The role of basement membrane proteins on the expression of neural cell adhesion molecule (N-CAM) in an adenoid cystic carcinoma cell line

[Advances in the molecular mechanisms of perineural invasion in salivary adenoid cystic carcinoma]

Salivary adenoid cystic carcinoma is a very common malignant neoplasm in the salivary glands. One of the most important features of salivary cystic carcinoma is perineural invasion, which renders its complete removal is very difficult through clinical surgery. Consequently, tumor recurrence occurs easily after clinical surgery. Therefore, the molecular mechanisms of perineural invasion in salivary adenoid cystic carcinoma are necessary to explore. These mechanisms are reviewed in this paper.

NCAM- and FGF-2-mediated FGFR1 signaling in the tumor microenvironment of esophageal cancer regulates the survival and migration of tumor-associated macrophages and cancer cells

Tumor-associated macrophages (TAMs) have important roles in the angiogenesis and tumor immunosuppression of various cancers, including esophageal squamous cell carcinomas (ESCCs). To elucidate the roles of TAMs in ESCCs, we compared the gene expression profiles between human peripheral blood monocyte-derived macrophage-like cells (Macrophage_Ls) and Macrophage_Ls stimulated with conditioned medium of the TE series human ESCC cell line (TECM) (TAM_Ls) using cDNA microarray analysis. Among the highly expressed genes in TAM_Ls, we focused on neural cell adhesion molecule (NCAM). NCAM knockdown in TAM_Ls revealed a significant decrease of migration and survival via a suppression of PI3K-Akt and fibroblast growth factor receptor 1 (FGFR1) signaling. Stimulation by TECM up-regulated the level of FGFR1 in Macrophage_Ls. Recombinant human fibroblast growth factor-2 (rhFGF-2) promoted the migration and survival of TAM_Ls and TE-cells through FGFR1 signaling. Our immunohistochemical analysis of 70 surgically resected ESCC samples revealed that the up-regulated FGF-2 in stromal cells, including macrophages, was associated with more aggressive phenotypes and a high number of infiltrating M2 macrophages. These findings may indicate a novel role of NCAM- and FGF-2-mediated FGFR1 signaling in the tumor microenvironment of ESCCs.

Immunohistochemical analysis of laminin expression in adenoid cystic carcinoma

BACKGROUND AND OBJECTIVES

This study aims at the observation of the immunohistochemical expression of laminin in adenoid cystic carcinoma (ACC) of salivary gland origin and to analyze the distribution of laminin in various components of the tumor and correlate the expression of laminin with the growth and differentiation of the tumor.

MATERIALS AND METHODS

THIRTY CASES OF ACC WERE SUBJECTED TO IMMUNOHISTOCHEMICAL STUDY USING POLYCLONAL ANTIHUMAN LAMININ PRIMARY ANTIBODY, DISTRIBUTION OF LAMININ IN EACH CASE OF ACC WAS OBSERVED IN THE FOLLOWING AREAS: Intracellularly, inner borders of the pseudocystic spaces, within the lumen of the pseudocysts, around the tumor islands and in the intervening stroma.

RESULTS

Laminin positivity was observed in the inner aspect of the pseudocystic spaces in 15 cases, within the lumen of pseudocystic spaces in 22 cases, in the intervening stroma in 20 cases, bordering the tumor islands in 16 cases and intracellularly in 4 cases.

INTERPRETATION AND CONCLUSION

Based on these observations, it can be assumed that laminin plays a major role in proliferation of the tumor cells and in pseudocyst formation. Thus, laminin might play a significant role in the growth and differentiation of ACC and also help in assessing the prognosis of the tumor.

Oestrogen receptor β in adenoid cystic carcinoma of salivary glands

AIMS

This study aimed to describe the expression of oestrogen receptor (ER)α, ERβ and aromatase in salivary gland adenoid cystic carcinoma (ACC).

METHODS AND RESULTS

ERα, ERβ and aromatase expression was analysed by immunohistochemistry in tissue microarray blocks from 38 cases of ACC and seven normal salivary glands. The intracellular localization and amount of total protein expression were investigated by immunofluorescence and western blotting in an ACC cell line. Western blotting analysis showed overexpression of ERα, ERβ and aromatase in the ACC cell line; however, with immunofluorescence, only ERβ was shown to be expressed in the nucleus. Immunohistochemistry revealed positive nuclear expression of ERβ, positive cytoplasmic expression of aromatase and a lack of ERα expression as compared with normal salivary glands.

