Heme oxygenase-1 protects tumor cells against photodynamic therapy-mediated cytotoxicity

Synthesis and photo-induced anticancer activity of new 2-phenylethenyl-1H-benzo[e]indole dyes

Herein, a series of new 1,1,2-trimethyl-1H-benzo[e]indole dyes was prepared via Knoevenagel condensation reaction between 1,1,2-trimethyl-1H-benzo[e]indole and benzaldehydes, and characterized using various spectroscopic methods. The obtained compounds showed cytotoxic properties in G361 melanoma cell line upon irradiation with 414 nm blue light at submicromolar doses. The mechanism of action of the most potent compound 15 was further investigated. The treatment induced substantial generation of reactive oxygen species, leading to DNA damage followed by cell death depending on the concentration of the photosensitizer compound and the irradiation intensity.

Molecular Determinants for Photodynamic Therapy Resistance and Improved Photosensitizer Delivery in Glioma

Gliomas account for 24% of all the primary brain and Central Nervous System (CNS) tumors. These tumors are diverse in cellular origin, genetic profile, and morphology but collectively have one of the most dismal prognoses of all cancers. Work is constantly underway to discover a new effective form of glioma therapy. Photodynamic therapy (PDT) may be one of them. It involves the local or systemic application of a photosensitive compound-a photosensitizer (PS)-which accumulates in the affected tissues. Photosensitizer molecules absorb light of the appropriate wavelength, initiating the activation processes leading to the formation of reactive oxygen species and the selective destruction of inappropriate cells. Research focusing on the effective use of PDT in glioma therapy is already underway with promising results. In our work, we provide detailed insights into the molecular changes in glioma after photodynamic therapy. We describe a number of molecules that may contribute to the resistance of glioma cells to PDT, such as the adenosine triphosphate (ATP)-binding cassette efflux transporter G2, glutathione, ferrochelatase, heme oxygenase, and hypoxia-inducible factor 1. We identify molecular targets that can be used to improve the photosensitizer delivery to glioma cells, such as the epithelial growth factor receptor, neuropilin-1, low-density lipoprotein receptor, and neuropeptide Y receptors. We note that PDT can increase the expression of some molecules that reduce the effectiveness of therapy, such as Vascular endothelial growth factor (VEGF), glutamate, and nitric oxide. However, the scientific literature lacks clear data on the effects of PDT on many of the molecules described, and the available reports are often contradictory. In our work, we highlight the gaps in this knowledge and point to directions for further research that may enhance the efficacy of PDT in the treatment of glioma.

The m-TORC1 inhibitor Sirolimus increases the effectiveness of Photodynamic therapy in the treatment of cutaneous Squamous Cell Carcinoma, impairing NRF2 antioxidant signaling

Squamous Cell Carcinoma (SCC) is a subtype of Non-Melanoma Skin Cancer, the most common group of malignancies worldwide. Photodynamic therapy (PDT) is a non-invasive treatment approved for specific subtypes of SCC. Some malignancies resist PDT, forming more aggressive tumors and multiple relapses. Thus, new approaches aimed at optimizing the response to PDT are needed. The mTORC1 inhibitor rapamycin, also known as Sirolimus (SRL), interferes with protein synthesis and cell metabolism. The use of SRL as an immunosuppressant is associated to lower rates of SCC in kidney-transplanted patients, which are frequently affected by this pathology. We have evaluated SRL pre-treatment efficacy to enhance the damage induced by PDT with Methyl 5-aminolevulinate in two different cutaneous SCC established cell lines (SCC13 and A431) in vitro and therapy sensitization in PDT-resistant cell lines. We tested for the first time the SRL + PDT combination in a SKH-1 mouse model of photocarcinogenesis, diminishing the frequency of lesions and restraining tumor growth. Molecular studies revealed that protoporphyrin IX and reactive oxygen species production induced by PDT were promoted by SRL pre-treatment. Lastly, SRL modifies the expression and intracellular location of NRF2, interfering with the downstream antioxidant response modulated by NQO1 and HO-1. In conclusion, we propose SRL as a potential adjuvant to enhance PDT efficacy for SCC treatment.

Nrf2-Mediated Antioxidant Response and Drug Efflux Transporters Upregulation as Possible Mechanisms of Resistance in Photodynamic Therapy of Cancers

Photodynamic therapy (PDT) is a groundbreaking approach involving the induction of cytotoxic reactive oxygen species (ROS) within tumors through visible light activation of photosensitizers (PS) in the presence of molecular oxygen. This innovative therapy has demonstrated success in treating various cancers. While PDT proves highly effective in most solid tumors, there are indications that certain cancers exhibit resistance, and some initially responsive cancers may develop intrinsic or acquired resistance to PDT. The molecular mechanisms underlying this resistance are not fully understood. Recent evidence suggests that, akin to other traditional cancer treatments, the activation of survival pathways, such as the KEAP1/Nrf2 signaling pathway, is emerging as an important mechanism of post-PDT resistance in many cancers. This article explores the dual role of Nrf2, highlighting evidence linking aberrant Nrf2 expression to treatment resistance across a range of cancers. Additionally, it delves into the specific role of Nrf2 in the context of photodynamic therapy for cancers, emphasizing evidence that suggests Nrf2-mediated upregulation of antioxidant responses and induction of drug efflux transporters are potential mechanisms of resistance to PDT in diverse cancer types. Therefore, understanding the specific role(s) of Nrf2 in PDT resistance may pave the way for the development of more effective cancer treatments using PDT.

Inhibition of Heme Oxygenase 1 Suppresses Growth, Migration, and Invasion, and Regulates Tumor-Infiltrating CD8+ T Cells and in Uveal Melanoma

Purpose

Metastatic uveal melanoma (UM) treatment is difficult, and effective treatments are urgently needed. We aimed to explore the role of heme oxygenase 1 (HO-1) in UM and provide new therapeutic strategies for UM.

Methods

Bioinformatics was used to analyze the relationship between HMOX1 and immunity in UM and other tumors. Cell Counting Kit-8, Western blot, immunofluorescence staining, wound healing, and Transwell assays were used. A subcutaneous transplanted UM tumor model was used in mice to verify the therapeutic effect.

Results

In UM, the expression level of HMOX1 was strongly correlated with the immune score and the infiltration level of various immune cells. ZnPP can inhibit the growth of UM cells, promote cell apoptosis, and block the cell cycle at G0/G1 phase in vitro. HO-1 knockout can effectively inhibit the proliferation of UM cells. ZnPP effectively inhibited the growth of UM and promoted the infiltration of CD8+ T cells in a subcutaneous tumor transplantation model.

Conclusions

These results indicate that targeting HO-1 in UM has the potential for independent targeted immunotherapy or adjuvant immunotherapy.

In vitro evaluation of the efficacy of photodynamic therapy using 5-ALA on homologous feline mammary tumors in 2D and 3D culture conditions and a mouse subcutaneous model with 3D cultured cells

BACKGROUND

Numerous studies have shown that photodynamic therapy (PDT) has a therapeutic effect on mammary tumor cells, with 5-aminolevulinic acid (5-ALA-HCL) being a commonly used photosensitizer for PDT. Feline mammary tumors (FMTs) are relatively common. However, the cytotoxic and antitumor effects of 5-ALA-PDT on FMTs have not been clarified. To this end, we evaluated the therapeutic effect of 5-ALA-PDT on FMTs through in vitro experiments using an FMT FKR cell line established for this study.

METHODS

We performed 5-ALA-PDT in 2D-cultured FKR-A (adherent cells) and 3D-cultured FKR-S (spheroid cells) cells and performed a series of studies to evaluate the cell viability and determine the protoporphyrin IX (PpIX) content in the cells as well as the expression levels of mRNAs associated with PpIX production and release. An in vivo study was performed to assess the effectiveness of 5-ALA-PDT.

RESULTS

There was a significant difference in the concentration of PpIX in FMT cells under different incubation culture modes (2D versus 3D culture). The concentration of PpIX in FMT cells was correlated with the differences in cell culture (2D and 3D) as well as the expression levels of genes such as PEPT1, PEPT2, FECH, and HO-1.

CONCLUSIONS

In the in vitro study, 5-ALA-PDT had a stronger inhibitory effect on 3D-cultured FKR-S cells, which resemble the internal environment of organisms more closely. We also observed a significant inhibitory effect of 5-ALA-PDT on FMT cells in vivo. To our knowledge, this is the first study on 5-ALA-PDT for FMTs under both 2D and 3D conditions.

