Overcoming drug resistance of MCF-7/ADR cells by altering intracellular distribution of doxorubicin via MVP knockdown with a novel siRNA polyamidoamine-hyaluronic acid complex

siRNA incorporated in slow-release injectable hydrogel continuously silences DDIT4 and regulates nucleus pulposus cell pyroptosis through the ROS/TXNIP/NLRP3 axis to alleviate intervertebral disc degeneration

Aims

In this investigation, we administered oxidative stress to nucleus pulposus cells (NPCs), recognized DNA-damage-inducible transcript 4 (DDIT4) as a component in intervertebral disc degeneration (IVDD), and devised a hydrogel capable of conveying small interfering RNA (siRNA) to IVDD.

Methods

An in vitro model for oxidative stress-induced injury in NPCs was developed to elucidate the mechanisms underlying the upregulation of DDIT4 expression, activation of the reactive oxygen species (ROS)-thioredoxin-interacting protein (TXNIP)-NLRP3 signalling pathway, and nucleus pulposus pyroptosis. Furthermore, the mechanism of action of small interfering DDIT4 (siDDIT4) on NPCs in vitro was validated. A triplex hydrogel named siDDIT4@G5-P-HA was created by adsorbing siDDIT4 onto fifth-generation polyamidoamine (PAMAM) dendrimer using van der Waals interactions, and then coating it with hyaluronic acid (HA). In addition, we established a rat puncture IVDD model to decipher the hydrogel's mechanism in IVDD.

Results

A correlation between DDIT4 expression levels and disc degeneration was shown with human nucleus pulposus and needle-punctured rat disc specimens. We confirmed that DDIT4 was responsible for activating the ROS-TXNIP-NLRP3 axis during oxidative stress-induced pyroptosis in rat nucleus pulposus in vitro. Mitochondria were damaged during oxidative stress, and DDIT4 contributed to mitochondrial damage and ROS production. In addition, siDDIT4@G5-P-HA hydrogels showed good delivery activity of siDDIT4 to NPCs. In vitro studies illustrated the potential of the siDDIT4@G5-P-HA hydrogel for alleviating IVDD in rats.

Conclusion

DDIT4 is a key player in mediating pyroptosis and IVDD in NPCs through the ROS-TXNIP-NLRP3 axis. Additionally, siDDIT4@G5-P-HA hydrogel has been found to relieve IVDD in rats. Our research offers an innovative treatment option for IVDD.

Human Vault RNAs: Exploring Their Potential Role in Cellular Metabolism

Non-coding RNAs have been described as crucial regulators of gene expression and guards of cellular homeostasis. Some recent papers focused on vault RNAs, one of the classes of non-coding RNA, and their role in cell proliferation, tumorigenesis, apoptosis, cancer response to therapy, and autophagy, which makes them potential therapy targets in oncology. In the human genome, four vault RNA paralogues can be distinguished. They are associated with vault complexes, considered the largest ribonucleoprotein complexes. The protein part of these complexes consists of a major vault protein (MVP) and two minor vault proteins (vPARP and TEP1). The name of the complex, as well as vault RNA, comes from the hollow barrel-shaped structure that resembles a vault. Their sequence and structure are highly evolutionarily conserved and show many similarities in comparison with different species, but vault RNAs have various roles. Vaults were discovered in 1986, and their functions remained unclear for many years. Although not much is known about their contribution to cell metabolism, it has become clear that vault RNAs are involved in various processes and pathways associated with cancer progression and modulating cell functioning in normal and pathological stages. In this review, we discuss known functions of human vault RNAs in the context of cellular metabolism, emphasizing processes related to cancer and cancer therapy efficacy.

Recent advances in multifunctional dendrimer-based complexes for cancer treatment

The application of nanotechnology in biological and medical fields have resulted in the creation of new devices, supramolecular systems, structures, complexes, and composites. Dendrimers are relatively new nanotechnological polymers with unique features; they are globular in shape, with a topological structure formed by monomeric subunit branches diverging to the sides from the central nucleus. This review analyzes the main features of dendrimers and their applications in biology and medicine regarding cancer treatment. Dendrimers have applications that include drug and gene carriers, antioxidant agents, imaging agents, and adjuvants, but importantly, dendrimers can create complex nanosized constructions that combine features such as drug/gene carriers and imaging agents. Dendrimer-based nanosystems include different metals that enhance oxidative stress, polyethylene glycol to provide biosafety, an imaging agent (a fluorescent, radioactive, magnetic resonance imaging probe), a drug or/and nucleic acid that provides a single or dual action on cells or tissues. One of major benefit of dendrimers is their easy release from the body (in contrast to metal nanoparticles, fullerenes, and carbon nanotubes), allowing the creation of biosafe constructions. Some dendrimers are already clinically approved and are being used as drugs, but many nanocomplexes are currently being studied for clinical practice. In summary, dendrimers are very useful tool in the creation of complex nanoconstructions for personalized nanomedicine. This article is categorized under: Diagnostic Tools > Diagnostic Nanodevices Diagnostic Tools > In Vivo Nanodiagnostics and Imaging Therapeutic Approaches and Drug Discovery > Nanomedicine for Oncologic Disease.

Multifunctional Fe-based coordination polymer nano-bomb modified with β-lapachone and CaO2 for targeted tumor dual chemodynamic therapy with enhanced ferroptosis and H2O2 self-supply

Chemodynamic therapy (CDT) is seriously limited by the inadequacy of exogenous catalytic ions and endogenous H2O2 in tumors. Herein, a multifunction nano-bomb integrated with calcium peroxide (CaO2) and β-lapachone as donors of H2O2 and GSH-sensitive Fe-based coordination polymer as provider of catalytic ions was constructed for dual cascade-amplified tumor CDT. This hyaluronic acid (HA)-modified nano-bomb could be specially endocytosed by breast cancer cells through a targeting pathway, degraded and released cargoes in response to the GSH-rich cytoplasm. Furthermore, the released CaO2 and β-lapachone could significantly self-generated sufficient H2O2, which could dual-cascade amplify CDT and induce severe oxidative to tumors via cooperating with the delivered iron ions from nano-bombs. Moreover, the unloaded iron and calcium ions could further accelerate tumor damage by overloading Ca2+ and ferroptosis, as accompanied by good magnetic resonance imaging (MRI). In vitro and in vivo studies collectively reveal that this nano-bomb not only self-initiates double cascade-amplified CDT via self-generation of H2O2, but also efficiently activates ferroptosis and initiates Ca2+ overloading, consequently significantly tumor growth suppression. This study offers a novel tumor-initiated nano-bomb for dual cascade-amplified CDT and bioimaging with activated ferroptosis and self-supplying H2O2.

