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Hellström, Mats
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Publications (10 of 19) Show all publications
Testini, C., Smith, R. O., Jin, Y., Martinsson, P., Sun, Y., Hedlund, M., . . . Claesson-Welsh, L. (2019). Myc-dependent endothelial proliferation is controlled by phosphotyrosine 1212 in VEGF receptor-2. EMBO Reports, 20(11), Article ID e47845.
Open this publication in new window or tab >>Myc-dependent endothelial proliferation is controlled by phosphotyrosine 1212 in VEGF receptor-2
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2019 (English)In: EMBO Reports, ISSN 1469-221X, E-ISSN 1469-3178, Vol. 20, no 11, article id e47845Article in journal (Refereed) Published
Abstract [en]

Exaggerated signaling by vascular endothelial growth factor (VEGF)-A and its receptor, VEGFR2, in pathologies results in poor vessel function. Still, pharmacological suppression of VEGFA/VEGFR2 may aggravate disease. Delineating VEGFR2 signaling in vivo provides strategies for suppression of specific VEGFR2-induced pathways. Three VEGFR2 tyrosine residues (Y949, Y1212, and Y1173) induce downstream signaling. Here, we show that knock-in of phenylalanine to create VEGFR2 Y1212F in C57Bl/6 and FVB mouse strains leads to loss of growth factor receptor-bound protein 2- and phosphoinositide 3 '-kinase (PI3K)p85 signaling. C57Bl/6 Vegfr2(Y1212F/Y1212F) show reduced embryonic endothelial cell (EC) proliferation and partial lethality. FVB Vegfr2(Y1212F/Y1212F) show reduced postnatal EC proliferation. Reduced EC proliferation in Vegfr2(Y1212F/Y1212F) explants is rescued by c-Myc overexpression. We conclude that VEGFR2 Y1212 signaling induces activation of extracellular-signal-regulated kinase (ERK)1/2 and Akt pathways required for c-Myc-dependent gene regulation, endothelial proliferation, and vessel stability.

Keywords
angiogenesis, GRB2, Nck, PI3Kp85, proliferation
National Category
Cell and Molecular Biology
Identifiers
urn:nbn:se:uu:diva-397954 (URN)10.15252/embr.201947845 (DOI)000496229500001 ()31545012 (PubMedID)
Funder
Swedish Research Council, 2015-02375Swedish Cancer Society, CAN2016/578Knut and Alice Wallenberg Foundation, KAW 2015.0030Knut and Alice Wallenberg Foundation, 2015.0275
Available from: 2020-01-02 Created: 2020-01-02 Last updated: 2020-01-02Bibliographically approved
Kundu, S., Ali, M. A., Handin, N., Padhan, N., Larsson, J., Karoutsou, M., . . . Sjöblom, T. (2018). Linking FOXO3, NCOA3, and TCF7L2 to Ras pathway phenotypes through a genome-wide forward genetic screen in human colorectal cancer cells. Genome Medicine, 10, Article ID 2.
Open this publication in new window or tab >>Linking FOXO3, NCOA3, and TCF7L2 to Ras pathway phenotypes through a genome-wide forward genetic screen in human colorectal cancer cells
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2018 (English)In: Genome Medicine, ISSN 1756-994X, E-ISSN 1756-994X, Vol. 10, article id 2Article in journal (Refereed) Published
Abstract [en]

Background:

The Ras pathway genes KRAS, BRAF, or ERBBs have somatic mutations in similar to 60% of human colorectal carcinomas. At present, it is unknown whether the remaining cases lack mutations activating the Ras pathway or whether they have acquired mutations in genes hitherto unknown to belong to the pathway.

Methods:

To address the second possibility and extend the compendium of Ras pathway genes, we used genome-wide transposon mutagenesis of two human colorectal cancer cell systems deprived of their activating KRAS or BRAF allele to identify genes enabling growth in low glucose, a Ras pathway phenotype, when targeted.

Results:

Of the 163 recurrently targeted genes in the two different genetic backgrounds, one-third were known cancer genes and one-fifth had links to the EGFR/Ras/MAPK pathway. When compared to cancer genome sequencing datasets, nine genes also mutated in human colorectal cancers were identified. Among these, stable knockdown of FOXO3, NCOA3, and TCF7L2 restored growth in low glucose but reduced MEK/MAPK phosphorylation, reduced anchorage-independent growth, and modulated expressions of GLUT1 and Ras pathway related proteins. Knockdown of NCOA3 and FOXO3 significantly decreased the sensitivity to cetuximab of KRAS mutant but not wild-type cells.

