Manuela Donalisio

Publications of Manuela Donalisio

• Enhanced antiviral activity of acyclovir loaded into nanoparticles.

  Authors: Roberta Cavalli, Manuela Donalisio, Agnese Bisazza, Andrea Civra, Elisabetta Ranucci, Paolo Ferruti, David Lembo

  Methods in enzymology. 01/2012; 509:1-19.

  The activity of antivirals can be enhanced by their incorporation in nanoparticulate delivery systems. Peculiar polymeric nanoparticles, based on a β-cyclodextrin-poly(4-acryloylmorpholine)The activity of antivirals can be enhanced by their incorporation in nanoparticulate delivery systems. Peculiar polymeric nanoparticles, based on a β-cyclodextrin-poly(4-acryloylmorpholine) monoconjugate (β-CD-PACM), are proposed as acyclovir carriers. The experimental procedure necessary to obtain the acyclovir-loaded nanoparticles using the solvent displacement preparation method will be described in this chapter. Fluorescent labeled nanoparticles are prepared using the same method for cellular trafficking studies. The biocompatibility assays necessary to obtain safe nanoparticles are reported. Section 4 of this chapter describes the assessment of the antiviral activity of the acyclovir-loaded nanoparticles.

• Putative mechanisms of antitumor activity of cyano-substituted heteroaryles in HeLa cells.

  Authors: Katja Ester, Fran Supek, Kristina Majsec, Marko Marjanović, David Lembo, Manuela Donalisio, Tomislav Smuc, Ivana Jarak, Grace Karminski-Zamola, Marijeta Kralj

  Investigational new drugs. 11/2010; 30(2):450-67.

  Six recently synthesized cyano-substituted heteroaryles, which do not bind to DNA but are highly cytotoxic against the human tumor cell line HeLa, were analyzed for their antitumor mechanisms ofSix recently synthesized cyano-substituted heteroaryles, which do not bind to DNA but are highly cytotoxic against the human tumor cell line HeLa, were analyzed for their antitumor mechanisms of action (MOA). They did not interfere with the expression of human papillomavirus oncogenes integrated in the HeLa cell genome, but they did induce strong G1 arrest and result in the activation of caspase-3 and apoptosis. A computational analysis was performed that compared the antiproliferative activities of our compounds in 13 different tumor cell lines with those of compounds listed in the National Cancer Institute database. The results indicate that interference with cytoskeletal function and inhibition of mitosis are the likely antitumor MOA. Furthermore, a second in silico investigation revealed that the tumor cells that are sensitive to the cyano-substituted compounds show differences in their expression of locomotion genes compared with that of insensitive cell lines, thus corroborating the involvement of the cytoskeleton. This MOA was also confirmed experimentally: the cyano-substituted heteroaryles disrupted the actin and the tubulin networks in HeLa cells and inhibited cellular migration. However, further analysis indicated that multiple MOA may exist that depend on the position of the cyano-group; while cyano-substituted naphthiophene reduced the expression of cytoskeletal proteins, cyano-substituted thieno-thiophene-carboxanilide inhibited the formation of cellular reactive oxygen species.

• Identification of a dendrimeric heparan sulfate-binding peptide that inhibits infectivity of genital types of human papillomaviruses.

  Authors: Manuela Donalisio, Marco Rusnati, Andrea Civra, Antonella Bugatti, Donatella Allemand, Giovanna Pirri, Andrea Giuliani, Santo Landolfo, David Lembo

  Antimicrobial agents and chemotherapy. 10/2010; 54(10):4290-9.

  Peptide dendrimers consist of a peptidyl branching core and/or covalently attached surface functional units. They show a variety of biological properties, including antiviral activity. In this study,Peptide dendrimers consist of a peptidyl branching core and/or covalently attached surface functional units. They show a variety of biological properties, including antiviral activity. In this study, a minilibrary of linear, dimeric, and dendrimeric peptides containing clusters of basic amino acids was evaluated for in vitro activity against human papillomaviruses (HPVs). The peptide dendrimer SB105-A10 was found to be a potent inhibitor of genital HPV types (i.e., types 16, 18, and 6) in pseudovirus-based neutralization assays. The 50% inhibitory concentration was between 2.8 and 4.2 μg/ml (0.59 and 0.88 μM), and no evidence of cytotoxicity was observed. SB105-A10 interacts with immobilized heparin and with heparan sulfates exposed on the cell surface, most likely preventing virus attachment. The findings from this study indicate SB105-A10 to be a leading candidate compound for further development as an active ingredient of a topical microbicide against HPV and other sexually transmitted viral infections.

• In vitro activity of dermaseptin S1 derivatives against genital pathogens.

  Authors: Dianella Savoia, Manuela Donalisio, Andrea Civra, Severo Salvadori, Remo Guerrini

  APMIS : acta pathologica, microbiologica, et immunologica Scandinavica. 09/2010; 118(9):674-80.

  The aim of this study was to evaluate the biological activity of nine dermaseptin-S1 (DRS-S1) derivatives (synthesized by solid-phase methods and purified) against different pathogens causing genitalThe aim of this study was to evaluate the biological activity of nine dermaseptin-S1 (DRS-S1) derivatives (synthesized by solid-phase methods and purified) against different pathogens causing genital infections (Trichomonas vaginalis, Herpes simplex virus, Papillomavirus). The in vitro activity on T. vaginalis was determined by counting the protozoon in a hemocytometer after vital staining with trypan blue; antiviral activity of the compounds was tested on monolayers of Vero cells for Herpes simplex virus-1 (GFP) and on 293TT cells for human papillomavirus (HPV-16) pseudovirions (GFP). The cytotoxicity of the derivatives was assessed by evaluating both the hemolytic activity and the effect on Vero and 293TT cells. The DRS-S1 longer peptides demonstrated a superior activity on T. vaginalis but also a certain cytopathic effect. The compounds with 29 amino acids exhibited activity against the two viruses tested at concentrations not toxic to cells. The results obtained show that some of the synthetic peptides assessed have inhibitory activity against the pathogens tested, indicating a potential for the development of new molecules for use as topical microbicides to prevent the sexual transmission of microorganisms.

• Effects of cytokines on long control region transcriptional activity in high-risk cutaneous human papillomavirus types 5 and 8.

  Authors: Manuela Donalisio, Alice Poli, Andrea Civra, Santo Landolfo, David Lembo

  Archives of virology. 02/2010; 155(4):583-7.

  Cytokines play an important role in the control of mucosal HPV transcription. However, there is little data available on cutaneous HPVs, which are associated with non-melanoma skin cancers. Here, weCytokines play an important role in the control of mucosal HPV transcription. However, there is little data available on cutaneous HPVs, which are associated with non-melanoma skin cancers. Here, we describe a cell-based assay exploiting HaCaT keratinocytes stably transfected with a reporter construct containing the long control region (LCR) regulatory sequence of gene transcription in HPV-5 and HPV-8. This novel assay has allowed the first systematic analysis of the effects of cytokines on HPV-5 and HPV-8 LCR activity and provides a valuable tool for the search for cutaneous HPV-gene expression inhibitors.

• Sulfated K5 Escherichia coli polysaccharide derivatives: A novel class of candidate antiviral microbicides.

