Metastasis-associated genes in oral squamous cell carcinoma and salivary adenoid cystic carcinoma: a differential DNA chip analysis between metastatic and nonmetastatic cell systems

Matrix metalloproteinase-7, -8, -9, -15, and -25 in minor salivary gland adenoid cystic carcinoma

Knowledge on the role of matrix metalloproteinases (MMPs) in adenoid cystic carcinoma (ACC) is limited. MMPs are capable of degrading almost all extracellular and pericellular components to promote invasion and metastasis. This study aimed to evaluate the immunohistochemical expression of MMP-7, -8, -9, -15, and -25 in ACC and to relate the results with clinicopathological factors and survival. The study included 68 patients with minor salivary gland ACC treated at the Helsinki University Hospital (Helsinki, Finland) in 1974-2012. Samples from 52 patients were available, consisting of 44 primary tumours and eight recurrent tumours. We scored immunostaining of MMP-7, -8, -9, -15, and -25 and analysed the immunoscore against clinical and pathological parameters using statistical correlation test. MMP-9 immunoexpression in pseudocysts of ACC and in peritumoural inflammatory cells associated with better survival and fewer treatment failures. High tumoural MMP-7 and -25 associated with better survival. High tumoural MMP-15 associated with poorer survival and high tumoural MMP-9 with advanced stage and regional recurrences. Tumour cells did not show MMP-8 immunopositivity. These results suggest that MMP-9 may contribute to ACC carcinogenesis in different roles. MMP-7, -8, and -9 can stimulate signalling pathways that may promote tissue modulation and metastatic potential. MMP-15 and -25 may reflect prognosis.

Complex integrated analysis of lncRNAs-miRNAs-mRNAs in oral squamous cell carcinoma

OBJECTIVES

This study aims to reveal regulatory network of lncRNAs-miRNAs-mRNAs in oral squamous cell carcinoma (OSCC) through gene expression data.

MATERIAL AND METHODS

Differentially expressed lncRNAs, miRNAs and mRNAs (cut-off: False discovery rate (FDR)<0.05 and |fold change|>1.5) were unveiled by package edgeR of R. Cox regression analysis was performed to screen prognostic factors in OSCC related with overall survival (OS) and relapse-free survival (RFS). Protein-protein interaction (PPI) network was constructed for differentially expressed mRNAs using BioGRID, HPRD and DIP. Key hub genes were identified from top 100 differentially expressed mRNAs ranked by betweenness centrality using recursive feature elimination. LncRNA-miRNA and miRNA-mRNA regulatory network were constructed and combined into ceRNAs regulatory network. Gene ontology biological terms and Kyoto Encyclopedia of Genes and Genomes pathways were identified using Fisher's exact test.

RESULTS

A total of 929 differentially expressed mRNAs, 23 differentially expressed lncRNAs and 29 differentially expressed miRNAs were identified. 59 mRNAs, 6 miRNAs (hsa-mir-133a-1, hsa-mir-1-2, hsa-mir-486, hsa-mir-135b, hsa-mir-196b, hsa-mir-193b) and 6 lncRNAs (C10orf91, C2orf48, SFTA1P, FLJ41941,PART1,TTTY14) were related with OS; and 52 mRNAs, 4 miRNAs (hsa-mir-133a-1, hsa-mir-135b, hsa-mir-196b, hsa-mir-193b) and 2 lncRNAs (PART1, TTTY14) were associated with RFS. A support vector machine (SVM) classifier containing 37 key hub genes was obtained. A ceRNA regulatory network containing 417 nodes and 696 edges was constructed. ECM-receptor interaction, cytokine-cytokine receptor interaction, focal adhesion, arachidonic acid metabolism, and p53 signaling pathway were significantly enriched in the network.

CONCLUSION

These findings uncover the pathogenesis of OSCC and might provide potential therapeutic targets.

MYB fusions and CD markers as tools for authentication and purification of cancer stem cells from salivary adenoid cystic carcinoma

