Expression of t-DARPP mediates trastuzumab resistance in breast cancer cells

Abbes Belkhiri, Altaf A. Dar, Dun Fa Peng, Mohammad H. Razvi, Cammie Rinehart, Carlos L. Arteaga, Wael El-Rifai

Research output: Contribution to journalArticle

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Abstract

Purpose: We have investigated the role of t-DARPP in trastuzumab resistance in ERBB2-amplified and overexpressed breast cancer cell lines. Experimental Design: We have used the HR-5 and HR-6 trastuzumab-resistant cells that were established from tumors that recurred in the presence of trastuzumab therapy following xenografts of BT-474 cells in nude mice. In addition, SKBR-3 cells, engineered for stable expression of t-DARPP, and HCC-1569 cells, which have constitutive expression of t-DARPP and are de novo resistant to trastuzumab, were used. Results: We reported ≥15-fold up-regulation of mRNA and protein levels of t-DARPP in HR-5 and HR-6 cells compared with their progenitor BT-474 trastuzumab-sensitive cells. The t-DARPP expression was not regulated by changes in its promoter DNA methylation levels. The SKBR-3 cells stably expressing t-DARPP developed resistance to trastuzumab compared with their parental cells and empty vector controls (P < 0.01). The trastuzumab-resistant cell lines showed a significant increase in pAKT (Ser473) and BCL2 protein levels. The small interfering RNA knockdown of t-DARPP in all trastuzumab-resistant cells led to a significant reduction in ERBB2, pAKT (Ser473), and BCL2 protein levels with a significant decrease in cell viability (P ≤ 0.001) and an increase in cleaved caspase-3 levels, indicating the progression of these cells toward apoptosis. The t-DARPP protein was associated with both heat shock protein 90 and ERBB2 forming a potential protein complex. This association may play a role in regulating ERBB2 protein in trastuzumab-resistant cells. Conclusion: We conclude that t-DARPP is a novel molecular target that can mediate the therapeutic resistance to trastuzumab in breast cancer cells.

Original languageEnglish (US)
Pages (from-to)4564-4571
Number of pages8
JournalClinical Cancer Research
Volume14
Issue number14
DOIs
StatePublished - Jul 15 2008

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Breast Neoplasms
Proto-Oncogene Proteins c-bcl-2
Trastuzumab
Proteins
HSP90 Heat-Shock Proteins
Cell Line
DNA Methylation
Heterografts
Nude Mice
Caspase 3
Small Interfering RNA
Cell Survival
Research Design
Up-Regulation
Apoptosis
Messenger RNA
Therapeutics
Neoplasms

ASJC Scopus subject areas

  • Oncology
  • Cancer Research

Cite this

Belkhiri, A., Dar, A. A., Fa Peng, D., Razvi, M. H., Rinehart, C., Arteaga, C. L., & El-Rifai, W. (2008). Expression of t-DARPP mediates trastuzumab resistance in breast cancer cells. Clinical Cancer Research, 14(14), 4564-4571. https://doi.org/10.1158/1078-0432.CCR-08-0121

Expression of t-DARPP mediates trastuzumab resistance in breast cancer cells. / Belkhiri, Abbes; Dar, Altaf A.; Fa Peng, Dun; Razvi, Mohammad H.; Rinehart, Cammie; Arteaga, Carlos L.; El-Rifai, Wael.

In: Clinical Cancer Research, Vol. 14, No. 14, 15.07.2008, p. 4564-4571.

Research output: Contribution to journalArticle

Belkhiri, A, Dar, AA, Fa Peng, D, Razvi, MH, Rinehart, C, Arteaga, CL & El-Rifai, W 2008, 'Expression of t-DARPP mediates trastuzumab resistance in breast cancer cells', Clinical Cancer Research, vol. 14, no. 14, pp. 4564-4571. https://doi.org/10.1158/1078-0432.CCR-08-0121
Belkhiri, Abbes ; Dar, Altaf A. ; Fa Peng, Dun ; Razvi, Mohammad H. ; Rinehart, Cammie ; Arteaga, Carlos L. ; El-Rifai, Wael. / Expression of t-DARPP mediates trastuzumab resistance in breast cancer cells. In: Clinical Cancer Research. 2008 ; Vol. 14, No. 14. pp. 4564-4571.
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