Evaluation of E1B-mutant Replicating Adenoviruses for Cancer Gene Therapy

Kim, Jae Sung; Kim, Joo Hang; Lee, Heui Ran; Jung, Kyeong Cheon; Yun, Chae Ok

Abstract

PURPOSE: Gene-attenuated replication-competent adenoviruses are emerging as a promising new modality for the treatment of cancer. In an effort to continually improve upon cancer gene therapy, we have modified gene- attenuated replication-competent adenoviruses so as to cause them to replicate efficiently and lyse the infected cancer cells more effectively.
MATERIALS AND METHODS
We modified the E1 region of the adenovirus (Ad) systematically, generating Ad-deltaE1B19, Ad-deltaE1B55, Ad-deltaE1B19/55, and Ad-WT. The cytopathic effects (CPE) and viral replication of these four gene modified adenoviruses were compared, and the morphology and DNA fragmentation of the infected cells was evaluated.
RESULTS
Among the constructed adenoviruses, E1B 19kD-inactivated adenovirus (Ad-deltaE1B19) was the most potent, inducing the largest-sized plaques and markedCPE. Moreover, cells infected with Ad-deltaE1B19 showed complete cell lysis with disintegrated cellular structure whereas cells infected with Ad-WT maintained intact cellular and nuclear membrane with properly structured organelles. TUNEL assay was also used to monitor DNA integrity, and a more profound induction of apoptosis was observed in the Ad-deltaE1B19 infected cells in comparison to wild type adenovirus infected cells.
CONCLUSION
We demonstrate that the inactivation of the E1B19kD gene in a replicating adenovirus leads to increased CPE, rapid viral release, improved cell-to-cell viral spread and increased induction of apoptosis.