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A drosophila model for EGFR-Ras and PI3K-dependent human glioma.

Read RD, Cavenee WK, Furnari FB, Thomas JB - PLoS Genet. (2009)

Bottom Line: This network acts synergistically to coordinately stimulate cell cycle entry and progression, protein translation, and inappropriate cellular growth and migration.In particular, we found that the fly orthologs of CyclinE, Cdc25, and Myc are key rate-limiting genes required for glial neoplasia.Moreover, orthologs of Sin1, Rictor, and Cdk4 are genes required only for abnormal neoplastic glial proliferation but not for glial development.

View Article: PubMed Central - PubMed

Affiliation: Molecular Neurobiology Laboratory, Salk Institute for Biological Studies, La Jolla, California, United States of America. rread@salk.edu

ABSTRACT
Gliomas, the most common malignant tumors of the nervous system, frequently harbor mutations that activate the epidermal growth factor receptor (EGFR) and phosphatidylinositol-3 kinase (PI3K) signaling pathways. To investigate the genetic basis of this disease, we developed a glioma model in Drosophila. We found that constitutive coactivation of EGFR-Ras and PI3K pathways in Drosophila glia and glial precursors gives rise to neoplastic, invasive glial cells that create transplantable tumor-like growths, mimicking human glioma. Our model represents a robust organotypic and cell-type-specific Drosophila cancer model in which malignant cells are created by mutations in signature genes and pathways thought to be driving forces in a homologous human cancer. Genetic analyses demonstrated that EGFR and PI3K initiate malignant neoplastic transformation via a combinatorial genetic network composed primarily of other pathways commonly mutated or activated in human glioma, including the Tor, Myc, G1 Cyclins-Cdks, and Rb-E2F pathways. This network acts synergistically to coordinately stimulate cell cycle entry and progression, protein translation, and inappropriate cellular growth and migration. In particular, we found that the fly orthologs of CyclinE, Cdc25, and Myc are key rate-limiting genes required for glial neoplasia. Moreover, orthologs of Sin1, Rictor, and Cdk4 are genes required only for abnormal neoplastic glial proliferation but not for glial development. These and other genes within this network may represent important therapeutic targets in human glioma.

