Time-dependent effects of hydrophobic amine-containing drugs on lysosome structure and biogenesis in cultured human fibroblasts

Quantitative Raman chemical imaging of intracellular drug-membrane aggregates and small molecule drug precipitates in cytoplasmic organelles

Raman confocal microscopes have been used to visualize the distribution of small molecule drugs within different subcellular compartments. This visualization allows the discovery, characterization, and detailed analysis of the molecular transport phenomena underpinning the Volume of Distribution - a key parameter governing the systemic pharmacokinetics of small molecule drugs. In the specific case of lipophilic small molecules with large Volumes of Distribution, chemical imaging studies using Raman confocal microscopes have revealed how weakly basic, poorly soluble drug molecules can accumulate inside cells by forming stable, supramolecular complexes in association with cytoplasmic membranes or by precipitating out within organelles. To study the self-assembly and function of the resulting intracellular drug inclusions, Raman chemical imaging methods have been developed to measure and map the mass, concentration, and ionization state of drug molecules at a microscopic, subcellular level. Beyond the field of drug delivery, Raman chemical imaging techniques relevant to the study of microscopic drug precipitates and drug-lipid complexes which form inside cells are also being developed by researchers with seemingly unrelated scientific interests. Highlighting advances in data acquisition, calibration methods, and computational data management and analysis tools, this review will cover a decade of technological developments that enable the conversion of spectral signals obtained from Raman confocal microscopes into new discoveries and information about previously unknown, concentrative drug transport pathways driven by soluble-to-insoluble phase transitions occurring within the cytoplasmic organelles of eukaryotic cells.

Increasing brain glucose metabolism by ligustrazine piperazine ameliorates cognitive deficits through PPARγ-dependent enhancement of mitophagy in APP/PS1 mice

PPARγ agonists have been proven to be neuroprotective in vitro and in vivo models of Alzheimer's disease (AD). In the present study, we identified ligustrazine piperazine derivative (LPD) as a novel PPARγ agonist, which was detected by a dual-luciferase reporter assay system. LPD treatment dose-dependently reduced Aβ40 and Aβ42 levels in PC12 cells stably transfected with APP695swe and PSEN1dE9. Intragastric administration of LPD for 3 months dose-dependently reversed cognitive deficits in APP/PS1 mice. LPD treatment substantially decreased hippocampal Aβ plaques in APP/PS1 mice and decreased the levels of Aβ40 and Aβ42 in vivo and in vitro. Moreover, LPD treatment induced mitophagy in vivo and in vitro and increased brain ¹⁸F-FDG uptake in APP/PS1 mice. LPD treatment significantly increased OCR, ATP production, maximal respiration, spare respiratory capacity, and basal respiration in APP/PS1 cells. Mechanistically, LPD treatment upregulated PPARγ, PINK1, and the phosphorylation of Parkin (Ser65) and increased the LC3-II/LC3-I ratio but decreased SQSTM1/p62 in vivo and in vitro. Importantly, all these protective effects mediated by LPD were abolished by cotreatment with the selective PPARγ antagonist GW9662. In summary, LPD could increase brain glucose metabolism and ameliorate cognitive deficits through PPARγ-dependent enhancement of mitophagy in APP/PS1 mice.

Efficient Delivery of Antibodies Intracellularly by Co-Assembly with Hexahistidine-Metal Assemblies (HmA)

PURPOSE

There has been a substantial global market for antibodies, which are based on extracellular targets. Binding intracellular targets by antibodies will bring new chances in antibody therapeutics and a huge market increase. We aim to evaluate the efficiency of a novel delivery system of His6-metal assembly (HmA) in delivering intracellular antibodies and biofunctions of delivered antibodies.

METHODS

In this study, the physicochemical properties of HmA@Antibodies generated through co-assembling with antibodies and HmA were well characterized by dynamic light scatter. The cytotoxicity of HmA@Antibodies was investigated by Cell Counting Kit-8 (CCK-8). The endocytic kinetics and lysosome escape process of HmA@Antibodies were studied by flow cytometry and fluorescent staining imaging, respectively. Compared to the commercialized positive control, the intracellular delivery efficiency by HmA@Antibodies and biofunctions of delivered antibodies were evaluated by fluorescent imaging and CCK-8.

