Triosephosphate isomerase and peroxiredoxin 6, two novel serum markers for human lung squamous cell carcinoma

Blood FOLR3 methylation dysregulations and heterogeneity in non-small lung cancer highlight its strong associations with lung squamous carcinoma

BACKGROUND

Non-small cell lung cancer (NSCLC) accounts for the vast majority of lung cancers. Early detection is crucial to reduce lung cancer-related mortality. Aberrant DNA methylation occurs early during carcinogenesis and can be detected in blood. It is essential to investigate the dysregulated blood methylation markers for early diagnosis of NSCLC.

METHODS

NSCLC-associated methylation gene folate receptor gamma (FOLR3) was selected from an Illumina 850K array analysis of peripheral blood samples. Mass spectrometry was used for validation in two independent case-control studies (validation I: n = 2548; validation II: n = 3866). Patients with lung squamous carcinoma (LUSC) or lung adenocarcinoma (LUAD), normal controls (NCs) and benign pulmonary nodule (BPN) cases were included. FOLR3 methylations were compared among different populations. Their associations with NSCLC clinical features were investigated. Receiver operating characteristic analyses, Kruskal-Wallis test, Wilcoxon test, logistics regression analysis and nomogram analysis were performed.

RESULTS

Two CpG sites (CpG_1 and CpG_2) of FOLR3 was significantly lower methylated in NSCLC patients than NCs in the discovery round. In the two validations, both LUSC and LUAD patients presented significant FOLR3 hypomethylations. LUSC patients were highlighted to have significantly lower methylation levels of CpG_1 and CpG_2 than BPN cases and LUAD patients. Both in the two validations, CpG_1 methylation and CpG_2 methylation could discriminate LUSC from NCs well, with areas under the curve (AUCs) of 0.818 and 0.832 in validation I, and 0.789 and 0.780 in validation II. They could also differentiate LUAD from NCs, but with lower efficiency. CpG_1 and CpG_2 methylations could also discriminate LUSC from BPNs well individually in the two validations. With the combined dataset of two validations, the independent associations of age, gender, and FOLR3 methylation with LUSC and LUAD risk were shown and the age-gender-CpG_1 signature could discriminate LUSC and LUAD from NCs and BPNs, with higher efficiency for LUSC.

CONCLUSIONS

Blood-based FOLR3 hypomethylation was shown in LUSC and LUAD. FOLR3 methylation heterogeneity between LUSC and LUAD highlighted its stronger associations with LUSC. FOLR3 methylation and the age-gender-CpG_1 signature might be novel diagnostic markers for the early detection of NSCLC, especially for LUSC.

Anti-Oxidant and Pro-Oxidant Effects of Peroxiredoxin 6: A Potential Target in Respiratory Diseases

Peroxiredoxin 6 (PRDX6) is widely distributed in several organs, especially the lungs. The role of PRDX6 in oxidative stress is controversial and even contradictory, as indicated by research conducted over the past 20 years. PRDX6 has anti-oxidant or pro-oxidant effects on oxidative stress in different diseases. It can even exhibit both anti-oxidant and pro-oxidant effects in the same disease. These findings are attributed to the fact that PRDX6 is a multifunctional enzyme. The peroxidase and phospholipase A2 activity of PRDX6 is closely related to its anti-oxidant and pro-oxidant effects, which leads to the conflicting regulatory effects of PRDX6 on oxidative stress in respiratory diseases. Moreover, PRDX6 interacts with multiple redox signaling pathways to interfere with cell proliferation and apoptosis. PRDX6 has become a new target in respiratory disease research due to its important regulatory role in oxidative stress. In this paper, the role of PRDX6 in oxidative stress in respiratory diseases and the research progress in targeting PRDX6 are reviewed.

Quantitative Proteomics Reveals Down-Regulated Glycolysis/Gluconeogenesis in the Large-Duct Type Intrahepatic Cholangiocarcinoma

Intrahepatic cholangiocarcinoma (iCCA) is a lethal hepatobiliary malignancy that arises from the epithelial cells of the intrahepatic bile ducts, accounting for approximately 10% of cholangiocarcinoma (CCA). According to the 2019 World Health Organization (WHO) classification of tumors of the digestive system, iCCA is divided into small-duct type (SD-type) and large-duct type (LD-type). However, it remains unknown which molecular events contribute to the disparity. To explore the proteomic characteristics of iCCA, we used an isobaric tag for relative and absolute quantitation (iTRAQ) based quantitative proteomics strategy to investigate stably dysregulated proteins in the SD-type and LD-type of iCCA tissues. Importantly, we found three glycolysis/gluconeogenesis-related enzymes, triosephosphate isomerize 1 (TPI1), glyceraldehyde-3-phosphate dehydrogenase (GAPDH), and phosphoglycerate kinase 1 (PGK1), were significantly down-regulated in the LD-type iCCA, which were further confirmed by immunohistochemistry using tissue microarray. Moreover, we demonstrated that the knockdown of these three candidate proteins by siRNAs notably increased the ability of proliferation in two CCA cell lines (HuH28 and RBE), suggesting that effective down-regulation of the glycolysis/gluconeogenesis pathway might be an underlying novel mechanism contributing to the LD-type iCCA.

TPI1 activates the PI3K/AKT/mTOR signaling pathway to induce breast cancer progression by stabilizing CDCA5

Background

Triosephosphate isomerase 1 (TPI1), as a key glycolytic enzyme, is upregulated in multiple cancers. However, expression profile and regulatory mechanism of TPI1 in breast cancer (BRCA) remain mysterious.

Methods

Western blotting and immunohistochemistry (IHC) assays were used to investigate the expression of TPI1 in BRCA specimens and cell lines. TPI1 correlation with the clinicopathological characteristics and prognosis of 362 BRCA patients was analyzed using a tissue microarray. Overexpression and knockdown function experiments in cells and mice models were performed to elucidate the function and mechanisms of TPI1-induced BRCA progression. Related molecular mechanisms were clarified using co-IP, IF, mass spectrometric analysis, and ubiquitination assay.

