Identification of differentially expressed, tumor-associated proteins in oral squamous cell carcinoma by proteomic analysis

RFX6 facilitates aerobic glycolysis-mediated growth and metastasis of hepatocellular carcinoma through targeting PGAM1

BACKGROUND

Hepatocellular carcinoma (HCC) cells undergo reprogramming of glucose metabolism to support uncontrolled proliferation, of which the intrinsic mechanism still merits further investigation. Although regulatory factor X6 (RFX6) is aberrantly expressed in different cancers, its precise role in cancer development remains ambiguous.

METHODS

Microarrays of HCC tissues were employed to investigate the expression of RFX6 in tumour and adjacent non-neoplastic tissues. Functional assays were employed to explore the role of RFX6 in HCC development. Chromatin immunoprecipitation, untargeted metabolome profiling and sequencing were performed to identify potential downstream genes and pathways regulated by RFX6. Metabolic assays were employed to investigate the effect of RFX6 on glycolysis in HCC cells. Bioinformatics databases were used to validate the above findings.

RESULTS

HCC tissues exhibited elevated expression of RFX6. High RFX6 expression represented as an independent hazard factor correlated to poor prognosis in patients with HCC. RFX6 deficiency inhibited HCC development in vitro and in vivo, while its overexpression exerted opposite functions. Mechanistically, RFX6 bound to the promoter area of phosphoglycerate mutase 1 (PGAM1) and upregulated its expression. The increased PGAM1 protein levels enhanced glycolysis and further promoted the development of HCC.

CONCLUSIONS

RFX6 acted as a novel driver for HCC development by promoting aerobic glycolysis, disclosing the potential of the RFX6-PGAM1 axis for therapeutic targeting.

Exosomal PGAM1 promotes prostate cancer angiogenesis and metastasis by interacting with ACTG1

Tumor-derived exosomes and their contents promote cancer metastasis. Phosphoglycerate mutase 1 (PGAM1) is involved in various cancer-related processes. Nevertheless, the underlying mechanism of exosomal PGAM1 in prostate cancer (PCa) metastasis remains unclear. In this study, we performed in vitro and in vivo to determine the functions of exosomal PGAM1 in the angiogenesis of patients with metastatic PCa. We performed Glutathione-S-transferase pulldown, co-immunoprecipitation, western blotting and gelatin degradation assays to determine the pathway mediating the effect of exosomal PGAM1 in PCa. Our results revealed a significant increase in exosomal PGAM1 levels in the plasma of patients with metastatic PCa compared to patients with non-metastatic PCa. Furthermore, PGAM1 was a key factor initiating PCa cell metastasis by promoting invadopodia formation and could be conveyed by exosomes from PCa cells to human umbilical vein endothelial cells (HUVECs). In addition, exosomal PGAM1 could bind to γ-actin (ACTG1), which promotes podosome formation and neovascular sprouting in HUVECs. In vivo results revealed exosomal PGAM1 enhanced lung metastasis in nude mice injected with PCa cells via the tail vein. In summary, exosomal PGAM1 promotes angiogenesis and could be used as a liquid biopsy marker for PCa metastasis.

Contribution of mechanical homeostasis to epithelial-mesenchymal transition

BACKGROUND

Metastasis refers to the spread of cancer cells from a primary tumor to other parts of the body via the lymphatic system and bloodstream. With tremendous effort over the past decades, remarkable progress has been made in understanding the molecular and cellular basis of metastatic processes. Metastasis occurs through five steps, including infiltration and migration, intravasation, survival, extravasation, and colonization. Various molecular and cellular factors involved in the metastatic process have been identified, such as epigenetic factors of the extracellular matrix (ECM), cell-cell interactions, soluble signaling, adhesion molecules, and mechanical stimuli. However, the underlying cause of cancer metastasis has not been elucidated.

CONCLUSION

In this review, we have focused on changes in the mechanical properties of cancer cells and their surrounding environment to understand the causes of cancer metastasis. Cancer cells have unique mechanical properties that distinguish them from healthy cells. ECM stiffness is involved in cancer cell growth, particularly in promoting the epithelial-mesenchymal transition (EMT). During tumorigenesis, the mechanical properties of cancer cells change in the direction opposite to their environment, resulting in a mechanical stress imbalance between the intracellular and extracellular domains. Disruption of mechanical homeostasis may be one of the causes of EMT that triggers the metastasis of cancer cells.

Comprehensive Review on Development of Early Diagnostics on Oral Cancer with a Special Focus on Biomarkers

One of the most frequent head and neck cancers is oral cancer, with less than half of those diagnosed surviving five years. Despite breakthroughs in the treatment of many other cancers, the prognosis for people with OSCC remains dismal. The conventional methods of detection include a thorough clinical examination, biochemical investigations, and invasive biopsies. Early identification and treatment are important for a better chance of extending a patient’s life. Early diagnosis may be possible by identifying biomarkers in biological fluids. Currently, the primary method for diagnosing oral lesions is a visual oral examination; however, such a technique has certain drawbacks, as individuals are recognized after their cancer has advanced to a severe degree. The first section of this review discusses several diagnostic techniques for cancer detection, while the second section discusses the present state of knowledge about known existing predictive markers for the timely identification of malignant lesions, as well as disease activity tracking. The aim of the paper is to conduct a critical review of existing oral cancer diagnostic processes and to consider the possible application of innovative technology for early detection. This might broaden our diagnostic choices and enhance our capacity to identify and treat oral malignant tumors more effectively.

2D-DIGE-Based Proteomic Profiling with Validations Identifies Vimentin as a Secretory Biomarker Useful for Early Detection and Poor Prognosis in Oral Cancers

Oral tongue squamous cell carcinoma (OTSCC) is an aggressive cancer with high morbidity and mortality rates, despite multimodality management. There are currently no clinically relevant molecular markers that identify patients at higher risk of recurrence and failure. We undertook 2D-DIGE proteomic profiling to study the differentially expressed proteins in OTSCC evaluating their role in prognosis. 2D-DIGE coupled with tandem mass spectrometry was performed on tissues obtained from early staged OTSCC along with its paired apparently adjacent normal tissue samples (n = 10). Top upregulated protein was validated using immunohistochemistry (n = 345), comprising of retrospective early stage OTSCC (n = 150) and prospective series of oral precancers, normal, and oral cancers (n = 195). Saliva samples collected from oral cancer and precancer samples were analyzed by ELISA (n = 146). We found statistically significant differential expression in 151 proteins out of 700 proteins quantified. Top ten differentially regulated proteins were identified using mass spectrometry analysis. We found vimentin, the mesenchymal protein, to be the most upregulated protein in tongue tumor tissues compared to adjacent apparent normal tissues. Vimentin was found to be significantly overexpressed in oral precancers along with cancers compared to normal tissues. The vimentin expression correlated significantly with differentiated states of oral precancers and cancers. Vimentin was also detected at significantly higher levels in saliva collected from oral precancer and cancer patients compared to normal healthy volunteers. Validation of vimentin in an independent series of retrospective early staged OTSCC showed that the vimentin expression is significantly associated with treatment failures and poorer DFS. The vimentin expression is useful as both poor prognostic and early detection marker in oral cancer. Vimentin detection in saliva can be a diagnostic test to detect oral precancers that may have malignant potential, needing closer follow-up, and disease monitoring.

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.

