Targeting autophagic pathways for cancer drug discovery

Autophagy , an evolutionarily conserved lysosomal degradation process , has drawn an increasing amount of attention in recent years for its role in a variety of human diseases, such as cancer. Notably, autophagy plays an important role in regulating several survival and death signaling pathways that determine cell fate in cancer. To date, substantial evidence has demonstrated that some key autophagic mediators, such as autophagy-related genes (ATGs), PI3K, mTOR, p53, and Beclin-1, may play crucial roles in modulating autophagic activity in cancer initiation and progression. Because autophagy-modulating agents such as rapamycin and chloroquine have already been used clinically to treat cancer, it is conceivable that targeting autophagic pathways may provide a new opportunity for discovery and development of more novel cancer therapeutics. With a deeper understanding of the regulatory mechanisms governing autophagy, we will have a better opportunity to facilitate the exploitation of autophagy as a target for therapeutic intervention in cancer. This review discusses the current status of targeting autophagic pathways as a potential cancer therapy.

Autophagy and apoptosis: rivals or mates?

Autophagy, a cellular process of "self-eating" by which intracellular components are degraded within the lysosome, is an evolutionarily conserved response to various stresses. Autophagy is associated with numerous patho-physiological conditions, and dysregulation of autophagy contributes to the pathogenesis of a variety of human diseases including cancer. Depending on context, activation of autophagy may promote either cell survival or death, two major events that determine pathological process of many illnesses. Importantly, the activity of autophagy is often associated with apoptosis, another critical cellular process determining cellular fate. A better understanding of biology of autophagy and its implication in human health and disorder, as well as the relationship between autophagy and apoptosis, has the potential of facilitating the development of autophagy -based therapeutic interventions for human diseases such as cancer.

Expression of nucleus accumbens-1 in colon cancer negatively modulates antitumor immunity

BACKGROUND Nucleus accumbens-1(NAC-1)is highly expressed in a variety of tumors,including colon cancer,and is closely associated with tumor recurrence,metastasis,and invasion.AIM To determine whether and how NAC-1 affects antitumor immunity in colon cancer.METHODS NAC-1-siRNA was transfected into RKO colon cancer cells to knock down NAC expression;tumor cells with or without knockdown of NAC-1 were treated with CD8+T cells to test their cytocidal effect.The level of the immune checkpoint programmed death receptor-1 ligand(PD-L1)in colon cancer cells with or without knockdown of NAC-1 was analyzed using Quantitative real-time polymerase chain reaction and Western blotting.A double luciferase reporter assay was used to examine the effects of NAC-1 on the transcription of PD-L1.Mice bearing MC-38-OVA colon cancer cells expressing NAC-shRNA or controlshRNA were treated with OT-I mouse CD8+T cells to determine the tumor response to immunotherapy.Immune cells in the tumor tissues were analyzed using flow cytometry.NAC-1,PD-L1 and CD8+T cells in colon cancer specimens from patients were examined using immunohistochemistry staining.RESULTS Knockdown of NAC-1 expression in colon cancer cells significantly enhanced the cytocidal effect of CD8+T cells in cell culture experiments.The sensitizing effect of NAC-1 knockdown on the antitumor action of cytotoxic CD8+T cells was recapitulated in a colon cancer xenograft animal model.Furthermore,knockdown of NAC-1 in colon cancer cells decreased the expression of PD-L1 at both the mRNA and protein levels,and this effect could be rescued by transfection of an RNAi-resistant NAC-1 expression plasmid.In a reporter gene assay,transient expression of NAC-1 in colon cancer cells increased the promoter activity of PD-L1,indicating that NAC-1 regulates PD-L1 expression at the transcriptional level.In addition,depletion of tumoral NAC-1 increased the number of CD8+T cells but decreased the number of suppressive myeloid-derived suppressor cells and regulatory T cells.CONCLUSION Tumor expression of NAC-1 is a negative determinant of immunotherapy.

Control of CD4^(+) T cells to restrain inflammatory diseases via eukaryotic elongation factor 2 kinase

CD4^(+)T cells,particularly IL-17-secreting helper CD4^(+)T cells,play a central role in the inflammatory processes underlying autoimmune disorders.Eukaryotic Elongation Factor 2 Kinase(eEF2K)is pivotal in CD8^(+)T cells and has important implications in vascular dysfunction and inflammation-related diseases such as hypertension.However,its specific immunological role in CD4^(+)T cell activities and related inflammatory diseases remains elusive.Our investigation has uncovered that the deficiency of eEF2K disrupts the survival and proliferation of CD4^(+)T cells,impairs their ability to secrete cytokines.Notably,this dysregulation leads to heightened production of pro-inflammatory cytokine IL-17,fosters a pro-inflammatory microenvironment in the absence of eEF2K in CD4^(+)T cells.Furthermore,the absence of eEF2K in CD4^(+)T cells is linked to increased metabolic activity and mitochondrial bioenergetics.We have shown that eEF2K regulates mitochondrial function and CD4^(+)T cell activity through the upregulation of the transcription factor,signal transducer and activator of transcription 3(STAT3).Crucially,the deficiency of eEF2K exacerbates the severity of inflammation-related diseases,including rheumatoid arthritis,multiple sclerosis,and ulcerative colitis.Strikingly,the use of C188-9,a small molecule targeting STAT3,mitigates colitis in a murine immunodeficiency model receiving eEF2K knockout(KO)CD4^(+)T cells.These findings emphasize the pivotal role of eEF2K in controlling the function and metabolism of CD4^(+)T cells and its indispensable involvement in inflammation-related diseases.Manipulating eEF2K represents a promising avenue for novel therapeutic approaches in the treatment of inflammation-related disorders.

Bismuth trichloride-catalyzed oxy-Michael addition of water and alcohol to α,β-unsaturated ketones

An efficient method was developed for the conjugate addition of water to various a,β-unsaturated ketones by using bismuth(Ⅲ)chlo ride as a catalyst.The reactions proceeded smoothly in the presence of a catalytic amount of BiCl3(20 mol%)in aqueous media to furnish a variety of synthetically usefulβ-hydroxyl ketones in moderate to good yields.Apart from water molecule,various alcohols could also be employed as nucleophiles to react withα,β-unsaturated ketones,leading toβ-alkoxyl ketones in modest to high yields.In addition,the mild reaction conditions also entailed the conjugate addition reactions to proceed with the tolerance to a range of functional groups.

An efficient Bi/NH_4I-mediated addition reaction for the highly diastereoselective synthesis of homoallylic alcohols in aqueous media

An efficient water-based bismuth-mediated addition reaction of carbonyl compound with cyclic allylic halide was developed.The reactions proceeded smoothly in aqueous DMF in the presence of ammonium iodide to afford the corresponding syn-homoallylic alcohols in moderate to good yields with excellent diastereoselectivities(>99:1 syn:anti).Reversal of product diastereoselectivity was observed when heteroaryl aldehyde possessing an adjacent chelating nitrogen atom was employed as substrate.