Background Studies show that abnormalities in non-coding
genes can contribute to carcinogenesis; microRNA levels
may modulate cancer growth and metastatic diffusion.
Method MicroRNA libraries were built and sequenced from
two osteosarcoma cell lines (MG-63 and 143B), which differ
in proliferation and transmigration. By cloning and transfection,
miR-93, expressed in both cell lines, was then
investigated for its involvement in osteosarcoma progression.
Results Six of the 19 miRNA identified were expressed in
both cell lines with higher expression levels of miR-93 in
143B and in primary osteosarcoma cultures compared to
normal osteoblasts. Interestingly, levels of miR-93 were
significantly higher in metastases from osteosarcoma than
in paired primary tumours. When 143B and MG-63 were
transfected with miR-93, clones appeared to respond
differently to microRNA overexpression. Ectopic expression
of miR-93 more significantly increased cell proliferation
and invasivity in 143B than in MG-63 clones.
Furthermore, increased mRNA and protein levels of
E2F1, one of the potential miR-93 targets, were seen in
osteosarcoma cellular clones and its involvement in 143B
cell proliferation was confirmed by E2F1 silencing.
Conclusion Although further studies are needed to evaluate
miRNA involvement in osteosarcoma progression, miR-93
overexpression seems to play an important role in osteosarcoma
cell growth and invasion.