EZH2 promotes a bi-lineage identity in basal-like breast cancer cells

ABSTRACT: The mechanisms regulating breast cancer differentiation state are poorly understood. Of particular interest are molecular regulators controlling the highly aggressive and poorly differentiated traits of basal-like breast carcinomas. Here we show that the Polycomb factor EZH2 maintains the differentiation state of basal-like breast cancer cells, and promotes the expression of progenitor-associated and basal-lineage genes. Specifically, EZH2 regulates the composition of basal-like breast cancer cell populations by promoting a M-bM-^@M-^\bi-lineageM-bM-^@M-^] differentiation state, in which cells co-express basal- and luminal-lineage markers. We show that human basal-like breast cancers contain a subpopulation of bi-lineage cells, and that EZH2-deficient cells give rise to tumors with a decreased proportion of such cells. Bi-lineage cells express genes that are active in normal luminal progenitors, and possess increased colony formation capacity, consistent with a primitive differentiation state. We found that GATA3, a driver of luminal differentiation, performs a function opposite to EZH2, acting to suppress bi-lineage identity and luminal progenitor gene expression. GATA3 levels increase upon EZH2 silencing, leading to the observed decrease in bi-lineage cell numbers. Our findings reveal a novel role for EZH2 in controlling basal-like breast cancer differentiation state and intra-tumoral cell composition. Total of four treatments (HCC70 cells stably expressing shEZH2, shEED, or EZH2 cDNA, and MDA-MB-468 cells stably expressing shEZH2) were done in duplicates, each with its own control.

ORGANISM(S): Homo sapiens

SUBMITTER: Roy Granit 

PROVIDER: E-GEOD-36939 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress