyaluronan (HA). In vitro, we found that metformin reduced TGF-ß signaling and the production of HA and collagen-I in cultured PSCs. Furthermore, we found that metformin alleviates tumor inflammation by reducing the expression of inflammatory cytokines including IL-1β as well as infiltration and M2 polarization of tumor-associated macrophages (TAMs) in vitro and in vivo. These effects on macrophages in vitro appear to be associated with a modulation of the AMPK/STAT3 pathway by metformin. Finally, we found in our preclinical models that the alleviation of desmoplasia by metformin was associated with a reduction in ECM remodeling, epithelial-to-mesenchymal transition (EMT) and ultimately systemic metastasis.

Conclusion

Metformin alleviates the fibro-inflammatory microenvironment in obese/diabetic individuals with pancreatic cancer by reprogramming PSCs and TAMs, which correlates with reduced disease progression. Metformin should be tested/explored as part of the treatment strategy in overweight diabetic PDAC patients.

Latex allergy in dentistry. Review and report of case presenting as a serious reaction to latex dental dam

Latex allergy may have severe consequences including development of anaphylaxis. This report describes a patient who underwent a reaction to latex dental dam manifesting as erythema, facial swelling and mild airway compromise. Restorative procedures under latex dental dam were performed under local anaesthesia on two occasions resulting in reactions of increasing severity. Following the first event the cause of the reaction was undetermined, but attributed to a possible allergy to local anaesthetic, and managed with corticosteroids and antihistamines. On a subsequent occasion the swelling was more severe, associated with difficulty in swallowing and mild airway compromise, and was managed as previously with adrenaline also being required. Latex allergy was subsequently confirmed.

The relationship between the position of the retinal area centralis and feeding behaviour in juvenile black bream Acanthopagrus butcheri (Sparidae: Teleostei)

The topography of the neurons in the retinal ganglion cell layer of juvenile black bream Acanthopagrus butcheri changes during development. The region of high cell density the area centralis (AC), relocates from a temporal (central) to a dorsal (peripheral) position within the dorso-temporal retinal quadrant. To ascertain whether the differences in the position of the AC during development are related to feeding behaviour, we monitored fishes that were given a choice of food. A range of feeding behaviour patterns was recorded in individual fishes. The smallest fishes (8-15 mm standard length (SL)) took live food from the water column. Following weaning onto pellets, fishes exhibited a preference for taking food from either the substrate or the surface (but not both). When greater than 20 mm SL, a number of individuals then divided their time between surface and substrate feeding before all fishes became exclusive benthic feeders at a stage between 50 and 80 mm SL. Three individual fishes, for which behaviour patterns were categorized, were killed and the topography of the retinal ganglion cell layer analysed. A range of positions for the AC was found with the smallest fish (12 mm SL) possessing a region of high cell density in the temporal retina. In a larger fish (70 mm SL), feeding from both the substrate and the surface, the AC was found in an intermediate dorso-temporal position. The AC of a fish (51 mm SL) preferentially taking food from the substrate was located in a dorsal position.

Variability in the location of the retinal ganglion cell area centralis is correlated with ontogenetic changes in feeding behavior in the black bream, Acanthopagrus butcheri (Sparidae, teleostei)

The development of neural cell topography in the retinal ganglion cell layer was examined in a teleost, the black bream (Acanthopagrus butcheri). From Nissl-stained wholemounts, it was established that fish between 10 and 15 mm standard body length (SL) possess high cell densities throughout the dorso-temporal retinal quadrant, with peak cell densities located in temporal regions of the retina. However, in fish between 15 and 80 mm SL, a wide variation in the position of the peak cell density is revealed with the locations of the areae centrales (AC) ranging from exclusively temporal to periphero-dorsal retina. Fish larger than 80 mm SL always possess an AC located in the dorsal region of the dorso-temporal retinal quadrant. The topography of ganglion cells within the ganglion cell layer was determined by comparing the numbers of ganglion cells retrogradely-labeled from the optic nerve with the total population of Nissl-stained neurons (ganglion plus displaced amacrine cells) in a range of different-sized individuals. Ganglion cell topography was the same as that recorded for all Nissl-stained neurons. The feeding behavior of juveniles from metamorphosis to 80 mm SL was observed, where fish were given the choice of feeding on live food in mid-water (until 15 mm SL) or obtaining pellets from the surface or the bottom. A range of feeding patterns was recorded, with the smallest fish taking food from mid-water but individuals between 15 and 80 mm SL taking food either from the surface or the bottom or both. A correlation between the preferred mode of feeding and the position of the AC was found, such that those individuals feeding in mid-water or at the surface possess a temporal or intermediate (dorso- temporal) AC, whereas those predominantly feeding from the bottom possess a dorsal AC.

