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Per- and polyfluoroalkyl substances (PFAS), specifically perfluorooctanesulfonate (PFOS) and its alternative, 2-[(6-chloro-1,1,2,2,3,3,4,4,5,5,6,6-dodecafluorohexyl)oxy]-1,1,2,2-tetrafluoroethanesulfonic acid (6:2 Cl-PFESA), are associated with environmental health concerns and potential cancer progression. However, their impact on multidrug resistance (MDR) in pancreatic cancer (PC) chemotherapy remains unclear. Here, we employed drug-sensitivity assays, including IC 50 calculations, in vitro and in vivo models with various chemotherapeutics, and paclitaxel (PTX) as a representative agent, combined with transcriptomic/proteomic sequencing and clinical prognostic analysis, to identify MDR-related genes and validate their relevance, with the objective of establishing the correlation between PFOS/6:2 Cl-PFESA exposure and MDR in PC at molecular, cellular, and animal model levels. Our findings demonstrate that PFOS/6:2 Cl-PFESA exposure increases the drug IC 50 in three different PC cell lines for various chemotherapeutic agents. Compared with PFOS, 6:2 Cl-PFESA demonstrated a more pro-MDR effect on PC cells in vitro . In vivo experiments further revealed that PFOS/6:2 Cl-PFESA exposures significantly reduced the efficacy of PTX in PC, with inhibition rates dropping from 78.3% to 23.8%/6.1%, respectively ( p < 0.05). This effect was driven by the aberrant activation of the PI3K-ABCB1 pathway, with 6:2 Cl-PFESA demonstrating a stronger capacity to promote this signal pathway's expression and function compared with PFOS. These data suggest that exposure to PFAS may elevate the risk of MDR and subsequent disease progression. Although marketed as a safer alternative to PFOS, the notable impact of 6:2 Cl-PFESA on MDR highlights the necessity for a comprehensive assessment of its potential carcinogenic risks.

Inspired by the structure of dysoxylactam A (DLA) that has been demonstrated to reverse P-glycoprotein (P-gp)-mediated multidrug resistance (MDR) effectively, 61 structurally simplified cyclolipopeptides were thus designed and synthesized via an effective method, and their reversing P-gp-mediated MDR potentials were evaluated, which provided a series of more potent analogues and allowed us to explore their structure-activity relationship (SAR). Among them, a well-simplified compound, 56 , with only two chiral centers that all derived from amino acids dramatically reversed drug resistance in KBV200 cells at 10 μM in combination with vinorelbine (VNR), paclitaxel (PTX), and adriamycin (ADR), respectively, which is more promising than DLA. The mechanism study showed that 56 reversed the MDR of tumor cells by inhibiting the transport function of P-gp rather than reducing its expression. Notably, compound 56 effectively restored the sensitivity of MDR tumors to VNR in vivo at a dosage without obvious toxicity.

Elesclomol (ES), a copper-binding ionophore, forms an ES-Cu complex with copper ions (Cu(II)). ES-Cu has been proven to induce mitochondrial oxidative stress and copper-dependent cell death (cuprotosis). However, ES-Cu is poorly water-soluble, and its delivery to various cancer cells is a challenge. Herein, we designed a d-α-tocopherol polyethylene glycol 1000 succinate/chondroitin sulfate-cholic acid (TPGS/CS-CA)-based micellar nanoparticle for delivering the ES-Cu complex to various cancer cell lines to demonstrate its efficacy as an anticancer agent. The ES-Cu nanoparticles exerted high encapsulation efficiency and excellent serum stability. The anticancer efficacy of ES-Cu nanoparticles was evaluated in various drug-sensitive cell lines (DU145, PC3, and A549) and drug-resistant cell lines (DU145TXR, PC3TXR, and A549TXR). The results showed that ES-Cu nanoparticles exerted potent anticancer activities in both drug-sensitive and drug-resistant cell lines. The Western blotting, reverse transcription quantitative polymerase chain reaction (RT-qPCR), and molecular docking results suggested that ES-Cu is not a substrate for P glycoprotein (P-gp), which is an efflux transporter potentially causing multidrug resistance (MDR) in cancer cells. ES-Cu nanoparticles could bypass P-gp without compromising their activity, indicating that they may overcome MDR in cancer cells and provide a novel therapeutic strategy. Additionally, the extracellular matrix of ES-Cu nanoparticles-pretreated drug-resistant cells could polarize Raw 264.7 macrophages into the M1 phenotype. Therefore, our TPGS/CS-CA-based ES-Cu nanoparticles provide an effective method of delivering the ES-Cu complex, a promising strategy to overcome MDR in cancer therapy with potential immune response stimulation.

Rapid and accurate diagnosis is crucial for managing the global health threat posed by multidrug-resistant bacterial infections; however, current methods have limitations in either being time-consuming, labor-intensive, or requiring instruments with high costs. Addressing these challenges, we introduce a wireless electrochemical sensor integrating the CRISPR/Cas system with electroconductive polymer dot (PD) nanoparticles to rapidly detect bacterial pathogens from human sputum. To enhance the electroconductive properties, we synthesized copper-ion-immobilized PD (PD-Cu), followed by conjugation of the deactivated Cas9 protein (dCas9) onto PD-Cu-coated Si electrodes to generate the dCas9-PD-Cu sensor. The dCas9-PD-Cu sensor integrated with isothermal amplification can specifically detect target nucleic acids of multidrug-resistant bacteria, such as the antibiotic resistance genes kpc-2 and mecA . The dCas9-PD-Cu sensor exhibits high sensitivity, allowing for the detection of ∼54 femtograms of target nucleic acids, based on measuring the changes in resistivity of the Si electrodes through target capture by dCas9. Furthermore, a wireless sensing platform of the dCas9-PD-Cu sensor was established using a Bluetooth module and a microcontroller unit for detection using a smartphone. We demonstrate the feasibility of the platform in diagnosing multidrug-resistant bacterial pneumonia in patients' sputum samples, achieving 92% accuracy. The current study presents a versatile biosensor platform that can overcome the limitations of conventional diagnostics in the clinic.

Cancer stem cells (CSCs) present a formidable challenge in cancer treatment due to their inherent resistance to chemotherapy, primarily driven by the overexpression of ABC transporters and multidrug resistance (MDR). Despite extensive research on pharmacological small-molecule inhibitors, effectively managing MDR and improving chemotherapeutic outcomes remain elusive. On the other hand, magnetic hyperthermia (MHT) holds great promise as a cancer therapeutic, but there is limited research on its potential to reverse MDR in breast CSCs and effectively eliminate CSCs through combined chemo-hyperthermia. To address these gaps, we developed tumor microenvironment-sensitive, drug-loaded poly(propylene sulfide) (PPS)-coated magnetic nanoparticles (PPS-MnFe). These nanoparticles were employed to investigate hyperthermia sensitivity and MDR reversion in breast CSCs, comparing their performance to that of small-molecule inhibitors. Additionally, we explored the efficacy of combined chemo-hyperthermia in killing CSCs. CSC-enriched breast cancer cells were subjected to low-dose MHT at 42 °C for 30 min and then treated with the chemical MDR inhibitor salinomycin (SAL). The effectiveness of each treatment in inhibiting MDR was assessed by measuring the efflux of the MDR substrate, rhodamine 123 (R123) dye. Notably, MHT induced a prolonged reversal of MDR activity compared with SAL treatment alone. After successfully inhibiting MDR, the breast CSCs were exposed to chemotherapy using paclitaxel to trigger synergistic cell death. The combination of MHT and chemotherapy demonstrated remarkable reductions in stemness properties, MDR reversal, and the effective eradication of breast CSCs in this innovative dual-modality approach.

