Near infrared-responsive quinacrine-gold hybrid nanoparticles deregulate HSP-70/P300-mediated H3K14 acetylation in ER/PR+ breast cancer stem cells.

Aim: This study aimed to determine if quinacrine-gold hybrid nanoparticles (QAuNPs) + near-infrared (NIR) deregulate HSP-70/P300 complex-mediated H3K14 acetylation in estrogen receptor/progesterone receptor (ER/PR+) breast cancer stem cells (CSCs). Materials & methods: Various cells and mouse-based systems were used as models. Results: QAuNP + NIR treatment reduced the nuclear translocation of HSP-70, affected the histone acetyltransferase activity of P300 and specifically decreased H3K14 acetylation in ER/PR+ breast CSCs. Finally, HSP-70 knockdown showed a reduction in P300 histone acetyltransferase activity, decreased H3K14 acetylation and inhibited activation of the TGF-ß gene. Conclusion: This study revealed that QAuNP + NIR irradiation inhibits oncogenic activation of the TGF-ß gene by decreasing H3K14 acetylation mediated through the HSP-70/P300 nuclear complex in ER/PR+ breast CSCs.

Quinacrine - The Winding Road from the Most Important Antimalarial of Its Time to an Indispensable Antiparasitic (Orphan) Drug of our Days.

Quinacrine, the main antimalarial drug during World War II, has had a chequered history that included the successful repurposing as an intrapleural sclerosant for the treatment of malignant pleural effusions, a non-surgical method of female sterilisation, and the use as an immunomodulatory drug in lupus erythematosus. While no longer used for these former indications, quinacrine (re)emerged as an indispensable second-line drug for the treatment of nitroimidazole-refractory Giardia duodenalis infections, and thus depicts an indispensable "orphan drug".

Talazoparib enhances the quinacrine-mediated apoptosis in patient-derived oral mucosa CSCs by inhibiting BER pathway through the modulation of GCN5 and P300.

The presence of cancer stem cells (CSCs) in the tumor microenvironment (TME) is majorly responsible for the development and recurrence of cancer. Earlier reports suggested that upon DNA damage, poly-(ADP-ribose) polymerase-1 (PARP-1) helps in chromatin modulation and DNA repair process, thereby promoting CSC survival. But whether a combination of DNA damaging agents along with PARP inhibitors can modulate chromatin assembly, inhibit DNA repair processes, and subsequently target CSCs is not known. Hence, we have investigated the effect of nontoxic bioactive compound quinacrine (QC) and a potent PARP inhibitor Talazoparib in patient-derived oral mucosa CSCs (OM-CSCs) and in vivo xenograft mice preclinical model systems. Data showed that QC + Talazoparib inhibited the PARP-1-mediated chromatin remodelers' recruitment and deregulated HAT activity of GCN5 (general control nonderepressible-5) and P300 at DNA damage site, thereby preventing the access of repair proteins to the damaged DNA. Additionally, this combination treatment inhibited topoisomerase activity, induced topological stress, and induced apoptosis in OM-CSCs. Similar results were observed in an in vivo xenograft mice model system. Collectively, the data suggested that QC + Talazoparib treatment inhibited BER pathway, induced genomic instability and triggered apoptosis in OM-CSCs through the deregulation of PARP-1-mediated chromatin remodelers (GCN5 and P300) activity. Schematic representation of QC + Talazoparib-induced apoptosis in oral mucosa CSCs. (1) Induction of DNA damage takes place after QC treatment (2) PARP1-mediated PARylation at the site of DNA damage, which recruits multiple chromatin remodelers (3) Acetylation at the histone tails relax the structure of chromatin and recruits the BER pathway proteins at the site of DNA damage. (4) BER pathway activated at the site of DNA damage. (5) CSCs survive after successful repair of DNA damage. (6) Treatment of QC-treated CSCs with PARP inhibitor Talazoparib (7) Inhibition of PARylation results in failure of chromatin remodelers to interact with PARP1. (8) Inhibition of acetylation status leads to chromatin compaction. (9) BER pathway proteins are not recruited at the site of DNA damage, resulting in inhibition of BER pathway and accumulation of unrepaired DNA damage, leading to apoptosis and cell death.

Quinacrine inhibits HIF-1α/VEGF-A mediated angiogenesis by disrupting the interaction between cMET and ABCG2 in patient-derived breast cancer stem cells.