Hyaluronic acid-empowered nanotheranostics in breast and lung cancers therapy

Nanomedicine application in cancer therapy is an urgency because of inability of current biological therapies for complete removal of tumor cells. The development of smart and novel nanoplatforms for treatment of cancer can provide new insight in tumor suppression. Hyaluronic acid is a biopolymer that can be employed for synthesis of smart nanostructures capable of selective targeting CD44-overexpressing tumor cells. The breast and lung cancers are among the most malignant and common tumors in both females and males that environmental factors, lifestyle and genomic alterations are among the risk factors for their pathogenesis and development. Since etiology of breast and lung tumors is not certain and multiple factors participate in their development, preventative measures have not been completely successful and studies have focused on developing new treatment strategies for them. The aim of current review is to provide a comprehensive discussion about application of hyaluronic acid-based nanostructures for treatment of breast and lung cancers. The main reason of using hyaluronic acid-based nanoparticles is their ability in targeting breast and lung cancers in a selective way due to upregulation of CD44 receptor on their surface. Moreover, nanocarriers developed from hyaluronic acid or functionalized with hyaluronic acid have high biocompatibility and their safety is appreciated. The drugs and genes used for treatment of breast and lung cancers lack specific accumulation at cancer site and their cytotoxicity is low, but hyaluronic acid-based nanostructures provide their targeted delivery to tumor site and by increasing internalization of drugs and genes in breast and lung tumor cells, they improve their therapeutic index. Furthermore, hyaluronic acid-based nanostructures can be used for phototherapy-mediated breast and lung cancers ablation. The stimuli-responsive and smart kinds of hyaluronic acid-based nanostructures such as pH- and light-responsive can increase selective targeting of breast and lung cancers.

A Glimpse into Dendrimers Integration in Cancer Imaging and Theranostics

Cancer is a result of abnormal cell proliferation. This pathology is a serious health problem since it is a leading cause of death worldwide. Current anti-cancer therapies rely on surgery, radiation, and chemotherapy. However, these treatments still present major associated problems, namely the absence of specificity. Thus, it is urgent to develop novel therapeutic strategies. Nanoparticles, particularly dendrimers, have been paving their way to the front line of cancer treatment, mostly for drug and gene delivery, diagnosis, and disease monitoring. This is mainly derived from their high versatility, which results from their ability to undergo distinct surface functionalization, leading to improved performance. In recent years, the anticancer and antimetastatic capacities of dendrimers have been discovered, opening new frontiers to dendrimer-based chemotherapeutics. In the present review, we summarize the intrinsic anticancer activity of different dendrimers as well as their use as nanocarriers in cancer diagnostics and treatment.

CHD4 promotes acquired chemoresistance and tumor progression by activating the MEK/ERK axis

AIMS

Chemoresistance remains a major challenge in gastric cancer (GC). Chromodomain helicase DNA-binding protein 4 (CHD4) mediated chromatin remodeling plays critical roles in various tumor types, but its role in chemoresistance in GC remains uncharacterized.

METHODS

CHD4 expression was examined by immunohistochemistry and Western blotting. The role of CHD4 on cell proliferation and chemoresistance of GC was examined in vitro and in vivo. Immunoprecipitation and liquid chromatography-mass spectrometry were used to identify CHD4-binding proteins and a proximity ligation assay was used to explore protein-protein interaction.

RESULTS

Chemoresistance is associated with upregulation of CHD4 in the tumor tissues of GC patients. Overexpression of CHD4 increased chemoresistance and cell proliferation. Knockdown of CHD4 induced cell apoptosis and cell cycle arrest. CHD4 mediates the decrease of the intracellular concentration of cisplatin by inducing drug efflux. Additionally, CHD4 promotes the interaction between ERK1/2 and MEK1/2, resulting in continuous activation of MEK/ERK pathway. Knockdown of CHD4 in GC increased sensitivity to chemotherapy and suppressed tumor growth in a mouse xenograft model.

CONCLUSIONS

This study identifies CHD4 dominated multi-drug efflux as a promising therapeutic target for overcoming acquired chemoresistance in GC.

Nanoparticles design considerations to co-deliver nucleic acids and anti-cancer drugs for chemoresistance reversal

Chemoresistance and hence the consequent treatment failure is considerably challenging in clinical cancer therapeutics. The understanding of the genetic variations in chemoresistance acquisition encouraged the use of gene modulatory approaches to restore anti-cancer drug efficacy. Many smart nanoparticles are designed and optimized to mediate combinational therapy between nucleic acid and anti-cancer drugs. This review aims to define a rational design of such co-loaded nanocarriers with the aim of chemoresistance reversal at various cellular levels to improve the therapeutic outcome of anticancer treatment. Going through the principles of therapeutics loading, physicochemical characteristics tuning, and different nanocarrier modifications, also looking at combination effectiveness on chemosensitivity restoration. Up to now, these emerging nanocarriers are in development status but are expected to introduce outstanding outcomes.

Polymeric Dendrimers as Nanocarrier Vectors for Neurotheranostics

Dendrimers are polymers with well-defined 3D branched structures that are vastly utilized in various neurotheranostics and biomedical applications, particularly as nanocarrier vectors. Imaging agents can be loaded into dendrimers to improve the accuracy of diagnostic imaging processes. Likewise, combining pharmaceutical agents and anticancer drugs with dendrimers can enhance their solubility, biocompatibility, and efficiency. Practically, by modifying ligands on the surface of dendrimers, effective therapeutic and diagnostic platforms can be constructed and implemented for targeted delivery. Dendrimer-based nanocarriers also show great potential in gene delivery. Since enzymes can degrade genetic materials during their blood circulation, dendrimers exhibit promising packaging and delivery alternatives, particularly for central nervous system (CNS) treatments. The DNA and RNA encapsulated in dendrimers represented by polyamidoamine that are used for targeted brain delivery, via chemical-structural adjustments and appropriate generation, significantly improve the correlation between transfection efficiency and cytotoxicity. This article reports a comprehensive review of dendrimers' structures, synthesis processes, and biological applications. Recent progress in diagnostic imaging processes and therapeutic applications for cancers and other CNS diseases are presented. Potential challenges and future directions in the development of dendrimers, which provide the theoretical basis for their broader applications in healthcare, are also discussed.

