Stearoyl-CoA desaturase 1 and paracrine diffusible signals have a major role in the promotion of breast cancer cell migration induced by cancer-associated fibroblasts

Abstract

Background:Despite the recognised contribution of the stroma to breast cancer development and progression, the effective targeting of the tumor microenvironment remains a challenge to be addressed. We previously reported that normal fibroblasts (NFs) and, notably, breast cancer-associated fibroblasts (CAFs) induced epithelial-to-mesenchymal transition and increases in cell membrane fluidity and migration in well- (MCF-7) and poorly-differentiated (MDA-MB-231) breast cancer cells. This study was designed to better define the role played, especially by CAFs, in promoting breast tumor cell migration.Methods:Fibroblast/breast cancer cell co-cultures were set up to investigate the influence of NFs and CAFs on gene and protein expression of Stearoyl-CoA desaturase 1 (SCD1), the main enzyme regulating membrane fluidity, as well as on the protein level and activity of its transcription factor, the sterol regulatory element-binding protein 1 (SREBP1), in MCF-7 and MDA-MB-231 cells. To assess the role of SREBP1 in the regulation of SCD1 expression, the desaturase levels were also determined in tumor cells treated with an SREBP1 inhibitor. Migration was evaluated by wound-healing assay in SCD1-inhibited (by small-interfering RNA (siRNA) or pharmacologically) cancer cells and the effect of CAF-conditioned medium was also assessed. To define the role of stroma-derived signals in cancer cell migration speed, cell-tracking analysis was performed in the presence of neutralising antibodies to hepatocyte growth factor, transforming growth factor-β or basic fibroblast growth factor.Results:A two to three fold increase in SCD1 mRNA and protein expression has been induced, particularly by CAFs, in the two cancer cell lines that appear to be dependent on SREBP1 activity in MCF-7 but not in MDA-MB-231 cells. Both siRNA-mediated and pharmacological inhibition of SCD1 impaired tumor cells migration, also when promoted by CAF-released soluble factors. Fibroblast-triggered increase in cancer cell migration speed was markedly reduced or abolished by neutralising the above growth factors.Conclusion:These results provide further insights in understanding the role of CAFs in promoting tumor cell migration, which may help to design new stroma-based therapeutic strategies.

Dynamics of cancerous tissue correlates with invasiveness

“…2a and b it is also apparent that the speed distribution of the most aggressive cells here investigated, the human MDA-MB-231, has a ‘fatter tail’ than the others, this signifies a relatively large number of cells moving extra-ordinarily fast. For the human cell lines, the average velocities here obtained correspond well to those reported in literature in migration assays14151617. For the murine cell lines, there only exists a value for the non-invasive 67NR of 0.03 μm/min18, which is somewhat lower than observed here.…”

Differentiation Affects the Release of Exosomes from Colon Cancer Cells and Their Ability to Modulate the Behavior of Recipient Cells

“…Cell trajectories were calculated by using ImageJ software version 1.41 (NIH, Bethesda, MD; http:// imagej.nih.gov/ij), as reported previously. 21 Quantitative Real-Time PCR Total RNA was extracted using the Ribo Pure Kit Ambion (Life Technologies) and was reverse transcribed into cDNA…”

Fatty acid-related modulations of membrane fluidity in cells: detection and implications

“…Two-photon infrared excitation techniques have been successfully applied to detect Laurdan emission [22]. By using this probe, coexisting lipid domains were characterized on the basis of their distinctive fluorescence spectra and dual-wavelength ratio measurements [23][24][25], which map changes in the structure of PM [19,22,[26][27][28].…”