Macrophages Facilitate Resistance to Anti-VEGF Therapy by Altered VEGFR Expression

Abstract Purpose: VEGF-targeted therapies have modest efficacy in cancerpatients, butacquiredresistance iscommon. Themechanisms underlying such resistance are poorly understood. Experimental Design: To evaluate the potential role of immune cells in the development of resistance to VEGF blockade, we first established a preclinical model of adaptive resistance to anti-VEGF therapy. Additional in vitro and in vivo studies were carried out to characterize the role of macrophages in such resistance. Results: Using murine cancer models of adaptive resistance to anti-VEGF antibody (AVA), we found a previously unrecognized roleofmacrophagesinsuchresistance.Macrophageswereactively recruited to the tumor microenvironment and were responsible for the emergence of AVA resistance. Depletion of macrophages following emergence of resistance halted tumor growth and prolonged survival of tumor-bearing mice. In a macrophagedeficient mouse model, resistance to AVA failed to develop, but could be induced by injection of macrophages. Downregulation of macrophage VEGFR-1 and VEGFR-3 expression accompanied upregulation of alternative angiogenic pathways, facilitating escape from anti-VEGF therapy. Conclusions: These findings provide a new understanding of the mechanisms underlying the modest efficacy of current antiangiogenesis therapies and identify new opportunities for combinationapproachesforovarianandothercancers. ClinCancerRes; 23(22); 7034–46. �2017 AACR

Hematogenous Metastasis of Ovarian Cancer: Rethinking Mode of Spread

SummaryOvarian cancer has a clear predilection for metastasis to the omentum, but the underlying mechanisms involved in ovarian cancer spread are not well understood. Here, we used a parabiosis model that demonstrates preferential hematogenous metastasis of ovarian cancer to the omentum. Our studies revealed that the ErbB3-neuregulin 1 (NRG1) axis is a dominant pathway responsible for hematogenous omental metastasis. Elevated levels of ErbB3 in ovarian cancer cells and NRG1 in the omentum allowed for tumor cell localization and growth in the omentum. Depletion of ErbB3 in ovarian cancer impaired omental metastasis. Our results highlight hematogenous metastasis as an important mode of ovarian cancer metastasis. These findings have implications for designing alternative strategies aimed at preventing and treating ovarian cancer metastasis

2′-OMe-phosphorodithioate-modified siRNAs show increased loading into the RISC complex and enhanced anti-tumour activity

Improving small interfering RNA (siRNA) efficacy in target cell populations remains a challenge to its clinical implementation. Here, we report a chemical modification, consisting of phosphorodithioate (PS2) and 2′-O-Methyl (2′-OMe) MePS2 on one nucleotide that significantly enhances potency and resistance to degradation for various siRNAs. We find enhanced potency stems from an unforeseen increase in siRNA loading to the RNA-induced silencing complex, likely due to the unique interaction mediated by 2′-OMe and PS2. We demonstrate the therapeutic utility of MePS2 siRNAs in chemoresistant ovarian cancer mouse models via targeting GRAM domain containing 1B (GRAMD1B), a protein involved in chemoresistance. GRAMD1B silencing is achieved in tumours following MePS2-modified siRNA treatment, leading to a synergistic anti-tumour effect in combination with paclitaxel. Given the previously limited success in enhancing siRNA potency with chemically modified siRNAs, our findings represent an important advance in siRNA design with the potential for application in numerous cancer types

Erythropoietin Stimulates Tumor Growth via EphB4

While recombinant human erythropoietin (rhEpo) has been widely used to treat anemia in cancer patients, concerns about its adverse effects on patient survival have emerged. A lack of correlation between expression of the canonical EpoR and rhEpo’s effects on cancer cells prompted us to consider the existence of an alternative Epo receptor. Here, we identified EphB4 as an Epo receptor that triggers downstream signaling via STAT3 and promotes rhEpo induced tumor growth and progression. In human ovarian and breast cancer samples, expression of EphB4 rather than the canonical EpoR correlated with decreased disease-specific survival in rhEpo-treated patients. These results identify EphB4 as a critical mediator of erythropoietin-induced tumor progression and further provide clinically significant dimension to the biology of erythropoietin

Investigation of in vitro and in vivo antioxidant potential of secoisolariciresinol diglucoside

