Drug-resistant Tumor Growth Research Articles

A novel indole derivative, 2-{3-[1-(benzylsulfonyl)piperidin-4-yl]-2-methyl-1H-indol-1-yl}-1-(pyrrolidin-1-yl)ethenone, suppresses hedgehog signaling and drug-resistant tumor growth.

The Hedgehog (Hh) signaling pathway plays important roles in various physiological functions. Several malignancies, such as basal cell carcinoma (BCC) and medulloblastoma (MB), have been linked to the aberrant activation of Hh signaling. Although therapeutic drugs have been developed to inhibit Hh pathway-dependent cancer growth, drug resistance remains a major obstacle in cancer treatment. Here, we show that the newly identified, 2-{3-[1-(benzylsulfonyl)-1,2,3,6-tetrahydropyridin-4-yl]-2-methyl-1H-indol-1-yl}-1-(pyrrolidin-1-yl)ethenone analog (LKD1214) exhibits comparable potency to vismodegib in suppressing the Hh pathway activation. LKD1214 represses Smoothened (SMO) activity by blocking its ciliary translocation. Interestingly, we also identified that it has a distinctive binding interface with SMO compared with other SMO-regulating chemicals. Notably, it maintains an inhibitory activity against the SmoD477H mutant, as observed in a patient with vismodegib-resistant BCC. Furthermore, LKD1214 inhibits tumor growth in the mouse model of MB. Collectively, these findings suggest that LKD1214 has the therapeutic potential to overcome drug-resistance in Hh-dependent cancers.

Identification of naphthalimide-derivatives as novel PBD-targeted polo-like kinase 1 inhibitors with efficacy in drug-resistant lung cancer cells

Targeting polo-box domain (PBD) small molecule for polo-like kinase 1 (PLK1) inhibition is a viable alternative to target kinase domain (KD), which could avoid pan-selectivity and dose-limiting toxicity of ATP-competitive inhibitors. However, their efficacy in these settings is still low and inaccessible to clinical requirement. Herein, we utilized a structure-based high-throughput virtual screen to find novel chemical scaffold capable of inhibiting PLK1 via targeting PBD and identified an initial hit molecule compound 1a. Based on the lead compound 1a, a structural optimization approach was carried out and several series of derivatives with naphthalimide structural motif were synthesized. Compound 4Bb was identified as a new potent PLK1 inhibitor with a KD value of 0.29 μM. 4Bb could target PLK1 PBD to inhibit PLK1 activity and subsequently suppress the interaction of PLK1 with protein regulator of cytokinesis 1 (PRC1), finally leading to mitotic catastrophe in drug-resistant lung cancer cells. Furthermore, 4Bb could undergo nucleophilic substitution with the thiol group of glutathione (GSH) to disturb the redox homeostasis through exhausting GSH. By regulating cell cycle machinery and increasing cellular oxidative stress, 4Bb exhibited potent cytotoxicity to multiple cancer cells and drug-resistant cancer cells. Subcutaneous and oral administration of 4Bb could effectively inhibit the growth of drug-resistant tumors in vivo, doubling the survival time of tumor bearing mice without side effects in normal tissues. Thus, our study offers an orally-available, structurally-novel PLK1 inhibitor for drug-resistant lung cancer therapy.

Bufalin reverses ABCB1-mediated resistance to docetaxel in breast cancer

BackgroundDocetaxel (DCT) is widely used in clinical practice, but the drug resistance of breast cancer patients has become an important reason to limit its clinical efficacy. Chan’su is a commonly used traditional Chinese medicine for the treatment of breast cancer. Bufalin (BUF) is a bioactive polyhydroxy steroid extracted from chan’su and has strong antitumor activity, but there are few studies on reversing drug resistance in breast cancer. The aim of this study is to determine whether BUF can reverse the drug resistance to DCT and restore efficacy in breast cancer. MethodologyThe reversal index of BUF was detected by Cell Counting Kit-8 (CCK-8) assays. The effects of BUF on enhancing the apoptosis of DCT were detected by flow cytometry and Western Blot (WB), and the main differential expression levels of sensitive and resistant strains were detected by high-throughput sequencing. Rhodamine 123 assay, WB and ATP Binding Cassette Subfamily B Member 1 (ABCB1) ATPase activity experiments were used to detect the effect of BUF on ABCB1. The nude mouse orthotopic model was constructed to investigate the reversal effect of BUF on DCT resistance in vivo. ResultsWith BUF intervention, the sensitivity of drug-resistant cell lines to DCT was increased. BUF can inhibit the expression of ABCB1 protein, increase the drug accumulation of DCT in drug-resistant strains, and reduce the ATPase activity of ABCB1. Animal experiments show that BUF can inhibit the growth of drug-resistant tumors in an orthotopic model of breast cancer and decrease the expression of ABCB1. ConclusionBUF can reverse ABCB1-mediated docetaxel resistance in breast cancer.

