title: Circulating tumor cells in melanoma patients.
abstract: Circulating tumor cells (CTCs) are of recognized importance for diagnosis and prognosis of cancer patients. With melanoma, most studies do not show any clear relationship between CTC levels and stage of disease. Here, CTCs were enriched (∼400X) from blood of melanoma patients using a simple centrifugation device (OncoQuick), and 4 melanocyte target RNAs (TYR, MLANA, MITF, and MIF) were quantified using QPCR. Approximately one-third of melanoma patients had elevated MIF and MLANA transcripts (p<0.0001 and p<0.001, respectively) compared with healthy controls. In contrast, healthy controls had uniformly higher levels of TYR and MITF than melanoma patients (p<0.0001). There was a marked shift of leukocytes into the CTC-enriched fractions (a 430% increase in RNA recovery, p<0.001), and no relationship between CTC levels and stage of disease was found. CTCs were captured on microfabricated filters and cultured. Captured melanoma CTCs were large cells, and consisted of 2 subpopulations, based on immunoreactivity. One subpopulation (∼50%) stained for both pan-cytokeratin (KRT) markers and the common leukocyte marker CD-45, whereas the second subpopulation stained for only KRT. Since similar cells are described in many cancers, we also examined blood from colorectal and pancreatic cancer patients. We observed analogous results, with most captured CTCs staining for both CD-45/KRT markers (and for the monocyte differentiation marker CD-14). Our results suggest that immature melanocyte-related cells (expressing TYR and MITF RNA) may circulate in healthy controls, although they are not readily detectable without considerable enrichment. Further, as early-stage melanomas develop, immature melanocyte migration into the blood is somehow curtailed, whereas a significant proportion of patients develop elevated CTC levels (based on MIF and MLANA RNAs). The nature of the captured CTCs is consistent with literature describing leukocyte/macrophage-tumor cell fusion hybrids, and their role in metastatic progression.
authors: Gittlen Cancer Research Foundation and Department of Pathology, Hershey Medical Center, Pennsylvania State University, Hershey, Pennsylvania, USA. Gac4@psu.edu
authors: Gary A
authors: GA
authors: Clawson
authors: Eric
authors: E
authors: Kimchi
authors: Susan D
authors: SD
authors: Patrick
authors: Ping
authors: P
authors: Xin
authors: Ramdane
authors: R
authors: Harouaka
authors: Siyang
authors: S
authors: Zheng
authors: Arthur
authors: A
authors: Berg
authors: Todd
authors: T
authors: Schell
authors: Kevin F
authors: KF
authors: Staveley-O'Carroll
authors: Rogerio I
authors: RI
authors: Neves
authors: Paul J
authors: PJ
authors: Mosca
authors: Diane
authors: D
authors: Thiboutot
mesh_terms: D000328:Adult; D014408:Biomarkers, Tumor / Q000097:blood; D005260:Female; D006801:Humans; D017493:Leukocyte Common Antigens / Q000378:metabolism; D018950:Lipopolysaccharide Receptors / Q000378:metabolism; D008297:Male; D008545:Melanoma / Q000378:metabolism / Q000473:pathology*; D008856:Microscopy, Fluorescence; D008875:Middle Aged; D009367:Neoplasm Staging; D009360:Neoplastic Cells, Circulating / Q000378:metabolism / Q000473:pathology*
chemical_list: D014408:Biomarkers, Tumor; D018950:Lipopolysaccharide Receptors; D017493:Leukocyte Common Antigens