Conclusions:

This work establishes a proof-of-concept that human cell-based genome-wide forward genetic screens can assign genes to pathways with clinical importance in human colorectal cancer.

Keywords
Forward genetics, piggyBac transposon, Colorectal cancer, Ras pathway
National Category
Medical Genetics
Identifiers
urn:nbn:se:uu:diva-341500 (URN)10.1186/s13073-017-0511-4 (DOI)000419613600002 ()29301589 (PubMedID)
Available from: 2018-02-14 Created: 2018-02-14 Last updated: 2018-02-14Bibliographically approved
Egaña, I., Kaito, H., Nitzsche, A., Becker, L., Ballester-Lopez, C., Niaudet, C., . . . Hellström, M. (2017). Female mice lacking Pald1 exhibit endothelial cell apoptosis and emphysema. Scientific Reports, 7(15453)
Open this publication in new window or tab >>Female mice lacking Pald1 exhibit endothelial cell apoptosis and emphysema
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2017 (English)In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 7, no 15453Article in journal (Refereed) Published
Abstract [en]

Paladin (Pald1, mKIAA1274 or x99384) was identified in screens for vascular-specific genes and is a putative phosphatase. Paladin has also been proposed to be involved in various biological processes such as insulin signaling, innate immunity and neural crest migration. To determine the role of paladin we have now characterized the Pald1 knock-out mouse in a broad array of behavioral, physiological and biochemical tests. Here, we show that female, but not male, Pald1 heterozygous and homozygous knock-out mice display an emphysema-like histology with increased alveolar air spaces and impaired lung function with an obstructive phenotype. In contrast to many other tissues where Pald1 is restricted to the vascular compartment, Pald1 is expressed in both the epithelial and mesenchymal compartments of the postnatal lung. However, in Pald1 knock-out females, there is a specific increase in apoptosis and proliferation of endothelial cells, but not in non-endothelial cells. This results in a transient reduction of endothelial cells in the maturing lung. Our data suggests that Pald1 is required during lung vascular development and for normal function of the developing and adult lung in a sex-specific manner. To our knowledge, this is the first report of a sex-specific effect on endothelial cell apoptosis.

National Category
Cell and Molecular Biology
Identifiers
urn:nbn:se:uu:diva-281704 (URN)10.1038/s41598-017-14894-9 (DOI)000415023200014 ()29133847 (PubMedID)
Funder
Swedish Cancer SocietyÅke Wiberg Foundation
Note

List of authors in thesis manuscript: Egaña I, Nitzsche A, Kaito H, Becker L, Garrett L, Niaudet C, Liu W, Vanlandewijck M, Larsson J, Hrabe de Angelis M, Fuchs H, Gailus-Durner V, Vernaleken A, Klopstock T, Hölter S M, Wurst W, Rask-Andersen H, German Mouse Clinic Consortium, Yildirim A Ö, Hellström M

Available from: 2016-04-18 Created: 2016-03-29 Last updated: 2018-02-22Bibliographically approved
Pandzic, T., Rendo, V., Lim, J., Larsson, C., Larsson, J., Stoimenov, I., . . . Sjöblom, T. (2017). Somatic PRDM2 c.4467delA mutations in colorectal cancers control histone methylation and tumor growth. OncoTarget, 8(58), 98646-98659
Open this publication in new window or tab >>Somatic PRDM2 c.4467delA mutations in colorectal cancers control histone methylation and tumor growth
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2017 (English)In: OncoTarget, ISSN 1949-2553, E-ISSN 1949-2553, Vol. 8, no 58, p. 98646-98659Article in journal (Refereed) Published
Abstract [en]

