The Function and Significance of SELENBP1 Downregulation in Human Bronchial Epithelial Carcinogenic Process

Background

Our quantitative proteomic study showed that selenium-binding protein 1 (SELENBP1) was progressively decreased in human bronchial epithelial carcinogenic process. However, there is little information on expression and function of SELENBP1 during human lung squamous cell cancer (LSCC) carcinogenesis.

Methods

iTRAQ-tagging combined with 2D LC-MS/MS analysis was used to identify differentially expressed proteins in the human bronchial epithelial carcinogenic process. SELENBP1, member of selenoproteins family and progressively downregulated in this process, was selected to further study. Both Western blotting and immunohistochemistry were performed to detect SELENBP1 expression in independent sets of tissues of bronchial epithelial carcinogenesis, and ability of SELENBP1 for discriminating NBE (normal bronchial epithelium) from preneoplastic lesions from invasive LSCC was evaluated. The effects of SELENBP1 downregulation on the susceptibility of benzo(a)pyrene (B[a]P)-induced human bronchial epithelial cell transformation were determined.

Results

102 differentially expressed proteins were identified by quantitative proteomics, and SELENBP1 was found and confirmed being progressively decreased in the human bronchial epithelial carcinogenic process. The sensitivity and specificity of SELENBP1 were 80% and 79% in discriminating NBE from preneoplastic lesions, 79% and 82% in discriminating NBE from invasive LSCC, and 77% and 71% in discriminating preneoplastic lesions from invasive LSCC, respectively. Furthermore, knockdown of SELENBP1 in immortalized human bronchial epithelial cell line 16HBE cells significantly increased the efficiency of B[a]P-induced cell transformation.

Conclusions

The present data shows for the first time that decreased SELENBP1 is an early event in LSCC, increases B[a]P-induced human bronchial epithelial cell transformation, and might serve as a novel potential biomarker for early detection of LSCC.     

LCM纯化的人支气管上皮癌变各阶段组织的定量蛋白质组学研究

为分析支气管上皮癌变进程中的差异表达蛋白质,筛选肺鳞癌早期诊断标志物,以人支气管上皮癌变各阶段组织为研究对象,先采用激光捕获显微切割技术(LCM) 纯化人正常支气管上皮组织、鳞状化生、不典型增生、原位癌、浸润性肺鳞癌组织,再用同位素标记相对和绝对定量 (iTRAQ) 技术结合二维液相色谱串联质谱（2D LC-MS/MS）鉴定支气管上皮癌变进程中各阶段的差异表达蛋白质。结果共鉴定了1036个蛋白质,筛选出102个与人支气管上皮癌变相关的差异蛋白质,在这些差异蛋白质中,有的在支气管上皮癌变过程中进行性上调,有的在支气管上皮癌变过程中进行性下调,有的呈阶段特异性改变;功能分析表明,这些差异蛋白质涉及代谢、细胞凋亡、增殖、分化、信号传导、转录、翻译、细胞粘附、免疫反应与发育等。Western blotting 及免疫组织化学技术验证了其中 2个差异蛋白(S100A9和 CKB) 的表达,证实了定量蛋白质组学结果的可靠性。研究结果提示：这些差异表达蛋白质与支气管上皮癌变相关,并可成为肺鳞癌的早期诊断标志物,进一步研究差异蛋白的生物学功能,将有助于阐明支气管上皮的癌变机制,从而为肺鳞癌的早期诊断与发病机制研究提供新思路。     

Heterogeneous nuclear ribonucleoprotein B1 protein impairs DNA repair mediated through the inhibition of DNA-dependent protein kinase activity

Heterogeneous nuclear ribonucleoprotein B1, an RNA binding protein, is overexpressed from the early stage of lung cancers; it is evident even in bronchial dysplasia, a premalignant lesion. We evaluated the proteins bound with hnRNP B1 and found that hnRNP B1 interacted with DNA-dependent protein kinase (DNA-PK) complex, and recombinant hnRNP B1 protein dose-dependently inhibited DNA-PK activity in vitro. To test the effect of hnRNP B1 on DNA repair, we performed comet assay after irradiation, using normal human bronchial epithelial (HBE) cells treated with siRNA for hnRNP A2/B1: reduction of hnRNP B1 treated with siRNA for hnRNP A2/B1 induced faster DNA repair in normal HBE cells. Considering these results, we assume that overexpression of hnRNP B1 occurring in the early stage of carcinogenesis inhibits DNA-PK activity, resulting in subsequent accumulation of erroneous rejoining of DNA double-strand breaks, causing tumor progression.     

