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Human papillomavirus-associated (HPV+) head and neck squamous cell carcinoma (HNSCC) is the most common HPV-associated cancer in the United States, with a rapid increase in incidence over the last two decades. The burden of HPV+ HNSCC is likely to continue to rise, and given the long latency between infection and the development of HPV+ HNSCC, it is estimated that the effect of the HPV vaccine will not be reflected in HNSCC prevalence until 2060. Efforts have begun to decrease morbidity of standard therapies for this disease, and its improved characterization is being leveraged to identify and target molecular vulnerabilities. Companion biomarkers for new therapies will identify responsive tumors. A more basic understanding of two mechanisms of HPV carcinogenesis in the head and neck has identified subtypes of HPV+ HNSCC that correlate with different carcinogenic programs and that identify tumors with good or poor prognosis. Current development of biomarkers that reliably identify these two subtypes, as well as biomarkers that can detect recurrent disease at an earlier time, will have immediate clinical application. [ABSTRACT FROM AUTHOR]

Prior to the next generation sequencing and characterization of the tumor genome landscape, mutations in the SWI/SNF chromatin remodeling complex and the KEAP1-NRF2 signaling pathway were underappreciated. While these two classes of mutations appeared to independently contribute to tumor development, recent reports have demonstrated a mechanistic link between these two regulatory mechanisms in specific cancer types and cell models. In this work, we expand upon these data by exploring the relationship between mutations in BAF and PBAF subunits of the SWI/SNF complex and activation of NRF2 signal transduction across many cancer types. ARID1A/B mutations were strongly associated with NRF2 transcriptional activity in head and neck squamous carcinomas (HNSC). Many additional tumor types showed significant association between NRF2 signaling and mutation of specific components of the SWI/SNF complex. Different effects of BAF and PBAF mutations on the polarity of NRF2 signaling were observed. Overall, our results support a context-dependent functional link between SWI/SNF and NRF2 mutations across human cancers and implicate ARID1A inactivation in HPV-negative HNSC in promoting tumor progression and survival through activation of the KEAP1-NRF2 signaling pathway. The tumor-specific effects of these mutations open a new area of study for how mutations in the KEAP1-NRF2 pathway and the SWI/SNF complex contribute to cancer. [ABSTRACT FROM AUTHOR]

We analyzed transcriptional data from 104 HPV+ (Human papillomavirus) HNSCC (head and neck squamous cell carcinoma) tumors together with two publicly available sources to identify highly robust transcriptional programs (modules) which could be detected consistently despite heterogeneous sequencing and quantification methodologies. Among 22 modules identified, we found a single module that naturally subclassifies HPV+ HNSCC tumors based on a bimodal pattern of gene expression, clusters all atypical features of HPV+ HNSCC biology into a single subclass, and predicts patient outcome in four independent cohorts. The subclass-defining gene set was strongly correlated with Nuclear factor kappa B (NF-κB) target expression. Tumors with high expression of this NF-κB module were rarely associated with activating PIK3CA alterations or viral integration, and also expressed higher levels of HPHPV E2 and had decreased APOBEC mutagenesis. Alternatively, they harbored inactivating alterations of key regulators of NF-κB, TNF receptor associated factor 3 (TRAF3), and cylindromatosis (CYLD), as well as retinoblastoma protein (RB1). HPV+ HNSCC cells in culture with experimental depletion of TRAF3 or CYLD displayed increased expression of the subclass-defining genes, as well as robust radio-sensitization, thus recapitulating both the tumor transcriptional state and improved treatment response observed in patient data. Across all gene sets investigated, methylation to expression correlations were the strongest for the subclass-defining, NF-κB-related genes. Increased tumor-infiltrating CD4+ T cells and increased Estrogen receptors alpha (ERa) expression were identified in NF-κB active tumors. Based on the relatively high rates of cure in HPV+ HNSCC, deintensification of therapy to reduce treatment-related morbidity is being studied at many institutions. Tumor subclassification based on oncogenic subtypes may help guide the selection of therapeutic intensity or modality for patients with HPV+ HNSCC. [ABSTRACT FROM AUTHOR]

