Study of growth factors and receptors in carcinoma ex pleomorphic adenoma

Molecular Factors in Carcinoma Ex Pleomorphic Adenoma: Systematic Review and Meta-Analysis

OBJECTIVE

Carcinoma ex pleomorphic adenoma (CXPA) is a rare malignant salivary gland tumor. Although multiple reviews have been published on salivary gland malignancies, it has been a decade since the last dedicated systematic review pertaining to CXPA alone was published. This study examines molecular factors in CXPA diagnosis.

DATA SOURCES

MEDLINE, CINAHL, Embase, Scopus, Web of Science (BIOSIS), Cochrane CENTRAL, Health Collection (Informit), OpenDOAR, and GreyNet International.

REVIEW METHODS

Systematic review and meta-analysis from inception to October 31, 2022 for all English language studies pertaining to "carcinoma ex pleomorphic adenoma." Predicted incidence of each biomarker was calculated with meta-analysis. Comparison against pleomorphic adenoma (PA) and salivary duct carcinoma (SDC) when reported within the same study are performed. Risk of bias performed with JBI tool for prevalence studies.

RESULTS

Of 19151 unique studies undergoing abstract screening, 55 studies (n = 1322 patients) underwent data analysis. Biomarkers with >3 studies were p53, HER2, AR, EGFR, PLAG1, ERBB, ER, PR, HMGA2, p16, p63, a-SMA, RAS, PTEN, PDL1, BRAF, PIK3CA, and c-kit. Highest incidence was seen in AR, EGFR, p16, and p53. Significant differences were demonstrated compared with PA and SDC. There was high heterogeneity and overall high risk of bias within studies.

CONCLUSION

Molecular factors are an area of interest in the diagnosis of CXPA. Our study results support examining CXPA as a discrete cohort in future targeted therapy trials. Laryngoscope, 134:1042-1053, 2024.

Identification of differentially expressed microRNAs as potential biomarkers for carcinoma ex pleomorphic adenoma

Carcinoma ex pleomorphic adenoma (CXPA) is a rare malignancy that transforms from PA. Early detection of the carcinoma by biopsy is difficult due to similar histopathology of the malignant and benign components. To address this, we investigated and compared the characteristic miRNA expression patterns across samples of the PA, carcinomatous portions (CA) of CXPA, as well as conventional PA. We selected 13 CXPA and 16 conventional PA FFPE samples, separated the PA and CA portions of CXPA samples and conducted miRNA profiling for each group. Among 13 transcripts that were differentially expressed between PA and CA of CXPA, eight miRNAs were up-regulated and five down-regulated in CA. Bioinformatic analysis revealed that the up-regulated miRNAs were related to cancer progression and down-regulated ones to tumor suppression. Additionally, seven miRNAs were significantly up-regulated in PA of CXPA compared to conventional PA, although they are histopathologically similar. Almost all of these transcripts interacted with TP53, a well-known tumor suppressor. In conclusion, we identified differentially expressed miRNAs in PA and CA of CXPA, which were closely associated with TP53 and various cancer-related pathways. We also identified differentially expressed miRNAs in the PA of CXPA and conventional PA which may serve as potential biomarkers.

The role of immune surveillance in malignant transformation of benign salivary gland tumors

Pleomorphic adenoma (PA), the most common salivary gland tumor, is a benign tumor that carries a risk of malignant transformation to various histologies of carcinoma ex pleomorphic adenoma (CA exPA). Recently, genomic analyses have provided deeper insights into the molecular biology of salivary gland cancers. However, the molecular processes that underlie the progression from PA to CA exPA are largely unknown. In this study, we used RNAseq data from CA ex PA of myoepithelial (n = 24) or salivary duct histology (n = 6), de novo myoepithelial carcinoma (n = 16) and de novo salivary duct carcinoma (n = 10), and compared their constituent immune tumor microenvironments. We found that increasing levels of immune infiltration and activation were associated with a generally lower probability of cancer developing ex-PA, suggesting that immune surveillance may constrain the malignant transformation of benign salivary tumors. More immunologically infiltrated tumors were more likely to have developed de novo. Taken together, these data suggest a role for tumor escape from immune surveillance in the development of CA exPA. The immune-cold microenvironments of CA ex PA tumors may in part explain their more aggressive clinical behavior.

