Citrate- and Succinate-Modified Carbonate Apatite Nanoparticles with Loaded Doxorubicin Exhibit Potent Anticancer Activity against Breast Cancer Cells

Delivery of siRNAs Against Selective Ion Channels and Transporter Genes Using Hyaluronic Acid-coupled Carbonate Apatite Nanoparticles Synergistically Inhibits Growth and Survival of Breast Cancer Cells

Introduction

Dysregulated calcium homeostasis and consequentially aberrant Ca2+ signalling could enhance survival, proliferation and metastasis in various cancers. Despite rapid development in exploring the ion channel functions in relation to cancer, most of the mechanisms accounting for the impact of ion channel modulators have yet to be fully clarified. Although harnessing small interfering RNA (siRNA) to specifically silence gene expression has the potential to be a pivotal approach, its success in therapeutic intervention is dependent on an efficient delivery system. Nanoparticles have the capacity to strongly bind siRNAs. They remain in the circulation and eventually deliver the siRNA payload to the target organ. Afterward, they interact with the cell surface and enter the cell via endocytosis. Finally, they help escape the endo-lysosomal degradation system prior to unload the siRNAs into cytosol. Carbonate apatite (CA) nanocrystals primarily is composed of Ca2+, carbonate and phosphate. CA possesses both anion and cation binding domains to target negatively charged siRNA molecules.

Methods

Hybrid CA was synthesized by complexing CA NPs with a hydrophilic polysaccharide - hyaluronic acid (HA). The average diameter of the composite particles was determined using Zetasizer and FE-SEM and their zeta potential values were also measured.

Results and Discussion

The stronger binding affinity and cellular uptake of a fluorescent siRNA were observed for HA-CA NPs as compared to plain CA NPs. Hybrid CA was electrostatically bound individually and combined with three different siRNAs to silence expression of calcium ion channel and transporter genes, TRPC6, TRPM8 and SLC41A1 in a human breast cancer cell line (MCF-7) and evaluate their potential for treating breast cancer. Hybrid NPs carrying TRPC6, TRPM8 and SLC41A1 siRNAs could significantly enhance cytotoxicity both in vitro and in vivo. The resultant composite CA influenced biodistribution of the delivered siRNA, facilitating reduced off target distribution and enhanced breast tumor targetability.

Characterization of herpetrione amorphous nanoparticles stabilized by hydroxypropylmethyl cellulose and its absorption mechanism in vitro

Herpetrione(HPE) is an effective compound that has been used in the treatment of liver diseases. To improve its dissolution and absorption, herpetrione nanosuspensions was prepared. Nanosuspensions were proved to achieve intact absorption in vivo. However, the transport mechanisms are not fully understood, especially lack of direct evidence of translocation of particulates. In this study, an environment-responsive dye, P4, was loaded into herpetrione amorphous nanoparticles (HPE-ANPs) to elucidate the absorption and transport mechanism of the nanoparticles. And the amount of HPE and nanoparticles in the samples were quantified using HPLC/LC-MS/MS and IVIS with the model of Caco-2 and Caco-2/HT29-MTX. Results demonstrated that HPE is mainly taken up by passive diffusion in the form of free drugs, while HPE-ANPs are internalized by an energy dependent active transport pathway or intracellular endocytosis. It is speculated that HPE-ANPs may change the original entry pathway of drug molecules. Furthermore, the presence of mucus layer and the use of HPMC E15 may contribute to drug absorption to some extent. Transcellular transport study indicates that HPE-ANPs has a poor absorption. In conclusion, the differences in the absorption behavior trends of HPE-ANPs are caused by the difference in particle properties and the form of existence of the drug.

Mitigating off-target distribution and enhancing cytotoxicity in breast cancer cells with alpha-ketoglutaric acid-modified Fe/Mg-CA nanoparticles

Purpose

In this work, pH-sensitive alpha-ketoglutaric acid-modified Fe/Mg-carbonate apatite (α-KAM-Fe/Mg-CA) NPs were introduced and found to be capable of promoting the selective delivery of cancer-killing drug doxorubicin (DOX) in breast cancer cells, while simultaneously mitigating DOX toxicity on normal cells.

