The diagnosis of sinonasal tumors is challenging due to a heterogeneous spectrum of various differential diagnoses as well as poorly defined, disputed entities such as sinonasal undifferentiated carcinomas (SNUCs). In this study, we apply a machine learning algorithm based on DNA methylation patterns to classify sinonasal tumors with clinical-grade reliability. We further show that sinonasal tumors with SNUC morphology are not as undifferentiated as their current terminology suggests but rather reassigned to four distinct molecular classes defined by epigenetic, mutational and proteomic profiles. This includes two classes with neuroendocrine differentiation, characterized by IDH2 or SMARCA4/ARID1A mutations with an overall favorable clinical course, one class composed of highly aggressive SMARCB1-deficient carcinomas and another class with tumors that represent potentially previously misclassified adenoid cystic carcinomas. Our findings can aid in improving the diagnostic classification of sinonasal tumors and could help to change the current perception of SNUCs.

Recent studies support an important role for human papillomavirus (HPV) in oropharyngeal squamous cell carcinomas (OPSCC), although the incidence varies widely depending on the geographic location and time period studied. The aim of this study was to determine the proportion of HPV in a large cohort of OPSCC in northern Spain in the years 1990–2009. Clinical records and paraffin embedded tumor specimens of 248 consecutive patients surgically treated for OPSCC (140 tonsillar and 108 base of tongue) between 1990 and 2009 were retrieved. OPSCC cases were histomorphologically evaluated, and protein expression of p16 and p53 was analyzed by immunohistochemistry. Detection of high‐risk HPV DNA was performed by GP5+/6+‐PCR and in situ hybridization (ISH). Thirty cases (12%) were positive for p16 immunostaining, of which eight (3.2% of the total series) were found positive for HPV type 16 by genotyping of GP5+6+‐PCR products. All HPV GP5+/6+‐PCR‐positive tumors were p53‐immunonegative, seven had a basaloid morphology and seven were also positive by HPV ISH. Presence of HPV correlated inversely with tobacco and alcohol consumption (p < 0.001), but not with age of onset of OPSCC. Overall survival was better in the HPV‐positive group, although not statistically significant (p = 0.175). OPSCC patients in northern Spain demonstrated a low involvement of HPV, increasing (although not significantly, p = 0.120) from 1.8% in 1990–1999 to 6.1% of cases in 2000–2009.

This study investigates for the first time the crosstalk between stromal fibroblasts and cancer stem cell (CSC) biology in head and neck squamous cell carcinomas (HNSCC), with the ultimate goal of identifying effective therapeutic targets. The effects of conditioned media from cancer-associated fibroblasts (CAFs) and normal fibroblasts (NFs) on the CSC phenotype were assessed by combining functional and expression analyses in HNSCC-derived cell lines. Further characterization of CAFs and NFs secretomes by mass spectrometry was followed by pharmacologic target inhibition. We demonstrate that factors secreted by CAFs but not NFs, in the absence of serum/supplements, robustly increased anchorage-independent growth, tumorsphere formation, and CSC-marker expression. Modulators of epidermal growth factor receptor (EGFR), insulin-like growth factor receptor (IGFR), and platelet-derived growth factor receptor (PDGFR) activity were identified as paracrine cytokines/factors differentially secreted between CAFs and NFs, in a mass spectrometry analysis. Furthermore, pharmacologic inhibition of EGFR, IGFR, and PDGFR significantly reduced CAF-induced tumorsphere formation and anchorage-independent growth suggesting a role of these receptor tyrosine kinases in sustaining the CSC phenotype. These findings provide novel insights into tumor stroma–CSC communication, and potential therapeutic targets to effectively block the CAF-enhanced CSC niche signaling circuit.