A sequentially responsive cascade nanoplatform for increasing chemo-chemodynamic therapy

Poly(lactide-co-glycolide) (PLGA) is promising carrier material for drugs delivery in cancer therapy. However, the slow degradation and lack of targeting have greatly limited the clinical effectiveness of PLGA-based nanomedicines. Herein, we fabricated a hybrid nanosystem (3 P @ He/Pt-NPs) comprising of acid-sensitive polymer (mPOE-PLGA), active-targeting polymer (PBA-PLGA) and therapeutic agents (hemin+cisplatin) to combat these problems. In neutral environment, PEGylation can effectively improve the blood stability and circulation time of hybrid nanosystem. After reaching tumor regions, this nanosystem efficiently increased cellular uptake by dePEGylation and PBA-mediated active-targeting. Furthermore, encapsulated hemin could catalyze the oxygen bubbles generation, which remarkably increasing the drugs release rate. Subsequently, hybrid particles produced a higher cell-killing effect to lung cancer cells (A549) by the combination therapy (chemotherapy and chemodynamic therapy (CDT)). Importantly, cisplatin further amplified CDT effect by inducing H2O2 regeneration owing to the cascade enzymatic reactions, while hemin decreased intracellular glutathione (GSH) level, resulting in a low detoxification effect to cisplatin. Thus, hybrid particles could efficiently inhibit drug-resistant tumor growth and the inhibition rate reached 83.2%. Overall, this hybrid polymer nanosystem improve the drawbacks of PLGA-based nanocarriers, and can realize a cascading enhanced tumor treatment.

Design, synthesis, and biological evaluation of novel 7-substituted 10,11-methylenedioxy-camptothecin derivatives against drug-resistant small-cell lung cancer in vitro and in vivo

A series of novel 7-substituted 10,11-methylenedioxy-camptothecin (FL118) derivatives were designed, synthesized, and biologically evaluated. All the FL118 analogues showed significant cytotoxic activities in vitro with IC50 values in the nanomolar range and were more potent than topotecan. The most active compound 9c exhibited more significant anti-tumor activity against small-cell lung cancer (NCI–H446, H69, drug-resistant H69AR cells, drug-resistant NCI–H446/Irinotecan cells and drug-resistant NCI–H446/EP cells) in vitro. Additionally, 9c could also induce the expression of apoptosis proteins such as caspase-3, caspase-9, and PARP in small-cell lung cancer. Further studies showed that 9c induced apoptosis by inhibiting the expression of Mcl-1, Bcl-2, XIAP and survivin in small-cell lung cancer. In vivo9c also showed better anti-tumor efficacy, with the tumor growth inhibition rates were 40.4% (0.75 mg/kg), 73.7% (1.5 mg/kg), and 95.5% (3 mg/kg). It is noteworthy that 9c also demonstrated potent inhibition of drug-resistant tumor growth in NCI–H446/Irinotecan and NCI–H446/EP xenograft models, the tumor growth inhibition rates were 93.42% and 84.46%, respectively. Taken together, these findings indicated that compound 9c displays outstanding antitumor activity and drug-resistance in small-cell lung cancer both in vivo and in vitro, which could be worth further research as a novel anti-tumor drug against small-cell lung cancer.

Copper-Based Metal-Organic Framework Overcomes Cancer Chemoresistance through Systemically Disrupting Dynamically Balanced Cellular Redox Homeostasis.