Results

We have found TPI1 is highly expressed in BRCA tissue and cell lines, acting as an independent indicator for prognosis in BRCA patients. TPI1 promotes BRCA cell glycolysis, proliferation and metastasis in vitro and in vivo. Mechanistically, TPI1 activates phosphoinositide 3-kinase (PI3K)/AKT/mammalian target of rapamycin (mTOR) pathway to regulate epithelial–mesenchymal transformation (EMT) and aerobic glycolysis, which is positively mediated by cell division cycle associated 5 (CDCA5). Moreover, TPI1 interacts with sequestosome-1 (SQSTM1)/P62, and P62 decreases the protein expression of TPI1 by promoting its ubiquitination in MDA-MB-231 cells.

Conclusions

TPI1 promotes BRCA progression by stabilizing CDCA5, which then activates the PI3K/AKT/mTOR pathway. P62 promotes ubiquitin-dependent proteasome degradation of TPI1. Collectively, TPI1 promotes tumor development and progression, which may serve as a therapeutic target for BRCA.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12967-022-03370-2.

Peroxiredoxin 6 Plays Essential Role in Mediating Fertilization and Early Embryonic Development in Rabbit Oviduct

The oviduct is a site for early reproductive events including gamete maturation, fertilization, and early embryo development. Secretory cells lining the oviduct lumen synthesize and secrete proteins that interact with gametes and developing embryos. Although previous studies have identified some of the secretory proteins in the oviduct, however, knowledge and their precise specific functions in the oviduct are poorly understood. In this study, by using proteomic approach, we identified a secretory protein, Peroxiredoxin 6 (PRDX6), and evaluated its role in mediating early pregnancy events, fertilization, and embryo development in rabbit oviduct. The expression of PRDX6 was significantly higher in ampulla and isthmus sections of the oviduct in mated animal groups compared to non-mated controls. Furthermore, significant reduction in number of embryos recovered from PRDX6 siRNA-transfected oviductal horn was observed compared to the control contralateral horn. Moreover, in animals receiving PRDX6 siRNA in their oviductal horn, the number of implanted blastocysts was significantly less in the uterus as observed on day 9 post-coital (p.c.). Further, during embryo-rabbit oviduct epithelial cell (ROEC) co-culture, siRNA-mediated PRDX6 silencing attenuated the early embryonic development. Mechanistically, increased levels of ROS and expression of oxidative stress- and inflammation-related proteins were found in PRDX6 siRNA-treated ROEC cells as compared to control cells, implicating that ablation of PRDX6 in the oviduct creates a stress-induced micro-environment detrimental to early embryonic development in oviduct. Taken together, our data suggest that PRDX6 maintains an optimal micro-environment conducive to successful embryo development and can be considered as a candidate to evaluate its therapeutic potential in IVF strategies.

TPI1-reduced extracellular vesicles mediated by Rab20 downregulation promotes aerobic glycolysis to drive hepatocarcinogenesis

Rab GTPases are major mediators that ensure the proper spatiotemporal regulation of intracellular trafficking. Functional impairment and altered expression of Rab proteins have been revealed in various human cancers. There is an emerging evidence about the role of Rab proteins in the biogenesis of extracellular vesicles (EVs). In hepatocellular carcinoma (HCC), using RNA sequencing comparing expression profiles of adjacent non-tumorous tissues and HCC, Rab20 is identified to be the most frequently downregulated Rab member in HCC. Functionally, restoration of Rab20 in metastatic HCC cells results in the release of EVs with a diminished activity to promote cell growth, motility and metastasis. Conversely, EVs released from normal liver cells with Rab20 knockdown loses suppressive effect on HCC cell growth and motility. Proteomic profiling revealed the level of triosephosphate isomerase 1 (TPI1), a glycolytic enzyme, in EVs to be positively associated with Rab20 expression of the releasing cells. TPI1 targeted to be expressed in EVs released by Rab20 knockdown cells compromises the oncogenic activity of EVs. Besides, EVs released by TPI1 knockdown cells recapitulates the promoting effect of EVs derived from HCC cells with Rab20 underexpression. Aerobic glycolysis is beneficial to the survival and proliferation of tumour cells. Here, we observed that the enhanced cell growth and motility are driven by the enhanced aerobic glycolysis induced by EVs with reduced TPI1. The addition of glycolytic inhibitor blocks the promoting effect of EVs with reduced TPI1. Taken together, our study provides a mechanistic link among tumour cell-derived EVs and glucose metabolism in HCC with Rab20 deregulation.

Autoantibodies to tumor-associated antigens in lung cancer diagnosis

Lung cancer (LC) accounts for the majority of cancer-related deaths worldwide. Although screening the high-risk population by low-dose CT (LDCT) has reduced mortality, the cost and high false positivity rate has prevented its general diagnostic use. As such, better and more specific minimally invasive biomarkers are needed in general and for early LC detection, specifically. Autoantibodies produced by humoral immune response to tumor-associated antigens (TAA) are emerging as a promising noninvasive biomarker for LC. Given the low sensitivity of any one single autoantibody, a panel approach could provide a more robust and promising strategy to detect early stage LC. In this review, we summarize the background of TAA autoantibodies (TAAb) and the techniques currently used for identifying TAA, as well as recent findings of LC specific antigens and TAAb. This review provides guidance toward the development of accurate and reliable TAAb as immunodiagnostic biomarkers in the early detection of LC.

Sequenced Combinations of Cisplatin and Selected Phytochemicals towards Overcoming Drug Resistance in Ovarian Tumour Models

In the present study, cisplatin, artemisinin, and oleanolic acid were evaluated alone, and in combination, on human ovarian A2780, A2780^ZD0473R, and A2780^cisR cancer cell lines, with the aim of overcoming cisplatin resistance and side effects. Cytotoxicity was assessed by MTT reduction assay. Combination index (CI) values were used as a measure of combined drug effect. MALDI TOF/TOF MS/MS and 2-DE gel electrophoresis were used to identify protein biomarkers in ovarian cancer and to evaluate combination effects. Synergism from combinations was dependent on concentration and sequence of administration. Generally, bolus was most synergistic. Moreover, 49 proteins differently expressed by 2 ≥ fold were: CYPA, EIF5A1, Op18, p18, LDHB, P4HB, HSP7C, GRP94, ERp57, mortalin, IMMT, CLIC1, NM23, PSA3,1433Z, and HSP90B were down-regulated, whereas hnRNPA1, hnRNPA2/B1, EF2, GOT1, EF1A1, VIME, BIP, ATP5H, APG2, VINC, KPYM, RAN, PSA7, TPI, PGK1, ACTG and VDAC1 were up-regulated, while TCPA, TCPH, TCPB, PRDX6, EF1G, ATPA, ENOA, PRDX1, MCM7, GBLP, PSAT, Hop, EFTU, PGAM1, SERA and CAH2 were not-expressed in A2780^cisR cells. The proteins were found to play critical roles in cell cycle regulation, metabolism, and biosynthetic processes and drug resistance and detoxification. Results indicate that appropriately sequenced combinations of cisplatin with artemisinin (ART) and oleanolic acid (OA) may provide a means to reduce side effects and circumvent platinum resistance.

