Hlutverk BRCA2 við að viðhalda litningaendum og stöðugleika litninga - verkefnislok
In the present study we found involvement of telomeres in chromosomal instability of breast tumors and cell lines from BRCA2 mutation carriers. This included higher frequency of chromosome end-to-end fusions (CEF) compared to controls indicating telomere capping defects, extrachromosomal telomeric repeat (ECTR) DNA scattered around metaphase chromosomes and common interstitial telomere sequences (ITS).
Heiti verkefnis: Hlutverk BRCA2 við að viðhalda litningaendum og stöðugleika litninga
Verkefnisstjóri: Sigríður Klara Böðvarsdóttir
Tegund styrks: Verkefnisstyrkur
Styrkár: 2010-2012
Fjárhæð styrks: 13,57 millj. kr. alls
Tilvísunarnúmer Rannís: 100455
Telomere sister chromatid exchanges (T-SCE), characteristic of cells using alternative lengthening of telomeres (ALT), were frequently detected. Chromatid type alterations were more prominent in the BRCA2 heterozygous cell lines that may have propensity for telomere based chromosome healing. Telomere dysfunction-induced foci (TIF) formation, identified by co-localization of telomeres and _-H2AX, supported telomere associated DNA damage response in BRCA2 heterozygous cell lines. These results suggest that BRCA2 has an important role in telomere stabilization by repressing CEFs through telomere capping and the prevention of telomere loss by replication stabilization. These phenotypes were also present in the FANCD1 cell lines (with homozygous BRCA2 mutations) but in an overstated manner. When BRCA2 heterozygous lymphoid cell lines were treated with Mitomycin C (MMC) cross linking agent chromosomal aberrations were induced like tri- and quadriradial chromosomes and shown to be more frequent than in MMC treated control cell lines indicating BRCA2 haploinsufficiency of BRCA2 heterozygous cells. In addition single telomere loss was drastically induced in these cell lines when treated with MMC. This indicates chromatid type alterations that may be due to sensitivity for DNA replication fork stalling, especially at telomeres recognized as single telomere loss or multiple telomere signals (MTS). Similar results were found in untreated FAND1 lymphoid cell lines including telomeresignal loss, MTS, ITS, ECTR, chromosome breaks with and without telomere signals and multicentromeric chromosomes. Conclusions driven from these results confirm that BRCA2 has an important role in maintaining genome stability, both in repairing DNA double strand breaks and in telomere maintenance and protection. We have preliminary results showing that BRCA2 breast cancer cases have shorter telomeres than sporadic cases. This was analysed by SYBR green quantitative PCR telomere length analysis of DNA from blood samples. Taken together, our results indicate BRCA2 haploinsufficiency
in relation to dysfunctional telomeres that could affect breast cancer risk among BRCA2 mutation carriers. Telomere length analysis could therefore be a promising tool to elevate breast cancer risk but further research is needed.
A list of project output:
Scientific per reviewed publications:
1. Skoulidis F, Cassidy LD, Pisupati V, Jonasson JG, Bjarnason H, Eyfjord JE, Karreth FA, Lim M, Barber LM, Clatworthy SA, Davies SE, Olive KP, Tuveson DA, Venkitaraman AR. Germline Brca2 heterozygosity promotes Kras(G12D) -driven carcinogenesis in a murine model of familial pancreatic cancer. Cancer Cell. 2010 Nov 16;18(5):499-509.
2. Stefansson OA, Jonasson JG, Bjarnason H, Johannsson OT, Olafsdottir K, Bodvarsdottir SK, Valgeirsdottir S, Eyfjord JE (2011). Characterization and copy number profiling of BRCA2 breast cancers reveals genetic networks linked to progression. Cancer Res 13(5):R95
3. Vidarsdottir L, Steingrimsdottir G, Bodvarsdottir SK, Ogmundsdottir HM, Eyfjord JE (2012). Sensitivity of BRCA2 mutated human cell lines to Aurora kinase inhibition. Invest New Drugs. 30(2): 425-434.
4. Bodvarsdottir SK, Steinarsdottir M, Bjarnason H, Eyfjord JE (2012). Dysfunctional telomeres in human BRCA2 breast tumors and cell lines. Mutat Res. 729(1-2):90-9.