Background: Human papillomavirus–positive (HPV+) squamous cell carcinoma of the oropharynx (OPSCC) is the most prevalent HPV‐associated malignancy in the United States. Favorable treatment outcomes have led to increased interest in treatment de‐escalation to reduce treatment morbidity as well as the development of prognostic markers to identify appropriately low‐risk patients. Intratumoral genomic heterogeneity and copy number alteration burden have been demonstrated to be predictive of poor outcomes in many other cancers; therefore, we sought to determine whether intratumor heterogeneity and genomic instability are associated with poor outcomes in HPV+ OPSCC. Methods: Tumor heterogeneity estimates were made based on targeted exome sequencing of 45 patients with HPV+ OPSCC tumors. Analysis of an additional cohort of HPV+ OPSCC tumors lacking matched normal sequencing allowed copy number analysis of 99 patient tumors. Results: High intratumorally genomic heterogeneity and high numbers of copy number alterations were strongly associated with worse recurrence‐free survival. Tumors with higher heterogeneity and frequent copy number alterations were associated with loss of distal 11q, which encodes key genes related to double‐strand break repair, including ATM and MRE11A. Conclusions: Both intratumor genomic heterogeneity and high‐burden copy number alterations are strongly associated with poor recurrence‐free survival in patients with HPV+ OPSCC. The drivers of genomic instability and heterogeneity in these tumors remains to be elucidated. However, 11q loss and defective DNA double‐strand break repair have been associated with genomic instability in other solid tumors. Copy number alteration burden and intratumoral heterogeneity represent promising avenues for risk stratification of patients with HPV+OPSCC. Molecular markers are needed to determine which human papillomavirus (HPV)‐positive patients with squamous cell carcinoma of the oropharynx (OPSCC) are best served by reduced intensity treatment, which has the potential to reduce severe treatment‐related morbidity. We demonstrate that 11q‐related copy number variant burden and heterogeneity are highly associated with poor recurrence‐free survival in patients with HPV‐positive OPSCC and may have potential as translational biomarkers. [ABSTRACT FROM AUTHOR]

• Diagnosis to surgery time (TTS) and short-term survival increased between 2004 and 2019. • Time from diagnosis to surgery was affected more in non-academic centers. • Very short and very long TTS were associated with increased mortality-risk. • HPV + HNSCC patients had the highest risk to die among those with TTS > 75 days. • The 2021 NCDB data are required for a comprehensive analysis of TTS in 2020. The delivery of healthcare has changed significantly over the past decades. This study analyzes the clinicodemographic factors and treatment patterns of head and neck squamous cell carcinoma (HNSCC) patients between 2004 and 2020. Retrospective cohort analysis of HNSCC patients from the National Cancer Data Base from 2004 to 2020. A total of 164,290 patients were included. Increased times from diagnosis to definitive surgery (TTS) were seen across all facility types (academic centers, AC; non-academic centers, NAC) between 2004 and 2019, with NAC affected more. TTS < 15 days (RR = 1.05, 95%CI:1.05–1.09) and > 75 days (1.07, 95%CI:1.05–1.09) were associated with increased mortality risk. This association was more prominent among HPV + HNSCC (RR = 1.45; 95%CI:1.18–1.78). Treatment in AC was associated with a decreased mortality risk (RR = 0.94, 95%CI:0.93–0.95). Despite the universal increase in wait times from 2004 to 2019, short-term mortality was significantly decreased from 2016 to 2019, relative to 2004–2007 (3-month mortality: RR = 0.77, 95%CI:0.70–0.85; 12-month mortality: RR = 0.80, 95%CI:0.77–0.84). Wait times decreased in 2020. TTS increased between 2004 and 2019, with NAC affected more. However, despite longer wait times, short-term survival increased significantly. Very short (<15 days) and very long (>75 days) TTS were associated with increased mortality risk. Patients with HPV + HNSCC have the highest increase among those treated > 75 days from diagnosis. Treatment at AC was associated with improved survival, which could be explained by the presence of multidisciplinary teams and subspecialists that may be less available at NAC. The 2021 NCDB data are required for a comprehensive analysis of wait times in 2020. [ABSTRACT FROM AUTHOR]

