The AP-2 Family of Transcription Factors-Still Undervalued Regulators in Gastroenterological Disorders

Activating enhancer-binding protein 2 (AP-2) is a family of transcription factors (TFs) that play crucial roles in regulating embryonic and oncogenic development. In addition to splice isoforms, five major family members encoded by the TFAP2A/B/C/D/E genes have been identified in humans, i.e., AP-2 alpha/beta/gamma/delta/epsilon. In general, the first three TFs have been studied more thoroughly than AP-2 delta or AP-2 epsilon. Currently, there is a relatively limited body of literature focusing on the AP-2 family in the context of gastroenterological research, and a comprehensive overview of the existing knowledge and recommendations for further research directions is lacking. Herein, we have collected available gastroenterological data on AP-2 TFs, discussed the latest medical applications of each family member, and proposed potential future directions. Research on AP-2 in gastrointestinal tumors has predominantly been focused on the two best-described family members, AP-2 alpha and AP-2 gamma. Surprisingly, research in the past decade has highlighted the importance of AP-2 epsilon in the drug resistance of gastric cancer (GC) and colorectal cancer (CRC). While numerous questions about gastroenterological disorders await elucidation, the available data undoubtedly open avenues for anti-cancer targeted therapy and overcoming chemotherapy resistance. In addition to gastrointestinal cancers, AP-2 family members (primarily AP-2 beta and marginally AP-2 gamma) have been associated with other health issues such as obesity, type 2 diabetes, liver dysfunction, and pseudo-obstruction. On the other hand, AP-2 delta has been poorly investigated in gastroenterological disorders, necessitating further research to delineate its role. In conclusion, despite the limited attention given to AP-2 in gastroenterology research, pivotal functions of these transcription factors have started to emerge and warrant further exploration in the future.