CONCLUSIONS

The nuclear expression of ERβ indicates that oestrogen may be active in ACC and possibly able to mediate E2-targeted gene transcription. This study strongly suggests that ERβ may be involved in tumour progression, playing a role in tumour development, and thus corroborating the indication for ER antagonists in the clinical control of ACC. This study opens a new perspective on the potential use of anti-oestrogens and aromatase inhibitors as therapeutic agents against ACC.

Molecular biology of adenoid cystic carcinoma

BACKGROUND

Adenoid cystic carcinoma (ACC) is an unusual salivary gland malignancy that remains poorly understood. Standard treatment, including surgery with postoperative radiation therapy, has attained reasonable local control rates, but the propensity for distant metastases has limited any improvement in survival over time. Our understanding of the molecular mechanisms driving ACC is quite rudimentary, due to the infrequent nature of its occurrence.

METHODS

An extensive literature review was performed on salivary gland ACCs and basic science research findings.

RESULTS

This review highlights many findings that are emerging about the carcinogenesis of ACC including cytogenetics, tumor suppressor genes, oncogenes, epigenetic alterations, mitochondrial alterations, and biomarker studies.

CONCLUSION

Although there have been many discoveries, much still remains unknown about this rare malignancy. © 2011 Wiley Periodicals, Inc. Head Neck, 2011.

The effect of proteoglycans inhibited by RNA interference on metastatic characters of human salivary adenoid cystic carcinoma

BACKGROUND

Salivary adenoid cystic carcinoma (SACC) is one of the most common malignancies of salivary gland. Recurrence or/and early metastasis is its biological properties. In SACC, neoplastic myoepithelial cells secrete proteoglycans unconventionally full of the cribriform or tubular and glandular structures of SACC. Literatures have demonstrated that extracellular matrix provided an essential microenvironment for the biological behavior of SACC. However, there is rare study of the effect of proteoglycans on the potential metastasis of SACC.In this study, human xylosyltransferase-I (XTLY-I) gene, which catalyzes the rate-limited step of proteoglycans biosynthesis, was knocked down by RNA interference (RNAi) to inhibit the proteoglycans biosynthesis in SACC cell line with high tendency of lung metastasis (SACC-M). The impact of down-regulated proteoglycans on the metastasis characters of SACC-M cells was analyzed and discussed. This research could provide a new idea for the clinical treatment of SACC.

METHODS

The eukaryotic expression vector of short hairpin RNA (shRNA) targeting XTLY-I gene was constructed and transfected into SACC-M cells. A stably transfectant cell line named SACC-M-WJ4 was isolated. The XTLY-I expression was measured by real-time PCR and Western blot; the reduction of proteoglycans was measured. The invasion and metastasis of SACC-M-WJ4 cells were detected; the effect of down-regulated proteoglycans on the potential lung metastasis of nude mice was observed, respectively.

RESULTS

The shRNA plasmid targeting XTLY-I gene showed powerful efficiency of RNAi. The mRNA level of target gene decreased by 86.81%, the protein level was decreased by 80.10%, respectively. The silence of XTLY-I gene resulted in the reduction of proteoglycans significantly in SACC-M-WJ4 cells. The inhibitory rate of proteoglycans was 58.17% (24 h), 66.06% (48 h), 57.91% (72 h), 59.36% (96 h), and 55.65% (120 h), respectively. The reduction of proteoglycans suppressed the adhesion, invasion and metastasis properties of SACC-M cells, and decreased the lung metastasis of SACC-M cells markedly either.

CONCLUSION

The data suggested that the silence of XTLY-I gene in SACC-M cells could suppress proteoglycans biosynthesis and secretion significantly. The reduction of proteoglycans inhibited cell adhesion, invasion and metastasis of SACC-M cells. There is a close relationship between proteoglycans and the biological behavior of SACC.

