The adrenal specific toxicant mitotane directly interacts with lipid membranes and alters membrane properties depending on lipid composition

The small-molecule kinase inhibitor ceritinib, unlike imatinib, causes a significant disturbance of lipid membrane integrity: A combined experimental and MD study

Ceritinib and imatinib are small-molecule protein kinase inhibitors which are applied as therapeutic agents against various diseases. The fundamentals of their clinical use, i.e. their pharmacokinetics as well as the mechanisms of the inhibition of the respective kinases, are relatively well studied. However, the interaction of the drugs with membranes, which can be a possible cause of side effects, has hardly been investigated so far. Therefore, we have characterized the interaction of both drugs with lipid membranes consisting of 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) in the absence and in the presence of cholesterol. For determining the membrane impact of both drugs on a molecular level, different experimental (NMR, ESR, fluorescence) and theoretical (MD simulations) approaches were applied. The data show that ceritinib, in contrast to imatinib, interacts more effectively with membranes significantly affecting various physico-chemical membrane parameters like membrane order and transmembrane permeation of polar solutes. The pronounced membrane impact of ceritinib can be explained by a strong affinity of the drug towards POPC which competes with the POPC-cholesterol interaction by that attenuating the ordering effect of cholesterol. The data are relevant for understanding putative toxic and cytotoxic side effects of these drugs such as the triggering of cell lysis or apoptosis.

Natamycin interferes with ergosterol-dependent lipid phases in model membranes

Natamycin is an antifungal polyene macrolide that is used as a food preservative but also to treat fungal keratitis and other yeast infections. In contrast to other polyene antimycotics, natamycin does not form ion pores in the plasma membrane, but its mode of action is poorly understood. Using nuclear magnetic resonance (NMR) spectroscopy of deuterated sterols, we find that natamycin slows the mobility of ergosterol and cholesterol in liquid-ordered (Lo) membranes to a similar extent. This is supported by molecular dynamics (MD) simulations, which additionally reveal a strong impact of natamycin dimers on sterol dynamics and water permeability. Interference with sterol-dependent lipid packing is also reflected in a natamycin-mediated increase in membrane accessibility for dithionite, particularly in bilayers containing ergosterol. NMR experiments with deuterated sphingomyelin (SM) in sterol-containing membranes reveal that natamycin reduces phase separation and increases lipid exchange in bilayers with ergosterol. In ternary lipid mixtures containing monounsaturated phosphatidylcholine, saturated SM, and either ergosterol or cholesterol, natamycin interferes with phase separation into Lo and liquid-disordered (Ld) domains, as shown by NMR spectroscopy. Employing the intrinsic fluorescence of natamycin in ultraviolet-sensitive microscopy, we can visualize the binding of natamycin to giant unilamellar vesicles (GUVs) and find that it has the highest affinity for the Lo phase in GUVs containing ergosterol. Our results suggest that natamycin specifically interacts with the sterol-induced ordered phase, in which it disrupts lipid packing and increases solvent accessibility. This property is particularly pronounced in ergosterol containing membranes, which could underlie the selective antifungal activity of natamycin.

Neurological adverse events of mitotane in adrenocortical carcinoma: results of a pilot study

Introduction

Mitotane, the only drug approved by the Food and Drug Administration (FDA) for the treatment of adrenocortical carcinoma, is associated with several side effects including neurotoxicity. The aim of our study is to investigate the relationship between mitotane plasma levels and neurological toxicity.

Methods

We have considered five patients affected by adrenocortical carcinoma treated with mitotane. The neurological assessment included a neurological examination, an electroencephalogram, event-related potentials (P300), and a neuropsychological assessment. All of the patients were first considered at the onset of symptoms of neurotoxicity or when mitotanemia levels were above 18 mg/L, for the second time at mitotanemia normalization and subsequently at its further increase, or in case of persistent neurological abnormalities, some months after normalization.