Chemodrug resistance is a major reason accounting for tumor recurrence. Given the mechanistic complexity of chemodrug resistance, molecular inhibitors and targeting drugs often fail to eliminate drug-resistant cancer cells, and sometimes even promote chemoresistance by activating alternative pathways. Here, by exploiting biochemical fragility of high-level but dynamically balanced cellular redox homeostasis in drug-resistant cancer cells, we design a nanosized copper/catechol-based metal-organic framework (CuHPT) that effectively disturbs this homeostasis tilting the balance toward oxidative stress. Within drug-resistant cells, CuHPT starts disassembly that is triggered by persistent consumption of cellular glutathione (GSH). CuHPT disassembly simultaneously releases two structural elements: catechol ligands and reductive copper ions (Cu+). Both of them cooperatively function to amplify the production of intracellular radical oxidative species (ROS) via auto-oxidation and Fenton-like reactions through exhausting GSH. By drastically heightening cellular oxidative stress, CuHPT exhibits selective and potent cytotoxicity to multiple drug-resistant cancer cells. Importantly, CuHPT effectively inhibits in vivo drug-resistant tumor growth and doubles the survival time of tumor-bearing mice. Thus, along with CuHPT's good biocompatibility, our biochemical, cell biological, preclinical animal model data provide compelling evidence supporting the notion that this copper-based MOF is a predesigned smart therapeutic against drug-resistant cancers through precisely deconstructing their redox homeostasis.

Bacteria-derived minicells for cancer therapy.

Bacteria are always a considerable tool for the cancer therapy. The bacteria-derived minicells are re-emerged as a promising drug delivery system for cancer therapy. The minicells are nano-sized, anucleated, non-dividing, and metabolically active cells produced by abnormal bacterial cell division that are able to transcribe and translate the gene of interest. Minicells encapsulate a wide range of chemotherapeutic and molecular drugs, si/shRNA, antigens and therapeutic toxins to precisely deliver them to the cancer cells through the easy modification of minicell surface with bi-specific antibodies against receptor-targeted cancer cells. Minicell-mediated chemotherapy may inhibit the growth of drug-resistant tumors and exhibits the potential to successfully deliver the chemotherapeutics into hypoxic and necrotic region in solid tumors. This novel approach significantly overcomes drug leakage and severe toxicity by enhancing targeting specificity and therapeutic index of drugs in cancer therapy. Many antibody-conjugated drug-loaded minicells are being investigated in clinical trials for cancer therapy. This review summarizes the advantages of bacteria-derived minicells as delivery systems for anti-cancer drugs or agents and the recent advances and emerging future in cancer therapy.

Tumor‐Oriented Telomerase‐Terminated Nanoplatform as Versatile Strategy for Multidrug Resistance Reversal in Cancer Treatment

Multidrug resistance is one of the major problems in chemotherapy, and exploiting impactful targets to reverse drug resistance of most tumors remains a difficult problem. In this study, the tumor-oriented nanoparticle, BIBR1532-loaded peptide dendrimeric prodrug nanoassembly (B-PDPN), is used to assist telomerase inhibition for multidrug resistance reversal. B-PDPN possesses the characteristics of an acid-activated histidine to promote cellular uptake, a redox-sensitive poly(ethylene glycol) (PEG) layer to actualize endosomal escape and telomerase inhibitor release, and an acid sensitive chemical bond to facilitate chemotherapeutic drug release. Telomerase termination weakens the protective effect of hTERT protein on mitochondria and enhances reactive oxygen species (ROS) production, which increases DNA damage and apoptosis. The tumor-oriented nanoparticle B-PDPN achieves a broad-spectrum telomerase inhibition to combat multidrug resistance. In vivo experiments support the evidence that B-PDPN accumulates in the tumor site and reduces the expression of hTERT in tumor tissues to inhibit drug resistant tumor growth. This work introduces an innovative strategy of utilizing features of tumor-activated nanoplatform to assist telomerase termination. The nanoplatform enhances intracellular drug concentration and nucleus delivery of doxorubicin (DOX), and promotes DNA damage to combat multidrug resistance.

In situ real-time tracing of hierarchical targeting nanostructures in drug resistant tumors using diffuse fluorescence tomography.

