Participation of p97Eps8 in Src-mediated Transformation

Abstract

Histone acetylase and histone deacetylase are two crucial enzymes that determine the structure of chromatin, regulating gene expression. In this study, we observed that trichostatin A (TSA), a specific histone deacetylase inhibitor, could effectively inhibit the growth of v-Src-transformed (IV5) cells and abrogate their ability to form colonies in soft agar. Further analysis demonstrated that, although TSA reduced the expression of Eps8 in a dose-and time-dependent manner, both the protein expression and kinase activity of v-Src remained constant, and the abundance and phosphotyrosine levels of Src substrates, including cortactin, focal adhesion kinase, p130 Cas , paxillin, and Shc, were not altered. Notably, removal of TSA from the medium restored not only the expression of Eps8, but also cellular growth. Northern and reverse transcription-PCR analyses revealed the significant reduction of eps8 transcripts in TSA-treated IV5 cells relative to control cells. When active Src-expressing chicken embryonic cells were forced to overexpress p97 Eps8 , they became resistant to TSA-mediated anti-proliferation. Furthermore, using small interference RNA of eps8, we demonstrated the requirement for Eps8 in IV5 cell proliferation. Thus, our results highlight a critical role for p97 Eps8 in TSA-exerted growth inhibition of v-Src-transformed cells.

Eps8 decreases chemosensitivity and affects survival of cervical cancer patients

“…Its expression is elevated by v-Src, which is critical in v-Src-mediated transformation (27). Recently, we confirm that Eps8 can mediate the activation of Src and participates in colon cancer formation and progression (28).…”

Requirement of Inducible Nitric-oxide Synthase in Lipopolysaccharide-mediated Src Induction and Macrophage Migration

“…Methods for immunoblotting analysis have been described (25). The cell lysates were resolved in an 8% SDS-polyacrylamide gel, transferred to nitrocellulose membranes, and probed with respective antibodies followed by horseradish peroxidase-conjugated protein A or horseradish peroxidase-conjugated secondary antibodies and detected by Enhanced Chemiluminescence method (Amersham Biosciences).…”

Eps8 Protein Facilitates Phagocytosis by Increasing TLR4-MyD88 Protein Interaction in Lipopolysaccharide-stimulated Macrophages

“…Eps8 can be mediated by Src activation in murine fibroblasts (21); therefore, its role in the LPS-induced, Src-dependent phagocytosis was determined. As shown in Fig Eps8 and p68 Eps8 were observed in fibroblasts (20), the former was the major Eps8 isoform detected in RAW cells regardless of LPS stimulation.…”

“…In addition to these functions, Eps8 is important in mitogenesis because its aberrant expression in cells not only increases proliferation in response to epidermal growth factor (EGF) (19) but also causes normal cells to become transformed (12). In addition to EGF receptor, Eps8 is also a substrate of Src tyrosine kinase (20) and is involved in Src-mediated transformation (21,22). The enzymatic activity of Src positively regulates not only the expression of Eps8 (20,21) but also the interaction between Eps8 and IRSp53, leading to the activation of Stat3 in Src-transformed cells (23).…”

“…In addition to EGF receptor, Eps8 is also a substrate of Src tyrosine kinase (20) and is involved in Src-mediated transformation (21,22). The enzymatic activity of Src positively regulates not only the expression of Eps8 (20,21) but also the interaction between Eps8 and IRSp53, leading to the activation of Stat3 in Src-transformed cells (23).…”