Carcinoma ex pleomorphic adenoma: a case report and review of literature

Background

Carcinoma ex pleomorphic adenoma (CA-ex-PA) is extremely unusual in minor salivary glands of oral cavity. CAex-PA is a carcinomatous change as a primary or as a recurrence of pleomorphic adenoma.

Objective

Due to resemblance of clinical symptoms of Ca ex PA and benign pleomorphic adenoma, it is mandatory for surgeons to keep high degree of clinical alertness, considering the peculiarity of this tumor.

Case Report

54-year-old male presented with swelling on left side in the pre-auricular region from the middle of zygomatic arch to mastoid process and from tragus of the ear up to angle of mandible. Fine needle aspiration cytology revealed a mixture of benign and malignant components. Total left parotidectomy with left radical neck dissection followed by reconstruction with cervicodeltopectoral flap was performed. Combination of chemotherapy and radiotherapy were given to patient. Histologic examination and pre-operative fine needle aspiration cytology confirmed the diagnosis of Carcinoma ex pleomorphic adenoma (CA-ex-PA). Two-year follow-up of patient showed no recurrence of the lesion.

Conclusion

Due to the similarity in the clinical symptoms of CA-ex-PA and benign pleomorphic adenoma, it is vital that clinicians maintain a high degree of clinical vigilance, considering the oddity of this malignancy.

Anlotinib is effective in the treatment of advanced carcinoma ex pleomorphic adenoma of the submandibular gland

Background: Carcinoma ex pleomorphic adenoma (CXPA), a very rare malignancy found mostly in the major salivary glands, has no established standardized treatment.

Case presentation: This report describes a 67-year-old male with advanced CXPA who was effectively treated by anlotinib. Pleomorphic adenoma of the submandibular gland was first diagnosed in 1976 after a surgical resection of a mass underneath the jaw. The patient underwent re-excision 3 years later due to a recurrent pleomorphic adenoma. CXPA was first diagnosed in 2016 after a surgical removal of the left submandibular mass. A lung nodule was found on a chest CT scan in January 2018. Following a CT-guided lung biopsy that demonstrated findings consistent with pulmonary metastasis, the patient underwent local therapy (microwave ablation and radioactive seed implantation) but suffered a recurrence of disease approximately 6 months later. Anlotinib was administered orally at a dose of 12 mg daily on a 2 weeks on/1 week off schedule. A partial response was observed after two cycles of treatment. The disease remains in continued partial response after completion of his sixth cycle.

Conclusion: This is the first report for anlotinib in treating CXPA. Further pre-clinical and clinical studies are needed to validate the efficacy and safety of anlotinib in the treatment of CXPA.

Cooperation Between Pten and Smad4 in Murine Salivary Gland Tumor Formation and Progression

Salivary gland tumor (SGT) is a rare tumor type, which exhibits broad-spectrum phenotypic, biological, and clinical heterogeneity. Currently, the molecular mechanisms that cause SGT pathogenesis remain poorly understood. A lack of animal models that faithfully recapitulate the naturally occurring process of human SGTs has hampered research progress on this field. In this report, we developed an inducible keratin 5-driven conditional knockout mouse model to delete gene(s) of interest in murine salivary gland upon local RU486 delivery. We have deleted two major tumor suppressors, Pten, a negative regulator of the PI3K pathway, and Smad4, the central signaling mediator of TGFβ pathway, in the murine salivary gland. Our results have shown that deletion of either Pten or Smad4 in murine salivary gland resulted in pleomorphic adenomas, the most common tumor in human SGT patients. Deletion of both Pten and Smad4 in murine salivary gland developed several malignancies, with salivary adenoid cystic carcinoma (SACC) being the most frequently seen. Molecular characterization showed that SACC exhibited mTOR activation and TGFβ1 overexpression. Examination of human SGT clinical samples revealed that loss of Pten and Smad4 is common in human SACC samples, particularly in the most aggressive solid form, and is correlated with survival of SACC patients, highlighting the human relevance of the murine models. In summary, our results offer significant insight into synergistic role of Pten and Smad4 in SGT, providing a rationale for targeting mTOR and/or TGFβ signaling to control SGT formation and progression.

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.