Therapeutic Targeting of Cancer Metabolism with Triosephosphate Isomerase

The increase in glycolytic flux in cancer, known as aerobic glycolysis, is one of the most important hallmarks of cancer. Therefore, glycolytic enzymes have importance in understanding the molecular mechanism of cancer progression. Triosephosphate isomerase (TPI) is one of the key glycolytic enzymes. Furthermore, it takes a part in gluconeogenesis, pentose phosphate pathway and fatty acid biosynthesis. To date, it has been shown altered levels of TPI in various cancer types, especially in metastatic phenotype. According to other studies, TPI might be considered as a potential therapeutic target and a cancer-related biomarker in different types of cancer. However, its function in tumor formation and development has not been fully understood. Here, we reviewed the relationship between TPI and cancer for the first time.

Peroxiredoxins and Immune Infiltrations in Colon Adenocarcinoma: Their Negative Correlations and Clinical Significances, an In Silico Analysis

Background: Peroxiredoxins (PRDXs) were reported to be associated with inflammation response in previous studies. In colon adenocarcinoma (COAD), however, their correlations and clinical significance were unclear.

Methods: The RNA-seq data of 452 COAD patients with clinical information was downloaded from The Cancer Genome Atlas (TCGA) and transcripts per million (TPM) normalized. Comparisons of relative expressions of PRDXs between COAD tumor and normal controls were applied. PRDXs dy-regulations in COAD were validated via Oncomine, Human Protein Atlas (HPA) and Gene Expression Omnibus (GEO) repository. Through Tumor Immune Estimation Resource (TIMER), the immune estimation of TCGA-COAD patients was downloaded and the dy-regulated PRDXs were analyzed for their correlations with immune infiltrations in COAD. The TCGA-COAD patients were divided into younger group (age≤65 years) and older group (age>65 years) to investigate the prognostic roles of age, TNM stage, dy-regulated PRDXs and the immune infiltrations in different age groups through Kaplan-Meier survival and Cox regression analyses.

Results: Three of the PRDX members showed their expressional differences both at protein and mRNA level. PRDX2 was consistently up-regulated while PRDX6 down-regulated in COAD. PRDX1 was overexpressed (mRNA) while nuclear absent (protein) in the tumor tissues. PRDX1 overexpression and PRDX6 under-expression were also shown in the stem-like colonospheres from colon cancer cells. Via TIMER, PRDX1, PRDX2, and PRDX6 were found to be negatively correlated with the immune infiltrations in COAD. Both in the younger and older patients, TNM stage had prognostic effects on their overall survival (OS) and recurrence-free survival (RFS). CD4⁺ T cell had independent unfavorable effects on OS of the younger patients while age had similar effects on RFS of the older ones. CD8⁺ T cell was independently prognostic for RFS in the two groups.

Conclusions: Late diagnosis indicated poor prognosis in COAD and dy-regulated PRDXs w might be new markers for its early diagnosis. Age was prognostic and should be considered in the treatments of the older patients. Dy-regulated PRDXs were negatively correlated with immune infiltration levels. CD4⁺ T cell and CD8⁺ T cell infiltrations were prognostic in COAD and their potential as immune targets needed further investigation.

Peroxiredoxins and Beyond; Redox Systems Regulating Lung Physiology and Disease

Significance: The lung is a unique organ, as it is constantly exposed to air, and thus it requires a robust antioxidant defense system to prevent the potential damage from exposure to an array of environmental insults, including oxidants. The peroxiredoxin (PRDX) family plays an important role in scavenging peroxides and is critical to the cellular antioxidant defense system. Recent Advances: Exciting discoveries have been made to highlight the key features of PRDXs that regulate the redox tone. PRDXs do not act in isolation as they require the thioredoxin/thioredoxin reductase/NADPH, sulfiredoxin (SRXN1) redox system, and in some cases glutaredoxin/glutathione, for their reduction. Furthermore, the chaperone function of PRDXs, controlled by the oxidation state, demonstrates the versatility in redox regulation and control of cellular biology exerted by this class of proteins. Critical Issues: Despite the long-known observations that redox perturbations accompany a number of pulmonary diseases, surprisingly little is known about the role of PRDXs in the etiology of these diseases. In this perspective, we review the studies that have been conducted thus far to address the roles of PRDXs in lung disease, or experimental models used to study these diseases. Intriguing findings, such as the secretion of PRDXs and the formation of autoantibodies, raise a number of questions about the pathways that regulate secretion, redox status, and immune response to PRDXs. Future Directions: Further understanding of the mechanisms by which individual PRDXs control lung inflammation, injury, repair, chronic remodeling, and cancer, and the importance of PRDX oxidation state, configuration, and client proteins that govern these processes is needed.

Eight potential biomarkers for distinguishing between lung adenocarcinoma and squamous cell carcinoma

Lung adenocarcinoma (LADC) and squamous cell carcinoma (LSCC) are the most common non-small cell lung cancer histological phenotypes. Accurate diagnosis distinguishing between these two lung cancer types has clinical significance. For this study, we analyzed four Gene Expression Omnibus (GEO) datasets (GSE28571, GSE37745, GSE43580, and GSE50081). We then imported the datasets into the Gene-Cloud of Biotechnology Information online platform to identify genes differentially expressed in LADC and LSCC. We identified DSG3 (desmoglein 3), KRT5 (keratin 5), KRT6A (keratin 6A), KRT6B (keratin 6B), NKX2-1 (NK2 homeobox 1), SFTA2 (surfactant associated 2), SFTA3 (surfactant associated 3), and TMC5 (transmembrane channel-like 5) as potential biomarkers for distinguishing between LADC and LSCC. Receiver operating characteristic curve analysis suggested that KRT5 had the highest diagnostic value for discriminating between these two cancer types. Using the PrognoScan online survival analysis tool and the Kaplan-Meier Plotter, we found that high KRT6A or KRT6B levels, or low NKX2-1, SFTA3, or TMC5 levels correlated with unfavorable prognoses in LADC patients. Further studies will be needed to verify our findings in additional patient samples, and to elucidate the mechanisms of action of these potential biomarkers in non-small cell lung cancer.