  Authors: Marco Rusnati, Elisa Vicenzi, Manuela Donalisio, Pasqua Oreste, Santo Landolfo, David Lembo

  Pharmacology & therapeutics. 06/2009;

  Antiviral microbicides, topical agents that prevent sexually transmitted infections, mainly work by blocking the interaction between viral proteins and cell surface components. In many instances,Antiviral microbicides, topical agents that prevent sexually transmitted infections, mainly work by blocking the interaction between viral proteins and cell surface components. In many instances, virus-cell interaction is mediated by cell surface heparan sulfate proteoglycans (HSPGs). HSPGs are exploited as attachment receptors by three sexually transmitted viruses: Human Immunodeficiency Virus (HIV), Herpes Simplex Virus (HSV) and Human Papilloma Virus (HPV). Since these viruses can either infect or co-infect humans, virus/HSPGs interaction is a preferential target for the development of wide-spectrum antiviral microbicides. Several polyanionic compounds prevent HIV, HSV and HPV infections in cell culture models by acting as heparan sulfate (HS)-antagonists. However, three promising polyanionic compounds recently failed to pass phase III clinical trials designed to establish their efficacy in preventing HIV acquisition. In this scenario, new polyanionic compounds must be added to the pipeline of candidate microbicides and their development as effective drugs reconsidered. The capsular K5 polysaccharide from E. coli has the same structure as the heparin/HS biosynthetic precursor. Chemical and enzymatic modifications have led to the synthesis of K5 derivatives with different degrees of sulfation and charge distribution and devoid of anticoagulant activity and cell toxicity. Recently attracting attention as candidate microbicides, they potently inhibit a broad spectrum of HIV-1 strains and genital types of HPV and HSV-1 and 2 in vitro. With a focus on the K5 derivatives, this article reviews the literature on polyanions as antiviral microbicides and discusses the possible therapeutic implications of this novel class of compounds.

• Enhanced antiviral activity of Acyclovir loaded into beta-cyclodextrin-poly(4-acryloylmorpholine) conjugate nanoparticles.

  Authors: Roberta Cavalli, Manuela Donalisio, Andrea Civra, Paolo Ferruti, Elisabetta Ranucci, Francesco Trotta, David Lembo

  Journal of controlled release : official journal of the Controlled Release Society. 05/2009;

  Novel polymeric nanoparticles based on a beta-cyclodextrin-poly(4-acryloylmorpholine) mono-conjugate (beta-CD-PACM), a tadpole-shaped polymer in which the beta-CD ring is the hydrophilic head and theNovel polymeric nanoparticles based on a beta-cyclodextrin-poly(4-acryloylmorpholine) mono-conjugate (beta-CD-PACM), a tadpole-shaped polymer in which the beta-CD ring is the hydrophilic head and the PACM chain the amphiphilic tail, were prepared by the solvent injection technique. Acyclovir-loaded nanoparticles were prepared from inclusion complexes of Acyclovir with beta-CD-PACM. Both unloaded and drug-loaded nanoparticles were characterized in terms of particle size distribution, morphology, zeta potential, drug loading and in vitro drug release rate. The antiviral activity of Acyclovir loaded into beta-CD-PACM nanoparticles against two clinical isolates of HSV-1 was evaluated and found to be remarkably superior compared with that of both the free drug and a soluble beta-CD-PACM complex reported in a previous paper. Fluorescent nanoparticles loaded with coumarin 6 were also prepared in order to investigate the nanoparticle cell uptake by confocal laser microscopy. It was found that the nanoparticles are internalized in cells and locate in the perinuclear compartment.

• Sulfated K5 Escherichia coli polysaccharide derivatives as wide-range inhibitors of genital types of human papillomavirus.

  Authors: David Lembo, Manuela Donalisio, Marco Rusnati, Antonella Bugatti, Maura Cornaglia, Paola Cappello, Mirella Giovarelli, Pasqua Oreste, Santo Landolfo

  Antimicrobial agents and chemotherapy. 05/2008; 52(4):1374-81.