RESULTS

Various antibodies (IgG, anti-β-tubulin and anti-NPC) could co-assemble with HmA under a gentle condition, producing nano-sized (~150 nm) and positively charged (~+30 eV) HmA@Antibodies particles with narrow size distribution (PDI ~ 0.15). HmA displayed very low cytotoxicity to divers cells (DCs, HeLa, HCECs, and HRPE) even after 96 h for the feeding concentration ≤100 μg mL-1, and fast escape from endosomes. In the case of delivery IgG, the delivery efficiency into alive cells of HmA was better than a commercial protein delivery reagent (PULSin). For cases of the anti-β-tubulin and anti-NPC, HmA showed comparable delivery efficiency to their positive controls, but HmA with ability to deliver these antibodies into alive cells was still superior to positive controls delivering antibodies into dead cells through punching holes.

CONCLUSION

Our results indicate that this strategy is a feasible way to deliver various antibodies intracellularly while preserving their functions, which has great potential in various applications and treating many refractory diseases by intracellular antibody delivery.

Propranolol Sensitizes Vascular Sarcoma Cells to Doxorubicin by Altering Lysosomal Drug Sequestration and Drug Efflux

Angiosarcoma is a rare cancer of blood vessel-forming cells with a high patient mortality and few treatment options. Although chemotherapy often produces initial clinical responses, outcomes remain poor, largely due to the development of drug resistance. We previously identified a subset of doxorubicin-resistant cells in human angiosarcoma and canine hemangiosarcoma cell lines that exhibit high lysosomal accumulation of doxorubicin. Hydrophobic, weak base chemotherapeutics, like doxorubicin, are known to sequester within lysosomes, promoting resistance by limiting drug accessibility to cellular targets. Drug synergy between the beta adrenergic receptor (β-AR) antagonist, propranolol, and multiple chemotherapeutics has been documented in vitro, and clinical data have corroborated the increased therapeutic potential of propranolol with chemotherapy in angiosarcoma patients. Because propranolol is also a weak base and accumulates in lysosomes, we sought to determine whether propranolol enhanced doxorubicin cytotoxicity via antagonism of β-ARs or by preventing the lysosomal accumulation of doxorubicin. β-AR-like immunoreactivities were confirmed in primary tumor tissues and cell lines; receptor function was verified by monitoring downstream signaling pathways of β-ARs in response to receptor agonists and antagonists. Mechanistically, propranolol increased cytoplasmic doxorubicin concentrations in sarcoma cells by decreasing the lysosomal accumulation and cellular efflux of this chemotherapeutic agent. Equivalent concentrations of the receptor-active S-(-) and -inactive R-(+) enantiomers of propranolol produced similar effects, supporting a β-AR-independent mechanism. Long-term exposure of hemangiosarcoma cells to propranolol expanded both lysosomal size and number, yet cells remained sensitive to doxorubicin in the presence of propranolol. In contrast, removal of propranolol increased cellular resistance to doxorubicin, underscoring lysosomal doxorubicin sequestration as a key mechanism of resistance. Our results support the repurposing of the R-(+) enantiomer of propranolol with weak base chemotherapeutics to increase cytotoxicity and reduce the development of drug-resistant cell populations without the cardiovascular and other side effects associated with antagonism of β-ARs.

Uptake Study in Lysosome-Enriched Fraction: Critical Involvement of Lysosomal Trapping in Quinacrine Uptake but Not Fluorescence-Labeled Verapamil Transport at Blood-Retinal Barrier

Lysosomal trapping at the blood-retinal barrier (BRB) was investigated through quinacrine and fluorescence-labeled verapamil (EFV) uptake. Quinacrine uptake by conditionally immortalized rat retinal capillary endothelial (TR-iBRB2) cells suggested saturable and non-saturable transport processes in the inner BRB. The reduction of quinacrine uptake by bafilomycin A1 suggested quinacrine distribution to the acidic intracellular compartments of the inner BRB, and this notion was also supported in confocal microscopy. In the study using the lysosome-enriched fraction of TR-iBRB2 cells, quinacrine uptake was inhibited by bafilomycin A1, suggesting the lysosomal trapping of quinacrine in the inner BRB. Pyrilamine, clonidine, and nicotine had no effect on quinacrine uptake, suggesting the minor role of lysosomal trapping in their transport across the inner BRB. Bafilomycin A1 had no effect on EFV uptake, and lysosomal trapping driven by the acidic interior pH was suggested as a minor mechanism for EFV transport in the inner BRB. The minor contribution of lysosomal trapping was supported by the difference in inhibitory profiles between EFV and quinacrine uptakes. Similar findings were observed in the outer BRB study with the fraction of conditionally immortalized rat retinal pigment epithelial (RPE-J) cells. These results suggest the usefulness of lysosome-enriched fractions in studying lysosomal trapping at the BRB.

