Elevated S100A6 (Calcyclin) enhances tumorigenesis and suppresses CXCL14-induced apoptosis in clear cell renal cell carcinoma. Oncotarget. 2015;6:6656-6669. [PMID: 25760073 PMCID: PMC4466641 DOI: 10.18632/oncotarget.3169]

S100A6 mediated epithelial-mesenchymal transition affects chemosensitivity of colorectal cancer to oxaliplatin

PURPOSE

To investigate the mechanism by which S100 calcium-binding protein A6 (S100A6) affects colorectal cancer (CRC) cells to oxaliplatin (L-OHP) chemotherapy, and to explore new strategies for CRC treatment.

METHODS

S100A6 expression was assessed in both parental and L-OHP-resistant CRC cells using western blotting, quantitative real-time polymerase chain reaction (qRT-PCR), and enzyme-linked immunosorbent assays (ELISA). Lentiviral vectors were utilized to induce the knockdown of S100A6 expression, followed by comprehensive evaluations of cell proliferation, apoptosis, and epithelial-mesenchymal transition (EMT). Additionally, RNA-seq analysis was conducted to identify genes associated with the knockdown of S100A6.

RESULTS

Elevated S100A6 expression in CRC tissues correlated with an adverse prognosis in patients with CRC. Higher expression of S100A6 was also observed in L-OHP-resistant CRC cells, which showed enhanced proliferation, migration, invasion, and antiapoptotic capabilities. Notably, the knockdown of S100A6 expression resulted in decreased proliferation, increased apoptosis, and suppression of EMT and tumorigenicity in L-OHP-resistant CRC cells. Transcriptome sequencing reveals a noteworthy association between S100A6 and vimentin expression. Application of the EMT agonist, transforming growth factor β (TGF-β), induces EMT in CRC cells. S100A6 expression positively correlates with TGF-β expression. TGF-β facilitated the expression of EMT-related molecules and reduced the chemosensitivity of L-OHP in S100A6-knockdown cells.

CONCLUSION

In conclusion, the knockdown of S100A6 may overcome the L-OHP resistance of CRC cells by modulating EMT.

CXCL14 as a potential marker for immunotherapy response prediction in renal cell carcinoma

Background

Epigenetic mechanisms play vital roles in the activation, differentiation, and effector function of immune cells. The breast and kidney-expressed chemokine (CXCL14) mainly contributes to the regulation of immune cells. However, its role in shaping the tumor immune microenvironment (TIME) is yet to be elucidated in renal cell carcinoma (RCC).

Objectives

This study aimed to elucidate the role of CXCL14 in predicting the efficacy of immunotherapy in patients with RCC.

Methods

CXCL14 expression and RNA-sequencing, single-cell RNA-sequencing (scRNA-seq), and survival datasets of RCC from public databases were analyzed, and survival was compared between different CXCL14 levels. The correlation between CXCL14 and immune infiltration and human leukocyte antigen (HLA) gene expression was analyzed with TIMER2.0 and gene expression profiling interactive analysis. Institutional scRNA-seq and immunohistochemical staining analyses were used to verify the relationship between CXCL14 expression level and the efficacy of immunotherapy.

Results

CXCL14 was expressed in fibroblast and malignant cells in RCC, and higher expression was associated with better survival. Enrichment analysis revealed that CXCL14 is involved in immune activation, primarily in antigen procession, antigen presentation, and major histocompatibility complex assemble. CXCL14 expression was positively correlated with T-cell infiltration as well as HLA-related gene expression. Among the RCC cohort receiving nivolumab in Checkmate 025, the patients with CXCL14 high expression had better overall survival than those with CXCL14 low expression after immunotherapy. scRNA-seq revealed a cluster of CXCL14+ fibroblast in immunotherapy responders. Immunohistochemistry analysis verified that the patients with high CXCL14 expression had an increased proportion of high CD8 expression simultaneously. The expression level of CXCL14 was associated with CXCR4 expression in RCC.

Conclusion

CXCL14 expression is associated with immunotherapy response in RCC. It is a promising biomarker for immunotherapy response prediction and may be an effective epigenetic modulator in combination with immunotherapy approaches.