  Genital human papillomaviruses (HPV) represent the most common sexually transmitted agents and are classified into low or high risk by their propensity to cause genital warts or cervical cancer,Genital human papillomaviruses (HPV) represent the most common sexually transmitted agents and are classified into low or high risk by their propensity to cause genital warts or cervical cancer, respectively. Topical microbicides against HPV may be a useful adjunct to the newly licensed HPV vaccine. A main objective in the development of novel microbicides is to block HPV entry into epithelial cells through cell surface heparan sulfate proteoglycans. In this study, selective chemical modification of the Escherichia coli K5 capsular polysaccharide was integrated with innovative biochemical and biological assays to prepare a collection of sulfated K5 derivatives with a backbone structure resembling the heparin/heparan biosynthetic precursor and to test them for their anti-HPV activity. Surface plasmon resonance assays revealed that O-sulfated K5 with a high degree of sulfation [K5-OS(H)] and N,O-sulfated K5 with a high [K5-N,OS(H)] or low [K5-N,OS(L)] sulfation degree, but not unmodified K5, N-sulfated K5, and O-sulfated K5 with low levels of sulfation, prevented the interaction between HPV-16 pseudovirions and immobilized heparin. In cell-based assays, K5-OS(H), K5-N,OS(H), and K5-N,OS(L) inhibited HPV-16, HPV-18, and HPV-6 pseudovirion infection. Their 50% inhibitory concentration was between 0.1 and 0.9 mug/ml, without evidence of cytotoxicity. These findings provide insights into the design of novel, safe, and broad-spectrum microbicides against genital HPV infections.

• TGF-beta1 and IL-4 downregulate human papillomavirus-16 oncogene expression but have differential effects on the malignant phenotype of cervical carcinoma cells.

  Authors: Manuela Donalisio, Maura Cornaglia, Santo Landolfo, David Lembo

  Virus research. 04/2008; 132(1-2):253-6.

  Host immune response to human papillomavirus (HPV) is a crucial factor in viral clearance and control of persistent infections. The existence of an intercellular control mechanism mediated byHost immune response to human papillomavirus (HPV) is a crucial factor in viral clearance and control of persistent infections. The existence of an intercellular control mechanism mediated by cytokines to suppress HPV-gene transcription and to prevent malignant conversion of HPV-infected cells, has been postulated. In a previous study, we demonstrated the inhibitory activity of several cytokines on the HPV-16 long control region (LCR)-driven transcription; among these, IL-4 was reported as a LCR inhibitor for the first time and proposed as a candidate for further studies. Here, we addressed the question of whether IL-4 represses HPV-16 oncogene transcription and exerts antitumor activity in HPV-16 positive cervical carcinoma cell lines. Results indicated that downregulation of E6 and E7 levels by IL-4 in CaSki cells is weaker than that exerted by TGF-beta1, a known LCR inhibitor, although both cytokines are equally active in suppressing LCR-driven transcriptional activity in a reporter cell line. Moreover, only TGF-beta rescued p53 expression, Rb response pathway, and induced cellular senescence. SiHa cells were unresponsive to both cytokines. These findings suggest that the two cytokines may play a role in the control of HPV infections, however, cervical carcinoma cells developed a partial or a total resistance to their inhibitory activity.

• Preparation and in vitro evaluation of the antiviral activity of the Acyclovir complex of a beta-cyclodextrin/poly(amidoamine) copolymer.

  Authors: Marco Bencini, Elisabetta Ranucci, Paolo Ferruti, Francesco Trotta, Manuela Donalisio, Maura Cornaglia, David Lembo, Roberta Cavalli

  Journal of controlled release : official journal of the Controlled Release Society. 03/2008; 126(1):17-25.