Serum tumor-associated autoantibodies as diagnostic biomarkers for lung cancer: A systematic review and meta-analysis

OBJECTIVE

We performed a comprehensive review and meta-analysis to evaluate the diagnostic values of serum single and multiplex tumor-associated autoantibodies (TAAbs) in patients with lung cancer (LC).

METHODS

We searched the MEDLINE and EMBASE databases for relevant studies investigating serum TAAbs for the diagnosis of LC. The primary outcomes included sensitivity, specificity and accuracy of the test.

RESULTS

The systematic review and meta-analysis included 31 articles with single autoantibody and 39 with multiplex autoantibodies. Enzyme-linked immunosorbent assay (ELISA) was the most common detection method. For the diagnosis of patients with all stages and early-stage LC, different single or combinations of TAAbs demonstrated different diagnostic values. Although individual TAAbs showed low diagnostic sensitivity, the combination of multiplex autoantibodies offered relatively high sensitivity. For the meta-analysis of a same panel of autoantibodies in patients at all stages of LC, the pooled results of the panel of 6 TAAbs (p53, NY-ESO-1, CAGE, GBU4-5, Annexin 1 and SOX2) were: sensitivity 38% (95% CI 0.35-0.40), specificity 89% (95% CI 0.86-0.91), diagnostic accuracy 65.9% (range 62.5-81.8%), AUC 0.52 (0.48-0.57), while the summary estimates of 7 TAAbs (p53, CAGE, NY-ESO-1, GBU4-5, SOX2, MAGE A4 and Hu-D) were: sensitivity 47% (95% CI 0.34-0.60), specificity 90% (95% CI 0.89-0.92), diagnostic accuracy 78.4% (range 67.5-88.8%), AUC 0.90 (0.87-0.93). For the meta-analysis of the same panel of autoantibodies in patients at early-stage of LC, the sensitivities of both panels of 7 TAAbs and 6 TAAbs were 40% and 29.7%, while their specificities were 91% and 87%, respectively.

CONCLUSIONS

Serum single or combinations of multiplex autoantibodies can be used as a tool for the diagnosis of LC patients at all stages or early-stage, but the combination of multiplex autoantibodies shows a higher detection capacity; the diagnostic value of the panel of 7 TAAbs is higher than the panel of 6 TAAbs, which may be used as potential biomarkers for the early detection of LC.

Roles of peroxiredoxins in cancer, neurodegenerative diseases and inflammatory diseases

Peroxiredoxins (PRDXs) are antioxidant enzymes, known to catalyze peroxide reduction to balance cellular hydrogen peroxide (H₂O₂) levels, which are essential for cell signaling and metabolism and act as a regulator of redox signaling. Redox signaling is a critical component of cell signaling pathways that are involved in the regulation of cell growth, metabolism, hormone signaling, immune regulation and variety of other physiological functions. Early studies demonstrated that PRDXs regulates cell growth, metabolism and immune regulation and therefore involved in the pathologic regulator or protectant of several cancers, neurodegenerative diseases and inflammatory diseases. Oxidative stress and antioxidant systems are important regulators of redox signaling regulated diseases. In addition, thiol-based redox systems through peroxiredoxins have been demonstrated to regulate several redox-dependent process related diseases. In this review article, we will discuss recent findings regarding PRDXs in the development of diseases and further discuss therapeutic approaches targeting PRDXs. Moreover, we will suggest that PRDXs could be targets of several diseases and the therapeutic agents for targeting PRDXs may have potential beneficial effects for the treatment of cancers, neurodegenerative diseases and inflammatory diseases. Future research should open new avenues for the design of novel therapeutic approaches targeting PRDXs.

Unveiling a novel biomarker panel for diagnosis and classification of well-differentiated thyroid carcinomas

Thyroid cancer is the most common human endocrine malignancy with increasing global incidence. Papillary thyroid carcinomas (PTC) and follicular thyroid carcinomas (FTC) are well-differentiated thyroid cancers (WDTC) accounting for 95% of all thyroid cancer cases, with survival rates of almost 100% when diagnosed early. Since PTC and FTC have different modes of metastasis, they require different treatment strategies. Standard diagnosis by fine needle aspiration with cytopathological examination can be inaccurate in approximately 10-30% of all cases and difficult to definitively classify as WDTC. Currently, there is no single or panel of biomarkers available for thyroid cancer diagnosis and classification. This study identified novel biomarkers for thyroid cancer diagnosis and classification using proteomics, which may be translated into a biomarker panel for clinical application. Two-dimensional SDS-PAGE and mass spectrometry were used to identify potential biomarkers in papillary and follicular thyroid carcinoma cell lines, and the biomarkers were validated in five PTC and five FTC tissues, with their adjacent normal tissues from Thai patients. Eight biomarkers could distinguish PTC from normal tissues, namely enolase 1, triose phosphate isomerase, cathepsin D, annexin A2, cofilin 1, proliferating cell nuclear antigen (PCNA), copine 1 and heat shock protein 27 kDa (HSP27). These biomarkers can also discriminate FTC from normal tissues, except for annexin A2. On the contrary, annexin A2, cofilin 1, PCNA and HSP27 can be used to classify the types of WDTC. These findings have potential for use as a novel multi-marker panel for more accurate diagnosis and classification to better guide physicians on thyroid cancer treatment. Moreover, our results suggest the involvement of proteins in cell growth and proliferation, and the p53 pathway in the carcinogenesis of WDTC, which may lead to targeted therapy for thyroid cancer.

