Evaluation of the Expression of Amine Oxidase Proteins in Breast Cancer

The tumour-derived extracellular vesicle proteome varies by endometrial cancer histology and is confounded by an obesogenic environment

Endometrial cancer, the most common gynaecological cancer worldwide, is closely linked to obesity and metabolic diseases, particularly in younger women. New circulating biomarkers have the potential to improve diagnosis and treatment selections, which could significantly improve outcomes. Our approach focuses on extracellular vesicle (EV) biomarker discovery by directly profiling the proteome of EVs enriched from frozen biobanked endometrial tumours. We analysed nine tissue samples to compare three clinical subgroups-low BMI (Body Mass Index) Endometrioid, high BMI Endometrioid, and Serous (any BMI)-identifying proteins related to histological subtype, BMI, and shared secreted proteins. Using collagenase digestion and size exclusion chromatography, we successfully enriched generous quantities of EVs (range 204.8-1291.0 µg protein: 1.38 × 1011-1.10 × 1012 particles), characterised by their size (∼150 nm), expression of EV markers (CD63/81), and proposed endometrial cancer markers (L1CAM, ANXA2). Mass spectrometry-based proteomic profiling identified 2075 proteins present in at least one of the 18 samples. Compared to cell lysates, EVs were successfully depleted for mitochondrial and blood proteins and enriched for common EV markers and large secreted proteins. Further analysis highlighted significant differences in EV protein profiles between the high BMI subgroup and others, underlining the impact of comorbidities on the EV secretome. Interestingly, proteins differentially abundant in tissue subgroups were largely not also differential in matched EVs. This research identified secreted proteins known to be involved in endometrial cancer pathophysiology and proposed novel diagnostic biomarkers (EIF6, MUC16, PROM1, SLC26A2).

A second life for MAO inhibitors? From CNS diseases to anticancer therapy

Monoamine oxidases A and B (MAO A, B) are ubiquitous enzymes responsible for oxidative deamination of amine neurotransmitters and xenobiotics. Despite decades of studies, MAO inhibitors (MAOIs) find today limited therapeutic space as second-line drugs for the treatment of depression and Parkinson's disease. In recent years, a renewed interest in MAOIs has been raised up by several studies investigating the role of MAOs, particularly MAO A, in tumor insurgence and progression, and the efficacy of MAOIs as coadjutants in the therapy of chemoresistant tumors. In this survey, we highlight the implication of MAOs in the biochemical pathways of tumorigenesis and review the state-of-the-art of preclinical and clinical studies of MAOIs as anticancer agents used in monotherapy or in combination with antitumor chemotherapeutics.

Molecular Investigation of the Antitumor Effects of Monoamine Oxidase Inhibitors in Breast Cancer Cells

The catalytic activity of monoamine oxidase A (MAO-A) has been linked to tumorigenesis due to the production of reactive oxygen species (ROS) and the resulting oxidative stress. MAO-A inhibition revealed a beneficial role in prostate and lung cancer treatment. This study is aimed at evaluating the effect of different monoamine oxidase A inhibitors (MAO-AIs) on the proliferation and progression of breast cancer cell lines. The cell viability assay was used to evaluate the antiproliferative and combined effects of MAO-AIs. Cell migration was evaluated using wound healing, invasion, and colony formation assays. The underlying mechanism of cell death was studied using flow cytometry. The real-time polymerase chain reaction was used to determine the relative gene expression. Finally, MAO-A activity in breast cancer cells was evaluated using an MAO-A activity assay. According to the results, the examined MAO-AIs significantly inhibited the proliferation of breast cancer cells in a dose-dependent manner. In breast cancer cells, the combination of anticancer drugs (doxorubicin or raloxifene) with MAO-AIs resulted in a synergistic effect. MAO-AIs significantly reduced wound closure and invasion ability in breast cancer cells. Also, MAO-AIs reduced the colony count and size of breast cancer cells. MAO-AIs resulted in significant proapoptotic activity in breast cancer cells. Finally, the MAO-AIs suppressed MAO-A, Bcl-2, and VEGF gene expressions in breast cancer cells relative to untreated cells. This study provides solid evidence supporting the anticancer effect of MAO-A inhibitors in breast cancer cells.

Synthesis and anti-cancer potential of potent peripheral MAOA inhibitors designed to limit blood:brain penetration

