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Neutrophil elastase-mediated degradation of IRS-1 accelerates lung tumor growth.

Houghton AM, Rzymkiewicz DM, Ji H, Gregory AD, Egea EE, Metz HE, Stolz DB, Land SR, Marconcini LA, Kliment CR, Jenkins KM, Beaulieu KA, Mouded M, Frank SJ, Wong KK, Shapiro SD - Nat. Med. (2010)

Bottom Line: Recent data suggest that tumor-associated inflammatory cells may modify lung tumor growth and invasiveness.This study identifies IRS-1 as a key regulator of PI3K within malignant cells.Additionally, to our knowledge, this is the first description of a secreted proteinase gaining access to the inside of a cell and altering intracellular signaling.

View Article: PubMed Central - PubMed

Affiliation: Department of Medicine, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA.

ABSTRACT
Lung cancer is the leading cause of cancer death worldwide. Recent data suggest that tumor-associated inflammatory cells may modify lung tumor growth and invasiveness. To determine the role of neutrophil elastase (encoded by Elane) on tumor progression, we used the loxP-Stop-loxP K-ras(G12D) (LSL-K-ras) model of mouse lung adenocarcinoma to generate LSL-K-ras-Elane(-/-) mice. Tumor burden was markedly reduced in LSL-K-ras-Elane(-/-) mice at all time points after induction of mutant K-ras expression. Kaplan-Meier survival analysis showed that whereas all LSL-K-ras-Elane(+/+) mice died, none of the mice lacking neutrophil elastase died. Neutrophil elastase directly induced tumor cell proliferation in both human and mouse lung adenocarcinomas by gaining access to an endosomal compartment within tumor cells, where it degraded insulin receptor substrate-1 (IRS-1). Immunoprecipitation studies showed that, as neutrophil elastase degraded IRS-1, there was increased interaction between phosphatidylinositol 3-kinase (PI3K) and the potent mitogen platelet-derived growth factor receptor (PDGFR), thereby skewing the PI3K axis toward tumor cell proliferation. The inverse relationship identified between neutrophil elastase and IRS-1 in LSL-K-ras mice was also identified in human lung adenocarcinomas, thus translating these findings to human disease. This study identifies IRS-1 as a key regulator of PI3K within malignant cells. Additionally, to our knowledge, this is the first description of a secreted proteinase gaining access to the inside of a cell and altering intracellular signaling.

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NE-induced proliferation is dependent upon PDGFR—PI3K signaling(a) Representative images for PDGF and PDGFR IHC of LSL/K-ras tumors. Inset, high magnification showing PDGF and PDGFR staining within cells displaying tumor morphology. (b) Western blots for PDGF, PDGFRα, pPDGFRα and β-actin from NE-exposed A549 cell lysates. Results from a representative experiment in triplicate. Immunoprecipitation of (c) p85 and (d) phospho-tyrosine p85 from A549 cell lysates followed by Western blotting for PDGFRα. Membranes stripped and probed for p85. (e) Representative blot for PDGFRα following siRNA treatment with SCR siRNA vs. PDGFRα siRNA. (f) 3H uptake for PDGFRα-silenced A549 cells subsequently exposed to NE or vehicle. Results from a representative experiment in triplicate. Bars +/− SEM. *P<0.001.
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Figure 3: NE-induced proliferation is dependent upon PDGFR—PI3K signaling(a) Representative images for PDGF and PDGFR IHC of LSL/K-ras tumors. Inset, high magnification showing PDGF and PDGFR staining within cells displaying tumor morphology. (b) Western blots for PDGF, PDGFRα, pPDGFRα and β-actin from NE-exposed A549 cell lysates. Results from a representative experiment in triplicate. Immunoprecipitation of (c) p85 and (d) phospho-tyrosine p85 from A549 cell lysates followed by Western blotting for PDGFRα. Membranes stripped and probed for p85. (e) Representative blot for PDGFRα following siRNA treatment with SCR siRNA vs. PDGFRα siRNA. (f) 3H uptake for PDGFRα-silenced A549 cells subsequently exposed to NE or vehicle. Results from a representative experiment in triplicate. Bars +/− SEM. *P<0.001.

Mentions: Of growth factors known to activate PI3K, the PDGF/PDGFR complex is an attractive candidate to drive tumor cell proliferation. It's a potent inducer of pAkt via PI3K, is not found in lung epithelial cells, but is highly expressed in non-small cell lung cancer (NSCLC)19. Both the ligand and the receptor are produced in NSCLC thereby creating a potent autocrine loop for PI3K activation. LSL-K-ras tumors also express PDGF and PDGFR (Fig. 3a).


