Analysis of differentially expressed proteins in oral squamous cell carcinoma by MALDI-TOF MS

Potential use of heat shock protein 90 as a biomarker for the diagnosis of human diseases

INTRODUCTION

The heat shock protein 90 (Hsp90) is a protein involved in many different biological processes and especially in cell survival. Some of these functions require the participation of other biological molecules, so Hsp90 is a chaperone that takes part in many protein-protein interactions working as a critical signaling hub protein. As a member of the heat shock protein family, Hsp90 expression is regulated under certain environmental and/or stressful situations, therefore Hsp90 concentration can be monitored and linked to these effects.

AREAS COVERED

This review discusses the Hsp90 expression in samples from individuals affected by different diseases (from infectious to cancer origin), and the biological consequences of these disorders, including the potential use of Hsp90 as a biomarker for the diagnosis of human diseases.

EXPERT OPINION

The potential of Hsp90 as a biomarker disease has been demonstrated in several studies in relation to infectious diseases and especially cancer. However, further research in this field is still needed, mainly to validate in statistically significant clinical studies that the detection of Hsp90 protein allows the diagnosis of some cancers at an early stage and also that it can act as a biomarker for monitoring the efficacy of their therapies.

E-cigarettes may serve as a gateway to conventional cigarettes and other addictive drugs

Electronic cigarettes (e-cigarettes) are devices that allow the user to inhale nicotine in a vapor, and are primarily marketed as a means of quitting smoking and a less harmful replacement for traditional cigarette smoking. However, further research is needed to determine if vaping nicotine via e-cigarettes can be effective. Conversely, nicotine has been considered a gateway drug to alcohol and other addictive drugs and e-cigarettes containing nicotine may have the same effects. Previous reports have shown that e-cigarette use may open the gate for the use of other drugs including conventional cigarettes, cannabis, opioids, etc. The increasing prevalence of e-cigarettes, particularly among youth and adolescents in the last decade have led to an increase in the dual use of e-cigarettes with alcohol, cannabis, and other illicit drug use like heroin and 3-4-methylenedioxymethamphetamine (MDMA). The advent of e-cigarettes as a device to self-administer addictive agents such as cocaine and synthetic cathinones may bring about additional adverse health effects associated with their concurrent use. This review aims to briefly describe e-cigarettes and their different generations, and their co-use with other addictive drugs as well as the use of the device as a tool to self-administer addictive drugs, such as cocaine, etc.

The Holistic Review on Occurrence, Biology, Diagnosis, and Treatment of Oral Squamous Cell Carcinoma

A prevalent head and neck cancer type is oral squamous cell carcinoma (OSCC). It is widespread and associated with a high death rate of around 50% in some regions of the world. We discuss the likelihood of developing OSCC and the impact of age in this review. Prior to examining the vast array of diagnostic indicators, a brief explanation of the biology of the disease is addressed. Finally, the therapeutic strategies for OSCC are listed. The complete literature for this study was compiled by searching Google Scholar and PubMed using the terms "OSCC," "oral squamous cell carcinoma," "diagnosis of OSCC," "oral cancer," and "biomarkers and OSCC." The research finds that OSCC has several critical parameters with a lot of room for additional in-depth study.

Mass spectrometry analysis of human tear fluid biomarkers specific for ocular and systemic diseases in the context of 3P medicine

Over the last two decades, a large number of non-communicable/chronic disorders reached an epidemic level on a global scale such as diabetes mellitus type 2, cardio-vascular disease, several types of malignancies, neurological and eye pathologies-all exerted system's enormous socio-economic burden to primary, secondary, and tertiary healthcare. The paradigm change from reactive to predictive, preventive, and personalized medicine (3PM/PPPM) has been declared as an essential transformation of the overall healthcare approach to benefit the patient and society at large. To this end, specific biomarker panels are instrumental for a cost-effective predictive approach of individualized prevention and treatments tailored to the person. The source of biomarkers is crucial for specificity and reliability of diagnostic tests and treatment targets. Furthermore, any diagnostic approach preferentially should be noninvasive to increase availability of the biomaterial, and to decrease risks of potential complications as well as concomitant costs. These requirements are clearly fulfilled by tear fluid, which represents a precious source of biomarker panels. The well-justified principle of a "sick eye in a sick body" makes comprehensive tear fluid biomarker profiling highly relevant not only for diagnostics of eye pathologies but also for prediction, prognosis, and treatment monitoring of systemic diseases. One prominent example is the Sicca syndrome linked to a cascade of severe complications that include dry eye, neurologic, and oncologic diseases. In this review, protein profiles in tear fluid are highlighted and corresponding biomarkers are exemplified for several relevant pathologies, including dry eye disease, diabetic retinopathy, cancers, and neurological disorders. Corresponding analytical approaches such as sample pre-processing, differential proteomics, electrophoretic techniques, high-performance liquid chromatography (HPLC), enzyme-linked immuno-sorbent assay (ELISA), microarrays, and mass spectrometry (MS) methodology are detailed. Consequently, we proposed the overall strategies based on the tear fluid biomarkers application for 3P medicine practice. In the context of 3P medicine, tear fluid analytical pathways are considered to predict disease development, to target preventive measures, and to create treatment algorithms tailored to individual patient profiles.

