Assessment of inhalation exposure to microplastic particles when disposable masks are repeatedly used

Wearing masks to prevent infectious diseases, especially during the COVID-19 pandemic, is common. However, concerns arise about inhalation exposure to microplastics (MPs) when disposable masks are improperly reused. In this study, we assessed whether disposable masks release inhalable MPs when reused in simulated wearing conditions. All experiments were conducted using a controlled test chamber setup with a constant inspiratory flow. Commercially available medical masks with a three-layer material, composition comprising polypropylene (PP in the outer and middle layers) and polyethylene (PE in the inner layer), were used as the test material. Brand-new masks with and without hand rubbing, as well as reused medical masks, were tested. Physical properties (number, size, and shape) and chemical composition (polymers) were identified using various analytical techniques such as fluorescence staining, fluorescence microscopy, and micro-Fourier Transform Infrared Spectroscopy (μFTIR). Scanning Electron Microscopy (SEM) was used to scrutinize the surface structure of reused masks across different layers, elucidating the mechanism behind the MP generation. The findings revealed that brand-new masks subjected to hand rubbing exhibited a higher cumulative count of MPs, averaging approximately 1.5 times more than those without hand rubbing. Fragments remained the predominant shape across all selected size classes among the released MPs from reused masks, primarily through a physical abrasion mechanism, accounting for >90 % of the total MPs. The numbers of PE particles were higher than PP particles, indicating that the inner layer of the mask contributed more inhalable MPs than the middle and outer layers combined. The released MPs from reused masks reached their peak after 8 h of wearing. This implies that regularly replacing masks serves as a preventive measure and mitigates associated health risks of inhalation exposure to MPs.

Links between oral microbiome and insulin resistance: Involvement of MAP kinase signaling pathway

Oral dysbiosis contributes to periodontitis and has implications for systemic diseases. Diabetes mellitus is a common metabolic disorder characterized by impaired glucose regulation. AMP-activated protein kinase (AMPK) plays a vital role in regulating glucose uptake and glycogenesis in the liver. This study aimed to investigate the association between periodontal bacteria and diabetes mellitus. A clinical trial was conducted to explore the association between oral bacteria and hyperglycemia. Additionally, we elucidated the molecular mechanisms by which periodontal bacteria cause insulin resistance. In the clinical trial, we discovered significant alterations in the expression levels of Fusobacterium nucleatum (Fn) and Tannerella forsythia (Tf) in patients with diabetes compared with healthy controls. Furthermore, Fn and Tf levels positively correlated with fasting blood glucose and glycated hemoglobin (HbA1C) levels. Moreover, we explored and elucidated the molecular mechanism by which Fusobacterium nucleatum culture filtrate (FNCF) induces cytokine release via the Toll-like receptor 2 (TLR2) signaling pathway in human gingival epithelial Smulow-Glickman (S-G) cells. This study investigated the effects of cytokines on insulin resistance pathways in liver cells. The use of an extracellular signal-regulated kinase (ERK) inhibitor (U0126) demonstrated that FNCF regulates the insulin receptor substrate 1 and protein kinase B (IRS1/AKT) signaling pathway, which affects key proteins involved in hepatic glycogen synthesis, including glycogen synthase kinase-3 beta (GSK3β) and glycogen synthase (GS), ultimately leading to insulin resistance. These findings suggest that ERK plays a crucial role in hepatocyte insulin resistance.

Sediment pollutant exposures caused hepatotoxicity and disturbed glycogenesis

Liver metabolic syndrome, which involves impaired hepatic glycogen synthesis, is persistently increased by exposure to environmental pollutants. Most studies have investigated the pathogenesis of liver damage caused by single metal species or pure organics. However, under normal circumstances, the pollutants that we are exposed to are usually chemical mixtures that accumulate over time. Sediments are long-term repositories for environmental pollutants due to their environmental cycles, which make them good samples for evaluating the effect of environmental pollutants on the liver via bioaccumulation. This study aimed to clarify the effects of sediment pollutants on liver damage. Our results indicate that industrial wastewater sediment (downstream) is more cytotoxic than sediments from other zones. Downstream sediment extract (DSE) causes hepatotoxicity, stimulates reactive oxygen species (ROS) generation, triggers mitochondrial dysfunction, induces cell apoptosis, and results in the release of glutamic oxaloacetic transaminase (GOT) and glutamic pyruvic transaminase (GPT) proteins. Additionally, to elucidate the underlying mechanism by which sediment pollutants disturb hepatic glycogen synthesis, we investigated the effects of different sediment samples from different pollution situations on glycogen synthesis in liver cell lines. It was found that DSE induced multiple severe impairments in liver cells, and disturbed glycogen synthesis more than under other conditions. These impairments include decreased hepatic glycogen synthesis via inhibition and insulin receptor substrate 1 (IRS-1) /AKT /glycogen synthase kinase3β (GSK3β)-mediated glycogen synthase (GYS) inactivation. To our knowledge, this study provides the first detailed evidence of in vitro sediment-accumulated toxicity that interferes with liver glycogen synthesis, leading to hepatic cell damage through apoptosis.

Fecal Protein Analysis of Dusp6 Knockout C57BL/6J Mice by Metaproteomics

The research of obesity and gut microbiota has been carried out for years, yet the study process was in a slow pace for several challenges to conquer. As a complex status of disorder, the contributing factors refer to gut microbiota about obesity were controversial in a wide range. In terms of proteomics, 2D-DIGE technology is a powerful method for this study to identify fecal proteins from lean microbiota in Dusp6 knockout C57BL/6J mice, exploring the protein markers of the ability resisting to diet-induced obesity (DIO) transferred to the host mice after fecal microbiota transplantation. The results showed that the fecal microbiota expressed 289 proteins differentially with 23 proteins identified, which were considered to be the reasons to assist the microbiota exhibiting distinct behavior. By means of proteomics technology, we had found that differentially expressed proteins of lean microbiota determined the lean microbial behavior might be able to resist leaky gut. To sum up our study, the proteomics strategies offered as a tool to demonstrate and analyze the features of lean microbiota, providing new speculations in the behavior about the gut microbiota reacting to DIO.

Proteomic analysis of tumor-specific biomarkers in colon cancer

Background:

With the development of medicine and technological advancement, the concept of precision medicine is rising, and the traditional principle of all-in-one therapy is gradually broken. Utilizing the detection of genome, transcriptome, proteome, and metabolome, combined with big data analysis to discover new pathogenic mechanisms, provide more effective prescriptions with fewer side effects, and even shift the emphasis of medicine from disease treatment to disease prevention.

