Endoplasmic reticulum-targeted delivery of celastrol and PD-L1 siRNA for reinforcing immunogenic cell death and potentiating cancer immunotherapy

The prospect of employing chemoimmunotherapy targeted towards the endoplasmic reticulum(ER)presents an opportunity to amplify the synergistic effects of chemotherapy and immunotherapy.In this study,we initially validated celastrol(CEL)as an inducer of immunogenic cell death(ICD)by promoting ER stress and autophagy in colorectal cancer(CRC)cells.Subsequently,an ER-targeted strategy was posited,involving the codelivery of CEL with PD-L1 small interfering RNAs(siRNA)using KDEL peptide-modified exosomes derived from milk(KME),to enhance chemoimmunotherapy outcomes.Our findings demonstrate the efficient transportation of KME to the ER via the Golgi-to-ER pathway.Compared to their non-targeting counterparts,KME exhibited a significant augmentation of the CEL-induced ICD effect.Additionally,it facilitated the release of danger signaling molecules(DAMPs),thereby stimulating the antigen-presenting function of dendritic cells and promoting the infiltration of T cells into the tumor.Concurrently,the ER-targeted delivery of PD-L1 siRNA resulted in the downregulation of both intracellular and membrane PD-L1 protein expression,consequently fostering the proliferation and activity of CD8^(+)T cells.Ultimately,the ER-targeted formulation exhibited enhanced anti-tumor efficacy and provoked anti-tumor immune responses against orthotopic colorectal tumors in vivo.Collectively,a robust ER-targeted delivery strategy provides an encouraging approach for achieving potent cancer chemoimmunotherapy.

Phomaketals A and B,pentacyclic meroterpenoids from a eupC overexpressed mutant strain of Phoma sp.

Phomaketals A(1)and B(2),two tropolonic meroterpenoids with the unprecedented pentacyclic skeletons,were isolated from the solid-substrate fermentation cultures of a eupC overexpressed mutant strain of the fungus Phoma sp.,together with a biogenetically related secondary metabolite pughiinin B(3),and the known one noreupenifeldin B(4).The structures of 1–3 were elucidated primarily by nuclear magnetic resonance(NMR)experiments.The absolute configurations of 1 and 2 were assigned by electronic circular dichroism calculations and the calculated NMR with DP4+analysis,while that of 3 was established by single-crystal X-ray diffraction analysis using Cu Kαradiation.Biogenetically,phomaketals A(1)and B(2)could be derived from the hypothetical tropolonic sesquiterpene intermediates neosetophomone B(6)and 9-R-neosetophomone B(6),respectively,via different reactions cascades.Compound 1 showed antiproliferative effect only against the SUPB15 cells,with an 50%inhibitory concentration(IC50)value of 4.85μmol/L,while the co-isolated known meroterpenoid 4 displayed potent effects against three tumor cell lines,SUPB15,EL4,and H9,showing IC50values of 0.36–27.08μmol/L.

Synthesis of 2,3-Diaminoindoles via a Copper-Iodine Co-catalytic Strategy

A one-pot synthesis of vicinal diamines using indoles,azoles and phenothiazines in a tandem multi-component reaction is developed.The utilization of a copper-iodine co-catalytic system enables the generation of a diverse range of vicinal diaminoindoles with good selectivity and moderate to good yields.An attractive aspect of this method is that it can be conducted under mild and environmentally friendly conditions,showcasing its potential as an alternative approach for synthesizing vicinal diamines.Moreover,the use of a multicomponent tandem reaction highlights the power and versatility of such strategies in synthetic chemistry.

Deciphering the Origin and Formation of Aminopyrrole Moiety in Kosinostatin Biosynthesis

Kosinostatin(KST)contains an uncommon aminopyrrole moiety,whose biosynthesis has remained elusive.Herein,aminopyrrolinic acid,which was generated by an L-ectoine synthase-like enzyme KstB3 via cyclization of L-glutamine,was identified to be the real substrate of adenylation enzyme KstB1.Subsequently,a FAD-dependent dehydrogenase KstB4 along with a transglutaminase-like enzyme KstB6 were also involved in formation of aminopyrrole.These results provided an unusual pathway for 2-aminopyrrole formation in KST biosynthesis.