A systematic review of proteomic biomarkers in oral squamous cell cancer

BACKGROUND

Head and neck squamous cell cancer (HNSCC) is the most common cancer associated with chewing tobacco, in the world. As this is divided in to sites and subsites, it does not make it to top 10 cancers. The most common subsite is the oral cancer. At the time of diagnosis, more than 50% of patients with oral squamous cell cancers (OSCC) had advanced disease, indicating the lack of availability of early detection and risk assessment biomarkers. The new protein biomarker development and discovery will aid in early diagnosis and treatment which lead to targeted treatment and ultimately a good prognosis.

METHODS

This systematic review was performed as per PRISMA guidelines. All relevant studies assessing characteristics of oral cancer and proteomics were considered for analysis. Only human studies published in English were included, and abstracts, incomplete articles, and cell line or animal studies were excluded.

RESULTS

A total of 308 articles were found, of which 112 were found to be relevant after exclusion. The present review focuses on techniques of cancer proteomics and discovery of biomarkers using these techniques. The signature of protein expression may be used to predict drug response and clinical course of disease and could be used to individualize therapy with such knowledge.

CONCLUSIONS

Prospective use of these markers in the clinical setting will enable early detection, prediction of response to treatment, improvement in treatment selection, and early detection of tumor recurrence for disease monitoring. However, most of these markers for OSCC are yet to be validated.

Comparative sera proteomics analysis of differentially expressed proteins in oral squamous cell carcinoma

Background

Oral squamous cell carcinoma (OSCC) has increased in incidence from 1990 to 2017, especially in South and Southeast Asia. It is often diagnosed at an advanced stage with a poor prognosis. Therefore, early detection of OSCC is essential to improve the prognosis of OSCC. This study aims to identify the differentially expressed serum proteins as potential biomarkers for oral squamous cell carcinoma (OSCC).

Methods

Comparative proteomics profiling of serum samples from OSCC patients, oral potentially malignant disorder (OPMD) patients, and healthy individuals were performed using two-dimensional gel electrophoresis (2-DE) coupled with mass spectrometry (MS) (n = 60) and bioinformatics analysis. The enzyme-linked immunosorbent assay (ELISA) (n = 120) and immunohistochemistry (IHC) (n = 70) were used to confirm our findings.

Results

The 2-DE analysis revealed that 20 differentially expressed proteins were detected in OPMD and OSCC (p < 0.05). Bioinformatics analysis indicated that the activation of classical complement, liver X receptor/retinoid X receptor (LXR/RXR) activation, and acute phase response signaling pathway are associated with the development and progression of OSCC. Most of the detected proteins are acute-phase proteins and were related to inflammation and immune responses, including apolipoprotein A-I (APOA1), complement C3 (C3), clusterin (CLU), and haptoglobin (HP). The expression levels of CLU and HP in ELISA are consistent with the findings from the 2-DE analysis, except for the mean serum level of HP in OPMD, whereby it was slightly higher than that in control. IHC results demonstrated that CLU and HP are significantly decreased in OSCC tissues.

Conclusion

Decreased expression of CLU and HP could serve as complementary biomarkers of OSCC. These proteins may assist in predicting the outcomes of OSCC patients. However, a larger cohort is needed for further investigation.

Antitumorigenic Effect of Hsp90 Inhibitor SNX-2112 on Tongue Squamous Cell Carcinoma is Enhanced by Low-Intensity Ultrasound

Purpose

The novel Hsp90 inhibitor SNX-2112 showed broad antitumor activity. However, it was still necessary to optimize the therapeutic dosage of SNX-2112 applied on tumors to obtain effective therapy with minimal dose to reduce toxicity. We investigated the role of low-intensity US in promoting antitumorigenic effect of low doses of SNX-2112 on tongue squamous cell carcinoma.

Methods

Cell viability was measured using CCK-8 assay or staining with Calcein AM/PI. Relative cumulative levels of SNX-2112 in cells were detected using high-performance liquid chromatography. The production of ROS was analyzed using fluorescence microscope and flow cytometer. Cellular apoptosis was detected using flow cytometer. The expression levels of proteins of the ERS-associated apoptosis signaling pathway were detected using Western blotting analysis. The efficacy and biosafety of SNX-2112 were also investigated in a mouse xenograft model.

Results

Low-intensity US combined with SNX-2112 exhibited significant antitumor effect, increased the absorption of SNX-2112 by cells even with a low dose, enhanced ROS generation and apoptosis. The combination regimen also inhibited the protein expression of Hsp90 and triggered apoptosis through endoplasmic reticulum stress (ERS) by enhancing PERK, CHOP and Bax protein levels, while downregulating the level of Bcl-2. Additionally, N-acetyl-L-cysteine (NAC), ROS scavenger, was able to reverse these results. Low-intensity US combined with SNX-2112 significantly inhibited tumor growth, prolonged survival of mice, decreased proliferation and promoted apoptosis with no visible damage or abnormalities in major organs in the mouse xenograft model with tongue squamous cell carcinoma.

