Effects Of Quinacrine Research Articles

Quinacrine and Niclosamide Promote Neurite Growth in Midbrain Dopaminergic Neurons Through the Canonical BMP-Smad Pathway and Protect Against Neurotoxin and α-Synuclein-Induced Neurodegeneration.

Parkinson's disease is a neurodegenerative disorder characterised by nigrostriatal dopaminergic degeneration, and intracellular α-synuclein aggregation. Current pharmacological treatments are solely symptomatic so there is a need to identify agents that can slow or stop dopaminergic degeneration. One proposed class of therapeutics are neurotrophic factors which promote the survival of nigrostriatal dopaminergic neurons. However, neurotrophic factors need to be delivered directly to the brain. An alternative approach may be to identify pharmacological agents which can reach the brain to stimulate neurotrophic factor expression and/or their signalling pathways in dopaminergic neurons. BMP2 is a neurotrophic factor that is expressed in the human substantia nigra; exogenous BMP2 administration protects against dopaminergic degeneration in in vitro models of PD. In this study, we investigated the neurotrophic potential of two FDA-approved drugs, quinacrine and niclosamide, that are modulators of BMP2 signalling. We report that quinacrine and niclosamide, like BMP2, significantly increased neurite length, as a readout of neurotrophic action, in SH-SY5Y cells and dopaminergic neurons in primary cultures of rat ventral mesencephalon. We also show that these effects of quinacrine and niclosamide require the activation of BMP-Smad signalling. Finally, we demonstrate that quinacrine and niclosamide are neuroprotective against degeneration induced by the neurotoxins, MPP+ and 6-OHDA, and by viral-mediated overexpression of α-synuclein in vitro. Collectively, this study identifies two drugs, that are safe for use in patients' to 'are approved for human use, that exert neurotrophic effects on dopaminergic neurons through modulation of BMP-Smad signalling. This rationalises the further study of drugs that target the BMP-Smad pathway as potential neuroprotective pharmacotherapy for Parkinson's disease.

Evaluation of the Gene Expression of Hedgehog Signaling Pathway Components in Response to Quinacrine in MDA-MB 231 Cells

Background: Hedgehog signaling pathway abnormality plays an important role in the development of various cancers. PTCH1 and SMO proteins are essential receptors in the hedgehog signaling pathway. Quinacrine as a derivative of 9-aminoacridine revealed an inhibitory effect on the growth of some cancer cells. Triple-negative breast cancer with stem cell-like characteristics remains a poor prognostic type. Objectives: In this study, the effect of quinacrine on patched1 protein receptor (PTCH1) and smoothened protein receptor (SMO) gene expression in the hedgehog signaling pathway was evaluated in MDA-MB 231 breast cancer cell line. Methods: Toxicity of quinacrine was determined based on the MTT assay results. MDA-MB 231 breast cancer cells were treated with 0.5 µM quinacrine for 72 hours. The alteration of the hedgehog signaling pathway was studied by quantitative assessment of PTCH1 and SMO gene expression. Results were evaluated using t-test and were analyzed based on P < 0.05. Results: This study showed that 0.5 µM quinacrine decreases SMO gene expression involved in the hedgehog signaling pathway (-2.1 fold) in MDA-MB 231 breast cancer cell line (P = 0.007). Quinacrine had no significant effect on PTCH1 gene expression (P = 0.059). Conclusions: The SMO gene inhibition by quinacrine could affect breast cancer cells growth with respect to its oncogenic role.

Effectiveness of Quinacrine (Mepacrine) in Photosensitive Autoimmune Diseases, Lupus Erythematosus, and Dermatomyositis: Report on 38 Cases and Literature Review

Objectives This study aims to report our experience with photosensitive autoimmune diseases including lupus erythematosus and dermatomyositis (DM) treated with quinacrine (Qn) as either monotherapy or combination with other antimalarials, steroids, and immunosuppressive therapy in an add-on regimen in light of a review of the relevant literature.

