FTO/IGF2BP2-mediated N6 methyladenosine modification in invasion and metastasis of thyroid carcinoma via CDH12.

Epigenetic reprogramming plays a critical role in cancer progression of cancer, and N6-methyladenosine (m6A) is the most common RNA modification in eukaryotes. The purpose of this study was to explore the related modification mode of m6A regulator construction and evaluate the invasion and migration of thyroid cancer. Our results showed that m6A levels were significantly increased in papillary thyroid cancer (PTC) and anaplastic thyroid cancer (ATC) samples, which may have been induced by the down-regulation of demethylase fat mass and obesity-associated gene (FTO). Moreover, FTO inhibited PTC and ATC invasion and metastasis through the epithelial-to-mesenchymal transition (EMT) pathway in vivo and in vitro. Mechanistically, an m6A-mRNA epitranscriptomic microarray showed that Cadherin 12 (CDH12) is the key target gene mediated by FTO in an m6A-dependent manner. CDH12 promotes invasion and metastasis through the EMT pathway in thyroid cancer, both in vivo and in vitro. Furthermore, we found that insulin-like growth factor 2 mRNA-binding protein 2 (IGF2BP2) is an important m6A reading protein, that regulates the stability of CDH12 mRNA and mediates EMT progression, thereby promoting the invasion and metastasis of PTC and ATC. Thus, FTO, IGF2BP2 and CDH12 may be effective therapeutic targets for PTC and ATC with significant invasion or distant metastasis. Schematic summary of FTO-IGF2BP2 axis in modulation of CDH12 mRNA m6A and upregulation of CDH12 expression in the invasion and metastasis of thyroid carcinoma.

Chen Z ，Zhong X ，Xia M ，Liu C ，Tang W ，Liu G ，Yi Y ，Guo Y ，Jiang Q ，Zu X ，Zhong J ... -  《Cell Death & Disease》

FTO suppresses glycolysis and growth of papillary thyroid cancer via decreasing stability of APOE mRNA in an N6-methyladenosine-dependent manner.

N6-methyladenosine (m6A) modification is the most common chemical modification in mammalian mRNAs, and it plays important roles by regulating several cellular processes. Previous studies report that m6A is implicated in modulating tumorigenesis and progression. However, dysregulation of m6A modification and effect of m6A demethylase fat-mass and obesity-associated protein (FTO) on glucose metabolism has not been fully elucidated in papillary thyroid cancer (PTC). 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 m6A 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. 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 m6A modification profile in PTC cells and Apolipoprotein E (APOE) was identified as the target gene for FTO-mediated m6A modification using RNA-seq and MeRIP-seq. FTO knockdown significantly increased APOE mRNA m6A modification and upregulated its expression. FTO-mediated m6A modification of APOE mRNA was recognized and stabilized by the m6A 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. 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 m6A modification and may inhibit glycolytic metabolism in PTC by modulating IL-6/JAK2/STAT3 signaling pathway, thus abrogating tumor growth.

Huang J ，Sun W ，Wang Z ，Lv C ，Zhang T ，Zhang D ，Dong W ，Shao L ，He L ，Ji X ，Zhang P ，Zhang H ... -  《-》

RNA N6-methyladenosine reader IGF2BP2 promotes lymphatic metastasis and epithelial-mesenchymal transition of head and neck squamous carcinoma cells via stabilizing slug mRNA in an m6A-dependent manner.