The Role of S100A6 in Human Diseases: Molecular Mechanisms and Therapeutic Potential

S100A6, also known as calcyclin, is a low-molecular-weight Ca2+-binding protein from the S100 family that contains two EF-hands. S100A6 is expressed in a variety of mammalian cells and tissues. It is also expressed in lung, colorectal, pancreatic, and liver cancers, as well as other cancers such as melanoma. S100A6 has many molecular functions related to cell proliferation, the cell cycle, cell differentiation, and the cytoskeleton. It is not only involved in tumor invasion, proliferation, and migration, but also the pathogenesis of other non-neoplastic diseases. In this review, we focus on the molecular mechanisms and potential therapeutic targets of S100A6 in tumors, nervous system diseases, leukemia, endometriosis, cardiovascular disease, osteoarthritis, and other related diseases.

S-100 Proteins: Basics and Applications as Biomarkers in Animals with Special Focus on Calgranulins (S100A8, A9, and A12)

S100 proteins are a group of calcium-binding proteins which received this name because of their solubility in a 100% saturated solution of ammonium sulphate. They have a similar molecular mass of 10-12 KDa and share 25-65% similarity in their amino acid sequence. They are expressed in many tissues, and to date 25 different types of S100 proteins have been identified. This review aims to provide updated information about S100 proteins and their use as biomarkers in veterinary science, with special emphasis on the family of calgranulins that includes S100A8 (calgranulin A; myeloid-related protein 8, MRP8), S100A9 (calgranulin B; MRP14), and S100A12 (calgranulin C). The proteins SA100A8 and S100A9 can be linked, forming a heterodimer which is known as calprotectin. Calgranulins are related to the activation of inflammation and the immune system and increase in gastrointestinal diseases, inflammation and sepsis, immunomediated diseases, and obesity and endocrine disorders in different animal species. This review reflects the current knowledge about calgranulins in veterinary science, which should increase in the future to clarify their role in different diseases and potential as biomarkers and therapeutic targets, as well as the practical use of their measurement in non-invasive samples such as saliva or feces.

S100A6 Protein-Expression and Function in Norm and Pathology

S100A6, also known as calcyclin, is a calcium-binding protein belonging to the S100 protein family. It was first identified and purified more than 30 years ago. Initial structural studies, focused mostly on the mode and affinity of Ca²⁺ binding and resolution of the resultant conformational changes, were soon complemented by research on its expression, localization and identification of binding partners. With time, the use of biophysical methods helped to resolve the structure and versatility of S100A6 complexes with some of its ligands. Meanwhile, it became clear that S100A6 expression was altered in various pathological states and correlated with the stage/progression of many diseases, including cancers, indicative of its important, and possibly causative, role in some of these diseases. This, in turn, prompted researchers to look for the mechanism of S100A6 action and to identify the intermediary signaling pathways and effectors. After all these years, our knowledge on various aspects of S100A6 biology is robust but still incomplete. The list of S100A6 ligands is growing all the time, as is our understanding of the physiological importance of these interactions. The present review summarizes available data concerning S100A6 expression/localization, interaction with intracellular and extracellular targets, involvement in Ca²⁺-dependent cellular processes and association with various pathologies.

RAGE Inhibitors for Targeted Therapy of Cancer: A Comprehensive Review

The receptor for advanced glycation end products (RAGE) is a member of the immunoglobulin family that is overexpressed in several cancers. RAGE is highly expressed in the lung, and its expression increases proportionally at the site of inflammation. This receptor can bind a variety of ligands, including advanced glycation end products, high mobility group box 1, S100 proteins, adhesion molecules, complement components, advanced lipoxidation end products, lipopolysaccharides, and other molecules that mediate cellular responses related to acute and chronic inflammation. RAGE serves as an important node for the initiation and stimulation of cell stress and growth signaling mechanisms that promote carcinogenesis, tumor propagation, and metastatic potential. In this review, we discuss different aspects of RAGE and its prominent ligands implicated in cancer pathogenesis and describe current findings that provide insights into the significant role played by RAGE in cancer. Cancer development can be hindered by inhibiting the interaction of RAGE with its ligands, and this could provide an effective strategy for cancer treatment.

