Endoreduplication and telomeric association in a choroid plexus carcinoma

Endoreduplication and telomeric association in a choroid plexus carcinoma

ELSEVIER Endoreduplication and Telomeric Association in a Choroid Plexus Carcinoma You S. Li, Yao-Shan Fan, and Ross E Armstrong ABSTRACT: Cytogenet...

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ELSEVIER

Endoreduplication and Telomeric Association in a Choroid Plexus Carcinoma You S. Li, Yao-Shan Fan, and Ross E Armstrong

ABSTRACT: Cytogenetic studies showed a hyperhaploid stemline, (32,XY,+1,+7,+9,+12,+13,+14, + 19, + 20) in a patient with choroid plexus carcinoma. Endoreduplication and doubling of the stemline to 200-400 chromosomes per cell and variation in numerical changes were also noted. Telomeric association was present in most cells. The 12p and 20q were by far the most frequently involved chromosome arms. Telomeric association is believed to have triggered further structural changes in this case since the 1213 and 20q were always involved in the f e w structural abnormalities identified. A review of the literature ,~mggests that hyperhaploidy may characterize choroid plexus carcinoma and hyperdiploidy choroid plexus papilloma.

INTRODUCTION Choroid plexus tumors are rare and most often occur in early childhood. As many as 30% of choroid plexus tumors are carcinomas; the rest are benign papillomas. Family cases have been reported, and autosomal recessive inheritance was suggested [1]. Only a few choroid plexus tumors have been karyotyped [2]: hyperhaploidy with 3335 chromosomes was detected in some cases and hyperdiploidy with 52-58 chromosomes was detected in others [2-7]. We n o w report a choroid plexus carcinoma in which endoreduplication and doubling of a hyperhaploid stemline to 200-400 chromosomes per cell were observed. Variation of numerical changes from cell to cell and telomeric association were also noted. MATERIALS AND METHODS A fresh tumor sample, obtained directly from the operating room, was minced with scissors in a Petri dish and disaggregated for a few hours in 0.1% collagenase (Sigma). Approximately 1 0 6 cells/ml were grown in F10 m e d i u m (GIBCO) supplemented[ with 15% fetal bovine serum in a tightly capped T30 flask. Cultures were harvested three times from 2 to 12 days. Colcemid was added 4-5 h before harvest. The tumor cells grew well, and no obvious difference was noted in preparations from the three harvests. All metaphase cells were examined but only cells of high quality were fully analyzed. From the Department of Pathology, Victoria Hospital, London, Ontario, Canada. Address reprint requeats to: Y S. Li, Ph.D., Cytogenetics Laboratory, Department of Pclthology, Victoria Hospital, Box 5375, London, Ontario N6A 4G5, Canada. Received March 20, 1995; accepted August 15, 1995. Cancer Genet Cytogenet87:7-10 (1996) © Elsevier Science Inc., 1996 655 Avenueof the Americas, New York,NY 10010

The patient was an 18-month-old boy. The pathologic diagnosis was choroid plexus carcinoma.

Cytogenetic Findings The karyotype was as follows: 32,XY,+1,+7,+9,+12,+13, +14,+ 19,+ 2017]/31-33,XY,+Y[1],+ 118],+ 717],+813],+916], +1218],+ 1211],+ 1313],+ 1416],+1511],-1711],-1711],+1811], -1811],+ 1911],+2017],+2013],+2012],+2211],+mar[3],+mar [2], +ace[2] [cp8]*/56-63,XY+X,+1,+l,+7,+7,+9,+12,+12, +13,+ 14,+19,+20,+20,+0-3mar with variation [cp12]/110123, inc [cp 5]**/200-400, inc [cp 3]**/37-45, inc[cp 4]**(* variations in the hyperhaploid line; ** cell clones are overrepresented in numbers). The doubling of the hyperhaploid line, 56-63 chromosomes per cell, was apparently unstable, with a tendency to lose chromosomes. Some of the cells would be classified as hypotriploid according to the International System of Human Cytogenetic Nomenclature [8]. To avoid confusion in this report, we refer to the clones with 49-63 chromosomes as hyperdiploid and to cells with 31-35 chromosomes as hyperhaploid. In our patient, ~ 1 5 % of all metaphase cells were in endoreduplication, with 4 of the 15 hyperhaploid cells and 2 of 12 hyperdiploid cells in endoreduplication (Fig. 1}. Consistent with endoreduplication, the size of interphase cells varied greatly from microcells to gigantic cells. Table 1 shows the extra chromosomes in reported choroid plexus tumors and in the present case. Extra copies of chromosomes 7, 12, and 20 were most consistent. Case 7 (Table 1) deserves special consideration. The majority of cells analyzed had a normal karyotype; the remaining cells (9 of 24) were hyperdiploid. Histopathologic analysis showed that some areas were carcinomatous and other areas resembled a papilloma, showing more regularly arranged and less atypical cells with a central vascularized stroma