Multiple forms of an inositol polyphosphate 5-phosphatase form signaling complexes with Shc and Grb2

BACKGROUND

Shc and Grb2 form a complex in cells in response to growth factor stimulation and link tyrosine kinases to Ras during the resulting signaling process. Shc and Grb2 each contain domains that mediate interactions with other unidentified intracellular proteins. For example, the Shc PTB domain binds to 130 kDa and 145 kDa tyrosine-phosphorylated proteins in response to stimulation of cells by growth factors, cytokines and crosslinking of antigen receptors. The Grb2 SH3 domains bind to an unidentified 116 kDa protein in T cells. We have identified three proteins, of 110 kDa, 130 kDa and 145 kDa, as a new family of molecules encoded by the same gene. In vivo studies show that these proteins form signal transduction complexes with Shc and with Grb2.

RESULTS

The 130 kDa and 145 kDa tyrosine-phosphorylated proteins that associate with the Shc PTB domain were purified by conventional chromatographic methods. Partial peptide and cDNA sequences corresponding to these proteins, termed SIP-145 and SIP-130 (SIP for signaling inositol polyphosphate 5-phosphatase), identified them as SH2 domain-containing products of a single gene and as members of the inositol polyphosphate 5-phosphatase family. The SIP-130 and SIP-145 proteins and inositol polyphosphate 5-phosphatase activity associated with Shc in vivo in response to B-cell activation. By using an independent approach, expression cloning, we found that the Grb2 SH3 domains bind specifically to SIP-110, a 110 kDa splice variant of SIP-145 and SIP-130, which lacks the SH2 domain. The SIP proteins hydrolyzed phosphatidylinositol (3,4,5)-trisphosphate (PtdIns (3,4,5)-P3) and Ins (1,3,4,5)-P4, but not PtdIns (4,5)-P2 or Ins (1,4,5)-P3.

CONCLUSIONS

These findings strongly implicate the inositol polyphosphate 5-phosphatases in Shc- and Grb2-mediated signal transduction. Furthermore, SIP-110, SIP-130 and SIP-145 prefer 3-phosphorylated substrates, suggesting a link to the phosphatidylinositol 3-kinase signaling pathway.

Molecular diagnosis of Duchenne muscular dystrophy in Singapore

Duchenne muscular dystrophy (DMD) is a common lethal sex-linked recessive disorder. Seventy percent of the cases are inherited and 30% are due to mutations. The mainstay of prevention is detection of female carriers and antenatal diagnosis of affected foetuses. Before the era of molecular diagnosis, DMD has been clinically defined. Serum creatine kinase (CK) has also been used to screen women at risk for carrier status. With the isolation and sequencing of the DMD gene at Xp21 and the identification of the DMD gene-product dystrophin, DNA technology can be applied for the diagnosis of the affected, for the detection of carriers and in antenatal diagnosis. The multiplex polymerase chain reaction (PCR) technique offers a rapid and simple screening method for deletions of the gene. We were able to detect partial deletions which account for 58.3% of gene defects in our patients. This direct demonstration of the gene defect that causes DMD gives a 100% assurance of accuracy and specificity of the diagnosis. Linkage analysis is especially useful for prenatal diagnosis and carrier detection in the remaining 41.7% of families without detectable deletions or duplications. This approach however is indirect and is dependent on information on genotypes from affected males and key family members. With the availability of increasingly more restriction fragment length polymorphisms (RFLPs), it has become practical to use the haplotype method for accurate carrier detection and prenatal diagnosis.

