Molecular Biology: Estrogens Shield Breast Cancer Cells
2007

Estrogens and Breast Cancer Cells

publication Evidence: moderate

Author Information

Author(s): Mead M. Nathaniel, David Shapiro, V. Craig Jordan, Margaret Whalen

Primary Institution: University of Illinois at Urbana–Champaign

Hypothesis

Do estrogens reinforce the evasion of host immunity in breast cancer cells?

Conclusion

Estrogens may help breast cancer cells evade immune responses by increasing levels of a protein that protects them from being killed by immune cells.

Supporting Evidence

  • Estrogen induces the expression of PI-9, which helps cancer cells evade immune attacks.
  • Tamoxifen can block NK cell killing of cancer cells in tumors with high estrogen receptor levels.
  • Environmental estrogens like DDT may also reduce immune function against breast cancer.

Takeaway

Estrogens can help cancer cells hide from the body's defenses, making it harder for the body to fight the cancer.

Methodology

The researchers linked estrogen concentrations to levels of the PI-9 protein and its effect on NK cell-mediated cell death.

Limitations

Most estrogen-responsive breast tumors have low to moderate estrogen receptors, limiting the effectiveness of tamoxifen.

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