Antitumor Activity Of Doxorubicin Research Articles

Chitotriose Enhanced Antitumor Activity of Doxorubicin through Egr1 Upregulation in MDA-MB-231 Cells.

Dietary supplementation is proposed as a strategy to reduce the side effects of conventional chemotherapy for triple-negative breast cancer (TNBC). Chitosan oligosaccharides (COS), a functional carbohydrate, have been identified to potentially inhibit cancer cell proliferation. However, a detailed investigation is required to fully understand its exact influence, particularly in terms of COS composition. The antitumor activities of COS oligomers and its monomer of glucosamine, when combined with doxorubicin separately, were evaluated in MDA-MB-231 cells. Chitotriose was identified to have the most significant synergistic effect. Preincubation with chitotriose was observed to promote the entry of doxorubicin into the cell nuclei and induce morphological changes in the cells. Mechanism analysis at the transcriptional level revealed that the early growth response 1 (Egr1) gene was a key regulator in enhancing the suppressive effect. This gene was found to modulate the activity of its downstream gene, growth arrest, and DNA damage-inducible alpha (Gadd45a). The role of Egr1 was confirmed through a small interfering RNA test and function assay. These findings provide insight into the effect and underlying mechanism of chitotriose supplementation for TNBC therapy.

Extracellular Vesicles from M1-Polarized Macrophages Combined with Hyaluronic Acid and a β-Blocker Potentiate Doxorubicin's Antitumor Activity by Downregulating Tumor-Associated Macrophages in Breast Cancer.

One of the main reasons for cancer’s low clinical response to chemotherapeutics is the highly immunosuppressive tumor microenvironment (TME). Tumor-ass ociated M2 macrophages (M2-TAMs) orchestrate the immunosuppression, which favors tumor progression. Extracellular vesicles (EVs) have shown great potential for targeted therapies as, depending on their biological origin, they can present different therapeutic properties, such as enhanced accumulation in the target tissue or modulation of the immune system. In the current study, EVs were isolated from M1-macrophages (M1-EVs) pre-treated with hyaluronic acid (HA) and the β-blocker carvedilol (CV). The resulting modulated-M1 EVs (MM1-EVs) were further loaded with doxorubicin (MM1-DOX) to assess their effect in a mouse model of metastatic tumor growth. The cell death and cell migration profile were evaluated in vitro in 4T1 cells. The polarization of the RAW 264.7 murine macrophage cell line was also analyzed to evaluate the effects on the TME. Tumors were investigated by qRT-PCR and immunohistochemistry. MM1-DOX reduced the primary tumor size and metastases. NF-κB was the major gene downregulated by MM1-DOX. Furthermore, MM1-DOX reduced the expression of M2-TAM (CD-163) in tumors, which resulted in increased apoptosis (FADD) as well as decreased expression of MMP-2 and TGF-β. These results suggest a direct effect in tumors and an upregulation in the TME immunomodulation, which corroborate with our in vitro data that showed increased apoptosis, modulation of macrophage polarization, and reduced cell migration after treatment with M1-EVs combined with HA and CV. Our results indicate that the M1-EVs enhanced the antitumor effects of DOX, especially if combined with HA and CV in an animal model of metastatic cancer.

Chemosensitizing effect and mechanism of imperatorin on the anti-tumor activity of doxorubicin in tumor cells and transplantation tumor model.

Multidrug resistance of tumors has been a severe obstacle to the success of cancer chemotherapy. The study wants to investigate the reversal effects of imperatorin (IMP) on doxorubicin (DOX) resistance in K562/DOX leukemia cells, A2780/Taxol cells and in NOD/SCID mice, to explore the possible molecular mechanisms. K562/DOX and A2780/Taxol cells were treated with various concentrations of DOX and Taol with or without different concentrations of IMP, respectively. K562/DOX xenograft model was used to assess anti-tumor effect of IMP combined with DOX. MTT assay, Rhodamine 123 efflux assay, RT-PCR, and Western blot analysis were determined in vivo and in vitro. Results showed that IMP significantly enhanced the cytotoxicity of DOX and Taxol toward corresponding resistance cells. In vivo results illustrated both the tumor volume and tumor weight were significantly decreased after 2-week treatment with IMP combined with DOX compared to the DOX alone group. Western blotting and RT-PCR analyses indicated that IMP downregulated the expression of P-gp in K562/DOX xenograft tumors in NOD/SCID mice. We also evaluated glycolysis and glutamine metabolism in K562/DOX cells by measuring glucose consumption and lactate production. The results revealed that IMP could significantly reduce the glucose consumption and lactate production of K562/DOX cells. Furthermore, IMP could also remarkably repress the glutamine consumption, α-KG and ATP production of K562/DOX cells. Thus, IMP may sensitize K562/DOX cells to DOX and enhance the anti-tumor effect of DOX in K562/DOX xenograft tumors in NOD/SCID mice. IMP may be an adjuvant therapy to mitigate the multidrug resistance in leukemia chemotherapy.

