A dopamine antagonist, domperidone enhances the replication of an oncolytic adenovirus in human tumour cells

Oncolytic adenoviruses (OAds) have attracted much attention as novel anticancer agents. Numerous studies have examined the antitumour effects of combinational use of an OAd and anticancer agents; however, few chemical compounds enhancing OAd infection have been reported. In this study, we screened a food and drug administration (FDA)- approved drug library containing 1134 small chemical compounds to identify chemical compounds that enhance OAd replication in human tumour cells. We found that domperidone, a dopamine D2 receptor antagonist, significantly enhanced the replication of an OAd in human tumour cells, including human pancreatic tumour cells, by two???fivefold, resulting in improvement of OAd- mediated tumour cell killing activities. The E1A mRNA levels were significantly increased in domperidone- pre- treated cells following OAd infection, which contributed to the promotion of OAd replication. However, mRNA levels of the dopamine D2 receptor (DRD2), which is known to be a target molecule of domperidone, were undetectable in most of the tumour cells by real- time reverse transcription (RT)- PCR analysis, indicating that domperidone promoted OAd replication by acting on a molecule other than DRD2. This study provides important clues for the improvement of OAd- mediated cancer therapy.