Nanoparticles that respond to specific endogenous or exogenous stimuli in tumor tissues are actively being developed to address multidrug resistance owing to multiple advantages, including a prolonged circulation time, enhanced permeability and retention effect, and superior cellular uptake. Although some exciting results have been obtained, existing nanoparticles have limited routes to overcome the drug resistance of tumor cells; this limitation results in a failure to ablate resistant tumors via intravenous administration. To resolve this dilemma, we developed a smart theranostic nanoplatform with programmable particle size, activatable target ligands and in vivo multimodal imaging. This nanoplatform, which includes stealth zwitterionic coating, was shown to be quickly trapped in tumor tissue from the blood circulation within 5 min. Subsequently, the targeting moieties were activated in response to the acidic tumor microenvironment by triggering the zwitterionic shell detachment, driving the peeled nanoparticles to penetrate into tumor cells. These smart nanoparticles completely inhibited drug-resistant tumor growth and did not cause any damage to normal organ tissues in live animals. The designed nanoplatforms simultaneously acted as a nanoprobe for fluorescence imaging. Moreover, we also used noninvasive pharmacokinetic diffuse fluorescence tomography (DFT) to dynamically monitor and in situ real-time trace the nanoplatforms' behavior throughout the entire tumor in live animals. The nanoplatforms enabled rapid drug accumulation and deep penetration throughout the entire tumor. The rate of drug accumulation after the administration of nanoplatforms was five-fold higher compared with that after the administration of the free drug, which resulted in increased drug delivery efficiency and improved antitumor efficacy. Collectively, this hierarchical vehicle design provides promising insights for the development of theragnosis for multidrug resistant tumors.

Ginsenoside Rg5 overcomes chemotherapeutic multidrug resistance mediated by ABCB1 transporter: in vitro and in vivo study

BackgroundMultidrug resistance (MDR) to chemotherapy drugs remains a major challenge in clinical cancer treatment. Here we investigated whether and how ginsenoside Rg5 overcomes the MDR mediated by ABCB1 transporter in vitro and in vivo. MethodsCytotoxicity and colon formation as well as the intracellular accumulation of ABCB1 substrates were carried out in MDR cancer cells A2780/T and A549/T for evaluating the reversal effects of Rg5. The expressions of ABCB1 and Nrf2/AKT pathway were determined by Western blotting. An A549/T cell xenograft model was established to investigate the MDR reversal activity of Rg5 in vivo. ResultsRg5 significantly reversed ABCB1-mediated MDR by increasing the intracellular accumulation of ABCB1 substrates without altering protein expression of ABCB1. Moreover, Rg5 activated ABCB1 ATPase and reduced verapamil-stimulated ATPase activity, suggesting a high affinity of Rg5 to ABCB1 binding site which was further demonstrated by molecular docking analysis. In addition, co-treatment of Rg5 and docetaxel (TXT) suppressed the expression of Nrf2 and phosphorylation of AKT, indicating that sensitizing effect of Rg5 associated with AKT/Nrf2 pathway. In nude mice bearing A549/T tumor, Rg5 and TXT treatment significantly suppressed the growth of drug-resistant tumors without increase in toxicity when compared to TXT given alone at same dose. ConclusionTherefore, combination therapy of Rg5 and chemotherapy drugs is a strategy for the adjuvant chemotherapy, which encourages further pharmacokinetic and clinical studies.

Hierarchically Self-Assembled Supramolecular Host-Guest Delivery System for Drug Resistant Cancer Therapy.

In this report, a new star-like copolymer β-CD- g-(PNIPAAm- b-POEGA) x, consisting of a β-CD core, grafted with temperature-responsive poly( N-isopropylacrylamide) (PNIPAAm) and biocompatible poly(oligo(ethylene glycol) acrylate) (POEGA) in a block copolymer of the arms, was used to deliver chemotherapeutics to drug resistant cancer cells and tumors. The first step of the self-assembly process involves the encapsulation of chemotherapeutics through host-guest inclusion complexation between the β-cyclodextrin cavity and the anticancer drug. Next, the chain interaction of the PNIPAAm segment at elevated temperature drives the drug-loaded β-CD- g-(PNIPAAm- b-POEGA) x/PTX inclusion complex to hierarchically self-assemble into nanosized supramolecular assemblies at 37 °C, whereas the presence of poly(ethylene glycol) (PEG) chains in the distal end of the star-like copolymer arms impart enhanced stability to the self-assembled structure. More interestingly, this supramolecular host-guest nanocomplex promoted the enhanced cellular uptake of chemotherapeutics in MDR-1 up-regulated drug resistant cancer cells and exhibited high therapeutic efficacy for suppressing drug resistant tumor growth in an in vivo mouse model, due to the increased stability, improvement in aqueous solubility, enhanced cellular uptake, and partial membrane pump impairment by taking the advantage of PEGylation and supramolecular complex between this star-like copolymer and chemotherapeutics. This work signifies that temperature-sensitive PEGylated supramolecular nanocarriers with good biocompatibility are effective in combating MDR-1 mediated drug resistance in both in vitro and in vivo models, which is of significant importance for the advanced drug delivery platform designed to combat drug resistant cancer.