The native states of globular proteins have been accessed in atomic detail by X-ray crystallography and nuclear magnetic resonance spectroscopy, yet characterization of denatured proteins beyond global metrics has proven to be elusive. Denatured proteins have been observed to exhibit global geometric properties of a random coil polymer. However, this does not preclude the existence of nonrandom, local conformational bias that may be significant for protein folding and function. Indeed, circular dichroism (CD) spectroscopy and other methods have suggested that the denatured state contains considerable local bias to the polyproline II (PII) conformation. Here, we develop predictive models to determine the extent that temperature and the chemical denaturant urea modulate PII propensity. In agreement with our predictive model, PII propensity is observed experimentally to decrease with an increase in temperature. Conversely, urea appears to promote the PII conformation as determined by CD and isothermal titration calorimetry. Importantly, the calorimetric data are in quantitative agreement with a model that predicts the stability of the PII helix relative to other denatured state conformations based upon solvent accessible surface area and experimentally measured Gibbs transfer free energies. The ability of urea to promote the PII conformation can be attributed to the favorable interaction of urea with the peptide backbone. Thus, perturbing denatured states by temperature or cosolutes has subtle, yet opposing, impacts on local PII conformational biases. These results have implications for protein folding as well as for the function of signaling proteins that bind proline-rich targets in globular or intrinsically disordered proteins. [ABSTRACT FROM AUTHOR]

Elucidating the complex interplay between protein structure and dynamics is a prerequisite to an understanding of both function and adaptation in proteins. Unfortunately, it has been difficult to experimentally decouple these effects because it is challenging to rationally design mutations that will either affect the structure but not the dynamics, or that will affect the dynamics but not the structure. Here we adopt a mutation approach that is based on a thermal adaptation strategy observed in nature, and we use it to study the binding interaction of Escherichia coil adenylate kinase (AK). We rationally design several single-site, surface-exposed glycine mutations to selectively perturb the excited state conformational repertoire, leaving the ground-state X-ray crystallographic structure unaffected. The results not only demonstrate that the conformational ensemble of AK is significantly populated by a locally unfolded state that is depopulated upon binding, but also that the excited-state conformational ensemble can be manipulated through mutation, independent of perturbations of the ground-state structures. The implications of these results are twofold. First, they indicate that it is possible to rationally design dynamic allosteric mutations, which do not propagate through a pathway of structural distortions connecting the mutated and the functional sites. Secondly and equally as important, the results reveal a general strategy for thermal adaptation that allows enzymes to modulate binding affinity by controlling the amount of local unfolding in the native-state ensemble. These findings open new avenues for rational protein design and fundamentally illuminate the role of local unfolding in function and adaptation. [ABSTRACT FROM AUTHOR]

