We have examined the effects of the protein kinase C (PKC)-activator
phorbol 12-myristate 13-acetate (PMA) on gene expression in two breast cancer cell (BCC) lines exhibiting
highly different phenotypes. These are the estrogen receptor alpha (ERalpha)-positive, weakly invasive,
luminal epithelial-like MCF-7 and the ERalpha-negative, highly invasive, fibroblast-like MDA-MB-231. They
express constitutively low and high PKC activities, respectively. After a 24-h exposition to 100 nM PMA,
the number of genes showing an altered expression at the 2-fold change level was much higher in MCF-7
(n=435) than in MDA-MB-231 (n=18) BCC. Four of these genes, namely CDC2 (Cell division cycle 2),
CENPA (Centromere protein A (17 kDa)), NR4A1 (Nuclear receptor subfamily 4, group A, member 1),
and MMP10 (Matrix metalloproteinase 10 (stromelysin 2)), were altered in the same way in both cell
lines. Two genes were regulated in an opposite way: ID1 (Inhibitor of DNA binding 1, dominant negative
helix-loop-helix protein) and EVA1 (Epithelial V-like antigen 1). Many of the genes down-regulated
in MCF-7 BCC appeared to be preferentially expressed in G1, S and/or G2 phases of the
cell cycle. The ERalpha gene, ESR1, and other genes associated to the ERalpha-positive, luminal
epithelial-like BCC phenotype were down-regulated, while a series of genes related to a more aggressive,
fibroblast-like phenotype were up-regulated. Other altered genes were notably linked to cell architecture,
supporting profound effects of PMA on cell morphology and motility, as well as on the interactions between
BCC and the neighboring proteins. Of note, all the modulated genes involved in proteolysis and its control
were up-regulated. In summary, PMA effects suggest that PKC activation may induce, to some extent, a more
fibroblast-like phenotype in the ERalpha-positive, luminal epithelial-like MCF-7 BCC, and significantly
modulate the interactions of these cells with their environment.
Genes most up- or down-regulated in MCF-7 BCC:
Up: MMP1 (Matrix metalloproteinase 1 (interstitial collagenase)), PRKACA (Protein
kinase, cAMP-dependent, catalytic, alpha), PLAB (Prostate differentiation factor), S100A9
(S100 calcium binding protein A9 (calgranulin B)), S100P (S100 calcium binding protein P),
SERPINA3 (Serine (or cysteine) proteinase inhibitor, clade A, member 3), AKR1C4 (Aldo-keto
reductase family 1, member C4), KRTHB1 (Keratin, hair, basic, 1), MMP10 (Matrix
metalloproteinase 10 (stromelysin 2)), BIRC3 (Baculoviral IAP repeat-containing 3), CDKN1A
(Cyclin-dependent kinase inhibitor 1A (p21, Cip1)), GLRX (Glutaredoxin (thioltransferase)),
ORM1 (Orosomucoid 1), AKR1C1 (Aldo-keto reductase family 1, member C1 (dihydrodiol
dehydrogenase 1)), KCNF1 (Potassium voltage-gated channel, subfamily F, member 1), H11
(Protein kinase H11), LTB (Lymphotoxin beta (TNF superfamily member 3)), RAI3 (Retinoic
acid induced 3), KRTHB3 (Keratin, hair, basic, 3), ELL2 (Elongation factor, RNA polymerase II,
2), DGAT2 (Diacylglycerol O-acyltransferase homolog 2 (mouse)), MMP9 (Matrix metalloproteinase 9)
Down: TRGV9 (T-cell receptor gamma locus), IGFBP5 (Insulin-like growth factor binding
protein 5), EXO1 (Exonuclease 1), SKP2 (S-phase kinase-associated protein 2 (p45)),
ADD3 (Adducin 3, gamma), NR2F2 (Nuclear receptor subfamily 2, group F, member 2), PCNA
(Proliferating cell nuclear antigen), MYB (v-myb myeloblastosis viral oncogene homolog (avian)),
TXNIP (Thioredoxin interacting protein), BBOX1 (Butyrobetaine (gamma), 2-oxoglutarate
dioxygenase 1), SSFA2 (Sperm specific antigen 2), EPLIN (Epithelial protein lost in neoplasm beta),
CCNE2 (Cyclin E2), BCHE (Butyrylcholiesterase), RFC4 (Replication factor C (activator
1), 4), TYMS (Thymidylate synthetase), VAV3 (vav3 oncogene), MCM2 (MCM2 minichromosome
maintenance deficient 2, mitotin (S. cerevisiae))
Genes up- or down-regulated in MDA-MB-231 BCC:
Up: SERPINB2 (Serine (or cysteine) proteinase inhibitor, clade B (ovalbumin), member 2),
PTGS2 (Prostaglandin-endoperoxidase synthase 2 (cyclooxygenase 2), TFPI2 (Tissue factor
pathway 2), MMP10 (Matrix metalloproteinase 10 (stromelysin 2)), IL1B (Interleukin 1 beta),
SGNE1 (Secretory granule, neuroendocrine protein 1 (7B2 protein)), PPARD (Peroxisome
proliferative activated receptor delta), NR4A1 (Nuclear receptor subfamily 4, group A, member 1),
MMP3 (Matrix metalloproteinase 3 (stromelysin 1))
Down: ID1 (Inhibitor of DNA binding 1, dominant negative helix-loop-helix protein),
SNCA (Synuclein alpha (non A4 component of amyloid precursor)), CCNA1 (Cyclin A1),
SERPINA5 (Serine (or cysteine) proteinase inhibitor, clade A (alpha-1 antiproteinase, antitrypsin),
member 5), PFN2 (profilin 2), EVA1 (Epithelial V-like antigen 1), CENPA (Centromere
protein A (17 kDa)), CDC2 (Cell division cycle 2), HEPH (Hephaestin)
