RESUMO
Snail2 is a zinc finger transcription factor involved in driving epithelial to mesenchymal transitions. Snail2 null mice are viable, but display defects in melanogenesis, gametogenesis and hematopoiesis, and are markedly radiosensitive. Here, using mouse genetics, we have studied the contributions of Snail2 to epidermal homeostasis and skin carcinogenesis. Snail2 (-/-) mice presented a defective epidermal terminal differentiation and, unexpectedly, an increase in number, size and malignancy of tumor lesions when subjected to the two-stage mouse skin chemical carcinogenesis protocol, compared with controls. Additionally, tumor lesions from Snail2 (-/-) mice presented a high inflammatory component with an elevated percentage of myeloid precursors in tumor lesions that was further increased in the presence of the anti-inflammatory agent dexamethasone. In vitro studies in Snail2 null keratinocytes showed that loss of Snail2 leads to a decrease in proliferation indicating a non-cell autonomous role for Snail2 in the skin carcinogenic response observed in vivo. Bone marrow (BM) cross-reconstitution assays between Snail2 wild-type and null mice showed that Snail2 absence in the hematopoietic system fully reproduces the tumor behavior of the Snail2 null mice and triggers the accumulation of myeloid precursors in the BM, blood and tumor lesions. These results indicate a new role for Snail2 in preventing myeloid precursors recruitment impairing skin chemical carcinogenesis progression.
Assuntos
Inflamação/patologia , Queratinócitos/patologia , Células Progenitoras Mieloides/patologia , Neoplasias Experimentais/patologia , Neoplasias Cutâneas/patologia , Fatores de Transcrição/fisiologia , 9,10-Dimetil-1,2-benzantraceno/toxicidade , Animais , Apoptose , Western Blotting , Carcinógenos/toxicidade , Diferenciação Celular , Proliferação de Células , Células Cultivadas , Imunofluorescência , Hematopoese , Técnicas Imunoenzimáticas , Inflamação/induzido quimicamente , Inflamação/metabolismo , Queratinócitos/efeitos dos fármacos , Queratinócitos/metabolismo , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Células Progenitoras Mieloides/efeitos dos fármacos , Células Progenitoras Mieloides/metabolismo , Neoplasias Experimentais/induzido quimicamente , Neoplasias Experimentais/metabolismo , RNA Mensageiro/genética , Reação em Cadeia da Polimerase em Tempo Real , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Neoplasias Cutâneas/induzido quimicamente , Neoplasias Cutâneas/metabolismo , Fatores de Transcrição da Família SnailRESUMO
Basal-like breast cancers (BLBC) express a luminal progenitor gene signature. Notch receptor signaling promotes luminal cell fate specification in the mammary gland, while suppressing stem cell self-renewal. Here we show that deletion of Lfng, a sugar transferase that prevents Notch activation by Jagged ligands, enhances stem/progenitor cell proliferation. Mammary-specific deletion of Lfng induces basal-like and claudin-low tumors with accumulation of Notch intracellular domain fragments, increased expression of proliferation-associated Notch targets, amplification of the Met/Caveolin locus, and elevated Met and Igf-1R signaling. Human BL breast tumors, commonly associated with JAGGED expression, elevated MET signaling, and CAVEOLIN accumulation, express low levels of LFNG. Thus, reduced LFNG expression facilitates JAG/NOTCH luminal progenitor signaling and cooperates with MET/CAVEOLIN basal-type signaling to promote BLBC.
