Abstract
Parathyroid hormone-related protein (PTHrP) has been localized in human colon cancer tissue and cell lines. We have previously shown that PTHrP increases colon cancer cell proliferation, extracellular matrix adhesion, and cell-surface integrin α6β4 expression. Since cancer cell migration, invasion, and survival are crucial components of metastasis, and colon cancer has a high metastatic potential, in this study we used the human colon cancer cell line LoVo as a model system to study the effects of PTHrP on these parameters. PTHrP expression was modulated by stable transfection with a construct expressing PTHrP (- 36 to + 139). We report that PTHrP increases cell migration, invasion, and survival. PTHrP altered cell morphology, with PTHrP-overexpressing cells exhibiting increased spreading and several long protrusions. PTHrP also increased the steady-state mRNA levels of the integrin α6 and β4 subunits, indicating a direct and/or indirect effect of PTHrP on the transcriptional and/or post-transcriptional regulation of integrin α6 and β4 expression. Integrin α6β4 activates the phosphoinositol 3-kinase (PI3-K)/Akt pathway, leading to glycogen synthase kinase-3 (GSK-3) deactivation. PTHrP overexpression also led to an increase in active Akt and inactive GSK-3 levels, indicating that the PTHrP-mediated upregulation of integrin α6β4 expression may activate the PI3-K pathway, resulting in increased cell survival, migration and invasion.
Original language | English |
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Pages (from-to) | 61-72 |
Number of pages | 12 |
Journal | Regulatory Peptides |
Volume | 141 |
Issue number | 1-3 |
DOIs | |
State | Published - Jun 7 2007 |
Bibliographical note
Funding Information:We thank Drs. D. Konkel and M.L. Thomas for critical reading of the manuscript. This work was supported by NIH grants DK035608 and CA104748.
Keywords
- Apoptosis
- Glycogen synthase kinase-3
- Integrin α6β4
- Laminin
- Parathyroid hormone-related protein
ASJC Scopus subject areas
- Endocrinology
- Cellular and Molecular Neuroscience
- Biochemistry
- Physiology
- Clinical Biochemistry