Targeting the GLIS1/DNMT3B-mediated DNA Methylation of HOXA9 to Suppress Metastasis in Lung Adenocarcinoma

Metastasis is the leading cause of death in patients with lung adenocarcinoma (LUAD), highlighting the urgent need to identify novel therapeutic targets. GLIS family zinc finger 1 (GLIS1) is a transcription factor implicated in multiple cancers. However, its role in LUAD remains poorly defined. In this study, we first identified that GLIS1 was significantly upregulated in LUAD tissues. To modulate its expression, lentiviral vectors were constructed to knock down or overexpress GLIS1 in NCI-H1975 and A549 LUAD cell lines, respectively. In vitro gain- and loss-of-function experiments revealed that GLIS1 knockdown significantly inhibited the migratory and invasive capabilities of NCI-H1975 cells. Conversely, GLIS1 overexpression enhanced these malignant phenotypes in A549 cells. In vivo study demonstrated that GLIS1 knockdown substantially reduced liver and lung metastasis of NCI-H1975 cells in mice. Furthermore, we found that downregulation of GLIS1 suppressed LUAD cell migration by inhibiting Homeobox A9 (HOXA9) methylation, which led to the subsequent upregulation of HOXA9 expression. Mechanistically, GLIS1 knockdown transcriptionally suppressed the mRNA level of the DNA methyltransferase DNMT3B, thereby attenuating HOXA9 methylation. Specifically, overexpression of DNMT3B led to DNA hypermethylation and transcriptional suppression of HOXA9, thereby partially rescuing the tumor-suppressive effects resulting from GLIS1 knockdown. Our work is the first to implicate the GLIS1/DNMT3B axis in the epigenetic silencing of HOXA9 in LUAD, highlighting the therapeutic potential of targeting GLIS1.