Transferrin-conjugated polymersomes, transferrin-biotin/avidin/biotin-Pluronic F127-poly(lactic acid) (Tf-F127-PLA), were successfully prepared through a biotin-avidin bridging technique to study their ability to inhibit multidrug resistance of cancer cells. Hydrophilic doxorubicin (DOX) was selected as the model drug to be loaded into Tf-F127-PLA polymersomes. DOX loaded in Tf-F127-PLA polymersomes was released fast initially, followed by a slow release. The effect of the transferrin ligand density of Tf-F127-PLA/DOX polymersomes on their targeting properties was studied by both cytotoxicity and cellular uptake assays against A549 lung cancer cells. It was shown that Tf-F127-PLA/DOX polymersomes had better targeting ability than nontargeted drug-loaded polymersomes. Furthermore, Tf-F127-PLA/DOX polymersomes with 2% Tf molar content have more effective antitumor activity and a higher cellular uptake than those with 4 and 5% Tf molar content. 2% Tf-F127-PLA/DOX polymersomes also exhibited better anticancer ability in multidrug resistant cancer cells A549/ADR than nontargeted PLA-F127-PLA/DOX polymersomes. It was further proved that the endocytosis of polymersomes by A549/ADR cells was an energy-dependent endocytosis process, which was related to clathrin, macrocytosis, and caveolin. Also, the endocytosis of Tf-F127-PLA/DOX polymersomes was proven to be mediated by the transferrin receptor.

We synthesized new pyrrole and indole derivatives as human carbonic anhydrase (hCA) inhibitors with the potential to inhibit the Wnt/β-catenin signaling pathway. The presence of both N 1-(4-sulfonamidophenyl) and 3-(3,4,5-trimethoxyphenyl) substituents was essential for strong hCA inhibitors. The most potent hCA XII inhibitor 15 ( K i = 6.8 nM) suppressed the Wnt/β-catenin signaling pathway and its target genes MYC, Fgf20, and Sall4 and exhibited the typical markers of apoptosis, cleaved poly(ADP-ribose)polymerase, and cleaved caspase-3. Compound 15 showed strong inhibition of viability in a panel of cancer cells, including colorectal cancer and triple-negative breast cancer cells, was effective against the NCI/ADR-RES DOX-resistant cell line, and restored the sensitivity to doxorubicin (DOX) in HT29/DX and MDCK/P-gp cells. Compound 15 is a novel dual-targeting compound with activity against hCA and Wnt/β-catenin. It thus has a broad targeting spectrum and is an anticancer agent with specific potential in P-glycoprotein overexpressing cell lines.

The search for more effective and selective drugs to overcome cancer multidrug resistance is urgent. As such, a new series of ruthenium-cyclopentadienyl ("RuCp") compounds with the general formula [Ru(η 5 -C 5 H 4 R)(4,4'-R'-2,2'-bipy)(PPh 3 )] were prepared and fully characterized. All compounds were evaluated toward non-small cell lung cancer cells with different degrees of cisplatin sensitivity (A549, NCI-H2228, Calu-3, and NCI-H1975), showing better cytotoxicity than the first-line chemotherapeutic drug cisplatin. Compounds 2 and 3 (R' = -OCH 3 ; R = CHO ( 2 ) or CH 2 OH ( 3 )) further inhibited the activity of P-gp and MRP1 efflux pumps by impairing their catalytic activity. Molecular docking calculations identified the R-site P-gp pocket as the preferred one, which was further validated using site-directed mutagenesis experiments in P-gp. Altogether, our results unveil the first direct evidence of the interaction between P-gp and "RuCp" compounds in the modulation of P-gp activity and establish them as valuable candidates to circumvent cancer MDR.

A tower-like Sb III -Se IV -templating polyoxotungstate [H 2 N(CH 3 ) 2 ] 12 Na 7 H 3 [Ce 0.5 /Na 0.5 (H 2 O) 5 ] 2 [SbSe 2 W 21 O 75 ] 2 ·50H 2 O ( 1 ) was synthesized, whose skeleton is assembled from two prolonged lacunary Dawson [SbSe 2 W 21 O 75 ] 13- units and two [Ce 0.5 /Na 0.5 (H 2 O) 5 ] 2+ linkers. The uncommon [SbSe 2 W 21 O 75 ] 13- unit can be viewed as a combination of one [SeW 6 O 21 ] 2- group grafted onto a trivacant Dawson [SbSeW 15 O 54 ] 11- subunit. The conductive composite 1 -Au@rGO containing 1 , gold nanoparticles, and reduced graphene oxide (rGO) was conveniently prepared, using which the 1 -Au@rGO-based electrochemical genosensor was constructed for detecting human multidrug resistance gene segment. This work enriches structural types of dual-heteroatom-inserted polyoxometalates and promotes the application of polyoxometalates in genosensors.

Rational design of multifunctional nanomedicines has revolutionized the therapeutic efficacy of cancers. Herein, we have constructed the functional nucleic acids (FNAs)-engineered nanoplatforms based on the concept of a bio-barcode (BBC) for synergistic targeted therapy of multidrug-resistant (MDR) cancer. In this study, the platinum(IV) prodrug is synthesized to covalently link two kinds of FNAs at a rational ratio to fabricate three-dimensional BBC-like DNA nanoscaffolds, accompanied by the one-pot encapsulation of ZnO nanoparticles (NPs) through electrostatic interaction. The multivalent AS1411 aptamers equipped in ZnO@BBCs facilitate specific and efficient endocytosis into MDR human lung adenocarcinoma cells (A549/DDP). In response to the intracellular environment of A549/DDP cells, such as the lysosome-acidic pH and overexpressed GSH, the ZnO NPs are degraded into Zn 2+ ions for generating reactive oxygen species (ROS), while the Pt(IV) prodrugs are reduced into Pt(II) active species by glutathione (GSH), followed by the release of therapeutic DNAzymes for chemotherapy and gene therapy. In particular, the designed system plays an important role in remodeling the intracellular environment to reverse cancer MDR. On the one hand, the depletion of GSH promotes the downregulation of glutathione peroxidase 4 (GPX4) for amplifying oxidative stress and increasing lipid peroxidation (LPO), resulting in the activation of ferroptosis. On the other hand, the silence of early growth response protein 1 (Egr-1) mRNA by Zn 2+ -dependent DNAzymes directly inhibits the proliferation and migration of MDR cells, which further suppresses the P-glycoprotein (P-gp)-mediated drug efflux. Thus, the proposed nanoplatforms show great promise for the development of versatile therapeutic tools and personalized nanomedicines for MDR cancers.

Nonsubstrate allosteric inhibitors of P-glycoprotein (Pgp), which are considered promising modulators for overcoming multidrug resistance (MDR), are relatively unknown. Herein, we designed and synthesized amino acids bearing amide derivatives of pyxinol, the main ginsenoside metabolite produced by the human liver, and examined their MDR reversal abilities. A potential nonsubstrate inhibitor ( 7a ) was identified to undergo high-affinity binding to the putative allosteric site of Pgp at the nucleotide-binding domains. Subsequent assays confirmed that 7a (25 μM) was able to suppress both basal and verapamil-stimulated Pgp-ATPase activities (inhibition rates of 87 and 60%, respectively) and could not be pumped out by Pgp, indicating that it was a rare nonsubstrate allosteric inhibitor. Moreover, 7a interfered with Pgp-mediated Rhodamine123 efflux while exhibiting high selectivity for Pgp. Notably, 7a also markedly enhanced the therapeutic efficacy of paclitaxel, with a tumor inhibition ratio of 58.1%, when used to treat nude mice bearing KBV xenograft tumors.

