METTL3 orchestrates glycolysis by stabilizing the c-Myc/WDR5 complex in triple-negative breast cancer.

BACKGROUND: The carcinogenic transcription factor c-Myc is the most aggressive oncogene, which drive malignant transformation and dissemination of triple-negative breast cancer (TNBC). Recruitment of many cofactors, especially WDR5, a protein that nucleates H3K4me chromatin modifying complexes, play a pivotal role in regulating c-Myc-dependent gene transcription, a critical process for c-Myc signaling to function in a variety of biological and pathological contexts. For this reason, interrupting the interaction between c-Myc and the transcription cofactor WDR5 may become the most promising new strategy for treating c-Myc driven TNBC. METHODS: Immunoprecipitation and mass spectrometry (IP-MS) is used to screen proteins that bind c-Myc/WDR5 interactions. The interaction of METTL3 with c-Myc/WDR5 in breast cancer tissues and TNBC cells was detected by Co-IP and immunofluorescence. Subsequently, we further analyzed the influence of METTL3 expression on c-Myc/WDR5 protein expression and its interaction stability by Western blot and Co-IP. The correlation between METTL3 and c-Myc pathway was analyzed by ChIP-seq sequencing and METTL3 knockdown transcriptome data. The effect of METTL3 expression on c-Myc transcriptional activity was detected by ChIP-qPCR and Dual Luciferase Reporter. At the same time, the overexpression vector METTL3-MUT (m6A) was constructed, which mutated the methyltransferase active site (Aa395-398, DPPW/APPA), and further explored whether the interaction between METTL3 and c-Myc/WDR5 was independent of methyltransferase activity. In addition, we also detected the changes of METTL3 expression on TNBC's sensitivity to small molecule inhibitors such as JQ1 and OICR9429 by CCK8, Transwell and clonal formation assays. Finally, we further verified our conclusions in spontaneous tumor formation mouse MMTV-PyMT and nude mouse orthotopic transplantation tumor models. RESULTS: METTL3 was found to bind mainly to c-Myc/WDR5 protein in the nucleus. It enhances the stability of c-Myc/WDR5 interaction through its methyltransferase independent mechanism, thereby enhancing the transcriptional activity of c-Myc on downstream glucose metabolism genes. Notably, the study also confirmed that METTL3 can directly participate in the transcription of glucose metabolism genes as a transcription factor, and knockdown METTL3 enhances the drug sensitivity of breast cancer cells to small molecule inhibitors JQ1 and OICR9429. The study was further confirmed by spontaneous tumor formation mouse MMTV-PyMT and nude mouse orthotopic transplantation tumor models. CONCLUSION: METTL3 binds to the c-Myc/WDR5 protein complex and promotes glycolysis, which plays a powerful role in promoting TNBC progression. Our findings further broaden our understanding of the role and mechanism of action of METTL3, and may open up new therapeutic avenues for effective treatment of TNBC with high c-Myc expression.

IGF2BP2-modified UBE2D1 interacts with Smad2/3 to promote the progression of breast cancer.

Recent studies have suggested that ubiquitin-conjugating enzyme E2D1 (UBE2D1) is involved in tumor progression. In this study, we found that UBE2D1 expression was upregulated in breast cancer (BC) and was related to the prognosis of BC patients. Through in vitro and in vivo experiments, we demonstrated the aberrant expression of UBE2D1 promoted the proliferation and migration of BC cells, and the IGF2BP2-mediated N6-methyladenosine (m6A) modification increased the stability of UBE2D1 mRNA. Mechanistically, UBE2D1 expression regulated the activity of TGF-ß signaling through modulating the expression and the phosphorylation level of Smad2/3. Furthermore, UBE2D1 directly bound to Smad2/3 and affected the subsequent binding of Smad2 and Smad3, which is a necessary step for TGF-ß signaling activation. Thus, our study reveals a pro-oncogenic role of UBE2D1 in the progression of BC and may provide novel strategies for BC treatment.

Mettl3 synergistically regulates TGF-ß/SMAD2/3 to promote proliferation and metastasis of gastric cancer.

Transforming Growth factor-ß (TGF-ß)/Smad signaling is a complex regulatory network that both inhibits and promotes tumorigenesis. However, the mechanisms underlying the function of TGF-ß/Smad signaling pathway remain to be fully elucidated. As a methyltransferase, METTL3 is closely related to tumor development, but the role of METTL3 in the proliferation and metastasis of TGF-ß/Smad-activated gastric cancer (GC) is unclear. In this study, we identified TGF-ß/Smad2/3 axis as an important carcinogenic pathway in GC, which significantly promoted the proliferation and metastasis of GC. Furthermore, we found that Smad3 mRNA could be modified by m6A, which was subsequently recognized and stabilized by IGF2BP2, thereby enhancing Smad3 protein expression and promoting the activation of TGF-ß/Smad pathway. Importantly, we also found that METTL3 could combine with p-Smad3 to regulate the transcription of downstream target genes. Therefore, this study revealed a novel mechanism by which METTL3 synergistically regulates TGF-ß/Smad2/3 signaling and provide a new potential therapeutic target for the treatment of GC.