Integrated tissue proteome and metabolome reveal key elements and regulatory pathways in cutaneous squamous cell carcinoma

Cutaneous squamous cell carcinoma (CSCC) is a widespread malignancy but has a very low long-term survival rate for patients at the metastatic stage. Therefore, it is urgent to identify prognostic biomarkers for CSCC and improve our understanding of disease progression. Here we took advantage of a data-independent acquisition (DIA)-based nano liquid chromatography equipped with an orbitrap mass spectrometry (nLC-MS/MS) and ultraperformance LC coupled to a time-of-flight tandem MS (UPLC-TOF-MS/MS) technique to analyze cancer and corresponding noncancerous tissues from 20 CSCC patients for integrated proteomic and metabolomic analyses. Overall, 6241 tissue proteins were detected, while 136 proteins were significantly expressed in CSCC tissues. Further functional analysis revealed that various biological processes were highly enriched and participated in the pathogenesis of CSCC, especially DNA damage responses. Moreover, 641 named metabolites in total were identified, among which 181 were significantly changed in CSCC tissues. A total of 101 pathways were significantly enriched including apoptosis, autophagy, PI3K-Akt and mTOR signaling pathways. Interestingly, two pathways, protein digestion & absorption and platelet activation were both enriched in proteomic and metabolomic studies involving 5 proteins and 11 metabolites. Accordingly, a four-metabolite panel consisting of arachidonate, glutamine, glutamic acid, and proline (all area under the curve (AUC) values more than 0.9) was developed with a high accuracy (0.971) to distinguish the 20 detected cancer tissues from their noncancerous tissues. Collectively, our work highlighted the key elements and regulatory pathways involved in the pathogenesis of CSCC. More importantly, the present study not only provided potential biomarkers for the early diagnosis of CSCC, but also expanded our knowledge of the physiopathology of the disease. SIGNIFICANCE: CSCC is the second most common human cancer but has few treatment options and few sensitive biomarkers for diagnosis. Here we comprehensively revealed its molecular characteristics by performing integrated tissue proteomic and metabolomic analyses. Significantly distinct profiles and certain enriched pathways including DNA damage responses were identified as associated with CSCC. Moreover, protein digestion & absorption and platelet activation were both enriched in the proteome and metabolome. These identified molecular changes probably play significant roles in CSCC development. Finally, we developed a four-metabolite panel to distinguish CSCC with high accuracy. Overall, our data not only provided potential diagnostic biomarkers, but also extended knowledge on the pathogenesis of CSCC.

Serum HSP90-Alpha and Oral Squamous Cell Carcinoma : A Prospective Biomarker

AIM

Current study aims to perform differential protein expression analysis of serum samples from Oral squamous cell carcinoma (OSCC) patients and healthy controls in search of potential diagnostic and/or prognostic biomarker(s).

OBJECTIVE

OSCC is diagnosed late, resulting in poor survival and high mortality. Identification of non-invasive prognostic biomarker is of utmost importance for early diagnosis and proper management of the disease; hence we used proteomic approach to identify potential biomarkers from serum.

METHODS

Serum samples (OSCC n=45 and control n=30) were depleted and proteins were separated using 2-D gel electrophoresis followed by identification by mass spectrometric analysis. Gene expression analysis of identified proteins in malignant and normal tissue was also performed to complement proteomics studies.

RESULTS

Among differentially expressed proteins, a noteworthy observation was up regulation of Heat shock protein alpha (HSP90α) from serum of oral cancer patients. We also observed elevated levels of Haptoglobin (HP) along with down regulation of Type II keratin cytoskeletal 1(KRT1) and serum Albumin (ALB) in oral cancer patients. Gene expression studies of identified proteins in malignant and normal tissue revealed a similar pattern with the exception of KRT1. We believe that elevated levels of serum HSP90 alpha might be used as a potential biomarker.

CONCLUSION

Our findings suggest the contribution of HSP90 alpha and other identified proteins in oral pathology as pro/anti apoptotic modulators, thus they are being considered as predictive biomarkers.

Proteomic approaches to assist in diagnosis and prognosis of oral cancer

Introduction: Oral squamous cell carcinoma (OSCC) ranks among the top 10 leading causes of cancer worldwide, with 5-year survival rate of about 50%, high lymph node metastasis, and relapse rates. The OSCC diagnosis, prognosis, and treatment are mostly based on the clinical TNM classification. There is an urgent need for the discovery of biomarkers and therapeutic targets to assist in the clinical decision-making process.Areas covered: We summarize proteomic studies of the OSCC tumor, immune microenvironment, potential liquid biopsy sites, and post-translational modifications trying to retrieve information in the discovery and verification or (pre)validation phases. The search strategy was based on the combination of MeSH terms and expert refinement.Expert opinion: Untargeted combined with targeted proteomics are strategies that provide reliable and reproducible quantitation of proteins and are the methods of choice of many groups worldwide. Undoubtedly, proteomics has been contributing to the understanding of OSCC progression and uncovers potential candidates as biomarker or therapeutic targets. Nevertheless, none of these targets are available in the clinical practice yet. The scientific community needs to overcome the limitations by investing in robust experimental designs to strengthen the value of the findings, leveraging the translation of knowledge, and further supporting clinical decisions.

Differentially methylated genes in proliferative verrucous leukoplakia reveal potential malignant biomarkers for oral squamous cell carcinoma

OBJECTIVES

To explore the pathophysiology of proliferative verrucous leucoplakia (PVL) through a methylated DNA immunoprecipitation and high-throughput sequencing (MeDIP-seq) case-control study.

MATERIALS AND METHODS

Oral biopsies from ten PVL patients and five healthy individuals were obtained and used to compare their epigenetic patterns. Network biology methods and integrative analyses of MeDIP-seq and RNAseq data were applied to investigate functional relations among differentially methylated genes (DMGs). The value of selected genes as malignant biomarkers was evaluated in a large cohort of oral squamous cell carcinoma (OSCC) patients from TCGA.

RESULTS

A total of 4647 differentially methylated regions were found, with a prominent state of hypermethylation in PVL patients. At the gene level, differentially methylated regions (DMRs) covered 826 genes with distinct roles, including transcription factors and binding proteins with functions in cell adhesion, migration, proliferation, regulation of transcription, bone morphogenesis, and cell signalling. Network analysis revealed three major hubs, two of them collecting proteins related to the response of the patients to PVL and treatment and one hub collecting proteins related to PVL and cancer. The integrative analysis revealed 8 genes (ARTN, CD8A, GATA3, HOXD10, MYO7A, OSR2, PLCB1, and SPOCK2) significantly upregulated in PVL compared to control and 5 genes (ANKRD6, DLG2, GPX3, PITX2, and ZNF736) significantly downregulated. The status of de-regulation found for PVL patients was concordant with what was found for OSCC samples compared to normal adjacent tissue.

CONCLUSION

Our findings show the potential of methylation markers in PVL and suggest novel OSCC diagnostic biomarkers which may boost the development of novel epigenetic-based therapies.

Dose and Sequence Dependent Synergism from the Combination of Oxaliplatin with Emetine and Patulin Against Colorectal Cancer

BACKGROUND

Colorectal cancer is the third most commonly diagnosed cancer in the world, causing many deaths every year. Combined chemotherapy has opened a new horizon in treating colorectal cancer. The objective of the present study is to investigate the activity of oxaliplatin in combination with emetine and patulin against colorectal cancer models.

METHODS

IC50 values of oxaliplatin, emetine and patulin were determined against human colorectal cancer cell lines (HT-29 and Caco-2) using MTT reduction assay. Synergistic, antagonistic and additive effects from the selected binary combinations were determined as a factor of sequence of administration and added concentrations. Proteomics was carried out to identify the proteins which were accountable for combined drug action applying to the selected drug combination.

