Anticancer Effect Of Doxorubicin Research Articles

Harpagoside Protects Against Doxorubicin-Induced Cardiotoxicity via P53-Parkin-Mediated Mitophagy

Doxorubicin (DOX) is one of the most effective chemotherapeutic agents. However, its clinical use is limited due to the severe risk of cardiotoxicity. One of the hallmarks of doxorubicin-induced cardiotoxicity (DICT) is the cascade of mitophagy deficiency-mitochondrial oxidative injury-apoptosis, while so far, there is no preventive strategy for alleviating DICT by targeting this molecular mechanism. Excitedly, based on our previous drug screen in DICT zebrafish model, harpagoside (HAR) showed dramatic anti-DICT efficacy superior to dexrazoxane (DXZ) only cardioprotectant approved by FDA. Therefore, its pharmacological effects and molecular mechanism on DICT mouse and rat cardiomyocytes were further discussed. In vivo, HAR significantly improved cardiac function and myocardial structural lesions with concomitant of diminished mitochondrial oxidative damage and recovered mitophagy flux. In parallel, HAR protected mitophagy and mitochondria homeostasis, and repressed apoptosis in vitro. Intriguingly, both nutlin-3 (agonist of p53) and Parkin siRNA reversed these protective effects of HAR. Additional data, including fluorescence colocalization of Parkin and MitoTracker and mt-Keima for the detection of mitophagy flux and coimmunoprecipitation of p53 and Parkin, showed that HAR promoted Parkin translocation to mitochondria and substantially restored Parkin-mediated mitophagy by inhibiting the binding of p53 and Parkin. Importantly, the results of the cell viability demonstrated that cardioprotective effect of HAR did not interfere with anticancer effect of DOX on MCF-7 and HepG2 cells. Our research documented p53-Parkin-mediated cascade of mitophagy deficiency-mitochondrial dyshomeostasis-apoptosis as a pathogenic mechanism and druggable pathway and HAR as a cardioprotection on DICT by acting on novel interaction between p53 and Parkin.

Algerian propolis: between protection of normal cells and potentialisation of the anticancer effects of doxorubicin against breast cancer cells via P-glycoprotein inhibition and cell cycle arrest in the S phase.

Breast cancer is a common cancer and is the leading cause of cancer-related deaths among women worldwide. Studies have shown that breast cancer is a heterogeneous tumor with varying response to treatments. The clinical use of doxorubicin (Dox) in the treatment of cancer is limited by its cardiotoxicity which results in often fatal heart failure and the development of multidrug resistance. Therefore, new therapeutic strategies and targets are underscored. Propolis has been reported to show a broad spectrum of biological activities including anticancer activity. In this study, we investigated the role of propolis on the antitumor effects of Dox on breast cancer cells (MDA-MB-231) and its ability to provide protection against Dox-mediated damage on normal cells (MRC-5). Modifications in cell viability, apoptosis induction, cell cycle progression and permeability glycoprotein (P-gp) activity of breast cancer cells in vitro were evaluated. Propolis combined with Dox inhibited cell growth in a dose dependent manner by inducing cell cycle arrest in the S phase and caspase-dependent apoptosis. In the presence of propolis, the IC50 of Dox against MDA-MB-231 cells decreased by 10-fold. The increased sensitivity of cancer cells to the combined treatment was explained by the capacity of propolis to cause a significant increase in Dox content in MDA-MB-231. Very interestingly, Algerian propolis showed its ability to inhibit efficiently P-gp function in comparison with verapamil, reference P-gp modulator, which proves the efficacy of propolis to reverse the problem of multidrug resistance. Our results showed also that propolis could protect normal cells from deleterious effects of Dox by amelioration of cell viability. In conclusion, the obtained results indicate that Algerian propolis potentiated the antitumor effects of Dox on breast cancer cells and could reduce the problem of multidrug resistance. Therefore, Algerian propolis may be an effective agent in a combined treatment with Dox for increased therapeutic efficacy against breast cancer. Clinically, our results are relevant because with this combined therapy it may be possible to counter the problem of cancer cell resistance while reducing the problem of toxicity on normal cells.

