Ferroptosis-modulating small molecules for targeting drug-resistant cancer: Challenges and opportunities in manipulating redox signaling.

Ferroptosis is an iron-dependent cell death program that is characterized by excessive lipid peroxidation. Triggering ferroptosis has been proposed as a promising strategy to fight cancer and overcome drug resistance in antitumor therapy. Understanding the molecular interactions and structural features of ferroptosis-inducing compounds might therefore open the door to efficient pharmacological strategies against aggressive, metastatic, and therapy-resistant cancer. We here summarize the molecular mechanisms and structural requirements of ferroptosis-inducing small molecules that target central players in ferroptosis. Focus is placed on (i) glutathione peroxidase (GPX) 4, the only GPX isoenzyme that detoxifies complex membrane-bound lipid hydroperoxides, (ii) the cystine/glutamate antiporter system Xc - that is central for glutathione regeneration, (iii) the redox-protective transcription factor nuclear factor erythroid 2-related factor (NRF2), and (iv) GPX4 repression in combination with induced heme degradation via heme oxygenase-1. We deduce common features for efficient ferroptotic activity and highlight challenges in drug development. Moreover, we critically discuss the potential of natural products as ferroptosis-inducing lead structures and provide a comprehensive overview of structurally diverse biogenic and bioinspired small molecules that trigger ferroptosis via iron oxidation, inhibition of the thioredoxin/thioredoxin reductase system or less defined modes of action.

PMCA inhibition reverses drug resistance in clinically refractory cancer patient-derived models.

BACKGROUND: Cancer cells have developed molecular strategies to cope with evolutionary stressors in the dynamic tumor microenvironment. Peroxisome proliferator-activated receptor-γ coactivator-1α (PGC1α) is a metabolic rheostat that regulates diverse cellular adaptive behaviors, including growth and survival. However, the mechanistic role of PGC1α in regulating cancer cell viability under metabolic and genotoxic stress remains elusive. METHODS: We investigated the PGC1α-mediated survival mechanisms in metabolic stress (i.e., glucose deprivation-induced metabolic stress condition)-resistant cancer cells. We established glucose deprivation-induced metabolic stress-resistant cells (selected cells) from parental tumor cells and silenced or overexpressed PGC1α in selected and parental tumor cells. RESULTS: Several in vitro and in vivo mouse experiments were conducted to elucidate the contribution of PGC1α to cell viability in metabolic stress conditions. Interestingly, in the mouse xenograft model of patient-derived drug-resistant cancer cells, each group treated with an anti-cancer drug alone showed no drastic effects, whereas a group that was co-administered an anti-cancer drug and a specific PMCA inhibitor (caloxin or candidate 13) showed marked tumor shrinkage. CONCLUSIONS: Our results suggest that PGC1α is a key regulator of anti-apoptosis in metabolic and genotoxic stress-resistant cells, inducing PMCA expression and allowing survival in glucose-deprived conditions. We have discovered a novel therapeutic target candidate that could be employed for the treatment of patients with refractory cancers.

Biocatalysis of precursors to new-generation SB-T-taxanes effective against paclitaxel-resistant cancer cells.

A 10-O-deacetylbaccatin III 10-O-acetyltransferase biocatalyst from Taxus plants was expressed in bacteria whole-cells that were fed 10-O-deacetylbaccatin III and cyclopropane carboxylic acid. Product analysis by qualitative LC/ESI-MS suggested that the C10-acylated products baccatin III, 10-O-n-propionyl-10-O-deacetylbaccatin III, and 10-O-cyclopropanecarbonyl-10-O-deacetylbaccatin III were made in vivo. The results implied that the cells provided non-natural cyclopropanecarbonyl CoA, from a broad-specificity CoA ligase, and natural products, acetyl CoA and n-propionyl CoA, from reserves in the bacteria for use by acyltransferase to acylate 10-O-deacetylbaccatin III in vivo. The 10-acyl-10-O-deacetylbaccatin III are precursors used to synthesize new-generation paclitaxel analogs SB-T-1214 and SB-T-121303, which are effective against cancer cells resistant to paclitaxel and its drug derivatives. The kcat and KM of the acyltransferase for cyclopropanecarbonyl CoA (0.83 s-1, 0.15 M) and n-propionyl CoA (1.2 s-1, 0.15 M) guided scale-up efforts. The 10-acyl-10-O-deacetylbaccatin III analogs (∼45 mg each) were made in vitro by the acyltransferase when incubated with the commercial taxane 10-O-deacetylbaccatin III and synthesized cyclopropanecarbonyl or n-propionyl CoA. The structures of the 10-acyl products were verified by NMR analyses that confirmed C10 acylation of the taxane substrate. LC/ESI-MS/MS analysis also supported the identities of the biocatalyzed products. This effort provides a biocatalysis framework to produce new-generation taxane precursors.

