Reversal of doxorubicin resistance in breast cancer cells by photochemical internalization

Metal-organic framework-mediated siRNA delivery and sonodynamic therapy for precisely triggering ferroptosis and augmenting ICD in osteosarcoma

The complex genomics, immunosuppressive tumor microenvironment (TME), and chemotherapeutic resistance of osteosarcoma (OS) have resulted in limited therapeutic effects in the clinic. Ferroptosis is involved in tumor progression and is regulated mainly by glutathione peroxidase 4 (GPX4). Small interfering RNA (siRNA)-based RNA interference (RNAi) can precisely target any gene. However, achieving effective siRNA delivery is highly challenging. Here, we fabricated a TME-responsive metal-organic framework (MOF)-based biomimetic nanosystem (mFeP@si) with siGPX4 delivery and sonodynamic therapy (SDT) to treat OS by targeting ferroptosis. Under ultrasound (US) irradiation, mFeP@si achieves lysosomal escape via singlet oxygen (1O2)-mediated lysosomal membrane disruption and then accelerates ROS generation and glutathione (GSH) depletion. Meanwhile, siGPX4 silences GPX4 expression by binding to GPX4 mRNA and leads to the accumulation of toxic phospholipid hydroperoxides (PL-OOH), further magnifying the ROS storm and triggering ferroptosis. Notably, synergistic therapy remarkably enhances antitumor effects, improves the immunosuppressive TME by inducing potent immunogenic cell death (ICD), and increases the sensitivity of chemotherapy-resistant OS cells to cisplatin. Overall, this novel nanosystem, which targets ferroptosis by integrating RNAi and SDT, exhibits strong antitumor effects both in vitro and in vivo, providing new insights for treating OS.

Synergy between PEDF and Doxorubicin in Breast Cancer Cells: Effects on Metastatic and Metabolic Pathways

Pigment epithelium-derived factor (PEDF), a serine protease inhibitor (Serpin) family member, shows promise in inhibiting tumour growth. In our study, we explored the effects of PEDF on the efficacy of the frontline chemotherapy agent doxorubicin (Dox) in BC cells. We found that Dox+PEDF treatment significantly reduced glucose uptake in MDA-MB-231 cells compared to the control (p = 0.0005), PEDF (p = 0.0137), and Dox (p = 0.0171) alone but paradoxically increased it in MCF-7 cells. Our findings further revealed that PEDF, Dox, and Dox+PEDF substantially hindered tumour cell migration from tumour spheroids, with Dox+PEDF showing the most significant impact (p < 0.0001). We also observed notable decreases in the expression of metastatic markers (uPAR, uPA, CXCR4, MT1-MMP, TNF-α) across all treatment groups (p < 0.0001) in both cell lines. When it comes to metabolic pathways, PEDF increased phosphorylated IRS-1 (p-IRS1) levels in MDA-MB-231 and MCF-7 (p < 0.0001), while Dox decreased it, and the combination led to an increase. In MDA-MB-231 cells, treatment with PEDF, Dox, and the combination led to a notable decrease in both phosphorylated AKT (p-AKT) and total AKT levels. In MCF-7, while PEDF, Dox, and their combination led to a reduction in p-AKT, total levels of AKT increased in the presence of Dox and Dox+PEDF. Combining PEDF with Dox enhances the targeting of metastatic and metabolic pathways in breast cancer cell lines. This synergy, marked by PEDF's increasing roles in cancer control, may pave the way for more effective cancer treatments.

Characterization of resistant MCF-7 breast cancer cells developed by repeated cycles of photodynamic therapy

Breast cancer mainly affects women and causes a severe global threat to health. It is often managed and treated with surgery, chemotherapy, immunotherapy, and radiation therapy. Generally, chemotherapy as a treatment option is often opposed by responsive tumor relapse and development of resistance, a significant setback of current treatment. Photodynamic therapy (PDT) offers a promising modality that can treat cancer by combining a photosensitizer and laser irradiation in the presence of oxygen. However, one problem of PDT in treating breast cancer is the apparition of the resistant cell population. Thus, we aimed for stepwise selection and characterization of MCF-7 cells resistant to PDT with a sulfonated zinc phthalocyanine (ZnPcS4) photosensitizer. The wild-type MCF-7 was exposed to successive cycles of ZnPcS4-PDT, and 10resistant populations were finally obtained. In wild-type and parental cells, we analyzed the cell morphology (light microscopy), cell cycle (BrdU staining), cell viability (MTT assay), antioxidant activity (superoxide dismutase measurement), and immunofluorescence expression of resistant p-glycoprotein (P-gp). The results indicate that resistant cells showed a mesenchymal cell phenotype, few differences in antioxidant activity, an increased DNA synthesis, and more expression of P-gp than the wild-type parental cells. These distinctive features of resistant cells can provide insight into the emergence of MCF-7 cell resistance to PDT, which was necessary to design the best therapeutic procedure for improved efficacy.

Inhibition of glioma development by doxorubicin-photochemical internalization generated macrophage vaccine: a survival study in rats

BACKGROUND

The process known as immunogenic cell death (ICD) is characterized by dead and dying cancer cells exposing and releasing so-called damage associated molecular patterns (DAMPs). ICD has been shown to enhance the efficacy of antigen presenting cell (APC) immunotherapy. Both anthracycline drugs such as doxorubicin (DOX), and photodynamic therapy (PDT) have been shown to be inducers of ICD. It was therefore hypothesized that combined PDT and DOX i.e. photochemical internalization of DOX (DOX-PCI) would increase ICD compared to DOX acting as a single agent.