Results

At the first neurotoxicity, four patients showed impaired neurological examination, electroencephalogram, and P300; three patients had impaired neuropsychological assessment; one patient, only P300. At mitotanemia normalization, the neurological examination became normal in all patients and electroencephalogram normalized in one patient, improved in another one, continuing to be altered in the other three. P300 latency and neuropsychological assessment normalized in two patients and persisted altered in the patient experiencing long-term mitotane toxicity. At the third evaluation, in the patient with prolonged mitotane toxicity, the normal mitotanemia in the previous 9 months restored P300 and improved the electroencephalogram but not the neuropsychological assessment. In the two patients experiencing a further rise of mitotanemia, neurological examination was normal but P300 and electroencephalogram were altered.

Conclusion

The results of our study highlighted the presence of neurophysiological and neuropsychological abnormalities associated with mitotane values above 18 mg/L.

Serotonergic drugs modulate the phase behavior of complex lipid bilayers

Serotonin is an endogenous neurotransmitter involved in both physiological and pathophysiological processes. Traditionally, serotonin acts as a ligand for G protein-coupled receptors (GPCRs) leading to subsequent cell signaling. However, serotonin can also bind to lipid membranes with high affinity and modulate the phase behavior in 1-palmitoyl-2-oleoyl-glycero-3-phosphocholine (POPC)/N-palmitoyl-D-erythro-sphingosylphosphorylcholine (PSM)/cholesterol model membranes mimicking the outer leaflet of the plasma membrane. Here, we investigated if serotonergic drugs containing the pharmacophore from serotonin would also modulate phase behavior in lipid membranes in a similar fashion. We used ²H NMR spectroscopy to explore the phase behavior of POPC/PSM/cholesterol (4/4/2 molar ratio) mixtures in the presence of the serotonergic drugs aripiprazole, BRL-54443, BW-723C86, and CP-135807 at a lipid to drug molar ratio of 10:1. POPC and PSM were perdeuterated in the palmitoyl chain, respectively, and prepared in individual samples. Numerical lineshape simulations of the ²H NMR spectra were used to calculate the order parameter profiles and projected lengths of the saturated acyl chains. All serotonergic drugs induce two components in ²H NMR spectra, indicating that they increased the hydrophobic mismatch between the thickness of the coexisting lipid phases leading to larger domain sizes, relatively similarly to serotonin. AFM force indentation and Raman spectral studies, which interrogate membrane mechanical properties, also indicate changes in membrane order in the presence of these drugs. These findings highlight how serotonergic drugs alter membrane phase behavior and could modulate both target and other membrane proteins, possibly explaining the side effects observed for serotonergic and other clinically relevant drugs.

Effects of the RNA-Polymerase Inhibitors Remdesivir and Favipiravir on the Structure of Lipid Bilayers-An MD Study

The structure and dynamics of membranes are crucial to ensure the proper functioning of cells. There are some compounds used in therapeutics that show nonspecific interactions with membranes in addition to their specific molecular target. Among them, two compounds recently used in therapeutics against COVID-19, remdesivir and favipiravir, were subjected to molecular dynamics simulation assays. In these, we demonstrated that the compounds can spontaneously bind to model lipid membranes in the presence or absence of cholesterol. These findings correlate with the corresponding experimental results recently reported by our group. In conclusion, insertion of the compounds into the membrane is observed, with a mean position close to the phospholipid head groups.

