Overexpression of S100A4 in pancreatic ductal adenocarcinomas is associated with poor differentiation and DNA hypomethylation

An mRNA vaccine for pancreatic cancer designed by applying in silico immunoinformatics and reverse vaccinology approaches

Pancreatic ductal adenocarcinoma is the most prevalent pancreatic cancer, which is considered a significant global health concern. Chemotherapy and surgery are the mainstays of current pancreatic cancer treatments; however, a few cases are suitable for surgery, and most of the cases will experience recurrent episodes. Compared to DNA or peptide vaccines, mRNA vaccines for pancreatic cancer have more promise because of their delivery, enhanced immune responses, and lower proneness to mutation. We constructed an mRNA vaccine by analyzing S100 family proteins, which are all major activators of receptors for advanced glycation end products. We applied immunoinformatic approaches, including physicochemical properties analysis, structural prediction and validation, molecular docking study, in silico cloning, and immune simulations. The designed mRNA vaccine was estimated to have a molecular weight of 165023.50 Da and was highly soluble (grand average of hydropathicity of -0.440). In the structural assessment, the vaccine seemed to be a well-stable and functioning protein (Z score of -8.94). Also, the docking analysis suggested that the vaccine had a high affinity for TLR-2 and TLR-4 receptors. Additionally, the molecular mechanics with generalized Born and surface area solvation analysis of the "Vaccine-TLR-2" (-141.07 kcal/mol) and "Vaccine-TLR-4" (-271.72 kcal/mol) complexes also suggests a strong binding affinity for the receptors. Codon optimization also provided a high expression level with a GC content of 47.04% and a codon adaptation index score 1.0. The appearance of memory B-cells and T-cells was also observed over a while, with an increased level of helper T-cells and immunoglobulins (IgM and IgG). Moreover, the minimum free energy of the mRNA vaccine was predicted at -1760.00 kcal/mol, indicating the stability of the vaccine following its entry, transcription, and expression. This hypothetical vaccine offers a groundbreaking tool for future research and therapeutic development of pancreatic cancer.

Medical Biology of Cancer-Associated Fibroblasts in Pancreatic Cancer

Pancreatic cancer is one of the deadliest forms of cancer with one of the lowest 5-year survival rates of all cancer types. A defining characteristic of pancreatic cancer is the existence of dense desmoplastic stroma that, when exposed to stimuli such as cytokines, growth factors, and chemokines, generate a tumor-promoting environment. Cancer-associated fibroblasts (CAFs) are activated during the progression of pancreatic cancer and are a crucial component of the tumor microenvironment (TME). CAFs are primarily pro-tumorigenic in their activated state and function as promoters of cancer invasion, proliferation, metastasis, and immune modulation. Aided by many signaling pathways, cytokines, and chemokines in the tumor microenvironment, CAFs can originate from many cell types including resident fibroblasts, mesenchymal stem cells, pancreatic stellate cells, adipocytes, epithelial cells, endothelial cells, and other cell types. CAFs are a highly heterogeneous cell type expressing a variety of surface markers and performing a wide range of tumor promoting and inhibiting functions. Single-cell transcriptomic analyses have revealed a high degree of specialization among CAFs. Some examples of CAF subpopulations include myofibrotic CAFs (myCAFs), which exhibit a matrix-producing contractile phenotype; inflammatory CAFs (iCAF) that are classified by their immunomodulating, secretory phenotype; and antigen-presenting CAFs (apCAFs), which have antigen-presenting capabilities and express Major Histocompatibility Complex II (MHC II). Over the last several years, various attempts have been undertaken to describe the mechanisms of CAF-tumor cell interaction, as well as CAF-immune cell interaction, that contribute to tumor proliferation, invasion, and metastasis. Although our understanding of CAF biology in cancer has steadily increased, the extent of CAFs heterogeneity and their role in the pathobiology of pancreatic cancer remains elusive. In this regard, it becomes increasingly evident that further research on CAFs in pancreatic cancer is necessary.

Hypermethylation in the promoter region inhibits AJAP1 expression and activates the JAK/STAT pathway to promote prostate cancer cell migration and stem cell sphere formation

BACKGROUND

AJAP1 is down-regulated in multiple cancer types and plays a suppressive role in cancer progression. However, its molecular regulatory mechanism in prostate cancer has not been reported.

METHODS

Bioinformatics methods were employed to analyze AJAP1 expression in prostate cancer tissues and its association with TNM staging. MSP and qRT-PCR were used to quantify promoter methylation and AJAP1 expression after 5-aza-20-deoxycytidine (5-AzaC) treatment. Scratch healing assay and Transwell method were adopted to analyze the effects of aberrant AJAP1 expression, 5-AzaC and AG490 on cell migration and invasion. The levels of AJAP1 protein, EMT-related and JAK/STAT pathway-related proteins were determined by Western blot. The effects of AJAP1 aberrant expression and AG490 treatment on the sphere forming ability of prostate cancer cells were analyzed by sphere formation assay.

RESULTS

This study confirmed the significant down-regulation of AJAP1 expression in prostate cancer tissues and cells, and its negative correlation with TNM staging. 5-AzaC treatment led to a significant reduction of AJAP1 methylation level and a significant upregulation of AJAP1 expression, indicating that the methylation level of AJAP1 promoter may affect the expression of AJAP1. Cell function experiments found that overexpression or decreased methylation of AJAP1 inhibited epithelial mesenchymal transition (EMT), migration, and invasion, while silencing or increased methylation of AJAP1 had the opposite functions. JAK2/STAT3 pathway inhibiting assay found that inhibition of JAK2/STAT3 pathway significantly reduced EMT, cell migration, and stem cell sphere formation in prostate cancer.

SIGNIFICANCE

Therefore, investigating the influence of aberrant AJAP1 expression on functions of prostate cancer cells is conducive to our in-depth understanding of the mechanism of prostate cancer genesis and development.

Targeting epigenetic regulation for cancer therapy using small molecule inhibitors

Cancer cells display pervasive changes in DNA methylation, disrupted patterns of histone posttranslational modification, chromatin composition or organization and regulatory element activities that alter normal programs of gene expression. It is becoming increasingly clear that disturbances in the epigenome are hallmarks of cancer, which are targetable and represent attractive starting points for drug creation. Remarkable progress has been made in the past decades in discovering and developing epigenetic-based small molecule inhibitors. Recently, epigenetic-targeted agents in hematologic malignancies and solid tumors have been identified and these agents are either in current clinical trials or approved for treatment. However, epigenetic drug applications face many challenges, including low selectivity, poor bioavailability, instability and acquired drug resistance. New multidisciplinary approaches are being designed to overcome these limitations, e.g., applications of machine learning, drug repurposing, high throughput virtual screening technologies, to identify selective compounds with improved stability and better bioavailability. We provide an overview of the key proteins that mediate epigenetic regulation that encompass histone and DNA modifications and discuss effector proteins that affect the organization of chromatin structure and function as well as presently available inhibitors as potential drugs. Current anticancer small-molecule inhibitors targeting epigenetic modified enzymes that have been approved by therapeutic regulatory authorities across the world are highlighted. Many of these are in different stages of clinical evaluation. We also assess emerging strategies for combinatorial approaches of epigenetic drugs with immunotherapy, standard chemotherapy or other classes of agents and advances in the design of novel epigenetic therapies.