Isoalantolactone Enhances the Antitumor Activity of Doxorubicin by Inducing Reactive Oxygen Species and DNA Damage.

Colon cancer is one of the most common cancer in the world. Doxorubicin (DOX) is a classical anti-tumor drug which widely used in treatment of cancers, however, high toxicity limited its further clinical application. Thus, it is urgent to find new drugs with low toxicity and high efficiency to treat colon cancer. Isoalantolactone (IATL), an isomeric sesquiterpene lactone isolated from the plant of inula helenium, has been reported to have anti-cancer activity against a variety of cancer cells. However, the function of IATL in colon cancer remains unclear. Here, we demonstrated that IATL inhibited colon cancer cell growth by increasing cellular reactive oxygen species (ROS) production. Further study showed that ROS accumulation contributed to DNA damage and JNK signaling pathway activation. In addition, we found that IATL markedly enhanced DOX-induced cell cytotoxicity in colon cancer cells. IATL in combination with DOX significantly increased the ROS production, induced DNA damage and activated JNK signaling pathway. Taken together, our data suggested that combined treatment with IATL and DOX may serve as a potential therapeutics for colon cancer.

In Vivo Study of Silver Nanoparticles Entrapped Poly(N-vinyl pyrrolidone/Dextran) Hydrogel Synthesized by Gamma Radiation on the Antitumor Activity of Doxorubicin

The preparation of interpenetrating hydrogel networks (IPN) based on cross-linked poly (N-vinyl pyrrolidone/Dextran) P(NVP/Dex) and poly (N-vinyl pyrrolidone/Dextran)-Ag nanocomposites P(NVP/Dex)-Ag prepared by gamma radiation. Highly stable and uniformly distributed silver nanoparticles have been obtained within hydrogel networks as nanoreactors via in situ reduction of silver nitrate (AgNO3) using sodium borohydride (NaBH4) as reducing agent. The formation of P(NVP/Dex)-Ag has been confirmed by fourier transform infrared (FT-IR) spectroscopy. The ultraviolet visible (UV–vis) spectroscopy measurements show a distinct characteristic absorption peaks around 420 nm indicating the formation of silver nanoparticles. The thermogravimetric analysis (TGA) results confirm the increase in thermal stability by incorporation of silver nanoparticles. X-ray diffraction (XRD) analysis and dynamic light scattering (DLS) results demonstrate that the hydrogels have regulated the silver nanoparticles size to a nanoscale with a range between 9.9–15.1 nm and 47.1–73.7 nm respectivelly. The combination of silver nanoparticles with Doxorubicin (DOX) as a model of antitumor drug forms a new biocompatible nano-drug. Our results show that, the mixing of silver nanoparticles with Doxorubicin can effectively increase the antitumor activity and enhance the cytotoxicity.

Sesamol Upregulates Death Receptors and Acts as a Chemosensitizer in Solid Ehrlich Carcinoma Model in Mice

Aims The aim of the present study was to investigate the anti-tumor effect of sesamol (SML), a nutritional phenolic compound of sesame, in solid Ehrlich carcinoma (SEC) model in mice and its ability to enhance doxorubicin (DOX) anti-tumor activity. Moreover, we analyzed the ability of SML to protect against DOX-induced cardiotoxicity. Main methods SML (70 mg/kg), DOX (2 mg/kg) and their combination were given to mice bearing SEC for 21 day. The mRNA level of Fas, FasL, TRAILR2, TRAIL, caspase-3 and Bcl-2 were assessed by qPCR. Tumor and cardiac tissues were examined for histopathological changes by hematoxylin and eosin. Active caspase-3 was scored by immunohistochemical analysis. Key findings SML treatment significantly decreased solid tumor size and weight. In addition, SML enhanced DOX anti-tumor activity. SML treatment either alone or in combination with DOX induced upregulation of Fas/FasL and TRAILR2/TRAIL gene expression. Moreover, SML increased caspase-3 protein and gene expressions and decreased Bcl-2 gene expression. Significance SML upregulates death receptors expression and enhances apoptosis induction in tumor cells that may explain its anti-tumor activity. Not only that, but SML also enhances DOX anti-tumor activity and attenuates its cardiotoxicity.

