Evaluation of the Pharmacokinetics of the Pancreastatin Inhibitor PSTi8 Peptide in Rats: Integration of In Vitro and In Vivo Findings

PSTi8 is a pancreastatin inhibitory peptide that is effective in the treatment of diabetic models. This study investigates the pharmacokinetic (PK) properties of PSTi8 in Sprague Dawley rats, for the first time. In vitro and in vivo PK studies were performed to evaluate the solubility, stability in plasma and liver microsomes, plasma protein binding, blood–plasma partitioning, bioavailability, dose proportionality, and gender difference in PK. Samples were analyzed using the validated LC-MS/MS method. The solubility of PSTi8 was found to be 9.30 and 25.75 mg/mL in simulated gastric and intestinal fluids, respectively. The protein binding of PSTi8 was estimated as >69% in rat plasma. PSTi8 showed high stability in rat plasma and liver microsomes and the blood–plasma partitioning was >2. The bioavailability of PSTi8 after intraperitoneal and subcutaneous administration was found to be 95.00 ± 12.15 and 78.47 ± 17.72%, respectively, in rats. PSTi8 showed non-linear PK in dose proportionality studies, and has no gender difference in the PK behavior in rats. The high bioavailability of PSTi8 can be due to high water solubility and plasma protein binding, low clearance and volume of distribution. Our in vitro and in vivo findings support the development of PSTi8 as an antidiabetic agent.

Comparative assessment of clinical trials, indications, pharmacokinetic parameters and side effects of approved platinum drugs

Platinum complexes are among the most commonly applied anticancer agents. The aim of current work is collection, analysing and comparative estimation of clinical trials and pharmacological indications of currently approved for application platinum detivatives: Cisplatin, Carboplatin, Oxaliplatin, Nedaplatin (Japan), Lobaplatin (China), Heptaplatin (North Korea), and Satraplatin. The other aim of the study includes the summarizing of the hystoric data for the stages of the developlement of these drugs, and the comparison of pharmacokimetic parameters, side effecs and the dose-liniting factors of the drugs. The observational study on pharmacokinetic parameters shows that protein binding decreases in order: 95% (Cisplatn); 90% (Oxaliplatin); 50% (Nedaplatin); low (Carboplatin). For every of Cisplatin, Carboplatin, Oxaliplatin have been reported more than 1000 clinical trials; for Lobaplatin, Nedaplatin, Satraplatin - about 10 trials. The differenses in dose-limiting effects are: neuro-, nephro-, ototoxicity (Cisplatin); neurotoxicity (Oxaliplatin); nephrotoxicity (Heptaplatin); myelosuppression: thrombocytopenia, neutropenia, leukopenia (Carboplatin, Nedaplatin, Satraplatin).

A4GALT Mediated the Glycosylation of B7-H3 in Human Colorectal Cancer Cell Lines

B7-H3 is one of the most important members of the B7/CD28 family, and its expression level is abnormally high in a variety of tumors. B7-H3 inhibits T cell activation via binding to the corresponding receptors on T cells, thereby mediating tumor immune escape. Glycosylation is a common post-translational modification of proteins, which plays an essential role in protein expression patterns and biological functions. Current evidence has shown that the abnormal glycosylation of B7-H3 in tumors is of great significance for protein expression and ligand-receptor binding. Therefore, in-depth exploration of the underlying mechanism of glycosylation modification of B7-H3 is expected to provide new insights for tumor immunotherapy. To investigate the underlying mechanism of glycosyltransferase-mediated glycosylation of B7-H3. Firstly, the CHIPBase database was used to screen glycosyltransferases with a high correlation with the protein expression of B7-H3. Then their siRNAs were designed and synthesized to transfect into cells, and the western blotting assay was performed for further screening. Secondly, the siRNA and overexpression plasmid of the screened glycosyltransferase were respectively transfected into cells to verify the effect on the expression level of B7-H3. Thirdly, the effect of glycosyltransferase on the expression level of B7-H3 was explored by changing its substrate level. Finally, the co-immunoprecipitation experiment was conducted to verify whether protein binding existed between B7-H3 and the glycosyltransferase. The glycosyltransferase called A4GALT had the highest correlation with the protein expression of B7-H3. After knocking down or overexpressing A4GALT, the protein expression level of B7-H3 both changed significantly. When knocked down GALT to reduce the galactosyl donors, B7-H3 was significantly down-regulated. And B7-H3 was up-regulated while increasing the galactose in the medium. In addition, the Co-immunoprecipitation experiment proved that there was protein binding between B7-H3 and A4GALT. A4GALT can positively regulate the expression of B7-H3, and changing the level of galactosyl donors can also positively regulate the expression of B7-H3. There is a protein interaction between A4GALT and B7-H3.

Harnessing the Intrinsic Photochemistry of Isoxazoles for the Development of Chemoproteomic Crosslinking Methods

Photo-crosslinking is a powerful technique for identifying both coarse- and fine-grained information on protein binding by small molecules. However, the scope of useful functional groups remains limited, with most studies focusing on diazirine, aryl azide, or benzophenone-containing molecules. Here, we report a unique method for photo-crosslinking, employing the intrinsic photochemistry of the isoxazole, a common heterocycle in medicinal chemistry, to offer an alternative to existing strategies using more perturbing, extrinsic crosslinkers. In this initial report, this technique is applied both in vitro and ex vivo, used in a variety of common chemoproteomic workflows, and validated across multiple proteins, demonstrating the utility of isoxazole photo-crosslinking in a wide range of biologically relevant experiments.