The Lysosomotropic Activity of Hydrophobic Weak Base Drugs is Mediated via Their Intercalation into the Lysosomal Membrane

Lipophilic weak base therapeutic agents, termed lysosomotropic drugs (LDs), undergo marked sequestration and concentration within lysosomes, hence altering lysosomal functions. This lysosomal drug entrapment has been described as luminal drug compartmentalization. Consistent with our recent finding that LDs inflict a pH-dependent membrane fluidization, we herein demonstrate that LDs undergo intercalation and concentration within lysosomal membranes. The latter was revealed experimentally and computationally by (a) confocal microscopy of fluorescent compounds and drugs within lysosomal membranes, and (b) molecular dynamics modeling of the pH-dependent membrane insertion and accumulation of an assortment of LDs, including anticancer drugs. Based on the multiple functions of the lysosome as a central nutrient sensory hub and a degradation center, we discuss the molecular mechanisms underlying the alteration of morphology and impairment of lysosomal functions as consequences of LDs’ intercalation into lysosomes. Our findings bear important implications for drug design, drug induced lysosomal damage, diseases and pertaining therapeutics.

Hexahistidine-metal assemblies: A promising drug delivery system

It is of considerable interest to construct an ideal drug delivery system (i.e., high drug payload, minimal cytotoxicity, rapid endocytosis, and lysosomal escape) under mild conditions for disease treatment, tissue engineering, bioimaging, etc. Inspired by the coordinative interactions between histidine and metal ions, we present the facile synthesis of hexahistidine (His₆)-metal assembly (HmA) particles under mild conditions for the first time. The HmA particles presented a high loading capacity, a wide variety of loadable drugs, minimal cytotoxicity, quick internalization, the ability to bypass the lysosomes, and rapid intracellular drug release. In addition, HmA encapsulation largely improved the antitumor ability of camptothecin (CPT) relative to free CPT. By capitalizing on these promising features in drug delivery, HmA will have great potential in various biomedical fields. STATEMENT OF SIGNIFICANCE: It is of considerable interest to construct an ideal drug delivery system (i.e., high drug payload, minimal cytotoxicity, rapid endocytosis, and lysosomal escape) under mild conditions. Inspired by the coordinative interactions between histidine and metal ions, we present for the first time the facile synthesis of Hexahistidine (His₆)-metal assembly (HmA) particles under mild conditions. The HmA particles exhibited a high loading capacity, a wide variety of loadable drugs, minimal cytotoxicity, quick internalization, the ability to bypass the lysosomes, and rapid intracellular drug release. By capitalizing on these promising features in drug delivery, HmA will have great potential in various biomedical fields.

An Expandable Mechanopharmaceutical Device (3): a Versatile Raman Spectral Cytometry Approach to Study the Drug Cargo Capacity of Individual Macrophages

PURPOSE

To improve cytometric phenotyping abilities and better understand cell populations with high interindividual variability, a novel Raman-based microanalysis was developed to characterize macrophages on the basis of chemical composition, specifically to measure and characterize intracellular drug distribution and phase separation in relation to endogenous cellular biomolecules.

METHODS

The microanalysis was developed for the commercially-available WiTec alpha300R confocal Raman microscope. Alveolar macrophages were isolated and incubated in the presence of pharmaceutical compounds nilotinib, chloroquine, or etravirine. A Raman data processing algorithm was specifically developed to acquire the Raman signals emitted from single-cells and calculate the signal contributions from each of the major molecular components present in cell samples.

RESULTS

Our methodology enabled analysis of the most abundant biochemicals present in typical eukaryotic cells and clearly identified "foamy" lipid-laden macrophages throughout cell populations, indicating feasibility for cellular lipid content analysis in the context of different diseases. Single-cell imaging revealed differences in intracellular distribution behavior for each drug; nilotinib underwent phase separation and self-aggregation while chloroquine and etravirine accumulated primarily via lipid partitioning.