Synergistic effect of antitumor activity of doxorubicin and bicomponent nanostructures based on aluminum oxide

Introduction. There are high-thech methods of nanoparticle production with controlled morphology and physical and chemical properties. Alumina-based mesoporous nanostructures have low toxicity and biocompatibility. FDI recommends alumina for biomedical application. Alumina inhibits the grow of cancer due to positive zeta-potential and low solubility in water. We observed the synergistic effect of joint application of doxorubicin and nanostructures. This approach reduces drug concentration and its toxicity.Purpose: to synthesize nanostructures with different surface potentials and to study toxicity of these nanostructures alone and in combination with doxorubicin.Material and Methods. The alumina-based nanostructures were obtained by the hydrolysis of nanopowder. The morphology of nanostructures was investigated by transmission electron microscopy with an integrated system of energy dispersive analysis. The phase composition of the particles was determined by x-ray diffraction. The effect of the synthesized nanostructures on the viability of cell lines was determined using the MTT test.Results. The synthesized nanostructures have a low toxicity and can be used as an adjuvant for doxorubicin.Conclusion. The combined use of doxorubicin and bicomponent nanostructures leads to an increase in the damaging effect of doxorubicin on Neuro-2a cells.

Pluronic micelles with suppressing doxorubicin efflux and detoxification for efficiently reversing breast cancer resistance

The antitumor activity of doxorubicin (DOX) is often limited owing to the occurrence of multidrug resistance (MDR) during treatment. Herein, we developed hybrid polymeric micelles, which consisted of pluronic F127 as long-circulating helper in blood, and phenylboronic ester-grafted pluronic P123 (PHE) as efflux and detoxification regulator to efficiently deliver DOX and reverse MDR in vivo. Hybrid F127/PHE micelles exhibited higher stability and drug encapsulation (~80%) than simple F127/P123 micelles due to its lower CMC, and displayed in vitro drug release in a hydrogen peroxide (H2O2)-sensitive manner. Besides, DOX-loaded hybrid micelles (F127/PHE-DOX) possessed higher cell-killing ability and induce more apoptotic in MDR-cells than other groups, which was probably because it not only could greatly increase intracellular drug concentration by inhibiting P-gp mediated drug efflux, but also promote reactive oxygen species (ROS) generation by decreasing glutathione (GSH) levels. Besides, in vivo evaluation indicated that F127/PHE-DOX could well accumulate at tumor regions and exhibit the strongest tumor growth inhibition (TGI 87.87%) accompanied with low side effects. As a result, F127/PHE micelles had great potentials as a platform for anticancer drugs delivery and tumor MDR reversal in clinical application.

Dantrolene Attenuates Cardiotoxicity of Doxorubicin Without Reducing its Antitumor Efficacy in a Breast Cancer Model

Dysregulation of calcium homeostasis is a major mechanism of doxorubicin (DOX)-induced cardiotoxicity. Treatment with DOX causes activation of sarcoplasmic reticulum (SR) ryanodine receptor (RYR) and rapid release of Ca2+ in the cytoplasm resulting in depression of myocardial function. The aim of this study was to examine the effect of dantrolene (DNT) a RYR blocker on both the cardiotoxicity and antitumor activity of DOX in a rat model of breast cancer. Female F344 rats with implanted MAT B III breast cancer cells were randomized to receive intraperitoneal DOX twice per week (12 mg/kg total dose), 5 mg/kg/day oral DNT or a combination of DOX + DNT for 3 weeks. Echocardiography and blood troponin I levels were used to measure myocardial injury. Hearts and tumors were evaluated for histopathological alterations. Blood glutathione was assessed as a measure of oxidative stress. The results showed that DNT improved DOX-induced alterations in the echocardiographic parameters by 50%. Histopathologic analysis of hearts showed reduced DOX induced cardiotoxicity in the group treated with DOX + DNT as shown by reduced interstitial edema, cytoplasmic vacuolization, and myofibrillar disruption, compared with DOX-only–treated hearts. Rats treated with DNT lost less body weight, had higher blood GSH levels and lower troponin I levels than DOX-treated rats. These data indicate that DNT is able to provide protection against DOX cardiotoxicity without reducing its antitumor activity. Further studies are needed to determine the optimal dosing of DNT and DOX in a tumor-bearing host.

