TRIB3 promotes exclusion of CD8 ⁺ T cells and enhances immune evasion by inhibiting the STAT1-CXCL10 signaling axis in colorectal cancer.

CD8 ⁺ T cell activation leads to the rapid proliferation and differentiation of effector T cells (T _effs ), which mediate antitumor immunity. Although aerobic glycolysis is preferentially activated in CD8 ⁺ T _effs , the mechanisms that regulate CD8 ⁺ T cell glucose uptake in the low-glucose and acidic tumor microenvironment (TME) remain poorly understood. Here, we report that the abundance of the glucose transporter GLUT10 is increased during CD8 ⁺ T cell activation and antitumor immunity. Specifically, GLUT10 deficiency inhibited glucose uptake, glycolysis, and antitumor efficiency of tumor-infiltrating CD8 ⁺ T cells. Supplementation with glucose alone was insufficient to rescue the antitumor function and glucose uptake of CD8 ⁺ T cells in the TME. By analyzing tumor environmental metabolites, we found that high concentrations of lactic acid reduced the glucose uptake, activation, and antitumor effects of CD8 ⁺ T cells by directly binding to GLUT10’s intracellular motif. Disrupting the interaction of lactic acid and GLUT10 by the mimic peptide PG10.3 facilitated CD8 ⁺ T cell glucose utilization, proliferation, and antitumor functions. The combination of PG10.3 and GLUT1 inhibition or anti–programmed cell death 1 antibody treatment showed synergistic antitumor effects. Together, our data indicate that GLUT10 is selectively required for glucose uptake of CD8 ⁺ T cells and identify that TME accumulated lactic acid inhibits CD8 ⁺ T cell effector function by directly binding to GLUT10 and reducing its glucose transport capacity. Last, our study suggests disrupting lactate-GLUT10 binding as a promising therapeutic strategy to enhance CD8 ⁺ T cell–mediated antitumor effects.

The MEK-ERK signaling pathway and autophagy play an important role for enterovirus71(EV71) replication. Inhibition of MEK-ERK signaling pathway and autophagy is shown to impair EV71 replication. Berberine (BBR), an isoquinoline alkaloid isolated from Berberis vulgaris L., has been reported to have ability to regulate this signaling pathway and autophagy. Herein, we want to determine whether berberine can inhibit EV71 infection by downregulating the MEK/ERK signaling pathway and autophagy. The antiviral effect of berberine was determined by cytopathic effect (CPE) assay, western blotting assay and qRT-PCR assay. The mechanism of BBR anti-virus was determined by western blotting assay and immunofluorescence assay. We showed that berberine does-dependently reduced EV71 RNA and protein synthesis, which was, at least in part, the result of inhibition of activation of MEK/ERK signaling pathway. Furthermore, we found that berberine suppressed the EV71-induced autophagy by activating AKT protein and inhibiting the phosphorylation of JNK and PI3KIII. BBR inhibited EV71 replication by downregulating autophagy and MEK/ERK signaling pathway. These findings suggest that BBR may be a potential agent or supplement against EV71 infection.

CSCs (Cancer stem cells) with distinct metabolic features are considered to cause HCC (hepatocellular carcinoma) initiation, metastasis and therapeutic resistance. Here, we perform a metabolic gene CRISPR/Cas9 knockout library screen in tumorspheres derived from HCC cells and find that deletion of SCARB2 suppresses the cancer stem cell-like properties of HCC cells. Knockout of Scarb2 in hepatocytes attenuates HCC initiation and progression in both MYC-driven and DEN (diethylnitrosamine)-induced HCC mouse models. Mechanistically, binding of SCARB2 with MYC promotes MYC acetylation by interfering with HDCA3-mediated MYC deacetylation on lysine 148 and subsequently enhances MYC transcriptional activity. Screening of a database of FDA (Food and Drug Administration)-approved drugs shows Polymyxin B displays high binding affinity for SCARB2 protein, disrupts the SCARB2-MYC interaction, decreases MYC activity, and reduces the tumor burden. Our study identifies SCARB2 as a functional driver of HCC and suggests Polymyxin B-based treatment as a targeted therapeutic option for HCC.

Acute promyelocytic leukemia (APL) is driven by the oncoprotein PML-RARα, which recruits corepressor complexes, including histone deacetylases (HDACs), to suppress cell differentiation and promote APL initiation. All-trans retinoic acid (ATRA) combined with arsenic trioxide (ATO) or chemotherapy highly improves the prognosis of APL patients. However, refractoriness to ATRA and ATO may occur, which leads to relapsed disease in a group of patients. Here, we report that HDAC3 was highly expressed in the APL subtype of AML, and the protein level of HDAC3 was positively associated with PML-RARα. Mechanistically, we found that HDAC3 deacetylated PML-RARα at lysine 394, which reduced PIAS1-mediated PML-RARα SUMOylation and subsequent RNF4-induced ubiquitylation. HDAC3 inhibition promoted PML-RARα ubiquitylation and degradation and reduced the expression of PML-RARα in both wild-type and ATRA- or ATO-resistant APL cells. Furthermore, genetic or pharmacological inhibition of HDAC3 induced differentiation, apoptosis, and decreased cellular self-renewal of APL cells, including primary leukemia cells from patients with resistant APL. Using both cell line- and patient-derived xenograft models, we demonstrated that treatment with an HDAC3 inhibitor or combination of ATRA/ATO reduced APL progression. In conclusion, our study identifies the role of HDAC3 as a positive regulator of the PML-RARα oncoprotein by deacetylating PML-RARα and suggests that targeting HDAC3 could be a promising strategy to treat relapsed/refractory APL.