Imatinib disturbs lysosomal function and morphology and impairs the activity of mTORC1 in human hepatocyte cell lines

Molecular glue meets antibody: next-generation antibody-drug conjugates

Antibody-drug conjugates (ADCs) have revolutionized oncology by enabling the delivery of cytotoxic agents. However, persistent limitations in payload diversity and emerging drug-resistance mechanisms have spurred investigations into innovative payload modalities. Molecular glue-antibody conjugates (MACs), which utilize molecular glues as payloads, represent a groundbreaking advance in this field. By leveraging the catalytic, event-driven nature of molecular glues, MACs offer enhanced efficacy, reduced off-target effects, and an improved therapeutic index. Two MACs are now in clinical trials. This review explores MAC mechanisms, advances, and potential to surpass traditional ADCs and molecular glues, while addressing development challenges and future directions.

Imatinib@glycymicelles entrapped in hydrogel: preparation, characterization, and therapeutic effect on corneal alkali burn in mice

Imatinib (IMB) is a type of tyrosine kinase inhibitor with great application potential for inhibiting corneal neovascularization (CNV), but its poor water solubility limits its application in eye disease treatment. In this study, novel IMB@glycymicelles entrapped in hydrogel (called IMB@glycymicelle-hydrogel) were prepared, characterized, and evaluated for their therapeutic effects on corneal alkali burn in mice. Imatinib could be successfully loaded in glycymicelles using glycyrrhizin as a nanocarrier with an optimized weight ratio of IMB:nanocarrier. The apparent solubility of IMB was significantly improved from 61.69 ± 5.55 μg/mL to bare IMB to 359,967.62 ± 20,059.42 μg/mL to IMB@glycymicelles. Then, the IMB@glycymicelles were entrapped in hydrogel fabricated with hydroxypropyl methylcellulose and sodium hyaluronate (HA) to prolong retention time on the ocular surface. Rabbit eye tolerance tests showed that IMB@glycymicelle-hydrogel possessed good ocular safety profiles. In a mouse model of corneal alkali burns, the topical administration of IMB@glycymicelle-hydrogel showed strong efficacy by prompting corneal wound healing, recovering corneal sensitivity, relieving corneal opacities, and inhibiting CNV, and these efficacy evaluation parameters were better than those of the positive drug HA. Overall, these results demonstrated that IMB@glycymicelle-hydrogel may be a promising candidate for the effective treatment of alkali ocular damage.

The tyrosine kinase inhibitor Nintedanib induces lysosomal dysfunctionality: Role of protonation-dependent crystallization processes

Nintedanib (NIN), a multi-tyrosine kinase inhibitor clinically approved for idiopathic pulmonary fibrosis and lung cancer, is characterized by protonation-dependent lysosomotropic behavior and appearance of lysosome-specific fluorescence emission properties. Here we investigate whether spontaneous formation of a so far unknown NIN matter within the acidic cell compartment is underlying these unexpected emissive properties and investigate the consequences on lysosome functionality. Lysosomes of cells treated with NIN, but not non-protonatable NIN derivatives, exhibited lysosome-associated birefringence signals co-localizing with the NIN-derived fluorescence emission. Sensitivity of both parameters towards vATPase inhibitors confirmed pH-dependent, spontaneous adoption of novel crystalline NIN structures in lysosomes. Accordingly, NIN crystallization from buffer solutions resulted in formation of multiple crystal polymorphs with pH-dependent fluorescence properties. Cell-free crystals grown at lysosomal-like pH conditions resembled NIN-treated cell lysosomes concerning fluorescence pattern, photobleaching dynamics, and Raman spectra. However, differences in birefringence intensity and FAIM-determined anisotropy, as well as predominant association with (intra)lysosomal membrane structures, suggested formation of a semi-solid NIN crystalline matter in acidic lysosomes. Despite comparable target kinase inhibition, NIN, but not its non-protonatable derivatives, impaired lysosomal functionality, mediated massive cell vacuolization, enhanced autophagy, deregulated lipid metabolism, and induced atypical phospholipidosis. Moreover, NIN exerted distinct phototoxicity, strictly dependent on lysosomal microcrystallization events. The spontaneous formation of NIN crystalline structures was also observable in the gut mucosa of orally NIN-treated mice. Summarizing, the here-described kinase inhibition-independent impact of NIN on lysosomal functionality mediates several of its cell biological activities and might contribute to NIN adverse effects.