CONCLUSIONS

This methodology establishes a versatile cytometric analysis of drug cargo loading in macrophages requiring small numbers of cells with foreseeable applications in toxicology, disease pathology, and drug discovery.

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

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

Reverse Engineering the Intracellular Self-Assembly of a Functional Mechanopharmaceutical Device

Weakly basic, poorly soluble chemical agents could be exploited as building blocks for constructing sophisticated molecular devices inside the cells of living organisms. Here, using experimental and computational approaches, we probed the relationship between the biological mechanisms mediating lysosomal ion homeostasis and the self-assembly of a weakly basic small molecule building block (clofazimine) into a functional, mechanopharmaceutical device (intracellular Crystal-Like Drug Inclusions – “CLDIs”) in macrophage lysosomes. Physicochemical considerations indicate that the intralysosomal stabilization of the self-assembled mechanopharmaceutical device depends on the pH_max of the weakly basic building block and its affinity for chloride, both of which are consistent with the pH and chloride content of a physiological lysosomal microenvironment. Most importantly, in vitro and in silico studies revealed that high expression levels of the vacuolar ATPase (V-ATPase), irrespective of the expression levels of chloride channels, are necessary and sufficient to explain the cell-type dependent formation, stabilization, and biocompatibility of the self-assembled mechanopharmaceutical device within macrophages.

Ion Trapping of Amines in Protozoa: A Novel Removal Mechanism for Micropollutants in Activated Sludge

To optimize removal of organic micropollutants from the water cycle, understanding the processes during activated sludge treatment is essential. In this study, we hypothesize that aliphatic amines, which are highly abundant among organic micropollutants, are partly removed from the water phase in activated sludge through ion trapping in protozoa. In ion trapping, which has been extensively investigated in medical research, the neutral species of amine-containing compounds diffuse through the cell membrane and further into acidic vesicles present in eukaryotic cells such as protozoa. There they become trapped because diffusion of the positively charged species formed in the acidic vesicles is strongly hindered. We tested our hypothesis with two experiments. First, we studied the distribution of the fluorescent amine acridine orange in activated sludge by confocal fluorescence imaging. We observed intense fluorescence in distinct compartments of the protozoa, but not in the bacterial biomass. Second, we investigated the distribution of 12 amine-containing and eight control micropollutants in both regular activated sludge and sludge where the protozoa had been inactivated. In contrast to most control compounds, the amine-containing micropollutants displayed a distinctly different behavior in the noninhibited sludge compared to the inhibited one: (i) more removal from the liquid phase; (ii) deviation from first-order kinetics for the removal from the liquid phase; and (iii) higher amounts in the solid phase. These results provide strong evidence that ion trapping in protozoa occurs and that it is an important removal mechanism for amine-containing micropollutants in batch experiments with activated sludge that has so far gone unnoticed. We expect that our findings will trigger further investigations on the importance of this process in full-scale wastewater treatment systems, including its relevance for accumulation of ammonium.

The physiological determinants of drug-induced lysosomal stress resistance

Many weakly basic, lipophilic drugs accumulate in lysosomes and exert complex, pleiotropic effects on organelle structure and function. Thus, modeling how perturbations of lysosomal physiology affect the maintenance of lysosomal ion homeostasis is necessary to elucidate the key factors which determine the toxicological effects of lysosomotropic agents, in a cell-type dependent manner. Accordingly, a physiologically-based mathematical modeling and simulation approach was used to explore the dynamic, multi-parameter phenomenon of lysosomal stress. With this approach, parameters that are either directly involved in lysosomal ion transportation or lysosomal morphology were transiently altered to investigate their downstream effects on lysosomal physiology reflected by the changes they induce in lysosomal pH, chloride, and membrane potential. In addition, combinations of parameters were simultaneously altered to assess which parameter was most critical for recovery of normal lysosomal physiology. Lastly, to explore the relationship between organelle morphology and induced stress, we investigated the effects of parameters controlling organelle geometry on the restoration of normal lysosomal physiology following a transient perturbation. Collectively, our results indicate a key, interdependent role of V-ATPase number and membrane proton permeability in lysosomal stress tolerance. This suggests that the cell-type dependent regulation of V-ATPase subunit expression and turnover, together with the proton permeability properties of the lysosomal membrane, is critical to understand the differential sensitivity or resistance of different cell types to the toxic effects of lysosomotropic drugs.