Luteolin attenuates cancer cell stemness in PTX-resistant oesophageal cancer cells through mediating SOX2 protein stability.

Cancer drug resistance is a formidable obstacle that enhances cancer stem-like cell properties, tumour metastasis and relapse. Luteolin (Lut) is a natural flavonoid with strong antitumor effects. However, the underlying mechanism(s) by which Lut protects against paclitaxel-resistant (PTX-resistant) cancer cell remains unknown. Herein, we found that Lut significantly attenuated the stem-like properties of PTX-resistant cancer cells by downregulating the expression of SOX2 protein. Additionally, further study showed that Lut could inhibit the PI3K/AKT pathway to decrease the phosphorylation level of AKT(S473) and UBR5 expression, which is an ubiquitin E3 ligase that promotes SOX2 degradation. In addition, Lut also inhibited PTX-resistant cancer cell migration and invasion by blocking epithelial-mesenchymal transition (EMT). Importantly, Lut inhibited the tumorigenic ability of oesophageal PTX-resistant cancer cells and showed no obvious toxicity in vivo. Thus, Lut has potential as a promising agent for drug-resistant oesophageal cancer therapy.

A cell-targeted, size-photocontrollable, nuclear-uptake nanodrug delivery system for drug-resistant cancer therapy.

The development of multidrug resistance (MDR) has become an increasingly serious problem in cancer therapy. The cell-membrane overexpression of P-glycoprotein (P-gp), which can actively efflux various anticancer drugs from the cell, is a major mechanism of MDR. Nuclear-uptake nanodrug delivery systems, which enable intranuclear release of anticancer drugs, are expected to address this challenge by bypassing P-gp. However, before entering the nucleus, the nanocarrier must pass through the cell membrane, necessitating coordination between intracellular and intranuclear delivery. To accommodate this requirement, we have used DNA self-assembly to develop a nuclear-uptake nanodrug system carried by a cell-targeted near-infrared (NIR)-responsive nanotruck for drug-resistant cancer therapy. Via DNA hybridization, small drug-loaded gold nanoparticles (termed nanodrugs) can self-assemble onto the side face of a silver-gold nanorod (NR, termed nanotruck) whose end faces were modified with a cell type-specific internalizing aptamer. By using this size-photocontrollable nanodrug delivery system, anticancer drugs can be efficiently accumulated in the nuclei to effectively kill the cancer cells.

Application of iPS cell technology to cancer epigenome study: uncovering the mechanism of cell status conversion for drug resistance in tumor.

Recent studies imply that cancer cells possess the ability to reversibly change their properties between a drug sensitive state and a drug resistant state accompanied by epigenetic changes. This evidence indicates that better understanding of cancer epigenetics is important for efficient cancer therapies. Nevertheless, it had been difficult to deeply examine the epigenetic mechanisms because of lack of the tools to actively modify coordinated epigenetic events. In this stagnant situation, the reprogramming technology established by Yamanaka and coworkers have shed a new light. The novel reprogramming technology has made it possible for researchers to artificially introduce epigenetic remodeling into somatic cells. Accordingly, we might be able to use this technology as a tool to introduce the coordinated epigenetic reorganization. In this review, we introduce the idea of cell state interconversion in cancer cells that is attributable to altered epigenetic regulations. We then depict the epigenetic modifications observed during the process of somatic cell reprogramming and give some examples of the difficulty in cancer cell reprogramming. Finally, we discuss how we can translate this reprogramming refractoriness of cancer cells into uncovering unique epigenetic regulations in cancer cells, which might be applicable eventually to the development of novel cancer therapeutics against drug resistant cancer cells.