Mitotane Nanocarriers for the Treatment of Adrenocortical Carcinoma: Evaluation of Albumin-Stabilized Nanoparticles and Liposomes in a Preclinical In Vitro Study with 3D Spheroids

Adrenocortical carcinoma (ACC) is a heterogeneous malignancy related to poor prognosis and limited treatment options. The orphan drug mitotane (MT) is still a cornerstone in ACC therapy, however, its application is characterized by low aqueous solubility, poor bioavailability, and unfavorable pharmacokinetics, often resulting in below-target plasma concentrations or toxic side effects. Throughout the last decades, nanoparticulate formulations have become attractive carriers to improve anticancer therapy. In this study, injectable MT liposomes (DOPC-MT) and albumin-stabilized MT nanoparticles (BSA-MT) were investigated in depth with respect to their physicochemical properties, and their colloidal and therapeutical stability upon storage. Furthermore, in vitro cytotoxicity was evaluated using the ACC model cell line NCI-H295R for preparing multicellular tumor spheroids, and was compared to non-malignant human dermal fibroblasts. Our results clearly demonstrate that BSA-MT, unlike DOPC-MT, represents a stable and storable MT formulation with a high drug concentration in an aqueous medium. Dual centrifugation was established as a reproducible method for nanoparticle preparation. Although an efficient cytotoxic effect on ACC tumor spheroids was demonstrated, concomitant low toxicity to fibroblasts suggests that higher drug concentrations may be tolerated in vivo. Consequently, BSA-MT is a novel and promising therapeutical approach to address key challenges in MT treatment.

Drug-Membrane Interactions: Effects of Virus-Specific RNA-Dependent RNA Polymerase Inhibitors Remdesivir and Favipiravir on the Structure of Lipid Bilayers

The two RNA-dependent RNA polymerase inhibitors remdesivir and favipiravir were originally developed and approved as broad-spectrum antiviral drugs for the treatment of harmful viral infections such as Ebola and influenza. With the outbreak of the global SARS-CoV-2 pandemic, the two drugs were repurposed for the treatment of COVID-19 patients. Clinical studies suggested that the efficacy of the drugs is enhanced in the case of an early or even prophylactic application. Because the contact between drug molecules and the plasma membrane is essential for a successful permeation process of the substances and therefore for their intracellular efficiency, drug-induced effects on the membrane structure are likely and have already been shown for other substances. We investigated the impact of remdesivir and favipiravir on lipid bilayers in model and cell membranes via several biophysical approaches. The measurements revealed that the embedding of remdesivir molecules in the lipid bilayer results in a disturbance of the membrane structure of the tested phospholipid vesicles. Nevertheless, in a cell-based assay, the presence of remdesivir induced only weak hemolysis of the treated erythrocytes. In contrast, no experimental indication for an effect on the structure and integrity of the membrane was detected in the case of favipiravir. Regarding potential prophylactic or accompanying use of the drugs in the therapy of COVID-19, the physiologically relevant impacts associated with the drug-induced structural modifications of the membrane might be important to understand side effects and/or low effectivities.

Characterization of hyperlipidemia secondary to mitotane in adrenocortical carcinoma

Background

This study examined the magnitude of changes and the time required to observe maximal changes in LDL-c, HDL-c, triglycerides (Tg) and non-HDL-c after the introduction of mitotane.

Methods

Retrospective study of 45 patients with adrenocortical carcinoma who were treated at the Centre hospitalier de l'Université de Montréal. Clinical and biochemical data were collected, including lipid profiles before and during the first year of treatment with mitotane.

Results

Among the 45 studied patients, 26 (58%) had a complete lipid profile before the introduction of mitotane and at least 1 lipid profile during the first year of treatment, and 19 patients (42%) had a lipid profile following initiation of the treatment. Among the 26 patients who had lipid profiles before and after the introduction of mitotane, the increase of LDL-c was 2.19 mmol/L (76%) (P< 0.0001), HDL-c was 0.54 mmol/L (35%) (P= 0.0002), Tg was 1.80 mmol/L (129%) (P< 0.0001) and non-HDL-c was 2.73 mmol/L (79%) (P< 0.0001). Between the first and the sixth month of mitotane treatment, peak values (n  = 45) of LDL-c and non-HDL-c were reached in 42 patients (93%) and 37 patients (82%), respectively, whereas peak values of HDL-c were reached after 6 months of mitotane treatment in 29 patients (66%). The peak value of Tg was almost equal throughout the first year. The mean peak values of HDL-c, Tg and non-HDL-c showed significant associations with their respective mitotane concentrations (β = 0.352, P= 0.03; β = 0.406, P= 0.02 and β = 0.339, P= 0.05).