Smart responsive nanoplatform via in situ forming disulfiram-copper ion chelation complex for cancer combination chemotherapy

Smart responsive nanomedicines serving as carriers can take advantage of the specific tumor microenvironment (TME) to convert non-toxic drugs into effective anticarcinogens and release chemotherapeutic drugs in situ to improve therapeutic efficiency against tumors without inducing off-target toxicity to surrounding normal tissues/cells. Herein, a pH-responsive metal-organic framework nanoparticle is constructed by encapsulating disulfiram (DSF) and doxorubicin (DOX) into the zeolitic imidazolate framework-8 (ZIF-8) and then coating with copper ion (Cu2+)-tannic acid (TA) complex (denoted as DSF/DOX@ZIF-8@Cu-TA) to achieve enhanced combination chemotherapy. The release of Cu2+ from the outer shell of DSF/DOX@ZIF-8@Cu-TA and the cooperative exposure of DSF and DOX are triggered at multiple stages by mild acidity TME. The accumulation of DSF (non-toxic drugs) and Cu2+ results in the rapid formation of high cytotoxic bis(N, N-diethyl dithiocarbamato)-Cu2+ complexes (CuL2) in situ via DSF and Cu2+ chelating reaction, which accompany the production of ROS via Cu+-based Fenton-like reaction. Besides, the anticancer effect of DOX is augmented by CuL2-modulated ROS-MAPK and NF-κB signal pathways. The constructed DSF/DOX@ZIF-8@Cu-TA present significantly improved therapeutic efficiency as demonstrated both in vitro and in vivo. The strategy of nontoxicity-to-toxicity transitions with the addictive effect of chemotherapeutics provides a promising paradigm to design novel nanoplatforms for synergistic cancer chemotherapy.

Inhibition of SIRT6 potentiates the anti-tumor effect of doxorubicin through suppression of the DNA damage repair pathway in osteosarcoma

BackgroundSIRT6 has diverse roles in cells, and the role of SIRT6 in tumorigenesis is controversial. Considering the role of SIRT6 as an inducer of DNA damage repair, it might be involved in resistance to anti-cancer therapy.MethodsWe evaluated the prognostic significance of SIRT6 in 37 osteosarcomas and investigated the therapeutic efficacy of SIRT6 on the anticancer effects of doxorubicin, olaparib, and ATM inhibitor.ResultsImmunohistochemical expression of SIRT6 was significantly associated with shorter overall survival and relapse-free survival of osteosarcoma patients, especially in patients who received adjuvant chemotherapy. In U2OS and KHOS/NP osteosarcoma cells, knock-down of SIRT6 significantly potentiated apoptotic effects of doxorubicin and SIRT6 overexpression induced resistance to doxorubicin. Moreover, SIRT6 induced the DNA damage repair pathway and SIRT6-mediated resistance to doxorubicin was attenuated by blocking the DNA damage repair pathway with olaparib and ATM inhibitor.ConclusionsThis study suggests that suppression of SIRT6 in combination with doxorubicin might be an effective modality in the treatment of osteosarcoma patients, especially for osteosarcomas with shorter survival with high expression of SIRT6.

GSK‑3β inhibition promotes doxorubicin‑induced apoptosis in human cholangiocarcinoma cells via FAK/AKT inhibition.

Cholangiocarcinoma (CCA) is the most common type of malignant tumor of the bile duct and is characterized by high morbidity and mortality; it is difficult to diagnose in the early stages and responds poorly to current conventional radiotherapy and chemotherapy. The present study investigated the role of GSK‑3β signaling on the anticancer effects of doxorubicin in human CCA cells. Blocking GSK‑3β enhanced the sensitivity of human CCA cells to doxorubicin (Dox)‑induced apoptosis, which was accompanied by decreased AKT and focal adhesion kinase (FAK) activity. Moreover, inhibiting GSK‑3β using 6‑bromoindirubin‑3'‑oxime, CHIR99021 or small interfering RNA decreased phosphorylation of FAK and AKT, and promoted apoptosis of Dox‑induced human CCA cells. Moreover, FAK inhibition suppressed AKT activity independently of phosphoinositide 3‑kinase activity. These results indicated that GSK‑3β protects human CCA cells against Dox‑induced apoptosis via sustaining FAK/AKT activity.

