HP1 βis α biomarker for breast cancer prognosis and PARP inhibitor therapy

Young Ho Lee, Xiyong Liu, Fuming Qiu, Timothy R. O'Connor, Yun Yen, David K. Ann

Research output: Contribution to journalArticle

Abstract

Members of the heterochromatin protein 1 family (HP1α, β and γ) are mostly associated with heterochromatin and play important roles in gene regulation and DNA damage response. Altered expression of individual HP1 subtype has profound impacts on cell proliferation and tumorigenesis. We analyzed the expression profile of HP1 family by data mining using a published microarray data set coupled with retrospective immunohistochemistry analyses of archived breast cancer biospecimens. We found that the patient group overexpressing HP1β mRNA is associated with poorly differentiated breast tumors and with a significantly lower survival rate. Immunohistochemical staining against HP1a, HP1βand HP1 γ shows that respective HP1 expression level is frequently altered in breast cancers. 57.4-60.1 % of samples examined showed high HP1β expression and 39.9-42.6 % of examined tumors showed no or low expression of each HP1 subtype. Interestingly, comparative analysis on HP1 expression profile and breast cancer markers revealed a positive correlation between the respective expression level of all three HP1 subtypes and Ki-67, a cell proliferation and well-known breast cancer marker. To explore the effect of individual HP1 on PARP inhibitor therapy for breast cancer, MCF7 breast cancer cells and individually HP1-depleted MCF7 cells were treated with PARP inhibitor ABT-888 with or without carboplatin. Notably, HP1 β-knockdown cells are hypersensitive to the PARP inhibitor ABT-888 alone and its combination with carboplatin. In summary, while increased HP1β expression is associated with the poor prognosis in breast cancer, compromised HP1β abundance may serve as a useful predictive marker for chemotherapy, including PARP inhibitors against breast cancer.

Original languageEnglish
Article numbere0121207
JournalPLoS One
Volume10
Issue number3
DOIs
Publication statusPublished - Mar 13 2015
Externally publishedYes

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Biomarkers
breast neoplasms
prognosis
biomarkers
Breast Neoplasms
therapeutics
Carboplatin
Cell proliferation
Tumors
Chemotherapy
Therapeutics
Microarrays
Gene expression
heterochromatin
Data mining
cell proliferation
Cells
Messenger RNA
Cell Proliferation
Poly(ADP-ribose) Polymerase Inhibitors

ASJC Scopus subject areas

  • Agricultural and Biological Sciences(all)
  • Biochemistry, Genetics and Molecular Biology(all)
  • Medicine(all)

Cite this

HP1 βis α biomarker for breast cancer prognosis and PARP inhibitor therapy. / Lee, Young Ho; Liu, Xiyong; Qiu, Fuming; O'Connor, Timothy R.; Yen, Yun; Ann, David K.

In: PLoS One, Vol. 10, No. 3, e0121207, 13.03.2015.

Research output: Contribution to journalArticle

Lee, Young Ho ; Liu, Xiyong ; Qiu, Fuming ; O'Connor, Timothy R. ; Yen, Yun ; Ann, David K. / HP1 βis α biomarker for breast cancer prognosis and PARP inhibitor therapy. In: PLoS One. 2015 ; Vol. 10, No. 3.
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