Seryl-tRNA synthetase inhibits Wnt signaling and breast cancer progression and metastasis

Tumors require ample protein synthesis to grow, and aminoacyl-tRNA synthetases, as critical translation factors, are expected to support cancer progression. Unexpectedly, overexpression of seryl-tRNA synthetase (SerRS) suppresses primary tumor growth of breast cancer. However, the effects of SerRS on metastasis have not been studied. We observe a decrease in SerRS expression in breast cancer patient metastases compared to matched primary tumors, suggesting an inhibitory role of SerRS in metastasis. Through mouse metastasis models using breast cancer cell lines overexpressing SerRS, we show that SerRS impedes both primary tumor growth and establishment of metastases. By inducing SerRS overexpression after primary tumor implantation, we demonstrate the potential of SerRS as an anticancer therapeutic. Through tumor RNA-Seq, we identify Wnt signaling among the top SerRS-regulated pathways. Using cell-based studies, we confirm SerRS suppresses Wnt signaling and metastatic processes in breast cancer cells. To our knowledge, this is the first study to show a translation factor can act as both a tumor and metastasis suppressor. Overall design: Primary breast tumors of BALB/c mice orthotopically injected with 4T1-tet-on-Luciferase stable mouse breast cancer cell lines (expressing tet-on vector control, mSerRS wild-type, mSerRS AA mutant)