The Arg-Gly-Asp (RGD) peptide sequence is the cell attachment site of a large number of adhesive extracellular matrix as well as blood cells, and nearly half of the over 20 known integrins recognize this sequence. The biological effect of this peptide has been well studied for its influences on migration, growth and morphological changes especially concerning its impact on cancer cells. But its effect on senescent cells has not been thoroughly studied. We report here a novel aspect of RGD effect on the senescent phenotype. It is well known that integrin alphavbeta3 and integrin alphavbeta5 bind to extracellular matrix (ECM) molecules through RGD binding site. In this work, we found out that the expressions of integrin alphavbeta3 and integrin alphavbeta5 decreased in senescent human diploid fibroblasts, when compared with those in young cells. Therefore, we assumed that RGD effect to the senescent cells would not be strong enough to induce any change. However, we observed that morphology of the senescent human diploid fibroblasts could be restored to the young-like phenotype by RGD treatment within five days. Therefore, we tentatively conclude that the senescent cells can readily respond to RGD treatment. These data suggest the critical role of cell to matrix interaction especially of RGD in maintenance of morphological integrity.
Human diploid fibroblasts