Influence of the tyrosine kinase inhibitors STI571 (Glivec), lavendustin A and genistein on human mast cell line (HMC-1(560)) activation

C-kit mutations determine dasatinib mechanism of action in HMC-1 neoplastic mast cells: dasatinib differently regulates PKCδ translocation in HMC-1(560) and HMC-1(560,816) cell lines

PURPOSE

The second generation of tyrosine kinase inhibitors is a group of compounds that inhibit c-kit receptor activity and therefore widely used in the treatment of mastocytosis. In this research, the relationship between the mechanism of action of tyrosine kinase inhibitors and protein kinase C is investigated in HMC-1(560) or HMC-1(560,816) cell lines.

RESULTS

From all the tyrosine kinase inhibitors tested, nilotinib is the compound that has the highest cytotoxic effect against HMC-1(560) mast cell line, while midostaurin is the most potent in HMC-1(560,816). Moreover, an increase on histamine release is observed after protein kinase C activation either in HMC-1(560) or HMC-1(560,816) cells. Furthermore, dasatinib increases histamine release in both mast cell lines, which could be related with the secondary reactions previously described in dasatinib-treated patients. Dasatinib also induces Ca(2+)-dependent protein kinase C isoforms translocation from the cytosol to the membrane, whereas protein kinase Cδ is translocated from the cytosol to the nucleus in the HMC-1(560,816) cell line, but not in HMC-1(560) cells.

CONCLUSION

Results obtained demonstrate that dasatinib induces an important cytotoxic effect in both HMC-1 cell lines and differently regulates protein kinase Cδ in HMC-1(560) and HMC-1(560,816) cells. Finally, our results confirm that PKCδ is an essential target for dasatinib.

Soy extracts suppressed iodine uptake and stimulated the production of autoimmunogen in rat thyrocytes

Soy consumption is associated with thyroid disorders such as hypothyroidism, goiter, and autoimmune thyroid disease (ATD) as well as increased iodine requirement in certain cases. However, the anti-thyroid component(s) in soy are yet to be identified and the molecular mechanism(s) involved remain unclear. This study examined the effects of soy isoflavones (ISF) on iodide uptake and expression of thyroglobulin (Tg) and sodium/iodide symporter (NIS) in thyrocytes. Fischer rat thyroid cells (FRTL) were treated with Novasoy (a soy alcohol extract containing 30% ISF) or major ISF aglycones or glycosides for 24 h. Iodide uptake was measured by a colorimetric assay. The protein level of Tg and NIS was measured by Western blotting. Cytotoxicity of tested compounds was determined by the MTT cell proliferation assay. Iodide uptake in FRTL cells was dose-dependently suppressed by Novasoy added into the cell culture (10, 25, or 50 µg/mL, P < 0.05). However, neither the major ISF aglycones nor glycosides alone or in combination had similar effects. Novasoy (up to 200 µg/mL) had no cytotoxic effect. Novasoy (1, 10, and 50 µg/mL) and genistein (1 and 10 µM) markedly increased the protein content of a 40 kDa Tg fragment (P40, a known autoimmunogen) and non-glycosylated NIS in the FRTL cells (P < 0.05). Overall, this study demonstrated that the alcohol soluble component(s) other than the major ISF in soy remarkably inhibited iodide uptake in the FRTL cells. Soy ISF, particularly genistein, induced the production of P40, which might be responsible for the higher incidence of ATD reported in soy infant formula-fed children.

Regulation of the immune response by soybean isoflavones

Soybeans are rich in immuno-modulatory isoflavones such as genistein, daidzein, and glycitein. These isoflavones are well-known antioxidants, chemopreventive and anti-inflammatory agents. Several epidemiological studies suggest that consumption of traditional soy food containing isoflavones is associated with reduced prevalence of chronic health disorders. Isoflavones are considered to be phytoestrogens because of their ability to bind to estrogen receptors. The literature is extensive on the chemistry, bio-availability, and bio-activity of isoflavones. However, their effects on immune response are yet to be fully understood, but are beginning to be appreciated. We review the role of isoflavones in regulation of the immune response and their potential clinical applications in immune-dysfunction. Special emphasis will be made regarding in vivo studies including humans and animal model systems.

Spiperone, identified through compound screening, activates calcium-dependent chloride secretion in the airway

Cystic fibrosis (CF) is caused by mutations in the gene producing the cystic fibrosis transmembrane conductance regulator (CFTR). CFTR functions as a Cl(-) channel. Its dysfunction limits Cl(-) secretion and enhances Na+ absorption, leading to viscous mucus in the airway. Ca2+-activated Cl(-) channels (CaCCs) are coexpressed with CFTR in the airway surface epithelia. Increases in cytosolic Ca(2+) activate the epithelial CaCCs, which provides an alternative Cl(-) secretory pathway in CF. We developed a screening assay and screened a library for compounds that could enhance cytoplasmic Ca2+, activate the CaCC, and increase Cl(-) secretion. We found that spiperone, a known antipsychotic drug, is a potent intracellular Ca2+ enhancer and demonstrated that it stimulates intracellular Ca2+, not by acting in its well-known role as an antagonist of serotonin 5-HT2 or dopamine D2 receptors, but through a protein tyrosine kinase-coupled phospholipase C-dependent pathway. Spiperone activates CaCCs, which stimulates Cl(-) secretion in polarized human non-CF and CF airway epithelial cell monolayers in vitro and in CFTR-knockout mice in vivo. In conclusion, we have identified spiperone as a new therapeutic platform for correction of defective Cl(-) secretion in CF via a pathway independent of CFTR.

Soybeans as a phytochemical reservoir for the production and stabilization of biocompatible gold nanoparticles

The present study demonstrates an unprecedented green process for the production of gold nanoparticles by simple treatment of gold salts with soybean extracts. Reduction capabilities of antioxidant phytochemicals present in soybean and their ability to reduce gold salts chemically to nanoparticles with subsequent coating of proteins and a host of other phytochemicals present in soybean on the freshly generated gold nanoparticles are discussed. The new genre of green nanoparticles exhibit remarkable in vitro stability in various buffers including saline, histidine, HSA, and cysteine solutions. MTT assays reveal that the green gold nanoparticles are nontoxic and thus provide excellent opportunities for their applications in nanomedicine for molecular imaging and therapy. The overall strategy described herein for the generation of gold nanoparticles meets all 12 principles of green chemistry, as no "man-made" chemicals, other than the gold salts, are used in the green nanotechnological process.