Nanoparticles as carriers of photosensitizers to improve photodynamic therapy in cancer.

Photodynamic therapy (PDT) has emerged as a promising non invasive therapeutic approach for cancer treatment, offering unique advantages over conventional treatments. The combination of light activation and photosensitizing agents allows for targeted and localized destruction of cancer cells, reducing damage to surrounding healthy tissues. In recent years, the integration of nanoparticles with PDT has garnered significant attention due to their potential to enhance therapeutic outcomes. This review article aims to provide a comprehensive overview of the current state-of-the-art in utilizing nanoparticles for photodynamic therapy in cancer treatment. We summarized various nanoparticle-based approaches, their properties, and their implications in optimizing PDT efficacy, and discussed challenges and prospects in the field.

Adenovirus-α-Defensin Complexes Induce NLRP3-Associated Maturation of Human Phagocytes via Toll-Like Receptor 4 Engagement.

Intramuscular delivery of human adenovirus (HAdV)-based vaccines leads to rapid recruitment of neutrophils, which then release antimicrobial peptides/proteins (AMPs). How these AMPs influence vaccine efficacy over the subsequent 24 h is poorly understood. In this study, we asked if human neutrophil protein 1 (HNP-1), an α-defensin that influences direct and indirect innate immune responses to a range of pathogens, impacts the response of human phagocytes to three HAdV species/types (HAdV-C5, -D26, -B35). We show that HNP-1 binds to the capsids and redirects HAdV-C5, -D26, and -B35 to Toll-like receptor 4 (TLR4), which leads to internalization, an NLRP3-mediated inflammasome response, and interleukin 1 beta (IL-1ß) release. Surprisingly, IL-1ß release was not associated with notable disruption of plasma membrane integrity. These data further our understanding of HAdV vaccine immunogenicity and may provide pathways to extend the efficacy. IMPORTANCE This study examines the interactions between danger-associated molecular patterns and human adenoviruses, and their impact on vaccines. HAdVs and HNP-1 can interact, and these interactions will modify the response of antigen-presenting cells, which will influence vaccine efficacy.

Nanosized-Loratadine Embedded Orodispersible Films for Enhanced Bioavailability: Scalable Preparations and Characterizations.

The patient-centric strategy urges the pharmaceutical companies to develop orodispersible films (ODF) as a new approach for pediatrics. However, the most common ODF-fabricated method, solvent casting, is facing the safety challenges of safety during manufacturing. To obtain favorable formulations with the ease of use and rapid dissolution, nanotechnology has been accounted for the development process. In this work, we investigated the wet-milling technique in preparing nanocarriers for loratadine-a hydrophobic anti-histamine drug. The results showed that the wet-milling technique could produce nanocarriers at the size of 400 nm. The reduction of particle size induced the increase of solubility and the dissolution rate of loratadine. Moreover, the pre-formulation of nanosized materials could adapt to the preparation of orodispersible films that disintegrated (less than 60s) and dissolved quickly. The DSC results showed that after the milling process, the crystallinity of loratadine was unchanged; however, the reduction in size induced an enhancement of drug bioavailability. After orally administrated to rats, the drug was quickly reached to the blood circulation, just after 30 min. Cmax increased from 44.97 ng/mL for the raw drug to 101.02 ng/mL for the nanocrystal leading to an enhancement of the AUC0-24h by 5.69-fold when the nanocrystal ODF was administrated. The ease of formulation and the improvement of drug solubility as well as bioavailability potentiated orodispersible films as a promising drug delivery for loratadine. Graphical abstract.

Peptide-Oleate Complexes Create Novel Membrane-Bound Compartments.

A challenging question in evolutionary theory is the origin of cell division and plausible molecular mechanisms involved. Here, we made the surprising observation that complexes formed by short alpha-helical peptides and oleic acid can create multiple membrane-enclosed spaces from a single lipid vesicle. The findings suggest that such complexes may contain the molecular information necessary to initiate and sustain this process. Based on these observations, we propose a new molecular model to understand protocell division.

