Estradiol (E2) regulates several cellular functions through the interaction with estrogen receptor subtypes, ERα and ERβ, which present different functional and regulation properties. ER subtypes have been identified in human astrocytomas, the most common and aggressive primary brain tumors. We studied the role of ER subtypes in cell growth of two human astrocytoma cell lines derived from tumors of different evolution grades: U373 and D54 (grades III and IV, respectively). E2 significantly increased the number of cells in both lines and the co-administration with an ER antagonist (ICI 182, 780) significantly blocked E2 effects. ERα was the predominant subtype in both cell lines. E2 and ICI 182, 780 down-regulated ERα expression. The number of U373 and D54 cells significantly increased after PPT (ERα agonist) treatment but not after DPN (ERβ agonist) one. To determine the role of SRC-1 and SRC-3 coactivators in ERα induced cell growth, we silenced them with RNA interference. Coactivator silencing blocked the increase in cell number induced by PPT. The content of proteins involved in proliferation and metastasis was also determined after PPT treatment. Western blot analysis showed that in U373 cells the content of PR isoforms (PR-A and PR-B), EGFR, VEGF and cyclin D1 increased after PPT treatment while in D54 cells only the content of EGFR was increased. Our results demonstrate that E2 induces cell growth of human astrocytoma cell lines through ERα and its interaction with SRC-1 and SRC-3 and also suggest differential roles of ERα on cell growth depending on astrocytoma grade.

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The use of micrometric hollow silica spheres is described as a strategy to reduce magnetic field inhomogeneities in the context of NMR chromatography. When employed as a stationary phase, hollow silica microspheres allow the use of common solution-state NMR instruments to measure the diffusion coefficient perturbation induced by the interaction of the analytes with the silica surface.

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In a search for novel vitamin D derivatives of potential therapeutic value, structurally simple but synthetically challenging A-ring epimers of the 19-nor-Calcitriol [19-nor-1α,25-(OH)2-D3] at C1 and C3 were efficiently synthesized. Both analogues (1-epi-and 3-epi-19-nor-Calcitriol) were obtained through a convergent synthesis starting from cis,cis-1,3,5-cyclohexanetriol and the protected 25-hydroxy Grundmann´s ketone. After Julia-Kocienski coupling of the corresponding C,D-ring/side chain sulfone fragment with the A-ring ketone moiety, both vitamin D analogues were isolated. The critical point was how to determine the structural configuration of both diastereoisomers since similar 1 H NMR spectra were observed. For that, a biocatalytic approach was crucial in the synthesis of orthogonally protected derivatives. NMR spectroscopy allows the unambiguous identification of these compounds and as a result the structural elucidation of the desired vitamin D diastereomeric analogues. Affinity studies demonstrated that these 1,25-19-nor analogues have a very low affinity for the vitamin D receptor compared with 1α,25-dihydroxyvitamin D3 or 1α,25-dihydroxy-19nor-vitamin D3. In addition, these analogues have a lower binding affinity for the human vitamin D binding protein than the natural hormone. In vitro cell culture studies revealed that synthesized analogues were less active than 1α,25-dihydroxyvitamin D3 in inhibiting cell proliferation.