Genetic profiling reveals cross-contamination and misidentification of 6 adenoid cystic carcinoma cell lines: ACC2, ACC3, ACCM, ACCNS, ACCS and CAC2

Adenoid cystic carcinoma (ACC) is the second most common malignant neoplasm of the salivary glands. Most patients survive more than 5 years after surgery and postoperative radiation therapy. The 10 year survival rate, however, drops to 40%, due to locoregional recurrences and distant metastases. Improving long-term survival in ACC requires the development of more effective systemic therapies based on a better understanding of the biologic behavior of ACC. Much preclinical research in this field involves the use of cultured cells and, to date, several ACC cell lines have been established. Authentication of these cell lines, however, has not been reported. We performed DNA fingerprint analysis on six ACC cell lines using short tandem repeat (STR) examinations and found that all six cell lines had been contaminated with other cells. ACC2, ACC3, and ACCM were determined to be cervical cancer cells (HeLa cells), whereas the ACCS cell line was composed of T24 urinary bladder cancer cells. ACCNS and CAC2 cells were contaminated with cells derived from non-human mammalian species: the cells labeled ACCNS were mouse cells and the CAC2 cells were rat cells. These observations suggest that future studies using ACC cell lines should include cell line authentication to avoid the use of contaminated or non-human cells.

Cimetidine inhibits salivary gland tumor cell adhesion to neural cells and induces apoptosis by blocking NCAM expression

Background

Cimetidine, a histamine type-2 receptor antagonist, has been reported to inhibit the growth of glandular tumors such as colorectal cancer, however the mechanism of action underlying this effect is unknown. Adenoid cystic carcinoma is well known as a malignant salivary gland tumor which preferentially invades neural tissues. We demonstrated previously that human salivary gland tumor (HSG) cells spontaneously express neural cell adhesion molecule (NCAM), that HSG cell proliferation may be controlled via a homophilic (NCAM-NCAM) binding mechanism and that NCAM may be associated with perineural invasion by malignant salivary gland tumors. We further demonstrated that cimetidine inhibited NCAM expression and induced apoptosis in HSG cells. Here, we investigated the effects of cimetidine on growth and perineural/neural invasion of salivary gland tumor cells.

Methods

In this study, we have examined the effect of cimetidine on cancer cell adhesion to neural cells in vitro, one of the critical steps of cancer invasion and metastasis. We have also used an in vivo carcinogenesis model to confirm the effect of cimetidine.

Results

We have demonstrated for the first time that cimetidine can block the adhesion of HSG cells to neural cell monolayers and that it can also induce significant apoptosis in the tumor mass in a nude mouse model. We also demonstrated that these apoptotic effects of cimetidine might occur through down-regulation of the cell surface expression of NCAM on HSG cells. Cimetidine-mediated down-regulation of NCAM involved suppression of the nuclear translocation of NF-κB, a transcriptional activator of NCAM gene expression.

Conclusion

These findings suggest that growth and perineural/neural invasion of salivary gland tumors can be blocked by administration of cimetidine via induction of apoptosis and in which NCAM plays a role.

Secretion of collagen I and tenascin is modulated by laminin-111 in 3D culture of human adenoid cystic carcinoma cells

Adenoid cystic carcinoma is a frequent malignant salivary gland neoplasm with high levels of recurrence and metastasis. This neoplasm expresses prominent extracellular matrix (ECM). We are studying regulatory mechanisms underlying secretion of ECM molecules in adenoid cystic carcinoma. We have previously demonstrated that laminin modulates the phenotype of a human adenoid cystic carcinoma (CAC2) cell line. Thus, this molecule would be a good candidate to regulate secretion of ECM molecules in these cells. Here we analysed the role played by laminin-111 [formerly laminin-1; Aumailley et al. (2005). Matrix Biol. 24, 326] stimulating secretory activity of CAC2 cells. Three-dimensional cultures of cells in laminin-111 (treated) or agarose (controls) were studied by light and electron microscopy. Ultrastructural analysis of CAC2 cells grown within laminin-111 showed pseudocysts filled with secretory-like material. Cells exhibited prominent and dilated endoplasmic reticulum and coated and uncoated vesicles. Ultrastructural findings suggested that laminin-111 induced secretory activity in CAC2 cells. We further investigated this point by light microscopy, immunofluorescence and confocal microscopy. Histochemistry showed periodic acid-Schiff (PAS)-positive diastase-resistant material in CAC2 cells treated by laminin-111. This material could represent laminin-induced secretion of ECM molecules. We searched for collagen I and tenascin in CAC2 cells treated by laminin-111. Confocal microscopy and immunoblot showed that laminin-111 enhanced secretion of collagen I and tenascin in CAC2 cells. We suggest that laminin-111 modulates secretion of collagen I and tenascin in cells derived from human adenoid cystic carcinoma.

