Effects of anti-leukemia drug Harringtonine on the levels of centromere proteins and gene expression of CenpB in L1210 cells.

In this study, we investigated the effects of the anti-leukemia drug Harringtonine (HT) on the levels of centromere proteins and gene expression of centromere protein CenpB in L1210 cells. The intensity of centromere fluorescence, shown by indirect immunofluorescence staining, decreased with HT treatment. Western blot showed that the anti-centromere antibody (ACA) serum used in this study recognized 8 proteins with different molecular weights: 140, 80, 70, 56, 37, 34, 32 and 17 kD. The amounts of some of these proteins were reduced to different extents by HT treatment. The ACA antibodies that recognized the 17, 80 and 140 kD proteins in L1210 cells also cross-reacted with 3 proteins with similar molecular weights which are known to be CenpA, CenpB and CenpC, respectively. Northern and Dot blot analyses revealed that the level of CenpB mRNA in HT-treated cells was markedly lower than that in the untreated cells. These results suggest that HT may cause a decrease in the intracellular level of some centromere proteins, probably by inhibiting mRNA expression of corresponding genes. Moreover, it is possible that the cell-killing and appotosis-inducing effects of HT may be mediated by the inhibition of the expression of CenpB and other centromere protein genes.