Tumor drug resistance has long been a major challenge in medical oncology. Ferroptosis is a form of regulated cell death with promising clinical applications. However, the efficacy of ferroptosis-inducing agents is often limited by endogenous factors when used alone, and thus, synergistic therapy offers a promising strategy to address this issue. In this study, we developed an iron-doped metal-organic framework (MOF), Fe/ZIF-8, loaded with glucose oxidase (Gox), l-arginine (l-arg), and adriamycin hydrochloride (Dox). The folic acid (FA)-targeted ZIF-8 (GLDFe/Z-FA) prepared was shown to be a multifunctional nanoparticle based on endogenous hydrogen peroxide (H 2 O 2 ) and glucose, which trigger adaptive cellular responses in cancer cells. The intracellular glucose level and adenosine-triphosphate (ATP) content decreased, indicating that GLDFe/Z-FA reduced the glucose metabolic rate and induced tumor starvation. And the generated • OH and H 2 O 2 induced reactive oxygen species (ROS) overload to implement chemodynamic therapy (CDT). ROS catalyzed l-arg released from GLDFe/Z-FA to release nitric oxide (NO), which inhibited P-glycoprotein expression, prevented Dox efflux, and accumulated intracellular content of Dox to enhance cytotoxicity. GLDFe/Z-FA also catalyzed glutathione degradation, which further disrupted intracellular redox homeostasis, enhanced CDT, and induced cell death. It was shown to follow the ferroptosis pathway and strongly inhibited tumor proliferation both in vitro and in vivo . These findings demonstrate that GLDFe/Z-FA effectively inhibits tumor proliferation, highlighting its potential as a viable therapeutic approach to suppress cancer progression.

A proposed strategy to overcome multidrug resistance (MDR) of anticancer drugs in chemotherapy is to disable the efflux function of P-glycoprotein (P-gp). In this study, based on ring-merging and fragment-growing strategies, 105 novel benzo five-membered heterocycle derivatives were designed, synthesized, and screened. Exploration of the structure-activity relationship (SAR) led to the identification of d7 with low cytotoxicity and promising reversal activity to doxorubicin in MCF-7/ADR cells. Furthermore, the mechanism studies revealed that the reversal activity of d7 stemmed from the inhibition of P-gp efflux. Molecular docking further clarified the observed trends in SAR with d7 displaying potent affinity to P-gp. Additionally, coadministration of d7 with doxorubicin achieved stronger antitumor activity in a xenograft model than doxorubicin alone. These results suggest that d7 is a potential MDR reveal agent acting as a P-gp inhibitor and provides guidelines for the future development of new P-gp inhibitors.

Targeted inhibition of a drug efflux transporter P-glycoprotein (P-gp) is an important strategy to reverse multidrug resistance in cancer chemotherapy. In this study, a rationally structural simplification to natural tetrandrine was performed based on molecular dynamics simulation and fragment growth, leading to an easily prepared, novel, and simplified compound OY-101 with high reversal activity and low cytotoxicity. Its excellent synergistic anti-cancer effect with vincristine (VCR) against drug-resistant cells Eca109/VCR was confirmed by reversal activity assay, flow cytometry, plate clone formation assay, and drug synergism analysis (IC 50 = 9.9 nM, RF = 690). Further mechanism study confirmed that the OY-101 was a specific and efficient P-gp inhibitor. Importantly, OY-101 increased VCR sensitization in vivo without obvious toxicity. Overall, our findings may provide an alternative strategy for the design of novel specific P-gp inhibitor as an anti-tumor chemotherapy sensitizer.

Natural macrocycles have shown impressive activity to overcome P-glycoprotein (P-gp)-mediated multidrug resistance (MDR). However, the total synthesis and structural modification of natural macrocycles are challenging, which would hamper the deeper investigations of their structure-activity relationship (SAR) and drug likeness. Herein, we describe a modular biomimetic strategy to expeditiously achieve a new class of macrocycles featuring polysubstituted 1,3-diene, which efficiently inhibited P-gp and reversed MDR in cancer cells. The SAR analysis revealed that the size and linker of the macrocycles are important structural characteristics to restore activity. Particularly, 32 containing a naphthyl group and (d)-Phe moiety has higher potency with an excellent reversal fold than verapamil at a concentration of 5 μM, which induces conformational change of P-gp and inhibits its function instead of altering P-gp expression. Furthermore, 23 and 32 were identified to be attractive leads, which possess a good pharmacokinetic profile and antitumor activity in a KBV200 xenograft mouse model.

The multi-drug resistance (MDR) of cancers is one of the main barriers for the success of diverse chemotherapeutic methods and is responsible for most cancer deaths. Developing efficient approaches to overcome MDR is still highly desirable for efficient chemotherapy of cancers. The delivery of targeted anticancer drugs that can interact with mitochondrial DNA is recognized as an effective strategy to reverse the MDR of cancers due to the relatively weak DNA-repairing capability in the mitochondria. Herein, we report on a polyprodrug that can sequentially target cancer cells and mitochondria using folic acid (FA) and tetraphenylphosphonium (TPP) targeting moieties, respectively. They were conjugated to the terminal groups of the amphiphilic block copolymer prodrugs composed of poly[oligo(ethylene glycol) methyl ether methacrylate] (POEGMA) and copolymerized monomers containing cinnamaldehyde (CNM) and doxorubicin (DOX). After self-assembly into micelles with the suitable size (∼30 nm), which were termed as TF@CNM + DOX, and upon intravenous administration, the micelles can accumulate in tumor tissues. After FA-mediated endocytosis, the endosomal acidity (∼pH 5) can trigger the release of CNM from TF@CNM + DOX micelles, followed by enhanced accumulation into the mitochondria via the TPP target. This promotes the overproduction of reactive oxygen species (ROS), which can subsequently enhance the intracellular oxidative stress and trigger ROS-responsive release of DOX into the mitochondria. TF@CNM + DOX shows great potential to inhibit the growth of DOX-resistant MCF-7 ADR tumors without observable side effects. Therefore, the tumor and mitochondria dual-targeting polyprodrug design represents an ideal strategy to treat MDR tumors through improvement of the intracellular oxidative level and ROS-responsive drug release.

Identifying effective reversal agents overcoming multidrug resistance with causal mechanisms from an efflux pump protein is of vital importance for enhanced tumor chemotherapy in clinic. To achieve this end, we construct a metal cluster-based probe, named clusterbody, to develop flow sorting-assisted single-cell mass spectrometry analysis. This clusterbody synthesized by biomimetic mineralization possesses an antibody-like property to selectively recognize an efflux pump protein. The intrinsic red fluorescence emission of the clusterbody facilitates fluorescence-activated high-throughput cell sorting of subpopulations with different multidrug resistance levels. Furthermore, based on the accurate formula of the clusterbody, the corresponding protein abundance at the single-cell level is determined through detecting gold content via precise signal amplification by laser ablation inductively coupled plasma mass spectrometry. Therefore, the effect of reversal agent treatment overcoming multidrug resistance is evaluated in a quantitative manner. This work opens a new avenue to identify reversal agents, shedding light on developing combined or synergetic tumor therapy.

