Calicheamicin y"is a potent antitumor antibiotic that cleaves DNA with a high degree of specificity; there is much interest in the recognition process. We have investigated the DNA-cleaving properties of calicheamicin T, a truncated derivative of calicheamicin. We show that calicheamicin T cleaves DNA in a double-stranded fashion, indicating that the first two sugars are sufficient to facilitate binding of the aglycone in the minor groove. However, calicheamicin T cleaves DNA nonselectively. This result suggests that cyclization kinetics do not determine the cleavage speiflcity of the intact drug. Instead, cleavage specificity probably reflects binding specificity. Because of the recognition sites reported in the original cleavage paper, calicheamicin has been assumed to recognize oligopyrimidine DNA sequences containing G-C base pailrs. We show here that calicheamicin also cuts efficiently at APT tracts, sometimes in preference to G-C-rich homopyrimidine tracts. Crystallographic data and experiments with chemical probes indicate that DNA sequences including GC base pairs have significantly different local conformations from DNA sequences containing several (four or more) sequential A-T base pairs. This difference makes it unlikely that calicheamicin simply senses inherent groove conformation and suggests that there is some degree of "induced fit." The ability to recognize both AFT-and G C-rich oligopyrimidine sequences with a high degree of specificity makes calicheamicin an unusual minor-groove binder.

Mounting evidence suggests that immunotherapies are a promising new class of anticancer therapies. However, the immunosuppressive tumor microenvironment (TME), poor immunogenicity, and off-target toxicity hinder the broader implementation of immunotherapies. Here, we describe a novel strategy combining chemotherapy and immunotherapy to modulate the TME by systemically and concurrently delivering the chemotherapeutic agent SN38 (7-ethyl-10-hydroxycamptothecin) and the STING agonist DMXAA (5,6-dimethylxanthenone-4-acetic acid) into tumors using triblock copolymer nanoparticles, named PS3D1@DMXAA, which enhances antigen cross-presentation and induces the conversion of the immunosuppressive TME to immunogenic TME through the newly found synergistic function between SN38 and STING activation. PS3D1@DMXAA thus shows potent therapeutic efficacy in three mice tumor models and elicits remarkable therapeutic benefit when combined with anti–PD-1 therapy. Our engineered nanosystem offers a rational design of an effective immunotherapy combination regimen to convert uninflamed “cold” tumors into “hot” tumors, addressing the major challenges immunotherapies faced.

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The 1,4-diyl (2) generated from calicheamicin 7/ (1, CLM) by reductive activation1•2 34and rearrangemen ****9t3•4 is believed to initiate DNA cleavage by hydrogen atom abstraction from both strands of the helix to give the reduced form of the drug, CLM e (3).

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Resveratrol, a polyphenol compound derived from various edible plants, protects against sepsis-induced acute kidney injury (AKI) via its anti-inflammatory activity, but the underlying mechanisms remain largely unknown. In this study, a rat model of sepsis was established by cecal ligation and puncture (CLP), 30 mg/kg resveratrol was intraperitoneally administrated immediately after the CLP operation. HK-2 cells treated by 1 μg/ml lipopolysaccharide, 0.2 μM tunicamycin, 2.5 mM irestatin 9389 and 20 μM resveratrol were used for in vitro study. The results demonstrated that resveratrol significantly improved the renal function and tubular epithelial cell injury and enhanced the survival rate of CLP-induced rat model of sepsis, which was accompanied by a substantial decrease of the serum content and renal mRNA expressions of TNF-α, IL-1β and IL-6. In addition, resveratrol obviously relieved the endoplasmic reticulum stress, inhibited the phosphorylation of inositol-requiring enzyme 1(IRE1) and nuclear factor-κB (NF-κB) in the kidney. In vitro studies showed that resveratrol enhanced the cell viability, reduced the phosphorylation of NF-κB and production of inflammatory factors in lipopolysaccharide and tunicamycin-induced HK-2 cells through inhibiting IRE1 activation. Taken together, administration of resveratrol as soon as possible after the onset of sepsis could protect against septic AKI mainly through inhibiting IRE1-NF-κB pathway-triggered inflammatory response in the kidney. Resveratrol might be a readily translatable option to improve the prognosis of sepsis.

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Background/Aims: Chondrocyte apoptosis is closely related to the development and progression of osteoarthritis. Global adiponectin (gAPN), secreted from adipose tissue, possesses potent anti-inflammatory and antiapoptotic properties in various cell types. This study aimed to investigate the role of autophagy induced by gAPN in the suppression of H 2 O 2 -induced apoptosis and the potential mechanism of gAPN-induced autophagy in chondrocytes. Methods: H 2 O 2 was used to induce apoptotic injury in rat chondrocytes. CCK-8 assay was performed to determine the viability of cells treated with different concentrations of gAPN with or without H 2 O 2 . Cell apoptosis was detected by flow cytometry and TUNEL staining. Mitochondrial membrane potential was examined using JC-1 fluorescence staining assay. The autophagy inhibitors 3-MA and Bafilomycin A1 were used to treat cells and then evaluate the effect of gAPN-induced autophagy. To determine the downstream pathway, chondrocytes were preincubated with the AMPK inhibitor Compound C. Beclin-1, LC3B, P62 and apoptosisrelated proteins were identified by Western blot analysis. Results: H 2 O 2 (400 μM)-induced chondrocytes apoptosis and caspase-3 activation were attenuated by gAPN (0.5 μg/mL). gAPN increased Bcl-2 expression and decreased Bax expression. The loss of mitochondrial membrane potential induced by H 2 O 2 was also abolished by gAPN. Furthermore, the antiapoptotic effect of gAPN was related to gAPN-induced autophagy by increased formation of Beclin-1 and LC3B and P62 degradation. In particular, the inhibition of gAPN-induced autophagy by 3-MA prevented the protective effect of gAPN on apoptosis induced by H 2 O 2 . Moreover, gAPN increased p-AMPK expression and decreased p-mTOR expression. Compound C partly suppressed the expression of autophagy-related proteins and restored the expression of p-mTOR suppressed by gAPN. Thus, the AMPK/mTOR pathway played an important role