Yuan Jingsong, Ma Jinfang, Zheng Hongwei, Shi Taiping, Sun Wenyue, Zhang Qiao, Lin Dongmei, Zhang Kaitai, He Jie, Mao Yousheng, Gao Xia, Gao Peng, Han Naijun, Fu Guobin, Xiao Ting, Gao Yanning, Ma Dalong, Cheng Shujun
Department of Chemical Etiology and Carcinogenesis, Cancer Institute & Hospital, Peking Union Medical College and Chinese Academy of Medical Sciences, Beijing, People's Republic of China.
J Natl Cancer Inst. 2008 Nov 19;100(22):1592-605. doi: 10.1093/jnci/djn379. Epub 2008 Nov 11.
Exposure to cigarette smoke is a major risk factor for lung cancer, but how it induces cancer is unclear. The overexpressed in lung cancer 1 (OLC1) gene is one of 50 candidate lung cancer genes identified by suppression subtractive hybridization as having higher expression in squamous cell carcinoma (SCC) than normal lung epithelia.
We used immunohistochemistry (IHC) to measure OLC1 protein levels in primary lung cancer samples from 559 patients and used fluorescence in situ hybridization to measure OLC1 copy number in primary SCC samples from 23 patients. We compared OLC1 protein expression in SCC samples of 371 patients with and without a smoking history using the Pearson chi(2) test. We assayed OLC1 protein levels by immunoblotting in H1299 human lung cancer cells, immortalized human bronchial epithelial cells, and primary cultured normal human bronchial epithelial cells that were treated with cigarette smoke condensate. We assayed tumor formation in athymic mice using NIH3T3 mouse fibroblast cells transfected with OLC1 (eight mice) and analyzed apoptosis and colony formation of H1299 and H520 lung cancer cells transfected with scrambled (negative) or OLC1 small interfering RNAs (siRNAs) (s1).
OLC1 protein was overexpressed in 387 of 464 (83.4%) of primary lung cancers, as detected by IHC, and OLC1 was amplified in 14 of 23 (60%) of SCC samples. OLC1 protein overexpression was more common in SCC patients with a smoking history than those without (77.1% vs 45.8%, P < .001). In addition, cigarette smoke condensate increased OLC1 protein levels in H1299 cells, immortalized human bronchial epithelial cells, and primary cultured normal human bronchial epithelial cells. Overexpression of OLC1 induced tumor formation in athymic mice (control vs OLC1, 0% vs 100%). Knockdown of OLC1 increased apoptosis (mean percentage of apoptotic H1299 cells, s1 vs negative: 30.3% vs 6.4%, difference = 23.9%, 95% confidence interval [CI] = 19.1% to 28.5%, P = .002; mean percentage of apoptotic H520 cells, s1 vs negative: 21.6% vs 4.9%, difference = 16.7%, 95% CI = 10.6% to 22.8%, P = .007) and decreased colony formation (mean no. of colonies of H1299 cells transfected with siRNAs, negative vs s1: 84 vs 4, difference = 80, 95% CI = 71 to 88, P < .001; mean no. of colonies of H520 cells transfected with siRNAs, negative vs s1: 103 vs 24, difference = 79, 95% CI = 40 to 116, P = .005).
OLC1 is a candidate oncogene in lung cancer whose expression may be regulated by exposure to cigarette smoke.
接触香烟烟雾是肺癌的主要危险因素，但它如何诱发癌症尚不清楚。肺癌过表达1（OLC1）基因是通过抑制性消减杂交鉴定出的50个候选肺癌基因之一，在鳞状细胞癌（SCC）中的表达高于正常肺上皮细胞。
我们使用免疫组织化学（IHC）检测559例原发性肺癌样本中的OLC1蛋白水平，并使用荧光原位杂交检测23例原发性SCC样本中的OLC1拷贝数。我们使用Pearson卡方检验比较了371例有吸烟史和无吸烟史的SCC患者样本中的OLC1蛋白表达。我们通过免疫印迹法检测了用香烟烟雾冷凝物处理的H1299人肺癌细胞、永生化人支气管上皮细胞和原代培养的正常人支气管上皮细胞中的OLC1蛋白水平。我们使用转染了OLC1的NIH3T3小鼠成纤维细胞检测无胸腺小鼠的肿瘤形成（8只小鼠），并分析了转染了乱序（阴性）或OLC1小干扰RNA（siRNA）（s1）的H1299和H520肺癌细胞的凋亡和集落形成情况。
通过免疫组织化学检测，464例原发性肺癌中有387例（83.4%）OLC1蛋白过表达，23例SCC样本中有14例（60%）OLC1扩增。有吸烟史的SCC患者中OLC1蛋白过表达比无吸烟史的患者更常见（77.1%对45.8%，P <.001）。此外，香烟烟雾冷凝物增加了H1299细胞、永生化人支气管上皮细胞和原代培养的正常人支气管上皮细胞中的OLC1蛋白水平。OLC1的过表达在无胸腺小鼠中诱导肿瘤形成（对照组对OLC1组，0%对100%）。敲低OLC1增加了凋亡（凋亡的H1299细胞的平均百分比，s1组对阴性组：30.3%对6.4%，差异 = 23.9%，95%置信区间[CI] = 19.1%至28.5%，P =.002；凋亡的H520细胞的平均百分比，s1组对阴性组：21.6%对4.9%，差异 = 16.7%，95% CI = 10.6%至22.8%，P =.007）并减少了集落形成（转染siRNA的H1299细胞的平均集落数，阴性组对s1组：84对4，差异 = 80，95% CI = 71至88，P <.001；转染siRNA的H520细胞的平均集落数，阴性组对s1组：103对24，差异 = 79，95% CI = 40至116，P =.005）。
OLC1是肺癌中的一个候选癌基因，其表达可能受接触香烟烟雾的调节。