Abstract 2675: Quinacrine-mediated activation of JNK1 inhibits Nrf2 and causes cell death in human colon cancer

Abstract Up-regulation of Nrf2 is associated with poor prognosis in skin, breast, prostate, lung, head and neck, endometrial, and colorectal cancer, and increases chemoresistance and radioresistance by inducing antioxidant and detoxification genes. Nrf2 inhibitors are not currently available for clinical use. Here, we investigated the feasibility of using quinacrine, an old antimalarial drug, as a novel Nrf2 inhibitor for treating colorectal cancer. Immunohistochemical analysis of colorectal cancer samples from 60 patients was used to assess the correlation between Nrf2 expression levels and clinicopathological features. Using data from tumors in the Cancer Genome Atlas (n=290 normal, n=295 cancer) and publicly available data sets, we validated the correlation between Nrf2 expression and poor prognosis in colorectal cancer. The effect of quinacrine on the activation of JNK1-mediated Nrf2 degradation was analyzed with co-immunoprecipitation, immunoblotting, and luciferase reporter assays. To confirm that quinacrine-mediated Nrf2 degradation caused cancer cell death, we used Nrf2 gain-of-function and loss-of-function experiments. The cytotoxicity of quinacrine against colorectal cancer cells under both normoxia (20% O2) and hypoxia (0.5% O2) was assessed by clonogenic survival assays. Finally, a xenograft mouse model was used to confirm the results of our in vitro experiments in an in vivo setting. High Nrf2 levels were correlated with increased expression of its target genes and poor survival among colorectal cancer patients in immunohistochemical analysis and analysis for publicly available data sets. The quinacrine-mediated activation of JNK1 induced Nrf2 degradation by increasing the interaction between Keap1 and Nrf2, thereby causing cancer cell death under normoxia and hypoxia and suppressing tumor growth in our in vivo model. Overexpression of Nrf2 effectively prevented quinacrine-mediated Nrf2 degradation and cancer cell death regardless of oxygen tension. Additionally, siRNA-mediated JNK1 knockdown inhibited quinacrine-mediated Nrf2 degradation. Luciferase reporter assays and qPCR revealed that quinacrine inhibited Nrf2-mediated transcription in cancer cells under normoxia and hypoxia. Finally, the quinacrine-mediated degradation of Nrf2 was found to increase the sensitivity of colorectal cancer in in vivo model and cancer cells under both normoxia and hypoxia in vitro to ROS-inducing drugs and anticancer drugs commonly used against colorectal cancer. Quinacrine caused colorectal cancer cell death by promoting activation of JNK1-mediated Nrf2 degradation. Citation Format: Eun-Taex Oh, Chan-Woo Kim, Ha Gyeong Kim, In-Seon Lee, Chae Won Lee, Heon Joo Park. Quinacrine-mediated activation of JNK1 inhibits Nrf2 and causes cell death in human colon cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 2675.

Abstract 4850: The minor groove binding agent quinacrine inhibits growth and increases apoptotic death in diffuse intrinsic pontine glioma tumor cells

Abstract Diffuse intrinsic pontine glioma (DIPG) is an invasive, incurable and aggressive pediatric brain tumor found in the brainstem. Improved understanding of the biology of DIPG tumors is urgently needed to develop novel treatments. Our previous studies have shown that DIPG tumors and cell lines express high levels of the DNA-binding stem cell factor high mobility group AT-hook 2 (HMGA2).. Targeting HMGA2 using lentiviral shRNA decreased DIPG cell invasion, proliferation and increased apoptosis in our studies. We hypothesized that inhibiting HMGA2 using DNA minor groove binding drugs like quinacrine would decrease DIPG proliferation and increase apoptotic cell death. We used three DIPG cell lines (JHHDIPG1, JHHDIPG16A, and SUDIPG13) to test the effect of quinacrine. Quinacrine has traditionally been used as an anti-malarial drug and is known to strongly bind to DNA. We used BrdU incorporation as a measure of proliferation and expression of cleaved caspase-3 (CC-3) as a measure of apoptosis. Treatment of DIPG cells with quinacrine showed a dose dependent increase in cell death (CC-3 expression) from 3uM to 20uM, with the most effective doses being from 3uM to 5uM. In all three DIPG cell lines, treatment with 1uM to 5uM quinacrine showed a significant reduction in cell proliferation (BrdU) from 3uM to 5uM compared to vehicle-treated cells (P&amp;lt;0.0001). Additionally, treatment of DIPG cell lines with 1uM to 5uM quinacrine showed a significant increase in apoptotic cell death (CC-3 expression) compared to vehicle control cells from 3uM to 5uM (P&amp;lt;0.001). Our data suggests that minor groove binding agents like quinacrine could be effective therapies for this lethal brain tumor. Our future studies are aimed at testing the efficacy of quinacrine in inhibiting DIPG tumorigenicity and elucidating the mechanism of action. Citation Format: Huizi Guo, Harpreet Kaur, Sepehr Akhtarkhavari, Charles G. Eberhart, Eric H. Raabe. The minor groove binding agent quinacrine inhibits growth and increases apoptotic death in diffuse intrinsic pontine glioma tumor cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 4850.