Bladder cancer therapy without toxicity-A dose-escalation study of alpha1-oleate.

Potent chemotherapeutic agents are required to counteract the aggressive behavior of cancer cells and patients often experience severe side effects, due to tissue toxicity. Our study addresses if a better balance between efficacy and toxicity can be attained using the tumoricidal complex alpha1-oleate, formed by a synthetic, alpha-helical peptide comprising the N-terminal 39 amino acids of alpha-lactalbumin and the fatty acid oleic acid. Bladder cancer was established, by intravesical instillation of MB49 cells on day 0 and the treatment group received five instillations of alpha1-oleate (1.7-17 mM) on days 3 to 11. A dose-dependent reduction in tumor size, bladder size and bladder weight was recorded in the alpha1-oleate treated group, compared to sham-treated mice. Tumor markers Ki-67, Cyclin D1 and VEGF were inhibited in a dose-dependent manner, as was the expression of cancer-related genes. Remarkably, toxicity for healthy tissue was not detected in alpha1-oleate-treated, tumor-bearing mice or healthy mice or rabbits, challenged with increasing doses of the active complex. The results define a dose-dependent therapeutic effect of alpha1-oleate in a murine bladder cancer model.

Preparation of High-Payload, Prolonged-Release Biodegradable Poly(lactic-co-glycolic acid)-Based Tacrolimus Microspheres Using the Single-Jet Electrospray Method.

Tacrolimus-loaded poly(lactic-co-glycolic acid) microspheres (TAC-PLGA-M) can be administered for the long-term survival of transplanted organs due to their immunosuppressive activity. The purpose of our study was to optimize the parameters of the electrospray method, and to prepare TAC-PLGA-M with a high payload and desirable release properties. TAC-PLGA-M were prepared using the electrospray method. In vitro characterization and evaluation were performed using scanning electron microscopy, X-ray diffraction (XRD), differential scanning calorimetry (DSC), and Fourier-transform infrared spectroscopy. Drug-loading efficiency was greater than 80% in all formulations with a maximum loading capacity of 16.81±0.37%. XRD and DSC studies suggested that the drug was incorporated in an amorphous state or was molecularly dispersed in the microspheres. The in vitro release study showed prolonged release patterns. TAC-PLGA-M with enhanced drug loading and prolonged-release patterns were successfully prepared using the electrospray method.

Development of Solid Self-Emulsifying Formulation for Improving the Oral Bioavailability of Erlotinib.

To improve the solubility and oral bioavailability of erlotinib, a poorly water-soluble anticancer drug, solid self-emulsifying drug delivery system (SEDDS) was developed using solid inert carriers such as dextran 40 and Aerosil® 200 (colloidal silica). The preliminary solubility of erlotinib in various oils, surfactants, and co-surfactants was determined. Labrafil M2125CS, Labrasol, and Transcutol HP were chosen as the oil, surfactant, and co-surfactant, respectively, for preparation of the SEDDS formulations. The ternary phase diagram was evaluated to show the self-emulsifying area. The formulations were optimized using the droplet size and polydispersity index (PDI) of the resultant emulsions. Then, the optimized formulation containing 5% Labrafil M2125CS, 65% Labrasol, and 30% Transcutol was spray dried with dextran or Aerosil® and characterized for surface morphology, crystallinity, and pharmacokinetics in rats. Powder X-ray diffraction (PXRD) and differential scanning calorimetry (DSC) exhibited the amorphous form or molecular dispersion of erlotinib in the formulations. The pharmacokinetic parameters of the optimized formulations showed that the maximum concentration (C max) and area under the curve (AUC) of erlotinib were significantly increased, compared to erlotinib powder (p < 0.05). Thus, this SEDDS could be a promising method for enhancing the oral bioavailability of erlotinib.