Efficient intrahepatic tumor generation by cell sheet transplantation to fabricate orthotopic hepatocarcinoma-bearing model mice for drug testing.

Subcutaneous tumor-bearing mice are commonly used to evaluate antitumor activity in preclinical studies of anticancer drugs. However, these models often exhibit excessive antitumor responses to anticancer drug candidates. In this study, intrahepatic tumor-bearing mice as orthotopic tumor models were fabricated by transplanting hepatocarcinoma cell monolayers (sheets) to investigate differences in ectopic versus orthotopic antitumor response. Cell sheets, harvested from temperature-responsive cell culture dishes using thin gelatin gel supporters, were transferred onto mouse liver surfaces. Cell sheet transplantation drastically improved intrahepatic tumor formation compared with direct intrahepatic injection of dispersed cells. In particular, all cell sheet-transplanted mice formed well-developed tumors inside the liver following removal of the mesothelial membrane at the liver surface. Notably, these mice exhibited comparable life spans, indicating similar intrahepatic tumor development rates. Antitumor activity of doxorubicin (DOX) was examined using both subcutaneous and intrahepatic tumor-bearing mice. Although DOX administration yielded decreased subcutaneous tumor volumes, intrahepatic tumors exhibited no significant antitumor response. The results were considered to represent pharmacokinetic and histological structure differences between ectopic and orthotopic tumors, and partially supported the clinical uses of DOX. Therefore, cancer cell sheet transplantation constitutes a promising method to fabricate intrahepatic tumor-bearing mice for drug screening test in preclinical studies. © 2019 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 107A: 1071-1079, 2019.

Redox-Responsive Dual Drug Delivery Nanosystem Suppresses Cancer Repopulation by Abrogating Doxorubicin-Promoted Cancer Stemness, Metastasis, and Drug Resistance.

Chemotherapy is a major therapeutic option for cancer patients. However, its effectiveness is challenged by chemodrugs' intrinsic pathological interactions with residual cancer cells. While inducing cancer cell death, chemodrugs enhance cancer stemness, invasiveness, and drug resistance of remaining cancer cells through upregulating cyclooxygenase‐2/prostaglandin‐E2 (COX‐2/PGE2) signaling, therefore facilitating cancer repopulation and relapse. Toward tumor eradication, it is necessary to improve chemotherapy by abrogating these chemotherapy‐induced effects. Herein, redox‐responsive, celecoxib‐modified mesoporous silica nanoparticles with poly(β‐cyclodextrin) wrapping (MSCPs) for sealing doxorubicin (DOX) are synthesized. Celecoxib, an FDA‐approved COX‐2 inhibitor, is employed as a structural and functional element to confer MSCPs with redox‐responsiveness and COX‐2/PGE2 inhibitory activity. MSCPs efficiently codeliver DOX and celecoxib into the tumor location, minimizing systemic toxicity. Importantly, through blocking chemotherapy‐activated COX‐2/PGE2 signaling, MSCPs drastically enhance DOX's antitumor activity by suppressing enhancement of cancer stemness and invasiveness as well as drug resistance induced by DOX‐based chemotherapy in vitro. This is also remarkably achieved in three preclinical tumor models in vivo. DOX‐loaded MSCPs effectively inhibit tumor repopulation by blocking COX‐2/PGE2 signaling, which eliminates DOX‐induced expansion of cancer stem‐like cells, distant metastasis, and acquired drug resistance. Thus, this drug delivery nanosystem is capable of effectively suppressing tumor repopulation and has potential clinical translational value.