MATERIALS AND METHODS

F98 glioma cells were treated with DOX-PCI in vitro and the ICD markers HMGB1, HSP70, and HSP90 were determined by ELISA assay. Peritoneal macrophages (Ma), obtained from Fisher rats acting as APCs, were co-incubated with dead F98 glioma cells killed via DOX or DOX-PCI treatment ex vivo. The pulsed Ma (Ma ^DOX or Ma ^DOX-PCI) were used to inoculate the animals either before (preventive) or after (curative) intra-cranially implantation of the glioma cells.

RESULTS

F98 cells, treated with DOX-PCI in vitro, induced a significantly higher level of HGMB1, HSP70, and HSP90 than DOX acting alone. Ma ^DOX-PCI inoculated animals, in both preventive and curative protocols, had a pronounced survival benefit compared to either the non-treatment or Ma^DOX control groups. In the curative protocol, a second booster inoculation significantly improved survival, with 60% of the animals alive at day 60.

CONCLUSION

Macrophages primed with DOX-PCI treated glioma cells appeared to be highly effective as APCs and, when injected into host animals, could delay and, in some cases, prevent tumor development.

Cyclo-γ-polyglutamic acid-coated dual-responsive nanomicelles loaded with doxorubicin for synergistic chemo-photodynamic therapy

Nanodrug delivery systems have been used extensively to improve the tumor-targeting ability and reduce the side effects of anticancer drugs. In this study, nanomicelles responsive to dual stimuli were designed and developed as drug carriers for delivering doxorubicin (DOX). The hydrophobic group of the nanomicelles was composed of the photosensitizer protoporphyrin IX (PpIX) and the disulfide bond-containing alpha-lipoic acid (LA); the hydrophilic group was made up of the nuclear localization signal (NLS, CGGGPKKKRKVGG) peptide with a lysine linker. Furthermore, anionic cyclo-γ-polyglutamic acid (cyclo-γ-PGA) was coated on the surface of the cationic micelles to construct a multifunctional drug delivery system (NLS-LA-PpIX-DOX@cyclo-γ-PGA). Cyclo-γ-PGA, as a biological coating material, notably improved the stability of the cationic micelles by reducing nonspecific reactions with anionic groups. Additionally, the cyclo-γ-PGA coating mediated active tumor targeting and enhanced the cellular uptake of micelles via the γ-glutamyl transpeptidase (GGT) pathway. The integrated micelles not only achieved photochemical internalization (PCI) and photodynamic therapy (PDT) via light-activated reactive oxygen species (ROS) but also realized controlled intracellular drug release via the glutathione (GSH)-responsive disulfide-bond cleavage. As a result, NLS-LA-PpIX-DOX@cyclo-γ-PGA exhibited excellent synergistic chemo-photodynamic antitumor activity and fewer side effects than other therapies both in vitro and in vivo. In conclusion, this new dual-responsive drug delivery system (NLS-LA-PpIX-DOX@cyclo-γ-PGA) with improved stability and enhanced tumor-targeting ability may facilitate the development of high-efficiency and low-toxicity nanotherapeutic approaches.

The role of endolysosomal trafficking in anticancer drug resistance

Multidrug resistance (MDR) remains a major obstacle towards curative treatment of cancer. Despite considerable progress in delineating the basis of intrinsic and acquired MDR, the underlying molecular mechanisms remain to be elucidated. Emerging evidences suggest that dysregulation in endolysosomal compartments is involved in mediating MDR through multiple mechanisms, such as alterations in endosomes, lysosomes and autophagosomes, that traffic and biodegrade the molecular cargo through macropinocytosis, autophagy and endocytosis. For example, altered lysosomal pH, in combination with transcription factor EB (TFEB)-mediated lysosomal biogenesis, increases the sequestration of hydrophobic anti-cancer drugs that are weak bases, thereby producing an insufficient and off-target accumulation of anti-cancer drugs in MDR cancer cells. Thus, the use of well-tolerated, alkalinizing compounds that selectively block Vacuolar H⁺-ATPase (V-ATPase) may be an important strategy to overcome MDR in cancer cells and increase chemotherapeutic efficacy. Other mechanisms of endolysosomal-mediated drug resistance include increases in the expression of lysosomal proteases and cathepsins that are involved in mediating carcinogenesis and chemoresistance. Therefore, blocking the trafficking and maturation of lysosomal proteases or direct inhibition of cathepsin activity in the cytosol may represent novel therapeutic modalities to overcome MDR. Furthermore, endolysosomal compartments involved in catabolic pathways, such as macropinocytosis and autophagy, are also shown to be involved in the development of MDR. Here, we review the role of endolysosomal trafficking in MDR development and discuss how targeting endolysosomal pathways could emerge as a new therapeutic strategy to overcome chemoresistance in cancer.

Nanomedicines for combating multidrug resistance of cancer

Chemotherapy typically involves the use of specific chemodrugs to inhibit the proliferation of cancer cells, but the frequent emergence of a variety of multidrug-resistant cancer cells poses a tremendous threat to our combat against cancer. The fundamental causes of multidrug resistance (MDR) have been studied for decades, and can be generally classified into two types: one is associated with the activation of diverse drug efflux pumps, which are responsible for translocating intracellular drug molecules out of the cells; the other is linked with some non-efflux pump-related mechanisms, such as antiapoptotic defense, enhanced DNA repair ability, and powerful antioxidant systems. To overcome MDR, intense efforts have been made to develop synergistic therapeutic strategies by introducing MDR inhibitors or combining chemotherapy with other therapeutic modalities, such as phototherapy, gene therapy, and gas therapy, in the hope that the drug-resistant cells can be sensitized toward chemotherapeutics. In particular, nanotechnology-based drug delivery platforms have shown the potential to integrate multiple therapeutic agents into one system. In this review, the focus was on the recent development of nanostrategies aiming to enhance the efficiency of chemotherapy and overcome the MDR of cancer in a synergistic manner. Different combinatorial strategies are introduced in detail and the advantages as well as underlying mechanisms of why these strategies can counteract MDR are discussed. This review is expected to shed new light on the design of advanced nanomedicines from the angle of materials and to deepen our understanding of MDR for the development of more effective anticancer strategies. This article is categorized under: Nanotechnology Approaches to Biology > Nanoscale Systems in Biology Therapeutic Approaches and Drug Discovery > Nanomedicine for Oncologic Disease.

