High expression of heme oxygenase-1 is associated with tumor invasiveness and poor clinical outcome in non-small cell lung cancer patients

Novel Acetamide-Based HO-1 Inhibitor Counteracts Glioblastoma Progression by Interfering with the Hypoxic-Angiogenic Pathway

Glioblastoma multiforme (GBM) represents the deadliest tumor among brain cancers. It is a solid tumor characterized by uncontrolled cell proliferation generating the hypoxic niches in the cancer core. By inducing the transcription of hypoxic inducible factor (HIF), hypoxia triggers many signaling cascades responsible for cancer progression and aggressiveness, including enhanced expression of vascular endothelial growth factor (VEGF) or antioxidant enzymes, such as heme oxygenase-1 (HO-1). The present work aimed to investigate the link between HO-1 expression and the hypoxic microenvironment of GBM by culturing two human glioblastoma cell lines (U87MG and A172) in the presence of a hypoxic mimetic agent, deferoxamine (DFX). By targeting hypoxia-induced HO-1, we have tested the effect of a novel acetamide-based HO-1 inhibitor (VP18/58) on GBM progression. Results have demonstrated that hypoxic conditions induced upregulation and nuclear expression of HO-1 in a cell-dependent manner related to malignant phenotype. Moreover, our data demonstrated that the HO-1 inhibitor counteracted GBM progression by modulating the HIFα/HO-1/VEGF signaling cascade in cancer cells bearing more malignant phenotypes.

Effect of Pyridoxine Derivative B6NO on Transcription Factor Nrf2 Activity and Cytotoxic Properties of Doxorubicin In Vitro

The effect of a new pyridoxine derivative B6NO on doxorubicin cytotoxicity and Nrf2-dependent cellular processes in vitro was studied. Antioxidant B6NO enhances the cytotoxic effect of doxorubicin on tumor cells, which is associated with G2/M cell division arrest and an increase in activity of proapoptotic enzyme caspase-3. The antioxidant promotes intracellular accumulation and nuclear translocation of Nrf2 transcription factor in non-tumor and tumor cells. In non-tumor cells, B6NO increases the expression of antioxidant system proteins and reduces ROS generation in the presence of doxorubicin. In tumor cells, no activation of Nrf2-dependent processes occurs under the action of the antioxidant. Our findings demonstrate the prospect of further studies of pyridoxine derivatives as antioxidants to reduce adverse reactions during chemotherapy.

Divergent iron-regulatory states contribute to heterogeneity in breast cancer aggressiveness

Primary tumors with similar mutational profiles can progress to vastly different outcomes where transcriptional state, rather than mutational profile, predicts prognosis. A key challenge is to understand how distinct tumor cell states are induced and maintained. In triple negative breast cancer cells, invasive behaviors and aggressive transcriptional signatures linked to poor patient prognosis can emerge in response to contact with collagen type I. Herein, collagen-induced migration heterogeneity within a TNBC cell line was leveraged to identify transcriptional programs associated with invasive versus non-invasive phenotypes and implicate molecular switches. Phenotype-guided sequencing revealed that invasive cells upregulate iron uptake and utilization machinery, anapleurotic TCA cycle genes, actin polymerization promoters, and a distinct signature of Rho GTPase activity and contractility regulating genes. The non-invasive cell state is characterized by actin and iron sequestration modules along with glycolysis gene expression. These unique tumor cell states are evident in patient tumors and predict divergent outcomes for TNBC patients. Glucose tracing confirmed that non-invasive cells are more glycolytic than invasive cells, and functional studies in cell lines and PDO models demonstrated a causal relationship between phenotype and metabolic state. Mechanistically, the OXPHOS dependent invasive state resulted from transient HO-1 upregulation triggered by contact with dense collagen that reduced heme levels and mitochondrial chelatable iron levels. This induced expression of low cytoplasmic iron response genes regulated by ACO1/IRP1. Knockdown or inhibition of HO-1, ACO1/IRP1, MRCK, or OXPHOS abrogated invasion. These findings support an emerging theory that heme and iron flux serve as important regulators of TNBC aggressiveness.

Telomerase deficiency and dysfunctional telomeres in the lung tumor microenvironment impair tumor progression in NSCLC mouse models and patient-derived xenografts

Non-small cell lung cancer (NSCLC) is a leading cause of cancer death. Tumor progression depends on interactions of cancer cells with the tumor microenvironment. Here, we find increased copy number and mRNA expression of the catalytic subunit of telomerase, TERT, in tumors from NSCLC patients, contributing to a lower survival. Moreover, TERT expression in NSCLC patients from the TCGA cohort is mainly associated to the reduced infiltration of CD8⁺ T lymphocytes, as well as to increased infiltration of myeloid-derived suppressor cells (MDSCs). We also show that TERT deficiency and dysfunctional telomeres induced by 6-thio-dG treatment in mice reduced lung tumor implantation and vascularization, increased DNA damage response, cell cycle arrest and apoptosis, as well as reduced proliferation, inflammation, lung tumor immunosupression and invasion upon induction of a Lewis lung carcinoma (LLC). Furthermore, 6-thio-dG-treated human NSCLC xenografts exhibited increased telomere damage, cell cycle arrest and apoptosis, as well as reduced proliferation, resulting in a reduced tumor growth. Our results show that targeting telomeres might be an effective therapeutic strategy in NSCLC.

Modulation of Nrf2/HO-1 by Natural Compounds in Lung Cancer

Oxidative stresses (OSs) are considered a pivotal factor in creating various pathophysiological conditions. Cells have been able to move forward by modulating numerous signaling pathways to moderate the defects of these stresses during their evolution. The company of Kelch-like ECH-associated protein 1 (Keap1) as a molecular sensing element of the oxidative and electrophilic stress and nuclear factor erythroid 2 (NF-E2)-related factor 2 (Nrf2) as a master transcriptional regulator of the antioxidant response makes a master cytoprotective antioxidant pathway known as the Keap1/Nrf2 pathway. This pathway is considered a dual-edged sword with beneficial features for both normal and cancer cells by regulating the gene expression of the array of endogenous antioxidant enzymes. Heme oxygenase-1 (HO-1), a critical enzyme in toxic heme removal, is one of the clear state indicators for the duality of this pathway. Therefore, Nrf2/HO-1 axis targeting is known as a novel strategy for cancer treatment. In this review, the molecular mechanism of action of natural antioxidants on lung cancer cells has been investigated by relying on the Nrf2/HO-1 axis.

LncRNA UCA1 promoted cisplatin resistance in lung adenocarcinoma with HO1 targets NRF2/HO1 pathway

PURPOSE

Our previous experiments have demonstrated that lncRNA UCA1 (UCA1) promoted cisplatin resistance in lung adenocarcinoma (LUAD). This study aimed to explore the potential downstream target genes regulated by UCA1 and how this downstream gene promotes cisplatin resistance in LUAD.

METHODS

Here, we measured the expression level of Heme oxygenase1 (HO1) in LUAD cell lines by reverse transcription-quantitative polymerase chain reaction (RT-qPCR) based on UCA1 overexpression cell lines and UCA1 knockdown cell lines. HO1 was knocked down in the UCA1 overexpression cell line, and HO1 was overexpressed in the UCA1 knockdown cell line, and the half maximal inhibitory concentration (IC50) trends were observed by adding cisplatin containing a certain concentration gradient. Cell functional assays were performed to observe the changes in the biological behavior of HO1 after overexpression and knockdown, and the tumorigenic assay in nude mice was performed to verify the effect of UCA1 in regulating the growth and cisplatin resistance of HO1 on LUAD cells in vivo.

RESULTS

The results showed that HO1 and UCA1 expression were both upregulated in LUAD tissues and LUAD cisplatin-resistant cell lines, and there was a significant positive correlation between the expression of HO1 and UCA1. In vitro experiments showed that HO1 overexpression could reverse the reduced sensitivity to cisplatin caused by UCA1 knockdown in A549/DDP cells, and HO1 knockdown could reduce cisplatin resistance in A549 UCA1 overexpressing cells. Tumorigenic assays in nude mice further confirmed the role of HO1 in the regulation of UCA1 by activating the NRF2/HO1 pathway against LUAD cisplatin resistance.

