The EGFR/miR-338-3p/EYA2 axis controls breast tumor growth and lung metastasis

Dysregulation of the epidermal growth factor receptor (EGFR) promotes cancer cell growth, invasion and metastasis. However, its relevant downstream effectors are still limited. Here, we show that EGFR promotes breast tumor growth and metastasis by downregulating the tumor suppressor micoRNA-338-3p (miR-338-3p) and activating the EYA2 (EYA transcriptional coactivator and phosphatase 2) oncoprotein. EGFR represses miR-338-3p expression largely through HIF1α transcription factor. miR-338-3p inhibits EYA2 expression by binding to the 3'-untranslated region of EYA2. EGFR increases EYA2 expression via HIF1α repression of miR-338-3p. Through the miR-338-3p/EYA2 pathway, EGFR increases breast cancer cell growth, epithelial-to-mesenchymal transition, migration, invasion and lung metastasis in vitro and in a allograft tumor mouse model in vivo. In breast cancer patients, miR-338-3p expression negatively correlates with the expression of EGFR and EYA2, EGFR status positively associates with EYA2 expression, and miR-338-3p and EYA2 predict breast cancer lung metastasis when expressed in primary breast cancers. These data suggest that the miR-338-3p/EYA2 axis contributes to EGFR-mediated tumor growth and lung metastasis and that miR-338-3p activation or EYA2 inhibition or combination therapy targeting EGFR/miR-338-3p/EYA2 axis may be a promising way to treat patients with metastatic cancer.