Monoamine oxidases (MAOA/MAOB) are enzymes known for their role in neurotransmitter regulation in the central nervous system (CNS). Irreversible and non-selective MAO inhibitors (MAOi's) were the first class of antidepressants, thus subsequent work on drugs such as the selective MAOA inhibitor clorgyline has focussed on selectivity and increased CNS penetration. MAOA is highly expressed in high grade and metastatic prostate cancer with a proposed effect on prostate cancer growth, recurrence, and drug resistance. A Phase II Clinical Trial has demonstrated the therapeutic effects of the irreversible nonselective MAOi phenelzine for prostate cancer. However, neurologic adverse effects led to early withdrawal in 25% of the enrolled patient-population. In this work, we revised the clorgyline scaffold with the goal of decreasing CNS penetration to minimize CNS-related side effects while retaining or enhancing MAOA inhibition potency and selectivity. Using the known co-crystal structure of clorgyline bound with FAD co-factor in the hMAOA active site as a reference, we designed and synthesized a series of compounds predicted to have lower CNS penetration (logBB). All synthesized derivatives displayed favorable drug-like characteristics such as predicted Caco-2 permeability and human oral absorption, and exhibited highly selective hMAOA binding interactions. Introduction of an HBD group (NH2 or OH) at position 5 of the phenyl ring clorgyline resulted in 3x more potent hMAOA inhibition with equivalent or better hMAOB selectivity, and similar prostate cancer cell cytotoxicity. In contrast, introduction of larger substituents at this position or at the terminal amine significantly reduced the hMAOA inhibition potency, attributed in part to a steric clash within the binding pocket of the MAOA active site. Replacement of the N-methyl group by a more polar, but larger 2-hydroxyethyl group did not enhance potency. However, introduction of a polar 2-hydroxy in the propyl chain retained the highly selective MAOA inhibition and cancer cell cytotoxicity of clorgyline while reducing its CNS score from 2 to 0. We believe that these results identify a new class of peripherally directed MAOIs that may allow safer therapeutic targeting of MAOA for a variety of anti-cancer and anti-inflammatory indications.

Identification of AOC3 and LRRC17 as Colonic Fibroblast Activation Markers and Their Potential Roles in Colorectal Cancer Progression

BACKGROUND

Accumulation of cancer-associated fibroblasts (CAFs) in the tumor stroma is linked to poor prognosis in colorectal cancer (CRC). CAF-cancer cell interplay, facilitated by secretomes including transforming growth factor-beta 1 (TGF-β1), supports fibroblast activation, drives colorectal carcinogenesis, and contributes to CRC aggressive phenotypes. Although widely used, traditional CAF biomarkers are found to have heterogeneous and non-specific expression. Amine oxidase copper containing 3 (AOC3) and leucine-rich repeat-containing 17 (LRRC17) have been reported to be emerging markers of myofibroblasts.

AIM

Our objective was to investigate the potential of AOC3 and LRRC17 as biomarkers for fibroblast activation thus predicting their roles in CRC progression.

METHODS

Immunofluorescence (IF) staining of AOC3 and LRRC17 was performed on myofibroblast line (CCD-112CoN), primary fibroblasts from colorectal tumor (CAFs), and adjacent normal tissue (normal fibroblasts-NFs). SW620 (epithelial CRC cell line) was used as a control.  Conventional CAF biomarker (alpha-smooth muscle actin - α-SMA) was included in the IF analysis. Fluorescence intensity was compared between groups using ImageJ software. Proliferation and contractility of treated cells were assessed using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) and collagen gel contraction assays, respectively. Fibroblast contraction under TGF-β1 treatment was compared to those treated with complete medium (addition of 10% serum) and serum free (SF) medium.

RESULTS

Positive AOC3, LRRC17, and α-SMA expression were observed in colonic fibroblasts, more prominent in CAFs, whereas negative staining was found in SW620. Significant downregulation of AOC3, and upregulations in LRRC17 and α-SMA expression was found in TGF-β1-treated fibroblasts compared to SF medium treatment (p-value<0.05). All fibroblasts exhibited higher proliferation in complete medium and under treatment with conditioned medium from SW620 than SF medium. Significant contraction of NFs was recorded in complete medium and TGF-β1 (p-value<0.01).

CONCLUSION

Our results demonstrate AOC3 and LRRC17 as the potential markers of CAF activation which promote CRC progression.

Expression of Amine Oxidase Proteins in Adrenal Cortical Neoplasm and Pheochromocytoma

We delved into the expression of amine oxidase family proteins and their potential significance in adrenal gland neoplasm. Tissue microarrays were prepared for 132 cases of adrenal cortical neoplasm (ACN) consisting of 115 cases of adrenal cortical adenoma (ACA), 17 cases of adrenal cortical carcinoma (ACC), and 163 cases of pheochromocytoma (PCC). Immunohistochemical stainings for MAOA, MAOB, LOX, and AOC3 were performed to evaluate the H-scores and compare them with clinicopathological parameters. The H-scores of MAOA (T; p = 0.005) and MAOB (T; p = 0.006) in tumor cells (T) were high in ACN, whereas LOX (T, S; p < 0.001) in tumor and stromal cells (S) and AOC3 (T; p < 0.001) were higher in PCC. In stromal cells, MAOA (S; p < 0.001) and AOC3 (S; p = 0.010) were more expressed in ACA than in ACC. MAOB (S) in PCC showed higher H-scores when the grading of adrenal pheochromocytoma and paraganglioma (GAPP) score was 3 or higher (p = 0.027). In the univariate analysis, low MAOA expression in stromal cells of ACN was associated with shorter overall survival (p = 0.008). In conclusion, monoamine oxidase proteins revealed differences in expression between ACN and PCC and also between benign and malignant cells.