BACKGROUND: Breast cancer stem cells (BCSCs) have a critical role in progression of breast cancer by inducing angiogenesis. Several therapeutic strategies have been designed for the treatment of breast cancer by specifically preventing angiogenesis. But there is a dearth of study regarding the treatment procedure which can specifically target and kill the BCSCs and cause lesser harm to healthy cells of the body. A plant-based bioactive compound Quinacrine (QC) specifically kills cancer stem cells (CSCs) without harming healthy cells and also inhibits cancer angiogenesis but the detailed mechanistic study of its anti-CSCs and anti-angiogenic activity is yet to explore. HYPOTHESIS: Earlier report showed that both cMET and ABCG2 play an essential role in cancer angiogenesis. Both are present on the cell surface of CSCs and share an identical ATP-binding domain. Interestingly, QC a plant based and bioactive compound which was found to inhibit the function of CSCs marker cMET and ABCG2. These relevant evidence led us to hypothesize that cMET and ABCG2 may interact with each other and induce the production of angiogenic factors, resulting in activation of cancer angiogenesis and QC might disrupt the interaction between them to stop this phenomena. METHODS: Co-immunoprecipitation assay, immunofluorescence assay, and western blotting were performed by using ex vivo patient-derived breast cancer-stem-cells (PDBCSCs) and human umbilical vein endothelial cells (HUVECs). In silico study was carried out to check the interaction between cMET and ABCG2 in presence or absence of QC. Tube formation assay using HUVECs and in ovo Chorioallantoic membrane (CAM) assay using chick fertilized eggs were performed to monitor angiogenesis. In vivo patient-derived xenograft (PDX) mice model was used to validate in silico and ex vivo results. RESULTS: Data revealed that in a hypoxic tumor microenvironment (TME), cMET and ABCG2 interact with each other and upregulate HIF-1α/VEGF-A axis to induce breast cancer angiogenesis. In silico and ex vivo study showed that QC disrupted the interaction between cMET and ABCG2 to inhibit the angiogenic response in endothelial cells by reducing the secretion of VEGF-A from PDBCSCs within the TME. Knockdown of cMET, ABCG2 or both, significantly downregulated the expression of HIF-1α and reduced the secretion of pro-angiogenic factor VEGF-A in the TME of PDBCSCs. Additionally, when PDBCSCs were treated with QC, similar experimental results were obtained. CONCLUSION: In silico, in ovo, ex vivo and in vivo data confirmed that QC inhibited the HIF-1α/VEGF-A mediated angiogenesis in breast cancer by disrupting the interaction between cMET and ABCG2.

Combination of niclosamide and quinacrine inactivates Akt/HK2/Cyclin D1 axis mediated by glucose deprivation towards the inhibition of melanoma cell proliferation.

Malignant melanoma is one of the most aggressive and lethal skin cancer. At present, the treatment methods for melanoma have shortcomings. Glucose is the primary energy source of cancer cells. However, it is unclear whether glucose deprivation can be used to treat melanoma. Herein, we first found glucose played an essential role in melanoma proliferation. We then further found a drug combination of niclosamide and quinacrine could inhibit melanoma proliferation and glucose intake. Thirdly, we revealed the mechanism of anti-melanoma effect of the drug combination, which suppressed the Akt pathway. In addition, the first-rate limiting enzyme HK2 of glucose metabolism was inhibited. This work also disclosed that the decrease of HK2 inhibited cyclin D1 by reducing the activity of transcription factor E2F3, which further suppressed the proliferation of melanoma cells. The drug combination treatment also resulted in significant tumor regression in the absence of obvious morphologic changes in primary organ in vivo. In summary, our study demonstrated that the drug combination treatment created glucose deprivation to inactive the Akt/HK2/cyclin D1 axis, thereby inhibited the proliferation of melanoma cells, providing a potential anti-melanoma strategy.

Near-infrared enhances antiangiogenic potentiality of quinacrine-gold hybrid nanoparticles in breast cancer stem cells via deregulation of HSP-70/TGF-ß.