Inflammation-Associated Cytotoxic Agents in Tumorigenesis

Chronic inflammatory processes are related to all stages of tumorigenesis. As inflammation is closely associated with the activation and release of different cytotoxic agents, the interplay between cytotoxic agents and antagonizing principles is highlighted in this review to address the question of how tumor cells overcome the enhanced values of cytotoxic agents in tumors. In tumor cells, the enhanced formation of mitochondrial-derived reactive species and elevated values of iron ions and free heme are antagonized by an overexpression of enzymes and proteins, contributing to the antioxidative defense and maintenance of redox homeostasis. Through these mechanisms, tumor cells can even survive additional stress caused by radio- and chemotherapy. Through the secretion of active agents from tumor cells, immune cells are suppressed in the tumor microenvironment and an enhanced formation of extracellular matrix components is induced. Different oxidant- and protease-based cytotoxic agents are involved in tumor-mediated immunosuppression, tumor growth, tumor cell invasion, and metastasis. Considering the special metabolic conditions in tumors, the main focus here was directed on the disturbed balance between the cytotoxic agents and protective mechanisms in late-stage tumors. This knowledge is mandatory for the implementation of novel anti-cancerous therapeutic approaches.

Heme Oxygenase-1 and Its Role in Colorectal Cancer

Heme oxygenase-1 (HO-1) is an enzyme located at the endoplasmic reticulum, which is responsible for the degradation of cellular heme into ferrous iron, carbon monoxide and biliverdin-IXa. In addition to this main function, the enzyme is involved in many other homeostatic, toxic and cancer-related mechanisms. In this review, we first summarize the importance of HO-1 in physiology and pathophysiology with a focus on the digestive system. We then detail its structure and function, followed by a section on the regulatory mechanisms that control HO-1 expression and activity. Moreover, HO-2 as important further HO isoform is discussed, highlighting the similarities and differences with regard to HO-1. Subsequently, we describe the direct and indirect cytoprotective functions of HO-1 and its breakdown products carbon monoxide and biliverdin-IXa, but also highlight possible pro-inflammatory effects. Finally, we address the role of HO-1 in cancer with a particular focus on colorectal cancer. Here, relevant pathways and mechanisms are presented, through which HO-1 impacts tumor induction and tumor progression. These include oxidative stress and DNA damage, ferroptosis, cell cycle progression and apoptosis as well as migration, proliferation, and epithelial-mesenchymal transition.

Critical role of heme oxygenase-1 in chaetoglobosin A by triggering reactive oxygen species mediated mitochondrial apoptosis in colorectal cancer

The incidence rate of colorectal cancer (CRC) has been increasing and poses severe threats to human health worldwide and developing effective treatment strategies remains an urgent task. In this study, Chaetoglobosin A (ChA), an endophytic fungal metabolite from the medicinal herb-derived fungus Chaetomium globosum Km1126, was identified as a potent and selective antitumor agent in human CRC. ChA induced growth inhibition of CRC cells in a concentration-dependent manner but did not impair the viability of normal colon cells. ChA triggered mitochondrial intrinsic and caspase-dependent apoptotic cell death. In addition, apoptosis antibody array analysis revealed that expression of Heme oxygenase-1 (HO-1) was significantly increased by ChA. Inhibition of HO-1 increased the sensitivity of CRC cells to ChA, suggesting HO-1 may play a protective role in ChA-mediated cell death. ChA induced cell apoptosis via the induction of reactive oxygen species (ROS) and ROS scavenger (NAC) prevented ChA-induced cell death, mitochondrial dysfunction, and HO-1 activation. ChA promoted the activation of c-Jun N-terminal kinase (JNK), and co-administration of JNK inhibitor or siRNA markedly reversed ChA-mediated apoptosis. ChA significantly decreased the tumor growth without eliciting any organ toxicity or affecting the body weight of the CRC xenograft mice. This is the first study to demonstrate that ChA exhibits promising anti-cancer properties against human CRC both in vitro and in vivo. ChA is a potential therapeutic agent worthy of further development in clinical trials for cancer treatment.

Cytoprotective Role of Heme Oxygenase-1 in Cancer Chemoresistance: Focus on Antioxidant, Antiapoptotic, and Pro-Autophagy Properties

Chemoresistance remains the foremost challenge in cancer therapy. Targeting reactive oxygen species (ROS) manipulation is a promising strategy in cancer treatment since tumor cells present high levels of intracellular ROS, which makes them more vulnerable to further ROS elevation than normal cells. Nevertheless, dynamic redox evolution and adaptation of tumor cells are capable of counteracting therapy-induced oxidative stress, which leads to chemoresistance. Hence, exploring the cytoprotective mechanisms of tumor cells is urgently needed to overcome chemoresistance. Heme oxygenase-1 (HO-1), a rate-limiting enzyme of heme degradation, acts as a crucial antioxidant defense and cytoprotective molecule in response to cellular stress. Recently, emerging evidence indicated that ROS detoxification and oxidative stress tolerance owing to the antioxidant function of HO-1 contribute to chemoresistance in various cancers. Enhanced HO-1 expression or enzymatic activity was revealed to promote apoptosis resistance and activate protective autophagy, which also involved in the development of chemoresistance. Moreover, inhibition of HO-1 in multiple cancers was identified to reversing chemoresistance or improving chemosensitivity. Here, we summarize the most recent advances regarding the antioxidant, antiapoptotic, and pro-autophagy properties of HO-1 in mediating chemoresistance, highlighting HO-1 as a novel target for overcoming chemoresistance and improving the prognosis of cancer patients.

A Thiosemicarbazone Derivative as a Booster in Photodynamic Therapy-A Way to Improve the Therapeutic Effect

Photodynamic therapy is one of the most patient friendly and promising anticancer therapies. The active ingredient is irradiated protoporphyrin IX, which is produced in the body that transfers energy to the oxygen-triggering phototoxic reaction. This effect could be enhanced by using iron chelators, which inhibit the final step of heme biosynthesis, thereby increasing the protoporphyrin IX concentration. In the presented work, we studied thiosemicarbazone derivative, which is a universal enhancer of the phototoxic effect. We examined several genes that are involved in the transport of the heme substrates and heme itself. The results indicate that despite an elevated level of ABCG2, which is responsible for the PpIX efflux, its concentration in a cell is sufficient to trigger a photodynamic reaction. This effect was not observed for 5-ALA alone. The analyzed cell lines differed in the scale of the effect and a correlation with the PpIX accumulation was observed. Additionally, an increased activation of the iron transporter MFNR1 was also detected, which indicated that the regulation of iron transport is essential in PDT.

High Hemin Concentration Induces Escape from Senescence of Normoxic and Hypoxic Colon Cancer Cells

Simple Summary

High red-meat consumption as well as bleeding or bruising can promote oxidative stress and, in consequence, cancer development. However, the mechanism of that phenomenon is not understood. The induction of therapy-induced senescence (TIS) might also be induced by oxidative stress. Recently, TIS cells, despite their inhibited proliferation potential, have been identified as one of the sources of tumor re-growth. Here, with the use of molecular analyses, we found that oxidative stress, promoted by high doses of hemin or H₂O₂, can trigger TIS escape and cell re-population. It is closely related to the activity of antioxidative enzymes, especially heme oxygenase-1. Hypoxia might accelerate these effects. Therefore, we propose that the prevention of excessive oxidative stress could be a potential target in senolytic therapies.

Abstract

Hemoglobin from either red meat or bowel bleeding may promote oxidative stress and increase the risk of colorectal cancer (CRC). Additionally, solid cancers or their metastases may be present with localized bruising. Escape from therapy-induced senescence (TIS) might be one of the mechanisms of tumor re-growth. Therefore, we sought to study whether hemin can cause escape from TIS in CRC. To induce senescence, human colon cancer cells were exposed to a chemotherapeutic agent irinotecan (IRINO). Cells treated with IRINO exhibited common hallmarks of TIS. To mimic bleeding, colon cancer cells were additionally treated with hemin. High hemin concentration activated heme oxygenase-1 (HO-1), induced escape from TIS and epithelial-to-mesenchymal transition, and augmented progeny production. The effect was even stronger in hypoxic conditions. Similar results were obtained when TIS cells were treated with another prooxidant agent, H₂O₂. Silencing of antioxidative enzymes such as catalase (CAT) or glutathione peroxidase-1 (GPx-1) maintained colon cancer cells in a senescent state. Our study demonstrates that a high hemin concentration combined with an increased activity of antioxidative enzymes, especially HO-1, leads to escape from the senescence of colon cancer cells. Therefore, our observations could be used in targeted anti-cancer therapy.

