TY - JOUR
T1 - mTOR inhibitors suppress homologous recombination repair and synergize with PARP inhibitors via regulating SUV39H1 in BRCA-proficient triple-negative breast cancer
AU - Mo, Wei
AU - Liu, Qingxin
AU - Lin, Curtis Chun Jen
AU - Dai, Hui
AU - Peng, Yang
AU - Liang, Yulong
AU - Peng, Guang
AU - Meric-Bernstam, Funda
AU - Mills, Gordon B.
AU - Li, Kaiyi
AU - Lin, Shiaw Yih
N1 - Publisher Copyright:
© 2015 AACR.
PY - 2016/4/1
Y1 - 2016/4/1
N2 - Purpose: Triple-negative breast cancer (TNBC) is a highly heterogeneous disease and has the worst outcome among all subtypes of breast cancers. Although PARP inhibitors represent a promising treatment in TNBC with BRCA1/BRCA2 mutations, there is great interest in identifying drug combinations that can extend the use of PARP inhibitors to a majority of TNBC patients with wild-type BRCA1/BRCA2. Here we explored whether mTOR inhibitors, through modulating homologous recombination (HR) repair, would provide therapeutic benefit in combination with PARP inhibitors in preclinical models of BRCA-proficient TNBC. Experimental Design: We have studied the effects of mTOR inhibitors on HR repair following DNA double-strand breaks (DSB). We further demonstrated the in vitro and in vivo activities of combined treatment of mTOR inhibitors with PARP inhibitors in BRCA-proficient TNBC. Moreover, microarray analysis and rescue experiments were used to investigate the molecular mechanisms of action. Results: We found that mTOR inhibitors significantly suppressed HR repair in two BRCA-proficient TNBC cell lines. mTOR inhibitors and PARP inhibitors in combination exhibited strong synergism against these TNBC cell lines. In TNBC xenografts, we observed enhanced efficacy of everolimus in combination with talazoparib (BMN673) compared with either drug alone. We further identified through microarray analysis and by rescue assays that mTOR inhibitors suppressed HR repair and synergized with PARP inhibitors through regulating the expression of SUV39H1 in BRCA-proficient TNBCs. Conclusions: Collectively, these findings strongly suggest that combining mTOR inhibitors and PARP inhibitors would be an effective therapeutic approach to treat BRCA-proficient TNBC patients.
AB - Purpose: Triple-negative breast cancer (TNBC) is a highly heterogeneous disease and has the worst outcome among all subtypes of breast cancers. Although PARP inhibitors represent a promising treatment in TNBC with BRCA1/BRCA2 mutations, there is great interest in identifying drug combinations that can extend the use of PARP inhibitors to a majority of TNBC patients with wild-type BRCA1/BRCA2. Here we explored whether mTOR inhibitors, through modulating homologous recombination (HR) repair, would provide therapeutic benefit in combination with PARP inhibitors in preclinical models of BRCA-proficient TNBC. Experimental Design: We have studied the effects of mTOR inhibitors on HR repair following DNA double-strand breaks (DSB). We further demonstrated the in vitro and in vivo activities of combined treatment of mTOR inhibitors with PARP inhibitors in BRCA-proficient TNBC. Moreover, microarray analysis and rescue experiments were used to investigate the molecular mechanisms of action. Results: We found that mTOR inhibitors significantly suppressed HR repair in two BRCA-proficient TNBC cell lines. mTOR inhibitors and PARP inhibitors in combination exhibited strong synergism against these TNBC cell lines. In TNBC xenografts, we observed enhanced efficacy of everolimus in combination with talazoparib (BMN673) compared with either drug alone. We further identified through microarray analysis and by rescue assays that mTOR inhibitors suppressed HR repair and synergized with PARP inhibitors through regulating the expression of SUV39H1 in BRCA-proficient TNBCs. Conclusions: Collectively, these findings strongly suggest that combining mTOR inhibitors and PARP inhibitors would be an effective therapeutic approach to treat BRCA-proficient TNBC patients.
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U2 - 10.1158/1078-0432.CCR-15-1772
DO - 10.1158/1078-0432.CCR-15-1772
M3 - Article
C2 - 26546619
AN - SCOPUS:84964331077
SN - 1078-0432
VL - 22
SP - 1699
EP - 1712
JO - Clinical Cancer Research
JF - Clinical Cancer Research
IS - 7
ER -