  A poly(amidoamine) (PAA) copolymer with beta-cyclodextrin was obtained by polyaddition reaction of 6-deoxy-6-amino-beta-cyclodextrin (beta-CD-NH(2)) and 2-methylpiperazine toA poly(amidoamine) (PAA) copolymer with beta-cyclodextrin was obtained by polyaddition reaction of 6-deoxy-6-amino-beta-cyclodextrin (beta-CD-NH(2)) and 2-methylpiperazine to 2,2-bis(acrylamido)acetic acid in aqueous medium. This beta-CD/PAA copolymer bears beta-CD units along the macromolecular chain, is water-soluble and non-cytotoxic. The complexing capacity of beta-CD/PAA was determined using an antiviral drug, Acyclovir, as a model of poorly water-soluble drug. Complex formation was confirmed by means of DSC and FTIR analyses. beta-CD/PAA can solubilize up to 11% w/w of Acyclovir notably increasing the aqueous solubility of the drug. The in vitro release studies showed the dependence of Acyclovir release rate on the solution pH. The antiviral activity of Acyclovir beta-CD/PAA complex was evaluated against herpes simplex virus type I in cell cultures. The Acyclovir beta-CD/PAA complex exhibited a higher antiviral activity than the free drug.

• Effect of high-risk human papillomavirus oncoproteins on p53R2 gene expression after DNA damage.

  Authors: David Lembo, Manuela Donalisio, Maura Cornaglia, Barbara Azzimonti, Anna Demurtas, Santo Landolfo

  Virus research. 01/2007; 122(1-2):189-93.

  The p53R2 protein is a p53-inducible small subunit of ribonucleotide reductase. It plays a crucial role in p53-dependent cellular response to DNA damage and oxidative stress by providingThe p53R2 protein is a p53-inducible small subunit of ribonucleotide reductase. It plays a crucial role in p53-dependent cellular response to DNA damage and oxidative stress by providing deoxyribonucleotides (dNTPs) to the DNA repair machinery and by scavenging reactive oxygen species (ROS). To investigate the effects of high-risk human papillomavirus (HPV) oncoproteins on p53R2 expression after DNA damage, we analyzed the p53R2 protein levels in human cells ectopically expressing the HPV-16 E6 and E7 genes, and in the HPV-positive cancer cell lines SiHa, CaSki and HeLa, exposed to adriamycin or to H(2)O(2). We found that in normal cells, p53R2 expression is efficiently induced by both H(2)O(2) and adriamycin, supporting the role of p53R2 in cellular response to oxidative stress. Ectopic expression of E6 impaired p53 and p53R2 induction after DNA damage in human fibroblasts. Moreover, SiHa, CaSki and HeLa cells were unresponsive to H(2)O(2) exposure, and adriamycin induced p53R2 levels only in SiHa cells. Our results imply that high-risk HPV infection may suppress the p53R2-dependent dNTPs supply to the DNA repair system and the ROS scavenging activity; they also suggest that an altered p53R2 response to genotoxins and to oxidative stress may contribute to HPV-induced genetic instability and carcinogenesis.

• A cell-based high-throughput assay for screening inhibitors of human papillomavirus-16 long control region activity.

  Authors: David Lembo, Manuela Donalisio, Marco De Andrea, Maura Cornaglia, Sara Scutera, Tiziana Musso, Santo Landolfo

  The FASEB journal : official publication of the Federation of American Societies for Experimental Biology. 02/2006; 20(1):148-50.

  Cervical carcinomas express human papillomavirus (HPV) E6 and E7 oncoproteins, which are required to maintain the proliferative state of cancer cells. Repression of E6 and E7 expression results inCervical carcinomas express human papillomavirus (HPV) E6 and E7 oncoproteins, which are required to maintain the proliferative state of cancer cells. Repression of E6 and E7 expression results in acquisition of senescent phenotype and in the rescue of functional p53 and p105(Rb) pathways; therefore, therapies directed against either viral protein may be beneficial. However, the systems to study HPV in vitro are technically difficult and not convenient for screening of antiviral compounds. This has hampered the discovery of drugs against HPV. Here we describe the generation and use of a high-throughput screening system based on keratinocytes stably transfected with a reporter construct containing the regulatory sequence of E6 and E7 gene transcription (LCR) that allows easy detection of inhibitors of E6 and E7 expression in libraries of synthetic or biological compounds. The assay was used to screen a wide panel of cytokines: among them, IL-4, IL-13, TGF-beta1, TGF-beta2, TGF-beta3, TNF-alpha, IFN-alpha, and IFN-beta were found to induce a strong inhibition of the LCR activity. Our assay provides a validated tool in the search for drugs against HPV-associated cervical carcinomas and allowed the first systematic analysis of the effect of cytokines on the HPV-16 LCR transcriptional activity.