Modulation of Pharmacokinetic and Cytotoxicity Profile of Imatinib Base by Employing Optimized Nanostructured Lipid Carriers.

PURPOSE: To prepare, optimize and characterize imatinib-loaded nanostructured lipid carriers (IMT-NLC), and evaluate their pharmacokinetic and cytotoxicity characteristics. METHODS: IMT-NLC was prepared by hot homogenization method, and optimized by an approach involving Plackett-Burman design (PBD) and central composite design (CCD). An in vivo pharmacokinetic study was conducted in rats after both oral and intravenous administration. The in vitro cytotoxicity was evaluated by MTT assay on NCI-H727 cell-lines. RESULTS: PBD screening, followed by optimization by CCD and desirability function, yielded an optimized condition of 0.054, 6% w/w, 2.5% w/w and 1.25% w/v for organic-to-aqueous phase ratio (O/A), drug-to-lipid ratio (D/L), amount of lecithin (Lec) and amount of Tween® 20 (Tw20) respectively. The optimized IMT-NLC exhibited a particle size (Sz) of 148.80 ± 1.37 nm, polydispersity index (PDI) 0.191 ± 0.017 of and ζ-potential of -23.0 ± 1.5 mV, with a drug loading (DL) of 5.48 ± 0.01% and encapsulation efficiency (EE) of 97.93 ± 0.03%. IMT-NLC displayed sustained IMT release in vitro, significantly enhanced in vivo bioavailability of IMT after intravenous and oral administration, and greater in vitro cytotoxicity on NCI-H727 cells, compared with free IMT. CONCLUSION: A combined DoE approach enabled accurate optimization and successful preparation of IMT-NLC with enhanced in vivo pharmacokinetic and in vitro cytotoxicity characteristics.

Development and Evaluation of Artesunate-Loaded Chitosan-Coated Lipid Nanocapsule as a Potential Drug Delivery System Against Breast Cancer.

Artesunate (ART)--a well-known hydrophobic anti-malarial agent was incorporated in a polymer-lipid hybrid nanocolloidal system for anti-cancer therapeutic. The lipid negatively charged nanoemulsion was formulated by modified hot homogenization method then covered with positively charged chitosan via electrostatic interaction to obtain chitosan-coated lipid nanocapsule (ART-CLN). Physical properties of the system were characterized in terms of size, charge, morphology, drug loading capacity, and physical state. In addition, anti-cancer activities were confirmed by conducting MTT assay for ART and ART-CLN on different cancer cell lines. Obtained ART-CLN after coating chitosan revealed positive charge (13.2 ± 0.87 mV), small particle size (160.9 ± 3.5 nm), and spherical shape. High drug entrapment efficiency (95.49 ± 1.13%) and sustained release pattern were observed. Moreover, the good cellular uptake was recorded by flow cytometry as well as confocal image. Finally, ART-CLN exhibited stronger anti-cancer activity than free ART on breast cancer cell lines (MCF-7, MDA-MB-231). These results suggested that by loading ART into lipid core of polymer-lipid hybrid carrier, the activity and physical stability of ART can be significantly increased for cancer chemotherapy.

Development of vorinostat-loaded solid lipid nanoparticles to enhance pharmacokinetics and efficacy against multidrug-resistant cancer cells.