Quinacrine in endometrial cancer: Repurposing an old antimalarial drug

ObjectiveGenerate preclinical data on the effect of quinacrine (QC) in inhibiting tumorigenesis in endometrial cancer (EC) in vitro and explore its role as an adjunct to standard chemotherapy in an EC mouse model. MethodsFive different EC cell lines (Ishikawa, Hec-1B, KLE, ARK-2, and SPEC-2) representing different histologies, grades of EC, sensitivity to cisplatin and p53 status were used for the in vitro studies. MTT and colony formation assays were used to examine QC's ability to inhibit cell viability in vitro. The Chou-Talalay methodology was used to examine synergism between QC and cisplatin, carboplatin or paclitaxel. A cisplatin-resistant EC subcutaneous mouse model (Hec-1B) was used to examine QC's role as maintenance therapy. ResultsQC exhibited strong synergism in vitro when combined with cisplatin, carboplatin or paclitaxel with the highest level of synergism in the most chemo-resistant cell line. Neither QC monotherapy nor carboplatin/paclitaxel significantly delayed tumor growth in xenografts. Combination treatment (QC plus carboplatin/paclitaxel) significantly augmented the antiproliferative ability of these agents and was associated with a 14-week survival prolongation compared to carboplatin/paclitaxel. Maintenance with QC resulted in further delay in tumor progression and survival prolongation compared to carboplatin/paclitaxel. QC was not associated with weight loss and the yellow skin discoloration noted during treatment was reversible upon discontinuation. ConclusionsQC exhibited significant antitumor activity against EC in vitro and was successful as maintenance therapy in chemo-resistant EC mouse xenografts. This preclinical data suggest that QC may be an important adjunct to standard chemotherapy for patients with chemo-resistant EC.

Abstract 3486: Synergistic effect of quinacrine in combination with decitabine for the treatment of acute myeloid leukemia cells in vitro: implication for treatment of AML in the elderly

Abstract Demethylating agents remain one of the few options for treatment of AML in the elderly; however, the response rate is limited. In searching for p53 pathway activating agents for cancer therapy, we found that quinacrine is a potent p53 stimulator and induces tumor cell death. Quinacrine also induces expression of Death Receptor 5 (DR5), reduces expression of anti-apoptotic Mcl-1, and suppresses NFkB activity in tumor cells. Because of its acceptable toxicity profile, history of use in humans, and relevance of the target pathways modulated by quinacrine we explored whether it may serve as a potent anti-leukemia drug as most leukemia cells carry a wild-type p53. We tested the cytotoxic effects of quinacrine on malignant hematopoietic cell lines derived from patients with myeloid leukemia, including HL-60, MOLM-13, and MV4-11. We found that quinacrine induces massive cell death in the cell lines tested, at concentrations from as less as 1 microM to 5 microM, 2-10 times lower than required to induce solid tumor cell death. Most interestingly, quinacrine facilitates cell death in decitabine pre-treated leukemia cells in a synergistic manner. Further mechanistic studies showed that quinacrine stabilizes p53, induces Mcl-1 degradation, and PARP cleavage in treated cells. Our work supports translational efforts to advance the use of quinacrine from the bench to the clinic and provides a preliminary rationale for its combination with decitabine for the treatment of AML. Citation Format: Wenge Wang, David T. Dicker, David F. Claxton, Hong-Gang Wang, Wafik S. El-Deiry. Synergistic effect of quinacrine in combination with decitabine for the treatment of acute myeloid leukemia cells in vitro: implication for treatment of AML in the elderly. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 3486. doi:10.1158/1538-7445.AM2015-3486

The effects of quinacrine, proglumide, and pentoxifylline on seizure activity, cognitive deficit, and oxidative stress in rat lithium-pilocarpine model of status epilepticus.