The beneficial effects of reducing NLRP3 inflammasome activation in the cardiotoxicity and the anti-cancer effects of doxorubicin.

Doxorubicin (DOX) is a powerful broad-spectrum anti-neoplastic anthracycline antibiotic. However, DOX may cause a dose-dependent cardiotoxicity that can eventually progress to congestive heart failure and death. Numerous molecular mechanisms have been implicated in the cardiotoxic effect of DOX including topoisomerase IIβ and generation of free radicals. However, targeting these pathways appears to be insufficient to mitigate the cardiotoxic effects of DOX and/or ultimately reduces the anti-tumor activity of DOX. Thus, there remains a crucial need to identify novel pharmacological targets that can alleviate the cardiotoxic effects of DOX without reducing its anti-tumor activity. Recent studies have suggested thatthe Nucleotide-Binding Domain-Like Receptor Protein 3 (NLRP3) inflammasome is implicated in tumor progression and the chemoresistance of cancer cells to DOX. Of interest, reducing NLRP3 inflammasome activity alleviates DOX-induced cardiotoxicity. Therefore, we postulate that strategies that targetthe NLRP3 inflammasome can help mitigate the cardiotoxic effects of DOX while maintaining and/or even enhancing its anti-cancer activity. Herein, we review the current knowledge about the potential implication ofthe NLRP3 inflammasome in the anti-cancer and cardiotoxic effects of DOX.

Nanoformulated Ajwa (Phoenix Dactylifera) Bioactive Compounds Improve the Safety of Doxorubicin without Compromising its Anticancer Efficacy in Breast Cancer.

One of the major causes of women’s death in the world is breast cancer. Consequently, numerous regimens for the control of this severe disease have been created. The chemotherapeutic agent doxorubicin (DOX) is frequently used to treat breast cancer, but DOX can also cause cardiotoxic effects that lead to heart failure. Therefore, many research studies have been done to find a natural product that effectively potentiates or does not interfere with DOX’s anticancer effect and protects against its cardiotoxicity. We studied the impact of combined nanoformulated Ajwa (Phoenix dactylifera) selected bioactive compounds (BAC) rutin (R) and quercetin (Q) in nude mice breast cancer xenografts on DOX-mediated anticancer efficacy. We also studied if this Ajwa BAC could safeguard against DOX-mediated cardiomyopathies by evaluating plasma cardiac troponin-I (cTn-I) levels and cardiac histopathology. Nanoformulated Ajwa BAC effectively alleviated weight loss induced by DOX in mice and significantly decreased the elevated cTn-I. Furthermore, 5 mg RQ-NPs/kg of nude mice that subcutaneously daily injected for 11 days, attenuated the histopathological alterations induced in cardiac muscles due to DOX without any interference with the anticancer effects of DOX against breast cancer.

The Role of Nuclear Receptor Subfamily 1 Group H Member 4 (NR1H4) in Colon Cancer Cell Survival through the Regulation of c-Myc Stability.

Nuclear receptor subfamily group H member 4 (NR1H4), also known as farnesoid X receptor, has been implicated in several cellular processes in the liver and intestine. Preclinical and clinical studies have suggested a role of NR1H4 in colon cancer development; however, how NR1H4 regulates colon cancer cell growth and survival remains unclear. We generated NR1H4 knockout (KO) colon cancer cells using clustered regularly interspaced short palindromic repeats (CRISPR)-CRISPR-associated protein-9 nuclease (CAS9) technology and explored the effects of NR1H4 KO in colon cancer cell proliferation, survival, and apoptosis. Interestingly, NR1H4 KO cells showed impaired cell proliferation, reduced colony formation, and increased apoptotic cell death compared to control colon cancer cells. We identified MYC as an important mediator of the signaling pathway alterations induced by NR1H4 KO. NR1H4 silencing in colon cancer cells resulted in reduced MYC protein levels, while NR1H4 activation using an NR1H4 ligand, chenodeoxycholic acid, resulted in time- and dose-dependent MYC induction. Moreover, NR1H4 KO enhanced the anti-cancer effects of doxorubicin and cisplatin, supporting the role of MYC in the enhanced apoptosis observed in NR1H4 KO cells. Taken together, our findings suggest that modulating NR1H4 activity in colon cancer cells might be a promising alternative approach to treat cancer using MYC-targeting agents.

