Biology and modulation of multidrug resistance (MDR) in XXXX .

@entity1 @entity1262 @entity137 @entity5 @entity8993 @entity26 @entity3052 @entity11092 @entity7895 @entity1583 @entity1893
Drug resistance is one of the most significant impediments in the treatment of @entity1583 . There have been a number of studies on the incidence of @entity7895 expression in @entity5 cells or tissues, where detectable level of @entity7895 has been found in all types of @entity1583 . @entity7895 expression and significance in the @entity1 varies widely between reported studies on @entity1 with different ages and different disease types. Some of this validation can be accounted for by the threshold used to consider a sample positive for @entity7895 . However, @entity1262 is likely important in determining therapeutic outcome in @entity1 with @entity3052 , @entity1893 , and MM, although there is a suggestion of a different "behavior" between adult and childhood @entity3052 . In contrast, the significant prognostic association with expression of @entity11092 and @entity8993 is not consistent with disease types and disease stages. Clinical trials of modulation of MDR have been limited by following major factors. One is inability of achieving adequate blood levels of the modulator to reverse MDR, and the other is presence of other resistance mechanisms in addition to @entity7895 . The fact that @entity7895 modulators alter the pharmacokinetics of anti- @entity5 drugs can potentially increase @entity137 if the dose of anticancer drugs is not appropriately reduced. Recently, MDR modulators such as valspodar have demonstrated substantial inhibition of @entity7895 . In this presentation, a number of characteristics in VCR-resistant cells are reported. We demonstrate that acquisition of MDR or recovery from MDR phenotypes differ in one cell type to another, a marked correlation between @entity7895 and susuceptibility to @entity26 radicals, and altered gene expression of cell membrane antigen and apoptosis cascade genes. The efficacy of immunotherapies depends on the altered or unchanged target molecules of MDR cells. Thus, immunotherapies or reversal agents that aim at these substances in @entity5 cells should be useful to overcome MDR phenotypes.