Hypoxia-Associated Prognostic Markers and Competing Endogenous RNA Co-Expression Networks in Breast Cancer.

Objective: Many primary tumors have insufficient supply of molecular oxygen, called hypoxia. Hypoxia is one of the leading characteristics of solid tumors resulting in a higher risk of local failure and distant metastasis. It is quite necessary to investigate the hypoxia associated molecular hallmarks in breast cancer. Materials and Methods: According to the published studies, we selected 13 hypoxia related gene expression signature to define the hypoxia status of breast cancer using ConsensusClusterPlus package based on the data from The Cancer Genome Atlas (TCGA). Subsequently, we characterized the infiltration of 24 immune cell types under different hypoxic conditions. Furthermore, the differentially expressed hypoxia associated microRNAs, mRNAs and related signaling pathways were analyzed and depicted. On this basis, a series of prognostic markers related to hypoxia were identified and ceRNA co-expression networks were constructed. Results: Two subgroups (cluster1 and cluster2) were identified and the 13 hypoxia related gene signature were all up-regulated in cluster1. Thus, we defined the cluster1 as "hypoxic subgroup" compared with cluster2. The infiltration of CD8+ T cell and CD4+ T cell were lower in cluster1 while the nTreg cell and iTreg cell were higher, indicating that there was immunosuppressive status in cluster1. We observed widespread hypoxia-associated dysregulation of microRNAs and mRNAs. Next, a risk signature for predicting prognosis of breast cancer patients was established based on 12 dysregulated hypoxia associated prognostic genes. Two microRNAs, hsa-miR-210-3p and hsa-miR-190b, with the most significant absolute logFC value were related to unfavorable and better prognosis, respectively. Several long non-coding RNAs were predicted to be microRNA targets and positively correlated with two selected mRNAs, CPEB2 and BCL11A. Predictions based on the SNHG16-hsa-miR-210-3p-CPEB2 and LINC00899/PSMG3-AS1/PAXIP-AS1-hsa-miR-190b-BCL11A ceRNA regulation networks indicated that the two genes might act as tumor suppressor and oncogene, respectively. Conclusion: Hypoxia plays an important role in the initiation and progression of breast cancer. Our research provides potential mechanisms into molecular-level understanding of tumor hypoxia.

Betulinic acid inhibits cell proliferation and migration in gastric cancer by targeting the NF-κB/VASP pathway.

Gastric cancer (GC) is one of the most common malignant neoplasms of the digestive system, with China leading in terms of morbidity and mortality rates. Betulinic acid (BA) is a widely-occurring pentacyclic triterpenoid that has been reported to exhibit potent anti-inflammatory, antioxidant, and antitumor activities. BA can combat tumors by inducing apoptosis, regulating cell cycle, and inhibiting autophagy, but its mechanism of action in the context of GC is unclear. A preliminary study found that higher expression of vasodilator-stimulated phosphoprotein (VASP) was correlated with migration in the GC cell line. In this study, BGC-823 cells and MNK45 cells were treated with BA for investigating its effect on the proliferation and migration of cells. Moreover, the expression of VASP and upstream signal molecules were also investigated in this background. The results showed BA could inhibit the proliferation and migration the GC cells. Furthermore, NF-κB acted as a transcription factor to upregulate VASP expression. Moreover, BA could downregulate the expression of VASP at the protein and mRNA level by inhibiting NF-κB activity. In conclusion, these results suggest that BA could inhibit the expression of VASP by negatively regulating NF-κB, thereby inhibiting the proliferation and migration of the GC cells. Our study provides a theoretical basis for exploring the molecular mechanism underlying BA-induced inhibition of proliferation and migration in GC cells.

Corrigendum: Hypoxia-Associated Prognostic Markers and Competing Endogenous RNA Co-Expression Networks in Breast Cancer.

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[Device associated infection in medical surgical intensive care unit inpatients of an A level, tertiary class hospital in Beijing].

OBJECTIVE: To understand the situation of the device-associated infection (DAI) in the medical-surgical intensive care unit(ICU)inpatients in an A-level tertiary class hospital in Beijing. METHODS: DAI date were collected through a surveillance on the medical-surgical ICU inpatients in an A-level tertiary class hospital in Beijing from January 2008 to December 2010. RESULTS: In 2279 patients admitted to the medical-surgical ICU (with a 15,332 days total hospitalization stay), 283 were found infected. The incidence for in-hospital infection was 12.42%, and 2.452% for the incidence per patient-day. The device utilization ratios for ventilator, central venous catheter and urinary catheter were 56.76%, 59.01% and 80.07% respectively while the incidence for ventilator-associated pneumonia (VAP), central line-associated bloodstream infection (CLABSI) and catheter-associated urinary tract infection (CAUTI) were 1.632%, 0.409% and 0.350% respectively. The predominant bacteria species found in these cases were Gram-negatives and the main stay of pathogenic species were A. baumannii, P. aeruginosa, Staphylococcus, E. coli, K. pneumoniae and C. albicans etc. CONCLUSION: The incidence of DAI in the surveyed hospital is close to other hospitals in China and other developing countries but higher than hospitals in United States. More efforts should be made for its prevention / control by hospital stuff, with the cooperation from the patients.