Anti-cancer effect of doxorubicin is mediated by downregulation of HMG-Co A reductase via inhibition of EGFR/Src pathway

Doxorubicin is a widely used DNA damage-inducing anti-cancer drug. However, its use is limited by its dose-dependent side effects, such as cardiac toxicity. Cholesterol-lowering statin drugs increase the efficacy of some anti-cancer drugs. Cholesterol is important for cell growth and a critical component of lipid rafts, which are plasma membrane microdomains important for cell signaling. 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase (HMG-CR) is a critical enzyme in cholesterol synthesis. Here, we show that doxorubicin downregulated HMG-CR protein levels and thus reduced levels of cholesterol and lipid rafts. Cholesterol addition attenuated doxorubicin-induced cell death, and cholesterol depletion enhanced it. Reduction of HMG-CR activity by simvastatin, a statin that acts as an HMG-CR inhibitor, or by siRNA-mediated HMG-CR knockdown enhanced doxorubicin cytotoxicity. Doxorubicin-induced HMG-CR downregulation was associated with inactivation of the EGFR-Src pathway. Furthermore, a high-cholesterol-diet attenuated the anti-cancer activity of doxorubicin in a tumor xenograft mouse model. In a multivulva model of Caenorhabditis elegans expressing an active-EGFR mutant, doxorubicin decreased hyperplasia more efficiently in the absence than in the presence of cholesterol. These data indicate that EGFR/Src/HMG-CR is a new pathway mediating doxorubicin-induced cell death and that cholesterol control could be combined with doxorubicin treatment to enhance efficacy and thus reduce side effects.

Abstract 3531: Glycolysis inhibition and its effect in doxorubicin resistance in neuroblastoma

Abstract Most cancer cells exhibit increased glycolysis and use this metabolic pathway to generate ATP (Adenosine triphosphate) as the main source of their energy supply. This phenomenon is known as the Warburg effect and is considered a fundamental metabolic alteration during malignant transformation. Increased glycolysis results in elevated production of lactate, which leads to acidification of tumor tissue and provides a microenvironment that promotes and selects cellular resistance to drugs. Thus, inhibition of glycolysis may lead to more effective treatment strategies for dealing with drug resistance. 3-Bromopyruvate (3-BrPA), an inhibitor of hexokinase II and an inhibitor of glycolysis, has been shown to be a potent chemotherapeutic agent. Despite many studies showing the efficacy of 3-BrPA against various cancer cells, there have been relatively few studies examining the effects of 3-BrPA on the anti-cancer effects of doxorubicin (Dox) in doxorubicin-resistant (DoxR) human neuroblastoma. The purpose of this study is to examine the effects of 3-BrPA upon DoxR human neuroblastoma cells to treatment with doxorubicin. In present study, we have found that 3-BrPA enhances the response of DoxR neuroblastoma to treatment with Dox and this enhancement exists in both normoxic conditions as well as hypoxic conditions. The results also suggested that this increased response of DoxR cells to treatment with Dox is mediated through decreased intracellular levels of ATP. Additionally the lactate assay revealed that intracellular lactate levels were decreased in neuroblastoma lines when glycolysis was inhibited with 3-BrPA. In order to determine if 3-BrPA, either alone or in combination with cytotoxic drugs, will lead to maximal efficacy of treating of drug-resistant tumor xenografts in vivo. Animal experiments were carried out to study the effects of 3-BrPA in drug-resistant neuroblastoma in nude mice. We have found that 3-BrPA combined with doxorubicin provided significant reduction in tumor size and the rate of tumor growth in mice. The efficacy of doxorubicin itself (88% reduction in tumor volume) overshadowed any effect of cotreatment with 3-BrPA on the Wild type tumors. However, in the DoxR tumors, doxorubicin alone had no efficacy as expected, but co-treatment with 3-BrPA suppressed tumor growth with an 80% reduction in tumor volume. These studies pave the way to determine whether inhibition of glycolysis may be an effective strategy to kill neuroblastoma cells and overcome drug resistance associated with hypoxic conditions. This novel approach may have broad applications in cancer treatment, considering the prevalent Warburg effect observed in a wide array of human cancers. Citation Format: Fei Chu, Yiyong Qiu, Sandra Clark, Kathryn Solka, Mary Beth Madonna. Glycolysis inhibition and its effect in doxorubicin resistance in neuroblastoma [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 3531.

