CD24 and CD44 in salivary gland pleomorphic adenoma and in human salivary gland morphogenesis: differential markers of glandular structure or stem cell indicators?

Immunohistochemical comparative analysis of tumor stem cell biomarkers in pleomorphic adenoma, adenoid cystic carcinoma and mucoepidermoid carcinoma of salivary glands

OBJECTIVE

This study aimed to compare the immunoexpression profile of tumor stem cell (TSC) biomarkers CD44, aldehyde dehydrogenase 1 (ALDH1), OCT4, and SOX2 in salivary gland tumors (SGTs).

STUDY DESIGN

Sixty tissue specimens of SGTs, including 20 pleomorphic adenomas, 20 adenoid cystic carcinomas (ACCs), and 20 mucoepidermoid carcinomas, in addition to 4 samples of normal glandular tissue, were subjected to immunohistochemistry. The expression of the biomarkers in the parenchyma and stroma was evaluated. Data were analyzed statistically by nonparametric tests (P < .05).

RESULTS

Higher parenchymal expression of ALDH1, OCT4, and SOX2 was observed in pleomorphic adenomas, ACCs, and mucoepidermoid carcinomas, respectively. Most ACCs did not express ALDH1. Higher immunoexpression of ALDH1 in major SGTs (P = .021) and of OCT4 in minor SGTs (P = .011) was found. Immunoexpression of SOX2 was related to lesions without myoepithelial differentiation (P < .001) and malignant behavior (P = .002). Furthermore, OCT4 was related to myoepithelial differentiation (P = .009). CD44 expression was related to a better prognosis. Stromal immunoexpressions of CD44, ALDH1, and OCT4 were higher in malignant SGTs.

CONCLUSIONS

Our findings suggest the participation of TSCs in the pathogenesis of SGTs. We emphasize the need for further investigations into the presence and role of TSCs in the stroma of these lesions.

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.

CD24-gold nanocomposite as promising and sensitive biomarker for cancer stem cells in salivary gland tumors

Cancer stem cells are highly tumorigenic cells in the majority of the tumor that are responsible for the initiation, rapid growth, invasion, metastasis, and therapeutic resistance associated with various human cancers. The aim of this project is to assess a diagnostic and prognostic biomarker for the detection of cancer stem cells in salivary gland tumors using gold nanoparticles that are synthesized and conjugated to CD24 primer to form a CD24-Gold Nanocomposite. Sixty cases were included (29 pleomorphic adenoma, 19 carcinoma ex pleomorphic adenoma, and 12 normal controls). Alterations in biomarker expression between studied groups were analyzed and correlated with clinicopathological characteristics using Fisher's exact and Chi-square tests. ROC and Kaplan-Meier curves were used to validate diagnostic and prognostic values, respectively. This study confirms that CD24-Gold Nanocomposite served as a promising and highly sensitive biomarker in salivary gland tumor diagnosis and prognosis prediction.

Immunohistochemical expression of OCT4 and CD44 in major and minor salivary gland neoplasms

The aim of this study was to identify tumor parenchyma cells exhibiting immunohistochemical profile of stem cells by evaluating the immunoreactivity of OCT4 and CD44 in a number of cases of salivary gland neoplasms. The sample consisted of 20 pleomorphic adenomas, 20 mucoepidermoid carcinomas, and 20 adenoid cystic carcinomas located in major and minor salivary glands. The expression of OCT4 and CD44 was evaluated by the percentage of positive cells and the intensity of expression. All studied cases showed positive expression of OCT4 and CD44 and higher values than the control groups. For OCT4, luminal and non-luminal cells were immunostained in the case of pleomorphic adenomas and adenoid cystic carcinomas. Moreover, the immunoreactivity of CD44 was particularly evident in the non-luminal cells of these lesions. In mucoepidermoid carcinomas, there was immunoreactivity for both markers in squamous and intermediate cells and absence of staining in mucous cells. For both markers, a significantly higher immunostaining was verified in neoplasms located in the major salivary glands compared with lesions in minor salivary glands (p<0.001). In the total sample and in minor salivary glands, malignant neoplasms exhibited higher immunoreactivity for OCT4 than pleomorphic adenoma. A significant moderate positive correlation (r = 0.444 and p ≤ 0.001) was found between OCT4 and CD44 immunoexpression in the total sample. The high expression of OCT4 and CD44 may indicate that these proteins play an important role in identifying tumor stem cells.

Technique of the Buccal Fat Pad Flap as an Alternative for the Surgical Defect of Pleomorphic Adenoma

Pleomorphic adenoma (PA) is the most common benign salivary gland neoplasm, and its malignant transformation rarely occurs. Diagnosis is based on clinical features of local or regional malignancy or distant metastasis, and histological identification of invasion and cellular atypia. Buccal fat pad, also called Bichat fat pad, is an excellent option to create tissue coverage over surgically treated areas, providing great blood supply. Thus, this study aims to report a surgical treatment of a patient who reported to the Oral and Maxillofacial Surgery and Traumatology service of a hospital in the city of Fortaleza, presenting a large lesion in the right side of the palate. Clinical examination revealed a nodular volume increase with smooth surface, sessile insertion, firm to palpation and coloration similar to the mucosa, no pain complaints, and 2 years of evolution. Orthopantomographic examination did not reveal alterations in the adjacent anatomical structures. After clinical and radiographic evaluation, an incisional biopsy was performed and histopathological diagnosis was PA. Patient was submitted to surgery for tumor excision with narrow surgical margins, including oral lining mucosa to reduce recurrence chances. In the same surgical act, after the excision of the lesion, the right buccal fat pad pedicle flap was sutured onto the residual mucosa in order to act as a framework for re-epithelialization of the palatal mucosa, phenomenon of metaplasia, and reduction of patient's morbidity. Surgical piece obtained was sent to anatomopathological study, confirming initial diagnosis. After 12-month follow-up, patient is esthetically and functionally rehabilitated, and satisfied with clinical and surgical plans executed.