Thesis from students:
1. Margrét Aradóttir. Aurora A nuclear expression and telomere length in BRCA2 related breast cancer. Master thesis at Faculty of Medicine, University of Iceland, October 2013.
2. Birna Þorvaldsdóttir. Dysfunctional telomeres and chromosomal aberrations in Fanconi anemia D1. B.Sc. thesis at Faculty of Environmental and life sciences, University of Iceland, May 2013.
3. Birna Þorvaldsdóttir. Is an association between telomere length in blood samples and chromosomal instability in breast tumors? Report to the Icelandic Student Innovation Fund, September 2013.
4. Hörður Bjarnason. Mitomycin C sensitivity and chromosomal alterations in BRCA2 mutated cells. Submission expected in Jan-Feb 2014.
Presentations:
1. Sigríður Klara Böðvarsdóttir. Dysfunctional telomeres in BRCA2 mutated breast tumors and cell lines. BMC Seminar, University of Iceland, February 2010.
2. Sigríður Klara Böðvarsdóttir, Hörður Bjarnason, Margrét Steinarsdóttir, Jórunn Erla Eyfjörð. Gallar í litningaendum í BRCA2 stökkbreyttum brjóstaæxlum og frumulínum. XV. Scientifical conference of Faculty of Medicine, University of Iceland, January 2011.
3. Hörður Bjarnason, Ólafur Andri Stefánsson, Jón Gunnlaugur Jónasson, Hólmfríður Hilmarsdóttir, Jórunn Erla Eyfjörð, Sigríður Klara Böðvarsdóttir. Tap á BRCA2 villigerðarsamsætu í brjósta-, blöðruháls- og briskrabbameinum í arfberum 999del5 kímlínustökkbreytingar og DNA viðgerðarhæfni í arfblendum brjóstaþekjufrumum. XV. Scientifical conference of Faculty of Medicine, University of Iceland, January 2011.
Posters:
1. Sigríður Klara Böðvarsdóttir, Margret Steinarsdóttir, Jorunn E Eyfjord. Dysfunctional telomeres in human BRCA2 mutated breast tumors and cell lines. 25-28 September 2011. EMBO Workshop: Chromosome structure, damage and repair. Cape Sounio, Greece
2. Jorunn Eyfjord, Olafur Stefansson, Margret Seinarsdottir, Sigridur K Bodvarsdottir. BRCA associated spontaneous tri-and quadriradial chromosome aberrations in primary familial and sporadic breast tumours. 25-28 September 2011. EMBO Workshop: Chromosome structure, damage and repair. Cape Sounio, Greece
3. Sigríður Klara Böðvarsdóttir, Margrét Aradóttir, Sigrídur T. Reynisdóttir, Hólmfrídur Hilmarsdóttir, Jón G. Jónasson, Jórunn E. Eyfjörd. BRCA2 haploinsufficiency induced telomere related genomic instability. October 2-6, 2012. EMBO Conference: Telomeres and DNA damage response, L´Isle sur la Sorgue, France.
4. Sigríður Klara Böðvarsdóttir, Hörður Bjarnason, Margrét Steinarsdóttir, Jórunn E Eyfjörð. BRCA2 stökkbreytt brjóstaæxli og brjóstafrumulínur með galla í telomere röðum á litningaendum. XVI. Scientifical conference of Faculty of Medicine, University of Iceland, January 2013.
5. Jórunn Eyfjörð, Ólafur Stefánsson, Margrét Seinarsdóttir, Sigríður K Böðvarsdóttir. Geislalitningar af völdum galla í BRCA tengdum ferlum í ættlægum og stökum brjóstaæxlum. XVI. Scientifical conference of Faculty of Medicine, University of Iceland, January 2013.
6. Sigríður Klara Böðvarsdóttir, Margrét Aradóttir, Sigríður Þ. Reynisdóttir, Hólmfríður Hilmarsdóttir, Jón G. Jónasson, Jórunn Erla Eyfjörð. Arfstök áhrif BRCA2 á telomer tengdan litningaóstöðugleika. XVI. Scientifical conference of Faculty of Medicine,
