Despite remarkable advances in the genomic characterization of adult melanoma, the molecular pathogenesis of pediatric melanoma remains largely unknown. We analyzed 15 conventional melanomas (CMs), 3 melanomas arising in congenital nevi (CNMs), and 5 spitzoid melanomas (SMs), using various platforms, including whole genome or exome sequencing, the molecular inversion probe assay, and/or targeted sequencing. CMs demonstrated a high burden of somatic single-nucleotide variations (SNVs), with each case containing a TERT promoter (TERT-p) mutation, 13/15 containing an activating BRAF V600 mutation, and >80% of the identified SNVs consistent with UV damage. In contrast, the three CNMs contained an activating NRAS Q61 mutation and no TERT-p mutations. SMs were characterized by chromosomal rearrangements resulting in activated kinase signaling in 40%, and an absence of TERT-p mutations, except for the one SM that succumbed to hematogenous metastasis. We conclude that pediatric CM has a very similar UV-induced mutational spectrum to that found in the adult counterpart, emphasizing the need to promote sun protection practices in early life and to improve access to therapeutic agents being explored in adults in young patients. In contrast, the pathogenesis of CNM appears to be distinct. TERT-p mutations may identify the rare subset of spitzoid melanocytic lesions prone to disseminate.

Protein kinase A (PKA) is an evolutionarily conserved protein which has been studied in model organisms from yeast to man. Although the cAMP-PKA signaling system was the first mammalian second messenger system to be characterized, many aspects of this pathway are still not well understood. Owing to findings over the past decade implicating PKA signaling in endocrine (and other) tumorigenesis, there has been renewed interest in understanding the role of this pathway in physiology, particularly as it pertains to the endocrine system. Because of the availability of genetic tools, mouse modeling has become the pre-eminent system for studying the physiological role of specific genes and gene families as a means to understanding their relationship to human diseases. In this review, we will summarize the current data regarding mouse models that have targeted the PKA signaling system. These data have led to a better understanding of both the complexity and the subtlety of PKA signaling, and point the way for future studies, which may help to modulate this pathway for therapeutic effect.

Oropharyngeal carcinoma (OPC) can be classified into two equally prevalent sub-types depending on the presence of Human Papillomavirus (HPV). Patients with HPV-positive (HPV+) OPC represent a unique cohort with a distinct tumor biology and clinical behavior compared to HPV-negative (HPV-) OPC. Genetic studies have demonstrated chromosomal and gene expression changes associated with distinct sub-classes of OPC, although the proteomic consequences of HPV infection are not known. We analyzed sets of 10 HPV+ and 10 HPV− OPCs, and 10 normal adult oral epithelia using a standardized global proteomic analysis platform. This analysis yielded a total of 2,653 confidently identified proteins from which we chose 31 proteins on the basis of expression differences between HPV+, HPV− and normal epithelium for targeted protein quantiation. Analysis of differentially expressed proteins by HPV status revealed enrichment of proteins involved epithelial cell development, keratinization, and extracellular matrix organization in HPV− OPC while enrichment of proteins in DNA initiation and replication and cell cycle control was found for HPV+ OPC. Enrichment analysis for transcription factor targets identified transcription factors E2F1 and E2F4 to be highly expressed in HPV+ OPC. We also found high expression of argininosuccinate synthase 1 (ASS1) in HPV+ OPC suggesting HPV+ OPC is more dependent on conditionally essential amino acid, arginine, and this was confirmed on a OPC-specific tissue microarray. These identified proteomic changes reveal novel driving molecular pathways for HPV+ and HPV− OPC that may be pertinent in therapeutic strategies and outcomes of OPC.

Background-Protein kinase A signaling has long been known to play an important role in cardiac function. Dysregulation of the protein kinase A system, caused by mutation of the protein kinase A regulatory subunit gene PRKAR1A, causes the inherited tumor syndrome Carney complex, which includes cardiac myxomas as one of its cardinal features. Mouse models of this genetic defect have been unsatisfactory because homozygote null animals die early in development and heterozygotes do not exhibit a cardiac phenotype. Methods and Results-To study the cardiac-specific effects resulting from complete loss of Prkar1a, we used cre-lox technology to generate mice lacking this protein specifically in cardiomyocytes. Conditional knockout mice died at day 11.5 to 12.5 of embryogenesis with thin-walled, dilated hearts. These hearts showed elevated protein kinase A activity and decreased cardiomyocyte proliferation before demise. Analysis of the expression of transcription factors required for cardiogenesis revealed downregulation of key cardiac transcription factors such as the serum response factor, Gata4, and Nkx2-5. Although heart wall thickness was reduced overall, specific areas exhibited morphological changes consistent with myxomatous degeneration in the walls of knockout hearts. Conclusions-Loss of Prkar1a from the heart causes a failure of proper myocardial development with subsequent cardiac failure and embryonic demise. These changes appear to be due to suppression of cardiac-specific transcription by increased protein kinase A activity. These biochemical changes lead to myxoma-like changes, indicating that these mice may be a good model with which to study the formation of these tumors. ) signaling system is one of the central means by which cardiac function is regulated in the body. PKA activation is achieved by stimulation of 7-transmembrane Gprotein-coupled receptors, which couple to adenylate cyclase and produce cAMP. In the heart, cAMP production is classically medicated by the ␤1-and ␤2-adrenergic receptors, 1 although other receptors also use this same second messenger system. 2 Once generated, intracellular cAMP binds to the regulatory subunits of PKA, releasing the catalytic subunit, which phosphorylates proteins involved in contractile function, including key targets such as the ryanodine receptor 2 (Ryr2) and the sarcoplasmic Ca 2ϩ -ATPase. These effects modulate the actions of catecholamines on cardiac function. Upregulation of PKA activity has been posited to occur in the failing heart because of increased phosphorylation of PKA targets, 3,4 providing an explanation for the beneficial effects of ␤-blockade in these patients. Clinical Perspective p 1422From a genetic point of view, dysregulation of the PKA system has been associated with abnormalities of heart function in mouse models, 1 although corresponding human syndromes are generally unknown. The singular example of a PKA abnormality causing an inherited human syndrome affecting the heart is the Carney complex (CNC). This genetic disease is caused by...

Initial stages of embryonic development rely on rapid, synchronized cell divisions of the fertilized egg followed by a set of morphogenetic movements collectively called epiboly and gastrulation. Lzap is a putative tumor suppressor whose expression is lost in 30% of head and neck squamous cell carcinomas. Lzap activities include regulation of cell cycle progression and response to therapeutic agents. Here we explore developmental roles of the lzap gene during zebrafish morphogenesis. Lzap is highly conserved among vertebrates and is maternally deposited. Expression is initially ubiquitous during gastrulation, and later becomes more prominent in the pharyngeal arches, digestive tract and brain. Antisense morpholino-mediated depletion of Lzap resulted in delayed cell divisions and apoptosis during blastomere formation, resulting in fewer, larger cells. Cell cycle analysis suggested that Lzap loss in early embryonic cells resulted in a G2/M arrest. Furthermore, the Lzap-deficient embryos failed to initiate epiboly – the earliest morphogenetic movement in animal development – which has been shown to be dependent on cell adhesion and migration of epithelial sheets. Our results strongly implicate Lzap in regulation of cell cycle progression, adhesion and migratory activity of epithelial cell sheets during early development. These functions provide further insight into Lzap activity that may contribute not only to development, but also to tumor formation.