Conclusion

The introduction of mitotane produces a clinically significant elevation of lipid parameters (LDL-c, HDL-c, Tg and non-HDL-c) during the first year of treatment.

Membrane Interaction of Ibuprofen with Cholesterol-Containing Lipid Membranes

Deciphering the membrane interaction of drug molecules is important for improving drug delivery, cellular uptake, and the understanding of side effects of a given drug molecule. For the anti-inflammatory drug ibuprofen, several studies reported contradictory results regarding the impact of ibuprofen on cholesterol-containing lipid membranes. Here, we investigated membrane localization and orientation as well as the influence of ibuprofen on membrane properties in POPC/cholesterol bilayers using solid-state NMR spectroscopy and other biophysical assays. The presence of ibuprofen disturbs the molecular order of phospholipids as shown by alterations of the ²H and ³¹P-NMR spectra of the lipids, but does not lead to an increased membrane permeability or changes of the phase state of the bilayer. ¹H MAS NOESY NMR results demonstrate that ibuprofen adopts a mean position in the upper chain/glycerol region of the POPC membrane, oriented with its polar carbonyl group towards the aqueous phase. This membrane position is only marginally altered in the presence of cholesterol. A previously reported result that ibuprofen is expelled from the membrane interface in cholesterol-containing DMPC bilayers could not be confirmed.

Interaction of the small-molecule kinase inhibitors tofacitinib and lapatinib with membranes

Lapatinib and tofacitinib are small-molecule kinase inhibitors approved for the treatment of advanced or metastatic breast cancer and rheumatoid arthritis, respectively. So far, the mechanisms which are responsible for their activities are not entirely understood. Here, we focus on the interaction of these drug molecules with phospholipid membranes, which has not yet been investigated before in molecular detail. Owing to their lipophilic characteristics, quantitatively reflected by large differences of the partition equilibrium between water and octanol phases (expressed by logP values), rather drastic differences in the membrane interaction of both molecules have to be expected. Applying experimental (nuclear magnetic resonance, fluorescence and ESR spectroscopy) and theoretical (molecular dynamics simulations) approaches, we found that lapatinib and tofacitinib bind to lipid membranes and insert into the lipid-water interface of the bilayer. For lapatinib, a deeper embedding into the membrane bilayer was observed than for tofacitinib implying different impacts of the molecules on the bilayer structure. While for tofacitinib, no influence to the membrane structure was found, lapatinib causes a membrane disturbance, as concluded from an increased permeability of the membrane for polar molecules. These data may contribute to a better understanding of the cellular uptake mechanism(s) and the side effects of the drugs.

Adjuvant Therapy in Adrenocortical Carcinoma: Reflections and Future Directions

Adrenocortical carcinoma (ACC) is a rare and aggressive malignancy with high risk of recurrence despite macroscopically complete surgical resection. The main predictors of ACC recurrence include advanced disease stage, incomplete surgical resection, cortisol production, certain genetic alterations, and high proliferation rate (Ki-67 proliferation index). Mitotane has been the mainstay adjuvant therapy of ACC. However, the use of mitotane is based on retrospective and occasionally conflicting evidence. As mitotane levels can take a few months before reaching therapeutic levels, there is an emerging practice of combining platinum-based chemotherapy with mitotane in the adjuvant setting. Retrospective data indicate that radiotherapy is an option for select patients, particularly those with positive resection margins. There are multiple knowledge gaps in selecting patients for adjuvant therapy. It is of great importance to establish risk calculators to predict recurrence and to implement molecular profiling of ACC to guide adjuvant therapy. The role of immunotherapy in metastatic ACC is emerging and if deemed efficacious, then future studies will be needed to ascertain the role of adjuvant immunotherapy in ACC.