In vitro 5-Fluorouracil resistance produces enhanced photodynamic therapy damage in SCC and tumor resistance in BCC

Non-melanoma skin cancer (NMSC) is the most common malignancy worldwide, with rising incidence in the recent years. It includes basal cell carcinoma (BCC), and squamous cell carcinoma (SCC). Several non-invasive therapies have been developed for its treatment such as topical 5-Fluorouracil (5FU) and photodynamic therapy (PDT), among others. Despite both are appropriated for NMSC treatment, recurrence cases have been reported. To prevent this, in this work we explore the potential of the combination of PDT and 5FU to treat SCC and BCC. First we evaluate the efficacy of PDT in cells resistant to 5FU. For this purpose, we use SCC-13 and CSZ-1 cells, obtained from a human SCC and a murine BCC, respectively. We first induced 5FU resistance in these cell lines by repeated treatments with the drug and then, the efficacy to PDT was evaluated. The results obtained indicated that SCC-5FU resistant cells were sensible to PDT administration, whereas BCC-5FU resistant cells were also resistant to PDT. The observed responses in both cell lines are in concordance to Protoporphyrin IX (PpIX) and reactive oxygen species (ROS) levels produced after the incubation with MAL and subsequent light exposure. The obtained data support the fact that PDT seems to be an appropriate therapeutic option to be administered after 5FU resistance in SCC. However, PDT would not be a choice therapy for resistant BCC cells to 5FU.

Heme Oxygenase-1 Has a Greater Effect on Melanoma Stem Cell Properties Than the Expression of Melanoma-Initiating Cell Markers

Melanoma-initiating cells (MICs) contribute to the tumorigenicity and heterogeneity of melanoma. MICs are identified by surface and functional markers and have been shown to display cancer stem cell (CSC) properties. However, the existence of MICs that follow the hierarchical CSC model has been questioned by studies showing that single unselected melanoma cells are highly tumorigenic in xenotransplantation assays. Herein, we characterize cells expressing MIC markers (CD20, CD24, CD133, Sca-1, ABCB1, ABCB5, ALDH^high) in the B16-F10 murine melanoma cell line. We use flow cytometric phenotyping, single-cell sorting followed by in vitro clonogenic assays, and syngeneic in vivo serial transplantation assays to demonstrate that the expression of MIC markers does not select CSC-like cells in this cell line. Previously, our group showed that heme-degrading enzyme heme oxygenase-1 (HO-1) can be upregulated in melanoma and increase its aggressiveness. Here, we show that HO-1 activity is important for non-adherent growth of melanoma and HO-1 overexpression enhances the vasculogenic mimicry potential, which can be considered protumorigenic activity. However, HO-1 overexpression decreases clone formation in vitro and serial tumor initiation in vivo. Thus, HO-1 plays a dual role in melanoma, improving the progression of growing tumors but reducing the risk of melanoma initiation.

Advanced photodynamic therapy with an engineered M13 phage targeting EGFR: Mitochondrial localization and autophagy induction in ovarian cancer cell lines

Photodynamic therapy (PDT) is a potential synergistic approach to chemotherapy for treating ovarian cancer, the most lethal gynecologic malignancy. Here we used M13 bacteriophage as a targeted vector for the efficient photodynamic killing of SKOV3 and COV362 cells. The M13 phage was refactored (M13_r) to display an EGFR binding peptide in its tip that is frequently overexpressed in ovarian cancer. The refactored phage was conjugated with chlorin e6 (Ce6), one of the most widely used photosensitizers (M13_r-Ce6). The new platform, upon irradiation, generated ROS by type I mechanism and showed activity in killing SKOV3 and COV362 cells even at concentrations in which Ce6 alone was ineffective. A microscopy analysis demonstrated an enhanced cellular uptake of M13_r-Ce6 compared to free Ce6 and its mitochondrial localization. Western blot analysis revealed significant downregulation in the expression of EGFR in cells exposed to M13_r-Ce6 after PDT. Following PDT treatment, autophagy induction was supported by an increased expression of LC3II, along with a raised autophagic fluorescent signal, as observed by fluorescence microscopy analysis for autophagosome visualization. As a conclusion we have herein proposed a bacteriophage-based receptor targeted photodynamic therapy for EGFR-positive ovarian cancer.

Targeting glioblastoma stem cells: The first step of photodynamic therapy

Glioblastoma is one of the most malignant types of brain cancer. Evidence suggests that within gliomas there is a small subpopulation of cells with the capacity for self-renewal, called glioma stem cells. These cells could be responsible for tumorigenesis, chemo and radioresistance, and finally for the recurrence of the tumor. Fluorescence-guided resection have improved the results of treatment against this disease, prolonging the survival of patients by a few months. Also, clinical trials have reported potential improvements in the therapeutic response after photodynamic therapy. Thus far, there are few published works that show the response of glioblastoma stem-like cells to photodynamic therapy. Here, we present a brief review exclusively commenting on the therapeutic approaches to eliminate glioblastoma stem cells and on the research publications about this topic of glioblastoma stem cells in relation to photodynamic therapy. It is our hope that this review will be useful to provide an overview about what is known to date on the topic and to promote the generation of new ideas for the eradication of glioblastoma stem cells by photodynamic treatment.

Computational Designing and Prediction of ADMET Properties of Four Novel Imidazole-Based Drug Candidates Inhibiting Heme Oxygenase-1 Causing Cancers

The overexpression of heme oxygenase-1 (HO-1) contributes to the development of several types of cancers. The inhibition of HO-1 through imidazole-based drugs, which is non-competitive with heme, is a focus of anticancer drug research. We designed the four following novel HO-1 inhibiting compounds: 2-(1-cyclopentyl-4-(1H-imidazol-4-yl)butan-2-yl)pyrazine (M11), 2-[(2-chloro-3-methylcyclohexyl)methyl]-1H-imidazole (M26), 2-(2-phenethyl-1H-imidazol-4-yl)ethanesulfonamide (M28), and 5-chloro-2-[2-(2,5-dihydro-1H-imidazol-2-yl)propan-2-yl]-1H-imidazole (M31). All compounds showed a strong binding affinity with HO-1 in molecular docking studies. The in silico absorption, distribution, metabolism, excretion and toxicity (ADMET) data showed that the compounds would be available orally in an acceptable manner. The bioactivity scores revealed that they were moderately active substances. They were found as non-mutagen, non-tumorigenic, non-irritant, and non-detrimental to the reproductive system. Finally, the drug-likeness values of the compounds were obtained as -0.71, -1.64, -2.04, and 0.4 respectively, with the final drug-score of 0.60, 0.54, 0.51, and 0.77 respectively.

A first principle study of heme molecule as an active adsorbent for halogenated hydrocarbons

Heme, a biomolecule with complex structure and unique properties and strong adsorption of oxygen, is utilized as an adsorbing material for haloalkene gas molecules. It has been systematically investigated employing density functional theory. Among the haloalkene gases chosen in the present study, the interaction energy is maximum for CDFM (-10.66 kcal/mol) and lowest for TFM (-5.02 kcal/mol). The calculated bond stabilization energy for heme-haloalkene complexes correlates with findings of interaction energy. The noncovalent interaction between heme and haloalkenes is confirmed from the topological analysis. The energy gap values decrease on adsorption of haloalkenes along with a decrease in reactivity of the complexes.

Clinical Significance of Heme Oxygenase 1 in Tumor Progression

Heme oxygenase 1 (HO-1) plays a key role in cell adaptation to stressors through the antioxidant, antiapoptotic, and anti-inflammatory properties of its metabolic products. For these reasons, in cancer cells, HO-1 can favor aggressiveness and resistance to therapies, leading to poor prognosis/outcome. Genetic polymorphisms of HO-1 promoter have been associated with an increased risk of cancer progression and a high degree of therapy failure. Moreover, evidence from cancer biopsies highlights the possible correlation between HO-1 expression, pathological features, and clinical outcome. Indeed, high levels of HO-1 in tumor specimens often correlate with reduced survival rates. Furthermore, HO-1 modulation has been proposed in order to improve the efficacy of antitumor therapies. However, contrasting evidence on the role of HO-1 in tumor biology has been reported. This review focuses on the role of HO-1 as a promising biomarker of cancer progression; understanding the correlation between HO-1 and clinical data might guide the therapeutic choice and improve the outcome of patients in terms of prognosis and life quality.