Multifunctional graphene oxide nanoparticles for drug delivery in cancer

Recent advancements in nanotechnology have enabled us to develop sophisticated multifunctional nanoparticles or nanosystems for targeted diagnosis and treatment of several illnesses, including cancers. To effectively treat any solid tumor, the therapy should preferably target just the malignant cells/tissue with minor damage to normal cells/tissues. Graphene oxide (GO) nanoparticles have gained considerable interest owing to their two-dimensional planar structure, chemical/mechanical stability, excellent photosensitivity, superb conductivity, high surface area, and good biocompatibility in cancer therapy. Many compounds have been functionalized on the surface of GO to increase their biological applications and minimize cytotoxicity. The review presents an overview of the physicochemical characteristics, strategies for various modifications, toxicity and biocompatibility of graphene and graphene oxide, current trends in developing GO-based nano constructs as a drug delivery cargo and other biological applications, including chemo-photothermal therapy, chemo-photodynamic therapy, bioimaging, and theragnosis in cancer. Further, the review discusses the challenges and opportunities of GO, GO-based nanomaterials for the said applications. Overall, the review focuses on the therapeutic potential of strategically developed GO nanomedicines and comprehensively discusses their opportunities and challenges in cancer therapy.

Notch signaling in female cancers: a multifaceted node to overcome drug resistance

Drug resistance is one of the main challenges in cancer therapy, including in the treatment of female-specific malignancies, which account for more than 60% of cancer cases among women. Therefore, elucidating the underlying molecular mechanisms is an urgent need in gynecological cancers to foster novel therapeutic approaches. Notably, Notch signaling, including either receptors or ligands, has emerged as a promising candidate given its multifaceted role in almost all of the hallmarks of cancer. Concerning the connection between Notch pathway and drug resistance in the afore-mentioned tumor contexts, several studies focused on the Notch-dependent regulation of the cancer stem cell (CSC) subpopulation or the induction of the epithelial-to-mesenchymal transition (EMT), both features implicated in either intrinsic or acquired resistance. Indeed, the present review provides an up-to-date overview of the published results on Notch signaling and EMT- or CSC-driven drug resistance. Moreover, other drug resistance-related mechanisms are examined such as the involvement of the Notch pathway in drug efflux and tumor microenvironment. Collectively, there is a long way to go before every facet will be fully understood; nevertheless, some small pieces are falling neatly into place. Overall, the main aim of this review is to provide strong evidence in support of Notch signaling inhibition as an effective strategy to evade or reverse resistance in female-specific cancers.

CD44-Targeted Nanocarrier for Cancer Therapy

Cluster of differentiation 44 (CD44) is a cell surface glycoprotein overexpressed in varieties of solid tumors including pancreatic, breast, ovary, brain, and lung cancers. It is a multi-structural glycoprotein of the cell surface which is majorly involved in cell proliferation, cell-to-cell interaction, cellular migration, inflammation, and generation of immune responses. Numerous studies focus on the development of nanocarriers for active targeting of the CD44 receptor to improve efficacy of targeting chemotherapy and achieve precise chemotherapy by defining the release, uptake, and accumulation of therapeutic agents. The CD44 receptor has a selective binding affinity towards hyaluronic and chondroitin sulfate (CS). Taking this into consideration, this review focused on the role of CD44 in cancer and its therapy using several nanocarriers such as polymeric/non-polymeric nanoparticles, dendrimer, micelles, carbon nanotubes, nanogels, nanoemulsions etc., for targeted delivery of several chemotherapeutic molecules and nucleic acid. This review also illuminates the role of hyaluronic acid (HA) in cancer therapy, interaction of HA with CD44, and various approaches to target CD44-overexpressed neoplastic cells.

Synergic Antitumor Effect of Photodynamic Therapy and Chemotherapy Mediated by Nano Drug Delivery Systems

This review provides a summary of recent progress in the development of different nano-platforms for the efficient synergistic effect between photodynamic therapy and chemotherapy. In particular, this review focuses on various methods in which photosensitizers and chemotherapeutic agents are co-delivered to the targeted tumor site. In many cases, the photosensitizers act as drug carriers, but this review, also covers different types of appropriate nanocarriers that aid in the delivery of photosensitizers to the tumor site. These nanocarriers include transition metal, silica and graphene-based materials, liposomes, dendrimers, polymers, metal–organic frameworks, nano emulsions, and biologically derived nanocarriers. Many studies have demonstrated various benefits from using these nanocarriers including enhanced water solubility, stability, longer circulation times, and higher accumulation of therapeutic agents/photosensitizers at tumor sites. This review also describes novel approaches from different research groups that utilize various targeting strategies to increase treatment efficacy through simultaneous photodynamic therapy and chemotherapy.

Receptor-Mediated Targeted Delivery of Surface-ModifiedNanomedicine in Breast Cancer: Recent Update and Challenges

Breast cancer therapeutic intervention continues to be ambiguous owing to the lack of strategies for targeted transport and receptor-mediated uptake of drugs by cancer cells. In addition to this, sporadic tumor microenvironment, prominent restrictions with conventional chemotherapy, and multidrug-resistant mechanisms of breast cancer cells possess a big challenge to even otherwise optimal and efficacious breast cancer treatment strategies. Surface-modified nanomedicines can expedite the cellular uptake and delivery of drug-loaded nanoparticulate constructs through binding with specific receptors overexpressed aberrantly on the tumor cell. The present review elucidates the interesting yet challenging concept of targeted delivery approaches by exploiting different types of nanoparticulate systems with multiple targeting ligands to target overexpressed receptors of breast cancer cells. The therapeutic efficacy of these novel approaches in preclinical models is also comprehensively discussed in this review. It is concluded from critical analysis of related literature that insight into the translational gap between laboratories and clinical settings would provide the possible future directions to plug the loopholes in the process of development of these receptor-targeted nanomedicines for the treatment of breast cancer.

