Collagen Type I may Influence the Expression of E-Cadherin and Beta-catenin in Carcinoma Ex-pleomorphic Adenoma

Heterogeneity and versatility of the extracellular matrix during the transition from pleomorphic adenoma to carcinoma ex pleomorphic adenoma: cumulative findings from basic research and new insights

Pleomorphic adenoma (PA) is the most common salivary gland tumor, accounting for 50%-60% of these neoplasms. If untreated, 6.2% of PA may undergo malignant transformation to carcinoma ex-pleomorphic adenoma (CXPA). CXPA is a rare and aggressive malignant tumor, whose prevalence represents approximately 3%-6% of all salivary gland tumors. Although the pathogenesis of the PA-CXPA transition remains unclear, CXPA development requires the participation of cellular components and the tumor microenvironment for its progression. The extracellular matrix (ECM) comprises a heterogeneous and versatile network of macromolecules synthesized and secreted by embryonic cells. In the PA-CXPA sequence, ECM is formed by a variety of components including collagen, elastin, fibronectin, laminins, glycosaminoglycans, proteoglycans, and other glycoproteins, mainly secreted by epithelial cells, myoepithelial cells, cancer-associated fibroblasts, immune cells, and endothelial cells. Like in other tumors including breast cancer, ECM changes play an important role in the PA-CXPA sequence. This review summarizes what is currently known about the role of ECM during CXPA development.

Evaluation of immunohistopathological profile of tubular and solid canine mammary carcinomas

Breast cancer is the most common cancer in women, but the incidence of mammary carcinoma in female dogs is even higher than in humans. These two tumors have similarities that can be seen by its biological behavior, molecular genetic alterations, and histology. This suggest that female dogs can be an excellent model for preclinical oncological studies. And the mammary carcinoma most frequently found in this species is the tubular and solid carcinomas. The extracellular matrix (ECM) has an important role in the progression of these tumors. Because of that we proposed to evaluate the ECM components of these carcinomas through histology with specific stains such as Masson's Trichrome, Picrosirius Red and the technique of scanning electron microscopy. With that, we found the presence of collagen fibers in the tubular carcinoma and around its parenchyma. On the other hand, the solid carcinoma presented collagen fibers throughout the parenchyma and around each tumor cell. With the transmission electron microscopy, we observed the presence of mitochondrias and rough endoplasmic reticulum in both tumors. And finally, we evaluated the expression of proteins through the immunohistochemistry, in which we found a high expression of VEGF, PCNA, CK-18 and vimentin in solid carcinoma, and a positive mark in the tubular and solid carcinoma for collagen I, III and fibronectin. Thus, we demonstrated some differences in the ECM of these mammary carcinomas, allowing a better understanding of its histological characteristics, and these data may contribute to future studies about therapies focused on tumors ECM.

A Rare Case of Mucoepidermoid Carcinoma ex Pleomorphic Adenoma arising in Minor Salivary Gland: Histopathological and Immunohistochemical Analysis

Mucoepidermoid carcinoma ex pleomorphic adenoma (MCxPA) is a rare salivary gland tumor predominantly found in major salivary glands. A case of MCxPA involving the soft tissue and bone of the retromolar region of a 26-year-old man is presented. The histopathological features revealed a neoplasm with predominance of pleomorphic adenoma (PA) elements, and presence of mucoepidermoid carcinoma malignant epithelial cells in several areas. Histochemical and immunohistochemical studies were positive for periodic acid Schiff, alcian blue, cytokeratins 7, 13, 14, and 19, Bcl-2, c-erbB-2, FGF-2 and maspin in the malignant areas. The patient underwent a partial resection of the left side of the mandible with neck dissection and MCxPA diagnosis was confirmed.

Myoepithelial cells from pleomorphic adenoma are not influenced by tumor conditioned media from breast ductal adenocarcinoma and melanoma cells: An in vitro study

Myoepithelial cells have been implicated in the regulation of the transition from in situ to invasive neoplasia in salivary gland tumors. Considering the importance of the microenvironment of the tumor, the present in vitro study therefore analyzed the morphological and phenotypic changes undergone by benign myoepithelial cells from pleomorphic adenoma (PA) stimulated by tumor-conditioned medium. The benign myoepithelial cells were obtained from PA and were cultured with fibronectin extracellular matrix protein, supplemented with tumor-conditioned medium, which was harvested from breast ductal adenocarcinoma AU-565 and melanoma Hs 852.T cells. The morphological alterations were assessed by immunofluorescence analysis using vimentin antibody. The α-smooth muscle actin (α-SMA) and fibroblast growth factor (FGF)-2 proteins were analyzed by indirect immunofluorescence and quantitative polymerase chain reaction (qPCR). No morphological changes were observed in the myoepithelial cells cultured in fibronectin protein under stimulation from either tumor-conditioned medium. The immunofluorescence results, which were supported by qPCR analysis, revealed that only α-SMA was upregulated in the fibronectin substratum, with or without tumor-conditioned medium obtained from breast ductal adenocarcinoma and melanoma cells. No significant difference in FGF-2 mRNA expression was detected when the cells were cultured either in the tumor-conditioned medium or in the fibronectin substratum. The tumor-conditioned medium harvested from breast ductal adenocarcinoma and melanoma did not affect myoepithelial cell differentiation and function, which was reflected by the fact that there was no observed increase in α-SMA and FGF-2 expression, respectively.

