Expressions of HLA and B7 in KBv200 cell line before and after reversion of multidrug resistance

ZHANG Jian; ZHANG Ji-Ren; YUAN Ya-wei; LIN Xue-yan

doi:10.3321/j.issn:1673-4254.2000.06.001

Abstract：Objective To investigate the mechanism by which multidrug-resistant (MDR) tumor cells evade the host immune surveillance, the expressions of HLA and B7 in KBv200 cell line before and after the reversion of MDR were studied. Methods By using lipofectin-mediated transfection method, eukaryotic expression plasmids incorporated with an anti-MDR ribozyme were transfected into KBv200 cell line. RNA dot blotting assay was used to detect the expression of ribozyme in the transfected cell line. Northern blotting assay and immunohistochemistry assay were employed to examine the expression of mdr1 mRNA and P-glycoprotein in cell lines. The expressions of HLA-Ⅰ, HLA-Ⅱ, B7-1, B7-2 in the above cell lines were measured by flow cytometry. Results After being screened by 400 mg/ml antibiotic G418, the transformed colonies, KB/Vec, KBv200/Vec, KB/5mR3 and KBv200/5mR3 were obtained. The ribozyme was stably expressed in the cell line and could decrease the level of mdr1 mRNA expression by 83% and inhibit the formation of P-glycoprotein. Most tumor cells expressed MHC class Ⅰ molecules, and a small portion of the cells also expressed MHC-Ⅱ, B7-1 and B7-2 molecules. Similar HLA Ⅰ expression levels in every cell colonies were observed. The expressions of HLA-Ⅱ, B7-1, B7-2 were higher in KB cells than those in KBv200 cells, and were lowered after anti-mdr1-ribozyme transfection. The expressions of HLA-Ⅱ, B7-2 in KB cells were further enhanced after vincristine treatment. Conclusions Anti-mdr1-ribozyme is able to inactivate mdr1 mRNA and reverse the multidrug resistance phenotype in MDR cell lines. Compared with its parental sensitive cell line, KBv200 cells are easier to escape the host immune surveillance.