Pan-cancer analysis of pyrimidine metabolism using pathway-based approach unravels complex signaling pathways connections with a role in chemoresistance
Ontology highlight
ABSTRACT: To investigate the effect of DHODH inhibitor, Brequinar (BRQ), in inhibiting the pyrimidine metabolism and its associated signaling pathways, lung cancer cell line (A549) was treated with BRQ for 72 hours and performed gene expression profiling using RNA-seq.
Project description:Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) is a promising agent in selectively killing tumor cells. However, TRAIL monotherapy is not especially successful due to the fact that many cancer cells are resistant to TRAIL. Chemotherapeutic agents, such as doxorubicin have been shown to act synergistically with TRAIL on cancer cells, but the exact mechanisms of actions are poorly understood. In this study we performed high-throughput siRNA screening and genome-wide gene expression profiling on doxorubicin treated U1690 cells to explore novel mechanisms underlying doxorubicin-TRAIL synergy. The screening and expression profiling results were integrated and dihydroorotate dehydrogenase (DHODH) was identified to be a potential candidate. DHODH is rate-limiting enzyme in the pyrimidine synthesis pathway, and its expression was downregulated by doxorubicin and silencing of DHODH sensitized U1690 cells to TRAIL. Inhibition of DHODH activity by brequinar dramatically increased the sensitivity of U1690 cells to TRAIL-induced apoptosis, and was accompanied by downregulation of cFLIPL and mitochondrial depolarization. However, the expressions of DR4 and 5 were not changed in response to brequinar treatment in contrast to doxorubicin. In addition, uridine, an end product of the pyrimidine synthesis pathway was able to rescue the sensitization effects initialized by both brequinar and doxorubicin. Furthermore, other cancer cell lines, LNCaP, MCF-7 and HT-29 were also shown to be sensitized to TRAIL by brequinar. Taken together, our findings have identified a novel drug, brequinar, to be potentially utilized in TRAIL combinatorial cancer therapy and highlighted for the first time the importance of DHODH and pyrimidine pathway in mediating TRAIL sensitization in cancer cells. Total RNA obtained from small cell lung cancer U1690 cells either treated with DMSO control or 1 M-BM-5M doxorubicin for 12 or 24h.
Project description:Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) is a promising agent in selectively killing tumor cells. However, TRAIL monotherapy has not been successful as many cancer cells are resistant to TRAIL. Chemotherapeutic agents, such as doxorubicin have been shown to act synergistically with TRAIL, but the exact mechanisms of actions are poorly understood. In this study, we performed high-throughput small interfering RNA screening and genome-wide gene expression profiling on doxorubicin-treated U1690 cells to explore novel mechanisms underlying doxorubicin-TRAIL synergy. The screening and expression profiling results were integrated and dihydroorotate dehydrogenase (DHODH) was identified as a potential candidate. DHODH is the rate-limiting enzyme in the pyrimidine synthesis pathway, and its expression was downregulated by doxorubicin. We demonstrated that silencing of DHODH or inhibition of DHODH activity by brequinar dramatically increased the sensitivity of U1690 cells to TRAIL-induced apoptosis both in 2D and 3D cultures, and was accompanied by downregulation of c-FLIPL as well as by mitochondrial depolarization. In addition, uridine, an end product of the pyrimidine synthesis pathway was able to rescue the sensitization effects initiated by both brequinar and doxorubicin. Furthermore, several other cancer cell lines, LNCaP, MCF-7 and HT-29 were also shown to be sensitized to TRAIL by brequinar. Taken together, our findings have identified a novel protein target and its inhibitor, brequinar, as a potential agent in TRAIL-based combinatorial cancer therapy and highlighted for the first time the importance of mitochondrial DHODH enzyme and pyrimidine pathway in mediating TRAIL sensitization in cancer cells.