Impact of N-acetylcysteine on antitumor activity of doxorubicin and landomycin A in NK/Ly lymphoma-bearing mice

Impact of N-acetylcysteine on antitumor activity of doxorubicin and landomycin A in NK/Ly lymphoma-bearing mice

COMPARATIVE STUDY OF ECHINOCHROME A, OXYGENATED CAROTENOIDS, GINSENOSIDE Rh2, LUTEOLIN DISULFATE AND METFORMIN AS A MEAN TO POTENTIATE ANTITUMOR EFFECT OF DOXORUBICIN

This work concerned a comparative study of potentiating effects produced by some drugs of natural origin, as well as metformin, upon antitumor activity of doxorubicin. An increased therapeutic efficacy of doxorubicin used in combination with echinochrome A, oxycarotenoids, ginsenoside Rh2, and metformin was tested in the in vivo Ehrlich ascites carcinoma model. The negative effect of luteolin disulfate (10 mg/kg body weight) upon efficacy of antitumor therapy was revealed. When studying the effect of these substances on the level of intracellular ROS in primary cultures of murine spleen cells, using a selective fluorescent indicator (2’,7’-dichlorofluorescein-diacetate), we did not find a positive correlation between induction of excessive ROS synthesis and potentiation of doxorubicin action with the compounds studied. Some of the studied agents showed a positive correlation between interferon-inducing activity, as well as a negative correlation between increased IL-1 content, and higher antitumor effect of doxorubicin. The obtained results suggest expedience of further studies of antitumor effect potentiation using preparations of echinochrome, ginsenoside Rh2, a mixture of oxygenated carotenoids and metformin.

Abstract B024: PKM2 activation suppresses cellular ROS scavenging capacity and potentiates doxorubicin antitumor activity

Abstract Pyruvate kinase (PK) is a key mediator of the metabolic reprogramming and the Warburg effect observed in tumorigenesis. PK catalyzes the rate-limiting conversion of phosphoenolpyruvate (PEP) to pyruvate in glycolysis. There are fourteen known transcript variants of the PKM gene. In normal adult tissues, the M1 (PKM1) isoform predominates, promoting oxidative phosphorylation and generation of ATP. The M2 (PKM2) isoform, however, and indeed many of the PKM variants other than M1, predominate in tumor tissues. Unlike PKM1, PKM2 exists largely as a less active dimer. The decreased activity of dimer PKM2, relative to PKM1, in this key conversion step leads to an accumulation and shunting of upstream glycolytic intermediates into synthetic pathways needed for the building blocks necessary to maintain continued tumor cell growth. Thus, PKM2 is the focus of intense research into its utility as a target for the treatment of cancer. It has been hypothesized that PKM2 activation should starve cells of necessary building blocks, slowing tumor cell proliferation. We have developed a PKM2 activator, TP-1454, that activates PKM2 in biochemical assays with an AC50 of 11 nM. In cell viability assays, TP-1454 inhibited A549 lung cell growth with an IC50 of 3.4 μM. In conditions where additional nutrients, such as serine, are withdrawn but not growth limiting, TP-1454 inhibited cell growth with an IC50 of 20.3 nM. Consistent with the notion that PKM2 activation leads to a reduction in upstream building blocks, a mass spectrometry metabolomics study showed that TP-1454-induced PKM2 activation modulated several key cellular metabolic components, including key amino acids and glycolytic and citric acid intermediates. However, the single highest-modulated metabolite was glutathione, which was reduced more than 10-fold in treated cells. This finding was also confirmed using a luciferase-based approach with the GSH-Glo glutathione assay. These data led us to hypothesize that PKM2 activation may cause multiple changes in cellular metabolism, but that the greatest vulnerability induced by PKM2 activation was to compromise the cell’s ability to combat reactive oxygen species (ROS) due to the loss of glutathione levels. Therefore, we reasoned that TP-1454 would combine well with drugs known to induce ROS-mediated cell death, such as the anthracyclines. Doxorubicin inhibited A549 cell viability with an IC50 of 173 nM. We observed a four-fold reduction in IC50 of A549 cells treated with 4 μM TP-1454. The antioxidant N-acetyl cysteine partially rescued the synergistic effect of TP-1454 on doxorubicin activity, suggesting that the combination effect was ROS driven. Studies investigating TP-1454-induced glutathione suppression in combination with doxorubicin, in vivo, are currently under way. Taken together, these data support the hypothesis that PKM2 activators may combine well with anthracycline drugs and warrant clinical investigation of PKM2 as a potential therapeutic target for the treatment of multiple cancer types. Citation Format: Peter Peterson, Clifford J. Whatcott, David J. Bearss, Steven L. Warner, Adam Siddiqui-Jain. PKM2 activation suppresses cellular ROS scavenging capacity and potentiates doxorubicin antitumor activity [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2017 Oct 26-30; Philadelphia, PA. Philadelphia (PA): AACR; Mol Cancer Ther 2018;17(1 Suppl):Abstract nr B024.

