Upregulation of cellular triacylglycerol – free fatty acid cycling by oleate is associated with long-term serum-free survival of human breast cancer cells

2007 ◽  
Vol 85 (3) ◽  
pp. 301-310 ◽  
Author(s):  
Ewa Przybytkowski ◽  
Érik Joly ◽  
Christopher J. Nolan ◽  
Serge Hardy ◽  
Ann-Michele Francoeur ◽  
...  

We previously showed that exogenous oleate protects human breast cancer cells against palmitate-induced apoptosis in part by increasing esterification of this free fatty acid (FFA) into triacylglycerol (TG). Here, we studied the mechanism whereby oleate protects these cells against apoptosis induced by serum withdrawal. The metabolism of FFA, TG, and glucose, in parallel with long-term cell survival in the absence of serum, was investigated in a panel of human breast cancer cell lines and in nontransformed MCF-10A cells after treatment with exogenous oleate. Short-term (3–24 h) exposure of MDA-MB-231 human breast cancer cells to exogenous oleate resulted in a dose-dependent long-term (10 day) serum-free survival that correlated with the accumulation of TG in lipid droplets and with upregulation of lipolysis. Both effects persisted for several days after oleate removal. Rapid TG lipolysis and FFA re-esterification, supported by high rates of glycolysis that provide the glycerol backbone for TG synthesis, are consistent with the presence of very active TG–FFA cycling in human breast cancer cells. Only the cancer cell lines capable of accumulating TG showed long-term serum-free survival after oleate treatment. The results suggest that upregulation of TG–FFA cycling induced by oleate may be involved in maintenance of human breast cancer cell survival.

1998 ◽  
Vol 20 (3) ◽  
pp. 375-380 ◽  
Author(s):  
R Stephen ◽  
D Corcoran ◽  
PD Darbre

Screening by differential display of oestrogen-sensitive MCF7 human breast cancer cells grown in the short-term (6 days) and long-term (70 weeks) absence of oestrogen has led to the identification of a new oestrogen-regulated mRNA. The cDNA isolated by differential display has 100% homology from nucleotides 615 to 859 of the published sequence for the mRNA for human megakaryocyte CD63 antigen but has a 3' tail extended by 23 nucleotides. Northern blotting has confirmed that this mRNA is regulated by oestrogen in both MCF7 and T47D human breast cancer cell lines.


2016 ◽  
Vol 30 (7) ◽  
pp. 693-708 ◽  
Author(s):  
Elena Pedraz-Cuesta ◽  
Jacob Fredsted ◽  
Helene H. Jensen ◽  
Annika Bornebusch ◽  
Lene N. Nejsum ◽  
...  

Prolactin (PRL) and its receptor (PRLR) are implicated in breast cancer invasiveness, although their exact roles remain controversial. The Na+/H+ exchanger (NHE1) plays essential roles in cancer cell motility and invasiveness, but the PRLR and NHE1 have not previously been linked. Here we show that in T47D human breast cancer cells, which express high levels of PRLR and NHE1, exposure to PRL led to the activation of Janus kinase-2 (JAK2)/signal transducer and activator of transcription-5 (STAT5), Akt, and ERK1/2 signaling and the rapid formation of peripheral membrane ruffles, known to be associated with cell motility. NHE1 was present in small ruffles prior to PRL treatment and was further recruited to the larger, more dynamic ruffles induced by PRL exposure. In PRL-induced ruffles, NHE1 colocalized with activated Akt, ERK1/2, and the ERK effector p90Ribosomal S kinase (p90RSK), known regulators of NHE1 activity. Stimulation of T47D cells with PRL augmented p90RSK activation, Ser703-phosphorylation of NHE1, NHE1-dependent intracellular pH recovery, pericellular acidification, and NHE1-dependent invasiveness. NHE1 activity and localization to ruffles were attenuated by the inhibition of Akt and/or ERK1/2. In contrast, noncancerous MCF10A breast epithelial cells expressed NHE1 and PRLR at lower levels than T47D cells, and their stimulation with PRL induced neither NHE1 activation nor NHE1-dependent invasiveness. In conclusion, we show for the first time that PRLR activation stimulates breast cancer cell invasiveness via the activation of NHE1. We propose that PRL-induced NHE1 activation and the resulting NHE1-dependent invasiveness may contribute to the metastatic behavior of human breast cancer cells.


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