The present data indicate that status epilepticus (SE) induced in adult rats is associated with cognitive dysfunctions and cerebral oxidative stress (OS). This has been demonstrated using lithium-pilocarpine (Li-Pc) model of SE. OS occurring in hippocampus and striatum of mature brain following SE is apparently due to both the increased free radicals production and the limited antioxidant defense. Pronounced alterations were noticed in the enzymatic, glutathione-S transferase (GST), catalase (CAT), and superoxide dismutase (SOD), as well as in the nonenzymatic; thiobarbituric acid (TBARS) and reduced glutathione (GST), indices of OS in the hippocampus and striatum of SE induced animals. Quinacrine (Qcn), proglumide (Pgm), and pentoxifylline (Ptx) administered to animals before inducing SE, were significantly effective in ameliorating the seizure activities, cognitive dysfunctions, and cerebral OS. The findings suggest that all the drugs were effective in the order of Ptx < Pgm < Qcn indicating that these drugs are potentially antiepileptic as well as antioxidant; however, further studies are needed to establish this fact. It can be assumed that these antiepileptic substances with antioxidant properties combined with conventional therapies might provide a beneficial effect in treatment of epilepsy through ameliorating the cerebral OS.

Abstract 608: Quinacrine and sorafenib as potential combination for anaplastic thyroid carcinoma.

Abstract Anaplastic thyroid cancer (ATC) comprises ∼2% of all thyroid cancers and its median survival rate remains poor. ATC is frequently resistant to conventional therapy and therefore it is essential to expand the number of treatment options for ATC. Proto-oncogenes RET, RAS and BRAF are some of the best targets described in thyroid cancer. Sorafenib is a small molecule multi-kinase inhibitor that inhibits RAF, MEK and ERK kinases among other targets and is therefore being evaluated in several phase II/III clinical trials in thyroid cancer. Quinacrine, a potent small molecule inhibitor of NFKB signaling, is currently being evaluated in phase II clinical trials. We have previously shown the effectiveness of quinacrine in combination with cytotoxic drugs in hepatocellular and colon carcinoma cells acts by inhibiting NFKB, Mcl-1, and angiogenesis in tumor cell lines that are deficient in p53. Here, we evaluate the efficacy of quinacrine in combination with sorafenib on a panel of human ATC cells. Quinacrine as a single agent effectively inhibits growth and promote apoptosis of ATC cells in vitro in a dose-dependent manner as assessed by CellTiter-Glo and sub-G1 analysis respectively. Combinatorial dose-response modulation of quinacrine with sorafenib suggests a synergistic drug-drug interaction with respect to growth stasis of ATC cells in vitro, as defined by Chou-Talalay. Western blot analysis suggest that the anti-apoptotic Bcl-2 family member Mcl-1, over-expressed in a number of solid tumors, is efficiently down-regulated in the ATC cell line 8505C by the combination of quinacrine and sorafenib. We also observe that the active form of transcription factor Stat3 is down-regulated by both quinacrine and sorafenib. In contrast to chloroquine that inhibits autophagy, our previous results have not shown that quinacrine's anti-tumor efficacy involves alterations in autophagy. Furthermore, sorafenib and quinacrine significantly improve survival in a mouse thyroid orthotopic in vivo xenograft model of ATC. We are currently exploring the detailed molecular mechanism of the quinacrine and sorafenib drug synergy and associated anti-tumor activity in vitro and in vivo. In addition, we are exploring the possibility of performing in vivo assays of the therapy combination with clinical samples. Our findings suggest that quinacrine in combination with sorafenib may be a novel and potentially cost effective therapeutic strategy for the treatment ATC. Citation Format: Junaid Abdulghani, Jean-Nicolas Gallant, Tiffany Whitcomb, David Dicker, David Goldenberg, Charles D. Smith, Niklas Finnberg, Wafik S. El-Deiry. Quinacrine and sorafenib as potential combination for anaplastic thyroid carcinoma. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 608. doi:10.1158/1538-7445.AM2013-608