Identification of potential therapeutic target of naringenin in breast cancer stem cells inhibition by bioinformatics and in vitro studies

Cancer therapy is a strategic measure in inhibiting breast cancer stem cell (BCSC) pathways. Naringenin, a citrus flavonoid, was found to increase breast cancer cells' sensitivity to chemotherapeutic agents. Bioinformatics study and 3D tumorsphere in vitro modeling in breast cancer (mammosphere) were used in this study, which aims to explore the potential therapeutic targets of naringenin (PTTNs) in inhibiting BCSCs. Bioinformatic analyses identified direct target proteins (DTPs), indirect target proteins (ITPs), naringenin-mediated proteins (NMPs), BCSC regulatory genes, and PTTNs. The PTTNs were further analyzed for gene ontology, Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment, protein-protein interaction (PPI) networks, and hub protein selection. Mammospheres were cultured in serum-free media. The effects of naringenin were measured by MTT-based cytotoxicity, mammosphere forming potential (MFP), colony formation, scratch wound-healing assay, and flow cytometry-based cell cycle analyses and apoptosis assays. Gene expression analysis was performed using real-time quantitative polymerase chain reaction (q-RT PCR). Bioinformatics analysis revealed p53 and estrogen receptor alpha (ERα) as PTTNs, and KEGG pathway enrichment analysis revealed that TGF-ß and Wnt/ß-catenin pathways are regulated by PTTNs. Naringenin demonstrated cytotoxicity and inhibited mammosphere and colony formation, migration, and epithelial to mesenchymal transition in the mammosphere. The mRNA of tumor suppressors P53 and ERα were downregulated in the mammosphere, but were significantly upregulated upon naringenin treatment. By modulating the P53 and ERα mRNA, naringenin has the potential of inhibiting BCSCs. Further studies on the molecular mechanism and formulation of naringenin in BCSCs would be beneficial for its development as a BCSC-targeting drug.

Synergy between Photodynamic Therapy and Dactinomycin Chemotherapy in 2D and 3D Ovarian Cancer Cell Cultures

In this study we explored the efficacy of combining low dose photodynamic therapy using a porphyrin photosensitiser and dactinomycin, a commonly used chemotherapeutic agent. The studies were carried out on compressed collagen 3D constructs of two human ovarian cancer cell lines (SKOV3 and HEY) versus their monolayer counterparts. An amphiphilc photosensitiser was employed, disulfonated tetraphenylporphine, which is not a substrate for ABC efflux transporters that can mediate drug resistance. The combination treatment was shown to be effective in both monolayer and 3D constructs of both cell lines, causing a significant and synergistic reduction in cell viability. Compared to dactinomycin alone or PDT alone, higher cell kill was found using 2D monolayer culture vs. 3D culture for the same doses. In 3D culture, the combination therapy resulted in 10 and 22 times higher cell kill in SKOV3 and HEY cells at the highest light dose compared to dactinomycin monotherapy, and 2.2 and 5.5 times higher cell kill than PDT alone. The combination of low dose PDT and dactinomycin appears to be a promising way to repurpose dactinomycin and widen its therapeutic applications.

Doxorubicin Assisted by Microsecond Electroporation Promotes Irreparable Morphological Alternations in Sensitive and Resistant Human Breast Adenocarcinoma Cells

Electroporation increases the transmembrane transport of molecules. The combination of electric pulses with cytostatic compounds is beneficial for cancer treatment. Doxorubicin (DOX) is a commonly used chemotherapeutic anticancer drug. Its fluorescence properties enable the investigation of drug distribution and metabolism. In this study, doxorubicin was enhanced by electroporation to eliminate cancer cells more effectively. The influence of electroporation on the drug uptake was evaluated in two cell lines: MCF-7/WT and MCF-7/DOX. The intracellular localization of doxorubicin and its impact on the intracellular structure organization were examined under a confocal microscope. Cellular effects were examined with the 3(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) test that estimates the rate of metabolism in viable cells. The ultrastructure (TEM) of tumor cells subjected to the electric field was analyzed. An enhanced doxorubicin efficacy was observed in MCF-7/DOX cells after combination with electroporation. The response of the resistant cell line was revealed to be more sensitive to electric pulses. Electroporation-based methods may be attractive for cancer treatment in human breast adenocarcinoma, especially with acquired resistance. Electroporation enables a reduction of the effective dose of the drugs and the exposure time in this type of cancer, diminishing side effects of the systemic therapy.

Photochemical Internalization for Intracellular Drug Delivery. From Basic Mechanisms to Clinical Research

Photochemical internalisation (PCI) is a unique intervention which involves the release of endocytosed macromolecules into the cytoplasmic matrix. PCI is based on the use of photosensitizers placed in endocytic vesicles that, following light activation, lead to rupture of the endocytic vesicles and the release of the macromolecules into the cytoplasmic matrix. This technology has been shown to improve the biological activity of a number of macromolecules that do not readily penetrate the plasma membrane, including type I ribosome-inactivating proteins (RIPs), gene-encoding plasmids, adenovirus and oligonucleotides and certain chemotherapeutics, such as bleomycin. This new intervention has also been found appealing for intracellular delivery of drugs incorporated into nanocarriers and for cancer vaccination. PCI is currently being evaluated in clinical trials. Data from the first-in-human phase I clinical trial as well as an update on the development of the PCI technology towards clinical practice is presented here.