Abstract P3-06-07: Combination of doxorubicin with S1P signaling modulator FTY720 significantly suppressed obesity-associated breast cancer

Abstract Background: Obesity is one of the biggest health issues in the US. It has been shown that obesity-associated breast cancer is more aggressive with poor prognosis, which is partly explained by the low-grade inflammation caused by obesity. Recently we have published that sphingosine-1-phosphate (S1P), a signaling lipid mediator, link inflammation and cancer in colitis-associated colon cancer model. We hypothesized that addition of S1P modulator that block S1P signaling thus suppress the effect of obesity-mediated inflammation should enhance anti-cancer effect of doxorubicin, which is a typical anti-cancer drug for breast cancer used as a standard of care. Methods: Female B6.cg-Lepob (OB/OB) mice fed with high fat diet for 2 weeks prior to implantation of cancer cells were used as an obesity model, and litter mate control mice fed with normal diet were used as a control. 1 x 106 murine mammary adenocarcinoma E0771 cells were inoculated into #2 rt. fat pads as previously described (Katsuta et al JSR 2016). 9 days after inoculation, both OB/OB and control mice were randomized into 4 groups in each group; vehicle, Doxorubicin, FTY720 and Combination of Doxorubicin and FTY720. Doxorubicin was administrated by i.p. injection at a dose of 5 mg/kg on Day 0 and 3. FTY720 was administered everyday by gavage at a dose of 1 mg/kg during the entire course. Tumor growths were measured daily by caliper measurements. Tumor weights were measured on 21 days after cell inoculation. Results: The body weight of obesity model was significantly heavier than control mice at the time of cancer cell inoculation (44.1 g vs 19.4 g; p < 0.001). In non-treatment group, tumor weight in obesity group was significant heavier than control mice[KT1] (1232 mg vs 966 mg; p = 0.049), which is consistent with the dogma that obesity worsen cancer progression. As expected, tumor weight in non-treatment group is heavier than any treatment group, and that in combination treatment of doxorubicin and FTY720 is lightest in both of obesity group and control group. Interestingly, tumor reduction rate in obesity group compared with non-treatment group is significant greater than control group (Doxorubicin: 83% vs 19%, p = 0.001; FTY720: 80% vs 46%, p = 0.027, Doxorubicin + FTY720: 93% vs 64%, p = 0.011). Over 15 % weight loss were seen in obesity doxorubicin group and obesity combination treatment group. Conclusion: Modification of S1P signaling by FTY720 was shown to enhance the effect of doxorubicin particularly in obese mice, which implicate a novel approach to treat obesity-associated breast cancer. Citation Format: Katsuta E, Takabe K. Combination of doxorubicin with S1P signaling modulator FTY720 significantly suppressed obesity-associated breast cancer [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr P3-06-07.

Abstract 2066: Albumin-binding doxorubicin prodrug selectively activated by radiation-induced apoptotic tumor cells

Abstract Despite the well-recognized potent anticancer effect of doxorubicin, the clinical use of doxorubicin is limited due to its dose-dependent toxicity. In this study, a novel drug delivery technology fundamentally different from the conventional tumor-targeting approaches was employed to improve the therapeutic index of doxorubicin. The prepared doxorubicin prodrug, EMC-DEVD-S-DOX, has two distinct features for effective tumor targeting: EPR effect-mediated passive targeting of tumor and extended plasma half-life by in situ albumin binding, and radiation-induced apoptosis targeting. The prodrug comprises of two important functional molecules: first, a maleimide group that allows in situ binding of the prodrug to the circulating albumin after intravenous administration; second, a DEVD motif that plays a crucial role in the activation of the prodrug through caspase-3-mediated cleavage in the apoptotic tumor cells that are exposed to radiation. As a result, EMC-DEVD-S-DOX showed a prolonged plasma half-life with selective accumulation within the tumor tissue, and was only activated and released free doxorubicin when combined with radiotherapy, thereby showing excellent synergistic effect. Our suggested drug delivery strategy completely relies on the anatomical feature of tumor vasculatures and the upregulated caspase-3 after exposure to radiation. In this reason, the genomic variations of tumor cells are unlikely to influence the efficacy of the prodrug. Considering that the conventional active tumor targeting approach is seriously challenged by the intratumor heterogeneity, EMC-DEVD-S-DOX could be an outstanding alternative for an effective cancer treatment. Citation Format: Seung Woo Chung, Kwangmeyung Kim, Seong Who Kim, In-San Kim, Sang Yoon Kim, Youngro Byun. Albumin-binding doxorubicin prodrug selectively activated by radiation-induced apoptotic tumor cells. [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 2066.

