PI3K regulation of RAC1 is required for KRAS-induced pancreatic tumorigenesis in mice

Chia Yen C Wu, Eileen S. Carpenter, Kenneth K. Takeuchi, Christopher J. Halbrook, Louise V. Peverley, Harold Bien, Jason C. Hall, Kathleen E. Delgiorno, Debjani Pal, Yan Song, Chanjuan Shi, Richard Z. Lin, Howard C. Crawford

Research output: Contribution to journalArticle

49 Citations (Scopus)

Abstract

BACKGROUND & AIMS: New drug targets are urgently needed for the treatment of patients with pancreatic ductal adenocarcinoma (PDA). Nearly all PDAs contain oncogenic mutations in the KRAS gene. Pharmacological inhibition of KRAS has been unsuccessful, leading to a focus on downstream effectors that are more easily targeted with small molecule inhibitors. We investigated the contributions of phosphoinositide 3-kinase (PI3K) to KRAS-initiated tumorigenesis.

METHODS: Tumorigenesis was measured in the KrasG12D/+;Ptf1aCre/+ mouse model of PDA; these mice were crossed with mice with pancreas-specific disruption of genes encoding PI3K p110α (Pik3ca), p110β (Pik3cb), or RAC1 (Rac1). Pancreatitis was induced with 5 daily intraperitoneal injections of cerulein. Pancreata and primary acinar cells were isolated; acinar cells were incubated with an inhibitor of p110α (PIK75) followed by a broad-spectrum PI3K inhibitor (GDC0941). PDA cell lines (NB490 and MiaPaCa2) were incubated with PIK75 followed by GDC0941. Tissues and cells were analyzed by histology, immunohistochemistry, quantitative reverse-transcription polymerase chain reaction, and immunofluorescence analyses for factors involved in the PI3K signaling pathway. We also examined human pancreas tissue microarrays for levels of p110α and other PI3K pathway components.

RESULTS: Pancreas-specific disruption of Pik3ca or Rac1, but not Pik3cb, prevented the development of pancreatic tumors in KrasG12D/+;Ptf1aCre/+ mice. Loss of transformation was independent of AKT regulation. Preneoplastic ductal metaplasia developed in mice lacking pancreatic p110α but regressed. Levels of activated and total RAC1 were higher in pancreatic tissues from KrasG12D/+;Ptf1aCre/+ mice compared with controls. Loss of p110α reduced RAC1 activity and expression in these tissues. p110α was required for the up-regulation and activity of RAC guanine exchange factors during tumorigenesis. Levels of p110α and RAC1 were increased in human pancreatic intraepithelial neoplasias and PDAs compared with healthy pancreata.

CONCLUSIONS: KRAS signaling, via p110α to activate RAC1, is required for transformation in KrasG12D/+;Ptf1aCre/+ mice.

Original languageEnglish (US)
Pages (from-to)1405-1416.e7
JournalGastroenterology
Volume147
Issue number6
DOIs
StatePublished - Dec 1 2014

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1-Phosphatidylinositol 4-Kinase
Carcinogenesis
Pancreas
Adenocarcinoma
Acinar Cells
Ceruletide
Metaplasia
Guanine
Intraperitoneal Injections
Pancreatitis
Genes
Statistical Factor Analysis
Reverse Transcription
Fluorescent Antibody Technique
Neoplasms
Histology
Up-Regulation
Immunohistochemistry
Pharmacology
Cell Line

Keywords

  • Cytoskeleton
  • Oncogene
  • Pancreatic Cancer
  • Signal Transduction

ASJC Scopus subject areas

  • Gastroenterology

Cite this

Wu, C. Y. C., Carpenter, E. S., Takeuchi, K. K., Halbrook, C. J., Peverley, L. V., Bien, H., ... Crawford, H. C. (2014). PI3K regulation of RAC1 is required for KRAS-induced pancreatic tumorigenesis in mice. Gastroenterology, 147(6), 1405-1416.e7. https://doi.org/10.1053/j.gastro.2014.08.032

PI3K regulation of RAC1 is required for KRAS-induced pancreatic tumorigenesis in mice. / Wu, Chia Yen C; Carpenter, Eileen S.; Takeuchi, Kenneth K.; Halbrook, Christopher J.; Peverley, Louise V.; Bien, Harold; Hall, Jason C.; Delgiorno, Kathleen E.; Pal, Debjani; Song, Yan; Shi, Chanjuan; Lin, Richard Z.; Crawford, Howard C.

In: Gastroenterology, Vol. 147, No. 6, 01.12.2014, p. 1405-1416.e7.

Research output: Contribution to journalArticle

Wu, CYC, Carpenter, ES, Takeuchi, KK, Halbrook, CJ, Peverley, LV, Bien, H, Hall, JC, Delgiorno, KE, Pal, D, Song, Y, Shi, C, Lin, RZ & Crawford, HC 2014, 'PI3K regulation of RAC1 is required for KRAS-induced pancreatic tumorigenesis in mice', Gastroenterology, vol. 147, no. 6, pp. 1405-1416.e7. https://doi.org/10.1053/j.gastro.2014.08.032
Wu CYC, Carpenter ES, Takeuchi KK, Halbrook CJ, Peverley LV, Bien H et al. PI3K regulation of RAC1 is required for KRAS-induced pancreatic tumorigenesis in mice. Gastroenterology. 2014 Dec 1;147(6):1405-1416.e7. https://doi.org/10.1053/j.gastro.2014.08.032
Wu, Chia Yen C ; Carpenter, Eileen S. ; Takeuchi, Kenneth K. ; Halbrook, Christopher J. ; Peverley, Louise V. ; Bien, Harold ; Hall, Jason C. ; Delgiorno, Kathleen E. ; Pal, Debjani ; Song, Yan ; Shi, Chanjuan ; Lin, Richard Z. ; Crawford, Howard C. / PI3K regulation of RAC1 is required for KRAS-induced pancreatic tumorigenesis in mice. In: Gastroenterology. 2014 ; Vol. 147, No. 6. pp. 1405-1416.e7.
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T1 - PI3K regulation of RAC1 is required for KRAS-induced pancreatic tumorigenesis in mice

AU - Wu, Chia Yen C

AU - Carpenter, Eileen S.

