Acquired resistance to erlotinib in A-431 epidermoid cancer cells requires down-regulation of MMAC1/PTEN and up-regulation of phosphorylated Akt.

Acquired resistance to erlotinib in A-431 epidermoid cancer cells requires down-regulation of MMAC1/PTEN and up-regulation of phosphorylated Akt. Research Abstract Details 

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Acquired resistance to erlotinib in A-431 epidermoid cancer cells requires down-regulation of MMAC1/PTEN and up-regulation of phosphorylated Akt. Abstract Text:

Fumiyuki Yamasaki,Mary J Johansen,Dongwei Zhang,Savitri Krishnamurthy,Edward Felix,Chandra Bartholomeusz,Richard J Aguilar,Kaoru Kurisu,Gordon B Mills,Gabriel N Hortobagyi,Naoto T Ueno,

Erlotinib (Tarceva), an epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor, has clinical activity in advanced lung cancer, but disease that initially responds to erlotinib eventually progresses. The mechanism of this acquired resistance is unclear. We established two erlotinib-resistant pools of A-431 cells, a well-characterized epidermoid cancer cell line that constitutively overexpresses EGFR and is sensitive to erlotinib, by continuous exposure to erlotinib over a 6-month period. The extent of EGFR gene amplification or mutation of the EGFR tyrosine kinase domain was not altered in the resistant cells. Intracellular erlotinib concentrations, determined by liquid chromatography-tandem mass spectrometry, were almost the same in all three cell lines. Immunoprecipitation with EGFR antibody followed by detection with phosphotyrosine antibody revealed that erlotinib effectively reduced EGFR phosphorylation in both parental cells and resistant cells. Erlotinib induced mutated in multiple advanced cancers 1/phosphatase and tensin homologue (MMAC1/PTEN) and suppressed phosphorylated Akt (Ser(473)) but not in the erlotinib-resistant cells. Overexpression of MMAC1/PTEN by transfection with Ad.MMAC1/PTEN or by pharmacologic suppression of Akt activity restored erlotinib sensitivity in both resistant pools. Further, transfection of parental A-431 cells with constitutively active Akt was sufficient to cause resistance to erlotinib. We propose that acquired erlotinib resistance associated with MMAC1/PTEN down-regulation and Akt activation could be overcome by inhibitors of signaling through the phosphatidylinositol 3-kinase pathway.

Acquired resistance to erlotinib in A-431 epidermoid cancer cells requires down-regulation of MMAC1/PTEN and up-regulation of phosphorylated Akt. Publishing Authors By Initials

F Yamasaki,MJ Johansen,D Zhang,S Krishnamurthy,E Felix,C Bartholomeusz,RJ Aguilar,K Kurisu,GB Mills,GN Hortobagyi,NT Ueno,

For similar genetic processes: gene expression regulation: up-regulation research abstracts see: genetic processes: gene expression regulation: up-regulation research

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Acquired resistance to erlotinib in A-431 epidermoid cancer cells requires down-regulation of MMAC1/PTEN and up-regulation of phosphorylated Akt. Journal Published:

PUBLICATION TYPE: Research Support, Non-U.S. Gov

Journal: Cancer research

VOLUME: 67

Page Numbers: 5779-88

Journal Abbreviation: Cancer Res.

ISSN: 0008-5472

DAY: 15

MONTH: Jun

YEAR: 2007

Acquired resistance to erlotinib in A-431 epidermoid cancer cells requires down-regulation of MMAC1/PTEN and up-regulation of phosphorylated Akt. Information

Number of References:

LANGUAGE: eng

NlmUniqueID: 2984705

Acquired resistance to erlotinib in A-431 epidermoid cancer cells requires down-regulation of MMAC1/PTEN and up-regulation of phosphorylated Akt. Keywords Mesh Terms:

KEYWORDS: Up-Regulation

MESH TERMS: metabolism

Chemical & Substance for Abstract: Acquired resistance to erlotinib in A-431 epidermoid cancer cells requires down-regulation of MMAC1/PTEN and up-regulation of phosphorylated Akt. Information

Substance Name: PTEN Phosphohydrolase

Registry Number: EC 3.1.3.67

Grant and Affiliation Information for Acquired resistance to erlotinib in A-431 epidermoid cancer cells requires down-regulation of MMAC1/PTEN and up-regulation of phosphorylated Akt.

AFFILIATION: Breast Cancer Translational Research Laboratory, The University of Texas M. D. Anderson Cancer Center, Houston, Texas 77030-4009, USA.

Country: United States

AGENCY: United States NCI

GRANT: CA-16672

ACRONYM: CA

MEDLINETA: Cancer Res

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