Cancer multidrug resistance (MDR) is an important reason that results in chemotherapy failure. As a main mechanism of MDR, overexpressed P-glycoprotein (P-gp) utilizes adenosine triphosphate (ATP) to actively pump chemotherapy drugs out of cells. In addition, metabolic reprogramming of drug-resistant tumor cells (DRTCs) exacerbates the specific hypoxic microenvironment and promotes tumor metastasis and recurrence. Therefore, we propose a novel sonodynamic therapy (SDT) paradigm to induce energy metabolism disorder and drug resistance change of DRTCs. A US-controlled "Nanoenabled Energy Metabolism Jammer" (TL@HPN) is designed using perfluoropentane (PFP) adsorbing oxygen in the core, and a targeting peptide (CGNKRTR) is attached to the liposome as the delivery carrier shell to incorporate hematoporphyrin monomethyl ether (HMME) and paclitaxel (PTX). The TL@HPN with ultrasonic/photoacoustic imaging (PAI/USI) precisely controlled the release of drugs and oxygen after being triggered by ultrasound (US), which attenuated the hypoxic microenvironment. SDT boosted the reactive oxygen species (ROS) content in tumor tissues, preferentially inducing mitochondrial apoptosis and maximizing immunogenic cell death (ICD). Persistently elevated oxidative stress levels inhibited ATP production and downregulated P-gp expression by disrupting the redox balance and electron transfer of the respiratory chain. We varied the effect of TL@HPN combined with PD-1/PD-L1 to activate autoimmunity and inhibit tumor metastasis, providing a practical strategy for expanding the use of SDT-mediated tumor energy metabolism.

Multidrug resistance (MDR) is a major obstacle to effective cancer treatment. Therefore, developing effective approaches for overcoming the limitation of MDR in cancer therapy is very essential. Chemotherapy combined with photothermal therapy (PTT) is a potential therapeutic option against MDR. Herein, we developed a subcellular-targeted near-infrared (NIR)-responsive nanomedicine (Fe 3 O 4 @PDA-TPP/S 2 -PEG-hyd-DOX, abbreviated as Fe 3 O 4 -ATSPD) as a new photothermal agent with improved photothermal stability and efficiency. This system demonstrates high stability in blood circulation and can be accumulated at the tumor site by magnetic targeting enhanced permeability and retention effect (EPR). Near-infrared (NIR) irradiation at the tumor site generates a photothermal effect from the photosensitizer Fe 3 O 4 @PDA, leading to a dramatic decrease in mitochondrial membrane potential. Simultaneously, the conjugated drugs released under low pH condition in endosomes or lysosomes cause nucleus DNA damage and cell apoptosis. This subcellular-targeted NIR-responsive nanomedicine with efficient integration of diagnosis and therapy could significantly enhance MDR cancer treatment by combination of chemotherapy and PTT.

In a continuing search of dual P-gp and hCA XII inhibitors, we synthesized and studied new N , N -bis(alkanol)amine aryl diester derivatives characterized by the presence of a coumarin group. These hybrids contain both P-gp and hCA XII binding groups to synergistically overcome the P-gp-mediated multidrug resistance (MDR) in cancer cells expressing both P-gp and hCA XII. Indeed, hCA XII modulates the efflux activity of P-gp and the inhibition of hCA XII reduces the intracellular pH, thereby decreasing the ATPase activity of P-gp. All compounds showed inhibitory activities on P-gp and hCA XII proteins taken individually, and many of them displayed a synergistic effect in HT29/DOX and A549/DOX cells that overexpress both P-gp and hCA XII, being more potent than in K562/DOX cells overexpressing only P-gp. Compounds 5 and 14 were identified as promising chemosensitizer agents for selective inhibition in MDR cancer cells overexpressing both P-gp and hCA XII.

Chemotherapy is an important method for the treatment of lung cancer, but multidrug resistance (MDR) greatly reduces the efficacy. The superfamily of ATP-binding cassette (ABC) transport proteins is related to MDR. As a subfamily of ABC proteins, ABCG2/BCRP (breast cancer resistance protein, BCRP) is considered a major player in the development of cancer MDR. For the stratification of chemotherapeutic choices, we constructed Cy5.5- or 89 Zr-labeled ABCG2-targeted monoclonal antibody (mAb) ABCG2-PKU1 for noninvasive evaluation of ABCG2 expression in lung cancer xenograft models. ABCG2 expression was screened in H460/MX (mitoxantrone resistant), H460, and H1299 human lung cancer cell lines using Western blotting. ELISA, flow cytometry, and cell immunofluorescent staining were used to evaluate the binding ability of ABCG2-PKU1 to ABCG2 antigen. Lung cancer murine xenograft models were built for in vivo experiments. ABCG2-PKU1 was labeled with Cy5.5 (Cy5.5-ABCG2) for fluorescent imaging and radiolabeled with 89 Zr ( 89 Zr-DFO-ABCG2) for immunoPET imaging following the conjugation with p-SCN-deferoxamine (DFO). In vivo imaging was performed in lung cancer models at 2, 24, 48, 72, 96, 120, 144, and 168 h postinjection. Ex vivo biodistribution was conducted after the terminal time point of imaging. Finally, tissue immunohistochemical staining was used to evaluate the tumor expression of ABCG2. Western blotting showed that the H460/MX cells had a high ABCG2 expression level whereas H460 and H1299 had moderate and low levels. ELISA, flow cytometry, and cell immunofluorescent staining results validated the good binding affinity between ABCG2-PKU1 and ABCG2. The H460/MX and H460 cells were used to build positive lung cancer models, and H1299 cells were used to build negative models. The fluorescent imaging showed that the tumor average radiant efficiency of Cy5.5-ABCG2 reached the maximum at 72 and 120 h in H460/MX and H460 respectively ( n = 3, P < 0.01). The tumor uptake of Cy5.5-ABCG2 in H1299 ( n = 3) was significantly lower than H460/MX and H460 ( P < 0.01). ImmunoPET imaging showed that the tumor uptake of 89 Zr-DFO-ABCG2 in H460/MX was significantly higher than H460, with a maximum of 4.15 ± 0.41 %ID/g and 2.81 ± 0.24 %ID/g at 168 and 144 h, respectively ( n = 5, P < 0.01). The H1299 tumors showed significantly lower uptake than H460/MX and H460 ( n = 5, P < 0.01). The radioactive uptake of 89 Zr-DFO-ABCG2 among three groups in the heart, liver, and kidney gradually decreased over time. Ex vivo biodistribution verified the differential tumor uptake among the three groups ( P < 0.01). Immunohistochemical staining revealed that the H460/MX tumor had the highest expression of ABCG2, whereas H460 and H1299 had the moderate and lowest expression, respectively. Therefore, in this study, fluorescent and immunoPET imaging of lung cancer MDR models using Cy5.5-ABCG2 and 89 Zr-DFO-ABCG2 noninvasively evaluated the differential expression of ABCG2, which are expected to be used for the diagnosis and the selection for clinical treatment options for lung cancer MDR patients in future applications.

