title: Social isolation stress impairs the resistance of mice to experimental liver metastasis of murine colon 26-L5 carcinoma cells.
abstract: Our previous study has demonstrated that the exposure of male BALB/c mice to social isolation stress caused a suppressed immune response and enhanced liver metastasis of colon 26-L5 carcinoma cells. To more precisely understand the influence of psychosocial factors on the metastatic process, here we have investigated the effect of social isolation stress on the vulnerability of the host to develop liver metastasis of colon 26-L5 cells, including the time span and incidence of metastatic formation, survival time and chemotherapy response. Isolation stress decreased the time period required for the metastasis formation relative to that in controls. On day 7 after the tumor injection, the 75% incidence of tumor metastasis in the stressed mice was 5 times the 15% incidence in the unstressed mice. When exposed to the challenge of lower cell numbers (0.025, 0.05, 0.1 x 10(4)/mouse) of colon 26-L5 cells, mice subjected to isolation stress developed an elevated incidence of metastasis (33.3, 66.6, and 100%, respectively) as compared with the controls (0, 33.3 and 50%, respectively). The survival time following the tumor inoculation was also shorter in the stressed mice (21.83 +/- 1.59d) than in the control mice (24.08 +/- 1.68 d). Furthermore, the response of liver metastasis to chemotherapy consisting of 2 mg/kg cisplatin (CDDP) was worse in the stressed mice than that in unstressed mice. These findings suggested that social isolation stress could significantly impair the resistance of mice to the development of metastasis.
authors.affiliation: Department of Pathogenic Biochemistry, Institute of Natural Medicine, Toyama Medical and Pharmaceutical University, Japan.
authors.forename: W
authors.initials: W
authors.lastname: Wu
authors.forename: J
authors.initials: J
authors.lastname: Murata
authors.forename: K
authors.initials: K
authors.lastname: Hayashi
authors.forename: T
authors.initials: T
authors.lastname: Yamaura
authors.forename: N
authors.initials: N
authors.lastname: Mitani
authors.forename: I
authors.initials: I
authors.lastname: Saiki
mesh_terms: D000818:Animals; D000970:Antineoplastic Agents / Q000627:therapeutic use; D002945:Cisplatin / Q000627:therapeutic use; D003110:Colonic Neoplasms / Q000188:drug therapy / Q000473:pathology*; D007113:Immunity, Innate / Q000502:physiology; D008113:Liver Neoplasms / Q000188:drug therapy / Q000473:pathology* / Q000556:secondary*; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D009368:Neoplasm Transplantation; D012934:Social Isolation; D013315:Stress, Psychological / Q000473:pathology*; D016019:Survival Analysis; D014407:Tumor Cells, Cultured
chemical_list: D000970:Antineoplastic Agents; D002945:Cisplatin