CONCLUSION

Our findings suggested that UCA1 regulates HO1 targets the UCA1/NRF2-HO1 pathway to exert cisplatin resistance in LUAD.

The dual role and mutual dependence of heme/HO-1/Bach1 axis in the carcinogenic and anti-carcinogenic intersection

INTRODUCTION

In physiological concentrations, heme is nontoxic to the cell and is essential for cell survival and proliferation. Increasing intracellular heme concentrations beyond normal levels, however, will lead to carcinogenesis and facilitate the survival of tumor cells. Simultaneously, heme in an abnormally high quantity is also a potent inducer of tumor cell death, contributing to its ability to generate oxidative stress on the cells by boosting oxidative phosphorylation and suppressing tumors through ferroptosis. During tumorigenesis and progression, therefore, heme works as a double-edged sword. Heme oxygenase 1 (HO-1) is the rate-limiting enzyme in heme catabolism, which converts heme into physiologically active catabolites of carbon monoxide (CO), biliverdin, and ferrous iron (Fe²⁺). HO-1 maintains redox equilibrium in healthy cells and functions as a carcinogenesis inhibitor. It is widely recognized that HO-1 is involved in the adaptive response to cellular stress and the anti-inflammation effect. Notably, its expression level in cancer cells corresponds with tumor growth, aggressiveness, metastasis, and angiogenesis. Besides, heme-binding transcription factor BTB and CNC homology 1 (Bach1) play a critical regulatory role in heme homeostasis, oxidative stress and senescence, cell cycle, angiogenesis, immune cell differentiation, and autoimmune disorders. Moreover, it was found that Bach1 influences cancer cells' metabolism and metastatic capacity. Bach1 controls heme level by adjusting HO-1 expression, establishing a negative feedback loop.

MATERIALS AND METHODS

Herein, the authors review recent studies on heme, HO-1, and Bach1 in cancer. Specifically, they cover the following areas: (1) the carcinogenic and anticarcinogenic aspects of heme; (2) the carcinogenic and anticarcinogenic aspects of HO-1; (3) the carcinogenic and anticarcinogenic aspects of Bach1; (4) the interactions of the heme/HO-1/Bach1 axis involved in tumor progression.

CONCLUSION

This review summarized the literature about the dual role of the heme/HO-1/Bach1 axis and their mutual dependence in the carcinogenesis and anti-carcinogenesis intersection.

CRISPR/Cas9-mediated knockout of HO-1 decreased the proliferation and migration of T47D cells and increased cisplatin-induced apoptosis: an in vitro study

Breast cancer is the most common type of neoplasm and the second cause of cancer-related death in women. Despite the development of novel therapeutic strategies and improved the clinical outcomes, the mortality rate for breast cancer is still high. Therefore, development of a new modality, particularly based on knocking out key genes, is under focus of investigation. Heme oxygenase-1 (HO-1) deregulation has been associated with various neoplasms-related behaviors of many types of tumor cells including breast cancer. In the current study, in order to evaluate the role of the HO-1 gene in breast cancer, we utilized the CRISPR/Cas9 technology to knock out HO-1 gene in T47D breast cancer cell line and studied its potential therapeutic effects in vitro. The cell proliferation and their sensitivity to Cisplatin were determined by CCK-8 kit. In addition, the apoptosis and the migratory potential of the cells were evaluated using Hoechst staining, and Transwell/Scratch methods, respectively. Our findings revealed that HO-1 suppression significantly reduced the proliferation ability of T47D cells (P < 0.001). Moreover, sensitivity to Cisplatin-induced toxicity increased significantly in KO-T47D cells compared to the control T47D cells. Furthermore, our findings indicated that Cisplatin-induced apoptosis increased in the KO-T47D cells. Moreover, the migratory capability of KO-T47D cells was abolished significantly (P < 0.001) as determined by Transwell migration assay. In a nutshell, our findings strongly suggest that HO-1 involved in breast cancer progression and metastasis and chemotherapy resistance. However, further comprehensive studies are required to clarify the precise role of the HO-1 gene on breast cancer cells.

HMOX1 promotes lung adenocarcinoma metastasis by affecting macrophages and mitochondrion complexes

Background

Metastasis is the leading cause of lung adenocarcinoma (LUAD) patient death. However, the mechanism of metastasis is unclear. We performed bioinformatic analyses for HMOX1 (Heme oxygenase-1), aiming to explore its role in LUAD metastasis.

Methods

Pan-cancer analysis was first used to identify the metastasis-associated role of HMOX1 in LUAD. HMOX1-related genomic alterations were then investigated. Based on functional enrichment, we systematically correlated HMOX1 with immunological characteristics and mitochondrial activities. Furthermore, weighted gene co-expression network analysis (WGCNA) was applied to construct the HMOX1-mediated metastasis regulatory network, which was then validated at the proteomic level. Finally, we conducted the survival analysis and predicted the potential drugs to target the HMOX1 network.

Results

HMOX1 expression was significantly associated with epithelial-mesenchymal transition (EMT) and lymph and distant metastasis in LUAD. High HMOX1 levels exhibited higher macrophage infiltration and lower mitochondrial complex expression. WGCNA showed a group of module genes co-regulating the traits mentioned above. Subsequently, we constructed an HMOX1-mediated macrophage-mitochondrion-EMT metastasis regulatory network in LUAD. The network had a high inner correlation at the proteomic level and efficiently predicted prognosis. Finally, we predicted 9 potential drugs targeting HMOX1-mediated metastasis in LUAD, like chloroxine and isoliquiritigenin.

Conclusions

Our analysis elaborates on the role of HMOX1 in LUAD metastasis and identified a highly prognostic HMOX1-mediated metastasis regulatory network. Novel potential drugs targeting the HMOX1 network were also proposed, which should be tested for their activity against LUAD metastasis in future studies.

Assessing the Prognostic Capability of Immune-Related Gene Scoring Systems in Lung Adenocarcinoma

Background

Lung adenocarcinoma (LUAD) is the commonest of the subtypes of lung cancer histologically. For this study, we intended to analyze the expression profiling of the immune-related genes (IRGs) from an independently available public database and developed a potent signature predictive of patients' prognosis.

Methods

Gene expression profiles and the clinical data of lung adenocarcinoma were gathered from the Gene Expression Omnibus database (GEO) and The Cancer Genome Atlas (TCGA), and the obtained data were split into a training set (n = 226), test set (n = 83), and validation set (n = 400). IRGs were then gathered from the ImmPort database. A prognostic model was constructed by analyzing the training set. Then the GO and KEGG analysis was performed, and a gene correlation prognostic nomogram was constructed. Finally, external validation, such as immune infiltration and immunohistochemistry, was performed.

Results

The 110 genes were significant by univariate Cox regression analysis and randomized survival forest algorithm for the training set and showed a good distinction between the low-risk-score and high-risk-score groups in the training set (P < 0.0001) by screening for four prognosis-related genes (HMOX1, ARRB1, ADM, PDIA3) and validated by the test set GSE30219 (P=0.0025) and TCGA dataset (P=0.00059). Multivariate Cox showed that the four gene signatures were an individual risk factor for LUAD. In addition, the genes in the signatures were externally verified using an online database. In particular, PDIA3 and HMOX1 are essential genes in the prognostic nomogram and play an important role in the model of immune-related genes.

Conclusion

Four immune-related genetic signatures are reliable prognostic indicators for patients with LUAD, providing a relevant theoretical basis and therapeutic rationale for immunotherapy.

The Nuclear Translocation of Heme Oxygenase-1 in Human Diseases

Heme oxygenase-1 (HO-1) is a rate-limiting enzyme in the degradation of heme to generate carbon monoxide (CO), free iron and biliverdin, which could then be converted to bilirubin by biliverdin reductase. HO-1 exhibits cytoprotective effects of anti-apoptosis, anti-oxidation, and anti-inflammation via these byproducts generated during the above process. In the last few years, despite the canonical function of HO-1 and possible biological significance of its byproducts, a noncanonical function, through which HO-1 exhibits functions in diseases independent of its enzyme activity, also has been reported. In this review, the noncanonical functions of HO-1 and its translocation in other subcellular compartments are summarized. More importantly, we emphasize the critical role of HO-1 nuclear translocation in human diseases. Intriguingly, this translocation was linked to tumorigenesis and tumor progression in lung, prostate, head, and neck squamous cell carcinomas and chronic myeloid leukemia. Given the importance of HO-1 nuclear translocation in human diseases, nuclear HO-1 as a novel target might be attractive for the prevention and treatment of human diseases.

