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  • 1.
    Asklund, Thomas
    et al.
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Oncology.
    Kvarnbrink, Samuel
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Oncology.
    Holmlund, Camilla
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Oncology.
    Wibom, Carl
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Oncology.
    Bergenheim, Tommy
    Umeå University, Faculty of Medicine, Department of Pharmacology and Clinical Neuroscience, Clinical Neuroscience.
    Henriksson, Roger
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Oncology.
    Hedman, Håkan
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Oncology.
    Synergistic Killing of Glioblastoma Stem-like Cells by Bortezomib and HADC Inhibitors.2012In: Anticancer Research, ISSN 0250-7005, E-ISSN 1791-7530, Vol. 32, no 7, p. 2407-2413Article in journal (Refereed)
    Abstract [en]

    Background: The malignant brain tumour glioblastoma is a devastating disease that remains a therapeutic challenge. Materials and Methods: Effects of combinations of the US Food and Drug Administation (FDA) approved proteasome inhibitor bortezomib and the histone deacetylase (HDAC) inhibitors vorinostat, valproic acid and sodium phenylbutyrate were studied on primary glioblastoma stem cell lines and conventional glioblastoma cell lines. Cell survival, proliferation and death were analyzed by fluorometric microculture cytotoxicity assay (FMCA), propidium iodide labeling and flow cytometry, and cell cloning through limiting dilution and live-cell bright-field microscopy. Results: Bortezomib and the HDAC inhibitors showed synergistic cell killing at clinically relevant drug concentrations, while the conventional cell lines cultured in serum-containing medium were relatively resistant to the same treatments. Conclusion: These findings of synergistic glioblastoma stem cell killing by bortezomib and three different FDA-approved HDAC inhibitors confirm and expand previous observations on co-operative effects between these classes of drugs.

  • 2.
    Asklund, Thomas
    et al.
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Oncology.
    Kvarnbrink, Samuel
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Oncology.
    Holmlund, Camilla
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Oncology.
    Wibom, Carl
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Oncology.
    Bergenheim, Tommy
    Umeå University, Faculty of Medicine, Department of Pharmacology and Clinical Neuroscience, Clinical Neuroscience.
    Henriksson, Roger
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Oncology.
    Hedman, Håkan
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Oncology.
    Synergistic killing of Glioblastoma Stem-like cells by Bortezomib and HDAC Inhibitors2012In: Anticancer Research, ISSN 0250-7005, E-ISSN 1791-7530, Vol. 32, no 7 ; Special Issue, p. 2407-2413Article in journal (Refereed)
    Abstract [en]

    Background: The malignant brain tumour glioblastoma is a devastating disease that remains a therapeutic challenge. Materials and Methods: Effects of combinations of the US Food and Drug Administation (FDA) approved proteasome inhibitor bortezomib and the histone deacetylase (HDAC) inhibitors vorinostat, valproic acid and sodium phenylbutyrate were studied on primary glioblastoma stem cell lines and conventional glioblastoma cell lines. Cell survival, proliferation and death were analyzed by fluorometric microculture cytotoxicity assay (FMCA), propidium iodide labeling and flow cytometry, and cell cloning through limiting dilution and live-cell bright-field microscopy. Results: Bortezomib and the HDAC inhibitors showed synergistic cell killing at clinically relevant drug concentrations, while the conventional cell lines cultured in serum-containing medium were relatively resistant to the same treatments. Conclusion: These findings of synergistic glioblastoma stem cell killing by bortezomib and three different FDA-approved HDAC inhibitors confirm and expand previous observations on co-operative effects between these classes of drugs.

  • 3.
    Faraz, Mahmood
    et al.
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Oncology.
    Herdenberg, Carl
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Oncology.
    Holmlund, Camilla
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Oncology.
    Henriksson, Roger
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Oncology.
    Hedman, Håkan
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Oncology.
    A protein interaction network centered on leucine-rich repeats and immunoglobulin-like domains 1 (LRIG1) regulates growth factor receptors2018In: Journal of Biological Chemistry, ISSN 0021-9258, E-ISSN 1083-351X, Vol. 293, no 9, p. 3421-3435Article in journal (Refereed)
    Abstract [en]