Abstract 735: Honokiol enhances the anticancer effects of doxorubicin by regulating Mucin 1 and Multidrug resistance-associated protein 1 (MRP1) in mammary carcinoma MDA-MB-231 cells

Abstract Although great progress has been made in the treatment of breast cancer, resistance to chemotherapeutic drugs is a problem facing current cancer research, promoting the need to understand the molecular mechanisms involved in breast cancer and identify future targeted therapy. One of the mechanisms by which chemoresistance is attained in cancer cells is mediated through the expression of MDR-related proteins (MRPs). These transmembrane proteins efflux drugs across the plasma membrane, conferring resistance of cancer cells to anticancer drugs. Acquiring drug resistance has been correlated to the emergence of metastasis, accounting for two factors that may be related to progression of the disease. One of the diagnostic markers of metastatic progression is Mucin 1 (MUC1), an oncoprotein which has been implicated in reduced survival rate. Interaction of MUC1 with MRP-1 promotes resistance to conventional chemotherapeutic drugs. While several inhibitors have been identified and characterized to overcome drug resistance, thus far none of these have led to effectively managing acquired drug resistance. Along with existing drug treatments for breast cancer, the focus of clinicians and researchers have shifted towards exploring natural products to treat alone or in combination with chemotherapeutic agents to enhance the efficacy of these drugs in cancer. One such compound is honokiol, a natural phenolic compound extracted from Magnolia grandiflora that suppresses breast carcinogenesis in vitro and in vivo. The purpose of the current study is to determine whether honokiol regulates MUC1 and MRP1 in mammary carcinoma cells, MDA-MB-231, and the role of honokiol to enhance the efficacy of chemotherapeutic agent, doxorubicin. We investigated the effects of honokiol on the expression of MUC1 and MRP1 in MDA-MB-231 cells by RT-PCR and Immunoblotting. Cell proliferation assays (MTT-(3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide) were used to study the effect of honokiol on doxorubicin-mediated growth suppression. Honokiol suppressed mRNA and protein expression levels of MUC1 and MRP1 in MDA-MB-231 cells. In addition, honokiol suppressed the growth of mammary carcinoma MDA-MB-231 cells, and enhanced the efficacy of doxorubicin-mediated mammary carcinoma growth suppression. Taken together, suppressing the expression level of MUC1 and MRP1 by honokiol enhances the effect of conventional chemotherapeutic drugs. Citation Format: Padmamalini Thulasiraman, Saad Alshareedah. Honokiol enhances the anticancer effects of doxorubicin by regulating Mucin 1 and Multidrug resistance-associated protein 1 (MRP1) in mammary carcinoma MDA-MB-231 cells. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 735. doi:10.1158/1538-7445.AM2015-735

Anti-cancer effects of novel doxorubicin prodrug PDOX in MCF-7 breast cancer cells.

Ac-Phe-Lys-PABC-DOX (PDOX) is a smart doxorubicin (DOX) prodrug designed to decrease toxicities while maintaining the potent anticancer effects of DOX. This study was aimed at elucidating the effectiveness and toxicities of DOX and PDOX in patient-derived MCF-7 breast cancer cells in vitro. The MCF-7 cells were exposed to both PDOX and DOX, and cytotoxicities, cell cycle and P53/P21 signaling alterations were studied. Abundant cathepsin B was found in the MCF-7 cells, and treatment with PDOX and DOX triggered dose- and time-dependent cytotoxicity and resulted in a significant reduction in cell viability. The IC50 of PDOX and DOX was 3.91 and 0.94 μmol/L, respectively. Both PDOX and DOX caused an up-regulation of the P53/P21-related signal pathway, and PDOX significantly increased expression of P53 and caspase 3, and arrested the cell cycle at the G1/G2 phase. As compared with DOX, PDOX reduced toxicities, and it may have different action mechanisms on breast cancer cells.