High intensity of cytoplasmic peroxiredoxin VI expression is associated with adverse outcome in diffuse large B-cell lymphoma independently of International Prognostic Index

AIMS

Diffuse large B-cell lymphoma (DLBCL) is an aggressive and potentially fatal disease. Prediction of risk of relapse is based on clinical markers. There is a need for more accurate biomarkers to select patients for more aggressive first-line treatments. Peroxiredoxins (Prxs) are a family of potent antioxidant proteins. Their prognostic role in DLBCL is unknown.

METHODS

Altogether, 103 diagnostic biopsy samples from patients with DLBCL were immunohistochemically stained for Prxs I, II, III, V and VI.

RESULTS

Strong Prx VI expression was associated with the presence of B-symptoms. There were no other significant associations with traditional risk factors. Five-year disease-specific survival was 68.6% in patients with high cytoplasmic Prx VI intensity vs 97.0% in those with low intensity. In multivariate analysis, high Prx VI expression (HR 12.846, 95% CI 1.722 to 95.807, p=0.013) was an independent risk factor of lymphoma-associated death not related to International Prognostic Index score (HR 2.514, 95% CI 1.040 to 6.073, p=0.041).

CONCLUSIONS

High intensity of cytoplasmic Prx VI expression in pretreatment DLBCL samples predicts worse outcome in patients with DLBCL. Whether Prx VI is associated with chemoresistance, and therefore a poorer outcome, needs to be evaluated. If Prx VI is a predictive marker and it proves causality, it would be crucial to study Prx VI ability to become a target enzyme for treatment.

PRDX6 promotes tumor development via the JAK2/STAT3 pathway in a urethane-induced lung tumor model

Peroxiredoxin 6 (PRDX6) is a bifunctional protein with both glutathione peroxidase (GPx) and iPLA2 activities. Even though several pathophysiological functions have been studied, the definitive role of PRDX6 in tumor growth is not clear. Here, we compared carcinogen-induced tumor growth in PRDX6-transgenic (Tg) mice and non-Tg mice to evaluate the roles of PRDX6 in lung tumor development. Urethane (1g/kg)-induced tumor incidence in PRDX6-Tg mice was significantly higher compared to non-Tg mice. In the tumors of PRDX6-Tg mice, the activation of JAK2/STAT3 and STAT3 DNA binding were also increased, accompanied by increased GPx and iPLA2 activities. PRDX6 was colocalized with JAK2 in tumor tissues and lung cancer cells and also showed physical interaction with JAK2. We found that increasing levels of PRDX6 increase the activation of the JAK2/STAT3 pathway. Furthermore, PRDX6-Tg mice showed altered cytokine levels in the tumors, especially leading to increased CCL5 levels. We validated that the activation of JAK2 was also decreased in lung tumors of CCR5(-/-) mice, and CCL5 increased the JAK2/STAT3 pathway in the lung cancer cells. Thus, our findings suggest that PRDX6 promotes lung tumor development via its mediated and CCL5-associated activation of the JAK2/STAT3 pathway.

Quantitative variability of 342 plasma proteins in a human twin population

The degree and the origins of quantitative variability of most human plasma proteins are largely unknown. Because the twin study design provides a natural opportunity to estimate the relative contribution of heritability and environment to different traits in human population, we applied here the highly accurate and reproducible SWATH mass spectrometry technique to quantify 1,904 peptides defining 342 unique plasma proteins in 232 plasma samples collected longitudinally from pairs of monozygotic and dizygotic twins at intervals of 2–7 years, and proportioned the observed total quantitative variability to its root causes, genes, and environmental and longitudinal factors. The data indicate that different proteins show vastly different patterns of abundance variability among humans and that genetic control and longitudinal variation affect protein levels and biological processes to different degrees. The data further strongly suggest that the plasma concentrations of clinical biomarkers need to be calibrated against genetic and temporal factors. Moreover, we identified 13 cis-SNPs significantly influencing the level of specific plasma proteins. These results therefore have immediate implications for the effective design of blood-based biomarker studies.

Glycolysis, tumor metabolism, cancer growth and dissemination. A new pH-based etiopathogenic perspective and therapeutic approach to an old cancer question

Cancer cells acquire an unusual glycolytic behavior relative, to a large extent, to their intracellular alkaline pH (pHi). This effect is part of the metabolic alterations found in most, if not all, cancer cells to deal with unfavorable conditions, mainly hypoxia and low nutrient supply, in order to preserve its evolutionary trajectory with the production of lactate after ten steps of glycolysis. Thus, cancer cells reprogram their cellular metabolism in a way that gives them their evolutionary and thermodynamic advantage. Tumors exist within a highly heterogeneous microenvironment and cancer cells survive within any of the different habitats that lie within tumors thanks to the overexpression of different membrane-bound proton transporters. This creates a highly abnormal and selective proton reversal in cancer cells and tissues that is involved in local cancer growth and in the metastatic process. Because of this environmental heterogeneity, cancer cells within one part of the tumor may have a different genotype and phenotype than within another part. This phenomenon has frustrated the potential of single-target therapy of this type of reductionist therapeutic approach over the last decades. Here, we present a detailed biochemical framework on every step of tumor glycolysis and then proposea new paradigm and therapeutic strategy based upon the dynamics of the hydrogen ion in cancer cells and tissues in order to overcome the old paradigm of one enzyme-one target approach to cancer treatment. Finally, a new and integral explanation of the Warburg effect is advanced.

Identification of proteins with increased levels in ameloblastic carcinoma

PURPOSE

The comparative proteomic approach by a combination of 2-dimensional electrophoresis and matrix-assisted laser desorption-ionization-time of flight mass spectrometry (MS) analysis is an attractive strategy for the discovery of cancer biomarkers and therapeutic targets. The identification of protein biomarkers associated with ameloblastic carcinoma (AC), a malignant epithelial odontogenic tumor, will potentially improve the diagnostic and prognostic accuracy for this malignant neoplasm. The aim of the present study was to identify highly expressed proteins in AC that could be considered as potential biomarkers.

MATERIALS AND METHODS

The protein profile of an AC was compared with the protein profiles of 3 cases of benign ameloblastoma. Proteins that showed increased levels in AC were identified using MS, and the augmented amount of some of these proteins in the malignant lesion was confirmed by Western blot or immunohistochemistry.