Oxidative Properties of Polystyrene Nanoparticles with Different Diameters in Human Peripheral Blood Mononuclear Cells (In Vitro Study)

With the ongoing commercialization, human exposure to plastic nanoparticles will dramatically increase, and evaluation of their potential toxicity is essential. There is an ongoing discussion on the human health effects induced by plastic particles. For this reason, in our work, we assessed the effect of polystyrene nanoparticles (PS-NPs) of various diameters (29, 44 and 72 nm) on selected parameters of oxidative stress and the viability of human peripheral blood mononuclear cells (PBMCs) in the in vitro system. Cells were incubated with PS-NPs for 24 h in the concentration range of 0.001 to 100 µg/mL and then labeled: formation of reactive oxygen species (ROS) (including hydroxyl radical), protein and lipid oxidation and cell viability. We showed that PS-NPs disturbed the redox balance in PBMCs. They increased ROS levels and induced lipid and protein oxidation, and, finally, the tested nanoparticles induced a decrease in PBMCs viability. The earliest changes in the PBMCs were observed in cells incubated with the smallest PS-NPs, at a concentration of 0.01 μg/mL. A comparison of the action of the studied nanoparticles showed that PS-NPs (29 nm) exhibited a stronger oxidative potential in PBMCs. We concluded that the toxicity and oxidative properties of the PS-NPs examined depended to significant degree on their diameter.

Metal-organic complex-based chemodynamic therapy agents for cancer therapy

In recent years, many inorganic nanoparticle-based chemodynamic therapy (CDT) agents have been employed in cancer therapy; however, the relatively lower catalytic activity compared to that of other CDT agents and long-term toxicity owing to low biodegradability present significant challenges for their future clinical application. In light of this, metal-organic complex-based agents have been attracting attention as potential alternatives/complements to traditional CDT agents. During the past few years, many reports of agents with improved therapeutic potential have been published; however, no comprehensive review regarding metal-organic complex-based CDT agents has appeared to date. In this feature article, we present the different types and characteristics of metal-organic CDT agents and the potential future therapeutic applications associated with each of these. Representative agents that have been used in the field of CDT over the past 5 years are summarized, and recent advances aimed at improving the therapeutic efficacy in various tumors are highlighted. This framework allows us to discuss recent trends in the field of CDT. We also provide views as to where the field is moving and discuss how the potential of CDT agents can be broadened to include a range of clinical applications that go beyond standard CDT-based treatment strategies.

Role of HMOX1 Promoter Genetic Variants in Chemoresistance and Chemotherapy Induced Neutropenia in Children with Acute Lymphoblastic Leukemia

Whilst the survival rates of childhood acute lymphoblastic leukemia (ALL) have increased remarkably over the last decades, the therapy resistance and toxicity are still the major causes of treatment failure. It was shown that overexpression of heme oxygenase-1 (HO-1) promotes proliferation and chemoresistance of cancer cells. In humans, the HO-1 gene (HMOX1) expression is modulated by two polymorphisms in the promoter region: (GT)n-length polymorphism and single-nucleotide polymorphism (SNP) A(−413)T, with short GT repeat sequences and 413-A variants linked to an increased HO-1 inducibility. We found that the short alleles are significantly more frequent in ALL patients in comparison to the control group, and that their presence may be associated with a higher risk of treatment failure, reflecting the role of HO-1 in chemoresistance. We also observed that the presence of short alleles may predispose to develop chemotherapy-induced neutropenia. In case of SNP, the 413-T variant co-segregated with short or long alleles, while 413-A almost selectively co-segregated with long alleles, hence it is not possible to determine if SNPs are actually of phenotypic significance. Our results suggest that HO-1 can be a potential target to overcome the treatment failure in ALL patients.

Modeling the photodynamic effect in 2D versus 3D cell culture under normoxic and hypoxic conditions

BACKGROUND

Photodynamic therapy (PDT), mainly as a combined therapy, can still be considered a promising technology for targeted cancer treatment. Besides the several and essential benefits of PDT, there are some concerns and limitations, such as complex dosimetry, tumor hypoxia, and other mechanisms of resistance. In this study, we present how the cell culture model and cell culture conditions may affect the response to PDT treatment. It was studied by applying two different 3D cell culture, non-scaffold, and hydrogel-based models under normoxic and hypoxic conditions. In parallel, a detailed mechanism of the action of zinc phthalocyanine M2TG3 was presented.

METHODS

Hydrogel-based and tumor spheroids consisting of LNCaP cells, were used as 3D cell culture models in experiments performed under normoxic and hypoxic (1% of oxygen) conditions. Several analyses were performed to compare the activity of M2TG3 under different conditions, such as cytotoxicity, the level of proapoptotic and stress-related proteins, caspase activity, and antioxidant gene expression status. Additionally, we tested bioluminescence and fluorescence assays as a useful approach for a hydrogel-based 3D cell culture.

RESULTS

We found that M2TG3 might lead to apoptotic cancer cell death and is strongly dependent on the model and oxygen availability. Moreover, the expression of the genes modulated in the antioxidative system in 2D and 3D cell culture models were presented. The tested bioluminescence assay revealed several advantages, such as repetitive measurements on the same sample and simultaneous analysis of different parameters due to the non-lysing nature of this assay.

CONCLUSIONS

It was shown that M2TG3 can effectively cause cancer cell death via a different mechanism, depending on cell culture conditions such as the model and oxygen availability.

Immune Modulation by Inhibitors of the HO System

The heme oxygenase (HO) system involves three isoforms of this enzyme, HO-1, HO-2, and HO-3. The three of them display the same catalytic activity, oxidating the heme group to produce biliverdin, ferrous iron, and carbon monoxide (CO). HO-1 is the isoform most widely studied in proinflammatory diseases because treatments that overexpress this enzyme promote the generation of anti-inflammatory products. However, neonatal jaundice (hyperbilirubinemia) derived from HO overexpression led to the development of inhibitors, such as those based on metaloproto- and meso-porphyrins inhibitors with competitive activity. Further, non-competitive inhibitors have also been identified, such as synthetic and natural imidazole-dioxolane-based, small synthetic molecules, inhibitors of the enzyme regulation pathway, and genetic engineering using iRNA or CRISPR cas9. Despite most of the applications of the HO inhibitors being related to metabolic diseases, the beneficial effects of these molecules in immune-mediated diseases have also emerged. Different medical implications, including cancer, Alzheimer´s disease, and infections, are discussed in this article and as to how the selective inhibition of HO isoforms may contribute to the treatment of these ailments.

Effect of Heme Oxygenase-1 on Melanoma Development in Mice-Role of Tumor-Infiltrating Immune Cells

OBJECTIVE

Heme oxygenase-1 (HO-1) is a cytoprotective, proangiogenic and anti-inflammatory enzyme that is often upregulated in tumors. Overexpression of HO-1 in melanoma cells leads to enhanced tumor growth, augmented angiogenesis and resistance to anticancer treatment. The effect of HO-1 in host cells on tumor development is, however, hardly known.

METHODS AND RESULTS

To clarify the effect of HO-1 expression in host cells on melanoma progression, C57BL/6xFvB mice of different HO-1 genotypes, HO-1+/+, HO-1+/-, and HO-1-/-, were injected with the syngeneic wild-type murine melanoma B16(F10) cell line. Lack of HO-1 in host cells did not significantly influence the host survival. Nevertheless, in comparison to the wild-type counterparts, the HO-1+/- and HO-1-/- males formed bigger tumors, and more numerous lung nodules; in addition, more of them had liver and spleen micrometastases. Females of all genotypes developed at least 10 times smaller tumors than males. Of importance, the growth of primary and secondary tumors was completely blocked in HO-1+/+ females. This was related to the increased infiltration of leukocytes (mainly lymphocytes T) in primary tumors.

CONCLUSIONS

Although HO-1 overexpression in melanoma cells can enhance tumor progression in mice, its presence in host cells, including immune cells, can reduce growth and metastasis of melanoma.

Possible mechanism of heme oxygenase-1 expression in rat malignant meningioma KMY-J cells subjected to talaporfin sodium-mediated photodynamic therapy

BACKGROUND

We previously demonstrated that heme oxygenase-1 (HO-1) induction may contribute to a protective response against photodynamic therapy (PDT) using talaporfin sodium (TS) in rat malignant meningioma KMY-J cells. In the present study, we examined the mechanism of HO-1 induction by PDT with TS (TS-PDT) in KMY-J cells.

