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Background To report associations between p16 status, clinicopathologic characteristics, and outcomes for unknown primary head and neck squamous cell carcinoma (SCCUPS). Methods Specimens of SCCUPS were re-analyzed. HPV status was determined by p16 stain. A tissue microarray (TMA) was constructed to evaluate biomarkers potentially prognostic in HNSCC. Results A majority of the population (n = 26, 74%) was p16+. Prognostic factors benefitting survival were p16+ status (p < 0.0001), absence of macroscopic extracapsular extension [ECE] (p = 0.004), younger age (p = 0.01), and higher grade (p = 0.007). The prognostic implication of worse OS with macroscopic ECE (p = 0.009) remained significant when limited to p16+ patients (p=0.002). Exploratory TMA between unknown primary and controls suggested a biomolecular difference between SCCUPS and known-primary cancer. Conclusions The majority of SCCUPS patients were p16+, indicative of HPV association. p16 staining and ECE appear to be the most prognostic features in SCCUPS.

Persistent signaling by the oncogenic epidermal growth factor receptor (EGFR) is a major source of cancer resistance to EGFR targeting. We established that inactivation of two sterol biosynthesis pathway genes, SC4MOL (sterol C4-methyl oxidase-like) and its partner NSDHL (NADP-dependent steroid dehydrogenase-like), sensitized tumor cells to EGFR inhibitors. Bioinformatics modeling of interactions for the sterol pathway genes in eukaryotes allowed us to hypothesize, and then extensively validate an unexpected role for SC4MOL and NSDHL in controlling the signaling, vesicular trafficking and degradation of EGFR and its dimerization partners, ERBB2 and ERBB3. Metabolic block upstream of SC4MOL with ketoconazole or CYP51A1 siRNA rescued cancer cell viability and EGFR degradation. Inactivation of SC4MOL markedly sensitized A431 xenografts to cetuximab, a therapeutic anti-EGFR antibody. Analysis of Nsdhl-deficient Bpa1H/+ mice confirmed dramatic and selective loss of internalized PDGFR in fibroblasts, and reduced activation of EGFR and its effectors in regions of skin lacking NSDHL.

The loss of Dab2 is closely associated with the transition of ovarian surface epithelial cells to premalignant states and is likely involved in the initiation of ovarian tumorigenicity. Transient loss of collagen IV and laminin in the basement membrane of the premalignant epithelium and subsequent inactivation of Dab2 are common early events associated with tumorigenicity of the ovarian surface epithelium.