Project description:Despite intensive therapy, children with high-risk neuroblastoma are at risk of treatment failure. We applied a multi-omic system approach to evaluate metabolic vulnerabilities in human neuroblastoma. We combined metabolomics, CRISPR screening and transcriptomic data across >700 solid tumor cell lines and identified dihydroorotate dehydrogenase (DHODH), a critical enzyme in pyrimidine synthesis, as a potential treatment target. Of note, DHODH inhibition is currently under clinical investigation in patients with hematologic malignancies. In neuroblastoma, DHODH expression was identified as an independent risk factor for aggressive disease, and high DHODH levels correlated to worse overall and event-free survival. A subset of tumors with the highest DHODH expression was associated with a dismal prognosis, with a 5-year survival of <10%. In xenograft and transgenic neuroblastoma mouse models treated with the DHODH inhibitor brequinar, tumor growth was dramatically reduced, and survival was extended. Furthermore, brequinar treatment was shown to reduce the expression of MYC targets in three different neuroblastoma models in vivo. A combination of brequinar and temozolomide was curative in the majority of transgenic TH-MYCN neuroblastoma mice, indicating a highly active clinical combination therapy. Overall, DHODH inhibition combined with temozolomide has therapeutic potential in neuroblastoma and we propose this combination for clinical testing.
Project description:Despite intensive therapy, children with high-risk neuroblastoma are at risk of treatment failure. We applied a multi-omic system approach to evaluate metabolic vulnerabilities in human neuroblastoma. We combined metabolomics, CRISPR screening and transcriptomic data across >700 solid tumor cell lines and identified dihydroorotate dehydrogenase (DHODH), a critical enzyme in pyrimidine synthesis, as a potential treatment target. Of note, DHODH inhibition is currently under clinical investigation in patients with hematologic malignancies. In neuroblastoma, DHODH expression was identified as an independent risk factor for aggressive disease, and high DHODH levels correlated to worse overall and event-free survival. A subset of tumors with the highest DHODH expression was associated with a dismal prognosis, with a 5-year survival of <10%. In xenograft and transgenic neuroblastoma mouse models treated with the DHODH inhibitor brequinar, tumor growth was dramatically reduced, and survival was extended. Furthermore, brequinar treatment was shown to reduce the expression of MYC targets in three different neuroblastoma models in vivo. A combination of brequinar and temozolomide was curative in the majority of transgenic TH-MYCN neuroblastoma mice, indicating a highly active clinical combination therapy. Overall, DHODH inhibition combined with temozolomide has therapeutic potential in neuroblastoma and we propose this combination for clinical testing.
Project description:Pan-cancer analysis of pyrimidine metabolism using pathway-based approach unravels complex signaling pathways connections with a role in chemoresistance
Project description:Glioblastoma stem cells (GSCs) reprogram glucose metabolism by hijacking high-affinity glucose uptake to survive in a nutritionally dynamic microenvironment. Here, we trace metabolic aberrations in GSCs to link core genetic mutations in glioblastoma to dependency on de novo pyrimidine synthesis. Targeting the pyrimidine synthetic rate-limiting step enzyme CAD (carbamoyl-phosphate synthetase 2, aspartate transcarbamyolase, dihydroorotase) or the critical downstream enzyme, DHODH (dihydroorotate dehydrogenase) inhibited GSC survival, self-renewal, and in vivo tumor initiation through the depletion of the pyrimidine nucleotide supply. Mutations in EGFR or PTEN generated distinct CAD phosphorylation patterns to activate carbon influx through pyrimidine synthesis. Simultaneous abrogation of tumor-specific driver mutations and DHODH activity with clinically approved inhibitors demonstrated sustained inhibition of metabolic activity of pyrimidine synthesis and GSC tumorigenic capacity. Higher expression of pyrimidine synthesis genes portend poor prognosis of glioblastoma patients. Collectively, our results demonstrate a novel therapeutic approach of precision medicine through targeting the nexus between driver mutations and metabolic reprogramming in cancer stem cells.