Unraveling the role of epidermal growth factor receptor in oral lesions: Key to non surgical treatment modes

Epidermal growth factor receptor (EGFR) is a transmembrane receptor with tyrosine kinase activity, mediating actions of various growth factors including EGF, transforming growth factor-α, and neuregulins. Protein binding to ligand induces receptor modification, tyrosine autophosphorylation leading to cell signaling resulting in cellular proliferation. This receptor plays diverse roles in maintaining homeostasis and recent molecular advances identify that EGFR mutations are linked to several carcinomas. EGFR plays important roles in the development and maintenance of various oral structures, tooth development, eruption and morphogenesis. EGFR expression has also been studied in diverse oral pathologies like squamous cell carcinomas, potentially malignant lesions, lichen planus, salivary gland tumors and odontogenic cysts and tumours. The present review delves into the various general features of EGFR with an insight into its physiological and pathological role in the oral cavity. The clinical implications and upcoming role of EGFR inhibitors in the nonsurgical treatment of oral lesions has also been discussed.

The EGF signaling pathway influences cell migration and the secretion of metalloproteinases by myoepithelial cells in pleomorphic adenoma

During tumor development, benign neoplastic cells are influenced by the expression of cytokines, growth factors, and proteases present in the tumor microenvironment. Epidermal growth factor (EGF) is the most studied growth factor and is considered important for cell proliferation and migration. Metalloproteinases (MMPs) are also involved in tumor progression. The present study aimed to analyze the proliferation, viability and migration index of pleomorphic adenoma myoepithelial cells, in addition to the secretion of MMPs with EGF supplementation. Benign myoepithelial cells were cultured with two different EGF doses (5 and 10 ng/ml), and the influence of EGF on cell proliferation and viability, using trypan blue and MTT assays, respectively, after 24, 48, and 72 h, was evaluated. To analyze cellular morphology, hematoxylin-eosin staining and indirect immunofluorescence using the anti-vimentin antibody, was performed. In vitro migration assays were performed in Transwell chambers with an 8-μm pore covered with Matrigel and supplemented with 5 or 10 ng/ml of EGF, after 96 h. After 4 days of cell culture, ELISA was performed to determine the MMP-2 and MMP-13 levels. One-way analysis of variance (ANOVA) with post hoc Tukey test was applied, with a significance level of 0.05. The results revealed that EGF influences myoepithelial cell morphology, without alteration of proliferation and viability. The migration assay showed that EGF increased the mean index from 16 % in the control group to 40 and 76 % for 5 and 10 ng/ml of EGF, respectively. ELISA revealed that when the cells were supplemented with either of the EGF doses, an increase in MMP-2 levels was observed when compared with the control group (C). This study concludes that EGF aids in the production of MMP-2, which favors the dissolution of the basement membrane, contributing to cell migration and tumor progression, hence permitting contact between the myoepithelial cells and stroma.

Carcinoma ex pleomorphic adenoma: a comprehensive review of clinical, pathological and molecular data

Carcinoma ex pleomorphic adenoma (Ca ex PA) is a carcinoma arising from a primary or recurrent benign pleomorphic adenoma. It often poses a diagnostic challenge to clinicians and pathologists. This study intends to review the literature and highlight the current clinical and molecular perspectives about this entity. The most common clinical presentation of CA ex PA is of a firm mass in the parotid gland. The proportion of adenoma and carcinoma components determines the macroscopic features of this neoplasm. The entity is difficult to diagnose pre-operatively. Pathologic assessment is the gold standard for making the diagnosis. Treatment for Ca ex PA often involves an ablative surgical procedure which may be followed by radiotherapy. Overall, patients with Ca ex PA have a poor prognosis. Accurate diagnosis and aggressive surgical management of patients presenting with Ca ex PA can increase their survival rates. Molecular studies have revealed that the development of Ca ex PA follows a multi-step model of carcinogenesis, with the progressive loss of heterozygosity at chromosomal arms 8q, then 12q and finally 17p. There are specific candidate genes in these regions that are associated with particular stages in the progression of Ca ex PA. In addition, many genes which regulate tumour suppression, cell cycle control, growth factors and cell-cell adhesion play a role in the development and progression of Ca ex PA. It is hopeful that these molecular data can give clues for the diagnosis and management of the disease.