Neutrophil elastase-mediated degradation of IRS-1 accelerates lung tumor growth.

Houghton AM, Rzymkiewicz DM, Ji H, Gregory AD, Egea EE, Metz HE, Stolz DB, Land SR, Marconcini LA, Kliment CR, Jenkins KM, Beaulieu KA, Mouded M, Frank SJ, Wong KK, Shapiro SD - Nat. Med. (2010)

NE-induced proliferation is dependent upon PDGFR—PI3K signaling(a) Representative images for PDGF and PDGFR IHC of LSL/K-ras tumors. Inset, high magnification showing PDGF and PDGFR staining within cells displaying tumor morphology. (b) Western blots for PDGF, PDGFRα, pPDGFRα and β-actin from NE-exposed A549 cell lysates. Results from a representative experiment in triplicate. Immunoprecipitation of (c) p85 and (d) phospho-tyrosine p85 from A549 cell lysates followed by Western blotting for PDGFRα. Membranes stripped and probed for p85. (e) Representative blot for PDGFRα following siRNA treatment with SCR siRNA vs. PDGFRα siRNA. (f) 3H uptake for PDGFRα-silenced A549 cells subsequently exposed to NE or vehicle. Results from a representative experiment in triplicate. Bars +/− SEM. *P<0.001.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2821801&req=5

Figure 3: NE-induced proliferation is dependent upon PDGFR—PI3K signaling(a) Representative images for PDGF and PDGFR IHC of LSL/K-ras tumors. Inset, high magnification showing PDGF and PDGFR staining within cells displaying tumor morphology. (b) Western blots for PDGF, PDGFRα, pPDGFRα and β-actin from NE-exposed A549 cell lysates. Results from a representative experiment in triplicate. Immunoprecipitation of (c) p85 and (d) phospho-tyrosine p85 from A549 cell lysates followed by Western blotting for PDGFRα. Membranes stripped and probed for p85. (e) Representative blot for PDGFRα following siRNA treatment with SCR siRNA vs. PDGFRα siRNA. (f) 3H uptake for PDGFRα-silenced A549 cells subsequently exposed to NE or vehicle. Results from a representative experiment in triplicate. Bars +/− SEM. *P<0.001.
Mentions: Of growth factors known to activate PI3K, the PDGF/PDGFR complex is an attractive candidate to drive tumor cell proliferation. It's a potent inducer of pAkt via PI3K, is not found in lung epithelial cells, but is highly expressed in non-small cell lung cancer (NSCLC)19. Both the ligand and the receptor are produced in NSCLC thereby creating a potent autocrine loop for PI3K activation. LSL-K-ras tumors also express PDGF and PDGFR (Fig. 3a).

Bottom Line: Recent data suggest that tumor-associated inflammatory cells may modify lung tumor growth and invasiveness.This study identifies IRS-1 as a key regulator of PI3K within malignant cells.Additionally, to our knowledge, this is the first description of a secreted proteinase gaining access to the inside of a cell and altering intracellular signaling.

View Article: PubMed Central - PubMed

Affiliation: Department of Medicine, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA.

ABSTRACT
Lung cancer is the leading cause of cancer death worldwide. Recent data suggest that tumor-associated inflammatory cells may modify lung tumor growth and invasiveness. To determine the role of neutrophil elastase (encoded by Elane) on tumor progression, we used the loxP-Stop-loxP K-ras(G12D) (LSL-K-ras) model of mouse lung adenocarcinoma to generate LSL-K-ras-Elane(-/-) mice. Tumor burden was markedly reduced in LSL-K-ras-Elane(-/-) mice at all time points after induction of mutant K-ras expression. Kaplan-Meier survival analysis showed that whereas all LSL-K-ras-Elane(+/+) mice died, none of the mice lacking neutrophil elastase died. Neutrophil elastase directly induced tumor cell proliferation in both human and mouse lung adenocarcinomas by gaining access to an endosomal compartment within tumor cells, where it degraded insulin receptor substrate-1 (IRS-1). Immunoprecipitation studies showed that, as neutrophil elastase degraded IRS-1, there was increased interaction between phosphatidylinositol 3-kinase (PI3K) and the potent mitogen platelet-derived growth factor receptor (PDGFR), thereby skewing the PI3K axis toward tumor cell proliferation. The inverse relationship identified between neutrophil elastase and IRS-1 in LSL-K-ras mice was also identified in human lung adenocarcinomas, thus translating these findings to human disease. This study identifies IRS-1 as a key regulator of PI3K within malignant cells. Additionally, to our knowledge, this is the first description of a secreted proteinase gaining access to the inside of a cell and altering intracellular signaling.

Show MeSH
Related in: MedlinePlus