AU - Takeuchi, Kenneth K.

AU - Halbrook, Christopher J.

AU - Peverley, Louise V.

AU - Bien, Harold

AU - Hall, Jason C.

AU - Delgiorno, Kathleen E.

AU - Pal, Debjani

AU - Song, Yan

AU - Shi, Chanjuan

AU - Lin, Richard Z.

AU - Crawford, Howard C.

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N2 - BACKGROUND & AIMS: New drug targets are urgently needed for the treatment of patients with pancreatic ductal adenocarcinoma (PDA). Nearly all PDAs contain oncogenic mutations in the KRAS gene. Pharmacological inhibition of KRAS has been unsuccessful, leading to a focus on downstream effectors that are more easily targeted with small molecule inhibitors. We investigated the contributions of phosphoinositide 3-kinase (PI3K) to KRAS-initiated tumorigenesis.METHODS: Tumorigenesis was measured in the KrasG12D/+;Ptf1aCre/+ mouse model of PDA; these mice were crossed with mice with pancreas-specific disruption of genes encoding PI3K p110α (Pik3ca), p110β (Pik3cb), or RAC1 (Rac1). Pancreatitis was induced with 5 daily intraperitoneal injections of cerulein. Pancreata and primary acinar cells were isolated; acinar cells were incubated with an inhibitor of p110α (PIK75) followed by a broad-spectrum PI3K inhibitor (GDC0941). PDA cell lines (NB490 and MiaPaCa2) were incubated with PIK75 followed by GDC0941. Tissues and cells were analyzed by histology, immunohistochemistry, quantitative reverse-transcription polymerase chain reaction, and immunofluorescence analyses for factors involved in the PI3K signaling pathway. We also examined human pancreas tissue microarrays for levels of p110α and other PI3K pathway components.RESULTS: Pancreas-specific disruption of Pik3ca or Rac1, but not Pik3cb, prevented the development of pancreatic tumors in KrasG12D/+;Ptf1aCre/+ mice. Loss of transformation was independent of AKT regulation. Preneoplastic ductal metaplasia developed in mice lacking pancreatic p110α but regressed. Levels of activated and total RAC1 were higher in pancreatic tissues from KrasG12D/+;Ptf1aCre/+ mice compared with controls. Loss of p110α reduced RAC1 activity and expression in these tissues. p110α was required for the up-regulation and activity of RAC guanine exchange factors during tumorigenesis. Levels of p110α and RAC1 were increased in human pancreatic intraepithelial neoplasias and PDAs compared with healthy pancreata.CONCLUSIONS: KRAS signaling, via p110α to activate RAC1, is required for transformation in KrasG12D/+;Ptf1aCre/+ mice.

AB - BACKGROUND & AIMS: New drug targets are urgently needed for the treatment of patients with pancreatic ductal adenocarcinoma (PDA). Nearly all PDAs contain oncogenic mutations in the KRAS gene. Pharmacological inhibition of KRAS has been unsuccessful, leading to a focus on downstream effectors that are more easily targeted with small molecule inhibitors. We investigated the contributions of phosphoinositide 3-kinase (PI3K) to KRAS-initiated tumorigenesis.METHODS: Tumorigenesis was measured in the KrasG12D/+;Ptf1aCre/+ mouse model of PDA; these mice were crossed with mice with pancreas-specific disruption of genes encoding PI3K p110α (Pik3ca), p110β (Pik3cb), or RAC1 (Rac1). Pancreatitis was induced with 5 daily intraperitoneal injections of cerulein. Pancreata and primary acinar cells were isolated; acinar cells were incubated with an inhibitor of p110α (PIK75) followed by a broad-spectrum PI3K inhibitor (GDC0941). PDA cell lines (NB490 and MiaPaCa2) were incubated with PIK75 followed by GDC0941. Tissues and cells were analyzed by histology, immunohistochemistry, quantitative reverse-transcription polymerase chain reaction, and immunofluorescence analyses for factors involved in the PI3K signaling pathway. We also examined human pancreas tissue microarrays for levels of p110α and other PI3K pathway components.RESULTS: Pancreas-specific disruption of Pik3ca or Rac1, but not Pik3cb, prevented the development of pancreatic tumors in KrasG12D/+;Ptf1aCre/+ mice. Loss of transformation was independent of AKT regulation. Preneoplastic ductal metaplasia developed in mice lacking pancreatic p110α but regressed. Levels of activated and total RAC1 were higher in pancreatic tissues from KrasG12D/+;Ptf1aCre/+ mice compared with controls. Loss of p110α reduced RAC1 activity and expression in these tissues. p110α was required for the up-regulation and activity of RAC guanine exchange factors during tumorigenesis. Levels of p110α and RAC1 were increased in human pancreatic intraepithelial neoplasias and PDAs compared with healthy pancreata.CONCLUSIONS: KRAS signaling, via p110α to activate RAC1, is required for transformation in KrasG12D/+;Ptf1aCre/+ mice.

KW - Cytoskeleton

KW - Oncogene

KW - Pancreatic Cancer

KW - Signal Transduction

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