The use of electronic-cigarettes has increased substantially in recent years among the younger population in particular. The liquid nicotine is the main component of the e-cigarette. Mice exposed to e-cigarette smoke (ECS) generated by heating the liquid nicotine developed lung adenocarcinoma and bladder hyperplasia. This implicated a potential role for ECS/nicotine in cancer development, while the underlying mechanisms remain unclear. Here we report that nicotine reduces the protein level of Stem-loop binding protein (SLBP), a critical factor for the stability, processing and translation of canonical histone pre-mRNAs, in human lung epithelial BEAS-2B cells. It has been known that canonical histone mRNAs typically do not end in a poly(A) tail and that depletion of SLBP results in polyadenylation of canonical histone mRNAs that appeared to be carcinogenic. Indeed, nicotine exposure induced polyadenylation of mRNAs for histones H2A, H2B, H3.1, H3.2, and H4. Interestingly, the inhibitor for nAChRs (nicotinic acetylcholine receptors) reversed nicotine-induced SLBP depletion. Moreover, the depletion of SLBP was attenuated not only by both the inhibitors and siRNAs specific for CDK1/2 and CK2, but also by inhibition of AKT signal pathway. Importantly, nicotine-induced anchorage-independent cell growth was rescued by overexpression of SLBP. These results suggest that activation of nAChR and a series of signal transduction pathways are involved in nicotine-mediated SLBP reduction and they may play an important role in nicotine-induced cell transformation and carcinogenesis.Keywords: Nicotine, Stem-loop binding protein, Cell transformation, nAChR

Citation Format: Qi Sun, Danqi Chen, Chunyuan Jin. Downregulation of Stem-loop binding protein by nicotine and its role in nicotine-induced cell transformation in human lung epithelial cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr LB191.