Zuo Ze-Hua, Zhao Min, Liu Juan, Wei Yun, Wu Xin-Xing
Department of Molecular Virology, Institute of Virology, Medical School of Wuhan University, Wuhan, Hubei, 430071, P. R. China.
Ai Zheng. 2006 Jul;25(7):811-7.
BACKGROUND & OBJECTIVE: Bladder cancer related protein (BLCAP) gene was found downregulated most in primary cervical cancer tissues using oncogene/tumor suppressor gene microarray screening in our previous study, therefore this study was to explore the possible correlation between BLCAP gene and cervical cancer.
BLCAP expression was investigated in 54 cervical cancer and 25 normal tissues by reverse transcription polymerase chain reaction (RT-PCR). Full length of BLCAP cDNA was cloned into pLXSN expression vector and stably transfected into cervical cancer cell line HeLa cells. Cell proliferation, colony formation ability and apoptosis were determined by cell number counting, colony formation and DNA ladder assay. Nude mice were used to study the anti-tumor effect of BLCAP gene in vivo.
BLCAP gene expression was significantly down-regulated or even not observed in human cervical cancer tissues compared to the normal ones. The cell doubling time of HeLa cells transfected with BLCAP was significantly elevated to 69.4 hrs (P<0.05), compared to that of the parental cells (27.5 hrs) or cells transfected with empty vectors (30.2 hrs). Moreover, in comparison with control cells, the colony formation efficiency of cells transfected with BLCAP gene was significantly lower (t=5.98, P<0.01). BLCAP expression also sensitized Hela cells to apoptosis induced by serum deprivation. In vivo, smaller size of tumors were formed in mice after the injection of cells transfected with BLCAP for 30 days compared to those injected with parental cells or cells transfected with empty vector (tumor wet weights were 1.015 g, 1.612 g, and 1.530 g, respectively, P<0.05). Furthermore, under pathological examinations, tumor tissues formed by cells transfected with BLCAP gene displayed less invasive potential with integral vascular fibrous capsules; muscle or adipocyte tissue invasion was not observed. In comparison, necropsy revealed that the tumors formed from the control cells were attached to the underlying muscles; histologically, the neoplastic cells were locally invasive and associated with fibrous connective tissues. These cells exhibited severer cytoplasmic and nuclear pleomorphism compared to cells transfected with BLCAP.
BLCAP gene is down-regulated in cervical carcinoma tissues and could suppress tumorigenic ability and growth of HeLa cells, thus it may be a potential suppressor candidate gene of cervical carcinoma.
在我们之前的研究中，通过癌基因/抑癌基因芯片筛选发现，膀胱癌相关蛋白（BLCAP）基因在原发性宫颈癌组织中下调最为明显，因此本研究旨在探讨BLCAP基因与宫颈癌之间可能存在的相关性。
采用逆转录聚合酶链反应（RT-PCR）检测54例宫颈癌组织和25例正常组织中BLCAP的表达情况。将BLCAP cDNA全长克隆到pLXSN表达载体中，并稳定转染至宫颈癌HeLa细胞系。通过细胞计数、集落形成和DNA梯状条带分析来测定细胞增殖、集落形成能力和细胞凋亡情况。利用裸鼠研究BLCAP基因在体内的抗肿瘤作用。
与正常组织相比，BLCAP基因在人宫颈癌组织中显著下调甚至未检测到。转染BLCAP的HeLa细胞倍增时间显著延长至69.4小时（P<0.05），而亲本细胞为27.5小时，转染空载体的细胞为30.2小时。此外，与对照细胞相比，转染BLCAP基因的细胞集落形成效率显著降低（t=5.98，P<0.01）。BLCAP表达还使HeLa细胞对血清剥夺诱导的凋亡更加敏感。在体内，注射转染BLCAP的细胞30天后，小鼠形成的肿瘤体积比注射亲本细胞或转染空载体的细胞更小（肿瘤湿重分别为1.015克 vs 1.612克和1.530克，P<0.05）。此外，病理检查显示，转染BLCAP基因的细胞形成的肿瘤组织侵袭潜力较小，有完整的血管纤维包膜；未观察到肌肉或脂肪组织浸润。相比之下，尸检发现对照细胞形成的肿瘤与下方肌肉相连；组织学上，肿瘤细胞呈局部浸润性生长，并与纤维结缔组织相关。与转染BLCAP的细胞相比，这些细胞表现出更严重的细胞质和细胞核多形性。
BLCAP基因在宫颈癌组织中表达下调，可抑制HeLa细胞的致瘤能力和生长，因此它可能是宫颈癌潜在的抑癌候选基因。
