[Cancer Biology & Therapy 3:1, 121-123, January 2004]; ©2004 Landes Bioscience
Commentary
Gene Expression Profiling of Human Cutaneous Melanoma
*Correspondence to: Menashe Bar-Eli; Department of Cancer Biology; Box 173; The University of Texas M.D. Anderson Cancer Center; 1515 Holcombe Blvd.; Houston, Texas 77030 USA; Tel.: 713.794.4004; Fax: 713.794.4005; Email:
[email protected] Received 01/26/04; Accepted 01/26/04 Previously published online as a Cancer Biology & Therapy E-publication:
KEY WORDS
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Expression Analysis of Genes Identified by Molecular Profiling of VGP Melanomas and MGP Melanoma-Positive Lymph Nodes
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Amanda Pfaff Smith, Ashani T. Weeraratna, Justin R. Spears, Paul S. Meltzer and Dorothea Becker and
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SAGE Identification and Fluorescence Imaging Analysis of Genes and Transcripts in Melanomas and Precursor Lesions
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Commentary to:
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melanoma, DNA microarrays, gene profiling, matastasis
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http://www.landesbioscience.com/journals/cbt/abstract.php?id=728
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1Departments of Cancer Biology and 2Surgical Oncology; The University of Texas M.D. Anderson Cancer Center; Houston, Texas 77030 USA
Over 55,100 new cases of cutaneous melanoma will be diagnosed in the United States in 2004, representing an increase in incidence that exceeds most other neoplastic diseases.1 It is particularly devastating in view of the young age at which so many of these patients are diagnosed and the lethality of metastatic disease. Although 85% of patients with melanoma present with clinically negative regional lymph nodes, many of these patients actually harbor occult lymphatic metastases2,3 and are at subsequent risk for distant disease and death from melanoma. The current melanoma staging system, which is based on relatively well-established prognostic determinants, including clinicopathologic factors such as tumor thickness, primary tumor ulceration, and presence of regional lymph node or other metastases, enables us to identify a fraction of patients with a high risk of developing metastases.4-6 Over the past fifteen years, clinicians have developed a sophisticated multidisciplinary approach—termed lymphatic mapping and sentinel node biopsy—that accurately stages the regional nodal basin in patients with melanoma and provides improved prognostic stratification of patients.2,3 This technique is based on the now well-established concept that finite regions of skin drain to specific lymph nodes—i.e., the “sentinel” nodes—and that these nodes are the most likely to contain microscopic metastases. In sentinel node biopsy, the sentinel node(s) are removed using a minimally invasive technique, and are then examined using specialized histologic techniques. Approximately 20% of patients have pathologic evidence of metastases in the sentinel nodes, and these patients undergo therapeutic lymphadenectomy. However, the approximately 80% of patients without evidence of metastases in the sentinel nodes can be spared the morbidity of therapeutic node dissection. We and others have demonstrated that the histologic status of the sentinel node in patients with clinically negative nodes is the most important predictor of recurrence and survival by univariate and multivariate analyses.2,3 Although revisions to the melanoma staging system have significantly enhanced our ability to stratify patients,4-6 current prognostic factors for melanoma, including sentinel node status, are not optimal. For example, while it is evident that the histologic status of the sentinel lymph node is an important prognostic determinant, not all patients with micrometastases develop distant disease or die from melanoma; in addition, some patients without evidence of microscopic nodal metastasis will ultimately develop recurrent melanoma. Better methods of distinguishing among patients with different risks of distant metastases are needed. However, the often capricious biological behavior of melanoma makes developing an improved staging system for this disease particularly difficult. The development of high-throughput gene expression analysis and more recently, proteomic profiling technologies offers an opportunity to identify new and more refined prognostic factors for melanoma.7 Such technologies permit the simultaneous study of numerous genes, including those whose function or even identity is as yet unknown.7-11 With such molecular profiling techniques, it might be possible to identify gene expression profiles associated with a favorable or unfavorable prognosis as well as targets for anti-metastasis therapy. Correlation of particular gene expression profiles with clinical outcome including response to therapy, risk of organ-specific metastasis, or survival, may ultimately define prognosis and optimal treatment approaches for the individual patient. Perhaps most exciting for the clinician, if molecular markers are identified that correlate with minimal metastatic potential, it may be possible for specific subsets of patients to be spared the potential morbidity of adjuvant therapy. One of the difficulties in studying melanoma is that unlike many other solid tumors, primary melanomas are often completely excised for initial diagnostic purposes, meaning that in most cases only formalin-fixed, paraffin-embedded tissue is available for analysis. This shortcoming has generally restricted use of cDNA microarray and oligonucleotidebased systems in studies of melanoma to the limited number of established primary cell lines or clinically evident metastases.
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Jeffrey E. Gershenwald1,2 Menashe Bar-Eli1,*
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Are We There Yet?