Adhesion and protease activity in cell lines from human salivary gland tumors are regulated by the laminin-derived peptide AG73, syndecan-1 and beta1 integrin

We studied the induction of protease activity by the laminin alpha1-derived peptide AG73 in cells from adenoid cystic carcinoma (CAC2) and myoepithelioma (M1), respectively a malignant and a benign salivary gland tumors. Laminin alpha1 chain and MMP9 were immunolocalized in adenoid cystic carcinoma and myoepithelioma in vivo and in vitro. Cells grown inside AG73-enriched laminin-111 exhibited large spaces in the extracellular matrix, suggestive of remodeling. The broad spectrum MMP inhibitor GM6001 decreased spaces induced by AG73 in CAC2 and M1 cells. This result strongly suggests that AG73-mediated matrix remodeling involves matrix metalloproteinases. CAC2 and M1 cells cultured on AG73 showed a dose-dependent increase of MMP9 secretion, as detected by zymography. Furthermore, siRNA silencing of MMP9 decreased remodeling in 3D cultures. We searched for AG73 receptors regulating MMP9 activity in our cell lines. CAC2 and M1 cells grown on AG73 exhibited colocalization of syndecan-1 and beta1 integrin. siRNA knockdown of syndecan-1 expression in these cells resulted in decreased adhesion to AG73 and reduced protease and remodeling activity. We investigated syndecan-1 co-receptors in both cell lines. Silencing beta1 integrin inhibited adhesion to AG73, matrix remodeling and protease activity. Double-knockdown experiments were carried out to further explore syndecan-1 and beta1 integrin cooperation. CAC2 cells transfected with both syndecan-1 and beta1 integrin siRNA oligos showed significant decrease in adhesion to AG73. Simultaneous silencing of receptors also induced a decrease in protease activity. Our results suggest that syndecan-1 and beta1 integrin signaling downstream of AG73 regulate adhesion and MMP production by CAC2 and M1 cells.

SIKVAV, a laminin alpha1-derived peptide, interacts with integrins and increases protease activity of a human salivary gland adenoid cystic carcinoma cell line through the ERK 1/2 signaling pathway

Adenoid cystic carcinoma is a frequently occurring malignant salivary gland neoplasm. We studied the induction of protease activity by the laminin-derived peptide, SIKVAV, in cells (CAC2) derived from this neoplasm. Laminin alpha1 and matrix metalloproteinases (MMPs) 2 and 9 were immunolocalized in adenoid cystic carcinoma cells in vivo and in vitro. CAC2 cells cultured on SIKVAV showed a dose-dependent increase of MMP9 as detected by zymography and colocalization of alpha3 and alpha6 integrins. Small interfering RNA (siRNA) knockdown of integrin expression in CAC2 cells resulted in decreased adhesion to the peptide. SIKVAV affinity chromatography and immunoblot analysis showed that alpha3, alpha6, and beta1 integrins were eluted from the SIKVAV column, which was confirmed by mass spectrometry and a solid-phase binding assay. Small interfering RNA experiments also showed that these integrins, through extracellular signal-regulated kinase (ERK) 1/2 signaling, regulate MMP secretion induced by SIKVAV in CAC2 cells. We propose that SIKVAV increases protease activity of a human salivary gland adenoid cystic carcinoma cell line through alpha3beta1 and alpha6beta1 integrins and the ERK 1/2 signaling pathway.

