Project description:The synthetic lethal association between BRCA deficiency and poly (ADP-ribose) polymerase (PARP) inhibition supports PARP inhibitor (PARPi) clinical efficacy in BRCA-mutated tumors. PARPis also demonstrate activity in non-BRCA mutated tumors presumably through induction of PARP1-DNA trapping. Despite pronounced clinical response, therapeutic resistance to PARPis inevitably develops. An abundance of knowledge has been built around resistance mechanisms in BRCA-mutated tumors, however, parallel understanding in non-BRCA mutated settings remains insufficient. In this study, we find a strong correlation between the epithelial-mesenchymal transition (EMT) signature and resistance to a clinical PARPi, Talazoparib, in non-BRCA mutated tumor cells. Genetic profiling demonstrates that SNAI2, a master EMT transcription factor, is transcriptionally induced by Talazoparib treatment or PARP1 depletion and this induction is partially responsible for the emerging resistance. Mechanistically, we find that the PARP1 protein directly binds to SNAI2 gene promoter and suppresses its transcription. Talazoparib treatment or PARP1 depletion lifts PARP1-mediated suppression and increases chromatin accessibility around SNAI2 promoters, thus driving SNAI2 transcription and drug resistance. We also find that depletion of the chromatin remodeler CHD1L suppresses SNAI2 expression and reverts acquired resistance to Talazoparib. The PARP1/CHD1L/SNAI2 transcription axis might be therapeutically targeted to re-sensitize Talazoparib in non-BRCA mutated tumors.
Project description:The synthetic lethal association between BRCA deficiency and poly (ADP-ribose) polymerase (PARP) inhibition supports PARP inhibitor (PARPi) clinical efficacy in BRCA-mutated tumors. PARPis also demonstrate activity in non-BRCA mutated tumors presumably through induction of PARP1-DNA trapping. Despite pronounced clinical response, therapeutic resistance to PARPis inevitably develops. An abundance of knowledge has been built around resistance mechanisms in BRCA-mutated tumors, however, parallel understanding in non-BRCA mutated settings remains insufficient. In this study, we find a strong correlation between the epithelial-mesenchymal transition (EMT) signature and resistance to a clinical PARPi, Talazoparib, in non-BRCA mutated tumor cells. Genetic profiling demonstrates that SNAI2, a master EMT transcription factor, is transcriptionally induced by Talazoparib treatment or PARP1 depletion and this induction is partially responsible for the emerging resistance. Mechanistically, we find that the PARP1 protein directly binds to SNAI2 gene promoter and suppresses its transcription. Talazoparib treatment or PARP1 depletion lifts PARP1-mediated suppression and increases chromatin accessibility around SNAI2 promoters, thus driving SNAI2 transcription and drug resistance. We also find that depletion of the chromatin remodeler CHD1L suppresses SNAI2 expression and reverts acquired resistance to Talazoparib. The PARP1/CHD1L/SNAI2 transcription axis might be therapeutically targeted to re-sensitize Talazoparib in non-BRCA mutated tumors.
Project description:The synthetic lethal association between BRCA deficiency and poly (ADP-ribose) polymerase (PARP) inhibition supports PARP inhibitor (PARPi) clinical efficacy in BRCA-mutated tumors. PARPis also demonstrate activity in non-BRCA mutated tumors presumably through induction of PARP1-DNA trapping. Despite pronounced clinical response, therapeutic resistance to PARPis inevitably develops. An abundance of knowledge has been built around resistance mechanisms in BRCA-mutated tumors, however, parallel understanding in non-BRCA mutated settings remains insufficient. In this study, we find a strong correlation between the epithelial-mesenchymal transition (EMT) signature and resistance to a clinical PARPi, Talazoparib, in non-BRCA mutated tumor cells. Genetic profiling demonstrates that SNAI2, a master EMT transcription factor, is transcriptionally induced by Talazoparib treatment or PARP1 depletion and this induction is partially responsible for the emerging resistance. Mechanistically, we find that the PARP1 protein directly binds to SNAI2 gene promoter and suppresses its transcription. Talazoparib treatment or PARP1 depletion lifts PARP1-mediated suppression and increases chromatin accessibility around SNAI2 promoters, thus driving SNAI2 transcription and drug resistance. We also find that depletion of the chromatin remodeler CHD1L suppresses SNAI2 expression and reverts acquired resistance to Talazoparib. The PARP1/CHD1L/SNAI2 transcription axis might be therapeutically targeted to re-sensitize Talazoparib in non-BRCA mutated tumors.
Project description:The synthetic lethal association between BRCA deficiency and poly (ADP-ribose) polymerase (PARP) inhibition supports PARP inhibitor (PARPi) clinical efficacy in BRCA-mutated tumors. PARPis also demonstrate activity in non-BRCA mutated tumors presumably through induction of PARP1-DNA trapping. Despite pronounced clinical response, therapeutic resistance to PARPis inevitably develops. An abundance of knowledge has been built around resistance mechanisms in BRCA-mutated tumors, however, parallel understanding in non-BRCA mutated settings remains insufficient. In this study, we find a strong correlation between the epithelial-mesenchymal transition (EMT) signature and resistance to a clinical PARPi, Talazoparib, in non-BRCA mutated tumor cells. Genetic profiling demonstrates that SNAI2, a master EMT transcription factor, is transcriptionally induced by Talazoparib treatment or PARP1 depletion and this induction is partially responsible for the emerging resistance. Mechanistically, we find that the PARP1 protein directly binds to SNAI2 gene promoter and suppresses its transcription. Talazoparib treatment or PARP1 depletion lifts PARP1-mediated suppression and increases chromatin accessibility around SNAI2 promoters, thus driving SNAI2 transcription and drug resistance. We also find that depletion of the chromatin remodeler CHD1L suppresses SNAI2 expression and reverts acquired resistance to Talazoparib. The PARP1/CHD1L/SNAI2 transcription axis might be therapeutically targeted to re-sensitize Talazoparib in non-BRCA mutated tumors.
