Abstract
Pregnancy-associated breast cancers (PABC) generally present at advanced stages and have a poor prognosis. The reasons are unclear but we hypothesized that the continuous high levels of estrogens and progesterone were involved. We have now carried out a detailed analysis of PABC compared to tumors of age-matched nonpregnant (non-PABC) women. Malignant epithelia and tumor-associated stroma of PABC and non-PABC were isolated by laser capture microdissection and gene expression profiled. Additionally, normal breast epithelia and stroma adjacent to the two tumor types were analyzed. Lastly, subsets of previously identified E- and P-regulated genes were defined in all tissues. We find that PABC signatures cluster with established breast cancer subtypes. Major hormone-regulated genes whose expression correlated with epithelia of PABC dealt with regulation of cell proliferation, metabolism, and tumor aggressiveness, including genes used to predict tumor recurrence. Compared to normal epithelia, a significant number of genes associated with cell cycle processes were enriched in PABC, many of which are hormone regulated. Thus, compared to normal epithelia, many of the genes that were differentially expressed in epithelia of PABC were distinct from those differentially expressed in non-PABC. With regard to the tumor microenvironment, immune-related genes were enriched in tumor-associated stroma of PABC. Compared to normal stroma, PABC-associated stroma overexpressed immune response genes, while genes involved in angiogenesis and extracellular matrix deposition were more commonly downregulated. This suggests that the heightened aggressiveness of PABC may involve a predisposition to metastasis through extracellular matrix degradation, plus angiogenesis independence. Moreover, genes encoding cell proliferative factors, signaling, immunomodulators and cell death, were hormone regulated in stroma. In sum, these analyses demonstrate complex patterns of enrichment and hormonal regulation of genes in PABC and suggest that it may have a distinct biological nature.
Original language | English |
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Pages (from-to) | 140-153 |
Number of pages | 14 |
Journal | Hormones and Cancer |
Volume | 4 |
Issue number | 3 |
DOIs | |
Publication status | Published - 2013 Jun |
Bibliographical note
Funding Information:AcknowledgmentsWe thank Wendy Dye for help with data analysis and acknowledge the use of the Laser Capture Microdissection Core, Microarray Core and Computational Bioscience Program of the University of Colorado Cancer Center. This work was supported by the Avon Foundation for Women, the Breast Cancer Research Foundation, the National Foundation for Cancer Research, and NIH R01 CA02689 (to KBH) and by a Building Interdisciplinary Research Careers in Women's Health (BIRCWH) K12 Award (to DMEH).
ASJC Scopus subject areas
- Endocrinology, Diabetes and Metabolism
- Oncology
- Endocrinology
- Endocrine and Autonomic Systems
- Cancer Research