title: Residual dormant cancer stem-cell foci are responsible for tumor relapse after antiangiogenic metronomic therapy in hepatocellular carcinoma xenografts.
abstract: Hepatocellular carcinoma (HCC) is the fifth most common solid tumor and the third leading cause of cancer-related deaths. Currently available chemotherapeutic options are not curative due in part to tumor resistance to conventional therapies. We generated orthotopic HCC mouse models in immunodeficient NOD/SCID/IL2rγ null mice by injection of human alpha-feto protein (hAFP)- and/or luciferase-expressing HCC cell lines and primary cells from patients, where tumor growth and spread can be accurately monitored in a non-invasive way. In this model, low-dose metronomic administration of cyclophosphamide (LDM-CTX) caused complete regression of the tumor mass. A significant increase in survival (P<0.0001), reduced aberrant angiogenesis and hyperproliferation, and decrease in the number of circulating tumor cells were found in LDM-CTX-treated animals, in comparison with untreated mice. Co-administration of LDM-CTX with anti-VEGF therapy further improved the therapeutic efficacy. However, the presence of residual circulating hAFP levels suggested that some tumor cells were still present in livers of treated mice. Immunohistochemistry revealed that those cells had a hAFP+/CD13+/PCNA- phenotype, suggesting that they were dormant cancer stem cells (CSC). Indeed, discontinuation of therapy resulted in tumor regrowth. Moreover, in-vitro LDM-CTX treatment reduced hepatosphere formation in both number and size, and the resulting spheres were enriched in CD13+ cells indicating that these cells were particularly resistant to therapy. Co-treatment of the CD13-targeting drug, bestatin, with LDM-CTX leads to slower tumor growth and a decreased tumor volume. Therefore, combining a CD13 inhibitor, which targets the CSC-like population, with LDM-CTX chemotherapy may be used to eradicate minimal residual disease and improve the treatment of liver cancer.
authors.affiliation: Laboratory of Hematology-Oncology, European Institute of Oncology, Milan, Italy.
authors.forename: Ines
authors.initials: I
authors.lastname: Martin-Padura
authors.forename: Paola
authors.initials: P
authors.lastname: Marighetti
authors.forename: Alice
authors.initials: A
authors.lastname: Agliano
authors.forename: Federico
authors.initials: F
authors.lastname: Colombo
authors.forename: Leyre
authors.initials: L
authors.lastname: Larzabal
authors.forename: Miriam
authors.initials: M
authors.lastname: Redrado
authors.forename: Anne-Marie
authors.initials: AM
authors.lastname: Bleau
authors.forename: Celia
authors.initials: C
authors.lastname: Prior
authors.forename: Francesco
authors.initials: F
authors.lastname: Bertolini
authors.forename: Alfonso
authors.initials: A
authors.lastname: Calvo
mesh_terms: D059250:Administration, Metronomic; D020533:Angiogenesis Inhibitors / Q000008:administration & dosage; D000818:Animals; D018906:Antineoplastic Agents, Alkylating / Q000008:administration & dosage; D000971:Antineoplastic Combined Chemotherapy Protocols / Q000008:administration & dosage*; D018826:CD13 Antigens / Q000037:antagonists & inhibitors; D045744:Cell Line, Tumor; D003520:Cyclophosphamide / Q000008:administration & dosage; D004357:Drug Synergism; D006801:Humans; D007930:Leucine / Q000008:administration & dosage / Q000031:analogs & derivatives; D008114:Liver Neoplasms, Experimental / Q000188:drug therapy* / Q000473:pathology* / Q000503:physiopathology; D008297:Male; D051379:Mice; D016688:Mice, Inbred NOD; D018345:Mice, Knockout; D016513:Mice, SCID; D018365:Neoplasm, Residual / Q000473:pathology; D014411:Neoplastic Stem Cells / Q000187:drug effects / Q000473:pathology* / Q000502:physiology; D018874:Spheroids, Cellular / Q000187:drug effects / Q000473:pathology; D042461:Vascular Endothelial Growth Factor A / Q000037:antagonists & inhibitors; D023041:Xenograft Model Antitumor Assays
chemical_list: D020533:Angiogenesis Inhibitors; D018906:Antineoplastic Agents, Alkylating; C467484:VEGFA protein, human; D042461:Vascular Endothelial Growth Factor A; D003520:Cyclophosphamide; D018826:CD13 Antigens; D007930:Leucine; C012211:ubenimex