SLC2As as diagnostic markers and therapeutic targets in LUAD patients through bioinformatic analysis

Facilitative glucose transporters (GLUTs), which are encoded by solute carrier 2A (SLC2A) genes, are responsible for mediating glucose absorption. In order to meet their higher energy demands, cancer cells are more likely than normal tissue cells to have elevated glucose transporters. Multiple pathogenic processes, such as cancer and immunological disorders, have been linked to GLUTs. Few studies, meanwhile, have been conducted on individuals with lung adenocarcinoma (LUAD) to evaluate all 14 SLC2A genes. We first identified increased protein levels of SLC2A1, SLC2A5, SLC2A6, and SLC2A9 via HPA database and downregulated mRNA levels of SLC2A3, SLC2A6, SLC2A9, and SLC2A14 by ONCOMINE and UALCAN databases in patients with LUAD. Additionally, lower levels of SLC2A3, SLC2A6, SLC2A9, SLC2A12, and SLC2A14 and higher levels of SLC2A1, SLC2A5, SLC2A10, and SLC2A11 had an association with advanced tumor stage. SLC2A1, SLC2A7, and SLC2A11 were identified as prognostic signatures for LUAD. Kaplan-Meier analysis, Univariate Cox regression, multivariate Cox regression and ROC analyses further revealed that these three genes signature was a novel and important prognostic factor. Mechanistically, the aberrant expression of these molecules was caused, in part, by the hypomethylation of SLC2A3, SLC2A10, and SLC2A14 and by the hypermethylation of SLC2A1, SLC2A2, SLC2A5, SLC2A6, SLC2A7, and SLC2A11. Additionally, SLC2A3, SLC2A5, SLC2A6, SLC2A9, and SLC2A14 contributed to LUAD by positively modulating M2 macrophage and T cell exhaustion. Finally, pathways involving SLC2A1/BUB1B/mitotic cell cycle, SLC2A5/CD86/negative regulation of immune system process, SLC2A6/PLEK/lymphocyte activation, SLC2A9/CD4/regulation of cytokine production might participate in the pathogenesis of LUAD. In summary, our results will provide the theoretical basis on SLC2As as diagnostic markers and therapeutic targets in LUAD.

S100 Proteins in Pancreatic Cancer: Current Knowledge and Future Perspectives

Pancreatic cancer (PC) is a highly malignant tumor occurring in the digestive system. Currently, there is a lack of specific and effective interventions for PC; thus, further exploration regarding the pathogenesis of this malignancy is warranted. The S100 protein family, a collection of calcium-binding proteins expressed only in vertebrates, comprises 25 members with high sequence and structural similarity. Dysregulated expression of S100 proteins is a biomarker of cancer progression and prognosis. Functionally, these proteins are associated with the regulation of multiple cellular processes, including proliferation, apoptosis, growth, differentiation, enzyme activation, migration/invasion, Ca2+ homeostasis, and energy metabolism. This review highlights the significance of the S100 family in the diagnosis and prognosis of PC and its vital functions in tumor cell metastasis, invasion and proliferation. A further understanding of S100 proteins will provide potential therapeutic targets for preventing or treating PC.

Genomic Heterogeneity of Pancreatic Ductal Adenocarcinoma and Its Clinical Impact

Pancreatic ductal adenocarcinoma (PDAC) is one of the leading causes of cancer death due to limited advances in recent years in early diagnosis and personalized therapy capable of overcoming tumor resistance to chemotherapy. In the last decades, significant advances have been achieved in the identification of recurrent genetic and molecular alterations of PDAC including those involving the KRAS, CDKN2A, SMAD4, and TP53 driver genes. Despite these common genetic traits, PDAC are highly heterogeneous tumors at both the inter- and intra-tumoral genomic level, which might contribute to distinct tumor behavior and response to therapy, with variable patient outcomes. Despite this, genetic and genomic data on PDAC has had a limited impact on the clinical management of patients. Integration of genomic data for classification of PDAC into clinically defined entities-i.e., classical vs. squamous subtypes of PDAC-leading to different treatment approaches has the potential for significantly improving patient outcomes. In this review, we summarize current knowledge about the most relevant genomic subtypes of PDAC including the impact of distinct patterns of intra-tumoral genomic heterogeneity on the classification and clinical and therapeutic management of PDAC.

S100A4 overexpression in pancreatic ductal adenocarcinoma: imaging biomarkers from whole-tumor evaluation with MRI and texture analysis

OBJECTIVE

To investigate the relationship between imaging findings and S100A4 overexpression in pancreatic ductal adenocarcinoma (PDAC) and to determine imaging biomarkers of S100A4 overexpression from whole-tumor evaluation with MRI and texture analysis.

METHODS

A total of 60 patients with pathologically confirmed PDAC were included in the study. All patients underwent preoperative abdominal contrast-enhanced MRI examination with Magnetom Aera (Siemens Healthcare, Germany, 1.5 T) at our institute. Whole-tumor evaluation including texture analysis was performed. Sections of specimens were reviewed, and the S100A4 expression status was quantitatively evaluated. Univariate and multivariate logistic regression analyses were conducted to find imaging biomarkers that could predict S100A4 overexpression.

RESULTS

Twenty-four tumors (40.0%) had negative results for S100A4 overexpression, and 36 tumors (60.0%) exhibited overexpression. After univariate and multivariate analysis, distal pancreatic duct dilatation, T₁WI_10th percentile and the enhancement rate difference between delayed phase (DP) and portal venous phase (PVP) were identified to predict S100A4 overexpression in PDAC independently (p = 0.009, 0.012 and 0.044), with odds ratios (ORs) of 0.102, 0.139 and 4.645, respectively. The area under the ROC curve (AUC) values were 0.715, 0.707 and 0.691. The AUC value of the proposed model was 0.877 with a sensitivity of 80.6% and specificity of 75.0%.

CONCLUSION

A model including distal pancreatic duct dilatation, T₁WI_10th percentile and the enhancement rate difference between the DP and PVP could predict S100A4 overexpression in PDAC as imaging biomarkers.

Absence of S100A4 in the mouse lens induces an aberrant retina-specific differentiation program and cataract

S100A4, a member of the S100 family of multifunctional calcium-binding proteins, participates in several physiological and pathological processes. In this study, we demonstrate that S100A4 expression is robustly induced in differentiating fiber cells of the ocular lens and that S100A4 (-/-) knockout mice develop late-onset cortical cataracts. Transcriptome profiling of lenses from S100A4 (-/-) mice revealed a robust increase in the expression of multiple photoreceptor- and Müller glia-specific genes, as well as the olfactory sensory neuron-specific gene, S100A5. This aberrant transcriptional profile is characterized by corresponding increases in the levels of proteins encoded by the aberrantly upregulated genes. Ingenuity pathway network and curated pathway analyses of differentially expressed genes in S100A4 (-/-) lenses identified Crx and Nrl transcription factors as the most significant upstream regulators, and revealed that many of the upregulated genes possess promoters containing a high-density of CpG islands bearing trimethylation marks at histone H3K27 and/or H3K4, respectively. In support of this finding, we further documented that S100A4 (-/-) knockout lenses have altered levels of trimethylated H3K27 and H3K4. Taken together, our findings suggest that S100A4 suppresses the expression of retinal genes during lens differentiation plausibly via a mechanism involving changes in histone methylation.

Cancer-Associated Fibroblasts: Understanding Their Heterogeneity

Simple Summary

Cancer-associated fibroblasts (CAFs) play an important contributory role in the microenvironment of tumors. They originate from different cells, have multiple pro-and anti-tumorigenic functions in tumors and their presence is variable among cancer types. Recently, there has been evidence that CAFs represent a highly heterogeneous group of cells that can now be characterized and identified at the single cell level. This review article summarizes our recent understanding of the highly heterogeneous nature of the origin, phenotype and function of CAFs and how such understanding will lead to a more precise approach to target or use CAFs and their precursor cells in the treatment of cancer.