Methods:

Proteomics is one of the potential tools for monitoring the alternations of protein expression. This study analyzed the proteomic alternations between normal colon tissue and cancerous colon tissue via two-dimensional difference gel electrophoresis (2D-DIGE) and matrix-assisted laser desorption/ionization-time of flight mass spectrometry (MALDI-TOF MS) to select the potential target proteins.

Results:

The experimental results demonstrated that a total of 90 proteins were identified with significantly expressed. These proteins were classified according to their functions. These proteins are mainly associated with cytoskeleton regulation, glycolysis, and protein folding. Furthermore, immunoblotting was used to verify the differentially expressed proteins, and the results showed positive agreement with the trends in the proteomic analysis.

Conclusion:

To sum up, these differentially expressed proteins could be used as potential and precise biomarkers in the diagnosis or treatment of colorectal cancer.

Urban sediment pollutants alternate human cell essential behaviour through promoting oxidative damage

The main objective of this study was to establish a human cell-based platform to assess the effects of sediment toxicity on oxidative damage and cell essential behaviour. Since sediment pollution has increased as a consequence of including but not limited to industrialisation, the contaminants accumulated in sediments have already led to human health concerns. The Hsinchu Science Park is one of the most prominent semiconductor manufacturing centres in the world, and the Ke-Ya River flows through Hsinchu Science Park and the Hsinchu urban district. Because semiconductor wastes potentially contribute to higher-than-normal rates of cancers, birth defects, and serious diseases, the quality assessment of the Ke-Ya River has prompted widespread concerns. While previous studies have shown an association between the degradation of fish populations and sediment pollutants, very little is known about the issues on human health. Herein, the effects of sediment from three sediment sampling sites of the Ke-Ya River on 11 different human cell lines were directly evaluated. The upstream represents the undeveloped zone, the middle-stream represents the household/industrial wastewater zone, and the downstream represents the accumulation zone. Our results indicated that the sediment pollution of the downstream Ke-Ya River was more cytotoxic than that of the middle stream and upstream. Downstream sediment extract (DSE) significantly increased reactive oxygen species (ROS) levels across all cell types. Accordingly, oxidative stress can trigger redox-sensitive pathways and alter essential biological processes such as cell viability, cell adhesion, and cell motility. Importantly, the MTT assay indicated that DSE significantly decreased the viability of brain, oral, lung, breast, liver, pancreatic, cervical, prostate, and colorectal cells. Furthermore, the adhesive ability and wound healing ability of most cells were greatly reduced in the presence of DSE compared to other conditions. Thus, this study shows the results of the first analyses completed on the sediment cytotoxicity in human cells, and stimulated ROS levels are crucial for cellular life. In future research, the detailed cause and effect mechanisms of the abundant ROS generated in DSE will be further investigated. We sincerely hope that our study provides a scientific basis for further investigations with a global perspective on public health challenges.

Proteomic and microbial assessments on the effect of Antrodia cinnamomea in C57BL/6 mice

Antrodia cinnamomea (AC) is a nutraceutical fungus and studies have suggested that AC has the potential to prevent or alleviate diseases. However, little is known about the AC-induced phenotypes on the intestine-liver axis and gut microbial alterations. Here, we performed two-dimensional difference gel electrophoresis (2D-DIGE) and MALDI-Biotyper to elaborate the AC-induced phenotypes on the intestine-liver axis and gut microbial distribution of C57BL/6 mice. The experimental outcomes showed that the hepatic density may increase by elevating hepatic redox regulation, lipid degradation and glycolysis-related proteins and alleviating cholesterol biosynthesis and transport-related proteins in C57BL/6 mice with AC treatment. Moreover, AC facilitates intestinal glycolysis, TCA cycle, redox and cytoskeleton regulation-related proteins, but also reduces intestinal vesicle transport-related proteins in C57BL/6 mice. However, the body weight, GTT, daily food/water intake, and fecal/urine weight were unaffected by AC supplementation in C57BL/6 mice. Notably, the C57BL/6-AC mice had a higher gut microbial abundance of Alistipes shahii (AS) than C57BL/6-Ctrl mice. In summary, the AC treatment affects intestinal permeability by regulating redox and cytoskeleton-related proteins and elevates the gut microbial abundance of AS in C57BL/6 mice that might be associated with increasing hepatic density and metabolism-related proteins of the liver in C57BL/6 mice. Our study provides an insight into the mechanisms of AC-induced phenotypes and a comprehensive assessment of AC's nutraceutical effect in C57BL/6 mice.

Biomarker discovery in highly invasive lung cancer cell through proteomics approaches

Lung cancer is one of the leading causes of cancer-related death worldwide. The most common type of lung cancer is non-small cell lung cancer (NSCLC). When NSCLC is detected, patients are typically already in a metastatic stage. Metastasized cancer is a major obstacle of effective treatment and understanding the mechanisms underlying metastasis is critical to treat cancer. Herein, we selected an invasive subpopulation from the human lung cancer cell line A549 using the transwell system and named it as A549-I5. Invasive and migratory activities of this cell line were analysed using wound healing, invasion, and migration assays. In addition, epithelial-mesenchymal transition (EMT) markers, such as Snail 1, Twist, Vimentin, N-cadherin and E-cadherin, were assessed through immunoblotting. In comparison to A549 cells, the invasive A549-I5 lung cancer cells had enhanced invasiveness, motility and EMT marker expression. Proteomic analysis identified 83 significantly differentially expressed proteins in A549-I5 cells. These identified proteins were classified according to their cellular functions and most were involved in cytoskeleton, redox regulation, protein degradation and protein folding. In summary, our results provide potential diagnostic markers and therapeutic candidates for the treatment of NSCLC metastasis. SIGNIFICANCE OF THE STUDY: When NSCLC is detected, most patients are already in a metastatic stage. Herein, we selected an invasive subpopulation from a human lung cancer cell line which had increased EMT markers as well as high wound healing, invasion and migration abilities. Proteomic analysis identified numerous proteins associated with functions in cytoskeleton, redox regulation, protein degradation and protein folding that were differentially expressed in these cells. These results may provide potential diagnostic markers and therapeutic candidates for the treatment of NSCLC metastasis.