Improving the response to lenvatinib in partial responders using a Constrained-Disorder-Principle-based second-generation artificial intelligence-therapeutic regimen: a proof-of-concept open-labeled clinical trial.

Introduction: The main obstacle in treating cancer patients is drug resistance. Lenvatinib treatment poses challenges due to loss of response and the common dose-limiting adverse events (AEs). The Constrained-disorder-principle (CDP)-based second-generation artificial intelligence (AI) systems introduce variability into treatment regimens and offer a potential strategy for enhancing treatment efficacy. This proof-of-concept clinical trial aimed to assess the impact of a personalized algorithm-controlled therapeutic regimen on lenvatinib effectiveness and tolerability. Methods: A 14-week open-label, non-randomized trial was conducted with five cancer patients receiving lenvatinib-an AI-assisted application tailored to a personalized therapeutic regimen for each patient, which the treating physician approved. The study assessed changes in tumor response through FDG-PET-CT and tumor markers and quality of life via the EORTC QLQ-THY34 questionnaire, AEs, and laboratory evaluations. The app monitored treatment adherence. Results: At 14 weeks of follow-up, the disease control rate (including the following outcomes: complete response, partial response, stable disease) was 80%. The FDG-PET-CT scan-based RECIST v1.1 and PERCIST criteria showed partial response in 40% of patients and stable disease in an additional 40% of patients. One patient experienced a progressing disease. Of the participants with thyroid cancer, 75% showed a reduction in thyroglobulin levels, and 60% of all the participants showed a decrease in neutrophil-to-lymphocyte ratio during treatment. Improvement in the median social support score among patients utilizing the system supports an ancillary benefit of the intervention. No grade 4 AEs or functional deteriorations were recorded. Summary: The results of this proof-of-concept open-labeled clinical trial suggest that the CDP-based second-generation AI system-generated personalized therapeutic recommendations may improve the response to lenvatinib with manageable AEs. Prospective controlled studies are needed to determine the efficacy of this approach.

Semi-Synthetic Dihydrotestosterone Derivatives Modulate Inherent Multidrug Resistance and Sensitize Colon Cancer Cells to Chemotherapy.

Multidrug resistance (MDR) is a serious hurdle to successful cancer therapy. Here, we examined the efficiency of novel semi-synthetic dihydrotestosterone derivatives, more specifically androstano-arylpyrimidines in inhibiting the efflux activity of ATP-binding cassette (ABC) transporters and sensitizing inherently MDR colon cancer cells to various chemotherapy drugs. Using the Rhodamine123 accumulation assay, we evaluated the efflux activity of cancer cells following treatments with androstano-arylpyrimidines. We found that acetylated compounds were capable of attenuating the membrane efflux of inherently MDR cells; however, deacetylated counterparts were ineffective. To delineate the possible molecular mechanisms underlying these unique activities of androstano-arylpyrimidines, the degree of apoptosis induction was assessed by AnnexinV-based assays, both upon the individual as well as by steroid and chemotherapy agent combination treatments. Five dihydrotestosterone derivatives applied in combination with Doxorubicin or Epirubicin triggered massive apoptosis in MDR cells, and these combinations were more efficient than chemotherapy drugs together with Verapamil. Furthermore, our results revealed that androstano-arylpyrimidines induced significant endoplasmic reticulum stress (ER stress) but did not notably modulate ABC transporter expression. Therefore, ER stress triggered by acetylated androstano-arylpyrimidines is probably involved in the mechanism of efflux pump inhibition and drug sensitization which can be targeted in future drug developments to defeat inherently multidrug-resistant cancer.

The response and resistance to drugs in ovarian cancer cell lines in 2D monolayers and 3D spheroids.