Comparative proteomic analysis of anti-benzo(a)pyrene-7,8-dihydrodiol-9,10-epoxide-transformed and normal human bronchial epithelial G0/G1 cells

In the present study, we investigated the proteomic profiling of anti-benzo(a)pyrene-7,8-dihydrodiol-9,10-epoxide (anti-BPDE)-transformed human bronchial epithelial cell line (16HBE-C) and its parental cell line (16HBE) G0/G1 cells. Differential analysis of proteomic profiling indicated that 67 polypeptides were down-regulated and 77 polypeptides were up-regulated in 16HBE-C G0/G1 cells compared to 16HBE G0/G1 cells. Then 16 differentially expressed protein spots were analyzed with Q-TOF MS/MS. Of these spots, 3 down-regulated polypeptides were identified as sorcin, small ubiquitin-related modifier 2 precursor and eukaryotic translation initiation factor 5A-1, and 9 up-regulated polypeptides were identified as calmodulin, myosin light polypeptide 6, eukaryotic translation initiation factor 6, proliferating cell nuclear antigen (PCNA), tumor protein D52 (TPD52), superoxide dismutase [Cu-Zn], prohibitin, nuclear protein Hcc-1 and vimentin. These proteins are involved in cell proliferation, protein synthesis, signal transduction and carcinogenesis. Western blotting analysis verified the increased expression levels of PCNA and TPD52 in 16HBE-C G0/G1 cells. Based on the clues from proteomic analysis, the migration and invasion capabilities of 16HBE-C and 16HBE cells were tested. The results indicated that 16HBE-C cells showed much higher migration and invasion capabilities than 16HBE cells, and moreover, the suppression of TPD52 by RNAi resulted in significant decrease of migration and invasion capabilities of 16HBE-C cells. These results will be valuable for further investigating and understanding the mechanisms underlying BaP-induced carcinogenesis.     

Quantitative proteomics revealed new functions of ALKBH4

ALKBH4 is a versatile demethylase capable of catalyzing the demethylation of monomethylated lysine-84 on actin and N⁶-methyladenine in DNA. In this study, we conducted a quantitative proteomic experiment to reveal the altered expression of proteins in HEK293T cells upon genetic ablation of ALKBH4. Our results showed markedly diminished levels of GSTP1 and HSPB1 proteins in ALKBH4-depleted cells, which emanate from an augmented expression level of DNA (cytosine-5)-methyltransferase 1 (DNMT1) and the ensuing elevated cytosine methylation in the promoter regions of GSTP1 and HSPB1 genes. Together, our results revealed a role of ALKBH4 in modulating DNA cytosine methylation through regulating the expression level of DNMT1 protein.     

Nutritional factors in lung, colon, and prostate carcinogenesis in animal models

Dietary factors are now considered to be among the most important environmental risk determinants for cancer. In addition to epidemiological studies, experimental animal studies are an important tool to investigate dietary modulation in carcinogenesis. Results of recent experimental studies on the effect of some nutrients indicate that vitamin A did show an inverse relation with the occurrence of preneoplastic respiratory lesions but not with respiratory tract tumors in benzo[a]pyrene-induced respiratory carcinogenesis. Dietary fat increases respiratory tract tumors and preneoplastic lesions. In colon carcinogenesis, a fat-fiber interrelation was noticed in 1,2-dimethyl-hydrazine- and N-methyl-N'-nitro-N-nitrosoguanidine-induced tumors. Preliminary results in prostate carcinogenesis indicate that dietary fat did not influence the incidence of prostate cancer in a recently developed rat model. Some possible mechanisms in colon and prostate carcinogenesis are discussed.     