RESULTS

Oxaliplatin in combination with patulin produced synergism against human colorectal cancer models depending on dose and sequence of drug administration. Bolus administration of oxaliplatin with patulin proved to be the best in terms of synergistic outcome. Altered expressions of nine proteins (ACTG, PROF1, PPIA, PDIA3, COF1, GSTP1, ALDOA, TBA1C and TBB5) were considered for combined drug actions of oxaliplatin with patulin.

CONCLUSION

Bolus administration of oxaliplatin with patulin has the potential to be used in the treatment of colorectal cancer, and would warrant further evaluation using suitable animal model.

Expression of Interleukin-1ß and Interleukin-8 in Oral Potentially Malignant Disorders and Carcinomas

Objective: To evaluate interleukin-1ß (IL-1ß) and interleukin-8 (IL-8) epithelial expressions in potentially malignant disorders of the oral mucosa as malignant predictive markers. Study design: About 55 tissues embedded in paraffin, comprising 15 oral lichen planus (OLP) lesions, 15 leukoplakias, 15 oral squamous cell carcinomas (OSCC), and 10 samples of normal oral mucosa were included in the study. IL-1ß and 8 expressions were assessed by immunohistochemistry using antibodies antihuman IL-1ß human (sc-7884, Santa Cruz® H-153) and antihuman IL-8 (ab7747, abcam®). The number of positive cells was compared using Student's t-test. Any p-value < 0.05 was considered statistically significant. Results: Nuclear and cytoplasmatic keratinocyte staining were positive for both cytokines in all study groups. However, a statistically significant decrease was observed within all cases compared to normal mucosa, both staining for IL-1β and 8. Moreover, IL-8 showed significant differences between OLP and leukoplakia, and when compared to OSCC. Conclusions: Oral epithelial expression of IL-1β and 8 seems to decrease when the malignant transformation of the oral mucosa increases.

Identification of cofilin-1 as a novel mediator for the metastatic potentials and chemoresistance of the prostate cancer cells

Prostate cancer (PCa) is the most common malignancy among men. Tumor metastasis and chemoresistance contribute to the major cause of the mortality. In this study, we compared the protein profiles of two prostate cancer cell lines with different metastatic potentials, and identified cofilin-1 (CFL1) was one of the most differentially expressed proteins between two cell lines. Further results suggested that cofilin-1 promoted the remodeling of F-actin cytoskeleton, and enhanced the proliferation, migration and invasion of the prostate cancer cells via activation of P38 MAPK signaling pathway. In addition, cofilin-1 elevated the expression and drug efflux activity of multidrug resistance protein 1 (MDR1) by P38 MAPK signaling pathway, resulting in decrease of the adriamycin-induced apoptosis as well as the lytic cell death, and the subsequent resistance against adriamycin. Collectively, cofilin-1 might serve as a novel target candidate for both inhibiting the metastasis and reversing the chemoresistance of PCa.

Overexpression of CFL1 in gastric cancer and the effects of its silencing by siRNA with a nanoparticle delivery system in the gastric cancer cell line

Gastric adenocarcinoma, like other cancers, is a multifactorial genetic disease, and metastasis of cancer cells is one of the main features of this illness. The expression levels of the CFL1 gene have been modulated in this pathway. Using small interfering RNA (siRNA) in the treatment of gastric cancer is considered a hopeful gene therapeutic approach. The present study reported the level of CFL1 genes between tumor and margin and healthy tissue of gastric cancer. Also, the features of a cationic nanoparticle with a polymer coating containing polyacrylic acid and polyethyleneimine that were used in the delivery of CFL1 siRNA, were shown. Then the cytotoxicity, cellular uptake, and gene silencing efficiency of this nanoparticle were evaluated with CFL1siRNA.

METHOD

In this study, the CFL1 gene expression was measured in 40 gastric adenocarcinoma, marginal and 15 healthy biopsy samples by a real-time polymerase chain reaction. Physicochemical characteristics, apoptosis, and inhibition of migration of the delivery of CFL1 siRNA by nanoparticle and lipofectamine were investigated in gastric cancer cells.

RESULT

The CFL1 expression was remarkably increased in gastric cancer tissues in comparison with the marginal samples and normal tissues (p < .05) and the biomarker index for CFL1 was obtained as 0.94, then this gene can be probably used as a biomarker for gastric cancer. After treatment of the AGS cell line by CFL1 siRNA, the CFL1 expression level of mRNA and migration in AGS cells were remarkably suppressed after transfection. Furthermore, the amount of apoptosis increased (p < .05).

CONCLUSION

Our results demonstrated that CFL1 downregulation in AGS cells can interdict cell migration. Finally, our outcomes propose that CFL1 can function as an oncogenic gene in gastric cancer and would be considered as a potential purpose of gene therapy for gastric cancer treatment.

Identification of GIMAP7 and Rabl3 as Putative Biomarkers for Oral Squamous Cell Carcinoma Through Comparative Proteomic Approach

Oral squamous cell carcinoma (OSCC) accounts for more than 90% of all oral cancers and has been listed as sixth most common human cancer. Due to late diagnosis and insufficient therapeutic response among patients, the survival rate remains very low accentuating the importance of early diagnostic markers. The study aimed to identify differentially expressed proteins in search for putative serum biomarkers and drug targets. Serum samples (n = 45) were depleted and resolved on two dimensional gel electrophoresis. Among differentially expressed proteins, two were identified using MALDI-TOF mass spectrometry. Gene expression levels of identified proteins were quantified in malignant and normal tissue using RT-qPCR. To validate serum Rabl3 expression, sandwich ELISA was performed. Proteomics analysis revealed two proteins which were found to be associated with oral cancer. The expression of GIMAP7 was found to be down regulated in serum of patients suffering from oral cancer while the expression of Rabl3 was found to be up-regulated. Gene expression analysis in malignant tissue and adjacent normal tissue revealed the same pattern. Quantitative ELISA was used to validate expression of Rabl3 in serum from oral cancer patients and healthy subjects which demonstrated significant up-regulation in cancer patients. Findings in current study demonstrate differential expression of novel putative biomarkers GIMAP7 and Rabl3 in oral cancer which suggests their potential role in oral cancer pathology and can be considered as predictive biomarkers.

PGAM1 knockdown is associated with busulfan‑induced hypospermatogenesis and spermatogenic cell apoptosis

Phosphoglycerate mutase 1 (PGAM1) is reported to be involved in spermatogenic dysfunction. However, the association between PGAM1 and busulfan-induced hypospermatogenesis and spermatogenic cell apoptosis remains unclear. The aim of the current study was to investigate the association between PGAM1 expression and busulfan-induced hypospermatogenesis, and the effect of PGAM1 expression on spermatogenic cell apoptosis. PGAM1 expression was detected in mouse models of busulfan-induced hypospermatogenesis by western blotting, reverse transcription-quantitative polymerase chain reaction and immunohistochemistry. Then, spermatogenic cell apoptosis in mouse models of busulfan-induced hypospermatogenesis was assessed by TUNEL assay. The effect and potential mechanism of PGAM1 downregulation on spermatogenic cells were further investigated. The results indicated that PGAM1 expression was significantly downregulated in the mouse models of busulfan-induced hypospermatogenesis, compared with those with normal spermatogenesis (P<0.05). Furthermore, the TUNEL assay revealed that the apoptosis of spermatogenic cells was accelerated in the mouse model of busulfan-induced hypospermatogenesis. In addition, PGAM1 knockdown promoted the apoptosis of spermatogenic cells in vitro, which was associated with the P53/Caspase 3/Caspase 6/Caspase 9 signaling pathway. In conclusion, these data indicate that PGAM1 knockdown is associated with busulfan-induced hypospermatogenesis and contributes to spermatogenic cell apoptosis by regulating the P53/Caspase 3/Caspase 6/Caspase 9 signaling pathway.