The present study was designed to evaluate the in vitro and in vivo ameliorative antioxidant potential of secoisolariciresinol diglucoside (SDG). In vitro antioxidant activity of synthetic SDG was carried out using DPPH, reducing power potency, and DNA protection assays. Wistar albino rats weighing 180-220 g were used for in vivo studies and liver damage was induced in the experimental animals by a single intraperitoneal (I.P.) injection of CCl 4 (2 g/kg b.w.). Intoxicated animals were treated orally with synthetic SDG at (12.5 and 25 mg/kg b.w.) and Silymarin (25 mg/kg) for 14 consecutive days. The levels of catalase (CAT), superoxide dismutase (SOD), peroxidase (POX), and lipid peroxidase (LPO) were measured in liver and kidney homogenates. The synthetic SDG exerts high in vitro antioxidant potency as it could scavenge DPPH at a IC50 value of 78.9 μg/ml and has dose-dependent reducing power potency and protected DNA at 0.5 mg/ml concentration. Oral administration of synthetic SDG at 12.5 and 25 mg/kg b.w. showed significant protection compared to Silymarin (25 mg/kg) and the activities of CAT, SOD, and POX were markedly increased (P < 0.05), whereas LPO significantly decreased (P < 0.001) in a dose-dependent manner in liver and kidney in both pre- and post-treatment groups when compared to toxin-treated group. The results of in vitro and in vivo investigations revealed that synthetic SDG at 25 mg/kg b.w. is associated with beneficial changes in hepatic enzyme activities and thereby plays a key role in the prevention of oxidative damage in immunologic system

Antidiabetic effect of secoisolariciresinol diglucoside in streptozotocin-induced diabetic rats

Diabetes mellitus is a chronic metabolic disorder characterized by hyperglycaemia. Its complications such as neuropathy, cardiopathy, nephropathy, and micro and macro vascular diseases are believed to be due to the increase in oxidative stress and decrease in the level of antioxidants. The aim of this study was to determine the antihyperglycemic activity of synthetic Secoisolariciresinol diglucoside (SDG) in streptozotocin (STZ)-induced diabetic rats. The synthetic SDG in a single-dose (20 mg/kg b.w.) two-day study showed dose-dependent reduction in glucose levels with maximum effect of 64.62% at 48 h post drug treatment (p \textless 0.05), which is comparable to that of the standard drug tolbutamide (20 mg/kg b.w.). In a multi-dose fourteen-day study, lower doses of SDG (5 and 10 mg/kg b.w.) exhibited moderate reduction in glucose levels, lipid profile, restoration of antioxidant enzymes and improvement of the insulin and c-peptide levels which shows the regeneration of β-cell which secretes insulin. Altered levels of lipids and enzymatic antioxidants were also restored by the SDG to the considerable levels in diabetic rats. Results of the present investigation suggest that diabetes is associated with an increase in oxidative stress as shown by increase in serum malondialdehyde (MDA), decreased levels of catalase (CAT), superoxide dismutase (SOD), and glutathione (GSH). Also, diabetes is associated with an increase in serum total cholesterol as well as triglycerides levels and decrease in insulin and c-peptide levels. SDG is effective in retarding the development of diabetic complications. We propose that synthetic SDG exerts anti hyperglycemic effect by preventing the liver from peroxidation damage through inhibition of ROS level mediated increased level of enzymatic and non-enzymatic antioxidants. And, also maintaining tissue function which results in improving the sensitivity and response of target cells in STZ-induced diabetic rats to insulin

Synergistic hepatoprotective effects of omega-3 and omega-6 fatty acids from Indian flax and sesame seed oils against CCl4-induced oxidative stress-mediated liver damage in rats

Flaxseed (FS) and sesame seed (SS) are traditional and functional foods in traditional Indian medicine for treating various disorders. The present study investigated the hepatoprotective effects of bioactive-fatty acids (FAs) from FS and SS against carbon tetrachloride (CCl4)-induced hepatic damage in rats. Pre and post-treatments for 28 consecutive days significantly increased the activities of in vivo antioxidant enzymes such as catalase (CAT), superoxide dismutase (SOD), and peroxidase (POX), whereas, lipid peroxidation (LPO) activity was markedly decreased in a dose-dependent manner in liver and kidneys. A significant reduction was observed in the hematological parameters like aspartate aminotransferase (AST), alanine aminotransferase (ALT), alkaline phosphatase (ALP), and total bilirubin in the serum of post-treated animals compared to the negative control. The results were confirmed histopathologically. The results suggested that the omega-3 and omega-6 FAs from flaxseed oil (FSO) and sesame seed oil (SSO), respectively, showed potential synergistic hepatoprotective and antioxidant effects that were mediated mainly by omega-3 and omega-6 FAs present in the respective seed oils. GRAPHICS] HIGHLIGHTS ALA and LA omega-3 and omega-6 FAs rich oils from FSO an SSO respectively, mitigated the hepatotoxicity induced by CCl4. The in vitro and in vivo studies have revealed that the combination of FSO+SSO significantly increased the hepatic antioxidant enzymes like CAT, SOD, POX, and decreased MDA levels in the liver and kidneys of CCl4 induced rats. Co-treatment of FSO+SSO shown more synergistic antioxidant potential compared to their individual treatments

