Research Interests:

• Mechanisms of c-Myc-dependent genomic instability. Analysis of replication- and/or segregation-driven mechanisms of c-Myc-dependent gene amplification.
• Myc mutants in genomic instability, apoptosis, and tumor development
• Structure and function of c-myc induced extrachromosomal elements (EEs).
• Genomic instability in pre-malignant cells. Tumor initiation and progression.
• The three-dimensional organization of the interphase nucleus in normal, immortalized and tumor cells.
  (Sample Movie 1) 
  (Sample Movie 2)
  
  Figure legends for movies. The 3D movies show the positions of chromosomes 5 (red) and 13 (green) in a diploid mouse Pre B lymphocyte line. Note the movement of both chromosomes 5 and 13 thirty hours after experimentally induced c-Myc deregulation. For details, see Louis et al., 2005.

Training opportunities / workshops and courses offered

"Innovative Technologies in Multidisciplinary Health Research Training". Advanced molecular imaging and analysis and applied genomics using emerging innovative technologies. Multinational, multidisciplinary, and industry-involved. Training target groups: graduate students, medical students, MD/PhD students, residents, clinical fellows, clinician-scientists, visiting fellows, clinical geneticists, technicians and research associates. Training through workshops, seminars, short- and long-term research projects. For details, see www.itmhrt.ca

Focus on mechanisms of genomic instability.

Genomic instability is a hallmark of pre-neoplastic and neoplastic cells. The mechanisms underlying the induction of genomic instability in cells have been poorly elucidated. We were first to demonstrate that c-Myc deregulation induces locus-specific genomic instability (Mai, 1994) and karyotypic instability (Mai et al., 1996a). Using c-Myc-inducible cell lines, we have identified the following genes as targets of c-Myc in genomic instability: dihydrofolate reductase (DHFR) (Mai, 1994, 1996b, Taylor et al., 1997, Taylor and Mai, 1998), ribonucleotide reductase R2 (Kuschak et al., 1999a), cyclin D2 (CCND2) (Mai et al., 1999), ornithine decarboxylase (ODC) (Smith et al., 2002, 2003), cyclin B1 (Mai et al., 2004). For reviews, see Mai and Mushinski, 2003; Kuttler and Mai, 2005. Our ongoing work focuses on the initiating mechanisms of c-Myc-mediated genomic instability and on the three-dimensional organization of the nucleus. The following research areas are actively pursued:

1) c-Myc-induced illegitimate DNA replication and re-organization of the genome.
2) c-Myc and mutant myc box II Myc protein-induced genomic instability and apoptosis.
3) c-Myc induced formation of extrachromosomal elements (EEs). 
4) Mechanisms of plasmacytoma development. 
5) The three-dimensional organization of the mammalian nucleus. 

Our previous work on c-Myc-dependent genomic instability.

c-Myc-dependent genomic instability has been observed in cell lines of different species and tissue origins, and also in vivo. DHFR gene amplification was found within the first week of pristane-induced c-Myc-dependent plasmacytomas in Balb/c mice. Moreover, we observed the spontaneous c-Myc deregulation in 5-15% of all hematopoietic cells of the fetal liver of p53 nullizygous (p53-/-) embryos as well as in the bone marrow, spleen, thymus, and primary fibroblasts of 4-6 week old p53 nullizygous (p53-/-) mice. The deregulation of c-Myc was associated with the locus-specific amplification of c-Myc target genes. In contrast, age-matched control mice (p53+/+) did not display genomic instability and c-Myc deregulation.

Mechanisms of c-Myc deregulation in translocation-negative plasmacytomas.

The activation of the c-myc gene is key to the development of all murine plasmacytomas (PCTs), resulting in deregulated levels of endogenous c-Myc protein expression. In the majority of pristane-induced mouse PCTs, the deregulation of c-myc transcription is achieved by chromosomal translocation that juxtaposes the c-myc/pvt-1 locus on chromosome 15 to one of the immunoglobulin (Ig) loci: on chromosome 12 (IgH), 6(IgK) or 16(IgL).