Aim: This study aimed to explore the antiangiogenic mechanism of quinacrine-gold hybrid nanoparticle (QAuNP) and near-infrared (NIR) radiation in patient-derived primary breast cancer stem cells. Materials & methods: Various cell-based in ovo angiogenesis and in vivo patient-derived xenograft mouse systems were used as models for the study. Results: The experimental results showed that QAuNP + NIR treatment deregulated the HSP-70/TGF-ß physical interaction in primary breast cancer stem cells. Reduced TGF-ß secretion in the tumor microenvironment inhibited angiogenesis activation in endothelial cells by deregulating the TGF-ß-mediated PI3K/AKT/mTOR cascade. Conclusion: This study revealed that QAuNP + NIR irradiation downregulated HSP-70 expression, inhibited the HSP-70/TGF-ß interaction, reduced the secretion of TGF-ß in the tumor microenvironment and ultimately inhibited TGF-ß-mediated angiogenesis.

This study discovered that the formation of blood vessels in breast cancer is significantly reduced when hybrid nanoparticles and infrared laser therapy are used to treat breast cancer stem cells. The secretory cytokines in the tumor microenvironment primarily responsible for developing blood vessels in the tumor are dramatically reduced by treatment. As a result, the tumor's blood vessel growth is reduced, making it difficult for the cancer cells to get the nutrients and oxygen they need to survive.

Quinacrine attenuates diet-induced obesity by inhibiting adipogenesis via activation of AMPK signaling.

Obesity, a global epidemic chronic metabolic disease, urgently demands novel therapies. As an antimalarial drug, quinacrine has not been reported for its anti-obesity effect to our knowledge. This study aimed to explore the ability of quinacrine to attenuate obesity. In an in vitro adipogenic model, quinacrine exhibited an outstanding suppression on adipogenesis of 3T3-L1 cells, mainly by activating the AMPK (Adenosine 5'-monophosphate (AMP)-activated protein kinase) signaling pathway to regulate preadipocytes differentiation and lipid accumulation. In addition, C57BL/6N female mice were fed with high-fat diet and high-fructose water for 14 weeks to establish an obesity model, followed by oral administration of quinacrine or orlistat. After 9 weeks of treatment, quinacrine significantly reduced the body weight and energy intake, ameliorated the impaired glucose tolerance and restored the homeostasis of serum lipids. Also, quinacrine improved lipid profile and optimized the expression of AMPK signaling pathway related proteins in livers and adipose tissues of obese mice. Quinacrine reverses obesity through activating AMPK phosphorylation to down-regulate adipogenesis, along with lowering the risk of type 2 diabetes and atherosclerosis. It should be a novel application for the treatment of obesity and its associated diseases.

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.

Discovery of Quinacrine as a Potent Topo II and Hsp90 Dual-Target Inhibitor, Repurposing for Cancer Therapy.

Topo II and Hsp90 are promising targets. In this study, we first verified the structural similarities between Topo IIα ATPase and Hsp90α N-ATPase. Subsequently, 720 compounds from the Food and Drug Administration (FDA) drug library and kinase library were screened using the malachite green phosphate combination with the Topo II-mediated DNA relaxation and MTT assays. Subsequently, the antimalarial drug quinacrine was found to be a potential dual-target inhibitor of Topo II and Hsp90. Mechanistic studies showed that quinacrine could specifically bind to the Topo IIα ATPase domain and inhibit the activity of Topo IIα ATPase without impacting DNA cleavage. Furthermore, our study revealed that quinacrine could bind Hsp90 N-ATPase and inhibit Hsp90 activity. Significantly, quinacrine has broad antiproliferation activity and remains sensitive to the multidrug-resistant cell line MCF-7/ADR and the atypical drug-resistant tumor cell line HL-60/MX2. Our study identified quinacrine as a potential dual-target inhibitor of Topo II and Hsp90, depending on the ATP-binding domain, positioning it as a hit compound for further structural modification.

Safranal Induces Vasorelaxation by Inhibiting Ca2+ Influx and Na+/Ca2+ Exchanger in Isolated Rat Aortic Rings.

