Enhanced therapeutic effects on the multi-drug resistant human leukemia cells in vitro and xenograft in mice using the stealthy liposomal vincristine plus quinacrine

A DFT approach for finding therapeutic potential of graphyne as a nanocarrier in the doxorubicin drug delivery to treat cancer

In the present work, the drug-loading efficacy of graphyne (GYN) for doxorubicin (DOX) drug is investigated for the first time by using density functional theory (DFT). Doxorubicin drug is effective in the cure of numerous types of cancer including bone cancer, gastric, thyroid, bladder, ovarian, breast, and soft tissue cancer. Doxorubicin drug prevents the cell division process by intercalating in the double-helix of DNA and stopping its replication. The optimized, geometrical, energetic, and excited-state characteristics of graphyne (GYN), doxorubicin drug (DOX), and doxorubicin-graphyne complex (DOX@GYN complex) are calculated to see how effective it is as a carrier. The DOX drug interacted with GYN with an adsorption-energy of -1.57 eV (gas-phase). The interaction of GYN with DOX drug is investigated using NCI (non-covalent interaction) analysis. The findings of this analysis showed that the DOX@GYN complex has weak forces of interaction. Charge transfer from doxorubicin drug to GYN during DOX@GYN complex formation is described by charge-decomposition analysis and HOMO-LUMO analysis. The increased dipole-moment (8.41 D) of the DOX@GYN in contrast with therapeutic agent DOX and GYN indicated that the drug will move easily in the biochemical system. Furthermore, the photo-induced electron-transfer process is explored for excited states, and it reveals that upon interaction, fluorescence-quenching will occur in the complex DOX@GYN. In addition, the influence of the positive and negative charge states on the GYN and DOX@GYN is also considered. Overall, the findings indicated that the GYN could be exploited as an effective drug-transporter for the delivery of doxorubicin drug. Investigators will be inspired to look at another 2D nanomaterials for drug transport applications as a result of this theoretical work.

Quinacrine enhances the efficacy of cisplatin by increasing apoptosis and modulating cancer survival proteins in a colorectal cancer cell line

BACKGROUND

Cisplatin and platinum-based compounds have been used successfully to treat various cancers. However, their use is often restricted due to the acquired resistance by cancer cells. Over-expression of p53 and inhibition of NF-kB sensitize several cancer cells towards cisplatin-induced apoptosis. Quinacrine, a cytotoxic drug with predictable safety revealed to concurrently suppress NF-kB and activate p53, which may be an attractive adjuvant in cisplatin chemotherapy. Therefore, the objective of the present study was to establish the role of quinacrine as an adjuvant in lowering the dose of cisplatin during cancer therapy to circumvent its toxic effects.

MATERIALS AND METHODS

The colon cancer (HCT-8) cells were cultured and cell survival assays were performed using standard procedures. Cell cycle arrest and the extent of apoptosis were determined using a muse cell analyzer. Cancer survival proteins were analyzed using western blotting techniques.

RESULTS AND CONCLUSION

We demonstrated that concomitant use of quinacrine with cisplatin increased cell apoptosis, suppressed cell proliferation and inhibited colony formation in a colorectal cancer cell line. Moreover, cell cycle arrest in the G0/G1 and G2/M phases and upregulation of p53 expression were observed. There was also downregulation of NF-kB and Bcl-xL protein expressions, both of which are associated with enhanced cell apoptosis and an increase in the sensitivity of cancer cells to cisplatin, overcoming its chemoresistance. Overall, the results of the present study and available literature clearly indicate that the use of quinacrine as an adjuvant with cisplatin may enhance its anti-cancer activity and reduce chemoresistance.

