Abstract
Purpose : To investigate the effect of indole-3-acetate (IAA) on the proliferation of 143B and HOS osteosarcoma cells, and its mechanism of action. Methods : Indole-3-acetate (IAA)-induced changes in cell proliferation and apoptosis were investigated using 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide (MTT) assay and flow cytometry, respectively. The effects of IAA on expressions of mRNAs for phosphatase and tensin homolog (PTEN), fas ligand (FasL), and fas receptor (FasR) were evaluated using western blot assay. Results : Early apoptosis in 143B cell cultures due to addition of IAA (5 μM) was 34.67 %, relative to 2.82 % in untreated cultures. In HOS cells, IAA caused 39.21 % apoptosis, relative to 3.53 % apoptosis in control. The addition of IAA to the cell cultures significantly enhanced the expressions of mRNAs for PTEN, FasL and FasR, compared to untreated cells (p < 0.05). Western blot analysis showed that IAA caused a significant decrease in the level of IκBα expression in both cell lines (p < 0.05). In 143B and HOS cells, treatment with IAA led to accumulation of higher levels of NF-κB in the nucleus than in the cytosol. The levels of cytosolic NF-κB, and nuclear lamin B1 in IAA-treated cells were lower than the corresponding levels in untreated cells. Conclusion : These results indicate that IAA inhibits proliferation, and induces apoptosis in 143B and HOS cells via activation of NF-κB, and its translocation to the nucleus. Therefore, IAA may be a useful drug target in the treatment of osteosarcoma. Keywords : Indole-3-acetate, Phosphatase, Fas receptor, Translocation, Proliferation, Tumoricidal activity
Highlights
Osteosarcoma (OS) is a frequently-occurring malignant tumour of the bone in people of various age groups such as children, adolescents and young adults
The results obtained in this study strongly suggest that indole-3-acetate inhibits the viability of osteosarcoma cells via induction of apoptosis, and by increasing the expressions of phosphatase and tensin homolog (PTEN), fas ligand and fas receptor
The results reveal that indole-3-acetate decreased the viabilities of 143B and HOS osteosarcoma cells through induction of apoptosis
Summary
Osteosarcoma (OS) is a frequently-occurring malignant tumour of the bone in people of various age groups such as children, adolescents and young adults. It has been demonstrated that indole compounds induce apoptosis, arrest cell cycle in G1 phase in cancer cells, and inhibit the invasive and metastasis potential of tumour cells [25,26,27] These effects are exerted through suppression of cell cycle protein expression (cyclin D1, E); inhibition of anti-apoptotic genes, and activation of caspases 3 and 9 [26,27]. Real-time RT-PCR was performed to study the effect of IAA on levels of expression mRNA in 143B and HOS cells. Each cell line was incubated at a density of 2 x 107 cells in 100-mm dishes for 48 h in DMEM containing IAA This was followed by RNA extraction using TRIzol reagent (Invitrogen) according to the manufacturer’s instructions.
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