Immunoexpression of α2β1, α3β1, and α5β1 integrins in pleomorphic adenoma and adenoid cystic carcinoma

The aim of the present study was to compare the expression of α2β1, α3β1, and α5β1 integrins between 28 pleomorphic adenomas (PAs) and 10 adenoid cystic carcinomas (ACCs), and investigate differences in the expression of these integrins according to histologic subtypes of ACCs. It was taken into consideration the presence or absence, distribution, and localization of integrin immunoexpression. There was immunoreactivity in the intercellular contacts of the strands, nests, and solid sheets of PAs, as well as in the luminal and nonluminal cells of the duct-like structures, with a predominant immunoexpression in the luminal cells. The immunoexpression in ACCs varied with histologic subtype of the tumor. It was verified for a tendency of absence and/or reduced expression of all integrins in the solid subtype of ACCs. In general, PAs revealed a more diffuse and remarkable immunoexpression of all studied integrins than ACCs. The reduced integrins expression in ACC may be related to a lesser degree of cell differentiation in this neoplasm. Moreover, the absence and/or reduced expression of the studied integrins in solid ACC suggest a possible role in pathogenesis and more aggressive biological behavior of this histologic subtype.

Increased mucin 1 expression in recurrence and malignant transformation of salivary gland pleomorphic adenoma

AIMS

Pleomorphic adenoma (PA) is the most common salivary gland tumour with a tendency to recur (RPA) and a risk of malignant transformation. Mucin 1 (MUC-1) plays a role in the progression of many tumours and may be a marker to predict RPA. The aim of this study was to evaluate MUC-1 expression in different phases of the adenoma to carcinoma sequence.

METHODS AND RESULTS

Twenty-one cases of PA, 18 cases of RPA, three cases of RPA with focal transformation (TRPA) and 11 cases of carcinoma ex-pleomorphic adenoma (CXPA) were analysed immunohistochemically for MUC1 expression using an antibody to MUC1/DF3. MUC1 reactivity in RPA was stronger than that observed in PA and, in all the different carcinoma groups, MUC-1 expression was significantly higher in carcinoma than in RPA and PA.

CONCLUSION

This study has confirmed that MUC-1 is related to the recurrence of PA and that this molecule is associated with malignant transformation of PA with carcinoma cells overexpressing MUC-1.

Study of growth factors and receptors in carcinoma ex pleomorphic adenoma

Carcinoma ex pleomorphic adenoma (CXPA) is a rare malignant salivary gland tumor derived from a pre-existing pleomorphic adenoma. It is a good model to study the evolution of carcinogenesis, starting with in situ areas to frankly invasive carcinoma. Growth factors are associated with several biological and neoplastic processes by transmembrane receptors. In order to investigate, by immunohistochemistry, the expression of some growth factors and its receptors [EGF receptor, fibroblast growth factor, fibroblast growth factor receptor 1, fibroblast growth factor receptor 2, hepatocyte growth factor, c-Met, transforming growth factor (TGF) beta1, TGFbetaR-II and insulin-like growth factor receptor 1] in the progression of CXPA, we have used ten cases of CXPA in several degrees of invasion- intracapsular, minimally and frankly invasive carcinoma- with only epithelial component. Slides were qualitatively and semi-quantitatively evaluated according to the percentage of stained tumor cells from 0 to 3 (0 = less than 10%; 1 = 10-25%; 2 = 25-50%; 3 = more than 50% of cells). Malignant epithelial cells starting with in situ areas showed stronger expression than luminal cells of pleomorphic adenoma for all antibodies. Most of the intracapsular, minimally and frankly invasive CXPA presented score 3. However, score 2 was more evident in the frankly invasive one. In small nests of invasive carcinoma, negative cells were observed probably indicating that the proliferative process is replaced by the invasive mechanism. Altogether this data infers that these factors may contribute to cell proliferation during initial phases of the tumor.