Ovarian cancer is the most common type of gynecologic cancer. One of the leading causes of high mortality is chemoresistance, developed primarily or during treatment. Different mechanisms of drug resistance appear at the cellular and cancer tissue organization levels. We examined the differences in response to the cytotoxic drugs CIS, MTX, DOX, VIN, PAC, and TOP using 2D (two-dimensional) and 3D (three-dimensional) culture methods. We tested the drug-sensitive ovarian cancer cell line W1 and established resistant cell lines to appropriate cytotoxic drugs. The following qualitative and quantitative methods were used to assess: 1) morphology - inverted microscope and hematoxylin & eosin staining; 2) viability - MTT assay; 3) gene expression - a quantitative polymerase chain reaction; 4) identification of proteins - immunohistochemistry, and immunofluorescence. Our results indicate that the drug-sensitive and drug-resistant cells cultured in 3D conditions exhibit stronger resistance than the cells cultured in 2D conditions. A traditional 2D model shows that drug resistance of cancer cells is caused mainly by changes in the expression of genes encoding ATP-binding cassette transporter proteins, components of the extracellular matrix, "new" established genes related to drug resistance in ovarian cancer cell lines, and universal marker of cancer stem cells. Whereas in a 3D model, the drug resistance in spheroids can be related to other mechanisms such as the structure of the spheroid (dense or loose), the cell type (necrotic, quiescent, proliferating cells), drug concentrations or drug diffusion into the dense cellular/ECM structure.

Immunotherapy with cure potential of multi-drug resistant hematologic malignancies using IL-2 preactivated intentionally mismatched donor lymphocyte.

PURPOSE: Unfortunately, cure of multi-drug resistant (MDR) hematologic malignancies remains an unmet need. Donor lymphocyte infusion (DLI) following allogeneic stem cell transplantation (SCT) can sometimes eliminate multi-drug resistant leukemia but at a risk of acute and chronic graft-vs-host disease (GVHD) and procedure-related toxicity. Supported by pre-clinical experiments in animal models, we hypothesized that immunotherapy induced by non-engrafting intentionally mismatched IL-2 activated killers (IMAK) including both T & NK cells could induce safer, faster and much more effective immunotherapy while avoiding the need for SCT and the risks of GVHD. METHODS: IMAK treatment was applied in 33 patients with MDR hematologic malignancies conditioned with cyclophosphamide 1000 mg/m2 based protocol. Haploidentical or unrelated donor lymphocytes were preactivated with IL-2 6000 IU/ml for 4 days. IMAK was combined with Rituximab in 12/23 patients with CD20+ B cells. RESULTS: A total of 23/33 patients with MDR (4 failing SCT) achieved complete remission (CR). First patient currently 30 years with no further treatment and 6 observed for > 5 years (2 AML; 2 multiple myeloma, 1 ALL & 1 NHL) can be considered cured. No patient developed > grade 3 toxicity or GVHD. No residual male cells were detectable among six females treated with male cells beyond day + 6, confirming that GVHD was prevented by consistent early rejection of donor lymphocytes. CONCLUSIONS: We hypothesize that safe and superior immunotherapy of MDR with cure potential may be accomplished by IMAK, most probably in patients with low tumor burden, but that remains to be confirmed by future clinical trials.

Single cell mass spectrometry analysis of drug-resistant cancer cells: Metabolomics studies of synergetic effect of combinational treatment.

Irinotecan (IRI), a topoisomerase I inhibitor blocking DNA synthesis, is a widely used chemotherapy drug for metastatic colorectal cancer. Despite being an effective chemotherapy drug, its clinical effectiveness is limited by both intrinsic and acquired drug resistance. Previous studies indicate IRI induces cancer stemness in irinotecan-resistant (IRI-resistant) cells. Metformin, an oral antidiabetic drug, was recently reported for anticancer effects, likely due to its selective killing of cancer stem cells (CSCs). Given IRI-resistant cells exhibiting high cancer stemness, we hypothesize metformin can sensitize IRI-resistant cells and rescue the therapeutic effect. In this work, we utilized the Single-probe mass spectrometry technique to analyze live IRI-resistant cells under different treatment conditions. We discovered that metformin treatment was associated with the downregulation of lipids and fatty acids, potentially through the inhibition of fatty acid synthase (FASN). Importantly, certain species can be only detected from cells in their living status. The level of synergistic effect of metformin and IRI in their co-treatment of IRI-resistant cells was evaluated using Chou-Talalay combinational index. Using enzymatic activity assay, we determined that the co-treatment exhibit the highest FASN inhibition compared with the mono-treatment of IRI or metformin. To our knowledge, this is the first single-cell MS metabolomics study demonstrating metformin-IRI synergistic effect overcoming drug resistance in IRI-resistant cells.

