Pim-1 kinase protects P-glycoprotein from degradation and enables its glycosylation and cell surface expression

Yingqiu Xie, Mehmet Burcu, Douglas E. Linn, Yun Qiu, Maria R. Baer

Research output: Contribution to journalArticle

52 Citations (Scopus)

Abstract

The oncogenic serine/threonine kinase Pim-1 phosphorylates and activates the ATP-binding cassette transporter breast cancer resistance protein (ABCG2). The ABC transporter P-glycoprotein (Pgp; ABCB1) also contains a Pim-1 phosphorylation consensus sequence, and we hypothesized that Pim-1 also regulates Pgp. Pgp is exported from the endoplasmic reticulum (ER) as a 150-kDa species that is glycosylated to 170-kDa Pgp, translocates to the cell surface, and mediates drug efflux; alternatively, 150-kDa Pgp is cleaved to a 130-kDa proteolytic product by ER proteases or undergoes ubiquitination and proteasomal degradation. Pim-1 and Pgp interaction was studied in GST pull-down and phosphorylation in in vitro kinase assays. Pim-1 knockdown and inhibition effects on Pgp expression were studied by immunoblotting and flow cytometry and on Pgp stability by immunoblotting after cycloheximide treatment. Pim-1 directly interacted with and phosphorylated Pgp in intact cells and in vitro. Pim-1 knockdown or inhibition decreased cellular and cell surface 170-kDa Pgp, in association with both transient increase in 130-kDa Pgp and increased Pgp ubiquitination and proteasomal degradation. Pim-1 inhibition also decreased expression of 150-kDa Pgp in the presence of the glycosylation inhibitor 2-deoxy-D-glucose. Finally, Pim-1 inhibition sensitized Pgp-overexpressing cells to doxorubicin. Thus, Pim-1 regulates Pgp expression by protecting 150-kDa Pgp from proteolytic and proteasomal degradation and enabling Pgp glycosylation and cell surface translocation and thus Pgp-mediated drug efflux. Pim-1 inhibitors are entering clinical trials and may provide a novel approach to abrogating drug resistance.

Original languageEnglish
Pages (from-to)310-318
Number of pages9
JournalMolecular Pharmacology
Volume78
Issue number2
DOIs
Publication statusPublished - Aug 2010
Externally publishedYes

Fingerprint

Proto-Oncogene Proteins c-pim-1
P-Glycoprotein
Glycosylation
ATP-Binding Cassette Transporters
Ubiquitination
Immunoblotting
Endoplasmic Reticulum
Phosphorylation
Protein-Serine-Threonine Kinases
Consensus Sequence
Deoxyglucose
Cycloheximide
Drug Resistance
Pharmaceutical Preparations
Doxorubicin
Flow Cytometry
Peptide Hydrolases
Phosphotransferases
Clinical Trials
Breast Neoplasms

ASJC Scopus subject areas

  • Pharmacology
  • Molecular Medicine

Cite this

Pim-1 kinase protects P-glycoprotein from degradation and enables its glycosylation and cell surface expression. / Xie, Yingqiu; Burcu, Mehmet; Linn, Douglas E.; Qiu, Yun; Baer, Maria R.

In: Molecular Pharmacology, Vol. 78, No. 2, 08.2010, p. 310-318.

Research output: Contribution to journalArticle

Xie, Yingqiu ; Burcu, Mehmet ; Linn, Douglas E. ; Qiu, Yun ; Baer, Maria R. / Pim-1 kinase protects P-glycoprotein from degradation and enables its glycosylation and cell surface expression. In: Molecular Pharmacology. 2010 ; Vol. 78, No. 2. pp. 310-318.
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