Introduction: Safranal, which endows saffron its unique aroma, causes vasodilatation and has a hypotensive effect in animal studies, but the mechanisms of these effects are unknown. In this study, we investigated the mechanisms of safranal vasodilation. Methods: Isolated rat endothelium-intact or -denuded aortic rings were precontracted with phenylephrine and then relaxed with safranal. To further assess the involvement of nitric oxide, prostaglandins, guanylate cyclase, and phospholipase A2 in safranal-induced vasodilation, aortic rings were preincubated with L-NAME, indomethacin, methylene blue, or quinacrine, respectively, then precontracted with phenylephrine, and safranal concentration-response curves were established. To explore the effects of safranal on Ca2+ influx, phenylephrine and CaCl2 concentration-response curves were established in the presence of safranal. Furthermore, the effect of safranal on aortic rings in the presence of ouabain, a Na+-K+ ATPase inhibitor, was studied to explore the contribution of Na+/Ca2+ exchanger to this vasodilation. Results: Safranal caused vasodilation in endothelium-intact and endothelium-denuded aortic rings. The vasodilation was not eliminated by pretreatment with L-NAME, indomethacin, methylene blue, or quinacrine, indicating the lack of a role for NO/cGMP. Safranal significantly inhibited the maximum contractions induced by phenylephrine, or by CaCl2 in Ca2+-free depolarizing buffer. Safranal also relaxed contractions induced by ouabain, but pretreatment with safranal totally abolished the development of ouabain contractions. Discussion/Conclusion: Inhibition of Na+-K+ ATPase by ouabain leads to the accumulation of Na+ intracellularly, forcing the Na+/Ca2+ exchanger to work in reverse mode, thus causing a contraction. Inhibition of the development of this contraction by preincubation with safranal indicates that safranal inhibited the Na+/Ca2+ exchanger. We conclude that safranal vasodilation is mediated by the inhibition of calcium influx from extracellular space through L-type Ca2+ channels and by the inhibition of the Na+/Ca2+ exchanger.

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.

Multidimensional Immune Profiling of Cutaneous Lupus Erythematosus In Vivo Stratified by Patient Response to Antimalarials.

OBJECTIVE: The pathogenesis of cutaneous lupus erythematosus (CLE) is multifactorial, and CLE is difficult to treat due to the heterogeneity of inflammatory processes among patients. Antimalarials such as hydroxychloroquine (HCQ) and quinacrine (QC) have long been used as first-line systemic therapy; however, many patients do not respond to treatment with antimalarials and require systemic immunosuppressants that produce undesirable side effects. Given the complexity and the unpredictability of responses to antimalarial treatments in CLE patients, we sought to characterize the immunologic profile of patients with CLE stratified by subsequent treatment outcomes to identify potential biomarkers of inducible response. METHODS: We performed mass cytometry imaging of multiple immune cell types and inflammation markers in treatment-naive skin biopsy samples from 48 patients with CLE to identify baseline immunophenotypes that may predict the response to antimalarial therapy. Patients were stratified according to their response to treatment with antimalarials, as HCQ responders, QC responders, or nonresponders. RESULTS: HCQ responders demonstrated increased CD4+ T cells compared to the QC responder group. Patients in the nonresponder group were found to have decreased Treg cells compared to QC responders and increased central memory T cells compared to HCQ responders. QC responders expressed increased phosphorylated stimulator of interferon genes (pSTING) and interferon-κ (IFNκ) compared to HCQ responders. Phosphorylated STING and IFNκ were found to be localized to conventional dendritic cells (cDCs), and the intensity of pSTING and IFNκ staining was positively correlated with the number of cDCs on a tissue and cellular level. Neighborhood analysis revealed decreased regulatory cell interactions in nonresponder patients. Hierarchical clustering revealed that nonresponder patients could be further differentiated based on expression of pSTAT2, pSTAT3, pSTAT4, pSTAT5, phosphorylated interferon regulatory factor 3 (pIRF3), granzyme B, pJAK2, interleukin-4 (IL-4), IL-17, and IFNγ. CONCLUSION: These findings indicate differential immune cell compositions between patients with CLE, offering guidance for future research on precision-based medicine and treatment response.

Multimodal Investigation into the Interaction of Quinacrine with Microcavity-Supported Lipid Bilayers.