Detecting ordered small molecule drug aggregates in live macrophages: a multi-parameter microscope image data acquisition and analysis strategy

Following prolonged administration, certain orally bioavailable but poorly soluble small molecule drugs are prone to precipitate out and form crystal-like drug inclusions (CLDIs) within the cells of living organisms. In this research, we present a quantitative multi-parameter imaging platform for measuring the fluorescence and polarization diattenuation signals of cells harboring intracellular CLDIs. To validate the imaging system, the FDA-approved drug clofazimine (CFZ) was used as a model compound. Our results demonstrated that a quantitative multi-parameter microscopy image analysis platform can be used to study drug sequestering macrophages, and to detect the formation of ordered molecular aggregates formed by poorly soluble small molecule drugs in animals.

Functional magnetic porous silica for T 1-T 2 dual-modal magnetic resonance imaging and pH-responsive drug delivery of basic drugs

A smart magnetic-targeting drug carrier γ-Fe₂O₃@p-silica comprising a γ-Fe₂O₃ core and porous shell has been prepared and characterized. The particles have a uniform size of about 60 nm, and a porous shell of thickness 3 nm. Abundant hydroxyl groups and a large surface area enabled the γ-Fe₂O₃@p-silica to be readily loaded with a large payload of the basic model drug rhodamine B (RB) (up to 73 mg g^-1). Cytotoxicity assays of the γ-Fe₂O₃@p-silica particles indicated that the particles were biocompatible and suitable for carrying drugs. It was found that the RB was released rapidly at pH 5.5 but at pH 7.4 the rate and extent of release was greatly attenuated. The particles therefore demonstrate an excellent pH-triggered drug release. In addition, the γ-Fe₂O₃@p-silica particles could be tracked by magnetic resonance imaging (MRI). A clear dose-dependent contrast enhancement in both T ₁-weighted and T ₂-weighted MR images indicated the potential of the γ-Fe₂O₃@p-silica particles to act as dual-mode T ₁ and T ₂ MRI contrast agents.

Clofazimine Biocrystal Accumulation in Macrophages Upregulates Interleukin 1 Receptor Antagonist Production To Induce a Systemic Anti-Inflammatory State

Clofazimine (CFZ) is a poorly soluble antibiotic and anti-inflammatory drug indicated for the treatment of leprosy. In spite of its therapeutic value, CFZ therapy is accompanied by the formation of drug biocrystals that accumulate within resident tissue macrophages, without obvious toxicological manifestations. Therefore, to specifically elucidate the off-target consequences of drug bioaccumulation in macrophages, we compared the level of inflammasome activation in CFZ-accumulating organs (spleen, liver and lung) in mice after 2 and 8 weeks of CFZ treatment when the drug exists in soluble and insoluble (biocrystalline) forms, respectively. Surprisingly, the results showed a drastic reduction in caspase 1 and interleukin-1β (IL-1β) cleavage in the livers of mice treated with CFZ for 8 weeks (8-week-CFZ-treated mice) compared to 2-week-CFZ-treated and control mice, which was accompanied by a 3-fold increase in hepatic IL-1 receptor antagonist (IL-1RA) production and a 21-fold increase in serum IL-1RA levels. In the lung and spleen, IL-1β cleavage and tumor necrosis factor alpha expression were unaffected by soluble or biocrystal CFZ forms. Functionally, there was a drastic reduction of carrageenan- and lipopolysaccharide-induced inflammation in the footpads and lungs, respectively, of 8-week-CFZ-treated mice. This immunomodulatory activity of CFZ biocrystal accumulation was attributable to the upregulation of IL-1RA, since CFZ accumulation had minimal effect in IL-1RA knockout mice or 2-week-CFZ-treated mice. In conclusion, CFZ accumulation and biocrystal formation in resident tissue macrophages profoundly altered the host's immune system and prompted an IL-1RA-dependent, systemic anti-inflammatory response.

