Comparison of tumors from the Cancer Genome Atlas (TCGA) reveals that head and neck squamous cell carcinomas (HNSCC) harbor the most frequent genomic amplifications of Fas-associated death domain (FADD), with or without Baculovirus Inhibitor of Apoptosis repeat containing BIRC2 (cIAP1), affecting ~30% of patients in association with worse prognosis. Here, we identified HNSCC cell lines harboring FADD/BIRC2 amplifications and overexpression by exome sequencing, RT-PCR and Western blot. In vitro, FADD or BIRC2 siRNA knockdown inhibited HNSCC displaying amplification and increased expression of these genes, supporting their functional importance in promoting proliferation. Birinapant, a novel SMAC mimetic, sensitized multiple HNSCC lines to cell death by agonists TNFα or TRAIL, and inhibited cIAP1>XIAP>IAP2. Combination of birinapant and TNFα induced sub-G0 DNA fragmentation in sensitive lines, and birinapant alone also induced significant G2/M cell cycle arrest and cell death in UM-SCC-46 cells. Gene transfer and expression of FADD sensitized resistant UM-SCC-38 cells lacking FADD amplification to birinapant and TNFα, supporting a role for FADD in sensitization to IAP inhibitor and death ligands. HNSCC varied in mechanisms of cell death, as indicated by reversal by inhibitors or protein markers of caspase-dependent apoptosis and/or RIPK1/MLKL-mediated necroptosis. In vivo, birinapant inhibited tumor growth and enhanced radiation induced TNFα, tumor responses, and host survival in UM-SCC-46 and -11B xenograft models displaying amplification and overexpression of FADD+/−BIRC2. These findings suggest that combination of SMAC mimetics such as birinapant plus radiation may be particularly active in HNSCC, which harbor frequent FADD/BIRC2 genomic alterations.

The trans-synaptic interaction of the cell-adhesion molecules teneurins (TENs) with latrophilins (LPHNs/ADGRLs) promotes excitatory synapse formation when LPHNs simultaneously interact with FLRTs. Insertion of a short alternatively-spliced region within TENs abolishes the TEN-LPHN interaction and switches TEN function to specify inhibitory synapses. How alternative-splicing regulates TEN-LPHN interaction remains unclear. Here, we report the 2.9 Å resolution cryo-EM structure of the TEN2-LPHN3 complex, and describe the trimeric TEN2-LPHN3-FLRT3 complex. The structure reveals that the N-terminal lectin domain of LPHN3 binds to the TEN2 barrel at a site far away from the alternatively spliced region. Alternative-splicing regulates the TEN2-LPHN3 interaction by hindering access to the LPHN-binding surface rather than altering it. Strikingly, mutagenesis of the LPHN-binding surface of TEN2 abolishes the LPHN3 interaction and impairs excitatory but not inhibitory synapse formation. These results suggest that a multi-level coincident binding mechanism mediated by a cryptic adhesion complex between TENs and LPHNs regulates synapse specificity.

Purpose: To identify deregulated and inhibitory miRNAs and generate novel mimics for replacement nanomedicine for head and neck squamous cell carcinomas (HNSCC). Experimental Design: We integrated miRNA and mRNA expression, copy number variation, and DNA methylation results from The Cancer Genome Atlas (TCGA), with a functional genome-wide screen. Results: We reveal that the miR-30 family is commonly repressed, and all 5 members sharing these seed sequence similarly inhibit HNSCC proliferation in vitro. We uncover a previously unrecognized inverse relationship with overexpression of a network of important predicted target mRNAs deregulated in HNSCC, that includes key molecules involved in proliferation (EGFR, MET, IGF1R, IRS1, E2F7), differentiation (WNT7B, FZD2), adhesion, and invasion (ITGA6, SER-PINE1). Reexpression of the most differentially repressed family member, miR-30a-5p, suppressed this mRNA program , selected signaling proteins and pathways, and inhibited cell proliferation, migration, and invasion in vitro. Furthermore, a novel miR-30a-5p mimic formulated into a targeted nanomedicine significantly inhibited HNSCC xenograft tumor growth and target growth receptors EGFR and MET in vivo. Significantly decreased miR-30a/e family expression was related to DNA promoter hypermethylation and/or copy loss in TCGA data, and clinically with decreased diseasespecific survival in a validation dataset. Strikingly, decreased miR-30e-5p distinguished oropharyngeal HNSCC with poor prognosis in TCGA (P ¼ 0.002) and validation (P ¼ 0.007) datasets, identifying a novel candidate biomarker and target for this HNSCC subset. Conclusions: We identify the miR-30 family as an important regulator of signal networks and tumor suppressor in a subset of HNSCC patients, which may benefit from miRNA replacement nanomedicine therapy.

To investigate the contribution of nonmuscle myosin II-A (NM II-A) to early cardiac development we crossed Myh9 floxed mice and Nkx2.5 cre-recombinase mice. Nkx2.5 is expressed in the early heart (E7.5) and later in the tongue epithelium. Mice homozygous for deletion of NM II-A (ANkx/ANkx) are born at the expected ratio with normal hearts, but consistently develop an invasive squamous cell carcinoma (SCC) of the tongue (32/32 ANkx/ANkx) as early as E17.5. To assess reproducibility a second, independent line of Myh9 floxed mice derived from a different embryonic stem cell clone was tested. This second line also develops SCC indistinguishable from the first (15/15). In ANkx/ANkx mouse tongue epithelium, genetic deletion of NM II-A does not affect stabilization of TP53, unlike a previous report for SCC. We attribute the consistent, early formation of SCC with high penetrance to the role of NM II in maintaining mitotic stability during karyokinesis.