Ординатура / Офтальмология / Английские материалы / Ocular Oncology_Albert, Polans_2003

male patients. The involvement of the Y chromosome is a little ambiguous, and could be artifactual, related to patient age or cultural conditions. Conversely, as loss of the Y chromosome is not a frequent event in corresponding blood from patients, and given that its occurrence is mainly associated with the presence of other abnormalities [13,29,38], (unpublished data, Sheffield 2001), an as yet undetermined role, possibly related to tumor progression, has been postulated [7,12]. The gain of chromosome 21 appears to be secondary to those of other chromosomes including 3, 6 and 8, and as such is also speculated to be associated with tumour progression [24]. Melanomas with involvement of chromosomes 3 and 8 seemingly have higher incidences of trisomy 21, and as a consequence, the change is more frequent in melanomas with ciliary body involvement [7,11–14,24,33].

Chromosomal abnormalities of 9, 10, and 11 may indicate a degree of commonality between uveal and cutaneous melanoma, as nonrandom alterations of these chromosomes are found in cutaneous melanoma, but at a much higher frequency than that observed in uveal melanoma [39]. Comparable regions appear to be targeted in both forms of melanoma [7,11–14,24,33], but less is known about the role such changes may have in uveal melanoma and few associations have been drawn. Chromosomal analysis suggests that changes of chromosome 9 are present in only approximately 10% of cases, but this frequency includes abnormalities of both 9p and 9q, indicating that the incidence for rearrangements of each arm is actually much less [12–14,24,33,37]. In cutaneous melanoma, 9p appears the preferential target; in uveal melanoma, using techniques other than cytogenetics, slightly higher incidences have been recorded of approximately 20% for imbalances of 9p with MSA [19]. CGH studies have also indicated more involvement for 9p alteration, but they are contradictory, identifying both increased loss and gain for the region [40,41]. The role, and the true incidence of chromosome 9 abnormalities in uveal melanoma, has yet to be clarified, but the change may identify a shared inheritance with cutaneous melanoma, at least in some uveal melanomas.

Cytogenetic studies have also reported incidences of around 10% for deletions and rearrangements of 10q in uveal melanoma [12,14,24,41]. A much higher frequency is reported for cutaneous melanoma, and specific regions of 10q have been implicated [42]. In uveal melanoma however, the association is more tenuous, and because of the limited number of cases with such abnormalities, the specific region of 10q affected, and the implication, has yet to be defined. Stronger evidence exists for the changes affecting chromosome 11 in ocular melanoma, which are found in approximately 20% of reported cases [7,11–14,24,33]. In the majority of cases, these rearrangements are highly specific, targeting the regions 11p15 or 11q23-q25 [7,24] (Figs. 2 and 3). A comparable region of 11q is seemingly implicated in the cutaneous counterpart, where it is speculated to be associated with poor prognosis [43]. Insufficient evidence exists to draw similar conclusions in uveal melanoma. It is, however, possible that an opposite relationship may occur than that seen in the cutaneous form, since these changes are slightly more common among melanomas with choroidal involvement and or tumors of a spindle morphology; as such, they may correlate with a better prognosis [12,14,24,41].

Figure 3 Representative karyotype from a primary posterior uveal melanoma. Structural rearrangements of chromosomes 3, 8, 11, 15, and 16 are present, as indicated by arrows, producing loss of 3p and gain of 8. Chromosome painting using FISH was used to confirm the partial involvement of chromosome 8 in both the derivative chromosomes 8 and 11. 47,XX,add(3)(p12–13), þ 4,add(8)(q24),add(11)(p15),-14, þ add(15)(p11),der(16)t(6;16) (p21;q13)