Abstract 3722: Quinacrine and sorafenib combination as potential therapy for anaplastic thyroid cancer

Abstract Anaplastic thyroid cancer (ATC) is uncommon and represents 2-5% of all thyroid cancers. It remains amongst the most lethal human cancers with a reported median survival of 6 months despite therapy. ATC represents over 50% of all thyroid cancer fatalities annually. We have previously shown the effectiveness of quinacrine in combination with standard therapies in hepatocellular and colon carcinoma. Quinacrine has been used in the past to treat lupus and malaria and in addition to being available and affordable (∼30 USD/month of therapy) it has a well-known and acceptable toxicity profile. Here, we evaluate the efficacy of quinacrine in combination with sorafenib on a panel of human anaplastic thyroid cancer tumor cells. We observed that quinacrine as a single agent effectively kills anaplastic thyroid cancer cells in vitro in a concentration-dependent manner as assessed by CellTiter-Glo and sub-G1 analysis. Quinacrine in combination with sorafenib provides an additive effect in vitro. On analyzing, we observe that the anti-apoptotic Bcl-2 family member Mcl-1, which is over-expressed in a number of solid tumors is down-regulated with this combination treatment. Unlike chloroquine that inhibits autophagy, our previous results have not shown that quinacrine's anti-tumor efficacy involves alterations in autophagy. We are testing the quinacrine plus sorafenib combination in vivo by sub-cutaneous or orthotopic injection in immune-deficient mice of established cell lines as well as freshly isolated cells from patients with anaplastic thyroid cancer. Our findings suggest that quinacrine in combination with sorafenib may be an effective therapeutic strategy for anaplastic thyroid cancer. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 3722. doi:1538-7445.AM2012-3722

Quinacrine sensitizes hepatocellular carcinoma cells to TRAIL and chemotherapeutic agents

Quinacrine has been widely explored in treatment of malaria, giardiasis, and rheumatic diseases. We find that quinacrine stabilizes p53 and induces p53-dependent and independent cell death. Treatment by quinacrine alone at concentrations of 10–20 mM for 1–2 d cannot kill hepatocellular carcinoma cells, such as HepG2, Hep3B, Huh7, which are also resistant to TRAIL. However, quinacrine renders these cells sensitive to treatment by TRAIL. Co-treatment of these cells with quinacrine and TRAIL induces overwhelming cell death within 3–4 h. Levels of DR5, a pro-apoptotic death receptor of TRAIL, are increased upon treatment with quinacrine, while levels of Mcl-1, an anti-apoptotic member of the Bcl-2 family, are decreased. While the synergistic effect of quinacrine with TRAIL appears to be in part independent of p53, knockdown of p53 in HepG2 cells by siRNA results in more cell death after treatment by quinacrine and TRAIL. The mechanism by which quinacrine sensitizes hepatocellular carcinoma cells to TRAIL and chemotherapies, and the potential for clinical application currently are being further explored. Lastly, quinacrine synergizes with chemotherapeutics, such as adriamycin, 5-FU, etoposide, CPT11, sorafenib, and gemcitabine, in killing hepatocellular carcinoma cells in vitro and the drug enhances the activity of sorafenib to delay tumor growth in vivo.

Mechanisms for Kir channel inhibition by quinacrine: acute pore block of Kir2.x channels and interference in PIP2 interaction with Kir2.x and Kir6.2 channels