IGF1R acts as a cancer-promoting factor in the tumor microenvironment facilitating lung metastasis implantation and progression

Given the long-term ineffectiveness of current therapies and late-stage diagnoses, lung cancer is a leading cause of malignant diseases. Tumor progression is influenced by cancer cell interactions with the tumor microenvironment (TME). Insulin-like growth factor 1 receptor (IGF1R) was reported to affect the TME; however, the role of IGF1R in lung TME has not been investigated. First, we assessed IGF1R genomic alterations and expression in NSCLC patient tissue samples, as well as IGF1R serum levels. Next, we performed tumor heterotopic transplantation and pulmonary metastases in IGF1R-deficient mice using melanoma and Lewis lung carcinoma (LLC) cells. Herein we report increased amplification and mRNA expression, as well as increased protein expression (IGF1R/p-IGF1R) and IGF1R levels in tumor samples and serum from NSCLC patients, respectively. Moreover, IGF1R deficiency in mice reduced tumor growth, proliferation, inflammation and vascularization, and increased apoptosis after tumor heterotopic transplantation. Following induction of lung metastasis, IGF1R-deficient lungs also demonstrated a reduced tumor burden, and decreased expression of tumor progression markers, p-IGF1R and p-ERK1/2. Additionally, IGF1R-deficient lungs showed increased apoptosis and diminished proliferation, vascularization, EMT and fibrosis, along with attenuated inflammation and immunosuppression. Accordingly, IGF1R deficiency decreased expression of p-IGF1R in blood vessels, fibroblasts, tumor-associated macrophages and FOXP3⁺ tumor-infiltrating lymphocytes. Our results demonstrate that IGF1R promotes metastatic tumor initiation and progression in lung TME. Furthermore, our research indicates that IGF1R could be a potential biomarker for early prediction of drug response and clinical evolution in NSCLC patients.

Expression Dynamics of Heme Oxygenase-1 in Tumor Cells and the Host Contributes to the Progression of Tumors

Heme oxygenase (HO-1) plays an important role in cellular protection against various stresses. The induction of HO-1 is an effective strategy for reactive oxygen species-related diseases, inflammatory diseases, as well as suppressing carcinogenesis. On the other hand, the high expression of HO-1 is now well known in many tumors. In this study, we investigated the dynamics of HO-1 expression in the host and the tumor. In the mouse sarcoma S180 solid tumor model and the rat hepatoma AH136B ascitic tumor model, HO-1 expression in the tumor, as indicated by the end product of HO-1 activation, i.e., carbon monoxide, gradually increased along with tumor growth. Over-expression of HO-1 expression in mouse colon cancer C26 tumor cells significantly promoted tumor growth as well as lung metastasis, whereas opposite results were found when the HO-1 expression was reduced in the cells. On the other hand, upregulating HO-1 levels in the host by using an HO-1 inducer protected the progression of the xenograft tumor in mice, whereas lowering HO-1 expression in the host with an HO-1 inhibitor showed accelerated tumor growth and lung metastasis after subcutaneous tumor xenograft inoculation. These findings strongly suggest that the balance of HO-1 levels in the host and the tumor cells is essential for the occurrence, progression, and prognosis of cancer. Maintenance of appropriately high HO-1 levels in the host is favorable for cancer prevention, whereas suppression of HO-1 in the tumor cells may thus become a therapeutic strategy for cancer.

FLLL32 Triggers Caspase-Mediated Apoptotic Cell Death in Human Oral Cancer Cells by Regulating the p38 Pathway

Oral cancer is the most common oral malignant tumor in Taiwan. Although there exist several methods for treatment, oral cancer still has a poor prognosis and high recurrence. FLLL32, a synthetic analog of curcumin with antitumor activity, is currently known to induce melanoma apoptosis and inhibit tumor growth in various cancers. However, few studies have examined the mechanisms of FLLL32 in oral cancer. In this study, we explore whether FLLL32 induces apoptosis in oral cancer. We determined that FLLL32 can inhibit the cell viability of oral cancer. Next, we analyzed the effect of FLLL32 on the cell cycle of oral cancer cells and observed that the proportion of cells in the G2/M phase was increased. Additionally, annexin-V/PI double staining revealed that FLLL32 induced apoptosis in oral cancer cells. Data from the Human Apoptosis Array revealed that FLLL32 increases the expression of cleaved caspase-3 and heme oxygenase-1 (HO-1). FLLL32 activates proteins such as caspase-8, caspase-9, caspase-3, PARP, and mitogen-activated protein kinases (MAPKs) in apoptosis-related molecular mechanisms. Moreover, by using MAPK inhibitors, we suggest that FLLL32 induces the apoptosis of oral cancer cells through the p38 MAPK signaling pathway. In conclusion, our findings suggest that FLLL32 is a potential therapeutic agent for oral cancer by inducing caspase-dependent apoptosis and HO-1 activation through the p38 pathway. We believe that the activation of HO-1 and the p38 pathway by FLLL32 represent potential targets for further research in oral cancer.

Discovery of Novel Acetamide-Based Heme Oxygenase-1 Inhibitors with Potent In Vitro Antiproliferative Activity

Heme oxygenase-1 (HO-1) promotes heme catabolism exercising cytoprotective roles in normal and cancer cells. Herein, we report the design, synthesis, molecular modeling, and biological evaluation of novel HO-1 inhibitors. Specifically, an amide linker in the central spacer and an imidazole were fixed, and the hydrophobic moiety required by the pharmacophore was largely modified. In many tumors, overexpression of HO-1 correlates with poor prognosis and chemoresistance, suggesting the inhibition of HO-1 as a possible antitumor strategy. Accordingly, compounds 7i and 7l-p emerged for their potency against HO-1 and were investigated for their anticancer activity against prostate (DU145), lung (A549), and glioblastoma (U87MG, A172) cancer cells. The selected compounds showed the best activity toward U87MG cells. Compound 7l was further investigated for its in-cell enzymatic HO-1 activity, expression levels, and effects on cell invasion and vascular endothelial growth factor (VEGF) extracellular release. The obtained data suggest that 7l can reduce cell invasivity acting through modulation of HO-1 expression.

Antidiabetic Agent DPP-4i Facilitates Murine Breast Cancer Metastasis by Oncogenic ROS-NRF2-HO-1 Axis via a Positive NRF2-HO-1 Feedback Loop

Cancer has been as one of common comorbidities of diabetes. Long-term antidiabetic treatment may potentially exert uncertain impacts on diabetic patients with cancer including breast cancer (BC). Dipeptidyl peptidase-4 inhibitors (DPP-4i) are currently recommended by the AACE as first-line hypoglycemic drugs in type 2 diabetes mellitus (T2DM). Although the safety of DPP-4i has been widely evaluated, the potential side-effects of DPP-4i in cancer metastasis were also reported and remain controversial. Here, we revealed that Saxagliptin (Sax) and Sitagliptin (Sit), two common DPP-4i compounds, potentially promoted murine BC 4T1 metastasis in vitro and in vivo under immune-deficient status. Mechanically, we observed that DPP-4i treatment induced aberrant oxidative stress by triggering ROS overproduction, as well as ROS-dependent NRF2 and HO-1 activations in BC cells, while specific inhibition of ROS, NRF2 or HO-1 activations abrogated DPP-4i-driven BC metastasis and metastasis-associated gene expression in vitro. Furthermore, ALA, a NRF2 activator significantly promoted BC metastasis in vitro and in vivo, which can be abrogated by specific HO-1 inhibition in vitro. Moreover, specific HO-1 inhibition not only reversed DPP-4i-induced NRF2 activation but also abrogated ALA-induced NRF2 activation, resulting in a decrease of metastasis-associated genes, indicating a positive-feedback NRF2-HO-1 loop. Our findings suggest that DPP-4i accelerates murine BC metastasis through an oncogenic ROS-NRF2-HO-1 axis via a positive-feedback NRF2-HO-1 loop. Therefore, this study not only offers novel insights into an oncogenic role of DPP-4i in BC progression but also provides new strategies to alleviate the dark side of DPP-4i by targeting HO-1.

