Aberrant kinase signaling: lessons from head and neck cancer

Genome-Wide Identification and Characterization of Tyrosine Kinases in the Silkworm, Bombyx mori

The tyrosine kinases (TKs) are important parts of metazoan signaling pathways and play significant roles in cell growth, development, apoptosis and disease. Genome-wide characterization of TKs has been conducted in many metazoans, however, systematic information about this family in Lepidoptera is still lacking. We retrieved 33 TK-encoding genes in silkworm and classified them into 25 subfamilies by sequence analysis, without members in AXL, FRK, PDGFR, STYK1 and TIE subfamilies. Although domain sequences in each subfamily are conserved, TKs in vertebrates tend to be remarkably conserved and stable. Our results of phylogenetic analysis supported the previous conclusion for the second major expansion of TK family. Gene-Ontology (GO) analysis revealed that a higher proportion of BmTKs played roles in binding, catalysis, signal transduction, metabolism, biological regulation and response to stimulus, compared to all silkworm genes annotated in GO. Moreover, the expression profile analysis of BmTKs among multiple tissues and developmental stages demonstrated that many genes exhibited stage-specific and/or sex-related expression during embryogenesis, molting and metamorphosis, and that 8 BmTKs presented tissue-specific high expression. Our study provides systematic description of silkworm tyrosine kinases, and may also provide further insights into metazoan TKs and assist future studies addressing their functions.

Epidermal growth factor receptor expression is predictive of poor prognosis in feline cutaneous squamous cell carcinoma

The aim of this study was to investigate epidermal growth factor receptor (EGFR) expression in feline cutaneous squamous cell carcinoma (FC-SCC) and assess its prognostic role. Nineteen formalin-fixed paraffin-embedded excisional biopsies of FC-SCC were tested for EGFR expression using immunohistochemistry (IHC). Relationships between EGFR expression and histopathological parameters (differentiation, mitotic activity), disease-free interval (DFI) and overall survival (OS) at 24 months were further investigated. Fourteen of 19 tumours (73.7%) were positive for EGFR, with great variation in intensity and proportion of labelled cells. EGFR expression was not correlated with tumour differentiation or mitotic activity. Nine cats (47.4%) died of tumour-related causes. Patients with EGFR-positive tumours had a significantly worse outcome (P=0.0217), with decreased DFIs (P=0.0075) and survival times (P=0.0391). These data suggest that EGFR expression carries a negative prognostic significance in FC-SCC. EGFR inhibitors in association with conventional treatments may improve outcome for the subgroup of cats with EGFR-positive tumours.

Molecular mechanisms of head and neck cancer

Despite advances in understanding the underlying genetics, squamous cell carcinoma of the head and neck (SCCHN) remains a major health risk and one of the leading causes of mortality in the world. Current standards of treatment have significantly improved long-term survival rates of patients, but second tumors and metastases still remain the most frequent cause of high mortality in SCCHN patients. A better understanding of the underlying genetic mechanisms of SCCHN tumorigenesis will help in developing better diagnostics and, hence, better cures. In this article we will briefly outline the current state of diagnostics and treatment and our understanding of the molecular causes of SCCHN.

Gene expansion and retention leads to a diverse tyrosine kinase superfamily in amphioxus

Tyrosine kinase (TK) proteins play a central role in cellular behavior and development of animals. The expansion of this superfamily is regarded as a key event in the evolution of the complex signaling pathways and gene networks of metazoans and is a prominent example of how shuffling of protein modules may generate molecular novelties. Using the intron/exon structure within the TK domain (TK intron code) as a complementary tool for the assignment of orthology and paralogy, we identified and studied the 118 TK proteins of the amphioxus Branchiostoma floridae genome to elucidate TK gene family evolution in metazoans and chordates in particular. Unlike all characterized metazoans to date, amphioxus has members of all known widespread TK families, with not a single loss. Putting amphioxus TKs in an evolutionary context, including new data from the cnidarian Nematostella vectensis, the echinoderm Strongylocentrotus purpuratus, and the ascidian Ciona intestinalis, we suggest new evolutionary histories for different TK families and draw a new global picture of gene loss/gain in the different phyla. Surprisingly, our survey also detected an unprecedented expansion of a group of closely related TK families, including TIE, FGFR, PDGFR, and RET, due most probably to massive gene duplication and exon shuffling. Based on their highly similar intron/exon structure at the TK domain, we suggest that this group of TK families constitute a superfamily of TK proteins, which we termed EXpanding TK, after their seemingly unique propensity to gene duplication and exon shuffling, not only in amphioxus but also across all metazoan groups. Due to this extreme tendency to both retention and expansion of TK genes, amphioxus harbors the richest and most diverse TK repertoire among all metazoans studied so far, retaining most of the gene complement of its ancestors, but having evolved its own repertoire of genetic novelties.