Co-treatment with the anti-malarial drugs mefloquine and primaquine highly sensitizes drug-resistant cancer cells by increasing P-gp inhibition

Proguanil Suppresses Breast Tumor Growth In Vitro and In Vivo by Inducing Apoptosis via Mitochondrial Dysfunction

Breast cancer, ranking as the second leading cause of female cancer-related deaths in the U.S., demands the exploration of innovative treatments. Repurposing FDA-approved drugs emerges as an expedited and cost-effective strategy. Our study centered on proguanil, an antimalarial drug, reveals notable anti-proliferative effects on diverse breast cancer cell lines, including those derived from patients. Proguanil-induced apoptosis was associated with a substantial increase in reactive oxygen species (ROS) production, leading to reduced mitochondrial membrane potential, respiration, and ATP production. Proguanil treatment upregulated apoptotic markers (Bax, p-H2AX, cleaved-caspase 3, 9, cleaved PARP) and downregulated anti-apoptotic proteins (bcl-2, survivin) in breast cancer cell lines. In female Balb/c mice implanted with 4T1 breast tumors, daily oral administration of 20 mg/kg proguanil suppressed tumor enlargement by 55%. Western blot analyses of proguanil-treated tumors supported the in vitro findings, demonstrating increased levels of p-H2AX, Bax, c-PARP, and c-caspase3 as compared to controls. Our results collectively highlight proguanil's anticancer efficacy in vitro and in vivo in breast cancer, prompting further consideration for clinical investigations.

Endocannabinoids are potential inhibitors of glioblastoma multiforme proliferation

Globally, it is evident that glioblastoma multiforme (GBM) is an aggressive malignant cancer with a high mortality rate and no effective treatment options. Glioblastoma is classified as the stage-four progression of a glioma tumor, and its diagnosis results in a shortened life expectancy. Treatment options for GBM include chemotherapy, immunotherapy, surgical intervention, and conventional pharmacotherapy; however, at best, they extend the patient's life by a maximum of 5 years. GBMs are considered incurable due to their high recurrence rate, despite various aggressive therapeutic approaches which can have many serious adverse effects. Ceramides, classified as endocannabinoids, offer a promising novel therapeutic approach for GBM. Endocannabinoids may enhance the apoptosis of GBM cells but have no effect on normal healthy neural cells. Cannabinoids promote atypical protein kinase C, deactivate fatty acid amide hydrolase enzymes, and activate transient receptor potential vanilloid 1 (TRPV1) and TRPV2 to induce pro-apoptotic signaling pathways without increasing endogenous cannabinoids. In previous in vivo studies, endocannabinoids, chemically classified as amide formations of oleic and palmitic acids, have been shown to increase the pro-apoptotic activity of human cancer cells and inhibit cell migration and angiogenesis. This review focuses on the biological synthesis and pharmacology of endogenous cannabinoids for the enhancement of cancer cell apoptosis, which have potential as a novel therapy for GBM. Please cite this article as: Duzan A, Reinken D, McGomery TL, Ferencz N, Plummer JM, Basti MM. Endocannabinoids are potential inhibitors of glioblastoma multiforme proliferation. J Integr Med. 2023; Epub ahead of print.

Developmental toxicity and programming alterations of multiple organs in offspring induced by medication during pregnancy

Medication during pregnancy is widespread, but there are few reports on its fetal safety. Recent studies suggest that medication during pregnancy can affect fetal morphological and functional development through multiple pathways, multiple organs, and multiple targets. Its mechanisms involve direct ways such as oxidative stress, epigenetic modification, and metabolic activation, and it may also be indirectly caused by placental dysfunction. Further studies have found that medication during pregnancy may also indirectly lead to multi-organ developmental programming, functional homeostasis changes, and susceptibility to related diseases in offspring by inducing fetal intrauterine exposure to too high or too low levels of maternal-derived glucocorticoids. The organ developmental toxicity and programming alterations caused by medication during pregnancy may also have gender differences and multi-generational genetic effects mediated by abnormal epigenetic modification. Combined with the latest research results of our laboratory, this paper reviews the latest research progress on the developmental toxicity and functional programming alterations of multiple organs in offspring induced by medication during pregnancy, which can provide a theoretical and experimental basis for rational medication during pregnancy and effective prevention and treatment of drug-related multiple fetal-originated diseases.

