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Med Hypotheses, 71(1), 126–140

Defining the steps that lead to cancer: replicative telomere erosion,aneuploidy and an epigenetic maturation arrest of tissue stem cells.

Reinhard Stindl

Recently, an influential sequencing study found that more than 1700 genes had non-silent mutations in either a breast or colorectal cancer, out of just 11 breast and 11 colorectal tumor samples. This is not surprising given the fact that genomic instability is the hallmark of cancer cells. The plethora of genomic alterations found in every carcinoma does not obey the 'law of genotype-phenotype correlation', since the same histological subtype of cancer harbors different gene mutations and chromosomal aberrations in every patient. In an attempt to make sense out of the observed genetic and chromosomal chaos in cancer, I propose a cascade model. According to this model, tissue regeneration depends on the proliferation and serial activation of stem cells. Replicative telomere erosion limits the proliferative life span of adult stem cells and results in the Hayflick limit (M1). However, local tissue exhaustion or old age might promote the activation of M1-deficient tissue stem cells. Extended proliferation of these cells leads to telomere-driven chromosomal instability and aneuploidy (abnormal balance of chromosomes and/or chromosome material). Several of the aforementioned steps have been already described in the literature. However, in contrast to common theories, it is proposed here that the genomic damage blocks the epigenetic differentiation switch. As a result of aneuploidy, differentiation-specific genes cannot be activated by modification of methylation patterns. Consequently, the phenotype of cancer tissue is largely determined by the epigenetic maturation arrest of tissue stem cells, which in addition enables a fraction of cancer cells to proliferate, invade and metastasize, as normal adult stem cells do. The new model combines genetic and epigenetic alterations of cancer cells in one causative cascade and offers an explanation for why identical histologic cancer types harbor a confusing variety of chromosomal and gene aberrations. The Viennese Cascade, as presented here, may end the debate on if and how 'tumor-unspecific' aneuploidy leads to cancer.

Cytogenet. Genome Res., 121, 79- 87

Elevated chromosome translocation frequencies in New Zealand nuclear test veterans.

M.A. Wahab, E.M. Nickless, R. Najar-M'Kacher, C. Parmentier, J.V. Podd, R.E. Rowland

In 1957/58 the British Government conducted a series of nuclear tests in the mid-Pacific codenamed Operation Grapple, which involved several naval vessels from Britain and New Zealand. Two New Zealand frigates with 551 personnel onboard were stationed at various distances between 20 and 150 nautical miles from ground zero. In the present study we applied the cytomolecular technique mFISH (multicolour fluorescent in situ hybridisation) to investigate a potential link between chromosome abnormalities and possible past radiation exposure in New Zealand nuclear test veterans who participated in Operation Grapple. Compared to age matched controls, the veterans showed significantly higher (P < 0.0001) frequencies of chromosomal abnormalities (275 translocations and 12 dicentrics in 9,360 cells vs. 96 translocations and 1 dicentric in 9,548 cells in the controls), in addition to a significant excess of CCRs (complex chromosomal rearrangements) in the veterans. A Kolmogorov-Smirnoff test showed that the distributions of translocations for the two groups were significantly different.

Mod Pathol, 20(4), 467–473
April, 2007

A variant TMPRSS2 isoform and ERG fusion product in prostate cancerwith implications for molecular diagnosis.

Jacques Lapointe, Young H. Kim, Melinda A. Miller, Chunde Li, Gulsah Kaygusuz, van de Rijn, Matt, David G. Huntsman, James D. Brooks, Jonathan R. Pollack

