TY - JOUR
T1 - Tipifarnib sensitizes cells to proteasome inhibition by blocking degradation of bortezomib-induced aggresomes
AU - David, Ebenezer
AU - Kaufman, Jonathan L.
AU - Flowers, Christopher R.
AU - Schafer-Hales, Katherine
AU - Torre, Claire
AU - Chen, Jing
AU - Marcus, Adam I.
AU - Sun, Shi Yong
AU - Boise, Lawrence H.
AU - Lonial, Sagar
PY - 2010/12/9
Y1 - 2010/12/9
N2 - In this report, we investigated the mechanism responsible for synergistic induction of myeloma cell apoptosis induced by the combination of tipifarnib and bortezomib. Immunofluorescence studies revealed that bortezomib alone resulted in an accumulation of puncta of ubiquitinated proteins that was further enhanced by the addition of tipifarnib. These data suggest inhibition of the degradation of bortezomib-induced aggresomes; and consistent with this possibility, we also observed an increase in p62SQSTM1 in cells treated with the combination. However, autophagy in these cells appears to be normal as LC3BII is present, and autophagic flux appears to be unaffected as demonstrated by the addition of bafilomycin A1. Together, these data demonstrate that tipifarnib synergizes with bortezomib by inducing protein accumulation as a result of the uncoupling of the aggresome and autophagy pathways.
AB - In this report, we investigated the mechanism responsible for synergistic induction of myeloma cell apoptosis induced by the combination of tipifarnib and bortezomib. Immunofluorescence studies revealed that bortezomib alone resulted in an accumulation of puncta of ubiquitinated proteins that was further enhanced by the addition of tipifarnib. These data suggest inhibition of the degradation of bortezomib-induced aggresomes; and consistent with this possibility, we also observed an increase in p62SQSTM1 in cells treated with the combination. However, autophagy in these cells appears to be normal as LC3BII is present, and autophagic flux appears to be unaffected as demonstrated by the addition of bafilomycin A1. Together, these data demonstrate that tipifarnib synergizes with bortezomib by inducing protein accumulation as a result of the uncoupling of the aggresome and autophagy pathways.
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U2 - 10.1182/blood-2010-03-272393
DO - 10.1182/blood-2010-03-272393
M3 - Article
C2 - 20844234
AN - SCOPUS:78650041246
SN - 0006-4971
VL - 116
SP - 5285
EP - 5288
JO - Blood
JF - Blood
IS - 24
ER -