RESULTS

We detected a total of 782 spots in the protein profile of AC, and 19 of them, showing elevated levels compared with benign ameloblastoma, were identified using MS. These proteins have been implicated in several cellular functions, such as cell structure, metabolism, stress response, and signal transduction.

CONCLUSIONS

The increased expression of the identified proteins and the minor expression of some proteins that might inhibit tumor progression could be involved in the evolution from a benign lesion to carcinoma.

Loss of presenilin 2 is associated with increased iPLA2 activity and lung tumor development

Presenilins are the enzymatic components of γ-secretase complex that cleaves amyloid precursor protein, Notch and β-catenin, which has critical roles in the development of Alzheimer's disease and cancer cell growth. Therefore, in the present study, we studied the effects and mechanisms of PS2 knockout on lung cancer development and possible mechanisms as a key regulator of lung tumor development. We compared carcinogen-induced tumor growth between PS2 knockout mice and wild-type mice. PS2 knockout mice showed increased urethane (1 mg/g)-induced lung tumor incidence when compared with that of wild-type mice with decreased activity of γ-secretase in the lung tumor tissues. Consequently, iPLA2 activities in lung tumor tissues of PS2 knockout mice were much higher than in tumor tissues of wild-type mice. Furthermore, knockdown of PS2 using PS2 siRNA decreased γ-secretase activity with increased iPLA2 activity in the lung cancer cells (A549 and NCI-H460), leading to increased lung cancer cell growth. PS2 knockout mice and PS2 knockdown lung cancer cells showed increased DNA-binding activities of nuclear factor kappa-beta, signal transducer and activator of transcription 3 (STAT3) and AP-1 which are critical transcriptional factors of iPLA2 than those of PS2 wild-type mice and control lung cancer cells. Taken together, these results suggest that the loss of PS2 could have a critical role in lung tumor development through the upregulation of iPLA2 activity by reducing γ-secretase.

Proteomics approaches for identification of tumor relevant protein targets in pulmonary squamous cell carcinoma by 2D-DIGE-MS

Potential markers for progression of pulmonary squamous cell carcinoma (SCC) were identified by examining samples of lung SCC and adjacent normal tissues using a combination of fluorescence two-dimensional difference gel electrophoresis (2D-DIGE), matrix-assisted laser desorption/ionization time of flight mass spectrometry (MALDI-TOF-MS), and electrospray ionization quadrupole-time of flight mass spectrometry (ESI-Q-TOF). The PANTHER System was used for gel image based quantification and statistical analysis. An analysis of proteomic data revealed that 323 protein spots showed significantly different levels of expression (P≤0.05) in lung SCC tissue compared to expression in normal lung tissue. A further analysis of these protein spots by MALDI-TOF-MS identified 81 different proteins. A systems biology approach was used to map these proteins to major pathways involved in numerous cellular processes, including localization, transport, cellular component organization, apoptosis, and reproduction. Additionally, the expression of several proteins in lung SCC and normal tissues was examined using immunohistochemistry and western blot. The functions of individual proteins are being further investigated and validated, and the results might provide new insights into the mechanism of lung SCC progression, potentially leading to the design of novel diagnostic and therapeutic strategies.

PRDX6 promotes lung tumor progression via its GPx and iPLA2 activities

PRDX6 is a bifunctional protein with both glutathione peroxidase (GPx) and calcium-independent phospholipase A2 (iPLA2) activities, which are concomitantly increased with the expression of PRDX6. PRDX6 promoted lung tumor growth in an in vivo allograft model. Herein, we further studied the vital roles in tumor progression of PRDX6 in lung cancer using nude mice bearing PRDX6-overexpressing lung cancer cells. Nude mice xenografted with PRDX6 showed increases in tumor size and weight compared to control mice. Histopathological and Western blotting examination demonstrated that expression of proliferating cell nuclear antigen, vascular endothelial growth factor, metalloproteinases 2 and 9, and cyclin-dependent kinases accompanied by increased iPLA2 and GPx activities were increased in the tumor tissues of PRDX6-overexpressing nude mice. In tumor tissues of PRDX6-overexpressing mice, the activation of mitogen-activated protein kinases and AP-1 DNA binding were also increased. The growth of lung cancer cell lines (A549 and NCI-H460) was enhanced by the increase in iPLA2 and GPx activities of PRDX6. In addition, mutant PRDX6 (C47S) attenuated PRDX6-mediated p38, ERK1/2, and AP-1 activities as well as its enzyme activities in the A549 and NCI-H460 lines. Furthermore, tumor growth and p38, ERK1/2, and AP-1 activities were also inhibited in nude mice bearing mutant PRDX6 (C47S) compared to PRDX6. Therefore, our findings indicate that PRDX6 promotes lung tumor growth via increased glutathione peroxidase and iPLA2 activities.

Anti-cancer effect of thiacremonone through down regulation of peroxiredoxin 6

Thiacremonone (2, 4-dihydroxy-2, 5-dimethyl-thiophene-3-one) is an antioxidant substance as a novel sulfur compound generated from High-Temperature-High-Pressure-treated garlic. Peroxiredoxin 6 (PRDX6) is a member of peroxidases, and has glutathione peroxidase and calcium-independent phospholipase A2 (iPLA2) activities. Several studies have demonstrated that PRDX6 stimulates lung cancer cell growth via an increase of glutathione peroxidase activity. A docking model study and pull down assay showed that thiacremonone completely fits on the active site (cys-47) of glutathione peroxidase of PRDX6 and interacts with PRDX6. Thus, we investigated whether thiacremonone inhibits cell growth by blocking glutathione peroxidase of PRDX6 in the human lung cancer cells, A549 and NCI-H460. Thiacremonone (0-50 μg/ml) inhibited lung cancer cell growth in a concentration dependent manner through induction of apoptotic cell death accompanied by induction of cleaved caspase-3, -8, -9, Bax, p21 and p53, but decrease of xIAP, cIAP and Bcl2 expression. Thiacremonone further inhibited glutathione peroxidase activity in lung cancer cells. However, the cell growth inhibitory effect of thiacremonone was not observed in the lung cancer cells transfected with mutant PRDX6 (C47S) and in the presence of dithiothreitol and glutathione. In an allograft in vivo model, thiacremonone (30 mg/kg) also inhibited tumor growth accompanied with the reduction of PRDX6 expression and glutathione peroxidase activity, but increased expression of cleaved caspase-3, -8, -9, Bax, p21 and p53. These data indicate that thiacremonone inhibits tumor growth via inhibition of glutathione peroxidase activity of PRDX6 through interaction. These data suggest that thiacremonone may have potentially beneficial effects in lung cancer.

iTRAQ-based proteomics reveals novel biomarkers of osteoarthritis

Objective:

We performed comprehensive proteomic analyses of articular cartilage by using the isobaric tags for relative and absolute quantitation (iTRAQ) method, and searched for candidate biomarkers for osteoarthritis (OA).