    Leucine-rich repeats and immunoglobulin-like domains 1 (LRIG1) is a tumor suppressor and a negative regulator of several receptor tyrosine kinases. The molecular mechanisms by which LRIG1 mediates its tumor suppressor effects and regulates receptor tyrosine kinases remain incompletely understood. Here, we performed a yeast two-hybrid screen to identify novel LRIG1-interacting proteins and mined data from the BioPlex (biophysical interactions of ORFeome-based complexes) protein interaction data repository. The putative LRIG1 interactors identified in the screen were functionally evaluated using a triple co-transfection system in which HEK293 cells were co-transfected with platelet-derived growth factor receptor α, LRIG1, and shRNAs against the identified LRIG1 interactors. The effects of the shRNAs on the ability of LRIG1 to down-regulate platelet-derived growth factor receptor α expression were evaluated. On the basis of these results, we present an LRIG1 protein interaction network with many newly identified components. The network contains the apparently functionally important LRIG1-interacting proteins RAB4A, PON2, GAL3ST1, ZBTB16, LRIG2, CNPY3, HLA-DRA, GML, CNPY4, LRRC40, and LRIG3, together with GLRX3, PTPRK, and other proteins. In silico analyses of The Cancer Genome Atlas data sets revealed consistent correlations between the expression of the transcripts encoding LRIG1 and its interactors ZBTB16 and PTPRK and inverse correlations between the transcripts encoding LRIG1 and GLRX3. We further studied the LRIG1 function–promoting paraoxonase PON2 and found that it co-localized with LRIG1 in LRIG1-transfected cells. The proposed LRIG1 protein interaction network will provide leads for future studies aiming to understand the molecular functions of LRIG1 and the regulation of growth factor signaling.

  • 4.
    Guo, Dongsheng
    et al.
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Oncology.
    Holmlund, Camilla
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Oncology.
    Henriksson, Roger
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Oncology.
    Hedman, Håkan
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Oncology.
    The LRIG gene family has three vertebrate paralogs widely expressed in human and mouse tissues and a homolog in ascidiacea2004In: Genomics, ISSN 0888-7543, E-ISSN 1089-8646, Vol. 84, no 1, p. 157-165Article in journal (Refereed)
    Abstract [en]

    Human LRIG1 (formerly LIG1), human LRIG2, and mouse Lrig1 (also known as Lig-1) encode integral membrane proteins. The human genes are located at chromosomes 3p14 and 1p13, which are regions frequently deleted in human cancers. We have searched for additional members of the LRIG family and by molecular cloning identified human LRIG3 and its mouse ortholog Lrig3. Human LRIG3 is located at chromosome 12q13. In silico analysis of public databases revealed a mouse Lrig2 mRNA, three LRIG homologs in the puffer fish Fugu rubripes, and one LRIG homolog in the ascidian tunicate Ciona intestinalis. The human and mouse LRIG polypeptides have the same predicted domain organization: a signal peptide, 15 tandem leucine-rich repeats with cysteine-rich N- and C-flanking domains, three immunoglobulin-like domains, a transmembrane domain, and a cytoplasmic tail. The extracellular part—especially the IgC2.2 domain, the transmembrane domain, and the membrane-proximal part of the cytoplasmic tail—are the most conserved regions. Northern blot analysis and real-time RT-PCR revealed that the three LRIG paralogs are widely expressed in human and mouse tissues. In conclusion, the LRIG gene family was found to have three widely expressed mammalian paralogs, corresponding orthologs in fish, and a homolog in Ascidiacea.

  • 5.
    Holmlund, Camilla
    Umeå University, Faculty of Medicine, Department of Radiation Sciences.
    Identification and investigations of leucine-rich repeats and immunoglobulin-like domains protein 2 (LRIG2)2010Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Receptor tyrosine kinases (RTKs) constitute a family of proteins controlling cell growth and proliferation and whose activities are tightly controlled in normal cells. LRIG1 is a negative regulator of RTK signaling and is a proposed tumor suppressor. The aim of this thesis was to identify and study possible paralogs of LRIG1. By using the basic local alignment search tool and cDNA cloning, a human mRNA sequence with similarity to LRIG1 was identified and named LRIG2. By fluorescence in situ hybridization analysis, LRIG2 was found to reside on chromosome 1p13. The LRIG2 amino acid sequence was 47% identical to LRIG1, and the predicted protein domain organization was the same as that of LRIG1. Antibodies against LRIG2 were developed and the apparent molecular weight of the protein was determined to be 132 kDa by SDS-polyacrylamide gel electrophoresis and Western blot analysis. The sub-cellular localization was studied by cell surface biotinylation experiments and confocal fluorescence laser microscopy, which revealed that LRIG2 resided at the cell surface and in the cytoplasm.