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Myc overexpression or Rb loss synergizes with EGFR.(A鈥揋) 2 碌m optical sections of larval brain hemispheres from late 3rd instar larvae, displayed at the same scale. 20 碌m scale bars. Frontal sections, midway through brains. Anterior up; midline to left. Glial cell nuclei are labeled with Repo (red); glial cell bodies and membranes are labeled with CD8GFP (green) driven by repo-Gal4; HRP (blue) reveals neuropil at high intensity and neuronal cell bodies at low intensity. repo>dMyc brains (C) contain many glia with enlarged nuclei (arrows). repo>dEGFR位;dMyc (D) brains have excess glia (red) throughout the brain, and these glia have very compact cell bodies (green) relative to wild-type glia (B). repo>dEGFR位;dCyclinD;dCdk4 (E) and repo>dEGFR位;Rbf1dsRNA (F) brains display increased numbers of glia (red) relative to wild-type (B), but show a less severe glial phenotype and a more normal neuronal compartment (blue) than either repo>dEGFR位;dp110CAAX (A) or repo>dEGFR位;dMyc (D). The combination of repo>Rbf1dsRNA;dEGFR位;dp110CAAX (G) enhances neoplasia, leading to a dramatic increase in aberrant glia. (H,I) dCyclinE expression (red) in repo>dEGFR位;dp110CAAX glia (H) and in repo>dEGFR位;dp110CAAX;Rbf1dsRNA glia (I), alone and overlaid with the Repo glial marker (blue, right panels). dCyclinE is more strongly and more broadly expressed in neoplastic glia upon Rbf1 loss, as evidenced by the increased number and intensity of dCyclinE-expressing glial nuclei in (I) compared to (H). Anterior is up, midline to the left. 4.5 碌m optical projections; 20 碌m scale bars. (J) Pathway diagram of key effectors involved in glial neoplasia initiated by EGFR and PI3K, showing the pathway circuits driving cell cycle entry and progression, and protein translation. Arrows indicate pathway connections, although these connections are not necessarily direct. Genotypes: (A) UAS-dEGFR位 UAS-dp110CAAX/+; repo-Gal4 UAS-CD8GFP/+, (B) repo-Gal4 UAS-CD8GFP/+, (C) UAS-dMyc/repo-Gal4 UAS-CD8GFP, (D) UAS-dEGFR位/+; repo-Gal4 UAS-CD8GFP/UAS-dMyc, (E) UAS-dEGFR位/+; UAS-dCyclinD UAS-dCdk4/+; repo-Gal4 UAS-CD8GFP, (F) UAS-dEGFR位/+; repo-Gal4 UAS-CD8GFP/UAS-Rbf1dsRNA, (G) UAS-dEGFR位 UAS-dp110CAAX/+; repo-Gal4 UAS-CD8GFP/UAS-Rbf1dsRNA, (H) UAS-dEGFR位 UAS-dp110CAAX/+; repo-Gal4 UAS-CD8GFP/+, (I) UAS-dEGFR位 UAS-dp110CAAX/+; repo-Gal4 UAS-CD8GFP/UAS-Rbf1dsRNA.
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pgen-1000374-g008: Myc overexpression or Rb loss synergizes with EGFR.(A鈥揋) 2 碌m optical sections of larval brain hemispheres from late 3rd instar larvae, displayed at the same scale. 20 碌m scale bars. Frontal sections, midway through brains. Anterior up; midline to left. Glial cell nuclei are labeled with Repo (red); glial cell bodies and membranes are labeled with CD8GFP (green) driven by repo-Gal4; HRP (blue) reveals neuropil at high intensity and neuronal cell bodies at low intensity. repo>dMyc brains (C) contain many glia with enlarged nuclei (arrows). repo>dEGFR位;dMyc (D) brains have excess glia (red) throughout the brain, and these glia have very compact cell bodies (green) relative to wild-type glia (B). repo>dEGFR位;dCyclinD;dCdk4 (E) and repo>dEGFR位;Rbf1dsRNA (F) brains display increased numbers of glia (red) relative to wild-type (B), but show a less severe glial phenotype and a more normal neuronal compartment (blue) than either repo>dEGFR位;dp110CAAX (A) or repo>dEGFR位;dMyc (D). The combination of repo>Rbf1dsRNA;dEGFR位;dp110CAAX (G) enhances neoplasia, leading to a dramatic increase in aberrant glia. (H,I) dCyclinE expression (red) in repo>dEGFR位;dp110CAAX glia (H) and in repo>dEGFR位;dp110CAAX;Rbf1dsRNA glia (I), alone and overlaid with the Repo glial marker (blue, right panels). dCyclinE is more strongly and more broadly expressed in neoplastic glia upon Rbf1 loss, as evidenced by the increased number and intensity of dCyclinE-expressing glial nuclei in (I) compared to (H). Anterior is up, midline to the left. 4.5 碌m optical projections; 20 碌m scale bars. (J) Pathway diagram of key effectors involved in glial neoplasia initiated by EGFR and PI3K, showing the pathway circuits driving cell cycle entry and progression, and protein translation. Arrows indicate pathway connections, although these connections are not necessarily direct. Genotypes: (A) UAS-dEGFR位 UAS-dp110CAAX/+; repo-Gal4 UAS-CD8GFP/+, (B) repo-Gal4 UAS-CD8GFP/+, (C) UAS-dMyc/repo-Gal4 UAS-CD8GFP, (D) UAS-dEGFR位/+; repo-Gal4 UAS-CD8GFP/UAS-dMyc, (E) UAS-dEGFR位/+; UAS-dCyclinD UAS-dCdk4/+; repo-Gal4 UAS-CD8GFP, (F) UAS-dEGFR位/+; repo-Gal4 UAS-CD8GFP/UAS-Rbf1dsRNA, (G) UAS-dEGFR位 UAS-dp110CAAX/+; repo-Gal4 UAS-CD8GFP/UAS-Rbf1dsRNA, (H) UAS-dEGFR位 UAS-dp110CAAX/+; repo-Gal4 UAS-CD8GFP/+, (I) UAS-dEGFR位 UAS-dp110CAAX/+; repo-Gal4 UAS-CD8GFP/UAS-Rbf1dsRNA.

Mentions: dMyc is necessary for glial neoplasia, but is not sufficient when overexpressed alone (Figure 8C). dMyc-overexpressing glia showed polyploidy (Figure 8C, data not shown), indicating that these cells undergo DNA replication without mitosis, but require additional signals for cell cycle progression. In contrast, co-overexpression of dMyc with dEGFR位 produced a phenotype on par with that of repo>dEGFR位;dp110CAAX (Figure 8D), indicating that dMyc overexpression can substitute for PI3K activation and promote neoplasia when combined with EGFR signaling.


