Non-small cell lung cancer (NSCLC) demonstrates a strong etiologic association with smoking. Although nicotine is not carcinogenic, it can induce cell proliferation and angiogenesis and suppress apoptosis induced by certain agents. Here we show that nicotine inhibits apoptosis induced by the drugs gemcitabine, cisplatin, and taxol, which are used to treat NSCLCs. This protection correlated with the induction of XIAP and survivin by nicotine in a panel of human NSCLC cell lines, and depletion of XIAP and survivin ablated the protective effects of nicotine. The antiapoptotic effects of nicotine were mediated by dihydro -erythroidine-sensitive ␣3-containing nicotinic acetylcholine receptors and required the Akt pathway. Chromatin immunoprecipitation assays demonstrated that nicotine stimulation caused an increased recruitment of E2F1 and concomitant dissociation of retinoblastoma tumor suppressor protein (Rb) from survivin promoter in A549 cells. Moreover, ablation of E2F1 levels caused abrogation of the protective effects of nicotine against cisplatin-induced apoptosis in A549 cells whereas ablation of signal transducer and activator of transcription 3 levels had no effect. These studies suggest that exposure to nicotine might negatively impact the apoptotic potential of chemotherapeutic drugs and that survivin and XIAP play a key role in the antiapoptotic activity of nicotine.E2F ͉ retinoblastoma ͉ Stat 3 ͉ IAP ͉ lung cancer C igarette smoking is a major risk factor in the development of non-small cell lung cancer (NSCLC), which accounts for 80% of all lung cancers (1-3). Previous studies have implied that nicotine may be genotoxic, forming adducts with DNA, histone H1͞H3, or H1b, thereby causing mutations in vital genes leading to neoplastic transformation (4, 5). However, recent evidence has shown that nicotine can also lead to sustained activation of mitogenic pathways, promote angiogenesis, and accelerate tumor growth and atherosclerosis (6-13). Nicotine and its related carcinogens, like 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone, have been found to activate Raf-1-, EGFR-, c-Src-, Akt-, and 5-lipooxygenase-mediated growth stimulatory pathways (14-19). In addition, nicotine has been also found to inhibit apoptosis induced by opioids, etoposide, cisplatin, and UV irradiation in lung cancer cells (7,10,14). The inhibitory effect of nicotine on apoptosis has been attributed to its ability to activate and phosphorylate antiapoptotic proteins like Bcl-2, induction of NF-B complexes, activation of the Akt pathway, as well as inactivation of proapoptotic proteins like Bax and Bad through phosphorylation in lung cancer cells (7,(20)(21)(22)(23)(24).NSCLC is characterized by its poor prognosis and resistance to the apoptotic activity of antineoplastic drugs both in vivo and in vitro (25,26). Although many signaling cascades have been implicated in the acquisition of chemoresistance in NSCLC (3, 26, 27), we conjectured that it is probable that the antiapoptotic effects of nicotine contribute to the process. Here we...