Xiaoyu Ji

Abstract Background N6-methyladenosine (m 6 A) modification is the most common chemical modification in mammalian mRNAs, and it plays important roles by regulating several cellular processes. Previous studies report that m 6 A is implicated in modulating tumorigenesis and progression. However, dysregulation of m 6 A modification and effect of m 6 A demethylase fat-mass and obesity-associated protein (FTO) on glucose metabolism has not been fully elucidated in papillary thyroid cancer (PTC). Methods Quantitative real-time PCR (qRT-PCR), western blotting and immunohistochemistry were performed to explore the expression profile of FTO in PTC tissues and adjacent non-cancerous thyroid tissues. Effects of FTO on PTC glycolysis and growth were investigated through in vitro and in vivo experiments. Mechanism of FTO-mediated m 6 A modification was explored through transcriptome-sequencing (RNA-seq), methylated RNA immunoprecipitation sequencing (MeRIP-seq), MeRIP-qPCR, luciferase reporter assays, RNA stability assay and RNA immunoprecipitation assay. Results FTO expression was significantly downregulated in PTC tissues. Functional analysis showed that FTO inhibited PTC glycolysis and growth. Further analyses were conducted to explore FTO-mediated m 6 A modification profile in PTC cells and Apolipoprotein E (APOE) was identified as the target gene for FTO-mediated m 6 A modification using RNA-seq and MeRIP-seq. FTO knockdown significantly increased APOE mRNA m 6 A modification and upregulated its expression. FTO-mediated m 6 A modification of APOE mRNA was recognized and stabilized by the m 6 A reader IGF2BP2. The findings showed that APOE also promoted tumor growth through glycolysis in PTC. Analysis showed that FTO/APOE axis inhibits PTC glycolysis by modulating IL-6/JAK2/STAT3 signaling pathway. Conclusion FTO acts as a tumor suppressor to inhibit tumor glycolysis in PTC. The findings of the current study showed that FTO inhibited expression of APOE through IGF2BP2-mediated m 6 A modification and may inhibit glycolytic metabolism in PTC by modulating IL-6/JAK2/STAT3 signaling pathway, thus abrogating tumor growth.

BACKGROUND AND AIMS: Because of a paucity of effective treatment options, metastasis is still a major cause for HCC-associated mortality. The molecular mechanism of inflammation-induced HCC metastasis is open for study. Here, we characterized the function of solute carrier family 7 member 11 (SLC7A11) in inflammation-related HCC metastasis and probed therapy strategies for this subpopulation of patients. APPROACH AND RESULTS: Elevated expression of SLC7A11 was positively correlated with poor tumor differentiation, and higher tumor-nodule-metastasis stage, and indicated poor prognosis in human HCC. SLC7A11 increased HIF1α expression through reducing α-ketoglutarate (αKG) level by exporting glutamate. SLC7A11 up-regulated programmed death ligand 1 (PD-L1) and colony-stimulating factor 1 (CSF1) expression through αKG-HIF1α cascade. SLC7A11 overexpression in HCC cells promoted intratumoral tumor-associated macrophage (TAM) and myeloid-derived suppressor cell (MDSC) infiltration through the CSF1/colony-stimulating factor 1 receptor (CSF1R) axis, whereas knockdown of CSF1 attenuated SLC7A11-mediated intratumoral TAM and MDSC infiltration and HCC metastasis. Depletion of either TAMs or MDSCs decreased SLC7A11-mediated HCC metastasis. Furthermore, the combination of CSF1R inhibitor BZL945 and anti-PD-L1 antibody blocked SLC7A11-induced HCC metastasis. In addition, IL-1β up-regulated SLC7A11 expression through the interleukin-1 receptor type 1 (IL-1R1)/extracellular signal-regulated kinase/specificity protein 1 pathway. SLC7A11 knockdown impaired IL-1β-promoted HCC metastasis. Anakinra, an IL-1R1 antagonist, reversed IL-1β-promoted HCC metastasis. In human HCC tissues, SLC7A11 expression was positively associated with HIF1α, PD-L1, and CSF1 expression and intratumoral TAM and MDSC infiltration. CONCLUSIONS: IL-1β-induced SLC7A11 overexpression up-regulated PD-L1 and CSF1 through the αKG/HIF1α axis, which promoted TAM and MDSC infiltration. Interruption of this oncogenic loop may provide a promising therapy strategy for the inhibition of SLC7A11-mediated HCC metastasis.

The homeobox (HOX) genes encoding an evolutionarily highly conserved family of homeodomain-containing transcriptional factors are essential for embryogenesis and tumorigenesis. HOX genes are involved in cell identity determination during early embryonic development and postnatal processes. The deregulation of HOX genes is closely associated with numerous human malignancies, highlighting the indispensable involvement in mortal cancer development. Since most HOX genes behave as oncogenes or tumor suppressors in human cancer, a better comprehension of their upstream regulators and downstream targets contributes to elucidating the function of HOX genes in cancer development. In addition, targeting HOX genes may imply therapeutic potential. Recently, novel therapies such as monoclonal antibodies targeting tyrosine receptor kinases, small molecular chemical inhibitors, and small interfering RNA strategies, are difficult to implement for targeting transcriptional factors on account of the dual function and pleiotropic nature of HOX genes-related molecular networks. This paper summarizes the current state of knowledge on the roles of HOX genes in human cancer and emphasizes the emerging importance of HOX genes as potential therapeutic targets to overcome the limitations of present cancer therapy.