Objectives: Patients with laryngeal squamous cell carcinoma (LSCC) often fail radiation therapy (RT), when received as monotherapy or in combination with other treatment modalities. Mechanisms for RT failure are poorly understood. We hypothesized that tumors failing RT would have increased rates of somatic mutations in genes associated with radiation resistance, particularly in genes associated with the NFE2L2 oxidative stress pathway. Using targeted exome sequencing on pretreated LSCC tumors, we retrospectively compared somatic mutation profile with clinical data and response to treatment. Methods: Tumors were classified as either radiation‐resistant (RR) or radiation‐sensitive (RS). RR was defined as persistent or recurrent disease within 2 years of receiving full‐dose RT. Early stage (ES) LSCC was defined as Stage I or II tumors without lymph node involvement. Eight genes associated with radiation resistance were prioritized for analysis. RT‐qPCR was performed on five NFE2L2 pathway genes. Results: Twenty LSCC tumors were included and classified as either RR (n = 8) or RS (n = 12). No differences in individual rates of somatic mutations by genes associated with radiation resistance were identified. Higher rates of total mutational burden (TMB) and increased alterations associated with the NFE2L2 pathway was observed in RR vs RS tumors (P <.05). In an analysis of only ES‐LSCC patients (RR, n = 3 and RS, n = 3), RR tumors had increased NFE2L2 somatic pathway mutations (P =.014) and increased NQO1 mRNA expression (P =.05). Conclusion: Increased TMB and NFE2L2 pathway alterations were associated with radiation resistance in LSCC. NQO1 mRNA expression may serve as a biomarker for RT response in ES‐LSCC. Level of Evidence: II1. [ABSTRACT FROM AUTHOR]

Abstract: It is now well-known that proteins exist at equilibrium as ensembles of conformational states rather than as unique static structures. Here we review from an ensemble perspective important biological effects of such spontaneous fluctuations on protein allostery, function, and evolution. However, rather than present a thorough literature review on each subject, we focus instead on connecting these phenomena through the ensemble-based experimental, theoretical, and computational investigations from our laboratory over the past decade. Special emphasis is given to insights that run counter to some of the prevailing ideas that have emerged over the past 40years of structural biology research. For instance, when proteins are viewed as conformational ensembles rather than as single structures, the commonly held notion of an allosteric pathway as an obligate series of individual structural distortions loses its meaning. Instead, allostery can result from energetic linkage between distal sites as one Boltzmann distribution of states transitions to another. Additionally, the emerging principles from this ensemble view of proteins have proven surprisingly useful in describing the role of intrinsic disorder in inter-domain communication, functional adaptation mediated by mutational control of fluctuations, and evolutionary conservation of the energetics of protein stability. [Copyright &y& Elsevier]

Simple Summary: Cell lines are widely used for research, but even commonly used cell lines may not be well characterized, making validation of published data and generalizing the results to the clinic problematic. Here, we have established a head and neck squamous cell carcinomas (HNSCC) cell line database. We believe that these cell lines are suitable models to study HNSCC disease in vitro and in vivo and may provide a valuable tool for investigators wishing to study the relation between e.g., hypoxia and radiosensitivity in HNSCC. To study head and neck squamous cell carcinomas (HNSCC) in vitro, a large variety of HNSCC cell lines have been developed. Here, we characterize a panel of 22 HNSCC cell lines, thereby providing a tool for research into tumor-specific treatment options in HNSCC. Both human papillomavirus (HPV) positive and HPV negative tumor cell lines were collected from commercial and collaborative sources. Short tandem repeat profiling was used to confirm or characterize the identity of the cell lines. Targeted sequencing was performed using a standard pathology single molecule Molecular Inversion Probe panel to detect mutations for 23 tumor suppressors and oncogenes. HPV status, p16 status, radiosensitivity data, and hypoxia data are summarized from all cell lines. We detected HPV transcripts in five cell lines, all of which overexpressed p16. One HPV negative cell line was also p16 positive. We detected mutations in KIT (SCCNij185), PIK3CA (SCCNij185), and CDKN2A (UT-SCC-5 and UT-SCC-38). TP53 mutations were the most frequent, occurring in 16/22 cell lines. HPV infection and TP53 mutations were almost mutually exclusive, with the exception of 93-VU-147T. The cell lines exhibited a wide range of sensitivities towards hypoxia and irradiation. Here, we provide a description of a set of frequently used HNSCC cell lines with diverse characteristics as found in HNSCC patients. [ABSTRACT FROM AUTHOR]