Methods:

Articular cartilage was collected from patients with OA or femoral neck fracture for the control group. Molecular variations were detected by the iTRAQ method, and quantitative analyses were performed by western blot.

Results:

Using the iTRAQ method, we identified 76 proteins with different expression levels in OA patients and the control group. Among these proteins, we selected LECT2 (leukocyte cell-derived chemotaxin-2), BAALC (brain and acute leukemia, cytoplasmic), and PRDX6 (peroxiredoxin-6), which had not been reported as biomarkers for OA.

Conclusions:

Use of these proteins in combination with conventional OA biomarkers may better reflect the grade and prognosis of OA.

Lung tumor growth-promoting function of peroxiredoxin 6

This study compared lung tumor growth in PRDX6-overexpressing transgenic (Tg) mice and normal mice. These mice expressed elevated levels of PRDX6 mRNA and protein in multiple tissues. In vivo, Tg mice displayed a greater increase in the growth of lung tumor compared with normal mice. Glutathione peroxidase and calcium-independent phospholipase 2 (iPLA2) activities in tumor tissues of Tg mice were much higher than in tumor tissues of normal mice. Higher tumor growth in PRDX6-overexpressing Tg mice was associated with an increase in activating protein-1 (AP-1) DNA-binding activity. Moreover, expression of proliferating cell nuclear antigen, Ki67, vascular endothelial growth factor, c-Jun, c-Fos, metalloproteinase-9, cyclin-dependent kinases, and cyclins was much higher in the tumor tissues of PRDX6-overexpressing Tg mice than in tumor tissues of normal mice. However, the expression of apoptotic regulatory proteins including caspase-3 and Bax was slightly less in the tumor tissues of normal mice. In tumor tissues of PRDX6-overexpressing Tg mice, activation of mitogen-activated protein kinases (MAPKs) was much higher than in normal mice. In cultured lung cancer cells, PRDX6 siRNA suppressed glutathione peroxidase and iPLA2 activities and cancer cell growth, but the enforced overexpression of PRDX6 increased cancer cell growth associated with their increased activities. In vitro, among the tested MAPK inhibitors, c-Jun NH2-terminal kinase (JNK) inhibitor clearly suppressed the growth of lung cancer cells and AP-1 DNA binding, glutathione peroxidase activity, and iPLA2 activity in normal and PRDX6-overexpressing lung cancer cells. These data indicate that overexpression of PRDX6 promotes lung tumor growth via increased glutathione peroxidase and iPLA2 activities through the upregulation of the AP-1 and JNK pathways.

Implications for oxidative stress and astrocytes following 26S proteasomal depletion in mouse forebrain neurones

Neurodegenerative diseases are characterized by progressive degeneration of selective neurones in the nervous system, but the underlying mechanisms involved in neuroprotection and neurodegeneration remain unclear. Dysfunction of the ubiquitin proteasome system is one of the proposed hypotheses for the cause and progression of neuronal loss. We have performed quantitative two-dimensional fluorescence difference in-gel electrophoresis combined with peptide mass fingerprinting to reveal proteome changes associated with neurodegeneration following 26S proteasomal depletion in mouse forebrain neurones. Differentially expressed proteins were validated by Western blotting, biochemical assays and immunohistochemistry. Of significance was increased expression of the antioxidant enzyme peroxiredoxin 6 (PRDX6) in astrocytes, associated with oxidative stress. Interestingly, PRDX6 is a bifunctional enzyme with antioxidant peroxidase and phospholipase A2 (PLA2) activities. The PLA2 activity of PRDX6 was also increased following 26S proteasomal depletion and may be involved in neuroprotective or neurodegenerative mechanisms. This is the first in vivo report of oxidative stress caused directly by neuronal proteasome dysfunction in the mammalian brain. The results contribute to understanding neuronal-glial interactions in disease pathogenesis, provide an in vivo link between prominent disease hypotheses and importantly, are of relevance to a heterogeneous spectrum of neurodegenerative diseases.

Differential protein analysis of lymphocytes between children with acute lymphoblastic leukemia and healthy children

We identified differential proteins in lymphocytes between patients with childhood acute lymphoblastic leukemia (c-ALL) and healthy children. Samples of bone marrow lymphocytes from children with c-ALL and peripheral blood lymphocytes from healthy children were collected, and total proteins were extracted and separated from these samples followed by two-dimensional gel electrophoresis for comparative analysis. The differential protein spots in c-ALL cells were digested in situ, and then analyzed with matrix-assisted laser desorption ionization/time of flight mass spectrometry (MALDI-TOF-MS) followed by identification using the relevant database. Fifteen differential expression proteins were obtained by comparative proteomics analysis. Of the 15 differential proteins, eight were identified. Of the eight proteins, two had high expression and six low expression in c-ALL cells. The eight differential proteins are expected to become new diagnostic markers and drug targets for c-ALL.

Comparative proteomic analysis of ductal breast carcinoma demonstrates an altered expression of chaperonins and cytoskeletal proteins

The aim of the present study was to analyze the protein composition of ductal breast carcinoma and the surrounding normal tissue in individual patients using comparative 2D proteomics and mass spectrometry to detect candidate disease biomarkers for diagnosis and prognosis. Samples of normal and cancerous tissue obtained form 28 patients were analyzed. Chaperonins and cytoskeletal proteins predominated among the 11 proteins for which major changes in abundance were detected. Of these 11 proteins with an altered expression, 2 had a decreased expression and 9 had an increased expression. In addition, the abundance of a few cytokeratins was also altered; however, they were not capable of serving as specific circulatory biomarkers. The proteins which we observed to exhibit an altered expression in infiltrating ductal breast carcinoma may be exploited as novel targets for therapeutic interventions or represent novel diagnostic/prognostic markers for the early detection of aggressive tumors, particularly those with multridrug-resistant phenotypes during the earlier stages of the disease.

