title: Circulating Melanoma Cell Subpopulations: Their Heterogeneity and Differential Responses to Treatment.
abstract: Metastatic melanoma is a highly heterogeneous tumor; thus, methods to analyze tumor-derived cells circulating in blood should address this diversity. Taking this into account, we analyzed, using multiparametric flow cytometry, the co-expression of the melanoma markers melanoma cell adhesion molecule and melanoma-associated chondroitin sulphate proteoglycan and the tumor-initiating markers ATP-binding cassette sub-family B member 5 (ABCB5), CD271, and receptor activator of NF-κβ (RANK) in individual circulating tumor cells (CTCs) from 40 late-stage (III-IV) and 16 early-stage (I-II) melanoma patients. CTCs were heterogeneous within and between patients, with limited co-expression between the five markers analyzed. Analysis of patient matched blood and metastatic tumors revealed that ABCB5 and RANK subpopulations are more common among CTCs than in the solid tumors, suggesting a preferential selection for these cells in circulation. Pairwise comparison of CTC subpopulations longitudinally before and 6-13 weeks after treatment initiation showed that the percentage of RANK(+) CTCs significantly increased in the patients undergoing targeted therapy (N=16, P<0.01). Moreover, the presence of ⩾5 RANK(+) CTCs in the blood of patients undergoing targeted therapies was prognostic of shorter progression-free survival (hazards ratio 8.73, 95% confidence interval 1.82-41.75, P<0.01). Taken together, our results provide evidence of the heterogeneity among CTC subpopulations in melanoma and the differential response of these subpopulations to targeted therapy.
authors.affiliation: School of Medical Sciences, Edith Cowan University, Perth, Washington, Australia. Electronic address: e.gray@ecu.edu.au.
authors.forename: Elin S
authors.initials: ES
authors.lastname: Gray
authors.affiliation: School of Medical Sciences, Edith Cowan University, Perth, Washington, Australia.
authors.forename: Anna L
authors.initials: AL
authors.lastname: Reid
authors.affiliation: Department of Medical Oncology, Sir Charles Gairdner Hospital, Nedlands, Washington, Australia.
authors.forename: Samantha
authors.initials: S
authors.lastname: Bowyer
authors.affiliation: School of Medical Sciences, Edith Cowan University, Perth, Washington, Australia.
authors.forename: Leslie
authors.initials: L
authors.lastname: Calapre
authors.affiliation: Department of Medical Oncology, Sir Charles Gairdner Hospital, Nedlands, Washington, Australia.
authors.forename: Kelvin
authors.initials: K
authors.lastname: Siew
authors.affiliation: School of Medical Sciences, Edith Cowan University, Perth, Washington, Australia.
authors.forename: Robert
authors.initials: R
authors.lastname: Pearce
authors.affiliation: Level 1 Melanoma Skin Cancer Clinic, Fremantle, Washington, Australia.
authors.forename: Lester
authors.initials: L
authors.lastname: Cowell
authors.affiliation: School of Medical Sciences, Edith Cowan University, Perth, Washington, Australia; Transplantation Research Program, Boston Children's Hospital and Department of Dermatology, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts, USA.
authors.forename: Markus H
authors.initials: MH
authors.lastname: Frank
authors.affiliation: Department of Medical Oncology, Sir Charles Gairdner Hospital, Nedlands, Washington, Australia; School of Medicine and Pharmacology, University of Western Australia, Crawley, Washington, Australia.
authors.forename: Michael
authors.initials: M
authors.lastname: Millward
authors.affiliation: School of Medical Sciences, Edith Cowan University, Perth, Washington, Australia; School of Pathology and Laboratory Medicine, University of Western Australia, Crawley, Washington, Australia.
authors.forename: Mel
authors.initials: M
authors.lastname: Ziman
mesh_terms: D018435:ATP Binding Cassette Transporter, Subfamily B; D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1 / Q000378:metabolism; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D014408:Biomarkers, Tumor / Q000378:metabolism*; D051929:CD146 Antigen / Q000378:metabolism; D045744:Cell Line, Tumor; D002478:Cells, Cultured; D011508:Chondroitin Sulfate Proteoglycans / Q000378:metabolism; D004358:Drug Therapy; D005260:Female; D006801:Humans; D007167:Immunotherapy; D007211:Indoles / Q000494:pharmacology / Q000627:therapeutic use; D008297:Male; D008545:Melanoma / Q000188:drug therapy* / Q000378:metabolism* / Q000473:pathology; D008565:Membrane Proteins / Q000378:metabolism; D008875:Middle Aged; D009367:Neoplasm Staging; D009360:Neoplastic Cells, Circulating / Q000187:drug effects* / Q000378:metabolism* / Q000473:pathology; D009419:Nerve Tissue Proteins / Q000378:metabolism; D053246:Receptor Activator of Nuclear Factor-kappa B / Q000378:metabolism; D017475:Receptors, Nerve Growth Factor / Q000378:metabolism; D012878:Skin Neoplasms / Q000188:drug therapy* / Q000378:metabolism* / Q000473:pathology; D013449:Sulfonamides / Q000494:pharmacology / Q000627:therapeutic use; D000077484:Vemurafenib; D000099216:Chondroitin Sulfate Proteoglycan 4
chemical_list: D018435:ATP Binding Cassette Transporter, Subfamily B; D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; D014408:Biomarkers, Tumor; D051929:CD146 Antigen; D011508:Chondroitin Sulfate Proteoglycans; D007211:Indoles; D008565:Membrane Proteins; D009419:Nerve Tissue Proteins; D053246:Receptor Activator of Nuclear Factor-kappa B; D017475:Receptors, Nerve Growth Factor; D013449:Sulfonamides; D000077484:Vemurafenib; C480744:ABCB5 protein, human; C101390:CSPG4 protein, human; D000099216:Chondroitin Sulfate Proteoglycan 4; C484065:NGFR protein, human; C505686:TNFRSF11A protein, human
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