Hyaluronic acid-based nanoplatforms for Doxorubicin: A review of stimuli-responsive carriers, co-delivery and resistance suppression

An important motivation for the use of nanomaterials and nanoarchitectures in cancer therapy emanates from the widespread emergence of drug resistance. Although doxorubicin (DOX) induces cell cycle arrest and DNA damage by suppressing topoisomerase activity, resistance to DOX has severely restricted its anti-cancer potential. Hyaluronic acid (HA) has been extensively utilized for synthesizing nanoparticles as it interacts with CD44 expressed on the surface of cancer cells. Cancer cells can take up HA-modified nanoparticles through receptor-mediated endocytosis. Various types of nanostructures such as carbon nanomaterials, lipid nanoparticles and polymeric nanocarriers have been modified with HA to enhance the delivery of DOX to cancer cells. Hyaluronic acid-based advanced materials provide a platform for the co-delivery of genes and drugs along with DOX to enhance the efficacy of anti-cancer therapy and overcome chemoresistance. In the present review, the potential methods and application of HA-modified nanostructures for DOX delivery in anti-cancer therapy are discussed.

Novel cancer stem cell marker MVP enhances temozolomide-resistance in glioblastoma

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MVP level were up-regulated in temozolomide-resistant glioblastoma cells and glioblastoma stem cells.

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MVP decreased the sensitization to temozolomide of glioblastoma cells and glioblastoma stem cells.

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Knockdown of MVP reduced temozolomide-resistance, sphere formation ability and invasive capacity.

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Negative correlation between MVP expression and prognosis of glioblastoma patients

The resistance of highly aggressive glioblastoma multiforme (GBM) to chemotherapy is a major clinical problem resulting in a poor prognosis. GBM contains a rare population of self-renewing cancer stem cells (CSCs) that proliferate, spurring the growth of new tumors, and evade chemotherapy. In cancer, major vault protein (MVP) is thought to contribute to drug resistance. However, the role of MVP as CSCs marker remains unknown and whether MVP could sensitize GBM cells to Temozolomide (TMZ) also is unclear. We found that sensitivity to TMZ was suppressed by significantly increasing the MVP expression in GBM cells with TMZ resistance. Also, MVP was associated with the expression of other multidrug-resistant proteins in tumorsphere of TMZ-resistant GBM cell, and was highly co-expressed with CSC markers in tumorsphere culture. On the other hands, knockdown of MVP resulted in reduced sphere formation and invasive capacity. Moreover, high expression of MVP was associated with tumor malignancy and survival rate in glioblastoma patients. Our study describes that MVP is a potentially novel maker for glioblastoma stem cells and may be useful as a target for preventing TMZ resistance in GBM patients.

Effects of the surface charge of polyamidoamine dendrimers on cellular exocytosis and the exocytosis mechanism in multidrug-resistant breast cancer cells

Background

Polyamidoamine (PAMAM) dendrimer applications have extended from tumor cells to multidrug-resistant tumor cells. However, their transportation in multidrug-resistant tumor cells remains unclear. Herein, we investigated the exocytosis rule and mechanism of PAMAM dendrimers in multidrug-resistant tumor cells.

Results

Using a multidrug-resistant human breast cancer cell model (MCF-7/ADR), we performed systematic analyses of the cellular exocytosis dynamics, pathways and mechanisms of three PAMAM dendrimers with different surface charges: positively charged PAMAM-NH₂, neutral PAMAM-OH and negatively charged PAMAM-COOH. The experimental data indicated that in MCF-7/ADR cells, the exocytosis rate was the highest for PAMAM-NH₂ and the lowest for PAMAM-OH. Three intracellular transportation processes and P-glycoprotein (P-gp) participated in PAMAM-NH₂ exocytosis in MCF-7/ADR cells. Two intracellular transportation processes, P-gp and multidrug resistance (MDR)-associated protein participated in PAMAM-COOH exocytosis. P-gp and MDR-associated protein participated in PAMAM-OH exocytosis. Intracellular transportation processes, rather than P-gp and MDR-associated protein, played major roles in PAMAM dendrimer exocytosis. PAMAM-NH₂ could enter MCF-7/ADR cells by forming nanoscale membrane holes, but this portion of PAMAM-NH₂ was eliminated by P-gp. Compared with PAMAM-OH and PAMAM-COOH, positively charged PAMAM-NH₂ was preferentially attracted to the mitochondria and cell nuclei. Major vault protein (MVP) promoted exocytosis of PAMAM-NH₂ from the nucleus but had no effect on the exocytosis of PAMAM-OH or PAMAM-COOH.

Conclusions

Positive charges on the surface of PAMAM dendrimer promote its exocytosis in MCF-7/ADR cells. Three intracellular transportation processes, attraction to the mitochondria and cell nucleus, as well as nuclear efflux generated by MVP led to the highest exocytosis observed for PAMAM-NH₂. Our findings provide theoretical guidance to design a surface-charged tumor-targeting drug delivery system with highly efficient transfection in multidrug-resistant tumor cells. Especially, to provide more DNA to the nucleus and enhance DNA transfection efficiency in multidrug-resistant tumor cells using PAMAM-NH₂, siRNA-MVP or an inhibitor should be codelivered to decrease MVP-mediated nuclear efflux.

Graphical abstract

Supplementary Information

The online version contains supplementary material available at 10.1186/s12951-021-00881-w.

Multifunctional nanoplatforms co-delivering combinatorial dual-drug for eliminating cancer multidrug resistance

Clinically, the primary cause of chemotherapy failure belongs to the occurrence of cancer multidrug resistance (MDR), which directly leads to the recurrence and metastasis of cancer along with high mortality. More and more attention has been paid to multifunctional nanoplatform-based dual-therapeutic combination to eliminate resistant cancers. In addition to helping both cargoes improve hydrophobicity and pharmacokinetic properties, increase bioavailability, release on demand and enhance therapeutic efficacy with low toxic effects, these smart co-delivery nanocarriers can even overcome drug resistance. Here, this review will not only present different types of co-delivery nanocarriers, but also summarize targeted and stimuli-responsive combination nanomedicines. Furthermore, we will focus on the recent progress in the co-delivery of dual-drug using such intelligent nanocarriers for surmounting cancer MDR. Whereas it remains to be seriously considered that there are some knotty issues in the fight against MDR of cancers via using co-delivery nanoplatforms, including limited intratumoral retention, the possible changes of combinatorial ratio under complex biological environments, drug release sequence from the nanocarriers, and subsequent free-drug resistance after detachment from the nanocarriers. It is hoped that, with the advantage of continuously developing nanomaterials, two personalized therapeutic agents in combination can be better exploited to achieve the goal of cooperatively combating cancer MDR, thus advancing the time to clinical transformation.