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.

Mitochondrial GRIM-19 deficiency facilitates gastric cancer metastasis through oncogenic ROS-NRF2-HO-1 axis via a NRF2-HO-1 loop

BACKGROUND

NRF2, a prime target of cellular defense against oxidative stress, has shown a dark side profile in cancer progression. GRIM-19, an essential subunit of the mitochondrial MRC complex I, was recently identified as a suppressive role in tumorigenesis of human gastric cancer (GC). However, little information is available on the role of GRIM-19 and its cross-talk with NRF2 in GC metastasis.

METHODS

Online GC database was used to investigate DNA methylation and survival outcomes of GRIM-19. CRISPR/Cas9 lentivirus-mediated gene editing, metastasis mice models and pharmacological intervention were applied to investigate the role of GRIM-19 deficiency in GC metastasis. Quantitative RT-PCR, FACS, Western blot, IHC, IF and reporter gene assay were performed to explore underlying mechanisms.

RESULTS

Low GRIM-19 is correlated with poor survival outcome of GC patients while DNA hypermethylation is associated with GRIM-19 downregulation. GRIM-19 deficiency facilitates GC metastasis and triggers aberrant oxidative stress as well as ROS-dependent NRF2-HO-1 activation. Experimental interventions of specific ROS, NRF2 or HO-1 inhibitor significantly abrogate GRIM-19 deficiency-driven GC metastasis in vitro and in vivo. Moreover, HO-1 inhibition not only reverses GRIM-19 deficiency-driven NRF2 activation, but also feedback blocks NRF2 activator-induced NRF2 signaling, resulting in decreased metastasis-associated genes.

CONCLUSIONS

Our data suggest that GRIM-19 deficiency accelerates GC metastasis through the oncogenic ROS-NRF2-HO-1 axis via a positive-feedback NRF2-HO-1 loop. Therefore, this study not only offers novel insights into the role of oncogenic NRF2 in tumor progression, but also provides new strategies to alleviate the dark side of NRF2 by targeting HO-1.

Development and validation of a robust immune-related prognostic signature in early-stage lung adenocarcinoma

Background

The incidence of stage I and stage II lung adenocarcinoma (LUAD) is likely to increase with the introduction of annual screening programs for high-risk individuals. We aimed to identify a reliable prognostic signature with immune-related genes that can predict prognosis and help making individualized management for patients with early-stage LUAD.

Methods

The public LUAD cohorts were obtained from the large-scale databases including 4 microarray data sets from the Gene Expression Omnibus (GEO) and 1 RNA-seq data set from The Cancer Genome Atlas (TCGA) LUAD cohort. Only early-stage patients with clinical information were included. Cox proportional hazards regression model was performed to identify the candidate prognostic genes in GSE30219, GSE31210 and GSE50081 (training set). The prognostic signature was developed using the overlapped prognostic genes based on a risk score method. Kaplan–Meier curve with log-rank test and time-dependent receiver operating characteristic (ROC) curve were used to evaluate the prognostic value and performance of this signature, respectively. Furthermore, the robustness of this prognostic signature was further validated in TCGA-LUAD and GSE72094 cohorts.

Results

A prognostic immune signature consisting of 21 immune-related genes was constructed using the training set. The prognostic signature significantly stratified patients into high- and low-risk groups in terms of overall survival (OS) in training data set, including GSE30219 (HR = 4.31, 95% CI 2.29–8.11; P = 6.16E−06), GSE31210 (HR = 11.91, 95% CI 4.15–34.19; P = 4.10E−06), GSE50081 (HR = 3.63, 95% CI 1.90–6.95; P = 9.95E−05), the combined data set (HR = 3.15, 95% CI 1.98–5.02; P = 1.26E−06) and the validation data set, including TCGA-LUAD (HR = 2.16, 95% CI 1.49–3.13; P = 4.54E−05) and GSE72094 (HR = 2.95, 95% CI 1.86–4.70; P = 4.79E−06). Multivariate cox regression analysis demonstrated that the 21-gene signature could serve as an independent prognostic factor for OS after adjusting for other clinical factors. ROC curves revealed that the immune signature achieved good performance in predicting OS for early-stage LUAD. Several biological processes, including regulation of immune effector process, were enriched in the immune signature. Moreover, the combination of the signature with tumor stage showed more precise classification for prognosis prediction and treatment design.

Conclusions

Our study proposed a robust immune-related prognostic signature for estimating overall survival in early-stage LUAD, which may be contributed to make more accurate survival risk stratification and individualized clinical management for patients with early-stage LUAD.

Loss of SWI/SNF Chromatin Remodeling Alters NRF2 Signaling in Non-Small Cell Lung Carcinoma

The NF-E2-related factor 2 (referred to as NRF2) transcription factor binds antioxidant responsive elements within the promoters of cytoprotective genes to induce their expression. Next-generation sequencing studies in lung cancer have shown a significant number of activating mutations within the NRF2 signaling pathway. Mutations in components of the SWI/SNF chromatin-remodeling complex, a general regulator of transcription using either BRG1 or BRM as the catalytic subunit, also frequently occur in lung cancers. Importantly, low BRG1 expression levels in primary human NSCLC correlated with increased NRF2-target gene expression. Here, we show that loss of SWI/SNF complex function activated a subset of NRF2-mediated transcriptional targets. Using a series of isogenic NSCLC lines with reduced or depleted BRG1 and/or BRM expression, we observed significantly increased expression of the NRF2-target genes HMOX1 and GSTM4. In contrast, expression of the NRF2 target genes NQO1 and GCLM modestly increased following BRM reduction. Chromatin immunoprecipitation showed that BRG1 knockdown led to increased NRF2 binding at its respective ARE sites in the HMOX1 promoter but not in NQO1 and GCLM. Our data demonstrate that loss of BRG1 or BRM in lung cancer results in activation of the NRF2/KEAP1 pathway and HMOX1 expression. Therefore, we provide an additional molecular explanation for why patients harboring BRG1 or BRM mutations show poor prognoses. A better understanding of this mechanism may yield novel insights into the design of targeted treatment modalities. IMPLICATIONS: Our study identifies a novel mechanism for how mutations in the SMARCA4 gene may drive progression of human lung adenocarcinomas.

Hyperglycemia during Adjuvant Chemotherapy as a Prognostic Factor in Breast Cancer Patients without Diabetes

Purpose

Breast cancer treatments, including chemotherapy, administered in combination with glucocorticoids can induce hyperglycemia. This study aimed to investigate the effect of hyperglycemia during adjuvant chemotherapy on the prognosis of breast cancer patients without a known history of diabetes.

Methods

In this study, 936 patients who underwent breast cancer surgery from 2010 to 2015 were initially selected as participants. Chemotherapy-related hyperglycemia was defined as fasting plasma glucose levels ≥ 100 mg/dL or random blood glucose levels ≥ 140 mg/dL during 2 or more cycles of adjuvant chemotherapy. After dividing the patients into the euglycemia and hyperglycemia groups, univariate and multivariate analyses were performed, and survival outcomes were analyzed by propensity score matching.

Results

The mean age of the patients was 47.4 ± 7.7 years, and the median follow-up period was 70.1 months. Eighty-two patients (19.4%) were diagnosed as having hyperglycemia. There were significant differences between the euglycemia and hyperglycemia groups with respect to age, hypertension, body mass index, axillary surgery extents, nodal stage, and total steroid dosage. T stage, vascular invasion, and hyperglycemia were identified as prognostic factors of relapse-free survival (RFS). The 5-year RFS rates were 92.0% and 82.3% in the euglycemia and hyperglycemia groups, respectively, and there was a statistically significant difference between the 2 groups (p = 0.011). The 5-year overall survival rates were 94.6% and 92.0% in the euglycemia and hyperglycemia groups, respectively, showing no statistically significant difference between the 2 groups (p = 0.113).

