LMW-E/CDK2 deregulates acinar morphogenesis, induces tumorigenesis, and associates with the activated b-raf-ERK1/2-mTOR pathway in breast cancer patients

MyLinh T. Duong, Said Akli, Caimiao Wei, Hannah F. Wingate, Wenbin Liu, Yiling Lu, Min Yi, Gordon Mills, Kelly K. Hunt, Khandan Keyomarsi

Research output: Contribution to journalArticle

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Abstract

Elastase-mediated cleavage of cyclin E generates low molecular weight cyclin E (LMW-E) isoforms exhibiting enhanced CDK2-associated kinase activity and resistance to inhibition by CDK inhibitors p21 and p27. Approximately 27% of breast cancers express high LMW-E protein levels, which significantly correlates with poor survival. The objective of this study was to identify the signaling pathway(s) deregulated by LMW-E expression in breast cancer patients and to identify pharmaceutical agents to effectively target this pathway. Ectopic LMW-E expression in nontumorigenic human mammary epithelial cells (hMECs) was sufficient to generate xenografts with greater tumorigenic potential than full-length cyclin E, and the tumorigenicity was augmented by in vivo passaging. However, cyclin E mutants unable to interact with CDK2 protected hMECs from tumor development. When hMECs were cultured on Matrigel, LMW-E mediated aberrant acinar morphogenesis, including enlargement of acinar structures and formation of multi-acinar complexes, as denoted by reduced BIM and elevated Ki67 expression. Similarly, inducible expression of LMW-E in transgenic mice generated hyper-proliferative terminal end buds resulting in enhanced mammary tumor development. Reverse-phase protein array assay of 276 breast tumor patient samples and cells cultured on monolayer and in three-dimensional Matrigel demonstrated that, in terms of protein expression profile, hMECs cultured in Matrigel more closely resembled patient tissues than did cells cultured on monolayer. Additionally, the b-Raf-ERK1/2-mTOR pathway was activated in LMW-E-expressing patient samples, and activation of this pathway was associated with poor disease-specific survival. Combination treatment using roscovitine (CDK inhibitor) plus either rapamycin (mTOR inhibitor) or sorafenib (a pan kinase inhibitor targeting b-Raf) effectively prevented aberrant acinar formation in LMW-E-expressing cells by inducing G1/S cell cycle arrest. LMW-E requires CDK2-associated kinase activity to induce mammary tumor formation by disrupting acinar development. The b-Raf-ERK1/2-mTOR signaling pathway is aberrantly activated in breast cancer and can be suppressed by combination treatment with roscovitine plus either rapamycin or sorafenib.

Original languageEnglish (US)
Article numbere1002538
JournalPLoS Genetics
Volume8
Issue number3
DOIs
StatePublished - Mar 1 2012
Externally publishedYes

Fingerprint

Cyclin E
MAP Kinase Signaling System
morphogenesis
cyclins
Morphogenesis
breast neoplasms
carcinogenesis
cancer
Carcinogenesis
Molecular Weight
Breast Neoplasms
molecular weight
tumor
inhibitor
breasts
Breast
epithelial cells
Epithelial Cells
phosphotransferases (kinases)
protein

ASJC Scopus subject areas

  • Genetics
  • Molecular Biology
  • Ecology, Evolution, Behavior and Systematics
  • Cancer Research
  • Genetics(clinical)

Cite this

LMW-E/CDK2 deregulates acinar morphogenesis, induces tumorigenesis, and associates with the activated b-raf-ERK1/2-mTOR pathway in breast cancer patients. / Duong, MyLinh T.; Akli, Said; Wei, Caimiao; Wingate, Hannah F.; Liu, Wenbin; Lu, Yiling; Yi, Min; Mills, Gordon; Hunt, Kelly K.; Keyomarsi, Khandan.

In: PLoS Genetics, Vol. 8, No. 3, e1002538, 01.03.2012.

Research output: Contribution to journalArticle

Duong, MyLinh T. ; Akli, Said ; Wei, Caimiao ; Wingate, Hannah F. ; Liu, Wenbin ; Lu, Yiling ; Yi, Min ; Mills, Gordon ; Hunt, Kelly K. ; Keyomarsi, Khandan. / LMW-E/CDK2 deregulates acinar morphogenesis, induces tumorigenesis, and associates with the activated b-raf-ERK1/2-mTOR pathway in breast cancer patients. In: PLoS Genetics. 2012 ; Vol. 8, No. 3.
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abstract = "Elastase-mediated cleavage of cyclin E generates low molecular weight cyclin E (LMW-E) isoforms exhibiting enhanced CDK2-associated kinase activity and resistance to inhibition by CDK inhibitors p21 and p27. Approximately 27{\%} of breast cancers express high LMW-E protein levels, which significantly correlates with poor survival. The objective of this study was to identify the signaling pathway(s) deregulated by LMW-E expression in breast cancer patients and to identify pharmaceutical agents to effectively target this pathway. Ectopic LMW-E expression in nontumorigenic human mammary epithelial cells (hMECs) was sufficient to generate xenografts with greater tumorigenic potential than full-length cyclin E, and the tumorigenicity was augmented by in vivo passaging. However, cyclin E mutants unable to interact with CDK2 protected hMECs from tumor development. When hMECs were cultured on Matrigel, LMW-E mediated aberrant acinar morphogenesis, including enlargement of acinar structures and formation of multi-acinar complexes, as denoted by reduced BIM and elevated Ki67 expression. Similarly, inducible expression of LMW-E in transgenic mice generated hyper-proliferative terminal end buds resulting in enhanced mammary tumor development. Reverse-phase protein array assay of 276 breast tumor patient samples and cells cultured on monolayer and in three-dimensional Matrigel demonstrated that, in terms of protein expression profile, hMECs cultured in Matrigel more closely resembled patient tissues than did cells cultured on monolayer. Additionally, the b-Raf-ERK1/2-mTOR pathway was activated in LMW-E-expressing patient samples, and activation of this pathway was associated with poor disease-specific survival. Combination treatment using roscovitine (CDK inhibitor) plus either rapamycin (mTOR inhibitor) or sorafenib (a pan kinase inhibitor targeting b-Raf) effectively prevented aberrant acinar formation in LMW-E-expressing cells by inducing G1/S cell cycle arrest. LMW-E requires CDK2-associated kinase activity to induce mammary tumor formation by disrupting acinar development. The b-Raf-ERK1/2-mTOR signaling pathway is aberrantly activated in breast cancer and can be suppressed by combination treatment with roscovitine plus either rapamycin or sorafenib.",
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AU - Wingate, Hannah F.

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AU - Lu, Yiling

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AU - Mills, Gordon

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