Quinacrine is active in preclinical models of glioblastoma through suppressing angiogenesis, inducing oxidative stress and activating AMPK

The poor prognosis of glioblastoma requires new innovative treatment strategies. We and others have shown that targeting tumor as well as angiogenesis in glioblastoma are effective therapeutic strategies. In line with these efforts, this work reveals that Quinacrine, an antimalarial drug, is a dual inhibitor of angiogenesis and glioblastoma. Using multiple glioblastoma cell lines, we found that Quinacrine inhibited proliferation and induced apoptosis in these cells, and acted in synergy with Temozolomide. Quinacrine potently inhibited tubular structure formations of glioblastoma microvascular endothelial cell (GMVEC) isolated from glioblastoma patients, especially for early stage tubular structure formation. Although Quinacrine induces apoptosis in GMVEC, the anti-angiogenic activity of Quinacrine is independent of its pro-apoptotic activity in GMVECs. Quinacrine inhibits glioblastoma angiogenesis and growth in vivo, and acts synergistically with Temozolomide in inhibiting glioblastoma growth in mice. Mechanistically, we found that Quinacrine acts on glioblastoma through inducing oxidative stress, impairing mitochondrial function and activating AMP-activated protein kinase (AMPK). Our work is the first to demonstrate the anti-angiogenic activity of Quinacrine. Our findings highlight Quinacrine as an attractive candidate to support treatment of glioblastoma.

Anti-Cancer Stem Cells Potentiality of an Anti-Malarial Agent Quinacrine: An Old Wine in a New Bottle

Quinacrine (QC) is a tricyclic compound and a derivative of 9-aminoacridine. It has been widely used to treat malaria and other parasitic diseases since the last century. Interestingly, studies have revealed that it also displays anti-cancer activities. Here, we have discussed the anti-cancer mechanism of QC along with its potentiality to specifically target cancer stem cells. The anti-cancer action of this drug includes DNA intercalation, inhibition of DNA repair mechanism, prevention of cellular growth, cell cycle arrest, inhibition of DNA and RNA polymerase activity, induction of autophagy, promotion of apoptosis, deregulation of cell signaling in cancer cells and cancer stem cells, inhibition of metastasis and angiogenesis. In addition, we have also emphasized on the synergistic effect of this drug with other potent chemotherapeutic agents and mentioned its different applications in anti-cancer therapy.

Repurposing quinacrine for treatment-refractory cancer

Quinacrine, also known as mepacrine, has originally been used as an antimalarial drug for close to a century, but was recently rediscovered as an anticancer agent. The mechanisms of anticancer effects of quinacrine are not well understood. The anticancer potential of quinacrine was discovered in a screen for small molecule activators of p53, and was specifically shown to inhibit NFκB suppression of p53. However, quinacrine can cause cell death in cells that lack p53 or have p53 mutations, which is a common occurrence in many malignant tumors including high grade serous ovarian cancer. Recent reports suggest quinacrine may inhibit cancer cell growth through multiple mechanisms including regulating autophagy, FACT (facilitates chromatin transcription) chromatin trapping, and the DNA repair process. Additional reports also suggest quinacrine is effective against chemoresistant gynecologic cancer. In this review, we discuss anticancer effects of quinacrine and potential mechanisms of action with a specific focus on gynecologic and breast cancer where treatment-refractory tumors are associated with increased mortality rates. Repurposing quinacrine as an anticancer agent appears to be a promising strategy based on its ability to target multiple pathways, its selectivity against cancer cells, and the synergistic cytotoxicity when combined with other anticancer agents with limited side effects and good tolerability profile.

Quinacrine Depletes BCR-ABL and Suppresses Ph-Positive Leukemia Cells

Drug resistance to TKIs and the existance of CML leukemia stem cells is an urgent problem. In this study, we demonstrate that quinacrine (QC) induces apoptosis in BCR-ABL positive CML and acute lymphoblastic leukemia (ALL) cells. Interestingly, QC inhibits the colony formation of primary CD34⁺ progenitor/stem leukemia cells from CML patients. QC targets RNA polymerase I, which produces ribosomal (r)RNA, involving in protein translation process. Also, QC treatment prolongs CML-like mice survival and inhibits K562 tumor growth in vivo. In conclusion, we demonstrate that QC depletes BCR-ABL protein and suppresses Ph-positive leukemia cells in vitro and in vivo.

