Osteosarcoma is a type of malignant bone
tumor with high
metastasis and poor prognosis. Previous studies have demonstrated the involvement of
LIM kinase 1 (LIMK1) in the proliferation of
osteosarcoma cells. LIMK1 is overexpressed in human
osteosarcoma tissues and cell lines. To further study LIMK1-associated mechanisms, we used
shRNA targeted to the LIMK1 gene to block its expression in the
osteosarcoma cell lines MG63 and U2OS.
Insulin promoted the proliferation of MG63 cells in a time- and dose-dependent manner, however, this
insulin induced proliferation was significantly inhibited by transfection of
shRNA targeted to the LIMK1 gene, as well as by the PI3K inhibitor
LY294002, but not by the mitogen‑activated
protein kinase (MAPK) inhibitor
PD98059. The level of
cofilin phosphorylation was increased significantly following stimulation of
insulin for 24 h, indicating the activation of LIMK1. MG63 cell proliferation was also significantly inhibited by 1,25-dihydroxy
vitamin D3 (
1,25(OH)2D3) in a time-dependent manner. Furthermore,
1,25(OH)2D3 negated the inhibitory effect of LIMK1
shRNA, indicating that LIMK1 is important in the inhibitory pathway of
1,25(OH)2D3. The present study confirms that LIMK1 is important in regulating
osteosarcoma cell proliferation via the
insulin/PI3K/LIMK1 signaling pathway, thus the development of gene therapy for
osteosarcoma targeting LIMK1 is warranted.