Design, Synthesis, and Antitumor Activity of Erlotinib Derivatives.

Nineteen erlotinib derivatives bearing different 1,2,3-triazole moieties were designed, synthesized, and evaluated for their potential against different cancer cell lines. The structures of the synthesized compounds were confirmed via 1H NMR, 13C NMR, and HR MS. Preliminary antitumor activity assay results suggested that some compounds showed remarkable inhibitory activity against different cancer cell lines including the corresponding drug-resistant ones. Among these compounds, 3d was the most promising one with an IC50 of 7.17 ± 0.73 µM (KYSE70TR), 7.91 ± 0.61 µM (KYSE410TR), 10.02 ± 0.75 µM (KYSE450TR), 5.76 ± 0.3 3 µM (H1650TR), and 2.38 ± 0.17 µM (HCC827GR). A preliminary mechanism study suggested that compound 3d suppressed cancer cell proliferation through the EGFR-TK pathway.

Metabolic targeting of cancer by a ubiquinone uncompetitive inhibitor of mitochondrial complex I.

SMIP004-7 is a small molecule inhibitor of mitochondrial respiration with selective in vivo anti-cancer activity through an as-yet unknown molecular target. We demonstrate here that SMIP004-7 targets drug-resistant cancer cells with stem-like features by inhibiting mitochondrial respiration complex I (NADH:ubiquinone oxidoreductase, complex I [CI]). Instead of affecting the quinone-binding site targeted by most CI inhibitors, SMIP004-7 and its cytochrome P450-dependent activated metabolite(s) have an uncompetitive mechanism of inhibition involving a distinct N-terminal region of catalytic subunit NDUFS2 that leads to rapid disassembly of CI. SMIP004-7 and an improved chemical analog selectively engage NDUFS2 in vivo to inhibit the growth of triple-negative breast cancer transplants, a response mediated at least in part by boosting CD4+ and CD8+ T cell-mediated immune surveillance. Thus, SMIP004-7 defines an emerging class of ubiquinone uncompetitive CI inhibitors for cell autonomous and microenvironmental metabolic targeting of mitochondrial respiration in cancer.

Activation of the Anaphase Promoting Complex Reverses Multiple Drug Resistant Cancer in a Canine Model of Multiple Drug Resistant Lymphoma.

Like humans, canine lymphomas are treated by chemotherapy cocktails and frequently develop multiple drug resistance (MDR). Their shortened clinical timelines and tumor accessibility make canines excellent models to study MDR mechanisms. Insulin-sensitizers have been shown to reduce the incidence of cancer in humans prescribed them, and we previously demonstrated that they also reverse and delay MDR development in vitro. Here, we treated canines with MDR lymphoma with metformin to assess clinical and tumoral responses, including changes in MDR biomarkers, and used mRNA microarrays to determine differential gene expression. Metformin reduced MDR protein markers in all canines in the study. Microarrays performed on mRNAs gathered through longitudinal tumor sampling identified a 290 gene set that was enriched in Anaphase Promoting Complex (APC) substrates and additional mRNAs associated with slowed mitotic progression in MDR samples compared to skin controls. mRNAs from a canine that went into remission showed that APC substrate mRNAs were decreased, indicating that the APC was activated during remission. In vitro validation using canine lymphoma cells selected for resistance to chemotherapeutic drugs confirmed that APC activation restored MDR chemosensitivity, and that APC activity was reduced in MDR cells. This supports the idea that rapidly pushing MDR cells that harbor high loads of chromosome instability through mitosis, by activating the APC, contributes to improved survival and disease-free duration.

Curcumin: reclaiming the lost ground against cancer resistance.