A Prognostic Model Based on Metabolism-Related Genes for Patients with Ovarian Cancer

Metabolism-associated genes (MAGs) are important regulators of tumor progression and can affect a variety of physiological processes. In this study, we focused on the relationship between MAGs and Ovarian cancer (OC) prognosis.

METHOD

Metabolism-related genes were extracted from the Cancer Genome Atlas (TCGA) database. Through univariate COX and lasso regression models, a dynamic risk model based on MAGs was established. Compared with other clinical factors, demonstrated the ability of the model to predict the prognosis of patients with OC. The clinical samples were used to verify the expression of these MAGs.

RESULTS

A metabolism-associated gene signature was constructed by LASSO Cox regression analysis in OC, which was composed of 3-MAGs (PTGIS, AOC3, and IDO1). The signature was used to classify the OC patients into high-risk and low-risk groups. The overall survival of the low-risk group was significantly better than that of the high-risk group. The analysis of the therapeutic effect of bevacizumab showed that bevacizumab was not conducive to improving the prognosis of the low-risk group.

CONCLUSIONS

We constructed a prognostic model of MAGs in OC, which can be used to predict the prognosis of OC patients and may have a good guiding significance in the individualized treatment of patients.

m6A-enriched lncRNA LINC00839 promotes tumor progression by enhancing TAF15-mediated transcription of amine oxidase AOC1 in nasopharyngeal carcinoma

Dysregulation of long non-coding RNAs (lncRNAs) contributes to tumorigenesis by modulating specific cancer-related pathways, but the roles of m6A-enriched lncRNAs and underlying mechanisms remain elusive in nasopharyngeal carcinoma (NPC). Here, we reanalyzed the previous genome-wide analysis of lncRNA profiles in 18 pairs of NPC and normal tissues, as well as in 10 paired samples from NPC with or without posttreatment metastases. We discerned that an oncogenic m6A-enriched lncRNA, LINC00839, which was substantially upregulated in NPC and correlated with poor clinical prognosis, promoted NPC growth and metastasis both in vitro and in vivo. Mechanistically, by using RNA pulldown assay combined with mass spectrometry, we found that LINC00839 interacted directly with the transcription factor, TATA-box binding protein associated factor (TAF15). Besides, ChIP and dual-luciferase report assays demonstrated that LINC00839 coordinated the recruitment of TAF15 to the promoter region of amine oxidase copper-containing 1 (AOC1), which encodes a secreted glycoprotein playing vital roles in various cancers, thereby activating AOC1 transcription in trans. In this study, potential effects of AOC1 in NPC progression were first proposed. Moreover, ectopic expression of AOC1 partially rescued the inhibitory effect of downregulation of LINC00839 in NPC. Furthermore, we showed that silencing vir-like m6A methyltransferase-associated (VIRMA) and insulin-like growth factor 2 mRNA-binding proteins 1 (IGF2BP1) attenuated the expression level and RNA stability of LINC00839 in an m6A-dependent manner. Taken together, our study unveils a novel oncogenic VIRMA/IGF2BP1-LINC00839-TAF15-AOC1 axis, and highlights the significance and prognostic value of LINC00839 expression in NPC carcinogenesis.

Monoamine oxidase A (MAOA): A promising target for prostate cancer therapy

Monoamine oxidase A (MAOA) is a mitochondrial enzyme that catalyzes the oxidative deamination of monoamine neurotransmitters and dietary amines. Previous studies have shown that MAOA is clinically associated with prostate cancer (PCa) progression and plays a key role in almost each stage of PCa, including castrate-resistant prostate cancer, neuroendocrine prostate cancer, metastasis, drug resistance, stemness, and perineural invasion. Moreover, MAOA expression is upregulated not only in cancer cells but also in stromal cells, intratumoral T cells, and tumor-associated macrophages; thus, targeting MAOA can be a multi-pronged approach to disrupt tumor promoting interactions between PCa cells and tumor microenvironment. Furthermore, targeting MAOA can disrupt the crosstalk between MAOA and the androgen receptor (AR) to restore enzalutamide sensitivity, blocks glucocorticoid receptor (GR)- and AR-dependent PCa cell growth, and is a potential strategy for immune checkpoint inhibition, thereby alleviating immune suppression and enhancing T cell immunity-based cancer immunotherapy. MAOA is a promising target for PCa therapy, which deserves further exploration in preclinical and clinical settings.