Abstract 5643: Role of leptin-induced Notch-Wnt crosstalk in proliferation/survival of triple negative breast cancer cells.

Abstract Obese African American and Latina women show the high mortality rate linked to triple negative breast cancer, TNBC. The disease is commonly detected at more advance degree and associated with resistance to common therapeutic treatments. Obesity, characterized by high levels of leptin, has consistently been associated with many different cancers including breast cancer. We hypothesize that leptin signaling is instrumental in the increased proliferation and survival of breast cancer cells, which is mediated through a crosstalk between the Notch and Wnt signaling pathways. We further hypothesized that these leptin actions are more evident in TNBC cells. Objective/Methods: The effects of leptin-Notch-Wnt crosstalk on the proliferation and survival (MTT-Vybrant assay and Annexin V-flow cytometry) of breast cancer cells responsive to estrogen (MCF-7 and T47D) and TNBC (MDA-MB231 and HC1806) were investigated. The cells were treated with agonists and inhibitors of leptin-Notch-Wnt axis [i.e., leptin, Wnt1, JAG1/14-mer peptide and leptin peptide receptor antagonist 2 (LPrA2), g-secretase inhibitor and Wif]. The expression of Notch and Wnt signaling components (ligands/receptors) and levels of cyclin D1 and myc were also determined via western blot and real-time RT-PCR. In a series of experiments the cells were treated with chemotherapeutic drugs, doxorubicin and cisplatin plus leptin and the activation of caspase 3, levels of Bcl-2 and, the drug resistance marker (multidrug resistance-associated protein 1, ABCC1/MRP1) were determined using as control the etoposide resistant MCF-7/VP cell line. The relative expression of leptin, Notch and Wnt systems in breast cancer tissue arrays (n=150; Pantomics) was also investigated. Results: Leptin induced significant increase of TNBC cell proliferation, cyclin D1, bcl-2, ABCC1 and Notch/Wnt axis. Leptin also decreased the anti-cancer effects of doxorubicin and cisplatin, which were related to leptin upregulation on Notch-Wnt crosstalk. HScore analyses of breast cancer tissue arrays showed significant correlation of the expression of leptin-targeted proteins (Notch and Wnt) in breast cancer tissues. These results suggest that leptin can induce the crosstalk between Notch and Wnt and breast cancer progression. Conclusions: Targeting leptin-Notch-Wnt signaling axis could be a new strategy to treat and/or prevent breast cancer. The inhibition of leptin signaling could be a promising new way to target the most deadly TBNC, especially in obese patients. Acknowledgments: This work was supported by NIH/NCI 5SC1CA138658-04, Georgia Cancer Coalition Distinguished Cancer Scholar Award (to RRGP), NIH/2G12RR003034-26 and U54 MSM/TU/UAB Cancer Center Partnership, and NIH/NIGMS R25 GM058268. This research was also supported, in part, facilities and support services at Morehouse School of Medicine (NIH 1C06 RR18386). Citation Format: Tanisha Z. McGlothen, Corey Gillespie, Krysta Greenleaf, Movado Long, Laronna S. Colbert, Gary L. Sanford, Ruben R. Gonzalez-Perez. Role of leptin-induced Notch-Wnt crosstalk in proliferation/survival of triple negative breast cancer cells. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 5643. doi:10.1158/1538-7445.AM2013-5643

Abstract 1698: Resveratrol potentiates the cytotoxic profile of docetaxel and doxorubicin via inhibiting the activity and expression of p-glycoprotein molecules