Viral inhibition of IL-1- and neutrophil elastase-induced inflammatory responses in bronchial epithelial cells

Previously, we elucidated the intracellular mechanisms by which neutrophil elastase (NE) up-regulates inflammatory gene expression in bronchial epithelial cells. In this study, we examine the effects of both IL-1 and NE on inflammatory gene expression in 16HBE14o- bronchial epithelial cells and investigate approaches to abrogate these inflammatory responses. IL-1 induced IL-8 protein production in time- and dose-dependent fashions, an important observation given that IL-8 is a potent neutrophil chemoattractant and a key inflammatory mediator. IL-1 and NE were shown to activate the p38 MAPK pathway in 16HBE14o- cells. Western blot analysis demonstrated IL-1R-associated kinase 1 (IRAK-1) degradation in response to stimulation with both IL-1 and NE. In addition, the expression of dominant negative IRAK-1 (IRAK-1delta), IRAK-2delta, or IRAK-4delta inhibited IL-1- and NE-induced NF-kappaB-linked reporter gene expression. Dominant negative versions of the intracellular adaptor proteins MyD88 (MyD88delta) and MyD88 adaptor-like (Mal P/H) abrogated NE-induced NF-kappaB reporter gene expression. In contrast, only MyD88delta was found to inhibit IL-1-induced NF-kappaB reporter activity. We also investigated the vaccinia virus proteins, A46R and A52R, which have been shown to antagonize IL-1 signaling. Transfection with A46R or A52R cDNA inhibited IL-1- and NE-induced NF-kappaB and IL-8R gene expression and IL-8 protein production in primary and transformed bronchial epithelial cells. Furthermore, cytokine array studies demonstrated that IL-1 and NE can up-regulate the expression of IL-6, oncostatin M, epithelial cell-derived neutrophil activating peptide-78, growth-related oncogene family members, vascular endothelial growth factor, and GM-CSF, with induction of these proteins inhibited by the viral proteins. These findings identify vaccinia virus proteins as possible therapeutic agents for the manifestations of several inflammatory lung diseases.     

Down-regulation of epidermal growth factor receptor by curcumin-induced UBE1L in human bronchial epithelial cells

UBE1L, ubiquitin-activating enzyme E1-like, is the activating enzyme of ISG15ylation (ISG15, interferon stimulated gene 15). Loss of UBE1L and activation of epidermal growth factor receptor (EGFR) signaling are common events in lung carcinogenesis. Curcumin, a well-studied chemopreventive agent, is known to down-regulate EGFR. The present study demonstrated that curcumin decreased EGFR expression in human bronchial epithelial (HBE) Beas-2B cells and lung cancer A549 cells. For the first time, UBE1L was found to be induced by curcumin in HBE cells. Interestingly, overexpression of UBE1L reduced EGFR at posttranslational level in HBE cells. UBE1L triggered EGFR membrane internalization and promoted complex formation between ISG15 and EGFR. Curcumin decreased EGFR downstream signaling pAKT and nuclear factor κB (NF-κB). Overexpression or knockdown of UBE1L also resulted in down-regulation or up-regulation of phosphoinositide 3-kinase/AKT/NF-κB correspondently. In human samples, there was an inverse relationship between UBE1L and EGFR/AKT/NF-κB in non-small cell lung cancer tissues and adjacent tissues. These results uncover a novel chemopreventive mechanism of curcumin in inducing UBE1L and down-regulating EGFR signaling in HBE cells.     

Bronchial epithelial cell matrix production in response to silica and basic fibroblast growth factor

BACKGROUND: Previous studies show that macrophages, lung fibroblasts, and their soluble mediators are responsible for the onset and development of pulmonary fibrosis. This study was conducted to determine whether airway epithelial cells are also directly involved in response to fibrogenic agents and consequently in the pathogenesis of lung fibrosis. To verify the hypothesis, we determined whether silica acts directly on human bronchial epithelial cells by stimulating cytokine and growth factor release and by modifying matrix production. MATERIALS AND METHODS: An SV40 large T antigen-transformed human airway epithelial cell line, 16HBE14o (16HBE), was used. The expression profile of some proinflammatory interleukins (ILs), such as IL-1alpha, IL-1beta and IL-6 and their modulation by silica, were evaluated by polymerase chain reaction (PCR) analysis. Transforming growth factor beta (TGFbeta) and basic fibroblast growth factor (bFGF) mRNA levels were tested by Northern blotting in the presence and in the absence of silica. The silica- and/or bFGF-induced effects on matrix components (total proteins, collagen, and fibronectin) were also evaluated using radio-labeled precursors. RESULTS: The results demonstrated 16HBE internalized silica particles. Silica induced a little IL-6 secretion, without affecting IL-1 and TGFbeta isoform production and strongly stimulated bFGF mRNA level and bFGF protein secretion. Silica also induced changes in 16HBE production of total proteins, collagen, and fibronectin production. When added in combination with the growth factor, it strengthened bFGF stimulation of matrix component secretion. CONCLUSIONS: These results support the hypothesis that the changes in matrix components are due to a direct effect of silica on bronchial epithelial cells. Silica-induced over-secretion of bFGF suggests that autocrine and paracrine differentiation loops for bFGF may also be operative and that these mechanisms may be involved in the pathogenesis of pulmonary fibrosis. In the future, cytokine-directed therapeutic strategies might find a place in clinical practice.     