The distribution of cultivable oral anaerobic microbiota identified by MALDI-TOF MS in healthy subjects and in patients with periodontal disease

In this study, we aimed to identify the cultivatable oral anaerobic bacterial distribution in oral cavity by MALDI-TOF Biotyper. The bacterial distribution of three groups, including subjects with/without periodontal disease, two clusters of age (60 years as the cutoff), and before/after treatment, were investigated in this study. There were 38 participants recruited in this study, involving 18 subjects with moderate to severe periodontal-infected patients and 20 healthy controls. Total number of 126 bacterial species were identified by MALDI-TOF MS. The relative abundance of Streptococcus gordonii and Streptococcus intermedius in periodontal patients is higher than healthy controls indicating potential biomarkers for periodontal disease. Participants with periodontal disease were subdivided in to two clusters of age (60 years as the cutoff), 11 and 7 participants were age <60 years and>60 years, respectively. Meanwhile, the incidence of Streptococcus pneumoniae and Streptococcus oralis infection were higher in the subjects above 60 years old than below. Moreover, the bacterial distribution between pre-treatment and post-treatment was similar indicating that basic treatment without the ability to redistribute the microbiota. In summary, the cultivable oral anaerobic bacteria were identified by MALDI-TOF MS and the bacterial distribution shifting was shown to be associated with the progress of periodontal disease to aging and basic treatment. This study provided information for diagnosis and treatment guidelines for oral healthcare.

Targeting UDP-glucose dehydrogenase inhibits ovarian cancer growth and metastasis

More than 70% of patients with ovarian cancer are diagnosed in advanced stages. Therefore, it is urgent to identify a promising prognostic marker and understand the mechanism of ovarian cancer metastasis development. By using proteomics approaches, we found that UDP-glucose dehydrogenase (UGDH) was up-regulated in highly metastatic ovarian cancer TOV21G cells, characterized by high invasiveness (TOV21G^HI ), in comparison to its parental control. Previous reports demonstrated that UGDH is involved in cell migration, but its specific role in cancer metastasis remains unclear. By performing immunohistochemical staining with tissue microarray, we found overexpression of UGDH in ovarian cancer tissue, but not in normal adjacent tissue. Silencing using RNA interference (RNAi) was utilized to knockdown UGDH, which resulted in a significant decrease in metastatic ability in transwell migration, transwell invasion and wound healing assays. The knockdown of UGDH caused cell cycle arrest in the G₀ /G₁ phase and induced a massive decrease of tumour formation rate in vivo. Our data showed that UGDH-depletion led to the down-regulation of epithelial-mesenchymal transition (EMT)-related markers as well as MMP2, and inactivation of the ERK/MAPK pathway. In conclusion, we found that the up-regulation of UGDH is related to ovarian cancer metastasis and the deficiency of UGDH leads to the decrease of cell migration, cell invasion, wound healing and cell proliferation ability. Our findings reveal that UGDH can serve as a prognostic marker and that the inhibition of UGDH is a promising strategy for ovarian cancer treatment.

The Role of Transforming Growth Factor-Beta in Retinal Ganglion Cells with Hyperglycemia and Oxidative Stress

A characteristic of diabetes mellitus is hyperglycemia, which is considered with an emphasis on the diabetic retinopathy of progressive neurodegenerative disease. Retinal ganglion cells (RGCs) are believed to be important cells affected in the pathogenesis of diabetic retinopathy. Transforming growth factor-beta (TGF-β) is a neuroprotective protein that helps to withstand various neuronal injuries. To investigate the potential roles and regulatory mechanisms of TGF-β in hyperglycemia-triggered damage of RGCs in vitro, we established RGCs in 5.5, 25, 50, and 100 mM D-glucose supplemented media and focused on the TGF-β-related oxidative stress pathway in combination with hydrogen peroxide (H₂O₂). Functional experiments showed that TGF-β1/2 protein expression was upregulated in RGCs with hyperglycemia. The knockdown of TGF-β enhanced the accumulation of reactive oxygen species (ROS), inhibited the cell proliferation rate, and reduced glutathione content in hyperglycemia. Furthermore, the results showed that the TGF-β-mediated enhancement of antioxidant signaling was correlated with the activation of stress response proteins and the antioxidant pathway, such as aldehyde dehydrogenase 3A1 (ALDH3A1), heme oxygenase-1 (HO-1), nuclear factor erythroid 2-related factor (Nrf2), and hypoxia-inducible factor (HIF-1α). Summarizing, our results demonstrated that TGF-β keeps RGCs from hyperglycemia-triggered harm by promoting the activation of the antioxidant pathway, suggesting a potential anti-diabetic therapy for the treatment of diabetic retinopathy.

Progesterone receptor membrane component 1 is involved in oral cancer cell metastasis

Cancer metastasis is a common cause of failure in cancer therapy. However, over 60% of oral cancer patients present with advanced stage disease, and the five‐year survival rates of these patients decrease from 72.6% to 20% as the stage becomes more advanced. In order to manage oral cancer, identification of metastasis biomarker and mechanism is critical. In this study, we use a pair of oral squamous cell carcinoma lines, OC3, and invasive OC3‐I5 as a model system to examine invasive mechanism and to identify potential therapeutic targets. We used two‐dimensional differential gel electrophoresis (2D‐DIGE) and matrix‐assisted laser desorption ionization time‐of‐flight mass spectrometry (MALDI‐TOF/TOF MS) to examine the global protein expression changes between OC3 and invasive OC3‐I5. A proteomic study reveals that invasive properties alter the expression of 101 proteins in OC3‐I5 cells comparing to OC3 cells. Further studies have used RNA interference technique to monitor the influence of progesterone receptor membrane component 1 (PGRMC1) protein in invasion and evaluate their potency in regulating invasion and the mechanism it involved. The results demonstrated that expression of epithelial‐mesenchymal transition (EMT) markers including Twist, p‐Src, Snail1, SIP1, JAM‐A, vimentin and vinculin was increased in OC3‐I5 compared to OC3 cells, whereas E‐cadherin expression was decreased in the OC3‐I5 cells. Moreover, in mouse model, PGRMC1 is shown to affect not only migration and invasion but also metastasis in vivo. Taken together, the proteomic approach allows us to identify numerous proteins, including PGRMC1, involved in invasion mechanism. Our results provide useful diagnostic markers and therapeutic candidates for the treatment of oral cancer invasion.