Methods

As part of the characterization and evaluation of α-KAM-Fe/Mg-CA NPs to target breast cancer cells, a series of assessments were performed, which included size measurements, morphological analysis, FTIR, cytotoxicity assessment, hemolysis, drug binding, cellular uptake, and pH-responsive drug release tests. Liquid chromatography-mass spectrometry was used to conduct the protein corona analysis of α-KAM-Fe/Mg-CA using 10% FBS (fetal bovine serum) and mice plasma. Furthermore, to investigate the distribution of DOX-loaded α-KAM-Fe/Mg-CA NPs in major tissues and the tumor, a biodistribution investigation was conducted in mammary tumor-induced Balb/c mouse models 24 h after the intravenous administration of DOX-loaded α-KAM-Fe/Mg-CA NPs.

Results

The in vitro pH-dependent release of DOX over time demonstrated that α-KAM-Fe/Mg-CA NPs were pH-responsive and degraded rapidly at acidic pH levels. When compared to free DOX, the DOX-loaded α-KAM-Fe/Mg-CA NPs demonstrated a potent antiproliferative effect on breast cancer cells. Confocal microscopy confirmed the effective internalization of DOX-loaded α-KAM-Fe/Mg-CA NPs in breast cancer cells. The protein corona analysis revealed an affinity for dysopsonins (serum albumin, apolipoproteins) and transport proteins that may assist in extending their blood circulation period. Furthermore, biodistribution data of DOX-loaded α-KAM-Fe/Mg-CA NPs in the mammary tumor-induced Balb/c mouse model indicated extended circulation in the bloodstream, reduced non-target distribution in major tissues, and increased drug accumulation in the tumor.

Conclusion

The results obtained suggest that α-KAM-Fe/Mg-CA NPs may emerge as a prospective candidate for delivering therapeutic cargos to treat malignant mammary tumors.

The apoptotic efficacy of succinic acid on renal cancer cell lines

Recently, studies on the effects of non-toxic substances on cancer prophylaxis have gained value as an alternative to existing treatment options. Current studies have shown that succinic acid or its derivatives exhibit anticancer activity by inducing apoptosis. We aimed to investigate the anticancer activity of succinic acid on renal cancer for the first time in the literature. The cytotoxic activity of succinic acid on CAKI-2 and ACHN as renal cancer cell lines and MRC-5 as a healthy cell line was determined using the WST-1 cytotoxicity test. Apoptotic activity was measured by Annexin V test and cell death ELISA kit. The results showed that 25 μM and 50 μM doses of succinic acid for 24 h remarkably reduced the cell viability for CAKI-2 cells (89.77% and 90.77%) and ACHN cells (41.57% and 54.54%). Also, no significant effect was observed on the healthy cell line, as we expected. Additionally, administration of succinic acid at same doses resulted in apoptotic activity for ACHN cells (19.1 and 12.7) and CAKI-2 cells (19.85 and 29.55). ELISA results with same doses of succinic acid treatment increased the apoptotic fragment rates by 4.7 and 2.13-fold in CAKI-2 cells, and 32.92, 12.7-fold in ACHN cells. Succinic acid is a focal point for cancer treatments not only for its apoptotic success on cancer cells but also for its capacity to be metabolically active for humans. Our results suggest that succinic acid could be a potential therapeutic agent for individual cancer treatment approaches together with further molecular research.

Optimization and Formulation of Nanostructured and Self-Assembled Caseinate Micelles for Enhanced Cytotoxic Effects of Paclitaxel on Breast Cancer Cells

BACKGROUND

Paclitaxel (PTX) is a widely used anti-cancer drug for treating various types of solid malignant tumors including breast, ovarian and lung cancers. However, PTX has a low therapeutic response and is linked with acquired resistance, as well as a high incidence of adverse events, such as allergic reactions, neurotoxicity and myelosuppression. The situation is compounded when its complex chemical structure contributes towards hydrophobicity, shortening its circulation time in blood, causing off-target effects and limiting its therapeutic activity against cancer cells. Formulating a smart nano-carrier may overcome the solubility and toxicity issues of the drug and enable its more selective delivery to the cancerous cells. Among the nano-carriers, natural polymers are of great importance due to their excellent biodegradability, non-toxicity and good accessibility. The aim of the present research is to develop self-assembled sodium caseinate nanomicelles (NaCNs) with PTX loaded into the hydrophobic core of NaCNs for effective uptake of the drug in cancer cells and its subsequent intracellular release.