    The expression patterns of LRIG2 mRNA, during development and in adult tissues, were evaluated using whole-mount in situ hybridization and quantitative real-time RT-PCR, respectively. In E10.5, E11.5 and E12.5 mouse embryos, the Lrig2 expression domains were both overlapping and unique as compared to the expression domains of Lrig1 and the third family member, Lrig3. In adult human tissues, the most prominent LRIG2 mRNA expression was found in skin, uterus and ovary. To study the developmental and physiological role of LRIG2, Lrig2 knock-out mice were generated. The knock-out mice were born at Mendelian frequencies without any apparent morphological abnormalities. However, Lrig2 knock-out mice showed reduced body weight between 5 days and 12-15 weeks of age, increased mortality, and impaired reproductive capacity.

    To study the role of LRIG2 as a prognostic factor in oligodendroglioma, LRIG2 expression was analyzed in 65 human oligodendrogliomas by immunohistochemistry. Cytoplasmic LRIG2 expression was an independent prognostic factor associated with poor oligodendroglioma patient survival. The possible functional role of LRIG2 in oligodendroglioma biology was further investigated using the RCAS/tv-a mouse model. Tumors resembling human oligodendroglioma were induced by intracranial injection of PDGFB carrying RCAS retroviruses into newborn Ntv-a mice. Lrig2 wild-type animals developed tumors at a higher frequency and of higher malignancy than the Lrig2 knock-out mice. This result supports the notion that LRIG2 promotes PDGF-induced oligodendroglioma genesis. A possible molecular mechanism was revealed as LRIG2 overexpression increased PDGFRa levels in transfected cells. In summary, we identified a new gene named LRIG2, showed that it is expressed in a variety of tissues during development and in adulthood, knocked it out and found that it was required for proper animal growth, health, and reproduction. We also found that Lrig2 expression promoted PDGF-induced oligodendroglioma genesis and was associated with poor oligodendroglioma patient survival, possibly via a PDGFRa stabilizing function.

  • 6.
    Holmlund, Camilla
    et al.
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Oncology.
    Casar Borota, Olviera
    Umeå University, Faculty of Medicine, Department of Medical Biosciences.
    Miller, J
    Wang, B
    Zahed, F
    Sweeney, C
    Henriksson, Roger
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Oncology.
    Hedman, Håkan
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Oncology.
    LRIG2 promotes PDGF induced experimental gliomaManuscript (preprint) (Other academic)
  • 7.
    Holmlund, Camilla
    et al.
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Oncology.
    Haapasalo, Hannu
    Yi, Wei
    Raheem, Olayinka
    Brännström, Thomas
    Umeå University, Faculty of Medicine, Department of Medical Biosciences, Pathology.
    Bragge, Helena
    Henriksson, Roger
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Oncology.
    Hedman, Håkan
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Oncology.
    Cytoplasmic LRIG2 expression is associated with poor oligodendroglioma patient survival.2009In: Neuropathology (Kyoto. 1993), ISSN 0919-6544, E-ISSN 1440-1789, Vol. 29, no 3, p. 242-247Article in journal (Refereed)
    Abstract [en]

    The three leucine-rich repeats and immunoglobulin-like domains (LRIG) genes encode integral membrane proteins. Of these, LRIG1 negatively regulates growth factor signaling and is implicated as a tumor suppressor in certain malignancies. In astrocytic tumors, the subcellular distribution of LRIG proteins is associated with specific clinicopathological features and patient survival. The role of LRIG proteins in oligodendroglioma has not previously been studied. Here we used immunohistochemistry to analyze the expression of the LRIG proteins in 63 oligodendroglial tumors, and evaluated possible associations between LRIG protein expression and clinicopathological parameters. Notably, cytoplasmic LRIG2 expression was found to be an independent prognostic factor associated with poor oligodendroglioma patient survival. This is the first report of an LRIG protein showing a negative effect on survival, suggesting that LRIG2 might have a function different from that of LRIG1, and possibly contributing to the etiology of oligodendroglioma.