Identification of Proteomic Markers in Head and Neck Cancer Using MALDI-MS Imaging, LC-MS/MS, and Immunohistochemistry

PURPOSE

The heterogeneity of squamous cell carcinoma tissue greatly complicates diagnosis and individualized therapy. Therefore, characterizing the heterogeneity of tissue spatially and identifying appropriate biomarkers is crucial. MALDI-MS imaging (MSI) is capable of analyzing spatially resolved tissue biopsies on a molecular level.

EXPERIMENTAL DESIGN

MALDI-MSI is used on snap frozen and formalin-fixed and paraffin-embedded (FFPE) tissue samples from patients with head and neck cancer (HNC) to analyze m/z values localized in tumor and nontumor regions. Peptide identification is performed using LC-MS/MS and immunohistochemistry (IHC).

RESULTS

In both FFPE and frozen tissue specimens, eight characteristic masses of the tumor's epithelial region are found. Using LC-MS/MS, the peaks are identified as vimentin, keratin type II, nucleolin, heat shock protein 90, prelamin-A/C, junction plakoglobin, and PGAM1. Lastly, vimentin, nucleolin, and PGAM1 are verified with IHC.

CONCLUSIONS AND CLINICAL RELEVANCE

The combination of MALDI-MSI, LC-MS/MS, and subsequent IHC furnishes a tool suitable for characterizing the molecular heterogeneity of tissue. It is also suited for use in identifying new representative biomarkers to enable a more individualized therapy.

Phosphoglycerate Mutase 1 Promotes Cell Proliferation and Neuroblast Differentiation in the Dentate Gyrus by Facilitating the Phosphorylation of cAMP Response Element-Binding Protein

In a previous study, we observed a significant increase in phosphoglycerate mutase 1 (PGAM1) levels after pyridoxine treatment. In the present study, we investigated the effects of PGAM1 on novel object recognition, cell proliferation, and neuroblast differentiation in the dentate gyrus. We generated a Tat-PGAM1 fusion protein to cross the blood-brain barrier and neuronal plasma membrane. We administered the Tat peptide, control-PGAM1, or Tat-PGAM1 fusion protein to 8-week-old mice once a day for 3 weeks and tested novel object recognition memory. The mice were then euthanized to conduct western blot analysis for polyhistidine expression and immunohistochemical analysis for Ki67, doublecortin, and phosphorylated cAMP response element-binding protein. Mice treated with Tat peptide showed similar exploration times for familiar and new objects and the discrimination index was significantly lower in this group than in the control group. Tat-PGAM1 moderately increased the exploration time of new objects when compared to familiar objects, while the discrimination index was significantly higher in the Tat-PGAM1-treated group, but not in the control-PGAM1-treated group, when compared with the control group. Higher PGAM1 protein expression was observed in the hippocampus of Tat-PGAM1-treated mice when compared with the hippocampi of control, Tat peptide-, and control-PGAM1-treated mice, using western blot analysis. In addition, the numbers of proliferating cells and differentiated neuroblasts were significantly lower in the Tat peptide-treated group than in the control group. In contrast, the numbers of proliferating cells and differentiated neuroblasts in the dentate gyrus were higher in the Tat-PGAM1-treated group than in the control group. Administration of Tat-PGAM1 significantly facilitated the phosphorylation of cAMP response element-binding protein in the dentate gyrus. Administration of control-PGAM1 did not show any significant effects on novel object recognition, cell proliferation, and neuroblast differentiation in the dentate gyrus. These results suggest that PGAM1 plays a role in cell proliferation and neuroblast differentiation in the dentate gyrus via the phosphorylation of cAMP response element-binding protein in the hippocampus.

Xanthone derivatives as phosphoglycerate mutase 1 inhibitors: Design, synthesis, and biological evaluation

Phosphoglycerate mutase 1 (PGAM1) is a glycolytic enzyme that dynamically converts 3-phosphoglycerate (3PG) to 2-phosphoglycerate (2PG), which was upregulated to coordinate glycolysis, pentose phosphate pathway (PPP) and serine biosynthesis to promote cancer cell proliferation and tumor growth in a variety of cancers. However, only a few inhibitors of PGAM1 have been reported with poor molecular or cellular efficacy. In this paper, a series of xanthone derivatives were discovered as novel PGAM1 inhibitors through scaffold hopping and sulfonamide reversal strategy based on the lead compound PGMI-004A. Most xanthone derivatives showed higher potency against PGAM1 than PGMI-004A and exhibited moderate anti-proliferation activity on different cancer cell lines.

Global Quantitative Proteomics reveal Deregulation of Cytoskeletal and Apoptotic Signalling Proteins in Oral Tongue Squamous Cell Carcinoma

Oral malignancies remain to have higher morbidity and mortality rates owing to the poor understanding of the carcinogenesis and the lack of early detection and diagnosis. The lack of established biomarkers for oral tongue squamous cell carcinoma (OTSCC) resulted in aggressive multi-modality management less effective. Here, we report for the first time that a panel of potential markers identified from tongue tumor samples using two-dimensional-differential-in-gel-electrophoresis (2D-DIGE). Our approach of combining 2D-DIGE with tandem mass spectrometry identified 24 candidate proteins including cofilins, myosin light chain family members, annexins, serpins, HSPs and tropomyosins, with significant differential expression in tongue carcinomas as compared with their matched adjacent normal tissues. The expression levels of the identified proteins were further validated in larger cohort of Indian samples using qPCR. Most of the differentially regulated proteins are involved in actin cytoskeletal dynamics, drug resistance, immune system, inflammation and apoptotic signalling pathways and are known to play critical role in oral tumorigenesis. Taken together, the results from present investigation provide a valuable base for understanding the development and progression of OTSCC. The validated panel of proteins may be used as potential biomarkers for early detection as well as in predicting therapeutic outcome of OTSCC.

Expression of UGP2 and CFL1 expression levels in benign and malignant pancreatic lesions and their clinicopathological significance

BACKGROUND

This study investigated UGP2 (uridine diphosphate-glucose pyrophosphorylase-2) and CFL1 (cofilin-1) expression in pancreatic ductal carcinoma (PDC), paracancerous tissue (PT), benign lesions (BL), and normal tissue (NT) and their clinicopathological significance.

METHODS

Surgical specimens, which were collected from 106 cases of pancreatic ductal carcinoma, 35 cases of paracancerous tissues, 55 cases of benign lesions and 13 cases of normal pancreatic tissues, were fixed with 4% formaldehyde to prepare conventional paraffin-embedded sections. EnVision immunohistochemical was used to stain for UGP2 and CFL1. Kaplan-Meier survival analysis was performed to assess the correlation of expression pattern with survival.