Threatening cancer with nanoparticle aided combination oncotherapy

Employing combination therapy has become obligatory in cancer cases exhibiting high tumor load, chemoresistant tumor population, and advanced disease stages. Realization of this fact has now led many of the combination oncotherapies to become an integral part of anticancer regimens. Combination oncotherapy may encompass a combination of anticancer agents belonging to a similar therapeutic category or that of different therapeutic categories (e.g. chemotherapy + gene therapy). Differences in the physicochemical properties, pharmacokinetics and biodistribution pattern of different payloads are the major constraints that are faced by combination chemotherapy. Concordant efforts in the field of nanotechnology and oncology have emerged with several approaches to solve the major issues encountered by combination therapy. Unique colloidal behaviors of various types of nanoparticles and differential targeting strategies have accorded an unprecedented ability to optimize combination oncotherapeutic delivery. Nanocarrier based delivery of the various types of payloads such as chemotherapeutic agents and other anticancer therapeutics such as small interfering ribonucleic acid (siRNA), chemosensitizers, radiosensitizers, and antiangiogenic agents have been addressed in the present review. Various nano-delivery systems like liposomes, polymeric nanoparticles, polymerosomes, dendrimers, micelles, lipid based nanoparticles, prodrug based nanocarriers, polymer-drug conjugates, polymer-lipid hybrid nanoparticles, carbon nanotubes, nanosponges, supramolecular nanocarriers and inorganic nanoparticles (gold nanoparticles, silver nanoparticles, magnetic nanoparticles and mesoporous silica based nanoparticles) that have been extensively explored for the formulation of multidrug delivery is an imperative part of discussion in the review. The present review features the outweighing benefits of combination therapy over mono-oncotherapy and discusses several existent nanoformulation strategies that facilitate a successful combination oncotherapy. Several obstacles that may impede in transforming nanotechnology-based combination oncotherapy from bench to bedside, and challenges associated therein have also been discussed in the present review.

Developments in drug delivery of bioactive alkaloids derived from traditional Chinese medicine

The bioactive alkaloids (e.g. vincristine, hydroxycamptothecin, ligustrazine, and so on) from traditional Chinese medicine (TCM) have exerted potent efficacies (e.g. anti-tumor, anti-inflammation, immunosuppression, etc.). However, a series of undesirable physicochemical properties (like low solubility and weak stability) and baneful pharmacokinetic (PK) profiles (e.g. low bioavailability, short half time, rapid clearance, etc.) have severely restricted their applications in clinic. In addition, some side effects (like cumulative toxicities caused by high-frequency administration and their own toxicities) have recently been reported and also confined their clinical uses. Therefore, developments in drug delivery of such alkaloids are of significance in improving their drug-like properties and, thus, treatment efficiencies in clinic. Strategies, including (i) specific delivery via liposomes; (ii) sustained delivery via nanoparticles, gels, and emulsions; and (iii) transdermal delivery via ethosomes, solid lipid nanoparticles, and penetrating enhancers, have been reported to improve the pharmacokinetic and physicochemical characters of problematic TCM alkaloids, decline their adverse effects, and thus, boost their curative efficacies. In this review, the recent reports in this field were comprehensively summarized with the aim of providing an informative reference for relevant readers.

Novel applications for an established antimalarial drug: tumoricidal activity of quinacrine

Quinacrine (QC), a synthetic antimalarial drug, was consistently used worldwide to combat malaria during the last century. Interestingly, later studies revealed that it also displays various additional properties, specifically antitumor activity. QC's antitumor activity occurs via a variety of pathways, including DNA intercalation, angiogenesis inhibition, signal transduction regulation, cell cycle arrest and autophagy induction. In combination with traditional therapies such as chemotherapy and radiotherapy, QC has also displayed synergistic effects against tumors, which may open promising therapeutic avenues. However, the breadth and complexity of its antitumor mechanisms have not yet been fully elucidated. In this review, we have systematically categorized QC's reported antitumor mechanisms from recent studies, to enable a deeper understanding of its antitumor activity.