E.The Future of Uveal Melanoma Cytogenetics

Abnormalities of all chromosomes have been reported in uveal melanoma. In some instances, associations have been made, but subsequent study has so far failed to substantiate such relationships. Until additional information is gained, it will not be possible to establish if these other abnormalities are of relevance or occur as a result of increasing instability associated with tumor progression. Cytogenetic analysis has played a valuable role in increasing our understanding of the genetic changes in uveal melanoma, allowing clear relationships between certain chromosome changes and prognosis to be determined. As more information accumulates, it is likely the involvement of other less common alterations will be further defined; in this respect cytogenetics still has much to offer. In addition, the correlation of certain chromosomal changes with prognosis, in particular chromosome 3, would suggest that cytogenetic analysis is a reliable and practicable method for determining prognosis in many uveal melanomas. The use of procedures such as FISH and MSA could, however, provide a valuable alternative, as they require smaller amounts of tumor material, and viability is not essential. With these techniques the procedure could be adapted to the assessment of small in situ lesions using fine-needle

aspiration biopsies (FNAB). Despite sampling only a small portion of the lesion, chromosome analysis is feasible on these biopsies and results are apparently comparable to the bulk of the lesion [44]. Both FISH and MSA are suitable techniques to determine the prognostic significance of certain chromosomal abnormalities in uveal melanoma and could theoretically provide results in 100% of cases, as the need for culturing is abrogated [31]. Assessment of chromosomal changes may in the future become part of the standard practices applied to every uveal melanoma. As our knowledge of the relevant genetic alterations increases, additional potentially moderating chromosomal changes may also be identified. Ultimately the future lies in the detection of the underlying genetic alterations that form the basis of the visible chromosomal rearrangements. Only by identifying the genes responsible for uveal melanoma development can we develop new strategies designed to combat their influence.

III.THE IDENTIFICATION OF GENES INVOLVED IN UVEAL MELANOMA TUMORIGENESIS

To date, most reports of the genetic abnormalities associated with uveal melanoma have detailed the chromosomal alterations, mainly by cytogenetics but also by CGH. Fewer studies have attempted to establish the genes responsible for uveal melanoma initiation and progression. For the most part, the chromosomal regions implicated are large, representing as they do either entire chromosomes or chromosome arms; at best, the rearrangements still involve large chromosomal regions, which could encompass many biologically relevant genes. Equally important is the type of abnormality produced. In broad terms changes which result in a loss of genetic material, can be considered to target genes with a suppressive function, or so called tumor suppressor genes. Conversely, areas where amplification of regions has occurred may suggest the input of positive regulators of the process, otherwise termed oncogenes, which in some manner enhance uveal melanoma development and progression. Determining which are the candidate genes is a daunting task when such large regions are implicated. Cytogenetic analysis can most readily assist in the identification of relevant genes by implementing a more targeted research through the discovery of structural rearrangements and thus minimizing the chromosomal region where relevant genes may reside.

A.Chromosome 3

The most consistent genetic alteration of uveal melanoma is a case in point. It is rather perplexing that uveal melanomas can, broadly speaking, be divided into those tumors where monosomy of chromosome 3 is found and those where ostensibly two normal copies of chromosome 3 are present. This chromosome is only infrequently involved in structural abnormalities in uveal melanoma; in a series of over 100 tumors, only 4 cases actually had visible rearrangements of chromosome 3 (unpublished data, Sheffield 2001). Both arms were affected, and miscellaneous breakpoints were found, 3p24–25, 3p12–13, 3q13, and 3q21 (Fig. 2). Reports in the literature also indicate an equally diverse range, with the smallest regions of involvement shown to be at 3p25, 3p13, 3q13–21, and 3q24–26 [20,21,45]. Numerous