  • 8.
    Holmlund, Camilla
    et al.
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Oncology.
    Nilsson, Jonas
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Oncology.
    Guo, Dongsheng
    Umeå University, Faculty of Medicine, Umeå Centre for Molecular Medicine (UCMM). Umeå University, Faculty of Medicine, Department of Radiation Sciences, Oncology.
    Starefeldt, Anna
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Oncology.
    Golovleva, Irina
    Umeå University, Faculty of Medicine, Department of Medical Biosciences, Medical and Clinical Genetics.
    Henriksson, Roger
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Oncology.
    Hedman, Håkan
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Oncology.
    Characterization and tissue-specific expression of human LRIG22004In: Gene, ISSN 0378-1119, E-ISSN 1879-0038, Vol. 332, p. 35-43Article in journal (Refereed)
    Abstract [en]

    We have recently identified and cloned the human LRIG1 gene (formerly LIG1). LRIG1 is a predicted integral membrane protein with a domain organization reminiscent of the Drosophila epidermal growth factor (EGF)-receptor antagonist Kekkon-1. We have searched for additional members of the human LRIG family and identified LRIG2 (KIAA0806). The LRIG2 gene was localized to chromosome 1p13 and had an open reading frame of 1065 amino acids. The LRIG2 protein was predicted to have the same domain organization as LRIG1 with a signal peptide, an extracellular part containing15 leucine-rich repeats and three immunoglobulin-like domains, a transmembrane domain, and a cytoplasmic tail. The LRIG2 amino acid sequence was 47% identical to human LRIG1 and mouse Lrig1 (also known as Lig-1). Northern blotting and RT-PCR revealed LRIG2 transcripts in all tissues analyzed. Quantitative real-time RT-PCR showed the most prominent RNA expression in skin, uterus, ovary, kidney, brain, small intestine, adrenal gland, and stomach. Immunoblotting of COS-7 cell lysates demonstrated that heterologously expressed human LRIG2 had an apparent molecular weight of 132 kDa under reducing gel-running conditions. N-glycosidase F treatment resulted in a reduction of the apparent molecular weight to 107 kDa, showing that LRIG2 was a glycoprotein carrying N-linked oligosaccharides. Cell surface biotinylation experiments and confocal fluorescence laser microscopy demonstrated expression of LRIG2 both at the cell surface and in the cytoplasm. LRIG2 was detected in tissue lysates from stomach, prostate, lung, and fetal brain by immunoblotting. In conclusion, LRIG2 was found to be a glycoprotein which was encoded by a gene on human chromosome 1p13 and its mRNA was present in all tissues analyzed.

  • 9. Janson, V
    et al.
    Holmlund, Camilla
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Oncology.
    Vlecken, DH
    Casar Borota, Olivera
    Umeå University, Faculty of Medicine, Department of Medical Biosciences.
    Bergh, Anders
    Umeå University, Faculty of Medicine, Department of Medical Biosciences, Pathology.
    Henriksson, Roger
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Oncology.
    Bagowski, CP
    Hedman, Håkan
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Oncology.
    Lrig2 knock-out mice have increased mortality, impaired fertility and transiently reduced body weightManuscript (preprint) (Other academic)
  • 10.
    Karlsson, Terese
    et al.
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Oncology.
    Kvarnbrink, Samuel
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Oncology.
    Holmlund, Camilla
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Oncology.
    Botling, Johan
    Micke, Patrick
    Henriksson, Roger
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Oncology.
    Johansson, Mikael
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Oncology.
    Hedman, Håkan
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Oncology.
    LMO7 and LIMCH1 interact with LRIG proteins in lung cancer, with prognostic implications for early-stage disease2018In: Lung Cancer, ISSN 0169-5002, E-ISSN 1872-8332, Vol. 125, p. 174-184Article in journal (Refereed)
    Abstract [en]

    Objectives: The human leucine-rich repeats and immunoglobulin-like domains (LRIG) protein family comprises the integral membrane proteins LRIG1, LRIG2 and LRIG3. LRIG1 is frequently down-regulated in human cancer, and high levels of LRIG1 in tumor tissue are associated with favorable clinical outcomes in several tumor types including non-small cell lung cancer (NSCLC). Mechanistically, LRIG1 negatively regulates receptor tyrosine kinases and functions as a tumor suppressor. However, the details of the molecular mechanisms involved are poorly understood, and even less is known about the functions of LRIG2 and LRIG3. The aim of this study was to further elucidate the functions and molecular interactions of the LRIG proteins.

