Project description:CDK4/6 inhibition is the standard of care for estrogen receptor positive (ER+) breast cancer, although cytostasis is frequently observed, and new treatment strategies that enhance efficacy are required. We performed a genome-wide CRISPR screen to identify genetic determinants of CDK4/6 inhibitors sensitivity. Multiple genes involved in oxidative stress and ferroptosis modulated palbociclib sensitivity. Depletion or inhibition of GPX4 increased sensitivity to palbociclib in ER+ breast cancer models, and sensitised triple negative breast cancer models to palbociclib, with GPX4 null xenografts being highly sensitive to palbociclib. Palbociclib induced oxidative stress and disordered lipid metabolism with lipid peroxidation, leading to a ferroptosis-sensitive state. Lipid peroxidation relied on a peroxisome AGPAT3-dependent pathway in ER+ breast cancer models, rather than the classical ACSL4 pathway. Our data demonstrate that CDK4/6 inhibition creates vulnerability to ferroptosis that could be exploited through combination with GPX4 inhibitors, enhancing sensitivity to CDK4/6 inhibition in breast cancer.
Project description:Acute Pten loss initiates prostate tumorigenesis characterized by cellular senescence response. Here we examine the cellular senescence response in epithelial individual cells, by single-cell RNA sequencing (scRNAseq) in Ptenpc-/- and Ptenpc-/-; Timp1-/- GEMMs. ScRNAseq analysis determines a cluster of senescent cells expressing the senescence-related genes. A significant positive correlation is observed between the senescence score and Bcl2 expression. This provides the rational for targeting senescent cells using Bcl2 inhibitor.
Project description:Nrf1 is a transcription factor that is highly conserved and reacts to oxidative, proteotoxic and endoplasmic reticulum stress in cells; nonetheless, its function in the context of acute kidney injury (AKI) remains unclear. Using a model of cisplatin-induced nephrotoxicity in vitro and in vivo, we found that the expression of Nrf1, which is expressed at high levels in renal tubular cells, was significantly downregulated after cisplatin treatment. Proximal tubule-specific Nrf1 knockout worsened and Nrf1 overexpression attenuated cisplatin-induced (CI)-AKI. RNA sequencing analysis revealed that Nrf1 overexpression decreased the number of transcripts involved in cell death, specifically those associated with ferroptosis, after cisplatin treatment. Furthermore, ferroptosis responses, characterized by increased lipid peroxidation and iron content and decreased FPN, XCT and glutathione peroxidase 4 levels, were attenuated in Nrf1-overexpressing HK-2 cells but worsened in Nrf1-knockout mice and Nrf1-knockdown HK-2 cells. Moreover, lipidomic and RNA sequencing results indicated that Nrf1 regulated the levels of polyunsaturated fatty acids (PUFAs) and inhibited the expression of ACSL4. Additionally, ChIP experiments revealed that Nrf1 bound to the promoter region of ACSL4, thereby inhibiting its transcription. Furthermore, inhibitors of ACSL4 significantly reduced the sensitivity of HK-2 cells to ferroptosis induced by Nrf1 knockdown. Collectively, these findings suggest that Nrf1 is a novel target for inhibiting ferroptosis in renal tubule cells by suppressing the transcription and expression of ACSL4, thereby reducing PUFA levels. Consequently, activators developed for Nrf1 may hold therapeutic potential in the treatment of patients with CI-AKI.
Project description:Introgressed variants from other species can be an important source of genetic variation because they may arise rapidly, can include multiple mutations on a single haplotype, and have often been pretested by selection in the species of origin. Although introgressed alleles are generally deleterious, several studies have reported introgression as the source of adaptive alleles-including the rodenticide-resistant variant of Vkorc1 that introgressed from Mus spretus into European populations of Mus musculus domesticus. Here, we conducted bidirectional genome scans to characterize introgressed regions into one wild population of M. spretus from Spain and three wild populations of M. m. domesticus from France, Germany, and Iran. Despite the fact that these species show considerable intrinsic postzygotic reproductive isolation, introgression was observed in all individuals, including in the M. musculus reference genome (GRCm38). Mus spretus individuals had a greater proportion of introgression compared with M. m. domesticus, and within M. m. domesticus, the proportion of introgression decreased with geographic distance from the area of sympatry. Introgression was observed on all autosomes for both species, but not on the X-chromosome in M. m. domesticus, consistent with known X-linked hybrid sterility and inviability genes that have been mapped to the M. spretus X-chromosome. Tract lengths were generally short with a few outliers of up to 2.7 Mb. Interestingly, the longest introgressed tracts were in olfactory receptor regions, and introgressed tracts were significantly enriched for olfactory receptor genes in both species, suggesting that introgression may be a source of functional novelty even between species with high barriers to gene flow.
