Vanadate disrupts mammary gland development in whole organ culture

Abstract

Protein tyrosine kinases and phosphatases are signaling molecules involved in all aspects of development, including proliferation, differentiation, and apoptosis. How disruption of protein tyrosine phosphatase affects mammary gland development is not entirely clear. We examined the effects of sodium vanadate, which is known to primarily inhibit tyrosine phosphatases, in mouse mammary gland development in whole organ culture. Mammary epithelial differentiation was effectively inhibited by vanadate in a dosedependent manner as indicated by lack of epithelial alveoli compared to the contralateral nontreated gland controls. Mammary glands in the differentiation medium after four days in the presence of vanadate did not differentiate into alveoli. Instead, they exhibited prominent terminal end buds and lost the distinctive epithelial structures. The inhibitory effect of vanadate on mammary epithelial cell differentiation was irreversible after one day of treatment. Immunohistochemical staining for PCNA (Proliferating Cell Nuclear Antigen) showed that vanadate-treated glands exhibited elevated proliferation signals in the differentiation medium. Expression of ␤-casein protein in the vanadate-treated glands decreased dramatically and progressively. Short-term exposure (up to 72 hours) of mammary glands to vanadate resulted in an increase in mammary epithelial cell density and loss of organization of the mammary structures. TUNEL assay of mammary glands with prolonged exposure to vanadate revealed widespread apoptosis. Furthermore, some cells were still proliferating or expressing ␤-casein after prolonged exposure to vanadate. Taken together, these data indicate that vanadate treatment blocks mammary epithelial cell differentiation and promotes abnormal proliferation and apoptosis, likely through the inhibition of protein tyrosine phosphatase-mediated signaling.

Vanadyl sulfate can differentially damage DNA in human lymphocytes and HeLa cells

“…At higher concentrations (greater than 10 )10 M) colony formation is inhibited (Hanauske et al 1987). The vanadate-mediated effect on cell proliferation is also time-dependent (Gallo-Hendrikx et al 2001). Short-term (1-2 days) exposure appears to increase cell numbers, whereas longer exposure to 50 lM vanadate leads to massive apoptosis of mammary epithelial cells.…”

“…On the one hand, vanadyl sulfate and orthovanadate can stimulate DNA synthesis in mammary glands (Hori and Oka 1980;Gallo-Hendrikx et al 2001), 3T3 and 3T6 cells (Smith 1983;Sheu et al 1992), and BALB/3T3 cells (Cortizo et al 1997). It seems that vanadium salts have biphasic effect on DNA synthesis and, by this way, on proliferation and differentiation.…”

Morphogenesis of epithelial tubes: Insights into tube formation, elongation, and elaboration

“…It is also possible to culture the entire epithelial organ (Sakai and Onodera, 2008), most notably in salivary gland (Larsen et al, 2003), kidney (Srinivas et al, 1999), lung (Bellusci et al, 1997), and mammary gland ( Topper et al, 1975; Gallo-Hendrikx et al, 2001). Since the epithelium is cultured in its normal stromal environment, development is often even more similar to normal in vivo development.…”