Quinacrine is a versatile drug that is widely recognized for its antimalarial action through its inhibition of the phospholipase enzyme. It also has antianthelmintic and antiprotozoan activities and is a strong DNA binder that may be used to combat multidrug resistance in cancer. Despite extensive cell-based studies, a detailed understanding of quinacrine's influence on the cell membrane, including permeability, binding, and rearrangement at the molecular level, is lacking. Herein, we apply microcavity-suspended lipid bilayers (MSLBs) as in vitro models of the cell membrane comprising DOPC, DOPC:Chol(3:1), and DOPC:SM:Chol(2:2:1) to investigate the influence of cholesterol and intrinsic phase heterogeneity induced by mixed-lipid composition on the membrane interactions of quinacrine. Using electrochemical impedance spectroscopy (EIS) and surface-enhanced Raman spectroscopy (SERS) as label-free surface-sensitive techniques, we have studied quinacrine interaction and permeability across the different MSLBs. Our EIS data reveal that the drug is permeable through ternary DOPC:SM:Chol and DOPC-only bilayer compositions. In contrast, the binary cholesterol/DOPC membrane arrested permeation, yet the drug binds or intercalates at this membrane as reflected by an increase in membrane impedance. SERS supported the EIS data, which was utilized to gain structural insights into the drug-membrane interaction. Our SERS data also provides a simple but powerful label-free assessment of drug permeation because a significant SERS enhancement of the drug's Raman signature was observed only if the drug accessed the plasmonic interior of the pore cavity passing through the membrane. Fluorescent lifetime correlation spectroscopy (FLCS) provides further biophysical insight, revealing that quinacrine binding increases the lipid diffusivity of DOPC and the ternary membrane while remarkably decreasing the lipid diffusivity of the DOPC:Chol membrane. Overall, because of its adaptability to multimodal approaches, the MSLB platform provides rich and detailed insights into drug-membrane interactions, making it a powerful tool for in vitro drug screening.

PARP inhibitor BMN-673 induced apoptosis by trapping PARP-1 and inhibiting base excision repair via modulation of pol-ß in chromatin of breast cancer cells.

PARP inhibitors emerged as clinically effective anti-tumor agents in combination with DNA damaging agents but the toxicity of DNA damaging agents and their off-target effects caused serious problems in cancer therapy. They confer cytotoxicity in cancer cells both by catalytic inhibition and trapping of PARP-1 at the DNA damage site. There is a lack of direct evidence to quantitatively determine the trapped PARP-1 in cellular DNA. Here, we have precisely evaluated the mechanism of PARP trapping mediated anti-cancer action of Quinacrine (QC), BMN-673, and their combination (QC + BMN-673) in breast cancer cells. We introduced a strategy to measure the cellular PARP trapping potentiality of BMN-673 in QC pretreated cells using a fluorescence-based assay system. It was found that QC+ BMN-673 induced apoptosis by triggering DNA damage in breast cancer cells. Treatment with QC + BMN-673 stimulated the expression of PARP-1 in the chromatin compared to that of PARP-2 and PARP-3. QC + BMN-673 treatment also caused a dose-dependent and time-dependent accumulation of PARP-1 and inhibition of PARylation in the chromatin. Upregulation of BER components (pol-ß and FEN-1), an unchanged HR and NHEJ pathway proteins, and reduction of luciferase activity of the cells transfected with R-p21-P (LP-BER) were noted in combined drug-treated cells. Interestingly, silencing of pol-ß resulted in unchanged PARP-1 trapping and PAR activity in the chromatin with increasing time after QC + BMN-673 treatment without altering APC and FEN-1 expression. Thus, our data suggested that the QC + BMN-673 augmented breast cancer cell death by pol-ß mediated repair inhibition primarily through trapping of PARP-1 besides PARP-1 catalytic inhibition.

NIR irradiation enhances the apoptotic potentiality of quinacrine-gold hybrid nanoparticles by modulation of HSP-70 in oral cancer stem cells.

Cancer stem cells (CSCs) are the tumor cell subpopulations that can self-renew, differentiate, initiate and maintain tumor growth. CSCs are frequently drug-resistant, resulting in tumor recurrence, metastasis, and angiogenesis. Herein, using in vitro oral squamous cell carcinoma (OSCC) CSCs and in vivo xenograft mice model, we have systematically studied the apoptotic potentiality of quinacrine-gold hybrid nanoparticle (QAuNP) and its underlying mechanism after NIR irradiation. QAuNP + NIR caused DNA damage and induced apoptosis in SCC-9-CSCs by deregulating mitochondrial membrane potential (ΔΨm) and activation of ROS. Upregulation of CASPASE-3 and DR-5/DR-4 and reduction of heat shock protein (HSP-70) up to 5-fold were also noticed upon the treatment. The increased expression of DR-5 and CASPASE-3 and decreased expression of HSP-70, CD-44 and Ki-67 were also noted in the xenograft mice treated with QAuNP + NIR + TRAIL. Thus, data suggest that the combined treatment enhances apoptosis in OSCC-CSCs by modulating HSP-70 in the DISC.

