Expression Of The POU Domain Transcription Factor Oct4 In Human Transitional Carcinoma Tissue Of Bladder And Its Effects On The Biological Behavior Of Human Bladder Cancer Cell Line EJ

Objectives:To study the expression and signifiance of Oct4 in bladder transitional cell carcinoma(BTCC)and to investigate the effects of small interference RNA(siRNA)silencing Oct4 on the biological behavior of human bladder cancer cell line EJ. Methods:Immunohistochemisty and Real-time RT-PCR were used to detect the expression of Oct4 in 74 cases of BTCC tissues,32 cases of pericarcinomatousetissues and 24 cases of normal bladder tissues ;EJ cells were divided into three groups: the blank control group,the negative control group,the Oct4-siRNA group. Chemically synthesized small interfering RNA targeting Oct4(Oct4 - siRNA)was transfected into the h human bladder cancer cell line EJ which have high metastatic potential by lipofectamin 2000. RT- PCR and western blot were used to semi- quantify the Oct4 mRNA and protein levels. Then proliferation of EJ cells was determined by MTT assay, Acridine orange-ethidium bromide(AO/EB) fluorescent staining were performed for detecting cell apoptosis, The activities of invasion and motility of EJ cell were assessed by cell wound model and Transwell chamber invasion assay in vitrol effectively. Results:The immunohistochemisty revealed that the expression of Oct4 in BTCC were much higher than those in pericarcinomatouse tissues and normal bladder tissues(P<0.05), The positive rate of Oct4 of each group was 83.78%,21.87%,0%,among the pathological grades,G1,G2,G3, respectively was 66.67%,87.50% ,100%, The positive rate of Oct4 in the two groups which with lymphatic metastasis and negative lymphatic metastasis was92.3%,79.1%. Moreover, with the advancing grades and appearances of lymph node metastasis,the expression of Oct4 increased gradually,There were significant differences in each group(P<0.05);The Real-time RT-PCR showed that the expression of Oct4 in BTCC were much higher than those in pericarcinomatouse tissues and normal bladder tissues(P<0.05),But the expression of Oct4 were not significantly different with each clinical stages (P>0.05);In the Oct4- siRNA group ,The Oct4mRNA and protein levels were down-regulated remarkably (P<0.05), the abilities of proliferation were inhibited, the motility,invation of EJ cellswere inhibited significantly(15. 34±1. 8 vs 63. 07±1. 73) in vitro. The rate of apoptosis increased notablely (52.73% vs 11.7%)compared with the negative control group(P<0.05). Conclusion:The positive expressions of Oct4 closely related to the pathology and metastasis of lymph node of the cancer but not clinical stages .The over expression of Oct4 may plays an important role in carcinogenesis and progress of BTCC ;Silencing Oct4 could regulate the malignant biological behaviors of bladder cancer cell line EJ effectively.