HPV E6 antisense induces apoptosis in CaSki cells via suppression of E6 splicing.

Cheong Weon Cho,Yong Keun Jung,Haryoung Poo,Young Il Yeom,Young Sik Cho,Min Chul Cho,Sue Nie Park,Kyung Ae Lee,In Seong Choe,Shin Je Lee,Yong Kyung Choe,Do Young Yoon,In Ki Kim

doi:10.1038/emm.2002.23

Abstract

Cervical cancer is known to be highly associated with viral oncogene E6 and E7 of human papilloma virus. Down-regulation of oncogene expression by antisense-based gene therapy has been extensively studied. To investigate the effect of HPV 16 E6 antisense nucleic acid (AS) on cervical cancer cells, human cervical cancer cell lines, CaSki and SiHa cells harboring HPV 16 genome were transfected with plasmid containing E6(AS). The decreased viability and the apoptotic morphology were observed in E6(AS)-transfected cervical cancer cell lines. By 6 h after transfection, inhibition of E6 splicing, rapid upregulations of p53 and a p53-responsive protein, GADD45, were displayed in E6(AS)-transfected CaSki cells. Furthermore, E6(AS) induced loss of mitochondrial transmembrane potential, release of mitochondrial cytochrome c into the cytoplasm, and subsequent activation of caspase-9 and caspase-3. These results indicate that HPV 16 E6(AS) induces apoptosis in CaSki cells via upregulation of p53 and release of cytochrome c into cytoplasm, consequently activating procaspase-9 and procaspase-3.

Highlights

Cervical cancer has been reported to be highly associated with viral oncogene E6 and E7 of human papillomavirus (HPV)
To test the effect of HPV 16 E6 antisense nucleic acid on the transcription of E6 and the viability of cervical cancer cells, cervical carcinoma cells were transfected with HPV 16 E6(AS) constructed in pTarget plasmid, respectively
Transcripts of E6 and E7 were detected in CaSki cells after treatment of antisense nucleic acids of HPV 16 by RT-polymerized chain reaction (PCR) (Figure 1)

Summary

Introduction

Cervical cancer has been reported to be highly associated with viral oncogene E6 and E7 of human papillomavirus (HPV). The repressed level of oncogene expression through the use of anti-sense RNA or antisense oligodeoxynucleotides may offer a new way to modify some genetic traits at the somatic level controlled by these oncogenes and possibly related to the maintenance of the transformed phenotype (Paoletti, 1988). One of these approaches is to develop an antisense and/or ribozyme strategy to inhibit E6 and E7 gene expression in cervical cancers to reverse the malignant phenotype (He and Huang, 1997).

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Conclusion