TY - JOUR
T1 - Increased cell survival, migration, invasion, and Akt expression in PTHrP-overexpressing LoVo colon cancer cell lines
AU - Shen, Xiaoli
AU - Mula, Ramanjaneya V.R.
AU - Evers, B. Mark
AU - Falzon, Miriam
N1 - 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.
PY - 2007/6/7
Y1 - 2007/6/7
N2 - 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.
AB - 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.
KW - Apoptosis
KW - Glycogen synthase kinase-3
KW - Integrin α6β4
KW - Laminin
KW - Parathyroid hormone-related protein
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U2 - 10.1016/j.regpep.2006.12.017
DO - 10.1016/j.regpep.2006.12.017
M3 - Article
C2 - 17276526
AN - SCOPUS:33947601561
SN - 0167-0115
VL - 141
SP - 61
EP - 72
JO - Regulatory Peptides
JF - Regulatory Peptides
IS - 1-3
ER -