Expression of cell adhesion molecule CD44 in mucoepidermoid carcinoma and its association with the tumor behavior

Background

The most common malignant salivary gland tumors that affect both adult and children is mucoepidermoid carcinoma. It usually affects both minor and major salivary glands but parotid gland is considering the most common site in which this tumor arises. CD44, a trans-membrane glycoprotein, is an adhesion molecule of cell surface that play a role in the connections between cell-cell and cell-matrix. Many malignant tumors express high levels of CD44, thus, CD44 may be used as an indicator of aggressive behavior of some human malignancy. We evaluate CD44 expression in different grades of mucoepidermoid carcinoma and determine whether expression of CD44 can be used to predict tumor aggressiveness.

Methods

Fifteen cases of mucoepidermoid carcinoma were retrieved from the oral pathology archives and grouped according to the histological grade as well as the clinical behavior regarding metastases and/or recurrence. Tissue sections were immunohistochemically stained for CD44. CD44 staining was scored for intensity and proportion of cells stained.

Results

A higher proportion of high-grade tumor tissues showed moderate or strong CD44 staining compared to low-grade tumors. Additionally, CD44 expression was stronger in tumors from patients with recurrences or metastases, but theses differences were not statistically significant.

Conclusion

Our result showed that mucoepidermoid carcinomas are immunohistochemistry positive to CD44 compare to normal. A trend of CD44 expression associated with different histological grading and aggressive behavior of this tumor.

p53 expression in pleomorphic adenoma of salivary glands: A systematic review and meta-analysis

OBJECTIVE

There are conflicting data regarding immunohistochemical expression of p53 in pleomorphic adenoma. This systematic review and meta-analysis aimed to examine whether p53 expression has a role in the pathogenesis of pleomorphic adenoma.

DESIGN

A comprehensive literature search for relevant studies published from 2000 up to end of 2014 was performed using PubMed, EMBASE and the Cochrane Library Databases. Only articles in which p53 detected by immunohistochemical staining were included. The meta-analysis was done using Comprehensive Meta-Analysis software.

RESULTS

Eighteen eligible studies were included in this meta-analysis. Heterogeneity measures showed a statistically significant Cochrane Q value (P-value<0.001). The random effects model showed an effect size of 0.254 with a 95% CI (0.139-0.417). The overall p53 positivity is 25.4%.

CONCLUSION

Mutant p53 has to be detected by more precise techniques to emphasize on its role in development of pleomorphic adenoma of salivary gland.

Immunolocalization of RhoA and RhoB GTPases in pleomorphic adenoma of the parotid

The pleomorphic adenoma of the parotid (PA) is characterized by the high tissues diversity. Rho GTPases participate in signal transduction pathways that regulate several biological processes, including cell differentiation. A quantitative analysis of RhoA and RhoB GTPases immunoexpression was performed in healthy parotids and in 23 PA cases, predominantly epithelial (PE) or mesenchymal (PM), followed by Student's t test. In PE cases, RhoA immunoexpression was higher in sheets and trabeculae (p < 0.05), whereas RhoB only in sheets (p < 0.05). In normal parotids, RhoA and RhoB were not detected in acinar cells. Ducts have expressed RhoA and RhoB in normal parotids and PA. RhoB was detected in myxoid and chondromyxoid cells. Normal parotids do not express RhoA and RhoB proteins in acinar cells, indicating a lack of function in secretory cells. Despite RhoA and RhoB GTPases are different in their biological roles, no significant difference in immunoexpression of the RhoA and RhoB GTPases in epithelial and mesenchymal structures of PA.

A review: Immunological markers for malignant salivary gland tumors

Salivary gland cancers are rare. Around 8 out of 10 salivary gland tumors (80%) are in the parotid. Just fewer than 2 out of 10 salivary gland cancers develop in the other two salivary glands - the submandibular or sublingual glands. Fewer than 1 in 10 cancers start in the minor salivary glands. There are many different types of salivary gland cancers. The most common is mucoepidermoid carcinoma (MEC). Just over 3 out of 10 (25-35%) salivary gland cancers (SGT, SGC) are of this type. The others include adenoid cystic carcinoma (ACC), acinic cell carcinoma, carcinoma ex-pleomorphic adenoma (Ca-PA), polymorphous low grade adenocarcinoma (PLGA) and some newly discovered salivary gland tumors. Because of the infrequency of salivary gland tumors and their complex histopathological diagnosis, it is difficult to exactly predict their clinical course by means of its recurrence, malignant progression or metastasis. Salivary gland tumors always pose problems in diagnosis. This review provides an insight into the recent concepts and immunohistochemical markers to diagnose the malignant salivary gland tumors (SGT), thus guiding the Ear, Nose and Throat specialists, Oral and Maxillofacial Surgeons, General Pathologists and other medical and dental specialists thereby enabling them to make correct diagnosis and provide the appropriate treatment.