RESULTS

We found that positive UGP2 and CFL1 expression in PDC were significantly higher than those in PT, BL, and NT. In PT and BL with positive UGP2 and CFL1 expression, mild to severe atypical hyperplasia or intraepithelial neoplasia of grades II-III was observed in ductal epithelium. Positive UGP2 and CFL1 expression in cases with high differentiation, no lymph node metastasis, no surrounding invasion, and TNM (tumor-node-metastasis) staging I or/and II were significantly lower than those in cases with poor differentiation, lymph node metastasis, surrounding invasion, and TNM stage III and/or IV. Positive UGP2 expression in male patients was significantly lower than that in female patients. UGP2 and CFL1 expression in PDC were positively correlated. Kaplan-Meier survival analysis showed the degree of differentiation, tumor maximal diameter, TNM stage, lymph node metastasis, and surrounding invasion, and UGP2 and CFL1 expression were closely related to the average survival time of patients with PDC. The survival time of patients with positive UGP2 and CFL1 expression was significantly shorter than that of patients with negative expression. Cox multivariate analysis showed that poor differentiation, tumor maximal diameter ≥ 3 cm, TNM stage III or IV, lymph node metastasis, surrounding invasion, and positive UGP2 and CFL1 expression was negatively correlated with the postoperative survival rate and positively correlated with the mortality of patients with PDC.

CONCLUSION

Positive expression of UGP2 and CFL1 can serve a valuable prognostic factor in pancreatic cancer.

Downregulation of LIMK1-ADF/cofilin by DADS inhibits the migration and invasion of colon cancer

This study aimed to explore whether the downregulation of LIM kinase 1 (LIMK1)-actin depolymerization factor (ADF, also known as destrin)/cofilin by diallyl disulfide (DADS) inhibited the migration and invasion of colon cancer. Previous studies have shown that silencing LIMK1 could significantly enhance the inhibitory effect of DADS on colon cancer cell migration and invasion, suggesting that LIMK1 was a target molecule of DADS, which needed further confirmation. This study reported that LIMK1 and destrin were highly expressed in colon cancer and associated with poor prognosis of patients with colon cancer. Also, the expression of LIMK1 was positively correlated with the expression of destrin. The overexpression of LIMK1 significantly promoted colon cancer cell migration and invasion. DADS obviously inhibited migration and invasion by suppressing the phosphorylation of ADF/cofilin via downregulation of LIMK1 in colon cancer cells. Furthermore, DADS-induced suppression of cell proliferation was enhanced and antagonized by the knockdown and overexpression of LIMK1 in vitro and in vivo, respectively. Similar results were observed for DADS-induced changes in the expression of vimentin, CD34, Ki-67, and E-cadherin in xenografted tumors. These results indicated that LIMK1 was a potential target molecule for the inhibitory effect of DADS on colon cancer cell migration and invasion.

A nuclear-directed human pancreatic ribonuclease (PE5) targets the metabolic phenotype of cancer cells

Ribonucleases represent a new class of antitumor RNA-damaging drugs. However, many wild-type members of the vertebrate secreted ribonuclease family are not cytotoxic because they are not able to evade the cytosolic ribonuclease inhibitor. We previously engineered the human pancreatic ribonuclease to direct it to the cell nucleus where the inhibitor is not present. The best characterized variant is PE5 that kills cancer cells through apoptosis mediated by the p21^WAF1/CIP1 induction and the inactivation of JNK. Here, we have used microarray-derived transcriptional profiling to identify PE5 regulated genes on the NCI/ADR-RES ovarian cancer cell line. RT-qPCR analyses have confirmed the expression microarray findings. The results show that PE5 cause pleiotropic effects. Among them, it is remarkable the down-regulation of multiple genes that code for enzymes involved in deregulated metabolic pathways in cancer cells.

Phosphoglycerate mutase 1 promotes cancer cell migration independent of its metabolic activity

Phosphoglycerate mutase 1 (PGAM1) is a glycolytic enzyme that coordinates glycolysis and biosynthesis to promote cancer growth via its metabolic activity. Here, we report the discovery of a non-metabolic function of PGAM1 in promoting cancer metastasis. A proteomic study identified α-smooth muscle actin (ACTA2) as a PGAM1-associated protein. PGAM1 modulated actin filaments assembly, cell motility and cancer cell migration via directly interacting with ACTA2, which was independent of its metabolic activity. The enzymatically inactive H186R mutant retained its association with ACTA2, whereas 201-210 amino acids deleted PGAM1 mutant lost the interaction with ACTA2 regardless of intact metabolic activity. Importantly, PGAM1 knockdown decreased metastatic potential of breast cancer cells in vivo and PGAM1 and ACTA2 were jointly associated with the prognosis of breast cancer patients. Together, this study provided the first evidence revealing a non-metabolic function of PGAM1 in promoting cell migration, and gained new insights into the role of PGAM1 in cancer progression.

The diagnostic value and functional roles of phosphoglycerate mutase 1 in glioma

Previous studies indicated that phosphoglycerate mutase 1 (PGAM1) is involved in many cancer types and promotes breast cancer progression. However, the role of PGAM1 in glioma remains unclear. The present study aimed to investigate the association of PGAM1 expression with glioma grade and the role of PGAM1 in proliferation, apoptosis, migration and invasion of glioma cells. The mRNA and protein expression of PGAM1 was analysed in glioma tissues and normal brain tissues. The expression of PGAM1 was examined further by immunohistochemical analysis. In addition, we inhibited the expression of PGAM1 in glioma cell line by siRNA to evaluate its role in glioma proliferation, apoptosis, migration and invasion. The mRNA and protein expression of PGAM1 was significantly greater in glioma than normal brain tissues. PGAM1 expression was associated with the WHO grade of glioma. siRNA knockdown of PGAM1 significantly inhibited glioma cell proliferation, promoted glioma cell apoptosis, induced S phase cell cycle arrest and inhibited glioma cell migration and invasion in vitro. PGAM1 may be associated with the grade of glioma and be involved in the biological behavior of glioma cells. PGAM1 might be a novel therapeutic target in glioma.

Updated overview of current biomarkers in head and neck carcinoma

Squamous cell cancer is the most common type of malignancy arising from the epithelial cells of the head and neck region. Head and neck squamous cell carcinoma (HNSCC) is one of the predominant causes of cancer related casualties worldwide. Overall prognosis in this disease has improved to some extent with the advancements in therapeutic modalities but detection of primary tumor at its initial stage and prevention of relapse are the major targets to be achieved for further improvement in terms of survival rate of patients. Latest achievements in basic research regarding molecular characterization of the disease has helped in better perception of the molecular mechanisms involved in HNSCC progression and also in recognizing and targeting various molecular biomarkers associated with HNSCC. In the present article, we review the information regarding latest and potential biomarkers for the early detection of HNSCC. A detailed molecular characterization, ultimately, is likely to improve the development of new therapeutic strategies, potentially relevant to diagnosis and prognosis of head and neck cancers. The need for more accurate and timely disease prediction has generated enormous research interests in this field.

Progesterone promotes cell migration, invasion and cofilin activation in human astrocytoma cells

Astrocytomas are the most common and aggressive primary brain tumors in humans. Invasiveness of these tumors has been attributed in part to deregulation of cell motility-dependent cytoskeletal dynamics that involves actin-binding proteins such as cofilin. Progesterone (P4) has been found to induce migration and invasion of cells derived from breast cancer and endothelium. However, the role of P4 in migration and invasion of astrocytoma cells as well as its effects on astrocytomas cytoskeleton remodeling is not known. In this work we evaluated these aspects in D54 and U251 cells derived from human astrocytomas from the highest degree of malignancy (grade IV, glioblastoma). Our results showed that in scratch-wound assays P4 increased the number of D54 and U251 cells migrating from 3 to 48 h. Both RU486, a P4 receptor (PR) antagonist, and an oligonucleotide antisense against PR significantly blocked P4 effects. Transwell assays showed that P4 significantly increased the number of invasive cells at 24h. As in the case of migration, this effect was blocked by RU486. Finally, by Western blotting, an increase in the cofilin/p-cofilin ratio at 15 and 30 min and a decrease at 30 and 60 min in U251 and D54 cells, respectively, was observed after P4, P4+RU486 and RU486 treatments. These data suggest that P4 increases human astrocytoma cells migration and invasion through its intracellular receptor, and that cofilin activation by P4 is independent of PR action.