METHODS

KMY-J cells were incubated with 25 μM TS for 2 h and then exposed to 664 nm diode laser irradiation at 1 J/cm². The gene and protein expression levels of HO-1 and hypoxia-inducible factor-1α (HIF-1α) were determined by real-time RT-PCR and western blot analysis, respectively. Cell viability was measured using the cell counting kit-8 assay.

RESULTS

mRNA and protein levels of HO-1 in KMY-J cells were increased significantly at 3, 6, and 9 h after laser irradiation and the increased mRNA level of HO-1 was decreased by antioxidant N-acetyl cysteine treatment. The protein level of HIF-1α, which mediates transcriptional activation of the HO-1 gene, was increased significantly at 1 h after laser irradiation. Additionally, induction of mRNA expression of HO-1 by TS-PDT was diminished by HIF-1α inhibitor echinomycin. We also demonstrated that echinomycin significantly augmented the cytotoxic effect of TS-PDT.

CONCLUSIONS

Our findings indicate that TS-PDT may induce HO-1 expression via reactive oxygen species production and then HIF-1 pathway activation in KMY-J cells, and the HO-1 induction may cause attenuation of the therapeutic effect of TS-PDT.

Predictive biomarkers for 5-ALA-PDT can lead to personalized treatments and overcome tumor-specific resistances

BACKGROUND

Photodynamic therapy (PDT) is a minimally invasive, clinically approved therapy with numerous advantages over other mainstream cancer therapies. 5-aminolevulinic acid (5-ALA)-PDT is of particular interest, as it uses the photosensitiser PpIX, naturally produced in the heme pathway, following 5-ALA administration. Even though 5-ALA-PDT shows high specificity to cancers, differences in treatment outcomes call for predictive biomarkers to better stratify patients and to also diversify 5-ALA-PDT based on each cancer's phenotypic and genotypic individualities.

AIMS

The present study seeks to highlight key biomarkers that may predict treatment outcome and simultaneously be exploited to overcome cancer-specific resistances to 5-ALA-PDT.

METHODS AND RESULTS

We submitted two glioblastoma (T98G and U87) and three breast cancer (MCF7, MDA-MB-231, and T47D) cell lines to 5-ALA-PDT. Glioblastoma cells were the most resilient to 5-ALA-PDT, while intracellular production of 5-ALA-derived protoporphyrin IX (PpIX) could not account for the recorded PDT responses. We identified the levels of expression of ABCG2 transporters, ferrochelatase (FECH), and heme oxygenase (HO-1) as predictive biomarkers for 5-ALA-PDT. GPX4 and GSTP1 expression vs intracellular glutathione (GSH) levels also showed potential as PDT biomarkers. For T98G cells, inhibition of ABCG2, FECH, HO-1, and/or intracellular GSH depletion led to profound PDT enhancement. Inhibition of ABCG2 in U87 cells was the only synergistic adjuvant to 5-ALA-PDT, rendering the otherwise resistant cell line fully responsive to 5-ALA-PDT. ABCG2 or FECH inhibition significantly enhanced 5-ALA-PDT-induced MCF7 cytotoxicity, while for MDA-MB-231, ABCG2 inhibition and intracellular GSH depletion conferred profound synergies. FECH inhibition was the only synergism to ALA-PDT for the most susceptible among the cell lines, T47D cells.

CONCLUSION

This study demonstrates the heterogeneity in the cellular response to 5-ALA-PDT and identifies biomarkers that may be used to predict treatment outcome. The study also provides preliminary findings on the potential of inhibiting specific molecular targets to overcome inherent resistances to 5-ALA-PDT.

HO-1 drives autophagy as a mechanism of resistance against HER2-targeted therapies

PURPOSE

Targeted therapies have resulted in major advances in the treatment of HER2-positive breast cancers. Despite this, up to 70% of patients will develop resistance to treatment within 2 years and new strategies for targeting resistant disease are needed.

METHODS

To identify potential resistance mechanisms, we used the mouse MMTV-NIC-PTEN+/- spontaneous model of HER2-positive breast cancer and the pan-HER family kinase inhibitor sapatinib. Vehicle and sapatinib-treated tumors were evaluated by immunohistochemistry and proteomic analysis. In vitro studies were carried out to define the role of heme oxygenase 1 (HO-1) and autophagy in resistance to sapatinib and lapatinib, another pan-HER family kinase inhibitor.

RESULTS

Treatment of tumor-bearing MMTV-NIC-PTEN+/- mice with sapatinib resulted in delayed tumor progression and increased survival. However, tumors eventually progressed on treatment. Proteomic analysis identified proteins associated with cellular iron homeostasis as being upregulated in the sapatinib-treated tumors. This included HO-1 whose overexpression was confirmed by immunohistochemistry. Overexpression of HO-1 in HER2-expressing SKBR3 breast cancer cells resulted in reduced sensitivity to both pan-HER family kinase inhibitors sapatinib and lapatinib. This was associated with increased autophagy in the HO-1 over-expressing cells. Furthermore, increased autophagy was also seen in the sapatinib-treated tumors. Treatment with autophagy inhibitors was able to increase the sensitivity of the HO-1 over-expressing cells to both lapatinib and sapatinib.

CONCLUSION

Together these data indicate a role for HO-1-induced autophagy in resistance to pan-HER family kinase inhibitors.

Grass carp (Ctenopharyngodon idella) NRF2 alleviates the oxidative stress and enhances cell viability through upregulating the expression of HO-1

As a member of the Cap 'n' Collar (CNC) family, NRF2 contains a basic leucine zipper (bZip) and can regulate the downstream target gene heme oxygenase 1 (HO-1) in response to oxidative stress. In the present study, a grass carp (Ctenopharyngodon idella) NRF2 ORF was cloned and identified. The largest ORF (1782 bp) encodes a polypeptide of 593 amino acids. The deduced amino acid sequence of grass carp NRF2 (CiNRF2) contains a well-conserved DNA-binding domain (BRLZ domain). Phylogenetic tree analysis revealed that CiNRF2 has a closer evolutionary relationship with other fish counterparts. After CIK (C. idellus kidney) cells were persistently stimulated with tunicamycin (TM), CiNRF2 was significantly upregulated from 12 to 36 h. Then, the expression was dropped at 48 h post-infection. Additionally, when TM or TG (thapsigargin) stimulated CIK cells, overexpression of CiNRF2 in cells downregulated the expression of Bip mRNA, a marker protein of oxidative stress, suggesting that fish NRF2 can alleviate the oxidative stress level induced by TM or TG. To study the protective mechanism of fish NRF2, the DNA sequences of CiNRF2 and CiATF4 (grass carp ATF4) were separately sub-cloned into the expression vectors pEGFP and pCMV-Flag for co-immunoprecipitation and GST pull-down assays. These assays showed that CiNRF2 can combine with CiATF4 through its Neh1 domain. Meanwhile, we cloned grass carp HO-1 promoter sequence and constructed the recombinant plasmid of pGL3-HO-1. Soon afterwards, pGL3-HO-1 was co-transfected into grass carp ovary (CO) cells with pcDNA3.1-CiNRF2 or pcDNA3.1-CiATF4, respectively. The results showed that the luciferase activity of pGL3-HO-1 in the overexpressed CiNRF2 plus CiATF4 cells was significantly increased, along with the increase of cell viability (~ 133%). However, when HO-1 was knocked down in cells, CiNRF2 was unable to perform its function. These results demonstrated that CiNRF2 was effective in protecting grass carp against the oxidative stress induced by TM and increasing cell viability by upregulating HO-1 expression.

