Remodeling of the lymphatic vasculature during mouse mammary gland morphogenesis is mediated via epithelial-derived lymphangiogenic stimuli.
Despite the key roles of lymphatic vessels in homeostasis and disease, the cellular sources of signals that direct lymphatic vascular growth and patterning remain unknown. Using high-resolution imaging in two and three dimensions, we demonstrated that postnatal mouse mammary gland lymphatic vessels share an intimate spatial association with epithelial ducts and large blood vessels. We further demonstrated that the lymphatic vasculature is remodeled together with the mammary epithelial tree and blood vasculature during postnatal mouse mammary gland morphogenesis. Neither estrogen receptor α nor progesterone receptor were detected in lymphatic endothelial cells in the mouse mammary gland, suggesting that mammary gland lymphangiogenesis is not likely regulated directly by these steroid hormones. Epithelial cells, especially myoepithelial cells, were determined to be a rich source of prolymphangiogenic stimuli including VEGF-C and VEGF-D with temporally regulated expression levels during mammary gland morphogenesis. Blockade of VEGFR-3 signaling using a small-molecule inhibitor inhibited the proliferation of primary lymphatic endothelial cells promoted by mammary gland conditioned medium, suggesting that lymphangiogenesis in the mammary gland is likely driven by myoepithelial-derived VEGF-C and/or VEGF-D. These findings provide new insight into the architecture of the lymphatic vasculature in the mouse mammary gland and, by uncovering the proximity of lymphatic vessels to the epithelial tree, suggest a potential mechanism by which metastatic tumor cells access the lymphatic vasculature.
Division of Haematology, Centre for Cancer Biology, SA Pathology, Adelaide, Australia.
Kelly L
KL
Betterman
Sophie
S
Paquet-Fifield
Marie-Liesse
ML
Asselin-Labat
Jane E
JE
Visvader
Lisa M
LM
Butler
Steven A
SA
Stacker
Marc G
MG
Achen
Natasha L
NL
Harvey
D000818:Animals; D000831:Animals, Newborn; D001808:Blood Vessels / Q000166:cytology / Q000254:growth & development / Q000378:metabolism; D049109:Cell Proliferation; D042783:Endothelial Cells / Q000166:cytology / Q000378:metabolism; D004848:Epithelium / Q000254:growth & development* / Q000378:metabolism*; D047628:Estrogen Receptor alpha / Q000378:metabolism; D005260:Female; D018507:Gene Expression Regulation, Developmental; D042583:Lymphangiogenesis; D042601:Lymphatic Vessels / Q000166:cytology / Q000378:metabolism*; D008321:Mammary Glands, Animal / Q000166:cytology / Q000254:growth & development* / Q000378:metabolism*; D051379:Mice; D008810:Mice, Inbred C57BL; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D011980:Receptors, Progesterone / Q000378:metabolism; D013997:Time Factors; D042643:Vascular Endothelial Growth Factor D / Q000235:genetics / Q000378:metabolism; D040321:Vascular Endothelial Growth Factor Receptor-3 / Q000378:metabolism
D047628:Estrogen Receptor alpha; D012333:RNA, Messenger; D011980:Receptors, Progesterone; D042643:Vascular Endothelial Growth Factor D; D040321:Vascular Endothelial Growth Factor Receptor-3