Connective Tissue Growth Factor (CTGF/CCN2) enhances lactogenic differentiation of mammary epithelial cells via integrin-mediated cell adhesion.
BACKGROUND
Connective Tissue Growth Factor (CTGF/CCN2), a known matrix-associated protein, is required for the lactogenic differentiation of mouse mammary epithelial cells. An HC11 mammary epithelial cell line expressing CTGF/CCN2 was constructed to dissect the cellular responses to CTGF/CCN2 that contribute to this differentiation program.


RESULTS
Tetracycline-regulated expression of CTGF/CCN2 in HC11 cells enhanced multiple markers of lactogenic differentiation including beta-casein transcription and mammosphere formation. In a separate measure of mammary differentiation the addition of CTGF/CCN2 to cultures of MCF10A cells increased the development of acini in vitro. In HC11 cells the elevated levels of CTGF/CCN2 diminished the requirement for extracellular matrix proteins in the activation of beta-casein transcription, indicating that CTGF/CCN2 contributed to lactogenic differentiation through the regulation of matrix dependent cell adhesion. CTGF/CCN2 expression in HC11 cells increased expression of extracellular matrix proteins and integrins, enhanced the formation of focal adhesion complexes, and increased survival signaling. In addition, HC11 cells adhered to immobilized CTGF/CCN2 and this was inhibited by function-blocking antibodies to the integrins alpha6 and beta1, and to a lesser degree by antibody to beta3 integrin.


CONCLUSIONS
CTGF/CCN2 expression in HC11 cells led to an increase in multiple markers of lactogenic differentiation. The mechanisms by which CTGF/CCN2 contributed to lactogenic differentiation include direct binding of CTGF/CCN2 to integrin complexes and CTGF/CCN2-induced matrix protein expression resulting in elevated integrin functionality.
Morrison
Bethanie L
BL
Department of Pathology, F, Edward Hebert School of Medicine, Uniformed Services University of Health Sciences, Bethesda, MD 20814, USA.
Jose
Cynthia C
CC
Cutler
Mary Lou
ML
D000818:Animals; D000911:Antibodies, Monoclonal / Q000494:pharmacology; D000943:Antigens, Differentiation / Q000096:biosynthesis* / Q000235:genetics; D002364:Caseins / Q000096:biosynthesis* / Q000235:genetics; D002454:Cell Differentiation; D045744:Cell Line, Tumor; D003001:Cloning, Molecular; D055513:Connective Tissue Growth Factor / Q000235:genetics / Q000378:metabolism*; D004847:Epithelial Cells / Q000187:drug effects / Q000378:metabolism* / Q000473:pathology; D005260:Female; D022001:Focal Adhesions / Q000187:drug effects; D039121:Integrin alpha6beta1 / Q000276:immunology / Q000378:metabolism*; D008321:Mammary Glands, Animal / Q000473:pathology; D051379:Mice; D015398:Signal Transduction / Q000187:drug effects; D019076:Transgenes / Q000235:genetics
D000911:Antibodies, Monoclonal; D000943:Antigens, Differentiation; D002364:Caseins; D039121:Integrin alpha6beta1; D055513:Connective Tissue Growth Factor