Comparative evaluation of hepatoprotective activity of carotenoids of microalgae

The present study deals with evaluation of the hepatotoprotective activity of carotenoids from two well-known microalgae, Spirulina platensis and Dunaliella salina. Carotenoids were extracted in hexane:isopropyl alcohol (1:1 vol/vol) and fed orally in olive oil to Wistar albino rats at a dose of 100 µg/kg of body weight/day (in terms of carotenoids). The degree of hepatoprotection was measured by estimation of biochemical parameters like serum transaminases serum glutamate oxaloacetate transaminase (SGOT) and serum glutamate pyruvate transaminase (SGPT), serum alkaline phosphatase, total albumin, and total protein. The results were compared with those for a control group, a CCl4-induced hepatic damage group, and a group treated with synthetic β-carotene (all-trans) at the same dose. The protein content of the CCl4-treated group, which received normal diet and a dose of toxin, showed a significant decrease, i.e., 3.92 mg/mL, whereas the protein levels were higher, i.e., 6.96 and 6.32 mg/mL, in the case of the Dunaliella and Spirulina, respectively, carotenoid-treated groups. The CCl4-treated group shown higher activity of transaminases (128.68 units/mL SGPT and 171.52 units/mL SGOT). However, the activity of SGPT was 62.83 units/mL for Dunaliella and 76.83 units/mL for Spirulina, i.e., carotenoids of Dunaliella showed a higher degree of protection. For serum alkaline phosphatase, the standard β-carotene value was 81.52 units/mL, compared with 84.46 units/mL for the CCl4-treated group; however, natural algal carotenoids yielded 38.45 units/mL (D. salina) and 44.73 units/mL (Spirulina). The total albumin value diminished with CCl4 treatment (2.46 mg/mL); the effect was highest for Dunaliella, followed by the Spirulina carotenoid-treated group. The results clearly indicate that carotenoids from Dunaliella possess better hepatoprotection compared with those from Spirulina. High-performance liquid chromatography of the carotenoids indicated that Spirulina contains only β-carotene and Dunaliella contains other carotenoids and xanthophyll. The increase in protection with Dunaliella indicates that mixed carotenoids exhibit better biological activity than β-carotene alone. The results of this study indicate that carotenoids obtained from an algal source have a higher antihepatotoxic effect, compared with synthetic β-carotene and with β-carotene alone from a natural source

Protective effect of dunaliella salina—A marine micro alga, against carbon tetrachloride-induced hepatotoxicity in rats

This is the first report on the hepatoprotective potentials of marine micro algae Dunaliella species. Dunaliella salina, halotolarent green alga was cultivated in modified autotrophic medium. The alga was subjected to light and nutrient stress in order to accumulate (β-carotene along with other carotenoids. Such β-carotene enriched yellow cells were fed to rats by mixing with regular feed at the dose of 2.5 and of 5.0gkg−1 b.w. for 2 weeks. The degree of hepatoprotection was measured up on challenging animals with toxin (2.0gkg−1 of carbon tetrachloride) by estimation of biochemical parameters like, serum transaminases (serum aspartate transaminase (S)AST and serum alanine transaminase (S)ALT), serum alkaline phosphatase and total protein. The results were compared to animals on normal diet and with group fed with 100μgkg−1 b.w. of standard all trans β-carotene. Among the three test groups the group fed with algae of 5.0gkg−1 body weight, showed maximum protection. The levels of (S)AST and (S)ALT was found to be 61.3±6.4 and 80.7±5.6, against 90.8±10.5 and 144.7±13.9 in case of standard β-carotene. The protein contents were increased in case of control to 6.1±0.7 and the same was found to be significantly less in case of 5.0gkg−1 Dunaliella fed group, which shown 5.6±0.8 total protein. However, the activity of 2.5gkg−1 was also significant comparatively (P<0.05). The results indicate that Dunaliella, which contains isomeric forms of β-carotene can act as good antihepatotoxic when compared to synthetic all trans β-carotene. Dunaliella has shown the presence of both cis and trans isomeric forms of β-carotene, where as synthetic compounds contain only trans isomer. Hepatoprotectivity may be due to presence of various isomeric forms of carotene and other oxygenated carotenoids (xanthophylls) in algae