BRCA1 modulates malignant cell behavior, the expression of survivin and chemosensitivity in human breast cancer cells.
BRCA1 is a multifunctional tumor-suppressive protein. Many functional aspects of BRCA1 are not fully understood. We used a shRNA approach to probe the function of BRCA1 in human breast cancer cells. Knocking down BRCA1 expression by shRNA in the wild-type BRCA1 human breast cancer MCF-7 and MDA-MB-231 cells resulted in an increase in cell proliferation, anchorage-independent growth, cell migration, invasion and a loss of p21/Waf1 and p27Kip1 expression. In BRCA1 knocked-down cells, the expression of survivin was significantly up regulated with a concurrent decrease in cellular sensitivity to paclitaxel. We also found that cells harboring endogenous mutant or defective BRCA1 (MDA-MB-436 and HCC1937) were highly proliferative and expressed a relatively low level of p21/Waf1 and p27Kip1 by comparison to wild-type BRCA1 cells. Cells harboring mutated BRCA1 also expressed a high level of survivin and were relatively resistant to paclitaxel by comparison to wild-type cells. Increase resistance to paclitaxel was due to an increase in the expression of survivin in both the BRCA1 knocked-down and mutant BRCA1 cells because knocking down survivin expression by siRNA restored sensitivity to paclitaxel. We conclude that BRCA1 down-modulates the malignant behavior of breast cancer cells, promotes the expression of p21/Waf1, p27Kip1 and inhibits the expression of survivin. Moreover, loss of BRCA1 expression or function leads to an increase in survivin expression and a reduction in chemosensitivity to paclitaxel.
Promkan
Moltira
M
Department of Microbiology, Immunology and Cell Biology, Southern Illinois University School of Medicine and SimmonsCooper Cancer Institute, Springfield, IL 62794-9677, USA.
Liu
Guangming
G
Patmasiriwat
Pimpicha
P
Chakrabarty
Subhas
S
D000972:Antineoplastic Agents, Phytogenic / Q000494:pharmacology*; D019313:BRCA1 Protein / Q000502:physiology*; D015153:Blotting, Western; D001943:Breast Neoplasms / Q000188:drug therapy* / Q000378:metabolism / Q000473:pathology; D002448:Cell Adhesion / Q000187:drug effects; D045744:Cell Line, Tumor; D002465:Cell Movement / Q000187:drug effects; D049109:Cell Proliferation / Q000187:drug effects; D050759:Cyclin-Dependent Kinase Inhibitor p21 / Q000235:genetics / Q000378:metabolism; D050760:Cyclin-Dependent Kinase Inhibitor p27 / Q000235:genetics / Q000378:metabolism; D019008:Drug Resistance, Neoplasm; D005260:Female; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D051034:Inhibitor of Apoptosis Proteins; D008869:Microtubule-Associated Proteins / Q000235:genetics / Q000378:metabolism*; D009361:Neoplasm Invasiveness; D017239:Paclitaxel / Q000494:pharmacology*; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D034741:RNA, Small Interfering / Q000494:pharmacology; D020133:Reverse Transcriptase Polymerase Chain Reaction; D000077022:Survivin
D000972:Antineoplastic Agents, Phytogenic; C107489:BIRC5 protein, human; D019313:BRCA1 Protein; C492913:BRCA1 protein, human; D050759:Cyclin-Dependent Kinase Inhibitor p21; D051034:Inhibitor of Apoptosis Proteins; D008869:Microtubule-Associated Proteins; D012333:RNA, Messenger; D034741:RNA, Small Interfering; D000077022:Survivin; D050760:Cyclin-Dependent Kinase Inhibitor p27; D017239:Paclitaxel