Paraptosis-Inducing Nanomedicine Overcomes Cancer Drug Resistance for a Potent Cancer Therapy.

Most chemotherapeutic drugs and their nanomedicine formulations exert anticancer activity by inducing cancer cell apoptosis. However, cancer cells inherently have and acquire many antiapoptosis mechanisms, causing cancer drug resistance and poor prognoses in patients. Herein, a potent paraptosis-inducing nanomedicine is reported that causes quick nonapoptotic death of cancer cells, overcoming apoptosis-based resistance and effectively inhibiting drug-resistant tumor growth. The nanomedicine is composed of micelles made from an amphiphilic 8-hydroxyquinoline (HQ)-conjugate block copolymer with polyethylene glycol. Cu2+ can catalyze the hydrolysis of the HQ conjugation linker and liberate HQ, and these molecules can form the complex Cu(HQ)2 , a strong proteasome inhibitor effective at inducing cell paraptosis. In vivo, the Cu2+ -responsive HQ-releasing micelles respond to elevated tumor Cu2+ levels or externally administered Cu2+ and effectively inhibit the growth of human breast adenocarcinoma doxorubicin-resistant (MCF-7/ADR) tumors. Compared with other nanomedicines that overcome drug resistance via delivering several agents or even siRNA, this paraptosis-inducing nanomedicine provides a simple but potent approach to overcoming cancer drug resistance.

Platelet-camouflaged nanococktail: Simultaneous inhibition of drug-resistant tumor growth and metastasis via a cancer cells and tumor vasculature dual-targeting strategy.

Multidrug resistance (MDR) poses a great challenge to cancer therapy. It is difficult to inhibit the growth of MDR cancer due to its chemoresistance. Furthermore, MDR cancers are more likely to metastasize, causing a high mortality among cancer patients. In this study, a nanomedicine RGD-NPVs@MNPs/DOX was developed by encapsulating melanin nanoparticles (MNPs) and doxorubicin (DOX) inside RGD peptide (c(RGDyC))-modified nanoscale platelet vesicles (RGD-NPVs) to efficiently inhibit the growth and metastasis of drug-resistant tumors via a cancer cells and tumor vasculature dual-targeting strategy.Methods: The in vitro immune evasion potential and the targeting performance of RGD-NPVs@MNPs/DOX were examined using RAW264.7, HUVECs, MDA-MB-231 and MDA-MB-231/ADR cells lines. We also evaluated the pharmacokinetic behavior and the in vivo therapeutic performance of RGD-NPVs@MNPs/DOX using a MDA-MB-231/ADR tumor-bearing nude mouse model.Results: By taking advantage of the self-recognizing property of the platelet membrane and the conjugated RGD peptides, RGD-NPVs@MNPs/DOX was found to evade immune clearance and target the αvβ3 integrin on tumor vasculature and resistant breast tumor cells. Under irradiation with a NIR laser, RGD-NPVs@MNPs/DOX produced a multipronged effect, including reversal of cancer MDR, efficient killing of resistant cells by chemo-photothermal therapy, elimination of tumor vasculature for blocking metastasis, and long-lasting inhibition of the expressions of VEGF, MMP2 and MMP9 within the tumor.Conclusion: This versatile nanomedicine of RGD-NPVs@MNPs/DOX integrating unique biomimetic properties, excellent targeting performance, and comprehensive therapeutic strategies in one formulation might bring opportunities to MDR cancer therapy.

