Autophagy is a lysosome-dependent degradative process that protects cancer cells from multiple stresses. In preclinical models, autophagy inhibition with chloroquine (CQ) derivatives augments the efficacy of many anticancer therapies, but CQ has limited activity as a single agent. Clinical trials are underway combining anticancer agents with hydroxychloroquine (HCQ), but concentrations of HCQ required to inhibit autophagy are not consistently achievable in the clinic. We report the synthesis and characterization of bisaminoquinoline autophagy inhibitors that potently inhibit autophagy and impair tumor growth in vivo. The structural motifs that are necessary for improved autophagy inhibition compared with CQ include the presence of two aminoquinoline rings and a triamine linker and C-7 chlorine. The lead compound, Lys01, is a 10-fold more potent autophagy inhibitor than HCQ. Compared with HCQ, Lys05, a water-soluble salt of Lys01, more potently accumulates within and deacidifies the lysosome, resulting in impaired autophagy and tumor growth. At the highest dose administered, some mice develop Paneth cell dysfunction that resembles the intestinal phenotype of mice and humans with genetic defects in the autophagy gene ATG16L1, providing in vivo evidence that Lys05 targets autophagy. Unlike HCQ, significant single-agent antitumor activity is observed without toxicity in mice treated with lower doses of Lys05, establishing the therapeutic potential of this compound in cancer.cell death | stress responses | cancer cell survival | drug resistance | antimalarials A utophagy, the sequestration of organelles and proteins in autophagic vesicles (AVs) and degradation of this cargo through lysosomal fusion (1), allows tumor cells to survive metabolic and therapeutic stresses (2-5). Therapy-induced autophagy is a key resistance mechanism to many anticancer agents (6), and autophagy levels are increased in most cancers (7). Chloroquine (CQ; Fig. 1, compound 1) derivatives block autophagy by impairing lysosomal function (3,8,9). Studies in multiple mouse models of malignancy have demonstrated that autophagy inhibition with CQ derivatives augments the efficacy of a variety of anticancer agents. Clinical trials combining cancer therapies with hydroxychloroquine (HCQ; Fig. 1), have been launched, and preliminary results indicate these combinations have activity (6). However, pharmacokinetic (PK)-pharmacodynamic (PD) studies conducted in patients receiving HCQ for cancer therapy have indicated that the high micromolar concentrations of HCQ required to inhibit autophagy in vitro are inconsistently achieved in humans (10). There is an unmet need to develop more potent inhibitors of autophagy.The design and synthesis of dimeric analogs of CQ that exploit the thermodynamic advantages imparted by polyvalency (11, 12) has been previously studied in the context of malaria (13-15). The synthesis of heteroalkane-bridged bisquinolines did not produce sufficient antimalarial activity to warrant further investigation (14). Subsequently, a seri...

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Highlights d DSB repair, but not NER, coevolves with maximum lifespan (MLS) in rodents d The activity of SIRT6 in stimulating DSB repair coevolves with MLS in rodent species d Five amino acids determine the differential activities of mouse and beaver SIRT6 d Stronger SIRT6 leads to a longer lifespan

We previously demonstrated that mesenchymal stem cells (MSCs) ameliorated experimental autoimmune uveoretinitis (EAU) in rats. Recently, MSC-derived exosomes (MSC-Exo) were thought to carry functions of MSCs. In this study, we tested the effect of local administration of human MSC-Exo on established EAU in the same species. Rats with EAU induced by immunization with interphotoreceptor retinol-binding protein 1177–1191 peptide were treated by periocular injections of increasing doses of MSC-Exo starting at the disease onset for 7 consecutive days. The in vitro effects of MSC-Exo on immune cell migration and responder T cell proliferation were examined by chemotactic assays and lymphocyte proliferation assays, respectively. We found that MSC-Exo greatly reduced the intensity of ongoing EAU as their parent cells by reducing the infiltration of T cell subsets, and other inflammatory cells, in the eyes. Furthermore, the chemoattractive effects of CCL2 and CCL21 on inflammatory cells were inhibited by MSC-Exo. However, no inhibitory effect of MSC-Exo on IRBP-specific T cell proliferation was observed. These results suggest that MSC-Exo effectively ameliorate EAU by inhibiting the migration of inflammatory cells, indicating a potential novel therapy of MSC-Exo for uveitis.