Photochemically-Induced Release of Lysosomal Sequestered Sunitinib: Obstacles for Therapeutic Efficacy

Lysosomal accumulation of sunitinib has been suggested as an underlying mechanism of resistance. Here, we investigated if photochemical internalization (PCI), a technology for cytosolic release of drugs entrapped in endosomes and lysosomes, would activate lysosomal sequestered sunitinib. By super-resolution fluorescence microscopy, sunitinib was found to accumulate in the membrane of endo/lysosomal compartments together with the photosensitizer disulfonated tetraphenylchlorin (TPCS_2a). Furthermore, the treatment effect was potentiated by PCI in the human HT-29 and the mouse CT26.WT colon cancer cell lines. The cytotoxic outcome of sunitinib-PCI was, however, highly dependent on the treatment protocol. Thus, neoadjuvant PCI inhibited lysosomal accumulation of sunitinib. PCI also inhibited lysosomal sequestering of sunitinib in HT29/SR cells with acquired sunitinib resistance, but did not reverse the resistance. The mechanism of acquired sunitinib resistance in HT29/SR cells was therefore not related to lysosomal sequestering. Sunitinib-PCI was further evaluated on HT-29 xenografts in athymic mice, but was found to induce only a minor effect on tumor growth delay. In immunocompetent mice sunitinib-PCI enhanced areas of treatment-induced necrosis compared to the monotherapy groups. However, the tumor growth was not delayed, and decreased infiltration of CD3-positive T cells was indicated as a possible mechanism behind the failed overall response.

The intracellular redox environment modulates the cytotoxic efficacy of single and combination chemotherapy in breast cancer cells using photochemical internalisation

The redox environment modulates photochemical internalization of an entrapped cytotoxic agent. Administration of light depicted by jagged arrow.

Establishment of 2D Cell Cultures Derived From 3D MCF-7 Spheroids Displaying a Doxorubicin Resistant Profile

In vitro 3D cancer spheroids generally exhibit a drug resistance profile similar to that found in solid tumors. Due to this property, these models are an appealing for anticancer compounds screening. Nevertheless, the techniques and methods aimed for drug discovery are mostly standardized for cells cultured in 2D. The development of 2D cell culture models displaying a drug resistant profile is required to mimic the in vivo tumors, while the equipment, techniques, and methodologies established for conventional 2D cell cultures can continue to be employed in compound screening. In this work, the response of 3D-derived MCF-7 cells subsequently cultured in 2D in medium supplemented with glutathione (GSH) (antioxidant agent found in high levels in breast cancer tissues and a promoter of cancer cells resistance) to Doxorubicin (DOX) is evaluated. These cells demonstrated a resistance toward DOX closer to that displayed by 3D spheroids, which is higher than that exhibited by standard 2D cell cultures. In fact, the 50% inhibitory concentration (IC₅₀ ) of DOX in 3D-derived MCF-7 cell cultures supplemented with GSH is about eight-times higher than that obtained for conventional 2D cell cultures (cultured without GSH), and is only about two-times lower than that attained for 3D MCF-7 spheroids (cultured without GSH). Further investigation revealed that this improved resistance of 3D-derived MCF-7 cells may result from their increased P-glycoprotein (P-gp) activity and reduced production of intracellular reactive oxygen species (ROS).

Enhanced targeting of triple-negative breast carcinoma and malignant melanoma by photochemical internalization of CSPG4-targeting immunotoxins

Triple-negative breast cancer (TNBC) and malignant melanoma are highly aggressive cancers that widely express the cell surface chondroitin sulfate proteoglycan 4 (CSPG4/NG2). CSPG4 plays an important role in tumor cell growth and survival and promotes chemo- and radiotherapy resistance, suggesting that CSPG4 is an attractive target in cancer therapy. In the present work, we applied the drug delivery technology photochemical internalization (PCI) in combination with the novel CSPG4-targeting immunotoxin 225.28-saporin as an efficient and specific strategy to kill aggressive TNBC and amelanotic melanoma cells. Light-activation of the clinically relevant photosensitizer TPCS2a (fimaporfin) and 225.28-saporin was found to act in a synergistic manner, and was superior to both PCI of saporin and PCI-no-drug (TPCS2a + light only) in three TNBC cell lines (MDA-MB-231, MDA-MB-435 and SUM149) and two BRAFV600E mutated malignant melanoma cell lines (Melmet 1 and Melmet 5). The cytotoxic effect was highly dependent on the light dose and expression of CSPG4 since no enhanced cytotoxicity of PCI of 225.28-saporin compared to PCI of saporin was observed in the CSPG4-negative MCF-7 cells. The PCI of a smaller, and clinically relevant CSPG4-targeting toxin (scFvMEL-rGel) validated the CSPG4-targeting concept in vitro and induced a strong inhibition of tumor growth in the amelanotic melanoma xenograft A-375 model. In conclusion, the combination of the drug delivery technology PCI and CSPG4-targeting immunotoxins is an efficient, specific and light-controlled strategy for the elimination of aggressive cells of TNBC and malignant melanoma origin. This study lays the foundation for further preclinical evaluation of PCI in combination with CSPG4-targeting.

Is senescence-associated β-galactosidase a marker of neuronal senescence?

One of the features of cellular senescence is the activity of senescence-associated- β-galactosidase (SA-β-gal). The main purpose of this study was to evaluate this marker of senescence in aging neurons. We found that cortical neurons exhibited noticeable SA-β-gal activity quite early in culture. Many SA-β-gal-positive neurons were negative for another canonical marker of senescence, namely, double-strand DNA breaks (DSBs). Moreover, DDR signalling triggered by low doses of doxorubicin did not accelerate the appearance of neuronal SA-β-gal. In vivo, we observed pronounced induction of SA-β-gal activity in the hippocampus of 24-month-old mice, which is consistent with previous findings and supports the view that at this advanced age neurons developed a senescence-like phenotype. Surprisingly however, relatively high SA-β-gal activity, probably unrelated to the senescence process, was also observed in much younger, 3-month-old mice. In conclusion, we propose that SA-β-gal activity in neurons cannot be attributed uniquely to cell senescence either in vitro or in vivo. Additionally, we showed induction of REST protein in aging neurons in long-term culture and we propose that REST could be a marker of neuronal senescence in vitro.