Malignancy-related 67kDa laminin receptor in adenoid cystic carcinoma. Effect on migration and beta-catenin expression

Adenoid cystic carcinoma is a malignant salivary gland neoplasm with recurrence and metastasis. We studied the expression of a malignancy-related non-integrin laminin receptor, the 67LR, in this neoplasm. Immunohistochemistry showed 67LR in adenoid cystic carcinoma. This receptor binds a sequence of laminin beta1 chain, the YIGSR peptide. We studied the effect of 67LR and YIGSR in cells (CAC2) from adenoid cystic carcinoma. Three-dimensional cultures of cells embedded into either laminin-111 gel (controls) or YIGSR-enriched laminin-111 (treated) were prepared and studied by light microscopy. CAC2 cells treated with YIGSR appeared fibroblast-like, while control cells were epithelioid. Blockage of 67LR by antibody abolished YIGSR effect in three-dimensional cultures. We analysed the relevance of 67LR and YIGSR on beta-catenin expression in CAC2 cells. Immunofluorescence and immunoblot showed that YIGSR decreased beta-catenin, while blockage of 67LR restored the presence of this molecule. The 67LR and YIGSR induced fibroblast-like morphology in CAC2 cells, with disruption of cell-cell contacts and decrease of beta-catenin. These features resemble epithelial-mesenchymal transition (EMT). EMT also increases cell migration. In monolayer assays YIGSR increased migration of CAC2 cells. We conclude that 67LR and YIGSR are involved in epithelial-mesenchymal transition, modulation of beta-catenin expression, and migratory activity of CAC2 cells.

Effect of Matrigel on adenoid cystic carcinoma cell line differentiation

Adenoid cystic carcinoma (ACC) is a frequent malignant salivary gland neoplasm presenting different growth patterns described as tubular, cribriform and solid, which represent distinct differentiation stages. Cell lines originated from ACCs grown inside three-dimensional environments have not been capable to reproduce all in vivo ACC growth patterns. As ACC cells in vivo present replicated basement membrane, to mimic this situation in vitro ACC cells (CAC2 cells) were grown on the top of a reconstituted basement membrane (Matrigel). Phenotype differences were assessed by light, fluorescence and transmission electron microscopy. The cultures grown on the top of Matrigel presented three-dimensional arrangement of cells intercepted by cellular cords. At these, cell nests pseudocyst formations were observed. This morphological structure entirely reproduced the cribriform growth pattern of ACC. We suggest that the cribriform differentiation of ACC in culture is dependent of proteins and growth factors associated in a bi-dimensional structure.

Laminin-1 and SIKVAV a laminin-1-derived peptide, regulate the morphology and protease activity of a human salivary gland adenoid cystic carcinoma cell line

In a previous paper, we demonstrated that laminin-1 and its derived peptide SIKVAV modulates the morphology of an adenoid cystic carcinoma cell line (CAC2 cells). Light microscopy of CAC2 cells grown in three-dimensional preparations of SIKVAV-enriched laminin-1 showed the presence of pseudocystic spaces. Pseudocysts are hallmarks of adenoid cystic carcinoma in vivo. We hypothesized that these pseudocystic spaces could be due to the protease-inducing/activating role of SIKVAV. Thus, we studied the presence of matrix metalloproteinases (MMPs) in CAC2 cells treated either by laminin-1 or by SIKVAV-enriched laminin-1. Immunohistochemistry and zymography suggested that SIKVAV enhanced the secretion of MMP-2 and MMP-9 in CAC2 cells. We propose that SIKVAV induces pseudocystic formation probably through the secretion of MMPs 2 and 9.

The effect of laminin and its peptide SIKVAV on a human salivary gland myoepithelioma cell line

We have demonstrated that the basement membrane regulates the myoepithelioma. We are now studying the effect of laminin, a basement membrane protein, in the morphology of a cell line (M1) derived from human salivary gland plasmacytoid myoepithelioma. These cells were grown inside a three-dimensional preparation of laminin-1. Phenotype differences were assessed by light and transmission electron microscopy. In addition, we analysed the effect of a molecular domain of laminin-1, the peptide SIKVAV, on M1 cells. This peptide was chosen because it is effective in cell proliferation and differentiation. M1 cells grown inside laminin-1 were mostly plasmacytoid-like, while cells treated by SIKVAV showed light and electron microscopic features of typical plasmacytoid cells. This peptide also modulated smooth-muscle actin expression in M1 cells. We demonstrated that laminin-1 and its derived peptide SIKVAV morphoregulates myoepithelioma cells in culture.