<p>Prostate cancer is the most commonly diagnosed cancer among men in the United States. Recently, fusion of <em>TMPRSS2</em> with ETS family oncogenic transcription factors has been identified as a common molecular alteration in prostate cancer, where most often the rearrangement places <em>ERG</em> under the androgen-regulated transcriptional control of <em>TMPRSS2</em>. Here, we carried out rapid amplification of cDNA ends (RACE) on a prostate cancer specimen carrying an atypical aberration discovered by array-based comparative genomic hybridization (array CGH), suggesting an alternative fusion partner of <em>ERG</em>. We identified novel transcribed sequences fused to <em>ERG</em>, mapping 4 kb upstream of the <em>TMPRSS2</em> start site. The sequences derive from an apparent second <em>TMPRSS2</em> isoform, which we found also expressed in some prostate tumors, suggesting similar androgen-regulated control. In a reverse transcription-polymerase chain reaction (RT-PCR)-based survey of 63 prostate tumor specimens (54 primary and nine lymph node metastases), 44 (70%) cases expressed either the known or novel variant <em>TMPRSS2</em>-<em>ERG</em> fusion, 28 (44%) expressed both, 10 (16%) expressed only the known, and notably six (10%) expressed only the variant isoform fusion. In this specimen set, the presence of a <em>TMPRSS2</em>-<em>ERG</em> fusion showed no statistical association with tumor stage, Gleason grade or recurrence-free survival. Nonetheless, the discovery of a novel variant <em>TMPRSS2</em> isoform-<em>ERG</em> fusion adds to the characterization of ETS-family rearrangements in prostate cancer, and has important implications for the accurate molecular diagnosis of <em>TMPRSS2</em>-<em>ETS</em> fusions.</p>

EMBO J, 26(1), 102–112
January, 2007

An essential function of the extreme C-terminus of MDM2 can be providedby MDMX.

Stjepan Uldrijan, Willem-Jan Pannekoek, Karen H Vousden

MDM2 (HDM2) is a ubiquitin ligase that can target the p53 tumor suppressor protein for degradation. The RING domain is essential for the E3 activity of MDM2, and we show here that the extreme C-terminal tail of MDM2 is also critical for efficient E3 activity. Loss of E3 function in MDM2 mutants deleted of the C-terminal tail correlated with a failure of these mutants to oligomerize with MDM2, or with the related protein MDMX (HDMX). However, MDM2 containing point mutations within the C-terminus that inactivated E3 function retained the ability to oligomerize with the wild-type MDM2 RING domain and MDMX, and our results indicate that oligomers containing both wild-type MDM2 and a C-terminal mutant protein retain E3 function both in auto-degradation and degradation of p53. Interestingly, the E3 activity of C-terminal point mutants of MDM2 can also be supported by interaction with wild-type MDMX, suggesting that MDMX can directly contribute to E3 function.

Int J Cancer, 120, 2734- 2738

Chromosomal 20q gain in the DNA diploid component of aneuploid colorectal carcinomas.

P.M. De Angelis, T. Stokke, M. Beigi, G. Flatberg, M. Enger, K. Haug, H.C.D. Aass, A. Schj\olberg, P.A. Andresen, S. Ariansen, A.S. B\o, O. Mj\aaland, O.P. Clausen

The order of appearance of different genetic aberrations during the shift from diploidy/near-diploidy to aneuploidy in colorectal cancers is not yet clear. We studied genetic alterations in flow cytometrically-sorted DNA diploid and corresponding aneuploid epithelial cell populations from each of 20 colorectal tumors using comparative genomic hybridization, FISH, and PCR. Analysis of the 19 cases in which aberrations were found in the flow-sorted diploid population indicated that large-scale aneuploidization in colorectal cancer was preceded by amplification of oncogene(s) localized to chromosome 20q13.2 and by KRAS mutations, but not by TP53 deletions or losses of large chromosomal regions such as 4q, 8p and 18q.

Leukemia Research, 31, 39- 47

Analysis of complex chromosomal rearrangements in adult patients with MDS and AML by multicolor FISH.

L. Babicka, S. Ransdorfova, J. Brezinova, Z. Zemanova, L. Sindelarova, M. Siskova, J. Maaloufova, J. Cermak, K. Michalova

We analyzed complex chromosomal aberrations in 37 adult patients with myelodysplastic syndrome (MDS) and acute myeloid leukemia (AML) using classical cytogenetic method, FISH with locus-specific probes, multicolor FISH (mFISH) and multicolor banding (mBAND). Unbalanced structural aberrations, leading to a gain or loss of chromosomal material, were frequently observed in bone marrow cells. In 30 patients (81.1%) loss or rearrangement of chromosome 5, 7 and/or 11 was found. The most frequent numerical change was trisomy 8 as expected (detected in six patients-16.2%) and the most frequent breakpoints 5q13, 5q33, 7q31, 10p12, 11q23, 12p13, 17p11 and 21q22 were determined.

Cancer Genet Cytogenet, 173(1), 10-6

Structural aberrations of chromosome 7 revealed by a combination of molecular cytogenetic techniques in myeloid malignancies.