Nanoengineering a Zeolitic Imidazolate Framework-8 Capable of Manipulating Energy Metabolism against Cancer Chemo-Phototherapy Resistance

Chemo-phototherapy has emerged as a promising approach to complement traditional cancer treatment and enhance therapeutic effects. However, it still faces the challenges of drug efflux transporter-mediated chemoresistance and heat shock proteins (HSPs)-mediated phototherapy tolerance, which both depend on an excessive supply of adenosine triphosphate. Therefore, manipulating energy metabolism to impair the expression or function of P-glycoprotein (P-gp) and HSPs may be a prospective strategy to reverse cancer therapeutic resistance. Herein, a chondroitin sulfate (CS)-functionalized zeolitic imidazolate framework-8 (ZIF-8) chemo-phototherapy nanoplatform (CS/ZIF-8@A780/DOX NPs) is rationally designed that is capable of manipulating energy metabolism against cancer therapeutic resistance by integrating the photosensitizer IR780 iodide (IR780)-conjugated atovaquone (ATO) (A780) and the chemotherapeutic agent doxorubicin (DOX). Mechanistically, ATO and zinc ions that are released in the acidic tumor microenvironment can lead to systematic energy exhaustion through disturbing mitochondrial electron transport and the glycolysis process, thus suppressing the activity of P-gp and HSP70, respectively. In addition, CS is used on the surface of ZIF-8@A780/DOX NPs to improve the targeting capability to tumor tissues. These data provide an efficient strategy for manipulating energy metabolism for cancer treatment, especially for overcoming cancer chemo-phototherapy resistance.

Mefloquine induces ER stress and apoptosis in BRAFi-resistant A375-BRAFV600E /NRASQ61K malignant melanoma cells targeting intracranial tumors in a bioluminescent murine model

Molecularly targeted therapeutics have revolutionized the treatment of BRAFV600E -driven malignant melanoma, but the rapid development of resistance to BRAF kinase inhibitors (BRAFi) presents a significant obstacle. The use of clinical antimalarials for the investigational treatment of malignant melanoma has shown only moderate promise, attributed mostly to inhibition of lysosomal-autophagic adaptations of cancer cells, but identification of specific antimalarials displaying single-agent antimelanoma activity has remained elusive. Here, we have screened a focused library of clinically used artemisinin-combination therapeutic (ACT) antimalarials for the apoptotic elimination of cultured malignant melanoma cell lines, also examining feasibility of overcoming BRAFi-resistance comparing isogenic melanoma cells that differ only by NRAS mutational status (BRAFi-sensitive A375-BRAFV600E /NRASQ61 vs. BRAFi-resistant A375-BRAFV600E /NRASQ61K ). Among ACT antimalarials tested, mefloquine (MQ) was the only apoptogenic agent causing melanoma cell death at low micromolar concentrations. Comparative gene expression-array analysis (A375-BRAFV600E /NRASQ61 vs. A375-BRAFV600E /NRASQ61K ) revealed that MQ is a dual inducer of endoplasmic reticulum (ER) and redox stress responses that precede MQ-induced loss of viability. ER-trackerTM DPX fluorescence imaging and electron microscopy indicated ER swelling, accompanied by rapid induction of ER stress signaling (phospho-eIF2α, XBP-1s, ATF4). Fluo-4 AM-fluorescence indicated the occurrence of cytosolic calcium overload observable within seconds of MQ exposure. In a bioluminescent murine model employing intracranial injection of A375-Luc2 (BRAFV600E /NRASQ61K ) cells, an oral MQ regimen efficiently antagonized brain tumor growth. Taken together, these data suggest that the clinical antimalarial MQ may be a valid candidate for drug repurposing aiming at chemotherapeutic elimination of malignant melanoma cells, even if metastasized to the brain and BRAFi-resistant.

