Salivary gland tumors: profiling and biomarker discovery

Bloemena, E. [Promotor]Veerman, E.C.I. [Promotor]Bolscher, J.G.M. [Copromotor

Mucoepidermoid carcinoma-associated expression of MUC5AC, MUC5B and mucin-type carbohydrate antigen sialyl-Tn in the parotid gland

Objectives The aberrant expression of mucins and mucin-type carbohydrates has been described in many types of cancer, including mucoepidermoid carcinoma (MEC), a malignant salivary gland tumor. In this study, we examined the aberrant expression patterns of mucins (MUC1, MUC4, MUC5AC and MUC5B), simple mucin-type carbohydrate antigens (Tn, sialyl-Tn and T) and mature carbohydrate antigens (Lewisa and sulfo-Lewisa antigens) in MEC originating from the parotid gland, which normally does not secrete mucins. Design We conducted an immunohistochemical study to investigate the presence of mucins and carbohydrates in 24 MEC samples originating from the parotid gland and in surrounding normal tissue of the same gland in comparison 6 samples of normal salivary glands. The expression levels were compared with respect to the histological grading. Furthermore, 24 MEC samples from non-parotid salivary glands were included. Results We observed loss of topology of membrane-bound MUC1 and MUC4, and de novo expression of MUC5AC, MUC5B and sialyl-Tn in MEC that originated in the parotid gland. Furthermore, mucins MUC1, MUC4 and carbohydrate antigens Tn, sialyl-Tn, T, Lewisa and sulfo-Lewisa were overexpressed in MEC samples compared to surrounding normal salivary gland tissues. MUC1 was expressed in both low- and high grade MECs, whereas MUC4 was not expressed in high grade MECs of the parotid gland. Conclusion During the development of MEC in the parotid gland, the genes for gel-forming secretory mucins are switched on. Besides these MEC tissues overexpress short oligosaccharides, suggesting that the glycosylation machinery is altered

Discovery and prevalidation of salivary extracellular microRNA biomarkers panel for the noninvasive detection of benign and malignant parotid gland tumors

Purpose: This study was conducted to explore the differences in salivary microRNA (miRNA) profiles between patients with malignant or benign parotid gland tumors as a potential preoperative diagnostic tool of tumors in the salivary glands. Experimental Design: Whole saliva samples from patients with malignant (n = 38) or benign (n = 29) parotid gland tumors were obtained from the Salivary Gland Tumor Biorepository (SGTB). After total RNA isolation, human miRNA cards were used for miRNA profiling. The differential miRNA expression was analyzed using two-sided Wilcoxon test. Quantitative real-time PCR (qRT-PCR) was used to validate selected miRNAs in an independent sample set. Receiver-operating characteristics curve and probability of malignancy was exploited to evaluate the diagnostic power of the validated miRNAs. Results: With miRNA profiling, 57 of 750 investigated miRNAs were differently expressed, of which 54 showed higher miRNA expression in samples from patients with malignant tumors than those from patients with benign tumors. Validating the expression in an independent sample set of 9 miRNAs revealed indeed higher expression of miRNAs in malignant samples compared with benign samples. The expression of 6 validated miRNAs was statistically significantly different between the two groups (P < 0.05). A four miRNA combination was able to discriminate between saliva samples from patients with malignant tumors from those of patients with benign parotid gland tumors (sensitivity 69%, specificity 95%). Conclusions: Salivary miRNA profiles differ in saliva from patients with malignant from saliva from patients with a benign parotid gland tumor. These preliminary results are promising to develop a noninvasive diagnostic tool for diagnosing tumors in the salivary glands

Human salivary micro-RNA in patients with parotid salivary gland neoplasms

Background Currently, clinical examination, ultrasound scanning (with or without fine needle aspiration cytology), preoperative CT-scan and MRI are available for the differential diagnosis of parotid gland swelling. A preliminary non-invasive salivary diagnostic tool may be helpful in the clinical decision making process. Altered salivary micro-RNA (miRNA) expression levels have been observed in saliva from patients with various cancers. Therefore, we investigated miRNA expression levels in saliva samples from patients with a parotid gland neoplasm using Human miRNA cards in comparison to controls. Results In the discovery phase, eight miRNAs were identified having different expression levels in patients compared to controls. In the validation phase, the differences in miRNA expression levels between patients and controls were confirmed for seven out of eight discovered miRNAs (p < 0.001). A combination of two miRNAs yielded a receiver-operator-characteristics curve with an AUC of 0.94 (95% CI: 0.87-1.00; sensitivity 91%; specificity 86%). Validation of discovered miRNAs in segregated collected parotid saliva revealed that expression of these miRNAs differ between whole saliva and parotid saliva. Conclusions A two miRNA combination can predict the presence of a parotid gland neoplasm. Furthermore, this study suggested that the identified, patient-specific, salivary miRNAs were not derived from the parotid gland itself