• The ribonucleotide reductase R1 homolog of murine cytomegalovirus is not a functional enzyme subunit but is required for pathogenesis.

  Authors: David Lembo, Manuela Donalisio, Anders Hofer, Maura Cornaglia, Wolfram Brune, Ulrich Koszinowski, Lars Thelander, Santo Landolfo

  Journal of virology. 05/2004; 78(8):4278-88.

  Ribonucleotide reductase (RNR) is the key enzyme in the biosynthesis of deoxyribonucleotides. Alpha- and gammaherpesviruses express a functional enzyme, since they code for both the R1 and the R2Ribonucleotide reductase (RNR) is the key enzyme in the biosynthesis of deoxyribonucleotides. Alpha- and gammaherpesviruses express a functional enzyme, since they code for both the R1 and the R2 subunits. By contrast, betaherpesviruses contain an open reading frame (ORF) with homology to R1, but an ORF for R2 is absent, suggesting that they do not express a functional RNR. The M45 protein of murine cytomegalovirus (MCMV) exhibits the sequence features of a class Ia RNR R1 subunit but lacks certain amino acid residues believed to be critical for enzymatic function. It starts to be expressed independently upon the onset of viral DNA synthesis at 12 h after infection and accumulates at later times in the cytoplasm of the infected cells. Moreover, it is associated with the virion particle. To investigate direct involvement of the virally encoded R1 subunit in ribonucleotide reduction, recombinant M45 was tested in enzyme activity assays together with cellular R1 and R2. The results indicate that M45 neither is a functional equivalent of an R1 subunit nor affects the activity or the allosteric control of the mouse enzyme. To replicate in quiescent cells, MCMV induces the expression and activity of the cellular RNR. Mutant viruses in which the M45 gene has been inactivated are avirulent in immunodeficient SCID mice and fail to replicate in their target organs. These results suggest that M45 has evolved a new function that is indispensable for virus replication and pathogenesis in vivo.

  Download

• TGF-β1 and IL-4 downregulate human papillomavirus-16 oncogene expression but have differential effects on the malignant phenotype of cervical carcinoma cells

  Authors: Manuela Donalisio, Maura Cornaglia, Santo Landolfo, David Lembo

  Virus Research.

  Host immune response to human papillomavirus (HPV) is a crucial factor in viral clearance and control of persistent infections. The existence of an intercellular control mechanism mediated byHost immune response to human papillomavirus (HPV) is a crucial factor in viral clearance and control of persistent infections. The existence of an intercellular control mechanism mediated by cytokines to suppress HPV-gene transcription and to prevent malignant conversion of HPV-infected cells, has been postulated. In a previous study, we demonstrated the inhibitory activity of several cytokines on the HPV-16 long control region (LCR)-driven transcription; among these, IL-4 was reported as a LCR inhibitor for the first time and proposed as a candidate for further studies. Here, we addressed the question of whether IL-4 represses HPV-16 oncogene transcription and exerts antitumor activity in HPV-16 positive cervical carcinoma cell lines. Results indicated that downregulation of E6 and E7 levels by IL-4 in CaSki cells is weaker than that exerted by TGF-β1, a known LCR inhibitor, although both cytokines are equally active in suppressing LCR-driven transcriptional activity in a reporter cell line. Moreover, only TGF-beta rescued p53 expression, Rb response pathway, and induced cellular senescence. SiHa cells were unresponsive to both cytokines. These findings suggest that the two cytokines may play a role in the control of HPV infections, however, cervical carcinoma cells developed a partial or a total resistance to their inhibitory activity.

