Sara C. Shalin

Kinase Suppressor of Ras1 Compartmentalizes Hippocampal Signal Transduction and Subserves Synaptic Plasticity and Memory Formation

The ERK/MAP kinase cascade is important for long-term memory formation and synaptic plasticity, with a myriad of upstream signals converging upon ERK activation. Despite this convergence of signaling, neurons routinely activate appropriate biological responses to different stimuli. Scaffolding proteins represent a mechanism to achieve compartmentalization of signaling and the appropriate targeting of ERK-dependent processes. We report that kinase suppressor of Ras (KSR1) functions biochemically in the hippocampus to scaffold the components of the ERK cascade, specifically regulating the cascade when a membrane fraction of ERK is activated via a PKC-dependent pathway but not via a cAMP/PKA-dependent pathway. Specificity of KSR1-dependent signaling also extends to specific downstream targets of ERK. Behaviorally and physiologically, we found that the absence of KSR1 leads to deficits in associative learning and theta burst stimulation-induced LTP. Our report provides novel insight into the endogenous scaffolding role of KSR1 in controlling kinase activation within the nervous system.

Sebaceous neoplasia and the Muir-Torre syndrome: important connections with clinical implications.

Shalin S C, Lyle S, Calonje E & Lazar A J F
(2010) Histopathology56, 133–147
Sebaceous neoplasia and the Muir–Torre syndrome: important connections with clinical implications

Neuronal MEK is important for normal fear conditioning in mice

The extracellular signal‐regulated kinase (ERK) cascade has received much attention for its possible role in neuronal synaptic plasticity. Although ERK activation has been linked to learning behaviors and activity‐dependent neuronal function, much of the acquired data has relied upon pharmacological agents that suppress ERK function in both neurons and nonneuronal cells. To determine the function of neuronal ERK activity in learning, a new line of transgenic mice was generated wherein dominant‐negative MEK1, the upstream obligate activator of ERK1/2, was expressed by using a neuronal‐specific and pan‐neuronal Tα1 α‐tubulin promoter element. Mice expressing this construct exhibited decreased ERK1/2 activity in the hippocampus and thus were tested for learning impairments. In a battery of control tests, including open field, rotarod, and shock threshold, the transgenic mice displayed no deficits and performed as well as their wild‐type littermate counterparts. However, the mice displayed a significant impairment in contextual fear conditioning compared with the wild‐type littermates. These findings indicate that the MEK1/ERK1/2 cascade within neurons plays an important role in the processes of learning and memory.

Clear cell adenocarcinoma arising from endometriosis in abdominal wall cesarean section scar: a case report and review of the literature.

Malignancy arising in association with endometriosis is a rare but well‐documented phenomenon that was first described in the literature as early as 1925. Cutaneous endometriosis with subsequent malignant transformation is even more uncommon, and high clinical suspicion is required for diagnosis. The clinical differential diagnosis of these lesions includes a wide variety of entities, ranging from benign cysts to malignancies such as melanoma. We report a case of clear cell adenocarcinoma arising from endometriosis in a cesarean section scar in a 47‐year‐old woman, and we complete a review of the literature regarding this unusual entity.

P53 Staining Correlates with Tumor Type and Location in Sebaceous Neoplasms

Abstract Sebaceous neoplasms are commonly considered in their relationship to the Muir–Torre syndrome and the now well-documented loss of DNA mismatch repair proteins leading to microsatellite instability. However, sebaceous neoplasms showing microsatellite instability comprise only a subset of this group of tumors, and thus, alternative tumorigenic mechanisms must exist. This article explores the relationship of p53, a tumor suppressor implicated in other cutaneous malignancies, and sebaceous neoplasia. We examined 94 sebaceous tumors from 92 patients. Tumors with strong nuclear p53 staining were significantly associated with the diagnosis of sebaceous carcinoma compared with benign sebaceous lesions, most notably for periocular carcinomas. Importantly, nuclear mismatch repair protein expression was intact in all lesions showing p53 alterations, suggesting that p53 dysfunction may represent a divergent pathway in the molecular pathogenesis of these tumors.

Signal transduction mechanisms in memory disorders.

This chapter explores some of the molecular events contributing to memory formation and how, when these events malfunction, disturbances in memory occur. After a brief discussion of signaling in the hippocampus, we will explore the topics of human mental retardation syndromes that involve disruption of these processes, including Angelman syndrome (AS), Neurofibromatosis 1 (NF1)-associated learning disorders, Coffin-Lowry syndrome (CLS), Rubinstein-Taybi syndrome (RTS), and Rett syndrome (RTT).

