Project description:Werner helicase inhibitors (WRNi) show promise for treating patients with microsatellite-unstable (MSI) tumors characterized by defective DNA mismatch repair. Multiple WRNi recently entered Phase 1 clinical trials. Here, we investigate the impact of cancer cell evolutionary adaptation on WRN pharmacological inhibition with implications for understanding drug selectivity and potential clinical resistance. Coupling genome-wide CRISPR screens with WRN gene knockout, no suppressors of WRN dependency were identified, underscoring WRN’s essential non-redundant function in MSI cells. Pharmacogenomic screens pinpointed modulators of WRNi sensitivity, including SMARCAL1, linking WRN-MSI synthetic lethality with chromatin remodelling and DNA repair pathways. Semi-saturation mutagenesis of WRN and prolonged drug treatment identified on-target WRN mutations driving spontaneous secondary resistance to multiple WRNi in vitro and in vivo. Specific resistance mutations preserve sensitivity to alternative WRNi, whereas others induce cross-resistance. Our work guides next-generation strategies for targeting MSI cancers, enabling cross-resistance studies to evaluate current and novel WRNi efficacy and informing future clinical trial design.
Project description:Cancers with microsatellite instability (MSI) depend on the WRN helicase enzyme to manage issues during DNA replication caused by long stretches of (TA) repeats in the DNA. Targeting WRN is a promising strategy for treating MSI cancers, and drugs that inhibit WRN are being developed. Through a process called fragment-based screening, we developed powerful and specific drugs that block WRN's action. These drugs effectively slowed down the growth of MSI cancer models in lab and animal studies by acting like WRN is absent, leading to DNA breaks at the long TA repeats and causing DNA damage. The development of these potent and specific drugs targeting WRN in MSI cancers proves that this approach can work and also helps us understand more about WRN's role in biology.
Project description:The mammalian target of rapamycin (mTOR) is a central regulator of cell proliferation. Inhibitors of mTOR are being evaluated as anti-tumor agents. Given the emerging role of microRNAs (miRNAs) in tumorgenesis we hypothesized that miRNAs could play important roles in the response of tumors to mTOR inhibitors. Rapamycin resistant myogenic cells developed by long-term rapamycin treatment showed extensive reprogramming of miRNAs expression, characterized by up-regulation of the mir-17~92 and related clusters and down-regulation of tumor-suppressor miRNAs. Antagonists of oncogenic miRNA families and mimics of tumor suppressor miRNAs (let-7) restored rapamycin sensitivity in resistant tumor cells. This study identified miRNAs as new downstream components of the mTOR-signaling pathway, which may determine the response of tumors to mTOR inhibitors. Total RNA extraction and hybridization on Affymetrix microarrays of rapamycin sensitive (RS) cells (BC3H1, mouse brain tumor cell line with myogenic properties, ATCC) cultured in Dulbecco’s modified essential medium (DMEM) media supplemented with 20% fetal bovine serum (FBS), penicillin (100 U/ml) and streptomycin (100 mg/ml). Rapamycin resistant cells (RR1) were developed by culturing BC3H1 cells in the presence of 1 uM rapamycin for 6 months. Three samples in triplicates: 1) Rapamycin sensitive cells treated with DMSO for 24 h(BC3H1, reference), 2) Rapamycin sensitive cells treated for 24 h with 100 nM rapamycin (BC3H1+R), 3) Rapamycin resistant cells constantly treated with 1uM Rapamycion (RR1+R).
Project description:Precise DNA replication is critical to the maintenance of genome stability, and the DNA replication machinery is a focal point of many current and upcoming chemotherapeutics. TrAEL-seq is a robust method for profiling DNA replication genome-wide that works in unsynchronised cells and does not require treatment with drugs or nucleotide analogues. Here, we provide an updated method for TrAEL-seq including multiplexing of up to 6 samples that dramatically improves sample quality and throughput, and we validate TrAEL-seq in multiple mammalian cell lines. The updated protocol is straightforward and robust yet provides excellent resolution comparable to OK-seq in mammalian cell samples, and does not require cell synchronisation, drug treatment, labelling or sorting. High resolution replication profiles can be obtained across large panels of samples and in dynamic systems, for example during the progressive onset of oncogene induced senescence. In addition to mapping zones where replication initiates and terminates, TrAEL-seq is sensitive to replication fork speed, revealing effects of both transcription and proximity to replication initiation zones on fork progression. Although forks move more slowly through transcribed regions, this does not have a significant impact on the broader dynamics of replication fork progression, which is dominated by rapid fork movement in long replication regions (>1Mb). Short and long replication regions are not intrinsically different, and instead replication forks accelerate across the first ~1 Mb of travel such that forks progress faster in the middle of regions lying between widely spaced initiation zones. We propose that this is a natural consequence of fewer replication forks being active later in S phase when these distal regions are replicated and there being less competition for replication factors.