Curcumin, a polyphenol, has a wide range of biological properties such as anticancer, antibacterial, antitubercular, cardioprotective and neuroprotective. Moreover, the anti-proliferative activities of Curcumin have been widely studied against several types of cancers due to its ability to target multiple pathways in cancer. Although Curcumin exhibited potent anticancer activity, its clinical use is limited due to its poor water solubility and faster metabolism. Hence, there is an immense interest among researchers to develop potent, water-soluble, and metabolically stable Curcumin analogs for cancer treatment. While drug resistance remains a major problem in cancer therapy that renders current chemotherapy ineffective, curcumin has shown promise to overcome the resistance and re-sensitize cancer to chemotherapeutic drugs in many studies. In the present review, we are summarizing the role of curcumin in controlling the proliferation of drug-resistant cancers and development of curcumin-based therapeutic applications from cell culture studies up to clinical trials.

Nanomedicines for combating multidrug resistance of cancer.

Chemotherapy typically involves the use of specific chemodrugs to inhibit the proliferation of cancer cells, but the frequent emergence of a variety of multidrug-resistant cancer cells poses a tremendous threat to our combat against cancer. The fundamental causes of multidrug resistance (MDR) have been studied for decades, and can be generally classified into two types: one is associated with the activation of diverse drug efflux pumps, which are responsible for translocating intracellular drug molecules out of the cells; the other is linked with some non-efflux pump-related mechanisms, such as antiapoptotic defense, enhanced DNA repair ability, and powerful antioxidant systems. To overcome MDR, intense efforts have been made to develop synergistic therapeutic strategies by introducing MDR inhibitors or combining chemotherapy with other therapeutic modalities, such as phototherapy, gene therapy, and gas therapy, in the hope that the drug-resistant cells can be sensitized toward chemotherapeutics. In particular, nanotechnology-based drug delivery platforms have shown the potential to integrate multiple therapeutic agents into one system. In this review, the focus was on the recent development of nanostrategies aiming to enhance the efficiency of chemotherapy and overcome the MDR of cancer in a synergistic manner. Different combinatorial strategies are introduced in detail and the advantages as well as underlying mechanisms of why these strategies can counteract MDR are discussed. This review is expected to shed new light on the design of advanced nanomedicines from the angle of materials and to deepen our understanding of MDR for the development of more effective anticancer strategies. This article is categorized under: Nanotechnology Approaches to Biology > Nanoscale Systems in Biology Therapeutic Approaches and Drug Discovery > Nanomedicine for Oncologic Disease.

Inherently nitric oxide containing polymersomes remotely regulated by NIR for improving multi-modal therapy on drug resistant cancer.

The therapeutic potential of nitric oxide (NO) has been highly attractive to tumor treatment, especially for surmounting the multidrug resistance (MDR) of cancer. However, the NO-involved therapy remains extremely challenging because of the difficulty to simultaneously control the NO release rate and real-time concentration. Herein, we construct NO-containing polymersomes with high amount of NO donors inherently grown on the polymer chains to keep the stability. These polymersomes can be simultaneously loaded with photosensitizer of IR780 iodide on the membrane layer and chemotherapeutic of DOX·HCl in the lumen. NO release can be triggered by the reduction conditions, and further accelerated by remote NIR irradiation due to the increased local temperature. The instantaneous NO release with high concentration significantly inhibits the P-gp expression and sensitize the chemotherapy, thus overcoming the tumor MDR and improving the anti-tumor activity. Meanwhile, DOX·HCl release is highly promoted at the intracellular conditions because of the cleavage of acid-labile cis-aconitic amide at endo/lysosomal pH, and the improved hydrophilicity of the membrane layer after NO release. The in vivo results show that the single intravenous injection of polymersome formulation companying with NIR irradiation exerts multi-modal therapies of chemotherapy, PTT/PDT, and NO-therapy on the MCF-7/R tumor models, showing superior and combinational treatment efficacy with the complete eradication of tumors and few side effects.

Toxicity-attenuated mesoporous silica Schiff-base bonded anticancer drug complexes for chemotherapy of drug resistant cancer.