Proteomic Analysis of Metastasis-Specific Biomarkers in Pancreatic Cancer: Galectin-1 Plays an Important Metastatic Role in Pancreatic Cancer

Cancer metastasis is the major cause of death in pancreatic cancer. We have established a pair of pancreatic ductal adenocarcinoma cell line, PANC1 and invasive PANC1-I5, as a model system toinvestigate the metastatic mechanism as well as potential therapeutic targets in pancreatic cancer. We used proteomic analysis based on two-dimensional differential gel electrophoresis (2D-DIGE) and matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS) to examine the global protein expression alterations between PANC1 and PANC1-I5. Proteomic study revealed that 88 proteins are differentially expressed between PANC1-I5 and PANC1 cells, and further functional evaluations through protein expression validation, gene knockout, migration and invasion analysis revealed that galectin-1 is one of the potential players in modulating pancreatic cancer metastasis. To conclude, we have identified numerous proteins might be associated with pancreatic cancer invasiveness in the pancreatic cancer model.

Role of PGRMC1 in cell physiology of cervical cancer

AIMS

The most frequent cancers among women worldwide. The mortality of cervical cancer has declined significantly primarily due to the widespread use of Pap smear tests as a screening test and therapeutic vaccination. However, cervical cancer still remains a severe disease among the female population, as the prognosis of metastatic cervical cancer is very poor.

KEY METHODS

In this study, we performed 2D-DIGE and MALDI-TOF/TOF MS to analyze differentially expressed proteins between HeLa and invasive HeLa-I5 cells..

KEY FINDINGS

According to our proteomics data, 68 differentially expressed proteins between the HeLa and HeLa-I5 cells were identified. One of these differentially expressed proteins, Progesterone receptor membrane component 1 (PGRMC1), was selected as a candidate for further studies. To correlate the role of PGRMC1 with cellular migration and cancer progression, small interfering RNA (siRNA) was used to knockdown the expression of PGRMC1. Similar function of PGRMC1 was also observed in two other cervical cancer lines, CaSki and ME-180.

SIGNIFICANCE

PGRMC1 plays an essential role in regulating cancer progression and metastasis of cervical cancer cells, thus serving as a potential therapeutic target for cervical cancer.

Upregulation of LGALS1 is associated with oral cancer metastasis

Background

Oral cancer metastasis is a devastating process that contributes to poor prognosis and high mortality, yet its detailed underlying mechanisms remain unclear. Here, we aimed to evaluate metastasis-specific markers in oral cancer and to provide comprehensive recognition concerning functional roles of the specific target in oral cancer metastasis.

Methods

Lectin, galactoside-binding, soluble, 1 (LGALS1) was identified by secretomic analysis. LGALS1 expression of patient samples with oral cancer on the tissue microarray were examined by immunochemical (IHC) staining. Small interfering RNA (siRNA)-mediated knockdown of LGALS1 revealed the role of LGALS1 in oral cancer metastasis in vitro and in vivo.

Results

LGALS1 was observed to be upregulated in highly invasive oral cancer cells, and elevated LGALS1 expression was correlated with cancer progression and lymph node metastasis in oral cancer tissue specimens. Functionally, silencing LGALS1 resulted in suppressed cell growth, wound healing, cell migration, and cell invasion in oral cancer cells in vitro. Knockdown of LGALS1 in highly invasive oral cancer cells dramatically inhibited lung metastasis in an in vivo mouse model. Mechanistic studies suggested p38 mitogen-activated protein kinase (MAPK) phosphorylation, upregulated MMP-9, and mesenchymal phenotypes of epithelial-mesenchymal transition (EMT) in highly invasive oral cancer cells, whereas siRNA against LGALS1 resulted in the inactivation of p38 MAPK pathway, downregulated MMP-9, and EMT inhibition.

Conclusions

These findings demonstrate that elevated LGALS1 is strongly correlated with oral cancer progression and metastasis, and that it could potentially serve as a prognostic biomarker and an innovative target for oral cancer therapy.

Proteomic analysis of evodiamine-induced cytotoxicity in thyroid cancer cells

Evodiamine is a natural product extracted from herbal plants such as Tetradium which has shown to have anti-fat uptake and anti-proliferation properties. However, the effects of evodiamine on the behavior of thyroid cancers are largely unknown. To determine if evodiamine might be useful in the treatment of thyroid cancer and its cytotoxic mechanism, we analyzed the impact of evodiamine treatment on differential protein expression in human thyroid cancer cell line ARO using lysine-labeling two-dimensional difference gel electrophoresis (2D-DIGE) combined with mass spectrometry (MS). This study demonstrated 77 protein features that were significantly changed in protein expression and revealed evodiamine-induced cytotoxicity in thyroid cancer cells involves dysregulation of protein folding, cytoskeleton, cytoskeleton regulation and transcription control. Our work shows that this combined proteomic strategy provides a rapid method to study the molecular mechanisms of evodiamine-induced cytotoxicity in thyroid cancer cells. The identified targets may be useful for further evaluation as potential targets in thyroid cancer therapy.

Proteomic investigating the cooperative lethal effect of EGFR and MDM2 inhibitors on ovarian carcinoma

With the concept of precision medicine, combining multiple molecular-targeting therapies has brought new approaches to current cancer treatments. Malfunction of the tumor suppressor protein, p53 is a universal hallmark in human cancers. Under normal conditions, p53 is degraded through an ubiquitin-proteosome pathway regulated by its negative regulator, MDM2. In contrast, cellular stress such as DNA damage will activate p53 to carry out DNA repair, cell cycle arrest, and apoptosis. In this study, we focused on ovarian carcinoma with high EGFR and MDM2 overexpression rate. We assessed the effects of combined inhibition by MDM2 (JNJ-26854165) and EGFR (gefitinib) inhibitors on various ovarian cell lines to determine the importance of these two molecular targets on cell proliferation. We then used a proteomic strategy to investigate the relationship between MDM2 and EGFR inhibition to explore the underlying mechanisms of how their combined signaling blockades work together to exert cooperative inhibition. Our results demonstrated that all four cell lines were sensitive to both individual and combined, MDM2 and EGFR inhibition. The proteomic analysis also showed that gefitinib/JNJ-treated CAOV3 cells exhibited downregulation of proteins involved in nucleotide biosynthesis such as nucleoside diphosphate kinase B (NME2). In conclusion, our study showed that the combined treatment with JNJ and gefitinib exerted synergistic inhibition on cell proliferation, thereby suggesting the potential application of combining MDM2 inhibitors with EGFR inhibitors for enhancing efficacy in ovarian cancer treatment.