PTPRN2 and PLCβ1 promote metastatic breast cancer cell migration through PI(4,5)P2-dependent actin remodeling

Altered abundance of phosphatidyl inositides (PIs) is a feature of cancer. Various PIs mark the identity of diverse membranes in normal and malignant cells. Phosphatidylinositol 4,5‐bisphosphate (PI(4,5)P₂) resides predominantly in the plasma membrane, where it regulates cellular processes by recruiting, activating, or inhibiting proteins at the plasma membrane. We find that PTPRN2 and PLCβ1 enzymatically reduce plasma membrane PI(4,5)P₂ levels in metastatic breast cancer cells through two independent mechanisms. These genes are upregulated in highly metastatic breast cancer cells, and their increased expression associates with human metastatic relapse. Reduction in plasma membrane PI(4,5)P₂ abundance by these enzymes releases the PI(4,5)P₂‐binding protein cofilin from its inactive membrane‐associated state into the cytoplasm where it mediates actin turnover dynamics, thereby enhancing cellular migration and metastatic capacity. Our findings reveal an enzymatic network that regulates metastatic cell migration through lipid‐dependent sequestration of an actin‐remodeling factor.

Transcriptional profiling of GBM invasion genes identifies effective inhibitors of the LIM kinase-Cofilin pathway

Malignant gliomas are highly proliferative and invasive neoplasms where total surgical resection is often impossible and effective local radiation therapy difficult. Consequently, there is a need to develop a greater understanding of the molecular events driving invasion and to identify novel treatment targets. Using microarray analysis comparing normal brain samples and mesenchymal glioblastoma multiforme (GBM), we identified over 140 significant genes involved in cell migration and invasion. The cofilin (CFL) pathway, which disassembles actin filaments, was highly up-regulated compared to normal brain. Up-regulation of LIM domain kinase 1 and 2 (LIMK1/2), that phosphorylates and inactivates cofilin, was confirmed in an additional independent data set comparing normal brain to GBM. We identified and utilized two small molecule inhibitors BMS-5 and Cucurbitacin I directed against the cofilin regulating kinases, LIMK1 and LIMK2, to target this pathway. Significant decreases in cell viability were observed in glioma cells treated with BMS-5 and Cucurbitacin I, while no cytotoxic effects were seen in normal astrocytes that lack LIMK. BMS-5 and Cucurbitacin I promoted increased adhesion in GBM cells, and decreased migration and invasion. Collectively, these data suggest that use of LIMK inhibitors may provide a novel way to target the invasive machinery in GBM.

Identification of RAB2A and PRDX1 as the potential biomarkers for oral squamous cell carcinoma using mass spectrometry-based comparative proteomic approach

Despite the recent advances in diagnostic and therapeutic strategies, oral squamous cell carcinoma (OSCC) remains a major health burden. Protein biomarker discovery for early detection will help to improve patient survival rate in OSCC. Mass spectrometry-based proteomics has emerged as an excellent approach for detection of protein biomarkers in various types of cancers. In the current study, we have used 4-Plex isobaric tags for relative and absolute quantitation (iTRAQ)-based shotgun quantitative proteomic approach to identify proteins that are differentially expressed in cancerous tissues compared to normal tissues. The high-resolution mass spectrometric analysis resulted in identifying 2,074 proteins, among which 288 proteins were differentially expressed. Further, it was noticed that 162 proteins were upregulated, while 125 proteins were downregulated in OSCC-derived cancer tissue samples as compared to the adjacent normal tissues. We identified some of the known molecules which were reported earlier in OSCC such as MMP-9 (8.4-fold), ZNF142 (5.6-fold), and S100A7 (3.5-fold). Apart from this, we have also identified some novel signature proteins which have not been reported earlier in OSCC including ras-related protein Rab-2A isoform, RAB2A (4.6-fold), and peroxiredoxin-1, PRDX1 (2.2-fold). The immunohistochemistry-based validation using tissue microarray slides in OSCC revealed overexpression of the RAB2A and PRDX1 gene in 80 and 68 % of the tested clinical cases, respectively. This study will not only serve as a resource of candidate biomarkers but will contribute towards the existing knowledge on the role of the candidate molecules towards disease progression and therapeutic potential.

Porphyromonas gingivalis attenuates ATP-mediated inflammasome activation and HMGB1 release through expression of a nucleoside-diphosphate kinase

Many intracellular pathogens evade the innate immune response in order to survive and proliferate within infected cells. We show that Porphyromonas gingivalis, an intracellular opportunistic pathogen, uses a nucleoside-diphosphate kinase (NDK) homolog to inhibit innate immune responses due to stimulation by extracellular ATP, which acts as a danger signal that binds to P2X7 receptors and induces activation of an inflammasome and caspase-1. Thus, infection of gingival epithelial cells (GECs) with wild-type P. gingivalis results in inhibition of ATP-induced caspase-1 activation. However, ndk-deficient P. gingivalis is less effective than wild-type P. gingivalis in reducing ATP-mediated caspase-1 activation and secretion of the pro-inflammatory cytokine, IL-1β, from infected GECs. Furthermore, P. gingivalis NDK modulates release of high-mobility group protein B1 (HMGB1), a pro-inflammatory danger signal, which remains associated with chromatin in healthy cells. Unexpectedly, infection with either wild-type or ndk-deficient P. gingivalis causes release of HMGB1 from the nucleus to the cytosol. But HMGB1 is released to the extracellular space when uninfected GECs are further stimulated with ATP, and there is more HMGB1 released from the cells when ATP-treated cells are infected with ndk-deficient mutant than wild-type P. gingivalis. Our results reveal that NDK plays a significant role in inhibiting P2X7-dependent inflammasome activation and HMGB1 release from infected GECs.

Novel technologies for oral squamous carcinoma biomarkers in diagnostics and prognostics

BACKGROUND

Oral squamous cell carcinoma (OSCC) is a highly prevalent malignant pathology of the oral cavity. Despite the significant progress accomplished in the field of OSCC, the diagnosis is performed mostly in advanced stages; thus, novel biomarkers need to be developed for the diagnostic and prognostic of this malignancy. Many new technologies are used to provide indispensable information related to the pathogenesis of OSCC. The molecular profiling studies that incorporate genetic and epigenetic alterations need to be integrated in clinical practice as routine approaches to facilitate a better diagnostic and prognostic.

REVIEW

In this review, the authors present a summary of these novel technologies in the field of genomics, transcriptomics or proteomics, capable of generating data related to personalized diagnostic and treatment.

Prelude to oral microbes and chronic diseases: past, present and future

Associations between oral and systemic health are ancient. Oral opportunistic bacteria, particularly, Porphyromonas gingivalis and Fusobacterium nucleatum, have recently been deviated from their traditional roles as periodontal pathogens and arguably ascended to central players based on their participations in complex co-dependent mechanisms of diverse systemic chronic diseases risk and pathogenesis, including cancers, rheumatoid-arthritis, and diabetes.

PGAM1 is Involved in Spermatogenic Dysfunction and Affects Cell Proliferation, Apoptosis, and Migration

OBJECTIVE

To investigate the correlation between PGAM1 and spermatogenic dysfunction and to evaluate the effect of expression of PGAM1 on the function of germ cells.