Quinacrine-CASIN combination overcomes chemoresistance in human acute lymphoid leukemia.

Chemoresistance posts a major hurdle for treatment of acute leukemia. There is increasing evidence that prolonged and intensive chemotherapy often fails to eradicate leukemic stem cells, which are protected by the bone marrow niche and can induce relapse. Thus, new therapeutic approaches to overcome chemoresistance are urgently needed. By conducting an ex vivo small molecule screen, here we have identified Quinacrine (QC) as a sensitizer for Cytarabine (AraC) in treating acute lymphoblastic leukemia (ALL). We show that QC enhances AraC-mediated killing of ALL cells, and subsequently abrogates AraC resistance both in vitro and in an ALL-xenograft model. However, while combo AraC+QC treatment prolongs the survival of primary transplanted recipients, the combination exhibits limited efficacy in secondary transplanted recipients, consistent with the survival of niche-protected leukemia stem cells. Introduction of Cdc42 Activity Specific Inhibitor, CASIN, enhances the eradication of ALL leukemia stem cells by AraC+QC and prolongs the survival of both primary and secondary transplanted recipients without affecting normal long-term human hematopoiesis. Together, our findings identify a small-molecule regimen that sensitizes AraC-mediated leukemia eradication and provide a potential therapeutic approach for better ALL treatment.

Quinacrine Ameliorates Cisplatin-Induced Renal Toxicity via Modulation of Sirtuin-1 Pathway.

Renal toxicity is a serious side effect that hinders the use of cisplatin, a commonly used and effective chemotherapeutic agent. Meanwhile, quinacrine is an FDA approved drug that has been stated for its anti-inflammatory effect. Thus, we investigated the ameliorative effect of quinacrine against cisplatin-induced renal toxicity. Single intraperitoneal (i.p.) 10 mg/kg cisplatin administration induced renal injury in rats. Our results showed that 10 mg/kg/day quinacrine decreased the mortality rate of rats from 46.15% (cisplatin group) to 12.5%, and significantly decreased renal tissue fibrosis, relative kidney to body weight ratio, serum creatinine and urea levels compared with the cisplatin group. Indeed, quinacrine significantly decreased renal malondialdehyde concentration and increased renal total antioxidant capacity, compared with the cisplatin group. Furthermore, quinacrine caused significant upregulation of renal sirtuin-1 (SIRT-1) with significant downregulation of intercellular adhesion molecule-1 (ICAM-1) and tumor necrosis factor-α (TNF-α). Moreover, quinacrine significantly blocked cisplatin-induced apoptosis, which was made evident by downregulating renal apoptotic proteins (BAX and p53) and upregulating the renal anti-apoptotic protein BCL2, compared with the cisplatin group. In conclusion, this study demonstrates, for the first time, that quinacrine alleviates cisplatin-induced renal toxicity via upregulating SIRT-1, downregulating inflammatory markers (ICAM-1 and TNF-α), reducing oxidative stress, and inhibiting apoptosis.

Quinacrine is not a vital fluorescent probe for vesicular ATP storage.

Quinacrine, a fluorescent amphipathic amine, has been used as a vital fluorescent probe to visualize vesicular storage of ATP in the field of purinergic signaling. However, the mechanism(s) by which quinacrine represents vesicular ATP storage remains to be clarified. The present study investigated the validity of the use of quinacrine as a vial fluorescent probe for ATP-storing organelles. Vesicular nucleotide transporter (VNUT), an essential component for vesicular storage and ATP release, is present in very low density lipoprotein (VLDL)-containing secretory vesicles in hepatocytes. VNUT gene knockout (Vnut-/-) or clodronate treatment, a VNUT inhibitor, disappeared vesicular ATP release (Tatsushima et al., Biochim Biophys Acta Molecular Basis of Disease 2021, e166013). Upon incubation of mice's primary hepatocytes, quinacrine accumulates in a granular pattern into the cytoplasm, sensitive to 0.1-µM bafilomycin A1, a vacuolar ATPase (V-ATPase) inhibitor. Neither Vnut-/- nor treatment of clodronate affected quinacrine granular accumulation. In vitro, quinacrine is accumulated into liposomes upon imposing inside acidic transmembranous pH gradient (∆pH) irrespective of the presence or absence of ATP. Neither ATP binding on VNUT nor VNUT-mediated uptake of ATP was affected by quinacrine. Consistently, VNUT-mediated uptake of quinacrine was negligible or under the detection limit. From these results, it is concluded that vesicular quinacrine accumulation is not due to a consequence of its interaction with ATP but due to ∆pH-driven concentration across the membranes as an amphipathic amine. Thus, quinacrine is not a vital fluorescent probe for vesicular ATP storage.