Polymeric nanoparticles produced by electrohydrodynamic atomisation for the passive delivery of imatinib

Imatinib is a chemotherapeutic agent known to cause severe side effects when administrated systemically. Encapsulating imatinib in co-polymer poly(lactic-co-glycolic acid) (PLGA) nanoparticles (NPs) offers a targeted drug delivery. In this work, PLGA 50:50 and PLGA 75:25 NPs encapsulated imatinib using the electrohydrodynamic atomisation technique. All particles generated were spherical with a smooth surface with a size distribution of 455±115 nm (PLGA 50:50) and 363±147 nm (PLGA 75:25). Encapsulation of imatinib was shown to be higher than 75 % and was shown to increase the zeta potential of the loaded NPs. The release of imatinib showed an initial burst in the first 12 h, followed by different sustained releases with up to 70 %. Both types of imatinib-loaded NPs' effect on cell viability and their cellular uptake were also studied on A549 cells, and the antiproliferative effect was comparable to that of cells treated with free drugs. Finally, Rhodamine-B-loaded NP-treated cells demonstrated the cellular uptake of NPs.

Is Autophagy Targeting a Valid Adjuvant Strategy in Conjunction with Tyrosine Kinase Inhibitors?

Tyrosine kinase inhibitors (TKIs) represent a relatively large class of small-molecule inhibitors that compete with ATP for the catalytic binding site of tyrosine kinase proteins. While TKIs have demonstrated effectiveness in the treatment of multiple malignancies, including chronic myelogenous leukemia, gastrointestinal tumors, non-small cell lung cancers, and HER2-overexpressing breast cancers, as is almost always the case with anti-neoplastic agents, the development of resistance often imposes a limit on drug efficacy. One common survival response utilized by tumor cells to ensure their survival in response to different stressors, including anti-neoplastic drugs, is that of autophagy. The autophagic machinery in response to TKIs in multiple tumor models has largely been shown to be cytoprotective in nature, although there are a number of cases where autophagy has demonstrated a cytotoxic function. In this review, we provide an overview of the literature examining the role that autophagy plays in response to TKIs in different preclinical tumor model systems in an effort to determine whether autophagy suppression or modulation could be an effective adjuvant strategy to increase efficiency and/or overcome resistance to TKIs.

Therapeutic implications of targeting autophagy and TGF-β crosstalk for the treatment of liver fibrosis

Liver fibrosis is characterized by the excessive deposition and accumulation of extracellular matrix components, mainly collagens, and occurs in response to a broad spectrum of triggers with different etiologies. Under stress conditions, autophagy serves as a highly conserved homeostatic system for cell survival and is importantly involved in various biological processes. Transforming growth factor-β1 (TGF-β1) has emerged as a central cytokine in hepatic stellate cell (HSC) activation and is the main mediator of liver fibrosis. A growing body of evidence from preclinical and clinical studies suggests that TGF-β1 regulates autophagy, a process that affects various essential (patho)physiological aspects related to liver fibrosis. This review comprehensively highlights recent advances in our understanding of cellular and molecular mechanisms of autophagy, its regulation by TGF-β, and the implication of autophagy in the pathogenesis of progressive liver disorders. Moreover, we evaluated crosstalk between autophagy and TGF-β1 signalling and discussed whether simultaneous inhibition of these pathways could represent a novel approach to improve the efficacy of anti-fibrotic therapy in the treatment of liver fibrosis.

Real-Time Monitoring of Lysosomal Membrane Permeabilization Using Acridine Orange

Loss of lysosomal membrane integrity results in leakage of lysosomal hydrolases to the cytosol which might harm cell function and induce cell death. Destabilization of lysosomes often precede apoptotic or necrotic cell death and occur during both physiological and pathological conditions. The weak base acridine orange readily enters cells and accumulates in the acidic environment of lysosomes. Vital staining with acridine orange is a well-proven technique to observe lysosomal destabilization using fluorescence microscopy and flow cytometry. These analyses are, however, time consuming and only adapted for discrete time points, which make them unsuitable for large-scale approaches. Therefore, we have developed a time-saving, high-throughput microplate reader-based method to follow destabilization of the lysosomal membrane in real-time using acridine orange. This protocol can easily be adopted for patient samples since the number of cells per sample is low and the time for analysis is short.