METHODS

The PTX-loaded micelle was characterized with high-performance liquid chromatography (HPLC), Fourier Transform Infrared Spectra (FTIR), High Resolution-Transmission Electron Microscope (HR-TEM), Field Emission Scanning Electron Microscope (FESEM) and Energy Dispersive X-Ray (EDX). Following treatment with PTX-loaded NaCNs, cell viability, cellular uptake and morphological changes were analyzed using MCF-7 and MDA-MB 231 human breast cancer cell lines.

RESULTS

We found that PTX-loaded NaCNs efficiently released PTX in an acidic tumor environment, while showing an enhanced cytotoxicity, cellular uptake and in-vivo anti-tumor efficacy in a mouse model of breast cancer when compared to free drug and blank micelles. Additionally, the nanomicelles also presented improved colloidal stability for three months at 4 °C and -20 °C and when placed at a temperature of 37 °C.

CONCLUSIONS

We conclude that the newly developed NaCNs is a promising carrier of PTX to enhance tumor accumulation of the drug while addressing its toxicity issues as well.

Molecular endoscopic imaging for the detection of Barrett's metaplasia using biodegradable inorganic nanoparticles: An ex-vivo pilot study on human tissue

BACKGROUND AND STUDY AIMS

Despite major technical advancements, endoscopic surveillance for detecting premalignant lesions in Barrett's esophagus is challenging because of their flat appearance with only subtle morphological changes. Molecular endoscopic imaging (MEI) using nanoparticles (NPs), coupled with fluorescently labeled antibody permits visualization of disease-specific molecular alterations. The aim of this ex vivo study was to assess the diagnostic applicability of MEI with NPs to detect Barrett's metaplasia.

PATIENTS AND METHODS

Seven patients undergoing endoscopic surveillance of known Barrett's esophagus were recruited. Freshly resected biopsy specimens were incubated with NPs coupled with FITC labeled Muc-2 antibodies and examined with MEI. Fluorescence intensity from Barrett's mucosa and control specimens were compared, followed by histological confirmation.

RESULTS

Fluorescence signals, indicating the presence of goblet cells, were noted for traditional MEI using Muc-2 antibodies in Barrett's intestinal metaplasia. Significantly stronger fluorescence signals were achieved with NPs coupled with FITC-conjugated Muc-2 antibodies. The results of MEI with NPs for the prediction of Barrett's metaplasia correlated with the final histopathological examination in all the cases.

CONCLUSIONS

Highly-specific NPs detected Barrett's metaplasia more efficiently than conventional MEI in this first feasibility study. MEI was as effective as standard histopathology for identifying Muc-2 containing goblet cells for diagnosis of Barrett's metaplasia. (DRKS-ID: DRKS00017747).

Characterization and Evaluation of Bone-Derived Nanoparticles as a Novel pH-Responsive Carrier for Delivery of Doxorubicin into Breast Cancer Cells

Background: The limitations of conventional treatment modalities in cancer, especially in breast cancer, facilitated the necessity for developing a safer drug delivery system (DDS). Inorganic nano-carriers based on calcium phosphates such as hydroxyapatite (HA) and carbonate apatite (CA) have gained attention due to their biocompatibility, reduced toxicity, and improved therapeutic efficacy. Methods: In this study, the potential of goose bone ash (GBA), a natural derivative of HA or CA, was exploited as a pH-responsive carrier to successfully deliver doxorubicin (DOX), an anthracycline drug into breast cancer cells (e.g., MCF-7 and MDA-MB-231 cells). GBA in either pristine form or in suspension was characterized in terms of size, morphology, functional groups, cellular internalization, cytotoxicity, pH-responsive drug (DOX) release, and protein corona analysis. Results: The pH-responsive drug release study demonstrated the prompt release of DOX from GBA through its disintegration in acidic pH (5.5–6.5), which mimics the pH of the endosomal and lysosomal compartments as well as the stability of GBA in physiological pH (pH 7.5). The result of DOX binding with GBA indicated an increment in binding affinity with increasing concentrations of DOX. Cell viability and cytotoxicity analysis showed no innate toxicity of GBA particles. Both qualitative and quantitative cellular uptake analysis in both cell lines displayed an enhanced cellular internalization of DOX-loaded GBA compared to free DOX molecules. The protein corona spontaneously formed on the surface of GBA particles exhibited its affinity toward transport proteins, structural proteins, and a few other selective proteins. The adsorption of transport proteins could extend the circulation half-life in biological environment and increase the accumulation of the drug-loaded NPs through the enhanced permeability and retention (EPR) effect at the tumor site. Conclusion: These findings highlight the potential of GBA as a DDS to successfully deliver therapeutics into breast cancer cells.