Primaquine Inhibits the Endosomal Trafficking and Nuclear Localization of EGFR and Induces the Apoptosis of Breast Cancer Cells by Nuclear EGFR/Stat3-Mediated c-Myc Downregulation

Triple-negative breast cancer (TNBC) cells overexpress the epidermal growth factor receptor (EGFR). Nuclear EGFR (nEGFR) drives resistance to anti-EGFR therapy and is correlated with poor survival in breast cancer. Inhibition of EGFR nuclear translocation may be a reasonable approach for the treatment of TNBC. The anti-malarial drugs chloroquine and primaquine have been shown to promote an anticancer effect. The aim of the present study was to investigate the effect and mechanism of chloroquine- and primaquine-induced apoptosis of breast cancer cells. We showed that primaquine, a malaria drug, inhibits the growth, migration, and colony formation of breast cancer cells in vitro, and inhibits tumor growth in vivo. Primaquine induces damage to early endosomes and inhibits the nuclear translocation of EGFR. Primaquine inhibits the interaction of Stat3 and nEGFR and reduces the transcript and protein levels of c-Myc. Moreover, primaquine and chloroquine induce the apoptosis of breast cancer cells through c-Myc/Bcl-2 downregulation, induce early endosome damage and reduce nEGFR levels, and induce apoptosis in breast cancer through nEGFR/Stat3-dependent c-Myc downregulation. Our study of primaquine and chloroquine provides a rationale for targeting EGFR signaling components in the treatment of breast cancer.

New Trends for Antimalarial Drugs: Synergism between Antineoplastics and Antimalarials on Breast Cancer Cells

Chemotherapy plays a key role in breast cancer therapy, but drug resistance and unwanted side effects make the treatment less effective. We propose a new combination model that combines antineoplastic drugs and antimalarials for breast cancer therapy. Cytotoxic effects of two antineoplastic agents alone and in combination with several antimalarials on MCF-7 tumor cell line was evaluated. Different concentrations in a fixed ratio were added to the cultured cells and incubated for 48 h. Cell viability was evaluated using MTT and SRB assays. Synergism was evaluated using the Chou-Talalay method. The results indicate doxorubicin (DOX) and paclitaxel (PTX) alone at concentrations of their IC50 and higher are cell growth inhibitors. Mefloquine, artesunate, and chloroquine at concentrations of their IC50 demonstrate anti-cancer activity. In combination, almost all antimalarials demonstrate higher ability than DOX and PTX alone to decrease cell viability at concentrations of IC50 and lower than their IC50. The combination of chloroquine, artesunate and mefloquine with DOX and PTX was synergic (CI < 1). The combination of DOX and mefloquine after 48 h incubation demonstrated the highest cytotoxicity against MCF-7 cells, and the combination of DOX and artesunate was the most synergic. These results suggest antimalarials could act synergistically with DOX/PTX for breast cancer therapy.

Repurposing old drugs to fight multidrug resistant cancers

Overcoming multidrug resistance represents a major challenge for cancer treatment. In the search for new chemotherapeutics to treat malignant diseases, drug repurposing gained a tremendous interest during the past years. Repositioning candidates have often emerged through several stages of clinical drug development, and may even be marketed, thus attracting the attention and interest of pharmaceutical companies as well as regulatory agencies. Typically, drug repositioning has been serendipitous, using undesired side effects of small molecule drugs to exploit new disease indications. As bioinformatics gain increasing popularity as an integral component of drug discovery, more rational approaches are needed. Herein, we show some practical examples of in silico approaches such as pharmacophore modelling, as well as pharmacophore- and docking-based virtual screening for a fast and cost-effective repurposing of small molecule drugs against multidrug resistant cancers. We provide a timely and comprehensive overview of compounds with considerable potential to be repositioned for cancer therapeutics. These drugs are from diverse chemotherapeutic classes. We emphasize the scope and limitations of anthelmintics, antibiotics, antifungals, antivirals, antimalarials, antihypertensives, psychopharmaceuticals and antidiabetics that have shown extensive immunomodulatory, antiproliferative, pro-apoptotic, and antimetastatic potential. These drugs, either used alone or in combination with existing anticancer chemotherapeutics, represent strong candidates to prevent or overcome drug resistance. We particularly focus on outcomes and future perspectives of drug repositioning for the treatment of multidrug resistant tumors and discuss current possibilities and limitations of preclinical and clinical investigations.

