Project description:Breast cancer gene 2 (BRCA2) deleterious mutations confer sensitivity to poly(ADP-ribose) polymerase (PARP) inhibition due to its critical role in DNA repair. PARP inhibitor Olaparib is now approved and several other PARP inhibitors are now in different stages of clinical trials. Development of resistance to PARP inhibitors limits their clinical utility. The mechanism of resistance remains not fully understood. Here we show that amplification of mutant BRCA2 confers PARP inhibitor resistance. The amplification of mutant BRCA2 gene copies correlates with an increase in mutant BRCA2 expression and an increase in the levels of its interacting proteins PALB2 and RAD51. In addition, homologous recombination mediated DNA repair is rescued in these cells as evidenced by the formation of RAD51 focus formation. The overexpressed mutant BRCA2 is essential for the observed PARP inhibitor resistance because knockdown of its expression is sufficient to re-sensitize these cells to PARP inhibition. Collectively, our results indicate a new mechanism of resistance to PARP inhibitor in BRCA2 mutant cancer cells
Project description:Most cases of adult myeloid neoplasms are routinely assumed to be sporadic. Here, we describe an adult familial acute myeloid leukemia (AML) syndrome caused by germline mutations in the DEAD/H-Box helicase gene DDX41. DDX41 was also found to be affected by somatic mutations in sporadic cases of myeloid neoplasms as well as in a biallelic fashion in 50% of patients with germline DDX41 mutations. Moreover, corresponding deletions on 5q35.3 present in 6% of cases lead to haploinsufficient DDX41 expression. DDX41 lesions caused altered pre-mRNA splicing and RNA processing. DDX41 is exemplary of other RNA helicase genes also affected by somatic mutations, suggesting that they constitute a family of tumor suppressor genes. Affymetrix SNP arrays were performed according to the manufacturer's directions on DNA extracted from cryopreserved diagnostic bone marrow or peripheral blood samples.
Project description:Here we characterized a series of cases with myeloid neoplasms using cytogenetic, single nucleotide polymorphism array, and next generation sequencing.
Project description:Most cases of adult myeloid neoplasms are routinely assumed to be sporadic. Here, we describe an adult familial acute myeloid leukemia (AML) syndrome caused by germline mutations in the DEAD/H-Box helicase gene DDX41. DDX41 was also found to be affected by somatic mutations in sporadic cases of myeloid neoplasms as well as in a biallelic fashion in 50% of patients with germline DDX41 mutations. Moreover, corresponding deletions on 5q35.3 present in 6% of cases lead to haploinsufficient DDX41 expression. DDX41 lesions caused altered pre-mRNA splicing and RNA processing. DDX41 is exemplary of other RNA helicase genes also affected by somatic mutations, suggesting that they constitute a family of tumor suppressor genes.
Project description:Here we characterized a series of 14 cases with myeloid neoplasms using cytogenetic, single nucleotide polymorphism array, and next generation sequencing.
Project description:PARP inhibitors have demonstrated remarkable clinical efficacy in treating ovarian cancer (OV) patients with BRCA1/2 mutations. However, drug resistance inevitably limits their clinical applications and there is an urgent need for improved therapeutic strategies to enhance the clinical utility of PARP inhibitors, such as Olaparib. Here, we present compelling evidence that PARP inhibitor sensitivity is associated with cell cycle dysfunction, independent of homologous recombination deficiency (HRD) /BRCA status. Through high-throughput drug screening with a cell cycle kinase inhibitor library, we identified XL413, a potent CDC7 inhibitor, which can synergistically enhance the anti-cancer efficacy of Olaparib. Mechanistically, we demonstrate that the combined administration of XL413 and Olaparib induced considerable DNA damage and DNA replication stress, leading to increased sensitivity to Olaparib. Additionally, a robust type-I interferon response was triggered through the induction of the cGAS/STING signaling pathway. Using a murine syngeneic tumor model, we further demonstrate that the combination treatment enhanced antitumor immunity, resulting in tumor regression. Collectively, this study presents a novel treatment strategy for patients with advanced OV by combining CDC7 and PARP inhibitiors, offering a promising therapeutic approach forpatients whith limited response to PARP inhibitors.
Project description:Poly(ADP-ribose) polymerase 1 (PARP-1) is abnormally expressed in a wide variety of tumors. Emerging evidence suggests that PARP-1 plays key roles in multiple biologic behaviors of tumors, such as modulation of chromatin structure, regulation of gene transcription, tumor proliferation, apoptosis, and angiogenesis, by acting on different molecular pathways. PARP-1 inhibition can achieve a beneficial outcome in tumor treatment. But the specific mechanism of PARP-1 in acute myeloid leukemia (AML) is still to be discovered. We used microarrays to detail the global gene expression in C1498 with and without PARP-1 inhibition and profile differentially expressed genes that might be involved in PARP-1 regulation in AML.
Project description:<p>Patients with myeloid malignancies bearing high-risk cytogenetic abnormalities lack effective therapies and have a poor overall survival. -7/del(7q) is identified in half of high-risk myeloid neoplasms. We recently identified <i>CUX1</i> to be a haploinsufficient myeloid tumor suppressor gene located within the commonly deleted segment of 7q22. Here we identify the spectrum of somatic mutations that co-occur with loss of <i>CUX1</i> and chromosome 7 in patients with <i>de novo</i> acute myeloid leukemia (AML) or a therapy-related myeloid neoplasm. -7/del(7q) leukemias have a distinct mutational profile characterized by low frequencies of alterations in major leukemogenic pathways, including genes encoding transcription factors, cohesin, and DNA-methylation-related proteins. In contrast, RAS pathway activating mutations occurred in 40% of -7/del(7q) samples, a significantly higher frequency than other AMLs and higher than previously reported. As targeted therapeutics advance, our data provide guidance for which pathways are most relevant in the treatment of adverse-risk myeloid leukemia. </p>