Transcription factor EB: from master coordinator of lysosomal pathways to candidate therapeutic target in degenerative storage diseases

The lysosome is the main catabolic hub of the cell. Owing to its role in fundamental processes such as autophagy, plasma membrane repair, mTOR signaling, and maintenance of cellular homeostasis, the lysosome has a profound influence on cellular metabolism and human health. Indeed, inefficient or impaired lysosomal function has been implicated in the pathogenesis of a number of degenerative diseases affecting various organs and tissues, most notably the brain, liver, and muscle. The discovery of the coordinated lysosomal expression and regulation (CLEAR) genetic program and its master controller, transcription factor EB (TFEB), has provided an unprecedented tool to study and manipulate lysosomal function. Most lysosome-based processes-including macromolecule degradation, autophagy, lysosomal exocytosis, and proteostasis-are under the transcriptional control of TFEB. Interestingly, impaired TFEB signaling has been suggested to be a contributing factor in the pathogenesis of several degenerative storage diseases. Preclinical studies based on TFEB exogenous expression to reinstate TFEB activity or promote CLEAR network-based lysosomal enhancement have highlighted TFEB as a candidate therapeutic target for the treatment of various degenerative storage diseases.

A beta-blocker, propranolol, decreases the efficacy from enzyme replacement therapy in Pompe disease

Enzyme replacement therapy (ERT) with recombinant human acid α-glucosidase (rhGAA) fails to completely reverse muscle weakness in Pompe disease. β2-agonists enhanced ERT by increasing receptor-mediated uptake of rhGAA in skeletal muscles.

PURPOSE

To test the hypothesis that a β-blocker might reduce the efficacy of ERT, because the action of β-blockers opposes those of β2-agonists.

METHODS

Mice with Pompe disease were treated with propranolol (a β-blocker) or clenbuterol in combination with ERT, or with ERT alone.

RESULTS

Propranolol-treated mice had decreased weight gain (p<0.01), in comparison with clenbuterol-treated mice. Left ventricular mass was decreased (and comparable to wild-type) in ERT only and clenbuterol-treated groups of mice, and unchanged in propranolol-treated mice. GAA activity increased following either clenbuterol or propranolol in skeletal muscles. However, muscle glycogen was reduced only in clenbuterol-treated mice, not in propranolol-treated mice. Cell-based experiments confirmed that propranolol reduces uptake of rhGAA into Pompe fibroblasts and also demonstrated that the drug induces intracellular accumulation of glycoproteins at higher doses.

CONCLUSION

Propranolol, a commonly prescribed β-blocker, reduced weight, increased left ventricular mass and decreased glycogen clearance in skeletal muscle following ERT. β-Blockers might therefore decrease the efficacy from ERT in patients with Pompe disease.

Autophagic flux inhibition and lysosomogenesis ensuing cellular capture and retention of the cationic drug quinacrine in murine models

The proton pump vacuolar (V)-ATPase is the driving force that mediates the concentration of cationic drugs (weak bases) in the late endosome-lysosome continuum; secondary cell reactions include the protracted transformation of enlarged vacuoles into autophagosomes. We used the inherently fluorescent tertiary amine quinacrine in murine models to further assess the accumulation and signaling associated with cation trapping. Primary fibroblasts concentrate quinacrine ∼5,000-fold from their culture medium (K_M 9.8 µM; transport studies). The drug is present in perinuclear granules that are mostly positive for Rab7 and LAMP1 (microscopy). Both drug uptake and retention are extensively inhibited by treatments with the V-ATPase inhibitor bafilomycin A1. The H⁺ ionophore monensin also prevented quinacrine concentration by fibroblasts. However, inhibition of plasma membrane transporters or of the autophagic process with spautin-1 did not alter quinacrine transport parameters. Ancillary experiments did not support that low micromolar concentrations of quinacrine are substrates for organic cation transporters-1 to -3 or P-glycoprotein. The secondary autophagy induced by quinacrine in cells may derive from the accumulation of incompetent autophagolysosomes, as judged from the accumulation of p62/SQSTM1 and LC3 II (immunoblots). Accordingly, protracted lysosomogenesis is evidenced by increased expression of LAMP1 and LAMP2 in quinacrine-treated fibroblasts (48 h, immunoblots), a response that follows the nuclear translocation of the lysosomal genesis transcription factor TFEB and upregulation of LAMP1 and −2 mRNAs (24 h). Quinacrine administration to live mice evidenced variable distribution to various organs and heterogeneous accumulation within the lung (stereo-microscopy, extraction). Dose-dependent in vivo autophagic and lysosomal accumulation was observed in the lung (immunoblots). No evidence has been found for transport or extrusion mechanisms modulating the cellular uptake of micromolar quinacrine at the plasma membrane level. As shown in vitro and in vivo, V-ATPase-mediated cation sequestration is associated, above a certain threshold, to autophagic flux inhibition and feed-back lysosomogenesis.