Leptin, a cytokine mainly produced by adipocytes, seems to play a crucial role in mammary carcinogenesis. In the present study, we explored the mechanism of leptin-mediated promotion of breast tumor growth using xenograft MCF-7 in 45-day-old female nude mice, and an in vitro model represented by MCF-7 three-dimensional cultures. Xenograft tumors, obtained only in animals with estradiol (E(2)) pellet implants, doubled control value after 13 weeks of leptin exposure. In three-dimensional cultures, leptin and/or E(2) enhanced cell-cell adhesion. This increased aggregation seems to be dependent on E-cadherin because it was completely abrogated in the presence of function-blocking E-cadherin antibody or EGTA, a calcium-chelating agent. In three-dimensional cultures, leptin and/or E(2) treatment significantly increased cell growth, which was abrogated when E-cadherin function was blocked. These findings well correlated with an increase of mRNA and protein content of E-cadherin in three-dimensional cultures and in xenografts. In MCF-7 cells both hormones were able to activate E-cadherin promoter. Mutagenesis studies, electrophoretic mobility shift assay, and chromatin immunoprecipitation assays revealed that cyclic AMP-responsive element binding protein and Sp1 motifs, present on E-cadherin promoter, were important for the up-regulatory effects induced by both hormones on E-cadherin expression in breast cancer MCF-7 cells. In conclusion, the present study shows how leptin is able to promote tumor cell proliferation and homotypic tumor cell adhesion via an increase of E-cadherin expression. This combined effect may give reasonable emphasis to the important role of this cytokine in stimulating primary breast tumor cell growth and progression, particularly in obese women.
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|Titolo:||Evidences that leptin upregulates E-cadherin expression in breast cancer: effects on tumor growth and progression|
|Data di pubblicazione:||2007|
|Citazione:||Evidences that leptin upregulates E-cadherin expression in breast cancer: effects on tumor growth and progression / Mauro, Loredana; Catalano, Stefania; Bossi, G; Pellegrino, M; Barone, I; Morales, S; Giordano, C; Bartella, V; Casaburi, Ivan; Ando', Sebastiano. - In: CANCER RESEARCH. - ISSN 0008-5472. - 67:7(2007), pp. 3412-3421.|
|Appare nelle tipologie:||1.1 Articolo in rivista|