Proteomic Analysis of Various Rat Ocular Tissues after Ischemia-Reperfusion Injury and Possible Relevance to Acute Glaucoma

Glaucoma is a group of eye diseases that can cause vision loss and optical nerve damage. To investigate the protein expression alterations in various intraocular tissues (i.e., the cornea, conjunctiva, uvea, retina, and sclera) during ischemia–reperfusion (IR) injury, this study performed a proteomic analysis to qualitatively investigate such alterations resulting from acute glaucoma. The IR injury model combined with the proteomic analysis approach of two-dimensional difference gel electrophoresis (2D-DIGE) and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) was used to monitor the protein expression alterations in two groups of specimens (an IR injury group and a control group). The analysis results revealed 221 unique differentially expressed proteins of a total of 1481 proteins in the cornea between the two groups. In addition, 97 of 1206 conjunctival proteins, 90 of 1354 uveal proteins, 61 of 1180 scleral proteins, and 37 of 1204 retinal proteins were differentially expressed. These findings imply that different ocular tissues have different tolerances against IR injury. To sum up, this study utilized the acute glaucoma model combined with 2D-DIGE and MALDI-TOF MS to investigate the IR injury affected protein expression on various ocular tissues, and based on the ratio of protein expression alterations, the alterations in the ocular tissues were in the following order: the cornea, conjunctiva, uvea, sclera, and retina.

Proteomic analysis of prognostic plasma biomarkers in peripheral arterial occlusive disease

A comprehensive patient-based plasma proteomic approach for the identification of potential plasma biomarkers for the screening and detection of good/poor prognosis of peripheral arterial occlusive disease (PAOD).

MMP-13 is involved in oral cancer cell metastasis

The oral cancer cell line OC3-I5 with a highly invasive ability was selected and derived from an established OSCC line OC3. In this study, we demonstrated that matrix metalloproteinases protein MMP-13 was up-regulated in OC3-I5 than in OC3 cells. We also observed that expression of epithelial-mesenchymal transition (EMT) markers including Twist, p-Src, Snail1, SIP1, JAM-A, and vinculin were increased in OC3-I5 compared to OC3 cells, whereas E-cadherin expression was decreased in the OC3-I5 cells. Using siMMP-13 knockdown techniques, we showed that siMMP-13 not only reduced the invasion and migration, but also the adhesion abilities of oral cancer cells. In support of the role of MMP-13 in metastasis, we used MMP-13 expressing plasmid-transfected 293T cells to enhance MMP-13 expression in the OC3 cells, transplanting the MMP-13 over expressing OC3 cells into nude mice led to enhanced lung metastasis. In summary, our findings show that MMP-13 promotes invasion and metastasis in oral cancer cells, suggesting altered expression of MMP-13 may be utilized to impede the process of metastasis.

Identification of Up- and Down-Regulated Proteins in Pemetrexed-Resistant Human Lung Adenocarcinoma: Flavin Reductase and Calreticulin Play Key Roles in the Development of Pemetrexed-Associated Resistance

Drug resistance is one of the major causes of cancer chemotherapy failure. In the current study, we used a pair of lung adenocarcinoma cell lines, A549 and the pemetrexed-resistant A549/PEM cells, as a model to monitor resistance-dependent cellular responses and identify potential therapeutic targets. By means of 2D differential gel electrophoresis (2D-DIGE) and matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS), we investigated the global protein expression alterations induced by pemetrexed treatment and resistance. The proteomic result revealed that pemetrexed exposure obviously altered the expression of 81 proteins in the A549 cells, whereas no significant response was observed in the similarly treated A549/PEM cells, hence implying an association between these proteins and the drug-specific response. Moreover, 72 proteins including flavin reductase and calreticulin demonstrated differential expression between the A549 and A549/PEM cells, indicating baseline resistance. Additional tests employed siRNA silencing, protein overexpression, cell viability analysis, and analysis of apoptosis to examine and confirm the potency of flavin reductase and calreticulin proteins in the development of pemetrexed resistance. In summary, by using a proteomic approach, we identified numerous proteins, including flavin reductase and calreticulin, involved in pemetrexed drug resistance-developing mechanisms. Our results provide useful diagnostic markers and therapeutic candidates for pemetrexed-resistant lung cancer treatment.

Identification of protein expression alterations in gefitinib-resistant human lung adenocarcinoma: PCNT and mPR play key roles in the development of gefitinib-associated resistance

Gefitinib is the first-line chemotherapeutic drug for treating non-small cell lung cancer (NSCLC), which comprises nearly 85% of all lung cancer cases worldwide. However, most patients eventually develop drug resistance after 12-18 months of treatment. Hence, investigating the drug resistance mechanism and resistance-associated biomarkers is necessary. Two lung adenocarcinoma cell lines, PC9 and gefitinib-resistant PC9/Gef, were established for examining resistance mechanisms and identifying potential therapeutic targets. Two-dimensional differential gel electrophoresis and matrix-assisted laser desorption ionization time-of-flight mass spectrometry were used for examining global protein expression changes between PC9 and PC9/Gef. The results revealed that 164 identified proteins were associated with the formation of gefitinib resistance in PC9 cells. Additional studies using RNA interference showed that progesterone receptor membrane component 1 and pericentrin proteins have major roles in gefitinib resistance. In conclusion, the proteomic approach enabled identifying of numerous proteins involved in gefitinib resistance. The results provide useful diagnostic markers and therapeutic candidates for treating gefitinib-resistant NSCLC.

Proteomic analysis of rhein-induced cyt: ER stress mediates cell death in breast cancer cells

Rhein is a natural product purified from herbal plants such as Rheum palmatum, which has been shown to have anti-angiogenesis and anti-tumor metastasis properties. However, the biological effects of rhein on the behavior of breast cancers are not completely elucidated. To evaluate whether rhein might be useful in the treatment of breast cancer and its cytotoxic mechanism, we analyzed the impact of rhein treatment on differential protein expression as well as redox regulation in a non-invasive breast cancer cell line, MCF-7, and an invasive breast cancer cell line, MDA-MB-231, using lysine- and cysteine-labeling two-dimensional difference gel electrophoresis (2D-DIGE) combined with MALDI-TOF/TOF mass spectrometry. This proteomic study revealed that 73 proteins were significantly changed in protein expression; while 9 proteins were significantly altered in thiol reactivity in both MCF-7 and MDA-MB-231 cells. The results also demonstrated that rhein-induced cytotoxicity in breast cancer cells mostly involves dysregulation of cytoskeleton regulation, protein folding, the glycolysis pathway and transcription control. A further study also indicated that rhein promotes misfolding of cellular proteins as well as unbalancing of the cellular redox status leading to ER-stress. Our work shows that the current proteomic strategy offers a high-through-put platform to study the molecular mechanisms of rhein-induced cytotoxicity in breast cancer cells. The identified differentially expressed proteins might be further evaluated as potential targets in breast cancer therapy.