Thermoresponsive Supramolecular Chemotherapy by “V”‐Shaped Armed β‐Cyclodextrin Star Polymer to Overcome Drug Resistance

Pump mediated drug efflux is the key reason to result in the failure of chemotherapy. Herein, a novel star polymer β-CD-v-(PEG-β-PNIPAAm)7 consisting of a β-CD core, grafted with thermo-responsive poly(N-isopropylacrylamide) (PNIPAAm) and biocompatible poly(ethylene glycol) (PEG) in the multiple "V"-shaped arms is designed and further fabricated into supramolecular nanocarriers for drug resistant cancer therapy. The star polymer could encapsulate chemotherapeutics between β-cyclodextrin and anti-cancer drug via inclusion complex (IC). Furthermore, the temperature induced chain association of PNIPAAm segments facilitated the IC to form supramolecular nanoparticles at 37 °C, whereas the presence of PEG impart great stability to the self-assemblies. When incubated with MDR-1 membrane pump regulated drug resistant tumor cells, much higher and faster cellular uptake of the supramolecular nanoparticles were detected, and the enhanced intracellular retention of drugs could lead to significant inhibition of cell growth. Further in vivo evaluation showed high therapeutic efficacy in suppressing drug resistant tumor growth without a significant impact on the normal functions of main organs. This work signifies thermo-responsive supramolecular chemotherapy is promising in combating pump mediated drug resistance in both in vitro and in vivo models, which may be encouraging for the advanced drug delivery platform design to overcome drug resistant cancer.

Extracellular Matrix/Integrin Signaling Promotes Resistance to Combined Inhibition of HER2 and PI3K in HER2+ Breast Cancer.

PIK3CA mutations are associated with resistance to HER2-targeted therapies. We previously showed that HER2+/PIK3CAH1047R transgenic mammary tumors are resistant to the HER2 antibodies trastuzumab and pertuzumab but respond to PI3K inhibitor buparlisib (TPB). In this study, we identified mechanisms of resistance to combined inhibition of HER2 and PI3K. TPB-resistant tumors were generated by treating HER2+/PIK3CAH1047R tumor-bearing mice long term with the drug combination. RNA sequencing of TPB-resistant tumors revealed that extracellular matrix and cell adhesion genes, including collagen II (Col2a1), were markedly upregulated, accompanied by activation of integrin β1/Src. Cells derived from drug-resistant tumors were sensitive to TBP when grown in vitro, but exhibited resistance when plated on collagen or when reintroduced into mice. Drug resistance was partially reversed by the collagen synthesis inhibitor ethyl-3,4-dihydroxybenzoate. Inhibition of integrin β1/Src blocked collagen-induced resistance to TPB and inhibited growth of drug-resistant tumors. High collagen II expression was associated with significantly lower clinical response to neoadjuvant anti-HER2 therapy in HER2+ breast cancer patients. Overall, these data suggest that upregulation of collagen/integrin/Src signaling contributes to resistance to combinatorial HER2 and PI3K inhibition. Cancer Res; 77(12); 3280-92. ©2017 AACR.

Targeting ETS1 with RNAi-based supramolecular nanoassemblies for multidrug-resistant breast cancer therapy

Overexpression of erythroblastosis virus E26 oncogene homolog 1 (ETS1) gene is correlated with both tumor progression and poor response to chemotherapy in cancer treatment, and the exploitation of RNA interference (RNAi) technology to downregulate ETS1 seems to be a promising approach to reverse multidrug-resistant cancer cells to chemotherapy. Hence, the RNAi-based nanomedicine which is able to simultaneously downregulate ETS1 expression and to deliver chemotherapeutic agents may improve multidrug-resistant cancer therapy synergistically. In this study, we developed a supramolecular nanoassembly that could deliver siRNA targeting ETS1 (siETS1) and doxorubicin (DOX) as an effective nanomedicine to achieve successful chemotherapy towards multidrug-resistant breast cancer. The nanotherapeutic system was prepared by loading adamantane-conjugated doxorubicin (AD) into polyethyleneimine-modified (2-hydroxypropyl)-γ-cyclodextrin (HP) through the supramolecular assembly to form AD-loaded HP (HPAD), followed by electrostatically-driven self-assembly between siETS1 and HPAD. When the HPAD/siETS1 nanoassemblies were delivered into drug-resistant MCF-7/ADR cells, the drug efflux was significantly reduced as a result of simultaneous silencing of ETS1 and MDR1 genes. Importantly, the HPAD/siETS1 nanoassembly could enhance drug residence time at tumor site, and effectively inhibit drug-resistant tumor growth due to the inhibition of angiogenesis and necrosis in tumor tissues. Western blot analysis indicated that the gene expression of both ETS1 and MDR1 in vivo was considerably downregulated after the drug-resistant tumor-bearing mouse was treated with HPAD/siETS1 nanoassemblies. This study offers a new therapeutic delivery strategy targeting ETS1 for the effective multidrug-resistant chemotherapy.