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.

LDH-doped electrospun short fibers enable dual drug loading and multistage release for chemotherapy of drug-resistant cancer cells

LDH-incorporated PLGA short nanofibers can be loaded with dual drugs for multistage release and chemotherapy of drug-resistant cancer cells.

Enhancing Chemotherapy by RNA Interference

Abstract Small interfering RNA (siRNA) has shown tremendous potential for treating human diseases in the past decades. siRNA can selectively silence a pathological pathway through the targeting and degradation of a specific mRNA, significantly reducing the off-target side effects of anticancer drugs. However, the poor pharmacokinetics of RNA significantly restricted the clinical use of RNAi technology. In this review, we examine in-depth the siRNA therapeutics currently in preclinical and clinical trials, multiple challenges faced in siRNA therapy, feasibility of siRNA treatment with anticancer drugs in combined with siRNA in nanoparticles or modified to be parental drugs, sequential therapy of siRNA treatment prior to drug treatment with siRNA and drugs loaded in nanoparticles. We focused on the combinatorial activation of apoptosis by different pathways, namely Bcl-2, survivin, and Pgp protein. Taken together, this review would serve to establish the pathway of effective and efficient combination therapy of siRNA and drugs as a new strategy.

Functionalized Graphene Oxide for Chemotherapeutic Drug Delivery and Cancer Treatment: A Promising Material in Nanomedicine

The usage of nanomaterials for cancer treatment has been a popular research focus over the past decade. Nanomaterials, including polymeric nanomaterials, metal nanoparticles, semiconductor quantum dots, and carbon-based nanomaterials such as graphene oxide (GO), have been used for cancer cell imaging, chemotherapeutic drug targeting, chemotherapy, photothermal therapy, and photodynamic therapy. In this review, we discuss the concept of targeted nanoparticles in cancer therapy and summarize the in vivo biocompatibility of graphene-based nanomaterials. Specifically, we discuss in detail the chemistry and properties of GO and provide a comprehensive review of functionalized GO and GO-metal nanoparticle composites in nanomedicine involving anticancer drug delivery and cancer treatment.

Recent Nanocarrier Approaches for Targeted Drug Delivery in Cancer Therapy

Cancer is one of the most serious health concerns in the 21st century whose prevalence is beyond boundaries and can affect any organ of the human body. The conventional chemotherapeutic treatment strategies lack specificity to tumors and are associated with toxic effects on the immune system and other organ systems. In the past decades, there has been continuous progress in the development of smart nanocarrier systems for target-specific delivery of drugs against a variety of tumors, including intracellular gene-specific targeting. These nanocarriers are able to recognize the tumor cells and deliver the therapeutic agent in fixed proportions, causing no or very less harm to healthy cells. Nanosystems have modified physicochemical properties, improved bioavailability, and long retention in blood, which enhances their potency. A huge number of nanocarrier based formulations have been developed and are in clinical trials. Nanocarrier systems include polymeric micelles, liposomes, dendrimers, carbon nanotubes, gold nanoparticles, etc. Recent advancements in nanocarrier systems include mesoporous silica nanoparticles (MSNs), metal organic frameworks, and quantum dots. In the present review, various nanocarrier based drug delivery systems, along with their applications in the management of cancer, have been described with special emphasis on MSNs.

A review of nanotechnology-based approaches for breast cancer and triple-negative breast cancer

Breast cancer (BC) is one of the most prevalent cancers in women. Triple-negative breast cancer (TNBC) in which the three major receptors i.e. estrogen receptor (ER), progesterone receptor (PR) and human epidermal growth factor receptor 2 (HER2), are absent is known to express the most aggressive phenotype and increased metastasis which results in the development of resistance to chemotherapy. It offers various therapeutic advantages in treating BC and TNBC. Nanotechnology offers various unique characteristics such as small size (nanometric), active and passive targeting, and the ability to attach multiple targeting moieties, controlled release, and site-specific targeting. This review focuses on conventional drug therapies, recent treatment strategies, and unique therapeutic approaches available for BC and TNBC. The role of breast cancer stem cells in the recurrence of BC and TNBC has also been highlighted. Several chemotherapeutic agents delivered using nanocarriers such as polymeric nanoparticles/micelles, metallic/inorganic NPs, and lipid-based NPs (Liposome, solid-lipid nanoparticles (SLNs), and nanostructured lipid carriers (NLCs)), etc. with excellent responses in the treatment of BC/TNBC along with breast cancer stem cells have been discussed in details. Moreover, the application of nanomedicine including CRISPR nanoparticle, exosomes for the treatment of BC/TNBC and other molecular targets available such as poly (ADP-ribose) polymerase (PARP), epidermal growth factor receptor (EGFR), Vascular endothelial growth factor (VEGF), etc. for further exploration have also been discussed.

Exploiting ionisable nature of PEtOx-co-PEI to prepare pH sensitive, doxorubicin-loaded micelles

AIMS

This study was conducted to evaluate block copolymers containing two different poly(ethyleneimine) (PEI) amounts, as new pH-sensitive micellar delivery systems for doxorubicin.

METHODS

Micelles were prepared with block copolymers consisting of poly(2-ethyl-2-oxazoline)-co-poly(ethyleneimine) (PEtOx-co-PEI) and poly(ε-caprolactone) (PCL) as hydrophilic and hydrophobic blocks, respectively. Doxorubicin loading, micelle size, pH-dependent drug release, and in vitro cytotoxicity on MCF-7 cells were investigated.

RESULTS

The average size of drug-loaded micelles was under 100 nm and drug loading was between 10.7% and 48.3% (w/w). pH-sensitive drug release was more pronounced (84.7% and 68.9% (w/w) of drug was released at pH 5.0 and pH 7.4, respectively) for the micelles of the copolymer with the lowest PEI amount. The cell viability of doxorubicin-loaded micelles which were prepared by the copolymer with the lowest PEI amount was 28-33% at 72 h.

CONCLUSIONS

PEtOx-co-PEI-b-PCL micelles of this copolymer were found to be stable and effective pH-sensitive nano-sized carriers for doxorubicin delivery.