PURPOSE: To investigate whether delivery of a histone deacetylase inhibitor, vorinostat (VOR), by using solid lipid nanoparticles (SLNs) enhanced its bioavailability and effects on multidrug-resistant cancer cells. METHODS: VOR-loaded SLNs (VOR-SLNs) were prepared by hot homogenization using an emulsification-sonication technique, and the formulation parameters were optimized. The cytotoxicity of the optimized formulation was evaluated in cancer cell lines (MCF-7, A549, and MDA-MB-231), and pharmacokinetic parameters were examined following oral and intravenous (IV) administration to rats. RESULTS: VOR-SLNs were spherical, with a narrowly distributed average size of ~100 nm, and were physically stable for 3 months. Drug release showed a typical bi-phasic pattern in vitro, and was independent of pH. VOR-SLNs were more cytotoxic than the free drug in both sensitive (MCF-7 and A549) and resistant (MDA-MB-231) cancer cells. Importantly, SLN formulations showed prominent cytotoxicity in MDA-MB-231 cells at low doses, suggesting an ability to effectively counter the P-glycoprotein-related drug efflux pumps. Pharmacokinetic studies clearly demonstrated that VOR-SLNs markedly improved VOR plasma circulation time and decreased its elimination rate constant. The areas under the VOR concentration-time curve produced by oral and IV administration of VOR-SLNs were significantly greater than those produced by free drug administration. These in vivo results clearly highlighted the remarkable potential of SLNs to augment the bioavailability of VOR. CONCLUSIONS: VOR-SLNs successfully enhanced the oral bioavailability, circulation half-life, and chemotherapeutic potential of VOR.

Chitosan-based polyelectrolyte complexes as potential nanoparticulate carriers: physicochemical and biological characterization.

PURPOSE: To investigate the effect of polyelectrolytes on the formation and physicochemical properties of chitosan nanoparticles (CS-NPs) used for the delivery of an anticancer drug, doxorubicin (DOX). METHOD: Three DOX-loaded CS-NPs were formulated with tripolyphosphate (CS-TP/DOX NPs), dextran sulfate (CS-DS/DOX NPs), and hyaluronic acid (CS-HA/DOX NPs) by using ionotropic gelation or complex coacervation. RESULTS: CS-TP/DOX NPs were the smallest, with an average size of ~100 nm and a narrow size distribution, while CS-DS/DOX and CS-HA/DOX NPs were ~200 nm in size. Transmission electron microscopy clearly showed a spherical shape for all the NPs. The strong binding affinity of DOX for the multiple sulfate groups in DS resulted in a sustained release profile from CS-DS/DOX NPs at pH 7.4, while CS-HA/DOX NPs exhibited faster DOX release. This trend was also present under acidic conditions, where release of DOX was significantly augmented because of polymer protonation. Compared to CS-TP/DOX or CS-DS/DOX NPs, CS-HA/DOX NPs showed superior cellular uptake and cytotoxicity in MCF-7 and A-549 cells, because of their ability to undergo CD44-mediated endocytosis. Pharmacokinetic studies clearly showed that all CS-NPs tested significantly improved DOX plasma circulation time and decreased its elimination rate constant. Consistent with the in vitro release data, CS-DS/DOX NPs exhibited a relatively better DOX plasma profile and enhanced blood circulation, compared to CS-HA/DOX or CS-TP/DOX NPs. Overall, these results demonstrated how NP design can influence their function. CONCLUSIONS: Taken together, CS-based polyelectrolyte complexes could provide a versatile delivery system with enormous potential in the pharmaceutical and biomedical sectors.

Formulation and optimization of raloxifene-loaded solid lipid nanoparticles to enhance oral bioavailability.

The main aim of this study was to improve the oral bioavailability of raloxifene (RXF), a selective estrogen receptor modulator, by incorporation into solid lipid nanoparticles (SLN). RXF-loaded SLN was prepared by homogenization-sonication technique and characterized through physicochemical, pharmacokinetic, and cytotoxicity studies. The optimized SLN formulation exhibited a spherical shape with average size around 140 nm, easing its transport across the lymphatic system. Augmentation in the profiles of C(max) (308%) and AUC (270%) indicated a significant enhancement in the rate and extent of bioavailability by SLN formulations compared to free drug. In vitro cytotoxicity study performed in NIH-3T3 cells revealed that RXF-SLN was cytocompatible, and SLN remained unchanged during the freeze-drying process. Furthermore, the optimized formulation was quite stable at room temperature for more than two months, exemplifying its superior performance. In conclusion, SLN provides a promising platform for the pronounced enhancement of RXF bioavailability.