J Brezinová, Z Zemanová, S Ransdorfová, L Pavlistová, L Babická, L Housková, J Melichercíková, M Sisková, J Cermák, K Michalová

In bone marrow cells of 33 patients with myelodysplastic syndrome and acute myeloid leukemia, structural rearrangements of chromosome 7 were found with conventional G-banding: 8 with deletions 7q and 25 with translocations. In 29 of the patients, complex karyotypes were confirmed using multicolor fluorescence in situ hybridization (mFISH). Commercial probes (Abbot Molecular) were used for 7q22, 7q31, and 7q35, the regions most frequently deleted in myeloid malignancies. In three cases without deletions, high-resolution multicolor banding (mBAND) for chromosome 7 revealed other aberrations. Five groups of chromosomal rearrangements were established: (a) deletion 7q as a sole aberration (2 cases), (b) deletion 7q and complex karyotypes (6 cases), (c) combined translocations and deletions of 7q (17 cases), (d) combined translocation and deletion 7p (5 cases), and (e) translocation of chromosomes 7 without deletion 7p or 7q (3 cases). Deletions of all three FISH-screened regions were the most frequent, with heterogeneous breakpoints. The region 7p13.2 approximately p15.2 was most commonly deleted. Most of the deletions were cryptic, not detectable with conventional cytogenetics. Aberrations of chromosome 7 are associated with a very poor outcome; survival time in our cohort was short (median 7 months).

Cancer Genet Cytogenet., 175, 159- 165

Detailed characterization of 7q deletions by multicolor banding (mBAND) in marginal zone cell lymphoma.

S. Gazzo, I. Chudoba, A. Traverse-Glehen, L. Baseggio, P. Felman, F. Berger, G. Salles, S. Hayette, J.-P. Magaud, E. Callet-Bauchu

<p>High-resolution multicolor banding (mBAND) analysis was applied to precisely fine-map the genomic extent of 7q deletions in a series of 26 marginal zone lymphoma patients displaying the abnormality on conventional karyotypes. Using this approach, the breakpoints and the extent of deletions revealed by conventional banding techniques had to be re-defined in 70% of cases. Although no common minimal region of deletion was delineated, mBAND demonstrated the involvement of the 7q32 region in more than 90% of cases. In addition, unsuspected translocations and intrachromosomal changes could be identified in four cases. Taken together, these data demonstrate that mBAND represents an alternative cytogenetic tool in the comprehensive analysis of chromosome aberrations in hematologic malignancies, allowing rapid screening and precise delineation of structural rearrangements of a defined chromosome. This also confirms the localization in the vicinity of band 7q32 of putative candidate gene(s) involved in the pathogenic development of the disease.</p>

Cancer Res, 67, 3010- 3017

Hyperthermia activates a subset of Ataxia-telangiectasia mutated effectors independent of DNA strand breaks and heat shock protein 70 status.

C.B. Hunt, R.K. Pandita, A. Laszlo, R. Higashikubo, M. Agarwal, T. Kitamura, A. Gupta, N. Rief, N. Horikoshi, R. Baskaran, J.-H. Lee, M. Löbrich, T.T. Paull, J.L. Roti Roti, T.K. Pandita

All cells have intricately coupled sensing and signaling mechanisms that regulate the cellular outcome following exposure to genotoxic agents such as ionizing radiation (IR). In the IR-induced signaling pathway, specific protein events, such as ataxia-telangiectasia mutated protein (ATM) activation and histone H2AX phosphorylation (gamma-H2AX), are mechanistically well characterized. How these mechanisms can be altered, especially by clinically relevant agents, is not clear. Here we show that hyperthermia, an effective radiosensitizer, can induce several steps associated with IR signaling in cells. Hyperthermia induces gamma-H2AX foci formation similar to foci formed in response to IR exposure, and heat-induced gamma-H2AX foci formation is dependent on ATM but independent of heat shock protein 70 expression. Hyperthermia also enhanced ATM kinase activity and increased cellular ATM autophosphorylation. The hyperthermia-induced increase in ATM phosphorylation was independent of Mre11 function. Similar to IR, hyperthermia also induced MDC1 foci formation; however, it did not induce all of the characteristic signals associated with irradiation because formation of 53BP1 and SMC1 foci was not observed in heated cells but occurred in irradiated cells. Additionally, induction of chromosomal DNA strand breaks was observed in IR-exposed but not in heated cells. These results indicate that hyperthermia activates signaling pathways that overlap with those activated by IR-induced DNA damage. Moreover, prior activation of ATM or other components of the IR-induced signaling pathway by heat may interfere with the normal IR-induced signaling required for chromosomal DNA double-strand break repair, thus resulting in increased cellular radiosensitivity.

