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Phosphatase PTP4A3 Promotes Triple-Negative Breast Cancer Growth and Predicts Poor Patient Survival

Petra den Hollander1, Kathryn Rawls1, Anna Tsimelzon2

  • 1Department of Clinical Cancer Prevention, The University of Texas MD Anderson Cancer Center, Houston, Texas.

Cancer Research
|February 28, 2016
PubMed

Insights

Triple-negative breast cancer (TNBC) lacks targeted therapies. Researchers identified overexpressed phosphatases, including PTP4A3, crucial for TNBC growth and survival, suggesting new therapeutic targets.

Area of Science:

  • Oncology
  • Molecular Biology
  • Biochemistry

Background:

  • Triple-negative breast cancer (TNBC) presents a significant clinical challenge due to its aggressive nature and limited targeted treatment options.
  • Phosphatases play critical roles in cellular signaling, and their dysregulation is implicated in various cancers.

Purpose of the Study:

  • To identify novel therapeutic targets for TNBC by investigating phosphatase expression and function.
  • To characterize the role of specific phosphatases, particularly PTP4A3, in TNBC progression.

Main Methods:

  • Microarray analysis of 102 breast cancers to identify differentially expressed phosphatases.
  • siRNA-mediated knockdown of overexpressed phosphatases in TNBC and ER-positive breast cancer cell lines.
  • In vitro assays for cell growth, anchorage-independent growth, and apoptosis.
  • In vivo studies using TNBC xenograft models.
  • In silico analysis of gene amplification and survival data.

Main Results:

  • 146 phosphatases were differentially expressed in TNBC compared to ER-positive tumors, with 19 upregulated.
  • Depletion of six phosphatases significantly inhibited TNBC cell growth and anchorage-independent growth.
  • PTP4A3 (PRL-3) is essential for G1-S cell-cycle progression in all breast cancer cells but regulates apoptosis selectively in TNBC.
  • PTP4A3 inhibition reduced TNBC tumor growth in vivo.
  • PTP4A3 gene amplification was observed in 29% of basal-like breast cancers, and high PTP4A3 expression correlated with worse overall survival.

Conclusions:

  • Phosphatase overexpression is a key feature of TNBC, highlighting phosphatases as potential therapeutic targets.
  • PTP4A3 is a promising therapeutic target for TNBC, impacting cell-cycle progression and apoptosis.
  • These findings provide a foundation for developing targeted therapies against phosphatases for TNBC patients.

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