    Materials and methods: A yeast two-hybrid screen was performed using a cytosolic LRIG3 peptide as bait. In transfected human cells, co-immunoprecipitation and co-localization experiments were performed. Proximity ligation assay was performed to investigate interactions between endogenously expressed proteins. Expression levels of LMO7 and LIMCH1 in normal and malignant lung tissue were investigated using qRT-PCR and through in silico analyses of public data sets. Finally, a clinical cohort comprising 355 surgically treated NSCLC cases was immunostained for LMO7.

    Results: In the yeast two-hybrid screen, the two paralogous proteins LMO7 and LIMCH1 were identified as interaction partners to LRIG3. LMO7 and LIMCH1 co-localized and co-immunoprecipitated with both LRIG1 and LRIG3. Endogenously expressed LMO7 was in close proximity of both LRIG1 and LRIG3. LMO7 and LIMCH1 were highly expressed in normal lung tissue and down-regulated in malignant lung tissue. LMO7 immunoreactivity was shown to be a negative prognostic factor in LRIG1 positive tumors, predicting poor patient survival.

    Conclusion: These findings suggest that LMO7 and LIMCH1 physically interact with LRIG proteins and that expression of LMO7 is of clinical importance in NSCLC.

  • 11.
    Karlsson, Terese
    et al.
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Oncology.
    Kvarnbrink, Samuel
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Oncology.
    Holmlund, Camilla
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Oncology.
    Botling, Johan
    Micke, Patrick
    Johansson, Mikael
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Oncology.
    Henriksson, Roger
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Oncology.
    Hedman, Håkan
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Oncology.
    Interactions between LRIG proteins and LMO7 and the expression of LMO7 in human lung cancer.2013In: Cancer Research, ISSN 0008-5472, E-ISSN 1538-7445, Vol. 73, no 8: suppl 1, p. 5315-Article in journal (Refereed)
  • 12.
    Kvarnbrink, Samuel
    et al.
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Oncology.
    Karlsson, Terese
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Oncology.
    Forssell, Joakim
    Umeå University, Faculty of Medicine, Department of Clinical Microbiology, Infectious Diseases.
    Edlund, Karin
    Umeå University, Faculty of Medicine, Department of Clinical Microbiology, Virology.
    Holmlund, Camilla
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Oncology.
    Faraz, Mahmood
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Oncology.
    Botling, J
    Feng, Mao
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Oncology.
    Lindquist, David
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Oncology.
    Micke, P
    Henriksson, Roger
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Oncology.
    Johansson, Mikael
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Oncology.
    Hedman, Håkan
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Oncology.
    LRIG1 is a prognostic biomarker and tumor suppressor in non-small cell lung cancerManuscript (preprint) (Other academic)
  • 13.
    Mao, Feng
    et al.
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Oncology.
    Holmlund, Camilla
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Oncology.
    Faraz, Mahmood
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Oncology.
    Wang, Wanzhong
    Bergenheim, Tommy
    Umeå University, Faculty of Medicine, Department of Pharmacology and Clinical Neuroscience, Clinical Neuroscience.
    Kvarnbrink, Samuel
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Oncology.
    Johansson, Mikael
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Oncology.
    Henriksson, Roger
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Oncology. Regionalt Cancercentrum Stockholm Gotland, Karolinska, Stockholm, Sweden.
    Hedman, Håkan
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Oncology.
    Lrig1 is a haploinsufficient tumor suppressor gene in malignant glioma2018In: Oncogenesis, E-ISSN 2157-9024, Vol. 7, article id 13Article in journal (Refereed)
    Abstract [en]