Effect of chemokine CXCL14 on in vitro angiogenesis of human hepatocellular carcinoma cells

The study was designed to investigate the effect of chemokine CXCL14 on in vitro angiogenesis of human hepatocellular carcinoma (HCC) cells. CXCL14 mRNA expression in HCC tissue samples and adjacent tissue samples was detected by quantitative reverse transcription polymerase chain reaction (qRT-PCR). CXCL14 mRNA and protein expression in human normal hepatocyte HL-7702 and HCC cell line HepG2 were detected by qRT-PCR and western blot. In HepG2 cell line, the expression of vascular endothelial growth factor (VEGF) was detected by enzyme-linked immunosorbent assay method, cell viability was detected by CCK-8, cell proliferation was detected by colony formation assay, and cell migration as well as invasion ability was detected by Transwell assay. Moreover, human umbilical vein endothelial cell (HUVEC) tube formation assay was carried out to determine the cell ability of angiogenesis. Results showed that the overexpression of CXCL14 could inhibit angiogenesis, proliferation, migration, and invasion abilities of HCC cells.Highlights CXCL14 is lowly expressed in hepatocellular carcinoma tissues and cells. CXCL14 overexpression inhibits the angiogenesis of hepatocellular carcinoma cells. CXCL14 overexpression inhibits proliferation, invasion, and migration of hepatocellular carcinoma cells.

Dysregulation of CXCL14 promotes malignant phenotypes of esophageal squamous carcinoma cells via regulating SRC and EGFR signaling

The present study was to identify abnormal methylation genes implicated in esophageal squamous cell carcinoma (ESCC). Genomic methylation alterations in ESCC tissues were analyzed using laser-microdissection and whole-genome bisulfite sequencing. CXCL14 promoter was frequently hypermethylated in ESCC tissues. The correlation of CXCL14 hypermethylation status and the mRNA and protein expression levels were validated using nested methylation-specific PCR (nMS-PCR), RNAscope in situ hybridization (RISH) and Western blot. RISH results showed completely negative CXCL14 expression in 34.3% (34/99) ESCC, compared with those in the basal layer cells of normal epithelia. Low expression of CXCL14 was more present in patients with lower differentiation. The anticancer role of CXCL14 has been commonly associated with immune regulation in the literature. Here, we observed by functional analysis that CXCL14 can also act as a tumor suppressor in ESCC cells. 5-Aza-dC treatment suppressed CXCL14 methylation and up-regulated the expression of CXCL14. Ectopic expression of CXCL14 suppressed the proliferation, invasion, tumor growth, and lung metastasis of ESCC cells. Both ectopic expression and induction of CXCL14 with 5-Aza-dC inhibited the activity of SRC, MEK1/2 and STAT3 in ESCC cells, while activated EGFR. Importantly, a combination of CXCL14 expression and SRC or EGFR inhibitor dramatically repressed the proliferation of ESCC cells and the growth of xenografts. Our findings revealed a direct tumor suppressor role of CXCL14, but not through the immune system. The data suggest that for ESCC patients with low level CXCL14, increasing CXCL14 expression combined with inhibition of SRC or EGFR might be a promising therapeutic strategy.

Chemokine CXCL14; a double-edged sword in cancer development

Cancer is a leading cause of death worldwide and imposes a substantial financial burden. Therefore, it is essential to develop cost-effective approaches to inhibit tumor growth and development. The imbalance of cytokines and chemokines play an important role among different mechanisms involved in cancer development. One of the strongly conserved chemokines that is constitutively expressed in skin epithelia is the chemokine CXCL14. As a member of the CXC subfamily of chemokines, CXCL14 is responsible for the infiltration of immune cells, maturation of dendritic cells, upregulation of major histocompatibility complex (MHC)-I expression, and cell mobilization. Moreover, dysregulation of CXCL14 in several cancers has been identified by several studies. Depending on the type or origin of the tumor and components of the tumor microenvironment, CXCL14 plays a conflicting role in cancer. Although fibroblast-derived CXCL14 has a tumor-supportive role, epithelial-derived CXCL14 mainly inhibits tumor progression. Hence, this review will elucidate what is known on the mechanisms of CXCL14 and its therapeutic approaches in tumor treatment. CXCL14 is a promising approach for cancer immunotherapy.

