Caveolin-1 gene is coordinately regulated with the multidrug resistance 1 gene in normal and leukemic bone marrow

Caveolin-1 is a structural protein that may function as a scaffold for plasma membrane proteins, one of which is P-glycoprotein (P-gp), product of the multidrug resistance-1 (MDR-1) gene. We tested the hypothesis that if P-gp and caveolin-1 interacted physically, caveolin-1 and MDR-1 genes might be coordinately regulated; by quantifiying their gene expression with quantitative-polymerase chain reaction. MDR-1 and caveolin-1 gene expressions were normalized to an internal control and related to a fixed calibrator by a comparative cycle-threshold (CT) method. In four different groups of marrow samples (20 normal, 56 acute myeloid leukemias (AML) at diagnosis, 48 AMLs at relapse, and 51 regenerating marrows), caveolin-1 and MDR-1 gene expressions were positively correlated. In 65 samples with MDR-1 over-expression, caveolin-1 and MDR-1 expressions were also correlated. The coordinate expression of caveolin-1 and MDR-1 suggests that they may either interact physically, or are involved in the same aberrant pathway(s) activated during MDR-1 up-regulation.