Cutaneous basal cell carcinosarcomas: evidence of clonality and recurrent chromosomal losses

Cutaneous carcinosarcomas are heterogeneous group of tumors composed of malignant epithelial and mesenchymal components. Although mutation analyses have identified clonal changes between these morphologically disparate components in some subtypes of cutaneous carcinosarcoma, few cases have been analyzed thus far. To our knowledge, copy number variations (CNVs) and copy-neutral loss of heterozygosity (CN-LOH) have not been investigated in cutaneous carcinosarcomas. We analyzed 4 carcinosarcomas with basal cell carcinoma and osteosarcomatous components for CNVs/CN-LOH by comparative genomic hybridization/single-nucleotide polymorphism array, TP53 hot spot mutations by polymerase chain reaction and Sanger sequencing, and TP53 genomic rearrangements by fluorescence in situ hybridization. All tumors displayed multiple CNV/CN-LOH events (median, 7.5 per tumor). Three of 4 tumors displayed similar CNV/CN-LOH patterns between the epithelial and mesenchymal components within each tumor, supporting a common clonal origin. Recurrent changes included allelic loss at 9p21 (CDKN2A), 9q (PTCH1), and 17p (TP53). Allelic losses of chromosome 16 including CDH1 (E-cadherin) were present in 2 tumors and were restricted to the sarcomatous component. TP53 mutation analysis revealed an R248L mutation in both epithelial and mesenchymal components of 1 tumor. No TP53 rearrangements were identified. Our findings indicate that basal cell carcinosarcomas harbor CNV/CN-LOH changes similar to conventional basal cell carcinoma, with additional changes including recurrent 9p21 losses and a relatively high burden of copy number changes. In addition, most cutaneous carcinosarcomas show evidence of clonality between epithelial and mesenchymal components.

Indicators of responsiveness to immune checkpoint inhibitors

Modulation of the immune system can produce anti-tumor responses in various cancer types, including melanoma. Recently, immune checkpoint inhibitors (ICI), in single agent and combination regimens, have produced durable and long-lasting clinical responses in a subset of metastatic melanoma patients. These monoclonal antibodies, developed against CTLA-4 and PD-1, block immune-inhibitory receptors on activated T-cells, amplifying the immune response. However, even when using anti-CTLA-4 and anti-PD-1 in combination, approximately half of patients exhibit innate resistance and suffer from disease progression. Currently, it is impossible to predict therapeutic response. Here, we report the first proteomic and histone epigenetic analysis of patient metastatic melanoma tumors taken prior to checkpoint blockade, which revealed biological signatures that can stratify patients as responders or non-responders. Furthermore, our findings provide evidence of mesenchymal transition, a known mechanism of immune-escape, in non-responding melanoma tumors. We identified elevated histone H3 lysine (27) trimethylation (H3K27me3), decreased E-cadherin, and other protein features indicating a more mesenchymal phenotype in non-responding tumors. Our results have implications for checkpoint inhibitor therapy as patient specific responsiveness can be predicted through readily assayable proteins and histone epigenetic marks, and pathways activated in non-responders have been identified for therapeutic development to enhance responsiveness.

Quantitative Histone Mass Spectrometry Identifies Elevated Histone H3 Lysine 27 (Lys27) Trimethylation in Melanoma

Normal cell growth is characterized by a regulated epigenetic program that drives cellular activities such as gene transcription, DNA replication, and DNA damage repair. Perturbation of this epigenetic program can lead to events such as mis-regulation of gene transcription and diseases such as cancer. To begin to understand the epigenetic program correlated to the development of melanoma, we performed a novel quantitative mass spectrometric analysis of histone post-translational modifications mis-regulated in melanoma cell culture as well as patient tumors. Aggressive melanoma cell lines as well as metastatic melanoma were found to have elevated histone H3 Lys27 trimethylation (H3K27me3) accompanied by overexpressed methyltransferase EZH2 that adds the specific modification. The altered epigenetic program that led to elevated H3K27me3 in melanoma cell culture was found to directly silence transcription of the tumor suppressor genes RUNX3 and E-cadherin. The EZH2-mediated silencing of RUNX3 and E-cadherin transcription was also validated in advanced stage human melanoma tissues. This is the first study focusing on the detailed epigenetic mechanisms leading to EZH2-mediated silencing of RUNX3 and E-cadherin tumor suppressors in melanoma. This study underscores the utility of using high resolution mass spectrometry to identify mis-regulated epigenetic programs in diseases such as cancer, which could ultimately lead to the identification of biological markers for diagnostic and prognostic applications.

Nuclear factor XIIIa staining (clone AC-1A1 mouse monoclonal) is a highly sensitive marker of sebaceous differentiation in normal and neoplastic sebocytes.

Sebaceous proliferations are common and may be confused with other cutaneous neoplasms. Few useful or specific immunohistochemical markers for sebaceous differentiation are available. We incidentally observed strong factor XIIIa (Ventana clone AC‐1A1 on Ventana Benchmark Ultra stainer) nuclear staining in normal sebaceous glands and hypothesized that this might be a useful marker in sebaceous proliferations.