Conclusion

The antitumor effects of SNX-2112 were enhanced by low-intensity US. The most probable mechanism was that US sonoporation induced more SNX-2112 delivery to the cells and enhanced ROS production, triggering the ERS-associated apoptosis signaling pathway. Therefore, low-intensity US may increase the efficiency of conventional chemotherapy and reduce the dosage of SNX-2112 required and its side effects.

Upregulation of tropomyosin alpha-4 chain in patients' saliva with oral squamous cell carcinoma as demonstrated by Phage display

Patients with oral squamous cell carcinoma (OSCC) present significant alterations in their saliva proteome. We have used the shotgun Phage Display (PD) technology to identify candidate proteins that were upregulated in saliva of OSCC by selecting ligands to salivary proteins from a single-chain variable fragment (scFv) PD combinatorial library. After two selection cycles, the highly reactive clone scFv-D09 was able to distinguish saliva of OSCC patients from healthy subjects by enzyme-linked immunosorbent assay (ELISA) with sensitivity and specificity of 96.67%. Additionally, the scFv-D09 clone presented a positive immunostaining for invasive malignant epithelial cells in the connective tissue, keratin pearls in the OSCC, and ducts of salivary glands. We have further identified the target protein as the tropomyosin alpha-4 chain (TPM4) by two-dimensional polyacrylamide gel electrophoresis and mass spectrometry, and its binding to the scFV-D09 was demonstrated by bioinformatics. Briefly, we have identified TPM4 as upregulated salivary protein in patients with OSCC, which plays a central role in stabilizing cytoskeleton actin filaments, probably linked with tumor tissue remodeling. Long-term longitudinal studies are needed to validate TPM4 as a potential marker of a malignant process.

Identification of Differentially Expressed Proteins from Smokeless Tobacco Addicted Patients Suffering from Oral Squamous Cell Carcinoma

Oral squamous cell carcinoma (OSCC) is the eight most common malignancy worldwide with an incidence rate of 40% in south-east Asia. Lack of effective diagnostic tools at early stage and disease recurrence despite extensive treatments are main reasons for high mortality and low survival rates. The aim of current study was to identify differentially expressed proteins to explore potential candidate biomarkers having diagnostic significance. We performed comparative proteomic analysis of paired protein samples (cancerous buccal mucosa and adjacent normal tissue) from OSCC patients using a combination of two dimensional gel electrophoresis and Mass spectrometric analysis. On the basis of spot intensity, seventeen proteins were found to be consistently differentially expressed among most of the samples which were identified through mass spectrometry. For validation of identified proteins, expression level of stratifin was determined using immuno-histochemistry and Western blot analysis. All identified proteins were analyzed by STRING to explore their interaction. Among uniquely identified proteins in this study, at least two candidate markers (Ig Kappa chain C region and Isoform 2 of fructose bisphosphate aldolase A) were found to be novel with respect to OSCC which can be explored further. Results presented in current study are likely to contribute in understanding the involvement of these molecules in carcinogenesis apart from their plausible role as diagnostic/prognostic markers.

Impact and Relevance of the Unfolded Protein Response in HNSCC

Head and neck squamous cell carcinomas (HNSCC) encompass a heterogeneous group of solid tumors that arise from the upper aerodigestive tract. The tumor cells face multiple challenges including an acute demand of protein synthesis often driven by oncogene activation, limited nutrient and oxygen supply and exposure to chemo/radiotherapy, which forces them to develop adaptive mechanisms such as the Unfolded Protein Response (UPR). It is now well documented that the UPR, a homeostatic mechanism, is induced at different stages of cancer progression in response to intrinsic (oncogenic activation) or extrinsic (microenvironment) perturbations. This review will discuss the role of the UPR in HNSCC as well as in the key processes that characterize the physiology of HNSCC. The role of the UPR in the clinical context of HNSCC will also be addressed.

Phosphoproteome Profiling Reveals Multifunctional Protein NPM1 as part of the Irradiation Response of Tumor Cells

To fight resistances to radiotherapy, the understanding of escape mechanisms of tumor cells is crucial. The aim of this study was to identify phosphoproteins that are regulated upon irradiation. The comparative analysis of the phosphoproteome before and after irradiation brought nucleophosmin (NPM1) into focus as a versatile phosphoprotein that has already been associated with tumorigenesis. We could show that knockdown of NPM1 significantly reduces tumor cell survival after irradiation. NPM1 is dephosphorylated stepwise within 1 hour after irradiation at two of its major phosphorylation sites: threonine-199 and threonine-234/237. This dephosphorylation is not the result of a fast cell cycle arrest, and we found a heterogenous intracellular distribution of NPM1 between the nucleoli, the nucleoplasm, and the cytoplasm after irradiation. We hypothesize that the dephosphorylation of NPM1 at threonine-199 and threonine-234/237 is part of the immediate response to irradiation and of importance for tumor cell survival. These findings could make NPM1 an attractive pharmaceutical target to radiosensitize tumor cells and improve the outcome of radiotherapy by inhibiting the pathways that help tumor cells to escape cell death after gamma irradiation.