Monoamine oxidase A: An emerging therapeutic target in prostate cancer

Monoamine oxidase A (MAOA), a mitochondrial enzyme degrading biogenic and dietary amines, has been studied in the contexts of neuropsychiatry and neurological disorders for decades, but its importance in oncology, as best exemplified in prostate cancer (PC) to date, was only realized recently. PC is the most commonly diagnosed non-skin cancer and the second deadliest malignancy for men in the United States. In PC, the increased expression level of MAOA is correlated with dedifferentiated tissue microarchitecture and a worse prognosis. A wealth of literature has demonstrated that MAOA promotes growth, metastasis, stemness and therapy resistance in PC, mainly by increasing oxidative stress, augmenting hypoxia, inducing epithelial-to-mesenchymal transition, and activating the downstream principal transcription factor Twist1-dictated multiple context-dependent signaling cascades. Cancer-cell-derived MAOA also enables cancer-stromal cell interaction involving bone stromal cells and nerve cells by secretion of Hedgehog and class 3 semaphorin molecules respectively to modulate the tumor microenvironment in favor of invasion and metastasis. Further, MAOA in prostate stromal cells promotes PC tumorigenesis and stemness. Current studies suggest that MAOA functions in PC in both cell autonomous and non-autonomous manners. Importantly, clinically available monoamine oxidase inhibitors have shown promising results against PC in preclinical models and clinical trials, providing a great opportunity to repurpose them as a PC therapy. Here, we summarize recent advances in our understanding of MAOA roles and mechanisms in PC, present several MAOA-targeted strategies that have been nominated for treating PC, and discuss the unknowns of MAOA function and targeting in PC for future exploration.

Downregulation of amine oxidase copper containing 1 inhibits tumor progression by suppressing IL-6/JAK/STAT3 pathway activation in hepatocellular carcinoma

Amine oxidase copper containing 1 (AOC1) is a copper-containing amine oxidase that catalyzes the deamination of polyamines. AOC1 functions as an oncogene in human gastric cancer. There is little information available regarding the function of AOC1 in hepatocellular carcinoma (HCC). In the present study, reverse transcription-quantitative PCR was used to detect the expression levels of AOC1 in HCC tissues, and the role of AOC1 in HCC progression was determined using western blot, Cell Counting Kit 8, clone formation, wound-healing and Transwell assays. An AOC1 survival curve was generated with data downloaded from The Cancer Genome Atlas, and Gene Set Enrichment Analysis was performed to investigate the potential biological mechanisms of AOC1 in HCC. AOC1 was found to be upregulated in HCC tissues, which was associated with a poor prognosis. Furthermore, AOC1-knockdown inhibited HCC cell proliferation, migration and invasiveness, suppressed IL-6 expression, as well as decreasing JAK2 and STAT3 phosphorylation. Ultimately, the results of the present study illustrate that AOC1 promoted the proliferation, migration and invasiveness of HCC cells by regulating the IL-6/JAK/STAT3 pathway.

Monoamine Oxidase (MAO) as a Potential Target for Anticancer Drug Design and Development

Monoamine oxidases (MAOs) are oxidative enzymes that catalyze the conversion of biogenic amines into their corresponding aldehydes and ketones through oxidative deamination. Owing to the crucial role of MAOs in maintaining functional levels of neurotransmitters, the implications of its distorted activity have been associated with numerous neurological diseases. Recently, an unanticipated role of MAOs in tumor progression and metastasis has been reported. The chemical inhibition of MAOs might be a valuable therapeutic approach for cancer treatment. In this review, we reported computational approaches exploited in the design and development of selective MAO inhibitors accompanied by their biological activities. Additionally, we generated a pharmacophore model for MAO-A active inhibitors to identify the structural motifs to invoke an activity.

Amine oxidase, copper containing 3 exerts anti‑mesenchymal transformation and enhances CD4+ T‑cell recruitment to prolong survival in lung cancer

Lung cancer remains notorious for its poor prognosis. Despite the advent of tyrosine kinase inhibitors and immune checkpoint inhibitors, the probability of curing the disease in lung cancer patients remains low. Novel mechanisms and treatment strategies are needed to provide hope to patients. Advanced strategies of next generation sequencing (NGS) and bioinformatics were used to analyze normal and lung cancer tissues from lung cancer patients. Amine oxidases have been linked to leukocyte migration and tumorigenesis. However, the roles of amine oxidases in lung cancer are not well-understood. Our results indicated that amine oxidase, copper containing 3 (AOC3) was significantly decreased in the tumor tissue compared with the normal tissue, at both the mRNA and protein level, in the included lung cancer patients and public databases. Lower expression of AOC3 conferred a poorer survival probability across the different cohorts. Epigenetic silencing of AOC3 via miR-3691-5p caused tumor promotion and progression by increasing migration and epithelial-mesenchymal transition (EMT). Furthermore, knockdown of AOC3 caused less CD4⁺ T-cell attachment onto lung cancer cells and reduced transendothelial migration in vitro, as well as reducing CD4⁺ T-cell trafficking to the lung in vivo. In conclusion, the present study revealed that downregulation of AOC3 mediated lung cancer promotion and progression, as well as decrease of immune cell recruitment. This novel finding could expand our understanding of the dysregulation of the tumor immune microenvironment and could help to develop a novel strategy for the treatment of lung cancer.

