PLD1 is overexpressed in an ER-negative MCF-7 cell line variant and a subset of phospho-Akt-negative breast carcinomas.
We have used a novel variant of the human oestrogen receptor (ER)-positive MCF-7 cell line, TMX2-28, as a model to study breast cancer. TMX2-28 cells show no detectable levels of mRNA or protein expression for the ER and express basal cytokeratins (CKs) 5, 14, and 17. cDNA microarray comparison between TMX2-28 and its parent cell line, MCF-7, identified 1402 differentially expressed transcripts, one of which was, phospholipase D1 (PLD1). Using real-time RT-PCR, we confirmed that PLD1 mRNA levels are 10-fold higher in TMX2-28 cells than in MCF-7 cells. We next examined PLD1 expression in human breast carcinomas. Phospholipase D1 mRNA levels were higher in breast tumours that expressed high-mRNA levels of basal CKs 5 and/or 17, but PLD1 mRNA levels were not significantly higher in ER-negative tumours. Phospholipase D1 protein was overexpressed in 10 of 42 (24%) breast tumours examined by IHC. Phospholipase D1 was overexpressed in 6 of 31 ER-positive tumours and 4 of 11 ER-negative tumours. Phospholipase D1 was overexpressed in three of the four tumours that showed high CK5/17 expression. Five PLD1-positive tumours were negative for phospho-Akt expression, but positive for phospho-mammalian target of rapamycin (mTOR) expression. The other five PLD1-positive breast tumours showed positive expression for phospho-Akt; however, only two of these cases were positive for phospho-mTOR. In this study, we report that PLD1 and phospho-mTOR are coexpressed in a subset of phospho-Akt-negative breast carcinomas.
Gozgit
J M
JM
Department of Veterinary and Animal Sciences, University of Massachusetts, Morrill 1 North, Amherst, MA 01003-9298, USA.
Pentecost
B T
BT
Marconi
S A
SA
Ricketts-Loriaux
R S J
RS
Otis
C N
CN
Arcaro
K F
KF
D015153:Blotting, Western; D001943:Breast Neoplasms / Q000201:enzymology* / Q000378:metabolism; D045744:Cell Line, Tumor; D018076:DNA, Complementary / Q000378:metabolism; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D046228:Microarray Analysis; D051058:Oncogene Protein v-akt / Q000378:metabolism; D010739:Phospholipase D / Q000235:genetics / Q000378:metabolism*; D011494:Protein Kinases / Q000378:metabolism*; D012333:RNA, Messenger / Q000378:metabolism; D011960:Receptors, Estrogen / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D058570:TOR Serine-Threonine Kinases; D015854:Up-Regulation
D018076:DNA, Complementary; D012333:RNA, Messenger; D011960:Receptors, Estrogen; D011494:Protein Kinases; C546842:MTOR protein, human; D051058:Oncogene Protein v-akt; D058570:TOR Serine-Threonine Kinases; D010739:Phospholipase D; C106801:phospholipase D1