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Shannon L. McDonald, Howard D. Edington, John M. Kirkwood and Dorothea Becker
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GENE EXPRESSION PROFILING OF HUMAN CUTANEOUS MELANOMA
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In summary, to yield the most useful information, any attempts to identify new molecular prognostic markers should take into account validated clinicopathologic prognostic markers. Combining the known clinicopathologic prognostic factors with newly discovered and clinically validated molecular markers thus has the potential to revolutionize patient staging, and identify targets for and predictors of response to anti-metastasis therapy, all with a goal of improving patient care. References
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1. Jemal A, Murray T, Samuels A, Ghafoor A, Ward E, Thun MJ, et al. Cancer statistics, 2004. CA Cancer J Clin 2004; 54:8-29. 2. Gershenwald JE, Thompson W, Mansfield PF, Lee JE, Colome MI, Tseng CH, et al. Multiinstitutional melanoma lymphatic mapping experience: the prognostic value of sentinel lymph node status in 612 stage I or II melanoma patients. J Clin Oncol 1999; 17:976-83. 3. Morton DL, Wen DR, Wong JH, Economou JS, Cagle LA, Storm FK, et al. Technical details of intraoperative lymphatic mapping for early stage melanoma. Arch Surg 1992; 127:392-9. 4. Balch CM, Buzaid AC, Soong SJ, Atkins MB, Cascinelli N, Coit DG, et al. Final version of the American Joint Committee on Cancer staging system for cutaneous melanoma. J Clin Oncol 2001; 19:3635-48. 5. Balch CM, Soong SJ, Gershenwald JE, Thompson JF, Reintgen DS, Cascinelli N, et al. Prognostic factors analysis of 17,600 melanoma patients: validation of the American Joint Committee on Cancer melanoma staging system. J Clin Oncol 2001; 19:3622-34. 6. Balch CM, Greene F, Page D, Fleming ID, et al. Melanoma of the Skin. In Green F, Page D, Fleming I, et al. eds. AJCC Cancer Staging Manual 2002; 6:209-17. 7. DeRisi J, Penland L, Brown PO, Bittner ML, Meltzer PS, Ray M, et al. Use of a cDNA microarray to analyse gene expression patterns in human cancer. Nat Genet 1996; 14:457-60. 8. Lockhart DJ, Dong H, Byrne MC, Follettie MT, Gallo MV, Chee MS, et al. Expression monitoring by hybridization to high-density oligonucleotide arrays. Nat Biotechnol 1996; 14:1675-80. 9. Service RF. Microchip arrays put DNA on the spot. Science 1998; 282:396-9. 10. Schena M, Shalon D, Davis RW, Brown PO. Quantitative monitoring of gene expression patterns with a complementary DNA microarray. Science 1995; 270:467-70. 11. Velculescu VE, Zhang L, Vogelstein B, Kinzler KW. Serial analysis of gene expression. Science 1995; 270:484-7. 12. Bittner M, Meltzer P, Chen Y, Jiang Y, Seftor E, Hendrix M, et al. Molecular classification of cutaneous malignant melanoma by gene expression profiling. Nature 2000; 406:536-40. 13. Clark EA, Golub TR, Lander ES, Hynes RO. Genomic analysis of metastasis reveals an essential role for RhoC. Nature 2000; 406:532-5. 14. Hendrix MJ, Seftor EA, Meltzer PS, Gardner LM, Hess AR, Kirschmann DA, et al. Expression and functional significance of VE-cadherin in aggressive human melanoma cells: role in vasculogenic mimicry. Proc Natl Acad Sci USA 2001; 98:8018-23. 15. Carr KM, Bittner M, Trent JM. Gene-expression profiling in human cutaneous melanoma. Oncogene 2003; 22:3076-80. 16. Seykora JT, Jih D, Elenitsas R, Horng WH, Elder DE. Gene expression profiling of melanocytic lesions. Am J Dermatopathol 2003; 25:6-11. 17. Luca M, Hunt B, Bucana CD, Johnson JP, Fidler IJ, Bar-Eli M. Direct correlation between MUC18 expression and metastatic potential of human melanoma cells. Melanoma Res 1993; 3:35-41. 18. Xie S, Luca M, Huang S, Gutman M, Reich R, Johnson JP, et al. Expression of MCAM/MUC18 by human melanoma cells leads to increased tumor growth and metastasis. Cancer Res 1997; 57:2295-303. 19. Mills L, Tellez C, Huang S, Baker C, McCarty M, Green L, et al. Fully human antibodies to MCAM/MUC18 inhibit tumor growth and metastasis of human melanoma. Cancer Res 2002; 62:5106-14. 20. Jean D, Bar-Eli M, Huang S, Xie K, Rodrigues-Lima F, Hermann J, et al. A cysteine proteinase, which cleaves human C3, the third component of complement, is involved in tumorigenicity and metastasis of human melanoma. Cancer Res 1996; 56:254-8. 21. Frade R, Rodrigues-Lima F, Huang S, Xie K, Guillaume N, Bar-Eli M. Procathepsin-L, a proteinase that cleaves human C3 (the third component of complement), confers high tumorigenic and metastatic properties to human melanoma cells. Cancer Res 1998; 58:2733-6. 22. Luca M, Huang S, Gershenwald JE, Singh RK, Reich R, Bar-Eli M. Expression of interleukin-8 by human melanoma cells up-regulates MMP-2 activity and increases tumor growth and metastasis. Am J Pathol 1997; 151:1105-13. 23. Bar-Eli M. Role of interleukin-8 in tumor growth and metastasis of human melanoma. Pathobiology 1999; 67:12-8. 24. Rosenwald A, Wright G, Chan WC, Connors JM, Campo E, Fisher RI, et al. The use of molecular profiling to predict survival after chemotherapy for diffuse large-B-cell lymphoma. N Engl J Med 2002; 346:1937-47. 25. Alizadeh AA, Eisen MB, Davis RE, Ma C, Lossos IS, Rosenwald A, et al. Distinct types of diffuse large B-cell lymphoma identified by gene expression profiling. Nature 2000; 403:503-11.
