Dataset Information

The m6A methyltransferase METTL3 controls epithelial-mesenchymal transition, migration and invasion of breast cancer through the MALAT1/miR-26b/HMGA2 axis.

ABSTRACT:

Background

Previous studies have revealed the key functions of N6-methyladenosine (m6A) modification in breast cancer (BC). MALAT1 as a highly m6A modified lncRNA associated with cancer development and metastasis, but the functional relevance of m6A methyltransferase and MALAT1 in BC is still unknown. Here, our study investigated the effects of the novel m6A methyltransferase METTL3 on epithelial-mesenchymal transition (EMT) in BC via the MALAT1/miR-26b/HMGA2 axis.

Methods

Firstly, we collected clinical BC samples and cultured BC cells, and detected mRNA and protein levels in the human samples and human cell lines by RT-qPCR and Western blot, respectively. Then, the binding of MALAT1 and miR-26b and the targeting relationship between miR-26b and HMGA2 were examined by dual-luciferase assay. Moreover, the binding of MALAT1 and miR-26b was tested by RNA pull down and RNA immunoprecipitation (RIP) assays. Methylated-RNA immunoprecipitation (Me-RIP) was used to detect the m6A modification level of MALAT1. The interaction of METTL3 and MALAT1 was detected by photoactivatable ribonucleoside-crosslinking immunoprecipitation (PAR-CLIP). Finally, effects on invasion and migration were detected by Transwell.

Results

In BC, the level of miR-26b was consistently low, while the levels of METTL3, MALAT1 and HMGA2 were high. Further experiments showed that METTL3 up-regulated MALAT1 expression by modulating the m6A modification of MALAT1, and that MALAT1 could promote the expression of HMGA2 by sponging miR-26b. In BC cells, we found that silencing METTL3 could inhibit EMT and tumor cell invasion by suppressing MALAT1. Furthermore, MALAT1 mediated miR-26b to target HMGA2 and promote EMT, migration, and invasion. In summary, METTL3 promoted tumorigenesis of BC via the MALAT1/miR-26b/HMGA2 axis.

Conclusions

Silencing METTL3 down-regulate MALAT1 and HMGA2 by sponging miR-26b, and finally inhibit EMT, migration and invasion in BC, providing a theoretical basis for clinical treatment of BC.

SUBMITTER: Zhao C

PROVIDER: S-EPMC8380348 | biostudies-literature |

REPOSITORIES: biostudies-literature

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Project description:BackgroundColorectal carcinoma (CRC) is the third most common cancer and second most common cause of cancer-related deaths worldwide. Ribonucleic acid (RNA) N6-methyladnosine (m6A) and methyltransferase-like 3 (METTL3) play key roles in cancer progression. However, the roles of m6A and METTL3 in CRC progression require further clarification.MethodsAdenoma and CRC samples were examined to detect m6A and METTL3 levels, and tissue microarrays were performed to evaluate the association of m6A and METTL3 levels with the survival of patients with CRC. The biological functions of METTL3 were investigated through cell counting kit-8, wound healing, and transwell assays. M6A epitranscriptomic microarray, methylated RNA immunoprecipitation-qPCR, RNA stability, luciferase reporter, and RNA immunoprecipitation assays were performed to explore the mechanism of METTL3 in CRC progression.ResultsM6A and METTL3 levels were substantially elevated in CRC tissues, and patients with CRC with a high m6A or METTL3 levels exhibited shorter overall survival. METTL3 knockdown substantially inhibited the proliferation, migration, and invasion of CRC cells. An m6A epitranscriptomic microarray revealed that the cell polarity regulator Crumbs3 (CRB3) was the downstream target of METTL3. METTL3 knockdown substantially reduced the m6A level of CRB3, and inhibited the degradation of CRB3 mRNA to increase CRB3 expression. Luciferase reporter assays also showed that the transcriptional level of wild-type CRB3 significantly increased after METTL3 knockdown but not its level of variation. Knockdown of YT521-B homology domain-containing family protein 2 (YTHDF2) substantially increased CRB3 expression. RNA immunoprecipitation assays also verified the direct interaction between the YTHDF2 and CRB3 mRNA, and this direct interaction was impaired after METTL3 inhibition. In addition, CRB3 knockdown significantly promoted the proliferation, migration, and invasion of CRC cells. Mechanistically, METTL3 knockdown activated the Hippo pathway and reduced nuclear localization of Yes1-associated transcriptional regulator, and the effects were reversed by CRB3 knockdown.ConclusionsM6A and METTL3 levels were substantially elevated in CRC tissues relative to normal tissues. Patients with CRC with high m6A or METTL3 levels exhibited shorter overall survival, and METTL3 promoted CRC progression. Mechanistically, METTL3 regulated the progression of CRC by regulating the m6A-CRB3-Hippo pathway.