title: Induction of metastatic cancer stem cells from the NK/LAK-resistant floating, but not adherent, subset of the UP-LN1 carcinoma cell line by IFN-γ.
abstract: As an advanced status of cancer stem cells (CSCs), metastatic CSCs (mCSCs) have been proposed to be the essential seeds that initiate tumor metastasis. However, the biology of mCSCs is poorly understood. In this study, we used a lymph node (LN) metastatic CEA-producing carcinoma cell line, UP-LN1, characterized by the persistent appearance of adherent (A) and floating (F) cells in culture, to determine the distribution of CSCs and mechanisms for the induction of mCSCs. F and A cells displayed distinct phenotypes, CD44(high)/CD24(low) and CD44(low)/CD24(high), respectively. The CSC-rich nature of F cells was typified by stronger expression of multiple drug resistance genes and a 7.8-fold higher frequency of tumor-initiating cells in NOD/SCID mice when compared with A cells. F cells showed a greater depression in HLA class I expression and an extreme resistance to NK/LAK-mediated cytolysis. Moreover, the NK/LAK-resistant F cells were highly susceptible to IFN-γ-mediated induction of surface CXCR4, with concomitant downregulation of cytoplasmic CXCL12 expression, whereas these two parameters remained essentially unchanged in NK/LAK-sensitive A cells. Following the induction of surface CXCR4, enhanced migratory/invasive potential of F cells was demonstrated by in vitro assays. Confocal immunofluorescence microscopy showed the two distinct phenotypes of F and A cells could be correspondingly identified in monodispersed and compact tumor cell areas within the patient's LN tumor lesion. In response to IFN-γ or activated NK/LAK cells, the CXCR4(+) mCSCs could be only induced from the CSCs, which were harbored in the highly tumorigenic CD44(high)/CD24(low) F subset. Our results revealed the complexity and heterogeneity of the CSC of this cell line/tumor and the differential immunomodulatory roles of F and A cells. A better understanding of the interactions among different classes of CSCs and their niches may assist us in eradicating the CSCs/mCSCs through targeted immunotherapy, chemotherapy, or both.
authors.affiliation: Graduate Institute of Biomedical Sciences, Chang Gung University, Taoyuan, Taiwan.
authors.forename: Hung-Chang
authors.initials: HC
authors.lastname: Chen
authors.forename: Andy Shau-Bin
authors.initials: AS
authors.lastname: Chou
authors.forename: Yu-Chen
authors.initials: YC
authors.lastname: Liu
authors.forename: Chin-Hsuan
authors.initials: CH
authors.lastname: Hsieh
authors.forename: Chen-Chen
authors.initials: CC
authors.lastname: Kang
authors.forename: See-Tong
authors.initials: ST
authors.lastname: Pang
authors.forename: Chi-Tai
authors.initials: CT
authors.lastname: Yeh
authors.forename: Hui-Ping
authors.initials: HP
authors.lastname: Liu
authors.forename: Shuen-Kuei
authors.initials: SK
authors.lastname: Liao
mesh_terms: D000818:Animals; D051927:CD24 Antigen / Q000378:metabolism; D002272:Carcinoembryonic Antigen / Q000378:metabolism; D015197:Carcinogenicity Tests; D002277:Carcinoma / Q000378:metabolism / Q000473:pathology* / Q000556:secondary; D045744:Cell Line, Tumor; D054377:Chemokine CXCL12 / Q000378:metabolism; D018432:Drug Resistance, Multiple / Q000235:genetics; D019008:Drug Resistance, Neoplasm / Q000235:genetics; D015870:Gene Expression; D015395:Histocompatibility Antigens Class I / Q000378:metabolism; D006801:Humans; D018960:Hyaluronan Receptors / Q000378:metabolism; D016130:Immunophenotyping; D007371:Interferon-gamma / Q000494:pharmacology*; D015979:Killer Cells, Lymphokine-Activated / Q000187:drug effects* / Q000378:metabolism; D008207:Lymphatic Metastasis; D051379:Mice; D016688:Mice, Inbred NOD; D016513:Mice, SCID; D009368:Neoplasm Transplantation; D014411:Neoplastic Stem Cells / Q000378:metabolism / Q000473:pathology*; D019718:Receptors, CXCR4 / Q000378:metabolism; D014183:Transplantation, Heterologous
chemical_list: D051927:CD24 Antigen; C515255:CXCL12 protein, human; D002272:Carcinoembryonic Antigen; D054377:Chemokine CXCL12; D015395:Histocompatibility Antigens Class I; D018960:Hyaluronan Receptors; D019718:Receptors, CXCR4; D007371:Interferon-gamma