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Transcription profiling of human age-dichotomized ER+ breast tumors

ABSTRACT: To investigate the biological basis between aging and sporadic breast cancer incidence and prognosis, RNA samples from matched ER+ invasive breast cancers diagnosed in either young (≤45) or old (≥70) women were analyzed by expression microarrays Experiment Overall Design: ER+ breast cancers collected from either young or old women, well matched for other clinical parameters were analyzed using expression microarrays. Age associated tumor subtypes and enrichment of pre-defined gene signatures were identified. Age associated differential expression and an age signature (gene-based classifier) was assessed

ORGANISM(S): Homo sapiens

SUBMITTER: Yau C

PROVIDER: S-ECPF-GEOD-8193 | biostudies-other | 2007

REPOSITORIES: biostudies-other

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Project description:Tumorigenic breast cancer cells characterized by CD44 expression and low or undetectable CD24 levels (CD44+/CD24-/low) may be resistant to chemotherapy and therefore responsible for cancer relapse. Paired breast cancer core biopsies before and after neoadjuvant chemotherapy or lapatinib were obtained and as single cell suspensions stained using antibodies against CD24, CD44, and lineage markers, and then analyzed by flow cytometry. Mammosphere (MS) formation in culture was compared before and after treatment. Global gene expression differences between cancer cells bearing CD44+/CD24-/low cells and all other sorted cells, and between cancer MS and the primary bulk invasive cancers were analyzed. We report that CD44+/CD24-/low tumorigenic breast cancer cells were intrinsically chemoresistant - chemotherapy led to increased CD44+/CD24-/low cells, increased self-renewal capacity on MS assays, and enhanced tumorigeneicity in immunocompromised SCID/Beige mice. Conversely, in patients with HER2 overexpressing tumors, the EGFR/HER2 tyrosine kinase inhibitor, lapatinib decreased CD44+/CD24-/low cells, with the majority of these patients after conventional therapy achieving pathologic complete response, a validated surrogate marker for long-term survival. Gene transcription pathways that underlie chemoresistant, MS-forming CD44+/CD24-/low cells involve genes belonging to stem cell self-renewal, Wnt signaling, and early development pathways. Experiment Overall Design: Cells from human breast tumors were grown as mammospheres (MS). Experiment Overall Design: Isolated single cell suspensions from primary breast cancers were plated onto non-adherent (polyhema-coated) plastic, counted with a hematocytometer, and 20,000 cells were then seeded into a 6-well ultra-low attachment plate supplemented with 2mL MEGM, with the addition of 2 mL of freshly unfrozen MEGM every 3-4 days. Gene expression profiles were taken of both MS and primary bulk tumors and compared with each other.

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Transcription profiling of human age-dichotomized ER+ breast tumors

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