Activity of suberoylanilide hydroxamic Acid against human breast cancer cells with amplification of her-2.
OBJECTIVE
We determined the effects of suberoylanilide hydroxamic acid (SAHA), a histone deacetylase inhibitor, on hsp90 and its client proteins Her-2, AKT, and c-Raf, as well as evaluated the cytotoxic effects of co-treatment of SAHA with trastuzumab or docetaxel in human breast cancer BT-474 and SKBR-3 cells containing amplification of Her-2.


METHODS
The cells were treated with SAHA (1.0-5.0 micromol/L) and/or trastuzumab (5-40 microg/mL) or docetaxel (5-20 nmol/L). Following this, apoptosis and the levels of p21(WAF1), p27(KIP1), AKT, c-Raf, and Her-2, as well as of the key regulators of apoptosis were determined. Synergistic interaction between drugs was evaluated by median dose-effect analysis.


RESULTS
Treatment with SAHA up-regulated p21(WAF1) and p27(KIP1) levels, increased the percentage of cells in G2-M phase of the cell cycle, as well as induced apoptosis in a dose-dependent manner. This was associated with up-regulation of the pro-death Bak and Bim, as well as with attenuation of the levels of Her-2 and XIAP, survivin, Bcl-2, and Bcl-x(L) proteins. SAHA treatment induced acetylation of hsp90. This reduced the chaperone association of Her-2 with hsp90, promoting polyubiquitylation and degradation of Her-2. SAHA also attenuated the levels of c-Raf and AKT. Co-treatment with SAHA significantly increased trastuzumab or docetaxel-induced apoptosis of BT-474 and SKBR-3 cells. Additionally, median dose-effect analysis revealed that co-treatment with SAHA and trastuzumab or docetaxel induced synergistic cytotoxic effects against the breast cancer cells.


CONCLUSIONS
These preclinical findings support the development of SAHA in combination with docetaxel and/or trastuzumab against Her-2-amplified breast cancer.
Bali
Purva
P
Department of Interdisciplinary Oncology, Moffitt Cancer Center and Research Institute, University of South Florida, Tampa, Florida 33612, USA.
Pranpat
Michael
M
Swaby
Ramona
R
Fiskus
Warren
W
Yamaguchi
Hirohito
H
Balasis
Maria
M
Rocha
Kathy
K
Wang
Hong-Gang
HG
Richon
Victoria
V
Bhalla
Kapil
K
D000107:Acetylation; D000911:Antibodies, Monoclonal / Q000008:administration & dosage; D061067:Antibodies, Monoclonal, Humanized; D000971:Antineoplastic Combined Chemotherapy Protocols / Q000494:pharmacology; D017209:Apoptosis / Q000187:drug effects; D015153:Blotting, Western; D001943:Breast Neoplasms / Q000188:drug therapy* / Q000235:genetics; D018797:Cell Cycle Proteins / Q000378:metabolism; D002455:Cell Division / Q000187:drug effects; D050759:Cyclin-Dependent Kinase Inhibitor p21; D050760:Cyclin-Dependent Kinase Inhibitor p27; D000077143:Docetaxel; D004357:Drug Synergism; D005434:Flow Cytometry; D016195:G2 Phase / Q000187:drug effects; D005784:Gene Amplification; D018841:HSP90 Heat-Shock Proteins / Q000378:metabolism; D056572:Histone Deacetylase Inhibitors; D006801:Humans; D006877:Hydroxamic Acids / Q000494:pharmacology*; D051034:Inhibitor of Apoptosis Proteins; D008869:Microtubule-Associated Proteins / Q000378:metabolism; D009363:Neoplasm Proteins / Q000378:metabolism; D046988:Proteasome Endopeptidase Complex / Q000187:drug effects; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D011506:Proteins / Q000378:metabolism; D011518:Proto-Oncogene Proteins / Q000378:metabolism; D051057:Proto-Oncogene Proteins c-akt; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000378:metabolism; D019908:Proto-Oncogene Proteins c-raf / Q000378:metabolism; D018719:Erb-b2 Receptor Tyrosine Kinases / Q000235:genetics* / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects*; D000077022:Survivin; D043823:Taxoids / Q000008:administration & dosage; D000068878:Trastuzumab; D014407:Tumor Cells, Cultured; D025521:Tumor Suppressor Proteins / Q000378:metabolism; D000077337:Vorinostat; D051636:X-Linked Inhibitor of Apoptosis Protein; D051020:bcl-X Protein
D000911:Antibodies, Monoclonal; D061067:Antibodies, Monoclonal, Humanized; D018797:Cell Cycle Proteins; D050759:Cyclin-Dependent Kinase Inhibitor p21; D050760:Cyclin-Dependent Kinase Inhibitor p27; D000077143:Docetaxel; D018841:HSP90 Heat-Shock Proteins; D056572:Histone Deacetylase Inhibitors; D006877:Hydroxamic Acids; D051034:Inhibitor of Apoptosis Proteins; D008869:Microtubule-Associated Proteins; D009363:Neoplasm Proteins; D046988:Proteasome Endopeptidase Complex; D017346:Protein Serine-Threonine Kinases; D011506:Proteins; D011518:Proto-Oncogene Proteins; D051057:Proto-Oncogene Proteins c-akt; D019253:Proto-Oncogene Proteins c-bcl-2; D019908:Proto-Oncogene Proteins c-raf; D018719:Erb-b2 Receptor Tyrosine Kinases; D000077022:Survivin; D043823:Taxoids; D000068878:Trastuzumab; D025521:Tumor Suppressor Proteins; D000077337:Vorinostat; D051636:X-Linked Inhibitor of Apoptosis Protein; D051020:bcl-X Protein; C494811:BCL2L1 protein, human; C107489:BIRC5 protein, human; C493956:CDKN1A protein, human; C496866:XIAP protein, human; C494918:AKT1 protein, human