Human papillomavirus-16 E7 interacts with glutathione S-transferase P1 and enhances its role in cell survival.
BACKGROUND
Human Papillomavirus (HPV)-16 is a paradigm for "high-risk" HPVs, the causative agents of virtually all cervical carcinomas. HPV E6 and E7 viral genes are usually expressed in these tumors, suggesting key roles for their gene products, the E6 and E7 oncoproteins, in inducing malignant transformation.


RESULTS
By protein-protein interaction analysis, using mass spectrometry, we identified glutathione S-transferase P1-1 (GSTP1) as a novel cellular partner of the HPV-16 E7 oncoprotein. Following mapping of the region in the HPV-16 E7 sequence that is involved in the interaction, we generated a three-dimensional molecular model of the complex between HPV-16 E7 and GSTP1, and used this to engineer a mutant molecule of HPV-16 E7 with strongly reduced affinity for GSTP1.When expressed in HaCaT human keratinocytes, HPV-16 E7 modified the equilibrium between the oxidized and reduced forms of GSTP1, thereby inhibiting JNK phosphorylation and its ability to induce apoptosis. Using GSTP1-deficient MCF-7 cancer cells and siRNA interference targeting GSTP1 in HaCaT keratinocytes expressing either wild-type or mutant HPV-16 E7, we uncovered a pivotal role for GSTP1 in the pro-survival program elicited by its binding with HPV-16 E7.


CONCLUSIONS
This study provides further evidence of the transforming abilities of this oncoprotein, setting the groundwork for devising unique molecular tools that can both interfere with the interaction between HPV-16 E7 and GSTP1 and minimize the survival of HPV-16 E7-expressing cancer cells.
Mileo
Anna M
AM
Department of Development of Therapeutic Programs, CRS, Regina Elena Cancer Institute, Rome, Italy.
Abbruzzese
Claudia
C
Mattarocci
Stefano
S
Bellacchio
Emanuele
E
Pisano
Paola
P
Federico
Antonio
A
Maresca
Vittoria
V
Picardo
Mauro
M
Giorgi
Alessandra
A
Maras
Bruno
B
Schininà
M Eugenia
ME
Paggi
Marco G
MG
D045744:Cell Line, Tumor; D002470:Cell Survival; D002471:Cell Transformation, Neoplastic; D015967:Gene Expression Regulation, Viral; D051549:Glutathione S-Transferase pi / Q000378:metabolism*; D052162:Human papillomavirus 16 / Q000378:metabolism*; D006801:Humans; D015603:Keratinocytes / Q000821:virology; D013058:Mass Spectrometry / Q000379:methods; D008968:Molecular Conformation; D009154:Mutation; D009856:Oncogene Proteins, Viral / Q000378:metabolism*; D050725:Papillomavirus E7 Proteins; D011485:Protein Binding; D025941:Protein Interaction Mapping; D012097:Repressor Proteins / Q000378:metabolism
C068651:E6 protein, Human papillomavirus type 16; D009856:Oncogene Proteins, Viral; D050725:Papillomavirus E7 Proteins; D012097:Repressor Proteins; C059731:oncogene protein E7, Human papillomavirus type 16; C496556:GSTP1 protein, human; D051549:Glutathione S-Transferase pi