Membrane Localization and Lipid Interactions of Common Lipid-Conjugated Fluorescence Probes

Lateral segregation of lipids in model and biological membranes has been studied intensively in the last decades using a comprehensive set of experimental techniques. Most methods require a probe to report on the biophysical properties of a specific molecule in the lipid bilayer. Because such probes can adversely affect the results of the measurement and perturb the local membrane structure and dynamics, a detailed understanding of probe behavior and its influence on the properties of its direct environment is important. Membrane phase-selective and lipid-mimicking molecules represent common types of probes. Here, we have studied how the fluorescent probes trans-parinaric acid (tPA), diphenylhexatriene (DPH), and 1-oleoyl-2-propionyl[DPH]-sn-glycero-3-phosphocholine (O-DPH-PC) affect the membrane properties of 1-palmitoyl-2-oleoyl-glycero-3-phosphocholine (POPC) bilayers using ²H and ³¹P NMR spectroscopy in the solid state. In addition, using 2D ¹H magic-angle spinning (MAS) nuclear Overhauser enhancement spectroscopy (NOESY) NMR, we have determined the distribution of the probe moieties in the POPC membrane parallel to the membrane normal. We found that the different probes exhibit distinct membrane localizations and distributions, e.g. tPA is located parallel to the membrane normal while DPH predominantly exist in two orientations. Further, tPA was conjugated to sphingomyelin (tPA-SM) as a substitute for the acyl chain in the SM. ¹H NOESY NMR was used to probe the interaction of the tPA-SM with cholesterol as dominant in liquid ordered membrane domains in comparison to POPC-cholesterol interaction in membranes composed of ternary lipid mixtures. We could show that tPA-SM exhibited a strong favorable and very temperature-dependent interaction with cholesterol in comparison to POPC. In conclusion, the NMR techniques can explain probe behavior but also be used to measure lipid-specific affinities between different lipid segments and individual molecules in complex bilayers, relevant to understanding nanodomain formation in biological membranes.

Hsp90 inhibition in adrenocortical carcinoma: Limited drug synergism with mitotane

90 kDa heat shock proteins (Hsp90) act as protein chaperones and play a role in modulating endoplasmic reticulum (ER) stress. Hsp90 inhibitors are under clinical investigation as cancer treatment. Mitotane therapy of adrenocortical carcinoma (ACC) has been shown to act through lipid-induced ER-stress. To explore the potential of Hsp90 inhibitors in ACC as a single agent and in combination with mitotane, we analyzed two independent gene expression data sets of adrenal tumors in silico and treated the ACC cell line model NCI-H295 with Hsp90 inhibitors BIIB021 (B) and CCT18159 (C) alone and in combination with mitotane. ER-stress markers were monitored by immunoblotting. Drug synergism was quantified using the median effect model with cell viability as read-out. Cytosolic Hsp90 isoforms AA1 and AB1 were significantly overexpressed in ACC. Viability of H295 cells was impaired by B and C as single agents with an EC₅₀ of 5.7 × 10^-6M and 12.1 × 10^-6M. B but not C dose-dependently increased XBP1 splicing and CHOP expression indicative of ER-stress activation. ER-stress marker expression was enhanced by co-incubation of B with 10  μM but not 5  μM mitotane. Maximal CHOP expression was induced by 25 μM mitotane alone with no additional effect of B. Combination indices (CI) of B and C with mitotane ranged from 0.64 to 1.38 and 0.68 to 1.30, respectively where CI values < 0.5 support clinically-relevant drug synergism. In conclusion, Hsp90 paralogs are differentially expressed in ACC and B but not C activates ER-stress in ACC cells. No meaningful drug synergism of Hsp90 inhibitors with mitotane was observed.

