title: Enhanced experimental tumor metastasis with age in senescence-accelerated mouse.
abstract: Tumor metastasis is affected by the host immune surveillance system. Since aging may attenuate the host immune potential, the experimental tumor metastasis may be enhanced with age. In the present study, we investigated this alteration of experimental tumor metastasis with age. We used senescence-accelerated mice prone 10 (SAMP10) as a model of aged animals. Natural killer cell (NK) activity, as an indicator of immune surveillance potential, in 8-month-old (aged) SAMP10 mice was observed to be much lower than that in 2-month-old (young) mice. When we examined the in vivo trafficking of lung-metastatic K1735M2 melanoma cells in SAMP10 with positron emission tomography (PET), K1735M2 cells labeled with [2-18F]2-deoxy-2-fluoro-D-glucose ([18F]FDG) were observed in both young and aged SAMP10 just after injection of the cells, whereas the clearance of 18F from the lungs was retarded in aged animals. The accumulation of 5-[125 I]iodo-2'-deoxyuridine ([125 I]IUdR)-labeled K1735M2 cells in the lungs of SAMP10 at 24 h after injection was significantly higher in aged mice. Corresponding to these results, the number of metastatic colonies in the lung was larger in the aged SAMP10 of the experimental tumor metastasis model. The present study demonstrated that the aging process produced a susceptible environment allowing the tumor cells to metastasize due to decrease in the host immune surveillance potential with age.
authors.affiliation: Department of Medical Biochemistry and Global COE Program, School of Pharmaceutical Sciences, University of Shizuoka, 52-1 Yada, Suruga-ku, Shizuoka, Shizuoka 422-8526, Japan.
authors.forename: Kosuke
authors.initials: K
authors.lastname: Shimizu
authors.forename: Naomi
authors.initials: N
authors.lastname: Kinouchi Shimizu
authors.forename: Tomohiro
authors.initials: T
authors.lastname: Asai
authors.forename: Hideo
authors.initials: H
authors.lastname: Tsukada
authors.forename: Naoto
authors.initials: N
authors.lastname: Oku
mesh_terms: D000375:Aging / Q000235:genetics* / Q000473:pathology*; D000818:Animals; D045744:Cell Line, Tumor; D019788:Fluorodeoxyglucose F18; D007065:Idoxuridine; D007157:Immunologic Surveillance; D008175:Lung Neoplasms / Q000276:immunology / Q000473:pathology / Q000556:secondary; D008546:Melanoma, Experimental / Q000473:pathology; D051379:Mice; D009362:Neoplasm Metastasis / Q000000981:diagnostic imaging / Q000235:genetics* / Q000473:pathology*; D009368:Neoplasm Transplantation; D019384:Nucleic Acid Synthesis Inhibitors; D049268:Positron-Emission Tomography; D019275:Radiopharmaceuticals
chemical_list: D019384:Nucleic Acid Synthesis Inhibitors; D019275:Radiopharmaceuticals; D019788:Fluorodeoxyglucose F18; D007065:Idoxuridine