Correlation of P-glycoprotein expression with poor vascularization in human gallbladder carcinomas.

Aim: To investigate the relationship between the expression of P-glycoprotein (P-gp) and the degree of vascularization in gallbladder carcinomas.

Methods: P-gp was stained with streptavidin-peroxidase complex immunohistochemical method in routine paraffin-embedded sections of gallbladder carcinomas. Microvessel counts (MVC) were determined using factor-VIII-related antigens.

Results: The average MVC in 32 cases of gallbladder carcinomas was (34 +/- 10)/HP. The value of MVC was closely correlated with Nevin staging and tumor differentiation (P<0.01 and P<0.05). The total expression rate of P-gp was 62.5%. The P-gp expression rate in cases of Nevin staging S1-S3 (78.6%) was higher than that of S4-S5 (50.0%) with no statistical significance. The P-gp expression rate was not correlated with tumor differentiation or pathologic types. The value of MVC in P-gp (+) cases was markedly lower than that in P-gp (-) cases (P<0.01). The positive rate of P-gp was significantly higher in cases of smaller MVC than those of bigger MVC (P<0.05).

Conclusion: MVC may be used as one of the important parameters to reflect the biological behaviors of gallbladder carcinomas. As a major cause of drug resistance, the overexpression of P-gp is closely correlated with the poor vascularization in gallbladder carcinomas.