Altered expression of ERK, Cytochrome-c, and HSP70 triggers apoptosis in Quinacrine-exposed human invasive ductal carcinoma cells.

Invasive ductal carcinoma (IDC) is the most recurrent cancer, accounting for 80% of all breast cancers worldwide. Originating from the milk duct, it eventually invades the fibrous tissue of the breast outside the duct, proliferation takes 1-2 months for each division. Quinacrine (QC), an FDA-approved small molecule, has been shown to have anti-cancer activity in numerous cancerous cell lines through diverse pathways; ultimately leading to cell death. Here, we have investigated the mode of action of QC in MCF7 cells. This study demonstrated the modulation of cellular cytoskeleton, such as the formation of distinct filopodial and lamellipodial structures and spikes, through the regulation of small-GTPases. We also observed that QC induces a signaling cascade by inducing apoptotic cell death by increasing ROS generation and altering HSP70 expression; which presumably involves ERK regulation. Our findings show that QC could be an attractive chemotherapeutic agent having a "shotgun" nature with potential of inducing different signaling pathways leading to apoptotic cell death. This opens new avenues for research on developing QC as an effective therapeutic agent for the treatment of invasive ductal carcinomas.

Cationic Compounds with SARS-CoV-2 Antiviral Activity and Their Interaction with Organic Cation Transporter/Multidrug and Toxin Extruder Secretory Transporters.

In the wake of the COVID-19 pandemic, drug repurposing has been highlighted for rapid introduction of therapeutics. Proposed drugs with activity against SARS-CoV-2 include compounds with positive charges at physiologic pH, making them potential targets for the organic cation secretory transporters of kidney and liver, i.e., the basolateral organic cation transporters, OCT1 and OCT2; and the apical multidrug and toxin extruders, MATE1 and MATE2-K. We selected several compounds proposed to have in vitro activity against SARS-CoV-2 (chloroquine, hydroxychloroquine, quinacrine, tilorone, pyronaridine, cetylpyridinium, and miramistin) to test their interaction with OCT and MATE transporters. We used Bayesian machine learning models to generate predictions for each molecule with each transporter and also experimentally determined IC50 values for each compound against labeled substrate transport into CHO cells that stably expressed OCT2, MATE1, or MATE2-K using three structurally distinct substrates (atenolol, metformin and 1-methyl-4-phenylpyridinium) to assess the impact of substrate structure on inhibitory efficacy. For the OCTs substrate identity influenced IC50 values, although the effect was larger and more systematic for OCT2. In contrast, inhibition of MATE1-mediated transport was largely insensitive to substrate identity. Unlike MATE1, inhibition of MATE2-K was influenced, albeit modestly, by substrate identity. Maximum unbound plasma concentration/IC50 ratios were used to identify potential clinical DDI recommendations; all the compounds interacted with the OCT/MATE secretory pathway, most with sufficient avidity to represent potential DDI issues for secretion of cationic drugs. This should be considered when proposing cationic agents as repurposed antivirals. SIGNIFICANCE STATEMENT: Drugs proposed as potential COVID-19 therapeutics based on in vitro activity data against SARS-CoV-2 include compounds with positive charges at physiological pH, making them potential interactors with the OCT/MATE renal secretory pathway. We tested seven such molecules as inhibitors of OCT1/2 and MATE1/2-K. All the compounds blocked transport activity regardless of substrate used to monitor activity. Suggesting that plasma concentrations achieved by normal clinical application of the test agents could be expected to influence the pharmacokinetics of selected cationic drugs.