In vitro antigene therapy targeting HPV-16 E6 and E7 in cervical carcinoma

Human papillomavirus (HPV) infection is believed to play a central role in cervical carcinogenesis. Specifically, two viral oncoproteins, E6 and E7, possess transforming ability and have been shown to interact with the cellular tumor suppressors p53 and p105, the retinoblastoma (Rb) gene product. To...

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Published in:Gynecologic oncology 1997, Vol.64 (1), p.18-25
Main Authors: MADRIGAL, M, JANICEK, M. F, SEVIN, B.-U, PERRAS, J, ESTAPE, R, PENALVER, M, AVERETTE, H. E
Format: Article
Language:English
Subjects:
Antigens, Viral - therapeutic use
Biological and medical sciences
Dose-Response Relationship, Drug
Female
Female genital diseases
Gynecology. Andrology. Obstetrics
Humans
Medical sciences
Oligonucleotides, Antisense - therapeutic use
Oncogene Proteins, Viral - genetics
Papillomaviridae - genetics
Papillomaviridae - immunology
Papillomavirus E7 Proteins
Repressor Proteins
Thionucleotides - therapeutic use
Tumor Cells, Cultured
Tumors
Uterine Cervical Neoplasms - therapy
Uterine Cervical Neoplasms - virology
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Summary:Human papillomavirus (HPV) infection is believed to play a central role in cervical carcinogenesis. Specifically, two viral oncoproteins, E6 and E7, possess transforming ability and have been shown to interact with the cellular tumor suppressors p53 and p105, the retinoblastoma (Rb) gene product. To test the hypothesis that E6 and E7 play an active role in the maintenance of the malignant phenotype and may be ideal targets for antigene therapy, we tested the antiproliferative effects of phosphorothioate oligodeoxynucleotides (oligos) targeting HPV-16 E6 and E7 in cervical cancer cell lines and primary tumor explants. The ATP cell viability assay was used to measure growth effects of 27-mer antisense oligos targeting the ATG translational start region of HPV-16 E6 and E7 sequences in HPV-16-positive cell lines SiHa and CaSki and four advanced, primary cervical tumor explants. A random oligo sequence, an HPV-18-positive and HPV-negative cell line, one histologically confirmed endometrial and two ovarian tumors were used as negative controls. HPV type was confirmed by hybrid capture techniques. Cell lines and sterile (staging laparotomy) tumor cells were plated at 5000 cells/0.1 ml and 100,000 cells/0.5 ml in 96-well plates or soft agar, respectively, and incubated at 37 degrees C with a single treatment of oligos at 0-16 microM. E6/E7 combinations at a fixed ratio of 1:1 were used at 0-8 microM for each oligo. Cellular ATP was measured by luciferin/luciferase fluorescence on Day 6. HPV-16 E6 and E7 oligos showed antiproliferative effects in all HPV-16-positive cell lines and primary tumor explants (IC50s 6.9-9.5 microM for cell lines, 9.1-12.1 microM primary cervical tumors), while the HPV-negative C33-A cell line and HPV-18-positive cell line HeLa were relatively insensitive to the HPV-16 oligos (IC50s > 30 microM extrapolated). The endometrial and two ovarian primary tumors were also insensitive to the HPV E6 and E7 oligos (IC50s > 25 microM extrapolated). Random oligos had little effect on cell growth at concentrations up to 16 microM (< 25% inhibition), except in CaSki (@50% inhibition at 16 microM). Combinations of E6 and E7 demonstrated mixed synergistic and antagonistic effects as determined by combination indices (CI) derived from median effect parameters. In the HPV-16-positive primary cervical tumors and the cell line SiHa, E6/E7 combinations were synergistic at low doses (< 25% growth inhibitory dose range) and antagonistic at doses above this. Fo
ISSN:0090-8258
1095-6859
DOI:10.1006/gyno.1996.4515