Leptin impairs the therapeutic effect of ionizing radiation in oral squamous cell carcinoma cells

PURPOSE

Leptin, an important hormone controlling energy homeostasis, has been linked to the pathogenesis of oral squamous cell carcinoma (OSCC). Evidence indicates that head and neck cancer patients undergoing radiotherapy show decreased leptin levels after radiotherapy treatment. Thus, we investigated, through phenotypic and molecular analyses, whether leptin can compromise the therapeutic effect of ionizing radiation and neoplastic behavior of OSCC cells.

METHODS

The human OSCC-derived cell lines SCC9 and SCC4 were treated with human recombinant leptin and exposed to 6 Gy of irradiation. We performed the in vitro assays of cell migration, death, proliferation, and colony-forming ability. The reactive oxygen species (ROS) levels and proteome analysis by mass spectrometry were also conducted.

RESULTS

Leptin was able to increase cell proliferation, migration, and colony-forming ability, despite the suppressive effect induced by irradiation. Furthermore, the leptin promoted a significant reduction of ROS intracellular accumulation, and increased expression of the cancer-related proteins, as ACTC1, KRT6A, and EEF2 in irradiated OSCC cells.

CONCLUSIONS

Our findings suggest that leptin impairs responsivity of OSCC cells to the ionizing radiation, reducing the suppressive effects of irradiation on the neoplastic phenotype, and increasing protein expression critical to carcinogenesis.

Proteomics investigation of OSCC-specific salivary biomarkers in a Hungarian population highlights the importance of identification of population-tailored biomarkers

Oral squamous cell carcinoma (OSCC) accounting for about 90% of malignant oral lesions is the 6th most common malignancy worldwide. Diagnostic delay may contribute to dismal survival rate therefore, there is a need for developing specific and sensitive biomarkers to improve early detection. Hungarian population occupies the top places of statistics regarding OSCC incidence and mortality figures therefore, we aimed at finding potential salivary protein biomarkers suitable for the Hungarian population. In this study we investigated 14 proteins which were previously reported as significantly elevated in saliva of patients with OSCC. In case of IL-1α, IL-1β, IL-6, IL-8, TNF-α and VEGF a Luminex-based multiplex kit was utilized and the salivary concentrations were determined. In case of catalase, profilin-1, S100A9, CD59, galectin-3-bindig protein, CD44, thioredoxin and keratin-19, SRM-based targeted proteomic method was developed and the relative amount of the proteins was determined in the saliva of patients with OSCC and controls. After several rounds of optimization and using stable isotope-containing peptides, we developed an SRM-based method for rapid salivary protein detection. The validation of the selected potential biomarkers by ELISA revealed salivary protein S100A9 and IL-6 as useful protein biomarkers for OSCC detection improving the diagnostic accuracy for OSCC in the Hungarian population.A noninvasive diagnostic method to detect biomarkers useful for the early diagnosis of OSCC was developed. This can be an attractive strategy in screening saliva samples collected in a nation-wide multi-centric study in order to decrease morbidity, mortality, to enhance survival rate and to improve quality of life. The heterogeneity of protein biomarkers found in different ethnic groups presented in the literature highlights the importance of identification of population-tailored protein biomarkers.

Tropomyosin-1 acts as a potential tumor suppressor in human oral squamous cell carcinoma

It is widely accepted that oral squamous cell carcinoma (OSCC) is a major contributor to the incidence and mortality of neck and head cancer. Tropomyosin-1 (TPM1), which is expressed at a low level, has been considered a prominent tumor-suppressing gene in a variety of solid tumors, although the precise mechanism of the TPM1 gene in OSCC progression remains unknown. We found that TPM1 expression levels decreased in OSCC patients and OSCC cell lines. The overall and cancer-specific survival of patients who exhibited low TPM1 levels were inferior to those of patients who had high TPM1 levels. It was also found that OSCC patients who suffered from disease stageⅠ-Ⅱ were more likely to have an up-regulated TPM1 expression level, and OSCC patients with lymph node metastasis had a higher probability of exhibiting reduced TPM1 expression. We show that overexpression of TPM1 can promote cell apoptosis and inhibit migration. Our results suggest that TPM1 can suppress tumors in OSCC, and the TPM1 expression level is related to OSCC patient prognosis.

