Oropharyngeal squamous cell cancers (OSCC) bearing transcriptionally active human papillomavirus (HPV) display distinct protein expression profile

Abstract

10028 Background: It is known that among HPV DNA+ OSCCs only the transcriptionally active ones are biologically and clinically relevant. pRb downregulation by HPVE7 results in p16 upregulation. We previously showed (JCO, Feb 2006) that p16 expression defines transcriptionally active HPV+ tumors. Thus, OSCC tumors can be Class I: HPV−/p16−, Class II: HPV+/p16−, or Class III: HPV+/p16+. We hypothesized that tumors classified by these criteria would show different protein expression profiles. Methods: Following institutional review board approval, paraffin-embedded specimens from 77 patients were collected from Yale-New Haven Hospital archives. Patients with OSCC treated with radiotherapy (RT) or surgery and RT were eligible. We used real-time polymerase chain reaction for HPV 16 and immunohistochemistry for p16 protein expression to classify 77 patients with OSCC. Tumors were classified into a 3-class model based on p16 expression and HPV DNA presence: Class I (HPV−, p16−) Class II (HPV+, p16−) and Class III (HPV+, p16+). A tissue microarray including these cases was constructed and examined for 13 target proteins with known involvement in tumor suppression or progression. We used a method of in-situ automated quantitative protein expression analysis (AQUA). Protein signal (AQUA score) was scored on a scale of 0–255.Protein expression between groups was analyzed by analysis of variance (ANOVA). Results: Thirty tumors were class I (39%), 29 were class II (38%), and 18 were class III (23%). There were significant differences for protein expression of Met (p=0.005), β-catenin (p=0.009), pRb (p=0.001), p53(p=0.026), epidermal growth factor receptor (EGFR) (p=0.009) and Vascular Endothelial Growth Factor (VEGF) (p=0.028). There was no difference for ki-67, COX2, p27, p21 or Cyclin D1 expression, while ERK2 and p14 trended towards significance (p=0.09 and 0.054, respectively). Conclusions: We demonstrated that tumors classified by HPV DNA presence and p16 expression status have different molecular phenotypes. Of particular note, class III tumors demonstrated increased expression of Met, β-catenin, EGFR and VEGF. These findings may prove useful for patient selection for molecular-targeted therapies. [Table: see text]