High level HPV-16 E7 oncoprotein expression correlates with reduced pRb-levels in cervical biopsies.
High-risk human papillomaviruses (HPVs) are major etiological agents of cervical cancer. Despite excellent epidemiological evidence for a direct role of HPV-16 in cervical carcinogenesis, molecular pathways underlying carcinogenesis in vivo remain obscure. The E7 gene is required for immortalization and maintenance of the transformed phenotype in vitro; however, little is known about its role for tumorigenesis in vivo. The E7 gene codes for an unstable protein the abundance of which in cervical biopsies is unknown. We show here that E7 protein levels strongly increase during cervical carcinogenesis, underlining its fundamental role in cervical cancer. The E7 protein was found predominantly in the nucleus and to a minor extent in the cytoplasm in the cervical cancer cell line Ca Ski in vitro and in invasive cervical carcinoma in situ, suggesting that nuclear resident E7 plays a major role in cervical carcinogenesis in humans. The retinoblastoma protein (pRb) is a major E7-target in vitro. We show here that pRb expression is initially upregulated in LSIL and disappears in later stages concomitant with increased E7 levels, suggesting that E7-driven degradation of pRb is involved in cervical tumorigenesis in humans.
Fiedler
Marc
M
Tyrolean Cancer Research Institute at the University of Innsbruck, 6020 Innsbruck, Austria.
Müller-Holzner
Elisabeth
E
Viertler
Hans-Peter
HP
Widschwendter
Andreas
A
Laich
Andreas
A
Pfister
Gerald
G
Spoden
Gilles A
GA
Jansen-Dürr
Pidder
P
Zwerschke
Werner
W
D000818:Animals; D000914:Antibodies, Viral / Q000276:immunology; D001706:Biopsy; D001859:Bone Neoplasms / Q000473:pathology / Q000821:virology; D002294:Carcinoma, Squamous Cell / Q000209:etiology / Q000235:genetics* / Q000473:pathology / Q000821:virology; D002454:Cell Differentiation; D045744:Cell Line, Tumor / Q000378:metabolism / Q000821:virology; D002467:Cell Nucleus / Q000821:virology; D002471:Cell Transformation, Neoplastic / Q000235:genetics; D002472:Cell Transformation, Viral / Q000235:genetics; D002584:Cervix Uteri / Q000473:pathology / Q000821:virology*; D018450:Disease Progression; D004847:Epithelial Cells / Q000648:ultrastructure / Q000821:virology; D005260:Female; D015972:Gene Expression Regulation, Neoplastic; D015967:Gene Expression Regulation, Viral; D016161:Genes, Retinoblastoma; D006801:Humans; D009856:Oncogene Proteins, Viral / Q000096:biosynthesis / Q000235:genetics / Q000276:immunology / Q000502:physiology*; D012516:Osteosarcoma / Q000473:pathology / Q000821:virology; D027383:Papillomaviridae / Q000235:genetics / Q000472:pathogenicity*; D050725:Papillomavirus E7 Proteins; D030361:Papillomavirus Infections / Q000235:genetics*; D011817:Rabbits; D016160:Retinoblastoma Protein / Q000378:metabolism*; D014162:Transfection; D014412:Tumor Virus Infections / Q000235:genetics*; D002583:Uterine Cervical Neoplasms / Q000209:etiology / Q000235:genetics* / Q000473:pathology / Q000821:virology; D002578:Uterine Cervical Dysplasia / Q000209:etiology / Q000235:genetics* / Q000473:pathology / Q000821:virology
D000914:Antibodies, Viral; D009856:Oncogene Proteins, Viral; D050725:Papillomavirus E7 Proteins; D016160:Retinoblastoma Protein; C059731:oncogene protein E7, Human papillomavirus type 16