METHODS

Expression of PGAM1 was detected in 40 cases of infertile males with definite pathological diagnosis and 12 cases of mouse models with spermatogenic dysfunction by immunohistochemistry. Then, cell proliferation, apoptosis, and migration were evaluated when expression of PGAM1 was knocked down by a specific small interfering RNA in GC1 and TM4 cells.

RESULTS

The positive rates of PGAM1 in patients with normal spermatogenesis, mild hypospermatogenesis, severe hypospermatogenesis, and Sertoli cell-only syndrome were 90%, 80%, 10%, 100%, respectively, and the difference was significant (P < .001). Meanwhile, expression of PGAM1 was found to be significantly decreased in mouse models with spermatogenic dysfunction. Moreover, when expression of PGAM1 was knocked down in GC1 cells, the proliferation and migration were significantly inhibited, but the rate of apoptosis was significantly increased. Furthermore, PGAM1 downregulation in TM4 cells significantly inhibited proliferation and promoted apoptosis but didn't affect migration.

CONCLUSION

PGAM1 correlates with spermatogenic distinction and affects the function of cell proliferation, apoptosis and migration.

The actin cytoskeleton as a sensor and mediator of apoptosis

Apoptosis is an important biological process required for the removal of unwanted or damaged cells. Mounting evidence implicates the actin cytoskeleton as both a sensor and mediator of apoptosis. Studies also suggest that actin binding proteins (ABPs) significantly contribute to apoptosis and that actin dynamics play a key role in regulating apoptosis signaling. Changes in the organization of the actin cytoskeleton has been attributed to the process of malignant transformation and it is hypothesized that remodeling of the actin cytoskeleton may enable tumor cells to evade normal apoptotic signaling. This review aims to illuminate the role of the actin cytoskeleton in apoptosis by systematically analyzing how actin and ABPs regulate different apoptosis pathways and to also highlight the potential for developing novel compounds that target tumor-specific actin filaments.

Proteomic analysis of oral cavity squamous cell carcinoma specimens identifies patient outcome-associated proteins

CONTEXT

Global proteomic analysis of oral cavity squamous cell carcinoma was performed to identify changes that reflect patient outcomes.

OBJECTIVES

To identify differentially expressed proteins associated with patient outcomes and to explore the use of imaging mass spectrometry as a clinical tool to identify clinically relevant proteins.

DESIGN

Two-dimensional separation of digested peptides generated from 43 specimens with high-resolution mass spectrometry identified proteins associated with disease-specific death, distant metastasis, and loco-regional recurrence. RNA expressions had been correlated to protein levels to test transcriptional regulation of clinically relevant proteins. Imaging mass spectrometry explored an alternative platform for assessing clinically relevant proteins that would complement surgical pathologic diagnosis.

RESULTS

Seventy-two peptide features were found to be associated with 3 patient outcomes: disease-specific death (9), distant metastasis (16), and loco-regional recurrence (39); 8 of them were associated with multiple outcomes. Functional ontology revealed major changes in cell adhesion and calcium binding. Thirteen RNAs showed strong correlation with their encoded proteins, implying transcriptional control. Reduction of DSP, PKP1, and TRIM29 was associated with significantly shorter time to onset of distant metastasis. Reduction of PKP1 and TRIM29 correlated with poorer disease-specific survival. Additionally, S100A8 and S100A9 reductions were verified for their association with poor prognosis using imaging mass spectrometry, a platform more adaptable for use with surgical pathology.

CONCLUSIONS

Using global proteomic analysis, we have identified proteins associated with clinical outcomes. The list of clinically relevant proteins observed will provide a means to develop clinical assays for prognosis and optimizing treatment selection.

Movers and shakers: cell cytoskeleton in cancer metastasis

Metastasis is responsible for the greatest number of cancer deaths. Metastatic disease, or the movement of cancer cells from one site to another, is a complex process requiring dramatic remodelling of the cell cytoskeleton. The various components of the cytoskeleton, actin (microfilaments), microtubules (MTs) and intermediate filaments, are highly integrated and their functions are well orchestrated in normal cells. In contrast, mutations and abnormal expression of cytoskeletal and cytoskeletal-associated proteins play an important role in the ability of cancer cells to resist chemotherapy and metastasize. Studies on the role of actin and its interacting partners have highlighted key signalling pathways, such as the Rho GTPases, and downstream effector proteins that, through the cytoskeleton, mediate tumour cell migration, invasion and metastasis. An emerging role for MTs in tumour cell metastasis is being unravelled and there is increasing interest in the crosstalk between key MT interacting proteins and the actin cytoskeleton, which may provide novel treatment avenues for metastatic disease. Improved understanding of how the cytoskeleton and its interacting partners influence tumour cell migration and metastasis has led to the development of novel therapeutics against aggressive and metastatic disease.

LINKED ARTICLES

This article is part of a themed section on Cytoskeleton, Extracellular Matrix, Cell Migration, Wound Healing and Related Topics. To view the other articles in this section visit http://dx.doi.org/10.1111/bph.2014.171.issue-24.

Looking in the Porphyromonas gingivalis cabinet of curiosities: the microbium, the host and cancer association

The past decades of biomedical research have yielded massive evidence for the contribution of the microbiome in the development of a variety of chronic human diseases. There is emerging evidence that Porphyromonas gingivalis, a well-adapted opportunistic pathogen of the oral mucosa and prominent constituent of oral biofilms, best known for its involvement in periodontitis, may be an important mediator in the development of a number of multifactorial and seemingly unrelated chronic diseases, such as rheumatoid arthritis and orodigestive cancers. Orodigestive cancers represent a large proportion of the total malignancies worldwide, and include cancers of the oral cavity, gastrointestinal tract and pancreas. For prevention and/or enhanced prognosis of these diseases, a good understanding of the pathophysiological mechanisms and the interaction between P. gingivalis and host is much needed. With this review, we introduce the currently accumulated knowledge on P. gingivalis's plausible association with cancer as a risk modifier, and present the putative cancer-promoting cellular and molecular mechanisms that this organism may influence in the oral mucosa.

Identification of stage-specific breast markers using quantitative proteomics

Matched healthy and diseased tissues from breast cancer patients were analyzed by quantitative proteomics. By comparing proteomic profiles of fibroadenoma (benign tumors, three patients), DCIS (noninvasive cancer, three patients), and invasive ductal carcinoma (four patients), we identified protein alterations that correlated with breast cancer progression. Three 8-plex iTRAQ experiments generated an average of 826 protein identifications, of which 402 were common. After excluding those originating from blood, 59 proteins were significantly changed in tumor compared with normal tissues, with the majority associated with invasive carcinomas. Bioinformatics analysis identified relationships between proteins in this subset including roles in redox regulation, lipid transport, protein folding, and proteasomal degradation, with a substantial number increased in expression due to Myc oncogene activation. Three target proteins, cofilin-1 and p23 (increased in invasive carcinoma) and membrane copper amine oxidase 3 (decreased in invasive carcinoma), were subjected to further validation. All three were observed in phenotype-specific breast cancer cell lines, normal (nontransformed) breast cell lines, and primary breast epithelial cells by Western blotting, but only cofilin-1 and p23 were detected by multiple reaction monitoring mass spectrometry analysis. All three proteins were detected by both analytical approaches in matched tissue biopsies emulating the response observed with proteomics analysis. Tissue microarray analysis (361 patients) indicated cofilin-1 staining positively correlating with tumor grade and p23 staining with ER positive status; both therefore merit further investigation as potential biomarkers.