Fe/Mg-Modified Carbonate Apatite with Uniform Particle Size and Unique Transport Protein-Related Protein Corona Efficiently Delivers Doxorubicin into Breast Cancer Cells

Breast cancer is the abnormal, uncontrollable proliferation of cells in the breast. Conventional treatment modalities like chemotherapy induce deteriorating side effects on healthy cells. Non-viral inorganic nanoparticles (NPs) confer exclusive characteristics, such as, stability, controllable shape and size, facile surface modification, and unique magnetic and optical properties which make them attractive drug carriers. Among them, carbonate apatite (CA) particles are pH-responsive in nature, enabling rapid intracellular drug release, but are typically heterogeneous with the tendency to self-aggregate. Here, we modified the nano-carrier by partially substituting Ca²⁺ with Mg²⁺ and Fe³⁺ into a basic lattice structure of CA, forming Fe/Mg-carbonate apatite (Fe/Mg-CA) NPs with the ability to mitigate self-aggregation, form unique protein corona in the presence of serum and efficiently deliver doxorubicin (DOX), an anti-cancer drug into breast cancer cells. Two formulations of Fe/Mg-CA NPs were generated by adding different concentrations of Fe³⁺ and Mg²⁺ along with a fixed amount of Ca²⁺ in bicarbonate buffered DMEM (Dulbecco's Modified Eagle's Medium), followed by 30 min incubation at 37 °C. Particles were characterized by turbidity analysis, z-average diameter and zeta potential measurement, optical microscopy, field emission scanning electron microscopy (FESEM), Fourier transform infrared spectroscopy (FTIR), energy dispersive X-ray (EDX), flame atomic absorption spectroscopy (FAAS), pH dissolution, drug binding, cellular uptake, thiazolyl blue tetrazolium bromide (MTT) assay, stability analysis, and protein corona study by LCMS (Liquid chromatography-mass spectrometry). Both formulations of Fe/Mg-CA displayed mostly uniform nano-sized particles with less tendency to aggregate. The EDX and FAAS elemental analysis confirmed the weight (%) of Ca, Fe and Mg, along with their Ca/P ratio in the particles. A constant drug binding efficiency was noticed with 5 μM to 10 μM of initial DOX concentration. A pH dissolution study of Fe/Mg-CA NPs revealed the quick release of DOX in acidic pH. Enhancement of cytotoxicity for the chemotherapy drug was greater for Fe/Mg-CA NPs as compared to CA NPs, which could be explained by an increase in cellular internalization as a result of the small z-average diameter of the former. The protein corona study by LCMS demonstrated that Fe/Mg-CA NPs exhibited the highest affinity towards transport proteins without binding with opsonins. Biodistribution study was performed to study the effect of DOX-loaded Fe/Mg-CA NPs on the tissue distribution of DOX in Balb/c 4T1 tumor-bearing mice. Both formulations of Fe/Mg-CA NPs have significantly increased the accumulation of DOX in tumors. Interestingly, high Fe/Mg-CA NPs exhibited less off-target distribution compared to low Fe/Mg-CA NPs. Furthermore, the blood plasma analysis revealed prolonged blood circulation half-life of DOX-loaded low and high Fe/Mg-CA NPs compared to free DOX solution. Modifying CA NPs with Fe³⁺ and Mg²⁺, thereby, led to the generation of nano-sized particles with less tendency to aggregate, enhancing the drug binding efficiency, cellular uptake, and cytotoxicity without hampering drug release in acidic pH, while improving the circulation half-life and tumor accumulation of DOX. Therefore, Fe/Mg-CA which predominantly forms a transport protein-related protein corona could be a proficient carrier for therapeutic delivery in breast cancer.

Krebs Cycle Intermediate-Modified Carbonate Apatite Nanoparticles Drastically Reduce Mouse Tumor Burden and Toxicity by Restricting Broad Tissue Distribution of Anticancer Drugs