Photochemical internalization enhanced macrophage delivered chemotherapy

BACKGROUND

Macrophage (Ma) vectorization of chemotherapeutic drugs has the advantage for cancer therapy in that it can actively target and maintain an elevated concentration of drugs at the tumor site, preventing their spread into healthy tissue. A potential drawback is the inability to deliver a sufficient number of drug-loaded Ma into the tumor, thus limiting the amount of active drug delivered. This study examined the ability of photochemical internalization (PCI) to enhance the efficacy of released drug by Ma transport.

METHODS

Tumor spheroids consisting of either F98 rat glioma cells or F98 cells combined with a subpopulation of empty or doxorubicin (DOX)-loaded mouse Ma (RAW264.7) were used as in vitro tumor models. PCI was performed with the photosensitizer AlPcS_2a and laser irradiation at 670 nm.

RESULTS

RAW264.7 Ma pulsed with DOX released the majority of the incorporated DOX within two hours of incubation. PCI significantly increased the toxicity of DOX either as pure drug or derived from monolayers of DOX-loaded Ma. Significant growth inhibition of hybrid spheroids was also observed with PCI even at subpopulations of DOX-loaded Ma as low as 11% of the total initial hybrid spheroid cell number.

CONCLUSION

Results show that RAW264.7 Ma, pulsed with DOX, could effectively incorporate and release DOX. PCI significantly increased the ability of both free and Ma-released DOX to inhibit the growth of tumor spheroids in vitro. The growth of F98 + DOX loaded Ma hybrid spheroids were synergistically reduced by PCI, compared to either photodynamic therapy or released DOX acting alone.

Enhancing Photochemical Internalization of DOX through a Porphyrin-based Amphiphilic Block Copolymer

Drug resistance is a primary obstacle that seriously reduces the therapy efficiency of most chemotherapeutic agents. To address this issue, the photochemical internalization (PCI) was employed to help the anticancer drug escape from lysosome and improve their translocation to the nucleus. A pH-sensitive porphyrin-based amphiphilic block copolymer (PEG₁₁₃-b-PCL₅₄-a-porphyrin) was synthesized, which was acted not only as a carrier for the delivery of DOX but also as a photosensitizer for PCI. PEG₁₁₃-b-PCL₅₄-a-porphyrin as a drug carrier exhibited a higher drug loading capacity, entrapment efficiency, and DOX release content. The PCI effect of PEG₁₁₃-b-PCL₅₄-a-porphyrin was studied by confocal laser scanning microscopy, and the results showed that most of DOX could be translocated into the nucleus for DOX-loaded PEG₁₁₃-b-PCL₅₄-a-porphyrin micelles. Moreover, the IC₅₀ of pH-sensitive DOX-loaded PEG₁₁₃-b-PCL₅₄-a-porphyrin micelles was much lower than that of its counterpart without pH-responsiveness, DOX-loaded PEG₁₁₃-b-PCL₅₄-porphyrin micelles. Therefore, this drug delivery system based on pH-sensitive porphyrin-containing block copolymer would act as a potential vehicle for overcoming drug resistance in chemotherapy.

Homeobox B4 inhibits breast cancer cell migration by directly binding to StAR-related lipid transfer domain protein 13

The present study aimed to investigate the role of homeobox B4 (HOXB4) in breast cancer. Analysis of The Cancer Genome Atlas data revealed that HOXB4 expression was positively associated with expression of the StAR-related lipid transfer domain protein 13 (STARD13), and the overall survival of patients with breast cancer. Immunohistochemistry and quantitative polymerase chain reaction assays demonstrated that HOXB4 expression was downregulated in breast cancer tissues compared with adjacent normal tissues and was additionally positively associated with STARD13 expression. HOXB4 promoted STARD13 expression in breast cancer cells. Chromatin immunoprecipitation and luciferase reporter assays confirmed that HOXB4 directly bound to the STARD13 promoter. Additionally, HOXB4 inhibited breast cancer cell migration and the epithelial-mesenchymal transition through the STARD13/Ras homolog (Rho) family member A/Rho associated protein kinase signaling pathway. HOXB4 overexpression enhanced the sensitivity of breast cancer cells to doxorubicin and reversed resistance in doxorubicin-resistant cells. Overall, the results indicated that HOXB4 inhibited breast cancer cell migration and enhanced the sensitivity of breast cancer cells to doxorubicin by targeting STARD13.

Sensitive Electrochemical Detection of Nitric Oxide Release from Cardiac and Cancer Cells via a Hierarchical Nanoporous Gold Microelectrode

The importance of nitric oxide (NO) in many biological processes has garnered increasing research interest in the design and development of efficient technologies for the sensitive detection of NO. Here we report on a novel gold microelectrode with a unique three-dimensional (3D) hierarchical nanoporous structure for the electrochemical sensing of NO, which was fabricated via a facile electrochemical alloying/dealloying method. Following the treatment, the electrochemically active surface area (ECSA) of the gold microelectrode was significantly increased by 22.9 times. The hierarchical nanoporous gold (HNG) microelectrode exhibited excellent performance for the detection of NO with high stability. On the basis of differential pulse voltammetry (DPV) and amperometric techniques, the obtained sensitivities were 21.8 and 14.4 μA μM^-1 cm^-2, with detection limits of 18.1 ± 1.22 and 1.38 ± 0.139 nM, respectively. The optimized HNG microelectrode was further utilized to monitor the release of NO from different cells, realizing a significant differential amount of NO generated from the normal and stressed rat cardiac cells as well as from the untreated and treated breast cancer cells. The HNG microelectrode developed in the present study may provide an effective platform in monitoring NO in biological processes and would have a great potential in the medical diagnostics.