cancer-related genes are located on chromosome 3 [46]. The virtual absence in uveal melanoma of structural rearrangements of this chromosome implies that its entire loss represents the most efficacious way to target multiple genes resident on a single chromosome [21]. The frequency with which this change occurs would suggest that it plays a pivotal role in the tumorigenesis of at least some uveal melanomas. Whether all uveal melanomas actually have small nonvisible deletions of chromosome 3 is unclear, but it is known that even apparently normal copies of chromosome 3 can harbor small deletions [21]. In extreme cases, isodisomy has been reported, where one copy of chromosome 3 is lost and the remaining homologue, presumably with all its deficiencies, is duplicated [47]. It is even possible that in uveal melanomas two pathways exist to target genes on chromosome 3. In the first, most of the relevant genes would effectively receive one ‘‘hit’’ by the loss of one entire copy, as seen with monosomy. In the second pathway, a more considered approach is taken, in which relevant genes are specifically targeted by nonvisible alterations or are the subject of structural rearrangements. From this point onwards it would seem that both pathways equally require the input of genes on chromosome 8; but, again, this may be effected by amplification of 8q in its entirety or through partial amplification. Seemingly a more conservative approach targeting genes on chromosome 3 gives rise to a similar approach to amplification of genes on 8q (Figs. 2 and 3), and several reports exist in the literature to support this theory [3].

In uveal melanoma, however, the relevant genes on chromosome 3 await identification, although recent evidence implicates one potential candidate gene, the TGF-bR2 gene. Breakpoints and loss of heterozygosity (LOH) of the region containing the gene, at 3p21–22, have been reported in uveal melanoma [48], while TGF-b itself has been shown to regulate uveal melanoma proliferation negatively [48]. Many other potentially relevant genes await exploration, including genes related to cellular divisional control and longevity, such as hereditary nonpolyposis type 2 (MLH1) at 3p23-p21.3, and the telomerase RNA component (TERC) (hTR), located at 3q21-q28 [46]. Indeed, TERC may be of particular interest as it has the potential to regulate negatively telomerase activity, which is known to be upregulated in uveal melanomas, potentially contributing to avoidance of both cell senescence and death [46,49–51]. Other potential candidate genes, including Von Hippel Lindau (VHL) and thyroid hormone receptor b (THRB) genes, have recently been eliminated by more detailed molecular investigations, in which losses of markers on both arms of chromosomes 3 were assessed [21,47].

B.Chromosome 8

A comparable situation exists for the identification of relevant genes on chromosome 8, since in the majority of cases the entire long arm is affected. In this instance, however, amplification of genes, rather than loss, is the net result. These amplifications are predominantly in the form of an isochromosome in which both arms of the chromosome are derived from the long arm of chromosome 8, effecting a deletion of the short arm; thus gene loss on 8p may also be important. A comparable situation is found in some of the more common solid malignancies—such as breast and prostate, where potential candidate genes have been investigated—and may also be a feature in uveal melanoma development [52]. For 8q, cytogenetic studies in combination with CGH have defined the smallest region of amplification as 8q21-

qter [7,33,41]. More recently, studies using a combination of SKY and CGH, have found that in actuality two distinct regions of 8q may be specifically amplified, at 8q21.1–21.2 and again at 8q23–24 [20]. At present we can only speculate as to which genes in uveal melanoma may be the targets of such amplifications, as many genes of potential importance in biological processes associated with cancer are located on this chromosome. Included are some genes related to its potential role in the development of more advanced uveal melanoma, such as degradative enzymes and cell adhesion molecules [46], but as yet no evidence exists for their involvement in uveal melanoma. A clear candidate does, however, exist, the myc oncogene, which has diverse effects on cellular proliferation, and is located at 8q24, therefore falling within the second region identified by Naus and associates (20). Whether myc is the preferred target, or is coamplified because of its proximity to an otherwise unknown gene, remains to be established. Evidence does suggest that myc has some role to play in uveal melanoma tumorigenesis, as at least 30% of tumors appear to have specific amplification of myc, with the gain itself occurring later in the genetic progression [53]. If myc is the potential target, its ultimate effect appears to be contradictory, since expression is consistently associated with a good outcome [54–56]. Ultimately refining regional involvement on 8q will greatly assist in the hunt for the relevant amplified genes.