Enzyme autoinduction by mitotane supported by population pharmacokinetic modelling in a large cohort of adrenocortical carcinoma patients

OBJECTIVE

Mitotane is used for the treatment of adrenocortical carcinoma. High oral daily doses of typically 1- 6 g are required to attain therapeutic concentrations. The drug has a narrow therapeutic index and patient management is difficult because of a high volume of distribution, very long elimination half-life, and drug interaction through induction of metabolizing enzymes. The present evaluation aimed at the development of a population pharmacokinetic model of mitotane to facilitate therapeutic drug monitoring.

METHODS

Appropriate dosing information, plasma concentrations (1137 data points) and covariates were available from therapeutic drug monitoring (TDM) of 76 adrenocortical carcinoma patients treated with mitotane. Using nonlinear mixed effects modeling, a simple structural model was first developed, with subsequent introduction of metabolic autoinduction. Covariate data were analyzed to improve overall model predictability. Simulations were performed to assess the attainment of therapeutic concentrations with clinical dosing schedules.

RESULTS

A one-compartment pharmacokinetic model with first order absorption was found suitable to describe the data, with an estimated central volume of distribution of 6086 L related to a high interindividual variability of 81.5%. Increase in clearance of mitotane during treatment could be modeled by a linear enzyme autoinduction process. Body mass index was found to have an influence upon disposition kinetics of mitotane. Model simulations favor a high dose regimen to rapidly attain therapeutic concentrations, with the first TDM suggested on day 16 of treatment to avoid systemic toxicity.

CONCLUSION

The proposed model describes mitotane pharmacokinetics and can be used to facilitate therapy by predicting plasma concentrations.

The GRP78/BiP inhibitor HA15 synergizes with mitotane action against adrenocortical carcinoma cells through convergent activation of ER stress pathways

Many types of cancer cells present constitutively activated ER stress pathways because of their significant burden of misfolded proteins coded by mutated and rearranged genes. Further increase of ER stress by pharmacological intervention may shift the balance towards cell death and can be exploited therapeutically. Recent studies have shown that an important component in the mechanism of action of mitotane, the only approved drug for the medical treatment of adrenocortical carcinoma (ACC), is represented by activation of ER stress through inhibition of the SOAT1 enzyme and accumulation of toxic lipids. Here we show that HA15, a novel inhibitor of the essential ER chaperone GRP78/BiP, inhibits ACC H295R cell proliferation and steroidogenesis and is able to synergize with mitotane action. These results suggest that convergent activation of ER stress pathways by drugs acting via different mechanisms represents a valuable therapeutic option for ACC.

Bexarotene Binds to the Amyloid Precursor Protein Transmembrane Domain, Alters Its α-Helical Conformation, and Inhibits γ-Secretase Nonselectively in Liposomes

Bexarotene is a pleiotropic molecule that has been proposed as an amyloid-β (Aβ)-lowering drug for the treatment of Alzheimer's disease (AD). It acts by upregulation of an apolipoprotein E (apoE)-mediated Aβ clearance mechanism. However, whether bexarotene induces removal of Aβ plaques in mouse models of AD has been controversial. Here, we show by NMR and CD spectroscopy that bexarotene directly interacts with and stabilizes the transmembrane domain α-helix of the amyloid precursor protein (APP) in a region where cholesterol binds. This effect is not mediated by changes in membrane lipid packing, as bexarotene does not share with cholesterol the property of inducing phospholipid condensation. Bexarotene inhibited the intramembrane cleavage by γ-secretase of the APP C-terminal fragment C99 to release Aβ in cell-free assays of the reconstituted enzyme in liposomes, but not in cells, and only at very high micromolar concentrations. Surprisingly, in vitro, bexarotene also inhibited the cleavage of Notch1, another major γ-secretase substrate, demonstrating that its inhibition of γ-secretase is not substrate specific and not mediated by acting via the cholesterol binding site of C99. Our data suggest that bexarotene is a pleiotropic molecule that interfere with Aβ metabolism through multiple mechanisms.