Cancer stem cells (CSC) are considered the major cause of aggressive tumor behavior, recurrence, metastases, and resistance to radiation, making them an attractive therapeutic target. However, isolation of CSC from tumor tissue and their characterization are challenging due to uncertainty about their molecular markers and conditions for their propagation. Adenoid cystic carcinoma (ACC), which arises predominantly in the salivary glands, is a slow-growing but relentless tumor that frequently invades nerves and metastasizes. New effective treatment approaches for ACC have not emerged over the last 40years. Previously, based on a highly conserved SOX10 gene signature that we identified in the majority of ACC tumors, we suggested the existence in ACC of SOX10+ cells with neural stem properties and corroborated this hypothesis via isolation from ACC tissue a novel population of CSC, termed ACC-CSC. These cells activated NOTCH1 signaling and co-expressed SOX10 and other ACC-intrinsic neural crest stem cell markers with CD133, a CSC cell surface marker, suggesting that ACC is driven by a previously uncharacterized population of SOX10+/CD133+ cells with neural stem cell properties. Here, we authenticated ACC identity of our primary cultures by demonstrating that most of them harbor MYB-NFIB fusions, which are found in 86% of ACC. We demonstrated using CyTOF, a novel mass cytometry technology, that these cells express high β-catenin and STAT3 levels and are marked by CD24 and CD44. Finally, to streamline development of ACC cell lines, we developed RT-PCR tests for distinguishing mouse and human cells and used immunomagnetic cell sorting to eliminate mouse cells from long-term cell cultures. Overall, this study describes a new population of CSC that activates signaling pathways associated with poor prognosis, validates their ACC identity, and optimizes approaches that can be used for purification of ACC-CSC and generation of cell lines.

Podoplanin-mediated cell adhesion through extracellular matrix in oral squamous cell carcinoma

Podoplanin (PDPN), one of the representative mucin-like type-I transmembrane glycoproteins specific to lymphatic endothelial cells, is expressed in various cancers including squamous cell carcinoma (SCC). On the basis of our previous studies, we have developed the hypothesis that PDPN functions in association with the extracellular matrix (ECM) from the cell surface side. The aim of this study was to elucidate the molecular role of PDPN in terms of cell adhesion, proliferation, and migration in oral SCC cells. Forty-four surgical specimens of oral SCC were used for immunohistochemistry for PDPN, and the expression profiles were correlated with their clinicopathological properties. Using ZK-1, a human oral SCC cell system, and five other cell systems, we examined PDPN expression levels by immunofluorescence, western blotting, and real-time PCR. The effects of transient PDPN knockdown by siRNA in ZK-1 were determined for cellular functions in terms of cell proliferation, adhesion, migration, and invasion in association with CD44 and hyaluronan. Cases without PDPN-positive cells were histopathologically classified as less-differentiated SCC, and SCC cells without PDPN more frequently invaded lymphatics. Adhesive properties of ZK-1 were significantly inhibited by siRNA, and PDPN was shown to collaborate with CD44 in cell adhesion to tether SCC cells with hyaluronan-rich ECM of the narrow intercellular space as well as with the stromal ECM. There was no siRNA effect in migration. We have demonstrated the primary function of PDPN in cell adhesion to ECM, which is to secondarily promote oral SCC cell proliferation.

EGFR inhibition prevents in vitro tumor growth of salivary adenoid cystic carcinoma

Background

Epidermal growth factor receptor (EGFR) is involved in the development of many human malignant tumors and plays an important role in tumor growth and metastasis. Antagonists of EGFR can suppress the growth of several malignancies; however, their therapeutic effect in adenoid cystic carcinoma (ACC) is controversial.

Results

The increased proliferation of two ACC cell lines induced by EGF-treatment was reversed by nimotuzumab. Regardless of EGF stimulation, nimotuzumab-treated ACC cells were arrested in G1 phase and showed decreased expression of Ki67. In addition, EGF activated the MAPK-dependent pathway and up-regulated the expression of matrix metalloproteinase-9 and Snail, enhancing the invasive potential of an ACC cell line (ACC-M). The effects of EGF were down-regulated by nimotuzumab treatment.

Conclusions

These results suggest that nimotuzumab can inhibit the growth and invasion of ACC cells induced by EGF, probably through inactivation of ERK phosphorylation. Thus, nimotuzumab should be considered as a promising novel agent for the treatment of ACC.

Basement membrane components are key players in specialized extracellular matrices

More than three decades ago, basement membranes (BMs) were described as membrane-like structures capable of isolating a cell from and connecting a cell to its environment. Since this time, it has been revealed that BMs are specialized extracellular matrices (sECMs) with unique components that support important functions including differentiation, proliferation, migration, and chemotaxis of cells during development. The composition of these sECM is as unique as the tissues to which they are localized, opening the possibility that such matrices can fulfill distinct functions. Changes in BM composition play significant roles in facilitating the development of various diseases. Furthermore, tissues have to provide sECM for their stem cells during development and for their adult life. Here, we briefly review the latest research on these unique sECM and their components with a special emphasis on embryonic and adult stem cells and their niches.