Activation of MTOR in pulmonary epithelium promotes LPS-induced acute lung injury

MTOR (mechanistic target of rapamycin [serine/threonine kinase]) plays a crucial role in many major cellular processes including metabolism, proliferation and macroautophagy/autophagy induction, and is also implicated in a growing number of proliferative and metabolic diseases. Both MTOR and autophagy have been suggested to be involved in lung disorders, however, little is known about the role of MTOR and autophagy in pulmonary epithelium in the context of acute lung injury (ALI). In the present study, we observed that lipopolysaccharide (LPS) stimulation induced MTOR phosphorylation and decreased the expression of MAP1LC3B/LC3B (microtubule-associated protein 1 light chain 3 β)-II, a hallmark of autophagy, in mouse lung epithelium and in human bronchial epithelial (HBE) cells. The activation of MTOR in HBE cells was mediated by TLR4 (toll-like receptor 4) signaling. Genetic knockdown of MTOR or overexpression of autophagy-related proteins significantly attenuated, whereas inhibition of autophagy further augmented, LPS-induced expression of IL6 (interleukin 6) and IL8, through NFKB signaling in HBE cells. Mice with specific knockdown of Mtor in bronchial or alveolar epithelial cells exhibited significantly attenuated airway inflammation, barrier disruption, and lung edema, and displayed prolonged survival in response to LPS exposure. Taken together, our results demonstrate that activation of MTOR in the epithelium promotes LPS-induced ALI, likely through downregulation of autophagy and the subsequent activation of NFKB. Thus, inhibition of MTOR in pulmonary epithelial cells may represent a novel therapeutic strategy for preventing ALI induced by certain bacteria.     

Poly(ADP-Ribose) Glycohydrolase (PARG) Silencing Suppresses Benzo(a)pyrene Induced Cell Transformation

Benzo(a)pyrene (BaP) is a ubiquitously distributed environmental pollutant and known carcinogen, which can induce malignant transformation in rodent and human cells. Poly(ADP-ribose) glycohydrolase (PARG), the primary enzyme that catalyzes the degradation of poly(ADP-ribose) (PAR), has been known to play an important role in regulating DNA damage repair and maintaining genomic stability. Although PARG has been shown to be a downstream effector of BaP, the role of PARG in BaP induced carcinogenesis remains unclear. In this study, we used the PARG-deficient human bronchial epithelial cell line (shPARG) as a model to examine how PARG contributed to the carcinogenesis induced by chronic BaP exposure under various concentrations (0, 10, 20 and 40 μM). Our results showed that PARG silencing dramatically reduced DNA damages, chromosome abnormalities, and micronuclei formations in the PARG-deficient human bronchial epithelial cells compared to the control cells (16HBE cells). Meanwhile, the wound healing assay showed that PARG silencing significantly inhibited BaP-induced cell migration. Furthermore, silencing of PARG significantly reduced the volume and weight of tumors in Balb/c nude mice injected with BaP induced transformed human bronchial epithelial cells. This was the first study that reported evidences to support an oncogenic role of PARG in BaP induced carcinogenesis, which provided a new perspective for our understanding in BaP exposure induced cancer.     

Hepatocyte growth factor and other fibroblast secretions modulate the phenotype of human bronchial epithelial cells

The luminal airway surface is lined with epithelial cells that provide a protective barrier from the external environment and clear inhaled pathogens from the lung. To accomplish this important function, human bronchial epithelial (HBE) cells must be able to rapidly regenerate a mucociliary layer of cells following epithelial injury. Whereas epithelial-fibroblast interactions are known to modulate the airway architecture during lung development and repair, little is known about how these two cells interact. Using a primary HBE and lung fibroblast coculture system, we demonstrate that 1) subepithelial fibroblasts provide a suitable environment for differentiation of HBE cells into a polarized ciliated phenotype despite being cultured in media that induces terminal squamous differentiation and growth arrest in the absence of fibroblasts, 2) HBE cells cocultured with subepithelial fibroblasts exhibit augmented ciliogenesis, accelerated wound repair, and diminished polarized ion transport compared with cells grown in control conditions, and 3) hepatocyte growth factor (HGF) is important for subepithelial fibroblast modulation of HBE cell differentiation. These results provide a model to study fibroblast modulation of epithelial phenotype and indicate that HGF secreted by subepithelial fibroblasts contributes to HBE cell differentiation.     