The chromatin modifier PRDM2/RIZ1 is inactivated by mutation in several forms of cancer and is a putative tumor suppressor gene. Frameshift mutations in the C-terminal region of PRDM2, affecting (A)8 or (A)9 repeats within exon 8, are found in one third of colorectal cancers with microsatellite instability, but the contribution of these mutations to colorectal tumorigenesis is unknown. To model somatic mutations in microsatellite unstable tumors, we devised a general approach to perform genome editing while stabilizing the mutated nucleotide repeat. We then engineered isogenic cell systems where the PRDM2 c.4467delA mutation in human HCT116 colorectal cancer cells was corrected to wild-type by genome editing. Restored PRDM2 increased global histone 3 lysine 9 dimethylation and reduced migration, anchorage-independent growth and tumor growth in vivo. Gene set enrichment analysis revealed regulation of several hallmark cancer pathways, particularly of epithelial-to-mesenchymal transition (EMT), with VIM being the most significantly regulated gene. These observations provide direct evidence that PRDM2 c.4467delA is a driver mutation in colorectal cancer and confirms PRDM2 as a cancer gene, pointing to regulation of EMT as a central aspect of its tumor suppressive action.

National Category
Cancer and Oncology
Identifiers
urn:nbn:se:uu:diva-345974 (URN)10.18632/oncotarget.21713 (DOI)000419392300074 ()
Funder
Swedish Foundation for Strategic Research , F06-0050 RBa08-0114Swedish Cancer Society, 2006/2154 2007/775 2012/834
Available from: 2018-03-13 Created: 2018-03-13 Last updated: 2018-09-20Bibliographically approved
Pandzic, T., Larsson, J., He, L., Kundu, S., Ban, K., Ali, M. A., . . . Hellström, M. (2016). Transposon Mutagenesis Reveals Fludarabine Resistance Mechanisms in Chronic Lymphocytic Leukemia. Clinical Cancer Research, 22(24), 6217-6227
Open this publication in new window or tab >>Transposon Mutagenesis Reveals Fludarabine Resistance Mechanisms in Chronic Lymphocytic Leukemia
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2016 (English)In: Clinical Cancer Research, ISSN 1078-0432, E-ISSN 1557-3265, Vol. 22, no 24, p. 6217-6227Article in journal (Refereed) Published
Abstract [en]

Purpose: To identify resistance mechanisms for the chemotherapeutic drug fludarabine in chronic lymphocytic leukemia (CLL), as innate and acquired resistance to fludarabine-based chemotherapy represents a major challenge for long-term disease control. Experimental Design: We used piggyBac transposon-mediated mutagenesis, combined with next-generation sequencing, to identify genes that confer resistance to fludarabine in a human CLL cell line. Results: In total, this screen identified 782 genes with transposon integrations in fludarabine-resistant pools of cells. One of the identified genes is a known resistance mediator DCK (deoxycytidine kinase), which encodes an enzyme that is essential for the phosphorylation of the prodrug to the active metabolite. BMP2K, a gene not previously linked to CLL, was also identified as a modulator of response to fludarabine. In addition, 10 of 782 transposon-targeted genes had previously been implicated in treatment resistance based on somatic mutations seen in patients refractory to fludarabine-based therapy. Functional characterization of these genes supported a significant role for ARID5B and BRAF in fludarabine sensitivity. Finally, pathway analysis of transposon-targeted genes and RNA-seq profiling of fludarabine-resistant cells suggested deregulated MAPK signaling as involved in mediating drug resistance in CLL. Conclusions: To our knowledge, this is the first forward genetic screen for chemotherapy resistance in CLL. The screen pinpointed novel genes and pathways involved in fludarabine resistance along with previously known resistance mechanisms. Transposon screens can therefore aid interpretation of cancer genome sequencing data in the identification of genes modifying sensitivity to chemotherapy.

National Category
Cancer and Oncology
Identifiers
urn:nbn:se:uu:diva-315914 (URN)10.1158/1078-0432.CCR-15-2903 (DOI)000391472400028 ()26957556 (PubMedID)
Funder
Swedish Cancer SocietySwedish Research CouncilSwedish National Infrastructure for Computing (SNIC), b2014071
Available from: 2017-02-23 Created: 2017-02-23 Last updated: 2017-11-29Bibliographically approved
Heiss, M., Hellstrom, M., Kalen, M., May, T., Weber, H., Hecker, M., . . . Korff, T. (2015). Endothelial cell spheroids as a versatile tool to study angiogenesis in vitro. The FASEB Journal, 29(7), 3076-3084
Open this publication in new window or tab >>Endothelial cell spheroids as a versatile tool to study angiogenesis in vitro
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2015 (English)In: The FASEB Journal, ISSN 0892-6638, E-ISSN 1530-6860, Vol. 29, no 7, p. 3076-3084Article in journal (Refereed) Published
Abstract [en]