Effects of neoadjuvant therapies on genetic regulation of targeted pathways in ER+ primary ductal breast carcinoma: A meta-analysis of microarray datasets

Breast cancer arises as a result of multiple interactions between environmental and genetic factors. Conventionally, breast cancer is treated based on histopathological and clinical features. DNA technologies like the human genome microarray are now partially integrated into clinical practice and are used for developing new "personalized medicines" and "pharmacogenetics" for improving the efficiency and safety of cancer medications. We investigated the effects of four established therapies-for ER+ ductal breast cancer-on the differential gene expression. The therapies included single agent tamoxifen, two-agent docetaxel and capecitabine, or combined three-agents CAF (cyclophosphamide, doxorubicin, and fluorouracil) and CMF (cyclophosphamide, methotrexate, and fluorouracil). Genevestigator 8.1.0 was used to compare five datasets from patients with infiltrating ductal carcinoma, untreated or treated with selected drugs, to those from the healthy control. We identified 74 differentially expressed genes involved in three pathways, i.e., apoptosis (extrinsic and intrinsic), oxidative signaling, and PI3K/Akt signaling. The treatments affected the expression of apoptotic genes (TNFRSF10B [TRAIL], FAS, CASP3/6/7/8, PMAIP1 [NOXA], BNIP3L, BNIP3, BCL2A1, and BCL2), the oxidative stress-related genes (NOX4, XDH, MAOA, GSR, GPX3, and SOD3), and the PI3K/Akt pathway gene (ERBB2 [HER2]). Breast cancer treatments are complex with varying drug responses and efficacy among patients. This necessitates identifying novel biomarkers for predicting the drug response, using available data and new technologies. GSR, NOX4, CASP3, and ERBB2 are potential biomarkers for predicting the treatment response in primary ER+ ductal breast carcinoma.

Targeting monoamine oxidase A-regulated tumor-associated macrophage polarization for cancer immunotherapy

Targeting tumor-associated macrophages (TAMs) is a promising strategy to modify the immunosuppressive tumor microenvironment and improve cancer immunotherapy. Monoamine oxidase A (MAO-A) is an enzyme best known for its function in the brain; small molecule MAO inhibitors (MAOIs) are clinically used for treating neurological disorders. Here we observe MAO-A induction in mouse and human TAMs. MAO-A-deficient mice exhibit decreased TAM immunosuppressive functions corresponding with enhanced antitumor immunity. MAOI treatment induces TAM reprogramming and suppresses tumor growth in preclinical mouse syngeneic and human xenograft tumor models. Combining MAOI and anti-PD-1 treatments results in synergistic tumor suppression. Clinical data correlation studies associate high intratumoral MAOA expression with poor patient survival in a broad range of cancers. We further demonstrate that MAO-A promotes TAM immunosuppressive polarization via upregulating oxidative stress. Together, these data identify MAO-A as a critical regulator of TAMs and support repurposing MAOIs for TAM reprogramming to improve cancer immunotherapy.

Polyamine biomarkers as indicators of human disease

The significant increase of periodontitis, chronic kidney disease (CKD), Alzheimer's disease and cancer can be attributed to an ageing population. Each disease produces a range of biomarkers that can be indicative of disease onset and progression. Biomarkers are defined as cellular (intra/extracellular components and whole cells), biochemical (metabolites, ions and toxins) or molecular (nucleic acids, proteins and lipids) alterations which are measurable in biological media such as human tissues, cells or fluids. An interesting group of biomarkers that merit further investigation are the polyamines. Polyamines are a group of molecules consisting of cadaverine, putrescine, spermine and spermidine and have been implicated in the development of a range of systemic diseases, in part due to their production in periodontitis. Cadaverine and putrescine within the periodontal environment have demonstrated cell signalling interfering abilities, by way of leukocyte migration disruption. The polyamines spermine and spermidine in tumour cells have been shown to inhibit cellular apoptosis, effectively prolonging tumorigenesis and continuation of cancer within the host. Polyamine degradation products such as acrolein have been shown to exacerbate renal damage in CKD patients. Thus, the use of such molecules has merit to be utilized in the early indication of such diseases in patients.

Identification of breast cancer prognostic modules via differential module selection based on weighted gene Co-expression network analysis

Breast cancer is a complex cancer which includes many different subtypes. Identifying prognostic modules, i.e., functionally related gene networks that play crucial roles in cancer development is essential in breast cancer study. Different subtypes of breast cancer correspond to different treatment methods. The purpose of this study is to use a new method to divide breast cancer into different prognostic modules, so as to provide scientific basis for improving clinical management. The method is based on comparing similarities between modules detected from different weighted gene co-expression networks. The method was applied on genomic data of breast cancer from The Cancer Genome Atlas database and was applied to select differential modules between two groups of patients with significant differences in survival times. It was compared with a previously proposed module selection method. The result shows that our method outperforms the previously proposed one. Moreover, within the identified two differential modules, the first one is highly enriched with genes involved in hormone responds, the second one is highly related with biological process engaged in M-phase. The two modules were further validated by log-rank test in the validation dataset GSE3494. Both of the two modules show significantly different with p-values less than 0.02. The identified two modules confirmed previous findings including importance of biological networks in breast cancer involved in hormone response and M-phase. Out of the top twenty hub genes in the two modules, fifteen genes were previously shown to be prognostic markers for breast cancer.

Coexpression Module Construction by Weighted Gene Coexpression Network Analysis and Identify Potential Prognostic Markers of Breast Cancer

Background: Breast cancer (BC) is a malignant tumor with the highest morbidity among women, disrupting millions of their lives worldwide each year. However, the molecular mechanisms underlying remain unclear. Methods: The RNA-Sequencing and clinical data of BC patients from The Cancer Genome Atlas (TCGA) database were analyzed by weighted gene coexpression network analysis (WGCNA). Additionally, coexpressed modules were used to detect their correlation with the clinical traits of BC. Next, nodes of the most significant coexpression modules were used for Gene Ontology (GO), Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway, mRNA-lncRNA coexpression network and survival analyses. Results: In total, 2056 differentially expressed mRNAs (DEmRNAs) and 297 differentially expressed lncRNAs (DElncRNAs) were identified and subjected to WGCNA analysis, and 12 coexpression modules were generated. The top five significant modules (turquoise, green, red, brown, and blue modules) were related to one or more clinical traits of BC. In particular, the turquoise and green modules were chosen for further analysis. Next, by lncRNA-mRNA coexpression analysis of the turquoise and green modules, 12 DEmRNAs and 2 DElncRNAs were identified as hub nodes. The lncRNA-associated mRNAs of the networks were commonly related to several cancer-related pathways. Moreover, these networks also revealed central roles for RP11-389C8.2 and TGFBR2 in the turquoise module and MYLK, KIT, and RP11-394O4.5 in the green module. Furthermore, 16 DEmRNAs and 3 DElncRNAs in these two modules were significantly correlated with the overall survival of BC patients. Conclusions: The authors' study identified some prognostic biomarkers that might play important roles in the development and treatment of BC. In particular, lncRNAs AC016995.3, RP1-193H18.2, and RP11-166D19.1 were novel biomarkers for BC.

The clinical value and potential molecular mechanism of the downregulation of MAOA in hepatocellular carcinoma tissues

Background

Hepatocellular carcinoma (HCC) remains one of the most common cancers worldwide and tends to be detected at an advanced stage. More effective biomarkers for HCC screening and prognosis assessment are needed and the mechanisms of HCC require further exploration. The role of MAOA in HCC has not been intensively investigated.

Methods

In‐house tissue microarrays, genechips, and RNAsequencing datasets were integrated to explore the expression status and the clinical value of MAOA in HCC. Immunohistochemical staining was utilized to determine MAOA protein expression. Intersection genes of MAOA related co‐expressed genes and differentially expressed genes were obtained to perform functional enrichment analyses. In vivo experiment was conducted to study the impact of traditional Chinese medicine nitidine chloride (NC) on MAOA in HCC.

Results

MAOA was downregulated and possessed an excellent discriminatory capability in HCC patients. Decreased MAOA correlated with poor prognosis in HCC patients. Downregulated MAOA protein was relevant to an advanced TNM stage in HCC patients. Co‐expressed genes that positively related to MAOA were clustered in chemical carcinogenesis, where CYP2E1 was identified as the hub gene. In vivo experiment showed that nitidine chloride significantly upregulated MAOA in a nude mouse HCC model.

Conclusions

A decreased MAOA level is not only correlated with aggressive behaviors in males but also serves as a promising biomarker for the diagnosis and prognosis of HCC patients. Moreover, MAOA may play a role in AFB1 toxic transformation through its synergistic action with co‐expressed genes, especially CYP3A4. MAOA also serves as a potential therapy target of NC in HCC patients.

Identification of a nine-gene prognostic signature for gastric carcinoma using integrated bioinformatics analyses

BACKGROUND

Gastric carcinoma (GC) is one of the most aggressive primary digestive cancers. It has unsatisfactory therapeutic outcomes and is difficult to diagnose early.

AIM

To identify prognostic biomarkers for GC patients using comprehensive bioinformatics analyses.

METHODS

Differentially expressed genes (DEGs) were screened using gene expression data from The Cancer Genome Atlas and Gene Expression Omnibus databases for GC. Overlapping DEGs were analyzed using univariate and multivariate Cox regression analyses. A risk score model was then constructed and its prognostic value was validated utilizing an independent Gene Expression Omnibus dataset (GSE15459). Multiple databases were used to analyze each gene in the risk score model. High-risk score-associated pathways and therapeutic small molecule drugs were analyzed and predicted, respectively.

RESULTS

A total of 95 overlapping DEGs were found and a nine-gene signature (COL8A1, CTHRC1, COL5A2, AADAC, MAMDC2, SERPINE1, MAOA, COL1A2, and FNDC1) was constructed for the GC prognosis prediction. Receiver operating characteristic curve performance in the training dataset (The Cancer Genome Atlas-stomach adenocarcinoma) and validation dataset (GSE15459) demonstrated a robust prognostic value of the risk score model. Multiple database analyses for each gene provided evidence to further understand the nine-gene signature. Gene set enrichment analysis showed that the high-risk group was enriched in multiple cancer-related pathways. Moreover, several new small molecule drugs for potential treatment of GC were identified.

CONCLUSION

The nine-gene signature-derived risk score allows to predict GC prognosis and might prove useful for guiding therapeutic strategies for GC patients.

AOC1 Contributes to Tumor Progression by Promoting the AKT and EMT Pathways in Gastric Cancer

Background

AOC1 is a copper-containing amine oxidase that is responsible for catalyzing the deamination of polyamines, which produces reactive oxygen species. Previous studies have demonstrated that polyamines are involved in the regulation of proliferation, migration, and apoptosis of cells. However, very little is known about the functions and regulatory mechanisms of AOC1 in tumors.

Methods

Based on GEPIA data, we found that AOC1 was significantly upregulated in human gastric cancer tissues. We knocked down AOC1 in human AGS and MKN45 cells using siRNA transfection, then utilized qRT-PCR assay and Western blot to verify the effectiveness of AOC1 knockdown in gastric cancer cells.

Results

Function analysis demonstrated that knockdown of AOC1 inhibited the proliferation, invasion, and migration of human gastric cancer cells. Flow cytometry detection suggested that AOC1 knockdown induced apoptosis in human gastric cancer cells. Mechanism investigation suggested that AOC1 knockdown increased the ratio of Bax/Bcl2 and induced activation of the caspase cascade. Furthermore, the AKT signaling pathway was inactivated when AOC1 was silenced, including downregulated phosphorylation level of AKT and expression of downstream effectors, Cyclin D1, and p70S6K. Finally, we found that knockdown of AOC1 inhibited the epithelial–mesenchymal transition (EMT) in human gastric cancer by increasing the expression of epithelial markers E-cadherin, as well as decreasing mesenchymal marker N-cadherin, SNAIL and Slug.

Conclusion

Our study suggests that AOC1 functions as an oncogene in human gastric cancer by activating the AKT signaling pathway and EMT process and maybe a target of 6-mercaptopurine, which provides new insight in the clinical use of AOC1 in gastric cancer therapy.

Monoamine oxidase-A activity is required for clonal tumorsphere formation by human breast tumor cells

Background

Breast tumor growth and recurrence are driven by an infrequent population of breast tumor-initiating cells (BTIC). We and others have reported that the frequency of BTIC is orders of magnitude higher when breast tumor cells are propagated in vitro as clonal spheres, termed tumorspheres, by comparison to adherent cells. We exploited the latter to screen > 35,000 small molecules to identify agents capable of targeting BTIC. We unexpectedly discovered that selective antagonists of serotonin signaling were among the hit compounds. To better understand the relationship between serotonin and BTIC we expanded our analysis to include monoamine oxidase-A (MAO-A), an enzyme that metabolizes serotonin.

Methods

We used the Nanostring technology and Western blotting to determine whether MAO-A is expressed in human breast tumor cell lines cultured as tumorspheres by comparison to those grown as adherent cells. We then determined whether MAO-A activity is required for tumorsphere formation, a surrogate in vitro assay for BTIC, by assessing whether selective MAO-A inhibitors affect the frequency of tumorsphere-forming cells. To learn whether MAO-A expression in breast tumor cells is associated with other reported properties of BTIC such as anticancer drug resistance or breast tumor recurrence, we performed differential gene expression analyses using publicly available transcriptomic datasets.

Results

Tumorspheres derived from human breast tumor cell lines representative of every breast cancer clinical subtype displayed increased expression of MAO-A transcripts and protein by comparison to adherent cells. Surprisingly, inhibition of MAO-A activity with selective inhibitors reduced the frequency of tumorsphere-forming cells. We also found that increased MAO-A expression is a common feature of human breast tumor cell lines that have acquired anticancer drug resistance and is associated with poor recurrence-free survival (RFS) in patients that experienced high-grade, ER-negative (ER⁻) breast tumors.

Conclusions

Our data suggests that MAO-A activity is required for tumorsphere formation and that its expression in breast tumor cells is associated with BTIC-related properties. The discovery that a selective MAO-A inhibitor targets tumorsphere-forming cells with potencies in the nanomolar range provides the first evidence of this agent’s anticancer property. These data warrant further investigation of the link between MAO-A and BTIC.

ROS Generation and Antioxidant Defense Systems in Normal and Malignant Cells

Reactive oxygen species (ROS) are by-products of normal cell activity. They are produced in many cellular compartments and play a major role in signaling pathways. Overproduction of ROS is associated with the development of various human diseases (including cancer, cardiovascular, neurodegenerative, and metabolic disorders), inflammation, and aging. Tumors continuously generate ROS at increased levels that have a dual role in their development. Oxidative stress can promote tumor initiation, progression, and resistance to therapy through DNA damage, leading to the accumulation of mutations and genome instability, as well as reprogramming cell metabolism and signaling. On the contrary, elevated ROS levels can induce tumor cell death. This review covers the current data on the mechanisms of ROS generation and existing antioxidant systems balancing the redox state in mammalian cells that can also be related to tumors.

