Category: 2010

BACKGROUND: Basal-like carcinoma are aggressive breast cancers that frequently carry p53 inactivating mutations, lack estrogen receptor-α (ERα) and express the cancer stem cell markers CD133 and CD44. These tumors also over-express Interleukin 6 (IL-6), a pro-inflammatory cytokine that stimulates the growth of breast cancer stem/progenitor cells.

RESULTS: Here we show that p53 deficiency in breast cancer cells induces a loss of methylation at IL-6 proximal promoter region, which is maintained by an IL-6 autocrine loop. IL-6 also elicits the loss of methylation at the CD133 promoter region 1 and of CD44 proximal promoter, enhancing CD133 and CD44 gene transcription. In parallel, IL-6 induces the methylation of estrogen receptor (ERα) promoter and the loss of ERα mRNA expression. Finally, IL-6 induces the methylation of IL-6 distal promoter and of CD133 promoter region 2, which harbour putative repressor regions.

CONCLUSION: We conclude that IL-6, whose methylation-dependent autocrine loop is triggered by the inactivation of p53, induces an epigenetic reprogramming that drives breast carcinoma cells towards a basal-like/stem cell-like gene expression profile.

Go to the full article: D’Anello L, Sansone P, Storci G, Mitrugno V, D’Uva G, Chieco P, Bonafé M. Epigenetic control of the basal-like gene expression profile via Interleukin-6 in breast cancer cells. Molecular Cancer, 2010

Extracellular and intracellular mediators of inflammation, such as tumor necrosis factor alpha (TNFα) and NF-kappaB (NF-κB), play major roles in breast cancer pathogenesis, progression and relapse. SLUG, a mediator of the epithelial-mesenchymal transition process, is over-expressed in CD44(+)/CD24(-) tumor initiating breast cancer cells and in basal-like carcinoma, a subtype of aggressive breast cancer endowed with a stem cell-like gene expression profile. Cancer stem cells also over-express members of the pro-inflammatory NF-κB network, but their functional relationship with SLUG expression in breast cancer cells remains unclear. Here, we show that TNFα treatment of human breast cancer cells up-regulates SLUG with a dependency on canonical NF-κB/HIF1α signaling, which is strongly enhanced by p53 inactivation. Moreover, SLUG up-regulation engenders breast cancer cells with stem cell-like properties including enhanced expression of CD44 and Jagged-1 in conjunction with estrogen receptor alpha down-regulation, growth as mammospheres, and extracellular matrix invasiveness. Our results reveal a molecular mechanism whereby TNFα, a major pro-inflammatory cytokine, imparts breast cancer cells with stem cell-like features, which are connected to increased tumor aggressiveness.

Go to the full article: Storci G, Sansone P, Mari S, D’Uva G, Tavolari S, Guarnieri T, Taffurelli M, Ceccarelli C, Santini D, Chieco P, Marcu KB, Bonafè M. TNFalpha up‐regulates SLUG via the NF‐kappaB/HIF1alpha axis, which imparts breast cancer cells with a stem cell‐like phenotype. J Cell Physiology, 2010