The Endosomal Recycling Pathway-At the Crossroads of the Cell

The endosomal recycling pathway lies at the heart of the membrane trafficking machinery in the cell. It plays a central role in determining the composition of the plasma membrane and is thus critical for normal cellular homeostasis. However, defective endosomal recycling has been linked to a wide range of diseases, including cancer and some of the most common neurological disorders. It is also frequently subverted by many diverse human pathogens in order to successfully infect cells. Despite its importance, endosomal recycling remains relatively understudied in comparison to the endocytic and secretory transport pathways. A greater understanding of the molecular mechanisms that support transport through the endosomal recycling pathway will provide deeper insights into the pathophysiology of disease and will likely identify new approaches for their detection and treatment. This review will provide an overview of the normal physiological role of the endosomal recycling pathway, describe the consequences when it malfunctions, and discuss potential strategies for modulating its activity.

Nanoparticles Formulations of Artemisinin and Derivatives as Potential Therapeutics for the Treatment of Cancer, Leishmaniasis and Malaria

Cancer, malaria, and leishmaniasis remain the deadly diseases around the world although several strategies of treatment have been developed. However, most of the drugs used to treat the aforementioned diseases suffer from several pharmacological limitations such as poor pharmacokinetics, toxicity, drug resistance, poor bioavailability and water solubility. Artemisinin and its derivatives are antimalarial drugs. However, they also exhibit anticancer and antileishmanial activity. They have been evaluated as potential anticancer and antileishmanial drugs but their use is also limited by their poor water solubility and poor bioavailability. To overcome the aforementioned limitations associated with artemisinin and its derivatives used for the treatment of these diseases, they have been incorporated into nanoparticles. Several researchers incorporated this class of drugs into nanoparticles resulting in enhanced therapeutic outcomes. Their potential efficacy for the treatment of parasitic infections such as malaria and leishmaniasis and chronic diseases such as cancer has been reported. This review article will be focused on the nanoparticles formulations of artemisinin and derivatives for the treatment of cancer, malaria, and leishmaniasis and the biological outcomes (in vitro and in vivo).

Lysosome Inhibition by Mefloquine Preferentially Enhances the Cytotoxic Effects of Tyrosine Kinase Inhibitors in Blast Phase Chronic Myeloid Leukemia

Despite the efficacy of BCR-ABL tyrosine kinase inhibitors (TKIs) in chronic phase-chronic myeloid leukemia, the management of blast phase-chronic myeloid leukemia (BP-CML) remains a challenge. Therefore, there is an urgent need to identify alternative agents that act synergistically with BCR-ABL TKIs in BP-CML. Our results show that the anti-malarial agent, mefloquine augments the efficacy of TKIs in CML cell lines and primary CML cells in vitro, including those with the T315I mutation. This effect is selective as mefloquine is more effective in inducing apoptosis, inhibiting colony formation and self-renewal capacity of CD34⁺ cells derived from TKI-resistant BP-CML patients than normal cord blood (CB) CD34⁺ stem/progenitor cells. Notably, the combination of mefloquine and TKIs at sublethal concentrations leads to synergistic effects in CML CD34⁺ cells, while sparing normal CB CD34⁺ cells. We further demonstrate that the initial action of mefloquine in CML cells is to increase lysosomal biogenesis and activation, followed by oxidative stress, lysosomal lipid damage and functional impairment. Taken together, our work elucidates that mefloquine selectively augments the effects of TKIs in CML stem/progenitor cells by inducing lysosomal dysfunction.