Preparation and characterization of fenofibrate-loaded nanostructured lipid carriers for oral bioavailability enhancement.

The aim of this study is to investigate the potential of nanostructured lipid carriers (NLCs) in improving the oral bioavailability of a lipid lowering agent, fenofibrate (FEN). FEN-loaded NLCs (FEN-NLCs) were prepared by hot homogenization followed by an ultrasonication method using Compritol 888 ATO as a solid lipid, Labrafil M 1944CS as a liquid lipid, and soya lecithin and Tween 80 as emulsifiers. NLCs were characterized in terms of particle size and zeta potential, surface morphology, encapsulation efficiency, and physical state properties. Bioavailability studies were carried out in rats by oral administration of FEN-NLC. NLCs exhibited a spherical shape with a small particle size (84.9 ± 4.9 nm). The drug entrapment efficiency was 99% with a loading capacity of 9.93 ± 0.01% (w/w). Biphasic drug release manner with a burst release initially, followed by prolonged release was depicted for in vitro drug release studies. After oral administration of the FEN-NLC, drug concentration in plasma and AUCt-∞ was fourfold higher, respectively, compared to the free FEN suspension. According to these results, FEN-NLC could be a potential delivery system for improvement of loading capacity and control of drug release, thus prolonging drug action time in the body and enhancing the bioavailability.

Anti-inflammatory effect of Piper longum L. fruit methanolic extract on lipopolysaccharide-treated RAW 264.7 murine macrophages.

Context: The Piper species was studied several potential properties such as anti-tumor, anti-inflammatory and antioxidant activity. However, the specific anti-inflammatory activity of the extract from the fruits of P. longum L. has not been investigated. Objectives: Our study want to examine the anti-inflammatory effects of P. longum L. fruit methanolic extracts (PLE) on lipopolysachharide (LPS)-stimulated RAW 264.7 murine macrophages to understand the mechanism of this effect. Method: This study examined the chemical profiling of PLE by LC-HRMS analysis and measured the presence of nitric oxide (NO), interleukin-6 (IL-6) and tumor necrosis factor alpha (TNF-α) in the supernatant using the Griess reagent assay and enzyme-linked immunosorbent assay (ELISA), respectively. The mRNA expression of IL-6, TNF-α, cyclooxygenase-2 (COX-2), and inducible nitric oxide synthase (iNOS) were evaluated by using real-time quantitative polymerase chain reaction (RT-qPCR). Furthermore, the protein expression of COX-2, iNOS and the phosphorylation of MAPK family, c-Jun N-terminal kinase (JNK), p38 in protein level were observed by western blotting. Result: PLE have detected 66 compounds which belong to different classes such as alkaloids, flavonoids, terpenoids, phenolics, lactones, and organic acids inhibited nitric oxide products with the IC50 = 28.5 ± 0.91 µg/mL. Moreover, PLE at 10-100 µg/mL up-regulate HO-1 protein expression from 3 to 10 folds at 3 h. It also downregulated the mRNA and protein expression of iNOS, COX-2, decreased IL-6 and TNF-α secretion by modulating the mitogen-activated protein kinase (MAPK) signaling pathway, specifically by decreasing the phosphorylation of p38 and JNK. Conclusion: These results shown chemical profiling of PLE and demonstrated that PLE exhibits anti-inflammatory effects by regulating the MAPK family and could be a potential candidate for the treatment of inflammatory diseases.

Statistical modeling, optimization and characterization of spray-dried solid self-microemulsifying drug delivery system using design of experiments.