5-Methoxytryptophan-dependent inhibition of oral squamous cell carcinoma metastasis

The metastatic status of oral cancer is highly associated with the overall survival rate of patients. Previous studies have revealed that the endogenous tryptophan metabolite 5-methoxytryptophan (5-MTP) can downregulate cyclooxygenase-2 expression; suppress tumor proliferation, migration, and invasion; and reduce the tumor size. To improve the understanding of the molecular mechanisms involved in the regulation of 5-MTP in the tumorigenesis of oral cancer, we conducted a comparative wound healing and transwell invasion assays. Our results revealed that 5-MTP reduce oral cancer cell migration and invasion ability. In addition, the results of an in vivo assay demonstrated that the growth of primary tumors was significantly inhibited by 5-MTP in OC3 oral cancer cells and in invasive OC3-I5 oral cancer cells. Moreover, enlarged spleens were observed in OC3-I5-implanted severe combined immunodeficiency mice although 5-MTP can inhibit spleen enlargement. Through comparative proteomics, we identified 32 differentially regulated protein spots by using 2D-DIGE/MALDI-TOF MS analyses. Some of the differentially regulated proteins such as amadillo-repeat-containing X-linked protein 1, phosphoglycerate kinase 1, tropomyosin alpha-1, and tropomyosin alpha-4 may be associated with the 5-MTP-dependent inhibition of oral cancer growth and metastasis. We conclude that 5-MTP plays a crucial role in inhibiting in vitro and in vivo cancer invasion and metastasis.

Mitochondrial proteomics with siRNA knockdown to reveal ACAT1 and MDH2 in the development of doxorubicin-resistant uterine cancer

Mitochondria are key organelles in mammary cells in responsible for a number of cellular functions including cell survival and energy metabolism. Moreover, mitochondria are one of the major targets under doxorubicin treatment. In this study, low-abundant mitochondrial proteins were enriched for proteomic analysis with the state-of-the-art two-dimensional differential gel electrophoresis (2D-DIGE) and matrix-assistant laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS) strategy to compare and identify the mitochondrial protein profiling changes in response to the development of doxorubicin resistance in human uterine cancer cells. The mitochondrial proteomic results demonstrate more than fifteen hundred protein features were resolved from the equal amount pooled of three purified mitochondrial proteins and 101 differentially expressed spots were identified. In which, 39 out of these 101 identified proteins belong to mitochondrial proteins. Mitochondrial proteins such as acetyl-CoA acetyltransferase (ACAT1) and malate dehydrogenase (MDH2) have not been reported with the roles on the formation of doxorubicin resistance in our knowledge. Further studies have used RNA interference and cell viability analysis to evidence the essential roles of ACAT1 and MDH2 on their potency in the formation of doxorubicin resistance through increased cell viability and decreased cell apoptosis during doxorubicin treatment. To sum up, our current mitochondrial proteomic approaches allowed us to identify numerous proteins, including ACAT1 and MDH2, involved in various drug-resistance-forming mechanisms. Our results provide potential diagnostic markers and therapeutic candidates for the treatment of doxorubicin-resistant uterine cancer.

Nuclear proteomics with XRCC3 knockdown to reveal the development of doxorubicin-resistant uterine cancer

The nucleus is a key organelle in mammary cells, which is responsible for several cellular functions including cell proliferation, gene expression, and cell survival. In addition, the nucleus is the primary targets of doxorubicin treatment. In the current study, low-abundance nuclear proteins were enriched for proteomic analysis by using a state-of-the-art two-dimensional differential gel electrophoresis (2D-DIGE) and matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS) strategy to compare and identify the nuclear protein profiling changes responsible for the development of doxorubicin resistance in human uterine cancer cells. The results of the nuclear proteomic analysis indicated that more than 2100 protein features were resolved from an equal pooled amount of three purified nuclear proteins and 117 differentially expressed spots were identified. Of these 117 identified proteins, 48 belonged to nuclear proteins and a positive correlation was observed between the expression levels of 32 of these nuclear proteins and an increase in drug resistance. According to our review of relevant research, nuclear proteins such as DNA repair protein XRCC3 (XRCC3) have not been reported to play roles in the formation of doxorubicin resistance. Previous studies have used RNA interference and cell viability analysis to evidence the essential roles of XRCC3 on its potency in the formation of doxorubicin resistance. To sum up, our nuclear proteomic approaches enabled us to identify numerous proteins, including XRCC3, involved in various drug-resistance-forming mechanisms. Our results provide potential diagnostic markers and therapeutic candidates for treating doxorubicin-resistant uterine cancer.

Proteomics analysis of the DF-1 chicken fibroblasts infected with avian reovirus strain S1133

BACKGROUND

Avian reovirus (ARV) is a member of the Orthoreovirus genus in the Reoviridae family. It is the etiological agent of several diseases, among which viral arthritis and malabsorption syndrome are the most commercially important, causing considerable economic losses in the poultry industry. Although a small but increasing number of reports have characterized some aspects of ARV infection, global changes in protein expression in ARV-infected host cells have not been examined. The current study used a proteomics approach to obtain a comprehensive view of changes in protein levels in host cells upon infection by ARV.

METHODOLOGY AND PRINCIPAL FINDINGS

The proteomics profiles of DF-1 chicken fibroblast cells infected with ARV strain S1133 were analyzed by two-dimensional differential-image gel electrophoresis. The majority of protein expression changes (≥ 1.5 fold, p<0.05) occurred at 72 h post-infection. Matrix-assisted laser desorption ionization time-of-flight mass spectrometry identified 51 proteins with differential expression levels, including 25 that were upregulated during ARV infection and 26 that were downregulated. These proteins were divided into eight groups according to biological function: signal transduction, stress response, RNA processing, the ubiquitin-proteasome pathway, lipid metabolism, carbohydrate metabolism, energy metabolism, and cytoskeleton organization. They were further examined by immunoblotting to validate the observed alterations in protein expression.

