SIX3 and SIX6 interact with GEMININ via C-terminal regions.

The histoarchitecture and function of eye and forebrain depend on a well-controlled balance between cell proliferation and differentiation. For example, the binding of the cell cycle regulator GEMININ to CDT1, which is a part of the pre-replication complex, promotes cell differentiation. Homeodomain transcription factors SIX3 and SIX6 also interact with GEMININ of which SIX3-GEMININ interaction promotes cell proliferation, whereas the nature of SIX6-GEMININ interaction has not been studied to date.

Two tales of Annexin A2 knock-down: One of compensatory effects by antisense RNA and another of a highly active hairpin ribozyme.

Besides altering its own expression during cell transformation, Annexin A2 is upregulated during the progression of many cancer types and also plays key roles during viral infection and multiplication. Consequently, there has been great interest in Annexin A2 as a potential drug target. The successful design of efficient in vivo delivery systems constitutes an obstacle in full exploitation of antisense and RNA-cleaving technologies for the knock-down of specific targets.

CorA is a copper repressible surface-associated copper(I)-binding protein produced in Methylomicrobium album BG8.

CorA is a copper repressible protein previously identified in the methanotrophic bacterium Methylomicrobium album BG8. In this work, we demonstrate that CorA is located on the cell surface and binds one copper ion per protein molecule, which, based on X-ray Absorption Near Edge Structure analysis, is in the reduced state (Cu(I)). The structure of endogenously expressed CorA was solved using X-ray crystallography.

CXXC5 (retinoid-inducible nuclear factor, RINF) is a potential therapeutic target in high-risk human acute myeloid leukemia.

The retinoid-responsive gene CXXC5 localizes to the 5q31.2 chromosomal region and encodes a retinoid-inducible nuclear factor (RINF) that seems important during normal myelopoiesis. We investigated CXXC5/RINF expression in primary human acute myeloid leukemia (AML) cells derived from 594 patients, and a wide variation in CXXC5/RINF mRNA levels was observed both in the immature leukemic myeloblasts and in immature acute lymphoblastic leukemia cells.

Low BRAF and NRAS expression levels are associated with clinical benefit from DTIC therapy and prognosis in metastatic melanoma.

Metastatic melanoma is characterized by a poor response to chemotherapy. Furthermore, there is a lack of established predictive and prognostic markers. In this single institution study, we correlated mutation status and expression levels of BRAF and NRAS to dacarbazine (DTIC) treatment response as well as progression-free and overall survival in a cohort of 85 patients diagnosed with advanced melanoma.

Functional characterisation of p53 mutants identified in breast cancers with suboptimal responses to anthracyclines or mitomycin.

Background: Approximately 4300 different TP53 mutations have been reported in human cancers. TP53 mutations, in particular those affecting the L2/L3 domains, are associated with resistance to anthracycline or mitomycin treatment in breast cancer patients. While many mutations have been characterised functionally, novel TP53 mutations are continuously reported.

The Methylococcus capsulatus (Bath) secreted protein, MopE*, binds both reduced and oxidized copper.

Under copper limiting growth conditions the methanotrophic bacterium Methylococcus capsulatus (Bath) secrets essentially only one protein, MopE*, to the medium. MopE* is a copper-binding protein whose structure has been determined by X-ray crystallography. The structure of MopE* revealed a unique high affinity copper binding site consisting of two histidine imidazoles and one kynurenine, the latter an oxidation product of Trp130.

Human protein N-terminal acetyltransferase hNaa50p (hNAT5/hSAN) follows ordered sequential catalytic mechanism: combined kinetic and NMR study.

N(α)-acetylation is a common protein modification catalyzed by different N-terminal acetyltransferases (NATs). Their essential role in the biogenesis and degradation of proteins is becoming increasingly evident. The NAT hNaa50p preferentially modifies peptides starting with methionine followed by a hydrophobic amino acid.

Receptor for activated protein C kinase 1 (RACK1) is overexpressed in papillary thyroid carcinoma.

