A novel four‑gene biomarker for tobacco smoking -induced colorectal cancer progression.

INTRODUCTION: Cigarette smoking greatly promotes the progression and poor prognosis of colorectal cancer (CRC) patients, with the molecular mechanism still not fully clear.

METHODS: In this study, CRC cells were exposed to tobacco specific nitrosamine 4‑(methylnitrosamino)‑1‑(3‑pyridyl) 1‑butanone (NNK), and the differentially expressed smoking-related genes were identified based on both NNK-induced CRC cells and a total of 763 CRC tissues from TCGA cohort. Cox regression analysis, ROC curve and Kaplan-Meier plot were used to establish the risk score model for CRC prognosis. Moreover, qRT-PCR, western blotting, colony formation, migration and invasion assays were performed to verify the core differentially expressed smoking-related gene and its molecular function in NNK-induced CRC progression.

RESULTS: Results indicated NNK significantly enhanced CRC cell proliferation, migration and invasion. Moreover, a four-gene signature containing AKR1B10, CALB2, PLAC1, GNA15 was established as CRC prognosis marker. Among these four genes, AKR1B10 was further validated as the core gene, and its expression was significantly inhibited after NNK exposure in CRC cells. Results of gene enrichment analysis and western blotting suggested AKR1B10 might reduce the malignant progression of NNK-induced CRC cells through inhibiting Wnt signaling pathway by promoting E-Cadherin expression and inhibiting the expression of N-Cadherin, β-Catenin, Vimentin and Snail.

CONCLUSION: In conclusion, a new four smoking-related genes can be jointly used as prognostic markers for CRC. AKR1B10 served as a tumor suppressor, can be used as a potential target to inhibit NNK-induced CRC malignant progression through regulating Wnt signaling pathway.

IMPLICATIONS: This study demonstrates tobacco-derived NNK dependence would promote the malignant progression of colorectal cancer through regulating the expressions of AKR1B10/Wnt signaling pathway. And a novel four-gene signature is established for the prognosis prediction of smoking CRC patients. These findings have important translational implications given the continued use of tobacco and the difficulty in smoking cessation worldwide, which can be applied to alleviate the adverse effects induced by tobacco dependence on colorectal cancer patients.