Risk assessment, disease prevention and personalised treatments in breast cancer: is clinically qualified integrative approach in the horizon?

Breast cancer is a multifactorial disease. A spectrum of internal and external factors contributes to the disease promotion such as a genetic predisposition, chronic inflammatory processes, exposure to toxic compounds, abundant stress factors, a shift-worker job, etc. The cumulative effects lead to high incidence of breast cancer in populations worldwide. Breast cancer in the USA is currently registered with the highest incidence rates amongst all cancer related patient cohorts. Currently applied diagnostic approaches are frequently unable to recognise early stages in tumour development that impairs individual outcomes. Early diagnosis has been demonstrated to be highly beneficial for significantly enhanced therapy efficacy and possibly full recovery. Actual paper shows that the elaboration of an integrative diagnostic approach combining several levels of examinations creates a robust platform for the reliable risk assessment, targeted preventive measures and more effective treatments tailored to the person in the overall task of breast cancer management. The levels of examinations are proposed, and innovative technological approaches are described in the paper. The absolute necessity to create individual patient profiles and extended medical records is justified for the utilising by routine medical services. Expert recommendations are provided to promote further developments in the field.

Identification of candidate biomarkers for early detection of human lung squamous cell cancer by quantitative proteomics

To discover novel biomarkers for early detection of human lung squamous cell cancer (LSCC) and explore possible mechanisms of LSCC carcinogenesis, iTRAQ-tagging combined with two dimensional liquid chromatography tandem MS analysis was used to identify differentially expressed proteins in human bronchial epithelial carcinogenic process using laser capture microdissection-purified normal bronchial epithelium (NBE), squamous metaplasia (SM), atypical hyperplasia (AH), carcinoma in situ (CIS) and invasive LSCC. As a result, 102 differentially expressed proteins were identified, and three differential proteins (GSTP1, HSPB1 and CKB) showing progressively expressional changes in the carcinogenic process were selectively validated by Western blotting. Immunohistochemistry was performed to detect the expression of the three proteins in an independent set of paraffin-embedded archival specimens including various stage tissues of bronchial epithelial carcinogenesis, and their ability for early detection of LSCC was evaluated by receiver operating characteristic analysis. The results showed that the combination of the three proteins could perfectly discriminate NBE from preneoplastic lesions (SM, AH and CIS) from invasive LSCC, achieving a sensitivity of 96% and a specificity of 92% in discriminating NBE from preneoplatic lesions, a sensitivity of 100% and a specificity of 98% in discriminating NBE from invasive LSCC, and a sensitivity of 92% and a specificity of 91% in discriminating preneoplastic lesions from invasive LSCC, respectively. Furthermore, we knocked down GSTP1 in immortalized human bronchial epithelial cell line 16HBE cells, and then measured their susceptibility to carcinogen benzo(a)pyrene-induced cell transformation. The results showed that GSTP1 knockdown significantly increased the efficiency of benzo(a)pyrene-induced 16HBE cell transformation. The present data first time show that GSTP1, HSPB1 and CKB are novel potential biomarkers for early detection of LSCC, and GSTP1 down-regulation is involved in human bronchial epithelial carcinogenesis.

Polymorphisms of peroxiredoxin 1, 2 and 6 are not associated with esophageal cancer

PURPOSE

Peroxiredoxins, which reduced intracellular peroxides as a noval kind of antioxidant protein, were extensively expressed in various types of cancers and were thought as a biomarker of cancer cells. In this work, we performed genotyping analyses for tag SNP of Prdx 1, 2 and 6, and then evaluated the association with susceptibility and clinic stage of esophageal squamous cell carcinoma (ESCC) in a case-control study.

METHODS

The protein level of these Prdx isoforms in ESCC cancer samples was evaluated by Western blot. Then 356 ESCC cancer cases and 315 controls were genotyped by SNPshot assay. Differences in frequencies of the genotypes of the SNPs variant between the cases and controls were evaluated by using the chi-square test.

RESULTS

Our result of Western blot confirmed the aberrant expression of Prdx 1, 2 and 6 in ESCC samples, which was coincident with other studies. After genotyping by SNPshot assay, the result showed that the allele and genotype frequencies did not differ between the patients and controls. And no association between the polymorphism and the progression of ESCC including tumor grade and stage was found.

CONCLUSIONS

Our data suggested that polymorphisms of Prdx 1, 2 and 6 were not associated with esophageal cancer.

Enhancement of a multianalyte serum biomarker panel to identify lymph node metastases in non-small cell lung cancer with circulating autoantibody biomarkers

We recently reported the development of a multianalyte serum algorithm to identify nodal status in non-small cell lung cancer (NSCLC) patients facing an anatomic resection with curative intent. This study aims to enhance the overall performance characteristics of this test by adding autoantibody biomarkers identified through immunoproteomic discovery. More specifically, we used sera from 20 NSCLC patients to probe 2-D immunoblots of HCC827 lysates for tumor-associated autoantigens. Relevant differences in immunoreactivity associated with pathological nodal status were then identified via tandem mass spectrometry. Identified autoantigens were then developed into Luminex immunobead assays alongside a series of autoantigen targets relevant to early-disease detection. These assays were then used to measure circulating autoantibody levels in the identical cohort of NSCLC patients used in our original study. This strategy identified 11 autoantigens found primarily in patients with disease progression to the locoregional lymph nodes. Custom Luminex-based "direct-capture" assays (25 total; including autoantibody targets relevant to early-disease detection) were assembled to measure autoantibody levels in sera from 107 NSCLC patients. Multivariate classification algorithms were then used to identify the optimal combination of biomarkers when considered collectively with our original 6-analyte serum panel. The new algorithm resulting from this analysis consists of TNF-α, TNF-RI, MIP-1α and autoantibodies against Ubiquilin-1, hydroxysteroid-(17-β)-dehydrogenase, and triosephosphate isomerase. The inclusion of autoantibody biomarkers provided a dramatic improvement in the overall test performance characteristics, relative to the original test panel, including an 11% improvement in the classification efficiency.