Background: The receptor for activated C kinase 1 (RACK1) has been shown to be overexpressed in several types of cancers such as breast, colon, melanomas, and lung. RACK1 is linked to Ras-Raf-mediated signal transduction and transformed foci formation of 3T3 cells in vitro, and since this pathway is central in papillary thyroid carcinoma (PTC) oncogenesis, we hypothesized that RACK1 could play a role in the development or maintenance of PTC. No report on RACK1 expression in thyroid tissue is available; the present study was therefore aimed at identifying possible correlation of RACK1 expression at the mRNA or protein level in normal thyroid tissue compared to PTC.

The human N-alpha-acetyltransferase 40 (hNaa40p/hNatD) is conserved from yeast and N-terminally acetylates histones H2A and H4.

Protein N(α)-terminal acetylation (Nt-acetylation) is considered one of the most common protein modification in eukaryotes, and 80-90% of all soluble human proteins are modified in this way, with functional implications ranging from altered protein function and stability to translocation potency amongst others. Nt-acetylation is catalyzed by N-terminal acetyltransferases (NATs), and in yeast five NAT types are identified and denoted NatA-NatE. Higher eukaryotes additionally express NatF.

Using VAAST to identify an X-linked disorder resulting in lethality in male infants due to N-terminal acetyltransferase deficiency.

We have identified two families with a previously undescribed lethal X-linked disorder of infancy; the disorder comprises a distinct combination of an aged appearance, craniofacial anomalies, hypotonia, global developmental delays, cryptorchidism, and cardiac arrhythmias. Using X chromosome exon sequencing and a recently developed probabilistic algorithm aimed at discovering disease-causing variants, we identified in one family a c.109T>C (p.

Predictive and prognostic impact of TP53 mutations and MDM2 promoter genotype in primary breast cancer patients treated with epirubicin or paclitaxel.

Background: TP53 mutations have been associated with resistance to anthracyclines but not to taxanes in breast cancer patients. The MDM2 promoter single nucleotide polymorphism (SNP) T309G increases MDM2 activity and may reduce wild-type p53 protein activity. Here, we explored the predictive and prognostic value of TP53 and CHEK2 mutation status together with MDM2 SNP309 genotype in stage III breast cancer patients receiving paclitaxel or epirubicin monotherapy.

Proteome-derived peptide libraries allow detailed analysis of the substrate specificities of N(alpha)-acetyltransferases and point to hNaa10p as the post-translational actin N(alpha)-acetyltransferase.

The impact of N(α)-terminal acetylation on protein stability and protein function in general recently acquired renewed and increasing attention. Although the substrate specificity profile of the conserved enzymes responsible for N(α)-terminal acetylation in yeast has been well documented, the lack of higher eukaryotic models has hampered the specificity profile determination of N(α)-acetyltransferases (NATs) of higher eukaryotes. The fact that several types of protein N termini are acetylated by so far unknown NATs stresses the importance of developing tools for analyzing NAT specificities.

Depletion of the human Nα-terminal acetyltransferase A induces p53-dependent apoptosis and p53-independent growth inhibition.

The human protein N(α)-terminal acetyltransferase A complex (hNatA), composed of the catalytic hNaa10p (hArd1) and auxiliary hNaa15p (hNat1/NATH/Tubedown) subunits, was reported to be important for cell survival and growth of various types of cancer. However, little is known about the mechanisms mediating growth inhibition and apoptosis following loss of hNatA function. Here, we have screened 11 different thyroid cell lines for hNAA10 RNAi phenotypes and observed mostly growth inhibition, which was independent of TP53 functional status and developed by several different mechanisms involving (i) downregulation of cyclin D1, (ii) increase in p27/Kip1 and (iii) inactivation of Rb/E2F pathway.

The MDM2 promoter SNP285C/309G haplotype diminishes Sp1 transcription factor binding and reduces risk for breast and ovarian cancer in Caucasians.

MDM2 plays a key role in modulating p53 function. The MDM2 SNP309T > G promoter polymorphism enhances Sp1 binding and has been linked to cancer risk and young age at diagnosis although with conflicting evidence. We report a second MDM2 promoter polymorphism, SNP285G > C, residing on the SNP309G allele.

Alterations of the retinoblastoma gene in metastatic breast cancer.

Germline mutations affecting the retinoblastoma gene (RB1) predispose to inherited retinoblastomas but also other malignancies, including breast cancer. While somatic RB1 mutations have been detected in different malignancies, information about the potential role of RB1 mutations in breast cancer is limited. Recently, we discovered RB1 mutations to be associated with resistance to anthracyclines/mitomycin in primary breast cancer.