Chromosome Res., 15, 327- 339

A new platform linking chromosomal and sequence information.

A. Kowalska, E. Bozsaky, T. Ramsauer, D. Rieder, G. Bindea, T. Lörch, Z. Trajanosky, P.F. Ambros

We have tested whether a direct correlation of sequence information and staining properties of chromosomes is possible and whether this combined information can be used to precisely map any position on the chromosome. Despite huge differences of compaction between the naked DNA and the DNA packed in chromosomes we found a striking correlation when visualizing the GGCC density on both levels. Software was developed that allows one to superimpose chromosomal fluorescence intensity profiles generated by chromolysin A3 (CMA3) staining with GGCC density extracted from the Ensembl database. Thus, any position along the chromosome can be defined in megabase pairs (Mb) besides the cytoband information, enabling direct alignment of chromosomal information with the sequence data. The mapping tool was validated using 13 different BAC clones, resulting in a mean difference from Ensembl data of 2 Mb (ranging from 0.79 to 3.57 Mb). Our results indicate that the sequence density information and information gained with sequence-specific fluorochromes are superimposable. Thus, the visualized GGCC motif density along the chromosome (sequence bands) provides a unique platform for comparing different types of genomic information.

J Bras Pneumol, 33(4), 487-91

Fatal outcome in bronchus-associated lymphoid tissue lymphoma

RL Mattedi, C Bernardi Fdel, CE Bacchi, SA Siqueira, T Mauad

Primary pulmonary lymphoma is rare. The most common histological type is the bronchus-associated lymphoid tissue lymphoma. This type of lymphoma has an indolent course and excellent response to therapy. One-third of all cases are diagnosed incidentally. However, due to the rarity of this disease, little is known about its natural history in terms of dissemination and evolution. Herein, we report the unusual case of a 61-year-old man who refused treatment after being diagnosed with bronchus-associated lymphoid tissue lymphoma and died 2 years later from massive lung infiltration without dissemination to other organs.

Nature, 448, 595- 599

Distinct classes of chromosomal rearrangements create oncogenic ETS gene fusions in prostate cancer.

S.A. Tomlins, B. Laxman, S.M. Dhanasekaran, B.E. Helgeson, X. Cao, D.S. Morris, A. Menon, X. Jing, Q. Ciao, B. Han, J. Yu, L. Wang, J.E. Montie, M.A. Rubin, K.J. Pienta, D. Roulston, R.B. Shah, S. Varambally, R. Mehra, A.M. Chinnaiyan

Recently, we identified recurrent gene fusions involving the 5' untranslated region of the androgen-regulated gene TMPRSS2 and the ETS (E26 transformation-specific) family genes ERG, ETV1 or ETV4 in most prostate cancers. Whereas TMPRSS2-ERG fusions are predominant, fewer TMPRSS2-ETV1 cases have been identified than expected on the basis of the frequency of high (outlier) expression of ETV1 (refs 3-13). Here we explore the mechanism of ETV1 outlier expression in human prostate tumours and prostate cancer cell lines. We identified previously unknown 5' fusion partners in prostate tumours with ETV1 outlier expression, including untranslated regions from a prostate-specific androgen-induced gene (SLC45A3) and an endogenous retroviral element (HERV-K_22q11.23), a prostate-specific androgen-repressed gene (C15orf21), and a strongly expressed housekeeping gene (HNRPA2B1). To study aberrant activation of ETV1, we identified two prostate cancer cell lines, LNCaP and MDA-PCa 2B, that had ETV1 outlier expression. Through distinct mechanisms, the entire ETV1 locus (7p21) is rearranged to a 1.5-megabase prostate-specific region at 14q13.3-14q21.1 in both LNCaP cells (cryptic insertion) and MDA-PCa 2B cells (balanced translocation). Because the common factor of these rearrangements is aberrant ETV1 overexpression, we recapitulated this event in vitro and in vivo, demonstrating that ETV1 overexpression in benign prostate cells and in the mouse prostate confers neoplastic phenotypes. Identification of distinct classes of ETS gene rearrangements demonstrates that dormant oncogenes can be activated in prostate cancer by juxtaposition to tissue-specific or ubiquitously active genomic loci. Subversion of active genomic regulatory elements may serve as a more generalized mechanism for carcinoma development. Furthermore, the identification of androgen-repressed and insensitive 5' fusion partners may have implications for the anti-androgen treatment of advanced prostate cancer.

