* Osteopontin mediates tumorigenic transformation of a preneoplastic murine cell line by suppressing anoikis: an Arg-Gly-Asp-dependent-focal adhesion kinase-caspase-8 axis.
- Osteopontin (OPN), an adhesive, matricellular glycoprotein, is a rate-limiting factor in tumor promotion of skin carcinogenesis. With a tumor promotion model, the JB6 Cl41.5a cell line, we have shown that suppressing 12-O-tetradecanoylphorbol-13-acetate (TPA)-induced OPN expression markedly inhibits TPA-induced colony formation in soft agar, an assay indicative of tumorigenic transformation. Further, the addition of exogenous OPN promotes colony formation of these cells. These findings support a function of OPN in mediating TPA-induced neoplastic transformation of JB6 cells. In regard to the mechanism of action by OPN, we hypothesized that, for JB6 cells grown in soft-agar, secreted OPN induced by TPA stimulates cell proliferation and/or prevents anoikis to facilitate TPA-induced colony formation. Analyses of cell cycle and cyclin D1 expression, and direct cell counting of JB6 cells treated with OPN indicate that OPN does not stimulate cell proliferation relative to non-treated controls. Instead, at 24 h, OPN decreases anoikis by 41%, as assessed by annexin V assays. Further, in suspended cells OPN suppresses caspase-8 activation, which is mediated specifically through its RGD-cell binding motif that transduces signals through integrin receptors. Transfection studies with wild-type and mutant focal adhesion kinases (FAK) and Western blot analyses suggest that OPN suppression of caspase-8 activation is mediated through phosphorylation of FAK at Tyr(861). In summary, these studies indicate that induced OPN is a microenvironment modulator that facilitates tumorigenic transformation of JB6 cells by inhibiting anoikis through its RGD-dependent suppression of caspase-8 activity, which is mediated in part through the activation of FAK at Tyr(861).
=>1.機能, 関数, 役割, 働き, 2.機能する, 作用する, 働く, 役目を果たす, 3.社交的会合, パーティー, 儀式
Overview of noun function
The noun function has 7 senses (first 3 from tagged texts)
1. (43) function, mathematical function, single-valued function, map, mapping -- ((mathematics) a
mathematical relation such that each element of a given set (the domain of the function) is
associated with an element of another set (the range of the function))
2. (24) function, purpose, role, use -- (what something is used for; "the function of an auger is to
bore holes"; "ballet is beautiful but what use is it?")
3. (7) function, office, part, role -- (the actions and activities assigned to or required or
expected of a person or group; "the function of a teacher"; "the government must do its part"; "play
its role")
4. function -- (a relation such that one thing is dependent on another; "height is a function of
age"; "price is a function of supply and demand")
5. function -- (a formal or official social gathering or ceremony; "it was a black-tie function")
6. affair, occasion, social occasion, function, social function -- (a vaguely specified social
event; "the party was quite an affair"; "an occasion arranged to honor the president"; "a seemingly
endless round of social functions")
7. routine, subroutine, subprogram, procedure, function -- (a set sequence of steps, part of larger
computer program)
Overview of verb function
The verb function has 3 senses (first 3 from tagged texts)
1. (9) function, work, operate, go, run -- (perform as expected when applied; "The washing machine
won't go unless it's plugged in"; "Does this old car still run well?"; "This old radio doesn't work
anymore")
2. (3) serve, function -- (serve a purpose, role, or function; "The tree stump serves as a table";
"The female students served as a control group"; "This table would serve very well"; "His freedom
served him well"; "The table functions as a desk")
3. (1) officiate, function -- (perform duties attached to a particular office or place or function;
"His wife officiated as his private secretary")
--- WordNet end ---