Conclusion

These data suggest that hyperglycemia during adjuvant chemotherapy is a prognostic factor for RFS in breast cancer patients without diabetes.

Roles of JNK/Nrf2 Pathway on Hemin-Induced Heme Oxygenase-1 Activation in MCF-7 Human Breast Cancer Cells

Heme oxygenase-1 (HO-1) is highly induced in various human disease states, including cancer, indicating that HO-1 is an emerging target of cancer therapy. In this study, we investigated that the mechanisms of hemin-induced HO-1 expression and its signaling pathways in human breast cancer cell. We used MCF-7 cells, a human breast cancer cell line. Hemin increased HO-1 expression in MCF-7 cells in a dose- and time-dependent manner. Hemin enhanced HO-1 expression through the activation of c-Jun N-terminal kinases (JNK) signaling pathway. Hemin also induced activation of Nrf2, a major transcription factor of HO-1 expression. These responses in MCF-7 cells were completely blocked by pretreatment with brazilin, a HO-1 regulator. These results indicated that brazilin inhibits hemin-induced HO-1 expressions through inactivation of JNK/Nrf2 in MCF-7 cells. Thus, our findings suggest that HO-1 is an important anticancer-target of brazilin in human breast cancer.

Inhibition of ALAS1 activity exerts anti-tumour effects on colorectal cancer in vitro

BACKGROUND/AIMS

Colorectal cancer (CRC) is the third most common malignant tumour worldwide and the second leading cause of cancer-related deaths. Commonly, 5'-aminolevulinic acid synthase1 (ALAS1) is the rate-limiting enzyme for haem biosynthesis. Recent studies have shown that ALAS1 is involved in a number of cellular functions and has significant effects on non-small cell lung cancer (NSCLC). However, current concepts of disease pathogenesis fail to fully explain the role of ALAS1 expression and biological functions in CRC.

MATERIALS AND METHODS

A total of 67 paired tumour tissues and adjacent colorectal tissues were used to detect ALAS1 levels and further analyse the correlation between ALAS1 expression levels and clinical features. Using HCT116 cell lines, we studied the impact of ALAS1 on biological function by knocking down or inhibiting ALAS1.

RESULTS

We found an increase in the levels of ALAS1 in cancer tissues compared to adjacent colorectal tissues. The increase in ALAS1 expression was closely related to the invasion depth, N staging and tumour size of CRC patients. The proliferation and metastasis of CRC cells could be inhibited by suppressing ALAS1.

CONCLUSIONS

The abnormal expression of ALAS1 is closely related to the proliferation and metastasis of CRC cells, suggesting that ALAS1 may be a novel therapeutic target for the treatment of CRC.

Widespread expression of Sonic hedgehog (Shh) and Nrf2 in patients treated with cisplatin predicts outcome in resected tumors and are potential therapeutic targets for HPV-negative head and neck cancer

Background:

Sonic hedgehog (Shh) and Nrf2 play a critical role in chemotherapeutic resistance. These two genes have been found to be dysregulated in head and neck squamous cell carcinomas (HNSCC). The purpose of this study was to analyze the expression, function and clinical prognostic relationship of Shh and Nrf2 in HNSCC in the context of therapeutic resistance and cancer stem cells (CSCs).

Methods:

We analyzed a cohort of patients with HNSCC to identify potential therapeutic biomarkers correlating with overall survival (OS) as well as disease-free survival (DFS) from our own data and validated these results using The Cancer Genome Atlas dataset. Expression of Shh and Nrf2 was knocked down by siRNA and cell growth, sphere growth and chemotherapeutic resistance were evaluated.

Results:

Widespread abundant expression of Shh and Nrf2 proteins were associated with shorter OS and DFS. The combination of Shh and Nrf2 expression levels was found to be a significant predictor of patient DFS. The tumor stromal index was correlated with Shh expression and inversely associated with shorter OS and DFS. Inhibition of Shh by siRNA or cyclopamine resulted in the attenuation of resistant CSC self-renewal, invasion, clonogenic growth and re-sensitization to the chemotherapeutic agents. Concomitant upregulation of Shh and Nrf2 proved to be an independent predictor of poor OS and DFS in patients with HNSCC.

Conclusions:

These findings suggest that Shh and Nrf2 could serve as therapeutic targets as well as promising dual prognostic therapeutic biomarkers for HNSCC.

Non-competitive heme oxygenase-1 activity inhibitor reduces non-small cell lung cancer glutathione content and regulates cell proliferation

Non-small cell lung cancer (NSCLC) remains the leading cause of cancer-related death mainly due to its high metastatic rate. Impairment of redox homeostasis mechanisms has been previously described in NSCLC and is associated with the disease itself as well as with comorbidities such as smoking. The aim of the present in vitro study was to evaluate the effect of selective and non-competitive inhibition of heme oxygenase-1 (HO-1) on cancer redox homeostasis with particular regards to glutathione (GSH) metabolism related enzymes. NSCLC cell line (A549) was treated with the HO-1 activity inhibitor VP13/47 (10 µM) and we further evaluated cell viability, apoptosis, mitochondrial dysfunction and oxidative stress. Our results showed that VP13/47 significantly reduced HO-1 expression and total HO activity thus, resulting in a significant reduction of cell viability, proliferation and increased apoptosis, mitochondrial dysfunction and oxidative stress. Consistently with increased oxidative stress, we also showed that reduced GSH was significantly decreased and such effect was also accompanied by a significant downregulation of the enzymes involved in its biosynthesis. Taken all together our results show that selective HO-1 inhibition significantly impairs NSCLC progression and may represent a possible pharmacological strategy for new chemotherapy agents.

Hyperoside suppresses hypoxia-induced A549 survival and proliferation through ferrous accumulation via AMPK/HO-1 axis

BACKGROUND

Hypoxia is commonly existed in tumors and lead to cancer cell chemo/radio-resistance. It is well-recognized that tumor hypoxia is a major challenge for the treatment of various solid tumors. Hyperoside (quercetin-3-O-galactoside, Hy) possesses antioxidant effects and has been reported to protect against hypoxia/reoxygenation induced injury in cardiomyocytes. Therefore, Hy may be attractive compound applicable to hypoxia-related diseases.

PURPOSE

This study was designed to determine the role of Hy in hypoxia-induced proliferation of non-small cell lung cancer cells and the underlying mechanism.

STUDY DESIGN AND METHODS

A549, a human non-small cell lung cancer (NSCLC) cell line, was used in the present study. 1% O₂ was used to mimic the in vivo hypoxic condition of NSCLC. The potential mechanisms of Hy on hypoxia-induced A549 survival and proliferation, as well as the involvement of AMPK/HO-1 pathway were studied via CCK-8 assay, EdU staining, flow cytometry, qRT-PCR and western blot.

RESULTS

We showed that pretreatment with Hy suppressed hypoxia-induced A549 survival and proliferation in dose-dependent manner. In terms of mechanism, hypoxia-treated A549 showed the lower AMPK phosphorylation and the reduced HO-1 expression, which were reversed by Hy pretreatment. Both AMPK inhibitor (Compound C) and HO-1 activity inhibitor (Zinc protoporphyrin IX) abolished Hy-evoked A549 cell death under hypoxia stimuli. Of note, Ferrous iron contributed to Hy-induced A549 cell death under hypoxia, while Hy had no effect on lipid peroxidation under hypoxia.

CONCLUSION

Taken together, our results highlighted the beneficial role of Hy against hypoxia-induced A549 survival and proliferation through ferrous accumulation via AMPK/HO-1 axis.

