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Transcription profiling by array of human breast cancer tumors following anastrozole treatment for 2 and 16 weeks

ABSTRACT: Analysis of breast cancer tumors following anastrozole treatment for 2 weeks and 16 weeks. The aromatase inhibitor anastrozole is an anti-estrogen drug used to treat postmenopausal women with breast cancer. Data provide insight into the molecular mechanism of action of anastrozole on hypoxia and proliferation metagenes. Core-cut tumor biopsies were collected from 81 postmenopausal women with stage I to IIIB ER+ early breast cancer before and after 2 weeks of anastrozole treatment. Further tumor biopsies were obtained from 20 of these patients after 16 weeks of anastrozole treatment prior to surgery

ORGANISM(S): Homo sapiens

SUBMITTER: Ghazoui Z

PROVIDER: S-ECPF-MTAB-520 | biostudies-other | 2011 May

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 by array of human breast cancer tumors following anastrozole treatment for 2 and 16 weeks

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