Lymph node metastasis is the main cause of poor prognosis of head and neck squamous carcinoma (HNSCC) patients. N6-methyladenosine (m6A) RNA modification is an emerging epigenetic regulatory mechanism for gene expression, and as a novel m6A reader protein, IGF2BP2 has been implicated in tumor progression and metastasis. However, not much is currently known about the functional roles of IGF2BP2 in HNSCC, and whether IGF2BP2 regulates lymphatic metastasis through m6A modification in HNSCC remains to be determined. The expression and overall survival (OS) probability of m6A-related regulators in HNSCC were analyzed with The Cancer Genome Atlas (TCGA) dataset and GEPIA website tool, respectively. The expression levels of IGF2BP2 were measured in HNSCC tissues and normal adjacent tissues. To study the effects of IGF2BP2 on HNSCC cell metastasis in vitro and in vivo, gain- and loss- of function methods were employed. RIP, MeRIP, luciferase reporter and mRNA stability assays were performed to explore the epigenetic mechanism of IGF2BP2 in HNSCC. We investigated 20 m6A-related regulators in HNSCC and discovered that only the overexpression of IGF2BP2 was associated with a poor OS probability and an independent prognostic factor for HNSCC patients. Additionally, we demonstrated that IGF2BP2 was overexpressed in HNSCC tissues, and significantly correlated to lymphatic metastasis and poor prognosis. Functional studies have shown that IGF2BP2 promotes both HNSCC cell migration as well as invasion via the epithelial-mesenchymal transition (EMT) process in vitro, and IGF2BP2 knockdown significantly inhibited lymphatic metastasis and lymphangiogenesis in vivo. Mechanistic investigations revealed that Slug, a key EMT-related transcriptional factor, is the direct target of IGF2BP2, and essential for IGF2BP2-regulated EMT and metastasis in HNSCC. Furthermore, we demonstrated that IGF2BP2 recognizes and binds the m6A site in the coding sequence (CDS) region of Slug and promotes its mRNA stability. Collectively, our study uncovers the oncogenic role and potential mechanism of IGF2BP2, which serves as a m6A reader, in controlling lymphatic metastasis and EMT in HNSCC, suggesting that IGF2BP2 may act as a therapeutic target and prognostic biomarker for HNSCC patients with metastasis.

Yu D ，Pan M ，Li Y ，Lu T ，Wang Z ，Liu C ，Hu G ... -  《-》

RNA N6-methyladenosine demethylase FTO promotes breast tumor progression through inhibiting BNIP3.

Niu Y ，Lin Z ，Wan A ，Chen H ，Liang H ，Sun L ，Wang Y ，Li X ，Xiong XF ，Wei B ，Wu X ，Wan G ... -  《-》

FTO Prevents Thyroid Cancer Progression by SLC7A11 m6A Methylation in a Ferroptosis-Dependent Manner.

N6 methyladenosine (m6A) modification serves as a novel epigenetic regulatory mechanism that is heavily implicated in the heredity of tumors. Meanwhile, fat mass and obesity-associated protein (FTO) has the potential to affect the regulation of m6A modification in the mRNA of key oncogenes as well as tumor suppressor genes that facilitate tumor progression. In our study, FTO was downregulated in papillary thyroid carcinoma (PTC) tissues. The role of FTO in PTC was assessed by Cell Counting Kit-8 analysis, cell scratch, migration, invasion experiment, flow cytometry apoptosis analysis, and nude mouse experiment. In addition to RNA-Seq and meRIP-Seq, luciferase reporting and mutation analysis have also identified SLC7A11 as the potential FTO regulatory gene. Moreover, X-ray electron microscopy, glutathione (GSH)/oxidized GSH, GPX, malondialdehyde determination, and western blot helped confirmed that FTO inhibited the development of PTC by downregulating the expression of SLC7A11 through ferroptosis. Finally, a rescue experiment was employed to clarify the relationship between FTO and its specific target gene SLC7A11. FTO is able to inhibit the occurrence of PTC by downregulating SLC7A11 in m6A independently, and it functions as a tumor suppressor gene in PTC. These findings could contribute to our understanding of the tumor malignancy regulated by m6A and might lead to new insights for potential biomarkers and therapeutic targets for the treatment of thyroid papillary carcinoma.

Ji FH ，Fu XH ，Li GQ ，He Q ，Qiu XG ... -  《-》