Three chemically distinct types of oxidants formed by iron-mediated Fenton reactions in the presence of DNA

Exposure of Escherichia coli to H2O2 leads to two kinetically distinguishable modes of killing: mode I killing occurs maximally near 2 mM H2O2, whereas mode II killing is essentially independent of H2O2 concentrations up to 20 mM. A major portion of H2O2 toxicity is attributed to DNA damage caused by the iron-mediated Fenton reaction. By studying DNA damage during Fenton reactions in vitro, the same complex kinetics were observed and three types of oxidants were distinguished based upon their reactivities toward H2O2 and alcohols and upon iron-chelator effects. Type I oxidants are sensitive to H2O2 but moderately resistant to ethanol; type II oxidants are resistant to both H2O2 and ethanol; type III oxidants are sensitive to H2O2, ethanol, and t-butanol. To explain these results, we hypothesize that type I oxidants are generated upon Fe2+ associated with DNA only through electrostatic interactions and cause mode I killing of E. coli; type II oxidants arise upon Fe2+, which is at least partially base-associated, and cause mode II killing; type III oxidants arise on Fe2+ free in solution and probably do not cause killing. Therefore, particular interactions of DNA with transition metals should be considered to be an integral part of the chemistry and toxicity of H2O2.

Expression and characterization of recombinant hepatitis A virus 3C proteinase

The 3C proteinase from the hepatitis A virus (HAV) was cloned into a multicopy expression vector in Escherichia coli under control of the tac promoter. The resulting plasmid construction produced 3C proteinase as a soluble and active enzyme constituting approximately 10% of total cellular proteins. The enzyme was purified to apparent homogeneity as judged by SDS gel electrophoresis and HPLC reversed-phase and FPLC ion-exchange chromatography. A colorimetric assay was developed, and synthetic peptides derived from the predicted cleavage sites of the HAV polyprotein were tested for proteolysis of the enzyme. The peptide representing the 2B/2C cleavage site was cleaved most efficiently with a Km and kcat of 2.1 +/- 0.5 mM and 1.8 +/- 0.1 s-1, respectively. Site-directed mutagenesis was then used to identify the cysteine at position 172 as the active site nucleophile. Finally, the purified enzyme showed the expected endoproteinase activity on the P1 precursor protein generated by in vitro transcription/translation.

Characterization of group specific antibodies in primates: studies with SIV envelope in macaques

Sera from SIV-infected macaques were found to contain antibodies that reacted with conformation-dependent, group-specific determinants on the SIV envelope protein gp130. These conformation-dependent antibodies exhibited virus neutralizing activity; their presence was associated with protection in vaccine studies. The properties of these antibodies are quite similar to those that have been identified in sera from HIV-infected human subjects. These data suggest that the SIV envelope gp130 remains a candidate for subunit vaccine studies.

Toxic DNA damage by hydrogen peroxide through the Fenton reaction in vivo and in vitro

Exposure of Escherichia coli to low concentrations of hydrogen peroxide results in DNA damage that causes mutagenesis and kills the bacteria, whereas higher concentrations of peroxide reduce the amount of such damage. Earlier studies indicated that the direct DNA oxidant is a derivative of hydrogen peroxide whose formation is dependent on cell metabolism. The generation of this oxidant depends on the availability of both reducing equivalents and an iron species, which together mediate a Fenton reaction in which ferrous iron reduces hydrogen peroxide to a reactive radical. An in vitro Fenton system was established that generates DNA strand breaks and inactivates bacteriophage and that also reproduces the suppression of DNA damage by high concentrations of peroxide. The direct DNA oxidant both in vivo and in this in vitro system exhibits reactivity unlike that of a free hydroxyl radical and may instead be a ferryl radical.