Vorinostat and quinacrine have synergistic effects in T-cell acute lymphoblastic leukemia through reactive oxygen species increase and mitophagy inhibition

Despite recent progress in the treatment, the outcome of adult acute T-cell lymphoblastic leukemia (T-ALL) is poor. Development of novel approach to combat this disease is urgently required. Vorinostat, a pan-histone deacetylase (HDAC) inhibitor, exerts promising anticancer activity in a variety of solid and hematologic malignancies. However, the efficacy of vorinostat monotherapy is unsatisfactory. Here, we show that quinacrine (QC), an anti-malaria drug with potent autophagy inhibitory activity, could synergistically enhance vorinostat-induced cell death at a non-toxic concentration. Compared to the single treatment, QC plus vorinostat significantly induced apoptosis, disrupted the mitochondrial transmembrane potential, and decreased Mcl-1 and Bcl-2/Bax ratio. Interestingly, the application of QC plus vorinostat resulted in mitophagy blockade, as reflected by the increase in the K63-linked ubiquitination of mitochondria protein and the formation of mitochondrial aggresomes. QC plus vorinostat markedly increased the reactive oxygen species (ROS) level in cells. Moreover, the ROS scavenger N-acetylcysteine (NAC) abrogated QC plus vorinostat-induced ROS, decreased the ubiquitination of mitochondria proteins, and cell death. Finally, using a xenograft mouse model, we demonstrated that QC plus vorinostat significantly reduced cell proliferation and induced cell death in vivo. Taken together, our results showed that the combination of QC with vorinostat may represent a novel regimen for the treatment of T-cell acute lymphoblastic leukemia, which deserves clinical evaluation in the future.

Metallic gold and bioactive quinacrine hybrid nanoparticles inhibit oral cancer stem cell and angiogenesis by deregulating inflammatory cytokines in p53 dependent manner

Complete eradication of aggressive oral cancer remains a challenge due to the presence of CSCs. They resist conventional chemotherapeutic agents due to their self-renewal, drug efflux, and efficient DNA repair capacity. Here, we formulated a hybrid-nanoparticle (QAuNP) using quinacrine and gold and characterized/investigated its anti-angiogenic and anti-metastatic effect on OSCC-CSCs. QAuNP significantly inhibited cellular proliferation, caused apoptosis in vitro, and disrupted angiogenesis in vivo and tumor regression in xenograft mice model. It not only inhibited crucial angiogenic markers Ang-1, Ang-2 and VEGF but also depleted MMP-2 in H-357-PEMT cells in a p53 and p21-dependent manner. QAuNP also increased the ROS and NO generation in OSCC-CSCs and reduced the mitochondrial membrane potential. It altered the level of inflammatory cytokines IL-6, IL-1β, TNF-α and metastasis-associated markers (CD-44, CD-133) in H-357-PEMT and CM-treated endothelial cells (HUVEC) in p53/p21-dependent manner. Therefore, QAuNP will be a useful therapeutic agent against metastatic OSCC.

Multifunctional targeting vinorelbine plus tetrandrine liposomes for treating brain glioma along with eliminating glioma stem cells

Malignant brain glioma is the most lethal and aggressive type of cancer. Surgery and radiotherapy cannot eliminate all glioma stem cells (GSCs) and blood–brain barrier (BBB) restricts the movement of antitumor drugs from blood to brain, thus leading to the poor prognosis with high recurrence rate. In the present study, the targeting conjugates of cholesterol polyethylene glycol polyethylenimine (CHOL-PEG₂₀₀₀-PEI) and D-a-tocopheryl polyethylene glycol 1000 succinate vapreotide (TPGS₁₀₀₀-VAP) were newly synthesized for transporting drugs across the BBB and targeting glioma cells and GSCs. The multifunctional targeting vinorelbine plus tetrandrine liposomes were constructed by modifying the targeting conjugates. The studies were undertaken on BBB model, glioma cells, GSCs, and glioma-bearing mice. In vitro results showed that multifunctional targeting drugs-loaded liposomes with suitable physicochemical property could enhance the transport drugs across the BBB, increase the intracellular uptake, inhibit glioma cells and GSCs, penetrate and destruct the GSCs spheroids, and induce apoptosis via activating related apoptotic proteins. In vivo results demonstrated that multifunctional targeting drugs-loaded liposomes could significantly accumulate into brain tumor location, show the specificity to tumor sites, and result in a robust overall antitumor efficacy in glioma-bearing mice. These data suggested that the multifunctional targeting vinorelbine plus tetrandrine liposomes could offer a promising strategy for treating brain glioma.