    Recently, a genome-wide association study showed that a single nucleotide polymorphism (SNP) —rs11706832—in intron 2 of the human LRIG1 (Leucine-rich repeats and immunoglobulin-like domains 1) gene is associated with susceptibility to glioma. However, the mechanism by which rs11706832 affects glioma risk remains unknown; additionally, it is unknown whether the expression levels of LRIG1 are a relevant determinant of gliomagenesis. Here, we investigated the role of Lrig1 in platelet-derived growth factor (PDGF)-induced experimental glioma in mice by introducing mono-allelic and bi-allelic deletions of Lrig1 followed by inducing gliomagenesis via intracranial retroviral transduction of PDGFB in neural progenitor cells. Lrig1 was expressed in PDGFB-induced gliomas in wild-type mice as assessed using in situ hybridization. Intriguingly, Lrig1-heterozygous mice developed higher grade gliomas than did wild-type mice (grade IV vs. grade II/III, p = 0.002). Reciprocally, the ectopic expression of LRIG1 in the TB107 high-grade human glioma (glioblastoma, grade IV) cell line decreased the invasion of orthotopic tumors in immunocompromised mice in vivo and reduced cell migration in vitro. Concomitantly, the activity of the receptor tyrosine kinase MET was downregulated, which partially explained the reduction in cell migration. In summary, Lrig1 is a haploinsufficient suppressor of PDGFB-driven glioma, possibly in part via negative regulation of MET-driven cell migration and invasion. Thus, for the first time, changes in physiological Lrig1 expression have been linked to gliomagenesis, whereby the SNP rs11706832 may affect glioma risk by regulating LRIG1 expression.

  • 14.
    Rondahl, Veronica
    et al.
    Umeå University, Faculty of Medicine, Department of Medical Biosciences, Clinical chemistry.
    Holmlund, Camilla
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Oncology.
    Karlsson, Terese
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Oncology.
    Wang, Baofeng
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Oncology.
    Faraz, Mahmood
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Oncology.
    Henriksson, Roger
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Oncology. Regionalt Cancercentrum Stockholm, Karolinska Universitetssjukhuset Solna, Stockholm, Sweden.
    Hedman, Håkan
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Oncology.
    Lrig2-deficient mice are protected against PDGFB-induced glioma2013In: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 8, no 9, p. e73635-Article in journal (Other academic)
    Abstract [en]

    Background: The leucine-rich repeats and immunoglobulin-like domains (LRIG) proteins constitute an integral membrane protein family that has three members: LRIG1, LRIG2, and LRIG3. LRIG1 negatively regulates growth factor signaling, but little is known regarding the functions of LRIG2 and LRIG3. In oligodendroglial brain tumors, high expression of LRIG2 correlates with poor patient survival. Lrig1 and Lrig3 knockout mice are viable, but there have been no reports on Lrig2-deficient mice to date. Methodology/Principal Findings: Lrig2-deficient mice were generated by the ablation of Lrig2 exon 12 (Lrig2E12). The Lrig2E12-/- mice showed a transiently reduced growth rate and an increased spontaneous mortality rate; 20-25% of these mice died before 130 days of age, with the majority of the deaths occurring before 50 days. Ntv-a transgenic mice with different Lrig2 genotypes were transduced by intracranial injection with platelet-derived growth factor (PDGF) B-encoding replication-competent avian retrovirus (RCAS)-producing DF-1 cells. All injected Lrig2E12+/+ mice developed Lrig2 expressing oligodendroglial brain tumors of lower grade (82%) or glioblastoma-like tumors of higher grade (18%). Lrig2E12-/- mice, in contrast, only developed lower grade tumors (77%) or had no detectable tumors (23%). Lrig2E12-/- mouse embryonic fibroblasts (MEF) showed altered induction-kinetics of immediate-early genes Fos and Egr2 in response to PDGF-BB stimulation. However, Lrig2E12-/- MEFs showed no changes in Pdgfr alpha or Pdgfr beta levels or in levels of PDGF-BB-induced phosphorylation of Pdgfr alpha, Pdgfr beta, Akt, or extracellular signal-regulated protein kinases 1 and 2 (ERK1/2). Overexpression of LRIG1, but not of LRIG2, downregulated PDGFR alpha levels in HEK-293T cells. Conclusions: The phenotype of Lrig2E12-/- mice showed that Lrig2 was a promoter of PDGFB-induced glioma, and Lrig2 appeared to have important molecular and developmental functions that were distinct from those of Lrig1 and Lrig3.

