Parity is associated with an expanded macrophage population in the mammary gland
Pregnancy is a well established protective factor against breast cancer. One explanation for protection is the increased differentiation status of the parous epithelium. However, this does not explain the association of parity with increased aggressiveness of breast cancers, particularly cancers that occur soon after pregnancy. Because tumor aggressiveness can be influenced by the cell population that surrounds the mammary epithelium, we examined the potential role of the immune system in establishing a long-term difference between the mammary glands of primiparous and virgin animals. Specific mRNA levels, enzyme activities and antigen expressing cells were quantified in primiparous and virgin mammary glands from Sprague-Dawley rats in diestrous. Our results show that macrophages, but not neutrophils or B-cells, are specifically increased in fully involuted glands compared with age-matched virgin mammary glands. Macrophages play a dual role in tumor progression, both opposing and supporting the process. Our finding of an increased macrophage population in the primiparous mammary gland could explain the dichotomy of the reported association of parity with decreased breast cancer incidence and increased breast cancer aggressiveness.
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Document Type: Research Article
Affiliations: Department of Biochemistry, Biophysics and Molecular Biology, Iowa State University, Ames, IA 50011, USA
Publication date: November 1, 2010
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- The International Journal of Oncology provides an international forum for the publication of the latest, cutting-edge research in the broad area of oncology and cancer treatment. The journal accepts original high quality works and reviews on all aspects of oncology research including carcinogenesis, metastasis, epidemiology, chemotherapy and viral oncology. Through fair and efficient peer review, the journal is dedicated to publishing top tier research in the field, offering authors rapid publication as well as high standards of copy-editing and production. The International Journal of Oncology is published on a monthly basis in both print and early online.
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