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Lysosomal sequestration of PARP inhibitors drives heterogeneous accumulation in ovarian cancer to increase efficacy [Spatial Transcriptomics]

ABSTRACT: PARP inhibitors have had a transformative impact in the treatment of high-grade serous ovarian cancer (HGSOC), but resistance remains a clinical hurdle. Increased expression of ABC drug efflux transporters has been identified as a resistance mechanism in patients but whether intracellular concentrations of these drugs is heterogeneous within tumours remains unclear. We developed a patient-derived explant multi-modal imaging pipeline which demonstrated significant cell-intrinsic heterogeneity of PARP inhibitor accumulation, both between patients and within tumours. Spatial transcriptomics revealed enrichment of apoptotic signatures in high-drug compared to low-drug regions, as well as metabolic and ECM-related differences. While some cases demonstrated a clear anticorrelation of PARP inhibitor levels with MDR1(ABCB1), this was not universal. Rucaparib, an intrinsically fluorescent PARP inhibitor accumulates heterogeneously at the single cell-level in established cell lines, and omics approaches revealed that this is driven by lysosomal sequestration, a pattern also observed in patient samples. Perturbation of lysosomal content altered intracellular levels of rucaparib and niraparib and impacted efficacy suggesting that lysosomes act as a drug reservoir to improve drug response.

ORGANISM(S): Homo sapiens

PROVIDER: GSE281519 | GEO | 2026/01/05

REPOSITORIES: GEO

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Lysosomal sequestration of PARP inhibitors drives heterogeneous accumulation in ovarian cancer to increase efficacy [RNA-seq]

Project description:PARP inhibitors have had a transformative impact in the treatment of high-grade serous ovarian cancer (HGSOC), but resistance remains a clinical hurdle. Increased expression of ABC drug efflux transporters has been identified as a resistance mechanism in patients but whether intracellular concentrations of these drugs is heterogeneous within tumours remains unclear. We developed a patient-derived explant multi-modal imaging pipeline which demonstrated significant cell-intrinsic heterogeneity of PARP inhibitor accumulation, both between patients and within tumours. Spatial transcriptomics revealed enrichment of apoptotic signatures in high-drug compared to low-drug regions, as well as metabolic and ECM-related differences. While some cases demonstrated a clear anticorrelation of PARP inhibitor levels with MDR1(ABCB1), this was not universal. Rucaparib, an intrinsically fluorescent PARP inhibitor accumulates heterogeneously at the single cell-level in established cell lines, and omics approaches revealed that this is driven by lysosomal sequestration, a pattern also observed in patient samples. Perturbation of lysosomal content altered intracellular levels of rucaparib and niraparib and impacted efficacy suggesting that lysosomes act as a drug reservoir to improve drug response.

2026-01-05 | GSE281517 | GEO

Lysosomal sequestration of PARP inhibitors drives heterogeneous accumulation in ovarian cancer to increase efficacy

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Project description:PROTACs (Proteolysis-Targeting Chimeras) represent a revolutionary new class of drugs that selectively degrade proteins of interest from cells. PROTACs targeting oncogenes are avidly being explored for cancer therapies, with several currently in clinical trials. Drug resistance represents a significant challenge in cancer therapies, and the mechanism by which cancer cells acquire resistance to protein degraders remains poorly understood. Here, we applied proteomics approaches to elucidate resistance mechanisms to protein degrader therapies in cancer cells. Our studies revealed acquired resistance to degrader therapies in cancer cells can be mediated by upregulation of the ATP-dependent drug efflux pump MDR1. Degrader-resistant cells could be re-sensitized to PROTACs through co-administering MDR1 inhibitors. Notably, MDR1 is frequently overexpressed in cancer, and cancer cell lines overexpressing MDR1 exhibited intrinsic resistance to protein degraders, requiring co-treatment with MDR1 inhibitors to achieve protein degradation and therapeutic response. Notably, co-treatment of MDR1-overexpressing K-ras mutant colorectal cancer cells with MEK1/2 or K-ras degraders and the dual ErbB receptor/MDR1 inhibitor lapatinib exhibited potent drug synergy due to simultaneous blockade of MDR1 activity and ErbB receptor-driven resistance. Together, our findings showed overexpression of MDR1 can promote both intrinsic and acquired resistance to protein degraders in cancer cells and that concurrent blockade of MDR1 will likely be required to achieve durable protein degradation and therapeutic response.

2022-10-06 | PXD029233 | Pride

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Combinatorial treatment with PARP and MAPK inhibitors overcomes phenotype switch-driven drug resistance in advanced melanoma

Project description:Metastatic melanoma is either intrinsically resistant or rapidly acquires resistance to targeted therapy treatments, such as MAPK inhibitors. A leading cause of resistance to targeted therapy is a dynamic transition of melanoma cells from a proliferative to a highly invasive state, a phenomenon called phenotype switching. Mechanisms regulating phenotype switching represent potential targets for improving treatment of melanoma patients. Using a drug screen targeting chromatin regulators in patient-derived 3D MAPK inhibitor-resistant melanoma cell cultures, we discovered that PARP inhibitors restore sensitivity to MAPK inhibitors, independent of DNA damage repair pathways. Integrated transcriptomic, proteomic, and epigenomic analyses demonstrated that PARP inhibitors induce lysosomal autophagic cell death, accompanied by enhanced mitochondrial lipid metabolism that ultimately increases antigen presentation and sensitivity to T-cell cytotoxicity. Moreover, transcriptomic and epigenetic rearrangements induced by PARP inhibition reversed EMT-like phenotype switching, which redirected melanoma cells toward a proliferative and MAPK inhibitor-sensitive state. The combination of PARP and MAPK inhibitors synergistically induced cancer cell death both in vitro and in vivo in patient-derived xenograft models. Therefore, this study provides a scientific rationale for treating melanoma patients with PARP inhibitors in combination with MAPK inhibitors to abrogate acquired therapy resistance.

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IGR_Michels_PARP

Project description:Non-small cell lung cancer (NSCLC) is often treated with cisplatin (CDDP). Here, we report that two distinct poly(ADP-ribose) polymerase (PARP) inhibitors exhibited a hyperadditive combination effect with CDDP to kill NSCLC cells. A majority of CDDP-resistant cell lines and clones exhibited constitutively increased PARP expression and enzymatic activity. Cells with hyperactivated PARP initiated a DNA damage response and the intrinsic pathway of apoptosis in response to pharmacological PARP inhibition or PARP1-targeting siRNAs. Transcriptome analysis depicted an unsupervised hierarchical clustering of NSCLC cells and CDDP resistant counterparts regarding to their response to PARP inhibitors. PARP-overexpressing tumors displayed elevated levels of intracellular poly(ADP-ribose) (PAR), which predicted the response to PARP inhibitors in vitro and in vivo more accurately than PARP expression itself. Thus, CDDP-resistant cancer cells develop a dependency to PARP, becoming susceptible to PARP inhibitor-induced apoptosis.

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