Several translocation-negative PCTs with deregulated Myc expression have been described. The histological features of such PCTs and the course of disease are indistinguishable from the ones with the typical chromosomal translocations. We have recently studied a translocation-negative mouse plasmacytoma, DCPC21, in great detail (Wiener et al., Proc. Natl. Acad. Sci. (USA) 96: 13967-13972, 1999) (see Fig.1). We have found that c-myc is juxtaposed to IgH on extrachromosomal elements (EEs). These EEs are functional genetic units able to transcribe c-myc as shown in mRNA track studies on the single cell level. This is further supported by the presence of active chromatin on these extrachromosomal DNA molecules. We have shown in addition, that the c-myc/IgH-containing EEs are able to confer c-Myc expression to non-proliferating B cells upon extrachromosomal gene transfer. Interestingly, when introduced into primary B cells, the c-myc/IgH-carrying EEs induce cell death in the majority of the target cells within 24 hours.


Figure 1

Development of novel technologies to study genomic instability.

- Quantitative analysis of protein levels and gene copy numbers by fluorescent in situ hybridization (FISH) within the same cell. This assay is called CPFA (Combined Protein/FISH Analysis)(Fukasawa et al. Oncogene 15: 1295-1302. 1997)..
- Analysis of the total cellular population of extrachromosomal elements (EEs) by FISH. This assay allows one to examine every gene of choice for its presence on EEs (Kuschak et al. Technical Tips Online. T01669. 1999).
- Banding technology for mouse chromosomes that works after spectral karyotyping (SKY). This allows one to examine mouse chromosomes as carefully as human chromosomes in SKY analyses (Wiener and Mai. Technical Tips Online T01884. 2000).
- Protocol for the preparation of elongated mouse chromosomes.
- Three-dimensional imaging of the interphase nucleus.
-Multicolor banding (mBAND) of mouse chromosome 11


Recent Publications:

1. Sarkar R, Guffei A, Vermolen BJ, Garini Y, Mai S. Alterations of centromere positions in nuclei of immortalized and malignant mouse lymphocytes. Cytometry Part A. In press. 2007.
2. Caporali A, Wark L, Vermolen BJ, Garini Y, Mai S. Telomeric aggregates and end-to-end chromosomal fusions require myc box II. Oncogene 26(10):1398-1406, 2007. [Epub 2006 Sep 4].
3. Mai S, Imreh S. Non-random genomic instability: A fact, not an illusion. Semin Cancer Biol. 17: 1-4. 2007. [Epub ahead of print: Nov 12, 2006].
4. Kuttler F and Mai S. Formation of non-random extrachromosomal elements during development, differentiation and oncogenesis. Seminars in Cancer Biology 17:56-64, 2007. [Epub ahead of print: 2006 Oct 26].
5. Mai S. The three-dimensional organization of the mammalian nucleus in normal and tumor cells. Atlas of Genetics and Cytogenetics in Hematology and Oncology. November 2005. URL: http://AtlasGeneticsOncology.org/Deep/3DOrganizNuclID20053.html.
6. Intasai N, Mai S, Kasinrerk W, Tayapiwatana C. Binding of multivalent CD147 phage induces apoptosis of U937 cells. Int J Immunol. In press. 2006.
7. Kuttler F and Mai S. c-Myc, genomic instability and disease. In: Volff, J-N. (ed). Genome dynamics. Vol 1: Genome and Disease. Karger Publishers, Wuerzburg, Germany. 171-191. 2006.
8. Cao L, Kim S, Xiao C, Wang R-H, Coumoul X, Wang X, Li WM, Xu XL, De Soto JA, Takai H, Mai S, Elledge SJ, Motoyama N, Deng C-X. ATM-chk2-p53 activation prevents tumorigenesis at an expense of organ homeostasis upon Brca1 deficiency. The EMBO J. 25(10):2167-77. Epub 2006 May 4.
9. Mai S and Garini Y. The significance of telomeric aggregates in the interphase nuclei of tumor cells. Journal Cell Biochem. 97: 904-915. 2006 Jan 11; [Epub ahead of print].
10. Paul JT, Mushinski JF, Henson E, Chuang M, Gibson S, Mai S, Johnston J. Cyclin D expression in chronic lymphocytic leukemia. Leukemia & Lymphoma 46: 1275-85. 2005
11. Mai S and Garini Y. Oncogenic remodeling of the three-dimensional organization of the interphase nucleus: c-Myc induces telomeric aggregates whose formation precedes chromosomal rearrangements. Cell Cycle 4:10, 1327-1331. 2005.
12. Vermolen BJ, Garini Y, Mai S, Mougey V, Fest T, Chuang TCY, Chuang AYC, Wark L, and Young IT. Characterizing the Three-Dimensional Organization of Telomeres. Cytometry. 2005. In press. 
13. Panigrahi S and Mai S. Telomeres, genomic instability, DNA repair and breast cancer. Curr. Med Chem ? Anti-Inflammatory & Anti-Allergy Agents 4: 421-428. 2005.
14. Louis S, Gruhne B, Mai S. Towards an understanding of DNA replication in normal and cancer cells: facts and concepts. Review. Progress in Oncogene Research. Chapter I, p. 1-56. Nova Science Publishers, Inc. Hauppauge, NY. 2005.
15. Rak M, Gough K, Del Bigio MR, Mai S, Westaway D. In Situ FTIR Spectromicroscopy of Brain Tissue from a Transgenic Mouse Model of Alzheimer Disease. Vibr Spectrosc 38, 133-141. 2005.
16. Louis SF, Vermolen BJ, Garini Y, Young IT, Guffei A, Zelda Lichtensztejn Z, Fabien Kuttler F, Chuang TCY, Moshir S, Mougey V, Chuang, AYC, Kerr PD, Fest T, Boukamp P, Mai S. c-Myc induces chromosomal rearrangements through telomere and chromosome remodeling in the interphase nucleus. Proc Natl Acad Sci (USA) 102(27): 9613-8. 2005.
17. Fest T, Guffei A, Williams G, Silva S, Mai S. Uncoupling of genomic instability and tumorigenesis in a mouse model of Burkitt?s lymphoma expressing conditional box II-deleted Myc protein. Oncogene 24(18):2944-53. 2005.
18. Kuttler F and Mai S. c-Myc, genomic instability and disease. In: Volff, J-N. (ed). Genome dynamics. Vol 1: Genome and Disease. Karger Publishers, Wuerzburg, Germany. 2005. In press.
19. Mai S, Guffei A, Fest T, Mushinski JF. c-Myc Deregulation Promotes a Complex Network of Genomic Instability. In: Hormonal Carcinogenesis IV (Eds. Li JJ, Li SA, Llombart-Bosch A).Springer-Verlag, New York, pp 87-97. 2005.
20. Ermler S, Krunic D, Knoch TA, Mai S, Greulich-Bode KM, Moshir S and Boukamp P. Cell cycle-dependent 3D distribution of telomeres and TRF2 in HaCaT and HaCaT-myc cells. European J of Cell Biol. Eur J Cell Biol 83: 681-90. 2004. 
21. Louis S, Benedek K, Mowat M, Klein G, Wiener F and Mai S. Elongated mouse chromosomes suitable for enhanced molecular cytogenetics. Cytotechnology 44(3): 143-149. 2004. 
22. Benedek K, Chudoba I, Klein G, Wiener F, Mai S. Rearrangements of the telomeric region of mouse chromosome 11 in Pre-B ABL/MYC cells revealed by mBANDing, spectral karyotyping, and fluoresence in situ hybridization. Chromosome Research 12: 1-9. 2004. 