Cardiac inward rectifier potassium currents determine the resting membrane potential and contribute repolarization capacity during phase 3 repolarization. Quinacrine is a cationic amphiphilic drug. In this work, the effects of quinacrine were studied on cardiac Kir channels expressed in HEK 293 cells and on the inward rectifier potassium currents, I(K1) and I(KATP), in cardiac myocytes. We found that quinacrine differentially inhibited Kir channels, Kir6.2 ∼ Kir2.3 > Kir2.1. In addition, we found in cardiac myocytes that quinacrine inhibited I(KATP) > I(K1). We presented evidence that quinacrine displays a double action towards strong inward rectifier Kir2.x channels, i.e., direct pore block and interference in phosphatidylinositol 4,5-bisphosphate, PIP(2)-Kir channel interaction. Pore block is evident in Kir2.1 and 2.3 channels as rapid block; channel block involves residues E224 and E299 facing the cytoplasmic pore of Kir2.1. The interference of the drug with the interaction of Kir2.x and Kir6.2/SUR2A channels and PIP(2) is suggested from four sources of evidence: (1) Slow onset of current block when quinacrine is applied from either the inside or the outside of the channel. (2) Mutation of Kir2.3(I213L) and mutation of Kir6.2(C166S) increase their affinity for PIP(2) and lowers its sensitivity for quinacrine. (3) Mutations of Kir2.1(L222I and K182Q) which decreased its affinity for PIP(2) increased its sensitivity for quinacrine. (4) Co-application of quinacrine with PIP(2) lowers quinacrine-mediated current inhibition. In conclusion, our data demonstrate how an old drug provides insight into a dual a blocking mechanism of Kir carried inward rectifier channels.

Using molecular beacon to monitor activity of E. coli DNA ligase

NAD(+)-dependent DNA ligase has been widely used in gene diagnostics for disease-associated mutation detection and has proved to be necessary for screening bactericidal drugs targeted to DNA ligases. However, further research has been restricted since conventional ligase assay technology is limited to gel electrophoresis, which is discontinuous, time-consuming and laborious. An innovative approach is developed for monitoring the activity of E. coli DNA ligase catalyzing nucleic acid ligation in the report. This approach utilizes a molecular beacon hybridized with two single-stranded DNA (ssDNA) segments to be ligated to form a hybrid with a nick, and could therefore be recognized by the enzyme. Ligation of the two ssDNA segments would cause conformation changes of the molecular beacon, leading to significant fluorescence enhancement. Compared to gel electrophoresis, this approach can provide real time information about ligase, is more time efficient, and is easier to use. The effect of quinacrine, a drug for malaria, on the activity of the ligase is detected, thereby certifying the capability of the method for developing novel antibacterial drugs targeted at NAD(+)-dependent ligase. The fidelity of strand joining by the ligase is examined based on this approach. The effects of external factors on activity of the ligase are analyzed, and then an assay of E. coli DNA ligase is performed with a broad linear range of 4.0 x 10(-4) Weiss Unit mL(-1) to 0.4 Weiss Unit mL(-1) and the detection limit of 4.0 x 10(-4) Weiss Unit mL(-1).

Effects of two-vessel forebrain ischemia and of administration of indomethacin and quinacrine on Na+, K+-ATPase activity in various rat brain areas

The effect of a two-vessel forebrain ischemia (induced by occlusion of carotid arteries and hypotension), subsequent reperfusion, and administration of indomethacin and quinacrine on the Na+,K+-ATPase activity and diene conjugate content was studied in various rat forebrain fields. The most pronounced metabolic alterations were observed during ischemia and reperfusion. Under these effects, there was a statistically significant reduction of the Na+,K+-ATPase activity in the brain cortex and striatum and an increase of the diene conjugate content in the rat brain cortex in comparison with sham-operated animals. Injection of indomethacin, a cyclooxygenase inhibitor, to rats subjected to ischemia and reperfusion, resulted to a statistically significant increase of the Na+,K+-ATPase activity in the brain cortex, hippocampus, and striatum (p < 0.02) as compared with control animals. The diene conjugate content in the rat brain cortex during brain ischemia and reperfusion was statistically significantly lower in the rats injected with indomethacin. The effect of quinacrine (a blocker of phospholipase A2) was similar to that of indomethacin in the rat cortex, whereas in the rat striatum and hippocampus, the quinacrine effect during ischemia and reperfusion was less marked than that of indomethacin. The obtained data indicate the ability of inhibitors of the arachidonic pathway of free radical formation to normalize the Na+, K+-ATPase activity during brain ischemia. There also revealed local peculiarities of metabolic disturbances in different regions of the rat forebrain during ischemia and reperfusion.

