Linked Life Data

20110775

Source:http://linkedlifedata.com/resource/pubmed/id/20110775

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
1
pubmed:dateCreated
2010-2-3
pubmed:abstractText
In recent studies, we and others showed that autophagy is critical to estrogen receptor positive (ER+) breast cancer cell survival and the development of antiestrogen resistance. Consequently, new approaches are warranted for targeting autophagy in breast cancer cells undergoing antiestrogen therapy. Because crosstalk has been demonstrated between the autophagy- and proteasome-mediated pathways of protein degradation, this study investigated how the proteasome inhibitor bortezomib affects autophagy and cell survival in antiestrogen-treated ER+ breast cancer cells. Bortezomib, at clinically achievable doses, induced a robust death response in ER+, antiestrogen-sensitive and antiestrogen-resistant breast cancer cells undergoing hormonal therapy. Cleavage of PARP and lamin A was detectable as a read-out of cell death, following bortezomib-induced mitochondrial dysfunction. Prior to induction of cell death, bortezomib-treated cells showed high levels of light chain 3 (LC3) and p62, two protein markers for autophagy. The accumulation of these proteins was due to bortezomib-mediated blockade of long-lived protein turnover during macroautophagy. This novel action of bortezomib was linked to its blockade of cathepsin-L activity, which is required for autolysosomal-mediated protein turnover in ER+ breast cancer cells. Further, bortezomib-treated breast cancer cells showed induction of the unfolded protein response, with upregulation of CH OP and GRP78. Bortezomib also induced high levels of the pro-apoptotic protein BNIP3. Knockdown of CH OP and/or BNIP3 expression via RNAi targeting significantly attenuated the death-promoting effects of bortezomib. Thus, bortezomib inhibits prosurvival autophagy, in addition to its known function in blocking the proteasome, and is cytotoxic to hormonally treated ER+ breast cancer cells. These findings indicate that combining a proteasome inhibitor like bortezomib with antiestrogen therapy may have therapeutic advantage in the management of early-stage breast cancer.
pubmed:grant
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Jan
pubmed:issn
1554-8635
pubmed:author
pubmed:issnType
Electronic
pubmed:volume
6
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
19-35
pubmed:meshHeading
pubmed-meshheading:20110775-Antineoplastic Agents, pubmed-meshheading:20110775-Autophagy, pubmed-meshheading:20110775-Boronic Acids, pubmed-meshheading:20110775-Breast Neoplasms, pubmed-meshheading:20110775-Caspases, pubmed-meshheading:20110775-Cathepsins, pubmed-meshheading:20110775-Cell Death, pubmed-meshheading:20110775-Down-Regulation, pubmed-meshheading:20110775-Drug Evaluation, Preclinical, pubmed-meshheading:20110775-Drug Resistance, Neoplasm, pubmed-meshheading:20110775-Endoplasmic Reticulum, pubmed-meshheading:20110775-Estrogen Receptor Modulators, pubmed-meshheading:20110775-Female, pubmed-meshheading:20110775-Humans, pubmed-meshheading:20110775-Metabolism, pubmed-meshheading:20110775-Pyrazines, pubmed-meshheading:20110775-Receptors, Estrogen, pubmed-meshheading:20110775-Signal Transduction, pubmed-meshheading:20110775-Stress, Physiological, pubmed-meshheading:20110775-Tumor Cells, Cultured
pubmed:year
2010
pubmed:articleTitle
Bortezomib blocks the catabolic process of autophagy via a cathepsin-dependent mechanism, affects endoplasmic reticulum stress and induces caspase-dependent cell death in antiestrogen-sensitive and resistant ER+ breast cancer cells.
pubmed:affiliation
Department of Cellular Biology and Anatomy, Medical College of Georgia, Augusta, GA, USA.
pubmed:publicationType
Journal Article, Research Support, Non-U.S. Gov't, Research Support, N.I.H., Extramural