Inhibition of glioblastoma cell proliferation, invasion, and mechanism of action of a novel hydroxamic acid hybrid molecule

Glioblastoma multiforme is one of the most aggressive brain tumors and current therapies with temozolomide or suberoylanilide hydroxamic acid (SAHA, vorinostat) show considerable limitations. SAHA is a histone deacetylase (HDAC) inhibitor that can cause undesirable side effects due to the lack of selectivity. We show here properties of a novel hybrid molecule, sahaquine, which selectively inhibits cytoplasmic HDAC6 at nanomolar concentrations without markedly suppressing class I HDACs. Inhibition of HDAC6 leads to significant α-tubulin acetylation, thereby impairing cytoskeletal organization in glioblastoma cells. The primaquine moiety of sahaquine reduced the activity of P-glycoprotein, which contributes to glioblastoma multiforme drug resistance. We propose the mechanism of action of sahaquine to implicate HDAC6 inhibition together with suppression of epidermal growth factor receptor and downstream kinase activity, which are prominent therapeutic targets in glioblastoma multiforme. Sahaquine significantly reduces the viability and invasiveness of glioblastoma tumoroids, as well as brain tumor stem cells, which are key to tumor survival and recurrence. These effects are augmented with the combination of sahaquine with temozolomide, the natural compound quercetin or buthionine sulfoximine, an inhibitor of glutathione biosynthesis. Thus, a combination of agents disrupting glioblastoma and brain tumor stem cell homeostasis provides an effective anti–cancer intervention.

Lysosomotropism depends on glucose: a chloroquine resistance mechanism

There has been long-standing interest in targeting pro-survival autophagy as a combinational cancer therapeutic strategy. Clinical trials are in progress testing chloroquine (CQ) or its derivatives in combination with chemo- or radiotherapy for solid and haematological cancers. Although CQ has shown efficacy in preclinical models, its mechanism of action remains equivocal. Here, we tested how effectively CQ sensitises metastatic breast cancer cells to further stress conditions such as ionising irradiation, doxorubicin, PI3K-Akt inhibition and serum withdrawal. Contrary to the conventional model, the cytotoxic effects of CQ were found to be autophagy-independent, as genetic targeting of ATG7 or the ULK1/2 complex could not sensitise cells, like CQ, to serum depletion. Interestingly, although CQ combined with serum starvation was robustly cytotoxic, further glucose starvation under these conditions led to a full rescue of cell viability. Inhibition of hexokinase using 2-deoxyglucose (2DG) similarly led to CQ resistance. As this form of cell death did not resemble classical caspase-dependent apoptosis, we hypothesised that CQ-mediated cytotoxicity was primarily via a lysosome-dependent mechanism. Indeed, CQ treatment led to marked lysosomal swelling and recruitment of Galectin3 to sites of membrane damage. Strikingly, glucose starvation or 2DG prevented CQ from inducing lysosomal damage and subsequent cell death. Importantly, we found that the related compound, amodiaquine, was more potent than CQ for cell killing and not susceptible to interference from glucose starvation. Taken together, our data indicate that CQ effectively targets the lysosome to sensitise towards cell death but is prone to a glucose-dependent resistance mechanism, thus providing rationale for the related compound amodiaquine (currently used in humans) as a better therapeutic option for cancer.

Cisplatin combination drugs induce autophagy in HeLa cells and interact with HSA via electrostatic binding affinity

Cisplatin combination drugs induce autophagy in HeLa cells and interact with HSAviaelectrostatic binding affinity.

Therapeutic effects of antibiotic drug mefloquine against cervical cancer through impairing mitochondrial function and inhibiting mTOR pathway

Targeting mitochondria is an attractive strategy for cancer therapy due to the essential roles of mitochondria in cancer cell energy metabolism. In this study, we show that mefloquine, an antibiotic drug, effectively targets cervical cancer cells through impairing mitochondrial function. Mefloquine dose-dependently induces apoptosis and inhibits proliferation and anchorage-independent colony formation of multiple cervical cancer cell lines. Mefloquine alone inhibits cervical tumor growth in vivo and its combination with paclitaxel is synergistic in inhibiting tumor growth. Mechanistically, mefloquine inhibits mitochondrial function via inhibiting mitochondrial respiration, decreasing membrane potential, increasing ROS generation, and decreasing ATP level. We further show that mefloquine suppresses activation of mTOR signaling pathway in HeLa cells. However, the inhibitory effects of mefloquine on survival, colony formation, and ATP are abolished in mitochondrial respiration-deficient HeLa ρ⁰ cells, demonstrating that mefloquine acts on cervical cancer cells via targeting mitochondrial respiration. Inhibition of mTOR signaling pathway by mefloquine was also reversed in HeLa ρ⁰ cells, suggesting deactivation of mTOR pathway as a consequence of mitochondria function disruption. Our work suggests that mefloquine is a potential candidate for cervical cancer treatment. Our work also highlights the therapeutic value of anti-mitochondria and establishes the association of mitochondrial function and the activation of mTOR signaling pathway in cervical cancer cells.

