Inactivation of TGFβ receptors in stem cells drives cutaneous squamous cell carcinoma.

Melanoma patients treated with oncogenic BRAF inhibitors can develop cutaneous squamous cell carcinoma (cSCC) within weeks of treatment, driven by paradoxical RAS/RAF/MAPK pathway activation. Here we identify frequent TGFBR1 and TGFBR2 mutations in human vemurafenib-induced skin lesions and in sporadic cSCC. Functional analysis reveals these mutations ablate canonical TGFβ Smad signalling, which is localized to bulge stem cells in both normal human and murine skin.

Circulating tumour cells as tumour biomarkers in melanoma: detection methods and clinical relevance.

Circulating tumour cells (CTCs) are cells of solid tumour origin detectable in the peripheral blood. Their occurrence is considered a prerequisite step for establishing distant metastases. Metastatic melanoma was the first malignancy in which CTCs were detected and numerous studies have been published on CTC detection in melanoma at various stages of disease.

Collaboration of AMPK and PKC to induce phosphorylation of Ser413 on PIP5K1B resulting in decreased kinase activity and reduced PtdIns(4,5)P2 synthesis in response to oxidative stress and energy restriction.

The spatial and temporal regulation of the second messenger PtdIns(4,5)P2 has been shown to be crucial for regulating numerous processes in the cytoplasm and in the nucleus. Three isoforms of PIP5K1 (phosphatidylinositol 4-phosphate 5-kinase), A, B and C, are responsible for the regulation of the major pools of cellular PtdIns(4,5)P2. PIP5K1B is negatively regulated in response to oxidative stress although it remains unclear which pathways regulate its activity.

Mind the IQGAP.

The scaffold protein IQGAP1 regulates cell signaling through the RAF/MEK/ERK pathway. Recent data show that cancer cells in which the RAF/MEK/ERK pathway is activated are particularly sensitive to the disruption of IQGAP1 function. IQGAP drugs may be particularly effective in tumors that develop resistance to existing pathway drugs.

PtdIns5P and Pin1 in oxidative stress signaling.

Oxidative signaling is important in cellular health, involved in aging and contributes to the development of several diseases such as cancer, neurodegeneration and diabetes. Correct management of reactive oxygen species (ROS) prevents oxidative stress within cells and is imperative for cellular wellbeing. A key pathway that is regulated by oxidative stress is the activation of proline-directed stress kinases (p38, JNK).

PtdIns5P is an oxidative stress-induced second messenger that regulates PKB activation.

Oxidative stress initiates signaling pathways, which protect from stress-induced cellular damage, initiate apoptosis, or drive cells into senescence or into tumorigenesis. Oxidative stress regulates the activity of the cell survival factor PKB, through the regulation of PtdIns(3,4,5)P₃ synthesis. Whether oxidative stress regulates other phosphoinositides to control PKB activation is not clear.

Twenty-fourth annual Pezcoller symposium: Molecular basis for resistance to targeted agents.

The mechanisms of genetically determined mechanisms of resistance to several target drugs were discussed in breast cancer, melanoma, colorectal and prostate cancers, chronic myelogenous leukemia, small cell lung cancer, and medulloblastoma. In each case, heterogeneity of mechanisms was emphasized. In melanoma, therapeutic interference with the effects of BRAF mutations was repeatedly discussed.

Assessment of circulating biomarkers for potential pharmacodynamic utility in patients with lymphoma.

Purpose: Treatment efficacy and toxicity are difficult to predict in lymphoma patients. In this study, the utility of circulating biomarkers in predicting and/or monitoring treatment efficacy/toxicity were investigated.

Patients And Methods: Circulating biomarkers of cell death (nucleosomal DNA (nDNA) and cytokeratin 18 (CK18)), and circulating FLT3 ligand, a potential biomarker of myelosuppression, were assessed before and serially after standard chemotherapy in 49 patients with Hodgkin and non-Hodgkin lymphoma.

PIP4Kbeta interacts with and modulates nuclear localization of the high-activity PtdIns5P-4-kinase isoform PIP4Kalpha.

The beta-isoform of PIP4K (PtdIns5P-4-kinase) regulates the levels of nuclear PtdIns5P, which in turn modulates the acetylation of the tumour suppressor p53. The crystal structure of PIP4Kbeta demonstrated that it can form a homodimer with the two subunits arranged in opposite orientations. Using MS, isoform-specific antibodies against PIP4Ks, RNAi (RNA interference) suppression and overexpression studies, we show that PIP4Kbeta interacts in vitro and in vivo with the PIP4Kalpha isoform.

Lipid kinases: charging PtdIns(4,5)P2 synthesis.

Phosphatidylinositol (4,5) bisphosphate is a lipid second messenger that controls diverse cellular processes. Phosphatidylinositolphosphate-5-kinases synthesise this lipid at the plasma membrane, although it is not clear how the localisation of these kinases is controlled. A recent study suggests that the intrinsic surface charge of the plasma membrane may be an important factor.

High correspondence between Affymetrix exon and standard expression arrays.

Exon arrays aim to provide comprehensive gene expression data at the level of individual exons, similar to that provided on a per-gene basis by existing expression arrays. This report describes the performance of Affymetrix GeneChip Human Exon 1.0 ST array by using replicated RNA samples from two human cell lines, MCF7 and MCF10A, hybridized both to Exon 1.

The Saccharomyces cerevisiae spindle pole body (SPB) component Nbp1p is required for SPB membrane insertion and interacts with the integral membrane proteins Ndc1p and Mps2p.