Abstract 5058: Silencing of NOTCH signaling enhances the sensitivity of ERG positive prostate cancer cells to AR inhibitors

Abstract Introduction: Androgen receptor (AR) signaling plays a critical role in all the stages of prostate cancer (CaP) ranging from organ confined to castration-resistant (CRPC) phases. Although androgen deprivation therapy (ADT) remains the mainstay treatment for advanced CaP, the inevitable transition from androgen- sensitive to CRCP presents the most significant challenge in CaP therapy. Androgen dependent expression of oncogenic ETS related gene (ERG) in half of all CaP in western countries plays critical role in the tumorigenesis of CaP through regulation of cancer specific signaling pathways. We found that NOTCH transcription factors are common targets of ERG in ERG positive cancer cells. NOTCH signaling pathway is an important signaling pathway in the development of drug-resistant tumor growth. In the current study we evaluated the combinatorial effects of NOTCH and AR inhibitors in the context of ERG positive prostate cancer cells. Methods: ERG, NOTCH1, NOTCH2 and downstream targets of NOTCH transcription factors were analyzed by Western blot assays. Dose and time kinetics of combining NOTCH inhibitor (γ-Secretase inhibitor 1, GSI-1) and AR inhibitors (Bicalutamide, Enzalutamide, and Abiraterone) were assessed in a panel of ERG positive or ERG negative CaP cells. Trypan blue exclusion, methylthiazole tetrazolium (MTT), or ApoTox-Glo™ Triplex assays were used to asses cell proliferation, apoptosis and drug cytotoxicity. Results: Prostate cancer cell lines with endogenous or ectopic expression of ERG showed upregulation of NOTCH1 and NOTCH2. The NOTCH inhibitor, GSI-1 conferred an increased sensitivity to all tested AR inhibitors (Bicalutamide, Enzalutamide, and Abiraterone) with bicalutamide showing the most robust inhibition of AR, ERG, NOTCH1, NOTCH2, PSA, decreased cell growth and enhanced apoptosis in ERG positive VCaP cells. This observation was not seen in ERG negative LNCaP cells or in ERG positive primary endothelial cells. Conclusions: NOTCH inhibitor enhanced sensitivity of AR inhibitors in ERG positive VCaP cells growth. The combination of the GSI-1 with AR inhibitors has shown synergistic effect when compared to single agent treatment. Taken together, our study suggests that NOTCH inhibitors may enhance the actions of AR inhibitors in the treatment of ERG positive prostate cancers. Inhibition of AR and NOTCH signaling may offer new opportunities in assessing ERG targeted therapy for prostate cancer. Citation Format: Ahmed A. Mohamed, Shyh-Han Tan, Shilpa Katta, Charles P. Xavier, Lakshmi Ravindranath, Wei Huang, Hua Li, Meera Srivastava, Shashwat Sharad, Taduru Sreenath, Gyorgy Petrovics, Albert Dobi, Shiv Srivastava. Silencing of NOTCH signaling enhances the sensitivity of ERG positive prostate cancer cells to AR inhibitors. [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 5058. doi:10.1158/1538-7445.AM2015-5058

An Autocrine Cytokine/JAK/STAT-Signaling Induces Kynurenine Synthesis in Multidrug Resistant Human Cancer Cells