Inhibition of exosome release by ketotifen enhances sensitivity of cancer cells to doxorubicin

ABSTRACTExosomes released from cancer cells support metastasis and growth of recipient cells and increase their resistance to chemotherapy. Therapeutic targeting of exosomes is a promising area in cancer research. Our aim is to test the effect of the mast cell stabilizer ketotifen on exosomes release from cancer cells and how this can modify their response to doxorubicin. Exosomes release from three cancer cell lines (MCF7, HeLa and BT549) was assessed by scan electron microscope and exosomes quantification kit. Doxorubicin export within exosomes was monitored flurometrically and cellular sensitivity to doxorubicin ± ketotifen was measured by sulphorhodamine-B and colony formation assays. The three cell lines release different amounts of exosomes with the highest quantity released from BT549 followed by MCF7 and then HeLa. Ketotifen (10 µmol L−1) reduced exosomes release in all three cell lines with different efficiency (HeLa>MCF7>BT549). Doxorubicin export via exosomes was highest in BT549, lower in HeLa and lowest in MCF7 cells. Pretreatment with ketotifen sensitized the cells to doxorubicin (HeLa>MCF7>BT549) with a sensitization factor of 27, 8 and 1.25 respectively. Increased sensitivity of cells to doxorubicin by ketotifen was proportional to its effect on exosomes release. Our data is the first report of ketotifen modulating exosomes release from cancer cells and opens the avenue for exosomes-targeting cancer therapy. The differential effects of ketotifen on doxorubicin exosomal export in the cell lines studied, suggests an opportunity of pharmacological enhancement of doxorubicin anti-tumor activity in some but not all cancer types.

Chloroquine upregulates TRAIL/TRAILR2 expression and potentiates doxorubicin anti-tumor activity in thioacetamide-induced hepatocellular carcinoma model

Impaired apoptosis and systemic toxicity of chemotherapeutic drugs make cancer treatment suboptimal. Thus, there is urgency for drug repurposing which facilitates discovery of safe and effective combination therapy. This study aimed to evaluate chloroquine's (CQ) ability to trigger TRAIL/TRAILR2 apoptotic pathway in thioacetamide (TAA)-induced hepatocellular carcinoma (HCC) either alone or in combination with doxorubicin (DOX). Moreover, its ability to attenuate DOX-induced cardiotoxicity was investigated. TAA was injected in male Sprague Dawely rats (200 mg/kg; ip; 2 times/week) for 16 weeks. After the 16th week, rats were further divided into different groups (n = 10) and treated for 7 weeks. CQ group (received CQ 25 mg/kg/day; orally), DOX group (received DOX 1 mg/kg; ip; 2 times/week) and CQ/DOX group. Liver function biomarkers, AFP, hepatic levels of MDA and GSH, serum CK-MB and LDH enzymes activity were measured. Quantitative, Real-Time PCR was used to measure TRAIL, TRAILR2, caspase-8, caspase-9, caspase-3, BCL-2 and TGF-β1 genes expression levels. Necroinflammation and fibrosis were scored by histopathological examination. CQ improved liver functions, reduced AFP level and attenuated HCC progression. CQ induced apoptosis via upregulation of TRAIL/TRAILR2, caspase-8, caspase-3 and caspase-8 genes and downregulation of BCL-2 gene. Moreover, CQ/DOX showed marked decrease in hepatic MDA level, serum CK-MB, LDH enzymes activity, as well as marked increase in hepatic GSH level. In conclusion, this work assess the in vivo efficacy of CQ/DOX combination therapy in this HCC model that not only has enhanced anti-tumor activity but it also protects against DOX-induced cardiotoxicity. Nevertheless, more studies should be performed to illustrate the molecular mechanism of CQ's cardioprotective effect.