Identification of tumor antigens that elicit a humoral immune response in the sera of Chinese esophageal squamous cell carcinoma patients by modified serological proteome analysis

Our aim was to identify novel tumor-associated antigens from the esophageal squamous cell carcinoma (ESCC) cell line EC0156, and related autoantibodies in sera from patients with ESCC. We used modified serological proteome analysis, involving one- and two-dimensional electrophoresis, Western blot, and MALDI-TOF/TOF-MS to identify 6 ESCC-associated antigens. From these, 105 kDa heat shock protein (HSP105) and triosephosphate isomerase (TIM) were further evaluated and we determined they could induce autoantibody responses in ESCC sera and are highly expressed in ESCC tissues. Anti-HSP105 and anti-TIM autoantibodies were found in 39.1% (18/46) and 34.8% (16/46) of patients with ESCC, respectively, but only in two controls. A receiver operating characteristic curve constructed with HSP105 and TIM gave a sensitivity of 54.3% and 95% (38/40) specificity in discriminating ESCC from matched controls. Interestingly, we found that autoantibodies against TIM in ESCC serum mainly reacted with glycosylated but not deglycosylated TIM. The preliminary results suggest the potential utility of screening autoantibodies in sera for use as biomarkers for cancer diagnosis.

Non-overlapping activities of ADF and cofilin-1 during the migration of metastatic breast tumor cells

BACKGROUND

ADF/cofilin proteins are key modulators of actin dynamics in metastasis and invasion of cancer cells. Here we focused on the roles of ADF and cofilin-1 individually in the development of polarized migration of rat mammary adenocarcinoma (MTLn3) cells, which express nearly equal amounts of each protein. Small interference RNA (siRNA) technology was used to knockdown (KD) the expression of ADF and cofilin-1 independently.

RESULTS

Either ADF KD or cofilin KD caused cell elongation, a reduction in cell area, a decreased ability to form invadopodia, and a decreased percentage of polarized cells after 180 s of epidermal growth factor stimulation. Moreover, ADF KD or cofilin KD increased the rate of cell migration and the time of lamellipodia protrusion but through different mechanisms: lamellipodia protrude more frequently in ADF KD cells and are more persistent in cofilin KD cells. ADF KD cells showed a significant increase in F-actin aggregates, whereas cofilin KD cells showed a significant increase in prominent F-actin bundles and increased cell adhesion. Focal adhesion area and cell adhesion in cofilin KD cells were returned to control levels by expressing exogenous cofilin but not ADF. Return to control rates of cell migration in ADF KD cells was achieved by expression of exogenous ADF but not cofilin, whereas in cofilin KD cells, expression of cofilin efficiently rescued control migration rates.

CONCLUSION

Although ADF and cofilin have many redundant functions, each of these isoforms has functional differences that affect F-actin structures, cell adhesion and lamellipodial dynamics, all of which are important determinants of cell migration.

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.

Promoter hypermethylation of the gene encoding heat shock protein B1 in oral squamous carcinoma cells

OBJECTIVE

The mechanism responsible for the regulation of HSPB1 expression in oral squamous cell carcinoma was explored in this study.

STUDY DESIGN

The expression and the methylation status of HSPB1 in oral squamous carcinoma cells were examined using real-time reverse transcription-PCR, methylation-specific PCR and pyrosequencing.

RESULTS

HSPB1 expression was weakly expressed in oral squamous carcinoma cell lines (N = 4) as compared to that of normal human oral keratinocytes. The lower expressed HSPB1 was associated with promoter hypermethylation of the HSPB1 gene, and the expression of HSPB1 could be induced by treating the cells with a DNA methyltransferase inhibitor, RG108. Promoter hypermethylation of the HSPB1 gene was also noted in primary oral squamous carcinomas, concomitant with reduced levels of HSPB1 gene expression, as compared to those of the paired neighboring normal tissues.

CONCLUSION

Aberrant promoter hypermethylation of the HSPB1 gene may explain the reduced expression of HSPB1 noted in oral cancer cells.

EWS represses cofilin 1 expression by inducing nuclear retention of cofilin 1 mRNA

In Ewing's sarcoma family tumors (ESFTs), the proto-oncogene EWS that encodes an RNA-binding protein is fused by chromosomal translocation to the gene encoding one of the E-twenty six (ETS) family of transcription factors, most commonly friend leukemia virus integration 1 (FLI-1). Although EWS/FLI-1 chimeric proteins are necessary for carcinogenesis, additional events seem to be required for transformation to occur. We have previously reported that a protein product of an EWS mRNA target, whose expression is negatively regulated by EWS but not by EWS/FLI-1, contributes to ESFT development. However, the mechanism by which EWS represses protein expression remains to be elucidated. Here, we report that overexpression of full-length EWS repressed protein expression and induced nuclear retention of reporter mRNAs in a tethering assay. In contrast, when a mutant lacking the EWS C-terminal nuclear localization signal (classified as a PY-NLS) was expressed, reporter protein expression was upregulated, and the number of cells exporting reporter mRNA to the cytoplasm increased. EWS binds to the 3'-untranslated region in another mRNA target, cofilin 1 (CFL1), and negatively regulates the expression of CFL1. Overexpression of EWS induced nuclear retention of CFL1 mRNA. Furthermore, ESFT cell proliferation and metastatic potential were suppressed by small interfering RNA-mediated CFL1 knockdown. Together, our findings suggest that EWS induces nuclear retention of CFL1 mRNA, thereby suppressing expression of CFL1, and that CFL1 promotes development of ESFT. Targeting CFL1 might therefore provide another novel approach for treatment of this aggressive disease.

Calreticulin, an endoplasmic reticulum-resident protein, is highly expressed and essential for cell proliferation and migration in oral squamous cell carcinoma

OBJECTIVES

Oral squamous cell carcinoma (OSCC) has emerged as one of the major malignant tumors of the head and neck cancers. However, the molecular mechanism behind tumorigenesis of OSCC is not fully understood. The aim of this study was to investigate the role of calreticulin (CRT), an endoplasmic reticulum-resident protein, in OSCC cells.

MATERIALS AND METHODS

Sixteen paired samples of tumor and non-cancerous matched tissue (NCMT), six OSCC cell lines and normal human oral keratinocytes (NHOKs), and oral tissue microarray were used to reveal the expression of CRT by Western blotting and immunohistochemistry. Later, shRNA-mediated stable knockdown of CRT in OSCC cells was generated. The knockdown cell line was used to analyze cell proliferation, colony formation, anchorage-independent growth and cell migration in vitro.

RESULTS

CRT was differentially expressed in fresh tumor samples and six OSCC cell lines but not adjacent NCMTs and NHOKs. In oral tissue microarray, we showed that there was positive CRT staining in the vast majority of tumor cases (99/103), in sharp contrast to that in NCMT cases (29/92) (p<0.001). Stable knockdown of CRT in oral cancer cells resulted in significantly reduced growth rate, colony-forming capacity and anchorage-independent growth. This may be attributed to the induction of G0/G1 cell cycle arrest when CRT was depleted in the cells. Both horizontal and vertical movements of the CRT-knockdown stable line were markedly impaired. The phosphorylation levels of focal adhesion kinase (FAK), paxillin and ERK1/2 and the activity of matrix metalloproteinase-2 and -9 (MMP-2 and MMP-9) were decreased in the CRT-knockdown cells. These results suggest that CRT can regulate oral cancer cell migration through activation of the FAK signaling pathway accompanied with proteolytic degradation of the extracellular matrix (ECM) by MMP-2 and MMP-9.

CONCLUSION

Together, this study has defined a novel biological role for CRT in oral cancer. CRT is a potential biomarker and may contribute to the malignant phenotypes of OSCC cells.