C.Chromosome 6

Essentially, cytogenetic changes of chromosome 6 would imply the contribution of two sets of genes; deletions of 6q would seemingly target negative regulators of the process, while the amplification of 6p would suggest the input of genes that enhance tumorigenesis. The situation may ultimately become more complex if the role of chromosome 6 as a moderating change is established. Breakpoints of 6p are consistently located toward the centromeric region, with the smallest regional gain established as 6pter-p21 [41], but on 6q they can be quite diverse, and often the whole arm is deleted through the formation of an isochromosome [7,12,24]. All uveal melanomas, including iris tumors, and more importantly cutaneous melanoma, appear to have comparable alterations of chromosome 6, suggesting the involvement of a common series of genes integral to melanocytic transformation [3,16,17,24]. Because of the nature of chromosome 6 rearrangements in uveal melanoma, again affecting both arms, it seems likely that numerous genes are important. In uveal melanoma there are several potential targets genes located in the region 6pter-p21; these include genes such as CDKN1A and VEGF, among whose functions are cell cycle control and angiogenesis [41,57,58]. The immunology of these melanomas could also be severely altered; as the genes encoding MHC class I molecules and TNF-a are also localized to this region [46]. Altered HLA expression in uveal melanoma is known; however, no clear relationship has been established with 6p abnormalities [59].

Potentially, at least two regions may be selectively deleted on 6q, but identifying the smallest regional involvement is hampered by the manner of rearrangements, which tend to produce loss from the breakpoint onward, rather than small interstitial deletions [7,12,–14,24,33,40]. Nevertheless, there appears to be a reasonably clear-cut distal deletion affecting 6q24-q27, but other breakpoints imply a second region at 6q13-q15, with potentially a third region at 6q21-q22 [7,12–

14,24,33,40]. Similar regions have been implicated in cutaneous melanoma, and it is entirely possible that the same panel of genes also has a functional role in uveal melanoma development. Much work still remains to be done regarding chromosome 6 in uveal melanoma. It is highly likely that aberrations of 6q in particular are far more complex than initially thought, but with the use of additional techniques such as SKY, the regions typically involved on 6q will be refined [20].

D.Chromosome 1

Although gain of 1q is occasionally found in uveal melanoma, in most instances deletions of 1p are the relevant alteration, either as loss of defined regions or as the result of unbalanced translocations in which the entire short arm is absent [7,12,24] (Fig. 1). These translocation events follow a specific pattern, and the recipient partner for 1q is often a member of the D group of chromosomes. Heterochromatic regions are heavily implicated in these transactions, and the presence of breakpoints in these regions may highlight the inherent weakness of highly repetitive DNA [7,12,24]. Other breakpoints, spanning a region of 1p12-p36, are reported, but a smallest regional involvement at 1p32-p36 has been established [7,12,24,33]. This more distal region appears different to a region identified by Aalto and associates [26], and it is likely that, as with other chromosomal changes in uveal melanoma, more than one gene is implicated by these rearrangements. Again, genes postulated to be involved in the cutaneous form could also be heavily implicated in uveal melanoma. In the cutaneous form, for example, deletions of a gene encoding a protein kinase isoform (CDC2L) located to 1p36, are found [60] and could potentially represent the target of the smallest regional involvement so far identified by cytogenetics [7,12,24,33].

E.Other Chromosomes Implicated in Uveal Melanoma

The gene targets of other chromosomal changes in uveal melanoma could again imply the input of genes involved in the pathogenesis of its cutaneous counterpart. Clear comparisons are provided by the comparable changes of chromosomes 9, 10, and 11 found in the two melanocytic malignancies. Deletions of chromosome 9 are considered to be an early event in the pathogenesis of cutaneous melanoma and target a familial melanoma susceptibility gene, p16, or CDKN2/MTS-1/INK4A, which is located at 9p21 [61,62]. In uveal melanoma, deletion of the p16 gene is rare [63]; inactivation is mainly thought to arise by other mechanisms, including altered methylation status and mutations, which have been identified in about 30% of uveal melanomas [64,65]. Inactivation of p16 appears to be a more important event in uveal melanoma tumorigenesis than might initially be thought on the basis of cytogenetic studies alone; it is possible that, as in cutaneous melanoma, it is a relatively early event. Similar importance may ultimately be attributed to the role of other chromosomal changes shared by both forms of melanoma. Currently, however, the targets on chromosome 10 appear to be different in the two forms of this malignancy, as the PTEN gene at 10q23 is implicated in cutaneous melanoma [66], but no mutations or deletions have been identified in uveal melanoma cell lines [67]. Finally, little is known about the target genes on chromosome 11 relevant for

melanomas, but it is possible that genes implicated in other solid malignancies, at 11q23, could be the targets [68].