INFLUENCE OF METRONIDAZOLE ON BIOLOGICAL ACTION OF DOXORUBICIN

Purpose. Investigation of the effect of the Metronizatol on the biological effect of Doxirubicin.Materials and methods. The studies were performed in the CBA/Lac males and C57Bl/6 females mice grafted with melanoma B16 and mucinous ovarian cancer CaO‑1. Metronidazole and Doxorubicin were used in the work. The antitumor effect was assessed by tumor volume and inhibition of tumor growth.Results. The data obtained indicate that Metronidazole used in oncologic practice for the treatment and prevention of infectious complications, and as a radiosensitizer, can enhance the antitumor effect of Doxorubicin, but this effect is accompanied by a significant increase of the cytostatic toxicity. These effects are leveled by increasing the interval between injections of Metronidazole and Doxorubicin up to 4 hours.Conclusion. The enhancement of the antitumor activity of Doxorubicin under the influence of Metronidazole depends on the interval between the administration of these drugs. When Metronidazole is used in cancer patients, the possibility of enhancing the toxic effect of cytostatics should be considered when they are simultaneously exposed. Patients receiving chemotherapy should be administered antitumor drugs no earlier than 4 hours after exposure to Metronidazole.

Abstract LB-194: Targeting tumor associated myeloid cells with CCR2 inhibitor PF-04136309 enhances gemcitabine/paclitaxel and doxorubicin anti-tumor activity

Abstract Purpose: MDSCs and macrophages have been reported to be increased in the tumor microenvironment by chemotherapy treatment. These cells may limit the beneficial effects of chemotherapy by limiting drug access or by suppressing the tumor targeted immune response evoked by the chemotherapy. The purpose of the current study was to investigate the ability of chemokine receptor CCR2 inhibitor, PF-04136309, to block tumor MDSC and macrophage accumulation and to investigate the combination of this treatment with standard of care chemotherapies. Experimental design: The ability of CCR2 inhibitor, PF-04136309, to reduce tumor growth in mice was evaluated using orthotopically or SC injected syngeneic colon, pancreatic and ovarian tumor cell lines. PF-04136309 was evaluated as single agent, in combination with doxorubicin, or in the combination of gemcitabine and paclitaxel. Results: In a model of ovarian carcinomatosis (ID8), where tumor progression is driven by MDSCs and macrophages, single agent PF-04136309 reduced peritoneal tumor load as well as the total volume and rate of ascites fluid production. Even delayed treatment of established tumors, at 6 weeks post tumor inoculation, was effective. Ascites volume correlated with overall tumor load in treated mice. The treatment of ovarian tumor bearing mice with PF-04136309 in combination with doxorubicin, resulted in significant reduction in tumor load and ascites formation, beyond that produced by doxorubicin alone. To evaluate the addition of PF-04136309 to the chemotherapy combination, gemcitabine/paclitaxel, we selected models of pancreatic (Pan02) and colon (MC38) carcinoma, where PF-04136309 did not show single agent efficacy. The addition of PF-04136309 resulted in significantly decreased tumor burden compared to mice treated with chemotherapy alone. To investigate the mechanism of action of PF-04136309 we selected the MC38 model. PF-04136309 treatment of MC38 tumor bearing mice resulted in a substantial reduction, as a proportion of CD45+ cells, of MDSCs (CD11b+MHCII-Ly6C+) in the circulation (80%), and of MDSCs (60%) and macrophages (CD11b+F4/80+MHCII+Ly6C/G-) (70%) in the tumor, respectively. Conclusion: PF-04136309 significantly improved the response to several chemotherapeutics, providing strong rationale for CCR2 antagonism as an addition to standard of care chemotherapies. PF-04136309 is currently being evaluated in combination with gemcitabine/nab-paclitaxel in metastatic pancreatic cancer patients. The observed inhibitory effect of PF-04136309 on ID8 ascites formation, the synergy with doxorubicin, and the known intervention of MDSC and macrophages in human ovarian peritoneal carcinomatosis, suggests potential clinical efficacy with reduction of ascites volume and synergy in combination with pegylated doxorubicin in platinum resistant ovarian cancer patients. Citation Format: Sasha Farina, Hsunhui Yang, Guang Huan Tu, Erick C. Gamelin, John C. Lin, Changyu Wang, Reid Feldman, Siler Panowski, Cecilia Oderup. Targeting tumor associated myeloid cells with CCR2 inhibitor PF-04136309 enhances gemcitabine/paclitaxel and doxorubicin anti-tumor activity [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr LB-194. doi:10.1158/1538-7445.AM2017-LB-194