Project description:Blocking pyrimidine de novo synthesis via inhibiting Dihydroorotate dehydrogenase (DHODH) is clinically used to treat autoimmunity and to prevent the growth of rapidly dividing cells including activated T-cells. We identified a previously unrecognized resistance of precursors of memory T-cells to pyrimidine starvation. While the treatment effectively blocks effector T-cells, numbers, function and transcriptional profiles of memory T-cells and their precursors remain completely unaltered. We pinpoint this effect to a narrow time-window in the early T-cell expansion phase, when developing effector, but not memory T-cells are selectively vulnerable to pyrimidine starvation. This stems from a higher proliferative pace of early effector T-cells paired with lower pyrimidine synthesis capacity compared to memory precursors. This differential sensitivity constitutes a novel, drug-targetable checkpoint that efficiently diminishes effector T-cells without harming the memory compartment. We envision that knowledge of this pyrimidine synthesis-based cell fate-determining particularity opens up new means to safely manipulate effector T-cell responses.
Project description:De novo pyrimidine biosynthesis is achieved by cytosolic enzymes, CAD and UMPS, and mitochondrial DHODH. However, how these enzymes are orchestrated remains enigmatical. Here, we show that cytosolic aspartate-producing GOT1 clusters with CAD and UMPS. This cytosolic cluster then connects with DHODH, which is mediated by the mitochondrial outer membrane channel protein VDAC3. Therefore, these proteins form a multi-enzyme complex, named “pyrimidinosome”, involving AMPK as a regulator. Activated AMPK dissociates from the complex, enhancing pyrimidinosome assembly to up-regulate intermediate orotate synthesis, which promotes DHODH-mediated ferroptosis defense. In contrast, pyrimidinosome-mediated UMP biosynthesis is significantly increased in cells lacking AMPK, so that cancer cells with lower expression of AMPK are more reliant on de novo pyrimidine biosynthesis and more vulnerable to its inhibition in vitro and in vivo. Our findings reveal the role of pyrimidinosome in regulating pyrimidine flux and ferroptosis, and suggest a pharmaceutical strategy of targeting pyrimidinosome in cancer treatment.
Project description:Blocking pyrimidine de novo synthesis via inhibiting Dihydroorotate dehydrogenase (DHODH) is clinically used to treat autoimmunity and to prevent the growth of rapidly dividing cells including activated T-cells. We identified a previously unrecognized resistance of precursors of memory T-cells to pyrimidine starvation. While the treatment effectively blocks effector T-cells, numbers, function and transcriptional profiles of memory T-cells and their precursors remain completely unaltered. We pinpoint this effect to a narrow time-window in the early T-cell expansion phase, when developing effector, but not memory T-cells are selectively vulnerable to pyrimidine starvation. This stems from a higher proliferative pace of early effector T-cells paired with lower pyrimidine synthesis capacity compared to memory precursors. This differential sensitivity constitutes a novel, drug-targetable checkpoint that efficiently diminishes effector T-cells without harming the memory compartment. We envision that knowledge of this pyrimidine synthesis-based cell fate-determining particularity opens up new means to safely manipulate effector T-cell responses.
Project description:Blocking pyrimidine de novo synthesis via inhibiting Dihydroorotate dehydrogenase (DHODH) is clinically used to treat autoimmunity and to prevent the growth of rapidly dividing cells including activated T-cells. We identified a previously unrecognized resistance of precursors of memory T-cells to pyrimidine starvation. While the treatment effectively blocks effector T-cells, numbers, function and transcriptional profiles of memory T-cells and their precursors remain completely unaltered. We pinpoint this effect to a narrow time-window in the early T-cell expansion phase, when developing effector, but not memory T-cells are selectively vulnerable to pyrimidine starvation. This stems from a higher proliferative pace of early effector T-cells paired with lower pyrimidine synthesis capacity compared to memory precursors. This differential sensitivity constitutes a novel, drug-targetable checkpoint that efficiently diminishes effector T-cells without harming the memory compartment. We envision that knowledge of this pyrimidine synthesis-based cell fate-determining particularity opens up new means to safely manipulate effector T-cell responses.