Molecular Classification of HPV-Associated Head Neck Cancer

Abstract

Problem

We previously proposed that head and neck squamous cell carcinoma (HNSCC) presents in three histopathologically similar but molecularly distinct types where p16 expression combined with high-risk Human Papillomavirus (HPV) presence defines three distinct subgroups: Class I (HPV-), Class II (HPV16+/p16-), Class III (HPV16+/p16+). In this study we sought to further explore and validate this classification schema.

Methods

Paraffin-embedded specimens from 77 patients with OSCC classified into the 3-class model based on p16 expression and HPV DNA presence were previously queried for expression of 14 target proteins with known involvement in tumor progression using AQUA(tm). We calculated pairwise associations by Spearman correlation and performed hierarchical clustering analysis to assess global expression patterns of class I, II and III tumors.

Results

Hierarchical clustering analysis demonstrated class I and class II tumors displayed similar clustering patterns. Class III tumors (HPV+/p16+) displayed unique clustering patterns distinct from both class I and class II tumors. In class I/II tumors ERK2, p27, p14, ki67 and PCNA were tightly associated. This contrasted with class III tumors which displayed two separate clusters (EGFR, RB, pAKT and CND1), and (ERK2, p16 and p14).

Conclusion

We demonstrated that HNSCC classified by a combination of HPV DNA presence and p16 expression status have distinct molecular phenotypes. Class III tumors, distinct from HPV+ but p16-negative class II tumors, have a unique molecular clustering profile, lending support to the proposed 3-class model.

Significance

These findings may have significant implications in patient selection for HPV-specific therapies.

Support

AAO/HNSF Resident Research Grant 26357 (PMW).