Non-glycosylphosphatidylinositol (GPI)-anchored recombinant prion protein with dominant-negative mutation inhibits PrPSc replication in vitro

Dominant-negative mouse prion protein (PrP) with a lysine mutation at codon 218 (Q218K) is known to inhibit prion replication. In order to gain further mechanistic insight into such dominant negative inhibition, non-glycosylphosphatidylinositol (GPI)-anchored recombinant PrP with Q218K (rPrP-Q218K) was investigated. When applied into scrapie-infected mouse neuroblastoma (ScN2a) cells, rPrP-Q218K but not wild-type rPrP (rPrP-WT) exclusively inhibited abnormal protease-resistant pathogenic isoform (PrPSc) replication without reducing the viability of the cells. It was even more efficient than quinacrine, which has already been prescribed for sporadic Creutzfeldt-Jakob disease (CJD) patients; 50% effective concentration (EC50) = 0.20 μM, 99% effective concentration (EC99) = 0.86 μM vs. EC50 = 0.45 μM, EC99 = 1.5 μM. Besides, no apparent cell damage was observed at the concentration of up to 4.3 μM (100 μg/ml). In combination treatment with 0.43 μM (10 μg/ml) of rPrP-Q218K, EC99 of quinacrine was decreased from 1.5 μM to 0.5 μM, and the cell viability was recovered from 50% to over 90% as inversely proportional to the concentration of quinacrine. Such combination could alleviate the side effects of quinacrine by reducing its effective concentration without changing or even acceleration the inhibition efficacy. Since homogeneous, high-quality rPrPs could be easily prepared from Escherichia coli in large quantities, rPrP-Q218K is a good candidate for a prion replication antagonist.

Effect of quinacrine treatment on the activity of acid hydrolases (phosphatase, N-acetyl-beta-glucosaminidase, glucosidase, galactosidase and esterase) in Tetrahymena.

The effect of phospholipase A2 (PLA2) inhibitor, quinacrine, on the activity of hydrolytic enzymes in Tetrahymena pyriformis homogenate, was investigated. The activity of all of the enzymes studied (acid phosphatase, N-acetyl-beta-glusosaminidase, glucosidase, galactosidase and esterase) was significantly reduced in the presence of quinacrine. Since there are no data on the inhibitory effect of PLA2 and PLA2 influenced metabolic pathways to the hydrolytic enzymes, the direct effect of quinacrine on the hydrolytic enzymes (of Tetrahymena) can be supposed. This is supported by the fact that the other PLA2 inhibitor, 4-bromophenacyl bromide, did not influence phosphatase activity.

Effects of quinacrine on endothelial cell morphology and transcription factor–DNA interactions

Quinacrine has been used for decades and the beneficial effects of this drug are as numerous as its toxic effects. Since endothelial cells (EC) are in many cases the first cells coming in contact with drugs, the effect of quinacrine on certain aspects of EC biology were studied. The presented data demonstrate that quinacrine can have a marked impact on the integrity on EC monolayer without grossly interfering with cell viability. The described impact of quinacrine on EC might explain, at least in part, the toxic effects of this drug observed in the past. Furthermore, quinacrine profoundly effects gene regulation in EC. Quinacrine binds to DNA in a sequence-specific manner. While NF-κB–DNA interactions are not effected, AP-1–DNA binding is blocked by quinacrine. Such differential effects are presumably due to intercalation of quinacrine into the AP-1 consensus element. Preincubation of oligonucleotides resembling this sequence blocked the subsequent binding of nuclear extract containing AP-1 protein(s). Taken together, these data suggest that quinacrine interferes with EC physiology and alters the repertoire of EC to respond to stimuli. Furthermore, the differential effects of quinacrine might be exploited to study and gain additional insight in the involvement of AP-1 and NF-κB in gene regulation.