Powerful quantifiers for cancer transcriptomics

Every day, investigators find a new link between a form of cancer and a particular alteration in the sequence or/and expression level of a key gene, awarding this gene the title of “biomarker”. The clinician may choose from numerous available panels to assess the type of cancer based on the mutation or expression regulation (“transcriptomic signature”) of “driver” genes. However, cancer is not a “one-gene show” and, together with the alleged biomarker, hundreds other genes are found as mutated or/and regulated in cancer samples. Regardless of the platform, a well-designed transcriptomic study produces three independent features for each gene: Average expression level, expression variability and coordination with expression of each other gene. While the average expression level is used in all studies to identify what genes were up-/down-regulated or turn on/off, the other two features are unfairly ignored. We use all three features to quantify the transcriptomic change during the progression of the disease and recovery in response to a treatment. Data from our published microarray experiments on cancer nodules and surrounding normal tissue from surgically removed tumors prove that the transcriptomic topologies are not only different in histopathologically distinct regions of a tumor but also dynamic and unique for each human being. We show also that the most influential genes in cancer nodules [the Gene Master Regulators (GMRs)] are significantly less influential in the normal tissue. As such, “smart” manipulation of the cancer GMRs expression may selectively kill cancer cells with little consequences on the normal ones. Therefore, we strongly recommend a really personalized approach of cancer medicine and present the experimental procedure and the mathematical algorithm to identify the most legitimate targets (GMRs) for gene therapy.

The multifarious roles of the chemokine CXCL14 in cancer progression and immune responses

The chemokine CXCL14 is a highly conserved, homeostatic chemokine that is constitutively expressed in skin epithelia. Responsible for immune cell recruitment and maturation, as well as impacting epithelial cell motility, CXCL14 contributes to the establishment of immune surveillance within normal epithelial layers. Furthermore, CXCL14 is critical to upregulating major histocompatibility complex class I expression on tumor cells. Given these important roles, CXCL14 is often dysregulated in several types of carcinomas including cervical, colorectal, endometrial, and head and neck cancers. Its disruption has been shown to limit critical antitumor immune regulation and is correlated to poor patient prognosis. However, other studies have found that in certain cancers, namely pancreatic and some breast cancers, overexpression of stromal CXCL14 correlates with poor patient survival due to increased invasiveness. Contributing to the ambiguity CXCL14 plays in cancer is that the native CXCL14 receptor remains uncharacterized, although several candidate receptors have been proposed. Despite the complexity of CXCL14 functions, it remains clear that this chemokine is a key regulatory factor in cancer and represents a potential target for future cancer immunotherapies.

Hypertonicity-Affected Genes Are Differentially Expressed in Clear Cell Renal Cell Carcinoma and Correlate with Cancer-Specific Survival

The heterogeneity of renal cell carcinoma (RCC) subtypes reflects the cell type of origin in the nephron, with consequences for therapy and prognosis. The transcriptional cues that determine segment-specific gene expression patterns are poorly understood. We recently showed that hypertonicity in the renal medulla regulates nephron-specific gene expression. Here, we analyzed a set of 223 genes, which were identified in the present study by RNA-Seq to be differentially expressed by hypertonicity, for the prediction of cancer-specific survival (CSS). Cluster analyses of these genes showed discrimination between tumor and non-tumor samples of clear cell RCC (ccRCC). Refinement of this gene signature to a four-gene score (OSM score) through statistical analyses enabled prediction of CSS in ccRCC patients of The Cancer Genome Atlas (TCGA) (n = 436) in univariate (HR = 4.1; 95% CI: 2.78−6.07; p = 4.39 × 10⁻¹³), and multivariate analyses including primary tumor (T); regional lymph node (N); distant metastasis (M); grading (G)(p = 2.3 × 10⁻⁵). The OSM score could be validated in an independent ccRCC study (n = 52) in univariate (HR = 1.29; 95% CI = 1.05–1.59; p = 0.011) and multivariate analyses (p = 0.016). Cell culture experiments using RCC cell lines demonstrated that the expression of the tumor suppressor ELF5 could be restored by hypertonicity. The innovation of our novel gene signature is that these genes are physiologically regulated only by hypertonicity, thereby providing the possibility to be targeted for therapy.