Neural adhesion molecule (N-CAM) in pleomorphic adenoma and carcinoma ex-pleomorphic adenoma

BACKGROUND

The neural cell adhesion molecule (N-CAM) has been implicated in the behaviour of the adenoid cystic carcinoma. In vitro, it was demonstrated that N-CAM inhibits cell invasion. The aim of this study was to search for N-CAM in the most common salivary gland tumour that has a malignant counterpart.

METHODS

We investigated the presence of N-CAM in pleomorphic adenoma and its malignant counterpart, the carcinoma ex-pleomorphic adenoma, using the immunohistochemistry technique.

RESULTS

Neural cell adhesion molecule was expressed in all cases of pleomorphic adenoma, strongly labelling the luminal cells of the double-layered ductform structures. This expression was weaker in neoplastic myoepithelial cells and progressively diminished at a distance from the luminal cells. In carcinoma, ex-pleomorphic adenoma N-CAM was either totally absent or faintly present at the apical pole of the few luminal cells.

CONCLUSIONS

As a result of the peculiar distribution of N-CAM in pleomorphic adenoma, we speculated that N-CAM behaves as a tumour-suppressor molecule, which is expressed in the benign neoplasm and which is down-regulated after malignancy, when the tumour assumes an invasive behaviour.

Perineural invasion in adenoid cystic carcinoma: Its causation/promotion by brain-derived neurotrophic factor

Adenoid cystic carcinoma (ACC) is a common salivary gland neoplasm with a lengthy clinical course and often late local recurrences after surgical resection. This is accounted for histologically by its infiltrative capacity and distinct propensity for perineural invasion. The expression of biological markers may help explain the clinicopathologic course in ACCs. Brain-derived neurotrophic factor (BDNF) is a growth factor known to be involved in neurogenesis. The aim of this study is to elucidate the expression of BDNF in ACCs, which is currently unknown. Twenty-nine cases of primary ACCs of the head and neck were immunostained to analyze BDNF protein expression. Staining intensity was described as focal or diffuse and graded on a 3-tiered scale. The study group comprised 20 adult females (age 30 to 78) and 9 adult males (age 22 to 70). Sites of involvement included the parotid gland (6 cases), nasopharynx (5), maxilla (4), palate (3), trachea (3), submandibular gland (2), buccal mucosa (2), mandible (1), tongue (1), lacrimal gland (1), and temporal region (1). All tumors exhibited diffuse cytoplasmic staining; 11 cases were classified as 1+ intensity, 12 cases as 2+, and six cases as 3+. Based on the results presented here, BDNF is unformly expressed by ACC and may play a causative role in its predilection for perineural invasion. ACCs may display neurogenesis with high levels of BDNF expression in some tumors. Further studies are warranted to gain better understanding of this possible relationship.

Effect of N-CAM on in vitro invasion of human adenoid cystic carcinoma cells

Adenoid cystic carcinoma of salivary glands is characterised by aggressive behaviour, high rate of local recurrences, neurotropism and late metastasis. In a previous work we demonstrated that adenoid cystic carcinoma cultured cells (CAC2 cells) expressed N-CAM. It was suggested that this expression, modulated by extracellular matrix, would be correlated to cell movement. The aim of our study was to verify whether CAC2 cells presented invasion capacity. Moreover, we tested whether the neural adhesion molecule (N-CAM) would participate in this process. CAC2 cells were either previously treated, or not (control), with a monoclonal antibody against N-CAM. Invasion assays were carried out using a modified Boyden chamber (Transwell chamber). CAC2 cells (10(5)) were dispensed into Transwell upper chamber on the top of Matrigel coated filter. The cells that invaded the filters in the first 8 h were counted under light microscopy, yielding data for the invasion rates (%). Control CAC2 cells presented an invasion rate of 5.28+/-0.04%. The invasion rate raised to 6.53+/-0.2% when N-CAM was blocked with monoclonal antibody. N-CAM impaired the adenoid cystic carcinoma cell invasion in vitro. Therefore, we suggest an anti-invasive role for N-CAM in adenoid cystic carcinoma.