Design and in vitro evaluation of electrospun shape memory polyurethanes for self-fitting tissue engineering grafts and drug delivery systems

Integration of multiple features including shape memory, biodegradation, and sustained drug delivery in a single material offers the opportunity to significantly improve the abilities of implantable devices for cardiovascular system regeneration. Two types of shape memory polyurethanes (SMPUs): PU-PLGA and PU-PLLA/PEG differing in soft segments composition that comprising blends of various biodegradable polyols, i.e. D,l-lactide-co-glycolide diol (o-PLGA), poly(e-caprolactone) diols (o-PCL) with various molecular weights, poly-l-lactide diol (o-PLLA), polyethylene glycol (o-PEG) were synthesized and further utilized to electrospun nanofibrous - rapamycin (Rap) delivery system. Structure characterization by Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DCS) and hydrophilicity measurements were performed to gain more insights on the influence of the particular units of the softs segments on the transition temperature (T_trans), shape recovery, degradation profile, and drug release kinetics. In vitro study in PBS solution revealed that incorporation of o-PLGA segments to SMPUs is favorable over o-PEG as increased shape memory performance was observed. Moreover, presence of PLGA in PU-PLGA gave more predictable degradation profile in comparison to PU-PLLA/PEG system. Human Cardiac Fibroblasts (HCF) viability tests in vitro confirmed that the amount of Rap released from evaluated PU-PLLA/PEG/Rap and PU-PLGA/Rap drug delivery systems was sufficient to inhibit cells growth on the surface of the tested materials.

Antioxidation and Antiapoptosis Characteristics of Heme Oxygenase-1 Enhance Tumorigenesis of Human Prostate Carcinoma Cells

Heme oxygenase-1 (HO-1) has antiinflammatory and antioxidant properties and is deemed as a tissue protector. However, effects of HO-1 in prostate cancer remain in controversy. We evaluated the role of HO-1 in prostate carcinoma in vitro and in vivo.

Overexpression of HO-1 did not affect prostate cell proliferation in the normal condition but enhanced cell proliferation under serum starvation. HO-1 overexpression enhanced cell invasion of PC-3 cells through epithelial–mesenchymal transition (EMT) induction, which was supported by increased Slug, N-cadherin, and vimentin expressions. In the xenograft animal study, HO-1 overexpression enhanced PC-3 cell tumor growth in vivo. HO-1 attenuated reactive oxygen species induced by H₂O₂ or pyocyanin treatment in PC-3 and DU145 cells. HO-1 further reduced PC-3 and DU145 cell apoptosis induced by H₂O₂ or serum starvation. Our results suggested that HO-1 was able to increase prostate carcinoma cell invasion in vitro and tumor growth in vivo. The EMT induction and antioxidant and antiapoptotic effects of HO-1 in the prostate carcinoma cells may be responsible for these findings.

Cell death in photodynamic therapy: From oxidative stress to anti-tumor immunity

Photodynamic therapy is a promising approach for cancer treatment that relies on the administration of a photosensitizer followed by tumor illumination. The generated oxidative stress may activate multiple mechanisms of cell death which are counteracted by cells through adaptive stress responses that target homeostasis rescue. The present renaissance of PDT was leveraged by the acknowledgment that this therapy has an immediate impact locally, in the illumination volume, but that subsequently it may also elicit immune responses with systemic impact. The investigation of the mechanisms of cell death under the oxidative stress of PDT is of paramount importance to understand how the immune system is activated and, ultimately, to make PDT a more appealing/relevant therapeutic option.

Development and characterization of a new inhibitor of heme oxygenase activity for cancer treatment

Heme oxygenase-1 (HO-1, HMOX1) degrades pro-oxidant heme into carbon monoxide (CO), ferrous ions (Fe²⁺) and biliverdin. The enzyme exerts multiple cytoprotective functions associated with the promotion of angiogenesis and counteraction of the detrimental effects of cellular stress which are crucial for the survival of both normal and tumor cells. Accordingly, in many tumor types, high expression of HO-1 correlates with poor prognosis and resistance to treatment, i.e. chemotherapy, suggesting inhibition of HO-1 as a possible antitumor approach. At the same time, the lack of selective and well-profiled inhibitors of HO-1 determines the unmet need for new modulators of this enzyme, with the potential to be used in either adjuvant therapy or as the stand-alone targeted therapeutics. In the current study, we provided novel inhibitors of HO-1 and validated the effect of pharmacological inhibition of HO activity by the imidazole-based inhibitor (SLV-11199) in human pancreatic (PANC-1) and prostate (DU-145) cancer cell lines. We demonstrated potent inhibition of HO activity in vitro and showed associated anticancer effectiveness of SLV-11199. Treatment with the tested compound led to decreased cancer cell viability and clonogenic potential. It has also sensitized the cancer cells to chemotherapy. In PANC-1 cells, diminished HO activity resulted in down-regulation of pro-angiogenic factors like IL-8. Mechanistic investigations revealed that the treatment with SLV-11199 decreased cell migration and inhibited MMP-1 and MMP-9 expression. Moreover, it affected mesenchymal phenotype by regulating key modulators of the epithelial to mesenchymal transition (EMT) signalling axis. Finally, F-actin cytoskeleton and focal contacts were destabilized by the reported compound. Overall, the current study suggests a possible relevance of the tested novel inhibitor of HO activity as a potential anticancer compound. To support such utility, further investigation is still needed, especially in in vivo conditions.

Photodynamic Therapy in Melanoma - Where do we Stand?

BACKGROUND

Malignant melanoma is one of the most aggressive malignant tumors, with unpredictable evolution. Despite numerous therapeutic options, like chemotherapy, BRAF inhibitors and immunotherapy, advanced melanoma prognosis remains severe. Photodynamic therapy (PDT) has been successfully used as the first line or palliative therapy for the treatment of lung, esophageal, bladder, non melanoma skin and head and neck cancers. However, classical PDT has shown some drawbacks that limit its clinical application in melanoma.

OBJECTIVE

The most important challenge is to overcome melanoma resistance, due to melanosomal trapping, presence of melanin, enhanced oxidative stress defense, defects in the apoptotic pathways, immune evasion, neoangiogenesis stimulation.

METHOD

In this review we considered: (1) main signaling molecular pathways deregulated in melanoma as potential targets for personalized therapy, including PDT, (2) results of the clinical studies regarding PDT of melanoma, especially advanced metastatic stage, (3) progresses made in the design of anti-melanoma photosensitizers (4) inhibition of tumor neoangiogenesis, as well as (5) advantages of the derived therapies like photothermal therapy, sonodynamic therapy.

RESULTS

PDT represents a promising alternative palliative treatment for advanced melanoma patients, mainly due to its minimal invasive character and low side effects. Efficient melanoma PDT requires: (1) improved, tumor targeted, NIR absorbing photosensitizers, capable of inducing high amounts of different ROS inside tumor and vasculature cells, possibly allowing a theranostic approach; (2) an efficient adjuvant immune therapy.

CONCLUSION

Combination of PDT with immune stimulation might be the key to overcome the melanoma resistance and to obtain better, sustainable clinical results.

Crosstalk Between Oxidative Stress and Endoplasmic Reticulum (ER) Stress in Endothelial Dysfunction and Aberrant Angiogenesis Associated With Diabetes: A Focus on the Protective Roles of Heme Oxygenase (HO)-1

Type-2 diabetes prevalence is continuing to rise worldwide due to physical inactivity and obesity epidemic. Diabetes and fluctuations of blood sugar are related to multiple micro- and macrovascular complications, that are attributed to oxidative stress, endoplasmic reticulum (ER) activation and inflammatory processes, which lead to endothelial dysfunction characterized, among other features, by reduced availability of nitric oxide (NO) and aberrant angiogenic capacity. Several enzymatic anti-oxidant and anti-inflammatory agents have been found to play protective roles against oxidative stress and its downstream signaling pathways. Of particular interest, heme oxygenase (HO) isoforms, specifically HO-1, have attracted much attention as major cytoprotective players in conditions associated with inflammation and oxidative stress. HO operates as a key rate-limiting enzyme in the process of degradation of the iron-containing molecule, heme, yielding the following byproducts: carbon monoxide (CO), iron, and biliverdin. Because HO-1 induction was linked to pro-oxidant states, it has been regarded as a marker of oxidative stress; however, accumulating evidence has established multiple cytoprotective roles of the enzyme in metabolic and cardiovascular disorders. The cytoprotective effects of HO-1 depend on several cellular mechanisms including the generation of bilirubin, an anti-oxidant molecule, from the degradation of heme; the induction of ferritin, a strong chelator of free iron; and the release of CO, that displays multiple anti-inflammatory and anti-apoptotic actions. The current review article describes the major molecular mechanisms contributing to endothelial dysfunction and altered angiogenesis in diabetes with a special focus on the interplay between oxidative stress and ER stress response. The review summarizes the key cytoprotective roles of HO-1 against hyperglycemia-induced endothelial dysfunction and aberrant angiogenesis and discusses the major underlying cellular mechanisms associated with its protective effects.

