Gadolinium borate and iron oxide bioconjugates: Nanocomposites of next generation with multifunctional applications.

The systematic investigations concerning the bioconjugation of GdBO3-Fe3O4 nanocomposite and their in vitro biocompatibility with cancer cell lines are reported. The nanocomposites were prepared hydrothermally from magnetite (Fe3O4), borax or boric acid and a Gd3+ salt. Bioconjugation processes were performed with citric acid and fluorescein isothiocyanate-doped silica, followed by the treatment with folic acid. Overall, the procedure involved "bare or PEGylated Fe3O4 as the magnetic core" and "vaterite- or triclinic-type of GdBO3 as the surface borate layer" for comparative evaluation of the results. The successful vectorization of the nanocomposite particles was demonstrated by quantitative and qualitative analytical data. All bioconjugates displayed soft ferromagnetic properties and negative zeta potential values that are appropriate for biological applications. The 10B and 157Gd contents were ca. 1014 atom/µg making them promising agents for BNCT, GdNCT and the combined GdBNCT. The Gd/Fe molar ratios (0.27-0.63) provided the capability for T1- or dual (T1 + T2) magnetic resonance imaging (MRI). In vitro studies were conducted to investigate the efficiency of targeted FA-conjugated versus non-FA conjugated nanoformulations on Mia-Pa-Ca-2, HeLa and A549 cells. Fluorescence microscopy and flow cytometry data unveiled the essential role of the zeta potential competing with folate targeting in the uptake mechanism. The bioconjugated nanoplatforms of GdBO3-Fe3O4 composite, introduced herein, proved to have potential features of next generation agents for magnetically targeted therapy, fluorescence imaging, magnetic resonance imaging/diagnosis and Neutron Capture Therapy.

Novel Molecular Mechanism of Regulation of CD40 Ligand by the Transcription Factor GLI2.

The interaction between tumor cells and their surrounding microenvironment is essential for the growth and persistence of cancer cells. This interaction is mediated, in part, by cytokines. Although the role of cytokines in normal and malignant cell biology is well established, many of the molecular mechanisms regulating their expression remain elusive. In this article, we provide evidence of a novel pathway controlling the transcriptional activation of CD40L in bone marrow-derived stromal cells. Using a PCR-based screening of cytokines known to play a role in the biology of bone marrow malignancies, we identified CD40L as a novel GLI2 target gene in stromal cells. CD40L plays an important role in malignant B cell biology, and we found increased Erk phosphorylation and cell growth in malignant B cells cocultured with CD40L-expressing stromal cells. Further analysis indicated that GLI2 overexpression induced increased CD40L expression, and, conversely, GLI2 knockdown reduced CD40L expression. Using luciferase and chromatin immunoprecipitation assays, we demonstrate that GLI2 directly binds and regulates the activity of the CD40L promoter. We found that the CCR3-PI3K-AKT signaling modulates the GLI2-CD40L axis, and GLI2 is required for CCR3-PI3K-AKT-mediated regulation of the CD40L promoter. Finally, coculture of malignant B cells with cells stably expressing human CD40L results in increased Erk phosphorylation and increased malignant B cell growth, indicating that CD40L in the tumor microenvironment promotes malignant B cell activation. Therefore, our studies identify a novel molecular mechanism of regulation of CD40L by the transcription factor GLI2 in the tumor microenvironment downstream of CCR3 signaling.