Identification and characterization of retinoblastoma gene mutations disturbing apoptosis in human breast cancers.

Background: The tumor suppressor pRb plays a key role regulating cell cycle arrest, and disturbances in the RB1 gene have been reported in different cancer forms. However, the literature reports contradictory findings with respect to a pro--versus anti--apoptotic role of pRb, and the consequence of alterations in RB1 to chemotherapy sensitivity remains unclear. This study is part of a project investigating alterations in pivotal genes as predictive factors to chemotherapy sensitivity in breast cancer.

MGMT expression levels predict disease stabilisation, progression-free and overall survival in patients with advanced melanomas treated with DTIC.

Metastatic melanoma responds poorly to systemic treatment. We report the results of a prospective single institution study evaluating O(6)-methylguanine-DNA methyltransferase (MGMT) status as a potential predictive and/or prognostic marker among patients treated with dacarbazine (DTIC) 800-1000 mg/m(2) monotherapy administered as a 3-weekly schedule for advanced malignant melanomas. The study was approved by the Regional Ethical Committee.

Gene expression profiling-based identification of molecular subtypes in stage IV melanomas with different clinical outcome.

Purpose: The incidence of malignant melanoma is increasing worldwide in fair-skinned populations. Melanomas respond poorly to systemic therapy, and metastatic melanomas inevitably become fatal. Although spontaneous regression, likely due to immune defense activation, rarely occurs, we lack a biological rationale and predictive markers in selecting patients for immune therapy.

Chk2 splice variants express a dominant-negative effect on the wild-type Chk2 kinase activity.

While the majority of RNA transcripts from protein-encoding genes in the human genome are subject to physiological splicing, pathological splicing is increasingly reported in cancer tissue. Previously, we identified >90 different splice variants of Chk2, a gene encoding a serine/threonine kinase propagating the DNA damage signal by phosphorylating and activating several downstream substrates like p53, Cdc25A, and Cdc25C involved in cell cycle arrest and apoptosis. While alternative splice forms of other genes have been reported to exert a dominant-negative effect on the wild-type molecules, the function of Chk2 splice protein variants is still unclear.

Inverse correlation between PDGFC expression and lymphocyte infiltration in human papillary thyroid carcinomas.

Background: Members of the PDGF family have been suggested as potential biomarkers for papillary thyroid carcinomas (PTC). However, it is known that both expression and stimulatory effect of PDGF ligands can be affected by inflammatory cytokines. We have performed a microarray study in a collection of PTCs, of which about half the biopsies contained tumour-infiltrating lymphocytes or thyroiditis.

Human Naa50p (Nat5/San) displays both protein N alpha- and N epsilon-acetyltransferase activity.

Protein acetylation is a widespread modification that is mediated by site-selective acetyltransferases. KATs (lysine N(epsilon)-acetyltransferases), modify the side chain of specific lysines on histones and other proteins, a central process in regulating gene expression. N(alpha)-terminal acetylation occurs on the ribosome where the alpha amino group of nascent polypeptides is acetylated by NATs (N-terminal acetyltransferase).

Application of reverse-phase HPLC to quantify oligopeptide acetylation eliminates interference from unspecific acetyl CoA hydrolysis.

Protein acetylation is a common modification that plays a central role in several cellular processes. The most widely used methods to study these modifications are either based on the detection of radioactively acetylated oligopetide products or an enzyme-coupled reaction measuring conversion of the acetyl donor acetyl CoA to the product CoASH. Due to several disadvantages of these methods, we designed a new method to study oligopeptide acetylation.

A novel human NatA Nalpha-terminal acetyltransferase complex: hNaa16p-hNaa10p (hNat2-hArd1).

Background: Protein acetylation is among the most common protein modifications. The two major types are post-translational Nepsilon-lysine acetylation catalyzed by KATs (Lysine acetyltransferases, previously named HATs (histone acetyltransferases) and co-translational Nalpha-terminal acetylation catalyzed by NATs (N-terminal acetyltransferases). The major NAT complex in yeast, NatA, is composed of the catalytic subunit Naa10p (N alpha acetyltransferase 10 protein) (Ard1p) and the auxiliary subunit Naa15p (Nat1p).