CONCLUSION/SIGNIFICANCE

This is the first report of a time-course proteomic analysis of ARV-infected host cells. Notably, all identified proteins involved in signal transduction, RNA processing, and the ubiquitin-proteasome pathway were downregulated in infected cells, whereas proteins involved in DNA synthesis, apoptosis, and energy production pathways were upregulated. In addition, other differentially expressed proteins were linked with the cytoskeleton, metabolism, redox regulation, and stress response. These proteomics data provide valuable information about host cell responses to ARV infection and will facilitate further studies of the molecular mechanisms underlying ARV pathogenesis.

Effect of glutathione reductase knockdown in response to UVB-induced oxidative stress in human lung adenocarcinoma

Background

Glutathione reductase (GR) plays a critical role in the maintenance of physiological redox status in cells. However, the comprehensive investigations of GR-modulated oxidative stress have not been reported.

Methods

In the present study, we cultured a human lung adenocarcinoma line CL1-0 and its GR-knockdown derivative CL1-0ΔGR to evaluate their differential responses to UVB-irradiation.

Results

We identified 18 proteins that showed significant changes under UVB-irradiation in CL1-0ΔGR cells rather than in CL1-0 cells. Several proteins involving protein folding, metabolism, protein biosynthesis and redox regulation showed significant changes in expression.

Conclusions

In summary, the current study used a comprehensive lung adenocarcinoma-based proteomic approach for the identification of GR-modulated protein expression in response to UVB-irradiation. To our knowledge, this is the first global proteomic analysis to investigate the role of GR under UVB-irradiation in mammalian cell model.

5-Methoxytryptophan-dependent protection of cardiomyocytes from heart ischemia reperfusion injury

5-Methoxytryptophan (5-MTP), a catabolic product of tryptophan, can block Cox-2 overexpression in cancer cells as well as suppress cancer cell growth, migration and invasion. The aim of this study was to in vitro examine whether 5-MTP is able to reduce reactive oxygen species (ROS)-induced heart ischemia reperfusion injury and activate the cardiomyocyte's damage surveillance systems. Accordingly, rattus cardiomyocytes were treated with H2O2 as a heart ischemia reperfusion model prior to incubation with/without 5-MTP and proteomic analysis was performed to investigate the physiologic protection of 5-MTP in H2O2-induced ischemia reperfusion in cardiomyocyte. Our data demonstrated that 5-MTP treatment does protect cardiomyocyte in the ROS-induced ischemia reperfusion model. 5-MTP has also been shown to significantly facilitate cell migration and wound healing via cytoskeletal regulations. Additionally, two-dimensional differential gel electrophoresis (2D-DIGE) combined matrix assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF/TOF MS) analysis showed that 5-MTP might modulate growth-associated proteins, cytoskeleton regulation, redox regulation and protein folding to stimulate wound healing as well as prevent these ischemia reperfusion-damaged cardiomyocytes from cell death through maintaining cellular redox-balance and reducing ER-stress. To our knowledge, we report for the first time the cell repair mechanism of 5-MTP against ischemia reperfusion-damage in cardiomyocytes based on cell biology and proteomic analysis.

Quercetin-induced cardioprotection against doxorubicin cytotoxicity

Background

Cancer has continually been the leading cause of death worldwide for decades. Thus, scientists have actively devoted themselves to studying cancer therapeutics. Doxorubicin is an efficient drug used in cancer therapy, but also produces reactive oxygen species (ROS) that induce severe cytotoxicity against heart cells. Quercetin, a plant-derived flavonoid, has been proven to contain potent antioxidant and anti-inflammatory properties. Thus, this in vitro study investigated whether quercetin can decrease doxorubicin-induced cytotoxicity and promote cell repair systems in cardiomyocyte H9C2 cells.

Results

Proteomic analysis and a cell biology assay were performed to investigate the quercetin-induced responses. Our data demonstrated that quercetin treatment protects the cardiomyocytes in a doxorubicin-induced heart damage model. Quercetin significantly facilitated cell survival by inhibiting cell apoptosis and maintaining cell morphology by rearranging the cytoskeleton. Additionally, 2D-DIGE combined with MALDI-TOF MS analysis indicated that quercetin might stimulate cardiomyocytes to repair damage after treating doxorubicin by modulating metabolic activation, protein folding and cytoskeleton rearrangement.

Conclusion

Based on a review of the literature, this study is the first to report detailed protective mechanisms for the action of quercetin against doxorubicin-induced cardiomyocyte toxicity based on in-depth cell biology and proteomic analysis.

Hyaluronic acid-dependent protection against UVB-damaged human corneal cells

Within ultraviolet radiation, ultraviolet B (UVB) is the most energetic and damaging to humans. At the protein level, UVB irradiation downregulates the expression of antioxidant enzymes leading to the accumulation of reactive oxygen species (ROS). Due to lacking of a global analysis of UVB-modulated corneal proteome, we investigate in vitro the mechanism of UVB-induced corneal damage to determine whether hyaluronic acid (HA) is able to reduce UVB irradiation-induced injury in human corneal epithelial cells. Accordingly, human corneal epithelial cell lines (HCE-2) were irradiated with UVB, followed by incubation with low molecular weight HA (LMW-HA, 100 kDa) or high molecular weight HA (HMW-HA, 1,000 kDa) to investigate the physiologic protection of HMW-HA in UVB-induced corneal injury, and to perform a global proteomic analysis. The data demonstrated that HA treatment protects corneal epithelial cells in the UVB-induced wound model, and that the molecular weight of HA is a crucial factor. Only HMW-HA significantly reduces the UVB-induced cytotoxic effects in corneal cells and increases cell migration and wound-healing ability. In addition, proteomic analysis showed that HMW-HA might modulate cytoskeleton regulation, signal transduction, biosynthesis, redox regulation, and protein folding to stimulate wound healing and to prevent these UVB-damaged cells from cell death. Further studies evidenced membrane-associated progesterone receptor component 1 (mPR) and malate dehydrogenase (MDH2) play essential roles in protecting corneal cells from UVB irradiation. This study reports on UVB-modulated cellular proteins that might play an important role in UVB-induced corneal cell injury and show HMW-HA to be a potential substance for protecting corneal cells from UVB-induced injury.