Reversing hypoxia-mediated multidrug resistance (MDR) presents a unique challenge in clinical chemotherapy. Here, a sequential dual delivery system composited with Cyclooxygenase-2 siRNA (siCOX-2) in poly-d-arginine (9R)/2-deoxyglucose (DG)-loaded gold nanostar (GNS) (siCOX-2@RDG) and paclitaxel (PTX)-loaded thermosensitive liposome (PTSL) was proposed to conquer the hypoxia-mediated MDR in tumors. As a result, the prepared siCOX-2@RDG exhibited a starlike morphology with a uniform particle size of 194.36 ± 1.44 nm and a ζ-potential of -11.83 ± 2.01 mV. In vitro , PTSL displayed expected thermal-responsive release properties. As expected, siCOX-2@RDG displayed exceptional DG-mediated hypoxia-targeting capability both in vitro and in vivo and downregulated the expression of COX-2 successfully. Meanwhile, GNS-triggered hyperthermia elevated the cellular uptake of PTSL in PTX-resistant HepG2(HepG2/PTX) cells in vitro and enhanced the permeability of tumor tissues, thus elevating the valid retention of PTX into solid tumors. Finally, we demonstrated that the sequential dual systems composed of siCOX-2@RDG and PTSL could reverse hypoxia-mediated MDR and exhibit excellent synergistic antitumor effects both in vitro and in vivo , prolonging the survival of tumor-bearing mice. The devised sequential dual systems, composed of two independent nanosystems, have a promising potential to overcome hypoxia-mediated MDR in clinical practice.

A recently proposed strategy to overcome multidrug resistance (MDR) in cancer is to target the collateral sensitivity of otherwise resistant cells. We designed a library of 120 compounds to explore the chemical space around previously identified 8-hydroxyquinoline-derived Mannich bases with robust MDR-selective toxicity. We included compounds to study the effect of halogen and alkoxymethyl substitutions in R5 in combination with different Mannich bases in R7, a shift of the Mannich base from R7 to R5, as well as the introduction of an aromatic moiety. Cytotoxicity tests performed on a panel of parental and MDR cells highlight a strong influence of experimentally determined p K a values of the donor atom moieties, indicating that protonation and metal chelation are important factors modulating the MDR-selective anticancer activity of the studied compounds. Our results identify structural requirements increasing MDR-selective anticancer activity, providing guidelines for the development of more effective anticancer chelators targeting MDR cancer.

The ATP-binding cassette, subfamily G, isoform 2 protein (ABCG2), as an important member of ABC transporters, plays a key role in multidrug resistance (MDR) in cancer and has been widely considered as a marker of cancer stem cells (CSC). Reagents capable of simultaneously targeting ABCG2 and reversing MDR have great clinical application values, but their development is highly challenging. Herein, ABCG2 glycosylated extracellular region-binding aptamers were efficiently screened by a cladded molecularly imprinted polymer (cMIP)-based in vitro screening method and further rationally engineered into cyclic bivalent aptamers. Experiments showed that both the monovalent and cyclic bivalent aptamers could specifically bind ABCG2 and thereby specially target CSC of human colorectal carcinomas (CoCSC), while the latter could effectively reverse MDR in drug-resistant liver cancer cells (HepG2/ADR). Different from currently predominant small molecule inhibitors, the reversal of MDR relied on a different mechanism; the cyclic bivalent aptamers bound the two monomers of ABCG2 dimers simultaneously and thereby blocked the ABCG2-mediated drug-pumping channel, resulting in increased intracellular accumulation of substrate drugs. This study opened a new access to the development of affinity reagents for targeting CSC and reversing MDR, holding great prospects in cancer diagnosis and treatment.

Multidrug resistance to chemotherapeutic drugs is one of the major causes for the failure of cancer treatment. Therefore, there is an urgent need to develop anticancer agents that can combat multidrug-resistant cancers effectively and mitigate drug resistance. Here, we report a rational design of anticancer heterochiral β-peptide polymers as synthetic mimics of host defense peptides to combat multidrug-resistant cancers. The optimal polymer shows potent and broad-spectrum anticancer activities against multidrug-resistant cancer cells and is insusceptible to anticancer drug resistance owing to its membrane-damaging mechanism. The in vivo study indicates that the optimal polymer efficiently inhibits the growth and distant transfer of solid tumors and the metastasis and seeding of circulating tumor cells. Moreover, the polymer shows excellent biocompatibility during anticancer treatment on animals. In addition, the β-peptide polymers address those prominent shortcomings of anticancer peptides and have superior stability against proteolysis, easy synthesis in large scale, and low cost. Collectively, the structural diversity and superior anticancer performance of β-peptide polymers imply an effective strategy in designing and finding anticancer agents to combat multidrug-resistant cancers effectively while mitigating drug resistance.

Overexpressed P-glycoprotein (P-gp), as the key factor in multidrug resistance (MDR), can greatly reduce intracellular drug levels as a result of chemotherapeutic drug efflux out of cancer cells. Although various P-gp antagonists have been developed to circumvent the MDR effect, the common strategies of physical entrapment or chemical conjugation of anticancer drugs may inevitably induce unstable circulation in vivo or poor response in cancer cells, greatly limiting the therapeutic efficacy. Herein a double-drug-based supramolecular complex (DDSC) was first constructed based on the host-guest interactions between two active drugs, curcumin (Cur)-bridged bis(β-cyclodextrin) and ferrocene-linked camptothecin (CPT). Supramolecular dual drug nanomicelles (SDDNMs) formed by the DDSC self-assembly are proposed to work against the MDR effect, in which Cur as a P-gp antagonist in combination with CPT realized stable transport in vivo and efficient stimuli-responsiveness in cells. In vitro and in vivo studies further confirmed that SDDNMs effectively circumvented the drug efflux induced by the MDR effect and remarkably enhanced the synergistic therapeutic effects.

Despite the development of various therapeutic modalities to tackle cancer, multidrug resistance (MDR) and incomplete destruction of deep tissue-buried tumors remain as long-standing challenges responsible for tumor recurrence and low survival rates. In addition to the MDR and deep tissue photoactivation problems, most primary tumors metastasize to the lungs and lymph nodes to form secondary tumors. Therefore, it leaves a great challenge to develop theranostic approaches to combat both MDR and deep tissue photoactivation problems. Herein, we develop a versatile plasmonic CuO/Cu 2 O truncated nanocube-based theranostic nanomedicine to act as a triple modal near-infrared fluorescence (NIRF) imaging agent in the biological window II (1000-1500 nm)/photoacoustic imaging (PAI)/ T 1 -weighted magnetic resonance (MR) imaging agents, sensitize the formation of singlet oxygen ( 1 O 2 ) to exert nanomaterial-mediated photodynamic therapeutic (NIR-II NmPDT), and absorb long NIR light (i.e., 1550 nm) in the biological window III (1500-1700 nm) to exert nanomaterial-mediated photothermal therapeutic (NIR-III NmPTT) effects for the effective destruction of multi-drug-resistant lung tumors. We found that H69AR lung cancer cells do not create drug resistance toward plasmonic CuO/Cu 2 O TNCs-based nanomedicines.

Antimicrobial resistance is one of the major problems in current practical medicine. The spread of genes coding for resistance determinants among bacteria challenges the use of approved antibiotics, narrowing the options for treatment. Resistance to carbapenems, last resort antibiotics, is a major concern. Metallo-β-lactamases (MBLs) hydrolyze carbapenems, penicillins, and cephalosporins, becoming central to this problem. These enzymes diverge with respect to serine-β-lactamases by exhibiting a different fold, active site, and catalytic features. Elucidating their catalytic mechanism has been a big challenge in the field that has limited the development of useful inhibitors. This review covers exhaustively the details of the active-site chemistries, the diversity of MBL alleles, the catalytic mechanism against different substrates, and how this information has helped developing inhibitors. We also discuss here different aspects critical to understand the success of MBLs in conferring resistance: the molecular determinants of their dissemination, their cell physiology, from the biogenesis to the processing involved in the transit to the periplasm, and the uptake of the Zn(II) ions upon metal starvation conditions, such as those encountered during an infection. In this regard, the chemical, biochemical and microbiological aspects provide an integrative view of the current knowledge of MBLs.

