Cortactin underpins CD44-promoted invasion and adhesion of breast cancer cells to bone marrow endothelial cells.
Using a validated tetracycline (tet)-regulated MCF7-founder (MCF7F) expression system to modulate expression of CD44 standard form (CD44s), we report the functional importance of CD44s and that of a novel transcriptional target of hyaluronan (HA)/CD44s signaling, EMS1/cortactin, in underpinning breast cancer metastasis. In functional experiments, tet-regulated induction of CD44s potentiated the migration and invasion of MCF7F cells through HA-supplemented Matrigel. EMS1/cortactin was identified by expression profiling as a novel transcriptional target of HA/CD44 signaling, an association validated by quantitative PCR and immunoblotting experiments in a range of breast cancer cell lines. The mechanistic basis underpinning CD44-promoted transcription of EMS1/cortactin was shown to be dependent upon a NFkappaB mechanism, since pharmacological inhibition of IkappaKinase-2 or suppression of p65 Rel A expression attenuated CD44-induced increases in cortactin mRNA transcript levels. Overexpression of a c-myc tagged murine cortactin construct in the weakly invasive, CD44-deficient MCF7F and T47D cells potentiated their invasion. Furthermore, the functional importance of cortactin to CD44s-promoted metastasis was demonstrated by selective suppression of cortactin in CD44-expressing MCF7F-B5 and MDA-MB-231 breast cancer cells using RNAi, which was shown to result in attenuated CD44-promoted invasion and CD44-promoted adhesion to bone marrow endothelial cells (BMECs).
Hill
A
A
Centre for Cancer Research and Cell Biology, Queens University Belfast, Belfast City Hospital, Belfast, Northern Ireland.
McFarlane
S
S
Mulligan
K
K
Gillespie
H
H
Draffin
J E
JE
Trimble
A
A
Ouhtit
A
A
Johnston
P G
PG
Harkin
D P
DP
McCormick
D
D
Waugh
D J J
DJ
D001483:Base Sequence; D015153:Blotting, Western; D001853:Bone Marrow / Q000473:pathology*; D001943:Breast Neoplasms / Q000473:pathology*; D002448:Cell Adhesion / Q000502:physiology*; D045744:Cell Line, Tumor; D051356:Cortactin / Q000502:physiology*; D017931:DNA Primers; D004727:Endothelium / Q000473:pathology*; D006801:Humans; D018960:Hyaluronan Receptors / Q000502:physiology*; D007150:Immunohistochemistry; D009361:Neoplasm Invasiveness; D015398:Signal Transduction; D014158:Transcription, Genetic
D051356:Cortactin; D017931:DNA Primers; D018960:Hyaluronan Receptors