The morphology, size, and surface area of nanoparticles (NPs), with the existence of functional groups on their surface, contribute to the drug binding affinity, distribution of the payload in different organs, and targeting of a particular tumor for exerting effective antitumor activity in vivo. However, the inherent chemical structure of NPs causing unpredictable biodistribution with a toxic outcome still poses a serious challenge in clinical chemotherapy. In this study, carbonate apatite (CA), citrate-modified CA (CMCA) NPs, and α-ketoglutaric acid-modified CA (α-KAMCA) NPs were employed as carriers of anticancer drugs for antitumor, pharmacokinetic, and toxicological analysis in a murine breast cancer model. The results demonstrated almost five-fold enhanced tumor regression in the cyclophosphamide (CYP)-loaded α-KAMCA NP-treated group compared to the group treated with CYP only. Also, NPs promoted much higher drug accumulation in blood and tumor in comparison with the drug injected without a carrier. In addition, doxorubicin (DOX)-loaded NPs exhibited less accumulation in the heart, indicating less potential myocardial toxicity in mice compared to free DOX. Our findings, thus, conclude that CA, CMCA, and α-KAMCA NPs extended the circulation half-life and enhanced the anticancer effect with reduced toxicity of conventional chemotherapeutics in healthy organs, signifying that they are promising drug delivery devices in breast cancer treatment.

Magnesium Fluoride Forms Unique Protein Corona for Efficient Delivery of Doxorubicin into Breast Cancer Cells

Background: The efficacy of chemotherapy is undermined by adverse side effects and chemoresistance of target tissues. Developing a drug delivery system can reduce off-target side effects and increase the efficacy of drugs by increasing their accumulation in target tissues. Inorganic salts have several advantages over other drug delivery vectors in that they are non-carcinogenic and less immunogenic than viral vectors and have a higher loading capacity and better controlled release than lipid and polymer vectors. Methods: MgF₂ crystals were fabricated by mixing 20 mM MgCl₂ and 10 mM NaF and incubating for 30 min at 37 °C. The crystals were characterized by absorbance, dynamic light scattering, microscopic observance, pH sensitivity test, SEM, EDX and FTIR. The binding efficacy to doxorubicin was assessed by measuring fluorescence intensity. pH-dependent doxorubicin release profile was used to assess the controlled release capability of the particle-drug complex. Cellular uptake was assessed by fluorescence microscopy. Cytotoxicity of the particles and the drug-particle complex were assessed using MTT assay to measure cell viability of MCF-7 cells. Results and Discussion: Particle size on average was estimated to be <200 nm. The crystals were cubic in shape. The particles were pH-sensitive and capable of releasing doxorubicin in increasing acidic conditions. MgF₂ nanocrystals were safe in lower concentrations, and when bound to doxorubicin, enhanced its uptake. The protein corona formed around MgF₂ nanoparticles lacks typical opsonins but contains some dysopsonins. Conclusion: A drug delivery vector in the form of MgF₂ nanocrystals has been developed to transport doxorubicin into breast cancer cells. It is pH-sensitive (allowing for controlled release), size-modifiable, simple and cheap to produce.

α-Ketoglutaric Acid-Modified Carbonate Apatite Enhances Cellular Uptake and Cytotoxicity of a Raf- Kinase Inhibitor in Breast Cancer Cells through Inhibition of MAPK and PI-3 Kinase Pathways

AZ628 is a hydrophobic Raf-kinase inhibitor (rapidly accelerated fibrosarcoma) currently in clinical trial of various cancer. The physicochemical properties of hydrophobic drugs that affect the drug-particle interactions and cause aggregation of drugs and particles might be the key aspect to impede effective drug delivery. Retaining smaller particle size is the prerequisite to overcome the opsonization and improve cytotoxicity in the targeted region. Carbonate apatite (CA), an attractive biodegradable vector, has been used to carry both hydrophilic and hydrophobic drugs and release the payloads inside the cells following endocytosis. We incorporated AZ628 into CA and also modified it with α-ketoglutaric acid (α-KA) for reducing particle growth kinetics and increasing total surface area to improve the delivery of AZ628 by enhancing cellular uptake by breast cancer cells. AZ628-loaded nanoparticles of CA and α-KA-modified CA (α-KAMCA) were synthesized and evaluated in MCF-7 and 4T1 cell lines by measuring cytotoxicity and cellular uptake analysis. HPLC (high-performance liquid chromatography) assay was performed to quantify the binding affinity of the nanocarriers towards the drug. Western blot analysis was done to see the activation and expression levels of Akt, MAPK (mitogen-activated protein kinase) pathways and Caspase-3. Zetasizer was used to measure the particle size along with the surface charge. α-KAMCA showed almost 88% encapsulation efficacy for AZ628 with around 21% enhanced cellular uptake of the drug in two different breast cancer cell lines. These findings suggest that α-KAMCA could be a promising therapeutic tool to carry AZ628 for breast cancer treatment.