Increasingly more detailed investigation of the relevant chromosomal changes in uveal melanoma is being undertaken, and it is to be anticipated that the culprit genes cannot remain hidden for much longer.

IV. SUMMARY

In the last decade our knowledge of the genetic changes related to uveal melanoma tumorigenesis has increased exponentially, but it is apparent that we have much more to learn. Clearly, in uveal melanoma sequential chromosome changes are present, with alterations of chromosome 3 and 6 occurring earlier to those of 1, 8, and 21. As yet, it is not known if any of these changes are responsible for initiating uveal melanoma pathogenesis or whether otherwise undetected abnormalities instigate the transformation. Certainly the few MSA studies so far undertaken suggest that much higher levels of genetic changes exist than originally suggested by cytogenetic studies. It is therefore possible that an undisclosed succession of discreet submicroscopic events is responsible for uveal melanoma tumorigenesis. The search for the underlying genetic defects has begun in earnest, and with the increasing application of techniques such as FISH, CGH, SKY, and MSA and the continued input of cytogenetics, we have the potential to more fully refine and characterize regional chromosomal involvement. The clinical relevance of the established chromosomes changes, specifically monosomy 3, is now apparent; for uveal melanoma genetics, such studies have come of age. The potential exists to make real improvements in our understanding of the development of these melanomas, with the associated benefits that this may provide.

ACKNOWLEDGMENTS

We would like to express our gratitude to Yorkshire Cancer Research, Trent Regional Health Authority, and the Medical Research Council for support. Our thanks to the contributions made to studies by Mr. Kirtikbhai A. Patel, Mr. Neil Cross, Ms. Nicola Tattersall, and to Mr. Robin Farr for graphics.

REFERENCES

1.Nowell PC, Hungerford DA. A minute chromosome in human chronic granulocytic leukaemia. Science 132:1497, 1960.

2.Sandberg AA, Chen Z. Cancer cytogenetics and molecular genetics—Clinical implications (review). Int J Oncol 7:1241–1251, 1995.

3.Mitelman F, Johansson B, Merten F, eds. Mitelman Database of Chromosome Abberrations in Cancer. The Cancer Genome Anatomy Project. http://cgap.nci.nih.gov/ Chromosomes/Mitelman 2001.

4.Rey JA, Bello MJ, DeCompos JM, Ramos MC, Benitez J. Cytogenetic findings in a human malignant melanoma metastatic to the brain. Cancer Genet Cytogenet 16:179– 183, 1985.

5.Griffin CA, Long PP, Schachat AP. Trisomy 6p in an ocular melanoma. Cancer Genet Cytogenet 32:129–132, 1998.

6.Horsman DE, Sroka H, Rootman J, White VA. Monosomy 3 and isochromosome 8q in a uveal melanoma. Cancer Genet Cytogenet 45:249–253, 1990.

7.Prescher G, Bornfeld N, Becher R. Non-random chromosomal abnormalities in primary uveal melanoma. J Natl Cancer Inst 82:1765–1769, 1990.

8.Sisley K, Rennie IG, Cottam DW, Potter AM, Potter CW, Rees RC. Cytogenetic findings in six posterior uveal melanomas: involvement of chromosomes 3, 6 and 8. Genes Chromosomes Cancer 2:205–209, 1990.

9.Prescher G, Bornfeld N, Horsthemke B, Becher R. Chromosomal aberrations defining uveal melanoma of poor prognosis. Lancet 339:691–692, 1992.