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8

Y . S . Li et al.

4

5

11

12

11 16

19

20

Figure I

21

Modal numbers

Case

Reference

t 2 3

[3] [4] [2]

and extra chromosomes

Chromosome no. 34-35 33 56 58

18

radii

2 2

x

Y

A k a r y o t y p e from a h y p e r h a p l o i d cell of t h e s t e m l i n e in e n d o r e d u p l i c a t i o n .

Telomeric fusion was apparent in many cells, and the involved chromosomes behaved like dicentric chromosomes. Unidentified markers were common,but occurred in a low percentage of cells. They appeared to be products of telomeric association or fusion, since the telomeric regions of 12p and 20q were always involved in a few identified chromosomearrangements. Figure 2 shows a hyperdiploid karyotype with a tricentric marker: tri(20;?;12) (q13;?;p15). This tricentric marker was observed in ,'~10% of cells examined and in both hyperhaploid and hyperdip]oid cells. Figure 3 shows missing bands in some dicentric chromosomes involvingchromosomearms:12p and 20q.

and few mitoses. Therefore, whether the hyperdiploid celks w e r e f r o m p a p i l l o m a t o u s areas or carcinomatous a r e a s is u n c e r t a i n . I n t h e r e m a i n i n g t u m o r s ( c a s e s 1 - 6 i n T a b l e 1), a l l t h r e e c a s e s o f h y p e r h a p l o i d y including the present case were carcinomas whereas all three hyperdiploid cases were papillomas. I n o u r p a t i e n t , 23 o f 33 ( 7 0 % ) c e l l s s h o w e d 4 4 t e l o meric associations or fusions. The 20q and 12p were by far the most frequently involved chromosome arms; they w e r e i n v o l v e d 25 a n d 17 t i m e s , r e s p e c t i v e l y . T h e n e x t frequently involved arms were 13p and 14p (seven times each).

Tab]~e I

17

1

2

3

4

5

+ + +

in seven choroid plexus tumors

6

7

8

9

+

+ + + +

+ + + +

+

+

+

11

12

+

+ + ++ ++

+ +

4

['5]

55

++

5 6

[6] Present study

52-55 31-33 56--63

+ ++

++ + ++

+ +

7

[7]

49-59

++

+

+

+

10

+

13

14

15 16 17

18

+ + + +

++

+

++ + ++

+ + +

+ + ++

+

+ +

+ ++

+

+

19

20

21

22

XY

+

+ + + +

+ +

+

XY XX XXY XXY

+

+

XY

+

XX XY XXY XX

+ +

+ + ++ ++

Each plus sign represents one extra chromosome. Cases 1, 2, and 6 were choroid plexus carcinomas and cases 3, 4, and 5 were papillomas. Case 7 was carcinoma with areas that resembled papilloma; most cells analyzed had a normal karyotype.

Chromosomes in Choroid Plexus Tumors

9

li 4

5

i 16

17

20

2]

22

18

17

Y

Figure 2 A karyotype from a hyperdiploid cell showing the duplication of a tricentric marker chromosome, which is the result of rearrangements involving the telomeric regions of 12p and 20q. DISCUSSION

Polyploidization is common in brain tumors. Many mechanisms lead to polyploidization, such as endomitosis, restitution, cell fusion. Endoreduplication is considered the mechanism for polyploidization in our patient, because a substantial proportion of cells was in endoreduplication. The patient reported by Petersen et al. [3] had only one abnormal clone with 34-35 chromosomes, but flow cytometric DNA measurement revealed a minor cell line which was doubled in DNA content and missed by cytogeFigure 3 Examples of te]omeric association or fusion illustrating missing material in the regions next to telomeres. (A) Telomeric association or fusion between the long arms of chromosomes 20. Partial deletion of 20q was evident. (B) Telomeric fusion of 13p and 20q with deletion of 20% (C) Telomeric fusions involving 12p with missing bands next to the fusion area.