Abstract

The tumor microenvironment (TME) plays a critical role in tumor progression. Among its multiple components are cancer-associated fibroblasts (CAFs) that are the main suppliers of extracellular matrix molecules and important contributors to inflammation. As a source of growth factors, cytokines, chemokines and other regulatory molecules, they participate in cancer progression, metastasis, angiogenesis, immune cell reprogramming and therapeutic resistance. Nevertheless, their role is not fully understood, and is sometimes controversial due to their heterogeneity. CAFs are heterogeneous in their origin, phenotype, function and presence within tumors. As a result, strategies to target CAFs in cancer therapy have been hampered by the difficulties in better defining the various populations of CAFs and by the lack of clear recognition of their specific function in cancer progression. This review discusses how a greater understanding of the heterogeneous nature of CAFs could lead to better approaches aimed at their use or at their targeting in the treatment of cancer.

S100A4/Nonmuscle Myosin IIA/p53 Axis Contributes to Aggressive Features in Ovarian High-Grade Serous Carcinoma

S100A4 is a small calcium-binding protein that exerts its biological functions by interacting with nonmuscle myosin IIA (NMIIA) and p53. Although S100A4 promotes metastasis in several tumors, little is known about its involvement in the progression of ovarian high-grade serous carcinomas (HGSCs). Herein, we focused on functional roles of the S100A4/NMIIA/p53 axis in these tumors. In HGSC cell lines harboring mutant p53, knockdown (KD) of S100A4 reduced the expression of several epithelial-mesenchymal transition/cancer stem cell markers and the ALDH1^high population, consistent with an inhibition of stemness features. S100A4-KD also increased apoptosis, decreased cell proliferation, and accelerated cell mobility. This was accompanied by increased Snail expression, which, in turn, was likely due to loss of p53 function. In contrast, specific inhibition of NMIIA by blebbistatin induced phenotypes that-with the exception of cell proliferation and mobility-were opposite to those observed in S100A4-KD cells. In clinical samples, cytoplasmic and/or nuclear interactions between S100A4, NMIIA, and mutant p53 were observed. In addition, high expression of S100A4, but not NMIIA or p53, was a significant and independent unfavorable prognostic factor in HGSC patients. These findings suggest that, via its interaction with NMIIA and p53, overexpressed S100A4 may induce epithelial-mesenchymal transition/cancer stem cell properties in HGSC and elicit several other tumor-associated phenotypes.

Role of DNA Methylation in the Resistance to Therapy in Solid Tumors

Despite the recent advances in chemotherapeutic treatments against cancer, some types of highly aggressive and invasive cancer develop drug resistance against conventional therapies, which continues to be a major problem in the fight against cancer. In recent years, studies of alterations of DNA methylome have given us a better understanding of the role of DNA methylation in the development of tumors. DNA methylation (DNAm) is an epigenetic change that promotes the covalent transfer of methyl groups to DNA. This process suppresses gene expression through the modulation of the transcription machinery access to the chromatin or through the recruitment of methyl binding proteins. DNAm is regulated mainly by DNA methyltransferases. Aberrant DNAm contributes to tumor progression, metastasis, and resistance to current anti-tumoral therapies. Aberrant DNAm may occur through hypermethylation in the promoter regions of tumor suppressor genes, which leads to their silencing, while hypomethylation in the promoter regions of oncogenes can activate them. In this review, we discuss the impact of dysregulated methylation in certain genes, which impact signaling pathways associated with apoptosis avoidance, metastasis, and resistance to therapy. The analysis of methylome has revealed patterns of global methylation, which regulate important signaling pathways involved in therapy resistance in different cancer types, such as breast, colon, and lung cancer, among other solid tumors. This analysis has provided gene-expression signatures of methylated region-specific DNA that can be used to predict the treatment outcome in response to anti-cancer therapy. Additionally, changes in cancer methylome have been associated with the acquisition of drug resistance. We also review treatments with demethylating agents that, in combination with standard therapies, seem to be encouraging, as tumors that are in early stages can be successfully treated. On the other hand, tumors that are in advanced stages can be treated with these combination schemes, which could sensitize tumor cells that are resistant to the therapy. We propose that rational strategies, which combine specific demethylating agents with conventional treatment, may improve overall survival in cancer patients.

Friend or Foe: S100 Proteins in Cancer

S100 proteins are widely expressed small molecular EF-hand calcium-binding proteins of vertebrates, which are involved in numerous cellular processes, such as Ca²⁺ homeostasis, proliferation, apoptosis, differentiation, and inflammation. Although the complex network of S100 signalling is by far not fully deciphered, several S100 family members could be linked to a variety of diseases, such as inflammatory disorders, neurological diseases, and also cancer. The research of the past decades revealed that S100 proteins play a crucial role in the development and progression of many cancer types, such as breast cancer, lung cancer, and melanoma. Hence, S100 family members have also been shown to be promising diagnostic markers and possible novel targets for therapy. However, the current knowledge of S100 proteins is limited and more attention to this unique group of proteins is needed. Therefore, this review article summarises S100 proteins and their relation in different cancer types, while also providing an overview of novel therapeutic strategies for targeting S100 proteins for cancer treatment.

Calcium Signaling Alterations Caused by Epigenetic Mechanisms in Pancreatic Cancer: From Early Markers to Prognostic Impact

Pancreatic ductal adenocarcinoma (PDAC) is an aggressive disease with high mortality rates. PDAC initiation and progression are promoted by genetic and epigenetic dysregulation. Here, we aimed to characterize the PDAC DNA methylome in search of novel altered pathways associated with tumor development. We examined the genome-wide DNA methylation profile of PDAC in an exploratory cohort including the comparative analyses of tumoral and non-tumoral pancreatic tissues (PT). Pathway enrichment analysis was used to choose differentially methylated (DM) CpGs with potential biological relevance. Additional samples were used in a validation cohort. DNA methylation impact on gene expression and its association with overall survival (OS) was investigated from PDAC TCGA (The Cancer Genome Atlas) data. Pathway analysis revealed DM genes in the calcium signaling pathway that is linked to the key pathways in pancreatic carcinogenesis. DNA methylation was frequently correlated with expression, and a subgroup of calcium signaling genes was associated with OS, reinforcing its probable phenotypic effect. Cluster analysis of PT samples revealed that some of the methylation alterations observed in the Calcium signaling pathway seemed to occur early in the carcinogenesis process, a finding that may open new insights about PDAC tumor biology.

Differential methylation landscape of pancreatic ductal adenocarcinoma and its precancerous lesions

BACKGROUND

Pancreatic cancer is one of the most lethal diseases with an incidence almost equal to the mortality. In addition to having genetic causes, cancer can also be considered an epigenetic disease. DNA methylation is the premier epigenetic modification and patterns of aberrant DNA methylation are recognized to be a common hallmark of human tumor. In the multistage carcinogenesis of pancreas starting from precancerous lesions to pancreatic ductal adenocarcinoma (PDAC), the epigenetic changes play a significant role.

DATA SOURCES

Relevant studies for this review were derived via an extensive literature search in PubMed via using various keywords such as pancreatic ductal adenocarcinoma, precancerous lesions, methylation profile, epigenetic biomarkers that are relevant directly or closely associated with the concerned area of our interest. The literature search was intensively done considering a time frame of 20 years (1998-2018).

RESULT

In this review we have highlighted the hypermethylation and hypomethylation of the precancerous PDAC lesions (pancreatic intra-epithelial neoplasia, intraductal papillary mucinous neoplasm, mucinous cystic neoplasm and chronic pancreatitis) and PDAC along with the potential biomarkers. We have also achieved the early epigenetic driver that leads to progression from precancerous lesions to PDAC. A bunch of epigenetic driver genes leads to progression of precancerous lesions to PDAC (ppENK, APC, p14/5/16/17, hMLH1 and MGMT) are also documented. We summarized the importance of these observations in therapeutics and diagnosis of PDAC hence identifying the potential use of epigenetic biomarkers in epigenetic targeted therapy. Epigenetic inactivation occurs by hypermethylation of CpG islands in the promoter regions of tumor suppressor genes. We listed all hyper- and hypomethylation of CpG islands of several genes in PDAC including its precancerous lesions.

