CYP3A5 Interacts with ATOH8 and Suppresses Metastasis via BMP/Smad1 Pathway in Lung Adenocarcinoma

Abstract

Background: Our previous work demonstrated the CYP3A5 gene as a novel tumor suppressor of hepatocellular carcinoma via the metabolic mechanism, however, the comprehensive understandings of the role of CYP3A5 in human pan-cancers are still limited. Here, we elaborate a novel mechanism of CYP3A5 for restraining the metastasis in lung adenocarcinoma(LUAD). Method: The expression of CYP3A5 were examined by RT-PCR, western blot and IHC in clinical samples and cell lines. The biological function of CYP3A5 in lung adenocarcinoma and the potential mechanisms were investigated in vitro and in vivo models. Results: Using the bioinformatics approach, we detected that CYP3A5 showed generally decreasing expression in multi-cancers across TCGA and the GEO datasets, especially in LUAD, and CYP3A5 was adversely correlated with TNM stage and predicted poor disease-free and overall survival. Invasion and migration assays demonstrated that ectopic expression of CYP3A5 could substantially inhibit the capacity of metastasis in vitro. When administered to mice xenograft with ectopic expression of CYP3A5 cells, we observed a significant reduction in metastatic compartments compared to the controls. Moreover, over-expression of CYP3A5 induced significant inhibition of phosphorylation of Smad1, resulting in suppression of metastasis. Cross rescue assay confirmed that CYP3A5 elicited the metastasis depending on the activity of the Smad1. Co-IP experiments further uncovered that CYP3A5 could interact with ATOH8, and the interaction, in turn, mediated in-activation in the Smad1 pathway. The combined IHC panel, including CYP3A5 and phosphorylation of Smad1, exhibited a better prognostic value for LUAD patients than any of these components individually. Conclusion: Our findings suggested that CYP3A5 served as a suppressor in metastasis of LUAD via ATOH8-mediated BMP/Smad1 pathway, which provided a promising therapeutic target in the treatment of metastatic LUAD. Funding Statement: This work was supported by the National Natural Science Foundation of China (Nos. 81372321, 81472702, 81501977, 81672294), Natural Science Foundation of Jiangsu Province (grant number: SBK016030028), and the Innovation Capability Development Project of Jiangsu Province (No. BM2015004). Declaration of Interests: The authors declared no conflicts of interest in this work. Ethics Approval Statement: This study was approved by the Nanjing Medical University affiliated Cancer Hospital Research Ethics Committee. Care of the laboratory animals and animal experimentation were carried out in accordance with the animal ethics guidelines and approved protocols of Nanjing Medical University Affiliated Cancer Hospital.