Participation of p97Eps8 in Src-mediated transformation.
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.
Leu
Tzeng-Horng
TH
Department of Pharmacology, College of Medicine, National Cheng Kung University, Tainan 70101, Taiwan. tzengleu@mail.ncku.edu.tw
Yeh
Hsu Hua
HH
Huang
Ching-Chung
CC
Chuang
Ya-Chun
YC
Su
Shu Li
SL
Maa
Ming-Chei
MC
D048868:Adaptor Proteins, Signal Transducing; D033942:Adaptor Proteins, Vesicular Transport / Q000378:metabolism; D000362:Agar / Q000494:pharmacology; D000818:Animals; D015152:Blotting, Northern; D002455:Cell Division; D002460:Cell Line; D002471:Cell Transformation, Neoplastic; D002645:Chickens; D051356:Cortactin; D003598:Cytoskeletal Proteins / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D015536:Down-Regulation; D004791:Enzyme Inhibitors / Q000494:pharmacology; D051417:Focal Adhesion Kinase 1; D051416:Focal Adhesion Protein-Tyrosine Kinases; D006657:Histones / Q000378:metabolism; D006877:Hydroxamic Acids / Q000494:pharmacology; D015151:Immunoblotting; D008840:Microfilament Proteins / Q000737:chemistry; D009154:Mutation; D051419:Paxillin; D010750:Phosphoproteins / Q000378:metabolism; D019000:Phosphotyrosine / Q000737:chemistry; D011233:Precipitin Tests; D011505:Protein-Tyrosine Kinases / Q000378:metabolism; D011506:Proteins / Q000378:metabolism / Q000502:physiology*; D012333:RNA, Messenger / Q000378:metabolism; D034741:RNA, Small Interfering / Q000378:metabolism; D051381:Rats; D020133:Reverse Transcriptase Polymerase Chain Reaction; D055765:Shc Signaling Adaptor Proteins; D000071425:Src Homology 2 Domain-Containing, Transforming Protein 1; D013997:Time Factors; D014162:Transfection; D019061:src-Family Kinases / Q000378:metabolism*
D048868:Adaptor Proteins, Signal Transducing; D033942:Adaptor Proteins, Vesicular Transport; D051356:Cortactin; C495870:Cttn protein, rat; D003598:Cytoskeletal Proteins; D004791:Enzyme Inhibitors; D006657:Histones; D006877:Hydroxamic Acids; D008840:Microfilament Proteins; D051419:Paxillin; D010750:Phosphoproteins; D011506:Proteins; C496063:Pxn protein, rat; D012333:RNA, Messenger; D034741:RNA, Small Interfering; D055765:Shc Signaling Adaptor Proteins; C528035:Shc1 protein, rat; D000071425:Src Homology 2 Domain-Containing, Transforming Protein 1; D019000:Phosphotyrosine; C012589:trichostatin A; D000362:Agar; D011505:Protein-Tyrosine Kinases; D051417:Focal Adhesion Kinase 1; D051416:Focal Adhesion Protein-Tyrosine Kinases; C496052:Ptk2 protein, rat; D019061:src-Family Kinases