CONCLUSIONS

The concept of the review would help to understand their biological effects, and to determine whether they may be successfully combined with other epigenetic drugs. However, we need to continue our research to develop more specific DNA-demethylating agents, which are the targets for hypermethylated CpG methylation sites.

The expression patterns of immune response genes in the Peripheral Blood Mononuclear cells of pregnant women presenting with subclinical or clinical HEV infection are different and trimester-dependent: A whole transcriptome analysis

Hepatitis E is an enteric disease highly prevalent in the developing countries. The basis for high mortality among pregnant hepatitis E patients remains unclear. Importantly, a large proportion of infected pregnant women present with subclinical infection as well. In order to understand the possible mechanisms influencing clinical presentation of hepatitis E in pregnant women, we explored a system biology approach. For this, PBMCs from various categories were subjected to RNAseq analysis. These included non-pregnant (NPR, acute and convalescent phases) and pregnant (PR, 2^nd and 3^rd trimesters, acute phase and subclinical HEV infections) patients and corresponding healthy controls. The current study deals with immune response genes.

In contrast to exclusive up-regulation of nonspecific, early immune response transcripts in the NPR patients, the PR patients exhibited broader and heightened expression of genes associated with innate as well as adaptive T and B cell responses. The study identified for the first time (1) inverse relationship of immunoglobulin (Ig) genes overexpression and (2) association of differential expression of S100 series genes with disease presentation. The data suggests possible involvement of TLR4 and NOD1 in pregnant patients and alpha defensins in all patient categories suggesting a role in protection. Induction of IFNγ gene was not detected during the acute phase irrespective of pregnancy. Association of response to vitamin D, transcripts related to NK/NKT and regulatory T cells during subclinical infection are noteworthy.

The data obtained here could be correlated with several studies reported earlier in hepatitis E patients suggesting utility of PBMCs as an alternate specimen. The extensive, informative data provided here for the first time should form basis for future studies that will help in understanding pathogenesis of fulminant hepatitis E.

Relationship between S100A4 protein expression and pre-operative serum CA19.9 levels in pancreatic carcinoma and its prognostic significance

BACKGROUND

Pancreatic carcinoma (PC) is one of the most lethal malignancies, and its poor prognosis is strongly associated with invasion and metastasis. CA19.9 is considered to be the most sensitive serum marker for PC in clinical practice; however, the detection of CA19.9 in PC has a certain false positive and false negative rate. The expression of the calcium-binding protein S100A4 has been reported to be associated with poor prognosis in various cancers. This study aimed to investigate the relationship between S100A4 and CA19.9 and its prognostic significance in PC.

METHODS

We performed immunohistochemical staining for S100A4 in formalin-fixed, paraffin-embedded blocks of 128 PC tissues. The levels of S100A4 expression and pre-operative serum CA19.9 were correlated with clinicopathological parameters. The possible correlation between S100A4 protein expression and pre-operative serum CA19.9 levels were evaluated using the chi-square test and Spearman correlation. Survival was assessed by Kaplan-Meier analysis together with a single variable or multivariate Cox analysis.

RESULTS

A significant positive correlation between S100A4 expression and pre-operative serum CA19.9 level was observed in PC tissues (ρ = 0.202, P = 0.022). The co-expression of both proteins correlated significantly with tumor differentiation (ρ = - 0.280, P = 0.001), TNM stage (ρ = - 0.389, P = 0.000), and lymph node metastasis (ρ = 0.254, P = 0.008). Upregulation of S100A4 was identified as a significant, independent predictor of poor overall survival (P = 0.000). Moreover, higher serum CA19.9 levels (≥ 35 U/mL) were also recognized as an independent predictor of inferior overall survival (P = 0.001). Additionally, upregulation of S100A4 and higher pre-operative serum CA19.9 levels (≥ 35 U/mL) in patients with PC contributed to a significant decrease in overall survival (P = 0.000).

CONCLUSIONS

The expression levels of S100A4 in PC tissues were positively correlated with pre-operative serum CA19.9 levels. S100A4 expression and pre-operative serum CA19.9 levels were significant, independent prognostic factors for the overall survival of patients with PC. S100A4 expression/pre-operative serum CA19.9 levels may prove useful as dual prognostic biomarkers for PC. Analysis of CA19.9 in combination with S100A4 can better predict the prognosis of PC.

The role of DNA methylation in ageing and cancer

The aim of the present review paper is to survey the literature related to DNA methylation, and its association with cancer and ageing. The review will outline the key factors, including diet, which modulate DNA methylation. Our rationale for conducting this review is that ageing and diseases, including cancer, are often accompanied by aberrant DNA methylation, a key epigenetic process, which is crucial to the regulation of gene expression. Significantly, it has been observed that with age and certain disease states, DNA methylation status can become disrupted. For instance, a broad array of cancers are associated with promoter-specific hypermethylation and concomitant gene silencing. This review highlights that hypermethylation, and gene silencing, of the EN1 gene promoter, a crucial homeobox gene, has been detected in various forms of cancer. This has led to this region being proposed as a potential biomarker for diseases such as cancer. We conclude the review by describing a recently developed novel electrochemical method that can be used to quantify the level of methylation within the EN1 promoter and emphasise the growing trend in the use of electrochemical techniques for the detection of aberrant DNA methylation.

Epigenetic upregulation of ARL4C, due to DNA hypomethylation in the 3'-untranslated region, promotes tumorigenesis of lung squamous cell carcinoma

ADP-ribosylation factor (ARF)-like 4c (ARL4C) expression, induced by a combination of Wnt/β-catenin and EGF/Ras signaling, has been demonstrated to form epithelial morphogenesis. ARL4C overexpression, due to Wnt/β-catenin and EGF/Ras signaling alterations, was involved in tumorigenesis. It was also reported that ARL4C expression correlates with DNA hypomethylation in the 3’-untranslated region (UTR) of ARL4C gene during lymphogenesis. The current study was conducted to investigate the expression and functions of ARL4C due to DNA hypomethylation in lung and tongue cancers. Immunohistochemical analyses of tissue specimens obtained from lung and tongue squamous cell carcinoma (SCC) patients revealed that ARL4C is not observed in non-tumor regions, but is strongly expressed at high frequencies in tumor lesions. Although inhibition of Wnt/β-catenin or Ras/MAP kinase signaling did not decrease ARL4C expression in NCI-H520 lung SCC cells, ARL4C DNA was clearly hypomethylated in the 3’-UTR. Ten-eleven translocation methylcytosine dioxygenase (TET) enzyme, which mediates DNA demethylation, was highly expressed in NCI-H520 cells. Knockout of TET family proteins (TET1-3) in NCI-H520 cells reduced 5-hydroxymethylcytosine (5hmC) levels and promoted DNA methylation in the 3’-UTR, leading to the decrease in ARL4C expression and ARL4C-mediated cellular migration. In tumor lesions of ARL4C-positive lung SCC, 5hmC was frequently detected and DNA methylation in the 3’-UTR of ARL4C gene was lower than in non-tumor regions, which were consistent with the Cancer Genome Atlas dataset. These results suggest that ARL4C is expressed due to hypomethylation in the 3’-UTR for certain types of cancers and that ARL4C methylation status is involved in cancer cell function.