Mitochondrial delivery of microRNA mimic let-7b to NSCLC cells by PAMAM-based nanoparticles

Many biological mechanisms including cellular metabolism and cell death are regulated by mitochondria known as powerhouse of the cell. Recently, let-7b, a tumour-suppressor microRNA has been detected in mitochondria of human cells targeting several mitochondrial-encoded respiratory chain genes. Triphenylphosphonium cation (TPP) is one of the major classes of mitochondriotropics that possess the ability of specifically targeting the mitochondria. PAMAM dendrimers are one of the most available agents in gene delivery due to their well-defined and beneficial features such as large density of surface functional groups. Hyaluronic acid (HA), a natural polysaccharide has been demonstrated to have the abilities such as good biocompatibility and targeting CD44 overexpressed receptors on non-small cell lung cancer (NSCLC) cells. In this research, let-7b-PAMAM (G5)-TPP and let-7b-PAMAM (G5)-TPP-HA nano-carriers were designed to deliver let-7b miRNA mimic to NSCLC cells' mitochondria as a novel way of cancer cells inhibition. Nano-carriers were capable of being successfully taken up by A549 cells and localised in mitochondria environment. Let-7b loaded nanoparticles reduced cell viability and induced apoptosis significantly. Expression of genes involved in mitochondrial oxidative function was decreased resulting in nanoparticles effect on mitochondria. Application of mitochondria targeted-miRNA delivery systems could regulate cellular functions to inhibit lung cancer.

Drug uptake-based chemoresistance in breast cancer treatment

Breast cancer is the most prevalent type of tumor and the second leading cause of death due to cancer among women. Although screening methods, diagnosis and therapeutic options have improved in the last decade, chemoresistance remains an important challenge. There is evidence relating breast cancer resistance with signaling pathways involving hormone and growth receptors, survival, apoptosis and the activation of efflux pumps. However, the resistance mechanisms linked to drug uptake are poorly understood, despite it often being observed that the drug content is lower in resistant cancer cells and that the entry of the drug into these cells is a limiting process for the subsequent therapeutic effect.In this review, we provide an overview of drug uptake-based resistance mechanisms developed by cancer cells in the four main types of chemotherapy used in breast cancer: anthracyclines, taxanes, oxazaphosphorines and platinum-based drugs. The contribution of tumor microenvironment to reduced drug-uptake and multidrug resistance is also analyzed. As a developing field, nanomedicine-based approaches provide promising opportunities to improve drug specific targeting, cell interaction and uptake into cancer cells. The endocytic-mediated pathways attributed to the different types of nanoformulations as well as the contribution of nanotherapeutics to overcoming chemoresistance affecting drug uptake in breast cancer will be described. New approaches focusing on drug uptake mechanisms could improve breast cancer chemotherapy, obtaining better dose-response outcomes and reducing toxic side effects.

Ligand-installed anti-VEGF genomic nanocarriers for effective gene therapy of primary and metastatic tumors

The systemic dosage regimen exhibited low therapeutic efficacy and incurred severe adverse effect, thus, the development of tumor-targeted therapeutics is crucial important for tumor precision therapy. Herein, the active targeted modulation of tumor microenvironments was schemed by developing hyaluronic acid-installed genomic nanocarriers (HA-NPs) for effectively ablation of both primary and metastatic tumors through anti-vascular endothelial growth factor (anti-VEGF) approach. The anti-VEGF genomic payloads were strategically packaged into the well-defined synthetic nanocarriers by layer-by-layer preparation strategy, exhibiting high colloidal stability and much lower cell viability than the cationic gene carriers. Besides, the HA-NPs could specifically and efficiently internalize with cancer cells for efficient intracellular gene delivery, leading to high gene transfection efficacy. Moreover, it further demonstrated efficient extravasation, high accumulation and deep penetration in tumors, which markedly facilitated tumor-targeted expression of anti-VEGF genomic payloads for inhabitation of neo-vasculature, consecutively contributing to potent ablation of solid tumors. In addition, the ligand-installed nanocarriers facilitated systemic treatment of melanoma lung metastasis by the expressed anti-VEGF proteins, which were extensively spread along blood circulation and metastatic niches to diminish the formation of neovasculature for tumorigenesis. Therefore, the proposed anti-VEGF genomic nanocarriers could shed intriguing implication in effectively treatment of primary tumors and metastasis.

Inactivation of the Cytoprotective Major Vault Protein by Caspase-1 and -9 in Epithelial Cells during Apoptosis

Inflammasome activation induces caspase-1-dependent secretion of the proinflammatory cytokine IL-1β. In addition, caspase-1 activates the protein GSDMD in immune cells, causing pyroptosis, a lytic type of cell death. In contrast, UVB irradiation of human primary keratinocytes induces NLRP1 inflammasome activation, cytokine secretion, and caspase-1-dependent apoptosis, rather than pyroptosis. Here, we addressed the molecular mechanisms underlying the role of caspase-1 in UVB-induced cell death of human primary keratinocytes. We show that GSDMD is a poor substrate of caspase-1 in human primary keratinocytes and that its activation upon UVB irradiation supports secretion of IL-1β. We screened for novel substrates of caspase-1 by a mass spectrometry-based approach and identified the specific cleavage of the major vault protein (MVP) at D441 by caspase-1 and -9. MVP is the main component of vaults, highly conserved ribonucleoprotein particles, whose functions are poorly understood. Cleavage of MVP is a common event occurring in human primary keratinocytes and fibroblasts undergoing apoptosis induced by different stimuli. In contrast, MVP cleavage could not be detected in pyroptotic cells. Cleavage of MVP by caspase-1 and -9 inactivates this cytoprotective protein. These results demonstrate a proapoptotic activity of caspase-1 and a crosstalk with caspase-9 upon inactivation of the cytoprotective MVP in apoptotic epithelial cells.

