325. Persistence of hAQP1 Expression in Human Salivary Gland Cells Following AdhAQP1 Transduction Is Associated With a Lack of Methylation of hCMV Promoter

Abstract

In 2012, we reported that five out of 11 subjects in a clinical trial (NCT00372320) of AdhAQP1 to radiation-damaged parotid glands showed increased saliva flow rates and decreased symptoms over the initial 42 days. AdhAQP1 is a first generation, E1-deleted, replication-defective, serotype 5 adenoviral vector encoding human aquaporin-1 (hAQP1). This vector uses the human cytomegalovirus enhancer/promoter (hCMVp). Since subject responses were longer than expected, we hypothesized that the hCMVp may not be methylated in human salivary gland cells to the extent previously observed in rodent salivary gland cells. To test our hypothesis, initially we transduced mouse and rat cell lines in vitro, or submandibular glands in vivo, with the same AdhAQP1 used in the clinical trial. The hCMVp was gradually methylated over time in rodent cells and associated with a decreased functional hAQP1 expression. The hCMVp, however, was not methylated in human salivary gland primary cultures or human salivary gland cell lines after transduction with AdhAQP1. Importantly, hAQP1 maintained its function in those cells. These data suggest that the hCMVp in AdhAQP1is likely not methylated, resulting in an unexpectedly longer functional expression of hAQP1 in transduced human salivary gland cells.