The annexin A2 system and angiogenesis

The formation of new blood vessels from pre-existing vasculature, the process known as angiogenesis, is highly regulated by pro- and anti-angiogenic signaling molecules including growth factors and proteases. As an endothelial cell-surface co-receptor for plasminogen and tissue plasminogen activator, the annexin A2 (ANXA2) complex accelerates plasmin generation and facilitates fibrinolysis. Plasmin can subsequently activate a downstream proteolytic cascade involving multiple matrix metalloproteinases. Thus, in addition to maintaining blood vessel patency, the ANXA2 complex can also promote angiogenesis via its pro-fibrinolytic activity. The generation of ANXA2-deficient mice allowed us to first observe the pro-angiogenic role of ANXA2 in vivo. Further investigations have provided additional details regarding the mechanism for ANXA2 regulation of retinal and corneal angiogenesis. Other studies have reported that ANXA2 supports angiogenesis in specific tumor-related settings. Here, we summarize results from in vivo studies that illustrate the pro-angiogenic role of ANXA2, and discuss the critical questions that may lead to an advanced understanding of the molecular mechanisms for ANXA2-mediated angiogenesis. Finally, highlights from studies on ANXA2-interacting agents offer potential therapeutic opportunities for the application of ANXA2-centered pharmaceuticals in angiogenesis-related disorders.

Knockdown of S100A4 blocks growth and metastasis of anaplastic thyroid cancer cells in vitro and in vivo

Anaplastic thyroid cancer (ATC) is a locally aggressive type of thyroid tumor with high rate of distant metastases. It is often incurable because it does not respond to radioiodine, radiotherapy, or chemotherapy. With conventional treatment, the median survival is about 6 months; therefore, new treatment options are needed. S100A4 is a calcium-binding protein related to the metastatic potential of carcinoma. Previous study has found S100A4 was overexpressed in human papillary thyroid carcinomas (PTC) tissues, and overexpression of S100A4 is associated with thyroid tumour invasion and metastasis. In the present study, we first examined S100A4 protein expression in 14 ATC tissues, 20 PTC tissues and 14 normal thyroid tissue by immunohistochemistry analysis. We then knocked down of S100A4 expression by RNA interference (S100A4 siRNA) and investigated its effects on growth and metastasis in two human ATC cell lines 8505C (BRAFV600E) and Cal-62 (BRAFwt) in vitro and in vivo. S100A4 and BRAFV600E protein expression was evaluated by western blot assay and immunohistochemistry analysis. Using immunohistochemistry, we found that high levels of S100A4 were detected in ATC specimens and PTC specimens. No S100A4 staining was observed in normal thyroid tissues. S100A4 siRNA significantly decreased proliferation and increased apoptosis, and inhibited the invasive potential of the two cells in vitro. In addition, S100A4 siRNA could effectively inhibit BRAFV600E expression in the 8505C cells, and treatment with 100 ng/ml human recombinant BRAF V600E in S100A4 siRNA/8505C cells could partly restore its proliferative and invasive ability. Results of implantation in vivo showed S100A4 shRNA could significantly inhibit abdominal cavity metastasis and tumor growth in vivo. Furthermore, knockdown of S100A4 has significant role on invasion, metastasis and growth inhibition in the 8505C cells than that of in the Cal-62 cells. These results support the hypothesis that S100A4 contributes significantly to growth and metastasis, and that down-regulation of S100A4 expression decreases the metastatic potential of ATC cells. Furthermore, down-regulation of S100A4 expression is more marked in BRAFV600E cells than that of in the BRAFwt cells.

Cellular Distribution and Gene Expression Pattern of Metastasin (S100A4), Calgranulin A (S100A8), and Calgranulin B (S100A9) in Oral Lesions as Markers for Molecular Pathology

The objective of this study was to analyze cellular localization and expression levels of oncologic relevant members of the S100 family in common oral lesions.Biopsies of various oral lesions were analyzed. S100A4 showed a higher expression rate in leukoplakias and oral squamous cell carcinomas. Transcript levels of S100A8 and S100A9 were significantly decreased in malignant OSCCs. A correlation could be drawn between the expression levels of these genes and the pathological characteristics of the investigated lesions. S100A4, A8, and A9 proteins represent promising marker genes to evaluate the risk potential of suspicious oral lesions in molecular pathology.

S100A4 promotes endometrial cancer progress through epithelial-mesenchymal transition regulation

Epithelial-mesenchymal transition (EMT) is a major cause of endometrial cancer (EC) to initiate invasion and metastasis. S100A4, a calcium-binding protein, is implicated in multistage of tumorigenesis and tumor progression. The correlation between S100A4 and EMT in EC is still unclear. This study was aimed to clarify the role of S100A4 in EC and the relationship between S100A4 expression and EMT markers. S100A4, E-cadherin, and vimentin were detected in tissues of EC patients (n=50) by immunohistochemistry. The impact of S100A4 on EC cell proliferation, migration and invasion was investigated via RNA interference, and the correlation between S100A4 and EMT markers were also explored. The results showed that S100A4 was significantly increased in epithelial cells of EC compared with the normal endometrium (P<0.05), also S100A4 level was positively related to age (P=0.021), histological grade (P<0.001), and lymph node metastasis (P<0.001). Additionally, silencing of S100A4 remarkably attenuated EC cell migration and invasion. Significant morphological change accompanied with the downregulation of EMT markers, E-cadherin and vimentin were also observed. Aberrant S100A4 expression may predict EC progression and play an important role in regulating EC cell invasion through EMT regulation. Hence, S100A4 is a promising therapeutic target.

Silencing of S100A4, a metastasis-associated protein, inhibits retinal neovascularization via the downregulation of BDNF in oxygen-induced ischaemic retinopathy

BackgroundTo investigate the underlying mechanism of S100A4 function and whether it has a role in retinal neovascularization (RNV) in a mouse model of oxygen-induced retinopathy (OIR).MethodsRetinas from a mouse model of OIR were treated with and without an intravitreous injection of adenoviral-S100A4-RNAi or adenoviral green fluorescence protein (GFP) at postnatal day 12 (P12). At P17, the efficacy of adenoviral gene transfer was assessed using fluorescence microscopy and western blot analysis. RNV was evaluated by whole-mount immunofluorescence staining of the mouse retina and by counting the number of pre-retinal neovascular cells. Protein and mRNA expression levels of S100A4, brain-derived growth factor (BDNF), and vascular endothelial growth factor (VEGF) were measured using western blot analysis and real-time PCR.ResultsRetinal S100A4 levels were positively correlated with the progression of RNV. In the OIR-S100A4-RNAi group, both protein and mRNA expression levels of S100A4 in the retina significantly decreased at P17 compared with those in the OIR group. Ad-S100A4-RNAi transfer was clearly demonstrated by GFP fluorescence in many layers of the retina 5 days after the Ad-S100A4-RNAi transfer. Whole-mount immunofluorescence staining of the retina and quantification of the pre-retinal neovascular cells demonstrated that RNV was significantly inhibited. Meanwhile, the levels of the transcription and translation of BDNF, VEGF, and hypoxia-inducible factor-1α (HIF-1α) significantly decreased in the OIR-S100A4-RNAi group.ConclusionsAd-S100A4-RNAi transfer ameliorates RNV. The related mechanism may involve silencing S100A4 to decrease the activation of BDNF, which downregulates VEGF expression via HIF-1α. This finding could provide a new therapeutic target for the treatment of ocular neovascularization diseases.

DNA Hypomethylation Contributes to Genomic Instability and Intestinal Cancer Initiation

Intestinal cancer is a heterogeneous disease driven by genetic mutations and epigenetic changes. Approximately 80% of sporadic colorectal cancers are initiated by mutation and inactivation of the adenomatous polyposis coli (APC) gene, which results in unrestrained intestinal epithelial growth and formation of adenomas. Aberrant DNA methylation promotes cancer progression by the inactivation of tumor suppressor genes via promoter methylation. In addition, global DNA hypomethylation is often seen before the formation of adenomas, suggesting that it contributes to neoplastic transformation. Previous studies employed mice with a hypomorphic mutation in DNA methyltransferase 1 (Dnmt1), which exhibited constitutive global DNA hypomethylation and decreased tumorigenesis in the Apc(Min/+) mouse model of intestinal cancer. However, the consequences of intestinal epithelial-specific acute hypomethylation during Apc(Min/+) tumor initiation have not been reported. Using temporally controlled intestinal epithelial-specific gene ablation, we show that total loss of Dnmt1 in the Apc(Min/+) mouse model of intestinal cancer causes accelerated adenoma initiation. Deletion of Dnmt1 precipitates an acute response characterized by hypomethylation of repetitive elements and genomic instability, which surprisingly is followed by remethylation with time. Two months post-Dnmt1 ablation, mice display increased macroadenoma load, consistent with a role for Dnmt1 and DNA methylation in maintaining genomic stability. These data suggest that DNA hypomethylation plays a previously unappreciated role in intestinal adenoma initiation. Cancer Prev Res; 9(7); 534-46. ©2016 AACRSee related article by Lee and Laird, p. 509.