Phthalocyanine induced phototherapy coupled with Doxorubicin; a promising novel treatment for breast cancer

INTRODUCTION

Globally, breast cancer is the most common life-threatening malignant disease among women. Adjuvant chemotherapeutic treatment of anthracycline-based chemotherapy (e.g., doxorubicin) has been shown to be more advantageous over non-anthracycline-based therapies, yet possess the tenacity of developing resistance and potential side effects which have limited its use in the clinical setting. These reasons necessitate combining doxorubicin with emerging photodynamic treatment regimens. Areas covered: In this review, the authors have concisely explained doxorubicin chemotherapy and the photobiological processes of phthalocyanine triggered photodynamic therapy (PDT). A literature search was conducted and reports demonstrating the use of doxorubicin and photodynamic therapy as a treatment modality for breast cancer were identified. More emphasis was made on studies demonstrating the efficacy and improved anticancer effect of combining chemotherapy with photodynamic therapy. However, it was concluded that for this combination therapy, still in it's infancy, it could be relevant when integrated into standard treatment. Expert Commentary: To these effects, comprehensive models based on experimental evaluations are needed for rational design of anthracycline-based chemotherapy and PDT to be integrated into the clinical setting.

Disulfonated tetraphenyl chlorin (TPCS2a)-induced photochemical internalisation of bleomycin in patients with solid malignancies: a phase 1, dose-escalation, first-in-man trial

BACKGROUND

Photochemical internalisation, a novel minimally invasive treatment, has shown promising preclinical results in enhancing and site-directing the effect of anticancer drugs by illumination, which initiates localised chemotherapy release. We assessed the safety and tolerability of a newly developed photosensitiser, disulfonated tetraphenyl chlorin (TPCS2a), in mediating photochemical internalisation of bleomycin in patients with advanced and recurrent solid malignancies.

METHODS

In this phase 1, dose-escalation, first-in-man trial, we recruited patients (aged ≥18 to <85 years) with local recurrent, advanced, or metastatic cutaneous or subcutaneous malignancies who were clinically assessed as eligible for bleomycin chemotherapy from a single centre in the UK. Patients were given TPCS2a on day 0 by slow intravenous injection, followed by a fixed dose of 15 000 IU/m(2) bleomycin by intravenous infusion on day 4. After 3 h, the surface of the target tumour was illuminated with 652 nm laser light (fixed at 60 J/cm(2)). The TPCS2a starting dose was 0·25 mg/kg and was then escalated in successive dose cohorts of three patients (0·5, 1·0, and 1·5 mg/kg). The primary endpoints were safety and tolerability of TPCS2a; other co-primary endpoints were dose-limiting toxicity and maximum tolerated dose. The primary analysis was per protocol. This study is registered with ClinicalTrials.gov, number NCT00993512, and has been completed.

FINDINGS

Between Oct 3, 2009, and Jan 14, 2014, we recruited 22 patients into the trial. 12 patients completed the 3-month follow-up period. Adverse events related to photochemical internalisation were either local, resulting from the local inflammatory process, or systemic, mostly as a result of the skin-photosensitising effect of TPCS2a. The most common grade 3 or worse adverse events were unexpected higher transient pain response (grade 3) localised to the treatment site recorded in nine patients, and respiratory failure (grade 4) noted in two patients. One dose-limiting toxicity was reported in the 1·0 mg/kg cohort (skin photosensitivity [grade 2]). Dose-limiting toxicities were reported in two of three patients at a TPCS2a dose of 1·5 mg/kg (skin photosensitivity [grade 3] and wound infection [grade 3]); thus, the maximum tolerated dose of TPCS2a was 1·0 mg/kg. Administration of TPCS2a was found to be safe and tolerable by all patients. No deaths related to photochemical internalisation treatment occurred.

INTERPRETATION

TPCS2a-mediated photochemical internalisation of bleomycin is safe and tolerable. We identified TPCS2a 0·25 mg/kg as the recommended treatment dose for future trials.

FUNDING

PCI Biotech.

AGPAT9 suppresses cell growth, invasion and metastasis by counteracting acidic tumor microenvironment through KLF4/LASS2/V-ATPase signaling pathway in breast cancer

Human 1-acylglycerol-3-phosphate O-acyltransferase 9 (AGPAT9) is the gene identified from adipose tissue in 2007. We found AGPAT9 expression was significantly higher in poorly invasive MCF7 human breast cancer cells than the highly invasive MDA-MB-231 cells. AGPAT9 significantly inhibited the proliferation of breast cancer cells in vitro and in vivo. Live-cell imaging and transwell assays showed that AGPAT9 could significantly inhibit the migration and invasive capacities of breast cancer cells. The inhibitory effect of AGPAT9 on metastasis was also observed in vivo in lung metastasis model. AGPAT9 inhibited breast cancer cell proliferation, migration and invasion through, at least in part, suppressing the V-ATPase activity. In addition, increased AGPAT9 expression in MCF-7/ADR cells could increase the chemosensitivity to doxorubicin (Dox). Our findings suggest that increasing AGPAT9 expression may be a new approach that can be used for breast cancer treatment.