Quinacrine induces the apoptosis of human leukemia U937 cells through FOXP3/miR-183/β-TrCP/SP1 axis-mediated BAX upregulation

Quinacrine, which is clinically used as an antimalarial drug, has anti-cancer activity. However, mechanism underlying its cytotoxic effect remains to be completely elucidated. In the present study, we investigated the cytotoxic effect of quinacrine on human leukemia U937 cells. Quinacrine-induced apoptosis of U937 cells was accompanied with ROS generation, mitochondrial depolarization, and BAX upregulation. Quinacrine-treated U937 cells showed ROS-mediated p38 MAPK activation and ERK inactivation, which in turn upregulated FOXP3 transcription. FOXP3-mediated miR-183 expression decreased β-TrCP mRNA stability and suppressed β-TrCP-mediated SP1 degradation, thus increasing SP1 expression in U937 cells. Upregulated SP1 expression further increased BAX expression. BAX knock-down attenuated quinacrine-induced mitochondrial depolarization and increased the viability of quinacrine-treated cells. Together, our data indicate that quinacrine-induced apoptosis of U937 cells is mediated by mitochondrial alterations triggered by FOXP3/miR-183/β-TrCP/SP1 axis-mediated BAX upregulation.

The sensitivity of glioma cells to pyropheophorbide-αmethyl ester-mediated photodynamic therapy is enhanced by inhibiting ABCG2

BACKGROUND AND OBJECTIVE

To study the mechanisms of human glioblastoma cell resistance to methyl ester pyropheophorbide-a-mediated photodynamic therapy (MPPa-PDT) and the relationship between the cells and adenosine triphosphate-binding cassette superfamily G member 2 (ABCG2).

STUDY DESIGN/MATERIALS AND METHODS

The sensitivity of four human glioma cell lines (U87, A172, SHG-44, and U251) to MPPa-PDT was detected with a CCK-8 assay. Cell apoptosis, intracellular MPPa, and singlet oxygen were tested with flow cytometry. The mRNA and protein expression of ATP-binding cassette transporters (ABCG2, MRP1, and MDR1) were detected by PCR and Western blot, respectively.

RESULTS

Both the sensitivity to MPPa-PDT and intracellular MPPa in A172 were the lowest among the four cell lines, while expression of ABCG2 mRNA and protein in A172 were the highest. The intracellular MPPa and ROS in A172 receiving MPPa-PDT significantly increased after using the ABCG2 inhibitor fumitremorgin C (FTC). Both cell viability and apoptosis in A172 cells undergoing MPPa-PDT were significantly improved with FTC.

CONCLUSIONS

ABCG2 plays a significant role in the resistance of A172 to MPPa-PDT. Lasers Surg. Med. 49:719-726, 2017. © 2017 Wiley Periodicals, Inc.

Quinacrine promotes autophagic cell death and chemosensitivity in ovarian cancer and attenuates tumor growth

A promising new strategy for cancer therapy is to target the autophagic pathway. In the current study, we demonstrate that the antimalarial drug Quinacrine (QC) reduces cell viability and promotes chemotherapy-induced cell death in an autophagy-dependent manner more extensively in chemoresistant cells compared to their isogenic chemosensitive control cells as quantified by the Chou-Talalay methodology. Our preliminary data, in vitro and in vivo, indicate that QC induces autophagy by downregulating p62/SQSTM1 to sensitize chemoresistant cells to autophagic- and caspase-mediated cell death in a p53-independent manner. QC promotes autophagosome accumulation and enhances autophagic flux by clearance of p62 in chemoresistant ovarain cancer (OvCa) cell lines to a greater extent compared to their chemosensitive controls. Notably, p62 levels were elevated in chemoresistant OvCa cell lines and knockdown of p62 in these cells resulted in a greater response to QC treatment. Bafilomycin A, an autophagy inhibitor, restored p62 levels and reversed QC-mediated cell death and thus chemosensitization. Importantly, our in vivo data shows that QC alone and in combination with carboplatin suppresses tumor growth and ascites in the highly chemoresistant HeyA8MDR OvCa model compared to carboplatin treatment alone. Collectively, our preclinical data suggest that QC in combination with carboplatin can be an effective treatment for patients with chemoresistant OvCa.