PTCSC3 Is Involved in Papillary Thyroid Carcinoma Development by Modulating S100A4 Gene Expression

CONTEXT

We previously showed that a long noncoding RNA gene, PTCSC3, located close to the variant rs944289 that predisposes to papillary thyroid carcinoma (PTC) might target the S100A4 gene.

OBJECTIVE

The aim was to investigate the impact of PTCSC3 on S100A4 expression and its role in cancer development.

DESIGN

S100A4 abundance was analyzed by quantitative PCR (qPCR) in unaffected and tumor tissue from n = 73 PTC patients. The expression of PTCSC3 and S100A4 was studied in BCPAP and TPC-1 cell lines with forced expression of PTCSC3 by qPCR. Expression of S100A4 target genes (VEGF and MMP-9) was studied in the BCPAP cell line with forced expression of PTCSC3 by qPCR, reverse transcriptase PCR, and Western blot. The impact of PTCSC3 on BCPAP motility and invasiveness was analyzed by the Transwell and Matrigel assays, respectively.

SETTING

This was a laboratory-based study using cells from clinical samples and thyroid cancer cell lines.

MAIN OUTCOME AND MEASURE

We aimed to find evidence for a link between the expression of PTCSC3 and thyroid carcinogenesis.

RESULTS

Expression data from PTC cell lines pinpointed S100A4 as the most significantly downregulated gene in the presence of PTCSC3. S100A4 was upregulated in tumor tissue (P = 9.33 × 10(-7)) while PTCSC3 was strongly downregulated (P = 2.2 × 10(-16)). S100A4 transcription was moderately correlated with PTCSC3 expression in unaffected thyroid tissue (r = 0.429, P = .0001), and strongly in unaffected tissue of patients with the risk allele of rs944289 (r = 0.685, P = 7.88 × 10(-5)). S100A4, VEGF, and MMP-9 were suppressed in the presence of PTCSC3 (P = .0051, P = .0090, and P =.0037, respectively). PTC cells expressing PTCSC3 showed reduction in motility and invasiveness (P = 4.52 × 10(-5) and P = 1.0 × 10(-4), respectively).

CONCLUSIONS

PTCSC3 downregulates S100A4, leading to a reduction in cell motility and invasiveness. We propose that PTCSC3 impacts PTC predisposition and carcinogenesis through the S100A4 pathway.

DNA methylation profiles distinguish different subtypes of gastroenteropancreatic neuroendocrine tumors

AIM

Most studies have considered gastroenteropancreatic neuroendocrine tumors (GEP-NETs) as a homogenous group of samples or distinguish only gastrointestinal from pancreatic endocrine tumors. This article investigates if DNA methylation patterns could distinguish subtypes of GEP-NETs.

MATERIALS & METHODS

The DNA methylation level of 807 cancer-related genes was investigated in insulinomas, gastrinomas, non-functioning pancreatic endocrine tumors and small intestine endocrine tumors.

RESULTS

DNA methylation patterns were found to be tumor type specific for each of the pancreatic tumor subtypes and identified two distinct methylation-based groups in small intestine endocrine tumors. Differences of DNA methylation levels were validated by pyrosequencing for 20 candidate genes and correlated with differences at the transcriptional level for four candidate genes.

CONCLUSION

The heterogeneity of DNA methylation patterns in the different subtypes of gastroenteropancreatic neuroendocrine tumors suggests different underlying pathways and, therefore, these tumors should be considered as distinct entities in molecular and clinical studies.

Overexpression of S100A4 as a biomarker of metastasis and recurrence in oral squamous cell carcinoma

S100A4, a biomarker of epithelial mesenchymal transition (EMT), plays an important role in invasion and metastasis by promoting cancer cell motility. In oral squamous cell carcinoma (OSCC), metastasis results in 90% of cancer associated mortality.

S100A4 hypomethylation affects epithelial-mesenchymal transition partially induced by LMP2A in nasopharyngeal carcinoma

To identify cellular target genes involved in NPC cell invasion and metastasis, gene expression profiles of CNE-1 cells with or without ectopic LMP2A expression were compared by using the metastatic gene array. S100 calcium binding protein A4 (S100A4) was the highest increased one among these genes both in mRNA and protein levels of NPC cells. Moreover, S100A4 was upregulated in LMP2A-positive NPC tissues. We found that CNE-1-S100A4 showed significantly increased invasion ability as compared to the controls both in vitro and in vivo, which indicated that S100A4 induced EMT occurrence and promoted metastasis. Notably, the DNA hypomethylation of S100A4 was found in LMP2A-positive NPC tissues. Besides, inhibition of DNA methyltransferases via 5-Aza-dC stimulated the expression of S100A4 in the cells without ectopic LMP2A expression. The methylation changes were confirmed by methylation specific PCR (MSP), suggesting that LMP2A ectopic expression led to the demethylation of S100A4 promoter. These results demonstrated that LMP2A-induced hypomethylation participated in regulating S100A4 expression in NPC. Our findings provide an evidence for the emerging notion that hypomethylation and activation of correlated genes are crucial for metastasis progression in cancer. © 2015 Wiley Periodicals, Inc.

DNA demethylation and invasive cancer: implications for therapeutics

One of the hallmarks of cancer is aberrant DNA methylation, which is associated with abnormal gene expression. Both hypermethylation and silencing of tumour suppressor genes as well as hypomethylation and activation of prometastatic genes are characteristic of cancer cells. As DNA methylation is reversible, DNA methylation inhibitors were tested as anticancer drugs with the idea that such agents would demethylate and reactivate tumour suppressor genes. Two cytosine analogues, 5-azacytidine (Vidaza) and 5-aza-2'-deoxycytidine, were approved by the Food and Drug Administration as antitumour agents in 2004 and 2006 respectively. However, these agents might cause activation of a panel of prometastatic genes in addition to activating tumour suppressor genes, which might lead to increased metastasis. This poses the challenge of how to target tumour suppressor genes and block cancer growth with DNA-demethylating drugs while avoiding the activation of prometastatic genes and precluding the morbidity of cancer metastasis. This paper reviews current progress in using DNA methylation inhibitors in cancer therapy and the potential promise and challenges ahead.

Next-generation sequencing reveals novel differentially regulated mRNAs, lncRNAs, miRNAs, sdRNAs and a piRNA in pancreatic cancer

Background

Previous studies identified microRNAs (miRNAs) and messenger RNAs with significantly different expression between normal pancreas and pancreatic cancer (PDAC) tissues. Due to technological limitations of microarrays and real-time PCR systems these studies focused on a fixed set of targets. Expression of other RNA classes such as long intergenic non-coding RNAs or sno-derived RNAs has rarely been examined in pancreatic cancer. Here, we analysed the coding and non-coding transcriptome of six PDAC and five control tissues using next-generation sequencing.