Adverse neuropsychiatric effects of antimalarial drugs

INTRODUCTION

Antimalarial drugs are the primary weapon to treat parasite infection, save lives, and curtail further transmission. Accumulating data have indicated that at least some antimalarial drugs may contribute to severe neurological and/or psychiatric side effects which further complicates their use and limits the pool of available medications.

AREAS COVERED

In this review article, we summarize published scientific studies in search of evidence of the neuropsychiatric effects that may be attributed to the commonly used antimalarial drugs administered alone or in combination. Each individual drug was used as a search term in addition to keywords such as neuropsychiatric, adverse events, and neurotoxicity.

EXPERT OPINION

Accumulating data based on published reports over several decades have suggested that among the major commonly used antimalarial drugs, only mefloquine exhibited clear indications of serious neurological and/or psychiatric side effects. A more systematic approach to assess the neuropsychiatric adverse effects of new or repurposed antimalarial drugs on their safety, tolerability and efficacy phases of clinical studies and in post-marketing surveillance, is needed to ensure that these life-saving tools remain available and can be prescribed with appropriate caution and medical judgment.

Psoralen reverses the P-glycoprotein-mediated multidrug resistance in human breast cancer MCF-7/ADR cells

The resistance of cancer to chemotherapeutic agents is a major obstacle during chemotherapy. Clinical multidrug resistance (MDR) is commonly mediated by membrane drug efflux pumps, including ATP‑binding cassette subfamily B member 1, also termed P-glycoprotein (P-gp). P-gp is a membrane transporter encoded by the MDR1 gene. The current study aimed to investigate the impact of psoralen on the expression and function of P‑gp. The 10% inhibitory concentration (IC10) of psoralen, and its capacity to reduce MDR in adriamycin (ADR)‑resistant MCF‑7/ADR cells were determined using MTT assay. The ability of psoralen to modulate the transport activity of P‑gp in MCF‑7/ADR cells was evaluated by measuring the accumulation and efflux of rhodamine 123 (Rh 123) and adriamycin with flow cytometry. The present study evaluated the mRNA level of MDR1 in MCF‑7 and MCF‑7/ADR cells treated with psoralen using reverse transcription-quantitative polymerase chain reaction. The protein expression level of P‑gp was examined by western blot analysis. The current study demonstrated that the IC10 of psoralen in MCF‑7/ADR cells was 8 µg/ml. At 8 µg/ml, psoralen reduced MDR and the sensitivity of the MCF‑7/ADR cells to ADR compared with untreated cells. Additionally, psoralen significantly increased the intracellular accumulation of ADR and Rh 123. However, the IC10 of psoralen did not affect the protein expression levels of P‑gp or mRNA levels of MDR1 (P>0.05). Psoralen reduces MDR by inhibiting the efflux function of P‑gp, which may be important for increasing the efficiency of chemotherapy and improving the clinical protocols aiming to reverse P-gp-mediated MDR.

Mefloquine effectively targets gastric cancer cells through phosphatase-dependent inhibition of PI3K/Akt/mTOR signaling pathway

Deregulation of PI3K/Akt/mTOR pathway has been recently identified to play a crucial role in the progress of human gastric cancer. In this study, we show that mefloquine, a FDA-approved anti-malarial drug, effectively targets human gastric cancer cells. Mefloquine potently inhibits proliferation and induces apoptosis of a panel of human gastric cancer cell lines, with EC50 ∼ 0.5-0.7 μM. In two independent gastric cancer xenograft mouse models, mefloquine significantly inhibits growth of both tumors. The combination of mefloquine with paclitaxel enhances the activity of either drug alone in in vitro and in vivo. In addition, mefloquine potently decreased phosphorylation of PI3K, Akt, mTOR and rS6. Overexpression of constitutively active Akt significantly restored mefloquine-mediated inhibition of mTOR phosphorylation and growth, and induction of apoptosis, suggesting that mefloquine acts on gastric cancer cells via suppressing PI3K/Akt/mTOR pathway. We further show that mefloquine-mediated inhibition of Akt/mTOR singaling is phosphatase-dependent as pretreatment with calyculin A does-dependently reversed mefloquine-mediated inhibition of Akt/mTOR phosphorylation. Since mefloquine is already available for clinic use, these results suggest that it is a useful addition to the treatment armamentarium for gastric cancer.

