MRNA stability and overexpression of fatty acid synthase in human breast cancer cell lines.
BACKGROUND
Elevation of fatty acid synthase (FAS) in human cancers is often associated with increased tumor aggression. The basic genetic mechanisms leading to increased enzyme content in cancer cells were investigated using cell lines derived from human metastatic breast carcinomas (T47D, Zr75 and SKBr3) and normal human breast epithelium (184A1).


METHODS
Western analysis, Northern blotting, [2-(14)C]malonyl-CoA incorporation assays, nuclear run-off transcription assays, mRNA decay assays, and poly(A) tail assays were used to measure and compare transcription rates of the FAS gene among the four cell lines.


RESULTS
By Western analysis, FAS levels in T47D were 2.6 times lower than ZR75 and SKBr3, but 6.7 times greater than non-neoplastic 184A1 cells. FAS mRNA levels and specific activity correlated with protein content. In contrast, relative rates of FAS gene transcription were significantly higher in non-neoplastic 184A1 cells than T47D, ZR75 and SKBr3. Stability of message was investigated to explain this discrepancy. The half-life of FAS mRNA in 184A1 cells was 5.6 h, or 4-5-fold less than ZR75 and SKBr3. Poly(A) tail assays showed that FAS mRNA species from 184A1 cells tended to be longer than those of breast cancer cell lines (500-1500 nt versus 500-800 nt, respectively).


CONCLUSIONS
Breast cancer cell lines contained significantly more FAS enzyme, message and activity than non-neoplastic 184A1 cells. Yet, 184A1 cells exhibited higher rates
Hunt
Dirk A
DA
Department of Microbiology and Immunology, The University of Oklahoma Health Sciences Center, 940 Stanton L. Young Boulevard, P.O. Box 26901, Oklahoma City, OK 73190, USA.
Lane
Hilary M
HM
Zygmont
Matthew E
ME
Dervan
Peter A
PA
Hennigar
Randolph A
RA
D000230:Adenocarcinoma / Q000201:enzymology* / Q000235:genetics*; D001943:Breast Neoplasms / Q000201:enzymology* / Q000235:genetics* / Q000378:metabolism; D045744:Cell Line, Tumor; D064429:Fatty Acid Synthases / Q000096:biosynthesis* / Q000235:genetics / Q000378:metabolism; D015971:Gene Expression Regulation, Enzymologic; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D011061:Poly A / Q000378:metabolism; D012333:RNA, Messenger / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism*; D014158:Transcription, Genetic
D012333:RNA, Messenger; D011061:Poly A; D064429:Fatty Acid Synthases