Abstract LB-082: Targeted inactivation of STAT3 inhibits proliferation and invasion of breast cancer cells and enhances antitumor activity of doxorubicin through reversion of EMT

Abstract Breast cancer is one of the most common malignant diseases in women. Epithelial-mesenchymal transition (EMT) has been documented to play an important role in proliferation, invasion and metastasis of tumor cells as well as drug resistance. Even though the signal transducer and activator of transcription 3 (STAT3) is not a master transcription factor of EMT, STAT3 is involved in the regulation of EMT-related gene expression. However, it remains unclear whether targeted inhibitors of STAT3 affect EMT-mediated proliferation, migration, invasion and drug resistance of tumor cells. In this paper, we investigated the effects of STAT3 and its interaction with Twist, a master transcription factor, in EMT program and subsequent changes in proliferation, migration and invasion of breast cancer cells by interfering STAT3 signaling pathway with different strategies such as STAT3 inactivation and STAT3 silencing. Furthermore, we explored the role of inhibiting STAT3 phosphorylation in the EMT regulation of the sensitivity of tumor cells response to doxorubicin. The results showed that the expression and activation of STAT3 correlated with cell phenotype and invasive ability of breast cancer cells. IL-6 induced phosphorylation of STAT3 can promote the EMT of breast cancer cells. WP1066 completely inhibited STAT3 autophosphorylation and IL-6-induced phosphorylation in breast cancer cells. WP1066 reversed EMT to MET through inhibiting the phosphorylation of STAT3 in breast cancer cells and significantly inhibited the proliferation and invasion in breast cancer cells. Silence STAT3 with siRNA also reversed EMT to MET in breast cancer cells. The expression of EMT transcription factor Twist1 was positively correlated with the activation of STAT3 but not with the expression of STAT3. WP1066 increased doxorubicin antitumor activity through inhibiting the STAT3 phosphorylation. These data provide a proof of concept that targeted inactivation of STAT3 can inhibit proliferation and invasion of breast cancer cells and reduce the resistance of Doxorubicin through reversion of EMT. Support by Natural Science Foundation of China (No.81472489) and Science and Technology Development Plan of Shandong (No.2014GSF118040) Citation Format: Yi Ding, Yu Jiang, Wenqing Li, Shurong Liu, Zhong Lu, Lihong Shi, Xuejian Wang, Jian Zhang, Lihua Wang. Targeted inactivation of STAT3 inhibits proliferation and invasion of breast cancer cells and enhances antitumor activity of doxorubicin through reversion of EMT [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr LB-082. doi:10.1158/1538-7445.AM2017-LB-082

Suppression of ABCG2 mediated MDR in vitro and in vivo by a novel inhibitor of ABCG2 drug transport

Cancer is a disease whose treatment is often limited due to the development of a phenomenon known as multidrug resistance (MDR). There is an immense demand for development of novel agents that can overcome the MDR in cancer. A group of transmembrane proteins called ATP-binding cassette transporters, present ubiquitously in the human body possesses a modular architecture, contributing immensely towards the development of MDR. An analysis of structural congeners among a group of compounds led to the discovery of CCTA-1523 that could selectively reverse ABCG2-mediated MDR in cancer cells in vitro and in vivo. CCTA-1523 (5μM) sensitized the ABCG2 overexpressing cancer cells and ABCG2 transfected cells to the substrate chemotherapeutic drugs. The reversal ability of CCTA-1523 was primarily due to the inhibition of the efflux function of ABCG2; also there was no change in the protein expression or the localization of the ABCG2 in the presence of CCTA-1523. The reversal effect of CCTA-1523 was reversible. Importantly, co-administration of CCTA-1523 restored the in vivo antitumor activity of doxorubicin in ABCG2 overexpressing tumor xenografts. Taken together, our findings indicate that CCTA-1523 is a potent, selective and reversible modulator of ABCG2 that may offer therapeutic promise for multidrug- resistant malignancies.