The human papillomavirus (HPV) oncogene E6 has been shown to perform multiple functions (p53 degradation, telomerase activation, etc.) that play a role in oncogenic transformation. Beyond known E6 functions, an undefined mechanism that allows cellular invasion requires the E6 PDZ binding motif (PDZBM). Here, we show that HPV type 16 (HPV16) E6 interacts with and induces loss of a protein tyrosine phosphatase (PTPN13) in a PDZBM-dependent manner. PTPN13 loss induced either by the presence of E6 or by a short hairpin RNA strategy allows for anchorage-independent growth (AIG) and synergy with a known oncogene, Ras v12 , resulting in invasive growth in vivo. Restoring PTPN13 expression reverses AIG in cells lacking PTPN13. A genomic analysis of colorectal carcinoma has identified an association between PTPN13 loss-of-function mutations and aberrant Ras signaling. Our findings support this correlation and provide methods for further evaluation of the mechanisms by which PTPN13 loss/Ras expression leads to invasive growth, the results of which will be important for treatment of HPV-related and non-HPV cancer.Significant associative evidence supports a role for human papillomavirus type 16 (HPV16) in the carcinogenic progression of at least 25% of head and neck squamous cell cancer (HNSCC) cases (27, 38). In particular, the incidence of HNSCC of the tonsillar region is increasing (18,20,38). The epithelial surfaces surrounding the tonsil (oropharynx) are cancerous in a very high (60%) proportion of cases that are HPV positive, and these cases present with more metastatic and advanced disease states (34, 38) than HPV-negative cases. The incidence of HPV-related HNSCC is also increased in individuals with human immunodeficiency virus/AIDS disease (10). While the data presented in the following studies pertain to HPV-related HNSCC they may also be applicable to cases of HPV-related cervical cancer, which remains the second leading cause of cancer-related death in women. Therefore, understanding the viral mechanisms that lead to cancer will help meet a need for HPV-specific targeted therapy.One of the major HPV viral oncogenes that allow progression to cancer is HPV16 E6. E6 has many potential carcinogenic effects, including telomerase activation and p53 degradation (26, 35). However, an understood mechanism that potentiates malignant progression has been associated with a PDZ (PSD-95, Discs Large, ZO-1) binding motif (PDZBM), a specific amino acid sequence that mediates protein-protein interactions with corresponding PDZ domain-containing proteins. High-risk HPV virus types 16, 18, 31, and 33 possess this binding motif at the E6 C terminus. In addition to this correlative evidence of increased malignant potential in humans, mouse studies demonstrated that PDZBM is required for HPV-related malignancy (37).The studies described below explored the role of the E6 PDZBM in binding and inducing loss of a PDZ domain containing phosphatase PTPN13. PTPN13 is a member of the nonreceptor phosphatases and specifically falls into a cl...

To provide a manipulatable system to study the mechanism of human papillomavirus 16 (HPV16) E6related transformation of an epithelial cell type affected by HPV16 in humans. Design: Biochemical and physiological studies of mouse tonsil epithelial cells (MTECs) transformed with HPV16 oncogenes plus H-ras in vitro and in vivo.

Background-Human papillomavirus 16 (HPV16) has been associated with head and neck squamous cell carcinoma (HNSCC) in up to 60%of sampled specimens.

NF-κB is activated during acute inflammatory states as well as in other injury response disease states. Several pathologic states in squamous tissue injury response are characterized by increased squamous proliferation. This study was performed to investigate the hypothesis that Pseudomonas aeruginosa LPS is able to activate a proliferative phenotype in squamous cells via NF-κB induction and that this NF-κB-mediated response may be abrogated with the classic anti-inflammatory agent indomethacin. EMSA, luciferase reporter gene experiments, Western blots, and cellular proliferation assays were performed in normal and transformed human keratinocytes after stimulation with P. aeruginosa LPS. EMSA and luciferase reporter gene assays showed a 3- to 5-fold induction of active NF-κB in human keratinocyte cell lines after stimulation with P. aeruginosa LPS. The stimulation correlated with significantly increased cellular proliferation. As one potential mechanism for this increase in proliferation, an NF-κB-specific activation of cyclin D1 was observed. Both the NF-κB induction and proliferation response were inhibited with indomethacin and in dominant negative stable transfection clones. P. aeruginosa LPS activates proliferation of human keratinocytes, potentially through the induction of NF-κB and cyclin D1. These findings suggest that bacterial components can contribute to proliferative disease states in squamous epithelium through NF-κB activation.