title: Side population cells of pancreatic cancer show characteristics of cancer stem cells responsible for resistance and metastasis.
abstract: Cancer stem cells (CSCs) have been proposed to underlie the initiation and maintenance of tumor growth and the development of chemoresistance in solid tumors. The identification and role of these important cells in pancreatic cancer remains controversial. Here, we isolate side population (SP) cells from the highly aggressive and metastatic human pancreatic cancer cell line L3.6pl and evaluate their potential role as models for CSCs. SP cells were isolated following Hoechst 33342 staining of L3.6pl cells. SP, non-SP, and unsorted L3.6pl cells were orthotopically xenografted into the pancreas of nude mice and tumor growth observed. RNA was analyzed by whole genome array and pathway mapping was performed. Drug resistant variants of L3.6pl were developed and examined for SP proportions and evaluated for surface expression of known CSC markers. A distinct SP with the ability to self-renew and differentiate into non-SP cells was isolated from L3.6pl (0.9 % ± 0.22). SP cells showed highly tumorigenic and metastatic characteristics after orthotopic injection. Transcriptomic analysis identified modulation of gene networks linked to tumorigenesis, differentiation, and metastasization in SP cells relative to non-SP cells. Wnt, NOTCH, and EGFR signaling pathways associated with tumor stem cells were altered in SP cells. When cultured with increasing concentrations of gemcitabine, the proportion of SP cells, ABCG2(+), and CD24(+) cells were significantly enriched, whereas 5-fluorouracil (5-FU) treatment lowered the percentage of SP cells. SP cells were distinct from cells positive for previously postulated pancreatic CSC markers. The Hoechst-induced side population in L3.6pl cells comprises a subset of tumor cells displaying aggressive growth and metastasization, increased gemcitabine-, but not 5-FU resistance. The cells may act as a partial model for CSC biology.
authors.affiliation: Department of Surgery, University of Munich, Campus Großhadern, Munich, Germany.
authors.forename: Hanno
authors.initials: H
authors.lastname: Niess
authors.forename: Peter
authors.initials: P
authors.lastname: Camaj
authors.forename: Andrea
authors.initials: A
authors.lastname: Renner
authors.forename: Ivan
authors.initials: I
authors.lastname: Ischenko
authors.forename: Yue
authors.initials: Y
authors.lastname: Zhao
authors.forename: Stefan
authors.initials: S
authors.lastname: Krebs
authors.forename: Josef
authors.initials: J
authors.lastname: Mysliwietz
authors.forename: Carsten
authors.initials: C
authors.lastname: Jäckel
authors.forename: Peter J
authors.initials: PJ
authors.lastname: Nelson
authors.forename: Helmut
authors.initials: H
authors.lastname: Blum
authors.forename: Karl-Walter
authors.initials: KW
authors.lastname: Jauch
authors.forename: Joachim W
authors.initials: JW
authors.lastname: Ellwart
authors.forename: Christiane J
authors.initials: CJ
authors.lastname: Bruns
mesh_terms: D000230:Adenocarcinoma / Q000188:drug therapy* / Q000235:genetics / Q000378:metabolism / Q000556:secondary; D000818:Animals; D000964:Antimetabolites, Antineoplastic / Q000494:pharmacology*; D014408:Biomarkers, Tumor / Q000235:genetics / Q000378:metabolism; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D002469:Cell Separation; D003841:Deoxycytidine / Q000031:analogs & derivatives* / Q000494:pharmacology; D019008:Drug Resistance, Neoplasm / Q000235:genetics; D005472:Fluorouracil / Q000494:pharmacology*; D020869:Gene Expression Profiling / Q000379:methods; D015972:Gene Expression Regulation, Neoplastic; D053263:Gene Regulatory Networks; D006801:Humans; D008297:Male; D008807:Mice, Inbred BALB C; D008819:Mice, Nude; D014411:Neoplastic Stem Cells / Q000187:drug effects* / Q000378:metabolism / Q000473:pathology; D020411:Oligonucleotide Array Sequence Analysis; D010190:Pancreatic Neoplasms / Q000188:drug therapy* / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D010641:Phenotype; D058985:Side-Population Cells / Q000187:drug effects* / Q000378:metabolism / Q000473:pathology; D015398:Signal Transduction / Q000187:drug effects; D013997:Time Factors; D023041:Xenograft Model Antitumor Assays; D000093542:Gemcitabine
chemical_list: D000964:Antimetabolites, Antineoplastic; D014408:Biomarkers, Tumor; D003841:Deoxycytidine; D005472:Fluorouracil; D000093542:Gemcitabine