Targeting proteomics to investigate metastasis-associated mitochondrial proteins

Mitochondria are essential organelles in eukaryotic cells and are responsible for regulating energy metabolism, ROS production, and cell survival. Recently, various cellular pathogeneses, including tumorigenesis and metastasis, have been reported to be associated with mitochondrial homeostasis. Consequently, exploiting the correlation between dysfunctional mitochondria and tumor progression has been implicated in the understanding of tumorigenesis, tumor metastasis, and chemoresistance, along with novel strategies to develop cancer therapeutics. To comprehensively understand the role of the mitochondria in cancer metastasis, it is necessary to resolve thousands of mitochondrial proteins and their post-translational modifications with high-throughput global assessments. We introduce mitochondrial proteomic strategies in this review and a discussion on their recent findings related to cancer metastasis. Additionally, the mitochondrial respiratory chain is believed to be a major site for ROS production, and elevated ROS is likely a key source to trigger dysfunctional mitochondria and impaired mitochondrial metabolism that subsequently contribute to the development of cancer progression. Equipment-based metabolomic analysis now allows the monitoring of disease progression and diagnosis. These newly emerging techniques, including proteomics, redox-proteomics, and metabolomics, are described in this review.

Proteomic analysis of retinopathy-related plasma biomarkers in diabetic patients

Diabetic retinopathy occurs in approximately 25% of patients with type 1 or type 2 diabetes; the disease can cause poor vision and even blindness because high glucose levels weaken retinal capillaries, causing leakage of blood into surrounding areas. We adopted a proteomics-based approach using 2D-DIGE and MALDI-TOF/TOF MS to compare the differential plasma proteome between diabetic retinopathy with significant retinopathy occurrence within 5years after diagnosis of diabetes, and diabetic non-retinopathy without diagnosed retinopathy for more than 10years after diagnosis of diabetes. We identified 77 plasma proteins, which represent 28 unique gene products. These proteins mainly have inflammatory response and coagulation roles. Our approach identified several potential diabetic retinopathy biomarkers including afamin and the protein arginine N-methyltransferase 5, which may be associated with the progression and development of diabetes. In conclusion, we report a comprehensive patient-based plasma proteomic approach to the identification of potential plasma biomarkers for diabetic retinopathy screening and detection.

Proteomics-based identification of plasma biomarkers in oral squamous cell carcinoma

Oral squamous cell carcinoma (OSCC) is an aggressive cancer and its occurrence is closely related to betel nut chewing in Taiwan. However, there are few prognostic and diagnostic biomarkers for this disease especially for its association with betel nut chewing. Recent progresses in quantitative proteomics have offered opportunities to discover plasma proteins as biomarkers for tracking the progression and for understanding the molecular mechanisms of OSCC. In present study, plasma samples from OSCC patients with at least 5-year history of betel nut chewing and healthy donors were analyzed by fluorescence 2D-DIGE-based proteomic analysis. Totally, 38 proteins have been firmly identified representing 13 unique gene products. These proteins mainly function in inflammatory responses (such as fibrinogen gamma chain) and transport (Apolipoprotein A-I). Additionally, the current quantitative proteomic approach has identified numerous OSCC biomarkers including fibrinogen (alpha/beta/gamma) chain, haptoglobin, leucine-rich alpha-2-glycoprotein and ribosomal protein S6 kinase alpha-3 (RSK2) which have not been reported and may be associated with the progression and development of the disease. In summary, this study reports a comprehensive patient-based proteomic approach for the identification of potential plasma biomarkers in OSCC. The potential of utilizing these markers for screening and treating OSCC warrants further investigations.

Hyaluronic acid-dependent protection in H9C2 cardiomyocytes: a cell model of heart ischemia-reperfusion injury and treatment

Hyaluronic acid (HA), a glycosaminoglycan with high molecular weight, has been reported to promote cell proliferation and serves as an important extracellular matrix component. The aim of this study was to in vitro investigate whether HA is able to reduce reactive oxygen species (ROS)-induced heart ischemia-reperfusion injury and activate the cardiomyocyte's damage surveillance systems. Accordingly, rattus cardiomyocyte line, H9C2, was treated with H(2)O(2) as a heart ischemia-reperfusion model followed by incubation with low molecular weight hyaluronan (LMW-HA, 100 kDa) or high molecular weight hyaluronan (HMW-HA, 1000 kDa) and proteomic analysis was performed to investigate the physiologic protection of HA in H(2)O(2)-induced ischemia-reperfusion in cardiomyocyte. Our data demonstrated that HA treatment does protect cardiomyocyte in the ROS-induced ischemia-reperfusion model and the molecular weight of HA is a crucial factor. HMW-HA has been shown to significantly facilitate cell migration and wound healing via cytoskeletal rearrangement. Additionally, 2D-DIGE combined MALDI-TOF/TOF analysis showed that HMW-HA might modulate biosynthetic pathways, cell migration, cell outgrowth and protein folding to stimulate wound healing as well as prevent these ischemia-reperfusion-damaged cardiomyocytes from cell death. To our knowledge, we report for the first time the cell repair mechanism of HMW-HA against ischemia-reperfusion-damage in cardiomyocytes based on cell biology and proteomic analysis.

Placenta proteome analysis from Down syndrome pregnancies for biomarker discovery

Down syndrome is one of the most frequent chromosomal disorders, with a prevalence of approximately 1/500 to 1/800, depending on the maternal age distribution of the pregnant population. However, few reliable protein biomarkers have been used in the diagnosis of this disease. Recent progress in quantitative proteomics has offered opportunities to discover biomarkers for tracking the progression and for understanding the molecular mechanisms of Down syndrome. In the present study, placental samples were analyzed by fluorescence two-dimensional differential gel electrophoresis (2D-DIGE) and differentially expressed proteins were identified by matrix assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS). In total, 101 proteins have been firmly identified representing 80 unique gene products. These proteins mainly function in cytoskeleton structure and regulation (such as vimentin and Profilin-1). Additionally, our quantitative proteomics approach has identified numerous previously reported Down syndrome markers, such as myelin protein. Here we present several Down syndrome biomarkers including galectin-1, ataxin-3 and sprouty-related EVH1 domain-containing protein 2 (SPRED2), which have not been reported elsewhere and may be associated with the progression and development of the disease. In summary, we report a comprehensive placenta-based proteomics approach for the identification of potential biomarkers for Down syndrome, in which serum amyloid P-component (APCS) and ataxin-3 have been shown to be up-regulated in the maternal peripheral plasma of Down syndrome cases. The potential of utilizing these markers for the prognosis and screening of Down syndrome warrants further investigation.