Project description:PARP1 inhibitors (PARP1is ) display single-agent anticancer activity in small cell lung cancer (SCLC) and other neuroendocrine tumors independent of BRCA1/2 mutations. Here, we determined the differential efficacy of multiple clinical PARP1is in SCLC cells. Compared to the other PARP1is (rucaparib, olaparib and niraparib), talazoparib displayed the highest potency across SCLC, also in SLFN11-negative cells. Chemical proteomics identified PARP16 as a unique talazoparib target in addition to PARP1. Silencing PARP16 significantly reduced cell survival, particularly in combination with PARP1 inhibition. Drug combination screening revealed talazoparib synergy with the WEE1/PLK1 inhibitor, adavosertib. Global phosphoproteomics identified disparate effects on cell cycle and DNA damage response signaling, illustrating underlying mechanisms. Synergy with adavosertib was more pronounced for talazoparib than olaparib and silencing PARP16 further reduced cell survival in combination with olaparib and adavosertib. Together, these data suggest that PARP16 contributes to talazoparib’s overall mechanism of action and constitutes a new actionable target in SCLC.
Project description:PARP1 inhibitors (PARP1is) display single-agent anticancer activity in small cell lung cancer (SCLC) and other neuroendocrine tumors independent of BRCA1/2 mutations. Here, we determined the differential efficacy of multiple clinical PARP1is in SCLC cells. Compared to the other PARP1is (rucaparib, olaparib and niraparib), talazoparib displayed the highest potency across SCLC, also in SLFN11-negative cells. Chemical proteomics identified PARP16 as a unique talazoparib target in addition to PARP1. Silencing PARP16 significantly reduced cell survival, particularly in combination with PARP1 inhibition. Drug combination screening revealed talazoparib synergy with the WEE1/PLK1 inhibitor, adavosertib. Global phosphoproteomics identified disparate effects on cell cycle and DNA damage response signaling, illustrating underlying mechanisms. Synergy with adavosertib was more pronounced for talazoparib than olaparib and silencing PARP16 further reduced cell survival in combination with olaparib and adavosertib. Together, these data suggest that PARP16 contributes to talazoparib’s overall mechanism of action and constitutes a new actionable target in SCLC.
Project description:PARP1 inhibitors (PARP1is ) display single-agent anticancer activity in small cell lung cancer (SCLC) and other neuroendocrine tumors independent of BRCA1/2 mutations. Here, we determined the differential efficacy of multiple clinical PARP1is in SCLC cells. Compared to the other PARP1is (rucaparib, olaparib and niraparib), talazoparib displayed the highest potency across SCLC, also in SLFN11-negative cells. Chemical proteomics identified PARP16 as a unique talazoparib target in addition to PARP1. Silencing PARP16 significantly reduced cell survival, particularly in combination with PARP1 inhibition. Drug combination screening revealed talazoparib synergy with the WEE1/PLK1 inhibitor, adavosertib. Global phosphoproteomics identified disparate effects on cell cycle and DNA damage response signaling, illustrating underlying mechanisms. Synergy with adavosertib was more pronounced for talazoparib than olaparib and silencing PARP16 further reduced cell survival in combination with olaparib and adavosertib. Together, these data suggest that PARP16 contributes to talazoparib’s overall mechanism of action and constitutes a new actionable target in SCLC.
Project description:PARP1 inhibitors (PARP1is) display single-agent anticancer activity in small cell lung cancer (SCLC) and other neuroendocrine tumors independent of BRCA1/2 mutations. Here, we determined the differential efficacy of multiple clinical PARP1is in SCLC cells. Compared to the other PARP1is (rucaparib, olaparib and niraparib), talazoparib displayed the highest potency across SCLC, also in SLFN11-negative cells. Chemical proteomics identified PARP16 as a unique talazoparib target in addition to PARP1. Silencing PARP16 significantly reduced cell survival, particularly in combination with PARP1 inhibition. Drug combination screening revealed talazoparib synergy with the WEE1/PLK1 inhibitor, adavosertib. Global phosphoproteomics identified disparate effects on cell cycle and DNA damage response signaling, illustrating underlying mechanisms. Synergy with adavosertib was more pronounced for talazoparib than olaparib and silencing PARP16 further reduced cell survival in combination with olaparib and adavosertib. Together, these data suggest that PARP16 contributes to talazoparib’s overall mechanism of action and constitutes a new actionable target in SCLC.
Project description:Trabectedin is a DNA-damaging agent with a peculiar mechanism of action; it traps the DNA repair machinery leading to DNA single- and double-strand breaks, particularly in BRCA1/2-deficient tumors. We hypothesized that trabectedin-induced DNA damage might activate PARP1 (a DNA-repair machinery key player), and consequently, PARP1 inhibition would perpetuate trabectedin-induced DNA damage. In several tumor histotypes, we demonstrated a different degree of synergism between trabectedin and PARP1 inhibitors (PARP1-Is). Independent of BRCA1/2 status, PARP1 expression dictated the degree of synergism. Namely, silenced PARP1 reduced trabectedin-PARP1-Is synergism, whereas overexpressed PARP1 increased combination efficacy. High-PARP1 expression and specific gene signatures associated with DNA damage response and repair (DDR-R) were predictive of trabectedin+PARP1-I synergy. These findings pave the way for the clinical development of this novel combination therapy, as well as evaluation of PARP1 expression and DDR-R signatures in tumor samples as predictive biomarkers of response