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Abnormalities of chromosomes 12p13 and 15q26-QTER in congenital fibrosarcoma

Abstracts ABNORMAL NUMBER OF CENTROSOMES AND DEVELOPMENT OF ANEUPLOIDY AND NUCLEAR PLEOMORPHISM IN BREAST TUMOR CELLS Y Ousev, J Sarople, WC Deeley, Department of Surgery, Johns Hopkins University, Baltimore, MD Recently published data (Fukasawa et al., 1996) suggests that abnormal number of centrosomes produces loss of mitotic fidelity via chromosome segregation errors and facilitates development of chromosomal instability in mouse embryonic fibroblasts lacking p53. We have used monoclonal antibodies against microtubule-associated protein MAPIB (MAP5) (Domingues et al., 1994) for detection of number of centrosomes in MCA-11 cells and feulgen stain in order to measure amount of DNA and nuclear morphology features. Double stained MCA-11 cells were analyzed using CAS 200 image analysis system with dual wavelengths. Results: Number of centrosomes per cell in more than 200 cells was determined by light microscopy. Near 75 percent of MCA-I 1 interphase calls contained more ma2 ceatrosomes in a range from 3 to 7 per cell. HS-578 human breast cell line was used as a normal control. Only 1 or 2 ceatrosomes per cell was detected for this diploid cell line. Approximately 75 percent of HS-578 cells had I centrosome and 25 percent had 2 centrosomes. This was in agreement with proportion of cells in GI-S and G2-M detected by image cytometry. For MCA-11 cell line we detected positive correlation of ceatrosome number with DNA content. Using standard karyotyping technique we have also detected high variation of chromosome number in MCA- 11 cells with modal value of 58 chromosomes per cells and range from 25 to 110 per cell. We detected an aneuploid peak of DNA content (DNA Index of 1.25) and high degree of nuclear pleomorphism in this cell line. On a contrast Hs-578 cells had DNA and chromosome number in a near-diploid range. These observations indicate correlation of multiple copies of centrosomes in cultured breast cancer cells with aneuploidy and possible connection between centrosome amplification and chromosomal instability. Experimental distribution of centrosome number was subjected to additional analysis using a mathematical model of loss of mitotic fidelity via segregation errors. Computer simulation suggests that abnormal distribution of centrosome number could be a result of centrosome segregation errors and cannot be explained in terms of centrosome amplification alone. I D E N T I F I C A T I O N O F T W O D I S T I N C T R E G I O N S O N l p 3 6 I N V O L V E D IN MERKEL CELL CARCINOMA M Van Gcle. N Van Roy, ML Geerts, J Lambert, JM Naeyaert,, L Messiaen, J Vandcsompele, L Maertens, F Speleman, From the Departments of Medical Genetics (MVG,NVR,LM,JV, LcM,FS), Dermatology (MLG, JL, JMN,), University Hospital, Ghent, Belgium Merkel cell carcinoma (MCC) is a rare tumor of neuro-endocrine origin, mostly occuring in elderly individuals. Only limited genetic data are presently available. Deletions and unbalanced translocations resulting in loss of the distal part of the short arm of chromosome 1 were observed as a recurrent change. LOH-studies also revealed frequent loss of the 3p1321.1 region. We describe the cytogenefic and molecular analysis of chromosome I abormalities in a primary MCC and a MCC cell line. In the primary MCC, a tier (1) t(1 ;1) (p36; q12) was observed as the only cytogenetic change. FISH analysis with region specific probes showed loss for CEB15, CDC2L1 (p58) and D I Z 2 which are located in lp36.33. PND (1p36.2336.31) and proximally located markers were retained. L O H was observed for locus D I S 2 4 3 . Other markers more proximal to D1S243 were either beterozygous or uninformative. In the MCC cell line an insertion of a chromosome segment not derived from chromosome 1 was found in lp36. Both FISH-analysis with region specific probes and LOH-analysis did not reveal loss o f lp material. The insertion breakpoint was located proximal to PND (lp36.2336.31) and distal to A 1 2 M 2 (lp36.13-36.2). Based upon previous mapping data this corresponds to a position between D I S 2 1 4 and D1S170 on the genetic map. Our data suggest involvement of two distinct regions within chromosome band lp36 in MCC. This observation is reminiscent to neuroblastoma for which several putative tumor suppressor loci on the short arm of chromosome 1 have been proposed. One particular locus was mapped distal to PND in a region which overlaps with the distal l p deletion in the primary MCC. The insertion breakpoint in the