In vivo bone metastases, osteoclastogenic ability, and phenotypic characterization of human breast cancer cells

• Published in: Bone (New York, N.Y.) Vol. 34; no. 4; pp. 697 - 709
• Main Authors: Rucci, Nadia, Ricevuto, Enrico, Ficorella, Corrado, Longo, Maurizio, Perez, Marie, Di Giacinto, Claudia, Funari, Alessia, Teti, Anna, Migliaccio, Silvia
• Format: Journal Article
• Language: English
• Published: New York, NY Elsevier Inc 01-04-2004; Elsevier Science
• Subjects: Animals; Biological and medical sciences; Bone Neoplasms - enzymology; Bone Neoplasms - metabolism; Bone Neoplasms - pathology; Bone Neoplasms - secondary; Bone Resorption - pathology; Breast cancer; Breast Neoplasms - pathology; Cell Differentiation; Cell Division; Cell Movement; Cell Size; Cells, Cultured; Cytokines - genetics; Cytoskeleton - pathology; Diseases of the osteoarticular system; Estrogen receptor; Estrogen Receptor alpha - genetics; Estrogen Receptor alpha - metabolism; Focal Adhesion Kinase 1; Focal Adhesion Kinase 2; Focal Adhesion Protein-Tyrosine Kinases; Fundamental and applied biological sciences. Psychology; Heat-Shock Proteins - genetics; Heat-Shock Proteins - metabolism; Humans; Medical sciences; Metalloproteases - metabolism; Mice; Neoplasm Invasiveness; Osteoclasts - enzymology; Osteoclasts - metabolism; Osteoclasts - pathology; Osteolytic metastasis; Phenotype; Protein Isoforms - metabolism; Protein kinase C; Protein Kinase C - metabolism; Protein-Tyrosine Kinases - genetics; Protein-Tyrosine Kinases - metabolism; Proto-Oncogene Proteins pp60(c-src) - genetics; Proto-Oncogene Proteins pp60(c-src) - metabolism; Tissue Inhibitor of Metalloproteinases - genetics; Transcription, Genetic; Traumas. Diseases due to physical agents; Vertebrates: anatomy and physiology, studies on body, several organs or systems; Estrogen receptor; Protein kinase C; TNFα; ALP; M-MLV; HRP; TRAP; DMEM; GM-CSF; Osteolytic metastasis; RT-PCR; NRTK; PBS; OPGL; Hsp; ERα; PKC; Breast cancer; IL-1β; IL-12; PTHrP; IL-6; ECL; FAK; MMP; PYK2; cbfa1; IL-18; FCS; GAPDH; TIMP; Ability; Human; Enzyme; Transferases; Metastasis; Malignant tumor; Characterization; In vivo; Morphology; Orthopedics; Physiology; Bone; Tumor cell; Hormonal receptor
• ISSN: 8756-3282; 1873-2763
• DOI: 10.1016/j.bone.2003.07.012

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-1β, tumor necrosis factor-α (TNF-α))  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 α (ERα), respectively. MCF-7ADR also showed significantly higher levels of the protein kinase C (PKC) α and β2 and a selective activation of PKCε compared to MCF-7, where the most abundant isoforms were β1 and δ. 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.