Filip Farnebo

Comparative evaluation of the antitumor activity of antiangiogenic proteins delivered by gene transfer

Although the systemic administration of a number of different gene products has been shown to result in the inhibition of angiogenesis and tumor growth in different animal tumor models, the relative potency of those gene products has not been studied rigorously. To address this issue, recombinant adenoviruses encoding angiostatin, endostatin, and the ligand-binding ectodomains of the vascular endothelial growth factor receptors Flk1, Flt1, and neuropilin were generated and used to systemically deliver the different gene products in several different preexisting murine tumor models. Single i.v. injections of viruses encoding soluble forms of Flk1 or Flt1 resulted in ≈80% inhibition of preexisting tumor growth in murine models involving both murine (Lewis lung carcinoma, T241 fibrosarcoma) and human (BxPC3 pancreatic carcinoma) tumors. In contrast, adenoviruses encoding angiostatin, endostatin, or neuropilin were significantly less effective. A strong correlation was observed between the effects of the different viruses on tumor growth and the activity of the viruses in the inhibition of corneal micropocket angiogenesis. These data underscore the need for comparative analyses of different therapeutic approaches that target tumor angiogenesis and provide a rationale for the selection of specific antiangiogenic gene products as lead candidates for use in gene therapy approaches aimed at the treatment of malignant and ocular disorders.

Thymic carcinoids in multiple endocrine neoplasia type 1

Thymic carcinoid is a rare malignancy with about 150 cases reported to date. It is associated with multiple endocrine neoplasia type 1 (MEN-1), but compared with other MEN-1-related neoplasia little is known about it. We have recently described and studied 20 MEN-1-related cases and found that up to 25% of all reported thymic carcinoids are MEN-1 related. It is an insidious tumour not associated with Cushings syndrome or carcinoid syndrome. Local invasion, recurrence and distant metastasis are common with no known effective treatment. Its male predominance, the absence of loss of heterozygosity (LOH) in the MEN1 region, clustering in some MEN-1 families and the findings of different MEN1 mutations in these clustered families suggest the involvement of additional aetiological factors. We propose that computed tomography (CT) or magnetic resonance imaging (MRI) of the chest should be included as part of the clinical workup for all MEN-1 patients. Prophylactic thymectomy should be considered during subtotal or total parathyroidectomy on MEN-1 patients to reduce the risk of this malignancy.

Notch Signaling Regulates Platelet-Derived Growth Factor Receptor-β Expression in Vascular Smooth Muscle Cells

Notch signaling is critically important for proper architecture of the vascular system, and mutations in NOTCH3 are associated with CADASIL, a stroke and dementia syndrome with vascular smooth muscle cell (VSMC) dysfunction. In this report, we link Notch signaling to platelet-derived growth factor (PDGF) signaling, a key determinant of VSMC biology, and show that PDGF receptor (PDGFR)-β is a novel immediate Notch target gene. PDGFR-β expression was upregulated by Notch ligand induction or by activated forms of the Notch receptor. Moreover, upregulation of PDGFR-β expression in response to Notch activation critically required the Notch signal integrator CSL. In primary VSMCs, PDGFR-β expression was robustly upregulated by Notch signaling, leading to an augmented intracellular response to PDGF stimulation. In newborn Notch3-deficient mice, PDGFR-β expression was strongly reduced in the VSMCs that later develop an aberrant morphology. In keeping with this, PDGFR-β upregulation in response to Notch activation was reduced also in Notch3-deficient embryonic stem cells. Finally, in VSMCs from a CADASIL patient carrying a NOTCH3 missense mutation, upregulation of PDGFR-β mRNA and protein in response to ligand-induced Notch activation was significantly reduced. In sum, these data reveal a hierarchy for 2 important signaling systems, Notch and PDGF, in the vasculature and provide insights into how dysregulated Notch signaling perturbs VSMC differentiation and function.

Characterization of the mouse Men1 gene and its expression during development

The gene responsible for multiple endocrine neoplasia type 1 (MEN1), a heritable predisposition to endocrine tumours in man, has recently been identified. Here we have characterized the murine homologue with regard to cDNA sequence, genomic structure, expression pattern and chromosomal localisation. The murine Men1 gene spans approximately 6.7 kb of genomic DNA and is comprised of 10 exons with similar genomic structure to the human locus. It was mapped to the pericentromeric region of mouse chromosome 19, which is conserved with the human 11q13 band where MEN1 is located. The predicted protein is 611 amino acids in length and overall is 97% homologous to the human orthologue. The 45 reported MEN1 mutations which alter or delete a single amino acid in human all occur at conserved residues, thereby supporting their functional significance. Two transcripts of approximately 3.2 and 2.8 kb were detected in both embryonal and adult murine tissues, resulting from alternative splicing of intron 1. By RNA in situ hybridization and Northern analysis the spatiotemporal expression pattern of Men1 was determined during mouse development. Men1 gene activity was detected already at gestational day 7. At embryonic day 14 expression was generally high throughout the embryo, while at day 17 the thymus, skeletal muscle, and CNS showed the strongest signal. In selected tissues from postnatal mouse Men1 was detected in all tissues analysed and was expressed at high levels in cerebral cortex, hippocampus, testis, and thymus. In brain the menin protein was detected mainly in nerve cell nuclei, whereas in testis it appeared perinuclear in spermatogonia. These results show that Men1 expression is not confined to organs affected in MEN1, suggesting that Men1 has a significant function in many different cell types including the CNS and testis.

