Reduced miR-34a expression in normal cervical tissues and cervical lesions with high-risk human papillomavirus infection.
BACKGROUND
Reduced miR-34a expression is associated with high-risk human papillomavirus (HR-HPV) infection and cervical cancer. Whether the reduction of miR-34a expression induced by HR-HPV E6 occurs in precancerous lesions, even before morphologic change, is still uncertain. Our study aimed to ascertain the possibility of pri-miR-34a involved in the development of cervical lesions and to explore the mechanism of altered pri-miR-34a expression induced by HPV-16 E6.


METHODS
The levels of pri-miR-34a expression were examined in different cervical tissues, including normal cervical epithelium with (n = 32) or without (n = 32) HR-HPV infection, cervical intraepithelial neoplasia (CIN) with (n = 32) or without (n = 12) HR-HPV infection, and cervical cancer (n = 32), by semiquantitative reverse transcription-polymerase chain reaction. The HPV-16 E6 expression vector and HPV-16 E6 small interfering RNAs were conducted and transfected into 293T cells and SiHa cells, respectively. The expression of pri-miR-34a and p53 protein was simultaneously analyzed by reverse transcription-polymerase chain reaction and Western blot in cells with gene transfection and without.


RESULTS
pri-miR-34a expression was significantly reduced in CIN and cervical cancer compared with normal cervical epithelium, as well as in CIN 2 and CIN 3 compared with CIN I. Moreover, the expression of pri-miR-34a was significantly lower in normal cervical epithelium and CIN with HR-HPV infection than in those without. Simultaneous down-regulation or up-regulation of pri-miR-34a and p53 expression was observed in E6-transfected 293T cells or E6 small interfering RNA-transferred SiHa cells compared with controls.


CONCLUSIONS
Reduced expression of pri-miR-34a occurs not only in cervical cancer but also in precancerous lesion even before morphologic change. The inhibition of miR-34a expression induced by HR-HPV E6 in the p53-dependent pathway is probably an early-onset event in the development of cervical cancer.
Li
Baohua
B
Women's Reproductive Health Key Laboratory of Zhejiang Province, Women's Hospital, School of Medicine, Zhejiang University, Hangzhou, China.
Hu
Ying
Y
Ye
Feng
F
Li
Yang
Y
Lv
Weiguo
W
Xie
Xing
X
D000328:Adult; D014408:Biomarkers, Tumor / Q000235:genetics*; D015153:Blotting, Western; D002478:Cells, Cultured; D002584:Cervix Uteri / Q000378:metabolism / Q000473:pathology; D004279:DNA, Viral / Q000235:genetics; D005260:Female; D052162:Human papillomavirus 16 / Q000235:genetics / Q000302:isolation & purification; D006801:Humans; D035683:MicroRNAs / Q000235:genetics*; D009856:Oncogene Proteins, Viral / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism; D030361:Papillomavirus Infections / Q000235:genetics* / Q000821:virology; D016133:Polymerase Chain Reaction; D011230:Precancerous Conditions / Q000235:genetics / Q000821:virology; D011379:Prognosis; D012333:RNA, Messenger / Q000235:genetics; D034741:RNA, Small Interfering / Q000494:pharmacology; D012097:Repressor Proteins / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015996:Survival Rate; D016159:Tumor Suppressor Protein p53 / Q000235:genetics; D002583:Uterine Cervical Neoplasms / Q000235:genetics* / Q000821:virology*; D002578:Uterine Cervical Dysplasia / Q000235:genetics* / Q000821:virology*
D014408:Biomarkers, Tumor; D004279:DNA, Viral; C068651:E6 protein, Human papillomavirus type 16; C522425:MIRN34 microRNA, human; D035683:MicroRNAs; D009856:Oncogene Proteins, Viral; D012333:RNA, Messenger; D034741:RNA, Small Interfering; D012097:Repressor Proteins; C495901:TP53 protein, human; D016159:Tumor Suppressor Protein p53