Increased fatty acid synthase as a potential therapeutic target in multiple myeloma.
OBJECTIVE
To determine fatty acid synthase (FAS) expression in human multiple myeloma and verify its potential as a therapeutic target in multiple myeloma.


METHODS
FAS expression was determined by immunohistochemistry, reverse-transcription polymerase chain reaction (RT-PCR) and immunoblot analysis in bone marrow samples obtained from 27 patients with multiple myeloma (MM patients) and peripheral blood mononuclear cells (PBMCs) obtained from 12 healthy donors. In parallel, additional analyses were performed on 2 human multiple myeloma cell lines, U266 and RPMI8226. U266 cells were treated with cerulenin at various concentrations (5 to 320 microg/ml) for 24 h, and metabolic activity was measured by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assays. Apoptosis was evaluated by dual Annexin V/PI (propidium iodide) labeling and flow cytometry (FCM) in U266 cells treated with 20 (g/ml cerulenin for 12 h or 24 h.


RESULTS
By immunohistochemistry, we found that 19 of 27 bone marrow samples obtained from MM patients expressed significantly high levels of FAS. Similarly, by RT-PCR, 22 of 27 bone marrow samples obtained from MM patients, U266 and RPMI8226 showed FAS expression, whereas PBMC samples from 12 healthy donors did not express detectable level of FAS. FAS protein expression was confirmed by immunoblot analysis in 16 of 27 bone marrow samples obtained from MM patients, U266 and RPMI8226 cell lines, and no FAS protein expression was detected in PBMC samples from 12 healthy donors. U266 cells were highly sensitive to cerulenin treatment, with a dosage-related effect on metabolic activity, as a measure for cell proliferation. U266 cells treated with 20 microg/ml cerulenin for 12 and 24 h also showed early sign of apoptosis with 56.9% and 69.3% Annexin V(+)/PI(-) cells, and late apoptotic and necrotic cells with 3.2% and 17.6% Annexin V(+)/PI(+) cells.


CONCLUSIONS
Increased FAS expression existed in multiple myeloma samples and human myeloma cell lines. Cerulenin greatly inhibited metabolic activity/cell proliferation of U266 cells and induced apoptosis, suggesting that FAS is an effective target for pharmacological therapy in human multiple myeloma.
Department of Hematology, the Second Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou 310009, China.
Wei-qin
WQ
Wang
Xiao-ying
XY
Zhao
Hai-yan
HY
Wang
Yun
Y
Liang
D000328:Adult; D000368:Aged; D017209:Apoptosis / Q000187:drug effects; D001483:Base Sequence; D015153:Blotting, Western; D016022:Case-Control Studies; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D002569:Cerulenin / Q000494:pharmacology; D017931:DNA Primers / Q000235:genetics; D004791:Enzyme Inhibitors / Q000494:pharmacology; D054890:Fatty Acid Synthase, Type I / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D054872:Fatty Acid Synthesis Inhibitors / Q000494:pharmacology; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D008297:Male; D008875:Middle Aged; D009101:Multiple Myeloma / Q000188:drug therapy / Q000201:enzymology* / Q000235:genetics / Q000473:pathology; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D012334:RNA, Neoplasm / Q000235:genetics / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction
D017931:DNA Primers; D004791:Enzyme Inhibitors; D054872:Fatty Acid Synthesis Inhibitors; D012333:RNA, Messenger; D012334:RNA, Neoplasm; D002569:Cerulenin; C518729:FASN protein, human; D054890:Fatty Acid Synthase, Type I