Nrf2 and the Nrf2-Interacting Network in Respiratory Inflammation and Diseases

Atmospheric pollutants and cigarette smoke influence the human respiratory system and induce airway inflammation, injury, and pathogenesis. Activation of the NF-E2-related factor 2 (Nrf2) transcription factor and downstream antioxidant response element (ARE)-mediated transcriptions play a central role in protecting respiratory cells against reactive oxidative species (ROS) that are induced by airway toxins and inflammation. Recent studies have revealed that Nrf2 can also target and activate many genes involved in developmental programs such as cell proliferation, cell differentiation, cell death, and metabolism. Nrf2 is closely regulated by the interaction with kelch-like ECH-associated protein 1 (Keap1), while also directly interacts with a number of other proteins, including inflammatory factors, transcription factors, autophagy mediators, kinases, epigenetic modifiers, etc. It is believed that the multiple target genes and the complicated interacting network of Nrf2 account for the roles of Nrf2 in physiologies and pathogeneses. This chapter summarizes the molecular functions and protein interactions of Nrf2, as well as the roles of Nrf2 and the Nrf2-interacting network in respiratory inflammation and diseases, including acute lung injury (ALI), asthma, chronic obstructive pulmonary disease (COPD), pulmonary fibrosis (PF), cystic fibrosis (CF), viral/bacterial infections, and lung cancers. Therapeutic applications that target Nrf2 and its interacting proteins in respiratory diseases are also reviewed.

Molecular Mechanisms Underlying Autophagy-Mediated Treatment Resistance in Cancer

Despite advances in diagnostic tools and therapeutic options, treatment resistance remains a challenge for many cancer patients. Recent studies have found evidence that autophagy, a cellular pathway that delivers cytoplasmic components to lysosomes for degradation and recycling, contributes to treatment resistance in different cancer types. A role for autophagy in resistance to chemotherapies and targeted therapies has been described based largely on associations with various signaling pathways, including MAPK and PI3K/AKT signaling. However, our current understanding of the molecular mechanisms underlying the role of autophagy in facilitating treatment resistance remains limited. Here we provide a comprehensive summary of the evidence linking autophagy to major signaling pathways in the context of treatment resistance and tumor progression, and then highlight recently emerged molecular mechanisms underlying autophagy and the p62/KEAP1/NRF2 and FOXO3A/PUMA axes in chemoresistance.

Role of Heme Oxygenase as a Modulator of Heme-Mediated Pathways

The heme oxygenase (HO) system is essential for heme and iron homeostasis and necessary for adaptation to cell stress. HO degrades heme to biliverdin (BV), carbon monoxide (CO) and ferrous iron. Although mostly beneficial, the HO reaction can also produce deleterious effects, predominantly attributed to excessive product formation. Underrated so far is, however, that HO may exert effects additionally via modulation of the cellular heme levels. Heme, besides being an often-quoted generator of oxidative stress, plays also an important role as a signaling molecule. Heme controls the anti-oxidative defense, circadian rhythms, activity of ion channels, glucose utilization, erythropoiesis, and macrophage function. This broad spectrum of effects depends on its interaction with proteins ranging from transcription factors to enzymes. In degrading heme, HO has the potential to exert effects also via modulation of heme-mediated pathways. In this review, we will discuss the multitude of pathways regulated by heme to enlarge the view on HO and its role in cell physiology. We will further highlight the contribution of HO to pathophysiology, which results from a dysregulated balance between heme and the degradation products formed by HO.

Semaphorin 6A Attenuates the Migration Capability of Lung Cancer Cells via the NRF2/HMOX1 Axis

Cell migration is a fundamental feature of cancer recurrence. Since recurrence is correlated with high mortality in lung cancer, it follows that reducing cell migration would decrease recurrence and increase survival rates. Semaphorin-6A (SEMA6A), a protein initially known as a regulator of axonal guidance, is down-regulated in lung cancer tissue, and low levels of SEMA6A are associated with cancer recurrence. Thus, we hypothesized that SEMA6A could suppress cancer cell migration. In this study, we found that the migration capability of H1299 lung cancer cells decreased with SEMA6A overexpression, while it increased with SEMA6A silencing. Moreover, silencing of the cellular homeostasis protein Heme-oxygenase-1 (HMOX1) and/or the transcription factor Nuclear Factor, Erythroid-2-Like-2 (NRF2) reversed the migration-suppressing effect of SEMA6A and the SEMA6A-driven alterations in expression of urokinase insulin-like-growth-factor-binding-protein-3, Matrix metalloproteinase (MMP)-1, and MMP9, the downstream effectors of HMOX1. Taken together, these results demonstrate that SEMA6A is a potential suppressor of cancer migration that functions through the NRF2/HMOX1 axis. Our results explain why low SEMA6A is linked to high recurrence in the clinical setting and suggest that SEMA6A could be useful as a biomarker or target in lung cancer therapy.

Effects of hyperglycemia on the progression of tumor diseases

Malignant tumors are often multifactorial. Epidemiological studies have shown that hyperglycemia raises the prevalence and mortality of certain malignancies, like breast, liver, bladder, pancreatic, colorectal, endometrial cancers. Hyperglycemia can promote the proliferation, invasion and migration, induce the apoptotic resistance and enhance the chemoresistance of tumor cells. This review focuses on the new findings in the relationship between hyperglycemia and tumor development.

Osthole promotes the suppressive effects of cisplatin on NRF2 expression to prevent drug-resistant cervical cancer progression

Cervical cancer is one of the most commonly diagnosed lethal malignancies among gynecological malignant tumors worldwide. Chemo-resistance is one of the key causal factors in cervical cancer death. Osthole (OST), a natural compound, exhibits various pharmacological activities, including anti-tumor effects. However, its involvement in the chemoresistance of human cervical cancer has not been reported. In the study, we aimed to clarify the role of OST in regulating the chemoresistance of human cervical cancer. The results indicated that cisplatin (CDDP) combined with OST markedly reduced the cell proliferation and induced cervical cancer cells undergoing apoptosis when compared to CDDP alone treatment. In CDDP-resistant cervical cancer cells, OST significantly decreased nuclear factor, erythroid 2 like 2 (NRF2), heme oxygenase-1 (HO-1), NAD(P)H quinone dehydrogenase 1 (NQO1) and glutamate-cysteine ligase catalytic subunit (GCLC) expression levels from mRNA or protein levels. Additionally, through combination with CDDP, OST dose- and time-dependently reduced NRF2 expression in CDDP-resistant cervical cancer cells. Moreover, we found that CDDP co-treated with OST significantly blocked phosphatidylinositol-3 kinase (PI3K)/AKT signaling pathway. Importantly, CDDP combined with LY294002, inhibitor of phosphoinositide 3-kinase (PI3K)/AKT serine/threonine kinase (AKT) signaling, markedly decreased the expression of NRF2, HO-1, NQO1 and GCLC in drug-resistant cervical cancer cells. The in vivo study also suggested that OST in combination obviously reduced tumor growth in comparison to the CDDP alone group. Taken together, these findings indicated that OST could be used as a potential sensitizer to reverse chemoresistance of cisplatin-resistant cervical cancer to cisplatin through repressing NRF2 expression partly associated with PI3K/AKT blockage.

Clinicopathological and prognostic significance of heme oxygenase-1 expression in small intestinal adenocarcinomas

Heme oxygenase-1 (HO-1), a stress-response protein, is highly induced in various carcinomas. It is implicated in carcinogenesis and tumor progression. High HO-1 expression is associated with better prognosis of patients with colorectal and gastric cancers. Induction or inhibition of HO-1 can mediate chemo-sensitivity, therefore it might be a therapeutic target to develop anticancer agents. To define the clinicopathological and prognostic significance of HO-1 expression in small-intestinal adenocarcinomas (SIACs), immunohistochemical microarray analysis of HO-1 expression was performed for 191 surgically resected SIAC cases and results were compared with various clinicopathologic variables, including survival. HO-1 was highly expressed in 127 (66.5%) cases. Patients with high HO-1 expression were associated with younger age (P = 0.048), lower pT category (P = 0.017), and less pancreatic invasion (P = 0.047). Patients with high HO-1 expression tended to have longer overall survival (median, 38.5 months) than those with low HO-1 expression (24.5 months), although the difference in overall survival was not statistically significant (P = 0.677). In summary, high HO-1 expression is frequently observed in SIACs. It is related to favorable clinicopathologic parameters, including younger age, lower T category, and less pancreatic invasion. Therefore, HO-1 may serve as a prognostic marker and a new target to modulate chemotherapeutic effects in patients with SIACs.