23. Chuang TCY, Moshir S, Garini Y, Chuang AYC, IT Young, van den Doel R, Mougey V, M Perrin, M Braun, Kerr DP, Fest T, Boukamp P, Mai S. The three-dimensional organization of telomeres in the nucleus of mammalian cells. BMC Biology 2: 12. 2004. 
24. Mai, S and Mushinski JF. c-Myc-dependent genomic instability. J. Environ Path Toxicol Oncol 22: 179-199. 2003.
25. Abrahams BS, Chong ACO, Nisha M, Milette D, Brewster D, Berry ML, Muratkhodjaev F, Mai S, Rajcan-Separovic, Simpsom EM. Metaphase FISHing of transgenic mice recommended: FISH and SKY define BAC-mediated balanced translocation. Genesis 36: 134-41. 2003
26. Smith, G, Dushnicki, L, Smith, S, Wright, JA, Mai, S. c-Myc-induced extrachromosomal elements carry active chromatin. Neoplasia 5: 110-20. 2003. Article and journal cover.
27. Beatty, B, Mai, S., Squire, J. (Eds). FISH: A practical approach. Oxford University Press. 2002.
28. Mai, S. and Wiener, F. Murine FISH. In: FISH: A practical approach. Oxford University Press. 2002.
29. Thierry Fest, T., Mougey, V., Dalstein, V., Hagerty, M.L., Milette, D., Silva, S. and Mai, S. c-MYC overexpression in Ba/F3 cells simultaneously elicits genomic instability and apoptosis. Oncogene 21: 2981-2990. 2002.
30. Mai, S. and Wiener, F. The impact of p53 loss on murine plasmacytoma development. Chromosome Research 10: 239-251. 2002.
31. Kuschak, T.I., Kuschak, B.C., Taylor, C., Wright, J.A., Wiener, F. and Mai, S. c-Myc initiates illegitimate replication of the ribonucleotide reductase R2 gene. Oncogene 21: 909-920. 2002. PMID 11840336
32. Mai, S. and Mushinski, J.F. c-Myc-mediated genomic instability. Critical Reviews in Oncogenesis 21: 31-47. 2001. 
33. Kuschak, T.I., Kuschak, B., Smith, G., Wright, J.A. and Mai, S. Immunoprecipitation of extrachromosomal DNA using anti-histone antibodies. BioTechniques 30(5):1065-1072, 2001. PMID 11355342
34. Hicks, G.G., Singh, N., Nashabi, A., Mai, S., Bozek, G., Klewes, L., White, E.K., 2, Koury, M.J., Oltz, E.M., Van Kaer, L., and Ruley, H.E. Fus deficiency in mice results in defective B lymphocyte development and activation, high levels of chromosomal instability and perinatal death. Nature Genetics. 24: 175-179. 2000. PMID 10655065
35. Wiener, F. and Mai, S. Banding of mouse chromosomes after spectral karyotyping. Technical Tips Online. http://www.biomednet.com/db/tto. T01884. 2000.
36. Kuschak, T.I., Paul, J.T., Wright, J.A., Mushinski, J.F. and Mai, S. FISH on purified extrachromsomal elements. Technical Tips Online. http://www.biomednet.com/db/tto. T01669. 1999.
37. Wiener, F., Kuschak, T.I., Ohno, S. and Mai, S. Deregulated expression of c-Myc in a translocation-negative plasmacytoma on extrachromosomal elements that carry IgH and c-myc genes. Proc. Natl. Acad. Sci (USA). 96 (24):
    13967-13972. 1999.
38. Kuschak, T.I., Taylor, C., McMillan-Ward, E., Israels, S., Henderson, D.W., Mushinski, J.F., Wright, J.A. and Mai, S. The ribonucleotide reductase R2 gene is a non-transcribed target of c-Myc-induced genomic instability. Gene 238: 351-365. 1999. PMID 10570963
39. Mai, S., Hanley-Hyde, J., Rainey, G.J., Kuschak, T.I., Paul, J.T., Littlewood, T.D., Mischak, H., Stevens, L.M., Henderson, D.W., Mushinski, J.F. Chromosomal and extrachromosomal instability of the cyclin D2 gene is induced by Myc overexpression. Neoplasia 1: 241-252. 1999.
40. Taylor, C. and Mai, S. 1998. c-Myc-associated genomic instability of the DHFR locus in vivo. Cancer Detect Prevent. 22: 350-356. 1998. PMID 9674878
41. Fukasawa, K., Wiener, F., Vande Woude, G. F., Mai, S. 1997. Genomic instability and apoptosis are frequent in p53 deficient young mice. Oncogene 15: 1295-1302. PMID 9315097
42. Taylor, C., Jalava, A. and Mai, S. 1997. c-Myc dependent initiation of genomic instability during neoplastic transformation. Current Topics in Microbiol. Immunol. 224: 201-207. PMID 9308243
43. Luecke-Huhle, C., Mai, S., Moll, J. 1997. c-Myc overexpression facilitates radiation-induced DHFR gene amplification. Int. J. Radiat. Res. 71: 167-175.
44. Mai, S., Fluri, M., Siwarski, D., Huppi, K. 1996. Genomic instability in MycER activated Rat1A-MycER cells. Chromosome Research 4: 365-371. PMID 8871825
45. Mai, S., Hanley-Hyde, J., Fluri, M. 1996. c-Myc overexpression associated DHFR gene amplification in hamster, rat, mouse and human cell lines. Oncogene 12: 277-288. PMID 8570205
46. Siegel, J., Fritsche, M., Mai, S., Brandner, G., Hess, R.D. 1995. Enhanced p53 activity and accumulation in response to DNA damage. Oncogene 11: 1363-1370. PMID 7478558
47. Mai, S., Hanley-Hyde, J., Coleman, A., Siwarski, D., Huppi, K. 1995. Amplified extrachromosomal elements containing c-Myc and Pvt 1 in a mouse plasmacytoma. Genome 38:780-785. PMID 7672608

