Isolation and characterization of spheroid cells from human malignant melanoma cell line WM-266-4.
OBJECTIVE
Spheroid cells which can grow as nonattached spheroids in vitro culture condition are considered as tumor-initiating cells that have properties similar to those of stem cells. However, the existence of spheroid cells in WM-266-4, a human malignant metastatic melanoma cell line, has not yet been reported.


METHODS
Accordingly, we investigated whether WM-266-4 can form spheroids, and characterized these spheroids using qRT-PCR, histology, immunohistochemistry and xenograft.


RESULTS
WM-266-4 contains a small subpopulation of cells that grow as spheroids and express genes strongly related to tumor malignancy and stem-like factors. Second, histological analysis of the spheres revealed that they consist of 300-400 round cells per sphere with a high karyoplasmic ratio. They have a basophilic cytoplasm and are highly pleomorphic in size, and sometimes multinucleated and giant. Third, although there were differences between the spheroid and bulk cells, they both have high tumorigenic potential, as both cell types formed a tumor mass upon injection of only 100 cells in nude mice.


CONCLUSIONS
We characterized the spheroid cells in an established melanoma cell line. We suggest that enriched spheroid cells might contain more dedifferentiated progenitor cells, but we could not conclude spheroid cells are cancer stem cells.
Na
Y R
YR
Department of Laboratory Animal Medicine, College of Veterinary Medicine and KRF Zoonotic Disease Priority Research Institute, Seoul National University, Seoul, Republic of Korea.
Seok
S H
SH
Kim
D J
DJ
Han
J H
JH
Kim
T H
TH
Jung
H
H
Lee
B H
BH
Park
J H
JH
D000071916:AC133 Antigen; D000070997:ATP Binding Cassette Transporter, Subfamily G, Member 2; D018528:ATP-Binding Cassette Transporters / Q000235:genetics; D000818:Animals; D015703:Antigens, CD / Q000235:genetics; D000951:Antigens, Neoplasm / Q000032:analysis; D014408:Biomarkers, Tumor / Q000032:analysis; D045744:Cell Line, Tumor; D049109:Cell Proliferation; D005260:Female; D015972:Gene Expression Regulation, Neoplastic; D006023:Glycoproteins / Q000235:genetics; D018398:Homeodomain Proteins / Q000235:genetics; D006801:Humans; D007150:Immunohistochemistry; D007381:Intermediate Filament Proteins / Q000032:analysis / Q000235:genetics; D058965:MART-1 Antigen; D008545:Melanoma / Q000235:genetics / Q000378:metabolism / Q000473:pathology*; D008546:Melanoma, Experimental / Q000235:genetics / Q000378:metabolism / Q000473:pathology*; D051379:Mice; D008819:Mice, Nude; D009363:Neoplasm Proteins / Q000032:analysis / Q000235:genetics; D009419:Nerve Tissue Proteins / Q000032:analysis / Q000235:genetics; D064231:Nestin; D009687:Nuclear Proteins / Q000235:genetics; D010455:Peptides / Q000235:genetics; D063150:Polycomb Repressive Complex 1; D011518:Proto-Oncogene Proteins / Q000235:genetics; D012097:Repressor Proteins / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D018874:Spheroids, Cellular / Q000378:metabolism / Q000473:pathology*; D013997:Time Factors; D014183:Transplantation, Heterologous; D047368:Tumor Burden; D025521:Tumor Suppressor Proteins / Q000235:genetics; D040321:Vascular Endothelial Growth Factor Receptor-3 / Q000235:genetics; D051153:Wnt Proteins / Q000235:genetics; D000071818:Wnt-5a Protein; D000098551:Prospero-Related Homeobox 1 Protein
C116614:ABCG2 protein, human; D000071916:AC133 Antigen; D000070997:ATP Binding Cassette Transporter, Subfamily G, Member 2; D018528:ATP-Binding Cassette Transporters; D015703:Antigens, CD; D000951:Antigens, Neoplasm; C069077:BMI1 protein, human; D014408:Biomarkers, Tumor; D006023:Glycoproteins; D018398:Homeodomain Proteins; D007381:Intermediate Filament Proteins; D058965:MART-1 Antigen; C548667:MLANA protein, human; C548668:Mlana protein, mouse; C577484:NES protein, human; D009363:Neoplasm Proteins; D009419:Nerve Tissue Proteins; C577485:Nes protein, mouse; D064231:Nestin; D009687:Nuclear Proteins; D010455:Peptides; D011518:Proto-Oncogene Proteins; D012097:Repressor Proteins; D025521:Tumor Suppressor Proteins; C085389:WNT5A protein, human; D051153:Wnt Proteins; D000071818:Wnt-5a Protein; D000098551:Prospero-Related Homeobox 1 Protein; D063150:Polycomb Repressive Complex 1; D040321:Vascular Endothelial Growth Factor Receptor-3