Jianhua Qu

The ability to selectively eradicate oncogene-addicted tumors while reducing systemic toxicity has endeared targeted therapies as a treatment strategy. Nevertheless, development of acquired resistance limits the benefits and durability of such a regime. Here we report evidence of enhanced reliance on mitochondrial oxidative phosphorylation (OXPHOS) in oncogene-addicted cancers manifesting acquired resistance to targeted therapies. To that effect, we describe a novel OXPHOS targeting activity of the small molecule compound, OPB-51602 (OPB). Of note, a priori treatment with OPB restored sensitivity to targeted therapies. Furthermore, cancer cells exhibiting stemness markers also showed selective reliance on OXPHOS and enhanced sensitivity to OPB. Importantly, in a subset of patients who developed secondary resistance to EGFR tyrosine kinase inhibitor (TKI), OPB treatment resulted in decrease in metabolic activity and reduction in tumor size. Collectively, we show here a switch to mitochondrial OXPHOS as a key driver of targeted drug resistance in oncogene-addicted cancers. This metabolic vulnerability is exploited by a novel OXPHOS inhibitor, which also shows promise in the clinical setting.

Abstract Tim‐3 is a negative immunoregulator in anti‐tumor response, but its mechanism in chronic lymphocytic leukemia (CLL) is not yet clear. The aim of this study was to understand the role of Galectin‐9/Tim‐3 signaling pathway in the regulation of CD4 + T cell subsets in CLL patients. Flow cytometry results showed that the number of Treg cells obviously increased, and there was a significant Treg/Th17 imbalance in CLL patients. In addition, Tim‐3 overexpressed on the surface of Th1 and Treg cells in CLL patients. The levels of Galectin‐9 and IL‐10 were significantly elevated in patients of CLL, especially in stages of Binet B, and C. However, IFN‐γ decreased. Moreover, Galectin‐9 in CLL patients was positively correlated with the number of Tim‐3 + Treg cells and the level of IL‐10. Interestingly, when the Tim‐3/Galectin‐9 pathway was blocked in vitro, the level of IL‐10 in the culture supernatant of CD4 + T was significantly reduced, while the levels of IFN‐γ and TNF‐α were increased. After co‐culture with activated Th1 cells, the apoptosis of CLL cells was significantly increased, and this effect was reversed after treatment with Tim‐3 + Tregs. In summary, Galectin‐9/Tim‐3 are elevated in CLL and associated with disease progression. By the negative regulation of CD4 + T cells, activated Galectin‐9/Tim‐3 suppresses Th1 effector function and also promotes Treg to be involved in immune escape of CLL. This pathway might become the potential target of immunotherapy in CLL patients.

Bcl-2 phosphorylation at serine-70 (S70pBcl2) confers resistance against drug-induced apoptosis. Nevertheless, its specific mechanism in driving drug-resistance remains unclear. We present evidence that S70pBcl2 promotes cancer cell survival by acting as a redox sensor and modulator to prevent oxidative stress-induced DNA damage and execution. Increased S70pBcl2 levels are inversely correlated with DNA damage in chronic lymphocytic leukemia (CLL) and lymphoma patient-derived primary cells as well as in reactive oxygen species (ROS)- or chemotherapeutic drug-treated cell lines. Bioinformatic analyses suggest that S70pBcl2 is associated with lower median overall survival in lymphoma patients. Empirically, sustained expression of the redox-sensitive S70pBcl2 prevents oxidative stress-induced DNA damage and cell death by suppressing mitochondrial ROS production. Using cell lines and lymphoma primary cells, we further demonstrate that S70pBcl2 reduces the interaction of Bcl-2 with the mitochondrial complex-IV subunit-5A, thereby reducing mitochondrial complex-IV activity, respiration and ROS production. Notably, targeting S70pBcl2 with the phosphatase activator, FTY720, is accompanied by an enhanced drug-induced DNA damage and cell death in CLL primary cells. Collectively, we provide a novel facet of the anti-apoptotic Bcl-2 by demonstrating that its phosphorylation at serine-70 functions as a redox sensor to prevent drug-induced oxidative stress-mediated DNA damage and execution with potential therapeutic implications.

OBJECTIVE: The gut microbiome is essential for human health due to its effects on disease development, drug metabolism and the immune system. It may also play a role in the interaction with environmental toxicants. However, the effect of epoxiconazole, a fungicide active ingredient from the class of azoles developed to protect crops, on the abundance and composition of the gut microbiome has never been studied. We put forward the hypothesis that changes in gut microbiota may be early signs of toxicity induced by epoxiconazole. METHODS: In this study, female rats were fed with epoxiconazole-adulterated diets (0, 4 and 100 mg/kg/day) for 90 days. The gut microbiome was determined by 16S rRNA gene sequencing. Body and organ weight, and blood biochemistry were also measured after 90 days of oral epoxiconazole exposure. RESULTS: Interestingly, the abundance of gut Firmicutes decreased, and Bacteroidetes and Proteobacteria increased. At family level, Lachnospiraceae and Enterobacteriaceae were selectively enriched following epoxiconazole exposure. Our results indicate that epoxiconazole exposure may induce changes in the gut microbiome and potential liver toxicity. CONCLUSION: Changes in the gut microbiome may be used as early indicators for monitoring the health risk of the host.

MicroRNAs (miRNAs) and aberrant glycosylation both play important roles in tumor metastasis. In this study, the role of miR-23a in N-glycosylation and the metastasis of mouse hepatocellular carcinoma (HCC) cells was investigated. The miRNA expression array profiles that were confirmed by qPCR and Western blot analyses revealed higher miR-23a expression levels in Hca-P cells (with lymphatic metastasis potential) than in Hepa1-6 cells (with no lymphatic metastasis potential), while the expression of mannoside acetylglucosaminyltransferase 3 (Mgat3) was negatively associated with metastasis potential. Mgat3 is a key glycosyltransferase in the synthesis of the bisecting (β1,4GlcNAc branching) N-glycan structure. Bioinformatics analysis indicated that Mgat3 may be a target of miR-23a, and this hypothesis was verified by dual-luciferase reporter gene assays. Furthermore, we found that the transcription factor Runx2 can directly bind to the miR-23a gene promoter and promote its expression, as shown in dual-luciferase reporter gene assays and ChIP assays. Collectively, these results indicate that miR-23a might increase the metastatic potential of mouse HCC by affecting the branch formation of N-glycan chains presented on the cell surface through the targeting of the glycosyltransferase Mgat3. These findings may provide insight into the relationship between abnormal miRNA expression and aberrant glycosylation during tumor lymphatic metastasis.