Alkaline phosphatase

About: Alkaline phosphatase is a research topic. Over the lifetime, 20218 publications have been published within this topic receiving 540547 citations. The topic is also known as: Alkaline_phosphatase & IPR001952.

Effects of Steroid Hormones and Antisteroids on Alkaline Phosphatase Activity in Human Endometrial Cancer Cells (Ishikawa Line)

Abstract: Alkaline phosphatase activity in human endometrial cancer cells of the estrogen-responsive Ishikawa line was markedly stimulated (3-20-fold in 4 days) by estrogens, 5 alpha-dihydrotestosterone, and dehydroepiandrosterone but not by testosterone, medroxyprogesterone acetate, glucocorticoids, several peptide hormones, prostaglandins, or growth factors. Maximum responses to estradiol were obtained at concentrations between 10(-9) and 10(-7) M; at 10(-8) M estradiol, the highest activity was reached 48-72 h after addition of the hormone. A linear relationship between enzyme activity at 48 h and the length of exposure to the hormone was observed. Dibutyryl cyclic guanosine 3':5'-monophosphate, but not dibutyryl cyclic adenosine 3':5'-monophosphate enhanced alkaline phosphatase activity and acted synergistically with estradiol. trans-4-Monohydroxytamoxifen completely antagonized the stimulatory effect of estradiol and had no agonistic activity. Dihydrotestosterone and dehydroepiandrosterone appear to exert their effects, at least in part, by interacting with estrogen receptors, since the simultaneous presence in the medium of monohydroxytamoxifen abolished their influence on alkaline phosphatase activity. The specific antiandrogen monohydroxyflutamide partially antagonized the effect of these hormones, suggesting that their action involved androgenic mechanisms as well. Exposure to elevated temperature and to specific inhibitors identified alkaline phosphatase of Ishikawa cells as a placental-type isoenzyme, thus contrasting with the nonplacental type found in glandular epithelial cells of normal endometrium and in another human endometrial cancer cell line, HEC-50. This study extends our previous observations of estrogen responsiveness in the Ishikawa cell line. In addition to the previously reported stimulatory effects on growth and progesterone receptor levels, we are now describing the stimulation by estrogens and C19 steroids of an enzyme, alkaline phosphatase, which can be used as a convenient end point to examine mechanisms of hormonal action.

Two cell lines from bone marrow that differ in terms of collagen synthesis, osteogenic characteristics, and matrix mineralization.

Abstract: Two cloned cell lines were isolated from cultures of mouse bone-marrow cells. One of the lines, D1, exhibited osteogenic properties and synthesized type-I collagen (alpha 1)2 alpha 2. The second cell line, D2, was not osteogenic and produced a collagen homotrimer (alpha 1)3. Whereas the extracellular matrix of the D1 cell cultures contained striated collagen fibrils, presumably composed of type-I collagen, the homotrimer-producing D2 cells did not demonstrate striated collagen fibrils. Instead, they had thin filaments without detectable striations. Sodium ascorbate stimulated collagen synthesis at the transcriptional level in both the D1 and the D2 cells. The bone-producing characteristics of D1 in vitro included high levels of alkaline phosphatase, increased cyclic adenosine monophosphate on treatment with parathyroid hormone, and expression of osteocalcin mRNA. The D1 cells, unlike the D2 cells, produced a mineralized matrix in vitro. Mineralization in the cultures of the D1 cells occurred in nodules of increased cell density, which also contained the cells with the highest concentrations of collagen mRNA, as shown by in situ hybridization. When the D1 cells were implanted in a diffusion chamber in vivo, a mixture of both osteogenic and adipogenic tissues was formed. This indicates that the D1 cell line is derived from an early marrow stromal precursor that is multipotential.