Nujiangexathone A, a novel compound from Garcinia nujiangensis, suppresses cervical cancer growth by targeting hnRNPK

Cervical cancer is among the most frequently diagnosed cancers in females worldwide. Nujiangexathone A (NJXA), a novel compound from Garcinia nujiangensis, has been shown to have anti-cancer potential. In this study, the anti-tumor effects and the underlying mechanisms of NJXA action were investigated. Our results suggested that NJXA induced G0/G1 cell cycle arrest in HeLa and SiHa cells by down-regulating cyclins B1, E1, and A and cyclin-dependent kinases 2, 4 and 6, while selectively restoring p27. Using two-dimensional gel electrophoresis, we showed that NJXA reduced the expression of heterogeneous nuclear ribonucleoprotein K (hnRNPK) by accelerating ubiquitin-proteasome-dependent hnRNPK degradation, which then induced cell cycle arrest through the c-Myc-cyclin/Cdk-Rb-E2F1 pathway. The loss-of-function study showed NJXA induced cell cycle arrest was mediated by down regulation of hnRNPK protein. In vivo results further confirmed the tumor inhibitory effect of NJXA via the down-regulation of hnRNPK, and NJXA induced no apparent toxicity. Our study suggests that NJXA may be a novel anti-cancer drug candidate, especially for treating cancers with abnormally high hnRNPK expression.

Cytokeratin and protein expression patterns in squamous cell carcinoma of the oral cavity provide evidence for two distinct pathogenetic pathways

Squamous cell carcinoma (SCC) of the oral cavity is a morphological heterogeneous disease. Various cytokeratin (CK) expression patterns with different prognostic values have been described, but little is known concerning the underlying biological cell mechanisms. Therefore, the present study investigated 193 cases of oral SCCs using immunohistochemistry for α/β/γ-catenin, glucose transporter 1, caspase-3, X-linked inhibitor of apoptosis protein, hypoxia inducible factor-1α, carbonic anhydrase 9, heat shock protein (hsp) 70, mast/stem cell growth factor receptor, p21, p27, p16, p53, B-cell lymphoma 6, epidermal growth factor receptor, cyclin D1 and CK1, 5/6, 8/18, 10, 14 and 19. Expression patterns were analyzed with biomathematical permutation analysis. The present results revealed a significant association between the expression of low-molecular weight CK8/18 and 19 and a high-tumor grade, β and γ-catenin expression, deregulated cell cycle proteins and a predominant localization of the tumor on the floor of the mouth. By contrast, expression of high-molecular weight CK1, 5/6, 10 and 14 was significantly associated with the expression of p21 and hsp70. In conclusion, the current study presents evidence for the existence of two parallel pathogenetic pathways in oral SCCs, characterized by the expression of low- and high-molecular weight CKs. Additional studies are required to demonstrate the extent that these results may be used to improve therapeutic regimens.

Status of p53 and p27(KIP1) in Iranian Patients With Oral Squamous Cell Carcinoma

Background:

Alterations in p53 and p27^KIP1 have been documented as important events in the carcinogenesis of various cancers, but their prognostic role in oral squamous cell carcinoma (OSCC) remains controversial.

Objectives:

The present investigation aimed to evaluate the clinicopathologic and prognostic significance of p53 and p27^KIP1 expression in a group of Iranian patients with OSCC.

Patients and Methods:

In this analytical cross-sectional study, medical records of patients with primary OSCC, diagnosed from 1994 to 2004 were reviewed and 28 subjects were selected based on the inclusion/exclusion criteria. Immunohistochemical staining using monoclonal antibodies against p53 and p27^KIP1 was performed on representative archival paraffin blocks. Demographic data along with information on p53 and p27^KIP1 expression, recurrence, and tumor grade was statistically analyzed using the Fischer exact test. Prognostic factors for overall survival were determined by Cox regression analysis (P < 0.05).

Results:

p53 and p27^KIP1 expression were found in 28.57% (8 positive versus 20 negative) and 67.85% (19 positive versus 9 negative) of OSCC cases, respectively. There was no significant association between these two proteins (P = 0.371), and neither of them showed a significant relationship with the studied clinicopathologic variables (P > 0.05). In survival analysis, only histopathologic differentiation (17 low and moderate, 11 poor) demonstrated a significant correlation with overall survival (P = 0.048).

Conclusions:

Despite the fact that abnormalities in p53 and p27^KIP1 may be involved in the development of OSCC, their clinical significance in the studied population seems limited. Further investigation on the combined p53/p27^KIP1 expression may be helpful in predicting the biologic behavior of this tumor.

Establishment of a new OSCC cell line derived from OLK and identification of malignant transformation-related proteins by differential proteomics approach

Oral squamous cell carcinoma (OSCC) is usually preceded by the oral premalignant lesions, mainly oral leukoplakia (OLK) after repeated insults of carcinogens, tobacco. B(a)P and DMBA are key carcinogens in tobacco smoke. In the present study, for the first time we established the cancerous cell line OSCC-BD induced by B(a)P/DMBA mixture and transformed from dysplastic oral leukoplakia cell line DOK. Cell morphology, proliferation ability, migration ability, colony formation, and tumorigenicity were studied and confirmed the malignant characteristics of OSCC-BD cells. We further identified the differential proteins between DOK and OSCC-BD cells by stable isotope dimethyl labeling based quantitative proteomic method, which showed 18 proteins up-regulated and 16 proteins down-regulated with RSD < 8%. Differential proteins are mainly related to cell cycle, cell proliferation, DNA replication, RNA splicing and apoptosis. Abberant binding function, catalysis activity and transportor activity of differential proteins might contribute to the malignant transformation of OLK. Of the 34 identified differential proteins with RSD < 8%, 13 novel cancer-related proteins were reported in the present study. This study might provide a new insight into the mechanism of OLK malignant transformation and the potent biomarkers for early diagnosis, meanwhile further facilitate the application of the quantification proteomics to carcinogenesis research.

