Tobacco smoking is a major risk factor for human cancers including urinary bladder carcinoma. In a previous study, nicotine enhanced rat urinary bladder carcinogenesis using a rat urinary bladder two-stage carcinogenesis model. In the present study, nicotine metabolites (cotinine, trans-3'-hydroxy cotinine and N'-nitrosonornicotine) were evaluated in a cell proliferation assay using urinary bladder urothelial cell lines. Cotinine (0.1 to 1 mM) induced the highest cell proliferation compared to the others, including nicotine, in three bladder cancer cell lines (RT4, T24 and UMUC3 cells). By Western blot, cotinine induced phosphorylation of Stat3 and expression of cyclin D1 in UMUC3 cells. The cell proliferation induced by cotinine was blocked by inhibitors of nicotinic receptors (10 nM SR16584 or 10 μM methyllycaconitine citrate) and Stat3 (100 nM stattic). In an in vivo study, cotinine (13, 40 and 120 ppm) in drinking water also induced cell proliferation and simple hyperplasia in urinary bladder and renal pelvis urothelium of rats, but to a lesser degree compared to nicotine (40 ppm). Cytotoxicity detected by scanning electron microscopy and apoptosis in the bladder urothelium were induced by nicotine but not cotinine. These data suggest that cotinine is able to induce urothelial cell proliferation both in vitro and in vivo, and high urinary concentrations may enhance urothelial carcinogenesis.

中文翻译：

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可替宁是主要的尼古丁代谢产物，可在体内和体外诱导尿路上皮细胞增殖。

吸烟是包括膀胱癌在内的人类癌症的主要危险因素。在先前的研究中，尼古丁使用大鼠膀胱两阶段癌变模型增强了大鼠膀胱癌的发生。在本研究中，使用膀胱尿路上皮细胞系在细胞增殖试验中评估了尼古丁代谢产物（可宁碱，反式3'-羟基可替宁和N'-硝化尼古丁）。在三种膀胱癌细胞系（RT4，T24和UMUC3细胞）中，可替宁（0.1至1 mM）与包括烟碱在内的其他物质相比诱导了最高的细胞增殖。通过蛋白质印迹，可替宁可诱导UMUC3细胞中Stat3磷酸化和细胞周期蛋白D1的表达。可替宁诱导的细胞增殖被烟碱样受体抑制剂（10 nM SR16584或10μM柠檬酸甲基卡卡尼汀）和Stat3（100 nM静态）阻滞。在一项体内研究中，饮用水中的可替宁（13、40和120 ppm）还诱导了大鼠膀胱和肾盂尿路上皮中的细胞增殖和单纯增生，但程度比尼古丁（40 ppm）低。扫描电子显微镜检测到的细胞毒性和膀胱尿路上皮的凋亡是由烟碱而不是可替宁诱导的。这些数据表明，可替宁在体外和体内均可诱导尿路上皮细胞增殖，而高尿液浓度可增强尿路上皮癌变。饮用水中的40 ppm和120 ppm）也会在大鼠的膀胱和肾盂尿路上皮中诱导细胞增殖和单纯增生，但与尼古丁（40 ppm）相比，其程度较低。扫描电子显微镜检测到的细胞毒性和膀胱尿路上皮的凋亡是由烟碱而不是可替宁诱导的。这些数据表明，可替宁在体外和体内均可诱导尿路上皮细胞增殖，而高尿液浓度可增强尿路上皮癌变。饮用水中的40 ppm和120 ppm）也会在大鼠的膀胱和肾盂尿路上皮中诱导细胞增殖和单纯增生，但与尼古丁（40 ppm）相比，其程度较低。扫描电子显微镜检测到的细胞毒性和膀胱尿路上皮的凋亡是由烟碱而不是可替宁诱导的。这些数据表明，可替宁在体外和体内均可诱导尿路上皮细胞增殖，而高尿液浓度可增强尿路上皮癌变。