Induction of apoptosis in cervical carcinoma cells by peptide aptamers that bind to the HPV‐16 E7 oncoprotein

Nauenburg, Sonja; Zwerschke, Werner; Jansen‐Dürr, Pidder

doi:10.1096/fj.00-0604fje

Cited by 43 publications

(23 citation statements)

References 52 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The present results suggest that decreased expression of E7 likely participates in the decreased viability of HPV-positive tumor cells. Nauenburg et al (2001) have shown that E7-binding peptide aptamers induced apoptosis in E7-expressing cells, whereas E7-negative cells were not affected. However, how E6/E7 transcription is downregulated by ST remains to be characterized.…”

Section: Discussionmentioning

confidence: 97%

Human papillomaviruses type 16+ and 18+ cervical carcinoma cells are sensitive to staurosporine‐mediated apoptosis

Bernard¹,

Prétet²,

Charlot³

et al. 2003

Biology of the Cell

View full text Add to dashboard Cite

We have recently shown that staurosporine (ST) can trigger apoptosis of CaSki and HeLa cervical tumor cells from G2/M checkpoint, though the mechanism remains elusive. In this study, we reported that ST induced the inhibition of E6 and E7 viral oncogene and MDM2 expression, while it led to increased levels of p53, which was transiently located to mitochondria. Additionally, the proteins of the p53-regulated genes, p21 WAF1 and Bax, were increased with a similar time, while Bcl-2 and Bcl-X L expression was lowered. Upon ST treatment, the cytochrome c was released into the cytosol and, then, activation of caspases-9 and -3 led to Poly(ADP)RibosePolymerase (PARP) cleavage. Finally, characteristic morphological signs confirmed the apoptosis execution. Thus, taken together, all these observations suggest that apoptosis can be reactivated in HPV-positive human carcinoma cells and highlight that ST could be used as a potently chemotherapy agent to enhance the sensitivity of tumor cells to apoptosis.

show abstract

Section: Discussionmentioning

confidence: 97%

Human papillomaviruses type 16+ and 18+ cervical carcinoma cells are sensitive to staurosporine‐mediated apoptosis

Bernard¹,

Prétet²,

Charlot³

et al. 2003

Biology of the Cell

View full text Add to dashboard Cite

show abstract

“…It has been shown that expression of HPV-16 E7 induces apoptosis in human fibroblasts and keratinocytes (1,20,44,51) and in the lens of transgenic mice (22,33). However, E7 has also been found to inhibit apoptosis induced by TNF-␣ in human fibroblasts (46), and E7-binding peptide aptamers induced apoptosis in cervical cancer cells (32). According to our results, differences in the level of E7 protein expressed in the various systems used for those studies may provide an explanation for such discrepancies.…”

Section: Vol 77 2003 Enhanced Expression Of Hpv-16 E7 By Codon Optimentioning

confidence: 99%

A Synthetic E7 Gene of Human Papillomavirus Type 16 That Yields Enhanced Expression of the Protein in Mammalian Cells and Is Useful for DNA Immunization Studies

Cid-Arregui

Juarez

Hausen

2003

J Virol

107

View full text Add to dashboard Cite

A synthetic E7 gene of human papillomavirus (HPV) type 16 was generated that consists entirely of preferred human codons. Expression analysis of the synthetic E7 gene in human and animal cells showed levels of E7 protein 20-to 100-fold higher than those obtained with wild-type E7. Enhanced expression of E7 protein resulted from highly efficient translation, as well as increased stability of the E7 mRNA due to its codon optimization. Higher levels of E7 protein in cells transfected with synthetic E7 correlated with significant loss of cell viability in various human cell lines. In contrast, lower E7 protein expression driven by the wild-type gene resulted in a slight induction of cell proliferation. Furthermore, mice inoculated with plasmids expressing the synthetic E7 gene produced significantly higher levels of E7 antibodies than littermates injected with wild-type E7, suggesting that synthetic E7 may be useful for DNA immunization studies and the development of genetic vaccines against HPV-16. In view of these results, we hypothesize that HPVs may have retained a pattern of G ؉ C content and codon usage distinct from that of their host cells in response to selective pressure. Thus, the nonhuman codon bias may have been conserved by HPVs to prevent compromising viability of the host cells by excessive viral early protein expression, as well as to evade the immune system.Human papillomaviruses (HPVs) are small double-stranded-DNA viruses that infect stratified epithelia and cause benign and malignant proliferative lesions. A subset of HPVs with mucosal tropism, the so-called "high-risk" HPVs, has been linked to cancers of the uterine cervix (55), which account for about 11% of the global cancer incidence in women. Of these, more than 90% contain HPV DNA, most notably HPV type 16 (HPV-16) and HPV-18, integrated into the host cell genome, where they express two viral early genes, E6 and E7, whose products block p53 and retinoblastoma protein-mediated cell cycle control pathways (38,56). Indeed, the tumorigenic phenotype of HPV relies on continuous expression of the E6 and E7 genes (9). E7 is an oncoprotein which can transform rodent fibroblasts (24), cooperate with activated ras to transform primary cells (34), and, in association with E6, immortalize keratinocytes (10,19,30).Progression from detectable HPV infection to invasive cancer occurs in less than 1% of cases and usually takes more than 2 decades, indicating that additional factors are involved in the process of carcinogenesis. Several lines of evidence suggest that such factors may act by intensifying HPV early gene expression, as illustrated in the following examples. First, disruption or mutation of the viral E2 gene, which is known to repress the HPV early promoter and hence expression of E6 and E7, is observed in cervical carcinogenesis (7,36,42,47,52). Moreover, the site of chromosomal integration of the viral DNA influences expression of viral early genes (48). Second, viral load appears to be a determinant for the development of cervical carcinoma ...