Global serum proteomic changes in water buffaloes infected with Fasciola gigantica

BACKGROUND

The liver fluke Fasciola gigantica modulates several signaling pathways in infected buffaloes to facilitate its survival and establishment of persistent infection. In response to the parasite invasion, buffaloes activate innate and adaptive immune responses to counter the parasite infection. To detect new proteins that might be involved in the interaction between F. gigantica and the buffaloes, and that also might serve as biomarkers for fasciolosis, we used proteomic techniques to study the serum proteome of buffaloes during F. gigantica infection. Here, we used an isobaric tags for relative and absolute quantitation (iTRAQ)-based quantitative proteomic approach to identify serum proteins that are differentially expressed in infected buffaloes compared to uninfected control buffaloes. Additionally, we applied a parallel reaction monitoring (PRM) assay to validate specific proteins identified by the iTRAQ method.

RESULTS

A total of 313, 459 and 399 proteins were identified at 3, 42 and 70 days post-infection, respectively; of these 92, 93 and 138 were differentially abundant proteins. Some of the identified differentially abundant proteins, including complement factor H related 5, complement component C6, complement component C7, amine oxidase, plasma serine protease inhibitor and lysozyme, are known to be involved in complement system activation, blood coagulation, platelet activation, lymphocyte's adhesion and lysozyme hydrolysis. Analysis of data for all three time points after infection identified six significantly upregulated proteins in infected serum that separated infected and uninfected buffaloes into distinct clusters. Further PRM analysis confirmed the expression of five proteins, namely MHC class I antigen, Beta-2-microglobulin, NID2 protein, Fetuin-B and Fibrinogen gamma-B chain.

CONCLUSIONS

These findings provide novel insights into the serum proteomics signature of buffaloes during F. gigantica infection.

Design, Synthesis, and Evaluation of Monoamine Oxidase A Inhibitors⁻Indocyanine Dyes Conjugates as Targeted Antitumor Agents

Monoamine oxidase A (MAOA) is an important mitochondria-bound enzyme that catalyzes the oxidative deamination of monoamine neurotransmitters. Accumulating evidence suggests a significant association of increased MAOA expression and advanced high-grade prostate cancer (PCa) progression and metastasis. Herein, a series of novel conjugates combining the MAOA inhibitor isoniazid (INH) and tumor-targeting near-infrared (NIR) heptamethine cyanine dyes were designed and synthesized. The synthesized compounds G1–G13 were evaluated in vitro for their cytotoxicity against PC-3 cells using the MTT assay, and molecular docking studies were performed. Results showed that most tested compounds exhibited improved antitumor efficacy compared with INH. Moreover, conjugates G10 and G11 showed potent anticancer activity with IC₅₀ values (0.85 and 0.4 μM respectively) comparable to that of doxorubicin (DOX). This may be attributable to the preferential accumulation of these conjugates in tumor cells. G10, G11, and G12 also demonstrated moderate MAOA inhibitory activities. This result and the results of molecular docking studies were consistent with their cytotoxicity activities. Taken together, these data suggest that a combination of the MAOA inhibitor INH with tumor-targeting heptamethine cyanine dyes may prove to be a highly promising tool for the treatment of advanced prostate cancer.

Site-specific expression of amine oxidases in breast cancer metastases

We aimed to evaluate the expression of amine oxidase-related proteins in metastatic breast cancer tissue and determine its clinical implication. A tissue microarray was constructed from a total of 126 metastatic breast tumors (31 bone metastases (24.6%), 36 brain metastases (28.6%), 11 liver metastases (8.7%), and 48 lung metastases (38.1%)). Immunohistochemical staining for amine oxidase-related proteins (lysyl oxidase, diamine oxidase, and monoamine oxidase A and B) was performed. In metastatic breast cancer tissue, lysyl oxidase ( p = 0.001), tumoral diamine oxidase ( p = 0.003), stromal diamine oxidase ( p = 0.047), and stromal monoamine oxidase B ( p = 0.002) were differentially expressed in different metastatic sites. Bone metastases showed low expression of lysyl oxidase, tumoral diamine oxidase, and stromal diamine oxidase. We observed high expression of lysyl oxidase in brain metastases, tumoral diamine oxidase in liver metastases, stromal diamine oxidase in lung metastases, and stromal monoamine oxidase B in bone metastases. Lysyl oxidase positivity was associated with progesterone receptor negativity ( p = 0.001), and monoamine oxidase A positivity was associated with human epidermal growth factor receptor-2 negativity ( p = 0.003) and the luminal A subtype ( p = 0.003). On univariate analysis shorter overall survival was associated with stromal diamine oxidase negativity ( p = 0.008), especially in lung metastases ( p = 0.025), and stromal monoamine oxidase B positivity ( p < 0.001). Stromal monoamine oxidase B positivity was an independent prognostic factor for shorter overall survival in multivariate Cox analysis (hazard ratio, 4.069; 95% confidence interval, 1.649–10.04; p = 0.002). Finally, in metastatic breast cancer, amine oxidase-related proteins were differentially expressed in a manner specific to metastatic site, and stromal monoamine oxidase B expression was correlated with prognosis.