The combination of high-intensity focused ultrasound (HIFU) and chemotherapy has promising potential in the synergistic treatment of various types of solid tumors. However, the clinical efficacy of HIFU in combination chemotherapy is often impeded by the pre-existing hypoxia tumor microenvironment-induced multidrug resistance (MDR). Therefore, it is imperative for HIFU combined with chemotherapy to overcome MDR by improving the tumor hypoxic microenvironment. Hence, we developed highly stable nanoparticles (P@BDOX/β-lapachone-NO-NPs) with intracellular nitric oxide (NO)- and reactive oxygen species (ROS)-generating capabilities at the tumor site to relieve the hypoxic tumor microenvironment in solid tumors. Doxorubicin prodrug (boronate-DOX, BDOX) and β-lapachone were concurrently loaded onto actively targeted pH (low) insertion peptides (pHLIPs)-poly(ethylene glycol) and nitrated gluconic acid copolymers. Our results showed that the ability of P@BDOX/β-lapachone-NO-NPs to generate NO and ROS simultaneously is vital for the sensitization of hypoxic solid tumors for chemotherapy, as evidenced by the suppression of tumor cells and tissues ( in vitro and in the nude mice model). Thus, this combined therapy holds considerable potential in the management of hypoxic solid tumors.

Multidrug resistance (MDR) is identified as a major impediment to the efficient chemotherapy of cancer, and considerable endeavors have been devoted to reverse MDR containing structuring varieties of multifunctional nanocarriers. Here, a specially light-activated hollow mesoporous silica nanocontainer with an in situ-synthesized Au nanorod (AuNR) core and a surface-modified hairpin structure DNA gatekeeper is reported for treating MDR tumor cells. In this system, the AuNR only fills part of the space in hollow mesoporous silica due to its controllable size, and the remaining space is used to load enough DOX. By controlling the near-infrared (NIR) laser intensity and exposure duration, the configuration of hairpin-structured DNA ( T m = 51.4 °C) can change reversibly and then trigger the controllable intracellular release of DOX, leading to a significantly enhanced chemotherapeutic efficacy and adjustable photothermal treatment for multidrug-resistant cancer cells. The in vitro experiments showed that this system could effectively overcome the MDR of HepG2-adm cells (a MDR cell line of human hepatocarcinoma cells) by the increased concentration of DOX intracellularly and the photothermal conversion of AuNRs, even at a low concentration (e.g., 30 μg mL -1 ). Therefore, this NIR-triggered chemo-photothermal synergistic treatment system can be used as a promising efficient strategy in reversing the multidrug resistance for cancer therapy.

Acinetobacter baumannii has emerged as a major bacterial pathogen during the past three decades. The majority of the A. baumannii infections occur in hospitals and are caused by strains endowed with high desiccation tolerance, which represents an essential feature for the adaptation to the nosocomial environment. This work aims at investigating the desiccation response of the multidrug-resistant A. baumannii strain ACICU as a function of the bacterial growth phase and oxygen availability, by correlating bacterial survival with shape alterations. The three-dimensional morphological analysis of bacteria was carried out by atomic force microscopy (AFM), following the evolution of bacterial shape descriptors, such as the area, volume, roughness of individual cell membranes, and the cell cluster roughness, which exhibited peculiar and distinctive behavior as a function of the growth conditions. AFM images of A. baumannii ACICU cells revealed the prevalence of the coccoid morphology at all growth stages, with a tendency to reduce their size in the stationary phase, accompanied by a higher survival rate to air-drying. Moreover, cells harvested from the logarithmic phase featured a larger volume and resulted to be more sensitive to desiccation compared to the cells harvested at later growth stages. In addition, oxygen deprivation caused a significant decrease in cellular size and was associated with the formation of pores in the cell membrane, accompanied by a relative reduction in culturability after desiccation. Morphological plasticity and multidrug resistance may contribute to desiccation tolerance and therefore to persistence in the hospital setting.

The use of nontherapeutic broad-spectrum antimicrobial agents triclosan (TCS) and benzalkonium chloride (BC) can contribute to bacterial resistance to clinically relevant antibiotics. Antimicrobial-resistant bacteria within wastewater may reflect the resistance burden within the human microbiome, as antibiotics and pathogens in wastewater can track with clinically relevant parameters during perturbations to the community. In this study, we monitored culturable and resistant wastewater bacteria and cross-resistance to clinically relevant antibiotics to gauge the impact of each antimicrobial and identify factors influencing cross-resistance profiles. Bacteria resistant to TCS and BC were isolated from wastewater influent over 21 months, and cross-resistance, taxonomy, and monthly changes were characterized under both antimicrobial selection regimes. Cross-resistance profiles from each antimicrobial differed within and between taxa. BC-isolated bacteria had a significantly higher prevalence of resistance to "last-resort antibiotic" colistin, while isolates resistant to TCS exhibited higher rates of multidrug resistance. Prevalence of culturable TCS-resistant bacteria decreased over time following Food and Drug Administration (FDA) TCS bans. Cross-resistance patterns varied according to sampling date, including among the most clinically important antibiotics. Correlations between strain-specific resistance profiles were largely influenced by taxonomy, with some variations associated with sampling date. The results reveal that time, taxonomy, and selection by TCS and BC impact features of cross-resistance patterns among diverse wastewater microorganisms, which could reflect the variety of factors influencing resistance patterns relevant to a community microbiome.

Hypoxia is a hostile hallmark of most solid tumors, which often leads to multidrug resistance (MDR) and causes the failure of chemotherapy. Hypoxia also promotes epithelial-mesenchymal transition (EMT), leading to acceleration of tumor metastasis. Many chemotherapeutic drugs can further exacerbate hypoxia and thus promote metastasis. Therefore, relieving hypoxia is necessary for chemotherapy to inhibit both MDR and EMT. Herein, highly stable cerasomal perfluorocarbon nanodroplets with an atomic layer of polyorganosiloxane surface and pH-sensitive tumor-targeting peptide (D-vPCs-O 2 ) were fabricated to co-deliver oxygen and therapeutic drug, doxorubicin. High-intensity focused ultrasound (HIFU) was utilized to trigger the co-release of doxorubicin and oxygen and simultaneously enhance ultrasound imaging, therefore achieving imaging-guided drug delivery. Mild-temperature HIFU (M-HIFU) not only triggered oxygen release from nanodroplets but also slightly elevated tumor temperature to accelerate tumor blood flow. The oxygen release and temperature elevation jointly relieved tumor hypoxia and alleviated MDR, which greatly enhanced the drug therapeutic efficacy as compared to clinically used doxorubicin and Doxil. Overall side effects were also largely reduced owing to the ultrastable drug loading of cerasome. The improvement of insufficient chemotherapy and the relief of tumor hypoxia corporately down-regulated TGF-β1, leading to the alleviation of EMT, and therefore significantly inhibited tumor metastasis. When "D-vPCs-O 2 + M-HIFU" was utilized as a neoadjuvant chemotherapy, nanodroplets down-regulated heat shock proteins, reducing tumor relapse after the high-temperature HIFU (H-HIFU)-mediated hyperthermia ablation. The chemo-hyperthermia therapy totally eradicated tumors without any relapse or metastasis, providing a promising way to treat the triple-negative breast cancer, which is highly malignant, easily metastatic, and lacks effective treatments.