Project description:Understanding mechanisms that determine the response of cells to ferroptotic stress is a timely issue that has significant ramifications for biology and pathology. We investigated these mechanisms in the context of breast cancer where tumors are comprised of diverse populations of cancer cells that differ in their ferroptosis sensitivity. Using single-cell RNA-sequencing, we determined that cancer cell populations with luminal differentiation are more resistant to ferroptosis than other cells within a heterogeneous tumor. Subsequent bioinformatic analysis and experimentation revealed that GATA3, a transcription factor that promotes luminal differentiation, has a causal role in ferroptosis resistance in luminal breast cancer cells. In pursuit of the mechanism involved, we found that GATA3 represses the expression of integrin β1 and its downstream signaling cascade. This observation led us to demonstrate that integrin β1 signaling is necessary for sensitivity to ferroptosis in basal breast cancer cells because it regulates a FAK/ROCK pathway that sustains the expression of ACSL4, a lipid-modifying enzyme that is essential for ferroptosis. The repression of integrin β1 by GATA3 inhibits this signaling pathway rendering cells ferroptosis resistant. Together, these data provide insight into mechanisms of ferroptosis sensitivity and resistance that are linked to the cell biology and signaling pathways of the diverse types of cells present in breast tumors.
Project description:Identification of IDH mutations has uncovered the crucial role played by metabolism in glioma-genesis. Oncolytic herpes virus (oHSV) therapy initiates direct tumor debulking by tumor lysis and also activates antitumor immunity however little is known about the role of glioma metabolism in determining oHSV efficacy. Here we identified that oHSV therapy rewired central carbon metabolism with increased glucose utilization towards oxidative phosphorylation and shuttled glutamine towards reductive carboxylation in IDH wildtype (wt) glioma. The switch in metabolism resulted in increased lipid synthesis, and cellular ROS. PKC induced ACSL4 in oHSV treated cells led to lipid peroxidation and ferroptosis. Ferroptosis was critical to launch an antitumor immune response important for efficacy. Mutant IDH (IDHR132H) gliomas are incapable of reductive carboxylation and hence ferroptosis. Pharmacological blockade of IDHR132H induced ferroptosis and antitumor immunity. This study provides a rationale to treat high grade IDHR132H glioma patients under oHSV treatment with IDHR132H inhibitor.
Project description:Ferroptosis is a form of regulated necrotic cell death controlled by glutathione peroxidase 4 (GPX4). At present, mechanisms that could predict sensitivity and/or resistance and that may be exploited to modulate this form of cell death are needed. We applied two independent approaches, a genome-wide CRISPR-based genetic screen and microarray analysis of ferroptosis-resistant cell lines to uncover acyl-CoA synthetase long-chain family member 4 (Acsl4) as an essential component for ferroptosis execution.
Project description:Translational research is commonly performed in the C57B6/J mouse strain, chosen for its genetic homogeneity and phenotypic uniformity. Here, we evaluate the suitability of the white-footed deer mouse (Peromyscus leucopus) as a model organism for aging research, offering a comparative analysis against C57B6/J and diversity outbred (DO) Mus musculus strains. Our study includes comparisons of body composition, skeletal muscle function, and cardiovascular parameters, shedding light on potential applications and limitations of P. leucopus in aging studies. Notably, P. leucopus exhibits distinct body composition characteristics, emphasizing reduced muscle force exertion and a unique metabolism, particularly in fat mass. Cardiovascular assessments showed changes in arterial stiffness, challenging conventional assumptions and highlighting the need for a nuanced interpretation of aging-related phenotypes. Our study also highlights inherent challenges associated with maintaining and phenotyping P. leucopus cohorts. Behavioral considerations, including anxiety-induced responses during handling and phenotyping assessment, pose obstacles in acquiring meaningful data. Moreover, the unique anatomy of P. leucopus necessitates careful adaptation of protocols designed for Mus musculus. While showcasing potential benefits, further extensive analyses across broader age ranges and larger cohorts are necessary to establish the reliability of P. leucopus as a robust and translatable model for aging studies.
Project description:Ferroptosis is a regulated form of necrotic cell death caused by iron-dependent phospholipid peroxidation. It can be induced by inhibiting glutathione peroxidase 4 (GPX4), the key enzyme for efficiently reducing peroxides within phospholipid bilayers. Recent data suggest that cancer cells undergoing EMT (dedifferentiation) and those resistant to standard therapy expose a high vulnerability toward ferroptosis. Although recent studies have begun to identify and characterize the metabolic and genetic determinants underlying ferroptosis, many mechanisms that dictate ferroptosis sensitivity remain unknown. Here, we show that low cell density sensitizes primary mammary epithelial and breast cancer cells to ferroptosis induced by GPX4 inhibition, whereas high cell density confers resistance. These effects occur irrespective of oncogenic signaling, cellular phenotype and expression of the fatty acid ligase acyl-CoA synthetase long chain family member 4 (ACSL4). By contrast, we show that a massive accumulation of neutral triacylglycerides (TAG) enriched with polyunsaturated fatty acids (PUFA) is induced at low cell density. In addition, de novo lipogenesis and desaturation pathways were found to be reduced at low cell density, indicative of increased fatty acid uptake. Our study suggests that PUFA-mediated toxicity is limited by the enrichment in TAGs that in turn might pose a vulnerability towards ferroptosis. Conclusively, cell density regulates lipid metabolism of breast epithelial and cancer cells, which results in a ferroptosis-sensitive cell state with the potential to be exploited therapeutically during metastatic dissemination.