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.

A promising protein responsible for overactive bladder in ovariectomized mice

OBJECTIVE

Ovariectomy (OVX) in mice is a model mimicking a neuro-electronic proof of an overactive bladder in postmenopausal women. Overactive bladder (OAB) was recently found to be due to an altered gap junction protein in a rat model. Thus, this study was conducted to evaluate changes in cell junction protein expression and composition in the bladder of OVX mice.

MATERIALS AND METHODS

Thirty-six virgin female mice were randomized into three groups: mice with a sham operation only (control), OVX mice without estradiol (E2) replacement, and OVX mice with E2 replacement (OVX + E2). Cystometry assessment was conducted and cell junction-associated protein zonula occludens-2 (ZO-2) expression was measured after 8 weeks. Voiding interval values (time between voids) were assessed in mice under anesthesia. After measurements, the bladders were removed for proteomic analysis using the label-free quantitative proteomics and liquid chromatography-mass spectrometry technology. Lastly, immunohistochemistry (IHC) and Western blot were used to confirm the location and level, respectively, of ZO-2 expression.

RESULTS

We identified 73 differentially expressed proteins in the bladder of OVX mice. The OVX mice showed significantly lower voiding interval values. Voiding interval values were significantly higher in the OVX + E2 group than in the OVX group. Urothelial thicknesses in the bladder were also significantly lower in the OVX group than in the control group. E2 replacement reversed the urothelium layers. Additionally, the expression of ZO-2, a tight junction protein, was the most affected by OVX treatment. IHC and Western blot confirmed the downregulation of ZO-2 in the bladder of OVX mice. Expression of ZO-2 protein was significantly increased in OVX + E2 group compared with OVX group.

CONCLUSION

This exploratory study estimated changes in protein expression and composition in the bladder of OVX mice. These changes may be associated with the molecular mechanisms of OAB.

Characterization of RNA editome in primary and metastatic lung adenocarcinomas

RNA editing results in post-transcriptional modification and could potentially contribute to carcinogenesis. However, RNA editing in advanced lung adenocarcinomas has not yet been studied. Based on whole genome and transcriptome sequencing data, we identified 1,071,296 RNA editing events from matched normal, primary and metastatic samples contributed by 24 lung adenocarcinoma patients, with 91.3% A-to-G editing on average, and found significantly more RNA editing sites in tumors than in normal samples. To investigate cancer relevant editing events, we detected 67,851 hyper-editing sites in primary and 50,480 hyper-editing sites in metastatic samples. 46 genes with hyper-editing in coding regions were found to result in amino acid alterations, while hundreds of hyper-editing events in non-coding regions could modulate splicing or gene expression, including genes related to tumor stage or clinic prognosis. Comparing RNA editome of primary and metastatic samples, we also discovered hyper-edited genes that may promote metastasis development. These findings showed a landscape of RNA editing in matched normal, primary and metastatic tissues of lung adenocarcinomas for the first time and provided new insights to understand the molecular characterization of this disease.

Salidroside Reduces High-Glucose-Induced Podocyte Apoptosis and Oxidative Stress via Upregulating Heme Oxygenase-1 (HO-1) Expression

Background

Hyperglycemia is one of the most dangerous factors causing diabetic nephropathy. Salidroside is considered to have the effects of reducing oxidative stress damage and improving cell viability. This study was performed to investigate whether and how salidroside reduces high-glucose (HG)-induced apoptosis in mouse podocytes.

Material/Methods

We examined whether salidroside could decrease HG-induced podocyte oxidative stress and podocyte apoptosis in vitro. The potential signaling pathways were also investigated. Podocytes (immortalized mouse epithelial cells) were treated with normal glucose (5.5 mM) as control or HG (30 mM), and then exposed to salidroside treatment.

Results

HG enhanced the generation of intracellular reactive oxygen species (ROS) and apoptosis in podocytes. Salidroside reduced HG-induced apoptosis-related consequences via promoting HO-1 expression. Salidroside increased the expression level of phosphorylated Akt (p-Akt) and phosphorylated ILK (p-ILK), p-JNK, and p-ERK and localization of Nrf-2. JNK inhibitor and ILK inhibitor decreased HO-1 expression to different degrees. Moreover, specific siRNAs of ILK, Nrf-2, and HO-1, and inhibitors of HO-1 and ILK significantly increased ROS generation and Caspase9/3 expression in the presence of salidroside and HG.

Conclusions

The results suggest that salidroside reduces HG-induced ROS generation and apoptosis and improves podocytes viability by upregulating HO-1 expression. ILK/Akt, JNK, ERK1/2, p38 MAPK, and Nrf-2 are involved in salidroside-decreased podocyte apoptosis in HG condition.

High expression of HO-1 predicts poor prognosis of ovarian cancer patients and promotes proliferation and aggressiveness of ovarian cancer cells

PURPOSE

HO-1 has been proved to be associated with tumor aggressivity and poor prognosis in various cancers. Our study provides the first study to demonstrate the relationship of HO-1 expression and clinical characteristics in ovarian cancer patients.

METHODS

Immunohistochemistry and western blotting were used to examine the expression of HO-1 in tissue species and fresh tissues. CCK-8 was used to investigate cell viability. Transwell chamber was performed to estimate migration and invasion capacities in A2780 and Skov-3 cells.

RESULTS

Immunohistochemistry and western blotting showed that the expression of HO-1 was higher in ovarian cancer tissues than normal ovarian tissues. High expression of HO-1 was significantly associated with serous ovarian cancer, high FIGO stage, lymph node metastasis, and non-optimal debulking. Patients with high expression of HO-1 exhibited an unfavorable prognosis. In vitro inducing the expression of HO-1 promoted the proliferation and metastasis of A2780 and Skov-3 cells, with the increased expressions of mesenchymal marker (Vimentin), epithelial-mesenchymal transition-associated transcript factor (Zeb-1), anti-apoptotic protein (Bcl-2), and the decreased expressions of epithelial marker (Keratin) and pro-apoptotic protein (Bax). Meanwhile, after incubating A2780 and Skov-3 together with HO-1 inhibitor, above results could be reversed.

CONCLUSION

HO-1 might be a potential marker for prediction of ovarian cancer prognosis and a target for ovarian cancer treatment.

Individual and co-expression patterns of nerve growth factor and heme oxygenase-1 predict shorter survival of gastric carcinoma patients

BACKGROUND

Nerve growth factor (NGF) is a neurotrophic factor which regulates cell development and proliferation. Recently, it has been suggested that NGF induces heme oxygenase-1 (HO1) expression, and that both NGF and HO1 are involved in the progression of malignant human tumors. However, exact roles of NGF and HO1 in tumorigenesis remain controversial. Therefore, we investigated the expression and correlation of NGF and HO1 in human gastric carcinoma tissues.

METHODS

We examined immunohistochemical expression of NGF and HO1 in 167 gastric carcinomas and compared with various prognostic clinicopathological factors.

RESULTS

The expression of NGF and HO1 was positive in 40% (67/167) and 51% (85/167) of cases, respectively, and their expression was significantly correlated with each other (p < 0.001). Individual expression patterns of NGF and HO1, and co-expression pattern of these two molecules were significantly associated with shorter survival by univariate analysis. HO1 expression (overall survival; p < 0.001, relapse-free survival; p = 0.002) and co-expression pattern of NGF and HO1 (overall survival; p = 0.002, relapse-free survival; p = 0.003) were independent poor prognostic indicators of gastric carcinoma patients by multivariate analysis.

CONCLUSIONS

These results demonstrate that the individual and co-expression patterns of NGF and HO1 might be used as prognostic indicators for gastric carcinoma patients.