10.Sisley K, Cottam DW, Rennie IG, Parsons MA, Potter AM, Potter CW, Rees RC. Nonrandom abnormalities of chromosomes 3, 6, and 8 associated with posterior uveal melanoma. Genes Chromosomes Cancer 5:197–200, 1992.

11.Dahlenfors R, Tornqvist G, Wettrell K, Mark J. Cytogenetical observations in nine malignant melanomas. Anticancer Res 13:1415–1420, 1993.

12.Horsman DE, White VA. Cytogenetic analysis of uveal melanoma. Consistent occurrence of monosomy 3 and trisomy 8q. Cancer 71, 811–819, 1993.

13.Wiltshire RN, Elner VM, Dennis T, Vine AK, Trent JM. Cytogenetic analysis of posterior uveal melanoma. Cancer Genet Cytogenet 66: 47–53, 1993.

14.Singh AR, Boghosian-Sell L. Wary KK, Shields CL, De Potter P, Donoso LA, Shields JA, Cannizzaro LA. Cytogenetic findings in primary uveal melanoma. Cancer Genet Cytogenet 72, 109–115, 1994.

15.Prescher G, Bornfeld N, Hirche H, Horsthemke B, Karl-Heinz Jokel, Becher R. Prognostic implications of monosomy 3 in uveal melanoma. Lancet 347:1222–1225, 1996.

16.White VA, Horsman DE, Rootman J. Cytogenetic characterization of an iris melanoma. Cancer Genet Cytogenet 82:85–87, 1995.

17.Sisley K, Brand C, Parsons MA, Maltby E, Rees RC, Rennie IG. Cytogenetics of iris melanomas disparity with other uveal melanomas. Cancer Genet Cytogenet 101:128–133, 1998.

18.Sisley K, Rennie IG, Parsons MA, Jacques R, Hammond DW, Bell SM, Potter AM, Rees RC. Abnormalities of chromosomes 3 and 8, in posterior uveal melanoma, correlate with prognosis. Genes Chromosom Cancer 19:22–28, 1997.

19.Parrella P, Sidransky D, Merbs SL. Allelotype of posterior uveal melanoma: Implications for a bifurcated tumour progression pathway. Cancer Res 59:3032–3037, 1999.

20.Naus NC, van Drunen E, De Klein A, Luyten GPM, Paridaens DA, Alers JC, Ksander B, Beverloo HB, Slater RM. Characterization of complex chromosomal abnormalities in uveal melanoma by fluorescent in situ hybridization, spectral karyotyping and comparative genomic hybridization. Genes Chromosomes Cancer 30:267–273, 2001.

21.Tschentscher F, Prescher G, Horsman DE, White VA, Rieder H, Anastassiou G, Schilling H, Bornfeld N, Bartz-Schmidt KU, Horsthemke B, Lohmann DR, Zeschnigk M. Partial deletions of the long and short arm of chromosome 3 point to two tumour suppressor genes in uveal melanoma. Cancer Res 61:3439–3442, 2001.

22.Prescher G, Bornfeld N, Becher R. Two subclones in a case of uveal melanoma: Relevance of monosomy 3 and multiplication of chromosome 8q. Cancer Genet Cytogenet 77:144–2146, 1994.

23.White VA, McNeil K, Thiberville L, Horsman DE. Acquired homozygosity (isodisomy) of chromosome 3 during clonal evolution of a uveal melanoma: Association with morphologic heterogeneity. Genes Chromosomes Cancer 15:138–143, 1996.

24.Sisley K, Parsons MA, Garnham J, Potter AM, Curtis DI, Rees RC, Rennie IG. Association of specific chromosome alterations with tumour phenotype in posterior uveal melanoma. Br J Cancer 82:330–338, 2000.

25.Parada LA, Maranon A, Hallen M, Tranberg KG, Stenram U, Bardi G, Johansson B. Cytogenetic analysis of secondary liver tumours reveal significant differences in genomic imbalances between primary and metastatic colon carcinomas. Clin Exp Metastasis 17:471–479, 1999.