Proteomic identification of the heterogeneous nuclear ribonucleoprotein K as irradiation responsive protein related to migration

Irradiation resistance is a major obstacle of head and neck squamous cell carcinoma (HNSCC) therapy, limiting treatment success and patient survival. The aim of our experiments was to identify irradiation-regulated proteins as potential drug targets. Two established HNSCC cell lines (HNSCCUM-01T and HNSCCUM-02T) were treated with a single 8Gy (Gray) fraction of irradiation. Changes in cellular protein expression were studied after 24h by means of 2D-electrophoresis and MALDI-TOF-mass spectrometry. Ninety-four differentially expressed proteins were identified. The expression levels of four proteins were regulated similarly in both cell lines after irradiation treatment, i.e., GRP78, PRDX, ACTC, and the heterogeneous nuclear ribonucleoprotein K (hnRNPK), suggesting a relevant role during irradiation response. hnRNPK as a p53 interacting protein was verified by Western blotting and immunocytochemical staining as well as functionally analyzed. Knock-down by the use of siRNA resulted in only slightly reduced viability, however, migratory activity was strongly reduced. Combined application of siRNA against hnRNPK and irradiation reduced migration almost completely. We conclude that hnRNPK is potentially implicated in the radiogenic response of HNSCC. The inhibition of hnRNPK might reduce the metastasizing potential of HNSCC especially in combination with irradiation and suggest that this molecule should be further evaluated in this context.

BIOLOGICAL SIGNIFICANCE

We showed completely impaired migration of irradiated hnRNPK-knock-out HNSCC cells, suggesting this molecule as a potential drug target in combined treatment schedules.

Proteomic identification of tumor biomarkers associated with primary gallbladder cancer

AIM: To identify potential biomarkers of primary gallbladder cancer (PGC).

METHODS: Fresh PGC, cholecystitis and normal gallbladder tissue specimens collected from 10 patients, respectively, were subjected to comparative proteomic analysis. The proteomic patterns of PGC were compared with those of cholecystitis and normal gallbladder tissues using two-dimensional gel electrophoresis (2-DE). The differentially expressed proteins were then identified using a MALDI-TOF mass spectrometer (MS) and database searches. To further validate these proteins, 20 samples of PGC tissues and normal tumor-adjacent tissues were collected for Western blot, quantitative real-time PCR, and immunohistochemical staining assay.

RESULTS: Seven differentially expressed protein spots were detected by 2-ED analysis by comparing the average maps of PGC, cholecystitis and normal gallbladder tissues. Six of the seven differentially expressed proteins were identified using MALDI-TOF MS, with three overexpressed and three underexpressed in PGC tissue. Protein levels of annexin A4 (ANXA4) were significantly elevated, and heat shock protein 90-beta (Hsp90β) and dynein cytoplasmic 1 heavy chain 1 (Dync1h1) were decreased in PGC tissues relative to the normal tumor-adjacent tissues as shown by Western blot analysis. However, levels of actin, aortic smooth muscle and gamma-actin were unchanged. In addition, the mRNA levels of all 5 proteins showed similar changes to those of the protein levels (P < 0.01). Further validation by immunohistochemical analysis showed the upregulated expression of ANXA4 and decreased expression of Hsp90β and Dync1h1 in the cytoplasm of PGC tissues relative to the normal tumor-adjacent tissues.

CONCLUSION: Three proteins are identified as potential biomarkers of PGC using proteomic analysis. The functions of these proteins in the carcinogenesis of PGC remain to be studied.

Expression of hypoxic signaling markers in head and neck squamous cell carcinoma and its clinical significance

Hypoxia is a consistent finding in fast-growing tumors; it contributes to tumor progression and therapeutic responses. We explored the expression of hypoxia-associated biomarkers in head and neck squamous cell carcinoma (HNSCC) to assess their relationship with clinical factors in HNSCC. In total, 90 patients with HNSCC were enrolled. Expression of HIF-1α, HSP70, HSP90, VEGF, IGF-1R, and P16 was investigated by immunohistochemistry. Their correlations with clinical factors, including location of primary sites, T stage, N stage, M stage, HPV status, primary treatment success/failure, recurrences, disease-free survival (DFS), and overall survival, were analyzed. HIF-1α, HPS70, HPS90, VEGF, and IGF-1R were positive in 33 of 89 (37.1 %), 62 of 87 (71.3 %), 83 of 89 (93.3 %), 41 of 87 (47.1 %), and 50 of 56 (89.3 %) cases, respectively. Expression levels of some of these markers were correlated. High HIF-1α or HSP 70 correlated with poor DFS, and expression of HSP70 correlated with LN metastasis. HPV-related carcinomas showed high HSP 70 and IGF-1R expression. Hypoxia-associated proteins were highly expressed and associated with aggressive clinical features in HNSCC. Expression of HIF-1α or HSP70 can be considered poor prognostic indicator in HNSCC. Our results suggest that hypoxic signaling is activated in HNSCC, especially in HPV-related tumors.