CXCL14 suppresses human papillomavirus-associated head and neck cancer through antigen-specific CD8+ T-cell responses by upregulating MHC-I expression

Evasion of the host immune responses is critical for both persistent human papillomavirus (HPV) infection and associated cancer progression. We have previously shown that expression of the homeostatic chemokine CXCL14 is significantly downregulated by the HPV oncoprotein E7 during cancer progression. Restoration of CXCL14 expression in HPV-positive head and neck cancer (HNC) cells dramatically suppresses tumor growth and increases survival through an immune-dependent mechanism in mice. While CXCL14 recruits natural killer (NK) and T cells to the tumor microenvironment, the mechanism by which CXCL14 mediates tumor suppression through NK and/or T cells remained undefined. Here, we report that CD8⁺ T cells are required for CXCL14-mediated tumor suppression. Using a CD8⁺ T cell receptor transgenic model, we show that the CXCL14-mediated antitumor CD8⁺ T cell responses require antigen specificity. Interestingly, CXCL14 expression restores major histocompatibility complex class I (MHC-I) expression on HPV-positive HNC cells downregulated by HPV, and knockdown of MHC-I expression in HNC cells results in loss of tumor suppression even with CXCL14 expression. These results suggest that CXCL14 enacts antitumor immunity through restoration of MHC-I expression on tumor cells and promoting antigen-specific CD8⁺ T cell responses to suppress HPV-positive HNC.

Upregulation of S100A6 in patients with endometriosis and its role in ectopic endometrial stromal cells

S100 calcium-binding protein A6 (S100A6) is up-regulated in many malignancies and overexpression of S100A6 has been identified associated with proliferation, migration and invasion phenotype in several cancer cells. In the present study, we explored whether S100A6 plays a role in the development of endometriosis. Significantly higher levels of mRNA and protein expression of S100A6 were observed in ectopic endometrial tissues compared to eutopic and normal endometrial tissues. Silencing of S100A6 in ectopic endometrial stromal cells (ESCs) significantly inhibited cell viability, migration and invasion. Moreover, knockdown of S100A6 suppressed p38/MAPK activity in ectopic ESCs, which can be partially attenuated by CacyBP/SIP phosphorylation inhibitor. In conclusion, our results suggest that the abnormal expression of S100A6 may contribute to the pathogenesis of endometriosis and the S100A6/CacyBP/p38 signaling may provide as a promising treatment target.

LncRNAs act as prognostic and diagnostic biomarkers in renal cell carcinoma: a systematic review and meta-analysis

We conducted a systematic review and meta-analysis to investigate the clinical values, including clinicopathology, prognosis, and diagnosis of different long non-coding RNAs (lncRNAs) in renal cell carcinoma (RCC). A total of 14 eligible studies, including 10 on clinicopathological features, 11 on prognosis, and 3 on diagnosis were identified. Results revealed that metastasis-associated lung adenocarcinoma transcript 1(MALAT1) expression was associated with tumor stage (odds ratio [OR], 3.46; 95% confidence interval [CI], 1.63-7.36; p=0.001). The high expression of MALAT1 could be considered a biomarker of the early detection of lymph node metastasis and predictor of poor survival in RCC patients, who likely manifested short overall survival (OS; hazard ratio [HR], 2.97; 95% CI, 1.68-5.28; p<0.001). For diagnostic value, the pooled result showed that lncRNA maintained a sensitivity of 0.89 and specificity of 0.91 in RCC diagnosis, The area under the curve of 0.94 (95% CI, 0.92-0.96) for lncRNA in RCC diagnosis also indicated a significant advantage over other biomarkers. Our systematic review and meta-analysis demonstrated that lncRNAs could be considered biomarkers to detect lymph node metastasis and distant metastasis in early stages. LncRNAs could function as potential prognostic markers in RCC. LncRNAs could also display high accuracy for RCC diagnosis.