Engineered Nanoparticles Against MDR in Cancer: The State of the Art and its Prospective

Cancer is a highly heterogeneous disease at intra/inter patient levels and known as the leading cause of death worldwide. A variety of mono and combinational therapies including chemotherapy have been evolved over the years for its effective treatment. However, advent of chemotherapeutic resistance or multidrug resistance (MDR) in cancer is a major challenge researchers are facing in cancer chemotherapy. MDR is a complex process having multifaceted non-cellular or cellular-based mechanisms. Research in the area of cancer nanotechnology over the past two decade has now proven that the smartly designed nanoparticles help in successful chemotherapy by overcoming the MDR and preferentially accumulate in the tumor region by means of active and passive targeting therefore reducing the offtarget accumulation of payload. Many of such nanoparticles are in different stages of clinical trials as nanomedicines showing promising result in cancer therapy including the resistant cases. Nanoparticles as chemotherapeutics carriers offer the opportunity to have multiple payload of drug and or imaging agents for combinational and theranostics therapy. Moreover, nanotechnology further bring in notice the new treatment strategies such as combining the NIR, MRI and HIFU in cancer chemotherapy and imaging. Here, we discussed the cellular/non-cellular factors constituting the MDR in cancer and the role of nanomedicines in effective chemotherapy of MDR cases of cancers. Moreover, recent advancements like combinational payload delivery and combined physical approach with nanotechnology in cancer therapy have also been discussed.

Multifunctional targeting daunorubicin plus quinacrine liposomes, modified by wheat germ agglutinin and tamoxifen, for treating brain glioma and glioma stem cells

Most anticancer drugs are not able to cross the blood-brain barrier (BBB) effectively while surgery and radiation therapy cannot eradicate brain glioma cells and glioma stem cells (GSCs), hence resulting in poor prognosis with high recurrence rates. In the present study, a kind of multifunctional targeting daunorubicin plus quinacrine liposomes was developed for treating brain glioma and GSCs. Evaluations were performed on in-vitro BBB model, murine glioma cells, GSCs, and GSCs bearing mice. Results showed that the multifunctional targeting daunorubicin plus quinacrine liposomes exhibited evident capabilities in crossing the BBB, in killing glioma cells and GSCs and in diminishing brain glioma in mice. Action mechanism studies indicated that the enhanced efficacy of the multifunctional targeting drugs-loaded liposomes could be due to the following aspects: evading the rapid elimination from blood circulation; crossing the BBB effectively; improving drug uptake by glioma cells and GSCs; down-regulating the overexpressed ABC transporters; inducing apoptosis of GSCs via up-regulating apoptotic receptor/ligand (Fas/Fasl), activating apoptotic enzymes (caspases 8, 9 and 3), activating pro-apoptotic proteins (Bax and Bok), activating tumor suppressor protein (P53) and suppressing anti-apoptotic proteins (Bcl-2 and Mcl-1). In conclusion, the multifunctional targeting daunorubicin plus quinacrine liposomes could be used as a potential therapy for treating brain glioma and GSCs.

Nonspecifically enhanced therapeutic effects of vincristine on multidrug-resistant cancers when coencapsulated with quinine in liposomes

The use of vincristine (VCR) to treat cancer has been limited by its dose-dependent toxicity and development of drug resistance after repeated administrations. In this study, we investigated the mechanism by which quinine hydrochloride (QN) acts as a sensitizer for VCR. Our experiments used three kinds of multidrug-resistant cancer cells and demonstrated that QN worked by inducing intracellular depletion of adenosine triphosphate, increasing adenosine triphosphatase activity, and decreasing P-glycoprotein expression. Based on these results, we designed and prepared a VCR and QN codelivery liposome (VQL) and investigated the effect of coencapsulated QN on the in vitro cytotoxicity of VCR in cells and three-dimensional multicellular tumor spheroids. The antitumor effects of the formulation were also evaluated in multidrug-resistant tumor-bearing mice. The results of this in vivo study indicated that VQL could reverse VCR resistance. In addition, it reduced tumor volume 5.4-fold when compared with other test groups. The data suggest that VQL could be a promising nanoscaled therapeutic agent to overcome multidrug resistance, and may have important clinical implications for the treatment of cancer.