Chromosomal Alterations in 15 Breast Cancer Cell Lines by Comparative Genomic Hybridization and Spectral Karyotyping

Breast cancer cell lines have been widely used as models in functional and therapeutical studies, but their chromosomal alterations are not well known. We characterized the chromosomal aberrations in 15 commonly used human breast carcinoma cell lines (BT‐474, BT‐549, CAMA‐1, DU4475, MCF7, MDA‐MB‐134, MDA‐MB‐157, MDA‐MB‐361, MDA‐MB‐436, MPE600, SK‐BR‐3, T‐47D, UACC‐812, UACC‐893, and ZR‐75‐1) by comparative genomic hybridization (CGH) and spectral karyotyping (SKY). By CGH the most frequent gains were detected at 1q, 8q, 20q, 7, 11q13, 17q, 9q, and 16p, whereas losses were most common at 8p, 11q14–qter, 18q, and Xq. SKY revealed a multitude of structural and numerical chromosomal aberrations. Simple translocations, typically consisting of entire translocated chromosome arms, were the most common structural aberrations. Complex marker chromosomes included material from up to seven different chromosomes. Evidence for a cytogenetic aberration not previously described in breast cancer, the isoderivative chromosome, was found in two cell lines. Translocations t(8;11), t(12;16), t(1;16), and t(15;17) were frequently found, although the resulting derivative chromosomes and their breakpoints were strikingly dissimilar. The chromosomes most frequently involved in translocations were 8, 1, 17, 16, and 20. An excellent correlation was found between the number of translocation events found by SKY in the individual cell lines, and the copy number gains and losses detected by CGH, indicating that the majority of translocations are unbalanced. Genes Chromosomes Cancer 28:308–317, 2000.

Heparan Sulfation–Dependent Fibroblast Growth Factor Signaling Maintains Embryonic Stem Cells Primed for Differentiation in a Heterogeneous State

Embryonic stem (ES) cells continuously decide whether to maintain pluripotency or differentiate. While exogenous leukemia inhibitory factor and BMP4 perpetuate a pluripotent state, less is known about the factors initiating differentiation. We show that heparan sulfate (HS) proteoglycans are critical coreceptors for signals inducing ES cell differentiation. Genetic targeting of NDST1 and NDST2, two enzymes required for N‐sulfation of proteoglycans, blocked differentiation. This phenotype was rescued by HS presented in trans or by soluble heparin. NaClO  3− , which reduces sulfation of proteoglycans, potently blocked differentiation of wild‐type cells. Mechanistically, N‐sulfation was identified to be critical for functional autocrine fibroblast growth factor 4 (FGF4) signaling. Microarray analysis identified the pluripotency maintaining transcription factors Nanog, KLF2/4/8, Tbx3, and Tcf3 to be negatively regulated, whereas markers of differentiation such as Gbx2, Dnmt3b, FGF5, and Brachyury were induced by sulfation‐dependent FGF receptor (FGFR) signaling. We show that several of these genes are heterogeneously expressed in ES cells, and that targeting of heparan sulfation or FGFR‐signaling facilitated a homogenous Nanog/KLF4/Tbx3 positive ES cell state. This finding suggests that the recently discovered heterogeneous state of ES cells is regulated by HS‐dependent FGFR signaling. Similarly, culturing blastocysts with NaClO  3− eliminated GATA6‐positive primitive endoderm progenitors generating a homogenous Nanog‐positive inner cell mass. Functionally, reduction of sulfation robustly improved de novo ES cell derivation efficiency. We conclude that N‐sulfated HS is required for FGF4 signaling to maintain ES cells primed for differentiation in a heterogeneous state. Inhibiting this pathway facilitates a more naïve ground state. STEM CELLS 2010;28:191–200

A Family with Isolated Hyperparathyroidism Segregating a Missense MEN1 Mutation and Showing Loss of the Wild-Type Alleles in the Parathyroid Tumors

We thank Mr. Ashley Brown and Mr. Hedley Berry for allowing us to study their patients. This study was supported by the Swedish Cancer Foundation and the Gustav Vs Jubilee Fund. B.T.T. is a postdoctoral fellow of the Torsten and Ragnar Soderberg Memory Foundations.