Red Yeast Rice Protects Circulating Bone Marrow-Derived Proangiogenic Cells against High-Glucose-Induced Senescence and Oxidative Stress: The Role of Heme Oxygenase-1

The inflammation and oxidative stress of bone marrow-derived proangiogenic cells (PACs), also named endothelial progenitor cells, triggered by hyperglycemia contributes significantly to vascular dysfunction. There is supporting evidence that the consumption of red yeast rice (RYR; Monascus purpureus-fermented rice) reduces the vascular complications of diabetes; however, the underlying mechanism remains unclear. This study aimed to elucidate the effects of RYR extract in PACs, focusing particularly on the role of a potent antioxidative enzyme, heme oxygenase-1 (HO-1). We found that treatment with RYR extract induced nuclear factor erythroid-2-related factor nuclear translocation and HO-1 mRNA and protein levels in PACs. RYR extract inhibited high-glucose-induced (30 mM) PAC senescence and the development of reactive oxygen species (ROS) in a dose-dependent manner. The HO-1 inducer cobalt protoporphyrin IX also decreased high-glucose-induced cell senescence and oxidative stress, whereas the HO-1 enzyme inhibitor zinc protoporphyrin IX and HO-1 small interfering RNA significantly reversed RYR extract-caused inhibition of senescence and reduction of oxidative stress in high-glucose-treated PACs. These results suggest that RYR extract serves as alternative and complementary medicine in the treatment of these diseases, by inducing HO-1, thereby decreasing the vascular complications of diabetes.

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.

Strange Bedfellows: Nuclear Factor, Erythroid 2-Like 2 (Nrf2) and Hypoxia-Inducible Factor 1 (HIF-1) in Tumor Hypoxia

The importance of the tumor microenvironment for cancer progression and therapeutic resistance is an emerging focus of cancer biology. Hypoxia, or low oxygen, is a hallmark of solid tumors that promotes metastasis and represents a significant obstacle to successful cancer therapy. In response to hypoxia, cancer cells activate a transcriptional program that allows them to survive and thrive in this harsh microenvironment. Hypoxia-inducible factor 1 (HIF-1) is considered the main effector of the cellular response to hypoxia, stimulating the transcription of genes involved in promoting angiogenesis and altering cellular metabolism. However, growing evidence suggests that the cellular response to hypoxia is much more complex, involving coordinated signaling through stress response pathways. One key signaling molecule that is activated in response to hypoxia is nuclear factor, erythroid 2 like-2 (Nrf2). Nrf2 is a transcription factor that controls the expression of antioxidant-response genes, allowing the cell to regulate reactive oxygen species. Nrf2 is also activated in various cancer types due to genetic and epigenetic alterations, and is associated with poor survival and resistance to therapy. Emerging evidence suggests that coordinated signaling through Nrf2 and HIF-1 is critical for tumor survival and progression. In this review, we discuss the distinct and overlapping roles of HIF-1 and Nrf2 in the cellular response to hypoxia, with a focus on how targeting Nrf2 could provide novel chemotherapeutic modalities for treating solid tumors.

MicroRNA-1304 suppresses human non-small cell lung cancer cell growth in vitro by targeting heme oxygenase-1

Previous studies have shown that microRNA-1304 (miR-1304) is dysregulated in certain types of cancers, including non-small cell lung cancer (NSCLC), and might be involved in tumor survival and/or growth. In this study we investigated the direct target of miR-1304 and its function in NSCLC in vitro. Human lung adenocarcinoma cell lines (A549 and NCI-H1975) were studied. The cell proliferation and survival were investigated via cell counting, MTT and colony-formation assays. Cell apoptosis and cell cycle were examined using annexin V-PE/7-AAD and PI staining assays, respectively. The dual-luciferase reporter assay was used to verify post-transcriptional regulation of heme oxygenase-1 (HO-1) by miR-1304. CRISPR/Cas9 was used to deplete endogenous miR-1304. Overexpression of MiR-1304 significantly decreased the number and viability of NSCLC cells and colony formation, and induced cell apoptosis and G₀/G₁ phase cell cycle arrest. HO-1 was demonstrated to be a direct target of miR-1304 in NSCLC cells. Restoration of HO-1 expression by hemin (20 μmol/L) abolished the inhibition of miR-1304 on cell growth and rescued miR-1304-induced apoptosis in A549 cells. Suppression of endogenous miR-1304 with anti-1304 significantly increased HO-1 expression and promoted cell growth and survival in A549 cells. In 17 human NSCLC tissue samples, miR-1304 expression was significantly decreased, while HO-1 expression was significantly increased as compared to normal lung tissues. MicroRNA-1304 is a tumor suppressor and HO-1 is its direct target in NSCLC. The results suggest the potential for miR-1304 as a therapeutic target for NSCLC.

Nrf2 and Notch Signaling in Lung Cancer: Near the Crossroad

The transcription factor Nrf2 (NF-E2 related factor 2) is a master regulator of the cell antioxidant response associated with tumor growth and resistance to cytotoxic treatments. In particular, Nrf2 induces upregulation of cytoprotective genes by interacting with the closely situated AREs (Antioxidant Response Elements) in response to endogenous or exogenous stress stimuli and takes part to several oncogenic signaling pathways. Among these, the crosstalk with Notch pathway has been shown to enhance cytoprotection and maintenance of cellular homeostasis, tissue organization by modulating cell proliferation kinetics, and stem cell self-renewal in several organs. The role of Notch and Nrf2 related pathways in tumorigenesis is highly variable and when they are both abnormally activated they can synergistically cause neoplastic proliferation by promoting cell survival, differentiation, invasion, and metastases. NFE2L2, KEAP1, and NOTCH genes family appear in the list of significantly mutated genes in tumors in both combined and individual sets, supporting the crucial role that the aberrant Nrf2-Notch crosstalk might have in cancerogenesis. In this review, we summarize current knowledge about the alterations of Nrf2 and Notch pathways and their reciprocal transcriptional regulation throughout tumorigenesis and progression of lung tumors, supporting the potentiality of putative biomarkers and therapeutic targets.

Identification of cyclins A1, E1 and vimentin as downstream targets of heme oxygenase-1 in vascular endothelial growth factor-mediated angiogenesis

Angiogenesis is an essential physiological process and an important factor in disease pathogenesis. However, its exploitation as a clinical target has achieved limited success and novel molecular targets are required. Although heme oxygenase-1 (HO-1) acts downstream of vascular endothelial growth factor (VEGF) to modulate angiogenesis, knowledge of the mechanisms involved remains limited. We set out identify novel HO-1 targets involved in angiogenesis. HO-1 depletion attenuated VEGF-induced human endothelial cell (EC) proliferation and tube formation. The latter response suggested a role for HO-1 in EC migration, and indeed HO-1 siRNA negatively affected directional migration of EC towards VEGF; a phenotype reversed by HO-1 over-expression. EC from Hmox1(-/-) mice behaved similarly. Microarray analysis of HO-1-depleted and control EC exposed to VEGF identified cyclins A1 and E1 as HO-1 targets. Migrating HO-1-deficient EC showed increased p27, reduced cyclin A1 and attenuated cyclin-dependent kinase 2 activity. In vivo, cyclin A1 siRNA inhibited VEGF-driven angiogenesis, a response reversed by Ad-HO-1. Proteomics identified structural protein vimentin as an additional VEGF-HO-1 target. HO-1 depletion inhibited VEGF-induced calpain activity and vimentin cleavage, while vimentin silencing attenuated HO-1-driven proliferation. Thus, vimentin and cyclins A1 and E1 represent VEGF-activated HO-1-dependent targets important for VEGF-driven angiogenesis.

Redox Homeostasis and Cellular Antioxidant Systems: Crucial Players in Cancer Growth and Therapy

Reactive oxygen species (ROS) and their products are components of cell signaling pathways and play important roles in cellular physiology and pathophysiology. Under physiological conditions, cells control ROS levels by the use of scavenging systems such as superoxide dismutases, peroxiredoxins, and glutathione that balance ROS generation and elimination. Under oxidative stress conditions, excessive ROS can damage cellular proteins, lipids, and DNA, leading to cell damage that may contribute to carcinogenesis. Several studies have shown that cancer cells display an adaptive response to oxidative stress by increasing expression of antioxidant enzymes and molecules. As a double-edged sword, ROS influence signaling pathways determining beneficial or detrimental outcomes in cancer therapy. In this review, we address the role of redox homeostasis in cancer growth and therapy and examine the current literature regarding the redox regulatory systems that become upregulated in cancer and their role in promoting tumor progression and resistance to chemotherapy.