Differential proteomic analysis of noncardia gastric cancer from individuals of northern Brazil

Gastric cancer is the second leading cause of cancer-related death worldwide. The identification of new cancer biomarkers is necessary to reduce the mortality rates through the development of new screening assays and early diagnosis, as well as new target therapies. In this study, we performed a proteomic analysis of noncardia gastric neoplasias of individuals from Northern Brazil. The proteins were analyzed by two-dimensional electrophoresis and mass spectrometry. For the identification of differentially expressed proteins, we used statistical tests with bootstrapping resampling to control the type I error in the multiple comparison analyses. We identified 111 proteins involved in gastric carcinogenesis. The computational analysis revealed several proteins involved in the energy production processes and reinforced the Warburg effect in gastric cancer. ENO1 and HSPB1 expression were further evaluated. ENO1 was selected due to its role in aerobic glycolysis that may contribute to the Warburg effect. Although we observed two up-regulated spots of ENO1 in the proteomic analysis, the mean expression of ENO1 was reduced in gastric tumors by western blot. However, mean ENO1 expression seems to increase in more invasive tumors. This lack of correlation between proteomic and western blot analyses may be due to the presence of other ENO1 spots that present a slightly reduced expression, but with a high impact in the mean protein expression. In neoplasias, HSPB1 is induced by cellular stress to protect cells against apoptosis. In the present study, HSPB1 presented an elevated protein and mRNA expression in a subset of gastric cancer samples. However, no association was observed between HSPB1 expression and clinicopathological characteristics. Here, we identified several possible biomarkers of gastric cancer in individuals from Northern Brazil. These biomarkers may be useful for the assessment of prognosis and stratification for therapy if validated in larger clinical study sets.     

Cigarette smoke extract affects functional activity of MRP1 in bronchial epithelial cells

Cigarette smoke is the principal risk factor for development of chronic obstructive pulmonary disease (COPD). Multidrug resistance-associated protein 1 (MRP1) is a member of the ATP-binding cassette (ABC) superfamily of transporters, which transport physiologic and toxic substrates across cell membranes. MRP1 is highly expressed in lung epithelium. This study aims to analyze the effect of cigarette smoke extract (CSE) on MRP1 activity. In the human bronchial epithelial cell line 16HBE14o-, MRP1 function was studied flow cytometrically by cellular retention of carboxyfluorescein (CF) after CSE incubation and MRP1 downregulation by RNA interference (siRNA). Cell survival was measured by the MTT assay. Immunocytochemically, it was shown that 16HBE14o(-) expressed MRP1 and breast cancer resistance protein. Coincubation of CSE IC50 (1.53% +/- 0.22%) with MK571 further decreased cell survival 31% (p, = 0.018). CSE increased cellular CF retention dose dependently from 1.7-fold at 5% CSE to 10.3-fold at 40% CSE (both p < 0.05). siRNA reduced MRP1 RNA expression with 49% and increased CF accumulation 67% versus control transfected cells. CSE exposure further increased CF retention 24% (p = 0.031). A linear positive relation between MRP1 function and CSE-modulating effects (r = 0.99, p =0.089) was shown in untransfected, control transfected, and MRP1 downregulated 16HBE14o- cells analogous to blocking effects with MRP1 inhibitor MK571 (r = 0.99, p = 0.034). In conclusion, cigarette smoke extract affects MRP1 activity probably competitively in bronchial epithelial cells. Inhibition of MRP1 in turn results in higher CSE toxicity. We propose that MRP1 may be a protective protein for COPD development.     

