Cancer progression by breast tumors with Pit-1-overexpression is blocked by inhibition of metalloproteinase (MMP)-13

Breast Cancer Res. 2014 Dec 20;16(6):505. doi: 10.1186/s13058-014-0505-8.

Abstract

Introduction: The POU class 1 homeobox 1 transcription factor (POU1F1, also known as Pit-1) is expressed in the mammary gland and its overexpression induces profound phenotypic changes in proteins involved in cell proliferation, apoptosis, and invasion. Patients with breast cancer and elevated expression of Pit-1 show a positive correlation with the occurrence of distant metastasis. In this study we evaluate the relationship between Pit-1 and two collagenases: matrix metalloproteinase-1 (MMP-1) and matrix metalloproteinase-13 (MMP-13), which have been related to metastasis in breast cancer.

Methods: We began by transfecting the MCF-7 and MDA-MB-231 human breast adenocarcinoma cell lines with the Pit-1 overexpression vector (pRSV-hPit-1). Afterward, the mRNA, protein, and transcriptional regulation of both MMP-1 and MMP-13 were evaluated by real-time PCR, Western blot, chromatin immunoprecipitation (ChIP), and luciferase reporter assays. We also evaluated Pit-1 overexpression with MMP-1 and MMP-13 knockdown in a severe combined immunodeficiency (SCID) mouse tumor xenograft model. Finally, by immunohistochemistry we correlated Pit-1 with MMP-1 and MMP-13 protein expression in 110 human breast tumors samples.

Results: Our data show that Pit-1 increases mRNA and protein of both MMP-1 and MMP-13 through direct transcriptional regulation. In SCID mice, knockdown of MMP-13 completely blocked lung metastasis in Pit-1-overexpressing MCF-7 cells injected into the mammary fat pad. In breast cancer patients, expression of Pit-1 was found to be positively correlated with the presence of both MMP-1 and MMP-13.

Conclusions: Our data indicates that Pit-1 regulates MMP-1 and MMP-13, and that inhibition of MMP-13 blocked invasiveness to lung in Pit-1-overexpressed breast cancer cells.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adenocarcinoma / genetics*
  • Adenocarcinoma / metabolism
  • Adenocarcinoma / secondary
  • Animals
  • Apoptosis
  • Breast Neoplasms / genetics*
  • Breast Neoplasms / metabolism
  • Breast Neoplasms / pathology
  • Cell Line, Tumor
  • Cell Proliferation
  • Female
  • Gene Expression Regulation, Neoplastic*
  • Humans
  • Lung Neoplasms / secondary
  • MCF-7 Cells
  • Matrix Metalloproteinase 1 / genetics*
  • Matrix Metalloproteinase 1 / metabolism
  • Matrix Metalloproteinase 13 / genetics*
  • Matrix Metalloproteinase 13 / metabolism
  • Mice
  • Neoplasm Invasiveness
  • Neoplasm Metastasis
  • Neoplasm Transplantation
  • RNA, Messenger / metabolism*
  • Transcription Factor Pit-1 / genetics*

Substances

  • POU1F1 protein, human
  • RNA, Messenger
  • Transcription Factor Pit-1
  • MMP13 protein, human
  • Matrix Metalloproteinase 13
  • MMP1 protein, human
  • Matrix Metalloproteinase 1