title: Involvement of TNF-alpha in enhancement of invasion and metastasis of colon 26-L5 carcinoma cells in mice by social isolation stress.
abstract: Psychosocial stress has been implicated in tumor metastasis. We have previously reported that social isolation stress exacerbated liver metastasis of colon 26-L5 by partially suppressing the cellular immunity in male Balb/c mice. To further understand the mechanism underlying the influence of isolation stress on liver metastasis, we investigated the effect of social isolation stress on tumor invasion, which is considered to be a pivotal step of tumor metastasis. The invasion and migration of tumor cells obtained from tumor nodules in the isolated mice were more markedly enhanced than that in the group-housed mice. The mRNA expression of proteolytic proteases, including matrix metalloproteinase (MMP)-2, MMP-9, membrane type 1 (MTI)-MMP, and urokinase-type plasminogen activator (u-PA), were increased in the tumor and liver tissues of the isolated mice compared with the control mice. On the other hand, production of plasma TNF-alpha and expression of hepatic TNF-alpha mRNA were elevated in the isolated mice with or without tumor burden. Increased TNF-alpha level was particularly discernible in the liver of tumor-bearing mice. Elevated positive staining for TNF-alpha was immunohistochemically observed within and around tumor mass in the liver from isolated tumor-bearing mice, compared with group-housed mice. In addition, the invasiveness of tumor cells and the expression of proteolytic enzymes, including MMP-9 and u-PA in tumor cells, were enhanced by the treatment of TNF-alpha in vitro. Thus, the data suggested that isolation stress-augmented TNF-alpha may be involved in the enhancement of tumor invasion and metastasis in part by upregulating the proteolytic enzymes such as MMPs and u-PA in tumor and liver tissues.
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: T
authors.initials: T
authors.lastname: Yamaura
authors.forename: K
authors.initials: K
authors.lastname: Murakami
authors.forename: M
authors.initials: M
authors.lastname: Ogasawara
authors.forename: K
authors.initials: K
authors.lastname: Hayashi
authors.forename: J
authors.initials: J
authors.lastname: Murata
authors.forename: I
authors.initials: I
authors.lastname: Saiki
mesh_terms: D000818:Animals; D003110:Colonic Neoplasms / Q000378:metabolism / Q000473:pathology*; D007150:Immunohistochemistry; D008099:Liver / Q000378:metabolism; D008113:Liver Neoplasms / Q000378:metabolism*; D008297:Male; D020782:Matrix Metalloproteinases / Q000378:metabolism; D051379:Mice; D008807:Mice, Inbred BALB C; D009361:Neoplasm Invasiveness; D009362:Neoplasm Metastasis; D009368:Neoplasm Transplantation; D012333:RNA, Messenger / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012934:Social Isolation; D013315:Stress, Psychological; D014407:Tumor Cells, Cultured; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism*; D014568:Urokinase-Type Plasminogen Activator / Q000378:metabolism
chemical_list: D012333:RNA, Messenger; D014409:Tumor Necrosis Factor-alpha; D014568:Urokinase-Type Plasminogen Activator; D020782:Matrix Metalloproteinases