Given the need for robust and cost-efficient in vitro models to study angiogenesis and reproducibly analyze potential pro-and antiangiogenic compounds in preclinical studies, we developed a 3-dimensional in vitro angiogenesis assay that is based on collagen gel-embedded, size-defined spheroids generated from cultured human umbilical vein endothelial cells (HUVECs). Despite its wide distribution, limitations, sensitivity, robustness, and improvements, the capacity of this assay for functional screening purposes has not been elucidated thus far. By using time-lapse video microscopy, we show that tip cells lead the formation of capillary-like and partially lumenized sprouts originating from the spheroids. Angiogenic sprouting from spheroids generated from 5 different primary cultured human endothelial cell types was induced by physiologic concentrations of vascular endothelial cell growth factor 165. Based on this assay system, we determined the capacity of 880 approved drugs to interfere with or boost angiogenic sprouting, thereby assessing their putative angiogenesis-related side effects or novel applications. However, although this assay allowed for a rapid and reproducible determination of functional IC50 values of individual compounds, the sprouting results were partially affected by the HUVEC passage number and donor variability. To overcome this limitation, immortalized HUVECs (iHUVECs) showing a more homogenous response in terms of proliferation and sprouting over multiple population doublings were used in the course of this study. Collectively, the spheroid-based angiogenesis assay provides a sensitive and versatile tool to study the impact of pro-and antiangiogenic determinants on multiple steps of the angiogenic cascade. It is compatible with different endothelial cell types and allows use of iHUVECs to improve its overall robustness.

Keywords
HUVEC, VEGF, tip cells
National Category
Biochemistry and Molecular Biology
Identifiers
urn:nbn:se:uu:diva-258754 (URN)10.1096/fj.14-267633 (DOI)000356859100034 ()25857554 (PubMedID)
Available from: 2015-07-21 Created: 2015-07-20 Last updated: 2017-12-04Bibliographically approved
Mansouri, L., Sutton, L.-A., Ljungström, V., Bondza, S., Arngården, L., Bhoi, S., . . . Rosenquist Brandell, R. (2015). Functional loss of IκBε leads to NF-κB deregulation in aggressive chronic lymphocytic leukemia. Journal of Experimental Medicine, 212(6), 833-843
Open this publication in new window or tab >>Functional loss of IκBε leads to NF-κB deregulation in aggressive chronic lymphocytic leukemia
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2015 (English)In: Journal of Experimental Medicine, ISSN 0022-1007, E-ISSN 1540-9538, Vol. 212, no 6, p. 833-843Article in journal (Refereed) Published
Abstract [en]

NF-κB is constitutively activated in chronic lymphocytic leukemia (CLL); however, the implicated molecular mechanisms remain largely unknown. Thus, we performed targeted deep sequencing of 18 core complex genes within the NF-κB pathway in a discovery and validation CLL cohort totaling 315 cases. The most frequently mutated gene was NFKBIE (21/315 cases; 7%), which encodes IκBε, a negative regulator of NF-κB in normal B cells. Strikingly, 13 of these cases carried an identical 4-bp frameshift deletion, resulting in a truncated protein. Screening of an additional 377 CLL cases revealed that NFKBIE aberrations predominated in poor-prognostic patients and were associated with inferior outcome. Minor subclones and/or clonal evolution were also observed, thus potentially linking this recurrent event to disease progression. Compared with wild-type patients, NFKBIE-deleted cases showed reduced IκBε protein levels and decreased p65 inhibition, along with increased phosphorylation and nuclear translocation of p65. Considering the central role of B cell receptor (BcR) signaling in CLL pathobiology, it is notable that IκBε loss was enriched in aggressive cases with distinctive stereotyped BcR, likely contributing to their poor prognosis, and leading to an altered response to BcR inhibitors. Because NFKBIE deletions were observed in several other B cell lymphomas, our findings suggest a novel common mechanism of NF-κB deregulation during lymphomagenesis.