  • 15. Yi, W
    et al.
    Haapasalo, H
    Holmlund, Camilla
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Oncology.
    Järvelä, S
    Raheem, O
    Bergenheim, A Tommy
    Umeå University, Faculty of Medicine, Department of Pharmacology and Clinical Neuroscience, Neurosurgery.
    Hedman, Håkan
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Oncology.
    Henriksson, Roger
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Oncology.
    Expression of leucine-rich repeats and immunoglobulin-like domains (LRIG) proteins in human ependymoma relates to tumor location, WHO grade, and patient age2009In: Clinical Neuropathology, ISSN 0722-5091, Vol. 28, no 1, p. 21-27Article in journal (Refereed)
    Abstract [en]

    Three human leucine-rich repeats and immunoglobulin-like domains (LRIG1-3) genes and proteins have recently been characterized. LRIG1 has been shown to be a suppressor of tumor growth by counteracting the signaling of epidermal growth factor receptor (EGFR) family members, including EGFR (ERBB1). Expression of LRIG proteins seems to be of importance in the pathogenesis of astrocytic tumors. In this study, the expression of LRIG1-3 was evaluated in 51 human ependymomas by immunohistochemistry. LRIG proteins were detected in all ependymomas analyzed, however, with a pronounced heterogeneity in expression and subcellular localization. Higher cytoplasmic immunoreactivity of LRIG1 correlated with older patient age and higher LRIG1 nuclear immunoreactivity with lower WHO Grade. LRIG1 displayed a stronger immunoreactivity in the cytoplasm and nuclei in spinal ependymomas than in the posterior fossa or supratentorial ependymomas, while perinuclear LRIG3 was more highly expressed in supratentorial than in infratentorial ependymomas. The indications that expression and subcellular localization of LRIG proteins could be pathogenetically associated with specific clinicopathological features of ependymoma tumors might be of importance in the carcinogeneses and tumor progression of human ependymomas.

  • 16.
    Yi, Wei
    et al.
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Oncology.
    Holmlund, Camilla
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Oncology.
    Nilsson, Jonas
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Oncology.
    Inui, Shigeki
    Department of Regenerative Dermatology, Graduate School of Medicine, Osaka University, Japan.
    Lei, Ting
    Department of Neurosurgery, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, China.
    Itami, Satoshi
    Department of Regenerative Dermatology, Graduate School of Medicine, Osaka University, Japan.
    Henriksson, Roger
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Oncology.
    Hedman, Håkan
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Oncology.
    Paracrine regulation of growth factor signaling by shed leucine-rich repeats and immunoglobulin-like domains 12011In: Experimental Cell Research, ISSN 0014-4827, E-ISSN 1090-2422, Vol. 317, no 4, p. 504-512Article in journal (Refereed)
    Abstract [en]

    Leucine-rich repeats and immunoglobulin-like domains 1 (LRIG1) is a recently discovered negative regulator of growth factor signaling. The LRIG1 integral membrane protein has been demonstrated to regulate various oncogenic receptor tyrosine kinases, including epidermal growth factor (EGF) receptor (EGFR), by cell-autonomous mechanisms. Here, we investigated whether LRIG1 ectodomains were shed, and if LRIG1 could regulate cell proliferation and EGF signaling in a paracrine manner. Cells constitutively shed LRIG1 ectodomains in vitro, and shedding was modulated by known regulators of metalloproteases, including the ADAM17 specific inhibitor TAPI-2. Furthermore, shedding was enhanced by ectopic expression of Adam17. LRIG1 ectodomains appeared to be shed in vivo, as well, as demonstrated by immunoblotting of mouse and human tissue lysates. Ectopic expression of LRIG1 in lymphocytes suppressed EGF signaling in co-cultured fibroblastoid cells, demonstrating that shed LRIG1 ectodomains can function in a paracrine fashion. Purified LRIG1 ectodomains suppressed EGF signaling without any apparent downregulation of EGFR levels. Taken together, the results show that the LRIG1 ectodomain can be proteolytically shed and can function as a non-cell-autonomous regulator of growth factor signaling. Thus, LRIG1 or its ectodomain could have therapeutic potential in the treatment of growth factor receptor-dependent cancers.

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