26.Aalto Y, Eriksson L, Seregard S, Larsson O, Knuutila S. Concomitant loss of chromosome 3 and whole arm losses and gains of chromosomes 1,6, or 8 in metastasizing primary uveal melanoma. Invest Ophthalmol Vis Sci 42:313–317, 2001.

27.Scholes AG, Liloglou T, Maloney P, Hagan S, Nunnj, Hiscott P, Damato BE, Grierson I, Field JK. Loss of heterozygosity on chromosomes 3, 9, 13, and 17 including the retinoblastoma locus, in uveal melanoma. Invest Ophthalmol Vis Sci 11:2472–2477, 2001.

28.Mooy CM, De Jong PT. Prognostic parameters in uveal melanoma: A review. Surv Ophthalmol 41:215–228, 1996.

29.White VA, Chambers JD, Courtright PD, Chang WY, Horsman DE. Correlation of cytogenetic abnormalities with the outcome of patients with uveal melanoma. Cancer 83:354–359, 1998.

30.McNamara M, Felix C, Davison EV, Fenton M, Kennedy SM. Assessment of chromosome 3 copy number in ocular melanoma using fluorescence in situ hybridization. Cancer Genet Cytogenet 98:4–8, 1997.

31.Patel KA, Edmondson ND, Talbot F, Parsons MA, Rennie IG, Sisley K. Prediction of prognosis in patients with uveal melanoma using fluorescence in situ hybridization. Br J Ophthalmol 85:1440–1444, 2001.

32.Tschentscher F, Prescher G, Zeschnigk M, Horsthemke B, Lohmann DR. Identification of chromosomes 3, 6, and 8 aberrations in uveal melanoma by microsatellite analysis in comparison to comparative genomic hybridization. Cancer Genet Cytogenet 122:13–17, 2000.

33.Prescher G, Bornfeld N, Friedrichs W, Seeber S, Becher R. Cytogenetics of twelve cases of uveal melanoma and patterns of nonrandom anomalies and isochromosome formation. Cancer Genet Cytogenet 80:40–46, 1995.

34.Zhang J, Glatfelter AA, Taetle R, Trent JM. Frequent alterations of evolutionary conserved regions of chromosome 1 in human malignant melanoma. Cancer Genet Cytogenet 111:119–123, 1999.

35.Dracopoli NC, Harnett P, Bale SJ, Stanger BZ, Tucker MA, Housman DE, Kefford RF. Loss of alleles from the distal short arm of chromosome 1 occurs late in melanoma progression. Proc Natl Acad Sci USA 86:4614–4618, 1989.

36.Mukai S, Dryja TP. Loss of alleles at polymorphic loci on chromosome 2 in uveal melanoma. Cancer Genet Cytogenet 22:45–53, 1986.

37.Magauran RG, Gray B, Small KW. Chromosome 9 abnormality in choroidal melanoma. Am J Ophthalmol 117:109–11, 1994.

38.Singh AD, Donoso LA, Jackson L, Shields CL, De Potter P, Shields JA. Familial uveal melanoma absence of constitutional cytogenetic abnormalities in 14 cases. Arch Ophthamol 114:502–503, 1996.

39.Nelson MA, Radmacher MD, Simon R, Aickin M, Yang JM, Panda L, Emerson J, Roe D, Adair L, Thompson F, Bangert J, Leong SPL, Taetle R, Salmon S, Trent J. Chromosome abnormalities in malignant melanoma: Clinical significance of nonrandom chromosome abnormalities in 206 cases. Cancer Genet Cytogenet 122:101–109, 2000.

40.Gordon KB, Thompson CT, Char DH, O’Brien JM, Kroll S, Ghazvini S, Gray JW. Comparative genomic hybridization in the detection of DNA copy number abnormalities in uveal melanoma. Cancer Res 54:4764–4768, 1994.

41.Speicher MR, Prescher G, du Manoir S, Jauch A, Horsthemke B, Bornfeld N, Becher R, Cremer T. Chromosomal gains and losses in uveal melanoma detected by comparative genomic hybridization. Cancer Res 54:3817–3823, 1994.