Advances in combination therapies based on nanoparticles for efficacious cancer treatment: an analytical report

The main objective of nanomedicine research is the development of nanoparticles as drug delivery systems or drugs per se to tackle diseases as cancer, which are a leading cause of death with developed nations. Targeted treatments against solid tumors generally lead to dramatic regressions, but, unfortunately, the responses are often short-lived due to resistant cancer cells. In addition, one of the major challenges of combination drug therapy (called "cocktail") is the crucial optimization of different drug parameters. This issue can be solved using combination nanotherapy. Nanoparticles developed in oncology based on combination nanotherapy are either (a) those designed to combat multidrug resistance or (b) those used to circumvent resistance to clinical cancer drugs. This review provides an overview of the different nanoparticles currently used in clinical treatments in oncology. We analyze in detail the development of combinatorial nanoparticles including dendrimers for dual drug delivery via two strategic approaches: (a) use of chemotherapeutics and chemosensitizers to combat multidrug resistance and (b) use of multiple cytotoxic drugs. Finally, in this review, we discuss the challenges, clinical outlook, and perspectives of the nanoparticle-based combination therapy in cancer.

Multidrug resistance in cancer or inefficacy of neuroactive agents: innovative strategies to inhibit or circumvent the active efflux transporters selectively

Multidrug resistance (MDR) is a crucial issue in the treatment of cancer cells that protect themselves by overexpression of active efflux transporters (AETs). AET expression maintains the homeostasis in healthy tissues and in the blood-brain barrier it often prevents drugs from reaching the brain. Inhibition of AETs could therefore be a valuable solution for preventing MDR; but nonselective long-term AET blocking can be harmful toward healthy tissues and, in particular, the brain. This review looks at the development of innovative formulations suitable for selectively blocking or avoiding AETs as promising ways to overcome the challenges of MDR and inefficacy of neuroactive agents.

Use of Nanotechnology to Develop Multi-Drug Inhibitors For Cancer Therapy

Therapeutic agents that inhibit a single target often cannot combat a multifactorial disease such as cancer. Thus, multi-target inhibitors (MTIs) are needed to circumvent complications such as the development of resistance. There are two predominant types of MTIs, (a) single drug inhibitor (SDIs) that affect multiple pathways simultaneously, and (b) combinatorial agents or multi-drug inhibitors (MDIs) that inhibit multiple pathways. Single agent multi-target kinase inhibitors are amongst the most prominent class of compounds belonging to the former, whereas the latter includes many different classes of combinatorial agents that have been used to achieve synergistic efficacy against cancer. Safe delivery and accumulation at the tumor site is of paramount importance for MTIs because inhibition of multiple key signaling pathways has the potential to lead to systemic toxicity. For this reason, the development of drug delivery mechanisms using nanotechnology is preferable in order to ensure that the MDIs accumulate in the tumor vasculature, thereby increasing efficacy and minimizing off-target and systemic side effects. This review will discuss how nanotechnology can be used for the development of MTIs for cancer therapy and also it concludes with a discussion of the future of nanoparticle-based MTIs as well as the continuing obstacles being faced during the development of these unique agents.’

Mitochondrial targeting liposomes incorporating daunorubicin and quinacrine for treatment of relapsed breast cancer arising from cancer stem cells

Breast cancer stem cells play a crucial role in the relapse of breast cancers because they are resistant to a standard chemotherapy and the residual cancer stem cells are able to proliferate indefinitely. The objectives of present study were to construct a kind of mitochondrial targeting daunorubicin plus quinacrine liposomes for treating and for preventing the recurrence of breast cancer arising from the cancer stem cells. MCF-7 cancer stem cells were identified as CD44(+)/CD24(-) cells and cultured in free-serum medium. Evaluations were performed on MCF-7 cancer stem cells, MCF-7 cancer stem cell mammospheres, and the relapsed tumor by xenografting MCF-7 cancer stem cells into female NOD/SCID mice. The particle size of mitochondrial targeting daunorubicin plus quinacrine liposomes was approximately 98 nm. The mitochondrial targeting liposomes evidently increased the mitochondrial uptake of drugs, were selectively accumulated into mitochondria, activated the pro-apoptotic Bax protein, dissipated the mitochondrial membrane potential, opened the mitochondrial permeability transition pores, released cytochrome C by translocation, and initiated a cascade of caspase 9 and 3 reactions, thereby inducing apoptosis of MCF-7 cancer stem cells. The mitochondrial targeting liposomes showed the strongest efficacy in treating MCF-7 cancer cells in vitro, in treating MCF-7 cancer stem cells in vitro, and in treating the relapsed tumor in mice. Mitochondrial targeting daunorubicin plus quinacrine liposomes would provide a new strategy for treating and preventing the relapse of breast cancers arising from cancer stem cells.