Proteomic approaches in biomarker discovery: new perspectives in cancer diagnostics

Despite remarkable progress in proteomic methods, including improved detection limits and sensitivity, these methods have not yet been established in routine clinical practice. The main limitations, which prevent their integration into clinics, are high cost of equipment, the need for highly trained personnel, and last, but not least, the establishment of reliable and accurate protein biomarkers or panels of protein biomarkers for detection of neoplasms. Furthermore, the complexity and heterogeneity of most solid tumours present obstacles in the discovery of specific protein signatures, which could be used for early detection of cancers, for prediction of disease outcome, and for determining the response to specific therapies. However, cancer proteome, as the end-point of pathological processes that underlie cancer development and progression, could represent an important source for the discovery of new biomarkers and molecular targets for tailored therapies.

Thioredoxins, glutaredoxins, and peroxiredoxins--molecular mechanisms and health significance: from cofactors to antioxidants to redox signaling

Thioredoxins (Trxs), glutaredoxins (Grxs), and peroxiredoxins (Prxs) have been characterized as electron donors, guards of the intracellular redox state, and "antioxidants". Today, these redox catalysts are increasingly recognized for their specific role in redox signaling. The number of publications published on the functions of these proteins continues to increase exponentially. The field is experiencing an exciting transformation, from looking at a general redox homeostasis and the pathological oxidative stress model to realizing redox changes as a part of localized, rapid, specific, and reversible redox-regulated signaling events. This review summarizes the almost 50 years of research on these proteins, focusing primarily on data from vertebrates and mammals. The role of Trx fold proteins in redox signaling is discussed by looking at reaction mechanisms, reversible oxidative post-translational modifications of proteins, and characterized interaction partners. On the basis of this analysis, the specific regulatory functions are exemplified for the cellular processes of apoptosis, proliferation, and iron metabolism. The importance of Trxs, Grxs, and Prxs for human health is addressed in the second part of this review, that is, their potential impact and functions in different cell types, tissues, and various pathological conditions.

Laser ionization mass spectrometry in oral squamous cell carcinoma

Biomarker research in oral squamous cell carcinoma (OSCC) aims for screening/early diagnosis and in predicting its recurrence, metastasis and overall prognosis. This article reviews the current molecular perspectives and diagnosis of oral cancer with proteomics using matrix-assisted laser desorption ionization (MALDI) and surface-enhanced laser desorption ionization (SELDI) mass spectrometry (MS). This method shows higher sensitivity, accuracy, reproducibility and ability to handle complex tissues and biological fluid samples. However, the data interpretation tools of contemporary mass spectrometry still warrant further improvement. Based on the data available with laser-based mass spectrometry, biomarkers of OSCC are classified as (i) diagnosis and prognosis, (ii) secretory, (iii) recurrence and metastasis, and (iv) drug targets. Majority of these biomarkers are involved in cell homeostasis and are either physiologic responders or enzymes. Therefore, proteins directly related to tumorigenesis have more diagnostic value. Salivary secretory markers are another group that offers a favourable and easy strategy for non-invasive screening and early diagnosis in oral cancer. Key molecular inter-related pathways in oral carcinogenesis are also intensely researched with software analysis to facilitate targeted drug therapeutics. The review suggested the need for incorporating 'multiple MS or tandem approaches' and focusing on a 'group of biomarkers' instead of single protein entities, for making early diagnosis and treatment for oral cancer a reality.

Proteomic profile of keratins in cancer of the gingivo buccal complex: consolidating insights for clinical applications

Keratins play a major role in several cellular functions. Each tissue type expresses a specific set of keratins. The immense potential of keratins as diagnostic and prognostic markers for different cancers is emerging. Oral cancer is the fifteenth most common cancer worldwide. However, comprehensive information on the profile of keratins in the oral cavity is not available. Several independent reports have identified keratins using antibody based techniques which have pitfalls due to the cross reactivity of the antibodies to this set of very homologous proteins. A few recent proteomic studies have reported the identification of keratins in head and neck cancer. Majority of the studies have used tissues from the head and neck region without specifying subsites. This study reports the analysis of enriched preparations of keratins from cancer of the gingivo buccal complex (GBC) using MS, 2DE, WB, silver staining of 2DE gels and IHC. Our study reveals the absence of K4 and K13 and presence of K14, K16, and K17, in cancers of the GBC and combination of these expression patterns in the cut margins. This report also shows that K13 is glycosylated. This well characterized profile of keratins may have potential to be used in clinics.

