Filopodial protrusion driven by density-dependent Ena-TOCA-1 interactions.

Filopodia are narrow actin-rich protrusions with important roles in neuronal development where membrane-binding adaptor proteins, such as I-BAR- and F-BAR-domain-containing proteins, have emerged as upstream regulators that link membrane interactions to actin regulators such as formins and proteins of the Ena/VASP family. Both the adaptors and their binding partners are part of diverse and redundant protein networks that can functionally compensate for each other. To explore the significance of the F-BAR domain-containing neuronal membrane adaptor TOCA-1 (also known as FNBP1L) in filopodia we performed a quantitative analysis of TOCA-1 and filopodial dynamics in Xenopus retinal ganglion cells, where Ena/VASP proteins have a native role in filopodial extension. Increasing the density of TOCA-1 enhances Ena/VASP protein binding in vitro, and an accumulation of TOCA-1, as well as its coincidence with Ena, correlates with filopodial protrusion in vivo. Two-colour single-molecule localisation microscopy of TOCA-1 and Ena supports their nanoscale association. TOCA-1 clusters promote filopodial protrusion and this depends on a functional TOCA-1 SH3 domain and activation of Cdc42, which we perturbed using the small-molecule inhibitor CASIN. We propose that TOCA-1 clusters act independently of membrane curvature to recruit and promote Ena activity for filopodial protrusion.

Impact of Neoadjuvant Chemotherapy on Concordance of PD-L1 Staining Fidelity between the Primary Tumor and Lymph Node Metastases in Bladder Cancer.

OBJECTIVE: To evaluate programmed death ligand 1 (PD-L1) staining fidelity between the primary tumor and associated lymph node metastases in bladder cancer. To secondarily evaluate whether neoadjuvant chemotherapy (NAC) affects this relationship. METHODS: Sixty-seven subjects with residual bladder cancer on cystectomy and associated positive lymph nodes were identified between 2008 and 2015. PD-L1 staining of tumor cells was evaluated using H score and 49 specimens were also evaluated using combined positive score (CPS). Univariable and multivariable logistic regression analysis were used to assess how various clinical variables affected odds of PD-L1 fidelity between primary and metastatic tumors. RESULTS: Tumor PD-L1 staining was concordant in 79.1% of cases and CPS was concordant in 79.6% of cases. NAC did not significantly impact odds of PD-L1 or CPS fidelity (OR 1.974, 95% CI 0.673-5.784, OR 0.500, 95% CI 0.093-2.700). Among clinical variables analyzed on univariable analysis of tumor PD-L1 fidelity, H-score, and PD-L1 staining intensity were associated with significantly increased odds of PD-L1 fidelity and the association with staining intensity was confirmed on multivariable analysis. CONCLUSION: PD-L1 fidelity between primary bladder tumors and nodal metastases was observed in >75% of cases in this study. Additionally, NAC was not shown to diminish this propensity to maintain PD-L1 staining status. Further standardization of immunohistochemistry of tumor and infiltrating imsmune cells in metastatic bladder cancer is needed to improve application of therapeutics.