PubMed Listed Publications

Visiting scientists and students, 2002.

Dr. Chatchai Tayapiwatana, University of Chiang Mai, Chiang Mai, Thailand.
Virginie Mougey, University of Besançon, Besançon, France.
Dr. Thierry Fest, Univeristy of Besançon, Besançon ,France.
Dr. Francis Wiener, Karolinska Institute, Stockholm, Sweden.
Dr. Karin Greulich-Bode, German Cancer Research Center, Heidelberg, Germany.
Sharareh Moshir, German Cancer Research Center, Heidelberg, Germany.

Visiting scientists and students, 2003.

Sibylle Ermler, German Cancer Research Center, Heidelberg, Germany
Dr. Thierry Fest, Univeristy of Besançon, Besançon ,France.
Sharareh Moshir, German Cancer Research Center, Heidelberg, Germany
Mathilde Perrin, University of Besancon, Besacon France
Dr. Francis Wiener, Karolinska Institute, Stockholm Sweden
Colleen Fordyce, University of California San Francisco, USA
Hal Berman, University of California San Francisco, USA
Caroline Miller, University of California San Francisco, USA
Virginie Mougey, University of Besançon, France
Nutjeera Intasai, University of Chiang Mai, Thailand

Visiting scientists and students, 2004:

Iris Gehrke, University of Cologne, Germany
Nutjeera Intasai, University of Chiang Mai, Thailand
Andrea Caporali, University of Parma, Italy
Dr. Thierry Fest, University of Rennes, France
Bettina Gruhne, University of Tuebingen, Germany

Visiting scientists and students, 2005:

Amanda Gonçalves Da Silva, Unversity of Sao Paulo, Brazil
Andrea Caporali, University of Parma, Italy
Iris Gehrke, University of Cologne, Germany
Nutjeera Intasai, University of Chiang Mai, Thailand
Dr. Eva Darai, MTC, Karolinska Institute, Stockholm, Sweden
Dr. Maria Kost-Alimova, MTC, Karolinska Institute, Stockholm, Sweden
Johannes Kohlschuetter, University of Freiburg, Germany.
Dr. Liudmila P. Zhakharenko, Institute of Cytology and Genetics, Siberian Department of the Russian Academy of Science, Novosibirsk, Russia

Visiting scientists and students, 2006:

Dr. Anna Szeles, MTC, Karolinska Institute, Stockholm Sweden
Fabio Morato de Oliveira, University of Sao Paulo, Brazil
Dr. Hans Knecht, University of Sherbrooke, Quebec
Dr. Qing Li, South Bend Medical Foundation, South Bend , IN, USA
Amanda Gonçalves da Silva, University of Sao Paulo, Brazil
Filip Misev, University of Basel, Switzerland.