Gene Expression Analysis Identifies Common and Distinct Signatures Underlying Ductal and Lobular Breast Cancers.

OBJECTIVE: To uncover potential genes and biological processes that contribute to breast cancer development. STUDY DESIGN: We studied gene expression profiles, which are publicly available from the Gene Expression Omnibus database, for the 2 most prevailing subtypes of breast cancer: lobular and ductal invasive breast carcinomas. RESULTS: We identified a total of 98 genes that shared regulation pattern in both subtypes of breast carcinoma. Further functional annotations indicated that 124 biological processes and 8 Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways were over-represented, such as cell surface receptor signaling pathway. We also identified unique gene expression profiles in each subtype of breast cancer. A total of 460 genes were solely differentially expressed between ductal cancer cells and normal cells, and 75 biological processes and 10 KEGG pathways were enriched by these 460 differential genes, including cell proliferation and regulation of cell death. Meanwhile, 308 genes were found to be differentially expressed between lobular cancer cells and normal cells. Intriguingly, only 11 biological processes and 8 KEGG pathways showed overrepresentation among these 308 genes, such as collagen metabolic process. CONCLUSION: Cumulatively, our results indicate that the invasive lobular and ductal carcinomas share a similar profile of gene expression and pathway alteration but also harbor subtype-specific mechanisms of tumorigenesis.