Myeloid Zinc Finger 1 Induces Migration, Invasion, and In vivo Metastasis through Axl Gene Expression in Solid Cancer

Abstract

Myeloid zinc finger 1 (MZF1) is a member of the SCAN domain family transcription factors that form dimers through their highly conserved SCAN motifs. Silencing of MZF1 inhibits cell proliferation, and abnormal expression of MZF1 results in cancer development. However, a potential role of MZF1 in metastasis remains unclear. Axl is a receptor tyrosine kinase and was first identified as a transforming gene in chronic myeloid leukemia. Axl overexpression induces proliferation, migration, and invasion and is highly expressed in different human cancers. In this study, we show that overexpression of MZF1 induces migration and invasion in colorectal (Rko, SW480) and cervical (HeLa) cancer cells. In addition, we show that MZF1 binds to the Axl promoter, transactivates promoter activity, and enhances Axl-mRNA and protein expression in a dose-dependent manner. In vitro, sh-RNA knockdown of Axl reduced MZF1-induced migration and invasion in HeLa and Rko cells (P = 0.05). Additionally, Rko cells overexpressing MZF1 showed increased tumor formation and liver metastasis in the chicken-embryo-metastasis assay in vivo. Furthermore, the expression of MZF1 and Axl was significantly higher in resected colorectal tumors compared with corresponding normal tissues (P = 0.02; P = 0.05), and MZF1 expression was positively correlated with Axl gene expression in tumor tissues (P < 0.01). Taken together, this is the first study to show that MZF1 induces invasion and in vivo metastasis in colorectal and cervical cancer, at least in part by regulating Axl gene expression. Mol Cancer Res; 8(2); 159-69. ©2010 AACR.

Regulation of Axl receptor tyrosine kinase expression by miR-34a and miR-199a/b in solid cancer

“…Axl-mRNA and Axl protein expression significantly inversely correlated with the miR-34a expression, and cell invading capacity positively correlated with Axl protein amounts and inversely with miR-34a expression. In general, our findings strongly support the existing literature that Axl is an oncogene and miR-34a is a tumor suppressor (Hafizi and Dahlback, 2006;Vajkoczy et al, 2006;Bommer et al, 2007;Welch et al, 2007;Mudduluru et al, 2010). Previous studies reported that miR-34a can inhibit cell cycle (CCNE2, CDK4, CDK6, Cyclin E2 and E2F5), anti-apoptotic protein (BCL2) and invasion (MET) inducing genes (Bommer et al, 2007;Chang et al, 2007;He et al, 2007;Raver-Shapira et al, 2007).…”

“…miR-34a is a p53 target gene that presumably mediates induction of apoptosis, cell cycle arrest and senescence by p53. Subsequently, Axl is known to induce migration, invasion and distant metastasis (Vajkoczy et al, 2006;Mudduluru et al, 2010). We now demonstrate that miR-34a and miR199a are potent inhibitors of migration, invasion (H1299, MDA-MB-231 and Rko) and tumor growth and, in vivo distant metastasis by CAM assay (H1299 and Rko).…”

“…The major finding of this study is that three microRNAs, miR-34a, miR-199a, and miR-199b can inhibit the expression and functions of Axl tyrosine kinase, thereby impairing migration, invasion and formation of distant metastasis of cancer cells (Vajkoczy et al, 2006;Mudduluru et al, 2010). As 5-aza treatment was shown to induce the constitutive expression of miR-34a, miR199a, and miR-199b and to inhibit Axl protein expression, we found that miR-34a and miR-199a/b were frequently methylated and that their expression levels significantly inversely correlated with invasive capacity and Axl expression.…”

“…Axl-mRNA levels were induced in H520, Geo and Colo 206f cells, since it is controlled by CpG methylation. However, protein amounts were significantly reduced after 5-aza treatment in all of these cells (Vajkoczy et al, 2006;Mudduluru and Allgayer, 2008;Mudduluru et al, 2010). In general, it implies different stages of controlling mechanisms of a gene, especially of an oncogene.…”

“…Axl is transcriptionally regulated by Sp1/ Sp3 transcription factors and further controlled by CpG island methylation (Mudduluru and Allgayer, 2008). Additionally, overexpression of MZF1 transactivates Axl gene expression and induces migration, invasion and in vivo metastasis formation (Mudduluru et al, 2010). However, little is known about the epigenetic regulation of Axl and especially its post-transcriptional regulation by microRNAs (miRNAs).…”