netic studies. Endoreduplication is the most common mode of polyploidization in differentiated tissues [9]. Endoreduplication also may be common in cancer, but has rarely been reported. In endoreduplication, chromosomes duplicate two or more times between mitoses instead of once as in normal mitosis. All the endoreduplications observed in our study contained only four chromatids, i.e., chromosomes duplicated only twice. The polyploidization to 200-400 chromosomes per cell in our patient must have been achieved by several endoreduplications with normal mitoses between two consecutive endoreduplications. As a result of endoreduplication, the hyperdiploid cell clone derived from the hyperhaploid clone and not the reverse; i.e., the hyperhaploid clone was the stemline, Therefore, many chromosomes were isodisomic in the hyperdiploid cells. About 1-3% of acute lymphoblastic leukemia (ALL) cases are near-haploid with 24-35 chromosomes and 15% are hyperdiploid with 50-65 chromosomes [10]. There are many similarities between the near-haploid/hyperdiploid leukemias and hyperhaploid/hyperdiploid choroid plexus tumors: 1) Extra copies of many chromosomes are the main abnormalities, and structural changes are not consistent; 2) extra copies of certain chromosomes are consistently evident both in near-haploid or hyperhaploid and in hyperdiploid cases, with extra 21, 10, 18 in leukemias and extra 7, 12, 20 in choroid plexus tumors; 3) near-haploid or hyperhaploid cases often have a hyperdiploid cell

10 line; and 4) near-haploidy is associated with poor prognosis, whereas h y p e r d i p l o i d y is associated with good prognosis in ALL. Although few patients have had choroid plexus tumors karyotyped (Table 1), hyperhaploidy appears to be frequently associated with choroid plexus carcinoma whereas hyperdiploidy is associated with papilloma. We suppose that similar m e c h a n i s m s may operate in both malignancies. Analysis of restriction fragment length p o l y m o r p h i s m has shown that some h y p e r d i p l o i d ALL cases derived from a near-haploid precursor cell [11, 12]. That the hyperdiploid clone p r e d o m i n a t e d at diagnosis in several nearhaploid leukemia patients suggests that the transition from near-haploidy to hyperdiploidy may be an early event [10]. As shown in Table 1, m a n y chromosomes were tetrasomic in the h y p e r d i p l o i d choroid plexus tumors, raising suspicion that hyperdiploid tumors might have arisen from a precursor cell with a hyperhaploid chromosome number. Q u a l m a n et al. reported that a n e u p l o i d choroid plexus tumors, carcinomas and papillomas, behaved as a group like flank carcinomas [13]. Molecular studies will answer the question of whether h y p e r d i p l o i d choroid plexus tumors derive from hyperhaploid precursors. Variation in numerical changes from cell to cell was observed in the present case and in two reported cases [3, 6]. Most of those variations meet the criteria for classification as subclones. Similar variations were also present among the reported karyotypes from different laboratories (Table 1). Minority subpopulations may well exist but be undetected in some cases owing to the limited n u m b e r of cells examined in standard cytogenetic studies. Indeed, the hyperhaploid cell clone was initially overlooked in our patient and instead was considered r a n d o m losses from the hyperdiploid clone. In our patient, ~ 2 5 % hyperhaploid cells were i n endoreduplication, but very few h y p e r d i p l o i d cells were exact doublings of the hyperhaploid cells, suggesting that m a n y extra chromosomes were lost soon after endoreduplication. The discrepancy among karyotypes reported from different laboratories may also be due to different cell subpopulations analyzed. Telomeric association or fusion may lead to nondisjunction, which may account for part of the variations of numerical changes in our patient. In our experience, such variation in numerical changes is also c o m m o n in other tumors without telomeric association. It may reflect the unstable status of the cell karyotypes. Cell karyotypes are unstable u n t i l they reach certain cellular DNA content [14], as is supported by the observation that h y p e r d i p l o i d cells were losing chromosomes after doubling from hyperhaploid cells in our patient. Telomeric association was recently subjected to extensive reviews [15-17]. Telomeric association has been reported in giant cell tumor of bone [16] and other malignancies [15]. The telomere repeat sequence TTAGGG is often shortened in tumor cells, which may trigger the activation of telomerase to elongate telomere sequences. The shortened telomeric sequence was often s h o w n to be associated with telomeric association [16-18]. Our case shows that telomeric association not only causes n o n d i s j u n c t i o n but also triggers further structural changes, w h i c h may

Y.S. Li et al.

contribute to the complexity of karyotypes of solid tumors.