show abstract

“…[7][8][9] Several approaches have been explored to interfere with the HPV-induced abnormal proliferation by blocking the E7 activity at either gene or protein level, e.g., by phosphorothioate oligonucleotides, 10 short interfering RNA 11 and aptamers. 12 Intracellular immunization has provided new chances for interfering with the function of predetermined intracellular targets by directing antibodies in scFv format to specific compartments of mammalian cells. 13 The intracellular antibodies (intrabodies) can specifically recognize the target antigen in the intracellular environment and counteract its function with a not yet clarified mechanism of action, spanning from forming antigen-antibody complexes to diverting the target-antigen to unusual compartments.…”

mentioning

confidence: 99%

Intracellular anti‐E7 human antibodies in single‐chain format inhibit proliferation of HPV16‐positive cervical carcinoma cells

Accardi

Donà

Bonito

et al. 2005

Intl Journal of Cancer

View full text Add to dashboard Cite

The E7 tumor antigen of human papillomavirus type 16 (HPV16) is a validated target for immunodiagnosis and immunotherapy of HPV-associated cervical cancer. Anti-HPV16 E7 antibodies in scFv format were isolated from a human antibody phage display library and characterized. With the aim of interfering with the oncogenic activity of E7 protein, the most reactive of the selected antibody fragments was expressed by eukaryotic vectors in different compartments of the HPV16-positive cervical carcinoma SiHa cell line. The intracellular antibodies (intrabodies) were tested for their ability of inhibiting cell proliferation. A significant inhibition was obtained targeting the intrabodies to the nuclear and secretory compartments whereas no significant effect was observed in case of cytoplasmic localization. Inhibition was highly specific as no antiproliferative effect was obtained either with the E7-specific intrabodies in HPV-negative cells nor with irrelevant intrabodies in SiHa cells. ' 2005 Wiley-Liss, Inc.Key words: human papillomavirus; E7 protein; intrabodies; singlechain variable fragment; antiproliferative effect; cervical cancer The HPV16 is involved in the aetiology of cervical cancer, the second main cause of cancer mortality in women worldwide.1,2 A real need exists to counter HPV infections either by prevention or by therapy. Many prophylactic and therapeutic vaccine strategies are currently under development or in clinical trial. 3,4The HPV16 oncoproteins E6 and E7, expressed in cervical carcinoma, are crucial for the development and the maintenance of the malignant phenotype.1 These antigens are valuable targets for immunotherapy of tumors because they are able to elicit CTLmediated tumor rejection.5 The HPV16 E7 has been shown recently to elicit antitumoral immunity in mice even when expressed in Nicotiana benthamiana plants. 6 This protein binds several tumour suppressors and promotes keratinocyte transformation by favoring DNA synthesis or inhibiting cellular differentiation.7-9 Several approaches have been explored to interfere with the HPV-induced abnormal proliferation by blocking the E7 activity at either gene or protein level, e.g., by phosphorothioate oligonucleotides, 10 short interfering RNA 11 and aptamers. 12 Intracellular immunization has provided new chances for interfering with the function of predetermined intracellular targets by directing antibodies in scFv format to specific compartments of mammalian cells. 13 The intracellular antibodies (intrabodies) can specifically recognize the target antigen in the intracellular environment and counteract its function with a not yet clarified mechanism of action, spanning from forming antigen-antibody complexes to diverting the target-antigen to unusual compartments.14 This approach has been employed already to achieve antineoplastic effects using intrabodies targeting oncogenic proteins.15 Evidence of antineoplastic effects was obtained in HPV16-positive human carcinoma cell lines by a hybridoma-derived recombinant scFv specific for the HPV16 E7...

show abstract

Induction of apoptosis in cervical carcinoma cells by peptide aptamers that bind to the HPV‐16 E7 oncoprotein

Cited by 43 publications

References 52 publications

Human papillomaviruses type 16+ and 18+ cervical carcinoma cells are sensitive to staurosporine‐mediated apoptosis

Human papillomaviruses type 16+ and 18+ cervical carcinoma cells are sensitive to staurosporine‐mediated apoptosis

A Synthetic E7 Gene of Human Papillomavirus Type 16 That Yields Enhanced Expression of the Protein in Mammalian Cells and Is Useful for DNA Immunization Studies

Intracellular anti‐E7 human antibodies in single‐chain format inhibit proliferation of HPV16‐positive cervical carcinoma cells

Contact Info

Product

Resources

About