The present study systematically and simultaneously investigates the influence of process variables of spray-drying on the properties of solid self-microemulsifying drug delivery system (SMEDDS) using design of experiment (DOE) and optimizes them in order to produce solid-SMEDDS satisfying pre-defined powder quality attributes. Flurbiprofen-loaded liquid-SMEDDS was dispersed in dextran and spray-dried. After preliminary screening, the independent factors selected according to three-factor, three-level Box-Behnken design were inlet temperature (X(1)), feed rate (X(2)) and carrier concentration (X(3)). The responses used to compute the effects of independent factors were moisture content (Y(1)), yield (Y(2)), drug content (Y(3)) and droplet size (Y(4)) of the micro-emulsion. SMEDDS powder characteristics such as morphology, thermal behavior, crystallinity and flowability were also considered. Models were developed and model fitting analysis showed an adequate fit for all responses, indicating good predictability. Significant effects of processing parameters on powder characteristics were observed. The spray-drying process parameters were optimized as inlet temperature (134°C), feed rate (5%) and carrier concentration (0.6%) to produce solid-SMEDDS with acceptable moisture content (0.72±0.02%), yield (58.5±2.9%), drug content (70.1±2.7 mg/g) and droplet size (166.8±13.8 nm). Validation of the optimization process in five batches showed experimental value very close to the predicted one, ensuring the reproducibility of the developed models. Furthermore, optimized parameters resulted a highly crystalline flurbiprofen changed to an amorphous form. In conclusion, this study demonstrated the applicability of the DOE approach for optimizing the process parameters to manufacture solid-SMEDDS with desired quality attributes.

Lactoferrin and Nanotechnology: The Potential for Cancer Treatment.

Lactoferrin (Lf)-a glycoprotein of the transferrin family-has been investigated as a promising molecule with diverse applications, including infection inhibition, anti-inflammation, antioxidant properties and immune modulation. Along with that, Lf was found to inhibit the growth of cancerous tumors. Owing to unique properties such as iron-binding and positive charge, Lf could interrupt the cancer cell membrane or influence the apoptosis pathway. In addition, being a common mammalian excretion, Lf offers is promising in terms of targeting delivery or the diagnosis of cancer. Recently, nanotechnology significantly enhanced the therapeutic index of natural glycoproteins such as Lf. Therefore, in the context of this review, the understanding of Lf is summarized and followed by different strategies of nano-preparation, including inorganic nanoparticles, lipid-based nanoparticles and polymer-based nanoparticles in cancer management. At the end of the study, the potential future applications are discussed to pave the way for translating Lf into actual usage.

Application of Computational Screening Tools and Nanotechnology for Enhanced Drug Synergism in Cancer Therapy.

BACKGROUND: Chemoresistance continues to limit the recovery of patients with cancer. New strategies, such as combination therapy or nanotechnology, can be further improved. OBJECTIVE: In this study, we applied the computational strategy by exploiting two databases (CellMiner and Prism) to sort out the cell lines sensitive to both anti-cancer drugs, paclitaxel (PTX) and dihydroartemisinin (DHA); both of which are potentially synergistic in several cell lines. METHODS: The combination of PTX and DHA was screened at different ratios to select the optimal ratio that could inhibit lung adenocarcinoma NCI-H23 the most. To further enhance therapeutic efficacy, these combinations of drugs were incorporated into a nanosystem. RESULTS: At a PTX:DHA ratio of 1:2 (w/w), the combined drugs obtained the best combination index (0.84), indicating a synergistic effect. The drug-loaded nanoparticles sized at 135 nm with the drug loading capacity of 15.5 ± 1.34 and 13.8 ± 0.56 corresponding to DHA and PTX, respectively, were used. The nano-sized particles improved drug internalization into the cells, resulting in the significant inhibition of cell growth at all tested concentrations (p < 0.001). Additionally, α-tubulin aggregation, DNA damage suggested the molecular mechanism behind cell death upon PTX-DHA-loaded nanoparticle treatment. Moreover, the rate of apoptosis increased from approximately 5% to more than 20%, and the expression of apoptotic proteins changed 4 and 3 folds corresponding to p-53 and Bcl-2, respectively. CONCLUSION: This study was designed thoroughly by screening cell lines for the optimization of formulations. This novel approach could pave the way for the selection of combined drugs for precise cancer treatment.

