Identification and characterization of ovarian cancer-initiating cells from primary human tumors.
The objective of this study was to identify and characterize a self-renewing subpopulation of human ovarian tumor cells (ovarian cancer-initiating cells, OCICs) fully capable of serial propagation of their original tumor phenotype in animals. Ovarian serous adenocarcinomas were disaggregated and subjected to growth conditions selective for self-renewing, nonadherent spheroids previously shown to derive from tissue stem cells. To affirm the existence of OCICs, xenoengraftment of as few as 100 dissociated spheroid cells allowed full recapitulation of the original tumor (grade 2/grade 3 serous adenocarcinoma), whereas >10(5) unselected cells remained nontumorigenic. Stemness properties of OCICs (under stem cell-selective conditions) were further established by cell proliferation assays and reverse transcription-PCR, demonstrating enhanced chemoresistance to the ovarian cancer chemotherapeutics cisplatin or paclitaxel and up-regulation of stem cell markers (Bmi-1, stem cell factor, Notch-1, Nanog, nestin, ABCG2, and Oct-4) compared with parental tumor cells or OCICs under differentiating conditions. To identify an OCIC cell surface phenotype, spheroid immunostaining showed significant up-regulation of the hyaluronate receptor CD44 and stem cell factor receptor CD117 (c-kit), a tyrosine kinase oncoprotein. Similar to sphere-forming OCICs, injection of only 100 CD44(+)CD117(+) cells could also serially propagate their original tumors, whereas 10(5) CD44(-)CD117(-) cells remained nontumorigenic. Based on these findings, we assert that epithelial ovarian cancers derive from a subpopulation of CD44(+)CD117(+) cells, thus representing a possible therapeutic target for this devastating disease.
Zhang
Shu
S
Medical Sciences, Indiana University School of Medicine, Bloomington, Indiana 47405, USA.
Balch
Curt
C
Chan
Michael W
MW
Lai
Hung-Cheng
HC
Matei
Daniela
D
Schilder
Jeanne M
JM
Yan
Pearlly S
PS
Huang
Tim H-M
TH
Nephew
Kenneth P
KP
D002448:Cell Adhesion; D002469:Cell Separation; D005260:Female; D005455:Fluorescent Antibody Technique; D006801:Humans; D014411:Neoplastic Stem Cells / Q000473:pathology*; D010051:Ovarian Neoplasms / Q000473:pathology*; D020133:Reverse Transcriptase Polymerase Chain Reaction