Results

Besides the confirmation of several deregulated mRNAs and miRNAs, miRNAs without previous implication in PDAC were detected: miR-802, miR-2114 or miR-561. SnoRNA-derived RNAs (e.g. sno-HBII-296B) and piR-017061, a piwi-interacting RNA, were found to be differentially expressed between PDAC and control tissues. In silico target analysis of miR-802 revealed potential binding sites in the 3′ UTR of TCF4, encoding a transcription factor that controls Wnt signalling genes. Overexpression of miR-802 in MiaPaCa pancreatic cancer cells reduced TCF4 protein levels. Using Massive Analysis of cDNA Ends (MACE) we identified differential expression of 43 lincRNAs, long intergenic non-coding RNAs, e.g. LINC00261 and LINC00152 as well as several natural antisense transcripts like HNF1A-AS1 and AFAP1-AS1. Differential expression was confirmed by qPCR on the mRNA/miRNA/lincRNA level and by immunohistochemistry on the protein level.

Conclusions

Here, we report a novel lncRNA, sncRNA and mRNA signature of PDAC. In silico prediction of ncRNA targets allowed for assigning potential functions to differentially regulated RNAs.

Electronic supplementary material

The online version of this article (doi:10.1186/s12943-015-0358-5) contains supplementary material, which is available to authorized users.

S100A4 promotes pancreatic cancer progression through a dual signaling pathway mediated by Src and focal adhesion kinase

S100A4 expression is associated with poor clinical outcomes of patients with pancreatic cancer. The effects of loss or gain of S100A4 were examined in pancreatic cancer cell lines. S100A4 downregulation remarkably reduces cell migration and invasion, inhibits proliferation, and induces apoptosis in pancreatic tumor cells. S100A4 downregulation results in significant cell growth inhibition and apoptosis in response to TGF-β1, supporting a non-canonical role of S100A4 in pancreatic cancer. The role of S100A4 in tumor progression was studied by using an orthotopic human pancreatic cancer xenograft mouse model. Tumor mass is remarkably decreased in animals injected with S100A4-deficient pancreatic tumor cells. P27^Kip1 expression and cleaved caspase-3 are increased, while cyclin E expression is decreased, in S100A4-deficient pancreatic tumors in vivo. S100A4-deficient tumors have lower expression of vascular endothelial growth factor, suggesting reduced angiogenesis. Biochemical assays revealed that S100A4 activates Src and focal adhesion kinase (FAK) signaling events, and inhibition of both kinases is required to maximally block the tumorigenic potential of pancreatic cancer cells. These findings support that S100A4 plays an important role in pancreatic cancer progression in vivo and S100A4 promotes tumorigenic phenotypes of pancreatic cancer cells through the Src-FAK mediated dual signaling pathway.

Increased expression levels of S100A4 associated with hypoxia-induced invasion and metastasis in esophageal squamous cell cancer

Here, we explored the expression of S100A4 in esophageal squamous cell cancer (ESCC) tissues and investigated its role in hypoxia-induced invasion and metastasis in ESCC cell lines EC-1 and EC-9706. Immunohistochemistry analysis demonstrated that S100A4 was overexpressed in human ESCC tissues especially in ESCC tissues with deep invasion and lymph node metastasis. Hypoxia-induced S100A4 overexpression was observed in EC-1 and EC-9706 cells, in which it was associated with invasion and metastasis. Furthermore, we used EC-1 and EC-9706 cells again to upregulate or knockdown the expression S100A4 to investigate the mechanism role of S100A4 in hypoxia-induced invasion and metastasis in ESCC cells. And the results showed that S100A4 played an important role in promoting the invasion and metastasis of EC-1 and EC-9706 cells under hypoxia. Therefore, S100A4 overexpression might be an important mechanism by which hypoxia induced invasion and metastasis, and S100A4 could also be a potential target for the treatment of ESCC.

Epigenetic therapy as a novel approach in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is the most common type of liver malignancy and one with high fatality. Its 5-year survival rate remains low and thus, there is a need for improvement of current treatment strategies as well as development of novel targeted methodologies in order to optimize existing therapeutic protocols. To this end, only recently, it was discovered that its pathophysiology also involves epigenetic alterations in DNA methylation, histone modifications and/or non-coding microRNA patterns. Unlike genetic events, epigenetic alterations are reversible and thus potentially considered to be an alternative option in cancer treatment protocols. In this review, we describe the general characteristics and resulted major alterations of the epigenetic machinery as well as current state of progress of epigenetic therapy (via different single or combinatorial experimental approaches) in HCC.

Identification of pancreatic cancer-associated tumor antigen from HSP-enriched tumor lysate-pulsed human dendritic cells

PURPOSE

Vaccine strategies utilizing dendritic cells (DCs) to elicit anti-tumor immunity are the subject of intense research. Although we have shown that DCs pulsed with heat-treated tumor lysate (HTL) induced more potent anti-tumor immunity than DCs pulsed with conventional tumor lysate (TL), the underlying molecular mechanism is unclear. In order to explore the molecular basis of this approach and to identify potential antigenic peptides from pancreatic cancer, we analyzed and compared the major histocompatibility complex (MHC) ligands derived from TL- and HTL-pulsed dendritic cells by mass spectrophotometry.

MATERIALS AND METHODS

Human monocyte-derived dendritic cells were pulsed with TL or HTL prior to maturation induction. To delineate differences of MHC-bound peptide repertoire eluted from DCs pulsed with TL or HTL, nanoflow liquid chromatography-electrospray ionization-tandem mass spectrometry (nLC-ESI-MS-MS) was employed.

RESULTS

HTL, but not TL, significantly induced DC function, assessed by phenotypic maturation, allostimulation capacity and IFN-γ secretion by stimulated allogeneic T cells. DCs pulsed with TL or HTL displayed pancreas or pancreatic cancer-related peptides in context of MHC class I and II molecules. Some of the identified peptides had not been previously reported as expressed in pancreatic cancer or cancer of other tissue types.

CONCLUSION

Our partial lists of MHC-associated peptides revealed the differences between peptide profiles eluted from HTL-and TL-loaded DCs, implying that induced heat shock proteins in HTL chaperone tumor-derived peptides enhanced their delivery to DCs and promoted cross-presentation by DC. These findings may aid in identifying novel tumor antigens or biomarkers and in designing future vaccination strategies.

A meta analysis of pancreatic microarray datasets yields new targets as cancer genes and biomarkers

The lack of specific symptoms at early tumor stages, together with a high biological aggressiveness of the tumor contribute to the high mortality rate for pancreatic cancer (PC), which has a five year survival rate of less than 5%. Improved screening for earlier diagnosis, through the detection of diagnostic and prognostic biomarkers provides the best hope of increasing the rate of curatively resectable carcinomas. Though many serum markers have been reported to be elevated in patients with PC, so far, most of these markers have not been implemented into clinical routine due to low sensitivity or specificity. In this study, we have identified genes that are significantly upregulated in PC, through a meta-analysis of large number of microarray datasets. We demonstrate that the biological functions ascribed to these genes are clearly associated with PC and metastasis, and that that these genes exhibit a strong link to pathways involved with inflammation and the immune response. This investigation has yielded new targets for cancer genes, and potential biomarkers for pancreatic cancer. The candidate list of cancer genes includes protein kinase genes, new members of gene families currently associated with PC, as well as genes not previously linked to PC. In this study, we are also able to move towards developing a signature for hypomethylated genes, which could be useful for early detection of PC. We also show that the significantly upregulated 800+ genes in our analysis can serve as an enriched pool for tissue and serum protein biomarkers in pancreatic cancer.

