NK4基因转染对裸鼠胰腺癌移植瘤生长的影响

Effect of NK4 Gene Transfection on Tumor Growth of Human Pancreatic Cancer Xenograft in Nude Mice

背景与目的:NK4不仅是肝细胞生长因子的拮抗剂,而且是血管形成的抑制剂。研究已经证实NK4可以抑制肿瘤的生长和转移,但有关其在胰腺癌中的作用,目前少见文献报道。为此,本研究旨在探讨NK4基因在裸鼠体内的抗胰腺癌作用及其可能的机制。方法:建立裸鼠胰腺癌皮下移植瘤模型,构建NK4基因真核细胞表达载体并转染入瘤体内,转染前后称其体重、瘤重和测肿瘤体积,采用免疫组织化学和脱氧核糖核酸末端转移酶介导的缺口末端标记技术对裸鼠胰腺癌组织中的凋亡细胞、增殖抗原和微血管密度进行观察和比较。结果:4周后,NK4转染组裸鼠移植瘤体积为(1.39±0.33)cm3,明显小于对照组和空载体组[(2.06±0.55)cm3和(1.90±0.36)cm3,P<0.01];其瘤重为(1.30±0.81)g,也显著低于对照组和空载体组[(3.45±1.88)g和(3.14±1.51)g,P<0.01],抑瘤率为62.29%。NK4转染组肿瘤细胞的凋亡指数为9.34±0.91,显著高于对照组和空载体组(4.13±0.79和3.94±1.03,P<0.001);而NK4转染组肿瘤细胞的增殖指数为53.88±4.30,与对照组间和空载体组比较无显著性差异(56.24±4.03和54.33±5.41,P>0.05);NK4转染组肿瘤组织的微血管密度为(12.24±4.63),明显低于对照组和空载体组(20.13±7.00和19.70±6.15,P<0.05)。结论:转染NK4基因可显著抑制裸鼠胰腺癌移植瘤的生长,其作用机制可能是通过抑制肿瘤新生血管的形成,促进肿瘤细胞凋亡。

BACKGROUND ＆ OBJECTIVE： NK4 is not only an antagonist of hepatocyte growth factor but also an angiogenesis inhibitor. Studies have confirmed that NK4 can inhibit tumor growth and metastasis, but its effect on pancreatic cancer remains unknown. This study was designed to observe the effect of NK4 gene on human pancreatic cancer in nude mice and the possible mechanisms. METHODS： The nude mouse model of pancreatic cancer was established with human pancreatic cancer cell line SW1990. The eukaryotic expression vector of NK4 gene was constructed and transfected into the tumors. The mice weight, tumor size and volume were measured before and after transfection. The apoptotic cells, microvessel density （MVD）, and the expression of proliferating cell nuclear antigen （PCNA） in the tumors were observed using immunohistochemistry and terminal deoxynucleotidyt transferase mediated dUTP nick end labeling （TUNEL） technique. RESULTS： Four weeks after NK4 gene transfection, the tumor volume and weight was significantly smaller in NK4-transfected group than in PBS control group and empty vector group [（1.39±0.33） cm3 vs. （2.06±0.55） cm^3 and （1.90±0.36） cm% P〈0.01; （1.30±0.81） g vs. （3.45±1.88） g and （3.14±1.51） g, P〈0.01]; the inhibition rate was 62.29%. The tumor cell apoptotic index was significantly higher in NK4-transfected group than in the rest 2 groups （9.34±0.91 vs. 4.13±0.79 and 3.94±1.03, P〈0.001）; the MVD was significantly lower in NK4-transfected group than in the rest 2 groups （12.24±4.63 vs. 20.13±7.00 and 19.70±6.15, P〈0.05）; the expression of PCNA in NK4-transfected group was not different from those of the rest 2 groups （53.88±4.30 vs. 56.24±4.03 and 54.33±5.41, P〉0.05）. CONCLUSION： NK4 gene transfection may inhibit the growth of human pancreatic cancer in mouse model through suppressing angiogenesis and enhancing the apoptosis of pancreatic cancer ceils.