Multidrug resistance (MDR) of a tumor is the main cause of failure of clinical chemotherapy. Herein, we report a simple, yet versatile, tumor-targeting "calcium ion nanogenerator" (TCaNG) to reverse drug resistance by inducing intracellular Ca 2+ bursting. Consequently, the TCaNG could induce Ca 2+ bursting in acidic lysosomes of tumor cells and then reverse drug resistance according to the following mechanisms: (i) Ca 2+ specifically accumulates in mitochondria, suppressing cellular respiration and relieving tumor hypoxia, thus inhibiting P-glycoprotein biosynthesis by downregulating HIF-1α expression. (ii) Ca 2+ -bursting-induced respiratory depression blocks intracellular ATP production, which further leads to the P-gp incompetence. As a result, the TCaNG could decrease the IC 50 of DOX to MCF-7/ADR cells by approximately 30 times and reduce the proliferation of drug-resistant tumors by approximately 13 times without obvious side effects. This simple, safe, and effective "Ca 2+ bursting" strategy holds the potential for clinical application in tumor treatment.

Clinically approved doxorubicin (Dox)-loaded liposomes (e.g., Doxil) guarantee good biosafety, but their insufficient nuclear delivery of Dox (<0.4%) after cellular uptake significantly hampers their final anticancer efficacy. Here, we report that simply doping protoporphyrin IX (PpIX, a commonly used hydrophobic photosensitizer) into the lipid bilayers of Dox-loaded liposomes (the resultant product is termed PpIX/Dox liposomes) is a feasible way to promote the nuclear delivery of Dox. This facile strategy relies on a unique property of PpIX-it presents considerably higher affinity for the real plasma membrane over its liposomal carrier, which drives the doped PpIX molecules to detach from the liposomes when encountering cancer cells. We demonstrate that this process can trigger the efficient release of the loaded Dox molecules and allow them to enter the nuclei of MCF-7 breast cancer cells without being trapped by lysosomes. Regarding the drug-resistant MCF-7/ADR cells, the aberrant activation of the efflux pumps in the plasma membranes expels the internalized Dox. However, we strikingly find that the robust drug resistance can be reversed upon mild laser irradiation because the photodynamic effect of PpIX disrupts the drug efflux system (e.g., P-glycoprotein) and facilitates the nuclear entry of Dox. As a proof-of-concept, this PpIX doping strategy is also applicable for enhancing the effectiveness of cisplatin-loaded liposomes against both A549 and A549/DDP lung cancer cells. In vivo experimental results prove that a single injection of PpIX/Dox liposomes completely impedes the growth of MCF-7 tumors in nude mice within 2 weeks and, in combination with laser irradiation, can synergistically ablate MCF-7/ADR tumors. Biosafety assessments reveal no significant systemic toxicity caused by PpIX/Dox liposomes. This work exemplifies a facile method to modulate the subcellular fate of liposomal drugs and may inspire the optimization of nanopharmaceuticals in the near future.

Gas therapy has emerged as a forceful strategy for augmenting the effects of chemotherapeutic drugs against cancer cells. However, it remains extremely challenging to effectively deliver gas into tissues of interest and unravel its underlying mechanisms. Herein, we designed a near-infrared (NIR) light-switchable nitric oxide (NO) delivery nanosystem for high-efficacy multidrug resistance (MDR) reversal in cancer therapy based on a yolk-shell upconverting nanoparticles@magnesium silica (UCNP@MgSiO 3 ). The internal hollow cavity and flower-like mesoporous shell of UCNPs@MgSiO 3 not only enabled a significantly high encapsulation capacity for the NO precursor (BNN6) and doxorubicin (DOX) but also allowed the enhanced cellular uptake, resulting in NIR-triggered NO generation and low pH-triggered DOX release in cancer cells. Mechanistically, intracellular NO can downregulate the drug efflux-related P-glycoprotein and adenosine 5'-triphosphate-binding cassette transporters, thereby increasing the DOX accumulation in the cell nuclei. Such combination therapy of NO and DOX induced the apoptosis of MDR cells and completely inhibited in vivo MDR tumor growth. We further elucidated the therapy mechanism via proteomic profiling, showcasing the downregulation of the ubiquitin-proteasome pathway and nuclear factor kappa-B signaling pathway in the NO-treated MDR cells. Therefore, our findings develop a promising nanoscale gas/drug delivery paradigm for fighting MDR tumors and providing molecular insights into cancer therapy.

We report on tailored lipid-polymer hybrid nanoparticles (NPs) delivering nitric oxide (NO) under the control of visible light as a tool for overcoming doxorubicin (DOX) resistance. The NPs consist of a polymeric core and a coating. They are appropriately designed to entrap DOX in the poly(lactide- co -glycolide) core and a NO photodonor (NOPD) in the phospholipid shell to avoid their mutual interaction both in the ground and excited states. The characteristic red fluorescence of DOX, useful for its tracking in cells, is well preserved upon incorporation within the NPs, even in the copresence of NOPD. The NP scaffold enhances the NO photoreleasing efficiency of the entrapped NOPD when compared with that of the free compound, and the copresence of DOX does not significantly affect such enhanced photochemical performance. Besides, the delivery of DOX and NOPD from NPs is also not mutually influenced. Experiments carried out in M14 DOX-resistant melanoma cells demonstrate that NO release from the multicargo NPs can be finely regulated by excitation with visible light, at a concentration level below the cytotoxic doses but sufficient enough to inhibit the efflux transporters mostly responsible for DOX cellular extrusion. This results in increased cellular retention of DOX with consequent enhancement of its antitumor activity. This approach, in principle, is not dependent on the type of chemotherapeutic used and may pave the way for new treatment modalities based on the photoregulated release of NO to overcome the multidrug resistance phenomenon and improve cancer chemotherapies.

Supramolecular hydrogels based on inclusion complexation between cyclodextrins (CDs) and polymers have attracted much interest because of their potential for biomedical applications. It is also attractive to incorporate stimuli-responsive properties into the system to create "smart" hydrogels. Herein, a poly( N -isopropylacrylamide) (PNIPAAm) star polymer with a β-CD core and an adamantyl-terminated poly(ethylene glycol) (Ad-PEG) polymer were synthesized. They self-assembled into a thermoresponsive pseudo-block copolymer through host-guest complexation and formed supramolecular micelles with the change in environment temperature. Subsequently, an injectable polypseudorotaxane-based supramolecular hydrogel was formed between α-CD and the PEG chains of the pseudo-block copolymer. The hydrogel had a unique network structure involving two types of supramolecular self-assemblies between cyclodextrins and polymers, that is, the host-guest complexation between β-CD units and adamantyl groups and the polypseudorotaxane formation between α-CD and PEG chains. We hypothesize that the dual supramolecular hydrogel formed at room temperature may be enhanced by increasing the temperature over the lower critical solution temperature of PNIPAAm because of the hydrophobic interactions of PNIPAAm segments. Furthermore, if the hydrogel is applied for sustained delivery of hydrophobic drugs, the copolymer dissolved from the hydrogel could micellize and continue to serve as micellar drug carriers with the drug encapsulated in the hydrophobic core. Rheological tests revealed that the hydrophobic interactions of the PNIPAAm segments could significantly enhance the strength of the hydrogel when the temperature increased from 25 to 37 °C. As compared to hydrogels formed by α-CD and PEG alone, the sustained release property of this thermoresponsive hydrogel for an anticancer drug, doxorubicin (DOX), improved at 37 °C. The hydrogel dissolved slowly and released the pseudo-block copolymer in the form of micelles that continued to serve as drug carriers with DOX encapsulated in the hydrophobic core, achieving a better cellular uptake and anticancer effect than free DOX controls, even in multidrug-resistant cancer cells. According to these findings, the dual supramolecular hydrogel developed in this work with remarkable thermoresponsive properties might have potential for sustained anticancer drug delivery with enhanced therapeutic effect in multidrug-resistant cancer cells.