Abstract P-glycoprotein is membrane protein highly abundant in tumor cells which facilitate the effluxes of several chemotherapeutic agents to the extracellular compartment. Several P-glycoprotein blockers of synthetic origin were suggested as adjuvant therapy for cancer; however, manifested several toxic side effects. Resveratrol was found to block p-glycoprotein with potential use as adjuvant therapy for several p-glycoprotein substrates such as docetaxel and doxorubicin. Herein, we have assessed the interactive characteristics of resveratrol with docetaxel and doxorubicin and further investigated the molecular bases of this interaction in three different solid tumor cell lines (MCF-7, HeLa and HepG2). Resveratrol per se was found to possess anti-cancer properties; however with relatively low potency in all tested cell lines (IC50 ranges from 8.0 to 19.1µg/ml). Doxorubicin and docetaxel showed IC50‘s ranged from 0.28 to 0.42 µg/ml and from 22.3 to 67.1 ng/ml, respectively. Resveratrol combination with doxorubicin and docetaxel significantly increased the potencies of both chemotherapeutic agents showing IC50‘s ranging from 0.07 to 0.2 µg/ml and from 6.2 to 45.7 ng/ml, respectively. The combination index showed synergistic interaction between resveratrol and doxorubicin or docetaxel in MCF-7 cell line, while additive interaction in HeLa and Hep-G2 cell lines. Real time PCR revealed that the expression of BAX and BcL2 were simultaneously elevated due to combination of resveratrol with doxorubicin or docetaxel in all tested cell lines while p-53 showed marginal elevation in MCF-7 and HepG2 cell lines. The p-glycoprotein efflux activity was significantly inhibited with subsequent accumulation of p-glycoprotein substrate within the intracellular compartment of all tested cell lines. Also the expression level of mdr1 gene was down regulated after resveratrol combination with doxorubicin or docetaxel in all tested cell lines. In conclusion, resveratrol potentiates the anti-cancer effects of doxorubicin and docetaxel via increasing their intracellular level due to p-glycoprotein activity inhibition and down regulation of mdr1 gene. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 1698. doi:10.1158/1538-7445.AM2011-1698

High-throughput RNAi screening identifies sensitizing targets to improve doxorubicin chemotherapy

9543 Treatment of cancer often involves the use of chemotherapeutic agents that preferentially target tumor cells. Doxorubicin is an anthracycline antibiotic that induces an anticancer effect through intercalation into DNA, and inhibition of topoisomerase II. However, not all patients benefit from doxorubicin therapy and heterogeneity in the response to this agent has limited its clinical efficacy. In order to improve the efficiency of doxorubicin in a greater number of patients, we used RNA interference (RNAi) knockdown experiments to determine the extent to which a change in gene expression can increase cellular sensitivity to the anticancer effects of doxorubicin. RNAi is a naturally occurring mechanism that can be experimentally exploited by introducing double-stranded RNA molecules of ∼21 base pairs termed short interfering RNAs (siRNAs) into cells to achieve sequence specific silence of gene expression. We have applied high-throughput RNAi analysis using a library of 83 siRNAs against 40 cancer-asso...

Pharmacokinetics and antitumor effect of doxorubicin carried by stealth and remote loading proliposome.

The aim of the study was to prepare stealth and remote loading proliposome (SRP-L) to carry doxorubicin (DXR) and evaluate the pharmacokinetics, acute toxicity, and anticancer effect of DXR carried with SRP-L. SRP-L was transparent solution. When SRP-L was injected into 0.9%, NaCl aqueous solution containing DXR. liposomes formed and automatically loaded DXR (SRP-L-DXR). The long circulation of SRP-L-DXR was evaluated using the pharmacokinetics of SRP-L-DXR. cardiolipin liposomal DXR (CL-DXR) and free DXR (F-DXR). The acute toxicity and anticancer effect of SRP-L-DXR were evaluated in C57BL/6 mice and murine hystocytoma M5076 tumor model. The average diameter of SRP-L-DXR in pure water was 112.9 +/- 8.6 (nm) and the encapsulation efficiency of SRP-L-DXR was 96.5 +/- 0.2% in pure water, 95.5 +/- 0.1% in 5% glucose and 98.01 +/- 0.6% in 0.9% NaCl. The plasma concentration of SRP-L-DXR was much higher than those of F-DXR and CL-DXR. Compared with that of F-DXR, the SRP-L-DXR had lower acute toxicity and its anticancer effects depended upon the therapeutic treatment. A novel proliposome (SRP-L) was developed, which could automatically load DXR and form SRP-L-DXR with excellent characteristics. SRP-L-DXR had lower acute toxicity but was not always more effective for the treatment of the ascitic M5076 than F-DXR.