Sprouty4 at the crossroads of Trk neurotrophin receptor signaling suppression by glucocorticoids.

Glucocorticoids (GC) affect neuronal plasticity, development and function of the nervous system by inhibiting neurotrophin-induced Trk signaling. It has been established that pretreatment with dexamethasone (DEX) restricts Neurotrophin-induced neurite outgrowth by inhibiting Trk-dependent activation of Ras-Erk1/2 signaling pathways. However, the precise molecular mechanism through which DEX interferes with neurotrophin signaling and Trk-mediated neurite outgrowth has not been clearly defined yet. Here, we observed that in PC12 cells DEX treatment promotes the transcription of Sprouty4, a regulatory molecule that is part of a negative feedback module that specifically abrogates Ras to Erk1/2 signaling in response to NGF. In line with this, either knockdown of Sprouty4 or overexpression of a dominant negative form of Sprouty4 (Y53A), rescue the inhibition of NGF/TrkA-promoted neurite outgrowth and Erk1/2 phosphorylation induced by DEX. Likewise, treatment of hippocampal neurons with DEX induces the expression of Sprouty4 and its knockdown abrogates the inhibitory effect of DEX on primary neurite formation, dendrite branching and Erk1/2 activation induced by BDNF. Thus, these results suggest that the induction of Sprouty4 mRNA by DEX translates into a significant inhibition of Trk to Erk1/2 signaling pathway. Together, these findings bring new insights into the crosstalk between DEX and neurotrophin signaling and demonstrate that Sprouty4 mediates the inhibitory effects of DEX on neurotrophin function.

Rational Identification of Hsp90 Inhibitors as Anticancer Lead Molecules by Structure Based Drug Designing Approach.

BACKGROUND: Heat shock protein 90 (Hsp90) is an encouraging anticancer target for the development of clinically significant molecules. Schiff bases play a crucial role in anticancer research because of their ease of synthesis and excellent antiproliferative effect against multiple cancer cell lines. Therefore, we started our research work with the discovery of resorcinol/4-chloro resorcinol derived Schiff bases as Hsp90 inhibitors, which resulted in the discovery of a viable anticancer lead molecule. OBJECTIVE: The objective of the study is to discover more promising lead molecules using our previously established drug discovery program, wherein the rational drug design is achieved by molecular docking studies. METHODS: The docking studies were carried out by using Surflex Geom X programme of Sybyl X-1.2 version software. The molecules with good docking scores were synthesized and their structures were confirmed by IR, 1H NMR and mass spectral analysis. Subsequently, the molecules were evaluated for their potential to attenuate Hsp90 ATPase activity by Malachite green assay. The anticancer effect of the molecules was examined on PC3 prostate cancer cell lines by utilizing 3-(4,5-dimethythiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay methodology. RESULTS: Schiff bases 11, 12, 20, 23 and 27 exhibiting IC50 value below 1µM and 15µM, in malachite green assay and MTT assay, respectively, emerged as viable lead molecules for future optimization. CONCLUSION: The research work will pave the way for the rational development of cost-effective Schiff bases as Hsp90 inhibitors as the method employed for the synthesis of the molecules is simple, economic and facile.

Fe3 O4 nanoparticles mediated synthesis of novel spirooxindole-dihydropyrimidinone molecules as Hsp90 inhibitors.

Heat shock protein 90 (Hsp90) is a validated molecular chaperone considered as the new key recipient for cancer intervention. The current study illustrates the synthesis of novel spirooxindole-dihydropyrimidinones (4a-j) by Fe3 O4 nanoparticles intervened synthesis and their Hsp90 ATPase inhibitory activity was investigated by the malachite green assay. All the compounds in the study demonstrated a moderate to potent ATPase inhibitory profile, with IC50 values ranging from 0.18 to 6.80 µM. Compounds 4j, 4h, 4f, and 4i exhibited maximum inhibitory potential with IC50 values of 0.18, 0.20, 0.35, and 0.55 µM, respectively. They were found to be better than the standard drug, geldanamycin (Hsp9 ATPase inhibition IC50 = 0.90 µM). Compounds 4h and 4j with IC50 values of 22.82 ± 0.532, 20.78 ± 0.234 and 21.32 ± 0.765, 28.43 ± 0.653 µM showed significantly greater potencies against the MCF-7 and HepG2 cell lines, respectively. Compound 4j showed good antioxidant activities in the DPPH test and H2 O2 assay (IC50 = 20.13.23 ± 0.32 and 23.27 ± 0.32 µg/mL) when compared with the standard ascorbic acid (IC50 = 19.16 ± 0.20 and 20.66 ± 1.09 µg/mL). A molecular docking study was performed to observe the binding efficiency and steric interactions of the lead moiety.