Formulation, characterization and optimization of valsartan self-microemulsifying drug delivery system using statistical design of experiment.

The aim of the present research was to systematically investigate the main, interaction and the quadratic effects of formulation variables on the performance of self-microemulsifying drug delivery system (SMEDDS) of valsartan using design of experiment. A 17-run Box-Behnken design (BBD) with 3-factors and 3-levels, including 5 replicates at the centre point, was used for fitting a 2nd-order response surface. After the preliminary screening, Labrafil M 2125 CS as oil, Tween 20 as surfactant and Capryol 90 as co-surfactant were taken as independent variables. The dependent factors (responses) were particle size, polydispersity index (PDI), dissolution after 15 min and equilibrium solubility. Coefficients were estimated by regression analysis and the model adequacy was checked by an F-test and the determination coefficient (R(2)). All the responses were optimized simultaneously by using desirability function. Our results demonstrated marked main and interaction effects of independent factors on responses. The optimized formulation consisted of 26.8% (w/w) oil, 60.1% (w/w) surfactant and 13.1% (w/w) co-surfactant, and showed average micelle size of 90.7 nm and 0.246 PDI, 91.2% dissolution after 15 min and 226.7 mg/g equilibrium solubility. For the optimized formulation, predicted value and experimental value were in close agreement. After oral administration, the optimized formulation gave more than 2-fold higher area under curve (AUC) and about 6-fold higher C(max) in rats than valsartan powder (p<0.05). The BBD facilitated in the better understanding of inherent relationship of formulation variables with the responses and in the optimization of valsartan SMEDDS in relatively time and labor effective manner.

Targeting the PD-1/PD-L1 axis for cancer treatment: a review on nanotechnology.

Although nanomedicines have been in the oncology field for almost three decades with the introduction of doxil, only a few nanomedicine products have reached approval. Can nanotechnology be a realistic tool to reduce the number of hospital beds? At present, several clinically approved anti-PD-1/PD-L1 antibodies or CAR T cell-based therapies are available; however, the immunotherapy field is far from mature. Will immunotherapy be the fourth pillar of cancer treatment? In this review, we summarized the current status of immunotherapy using PD-1/PD-L1-targeting nanocarriers. The knowledge on material science, therapeutic agents and formulation designs could pave the way for high-efficacy treatment outcomes.

Lipid bilayer composition as a determinant of cancer cell sensitivity to tumoricidal protein-lipid complexes.

Complexes formed by the alpha1 N-terminal peptide of alpha-lactalbumin and oleic acid (alpha1-oleate) interact with lipid bilayers. Plasma membrane perturbations trigger tumor cell death but normal differentiated cells are more resistant, and their plasma membranes are less strongly affected. This study examined membrane lipid composition as a determinant of tumor cell reactivity. Bladder cancer tissue showed a higher abundance of unsaturated lipids enriched in phosphatidylcholine, PC (36:4) and PC (38:4), and sphingomyelin, SM (36:1) than healthy bladder tissue, where saturated lipids predominated and the lipid extracts from bladder cancer tissue inhibited the tumoricidal effect of the complex more effectively than healthy tissue extracts. Furthermore, unsaturated PC in solution inhibited tumor cell death, and the complex interacted with giant unilamellar vesicles formed by PC, confirming the affinity of alpha1-oleate for fluid membranes enriched in PC. Quartz Crystal Microbalance with dissipation monitoring (QCM-D) detected a preference of the complex for the liquid-disordered phase, suggesting that the insertion into PC-based membranes and the resulting membrane perturbations are influenced by membrane lipid saturation. The results suggest that the membrane lipid composition is functionally important and that specific unsaturated membrane lipids may serve as "recognition motifs" for broad-spectrum tumoricidal molecules such as alpha1-oleate.