We thank Dr. Ralando F. Del Maestro and Dr. David A. Ramsay for providing the tumor sample and allowing us to study their patient.

REFERENCES 1. Zwetsloot CP, Kros JM, Geuze P (1991): Familial occurrence of tumors of the choroid plexus. J Med Genet 28:292-294. 2. Punnett HH, Tomczak EZ, de Chadarevian J-P, Kanev PM (1994): Cytogenetic analysis of a choroid plexus papilloma. Genes Chrom Cancer 10:282-285. 3. Petersen SE, Frederiksen P, Friedrich U (1981): Cytogenetic analysis and flow cytometric DNA measurement of a human tumor with pronounced hypodiploidy. Cancer Genet Cytogenet 4:167-169. 4. Neumann E, Kalousek DK, Norman MG, Steinbok P, Cochrane DD, Goddark K (1993): Cytogenetic analysis of 109 pediatric central nervous system tumors. Cancer Genet Cytogenet 7l:40-49. 5. Roland B, Pinto A (1994): Choroid plexus papilloma with a hyperdiploid karyotype. Am J Hum Genet (suppl)55:A302. 6. Donovan MJ, Yunis EJ, DeGirolami U, Fletcher JA, Schofield DE (1994): Chromosome aberrations in choroid plexus papillomas. Genes Chrom Cancer 11:267-270. 7. Mertens F, Heim S, Mandahl N, Mitelman F, Brun A, StrSmblad L-G, Kullendorff C-M, Donner M (1995): Recurrent chromosomal imbalances in choroid plexus tumors. Cancer Genet Cytogenet 80:83-84. 8. ISCN (1991): Guidelines for Cancer Cytogenetics. Supplement to An International System for Human Cytogenetic Nomenclature, F Mitelman, ed. S. Karger, Basel. 9. Therman E, Susman M (1993): Human Chromosomes, 3rd Ed. Springer-Verlag, New York, p. 151. 10. Sandberg AA (1990): The Chromosomes in Human Cancer and Leukemia, 2nd Ed., Elsevier, New York, pp. 352-357. 11. Onodera N, McCabe NR, Nachman JB, Johnson FL, Le Beau MM, Rowley JD, Rubin CM (1992): Hyperdiploidy arising from near-haploidy in childhood acute lymphoblastic leukemia. Genes Chrom Cancer 4:331-336. 12. Onodera N, McCabe NR, Rubin CM (1992): Formation of a hyperdiploid karyotype in childhood acute lymphoblastic leukemia. Blood 80:203-208. 13. Qualman SJ, Shannon BT, Boesel CP, Jacobs D, Jinkens C, Hayes J (1992): Ploidy analysis and cerebrospinal fluid nephelometry as measures of clinical outcome in childhood choroid plexus neoplasia. Pathol Annu 27:305-320. 14. Deaven LL, Cram LS, Wells RS, Kraemer PM (1981): Relationship between chromosome complement and cellular DNA content in tumorigenic cell populations. In: Genes, Chromosomes, and Neoplasia. PE Arrighi, PN Rao, E Stubblefield, eds. New York: Raven Press. 15. Schwartz HS, Allen GA, Butler MG (1990): Telomeric associations: Appl Cytogenet 16:133-137. 16. Sandberg AA, Bridge JA (1994): The Cytogenetics of Bone and Soft Tissue Tumors. R. G. Landes, Austin, pp. 39-41. 17. Marx J (1994): Chromosome ends catch fire. Science 265: 1656-1658. 18. Holzman K, Blin N, Welter C, Zang KD, Seitz G, Henn W (1993): Telomeric associations and loss of telomeric DNA repeats in renal tumors. Gene Chrom Cancer 6:178-181.