Cancer Genet Cytogenet, 173(1), 10-6

Structural aberrations of chromosome 7 revealed by a combination of molecular cytogenetic techniques in myeloid malignancies

J Brezinov{\'a}, Z Zemanov{\'a}, S Ransdorfov{\'a}, L Pavlistov{\'a}, L Babick{\'a}, L Houskov{\'a}, J Melicherc{\'i}kov{\'a}, M Siskov{\'a}, J Cerm{\'a}k, K Michalov{\'a}

In bone marrow cells of 33 patients with myelodysplastic syndrome and acute myeloid leukemia, structural rearrangements of chromosome 7 were found with conventional G-banding: 8 with deletions 7q and 25 with translocations. In 29 of the patients, complex karyotypes were confirmed using multicolor fluorescence in situ hybridization (mFISH). Commercial probes (Abbot Molecular) were used for 7q22, 7q31, and 7q35, the regions most frequently deleted in myeloid malignancies. In three cases without deletions, high-resolution multicolor banding (mBAND) for chromosome 7 revealed other aberrations. Five groups of chromosomal rearrangements were established: (a) deletion 7q as a sole aberration (2 cases), (b) deletion 7q and complex karyotypes (6 cases), (c) combined translocations and deletions of 7q (17 cases), (d) combined translocation and deletion 7p (5 cases), and (e) translocation of chromosomes 7 without deletion 7p or 7q (3 cases). Deletions of all three FISH-screened regions were the most frequent, with heterogeneous breakpoints. The region 7p13.2 approximately p15.2 was most commonly deleted. Most of the deletions were cryptic, not detectable with conventional cytogenetics. Aberrations of chromosome 7 are associated with a very poor outcome; survival time in our cohort was short (median 7 months).

Modern Pathology, 19, 648- 658

Genetic profiling of stage I and II colorectal cancer may predict metastatic relapse.

F. Al-Mulla, A.I. Behbehani, M.S. Bitar, G. Varadharaj, J.J. Going

A substantial number of patients with early-stage colorectal cancer relapse from metastatic disease. Identification of these patients by genetic profiling of their primary tumours may allow more informed follow-up and tailored administration of adjuvant therapy. Primary tumours from 70 patients with early-stage and largely microsatellite-stable colorectal cancer were profiled using metaphase-based comparative genomic hybridization (CGH) and the aberrations confirmed independently in a subset of patients using microarray-based CGH. Of the 70 cancers, 61 were amenable to CGH, and follow-up data was available from 56 patients. Genomic aberrations were correlated with patients' survival using univariate, multivariate and Kaplan-Meier survival curves. Metastatic primary tumours exhibited more complex genomic aberrations than non-metastatic primary tumours. Loss of chromosome 4p was an independent prognostic factor in early-stage colorectal cancer using multivariate analysis (Hazard ratio, 9.6; 95% CI, 3.3-28; P = 0.0001). Loss of both chromosome arms 8p and 18q had a statistically significant negative effect on disease-free survival. Moreover, primary tumours with loss of both chromosomes 4 and 14q bestowed poorer prognosis than tumours with loss of any one of the two chromosomes (P<0.0001). Genetic profiling of primary tumours of patients with early-stage colorectal cancer is of significant value in identifying the subset of patients who may relapse with metastatic disease. Accordingly, the molecular genetic features of primary tumours should be considered in the mainstream management of patients with this specific stage of the disease.

Nature, 442, 466- 470

ATM stabilizes DNA double-strand-break complexes during V(D)J recombination.