The antitumor efficacy of functional paclitaxel nanomicelles in treating resistant breast cancers by oral delivery

Paclitaxel has shown potent efficacy against a wide spectrum of cancers in clinical treatment. However, chemotherapy with paclitaxel has been limited due to serious allergic reactions in patients caused by cremophor EL, and multidrug resistance in many types of tumors, and the restricted permeability across the intestinal barrier. Functional paclitaxel nanomicelles were developed to overcome these obstacles. Evaluations were performed on the breast cancer MCF-7 and resistant MCF-7/Adr cells, MCF-7 and MCF-7/Adr tumor spheroids, Caco-2 cell manolayers, everted gut sacs and the xenografted resistant MCF-7/Adr cancers in nude mice. The functional paclitaxel nanomicelles were approximately of 15 nm in diameter, significantly increased the intracellular uptake of paclitaxel, and selectively accumulated into mitochondria and endoplasmic reticulum after treatment, showing strong inhibitory effect on MCF-7 and MCF-7/Adr cells. They were able to penetrate deeply into the central region of the MCF-7 and MCF-7/Adr spheroids, resulting in a significant reduction in the size of the spheroids. TEM observations showed that the intact functional paclitaxel nanomicelles were transported across the Caco-2 cell manolayer or the everted gut sac. A significant antitumor efficacy in the xenografted resistant MCF-7/Adr cancers in mice was evidenced by oral administration, which was comparable to intravenous administration. The functional paclitaxel nanomicelles would provide a strategy for oral administration of paclitaxel, increasing solubility of paclitaxel, and overcoming the multidrug resistant cancers.

Beyond DNA binding - a review of the potential mechanisms mediating quinacrine's therapeutic activities in parasitic infections, inflammation, and cancers

This is an in-depth review of the history of quinacrine as well as its pharmacokinetic properties and established record of safety as an FDA-approved drug. The potential uses of quinacrine as an anti-cancer agent are discussed with particular attention to its actions on nuclear proteins, the arachidonic acid pathway, and multi-drug resistance, as well as its actions on signaling proteins in the cytoplasm. In particular, quinacrine's role on the NF-κB, p53, and AKT pathways are summarized.

Inhibition of RNA recruitment and replication of an RNA virus by acridine derivatives with known anti-prion activities

Background

Small molecule inhibitors of RNA virus replication are potent antiviral drugs and useful to dissect selected steps in the replication process. To identify antiviral compounds against Tomato bushy stunt virus (TBSV), a model positive stranded RNA virus, we tested acridine derivatives, such as chlorpromazine (CPZ) and quinacrine (QC), which are active against prion-based diseases.

Methodology/Principal Findings

Here, we report that CPZ and QC compounds inhibited TBSV RNA accumulation in plants and in protoplasts. In vitro assays revealed that the inhibitory effects of these compounds were manifested at different steps of TBSV replication. QC was shown to have an effect on multiple steps, including: (i) inhibition of the selective binding of the p33 replication protein to the viral RNA template, which is required for recruitment of viral RNA for replication; (ii) reduction of minus-strand synthesis by the tombusvirus replicase; and (iii) inhibition of translation of the uncapped TBSV genomic RNA. In contrast, CPZ was shown to inhibit the in vitro assembly of the TBSV replicase, likely due to binding of CPZ to intracellular membranes, which are important for RNA virus replication.

Conclusion/Significance

Since we found that CPZ was also an effective inhibitor of other plant viruses, including Tobacco mosaic virus and Turnip crinkle virus, it seems likely that CPZ has a broad range of antiviral activity. Thus, these inhibitors constitute effective tools to study similarities in replication strategies of various RNA viruses.