Multidrug resistance (MDR), evoked by improper chemotherapeutic practices, poses a serious threat to public health, which leads to increased medical burdens and weakened curative effects. Taking advantage of the enhanced pharmaceutical effect of Schiff base compounds, an aldehyde-modified mesoporous silica SBA-15 (CHO-SBA-15)-bonded anticancer drug combined with doxorubicin hydrochloride (DOX) was synthesized via a Schiff base reaction. Due to the acid-sensitive imine bonds formed between CHO-SBA-15 and DOX, the as-prepared nanocomposites exhibited pH-responsive drug releasing behaviours, resulting in a more enhanced cytotoxic effect on DOX-resistant tumour cells than that of free drugs. Notably, the in vivo studies indicated that mice treated with CHO-SBA-15/DOX composites evidently showed more attenuated systemic toxicity than the free drug molecules. The siliceous mesopore Schiff base-bonded anticancer drug nanocomposite, with minimal chemical modifications, provides a simplified yet efficient therapeutic nanoplatform to deal with drug-resistant cancer.

Discovery of Novel Autophagy Inhibitors and Their Sensitization Abilities for Vincristine-Resistant Esophageal Cancer Cell Line Eca109/VCR.

Resistance phenomena, especially acquired drug resistance, have been severely hampering the application of chemotherapeutics during cancer chemotherapy. Autophagy plays a role in maintaining the survival of cancer cells and might mediate resistance to chemotherapy drugs. Herein, a new series of 5-amino-2-ether-benzamide derivatives were synthesized and evaluated as autophagy inhibitors. Selected from 14 synthesized compounds as lead autophagy inhibitor, N-(cyclohexylmethyl)-5-(((cyclohexylmethyl)amino)methyl)-2-((4-(trifluoromethyl)benzyl)oxy)benzamide (4 d) showed the most obvious effect of LC3B protein conversion. Further, its autophagy inhibition, evaluated by using transmission electron microscopy and confocal microscopy, showed that the fusion of autophagosomes and lysosomes in the final stage of autophagic flux was suppressed. We also found that 4 d could enhance the chemosensitivity of vincristine in vincristine-resistant esophageal cancer cell line Eca109/VCR in a synergistic, associative manner. Moreover, a computational study showed that 4 d might bind with p62-zz to inhibit autophagy. We also found 4 d to be relatively less cytotoxic to normal cells versus cancer cells than the reported p62-zz inhibitor.

Aptamer-Functionalized DNA Origami for Targeted Codelivery of Antisense Oligonucleotides and Doxorubicin to Enhance Therapy in Drug-Resistant Cancer Cells.

Drug resistance is a major obstacle to the efficient therapy of drug-resistant cancer. To overcome this problem, we constructed a multifunctional DNA origami-based nanocarrier for codelivery of a chemotherapeutic drug (doxorubicin, Dox) and two different antisense oligonucleotides (ASOs; B-cell lymphoma 2 (Bcl2) and P-glycoprotein (P-gp)) into drug-resistant cancer cells for enhanced therapy. To increase the targeting ability of origami, staple strands with 5'-end extended MUC1 sequences were used in the preparation of aptamer-functionalized origami carrying ASOs (Apt-origami-ASO). Dox-loaded Apt-origami-ASO (Apt-Dox-origami-ASO) was prepared by electrostatic adsorption of Dox in origami. Atomic force microscopy (AFM) images demonstrated the successful preparation of Apt-origami-ASO. In vitro studies showed that the Apt-Dox-origami-ASO (Apt-DOA) could controllably release Dox in pH 5.0 phosphate-buffered saline (PBS) buffer and release ASOs in response to glutathione. Further experiments revealed that the origami could protect ASOs against nuclease degradation in 10% FBS. Confocal imaging showed that the Apt-DOA nanocarrier could efficiently enter the Hela/adriamycin (ADR) cells and escape from lysosomes for codelivery of Dox and ASOs into the cytoplasm. The quantitative reverse transcriptase polymerase chain reaction (qRT-PCR) and western blot assays testified the efficient silencing of Bcl2 and P-gp mRNA and downregulation of the corresponding protein expressions by Apt-DOA in Hela/ADR cells. Moreover, with the synergetic effect by codelivery of multi-ASOs and Dox, the anticancer assay showed that Apt-DOA could circumvent multidrug resistance and significantly enhance cancer therapy in Hela/ADR and MCF-7/ADR cells. Hence, this multifunctional origami-based codelivery nanocarrier presents a new strategy for efficient therapy of drug-resistant cancer.