A.L. Bredemeyer, G.G. Sharma, C.-Y. Huang, B.A. Helmink, L.M. Walker, K.C. Khor, B. Nuskey, K.E. Sullivan, T.K. Pandita, C.H. Bassing, B.P. Sleckman

The ATM (ataxia-telangiectasia mutated) protein kinase mediates early cellular responses to DNA double-strand breaks (DSBs) generated during metabolic processes or by DNA-damaging agents. ATM deficiency leads to ataxia-telangiectasia, a disease marked by lymphopenia, genomic instability and an increased predisposition to lymphoid malignancies with chromosomal translocations involving lymphocyte antigen receptor loci5, 6. ATM activates cell-cycle checkpoints and can induce apoptosis in response to DNA DSBs. However, defects in these pathways of the DNA damage response cannot fully account for the phenotypes of ATM deficiency. Here, we show that ATM also functions directly in the repair of chromosomal DNA DSBs by maintaining DNA ends in repair complexes generated during lymphocyte antigen receptor gene assembly. When coupled with the cell-cycle checkpoint and pro-apoptotic activities of ATM, these findings provide a molecular explanation for the increase in lymphoid tumours with translocations involving antigen receptor loci associated with ataxia-telangiectasia.

J Invest Dermatol, 126, 2308- 2315

Are keratoacanthomas variants of squamous cell carcinomas? A comparison of chromosomal aberrations by comparative genomic hybridization.

O.P.F. Clausen, H.C.D. Aass, M. Beigi, K.J. Purdie, C.M. Proby, V.L. Brown, M. Mattingsdahl, F. Micci, S. K\olvraa, L. Bolund, P.M. De Angelis

Keratoacanthoma (KA) is a benign keratinocytic neoplasm that usually presents as a solitary nodule on sunexposed areas, develops within 6-8 weeks and spontaneously regresses after 3-6 months. KAs share features such as infiltration and cytological atypia with squamous cell carcinomas (SCCs). Furthermore, there are reports of KAs that have metastasized, invoking the question of whether or not KA is a variant of SCC. To date no reported criteria are sensitive enough to discriminate reliably between KA and SCC, and consequently there is a clinical need for discriminating markers. We screened fresh frozen material from 132 KAs and 37 SCCs for gross chromosomal aberrations by using comparative genomic hybridization (CGH). Forty-nine KAs (37.1%) and 31 SCCs (83.7%) showed genomic aberrations, indicating a higher degree of chromosomal instability in SCCs. Gains of chromosomal material from 1p, 14q, 16q, 20q, and losses from 4p were seen significantly more frequently in SCCs compared with KAs (P-values 0.0033, 0.0198, 0.0301, 0.0017, and 0.0070), whereas loss from 9p was seen significantly more frequently in KAs (P-value 0.0434). The patterns of recurrent aberrations were also different in the two types of neoplasms, pointing to different genetic mechanisms involved in their developments.

Int J Med Sci, 3, 124- 129

Low temperature tolerance of human embryonic stem cells.

B.C. Heng, K.J. Vinoth, H. Liu, M.P. Hande, T. Cao

This study investigated the effects of exposing human embryonic stem cells (hESC) to 4oC and 25oC for extended durations of 24h and 48h respectively. Cell survivability after low temperature exposure was assessed through the MTT assay. The results showed that hESC survivability after exposure to 25oC and 4oC for 24h was 77.3 ± 4.8 % and 64.4 ± 4.4 % respectively (significantly different, P < 0.05). The corresponding survival rates after 48h exposure to 25oC and 4oC was 71.0 ± 0.5 % and 69.0 ± 2.3 % respectively (not significantly different, P > 0.05). Spontaneous differentiation of hESC after low temperature exposure was assessed by morphological observations under bright-field and phase-contrast microscopy, and by immunocytochemical staining for the pluripotency markers SSEA-3 and TRA-1-81. hESC colonies were assigned into 3 grades according to their degree of spontaneous differentiation: (1) Grade A which was completely or mostly undifferentiated, (2) Grade B which was partially differentiated, and (3) Grade C which was mostly differentiated. In all low temperature exposed groups, about 95% of colonies remain undifferentiated (Grade A), which was not significantly different (P > 0.05) from the unexposed control group maintained at 37oC. Additionally, normal karyotype was maintained in all low temperature-exposed groups, as assessed by fluorescence in situ hybridization (FISH) of metaphase spreads with telomere and centromere-specific PNA probes. Further analysis with m-FISH showed that chromosomal translocations were absent in all experimental groups. Hence, hESC possess relatively high-tolerance to extended durations of low temperature exposure, which could have useful implications for the salvage of hESC culture during infrequent occurrences of incubator break-down and power failure.

