Regulation of motility, invasion, and metastatic potential of squamous cell carcinoma by 1,25-dihydroxycholecalciferol
Ma Y et al. – 1,25D3 suppressed SCC cell motility, invasion, and metastasis, partially through the promotion of E-cadherin-mediated cell-cell adhesion.Methods
- Squamous cell carcinoma (SCC) or 1,25D3-resistant variant SCC-DR cells were treated with 1,25D3.
- Actin organization was examined by immunofluorescence assay.
- Cell migration was assessed by “wound” healing and chemotactic migration assays.
- Cell invasion was assessed by a Matrigel-based invasion assay and in situ zymography.
- Matrix metalloproteinase 2 (MMP-2) and MMP-9 expression and secretion were examined by immunoblot analysis and an enzyme-linked immunosorbent assay, respectively.
- E-cadherin expression was assessed by flow cytometry, immunoblot analysis, and immunohistochemistry.
- Knockdown of E-cadherin was achieved by small interfering RNA.
- An experimental metastasis mouse model was created by intravenous injection of tumor cells; and lung tumor development in the mice was assessed by magnetic resonance imaging, gross observation, and histology.
- SCC cellular morphology and actin organization were altered by 10 nM 1,25D3. 1,25D3 inhibited SCC cell motility and invasion, which were associated with reduced expression and secretion of MMP-2 and MMP-9, and 1,25D3 promoted the expression of E-cadherin.
- These findings were not observed in SCC-DR cells. Knock down of E-cadherin rescued 1,25D3-inhibited cell migration. Intravenous injection of SCC or SCC-DR cells resulted in the establishment of extensive pulmonary lesions in saline-treated C3H mice.
- Treatment with 1,25D3 resulted in a marked reduction in the formation of lung tumor colonies in mice that were injected with SCC cells, but not in mice that were injected with SCC-DR cells.