High Expression of S100A6 Predicts Unfavorable Prognosis of Lung Squamous Cell Cancer

Background

S100 family of proteins is mainly involved in regulation of intracellular calcium homeostasis. Aberrant expression of S100 family members has been reported in many types of cancers. However, as a member of S100 family, the prognostic value of S100A6 for lung squamous cell carcinoma (SCC) has not been well-studied.

Material/Methods

Using immunohistochemistry, we investigated the expression of S100A6 in 177 patients with SCC and further divided the cohort into a high S100A6 expression group and a low S100A6 expression group. The chi-square test was applied to analyze the correlation between S100A6 expression and clinicopathological factors. Univariate analysis using the Kaplan-Meier method was performed to compare the difference in survival rates between the high S100A6 expression group and the low S100A6 expression group; multivariate analysis with Cox regression model was used to identify independent prognostic risk factors.

Results

In our experiment, we demonstrated that the expression of S100A6 was significantly associated with patient age and tumor differentiation. High-expression of S100A6 was shown to be substantially related to the unfavorable prognosis of SCC. Moreover, our results confirmed that S100A6 was an independent risk factor for SCC prognosis, and could predict unfavorable prognosis.

Conclusions

High-expression of S100A6 was identified as an independent unfavorable prognostic factor for SCC, suggesting that targeting S100A6 may result in the development of potential targeted drug for SCC.

S100A6 promotes proliferation of intrahepatic cholangiocarcinoma cells via the activation of the p38/MAPK pathway

Aim: We explored the expression of S100A6 and its role in intrahepatic cholangiocarcinoma (ICC). Methods: The expression of S100A6 in ICC samples was detected by immunohistochemistry. In vitro experiments, we silenced and overexpressed S100A6 to investigate its role in cell functions. Results: The expression of S100A6 was markedly increased in ICC tissues and cell lines. S100A6 overexpression was an independent risk factor for patients’ survival. Silencing S100A6 resulted in a suppression of proliferation and p38/MAPK activity, while overexpressing S100A6 caused a promotion of proliferation and p38/MAPK. Discussion: S100A6 participated in the proliferation of ICC cells and correlated with a more aggressive behavior of ICC. Conclusion: S100A6 may serve as a novel prognostic marker and a potential therapeutic target for ICC patients.

"Stealth dissemination" of macrophage-tumor cell fusions cultured from blood of patients with pancreatic ductal adenocarcinoma

Here we describe isolation and characterization of macrophage-tumor cell fusions (MTFs) from the blood of pancreatic ductal adenocarcinoma (PDAC) patients. The MTFs were generally aneuploidy, and immunophenotypic characterizations showed that the MTFs express markers characteristic of PDAC and stem cells, as well as M2-polarized macrophages. Single cell RNASeq analyses showed that the MTFs express many transcripts implicated in cancer progression, LINE1 retrotransposons, and very high levels of several long non-coding transcripts involved in metastasis (such as MALAT1). When cultured MTFs were transplanted orthotopically into mouse pancreas, they grew as obvious well-differentiated islands of cells, but they also disseminated widely throughout multiple tissues in "stealth" fashion. They were found distributed throughout multiple organs at 4, 8, or 12 weeks after transplantation (including liver, spleen, lung), occurring as single cells or small groups of cells, without formation of obvious tumors or any apparent progression over the 4 to 12 week period. We suggest that MTFs form continually during PDAC development, and that they disseminate early in cancer progression, forming "niches" at distant sites for subsequent colonization by metastasis-initiating cells.