We report a general fabrication method for water-soluble pillar[ n ]arene nanosponges (NS) by the use of a supra-amphiphilic template. For the first time, a supra-amphiphilic template is used to conveniently control the size of host molecule-based NS. The intrinsic cavity of water-soluble pillar[6]arene could stably encapsulate dyes (acridine orange and indocyanine green) and antitumor drugs (doxorubicin hydrochloride and mitoxantrone) by host-guest interaction. NS could deliver antitumor drugs to cancer cells. Multidrug resistance (MDR) of cancer cells (MCF-7/ADR) is overcome by the use of NS with a ninefold reduction in the IC 50 value compared to that of the free drug (3.4 μM vs 34.4 μM). Mechanistic studies show that stable encapsulation of the antitumor drug is the reason to overcome MDR.

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.

Nitric oxide (NO) molecular messenger can reverse the multidrug resistance (MDR) effect of cancer cells through reducing P-glycoprotein (P-gp) expression, beneficial for creating a favorable microenvironment for the treatment of doxorubicin (Dox)-resistant cancer cells. Development of sophisticated nanosystems to programmably release NO and Dox becomes an efficient strategy to overcome the MDR obstacles and achieve promising therapeutic effects in Dox-resistant cancer. Herein, a NO stimulated nanosystem was designed to engineer a significant time gap between NO and Dox release, promoting MDR cancer therapy. A o -phenylenediamine-containing lipid that can hydrolyze in response to NO was embedded in the phospholipid bilayer structure of liposome to form NO-responsive liposome, which could further encapsulate l-arginine (l-Arg)/Dox-loaded gold@copper sulfide yolk-shell nanoparticls ( AD Au@CuS YSNPs) to form ADL Au@CuS YSNPs. Under 808 nm laser irradiation, the unique resonant energy transfer (RET) process and reactive oxygen species (ROS) generation in the confined space of ADL Au@CuS YSNPs could effectively convert l-Arg into NO, regionally destabilizing the phospholipid bilayer structure, as a result of NO release. However, at this early stage Dox could not be released from YSNPs due to the molecular scaffold limit. As the NO release progressed, the NO-responsive liposome layer was deteriorated more severely, allowing Dox to escape. This NO and Dox sequential release of ADL Au@CuS YSNPs could significantly inhibit P-gp expression and enhance Dox accumulation in Dox-resistant MCF-7/ADR cells, leading to promising in vitro and in vivo therapeutic effects and presenting their great potential for MDR cancer therapy.

Intracellular doxorubicin (DOX) pumping out of cells through the P-glycoprotein (P-gp) transporter leads to the reduction of intracellular DOX levels and induces multidrug resistance (MDR). A hyaluronic acid-deoxycholic acid-histidine and Pluronic F127 (PF127) mixed micellar system, named HA-DOCA-His-PF micelles, functionalized with active targeted endocytosis mediated via CD44 receptor, intracellular triggered DOX release under endosome-pH, and combined with PF127-mediated P-gp efflux inhibition was developed for sufficient intracellular DOX delivery and MDR reversion. The DOX/HA-DOCA-His-PF drug-loaded micelles displayed endosomal pH-mediated self-assembly/disassembly characteristics, triggered DOX release under an endosomal (pH 5.5) environment, and demonstrated enhanced cytotoxicity and superior MDR reversion performance against drug-resistant MCF-7/Adr tumor cells. Importantly, superior antitumor activity of DOX/HA-DOCA-His-PF micelles was presented on the growth inhibition of MCF-7/Adr tumor cells, by further inhibiting the P-gp activity on intracellular DOX efflux through the depletion of intracellular adenosine triphosphate content. This multifunctional micellar system could be facilitated by the intracellular DOX delivery for reversing MDR of breast cancer.

Multidrug resistance (MDR) is a significant challenge in the treatment of many types of cancers as membrane-associated transporters actively pump drugs out of the cell, limiting therapeutic efficacy. While nanoparticle (NP)-based therapeutics have emerged as a mechanism for overcoming MDR, they often rely on the delivery of multiple anticancer drugs, nucleic acid hybrids, or MDR pump inhibitors. The effectiveness of these strategies, however, can be limited by their off-target toxicity or the need for genetic transfection. In this paper, we describe a NP-peptide-drug bioconjugate that achieves significant cell killing in MDR-positive cancer cells without the need for additional drugs. We use a quantum dot (QD) as a central scaffold to append two species of peptide, a cell-uptake peptide to facilitate endocytic internalization and a peptide-drug conjugate that is susceptible to cleavage by esterases found within the endocytic pathway. This approach relies on spatiotemporal control over drug release, where endosomes traffic drug away from membrane-resident pumps and release it closer to the nucleus. Cellular internalization studies showed high uptake of the NP-drug complex and nuclear localization of the drug after 48 h in MDR-positive cells. Additionally, cellular proliferation assays demonstrated a 40% decrease in cell viability for the NP-drug bioconjugate compared to free drug, confirming the utility of this system in overcoming MDR in cancer cells.

Robust and accurate analysis of cell-population heterogeneity is challenging but required in many areas of biology and medicine. In particular, it is pivotal to the development of reliable cancer biomarkers. Here, we prove that cytometry of reaction rate constant (CRRC) can facilitate such analysis when the kinetic mechanism of a reaction associated with the heterogeneity is known. In CRRC, the cells are loaded with a reaction substrate, and its conversion into a product is followed by time-lapse fluorescence microscopy at the single-cell level. A reaction rate constant is determined for every cell, and a kinetic histogram "number of cells versus the rate constant" is used to determine quantitative parameters of reaction-based cell-population heterogeneity. Such parameters include, for example, the number and sizes of subpopulations. In this work, we applied CRRC to a reaction of substrate extrusion from cells by ATP-binding cassette (ABC) transporters. This reaction is viewed as a potential basis for predictive biomarkers of chemoresistance in cancer. CRRC proved to be robust (insensitive to variations in experimental settings) and accurate for finding quantitative parameters of cell-population heterogeneity. In contrast, a typical nonkinetic analysis, performed on the same data sets, proved to be both nonrobust and inaccurate. Our results suggest that CRRC can potentially facilitate the development of reliable cancer biomarkers on the basis of quantitative parameters of cell-population heterogeneity. A plausible implementation scenario of CRRC-based development, validation, and clinical use of a predictor of ovarian cancer chemoresistance to its frontline therapy is presented.

Cancer therapies are plagued by resistance. Previously, we discovered a novel form of cancer drug resistance where the Glioma-associated protein 1 (GLI1) elevates UGT1A glucuronidation enzymes, thereby glucuronidating cytarabine and ribavirin, leading to resistance in leukemia patients. Here, we demonstrate that GLI1 imparts resistance to ∼40 compounds, including FDA-approved drugs with disparate chemotypes ( e.g., methotrexate and venetoclax). GLI1 indirectly elevates UGT1As via the chaperone calreticulin, which is required for resistance. Further, we demonstrate that resistant cells are more sensitive to ATP inhibitors, suggesting an Achilles' heel, which could be exploited in the future. In all, we identify GLI1-inducible glucuronidation as a broad-spectrum multidrug resistance pathway.