title: Limited genomic heterogeneity of circulating melanoma cells in advanced stage patients.
abstract: Purpose. Circulating melanoma cells (CMCs) constitute a potentially important representation of time-resolved tumor biology in patients. To date, genomic characterization of CMCs has been limited due to the lack of a robust methodology capable of identifying them in a format suitable for downstream characterization. Here, we have developed a methodology to detect intact CMCs that enables phenotypic, morphometric and genomic analysis at the single cell level. Experimental design. Blood samples from 40 metastatic melanoma patients and 10 normal blood donors were prospectively collected. A panel of 7 chondroitin sulfate proteoglycan 4 (CSPG4)-specific monoclonal antibodies (mAbs) was used to immunocytochemically label CMCs. Detection was performed by automated digital fluorescence microscopy and multi-parametric computational analysis. Individual CMCs were captured by micromanipulation for whole genome amplification and copy number variation (CNV) analysis. Results. Based on CSPG4 expression and nuclear size, 1-250 CMCs were detected in 22 (55%) of 40 metastatic melanoma patients (0.5-371.5 CMCs ml(-1)). Morphometric analysis revealed that CMCs have a broad spectrum of morphologies and sizes but exhibit a relatively homogeneous nuclear size that was on average 1.5-fold larger than that of surrounding PBMCs. CNV analysis of single CMCs identified deletions of CDKN2A and PTEN, and amplification(s) of TERT, BRAF, KRAS and MDM2. Furthermore, novel chromosomal amplifications in chr12, 17 and 19 were also found. Conclusions. Our findings show that CSPG4 expressing CMCs can be found in the majority of advanced melanoma patients. High content analysis of this cell population may contribute to the design of effective personalized therapies in patients with melanoma.
authors.affiliation: Department of Cell and Molecular Biology, The Scripps Research Institute, La Jolla, CA, USA.
authors.forename: Carmen
authors.initials: C
authors.lastname: Ruiz
authors.forename: Julia
authors.initials: J
authors.lastname: Li
authors.forename: Madelyn S
authors.initials: MS
authors.lastname: Luttgen
authors.forename: Anand
authors.initials: A
authors.lastname: Kolatkar
authors.forename: Jude T
authors.initials: JT
authors.lastname: Kendall
authors.forename: Edna
authors.initials: E
authors.lastname: Flores
authors.forename: Zheng
authors.initials: Z
authors.lastname: Topp
authors.forename: Wolfram E
authors.initials: WE
authors.lastname: Samlowski
authors.forename: Edward
authors.initials: E
authors.lastname: McClay
authors.forename: Kelly
authors.initials: K
authors.lastname: Bethel
authors.forename: Soldano
authors.initials: S
authors.lastname: Ferrone
authors.forename: James
authors.initials: J
authors.lastname: Hicks
authors.forename: Peter
authors.initials: P
authors.lastname: Kuhn
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D045744:Cell Line, Tumor; D005260:Female; D015894:Genome, Human / Q000235:genetics*; D023281:Genomics; D006801:Humans; D008297:Male; D008545:Melanoma / Q000235:genetics* / Q000473:pathology*; D008875:Middle Aged; D009367:Neoplasm Staging; D009360:Neoplastic Cells, Circulating / Q000473:pathology*