Patterns of Chromosomal Imbalances in Parathyroid Carcinomas

In this study we have characterized chromosomal imbalances in a panel of 29 parathyroid carcinomas using comparative genomic hybridization (CGH). The most frequently detected imbalances were losses of 1p and 13q that were seen in >40% of the cases. The commonly occurring regions of loss were assigned to 1p21-p22 (41%), 13q14-q31 (41%), 9p21-pter (28%), 6q22-q24 (24%), and 4q24 (21%), whereas gains preferentially involved 19p (45%), Xc-q13 (28%), 9q33-qter (24%), 1q31-q32 (21%) and 16p (21%). The distribution of CGH alterations supports the idea of a progression of genetic events in the development of parathyroid carcinoma, where gains of Xq and 1q would represent relatively early events that are followed by loss of 13q, 9p, and 1p, and by gain of 19p. A sex-dependent distribution was also evident for two of the common alterations with preferential gain of 1q in female cases and of Xq in male cases. When the CGH profiles for the 29 carcinomas were compared with our previously published results for sporadic parathyroid adenomas, highly significant differences were revealed. Loss of 1p, 4q, and 13q as well as gains of 1q, 9q, 16p, 19p and Xq were significantly more common in the carcinomas than in the adenomas. In contrast, loss of the 11q13 region, which is the most common CGH abnormality in sporadic adenomas, was not detected in any of the carcinomas. Taken together, the findings identify several candidate locations for tumor suppressor genes and oncogenes that are potentially involved in parathyroid carcinogenesis.

A comparative study of the expression patterns for vegf, vegf-b/vrf and vegf-c in the developing and adult mouse.

With the goal of better understanding the function and regulation of the different members of the VEGF family this study reports mapping of vegf, vegf-b and vegf-c mRNA expression in developing and adult mice. On embryonic day 14 (E14) there is a high expression of vegf and vegf-b, vegf-b being exceptionally high in heart and CNS. The vegf-c expression is lower with distinct signals in CNS and heart. Prior to birth (E17), vegf and vegf-b expression is moderately downregulated. Overlapping expression is present in intrascapular fat and heart. vegf dominates in thyroid and lung, while vegf-b appears to be the only VEGF member expressed at detectable levels in the CNS. In young adult mouse vegf and vegf-b show partly overlapping expression patterns particularly in kidney, heart and in the thymus, vegf displays higher levels in lung and liver, vegf-b appears to be dominating in brain, heart, testis and kidney. In brain the highest levels of vegf-b is present in the hippocampus. No vegf-c mRNA expression could be detected in the adult. Taken together, these results illustrate, in detail, the different regulations of the members of the VEGF gene family. There are at present at least three specific effectors of vascular proliferation with clear differences in their expression.

Sustained Inflammation Due to Nuclear Factor-Kappa B Activation in Irradiated Human Arteries

OBJECTIVES The aim of this study was to investigate gene expression networks related to cardiovascular disease in radiated human arteries. BACKGROUND Recent epidemiological studies have shown that radiotherapy is associated with cardiovascular disease years after treatment. However, the molecular mechanisms underlying late effects of radiation are poorly described. METHODS Arterial biopsies from radiated and nonradiated human conduit arteries, from the same patient, were simultaneously harvested during microvascular free tissue transfer for cancer-reconstruction in 13 patients, 4 to 500 weeks from radiation treatment. Radiated and nonradiated arteries were compared, with Affymetrix (Santa Clara, California) microarrays on a subset of the material to generate candidate genes. A Taqman (Applied Biosystems, Foster City, California) low-density array of 45 selected genes was designed for analysis of the whole material. RESULTS Thirteen genes were synchronously expressed in all patients (p = 0.0015), including CCL8, CCL3, CXCL2, DUSP5, FGFR2, HMOX1, HOXA9, IL-6, MMP-1, PTX3, RDH10, SOD2, and TNFAIP3. A majority of differentially regulated genes related to the nuclear factor-kappa B (NF-kappaB) signaling pathway and were dysregulated even years after radiation. The NF-kappaB activation was confirmed by immunohistochemistry and immunofluorescence. CONCLUSIONS In the present study, we found sustained inflammation due to NF-kappaB activation in human radiated arteries. The results are supported by previous in vitro findings suggesting that deoxyribonucleic acid injury, after radiation, activates NF-kappaB. We also suggest that HOXA9 might be involved in the regulation of NF-kappaB activation. The observed sustained inflammatory response can explain cardiovascular disease years after radiation.