S100A4 is frequently overexpressed in lung cancer cells and promotes cell growth and cell motility

S100A4, a small calcium-binding protein belonging to the S100 protein family, is commonly overexpressed in a variety of tumor types and is widely accepted to associate with metastasis by regulating the motility and invasiveness of cancer cells. However, its biological role in lung carcinogenesis is largely unknown. In this study, we found that S100A4 was frequently overexpressed in lung cancer cells, irrespective of histological subtype. Then we performed knockdown and forced expression of S100A4 in lung cancer cell lines and found that specific knockdown of S100A4 effectively suppressed cell proliferation only in lung cancer cells with S100A4-overexpression; forced expression of S100A4 accelerated cell motility only in S100A4 low-expressing lung cancer cells. PRDM2 and VASH1, identified as novel upregulated genes by microarray after specific knockdown of S100A4 in pancreatic cancer, were also analyzed, and we found that PRDM2 was significantly upregulated after S100A4-knockdown in one of two analyzed S100A4-overexpressing lung cancer cells. Our present results suggest that S100A4 plays an important role in lung carcinogenesis by means of cell proliferation and motility by a pathway similar to that in pancreatic cancer.

CD24 and S100A4 expression in resectable pancreatic cancers with earlier disease recurrence and poor survival

OBJECTIVES

The objectives of this study were to study the expression status of markers associated with epithelial-to-mesenchymal transition (EMT) and metastasis in pancreatic ductal adenocarcinomas (PDACs) and to explore the prognostic value of these markers.

METHODS

Immunohistochemical stains for CD24, CD44, E-cadherin, N-cadherin, Snail, S100A4, Vimentin, urokinase-type plasminogen activator receptor, Ezrin, and matrix metalloproteinase 2 were performed on 67 resected PDACs.

RESULTS

Proteins associated with EMT and metastasis were more frequently expressed in PDACs with poor differentiation, higher tumor stage, and lymphatic and perineural invasion. CD24 expression was associated with frequent expression of EMT markers (CD44 [P = 0.004], S100A4 [P < 0.001], Vimentin [P = 0.022], urokinase-type plasminogen activator receptor [P = 0.002], and Ezrin [P = 0.010]). CD24 and S100A4 expressions in PDAC were significant prognostic factors for early tumor recurrence (hazard risk [HR], 5.185 and 2.490, P = 0.048 and 0.009, respectively) and poor survival (HR, 11.977 and 3.202, P = 0.006 and 0.004, respectively). In addition, the interaction between CD24 and S100A4 expression status was a significant prognostic factor for poor survival (HR, 18.518, P = 0.003).

CONCLUSIONS

The expression of markers of EMT and metastasis in PDACs was significantly associated with pathologic features of aggressiveness. CD24 and S100A4 expressions were significant predictors of poor survival; thus, immunohistochemistry for these markers in resected specimens may help to identify PDAC patients with a poor prognosis.

S100 protein family in human cancer

S100 protein family has been implicated in multiple stages of tumorigenesis and progression. Among the S100 genes, 22 are clustered at chromosome locus 1q21, a region frequently rearranged in cancers. S100 protein possesses a wide range of intracellular and extracellular functions such as regulation of calcium homeostasis, cell proliferation, apoptosis, cell invasion and motility, cytoskeleton interactions, protein phosphorylation, regulation of transcriptional factors, autoimmunity, chemotaxis, inflammation and pluripotency. Many lines of evidence suggest that altered expression of S100 proteins was associated with tumor progression and prognosis. Therefore, S100 proteins might also represent potential tumor biomarkers and therapeutic targets. In this review, we summarize the evidence connecting S100 protein family and cancer and discuss the mechanisms by which S100 exerts its diverse functions.

Silencing of S100A4, a metastasis-associated protein, in endothelial cells inhibits tumor angiogenesis and growth

Endothelial cells express S100A4, a metastasis-associated protein, but its role in angiogenesis remains to be elucidated. Here we show that knockdown of S100A4 in mouse endothelial MSS31 cells by murine specific small interference RNA (mS100A4 siRNA) markedly suppressed capillary-like tube formation in vitro, in early stage after the treatment, along with down- and up-regulation of some of the pro-angiogenic and anti-angiogenic gene expression, respectively. Of particular note is that intra-tumor administration of the mS100A4 siRNA in a human prostate cancer xenograft significantly reduced tumor vascularity and resulted in the inhibition of tumor growth. These findings show that S100A4 in endothelial cells is involved in tube formation, and suggest its potential as a molecular target for inhibiting tumor angiogenesis, which warrants further development of endothelial S100A4-based strategies for cancer treatment.

The expression of S100A4 in human pancreatic cancer is associated with invasion

OBJECTIVES

Pancreatic cancer is one of the most lethal malignancies; its poor prognosis is strongly associated with invasion and metastasis. Expression of S100A4 has been reported to correlate with poor prognosis in various cancers. We have investigated the role of S100A4 in pancreatic cancer tumorigenesis and its clinicopathologic significance.

METHODS

Protein expression of S100A4 was examined by Western blot in pancreatic cancer cell lines and a human pancreatic ductal epithelium cell line, HPDE-6. Then the expressions of S100A4, TP53, and CD133 were examined immunohistochemically in resected specimens from 83 patients with pancreatic cancer to clarify their clinicopathologic significance. Survival analyses were performed using the Kaplan-Meier method and the Mantel-Cox method.

RESULTS

Forty-eight (58%) of 83 patients with pancreatic cancer positively expressed S100A4, and 50 (60%) and 29 (36%) patients positively expressed TP53 and CD133, respectively. S100A4 expression was significantly correlated with perineural invasion (P = 0.029) and invasion pattern (P = 0.001). Neither TP53 nor CD133 expression showed significant correlations with any other parameters.

CONCLUSIONS

Our present results suggest that S100A4 plays an important role in the invasiveness, particularly with perineural invasion and invasion pattern, of pancreatic cancer. Development of new strategies targeting S100A4 or its downstream effectors is warranted.

S100A4 interacts with p53 in the nucleus and promotes p53 degradation

S100A4 is a small calcium-binding protein that is commonly overexpressed in a range of different tumor types, and it is widely accepted that S100A4 has an important role in the process of cancer metastasis. In vitro binding assays has shown that S100A4 interacts with the tumor suppressor protein p53, indicating that S100A4 may have additional roles in tumor development. In the present study, we show that endogenous S100A4 and p53 interact in complex samples, and that the interaction increases after inhibition of MDM2-dependent p53 degradation using Nutlin-3A. Further, using proximity ligation assay, we show that the interaction takes place in the cell nucleus. S100A4 knockdown experiments in two p53 wild-type cell lines, A549 and HeLa, resulted in stabilization of p53 protein, indicating that S100A4 is promoting p53 degradation. Finally, we demonstrate that S100A4 knockdown leads to p53-dependent cell cycle arrest and increased cisplatin-induced apoptosis. Thus, our data add a new layer to the oncogenic properties of S100A4 through its inhibition of p53-dependent processes.

S100A4 calcium-binding protein is key player in tumor progression and metastasis: preclinical and clinical evidence

The fatality of cancer is mainly bestowed to the property of otherwise benign tumor cells to become malignant and invade surrounding tissues by circumventing normal tissue barriers through a process called metastasis. S100A4 which is a member of the S100 family of calcium-binding proteins has been shown to be able to activate and integrate pathways both intracellular and extracellular to generate a phenotypic response characteristic of cancer metastasis. A large number of studies have shown an increased expression level of S100A4 in various types of cancers. However, its implications in cancer metastasis in terms of whether an increased expression of S100A4 is a causal factor for metastasis or just another after effect of several other physiological and molecular changes in the body resulting from metastasis are not clear. Here we describe the emerging preclinical and clinical evidences implicating S100A4 protein, in both its forms (intracellular and extracellular) in the process of tumorigenesis and metastasis in humans. Based on studies utilizing S100A4 as a metastasis biomarker and molecular target for therapies such as gene therapy, we suggest that S100A4 has emerged as a promising molecule to be tested for anticancer drugs. This review provides an insight in the (1) molecular mechanisms through which S100A4 drives the tumorigenesis and metastasis and (2) developments made in the direction of evaluating S100A4 as a cancer biomarker and drug target.