National Category
Cell and Molecular Biology
Identifiers
urn:nbn:se:uu:diva-279237 (URN)10.1084/jem.20142009 (DOI)000355569300001 ()25987724 (PubMedID)
Funder
Swedish National Infrastructure for Computing (SNIC), b2011080Swedish Cancer SocietySwedish Research CouncilNIH (National Institute of Health), CA81554; CA081554EU, European Research Council, 259796EU, FP7, Seventh Framework Programme, 306242
Available from: 2016-02-29 Created: 2016-02-29 Last updated: 2018-01-10Bibliographically approved
Hjelmqvist, D., Hellström, M. & Lau, J. (2014). Improving Pancreatic Islet Engraftment after Islet Transplantation through Administration of Gamma-Secretase Inhibitor DAPT. Journal of endocrinology and diabetes mellitus, 2, 65-69
Open this publication in new window or tab >>Improving Pancreatic Islet Engraftment after Islet Transplantation through Administration of Gamma-Secretase Inhibitor DAPT
2014 (English)In: Journal of endocrinology and diabetes mellitus, ISSN 2310-9971, Vol. 2, p. 65-69Article in journal (Refereed) Published
Abstract [en]

Abstract: Rapid and effective revascularization of transplanted pancreatic islets is vital for the survival and function of the islet graft. Insufficient vascularization after islet transplantation may be one causative factor to the failure of islet grafts in clinical transplantation. The aim of this study was to investigate if N-{N-[2-(3,5-Difluorophenyl)acetyl]-(S)-alanyl}- (S)-phenylglycine- tert-butyl ester (DAPT) administration can improve engraftment of transplanted islets. DAPT is a dipeptidic gamma-secretase inhibitor which inhibits Notch signaling. Notch signaling is involved in angiogenesis and inhibition may result in excessive formation of new blood vessels. Excessive vasculature may be beneficial in the immediate posttransplantation period since the transplanted islets are dependent on diffusion of oxygen and nutrients before revascularization. Islets isolated from C57BL/6 mice were transplanted beneath the renal capsule of C57BL/6 mice. After islet transplantation DAPT or vehicle was administered subcutaneously for three days. Mice treated with DAPT had an increased vascular density when compared to control mice two days and one month posttransplantation. Moreover, mice treated with DAPT showed 54±8.2 % functional blood vessels compared to 40±6.7 % in control mice two days posttransplantation. After one month, the fraction of functional blood vessels increased to 86±2.8 % in DAPT treated mice compared to 61±9.4 % in control mice. Our findings demonstrated that administration of DAPT may be a feasible strategy to improve engraftment of transplanted islets.

Place, publisher, year, edition, pages
Synergy Publishers, 2014
National Category
Medical and Health Sciences
Identifiers
urn:nbn:se:uu:diva-245745 (URN)10.12970/2310-9971.2014.02.02.5 (DOI)
Available from: 2015-02-27 Created: 2015-02-27 Last updated: 2015-03-02Bibliographically approved
Mansouri, L., Sutton, L.-A., Ljungström, V., Bondza, S., Arngården, L., Bhoi, S., . . . Rosenquist, R. (2014). Recurrent Mutations within the Nfkbie gene: A Novel Mechanism for NF-kappa B Deregulation in Aggressive Chronic Lymphocytic Leukemia. Blood, 124(21)
Open this publication in new window or tab >>Recurrent Mutations within the Nfkbie gene: A Novel Mechanism for NF-kappa B Deregulation in Aggressive Chronic Lymphocytic Leukemia
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2014 (English)In: Blood, ISSN 0006-4971, E-ISSN 1528-0020, Vol. 124, no 21Article in journal, Meeting abstract (Other academic) Published
National Category
Hematology
Identifiers
urn:nbn:se:uu:diva-249073 (URN)000349242707052 ()
Available from: 2015-04-17 Created: 2015-04-10 Last updated: 2017-12-04Bibliographically approved
Benedito, R. & Hellström, M. (2013). Notch as a hub for signaling in angiogenesis. Experimental Cell Research, 319(9), 1281-1288
Open this publication in new window or tab >>Notch as a hub for signaling in angiogenesis
2013 (English)In: Experimental Cell Research, ISSN 0014-4827, E-ISSN 1090-2422, Vol. 319, no 9, p. 1281-1288Article, review/survey (Refereed) Published
National Category
Medical and Health Sciences
Identifiers
urn:nbn:se:uu:diva-203422 (URN)10.1016/j.yexcr.2013.01.010 (DOI)000319369500007 ()
Available from: 2013-07-10 Created: 2013-07-10 Last updated: 2017-12-06Bibliographically approved
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