Project description:Werner syndrome (WS) is a rare disorder characterized by the premature onset of a number of age-related diseases. The gene responsible for WS is believed to be involved in different aspects of transcription, replication, and/or DNA repair. We generated a mouse model with a deletion in the helicase domain of the murine WRN homologue that recapitulates most of the WS phenotypes including an abnormal hyaluronic acid excretion, higher reactive oxygen species (ROS) levels, increased genomic instability and cancer incidence resulting in a 10-15% decreased life span expectancy. In addition, WS patients and Wrn mutant mice show hallmarks of a metabolic syndrome including premature visceral obesity, hypertriglyceridemia, insulin-resistant diabetes type 2 and associated cardiovascular diseases. In this study, we compared the expression profile of liver tissues from 3 months old Wrn mutant mice treated with 0.4% vitamin C to untreated 3 months old Wrn mutant mice. Microarray analyses were performed on the liver tissues of 3 months old mice. Four independent biological replicates of this experiment (untreated Wrn mutant mice vs vitamin C treated Wrn mutant mice) were carried out on four replicates of each genotype.
Project description:Starting with H3122 cells, which harbor the EML4-ALK E13;A20 fusion and are known to be sensitive to ALK tyrosine kinase inhibitors, we generated isogenic pairs of ALK TKI sensitive and ALK TKI resistant cell lines using established methods (see Chmeliecki, J et al Science Trans Med 2011). We modeled resistance against the currently FDA approved ALK TKI, crizotinib (also called PF-1066). We also modeled resistance against a novel more potent ALK inhibitor, X-376 (ref: Lovly, CM et al Cancer Research 2011). We compared gene expression profiles between the 'parental' (ALK TKI sensitive) H3122 cells and the drug resistant cells (H3122 CR for Crizotinib resistant cells and H3122 XR for X-376 resistant cells).
Project description:Werner syndrome (WS) is a rare disorder characterized by the premature onset of a number of age-related diseases. The gene responsible for WS is believed to be involved in different aspects of transcription, replication, and/or DNA repair. We generated a mouse model with a deletion in the helicase domain of the murine WRN homologue that recapitulates most of the WS phenotypes including an abnormal hyaluronic acid excretion, higher reactive oxygen species (ROS) levels, increased genomic instability and cancer incidence resulting in a 10-15% decreased life span expectancy. In addition, WS patients and Wrn mutant mice show hallmarks of a metabolic syndrome including premature visceral obesity, hypertriglyceridemia, insulin-resistant diabetes type 2 and associated cardiovascular diseases. In this study, we compared the expression profile of liver tissues from 3 months old Wrn mutant mice treated with 0.4% vitamin C to untreated 3 months old Wrn mutant mice.
Project description:10 cell lines (five cetuximab sensitive and five cetuximab resistant) were selected for gene copy number array analysis on the Affymetrix SNP 6.0 platform. 39 protein coding genes were amplified in cetuximab resistant cells and normal in sensitive cells, all present on genomic regions 11q22.1 or 5p13-15. Five genes were selected for quantitative PCR verification, namely, YAP1 and TRPC6 (11q22.1) and PDCD6, TPPP, and PTGER4 (5p13-15). An extended panel of totally 10 cetuximab resistant and 10 sensitive cell lines verified that YAP1 amplified cells are cetuximab resistant. YAP1 gene amplification was highly correlated to the YAP1 mRNA expression, which was significantly higher in cetuximab resistant cells than in sensitive. YAP1 downregulation resulted in increased cetuximab sensitivity in one of two cetuximab resistant cell lines investigated and growth inhibition in another. We conclude that YAP1 is a marker for cetuximab resistance in head and neck cancer.