Transferrin receptor-targeted redox/pH-sensitive podophyllotoxin prodrug micelles for multidrug-resistant breast cancer therapy

Podophyllotoxin (PPT), a toxic polyphenol extracted from the roots of Podophyllum species, showed remarkable activity against P-glycoprotein (P-gp) mediated multidrug resistant (MDR) cancer cells. Many PPT-prodrugs based on nano-technology have been developed for increasing aqueous solubility and reducing the side effects of PPT; however, the sensitive linkers in almost all PPT-prodrugs were ester bonds, resulting in slow and incomplete drug release. We developed a redox/pH double-sensitive and tumor active targeted drug delivery system for PPT delivery, in which PPT was covalently coupled to T7-peptide (Pep) modified polyethylene glycol (PEG) or methoxy-polyethylene glycol (mPEG) through a disulfide bond to obtain the final polymer (Pep-PEG-SS-PPT or PEG-SS-PPT). The mixed micelles (Pep-SS-NPs) were made by mixing Pep-PEG-SS-PPT with PEG-SS-PPT, and the mixed micelles showed good size uniformity and high stability in serum solution. The in vitro release experiment showed that about (81.7 ± 2.8)% PPT was released from Pep-SS-NPs in 10 mM glutathione (GSH) at pH 7.4, and also about (64.6 ± 1.7)% PPT was released from Pep-SS-NPs at pH 5.0. In vitro cytotoxicity analysis suggested that Pep-SS-NPs exhibited 57- to 270-fold lower resistance index (RI) values for different drug-resistant cancer cell lines than paclitaxel (PTX) or docetaxel (DTX). The cell uptake assay indicated that the Pep-SS-NPs could significantly enhance the intracellular level of coumarin-6 compared to that of the control group. The maximum tolerated dose (MTD) of Pep-SS-NPs was increased greatly compared to that of free PPT (5.3-fold). In vivo research showed that Pep-SS-NPs significantly enhanced antitumor efficacy against MCF-7/ADR xenograft tumors compared to the control groups. These findings suggest that mixed micelles could be a potentially successful nanomedicine for MDR breast cancer therapy.

Cytotoxicity of Dendrimers

Drug delivery systems are molecular platforms in which an active compound is packed into or loaded on a biocompatible nanoparticle. Such a solution improves the activity of the applied drug or decreases its side effects. Dendrimers are promising molecular platforms for drug delivery due to their unique properties. These macromolecules are known for their defined size, shape, and molecular weight, as well as their monodispersity, the presence of the void space, tailorable structure, internalization by cells, selectivity toward cells and intracellular components, protection of guest molecules, and controllable release of the cargo. Dendrimers were tested as carriers of various molecules and, simultaneously, their toxicity was examined using different cell lines. It was discovered that, in general, dendrimer cytotoxicity depended on the generation, the number of surface groups, and the nature of terminal moieties (anionic, neutral, or cationic). Higher cytotoxicity occurred for higher-generation dendrimers and for dendrimers with positive charges on the surface. In order to decrease the cytotoxicity of dendrimers, scientists started to introduce different chemical modifications on the periphery of the nanomolecule. Dendrimers grafted with polyethylene glycol (PEG), acetyl groups, carbohydrates, and other moieties did not affect cell viability, or did so only slightly, while still maintaining other advantageous properties. Dendrimers clearly have great potential for wide utilization as drug and gene carriers. Moreover, some dendrimers have biological properties per se, being anti-fungal, anti-bacterial, or toxic to cancer cells without affecting normal cells. Therefore, intrinsic cytotoxicity is a comprehensive problem and should be considered individually depending on the potential destination of the nanoparticle.

Dendrimer-Enabled Therapeutic Antisense Delivery Systems as Innovation in Medicine

Antisense oligonucleotide (AON)-based therapies concern the treatment for genetic disorders or infections such as a range of neurodegenerative and neuromuscular diseases and have shown benefits in animal models and patients. Nevertheless, successes in the clinic are still strongly limited by unfavorable biodistribution and poor cellular uptake of AONs. Dendrimer macromolecules are synthetically accessible and consist of a core with repeated iterations (named branches) surrounding this core, and on the periphery functional groups which can be modified for ligand attachment. The generations of these branched nanoparticles are based on the number of branches emanating from the core with layered architectures. Dendrimers show promise in several biomedical applications based on their tunable surface modifications allowing the adjustment of their in vivo behavior related to biocompatibility and pharmacokinetic parameters. Dendrimers can be used as nanocarriers of various types of drugs including AONs or nanodrugs. As nanocarriers, polycationic dendrimers can complex multiple negatively charged DNA oligonucleotides on their surface and form stable complexes to promote internalization into the cells based on a good cell membrane affinity. These nanocarriers complexing antisense oligonucleotides must be stable enough to reach the cellular target, but with adequate in vivo global clearance, and have good pharmacokinetic (PK) and pharmacodynamic (PD) profiles. This Review was designed to analyze the development of AONs carried by polycationic and polyanionic (few example) dendrimers. This Review strongly supports the idea that dendrimers, with adequate modulation of their terminal groups, could be used to carry AONs in cells.

Co-Delivery of Metformin Enhances the Antimultidrug Resistant Tumor Effect of Doxorubicin by Improving Hypoxic Tumor Microenvironment

Doxorubicin (DOX) is a first-line chemo drug for cancer therapy, yet it fails to treat multi-drug-resistant tumors. Hypoxia is a major causative factor leading to chemotherapy failure. Particularly, hypoxia up-regulates its responsive transcription factor-hypoxia-inducible factors (HIF)-to induce the overexpression of drug resistant genes. Metformin (MET) is recently found to cooperate with DOX against multiple tumors. As a mitochondrial inhibitor, MET could suppress tumor oxygen consumption, and thereby modulate the hypoxic tumor microenvironment. In this study, we used cationic liposomes to codeliver both DOX and MET for treating multi-drug-resistant breast cancer cells-MCF7/ADR. Faster release of MET enhanced the cytotoxicity of DOX through attenuating hypoxic stress both in vivo and in vitro. MET diminished the cellular oxygen consumption and inhibited HIF1α and P-glycoprotein (Pgp) expression in vitro. In addition, the dual-drug-loaded liposomes increased tumor targeting and intratumoral blood oxygen saturation, which suggested that the tumor reoxygenation effect of MET facilitated the exertion of its synergistic activity with DOX against MCF7/ADR xenografts. In general, our study represents a feasible strategy to boost the therapeutic effect in treating multi-drug-resistant cancer by improving the hypoxic tumor microenvironment.

Chemoresistance mechanisms of breast cancer and their countermeasures

Chemoresistance is one of the major challenges for the breast cancer treatment. Owing to its heterogeneous nature, the chemoresistance mechanisms of breast cancer are complicated, and not been fully elucidated. The existing treatments fall short of offering adequate solution to drug resistance, so more effective approaches are desperately needed to improve existing therapeutic regimens. To overcome this hurdle, a number of strategies are being investigated, such as novel agents or drug carriers and combination treatment. In addition, some new therapeutics including gene therapy and immunotherapy may be promising for dealing with the resistance. In this article, we review the mechanisms of chemoresistance in breast cancer. Furthermore, the potential therapeutic methods to overcome the resistance were discussed.

