To enable stratification and barrier function, the epidermis must permit self-renewal while maintaining adhesive connections. By generating K14-GFP-actin mice to monitor actin dynamics in cultured primary keratinocytes, we uncovered a role for the actin cytoskeleton in establishing cellular organization. During epidermal sheet formation, a polarized network of nascent intercellular junctions and radial actin cables assemble in the apical plane of the monolayer. These actin fibers anchor to a central actin-myosin network, creating a tension-based plane of cytoskeleton across the apical surface of the sheet. Movement of the sheet surface relative to its base expands the zone of intercellular overlap, catalyzing new sites for nascent intercellular junctions. This polarized cytoskeleton is dependent upon alpha-catenin, Rho, and Rock, and its regulation may be important for wound healing and/or stratification, where coordinated tissue movements are involved.

ACF7 is a member of the spectraplakin family of cytoskeletal crosslinking proteins possessing actin and microtubule binding domains. Here, we show that ACF7 is an essential integrator of MT-actin dynamics. In endodermal cells, ACF7 binds along microtubules but concentrates at their distal ends and at cell borders when polarized. In ACF7's absence, microtubules still bind EB1 and CLIP170, but they no longer grow along polarized actin bundles, nor do they pause and tether to actin-rich cortical sites. The consequences are less stable, long microtubules with skewed cytoplasmic trajectories and altered dynamic instability. In response to wounding, ACF7 null cultures activate polarizing signals, but fail to maintain them and coordinate migration. Rescue of these defects requires ACF7's actin and microtubule binding domains. Thus, spectraplakins are important for controlling microtubule dynamics and reinforcing links between microtubules and polarized F-actin, so that cellular polarization and coordinated cell movements can be sustained.

alphabeta1 integrins have been implicated in the survival, spreading, and migration of cells and tissues. To explore the underlying biology, we identified conditions where primary beta1 null keratinocytes adhere, proliferate, and display robust alphavbeta6 integrin-induced, peripheral focal contacts associated with elaborate stress fibers. Mechanistically, this appears to be due to reduced FAK and Src and elevated RhoA and Rock activities. Visualization on a genetic background of GFPactin shows that beta1 null keratinocytes spread, but do so aberrantly, and when induced to migrate from skin explants in vitro, the cells are not able to rapidly reorient their actin cytoskeleton toward the polarized movement. As judged by RFPzyxin/GFPactin videomicroscopy, the alphavbeta6-actin network does not undergo efficient turnover. Without the ability to remodel their integrin-actin network efficiently, alphabeta1-deficient keratinocytes cannot respond dynamically to their environment and polarize movements.

The proposed sphenoid sinus pneumatization classification in the coronal plane is simple and reproducible. It predicts the distance between vidian and maxillary nerve, determines the size of the surgical window to access the middle cranial fossa transnasally, and instructs on the potential risk to neurovascular structures during surgery.

Background:Cisplatin-radiotherapy is a preferred standard for locally advanced, head and neck squamous cell carcinoma (HNSCC). However, the cisplatin-attributable survival benefit is small and toxicity substantial. A biomarker of cisplatin resistance could guide treatment selection and spare morbidity. The ERCC1-XPF nuclease is critical to DNA repair pathways resolving cisplatin-induced lesions.Methods:In a phase II trial, patients with untreated Stage III-IVb HNSCC were randomised to cisplatin-radiotherapy with/without erlotinib. Archived primary tumours were available from 90 of 204 patients for this planned substudy. Semi-quantitative ERCC1 protein expression (H-score) was determined using the FL297, 4F9, and 8F1 antibodies. The primary analysis evaluated the relationship between continuous ERCC1 protein expression and progression-free survival (PFS). Secondary analyses included two pre-specified ERCC1 cutpoints and performance in HPV-associated disease.Results:Higher ERCC1 expression was associated with inferior PFS, as measured by the specific antibodies FL297 (HR=2.5, 95% CI=1.1–5.9, P=0.03) and 4F9 (HR=3.0, 95% CI=1.2–7.8, P=0.02). Patients with increased vs decreased/normal ERCC1 expression experienced inferior PFS (HR=4.8 for FL297, P=0.003; HR=5.5 for 4F9, P=0.007). This threshold remained prognostic in HPV-associated disease.Conclusion:ERCC1-XPF protein expression by the specific FL297 and 4F9 antibodies is prognostic in patients undergoing definitive cisplatin-radiotherapy for HNSCC, irrespective of HPV status.

Purpose Tumor-specific biomarkers that predict resistance to DNA damaging agents may improve therapeutic outcomes by guiding the selection of effective therapies and limiting morbidity related to ineffective approaches. XPF (ERCC4) is an essential component of several DNA repair pathways and XPF-deficient cells are exquisitely sensitive to DNA damaging agents. The purpose of this study was to determine whether XPF expression levels predict clinical response to DNA damaging agents in head and neck squamous cell carcinoma (HNSCC). Experimental Design Quantitative immunohistochemistry was used to measure XPF expression in tumors from a cohort of 80 patients with newly diagnosed HNSCC treated with radiation therapy with or without platinum-based chemotherapy; samples were collected prospectively. Genomic DNA isolated from blood samples was analyzed for nine single nucleotide polymorphisms in the XPF gene using a custom array. The primary endpoint was progression-free survival (PFS). Results XPF expression was higher in tumors from the oral cavity than from the other sites (p<0.01). High XPF expression correlated with early time to progression both by univariate (HR =1.87, p=0.03) and multivariate analysis (HR =1.83, p=0.05). The one year PFS for high expressers was 47% (95% CI = 31% – 62%) compared to 72% (95% CI = 55% – 83%) for low expressers. In addition, we identified four XPF single nucleotide polymorphisms (SNPs) that demonstrated marginal association with treatment failure. Conclusions Expression level of XPF in HNSCC tumors correlates with clinical response to DNA damaging agents. XPF has potential to guide next-generation personalized cancer therapy.

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Objectives To describe patterns of primary surgical treatments in patients with T4b oral cavity squamous cell carcinoma (OCSCC). Study Design Historical cohort study. Setting National Cancer Database. Methods Review of the National Cancer Database between 2004 and 2017 for all T4b OCSCCs. Only patients with curative treatment methods were included in the survival analysis. Surgical and nonsurgical outcomes were compared by multivariable and propensity score matching analysis. Results A total of 1515 cases of T4b OCSCC were identified. A minority of patients (n = 363, 24.0%) underwent curative treatment; among these, 206 (56.7%) underwent primary surgery. Median length of follow-up was 24 months. The 90-day mortality of patients who underwent surgical treatment was 1.0%. The 2-year survival was higher for patients who underwent surgery + chemoradiotherapy (CRT) as compared with CRT (64.6% vs 45.2%, P < .001). On multivariable analysis, surgery + CRT was associated with longer survival. In a propensity score–matched cohort of 312 patients, 2-year survival remained higher in the surgical group versus the nonsurgical group (59.4% vs 45.5%, P = .02). Among patients who underwent surgery + CRT, there was no difference in 2-year survival between clinical T4a and T4b (59% vs 64.6%, P = .20). Conclusions A minority of patients with T4b OCSCC undergo treatments with curative intent. A subset of patients underwent primary surgical treatment, which was associated with longer survival. The T4b classification might entail a heterogenous group, and further studies in revision of this classification might be justified.