In vivo bone metastases, osteoclastogenic ability, and phenotypic characterization of human breast cancer cells.
Mouse bone marrow cells cultured with human breast cancer MCF-7 cell-conditioned media showed osteoclastogenesis with an increment of bone resorption, although conditioned media from an adriamycin-selected MCF-7 clone (MCF-7ADR) had no effect. Consistently, MCF-7 cells induced 5-fold more in vivo experimental osteolytic bone metastases, with no soft tissue lesions, compared to MCF-7ADR cells. Paracrine factors stimulating (interleukin (IL)-6, IL-1beta, tumor necrosis factor-alpha (TNF-alpha)) or inhibiting (IL-12, IL-18, granulocyte macrophage-colony stimulating factor (GM-CSF)) osteoclastogenesis were significantly increased in MCF-7ADR relative to MCF-7 cells, suggesting that the inhibitory cytokines could selectively overwhelm the effects of the stimulatory ones. Treatment of osteoblast primary cultures with MCF-7-conditioned medium induced a selective upregulation of IL-6 expression, suggesting an indirect stimulation of osteoclastogenesis via the osteoblasts. MCF-7 and MCF-7ADR showed no difference in proliferation rate. However, a higher ability to migrate and invade gelatin and matrigel was observed in MCF-7ADR. Enhanced invasiveness might result from increased metalloproteinase (MMP) activity and cytoskeleton rearrangement. MCF-7ADR cells expressed higher levels of c-Src, focal adhesion kinase (FAK), and protein tyrosine kinase 2 (PYK2) involved in cell adhesion and motility. MCF-7 and MCF-7ADR expressed high and faint levels of functional estrogen receptor alpha (ERalpha), respectively. MCF-7ADR also showed significantly higher levels of the protein kinase C (PKC) alpha and beta2 and a selective activation of PKC compared to MCF-7, where the most abundant isoforms were beta1 and delta. Heat shock protein 27 (Hsp27) was more abundant in MCF-7 cells, but failed to translocate to the nucleus in response to heat shock. In conclusion, we have demonstrated that despite the fact that MCF-7ADR cells showed a more invasive phenotype relative to MCF-7, they have low potential to induce osteolytic bone lesions and stimulate osteoclastogenesis and osteoclast activity. Therefore, we believe that reduced aggressiveness of breast carcinomas could correlate with a greater osteolytic activity featuring their bone metastases.
Rucci
Nadia
N
Department of Experimental Medicine, University of L'Aquila, L'Aquila, Italy.
Ricevuto
Enrico
E
Ficorella
Corrado
C
Longo
Maurizio
M
Perez
Marie
M
Di Giacinto
Claudia
C
Funari
Alessia
A
Teti
Anna
A
Migliaccio
Silvia
S
D000818:Animals; D001859:Bone Neoplasms / Q000201:enzymology / Q000378:metabolism / Q000473:pathology* / Q000556:secondary*; D001862:Bone Resorption / Q000473:pathology; D001943:Breast Neoplasms / Q000473:pathology*; D002454:Cell Differentiation; D002455:Cell Division; D002465:Cell Movement; D048429:Cell Size; D002478:Cells, Cultured; D016207:Cytokines / Q000235:genetics; D003599:Cytoskeleton / Q000473:pathology; D047628:Estrogen Receptor alpha / Q000235:genetics / Q000378:metabolism; D051417:Focal Adhesion Kinase 1; D051418:Focal Adhesion Kinase 2; D051416:Focal Adhesion Protein-Tyrosine Kinases; D006360:Heat-Shock Proteins / Q000235:genetics / Q000378:metabolism; D006801:Humans; D045726:Metalloproteases / Q000378:metabolism; D051379:Mice; D009361:Neoplasm Invasiveness; D010010:Osteoclasts / Q000201:enzymology / Q000378:metabolism / Q000473:pathology*; D010641:Phenotype; D020033:Protein Isoforms / Q000378:metabolism; D011493:Protein Kinase C / Q000378:metabolism; D011505:Protein-Tyrosine Kinases / Q000235:genetics / Q000378:metabolism; D016392:Proto-Oncogene Proteins pp60(c-src) / Q000235:genetics / Q000378:metabolism; D019714:Tissue Inhibitor of Metalloproteinases / Q000235:genetics; D014158:Transcription, Genetic
D016207:Cytokines; D047628:Estrogen Receptor alpha; D006360:Heat-Shock Proteins; D020033:Protein Isoforms; D019714:Tissue Inhibitor of Metalloproteinases; D011505:Protein-Tyrosine Kinases; D051417:Focal Adhesion Kinase 1; D051418:Focal Adhesion Kinase 2; D051416:Focal Adhesion Protein-Tyrosine Kinases; C496050:PTK2 protein, human; D016392:Proto-Oncogene Proteins pp60(c-src); C496051:Ptk2 protein, mouse; C496053:Ptk2b protein, mouse; D011493:Protein Kinase C; D045726:Metalloproteases