PLAG1, SOX10, and Myb Expression in Benign and Malignant Salivary Gland Neoplasms

BACKGROUND: Recent findings in molecular pathology suggest that genetic translocation and/or overexpression of oncoproteins is important in salivary gland tumorigenesis and diagnosis. We investigated PLAG1, SOX10, and Myb protein expression in various salivary gland neoplasm tissues. METHODS: A total of 113 cases of surgically resected salivary gland neoplasms at the National Cancer Center from January 2007 to March 2017 were identified. Immunohistochemical staining of PLAG1, SOX10, and Myb in tissue samples was performed using tissue microarrays. RESULTS: Among the 113 cases, 82 (72.6%) were benign and 31 (27.4%) were malignant. PLAG1 showed nuclear staining and normal parotid gland was not stained. Among 48 cases of pleomorphic adenoma, 29 (60.4%) were positive for PLAG1. All other benign and malignant salivary gland neoplasms were PLAG1-negative. SOX10 showed nuclear staining. In normal salivary gland tissues SOX10 was expressed in cells of acinus and intercalated ducts. In benign tumors, SOX10 expression was observed in all pleomorphic adenoma (48/48), and basal cell adenoma (3/3), but not in other benign tumors. SOX10 positivity was observed in nine of 31 (29.0%) malignant tumors. Myb showed nuclear staining but was not detected in normal parotid glands. Four of 31 (12.9%) malignant tumors showed Myb positivity: three adenoid cystic carcinomas (AdCC) and one myoepithelial carcinoma with focal AdCC-like histology. CONCLUSIONS: PLAG1 expression is specific to pleomorphic adenoma. SOX10 expression is helpful to rule out excretory duct origin tumor, but its diagnostic value is relatively low. Myb is useful for diagnosing AdCC when histology is unclear in the surgical specimen.

Conformational dynamism in d-(GAATTCCGTTATT) containing the complementary Myb responsive element d-CCGTTA: NMR and MD investigations.

Conformational features of the DNA segment d-(GAATTCCGTTATT) containing the complementary Myb responsive element CCGTTA has been studied by NMR and molecular dynamics calculations with a view to see the role of 3D structure in specific DNA recognition. From the low field imino proton NMR spectra, the DNA sequence is seen to exist as a duplex with pyrimidine mismatches in the centre. The 2D NMR spectra however show that teh molecule exhibits substantial dynamism even at 1 degree C. Several extra cross peaks, more than the expected number, are seen in particular regions in all the spectra. These observations indicate that the duplex undergoes slow transitions between base-paired and unbase-paired states due to mismatches in the centre. Hence, to characterise those transitions a restrained verlet dynamics has been performed for 50ps using X-PLOR force field. Structural intermediates at regular intervals have been analysed, and we see that the dynamism in the molecule results in substantial fluctuations in the different torsion angles. The mismatch sites are seen to exhibit the highest degree of fluctuations, with the bases stacking in and looping out of the duplex. The sugar geometry is seen to be fairly steady around the S domain for most of the residues.