Chemical Reactivity Window Determines Prodrug Efficiency toward Glutathione Transferase Overexpressing Cancer Cells

Glutathione transferases (GSTs) are often overexpressed in tumors and frequently correlated to bad prognosis and resistance against a number of different anticancer drugs. To selectively target these cells and to overcome this resistance we previously have developed prodrugs that are derivatives of existing anticancer drugs (e.g., doxorubicin) incorporating a sulfonamide moiety. When cleaved by GSTs, the prodrug releases the cytostatic moiety predominantly in GST overexpressing cells, thus sparing normal cells with moderate enzyme levels. By modifying the sulfonamide it is possible to control the rate of drug release and specifically target different GSTs. Here we show that the newly synthesized compounds, 4-acetyl-2-nitro-benzenesulfonyl etoposide (ANS-etoposide) and 4-acetyl-2-nitro-benzenesulfonyl doxorubicin (ANS-DOX), function as prodrugs for GSTA1 and MGST1 overexpressing cell lines. ANS-DOX, in particular, showed a desirable cytotoxic profile by inducing toxicity and DNA damage in a GST-dependent manner compared to control cells. Its moderate conversion of 500 nmol/min/mg, as catalyzed by GSTA1, seems hereby essential since the more reactive 2,4-dinitrobenzenesulfonyl doxorubicin (DNS-DOX) (14000 nmol/min/mg) did not display a preference for GSTA1 overexpressing cells. DNS-DOX, however, effectively killed GSTP1 (20 nmol/min/mg) and MGST1 (450 nmol/min/mg) overexpressing cells as did the less reactive 4-mononitrobenzenesulfonyl doxorubicin (MNS-DOX) in a MGST1-dependent manner (1.5 nmol/min/mg) as shown previously. Furthermore, we show that the mechanism of these prodrugs involves a reduction in GSH levels as well as inhibition of the redox regulatory enzyme thioredoxin reductase 1 (TrxR1) by virtue of their electrophilic sulfonamide moiety. TrxR1 is upregulated in many tumors and associated with resistance to chemotherapy and poor patient prognosis. Additionally, the prodrugs potentially acted as a general shuttle system for DOX, by overcoming resistance mechanisms in cells. Here we propose that GST-dependent prodrugs require a conversion rate "window" in order to selectively target GST overexpressing cells, while limiting their effects on normal cells. Prodrugs are furthermore a suitable system to specifically target GSTs and to overcome various drug resistance mechanisms that apply to the parental drug.

Nanoparticle-mediated drug delivery for treating melanoma

Melanoma originated from melanocytes is the most aggressive type of skin cancer with limited treatment options. New targeted therapeutic options with the discovery of BRAF and MEK inhibitors have shown significant survival benefits. Despite the recent progress, development of chemoresistance and systemic toxicity remains a challenge for treating metastatic melanoma. While the response from the first line of treatment against melanoma using dacarbazine remains only 5-10%, the prolonged use of targeted therapy against mutated oncogene BRAF develops chemoresistance. In this review, we will discuss the nanoparticle-based strategies for encapsulation and conjugation of drugs to the polymer for maximizing their tumor distribution through enhanced permeability and retention effect. We will also highlight photodynamic therapy and design of melanoma-targeted nanoparticles.

Enhancing the efficacy of cytotoxic agents for cancer therapy using photochemical internalisation

Photochemical internalisation (PCI) is a technique for improving cellular delivery of certain bioactive agents which are prone to sequestration within endolysosomes. There is a wide range of agents suitable for PCI‐based delivery including toxins, oligonucleotides, genes and immunoconjugates which demonstrates the versatility of this technique. The basic mechanism of PCI involves triggering release of the agent from endolysosomes within the target cells using a photosensitiser which is selectively retained with the endolysosomal membranes. Excitation of the photosensitiser by visible light leads to disruption of the membranes via photooxidative damage thereby releasing the agent into the cytosol. This treatment enables the drugs to reach their intended subcellular target more efficiently and improves their efficacy. In this review we summarise the applications of this technique with the main emphasis placed on cancer chemotherapy.

Photochemical activation of drugs for the treatment of therapy-resistant cancers

Resistance to chemotherapy, molecular targeted therapy as well as radiation therapy is a major obstacle for cancer treatment.

Photochemical internalisation, a minimally invasive strategy for light-controlled endosomal escape of cancer stem cell-targeting therapeutics

Despite progress in radio-, chemo- and photodynamic-therapy (PDT) of cancer, treatment resistance still remains a major problem for patients with aggressive tumours.

Circumvention of resistance to photodynamic therapy in doxorubicin-resistant sarcoma by photochemical internalization of gelonin

A wide range of anti-cancer therapies have been shown to induce resistance upon repetitive treatment and such adapted resistance may also cause cross-resistance to other treatment modalities. We here show that MES-SA/Dx5 cells with adapted resistance to doxorubicin (DOX) are cross-resistant to photodynamic therapy (PDT). A DOX-induced increased expression of the reactive oxygen species (ROS)-scavenging proteins glutathione peroxidase (GPx) 1 and GPx4 in MES-SA/Dx5 cells was indicated as the mechanism of resistance to PDT in line with the reduction in PDT-generated ROS observed in this cell line. ROS-induced p38 activation was, in addition, shown to be reduced to one-third of the signal of the parental MES-SA cells 2h after PDT, and addition of the p38 inhibitor SB203580 confirmed p38 activation as a death signal after PDT in the MES-SA cells. The MES-SA/Dx5 cells were also cross-resistant to ionizing radiation in agreement with the increased GPx1 and GPx4 expression. Surprisingly, PDT-induced endo/lysosomal release of the ribosome-inactivating protein gelonin (photochemical internalization (PCI)) was more effective in the PDT-resistant MES-SA/Dx5 cells, as measured by synergy calculations in both cell lines. Analysis of death-inducing signaling indicated a low activation of caspase-3 and a strong PARP I cleavage after PDT and PCI in both cell lines. The PARP I activation was, however, stronger after PCI than after PDT in the MES-SA cells, but not in the MES-SA/Dx5 cells, and therefore cannot explain the strong PCI effect in the MES-SA/Dx5 cells. In conclusion PCI of recombinant gelonin circumvents ROS resistance in an apoptosis-independent manner.