Benefits of Adjuvant Mitotane after Resection of Adrenocortical Carcinoma: A Systematic Review and Meta-Analysis

Background

The adjuvant use of mitotane on adrenocortical carcinoma (ACC) has always been in controversy. We aimed to assess the prognostic benefits of adjuvant mitotane after resection of ACC in patients without distant metastasis.

Methods

The PubMed, WoS, Embase, and Cochrane Library databases were systematically searched. Recurrence-free survival (RFS) and overall survival (OS) were adopted as measurements. A meta-analysis was conducted based on hazard ratio (HR) with 95% confidence interval (CI). A study was included only if the enrolled patients underwent resection of ACC without adjuvant chemotherapy except mitotane.

Results

A total of 5 retrospective studies reporting on 1249 patients were included for this meta-analysis. The meta-analysis showed that adjuvant mitotane was significantly associated with prolonged RFS (HR = 0.62; 95%CI, 0.42-0.94; P < 0.05) and prolonged OS (HR = 0.69; 95%CI, 0.55-0.88, P < 0.05).

Conclusion

After comprehensive review, current evidence suggests that adjuvant mitotane significantly decreases the recurrence rate and mortality after resection of ACC in patients without distant metastasis, but these findings need further demonstration from prospective controlled trials.

Immunohistochemical Biomarkers of Adrenal Cortical Neoplasms

Careful morphological evaluation forms the basis of the workup of an adrenal cortical neoplasm. However, the adoption of immunohistochemical biomarkers has added tremendous value to enhance diagnostic accuracy. The authors provide a brief review of immunohistochemical biomarkers that have been used in the confirmation of adrenal cortical origin and in the detection of the source of functional adrenal cortical proliferations, as well as diagnostic, predictive, and prognostic biomarkers of adrenal cortical carcinoma. In addition, a brief section on potential novel theranostic biomarkers in the prediction of treatment response to mitotane and other relevant chemotherapeutic agents is also provided. In the era of precision and personalized medical practice, adoption of combined morphology and immunohistochemistry provides a new approach to the diagnostic workup of adrenal cortical neoplasms, reflecting the evolution of clinical responsibility of pathologists.

Identifying mitotane-induced mitochondria-associated membranes dysfunctions: metabolomic and lipidomic approaches

Mitotane (o,p’DDD), the most effective drug in adrenocortical carcinoma, concentrates into the mitochondria and impacts mitochondrial functions. To address the molecular mechanisms of mitotane action and to identify its potential target, metabolomic and lipidomic approaches as well as imaging analyses were employed in human adrenocortical H295R cells allowing identification of Mitochondria-Associated Membranes dysfunction as a critical impact of mitotane. Study of intracellular energetic metabolites by NMR spectroscopy showed that mitotane significantly decreased aspartate while concomitantly increased glutamate content in a time- and concentration-dependent manner. Such alterations were very likely linked to the previously described, mitotane-induced respiratory chain defect. Lipidomic studies of intracellular and intramitochondrial phospholipids revealed that mitotane exposure markedly reduced the phosphatidylserine/phosphatidylethanolamine ratio, indicative of a dysfunction of phosphatidylserine decarboxylase located in Mitochondria-Associated Membranes. Expression levels of Mitochondria-Associated Membranes proteins phosphatidylserine decarboxylase, DRP1, ATAD3A or TSPO were greatly reduced by mitotane as assessed by western blot analyses. Mitotane exposure markedly altered endogenous Mitochondria-Associated Membranes integrity and reduced the magnitude of mitochondria and the endoplasmic reticulum interactions as demonstrated by high resolution deconvolution microscopy and quantification. Finally, we showed that PK11195, a pharmacological inhibitor of the cholesterol translocator TSPO, embedded in Mitochondria-Associated Membranes, exerts a synergetic effect with mitotane in inducing Mitochondria-Associated Membranes disruption, apoptosis and in inhibiting steroid secretion. Altogether, our results demonstrate Mitochondria-Associated Membranes dysfunction in H295R cells treated with mitotane and that TSPO inhibition significantly potentiates mitotane antitumoral and antisecretory actions in vitro. This constitutes a potential and promising pharmacological strategy for patients with adrenocortical carcinoma.