• Sulfated K5 Escherichia coli polysaccharide derivatives: A novel class of candidate antiviral microbicides

  Authors: Marco Rusnati, Elisa Vicenzi, Manuela Donalisio, Pasqua Oreste, Santo Landolfo, David Lembo

  Pharmacology & Therapeutics.

  Antiviral microbicides, topical agents that prevent sexually transmitted infections, mainly work by blocking the interaction between viral proteins and cell surface components. In many instances,Antiviral microbicides, topical agents that prevent sexually transmitted infections, mainly work by blocking the interaction between viral proteins and cell surface components. In many instances, virus–cell interaction is mediated by cell surface heparan sulfate proteoglycans (HSPGs). HSPGs are exploited as attachment receptors by three sexually transmitted viruses: Human Immunodeficiency Virus (HIV), Herpes Simplex Virus (HSV) and Human Papilloma Virus (HPV). Since these viruses can either infect or co-infect humans, virus/HSPGs interaction is a preferential target for the development of wide-spectrum antiviral microbicides. Several polyanionic compounds prevent HIV, HSV and HPV infections in cell culture models by acting as heparan sulfate (HS)-antagonists. However, three promising polyanionic compounds recently failed to pass phase III clinical trials designed to establish their efficacy in preventing HIV acquisition. In this scenario, new polyanionic compounds must be added to the pipeline of candidate microbicides and their development as effective drugs reconsidered. The capsular K5 polysaccharide from Escherichia coli has the same structure as the heparin/HS biosynthetic precursor. Chemical and enzymatic modifications have led to the synthesis of K5 derivatives with different degrees of sulfation and charge distribution and devoid of anticoagulant activity and cell toxicity. Recently attracting attention as candidate microbicides, they potently inhibit a broad spectrum of HIV-1 strains and genital types of HPV and HSV-1 and 2 in vitro. With a focus on the K5 derivatives, this article reviews the literature on polyanions as antiviral microbicides and discusses the possible therapeutic implications of this novel class of compounds.

• Effect of high-risk human papillomavirus oncoproteins on p53R2 gene expression after DNA damage

  Authors: David Lembo, Manuela Donalisio, Maura Cornaglia, Barbara Azzimonti, Anna Demurtas, Santo Landolfo

  Virus Research.

  The p53R2 protein is a p53-inducible small subunit of ribonucleotide reductase. It plays a crucial role in p53-dependent cellular response to DNA damage and oxidative stress by providingThe p53R2 protein is a p53-inducible small subunit of ribonucleotide reductase. It plays a crucial role in p53-dependent cellular response to DNA damage and oxidative stress by providing deoxyribonucleotides (dNTPs) to the DNA repair machinery and by scavenging reactive oxygen species (ROS). To investigate the effects of high-risk human papillomavirus (HPV) oncoproteins on p53R2 expression after DNA damage, we analyzed the p53R2 protein levels in human cells ectopically expressing the HPV-16 E6 and E7 genes, and in the HPV-positive cancer cell lines SiHa, CaSki and HeLa, exposed to adriamycin or to H2O2. We found that in normal cells, p53R2 expression is efficiently induced by both H2O2 and adriamycin, supporting the role of p53R2 in cellular response to oxidative stress. Ectopic expression of E6 impaired p53 and p53R2 induction after DNA damage in human fibroblasts. Moreover, SiHa, CaSki and HeLa cells were unresponsive to H2O2 exposure, and adriamycin induced p53R2 levels only in SiHa cells. Our results imply that high-risk HPV infection may suppress the p53R2-dependent dNTPs supply to the DNA repair system and the ROS scavenging activity; they also suggest that an altered p53R2 response to genotoxins and to oxidative stress may contribute to HPV-induced genetic instability and carcinogenesis.