Promoting role of cholecystokinin 2 receptor (CCK2R) in gastrointestinal stromal tumours pathogenesis

The cholecystokinin 2 receptor (CCK2R/CCKBR) is expressed in gastrointestinal stromal tumours (GIST). We sought to investigate the role of CCK2R in GIST pathogenesis. Molecular characterization of CCK2R was performed on a heterogeneous cohort of 50 GIST. In addition, CCK2R expression was evaluated by immunohistochemistry (IHC) using tissue microarray (TMA) containing 292 GIST, two cases of hyperplasia of interstitial Cajal's cells (ICC) and six gastric microscopic GIST. Mono-allelic loss of the CCK2R/11p15 allele was identified in 13.7% of GIST, having no impact on the level of CCK2R transcript expression. No CCK2R mutations were found. The CCK2Ri4sv, CCK2R splice variant with retention of intron 4, was detected in 6 out of 20 analysed tumours. Wild-type CCK2R transcripts were commonly expressed (57.1% of cases) and this expression highly correlated with gastric primary site of GIST (p