Photodynamic therapy for photochemists

Photodynamic therapy (PDT) is an evolving technique for localized control of diseased tissue with light after prior administration of a photosensitizing agent and in the presence of oxygen. The biological effect is quite different from surgery, radiotherapy and chemotherapy. With no temperature change during treatment, connective tissues like collagen are largely unaffected, so maintaining the mechanical integrity of hollow organs. PDT is of particular value for pre-cancer and early cancers of the skin (not melanomas) and mouth as the cosmetic and functional results are so good. Another key indication is for small areas of cancer that are unsuitable for or have persisted or recurred after conventional management. It can be applied in areas already exposed to the maximum safe dose of radiotherapy. Outside cancer, in ophthalmology, it is established for age-related macular degeneration, and has considerable potential in arterial disease for preventing restenosis after balloon angioplasty and in the treatment of infectious diseases, where the responsible organisms are accessible to both the photosensitizer and light. New developments on the horizon include techniques for increasing the selectivity for cancers, such as coupling photosensitizers to antibodies, and for stimulating immunological responses, but many further pre-clinical and clinical studies are needed to establish PDT's role in routine clinical practice.

Sequestration of AS-DACA into acidic compartments of the membrane trafficking system as a mechanism of drug resistance in rhabdomyosarcoma

The accumulation of weakly basic drugs into acidic organelles has recently been described as a contributor to resistance in childhood cancer rhabdomyosarcoma (RMS) cell lines with differential sensitivity to a novel topoisomerase II inhibitor, AS-DACA. The current study aims to explore the contribution of the endocytic pathway to AS-DACA sequestration in RMS cell lines. A 24-fold differential in AS-DACA cytotoxicity was detected between the RMS lines RD and Rh30. The effect of inhibitors of the endocytic pathway on AS-DACA sensitivity in RMS cell lines, coupled with the variations of endosomal marker expression, indicated the late endosomal/lysosomal compartment was implicated by confounding lines of evidence. Higher expression levels of Lysosomal-Associated Membrane Protein-1 (LAMP1) in the resistant RMS cell line, RD, provided correlations between the increased amount and activity of these compartments to AS-DACA resistance. The late endosomal inhibitor 3-methyladenine increased AS-DACA sensitivity solely in RD leading to the reduction of AS-DACA in membrane trafficking organelles. Acidification inhibitors did not produce an increase in AS-DACA sensitivity nor reduce its sequestration, indicating that the pH partitioning of weakly basic drugs into acidic compartments does not likely contribute to the AS-DACA sequestering resistance mechanism evident in RMS cells.

LASS2 enhances chemosensitivity of breast cancer by counteracting acidic tumor microenvironment through inhibiting activity of V-ATPase proton pump

A main obstacle to overcome during the treatment of tumors is drug resistance to chemotherapy; emerging studies indicate that a key factor contributing to this problem is the acidic tumor microenvironment. Here, we found that LASS2 expression was significantly lower in drug-resistant Michigan Cancer Foundation-7/adriamycin (MCF-7/ADR) human breast cancer cells than the drug-sensitive MCF-7 cells, and low expression of LASS2 was associated with poor prognosis in patients with breast cancer. Our results showed that the overexpression of LASS2 in MCF-7/ADR cells increased the chemosensitivity to multiple chemotherapeutic agents, including doxorubicin (Dox), whereas LASS2 knockdown in MCF-7 cells decreased the chemosensitivity. Cell-cycle analysis revealed a corresponding increase in apoptosis in the LASS2-overexpressing cells following Dox exposure, showing that the overexpression of LASS2 increased the susceptibility to Dox cytotoxicity. This effect was mediated by a significant increase in pHe (extracellular pH) and lysosomal pH, and more Dox entered the cells and stayed in the nuclei of cells. In nude mice, the combination of LASS2 overexpression and Dox significantly inhibited the growth of xenografts. Our findings suggest that LASS2 is involved in chemotherapeutic outcomes and low LASS2 expression may predict chemoresistance.

Cascaded photoinduced drug delivery to cells from multifunctional core-shell mesoporous silica

Different bioactive molecules are released into living cells from lipid-covered mesoporous silica nanoparticles. The release is triggered by light, as the particles feature covalently attached photosensitizers as membrane-opening agents. It is demonstrated that the particles achieve endosomal escape and that they release their cargo into the cytosol.

Photochemical internalisation of a macromolecular protein toxin using a cell penetrating peptide-photosensitiser conjugate

Photochemical internalisation (PCI) is a site-specific technique for improving cellular delivery of macromolecular drugs. In this study, a cell penetrating peptide, containing the core HIV-1 Tat 48-57 sequence, conjugated with a porphyrin photosensitiser has been shown to be effective for PCI. Herein we report an investigation of the photophysical and photobiological properties of a water soluble bioconjugate of the cationic Tat peptide with a hydrophobic tetraphenylporphyrin derivative. The cellular uptake and localisation of the amphiphilic bioconjugate was examined in the HN5 human head and neck squamous cell carcinoma cell line. Efficient cellular uptake and localisation in endo/lysosomal vesicles was found using fluorescence detection, and light-induced, rupture of the vesicles resulting in a more diffuse intracellular fluorescence distribution was observed. Conjugation of the Tat sequence with a hydrophobic porphyrin thus enables cellular delivery of an amphiphilic photosensitiser which can then localise in endo/lysosomal membranes, as required for effective PCI treatment. PCI efficacy was tested in combination with a protein toxin, saporin, and a significant reduction in cell viability was measured versus saporin or photosensitiser treatment alone. This study demonstrates that the cell penetrating peptide-photosensitiser bioconjugation strategy is a promising and versatile approach for enhancing the therapeutic potential of bioactive agents through photochemical internalisation.