Major vault protein is a direct target of Notch1 signaling and contributes to chemoresistance in triple-negative breast cancer cells

Resistance to chemotherapy remains a significant problem in the treatment of breast cancer, especially for triple-negative breast cancer (TNBC), in which standard systemic therapy is currently limited to chemotherapeutic agents. Our study aimed to better understand the molecular mechanisms that lead to failure of chemotherapy in TNBC. Herein, we observed elevated expression of Notch1 and major vault protein (MVP) in MDA-MB-231DDPR cells compared to their parental counterparts. We demonstrated that Notch1 could positively regulate the expression of MVP. Also, Notch1 intracellular domain (ICD) was capable of binding to CBF-1 on the promoter of MVP to drive its transcription, resulting in activation of AKT pathway and promoting the progress of epithelial to mesenchymal transition (EMT). Conversely, silencing of Notch1 and MVP suppressed AKT pathway, reduced EMT and enhanced the sensitivity of TNBC cells to cisplatin and doxorubicin. Survival analysis indicated that the MVP was closely related to shorter recurrence-free survival (RFS) in patients with TNBC. Collectively, this study provides evidence that Notch1 activates AKT pathway and promotes EMT partly through direct activation of MVP. Targeting Notch1/MVP pathway appears to have potential in overcoming chemoresistance in TNBC.

Enhanced cellular uptake by non-endocytic pathway for tumor therapy

Endosome/lysosome, as the potential risk of therapeutic inactivation resulting from physical obstruction and a number of acid hydrolases, is a bottleneck in effective intracellular delivery which needs to be overcome. One promising strategy to avoid this barrier is to deliver therapeutic agents directly into the cytoplasm. In this study, CLIP6 peptide (KVRVRVRV^DPPTRVRERVK-NH₂) which can facilitate non-endosomal cell entry and anticancer drug doxorubicin (DOX) were covalently grafted to N-(2-hydroxypropyl)methacrylamide (HPMA) backbone (P-DOX-CLIP6). As a result, CLIP6 peptide modification increased the cellular uptake of DOX-loaded HPMA copolymers. Importantly, it effectively reduced lysosomal accumulation, leading to stronger proliferation inhibition and superior growth inhibition effect on three-dimensional tumor spheroids, compared to unmodified HPMA copolymer conjugates. Furthermore, P-CLIP6-DOX induced the highest therapeutic efficacy in HeLa tumor-bearing nude mice. Meanwhile, no significant systemic toxicity was observed during the treatment. In conclusion, this study provided a promising strategy to efficiently deliver drug candidates which were limited by endo/lysosomal trapping.

Establishment of 2D Cell Cultures Derived From 3D MCF-7 Spheroids Displaying a Doxorubicin Resistant Profile

In vitro 3D cancer spheroids generally exhibit a drug resistance profile similar to that found in solid tumors. Due to this property, these models are an appealing for anticancer compounds screening. Nevertheless, the techniques and methods aimed for drug discovery are mostly standardized for cells cultured in 2D. The development of 2D cell culture models displaying a drug resistant profile is required to mimic the in vivo tumors, while the equipment, techniques, and methodologies established for conventional 2D cell cultures can continue to be employed in compound screening. In this work, the response of 3D-derived MCF-7 cells subsequently cultured in 2D in medium supplemented with glutathione (GSH) (antioxidant agent found in high levels in breast cancer tissues and a promoter of cancer cells resistance) to Doxorubicin (DOX) is evaluated. These cells demonstrated a resistance toward DOX closer to that displayed by 3D spheroids, which is higher than that exhibited by standard 2D cell cultures. In fact, the 50% inhibitory concentration (IC₅₀ ) of DOX in 3D-derived MCF-7 cell cultures supplemented with GSH is about eight-times higher than that obtained for conventional 2D cell cultures (cultured without GSH), and is only about two-times lower than that attained for 3D MCF-7 spheroids (cultured without GSH). Further investigation revealed that this improved resistance of 3D-derived MCF-7 cells may result from their increased P-glycoprotein (P-gp) activity and reduced production of intracellular reactive oxygen species (ROS).

Star-Graft Quarterpolymer-Based Polymersomes as Nanocarriers for Co-Delivery of Hydrophilic/Hydrophobic Chemotherapeutic Agents

We report the fabrication of polymersomes, using as building blocks star-graft quarterpolymers, composed of hydrophobic polystyrene and pH-sensitive poly(2-vinylpyridine)-b-poly(acrylic acid) (P2VP-b-PAA) arms, emanated from a common nodule, enriched by thermosensitive poly(N-isopropylacrylamide) grafts covalently bonded on the PAA block-arms. These multicompartmental polymersomes were evaluated as nanocarriers for the encapsulation and controlled co-delivery of doxorubicin (hydrophilic) and paclitaxel (hydrophobic) chemotherapeutic agents. The polymersomes can load these drugs in different compartments and can efficiently be internalized in the human lung adenocarcinoma epithelial cells, delivering their cargo and inducing high cell apoptosis. The release kinetics of both anticancer agents was controlled differently by the environmental conditions (pH and temperature). Enhanced release was observed at the acidic pH 6.0 and under physiological temperature (37 °C). At the same total drug level, co-delivery of these drugs with the polymersomes caused enhanced cytotoxicity and induced significantly higher cell apoptosis in the cancer cell line compared to the polymersomes loaded with either of the two drugs.

Subcellular drug distribution: mechanisms and roles in drug efficacy, toxicity, resistance, and targeted delivery

After administration, drug molecules usually enter target cells to access their intracellular targets. In eukaryotic cells, these targets are often located in organelles, including the nucleus, endoplasmic reticulum, mitochondria, lysosomes, Golgi apparatus, and peroxisomes. Each organelle type possesses unique biological features. For example, mitochondria possess a negative transmembrane potential, while lysosomes have an intraluminal delta pH. Other properties are common to several organelle types, such as the presence of ATP-binding cassette (ABC) or solute carrier-type (SLC) transporters that sequester or pump out xenobiotic drugs. Studies on subcellular drug distribution are critical to understand the efficacy and toxicity of drugs along with the body's resistance to them and to potentially offer hints for targeted subcellular drug delivery. This review summarizes the results of studies from 1990 to 2017 that examined the subcellular distribution of small molecular drugs. We hope this review will aid in the understanding of drug distribution within cells.