The spindle pole body (SPB) in Saccharomyces cerevisiae functions to nucleate and organize spindle microtubules, and it is embedded in the nuclear envelope throughout the yeast life cycle. However, the mechanism of membrane insertion of the SPB has not been elucidated. Ndc1p is an integral membrane protein that localizes to SPBs, and it is required for insertion of the SPB into the nuclear envelope during SPB duplication.

Cdk1-Clb4 controls the interaction of astral microtubule plus ends with subdomains of the daughter cell cortex.

As in many polarized cells, spindle alignment in yeast is essential and cell cycle regulated. A key step that governs spindle alignment is the selective binding of the Kar9 protein to only one of the two spindle pole bodies (SPBs). It has been suggested that cyclin-dependent kinase Cdc28, in complex with cyclin Clb4, associates only with the SPB in the mother cell and so prevents Kar9 binding to this SPB.

CLIP-170 family members: a motor-driven ride to microtubule plus ends.

CLIP-170 family proteins regulate microtubule plus end dynamics. Two reports published in this issue of Developmental Cell show that Bik1 and tip1p, the CLIP-170-like proteins of budding and fission yeast, are carried to microtubule plus ends by kinesin motor proteins. These findings indicate a complex interplay between microtubule-associated proteins and suggest a novel mechanism by which kinesin proteins stabilize microtubules.

Role of mitochondrial membrane permeabilization in apoptosis and cancer.

The release of proteins from the intermembrane space of mitochondria is one of the pivotal events in the apoptotic process, which can lead to the activation of caspases and the ultimate demise of the cell. How these proteins exit the mitochondria is still a matter of intense debate. Here, we discuss the possible mechanisms behind the release of apoptogenic proteins, the ways in which cancer cells subvert these mechanisms, and the therapeutic regimens that aim to promote the timely loss of integrity of the outer mitochondrial membrane.

Novel regulation of mitotic exit by the Cdc42 effectors Gic1 and Gic2.

The guanine nucleotide exchange factor Cdc24, the GTPase Cdc42, and the Cdc42 effectors Cla4 and Ste20, two p21-activated kinases, form a signal transduction cascade that promotes mitotic exit in yeast. We performed a genetic screen to identify components of this pathway. Two related bud cortex-associated Cdc42 effectors, Gic1 and Gic2, were obtained as factors that promoted mitotic exit independently of Ste20.

Identification of recurrent regions of chromosome loss and gain in vestibular schwannomas using comparative genomic hybridisation.

Background: Schwannomas are benign tumours of the nervous system that are usually sporadic but also occur in the inherited disorder neurofibromatosis type 2 (NF2). The NF2 gene is a tumour suppressor on chromosome 22. Loss of expression of the NF2 protein product, merlin, is universal in both sporadic and NF2 related schwannomas.

Separase regulates INCENP-Aurora B anaphase spindle function through Cdc14.

The inner centromere-like protein (INCENP) forms a complex with the evolutionarily conserved family of Aurora Bkinases. The INCENP-Aurora complex helps coordinate chromosome segregation, spindle behavior, and cytokinesis during mitosis. INCENP-Aurora associates with kinetochores in metaphase and with spindle microtubules in anaphase, yet the trigger for this abrupt transfer is unknown.

The XMAP215 homologue Stu2 at yeast spindle pole bodies regulates microtubule dynamics and anchorage.

The yeast protein Stu2 belongs to the XMAP215 family of conserved microtubule-binding proteins which regulate microtubule plus end dynamics. XMAP215-related proteins also bind to centrosomes and spindle pole bodies (SPBs) through proteins like the mammalian transforming acidic coiled coil protein TACC or the yeast Spc72. We show that yeast Spc72 has two distinct domains involved in microtubule organization.

Yeast Cdk1 translocates to the plus end of cytoplasmic microtubules to regulate bud cortex interactions.

The budding yeast spindle aligns along the mother- bud axis through interactions between cytoplasmic microtubules (CMs) and the cell cortex. Kar9, in complex with the EB1-related protein Bim1, mediates contacts of CMs with the cortex of the daughter cell, the bud. Here we established a novel series of events that target Kar9 to the bud cortex.

A role for cell polarity proteins in mitotic exit.

The budding yeast mitotic exit network (MEN) is a signal transduction cascade that controls exit from mitosis by facilitating the release of the cell cycle phosphatase Cdc14 from the nucleolus. The G protein Tem1 regulates MEN activity. The Tem1 guanine nucleotide exchange factor (GEF) Lte1 associates with the cortex of the bud and activates the MEN upon the formation of an anaphase spindle.

5T4 interacts with TIP-2/GIPC, a PDZ protein, with implications for metastasis.

Overexpression of the 5T4 transmembrane glycoprotein can have marked effects on both the actin cytoskeleton and cell migration. Using a yeast two-hybrid approach, we describe a novel interaction between 5T4 and TIP-2/GIPC, a cytoplasmic interacting protein containing a PDZ domain. The cytoplasmic tail of 5T4 contains a class I PDZ-binding motif (Ser-Asp-Val) and we demonstrate that this region, in particular the terminal valine, is required for 5T4 interaction with TIP-2/GIPC.

Inhibition by uridine but not thymidine of p53-dependent intestinal apoptosis initiated by 5-fluorouracil: evidence for the involvement of RNA perturbation.

The epithelia from the crypts of the intestine are exquisitely sensitive to metabolic perturbation and undergo cell death with the classical morphology of apoptosis. Administration of 40 mg/kg 5-fluorouracil (5-FU) to BDF-1 p53+/+ mice resulted in an increase in p53 protein at cell positions in the crypts that were also those subjected to an apoptotic cell death. In p53-/- mice apoptosis was almost completely absent, even after 24 hr.