LMX1A inhibits C-Myc expression through ANGPTL4 to exert tumor suppressive role in gastric cancer.

Abstract

Our research group has showed that the LIM homeobox transcription factor 1 alpha (LMX1A) is inactivated in gastric cancers. Overexpression of LMX1A inhibits tumor growth. However, the mechanisms remains unclear. Considering LMX1A as a transcription factor, a comparison of RNA-seq between gastric cancer cells (GCCs) and GCCs with LMX1A overexpressed was performed to identify genes transcriptionally activated by LMX1A. Among the potential LMX1A target genes, angiopoietin-like 4 (ANGPTL4) has been reported to be an important tumor suppressor and thus was selected for further validation and research. Both LMX1A and ANGPTL4 showed downregulated expression in gastric cancer samples. More importantly, the expression of LMX1A is positively correlated with ANGPTL4, without including other family members in gastric cancer cell lines. What's more, knockdown of ANGPTL4 rescued the tumor suppressive phenotype of LMX1A overexpression, which indicated that LMX1A upregulates ANGPTL4 to exert its role. Mechanistically, we found that LMX1A inhibited the expression of the oncogene C-Myc, which is alleviated by ANGPTL4 knockdown. In general, our results showed that LMX1A exerts its tumor suppressive role by activating ANGPTL4 to inhibit C-Myc.