First name
Chiara
Last name
Malinverno
Year of Study
Thesis Title
RAB5A in the control of mammary epithelial morphogenesis and motility
Thesis Abstract
RAB5A, a master regulator of endocytosis, promotes a tumor mesenchymal invasive program. In Drosophila, however, loss-‐of-‐function mutant of RAB5 transforms imaginal disc epithelia into highly proliferative tissues, pointing to a tumor suppressor function.
To dissect the complex role of RAB5A in tumor development, we investigated its impact on MCF-10A, an immortalized non-‐transformed mammary epithelial cell line that mimics morphogenesis of mammary gland when culture on 3D reconstituted basement membrane. We generated inducible MCF-‐10A cells expressing either RAB5A-WT or its dominant negative form (RAB5A-S34N). We found that the expression of RAB5A-S34N is sufficient to sustain MCF-10A cells proliferation in the absence of EGF, through the secretion of a diffusible growth-‐ promoting factor. Conversely, the expression of RAB5A-WT delayed cell cycle progression of cells grown in 2D, albeit it promoted the formation of hyperproliferative acini when grown in 3D. Thus, RAB5A may either be implicated in growth factor independent growth, or may promote proliferation in 3D.
Both clinical data and in vitro studies demonstrated that RAB5A is required for invasion and metastasis, suggesting its involvement in tumor progression. To further explore this latter role, we tested MCF-10A cells motility. We demonstrated that RAB5A expression does not affect single cell migration, but specifically enhances collective locomotion. Indeed, RAB5A-expression promotes increased coordination and coherence of epithelial cell sheet motility, related both to the increase in the area and persistence of cell protrusions at the leading front, and possibly to a tightening of cell-‐cell contacts.
We are currently dissecting the molecular mechanisms through which RAB5A altered function or expression impact on both mammary gland morphogenesis and tumor progression.
To dissect the complex role of RAB5A in tumor development, we investigated its impact on MCF-10A, an immortalized non-‐transformed mammary epithelial cell line that mimics morphogenesis of mammary gland when culture on 3D reconstituted basement membrane. We generated inducible MCF-‐10A cells expressing either RAB5A-WT or its dominant negative form (RAB5A-S34N). We found that the expression of RAB5A-S34N is sufficient to sustain MCF-10A cells proliferation in the absence of EGF, through the secretion of a diffusible growth-‐ promoting factor. Conversely, the expression of RAB5A-WT delayed cell cycle progression of cells grown in 2D, albeit it promoted the formation of hyperproliferative acini when grown in 3D. Thus, RAB5A may either be implicated in growth factor independent growth, or may promote proliferation in 3D.
Both clinical data and in vitro studies demonstrated that RAB5A is required for invasion and metastasis, suggesting its involvement in tumor progression. To further explore this latter role, we tested MCF-10A cells motility. We demonstrated that RAB5A expression does not affect single cell migration, but specifically enhances collective locomotion. Indeed, RAB5A-expression promotes increased coordination and coherence of epithelial cell sheet motility, related both to the increase in the area and persistence of cell protrusions at the leading front, and possibly to a tightening of cell-‐cell contacts.
We are currently dissecting the molecular mechanisms through which RAB5A altered function or expression impact on both mammary gland morphogenesis and tumor progression.
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