Anti-malarials are anti-cancers and vice versa - one arrow two sparrows

Repurposing is the novel means of drug discovery in modern science due to its affordability, safety and availability. Here, we systematically discussed the efficacy and mode of action of multiple bioactive, synthetic compounds and their potential derivatives which are used to treat/prevent malaria and cancer. We have also discussed the detailed molecular pathway involved in anti-cancer potentiality of an anti-malarial drug and vice versa. Although the causative agents, pathophysiology and manifestation of both the diseases are different but special emphasis has been given on similar pathways governing disease manifestation and the drugs which act through deregulating those pathways. Finally, a future direction has been speculated to combat these two diseases by a single agent developed using nanotechnology. Extended combination and new formulation of existing drugs for one disease may lead to the discovery of drug for other diseases like an arrow for two sparrows.

Selenate specifically sensitizes drug-resistant cancer cells by increasing apoptosis via G2 phase cell cycle arrest without P-GP inhibition

The purpose of this study was to identify conditions that will increase the sensitivity of drug-resistant cancer cells. Selenium derivatives have been shown to present anti-cancer properties in the clinic. Currently, selenate, selenite, selenomethionine (SeMet), methyl-selenocysteine (MSC), and methaneselenic acid (MSA) are the most common selenium derivatives used as drugs in humans. Herein, we tested whether these selenium derivatives can sensitize KBV20C cancer cells, which are highly resistant to anti-cancer drugs such as vincristine. All five drugs could sensitize KBV20C cells to the same extent as they sensitized the sensitive parent KB cells, suggesting that selenium-derived drugs can be used for drug-resistant cancer cells. We also observed that these drugs did not inhibit the P-glycoprotein (P-gp) pumping-out ability, suggesting that the sensitization by selenium-derived drugs does not depend on P-gp activity in resistant KBV20C cells. Interestingly, using a cell viability assay, microscopic observation, and Hoechst staining, we found that selenate highly sensitized drug-resistant KBV20C cells by activating the apoptotic pathway, when compared to sensitive KB cells. Furthermore, we investigated why selenate sensitizes resistant KBV20C cells. Selenate-induced toxicity was associated with an increase in G2-phase cell cycle arrest in KBV20C cells, suggesting that the selenate-induced increase in apoptosis resulted from cell cycle arrest in resistant KBV20C cells. Our findings may contribute to the development of selenate-based therapies for patients resistant to cancer drugs.

Thioridazine specifically sensitizes drug-resistant cancer cells through highly increase in apoptosis and P-gp inhibition

This study was designed to identify conditions that induce an increase in the sensitivity of drug-resistant cancer cells compared to sensitive cells. Using cell proliferation assays and microscopic observation, thioridazine (THIO) was found to induce higher sensitization in drug-resistant KBV20C cancer cells compared to sensitive KB parent cells. By studying cleaved PARP, annexin V staining, and Hoechst staining, we found that THIO largely increased apoptosis specifically in KBV20C cells, suggesting that the difference in sensitization between the resistant and sensitive cells can be attributed to the ability of THIO to induce apoptosis. THIO could also inhibit p-glycoprotein (P-gp) activity in the resistant KBV20C cells. These observations suggest that the mechanisms underlying THIO sensitization in resistant KBV20C cells involve both apoptosis and P-gp inhibition. Furthermore, co-treatment with THIO and vinblastine (VIB) induces higher sensitization in KBV20C cells than KB cells. As observed in a single treatment with THIO, the sensitization mechanism induced by the co-treatment also involves both apoptosis and P-gp inhibition. These results suggest that the THIO sensitization mechanism is generally conserved. Our findings may contribute to the development of THIO-based therapies for patients presenting resistance to antimitotic drugs.