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Human prostate cancer expresses the low affinity insulin-like growth factor binding protein IGFBP-rP1

A Degeorges1, F Wang, H F Frierson

  • 1Department of Urology, Molecular Urology, University of Virginia Health Sciences Center, Charlottesville 22908, USA.

Cancer Research
|June 26, 1999
PubMed

Insights

Insulin-like growth factor binding protein-related protein 1 (IGFBP-rP1) is found in prostate cancer but not normal tissue. Its expression can be induced in cancer cells within the body, suggesting a role in tumor development.

Area of Science:

  • Molecular Biology
  • Oncology
  • Endocrinology

Background:

  • Alterations in the insulin-like growth factor (IGF) axis are linked to prostate disease.
  • Insulin-like growth factor binding proteins (IGFBPs) modulate IGF actions.
  • IGFBP-related protein 1 (IGFBP-rP1), also known as IGFBP-7, is a newly identified IGFBP family member with an unclear biological function.

Purpose of the Study:

  • To investigate the localization of IGFBP-rP1 in prostate cancer and benign prostate tissues.
  • To analyze the expression of IGFBP-rP1 in prostate cancer cell lines and in vivo models.

Main Methods:

  • Immunohistochemistry using a specific polyclonal antibody (T1A12) to detect IGFBP-rP1.
  • Northern blot analysis to assess IGFBP-rP1 mRNA expression in prostate cancer cell lines.
  • Analysis of tumor xenografts generated from prostate cancer cell lines in vivo.

Main Results:

  • IGFBP-rP1 staining was intense in nerves and weak in smooth muscle cells; lymphocytes were negative.
  • Normal prostatic secretory epithelium and benign prostatic hyperplasia (BPH) epithelium showed little to no IGFBP-rP1 staining.
  • Positive IGFBP-rP1 staining was observed in 90.5% of primary adenocarcinomas and 100% of metastases.
  • Prostate cancer cell lines did not express IGFBP-rP1 mRNA in vitro.
  • IGFBP-rP1 expression was induced in vivo in tumor xenografts when prostate cancer cells interacted with the host environment, particularly in bone marrow.

Conclusions:

  • IGFBP-rP1 is expressed in both in situ and invasive prostate neoplasms, distinguishing them from normal or hyperplastic epithelium.
  • The expression of IGFBP-rP1 can be induced in human prostate cancer cell lines in vivo, suggesting a role for the host microenvironment.
  • IGFBP-rP1 may serve as a potential biomarker or therapeutic target in prostate cancer.

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