Latent adenoviral infection induces production of growth factors relevant to airway remodeling in COPD

Previous studies showed an association between latent adenoviral infection with expression of the adenoviral E1A gene and chronic obstructive pulmonary disease (COPD). The present study focuses on how the adenoviral E1A gene could alter expression of growth factors by human bronchial epithelial (HBE) cells. The data show that connective tissue growth factor (CTGF) and transforming growth factor (TGF)-beta 1 mRNA and protein expression were upregulated in E1A-positive HBE cells. Upregulation of CTGF in this in vitro model was independent of TGF-beta secreted into the growth medium. Comparison of E1A-positive with E1A-negative HBE cells showed that both expressed cytokeratin but only E1A-positive cells expressed the mesenchymal markers vimentin and alpha-smooth muscle actin. We conclude that latent infection of epithelial cells by adenovirus E1A could contribute to airway remodeling in COPD by the viral E1A gene, inducing TGF-beta 1 and CTGF expression and shifting cells to a more mesenchymal phenotype.     

Inflammatory cytokines can enhance CD44-mediated airway epithelial cell adhesion independently of CD44 expression

In airways, the cell surface molecule CD44 is upregulated on bronchial epithelial cells in areas of damage. We have shown that a blocking standard CD44 (CD44s) antibody caused a 77% (+/- 19%) inhibition of cell migration at 3 h after mechanical damage and decreased epithelial cell repair of cells grown on cell culture filter inserts. With the use of primary human bronchial epithelial cells and the bronchial epithelial cell line 16HBE 14o-, a CD44s antibody inhibited >95% (P < 0.01) of cell binding to hyaluronic acid (HA). The cytokines TNF-alpha, IFN-gamma, IL-1 beta, and IL-4 stimulated a 2- to 3.5-fold increase in CD44-dependent cell binding to HA. IFN-gamma treatment did not increase CD44 expression as assessed by flow cytometry, although phorbol myristate acetate treatment did. This indicates that IFN-gamma-induced cell binding to HA did not require increased CD44 expression. These data indicate that CD44 is important for bronchial epithelial cell binding to HA and that cytokines known to be expressed in inflammation can increase HA binding independently of the level of CD44 expression.     

线粒体DNA拷贝量降低诱发人支气管上皮细胞钙信号失调

采用溴化乙锭（EtBr）诱导线粒体DNA（mitochondrial DNA,mtDNA）拷贝量降低的人支气管上皮细胞株（ρ-HBE）;Real—timePCR与共聚焦成像表明,经EtBr诱导60d并挑取的单克隆细胞株,其mtDNA拷贝量下降为正常细胞的24％,成功构建了ρ-HBE。与母本细胞相比,ρ-HBE群体倍增时间延长,生长速度减慢。流式细胞术检测细胞线粒体膜电位（△ψm）下降,以Fura-2标记胞浆内游离钙,ρ-HBE[Ca2＋]i升高;线粒体解耦联剂FccP刺激细胞后,激光共聚焦扫描显微镜动态监测单个活细胞[Ca2＋]i变化,发现[ca2＋]i水平波动幅度小。提示mtDNA拷贝数降低可导致细胞内钙信号调节紊乱。     

Low expression of GSTP1 in the aqueous humour of patients with primary open-angle glaucoma

Primary open-angle glaucoma (POAG) is characterized by irreversible neurodegeneration accompanied by visual field defects and high intraocular pressure. Currently, an effective treatment is not available to prevent the progression of POAG, other than treatments to decrease the high intraocular pressure. We performed proteomic analysis of aqueous humour (AH) samples from patients with POAG combined with cataract and patients with cataract to obtain a better understanding of the pathogenesis of POAG and explore potential treatment targets for this condition. Samples were collected from 10 patients with POAG combined with cataract and 10 patients with cataract. Samples from each group were pooled. A high-resolution, label-free, liquid chromatography-tandem mass spectrometry-based quantitative proteomic analysis was performed. In total, 610 proteins were identified in human AH samples from the two groups. A total of 48 up-regulated proteins and 49 down-regulated proteins were identified in the POAG combined with cataract group compared with the control group. Gene Ontology (GO) analysis revealed key roles for these proteins in inflammation, immune responses, growth and development, cellular movement and vesicle-mediated transport in the biological process category. Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis indicated the down-regulated expression of glutathione S-transferase P (GSTP1) in the glutathione metabolism signalling pathway in the POAG combined with cataract group. Additionally, certain significantly differentially expressed proteins in the proteomic profile were verified by enzyme-linked immunosorbent assay (ELISA). GSTP1 levels were reduced in the human AH samples from the POAG combined with cataract group, based on the results of ELISA and proteomic profiling. Therefore, GSTP1, a redox-related marker, may be involved in the pathological process of POAG and may become a treatment target in the future.