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

Bernard, Benjamin; Prétet, Jean‐Luc; Charlot, Jean-François; Mougin, Christiane

doi:10.1016/s0248-4900(02)01220-0

Cited by 16 publications

(12 citation statements)

References 92 publications

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“…We did not observe any cleavage of PARP1 polypeptide in HeLa-expressing E6 mutants in contrast to HeLa cells treated with staurosporine, a drug that triggers apoptosis (Bernard et al, 2003). Therefore, cell growth suppression induced by E6 mutants was not driven by induction of caspase-dependent apoptosis.…”

Section: E6 F47r Inhibits Proliferation Of Hela Cellscontrasting

confidence: 61%

A single-codon mutation converts HPV16 E6 oncoprotein into a potential tumor suppressor, which induces p53-dependent senescence of HPV-positive HeLa cervical cancer cells

et al. 2008

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High-risk mucosal human papillomaviruses (HPV), mainly HPV16 and HPV18, are implicated in cervical carcinogenesis. HPV16 E6 oncoprotein binds and often targets for degradation numerous cell proteins, including the tumor suppressor p53 and several PDZ domain proteins. Here, we show that a single-point mutation, F47R, is sufficient to convert the HPV16 E6 oncoprotein into a suppressor of HPV-positive HeLa cervical cancer cells proliferation. The E6 F47R mutant is defective for polyubiquitination and subsequent degradation of p53. When expressed in HPV-positive cervical cancer cells, E6 F47R acts as a dominant negative mutant by counteracting the p53 degradation activity of endogenous E6 and restoring high p53 protein levels. Moreover, the prolonged expression of E6 F47R leads to suppression of HeLa cells proliferation through the induction of premature senescence. This phenotype is independent on the PDZ-binding activity of E6. F47R-senescent HeLa cells exhibit a sustained expression of p53, hMDM2 and p21 CIP proteins and a reduced expression of endogenous HPV18 E6 protein. Finally, small interfering RNAs directed against p53 counteract the effect of E6 F47R expression, indicating that E6 F47R-induced cellular senescence is strongly dependent on p53 signaling pathway.

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Section: E6 F47r Inhibits Proliferation Of Hela Cellscontrasting

confidence: 61%

A single-codon mutation converts HPV16 E6 oncoprotein into a potential tumor suppressor, which induces p53-dependent senescence of HPV-positive HeLa cervical cancer cells

et al. 2008

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“…As expected, expression of the anti-apoptotic protein Bcl-2 was reduced after ST treatment, confirming our previous data. 18 PRIMA-1 alone or in combination with ST did not influence the levels of p53, p21 Bax and Bcl-2.…”

Section: Prima-1 Restores the Transcriptional Activity Of P53 Mt C33amentioning

confidence: 76%

Modulation of p53 transcriptional activity by PRIMA-1 and Pifithrin-α on staurosporine-induced apoptosis of wild-type and mutated p53 epithelial cells

Charlot¹,

Nicolier²,

Prétet³

et al. 2006

Apoptosis

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We recently argued for a major role of p53 in staurosporine(ST)-induced apoptosis of immortalized epithelial cells, depending on their p53 status. Here, we studied the effects of PRIMA-1 (p53 reactivation and induction of massive apoptosis) and Pifithrin-alpha (p fifty-three inhibitor) in combination with ST to reinforce our previous results by respectively restoring or inhibiting the p53 transcriptional activity in different cell lines.PRIMA-1 does modify neither expression of apoptosis-related proteins nor the percentage of wild-type p53 HeLa and CaSki cells with [symbol: see text]delta psi m and DNA cleavage, whilst it increases by 45% Bax expression and apoptosis of mutated p53 C33A cells. Pifithrin-alpha, does modify neither Bax expression nor apoptosis level of C33A cells, but readily inhibits both [symbol: see text]delta psi m and DNA fragmentation of p53wt cells with decreasing Bax expression. These data support the evidence that PRIMA-1 could be a good candidate, as an anti-cancer drug targeting mutant p53, in order to increase ST efficiency. Moreover, Pifithrin-alpha could be used in combination with ST and PRIMA-1 to prevent side effects of anti-tumor therapies in cells expressing mutant P53.

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“…Cleavage of PARP could be clearly observed in CaSki cells treated in parallel with staurosporine (Fig. 5A), a drug that triggers apoptosis in cervical carcinoma cells (30). We could not detect the GADD45a polypeptides in the extracts of antibody-or siRNA-treated cells, in contrast to what is seen after single treatment with doxorubicin (results not shown).…”

Section: Induction Of Cell Growth Arrest and Synergistic E6 Down-regumentioning

confidence: 79%

Suppression of cervical carcinoma cell growth by intracytoplasmic codelivery of anti-oncoprotein E6 antibody and small interfering RNA

Courtête¹,

Sibler²,

Zeder‐Lutz³

et al. 2007

Molecular Cancer Therapeutics

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Cervical cancer is caused by high-risk types of human papillomaviruses (HPV) that encode the E6 and E7 oncogenes. Silencing of E6 gene expression in HPVpositive cell lines by transfection of small interfering RNA (siRNA) with cationic lipids restores the dormant p53 tumor suppressor pathway. Because cationic lipids can also be used for intracytoplasmic delivery of proteins, we tested whether the delivery of monoclonal antibodies that bind to HPV16 E6 and neutralize its biological activity in vitro could restore p53 function in tumor cells. Here, we show that the 4C6 antibody is efficiently delivered into the cell cytoplasm using a lipidic reagent used for siRNA transfection. The delivery of 4C6 resulted in the nuclear accumulation of p53 protein in CaSki and SiHa cells but not in HeLa cells. Furthermore, the antibody-mediated p53 response was dramatically increased when a peptide corresponding to the 4C6 epitope and bearing a COOHterminal cysteine residue was added to the transduction mixture. We found that a fraction of the added peptides were dimers that allowed the formation of antibody polymers adsorbed onto the lipidic matrix. With this system, the proliferation of CaSki and SiHa cells was strongly diminished, but no apoptosis was detectable. Remarkably, cell growth was almost totally suppressed by the addition of E6-specific siRNA to the transduction complex. The results indicate that the activity of E6 oncoprotein can be down-regulated in vivo by lipidmediated antibody delivery and that antibodies and siRNA act synergistically when codelivered. This novel targeting strategy is simple to implement and may find therapeutic applications.

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

Cited by 16 publications

References 92 publications

A single-codon mutation converts HPV16 E6 oncoprotein into a potential tumor suppressor, which induces p53-dependent senescence of HPV-positive HeLa cervical cancer cells

A single-codon mutation converts HPV16 E6 oncoprotein into a potential tumor suppressor, which induces p53-dependent senescence of HPV-positive HeLa cervical cancer cells

Modulation of p53 transcriptional activity by PRIMA-1 and Pifithrin-α on staurosporine-induced apoptosis of wild-type and mutated p53 epithelial cells

Suppression of cervical carcinoma cell growth by intracytoplasmic codelivery of anti-oncoprotein E6 antibody and small interfering RNA

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