Dual Imaging-Guided Oxidative-Photothermal Combination Anticancer Therapeutics

Heme oxygenase-1 (HO-1) is a stress-response protein with potent cytoprotective and antioxidant activity, and its expression in cancer cells is enhanced in response to chemotherapy and radiotherapy. HO-1 is known to serve as a shield to protect cancer cells from anticancer therapy and attenuate apoptotic signals. It can be therefore reasoned that inhibition of HO-1 reduces the antioxidant level, making cancer cells more sensitive to photothermal heating. In this work, we developed dual imaging-guided oxidative-photothermal combination nanotherapeutics (OPCN) consisting of amphiphilic polymers conjugated with zinc protoporphyrin as a HO-1 inhibitor and fluorescent IR820 as a photothermal agent. A combination of OPCN and near-infrared (NIR) laser irradiation markedly increased the temperature and exerted significant toxicity through induction of apoptosis. In a mouse model of xenografts, tumors were identified by the strong fluorescence and photoacoustic signals. OPCN combined with NIR laser irradiation resulted in effective and complete thermal ablation of tumors without discernable side effects and tumor recurrence. We believe that OPCN hold tremendous translational potential for dual imaging-guided oxidative-photothermal combination anticancer therapy.

Apoptosis and autophagy induced by DVDMs-PDT on human esophageal cancer Eca-109 cells

BACKGROUND

Esophageal cancer is a common gastrointestinal cancer. About 300,000 people die from esophageal cancer every year in the world. Photodynamic therapy (PDT) has attracted attention as a feasible cancer therap for this diagnosis. Sinoporphyrin sodium (DVDMs) is a novel sensitizer isolated from photofrin. In this study, we aimed to investigate the effects of DVDMs mediated photodynamic therapy and the possible mechanism on human esophageal cancer Eca-109 cells.

METHODS

Cell viability was measured by MTT assay and cell apoptosis was determined by Annexin V-PE/7-AAD and western blot. MDC staining and western blot were used to evaluate cell autophagy. The production of intracellular reactive oxygen species (ROS) was detected by flow cytometry. The expression of MAPK and HO-1 were detected by western blot.

RESULTS

DVDMs-PDT decreased cell viability and induced cell apoptosis and autophagy. Autophagy inhibition reduced cell apoptosis triggered by DVDMs-PDT in Eca-109 cells. Generation of ROS was detected in DVDMs-PDT group. p38MAPK, JNK and HO-1 were activated after PDT treatment and the activation were reversed by adding ROS scavenger NAC.

CONCLUSIONS

Our studies demonstrated that DVDMs-PDT induced apoptosis and autophagy in Eca-109 cells. DVDMs-PDT induced ROS generation in Eca-109 cells, and the generation of ROS activated p38MAPK and JNK. Activation of p38MAPK and JNK may be involved in PDT-induced apoptosis.

Safety evaluation of repeated intravenous infusion of sinoporphyrin with and without PDT in rats

Photodynamic therapy (PDT) is a promising antineoplastic modality in the oncology field. We assessed the safety of repeated intravenous administrations of sinoporphyrin, a porphyrin derivative, with and without illumination in rats. Toxicokinetic studies of single and multiple administrations of sinoporphyrin were also carried out. Sprague-Dawley rats were randomly assigned to the dark-toxicity and PDT groups. Animals in the dark toxicity group received an i.v. infusion of sinoporphyrin at 3 doses: 2 mg kg^-1, 6 mg kg^-1, and 18 mg kg^-1. The PDT group included 2 doses of sinoporphyrin (2 mg kg^-1 and 18 mg kg^-1), and the rats received 60 J of 630 nm laser illumination 24 h after photosensitizer infusion. The treatments were repeated every 7 days for 5 cycles and were followed by a 14-day recovery period. Systematic analyses were conducted at the end of treatment and recovery periods. Blood samples were obtained 5 min, 30 min, 2 h, 8 h, 24 h, 48 h, 72 h, and 96 h after the first and fifth treatments for toxicokinetic studies. Sinoporphyrin-PDT led to the death of one out of 270 rats; the dead animal had been treated with 18 mg kg^-1 sinoporphyrin and died at the end of the fifth PDT treatment. Liver injury, the primary toxicity observed in the study, was identified using biochemical tests, necropsy, and histopathology. Elevated white blood cell and neutrophil counts were found in the rats in both the dark toxicity and PDT groups. Skin lesions at the illumination site were obvious in the PDT group. Pigment deposits were detected in multiple organs such as the liver, spleen, lymph nodes, and ovaries in the 6 mg kg^-1 and 18 mg kg^-1 groups. No other abnormalities were observed. The toxicokinetic parameters of single and multiple sinoporphyrin administrations were calculated and compared. Repeated sinoporphyrin administrations both alone and in combination with laser illumination were tolerable, and all toxicities were transient. The no observed adverse effect level (NOAEL) for repeated sinoporphyrin administration and sinoporphyrin-PDT was 6 mg kg^-1 and 2 mg kg^-1, respectively. Further studies are warranted.

A review on heme oxygenase-1 induction: is it a necessary evil

Heme oxygenase-1 (HO-1) is considered to be the main protein in diseases arising as a result of oxidative and inflammatory insults. Tremendous research has been carried out on HO-1 since years, pertaining its cytoprotective effect against oxidative injury and other cellular stresses. HO-1, by regulating intracellular levels of pro-oxidant heme, or by other benefits of its by-products such as carbon monoxide (CO) and biliverdin (BV) had become an important candidate protein to be up-regulated to combat diverse stressful events. Although the beneficial effects of HO-1 induction have been reported in a number of cells and tissues, a growing body of evidence indicates that this increased HO-1 expression may lead to the progression of several diseases such as neurodegeneration, carcinogenesis. But it is not clear, what accounts for the increased expression of HO-1 in cells and tissues. The observed friendly role of HO-1 in a wide range of stress conditions since times is now doubtful. Therefore, more studies are needed to elucidate the exact role of HO-1 in various stressful events. Being more concise, elucidating the effect of HO-1 up-regulation on critical genes involved in particular diseases such as cancer will help to a larger extent to comprehend the exact role of HO-1. This review will assist in understanding the dual role (protective and detrimental) of HO-1 and the signaling pathway involved and will help in unraveling the doubtful role of HO-1 induction.

An experimental investigation of a novel iron chelating protoporphyrin IX prodrug for the enhancement of photodynamic therapy

Objectives

Non‐melanoma skin cancers are the most frequently occurring type of cancer worldwide. They can be effectively treated using topical dermatological photodynamic therapy (PDT) employing protoporphyrin IX (PpIX) as the active photosensitising agent as long as the disease remains superficial. Novel iron chelating agents are being investigated to enhance the effectiveness and extend the applications of this treatment modality, as limiting free iron increases the accumulation of PpIX available for light activation and thus cell kill.

Methods

Human lung fibroblasts (MRC‐5) and epithelial squamous carcinoma (A431) cells were treated with PpIX precursors (aminolaevulinic acid [ALA] or methyl‐aminolevulinate [MAL]) with or without the separate hydroxypyridinone iron chelating agent (CP94) or alternatively, the new combined iron chelator and PpIX producing agent, AP2‐18. PpIX fluorescence was monitored hourly for 6 hours prior to irradiation. PDT effectiveness was then assessed the following day using the lactate dehydrogenase and neutral red assays.

Results

Generally, iron chelation achieved via CP94 or AP2‐18 administration significantly increased PpIX fluorescence. ALA was more effective as a PpIX‐prodrug than MAL in A431 cells, corresponding with the lower PpIX accumulation observed with the latter congener in this cell type. Addition of either iron chelating agent consistently increased PpIX accumulation but did not always convey an extra beneficial effect on PpIX‐PDT cell kill when using the already highly effective higher dose of ALA. However, these adjuvants were highly beneficial in the skin cancer cells when compared with MAL administration alone. AP2‐18 was also at least as effective as CP94 + ALA/MAL co‐administration throughout and significantly better than CP94 supplementation at increasing PpIX fluorescence in MRC5 cells as well as at lower doses where PpIX accumulation was observed to be more limited.

Conclusions

PpIX fluorescence levels, as well as PDT cell kill effects on irradiation can be significantly increased by pyridinone iron chelation, either via the addition of CP94 to the administration of a PpIX precursor or alternatively via the newly synthesized combined PpIX prodrug and siderophore, AP2‐18. The effect of the latter compound appears to be at least equivalent to, if not better than, the separate administration of its constituent parts, particularly when employing MAL to destroy skin cancer cells. AP2‐18 therefore warrants further detailed analysis, as it may have the potential to improve dermatological PDT outcomes in applications currently requiring enhancement. Lasers Surg. Med. 50:552–565, 2018. © 2018 The Authors. Lasers in Surgery and Medicine Published by Wiley Periodicals, Inc.