Int. J. Molecular Medicine, 17, 209- 213

Molecular cytogenetic characterization of the mouse cell line WMP2 by spectral karyotyping and multicolor banding applying murine probes.

C. Karst, V. Trifonov, S.A. Romanenko, U. Claussen, K. Mrasek, S. Michel, P. Avner, T. Liehr

The Moloney murine leukemia virus-transformed suspension cell line WMP2 is derived from wild mice (Mus musculus) of the WMP/WMP strain. These mice carry nine pairs of metacentric Robertsonian translocation chromosomes. As the chromosomes of the wild-type mouse are all acrocentric, metaphase spreads of the WMP2 cells seam to be highly suited for physical gene mapping. Here we studied the WMP2 line using spectral karyotyping (SKY) combined with new established mouse specific multicolor banding (mcb) probes for the chromosomes X, 3, 4, 6 and 18. SKY revealed that the WMP2 cell line developed further four derivative chromosomes. After application of mcb five previously unrecognizable intrachromosomal rearrangements with 9 breakpoints were detected for the studied chromosomes.

Cytogenet. Genome Res., 112, 194- 201

Sex-specific telomere length profiles and age-dependent erosion dynamics of individual chromosome arms in humans.

S. Mayer, S. Brüderlein, S. Perner, I. Waibel, A. Holdenried, N. Ciloglu, C. Hasel, T. Mattfeldt, K.V. Nielsen, P. Möller

During aging, telomeres are gradually shortened, eventually leading to cellular senescence. By T/C-FISH (telomere/centromere-FISH), we investigated human telomere length differences on single chromosome arms of 205 individuals in different age groups and sexes. For all chromosome arms, we found a linear correlation between telomere length and donor age. Generally, males had shorter telomeres and higher attrition rates. Every chromosome arm had its individual age-specific telomere length and erosion pattern, resulting in an unexpected heterogeneity in chromosome-specific regression lines. This differential erosion pattern, however, does not seem to be accidental, since we found a correlation between average telomere length of single chromosome arms in newborns and their annual attrition rate. Apart from the above-mentioned sex-specific discrepancies, chromosome arm-specific telomere lengths were strikingly similar in men and women. This implies a mechanism that arm specifically regulates the telomere length independent of gender, thus leading to interchromosomal telomere variations.

Am J Surg Pathol, 30, 828- 837

Fluorescence in situ hybridization (FISH) on touch preparations: a reliable method for detecting loss of heterozygosity at 1p and 19q in oligodendroglial tumors.

D. Scheie, P. A. Andresen, M. Cvancarova, A. S. B\o, E. helseth, K. Skullerud, K. Beiske

Combined loss of heterozygosity (LOH) on 1p and 19q is reported in 50% to 90% of oligodendroglial tumors and has emerged as a strong and favorable prognostic factor. Fluorescence in situ hybridization (FISH) and polymerase chain reaction (PCR) are the most widely used techniques. The aim of this study was to evaluate the reliability of FISH to predict LOH at 1p and 19q when performed on touch preparations from 40 oligodendroglial tumors, even if the majority of the nuclei showed chromosomal imbalance. PCR was used as the gold standard. The presence of none or one target signal was reported as FISH-LOH, whereas all other losses were defined as FISH-imbalance. The sum of nuclei with FISH-LOH and imbalance was calculated in each case (FISH-sum) and cut-off values were defined as the mean FISH-sum value in controls plus 3 standard deviations; 27.7% for 1p and 33.2% for 19q. These corresponded well with the optimal cut-off values for our data, calculated using the minimum error rate classification procedure (35.6% for 1p and 33.1% for 19q). Concurrent FISH and PCR results were encountered in 95% for 1p and 87.5% for 19q. FISH-sum was the best and simplest discriminating variable for correct classification of LOH status. Under these conditions, even a dominant population of nuclei showing FISH-imbalance represented an LOH status in the tumor cells. FISH on touch preparations is a quick and reliable method for 1p/19q testing, does not require normal DNA and can be easily performed in an immunohistochemistry unit.