TGF-β plays a dual role in epithelial malignancies, including head and neck squamous cell carcinoma (HNSCC). Attenuation of canonical TGF-β signaling enhances de novo tumor development, while TGF-β overexpression and signaling paradoxically promotes malignant progression. We recently observed that TGF-β-induced growth arrest response is attenuated, in association with aberrant activation of Nuclear Factor-κB (NF-κB), a transcription factor which promotes malignant progression in HNSCC. However, what role cross-talk between components of the TGF-β and NF-κB pathways plays in altered activation of these pathways has not been established. Here, we show TGF-β receptor II and TGF-β-activated kinase 1 (TAK1) are predominantly expressed in a subset of HNSCC tumors with nuclear activation of NF-κB family member RELA (p65). Further, TGF-β1 treatment induced sequential phosphorylation of TAK1, IKK, IκBα, and RELA in human HNSCC lines. TAK1 enhances TGF-β-induced NF-κB activation, as TAK1 siRNA knock-down decreased TGF-β1-induced phosphorylation of IKK, IκB, and RELA, degradation of IκBα, nuclear translocation, and DNA binding of RELA, and NF–κB-induced reporter and target gene transcription. Functionally, TAK1 siRNA inhibited cell proliferation, migration and invasion. Celastrol, a TAK1 inhibitor and anti-inflammatory used in traditional Chinese medicine, also decreased TGF-β1-induced phosphorylation of TAK1 and RELA, suppressed basal, TGF-β1- and TNFα-induced NF-κB reporter gene activity, and cell proliferation, while increasing sub-G0 DNA fragmentation and Annexin V markers of apoptosis. Furthermore, TGF-β and RELA activation promoted SMAD7 expression. In turn, SMAD7 preferentially suppressed TGF-β-induced SMAD and NF-κB reporters when compared with constitutive or TNF-α-induced NF-κB reporter gene activation. Thus, cross-talk by TGF-β via TAK1 and NF-κB promotes the malignant phenotype of HNSCC. Moreover, NF-κB may contribute to the downstream attenuation of canonical TGF-β signaling through increased SMAD7 expression. Celastrol highlights the therapeutic potential of agents targeting TAK1 as a key node in this pro-oncogenic TGF-β-NF-κB signal pathway.

Importance of the field Recent advances in understanding the oncogenesis of head and neck squamous cell carcinomas (HNSCC) have revealed multiple dysregulated signaling pathways. One frequently altered axis is the EGFR/PI3K/Akt/mTOR pathway. This pathway plays a central role in numerous cellular processes including metabolism, cell growth, apoptosis, survival and differentiation, which ultimately contributes to HNSCC progression. What the reader will gain This article reviews the current understanding of EGFR/PI3K/Akt/mTOR signaling in HNSCC, including the impact of both genetic and epigenetic alterations. This review further highlights the potential of targeting this signaling cascade as a promising therapeutic approach in the treatment of HNSCC. Areas covered in this review Books, journals, databases and websites have been searched to provide a current review on the subject. Take home message Genetic alterations of several nodes within this pathway, including both genetic and epigenetic changes, leading to either oncogene activation or inactivation of tumor suppressors, have frequently been implicated in HNSCC. Consequently, drugs that target the central nodes of this pathway have become attractive for molecular oriented cancer therapies. Numerous preclinical and clinical studies are being performed in HNSCC, however, more studies are still needed to better understand the biology of this pathway.

Renibacterium salmoninarum is the causative agent of bacterial kidney disease and a significant threat to healthy and sustainable production of salmonid fish worldwide. This pathogen is difficult to culture in vitro, genetic manipulation is challenging, and current therapies and preventative strategies are only marginally effective in preventing disease. The complete genome of R. salmoninarum ATCC 33209 was sequenced and shown to be a 3,155,250-bp circular chromosome that is predicted to contain 3,507 open-reading frames (ORFs). A total of 80 copies of three different insertion sequence elements are interspersed throughout the genome. Approximately 21% of the predicted ORFs have been inactivated via frameshifts, point mutations, insertion sequences, and putative deletions. The R. salmoninarum genome has extended regions of synteny to the Arthrobacter sp. strain FB24 and Arthrobacter aurescens TC1 genomes, but it is approximately 1.9 Mb smaller than both Arthrobacter genomes and has a lower G؉C content, suggesting that significant genome reduction has occurred since divergence from the last common ancestor. A limited set of putative virulence factors appear to have been acquired via horizontal transmission after divergence of the species; these factors include capsular polysaccharides, heme sequestration molecules, and the major secreted cell surface antigen p57 (also known as major soluble antigen). Examination of the genome revealed a number of ORFs homologous to antibiotic resistance genes, including genes encoding ␤-lactamases, efflux proteins, macrolide glycosyltransferases, and rRNA methyltransferases. The genome sequence provides new insights into R. salmoninarum evolution and may facilitate identification of chemotherapeutic targets and vaccine candidates that can be used for prevention and treatment of infections in cultured salmonids.

BackgroundThe chlamydiae alter many aspects of host cell biology, including the division process, but the molecular biology of these alterations remains poorly characterized. Chlamydial inclusion membrane proteins (Incs) are likely candidates for direct interactions with host cell cytosolic proteins, as they are secreted to the inclusion membrane and exposed to the cytosol. The inc gene CT223 is one of a sequential set of orfs that encode or are predicted to encode Inc proteins. CT223p is localized to the inclusion membrane in all tested C. trachomatis serovars.ResultsA plasmid transfection approach was used to examine the function of the product of CT223 and other Inc proteins within uninfected mammalian cells. Fluorescence microscopy was used to demonstrate that CT223, and, to a lesser extent, adjacent inc genes, are capable of blocking host cell cytokinesis and facilitating centromere supranumeracy defects seen by others in chlamydiae-infected cells. Both phenotypes were associated with transfection of plasmids encoding the carboxy-terminal tail of CT223p, a region of the protein that is likely exposed to the cytosol in infected cells.ConclusionThese studies suggest that certain Inc proteins block cytokinesis in C. trachomatis-infected cells. These results are consistent with the work of others showing chlamydial inhibition of host cell cytokinesis.