Rapid adhesion and spread of non-adherent colon cancer Colo201 cells induced by
the protein kinase inhibitors, K252a and KT5720 and suppression of the adhesion
by the immunosuppressants FK506 and cyclosporin A.
Mohri T, Kameshita I, Suzuki S, Hioki K, Tokunaga R, Takatani S.
Second Department of Surgery, Kansai Medical University, Moriguchi, Osaka,
Japan.
We examined alterations in cell morphology and expression of adhesion molecules
in response to a general protein kinase inhibitor K252a treatment of
non-adherent colon adenocarcinoma Colo201 cells. K252a induced rapid cell
adhesion and spreading with concomitant formation of actin stress fibers. A
protein kinase A inhibitor KT5720 also induced cell adhesion, but the rate of
spread was slower than that seen with K252a. These adhesions were mediated by
integrin molecules since cell adhesion required Mg2+, Mn2+ or Ca2+, and was
inhibited by monoclonal antibodies for integrins alpha2 and beta1. Indirect
immunofluorescence microscopic observations revealed that integrin alpha2 and
beta1 molecules in K252a-treated cells were concentrated at sites of focal
adhesion, but expressions of integrin molecules were not modulated. Tyrosine
phosphorylation of focal adhesion kinase (FAK) and paxillin increased during
K252a- or KT5720-induced cell adhesion. Immunosuppressants FK506 and cyclosporin
A suppressed the K252a-induced cell adhesion and abolished tyrosine
phosphorylation of cellular proteins including FAK and paxillin. Furthermore, W7
and calmidazolium, inhibitors of calmodulin, also inhibited the cell adhesion.
Based on findings that FK506 and cyclosporin A are inhibitors of the calcium
calmodulin-dependent protein phosphatase, calcineurin, this phosphatase may
regulate integrin-dependent cell adhesion and spread of Colo201 cells. This
Colo201 cell model provides a pertinent system for studying molecules involved
in signal transduction pathways and can shed light on mechanisms of metastasis
and invasion of colon carcinoma cells.
Publication Types:
Research Support, Non-U.S. Gov't
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