TY - JOUR
T1 - The putative BH3 mimetic S1 sensitizes leukemia to ABT-737 by increasing reactive oxygen species, inducing endoplasmic reticulum stress, and upregulating the BH3-only protein NOXA
AU - Soderquist, Ryan
AU - Pletnev, Alexandre A.
AU - Danilov, Alexey V.
AU - Eastman, Alan
N1 - Funding Information:
Acknowledgments This research was supported by a Translational Research Grant from the Leukemia and Lymphoma Society and a Cancer Center Support Grant to the Norris Cotton Cancer Center (NIH CA23108). Support to A.V.D. was provided by a National Cancer Institute new faculty award (NIH CA023108-31S4) to the Norris Cotton Cancer Center.
PY - 2014/1
Y1 - 2014/1
N2 - S1 is a putative BH3 mimetic proposed to inhibit BCL2 and MCL1 based on cell-free assays. However, we previously demonstrated that it failed to inhibit BCL2 or induce apoptosis in chronic lymphocytic leukemia (CLL) cells, which are dependent on BCL2 for survival. In contrast, we show here that S1 rapidly increases reactive oxygen species, initiates endoplasmic reticulum stress, and upregulates the BH3-only protein NOXA. The BCL2 inhibitors, ABT-737, ABT-263, and ABT-199, have demonstrated pro-Apoptotic efficacy in cell lines, while ABT-263 and ABT-199 have demonstrated efficacy in early clinical trials. Resistance to these inhibitors arises from the upregulation of anti-Apoptotic factors, such as MCL1, BFL1, and BCLXL. This resistance can be induced by co-culturing CLL cells on a stromal cell line that mimics the microenvironment found in patients. Since NOXA can inhibit MCL1, BFL1, and BCLXL, we hypothesized that S1 may overcome resistance to ABT- 737. Here we demonstrate that S1 induces NOXA-dependent sensitization to ABT-737 in a human promyelocytic leukemia cell line (NB4). Furthermore, S1 sensitized CLL cells to ABT-737 ex vivo, and overcame resistance to ABT-737 induced by co-culturing CLL cells with stroma.
AB - S1 is a putative BH3 mimetic proposed to inhibit BCL2 and MCL1 based on cell-free assays. However, we previously demonstrated that it failed to inhibit BCL2 or induce apoptosis in chronic lymphocytic leukemia (CLL) cells, which are dependent on BCL2 for survival. In contrast, we show here that S1 rapidly increases reactive oxygen species, initiates endoplasmic reticulum stress, and upregulates the BH3-only protein NOXA. The BCL2 inhibitors, ABT-737, ABT-263, and ABT-199, have demonstrated pro-Apoptotic efficacy in cell lines, while ABT-263 and ABT-199 have demonstrated efficacy in early clinical trials. Resistance to these inhibitors arises from the upregulation of anti-Apoptotic factors, such as MCL1, BFL1, and BCLXL. This resistance can be induced by co-culturing CLL cells on a stromal cell line that mimics the microenvironment found in patients. Since NOXA can inhibit MCL1, BFL1, and BCLXL, we hypothesized that S1 may overcome resistance to ABT- 737. Here we demonstrate that S1 induces NOXA-dependent sensitization to ABT-737 in a human promyelocytic leukemia cell line (NB4). Furthermore, S1 sensitized CLL cells to ABT-737 ex vivo, and overcame resistance to ABT-737 induced by co-culturing CLL cells with stroma.
KW - Atf3
KW - Bcl2
KW - Bclxl
KW - Mcl1
KW - Noxa
KW - Reactive Oxygen Species
UR - http://www.scopus.com/inward/record.url?scp=84892687335&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=84892687335&partnerID=8YFLogxK
U2 - 10.1007/s10495-013-0910-y
DO - 10.1007/s10495-013-0910-y
M3 - Article
C2 - 24072590
AN - SCOPUS:84892687335
SN - 1360-8185
VL - 19
SP - 201
EP - 209
JO - Apoptosis
JF - Apoptosis
IS - 1
ER -