The Effect of Quinacrine on Oxidative Stress in Kidney Tissue Stored at Low Temperature after Warm Ischemic Injury

Rabbit kidney cortex tissue slices were made ischemic (37°C) for 60 min and then either reperfused in warm (37°C) oxygenated physiologic buffer for 210 min or placed in UW Na gluconate solution (± quinacrine; 100 μmol/L) for 18 h followed by warm aerobic reperfusion. Slices were sampled at intervals and analyzed for malondialdehyde (MDA) content by HPLC. Control (nonischemic) slices had no change in MDA content over the duration of the experiment. Hypothermic storage of nonischemic slices did not result in any increase in MDA during reperfusion. Ischemic slices showed significant increases in MDA content during the first 1.5 h of reperfusion and remained elevated for the remainder of the experiment. Hypothermic storage of warm ischemic kidney slices resulted in a significant decrease in MDA content during the storage period. However, MDA content in these slices increased during warm reperfusion and was significantly higher than that in nonischemic controls. Quinacrine added during hypothermic storage of warm ischemic slices significantly decreased slice MDA content during warm reperfusion, an effect which was lost by increasing the storage solution calcium content. This study shows that aerobic hypothermic storage can aid in reducing oxidative stress in warm ischemic kidney tissue during reperfusion. This study suggests that the effects of quinacrine are at the level of the mitochondrion and not as an antioxidant compound.

Phospholipase A2 mediates nitric oxide production by alveolar macrophages and acute lung injury in pancreatitis.

Reportedly, nitric oxide (NO) derived from alveolar macrophages (AMs) and increased serum phospholipase A2 (PLA2) activity are associated with the pathogenesis of lung injury in acute pancreatitis. The authors examined the possibility that PLA2 causes, in part, the induction of NO production by AMs in pancreatitis. Pancreatitis was induced in rats by selective pancreatic duct ligation (SPL). AMs were stimulated with PLA2 or SPL rat serum, with or without administration of the PLA2 inhibitor quinacrine. Then NO production from the AMs was measured by the Griess method, inducible NO synthase mRNA expression of AMs was analyzed by the reverse transcription-polymerase chain reaction, and cytotoxic effects of AMs on human umbilical vein endothelial cells was examined by a 51Cr release assay. In vivo, the effect of quinacrine on lung injury was determined by measuring the arterial blood oxygen pressure (PaO2), lung weight, and lung permeability using Evans blue dye concentration of SPL rat. In vitro, the serum with high PLA2 activity induced NO production by rat AMs. PLA2 (50 ng/ml) induced significant amounts of NO production, inducible NO synthase mRNA expression, and cytotoxicity toward the human umbilical vein endothelial cells in normal rat AMs, and these activities were significantly inhibited by quinacrine. In vivo, rats with pancreatitis that were given quinacrine showed decreased concentrations of NO2- and NO3- in the bronchoalveolar lavage fluid, and the PaO2, lung edema, and lung permeability were improved significantly. PLA2 induces AMs to release NO, which contributes to lung injury in acute pancreatitis. This lung injury was prevented by the administration of the PLA2 inhibitor quinacrine.

Effect of quinacrine, a phospholipase A2 inhibitor on stress and chemically induced gastroduodenal ulcers.

Quinacrine, a phospholipase A2 inhibitor, has been studied for its ability to inhibit gastric secretion and to protect the gastric and duodenal mucosa against chemically and stress-induced ulcers. Acid secretion studies were undertaken in pylorus-ligated rats with and without quinacrine treatment. Experimental gastric lesions were induced by water-immersion restraint stress, indomethacin and 80% ethanol in rats; whereas duodenal ulcers were produced by treatment of rats with cysteamine. The level of nonprotein sulfhydryl compounds and gastric wall mucus were also measured in the glandular stomach of the rats following ethanol-induced gastric lesions. The results of this study demonstrate that quinacrine produces a dose-dependent inhibition of gastric acid secretion in rats. Pretreatment with quinacrine significantly attenuated the formation of stress-, indomethacin- and ethanol-induced gastric lesions. Quinacrine also protected intestinal mucosa against cysteamine-induced duodenal ulcers. The antiulcer activity of quinacrine was associated with appreciable inhibition of ethanol-induced depletion of nonprotein sulfhydryls and gastric wall mucus. These findings point towards the mediation of sulfhydryls in quinacrine-induced gastrointestinal cytoprotection. In conclusion, this study demonstrates that quinacrine possesses significant antiulcer and cytoprotective activity against various experimentally induced gastroduodenal lesions. Although the mechanism of action of quinacrine requires further evaluation, the experimental observations derived from this study may have future clinical relevance and therefore deserve to be investigated thoroughly.