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To explore whether cholecystokinin-B/gastrin receptor (CCKBRwt) gene and its alternative splicing variant preserving intron 4 (CCKBRi4sv) are expressed in human gastric carcinoma cell line and tissue, we detect mRNA expression of CCKBRwt and CCKBRi4sv in 30 gastric carcinoma and their corresponding normal tissues, 10 gastritis, and 2 autopsied normal stomach specimens as well as in a gastric carcinoma cell line SGC-7901 cells by RT-PCR and sequencing. The results revealed that human normal, inflammatory, and malignant gastric tissues simultaneously expressed the classical and alternative splicing cholecystokinin-B/gastrin receptor genes. The alternative splicing variant contains the intron 4 of cholecystokinin-B/gastrin receptor gene.

hCGR of plasm membrane isolated from gastric carcinoma was studied by Radioligand Receptor Assay. The results showed that there is hCGR on plasm membrane from gastric carcinoma, with straight line of scatchard plot, and LH can’t displace the (binding of125I-hCG to plasm membrane. Compared with controls normal gastric mucosae), hCGR is increased in adenocarcinoma and well-differentiated carcinoma, but not changed in mucoid and poorly-differentiated carcinoma; hCGR is increased in ulcarative type of gastric carcinoma, but not altered in fungating type. hCGR existence on plasm membrane from gastric mucosa and carcinoma suggests that hCG may have some effects on gastric mucosa and carcinoma.

To compare the expression patterns of cholecystokinin-B (CCK-B)/gastrin receptor genes in matched human gastric carcinoma and adjacent non-neoplastic mucosa of patients with gastric cancer, inflammatory gastric mucosa from patients with gastritis, normal stomachs from 2 autopsied patients and a gastric carcinoma cell line (SGC-7901), and to explore their relationship with progression to malignancy of human gastric carcinomas.RT-PCR and sequencing were employed to detect the mRNA expression levels of CCK-B receptor and gastrin gene in specimens from 30 patients with gastric carcinoma and healthy bordering non-cancerous mucosa, 10 gastritis patients and normal stomachs from 2 autopsied patients as well as SGC-7901. The results were semi-quantified by normalizing it to the mRNA level of beta-actin gene using Lab Image software. The sequences were analyzed by BLAST program.CCK-B receptor transcripts were detected in all of human gastric tissues in this study, including normal, inflammatory and malignant tissues and SGC-7901. However, the expression levels of CCK-B receptor in normal gastric tissues were higher than those in other groups (P0.05), and its expressions did not correlate with the differentiation and metastasis of gastric cancer (P0.05). On the other hand, gastrin mRNA was detected in SGC-7901 and in specimens obtained from gastric cancer patients (22/30) but not in other gastric tissues, and its expression was highly correlated with the metastases of gastric cancer (P0.05).Human gastric carcinomas and gastric cancer cell line SGC-7901 cells coexpress CCK-B receptor and gastrin mRNA. Gastrin/CCK-B receptor autocrine or paracrine pathway may possibly play an important role in the progression of gastric cancer.