S100A6 protein: functional roles

S100A6 protein belongs to the A group of the S100 protein family of Ca2+-binding proteins. It is expressed in a limited number of cell types in adult normal tissues and in several tumor cell types. As an intracellular protein, S100A6 has been implicated in the regulation of several cellular functions, such as proliferation, apoptosis, the cytoskeleton dynamics, and the cellular response to different stress factors. S100A6 can be secreted/released by certain cell types which points to extracellular effects of the protein. RAGE (receptor for advanced glycation endproducts) and integrin β1 transduce some extracellular S100A6's effects. Dosage of serum S100A6 might aid in diagnosis in oncology.

Distinct prognostic values of S100 mRNA expression in breast cancer

S100 family genes encode low molecular weight, acidic-Ca²⁺ binding proteins implicating in a wide spectrum of biological processes. S100 family contains at least 20 members, most of which are frequently dysregulated in human malignancies including breast cancer. However, the prognostic roles of each individual S100, especially the mRNA level, in breast cancer patients remain elusive. In the current study, we used "The Kaplan-Meier plotter" (KM plotter) database to investigate the prognostic values of S100 mRNA expression in breast cancer. Our results indicated that high mRNA expression of S100A8, S100A9, S100A11 and S100P were found to be significantly correlated to worse outcome, while S100A1 and S100A6 were associated with better prognosis in all breast cancer patients. We further assessed the prognostic value of S100 in different intrinsic subtypes and clinicopathological features of breast cancer. The associated results will elucidate the role of S100 in breast cancer and may further lead the research to explore the S100-targeting reagents for treating breast cancer patients.

Serum levels of S100A6 are unaltered in patients with resectable cholangiocarcinoma

Background

Elevated expression levels of S100A6, a calcium-binding low-molecular-weight protein, were demonstrated in various malignancies. Moreover, increased serum levels of S100A6 were suggested as a novel biomarker for various inflammatory and malignant diseases including lung and gastric cancer. However, up to now, serum concentrations of S100A6 have not been analyzed in patients with cholangiocarcinoma (CCA).

Methods

S100A6 mRNA expression levels were analyzed in human and murine CCA tumor samples, using semi-quantitative reverse transcriptase PCR. S100A6 serum concentrations were measured using an enzyme-linked immunosorbent assay in 112 patients with CCA referred to surgery for curative resection and were compared to those of 42 healthy controls. Results were correlated with clinical data.

Results

S100A6 mRNA expression levels were significantly up-regulated in tumor samples of CCA patients and in tumor tissue of a CCA mouse model. In contrast, serum levels of S100A6 were not significantly altered in patients with CCA compared to healthy controls. Whereas no differences became apparent within the different clinical subgroups of CCA, patients with primary sclerosing cholangitis (PSC)-based CCA displayed higher levels of S100A6 compared to the other patients. Nevertheless, patients with higher S100A6 serum concentrations showed a trend towards an impaired prognosis compared to patients with lower levels. Finally, within our cohort of patients both the diagnostic and prognostic potentials of S100A6 were similar to those of the clinically established biomarkers CEA and CA19-9.

Conclusion

Although S100A6 was expressed at significantly higher levels in human and murine CCA tumor samples, S100A6 serum levels were not regulated in patients with CCA and are thus not suitable for diagnosis of CCA. However, CCA-patients with elevated S100A6 displayed a trend toward an impaired prognosis compared to patients with lower S100A6 levels, supporting its further evaluation as a prognostic biomarker in CCA.

Electronic supplementary material

The online version of this article (doi:10.1186/s40169-016-0120-7) contains supplementary material, which is available to authorized users.

CXCL14 as an emerging immune and inflammatory modulator

CXCL14, a relatively novel chemokine, is a non-ELR (glutamic acid-leucine-arginine) chemokine with a broad spectrum of biological activities. CXCL14 mainly contributes to the regulation of immune cell migration, also executes antimicrobial immunity. The identity of the receptor for CXCL14 still remains obscure and therefore the intracellular signaling pathway is not entirely delineated. The present review summarizes the contribution of CXCL14 in these two aspects and discusses the biological mechanisms regulating CXCL14 expression and potential CXCL14 mediated functional implications in a variety of cells.