Differential expression of ARID3B in normal adult tissue and carcinomas

• ARID3B is expressed highly in squamous epithelium.
• ARID3B isoforms are coordinately regulated in adult tissues at the level of RNA.
• The ARID3 subfamily of proteins has distinct expression patterns.
• ARID3B expression is decreased in esophageal and stomach malignancies.

ARID3B is a DNA binding protein that is overexpressed in neuroblastoma and ovarian cancer. To understand the extent that ARID3B participates in tumor development, we assessed protein expression of ARID3B in normal adult and malignant tissues. We found that ARID3B is highly expressed in differentiated layers of squamous epithelium. We also examined expression of an alternative splice form of ARID3B and found that it has similar but not identical expression patterns to the full length ARID3B isoform. ARID3B has two closely related paralogues, ARID3A and ARID3C. Each of these 3 family members exhibits different patterns of expression. Of the ARID3 family members, ARID3B is the most widely expressed and is particularly expressed in epithelium. In addition to examining normal tissue, we investigated ARID3B expression in a variety of tumor types. Most notably we found that ARID3B expression is decreased in esophagus and stomach tumors compared to normal corresponding tissues. Our results indicate that the different patterns of ARID3B in normal tissues translate into different roles for ARID3B in carcinomas.