BIOLOGICAL SIGNIFICANCE

In recent years the immense potential of keratins as diagnostic and prognostic markers for different cancers is emerging. However, comprehensive information on the profile of keratins in the oral cavity is not available. Several independent reports have identified keratins using only antibody based techniques which have pitfalls due to the cross reactivity of the antibodies to this set of very homologous proteins. This study reports the analysis of enriched preparations of keratins from a subsite of the oral cavity, the gingivo buccal complex (GBC) using mass spectrometry, 2DE, western blotting, silver staining of 2DE gels and IHC. The proteomic analysis shows the absence of K4 and K13 and presence of K14, K16, and K17 in cancers of the GBC and combination of these expression patterns in the cut margins. This well characterized profile of keratins from the gingivo buccal complex provides defined markers which may have potential to be used in the clinics.

Quantum dot imaging for HSP70 and HSF‑1 kinetics in SCC‑25 cells with or without leucine deprivation following heat shock

The aim of this study was to develop a quantum dot-based approach for heat shock protein 70 (HSP70) and heat shock factor 1 (HSF-1) kinetics following heat shock, and to discover approaches to thermotherapy based on disrupting the effect of activation of HSF-1 and the accumulation of HSP70 by leucine deprivation. SCC-25 cells cultured with limiting leucine or normal leucine were stressed at 42˚C for 30 min, and were cultured for 2, 4, 6, 8 and 10 h, respectively. The expression of HSP70 and HSF-1 was observed using confocal laser microscopy and semi-quantitative analysis was performed by Image-Pro Plus. At 6 h after heating, HSF-1 in cells cultured with normal leucine was activated and translocated from the cytosol to the nucleus, and the synthesis of HSP70 reached the maximum value and had a tendency to gather in the nucleus. However, in cells cultured with limiting leucine, HSF-1 activity decreased and accumulation of HSP70 was not found. Leucine deprivation results in the inactivation of HSF-1 leading to slight accumulation of HSP70 and no tendency to gather in the nucleus. Thus, HSF-1 may serve as a novel therapeutic target in the treatment of oral cancer.

Identification of novel transcripts deregulated in buccal cancer by RNA-seq

The differential transcriptome analysis provides better understanding of molecular pathways leading to cancer, which in turn allows designing the effective strategies for diagnosis, therapeutic intervention and prediction of therapeutic outcome. This study describes the transcriptome analysis of buccal cancer and normal tissue by CLC Genomics Workbench from the data generated by Roche's 454 sequencing platform, which identified total of 1797 and 2655 genes uniquely expressed in normal and cancer tissues, respectively with 2466 genes expressed in both tissues. Among the genes expressed in both tissues, 1842 were up-regulated whereas 624 were down-regulated in cancer tissue. Besides transcripts known to be involved in cancer, this study led to the identification of novel transcripts, with significantly altered expression in buccal cancer tissue, providing potential targets for diagnosis and cancer therapeutics. The functional categorization by the KEGG pathway and gene ontology analysis revealed enrichment of differentially expressed transcripts to various pathways leading to cancer, including the p53 signaling pathway. Moreover, the gene ontology analysis unfolded suppression of transcripts involved in actin mediated cell contraction process. The down-regulation of four of these transcripts MYL1, ACTA1, TCAP and DESMIN in buccal cancer were further supported by quantitative PCR signifying its possible implication in the cancer progression.

Nanoparticle size is a critical physicochemical determinant of the human blood plasma corona: a comprehensive quantitative proteomic analysis

In biological fluids, proteins associate with nanoparticles, leading to a protein "corona" defining the biological identity of the particle. However, a comprehensive knowledge of particle-guided protein fingerprints and their dependence on nanomaterial properties is incomplete. We studied the long-lived ("hard") blood plasma derived corona on monodispersed amorphous silica nanoparticles differing in size (20, 30, and 100 nm). Employing label-free liquid chromatography mass spectrometry, one- and two-dimensional gel electrophoresis, and immunoblotting the composition of the protein corona was analyzed not only qualitatively but also quantitatively. Detected proteins were bioinformatically classified according to their physicochemical and biological properties. Binding of the 125 identified proteins did not simply reflect their relative abundance in the plasma but revealed an enrichment of specific lipoproteins as well as proteins involved in coagulation and the complement pathway. In contrast, immunoglobulins and acute phase response proteins displayed a lower affinity for the particles. Protein decoration of the negatively charged particles did not correlate with protein size or charge, demonstrating that electrostatic effects alone are not the major driving force regulating the nanoparticle-protein interaction. Remarkably, even differences in particle size of only 10 nm significantly determined the nanoparticle corona, although no clear correlation with particle surface volume, protein size, or charge was evident. Particle size quantitatively influenced the particle's decoration with 37% of all identified proteins, including (patho)biologically relevant candidates. We demonstrate the complexity of the plasma corona and its still unresolved physicochemical regulation, which need to be considered in nanobioscience in the future.