A comparative study of using free radical generators in the testing of chosen oxidative stress parameters in the different types of cells

The aim of this study was to assess whether there are differences between the results of determining oxidative stress markers obtained from different origin cell lines after exposure to chemicals generating free radicals. The studies considered two markers of oxidative stress: the level of thiobarbituric acid reactive substances (TBARS) and superoxide dismutase activity. The evaluation was performed in five cell lines: Chinese hamster ovary (CHO-9) cells, lung adenocarcinoma A549, macrophages RAW264.7, skin carcinoma cells A431, and keratinocytes HaCaT. Three compounds generating free radicals were used as a source of reactive oxygen/nitrogen: 2,2'-azobis-2-methyl-propanimidamide dihydrochloride (AAPH), sodium persulfate (SP), and 3-morpholinosydnonimine hydrochloride (SIN-1). The most appropriate cell line to assess the level of TBARS proved to be the murine macrophage cell line RAW 264.7. Equally, good performance was observed in the lung cancer cell line A549, but only when tested with AAPH and SP. In the case of measuring superoxide dismutase activity, it appeared that the most suitable cell line was also the RAW 264.7 line, although dispersion increased significantly at the highest concentrations of AAPH and SP measurements. When choosing a cell line to determine oxidative stress, the specificity of the stress-inducing compound and the parameter determined should be taken into consideration.

Heme oxygenase inhibition in cancers: possible tools and targets

Heme oxygenase-1 (HO-1, encoded by HMOX1) through degradation of pro-oxidant heme into carbon monoxide (CO), ferrous ions (Fe²⁺) and biliverdin, exhibits cytoprotective, anti-apoptotic and anti-inflammatory properties. All of these potentially beneficial functions of HO-1 may play an important role in tumors’ development and progression. Moreover, HO-1 is very often upregulated in tumors in comparison to healthy tissues, and its expression is further induced upon chemo-, radio- and photodynamic therapy, what results in decreased effectiveness of the treatment. Consequently, HO-1 can be proposed as a therapeutic target for anticancer treatment in many types of tumors. Nonetheless, possibilities of specific inhibition of HO-1 are strongly limited. Metalloporphyrins are widely used in in vitro studies, however, they are unselective and may exert serious side effects including an increase in HMOX1 mRNA level. On the other hand, detailed information about pharmacokinetics and biodistribution of imidazole-dioxolane derivatives, other potential inhibitors, is lacking. The genetic inhibition of HO-1 by RNA interference (RNAi) or CRISPR/Cas9 approaches provides the possibility to specifically target HO-1; however, the potential therapeutic application of those methods are distant at best. In summary, HO-1 inhibition might be the valuable anticancer approach, however, the ideal strategy for HO-1 targeting requires further studies.

Association between (GT)n Repeats in Heme Oxygenase-1 Gene Promoter and 3-Year Survival of Patients with Acute Leukemia: a Controlled, Cross-Sectional Study

Background: Acute leukemia is a common pediatric cancer. Novel strategies for treatment of acute leukemia have been developed, but treatment resistance is remained as the most problematic issue. It is hypothesized that the HO-1 gene up-regulation is responsible for tumor resistance to chemotherapy or radiotherapy-induced apoptosis. The levels of HO-1 expression are related to (GT)_n microsatellite polymorphisms in the location of its promoter. This study designed to compare allelic frequencies of (GT)_n microsatellite polymorphisms in HO-1 gene between acute leukemia patients and healthy controls. Indeed, 3-year disease-free survival was also evaluated. Methods: Sixty-three patients with acute leukemia and seventy healthy infants were included in this study. We used the medical records of patients to collect information about survival after chemotherapy. The number of GT repeats in HO-1 promoter was determined by an ABI 3100 sequencer. Results: The HO-1 GT repeats ranged from 14 to 34 with peaks at 27 repeats in both cases and controls. Children with longer alleles ((GT)_n ≥ 27) had enhanced 3-year survival rate after treatment with chemotherapy or radiotherapy (P<0.05). Conclusion: Although no significant differences were observed between leukemia patients and controls regarding allelic frequency, we found elevated frequency of "LL" genotype in leukemia patients with good prognosis and 3-year surveillance. Radiotherapy and chemotherapy might elevate the expression levels of HO-1 with subsequent increased resistance of leukemia patients to therapy.

Novel carbohydrate-substituted metallo-porphyrazine comparison for cancer tissue-type specificity during PDT

A longstanding obstacle to cancer eradication centers on the heterogeneous nature of the tissue that manifests it. Variations between cancer cell resistance profiles often result in a survival percentage following classic therapeutics. As an alternative, photodynamic therapys' (PDT) unique non-specific cell damage mechanism and high degree of application control enables it to potentially deliver an efficient treatment regime to a broad range of heterogeneous tissue types thereby overcoming individual resistance profiles. This study follows on from previous design, characterization and solubility analyses of three novel carbohydrate-ligated zinc-porphyrazine (Zn(II)Pz) derivatives. Here we report on their PDT application potential in the treatment of five common cancer tissue types in vitro. Following analyses of metabolic homeostasis, toxicity and cell death induction, overall Zn(II)Pz-PDT proved comparably efficient between all cancer tissue populations. Differential localization patterns of Zn(II)Pz derivatives between cell types did not appear to influence the overall PDT effect. All cell types exhibited significant disruptions to mitochondrial activity and associated ATP production levels. Toxicity and chromatin structure profiles revealed indiscernible patterns of damage between Zn(II)Pz derivatives and cell type. The subtle differences observed between individual Zn(II)Pz derivatives is most likely due to a combination of carbohydrate moiety characteristics on energy transfer processes and associated dosage optimization requirements per tissue type. Collectively, this indicates that resistance profiles are negated to a significant extent by Zn(II)Pz-PDT making these derivatives attractive candidates for PDT applications across multiple tissue types and subtypes.

HO-1 Induction in Cancer Progression: A Matter of Cell Adaptation

The upregulation of heme oxygenase-1 (HO-1) is one of the most important mechanisms of cell adaptation to stress. Indeed, the redox sensitive transcription factor Nrf2 is the pivotal regulator of HO-1 induction. Through the antioxidant, antiapoptotic, and antinflammatory properties of its metabolic products, HO-1 plays a key role in healthy cells in maintaining redox homeostasis and in preventing carcinogenesis. Nevertheless, several lines of evidence have highlighted the role of HO-1 in cancer progression and its expression correlates with tumor growth, aggressiveness, metastatic and angiogenetic potential, resistance to therapy, tumor escape, and poor prognosis, even though a tumor- and tissue-specific activity has been observed. In this review, we summarize the current literature regarding the pro-tumorigenic role of HO-1 dependent tumor progression as a promising target in anticancer strategy.

Au Nanoclusters and Photosensitizer Dual Loaded Spatiotemporal Controllable Liposomal Nanocomposites Enhance Tumor Photodynamic Therapy Effect by Inhibiting Thioredoxin Reductase

Photodynamic therapy (PDT) is a minimally invasive therapeutic procedure of tumors with high selectivity and low side effect. However, it is usually not efficient in long-lasting tumor control. One of the main reasons is tumor cells develop some protective mechanisms that help them to deal with oxidative stress in the environment. The thioredoxin system in cancer is an important antioxidant defense system. Au nanoclusters could effectively inhibit thioredoxin reductase (TrxR) in tumor cell cytoplasm. Herein, Au nanoclusters and photosensitizer Chlorine 6 (Ce6) are co-loaded in spatiotemporal controllable liposomal nanocomposites. pH responsive molecule inserted in lipid bilayer greatly contributes to the instability of the lipid membrane in lysosomal at low pH environment. Then the payloads can rapidly release into cytoplasm. Au nanoclusters effectively inhibit TrxR in cytoplasm and enhance the photodynamic-induced intracellular reactive oxygen-free radical concentration, improving the effect of PDT. Breast cancer is chosen as a tumor model and the Au nanoclusters and photosensitizer co-loaded liposomal nanocomposites are studied to improve the effect of PDT both in vitro and in vivo, and its corresponding mechanism is investigated. This study develops a new application of gold nanoclusters and provides a new train of thoughts for enhancing the effect of PDT.