Roles for Myoepithelial Cells in the Formation and Maintenance of Submucosal Glands

SOX2 and SOX21 in Lung Epithelial Differentiation and Repair

The lung originates from the ventral foregut and develops into an intricate branched structure of airways, alveoli, vessels and support tissue. As the lung develops, cells become specified and differentiate into the various cell lineages. This process is controlled by specific transcription factors, such as the SRY-related HMG-box genes SOX2 and SOX21, that are activated or repressed through intrinsic and extrinsic signals. Disturbances in any of these processes during the development of the lung may lead to various pediatric lung disorders, such as Congenital Diaphragmatic Hernia (CDH), Congenital Pulmonary Airway Malformation (CPAM) and Broncho-Pulmonary Dysplasia (BPD). Changes in the composition of the airways and the alveoli may result in reduced respiratory function and eventually lead to chronic lung disorders. In this concise review, we describe different intrinsic and extrinsic cellular processes required for proper differentiation of the epithelium during development and regeneration, and the influence of the microenvironment on this process with special focus on SOX2 and SOX21.

Proliferative Activity of Myoepithelial Cells in Normal Salivary Glands and Adenoid Cystic Carcinomas Based on Double Immunohistochemical Labeling

Objective

To investigate the proliferative activity of myoepithelial cells (MEC) in normal salivary glands (NSG) and adenoid cystic carcinomas (ACC)) Study design. Twenty -three salivary gland specimens (13 ACC, 10 NSG) were studied using double immunohistochemical labeling for α smooth muscle actin (a-SMA) and proliferative cell nuclear antigen (PCNA)).

Results

There was a significant difference in PCNA reactivity in normal samples between myoepithelial cells of the parotid glands and of the submandibular glands, rates being higher in the latter. Neoplastic myoepithelial cells exhibited higher expression than neoplastic epithelial cells. In addition, myoepithelial cells of the cribriform type of ACC showed PCNA reactivity lower than those of the tubular type, whereas there was no statistically significant difference in epithelial cell rates. We could not identify myoepithelial cells in solid pattern due to α-SMA negativity; although high PCNA reactivity was evident.

Conclusion

These data suggest that the myoepithelial cell has a key role in ACC oncogenesis, more so than its epithelial cell counterparts. Moreover, the data provide a histopathological interpretation for aggressive clinical features of submandibular ACC, as the myoepithelial cells were less differentiated as compared to those of parotid glands.