A drosophila model for EGFR-Ras and PI3K-dependent human glioma.

Read RD, Cavenee WK, Furnari FB, Thomas JB - PLoS Genet. (2009)

Myc overexpression or Rb loss synergizes with EGFR.(A鈥揋) 2 碌m optical sections of larval brain hemispheres from late 3rd instar larvae, displayed at the same scale. 20 碌m scale bars. Frontal sections, midway through brains. Anterior up; midline to left. Glial cell nuclei are labeled with Repo (red); glial cell bodies and membranes are labeled with CD8GFP (green) driven by repo-Gal4; HRP (blue) reveals neuropil at high intensity and neuronal cell bodies at low intensity. repo>dMyc brains (C) contain many glia with enlarged nuclei (arrows). repo>dEGFR位;dMyc (D) brains have excess glia (red) throughout the brain, and these glia have very compact cell bodies (green) relative to wild-type glia (B). repo>dEGFR位;dCyclinD;dCdk4 (E) and repo>dEGFR位;Rbf1dsRNA (F) brains display increased numbers of glia (red) relative to wild-type (B), but show a less severe glial phenotype and a more normal neuronal compartment (blue) than either repo>dEGFR位;dp110CAAX (A) or repo>dEGFR位;dMyc (D). The combination of repo>Rbf1dsRNA;dEGFR位;dp110CAAX (G) enhances neoplasia, leading to a dramatic increase in aberrant glia. (H,I) dCyclinE expression (red) in repo>dEGFR位;dp110CAAX glia (H) and in repo>dEGFR位;dp110CAAX;Rbf1dsRNA glia (I), alone and overlaid with the Repo glial marker (blue, right panels). dCyclinE is more strongly and more broadly expressed in neoplastic glia upon Rbf1 loss, as evidenced by the increased number and intensity of dCyclinE-expressing glial nuclei in (I) compared to (H). Anterior is up, midline to the left. 4.5 碌m optical projections; 20 碌m scale bars. (J) Pathway diagram of key effectors involved in glial neoplasia initiated by EGFR and PI3K, showing the pathway circuits driving cell cycle entry and progression, and protein translation. Arrows indicate pathway connections, although these connections are not necessarily direct. Genotypes: (A) UAS-dEGFR位 UAS-dp110CAAX/+; repo-Gal4 UAS-CD8GFP/+, (B) repo-Gal4 UAS-CD8GFP/+, (C) UAS-dMyc/repo-Gal4 UAS-CD8GFP, (D) UAS-dEGFR位/+; repo-Gal4 UAS-CD8GFP/UAS-dMyc, (E) UAS-dEGFR位/+; UAS-dCyclinD UAS-dCdk4/+; repo-Gal4 UAS-CD8GFP, (F) UAS-dEGFR位/+; repo-Gal4 UAS-CD8GFP/UAS-Rbf1dsRNA, (G) UAS-dEGFR位 UAS-dp110CAAX/+; repo-Gal4 UAS-CD8GFP/UAS-Rbf1dsRNA, (H) UAS-dEGFR位 UAS-dp110CAAX/+; repo-Gal4 UAS-CD8GFP/+, (I) UAS-dEGFR位 UAS-dp110CAAX/+; repo-Gal4 UAS-CD8GFP/UAS-Rbf1dsRNA.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2636203&req=5