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Despite these limitations, insight into the biology of melanoma has been gained from a limited cadre of gene expression profiling studies. Although most of the genes identified to date are not melanoma-specific—including Wnt-5,12 Rho-C,13 and VE-cadherin14 —and their contributions to melanoma progression and biological significance to tumor growth and metastasis of human melanoma require additional investigation, these early landmark efforts have begun to further define the biology of melanoma (also reviewed in ref. 15). Unfortunately, recent preliminary studies involving gene expression profiling of melanocytic lesions16 has failed to identify major differences in expression profiles between nevi and melanoma, and suggests that significant additional investigation is required using multiple tools (i.e., gene expression profiling, proteomics, DNA methylation, DNA copy number, etc.). In this issue of Cancer Biology & Therapy, Dr. Becker and colleagues have used microarrays and SAGE to study the molecular profile of melanoma progression. Among the genes overexpressed in VGP melanoma tissues in the study by McDonald et al.29 and Smith et al.30 were the glycoprotein MUC18 and the cysteine protease cathepsin L. Cellular adhesion molecules of the cadherin, integrin, and immunoglobulin superfamilies are important to both growth and metastasis of many cancers, including malignant melanoma. As the malignant phenotype of primary melanoma changes from the noninvasive radial growth phase (RGP) to vertical growth phase (VGP), which has metastatic potential, so does the repertoire of cellular adhesion molecules expressed on the cell surface. For example, the cellular adhesion molecule MCAM/MUC18 confers enhanced metastatic potential and tumorigenicity to melanoma cells.17-19 We have previously demonstrated that metastatic melanoma cells overexpress cathepsin L.20 In addition to its involvement in degrading components of the extracellular matrix, cathepsin L can cleave C3, the third component of the complement. By enabling melanoma cells to inactivate complement-mediated lysis, cathepsin L also contributes to tumor growth and metastasis.21 In the studies reported here, the CST-8 gene (an inhibitor of cathepsins including cathepsin L) was downregulated in MGP (metastatic) lymph nodes compared to VGP melanoma. This may explain in part the ability of melanoma cells to metastasize to the regional lymph nodes. ST13/HiP is another gene reported in these studies to be upregulated in melanoma. The product of this gene binds to CXCR2, one of the two IL-8 receptors. Metastatic melanoma cells overexpress IL-8 and both IL-8 receptors. Binding of IL-8 to its receptors upregulate the metalloproteinase MMP-2, thus contributing to invasion and metastasis. In this sense, IL-8 serves as a very potent angiogenic factor secreted by melanoma cells.22,23 Yet to be determined, however, is how overexpression of ST13/HiP contributes to tumor growth and metastasis of human melanoma. As has been recently demonstrated for other malignancies— including lymphoma24-26 and breast cancer27—gene expression profiling of melanoma may ultimately provide us with a better tool for classification of patients with melanoma. Recent methodologic advances now allow successful and reliable isolation of small fragment mRNA from archival tissue, while technical advances permit gene expression profiling of microgram quantity specimens. These advances, including the technique of laser capture microdissection,28 will enable investigators to study both the tumor and its microenvironment from ever smaller samples. Such data will hopefully provide the clinician with an additional layer of information to improve diagnostic, prognostic, and treatment planning activities.
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26. Alizadeh A, Eisen M, Davis RE, Ma C, Sabet H, Tran T, et al. The lymphochip: a specialized cDNA microarray for the genomic-scale analysis of gene expression in normal and malignant lymphocytes. Cold Spring Harb Symp Quant Biol 1999; 64:71-8. 27. Perou CM, Sorlie T, Eisen MB, van de Rijn M, Jeffrey SS, Rees CA, et al. Molecular portraits of human breast tumours. Nature 2000; 406:747-52. 28. Bonner RF, Emmert-Buck M, Cole K, Pohida T, Chuaqui R, Goldstein S, et al. Laser capture microdissection: molecular analysis of tissue. Science 1997; 278:1481-3. 29. McDonald SL, Edington HD, Kirkwood JM, Becker D. Expression analysis of genes identified by molecular profiling of VGP melanomas and MGP melanoma-positive lymph nodes. Cancer Biol Ther 2004; 3:110-20. 30. Smith AP, Weeraratna AT, Spears JR, Meltzer PS, Becker D. SAGE identification and fluorescence imaging analysis of genes and transcripts in melanomas and precursor lesions. Cancer Biol Ther 2004; 3:104-9.
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