MCC cell line could correspond to the constitutional lp-translocation breakpoint which we reported in a neuroblastoma patient.We are currently analyzing the position of the insertion breakpoint with respect to the tRNAsnRNA gone cluster within which the constitutional neuroblastoma Ip-breakpoint was mapped. As both MCC and neuroblastoma are tumors of neuro-eetodermal origin, it is tempting to assume that similar genes located on l p 3 6 are involved in the differentiation of these cells which when deregulated or lost result in tumor formation. USE OF A CHROMOSOME SPECIFIC PROBE (10Q22) T O D E T E C T A T U M O R SUPPRESSOR LOCUS, IN FAMILIAL JUVENILE POLYPOSIS. R Jacobv, S Schlack, C Cole, D Marshall, G Kuhlman, M Skarbek, C Hams, F Meisner, Cytogenetics section, State Laboratory of Hygiene, University of Wisconsin. Madison, WI 53706 A cytogenetic deletion was detected in a patient with juvenile polyposis (JPC), suggesting that this could be the site of a tumor suppressor locus. This was later supported by detection of somatic deletions of 10q22 in 39/47 (83 percent) of juvenile polyps from 16 unrelated patients with either hereditary or sporadic juvenile polyps. Mapping the minimum overlap of the germline and somatic deletions localized JPC to the 3cM interval DIOS219-DIOSI696. Comparison of the mapped deletions to commercially available probes for fluorescent in situ hybridization (FISH) suggested a specific cosrnid probe from ONCOR, Inc. which spanned a sufficient distance of the suspected region to enable identification of deletions in most cases. Sequential slides were probed with both the 10q22 probe and with a similar sized control probe (ONCOR's 21q22.3) probe. In all deleted cases, the 10q22 probe was found to average 1.7-1.8 signals per cell in glandular epithelium while the lamina propia averaged 1.3-1.5 per cell. The control probe, 21q22.3 gave consistent averages for both glandular epithelium and larmna propia layer in the 1.7-l.8 range. Although they are possible precursors to adenomas and adenocarcinoma of the colonic epithelium, the mutated cells in juvenile polyposis were shown by FISH to reside exclusively in the lamina propia. Further trials with this probe may support its use for the clinical diagnosis of familial juvenile polyposis call. ABNORMALITIES CHROMOSOMES 12p13 AND 15q26-QTER IN OF CONGENITAL FIBROSARCOMA SR Knezevich, S Maani, and PHB Sorensen Department of Pathology, BC's Children's Hospital, Vancouver, BC, Canada. Congenital fihrosarcoma (CFS) is a cellular, mitotically active neoplasm of the soft tissues affecting primarily infants less than one year of age. This tumor has a metastatic rate of up to 10% and a high propensity for local recurrence. The predominant controversy surrounding CFS is its distinction from infantile fihromatosis (IFB), which is a benign condition that behaves less aggressively than CFS. IFB is characterized by the proliferation of normal-appearing fihroblasts in the soft tissue of infants and young children but its morphologic appearance may be virtually indistinguishable from that of CFS. Clearly, alternative molecular methodologies would be useful to reliably differentiate CFS from IFB. Very little data is currently available regarding karyotypic alterations in CFS, with the most consistent findings being numerical abnormalities of chromosomes 8, 11, t7, and/or 20. Further genetic and molecular cytogenetic studies of CFS and related tumours are therefore warranted. We have performed cytogenetic analysis of three cases of CFS. Two of the three turnouts showed cytogenetic alterations of chromosome 12pl 3 as well as evidence of rearrangements involving chromosome 15q26-qter. One of the two latter cases also showed additional material at lq44. To further study these abnormalities, we have performed dual colour FISH experiments of a CFS case using yeast artificial chromosome (YAC) probes from 12p13 and 15q26-qter, a-centromeric probes for chromosomes 1, 12, and 15, and a cosmid probe for lq44. These studies demonstrated a complex t(l;12;15)(q44;p13;q26-qter) transhication in this case. Similar analysis of 3 cases of IFB did not reveal rearrangements of chromosomes 12 or 15. We are currently screening other CFS eases to determine if a specific translocation involving these regions characterizes CFS. It is hoped that our findings will lead to a reliable genetic marker for CFS that will allow its distinction from morphologically similar IFB. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Cancer Genetics and Cytogenetics Elsevier

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