pgen-1000374-g008: Myc overexpression or Rb loss synergizes with EGFR.(A鈥揋) 2 碌m optical sections of larval brain hemispheres from late 3rd instar larvae, displayed at the same scale. 20 碌m scale bars. Frontal sections, midway through brains. Anterior up; midline to left. Glial cell nuclei are labeled with Repo (red); glial cell bodies and membranes are labeled with CD8GFP (green) driven by repo-Gal4; HRP (blue) reveals neuropil at high intensity and neuronal cell bodies at low intensity. repo>dMyc brains (C) contain many glia with enlarged nuclei (arrows). repo>dEGFR位;dMyc (D) brains have excess glia (red) throughout the brain, and these glia have very compact cell bodies (green) relative to wild-type glia (B). repo>dEGFR位;dCyclinD;dCdk4 (E) and repo>dEGFR位;Rbf1dsRNA (F) brains display increased numbers of glia (red) relative to wild-type (B), but show a less severe glial phenotype and a more normal neuronal compartment (blue) than either repo>dEGFR位;dp110CAAX (A) or repo>dEGFR位;dMyc (D). The combination of repo>Rbf1dsRNA;dEGFR位;dp110CAAX (G) enhances neoplasia, leading to a dramatic increase in aberrant glia. (H,I) dCyclinE expression (red) in repo>dEGFR位;dp110CAAX glia (H) and in repo>dEGFR位;dp110CAAX;Rbf1dsRNA glia (I), alone and overlaid with the Repo glial marker (blue, right panels). dCyclinE is more strongly and more broadly expressed in neoplastic glia upon Rbf1 loss, as evidenced by the increased number and intensity of dCyclinE-expressing glial nuclei in (I) compared to (H). Anterior is up, midline to the left. 4.5 碌m optical projections; 20 碌m scale bars. (J) Pathway diagram of key effectors involved in glial neoplasia initiated by EGFR and PI3K, showing the pathway circuits driving cell cycle entry and progression, and protein translation. Arrows indicate pathway connections, although these connections are not necessarily direct. Genotypes: (A) UAS-dEGFR位 UAS-dp110CAAX/+; repo-Gal4 UAS-CD8GFP/+, (B) repo-Gal4 UAS-CD8GFP/+, (C) UAS-dMyc/repo-Gal4 UAS-CD8GFP, (D) UAS-dEGFR位/+; repo-Gal4 UAS-CD8GFP/UAS-dMyc, (E) UAS-dEGFR位/+; UAS-dCyclinD UAS-dCdk4/+; repo-Gal4 UAS-CD8GFP, (F) UAS-dEGFR位/+; repo-Gal4 UAS-CD8GFP/UAS-Rbf1dsRNA, (G) UAS-dEGFR位 UAS-dp110CAAX/+; repo-Gal4 UAS-CD8GFP/UAS-Rbf1dsRNA, (H) UAS-dEGFR位 UAS-dp110CAAX/+; repo-Gal4 UAS-CD8GFP/+, (I) UAS-dEGFR位 UAS-dp110CAAX/+; repo-Gal4 UAS-CD8GFP/UAS-Rbf1dsRNA.
Mentions: dMyc is necessary for glial neoplasia, but is not sufficient when overexpressed alone (Figure 8C). dMyc-overexpressing glia showed polyploidy (Figure 8C, data not shown), indicating that these cells undergo DNA replication without mitosis, but require additional signals for cell cycle progression. In contrast, co-overexpression of dMyc with dEGFR位 produced a phenotype on par with that of repo>dEGFR位;dp110CAAX (Figure 8D), indicating that dMyc overexpression can substitute for PI3K activation and promote neoplasia when combined with EGFR signaling.

Bottom Line: This network acts synergistically to coordinately stimulate cell cycle entry and progression, protein translation, and inappropriate cellular growth and migration.In particular, we found that the fly orthologs of CyclinE, Cdc25, and Myc are key rate-limiting genes required for glial neoplasia.Moreover, orthologs of Sin1, Rictor, and Cdk4 are genes required only for abnormal neoplastic glial proliferation but not for glial development.

View Article: PubMed Central - PubMed

Affiliation: Molecular Neurobiology Laboratory, Salk Institute for Biological Studies, La Jolla, California, United States of America. rread@salk.edu

ABSTRACT
Gliomas, the most common malignant tumors of the nervous system, frequently harbor mutations that activate the epidermal growth factor receptor (EGFR) and phosphatidylinositol-3 kinase (PI3K) signaling pathways. To investigate the genetic basis of this disease, we developed a glioma model in Drosophila. We found that constitutive coactivation of EGFR-Ras and PI3K pathways in Drosophila glia and glial precursors gives rise to neoplastic, invasive glial cells that create transplantable tumor-like growths, mimicking human glioma. Our model represents a robust organotypic and cell-type-specific Drosophila cancer model in which malignant cells are created by mutations in signature genes and pathways thought to be driving forces in a homologous human cancer. Genetic analyses demonstrated that EGFR and PI3K initiate malignant neoplastic transformation via a combinatorial genetic network composed primarily of other pathways commonly mutated or activated in human glioma, including the Tor, Myc, G1 Cyclins-Cdks, and Rb-E2F pathways. This network acts synergistically to coordinately stimulate cell cycle entry and progression, protein translation, and inappropriate cellular growth and migration. In particular, we found that the fly orthologs of CyclinE, Cdc25, and Myc are key rate-limiting genes required for glial neoplasia. Moreover, orthologs of Sin1, Rictor, and Cdk4 are genes required only for abnormal neoplastic glial proliferation but not for glial development. These and other genes within this network may represent important therapeutic targets in human glioma.

Show MeSH
Related in: MedlinePlus