The ER-mitochondria couple: In life and death from steroidogenesis to tumorigenesis

Steroidogenesis is a multistep process where interorganelle communications between the endoplasmic reticulum and mitochondria are critical. These intimate interactions physically occur through the Mitochondria-Associated ER membranes called MAMs. MAMs play important roles in mitochondrial morphology and in many cellular functions ranging from lipid metabolism, to calcium signaling and apoptosis together with a critical effect on steroidogenesis. Moreover, our recent characterization of new MAM resident proteins in adrenocortical cells extends the function of MAM in the mechanism of resistance of cancer cells to apoptotic stimuli and offers new perspectives in targeted therapeutic approaches for adrenocortical tumorigenesis.

Oral and vulvo-vaginal lichenoid reactions due to mitotane (Lysodren): A case report

BACKGROUND

The purpose of pharmacovigilance (drug safety) is collection, detection, assessment, monitoring, and prevention of adverse effects with pharmaceutical products. It is meant to identify, characterize, prevent, or minimize actual or potential risks relating to medicinal products. To prevent these adverse effects and improve our practice, health professionals have a duty to report side effects to assess this risk and evaluate the benefit/risk requirements. Mitotane (Lysodren) is used for treating adrenocortical carcinoma. Currently, no side effects concerning oral and genital mucosa have been reported.

CASE SUMMARY

This case report is about a 50 years old woman. Six months after the initiation on mitotane treatment, she developed erosive lesions located on the oral and vaginal mucosa. These drug reactions were diagnosed as erosive lichen planus by the biopsy. This lichenoid lesions were resistant to the usual treatments, mitotane being at the time not replaceable.

CONCLUSION

This case describes an unreported adverse effect of mitotane, it is - to our knowledge - the 1st description of erosive lichenoid drug reaction due to Mitotane.

The chain order of binary unsaturated lipid bilayers modulated by aromatic-residue-containing peptides: an ATR-FTIR spectroscopy study

It highlights the importance of aromatic residues in influencing peptide binding to the membrane, demonstrates that the stability of the membranes depends on the lipid composition and the sequence, structural context, and orientation of the peptides.

The interaction of sorafenib and regorafenib with membranes is modulated by their lipid composition

Sorafenib and regorafenib are small-molecule kinase inhibitors approved for the treatment of locally recurrent or metastatic, progressive, differentiated thyroid carcinoma, renal cell carcinoma, and hepatocellular carcinoma (sorafenib) and of colorectal cancer (regorafenib). As of now, the mechanisms, which are responsible for their antitumor activities, are not completely understood. Given the lipophilic nature of the molecules, it can be hypothesized that the pharmacological impact is mediated by the interaction with cellular membranes as it is true for many pharmacologically active molecules. However, an interaction of sorafenib or regorafenib with lipid membranes has not yet been investigated in detail. Here, we characterized the interaction of both drugs with lipid membranes by applying a variety of biophysical approaches including nuclear magnetic resonance, electron spin resonance, and fluorescence spectroscopy. We found that sorafenib and regorafenib bind to lipid membranes by inserting into the lipid-water interface of the bilayer. This membrane embedding causes a disturbance of bilayer structure leading to an increased permeability of the membrane for polar molecules. One approach shows that the extent of the effects depends on the membrane lipid composition underlining a particular role of phosphatidylcholine and cholesterol. Our data for the first time characterize the impact of sorafenib and regorafenib on the lipid membrane structure and dynamics, which may contribute to a better understanding of their effectiveness in the treatment of malignancies as well as of their side effects.