42.Robertson GP, Herbst RA, Nagane M, Huang HJ, Cavenee WK. The chromosome 10 monosomy common in human melanoma results from loss of two separate tumour suppressor loci. Cancer Res 59:3596–3601, 1999.

43.Herbst RA, Mommert S, Casper U, Podewski EK, Kiehl P, Kapp A, Weiss J. 11q23 allelic loss is associated with regional lymph node metastasis in melanoma. Clin Cancer Res 6:3222–2227, 2000.

44.Sisley K, Nichols C, Parsons MA, Farr R, Rees RC Rennie IG. Clinical applications of chromosome analysis, from fine needle aspiration biopsies, of posterior uveal melanoma. Eye 12:203–207, 1998.

45.Blasi MA, Roccella E, Balestrazzi E, Del Porto G, De Felice N, Roccella M, Rota R, Grammatico P. 3p13 region: A possible location of a tumour suppressor gene involved in uveal melanoma. Cancer Genet Cytogenet 108:81–83, 1999.

46.Online Mendelian Inheritance in Man (OMIM), Johns Hopkins University, 1966–2001, http://www.ncbi.nlm.nih.gov/Omim/

47.White VA, McNeil BK, Horsman DE. Acquired homozygosity (isodisomy) of chromosome 3 in uveal melanoma. Cancer Genet Cytogenet 102:40–45, 1998.

48.Myatt N, Aristodemou P, Neale MH, Foss AJE, Hungerford JL, Bhattacharya S, Cree IA. Abnormalities of the transforming growth factor-beta pathway in ocular melanoma. J Pathol 192:511–518, 2000.

49.De Lange T, Jacks T. For better or worse? Telomerase inhibition and cancer. Cell 98:273–275, 1999.

50.Mitchell JR, Collins K. Human telomerase activation requires two independent interactions between telomerase RNA and telomerase reverse transcriptase. Mol Cell 6:361–371, 2000.

51.Heine B, Coupland SE, Kneiff S, Demel G, Bornfeld N, Hummel M, Stein H. Telomerase expression in uveal melanoma. Br J Ophthalmol 84:217–223, 2000.

52.Ugolini F, Adelaide J, Charafe-Jauffret E, Nguyen C, Jacquemier J, Jordan B, Birnbaum D, Pebusque MJ. Differential expression assay of chromosome arm 8p genes identifies Frizzled-related (FRP1/FRZB) and fibroblast growth factor receptor 1 (FGFR1) as candidate breast cancer genes. Oncogene 18:1903–1910, 1999.

53.Parrella P, Caballero OT, Sidransky D, Merbs SL. Detection of c-myc amplification in uveal melanoma by fluorescent in situ hybridization. Invest Ophthalmol Vis Sci 42:1679– 1684, 2001.

54.Mooy CM, Luyten GPM, de Jong PTVM, Luider TM, Stijnen T, van de Ham F, van Vroonhoven CC, Bosmam FT. Immunohistochemical and prognostic analysis of apoptosis and proliferation in uveal melanoma. Am J Pathol 147:1097–1104, 1995.

55.Chana JS, Cree IA, Foss AJE, Hungerford JL, Wilson GD. The prognostic significance of c-myc oncogene expression in uveal melanoma. Melanoma Res 8:139–144, 1998.

56.Chana JS, Wilson GD Cree IA, Alexander RA, Myatt N, Neale M, Foss AJE, Hungerford JL. c-myc, p53, and Bcl-2 expression and clinical outcome in uveal melanoma. Br J Ophthalmol 83:110–114, 1999.

57.Demetrick DJ, Matsumoto S, Hannon GJ, Okamoto K, Xiong Y, Zhang H, Beach DH. Chromosomal mapping of the genes for the human cell cycle proteins cyclin C (CCNC), cyclin E (CCNE), p21 (CDKN1) and KAP (CDKN3). Cytogenet Cell Genet 69:190–192, 1995.