BackgroundMultidrug resistant cancer cells are hard to eradicate for the inefficacy of conventional anticancer drugs. Besides escaping the cytotoxic effects of chemotherapy, they also bypass the pro-immunogenic effects induced by anticancer drugs: indeed they are not well recognized by host dendritic cells and do not elicit a durable anti-tumor immunity. It has not yet been investigated whether multidrug resistant cells have a different ability to induce immunosuppression than chemosensitive ones. We addressed this issue in human and murine chemosensitive and multidrug resistant cancer cells.ResultsWe found that the activity and expression of indoleamine 2,3-dioxygenase 1 (IDO1), which catalyzes the conversion of tryptophan into the immunosuppressive metabolite kynurenine, was higher in all the multidrug resistant cells analyzed and that IDO1 inhibition reduced the growth of drug-resistant tumors in immunocompetent animals. In chemoresistant cells the basal activity of JAK1/STAT1 and JAK1/STAT3 signaling was higher, the STAT3 inhibitor PIAS3 was down-regulated, and the autocrine production of STAT3-target and IDO1-inducers cytokines IL-6, IL-4, IL-1β, IL-13, TNF-α and CD40L, was increased. The disruption of the JAK/STAT signaling lowered the IDO1 activity and reversed the kynurenine-induced pro-immunosuppressive effects, as revealed by the restored proliferation of T-lymphocytes in STAT-silenced chemoresistant cells.ConclusionsOur work shows that multidrug resistant cells have a stronger immunosuppressive attitude than chemosensitive cells, due to the constitutive activation of the JAK/STAT/IDO1 axis, thus resulting chemo- and immune-evasive. Disrupting this axis may significantly improve the efficacy of chemo-immunotherapy protocols against resistant tumors.

Abstract LB-13: Hyaluronic acid-based CD44 targeted nanoparticle delivery of combination MDR1 siRNA/paclitaxel to overcome drug resistance in ovarian cancer

Abstract A major obstacle in the success of chemotherapy in ovarian cancer is the emergence of multidrug resistance (MDR). Overexpression of the MDR1 gene and corresponding P-glycoprotein (Pgp) efflux pumps is one of the best characterized MDR mechanisms. Although MDR1 siRNA based strategies are emerging as highly promising approaches to reverse MDR, the systemic delivery still remains a great challenge. In the present study, CD44 targeting hyaluronic acid (HA) based self-assembling nanoparticle systems were designed with MDR1 siRNA to evaluate its delivery efficiency and combination anticancer therapeutic efficacy with paclitaxel in vitro and in vivo. The results showed that HA-poly(ethyleneimine)/HA-poly(ethylene glycol) (HA-PEI/HA-PEG) nanoparticle successfully delivered MDR1 siRNA into MDR ovarian cancer cell lines, SKOV-3TR and OVCAR8TR. Western blot analysis, calcein AM retention assay, and MTT assay further demonstrated that HA-PEI/HA-PEG nanoparticles loaded with MDR1 siRNA efficiently down-regulated the expression of MDR1 and inhibited the functional activity of Pgp, and subsequently increase cell sensitivity to paclitaxel. HA-PEI/HA-PEG/MDR1 siRNA nanoparticle therapy followed by paclitaxel treatment produced a significant inhibitory effect on the drug-resistant tumor growth as compared with control groups in MDR ovarian cancer xenograft mouse models. These results indicated CD44-targeted HA-PEI/HA-PEG nanoparticle platform is an effective siRNA delivery system for potential siRNA-based anticancer therapeutics in ovarian cancer. Citation Format: Xiaoqian Yang, Arun lyer, Francis hornicek, Mansoor Amiji, Zhenfeng Duan. Hyaluronic acid-based CD44 targeted nanoparticle delivery of combination MDR1 siRNA/paclitaxel to overcome drug resistance in ovarian cancer. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr LB-13. doi:10.1158/1538-7445.AM2014-LB-13

Priming cancer cells for drug resistance: role of the fibroblast niche.

Conventional and targeted chemotherapies remain integral strategies to treat solid tumors. Despite the large number of anti-cancer drugs available, chemotherapy does not completely eradicate disease. Disease recurrence and the growth of drug resistant tumors remain significant problems in anti-cancer treatment. To develop more effective treatment strategies, it is important to understand the underlying cellular and molecular mechanisms of drug resistance. It is generally accepted that cancer cells do not function alone, but evolve through interactions with the surrounding tumor microenvironment. As key cellular components of the tumor microenvironment, fibroblasts regulate the growth and progression of many solid tumors. Emerging studies demonstrate that fibroblasts secrete a multitude of factors that enable cancer cells to become drug resistant. This review will explore how fibroblast secretion of soluble factors act on cancer cells to enhance cancer cell survival and cancer stem cell renewal, contributing to the development of drug resistant cancer.