Relationship between expression of gastrin, somatostatin, Fas/FasL and caspases in large intestinal carcinoma.

Aim: To explore the correlation between the mRNAs and protein expression of gastrin (GAS), somatostatin (SS) and apoptosis index (AI), apoptosis regulation gene Fas/FasL and caspases in large intestinal carcinoma (LIC).

Methods: Expression of GAS and SS mRNAs were detected by nested RT-PCR in 79 cases of LIC. Cell apoptosis was detected by molecular biology in situ apoptosis detecting methods (TUNEL). Immunohistochemical staining for GAS, SS, Fas/FasL, caspase-3 and caspase-8 was performed according to the standard streptavidin-biotin-peroxidase (S-P) method.

Results: There was a significant positive correlation between mRNA and protein expression of GAS and SS (GASrs = 0.99, P < 0.01; SSrs = 0.98, P < 0.01). There was significant difference in positive expression rates of GAS, SS mRNAs and protein among different histological differentiation, histological types and Dukes' stage of LIC. The AI in GAS high and moderate expression groups was significantly lower than that in low expression groups (3.75 +/- 2.38 vs 7.82 +/- 2.38, P < 0.01; 5.51 +/- 2.66 vs 7.82 +/- 2.38, P < 0.01), and the AI in SS high and moderate expression groups was significantly higher than that in low expression groups (9.03 +/- 1.76 vs 5.35 +/- 3.00, P < 0.01; 7.44 +/- 2.67 vs 5.35 +/- 3.00, P < 0.01). There was a significant negative correlation between the integral ratio of GAS to SS and the AI (r(s) = -0.41, P < 0.01). The positive expression rate of FasL in GAS high and moderate expression groups was higher than that in low expression group (90.9% and 81.0% vs 53.2%, P < 0.05). The positive expression rates of Fas, caspase-8 and caspase-3 in SS high (90.0%, 90.0% and 100%) and moderate (80.0%, 70.0%, 75.0%) expression groups were higher than that in low expression group (53.1%, 42.9%, 49.0%) (90.0% and 80.0% vs 53.1%, P < 0.05; 90.0% and 70.0% vs 42.9%, P < 0.05; 100.0% and 75.0% vs 49.0%, P < 0.05). There was a significant positive correlation between the integral ratio of GAS to SS and the semiquantitative integral of FasL (rs = 0.32, P < 0.01).

Conclusion: GAS and SS play important roles in the regulation and control of cell apoptosis in LIC, and the mechanism may be directly related to the aberrant expression of Fas/FasL. The GAS and SS will be valuable targets of the biological behavior of LIC.