Project description:The aim of the study is to identify differences in the global phosphoproteome across a BRCA1-deficient mouse mammary tumor panel. We have matched PARPi-naive and PARPi-resistant tumors, in which resistance was induced in vivo (mice bearing tumors were treated with PARPi untill the tumors stopped responding). Each pair of matched naive/resistant tumors originate from a different original tumor donor (one can consider each individual donor as an individual patient). From another analysis (RAD51 IRIF) we know that the mechanism of PARPi-resistance in a number of the tumors is driven by alterations in DNA damage response. Therefore, we can divide the tumors into four groups: (A) HR proficient, the exact mechanism not known, (B) HR proficient due to the loss of 53bp1 (TP53BP1), (C) HR proficient due to loss of Rev7 (MAD2L2) and (D) HR deficient, mechanism of resistance not known. Additionally, each tumor from our panel was retransplanted and challenged with 15 Gy irradiation to trigger a DNA damage response, therefore for each tumor we have an irradiated (IR) and a non-irradiated (NIR) sample. In this experiment each sample was processed in duplicate. Given all this, group (A) consists of 6 individual donors x 2 (matched naive/resistant) x 2 (NIR/IR) x 2 (duplicate) = 48 samples (samples 1-48); groups (B)-(D): 2 donors (per group) x 2 (naive/resistant) x 2 (NIR/IR) x 2 (duplicate) = 16 samples/group (B: samples 65-80, C: samples 81-96 and D: 49-64, according to the OPL label). In total this gives: 48 + 16 +16 +16 = 96 samples. Part of this analysis is used in the paper that also describes data from PXD031711
Project description:Most BRCA1-deficient BLBCs carry a dysfunctional INK4-RB pathway. Thus, we have created genetically engineered mice with Brca1 loss and deletion of p16INK4A, or separately p18INK4C, to model the deficient INK4-RB signaling in human BLBC. By using these mutant mice and human BRCA1 deficient and proficient breast cancer tissues and cells, we tested if there exists a druggable target in BRCA1 deficient breast cancers.
Project description:Brca1 mutation predisposes women to early onset of breast and ovarian cancers.Through its diverse functions in DNA damage repair, cell cycle control, transcription regulation, ubiquitination and so on, BRCA1 acts as a very significant tumor suppressor and genomic safeguard. Brca1 deficiency induces severe cellular stress, when occurring in the mammary glands, it impairs the regular developmental process and eventually causes tumorigenesis due to accumulation of genome instability and other mechanisms. The Brca1-defiencient mouse mammary tumor were characterized with great tumoral heterogeneity, which is in line with the human breast cancers carrying BRCA1 mutations. Here we studied the molecular complexicity of Brca1-deficient mouse mammary tumors vie RNA sequencing.
Project description:The defect in homologous recombination (HR) found in BRCA1-associated cancers can be therapeutically exploited by treatment with DNA-damaging agents and PARP inhibitors. We and others previously reported that BRCA1-deficient tumors are initially hypersensitive to the inhibition of topoisomerase I/II and PARP, but acquire drug resistance through restoration of HR activity by the loss of end-resection antagonists of the 53BP1/RIF1/REV7/Shieldin/CST pathway. Here, we identify radiotherapy as an acquired vulnerability of 53BP1;BRCA1-deficient cells in vitro and in vivo. In contrast to the radioresistance caused by HR restoration through BRCA1 reconstitution, HR restoration by 53BP1 pathway inactivation further increases radiosensitivity. This highlights the relevance of this pathway for the repair of radiotherapy-induced damage. Moreover, our data show that BRCA1-mutated tumors that acquire drug resistance due to BRCA1-independent HR restoration can be targeted by radiotherapy. SIGNIFICANCE: These findings uncover radiosensitivity as a novel, therapeutically viable vulnerability of BRCA1-deficient mouse mammary cells that have acquired drug resistance due to the loss of the 53BP1 pathway.
Project description:PARP inhibitors (PARPi) have drastically changed the treatment landscape of advanced ovarian tumors with BRCA mutations. However, the impact of this class of inhibitors in patients with advanced BRCA-mutant breast cancer is relatively modest. Using a syngeneic genetically-engineered mouse model of breast tumor driven by Brca1 deficiency, we show that tumor-associated macrophages (TAMs) blunt PARPi efficacy both in vivo and in vitro. Mechanistically, BRCA1-deficient breast tumor cells induce pro-tumor polarization of TAMs, which in turn suppress PARPi-elicited DNA damage in tumor cells, leading to reduced production of dsDNA fragments and synthetic lethality, hence impairing STING-dependent anti-tumor immunity. STING agonists reprogram M2-like pro-tumor macrophages into an M1-like anti-tumor state in a macrophage STING-dependent manner. Systemic administration of a STING agonist breaches multiple layers of tumor cell-mediated suppression of immune cells, and synergizes with PARPi to suppress tumor growth. The therapeutic benefits of this combination require host STING and are mediated by a type I IFN response and CD8+ T cells, but do not rely on tumor cell-intrinsic STING. Our data illustrate the importance of targeting innate immune suppression to facilitate PARPi-mediated engagement of anti-tumor immunity in breast cancer.
Project description:Brca1 mutation predisposes women to early onset of breast and ovarian cancers.Through its diverse functions in DNA damage repair, cell cycle control, transcription regulation, ubiquitination and so on, BRCA1 acts as a very significant tumor suppressor and genomic safeguard. Brca1 deficiency induces severe cellular stress, when occurring in the mammary glands, it impairs the regular developmental process and eventually causes tumorigenesis due to accumulation of genome instability and other mechanisms. The Brca1-defiencient mouse mammary tumor were characterized with great tumoral heterogeneity, which is in line with the human breast cancers carrying BRCA1 mutations. Here we studied the molecular complexicity of Brca1-deficient mouse mammary tumors vie Dropseq.
Project description:We have previously established an in vitro model of PARPi-resistant ovarian cancer by long-term exposure of UWB1.289 ovarian cancer cells (and their isogenic derivatives UWB1.289+BRCA1) to incrementally ascending olaparib concentrations. After finalizing this model, we performed RNA-seq, in order to identify differentially expressed transcript in the PARPi-resistant cells, with a focus on genes related to DNA-repair, multi-drug resistance and EMT. As a result, we show that the phenotype of PARPi resistance is associated with EMT-like traits and up-regulation of selective multi-drug related transcripts.