Effects of Ibandronate on the Expression of Matrix Metalloproteinases in Human U2OS Osteosarcoma Cells

사람 U2OS 골육종 세포에서 Matrix Metalloproteinase의 발현에 Ibandronate가 미치는 영향

Background: Osteosarcoma is one of the most common primary malignant tumors of bone occurring mainly in children and adolescents. Although surgery combined with chemotherapy has markedly improved patient survival during the last years, the use of anticancer drugs is still associated with serious problem, such as the frequent acquisition of drug-resistant phenotypes and occurrence of "secondary malignancies". Several solid tumors display enhanced expression of matrix metalloproteinases (MMPs), and recently clinical trials have been initiated on MMP-inhibitors. On the other hand, bisphosphonates (BPs) are inhibitors of bone resorption, and widely used to treat osteoclast-mediated bone diseases. Also they appear to possess direct antitumor activity. Methods: One osteosarcoma cell line (U2OS) was treated with ibandronate (0, 0.1, 1, $10{\mu}M$) for 48 hours. Cell viabilities were determined using MTT assay, the mRNA levels of MMP-2 and MT1-MMP were detected by reverse-transcription polymerase chain reaction, the amount of MMP-2 and MT1-MMP protein were measured by Westernblot, the activities of MMP-2 were observed by Gelatin zymography, and Matrigel invasion assays were used to investigate the invasive potential of osteosarcoma cell lines before and after ibandronate treatment. Results: The invasiveness of U2OS cell line was reduced dose-dependently following 48 hour treatment of up to $10{\mu}M$ of the ibandronate at which concentration no cytotoxicity occurred. Furthermore, the gelatinolytic activities and protein and mRNA levels of MMP-2 and MT1-MMP were also suppressed by increasing ibandronate concentrations. Conclusion: Given that MMP-2 is instrumental in tumor cell invasion, it is very likely that the reduction in osteosarcoma cell invasion by ibandronate is a consequence, at least in part, of suppressed expression of both MMP-2 and MT1-MMP. Isolation of a molecule (s) responsible for the bisphosphonate inhibition of tumor cell invasion would pave the way for the development of a new generation of metastasis inhibitors.

배경: 골육종은 소아 및 청소년기에 가장 흔하게 발생하는 악성 골종양 중 하나이다. 최근 수술적 치료와 항암 화학요법을 병행하여 생존률이 증가하였지만, 아직까지도 항암제는 항암제 내성 및 이차성 악성 종양의 발생 등 여러 문제점을 가지고 있다. 일부 종양은 matrix metalloproteinase(MMPs)의 발현이 증가되어 있고, MMP inhibitor에 대한 연구가 진행되고 있다. 반면 bisphosphonate(BPs) 제제는 골흡수를 억제하는 능력이 있으며, 파골세포와 관계된 골 병변에 광범위하게 사용되고 있다. 또 bisphosphonate 제제는 직접적인 항암효과를 가지고 있는 것으로 알려져 있다. 대상 및 방법: 골육종 세포주(U2OS)를 ibandronate(0, 0.1, 1, 10M)를 이용하여 48시간 동안 처치하였다. 세포의 생존능은 MTT assay를 이용하여, MMP-2와 MT1-MMP의 mRNA level은 reverse-transciption polymerase chain reaction을 이용하여 측정하였으며, MMP-2와 MT1-MMP 단백의 양은 Westernblot을, MMP-2의 활성은 Gelatin zymography를 이용하여 측정하였다. 또, ibandronate 처치 전후의 골육종 세포주의 침습성은 Matrigel invasion assay를 이용하여 측정하였다. 결과: 48시간 ibandronate 처치 후 U2OS 세포주의 침습력은 ibandronate에 대해 용량 의존적으로 감소하였다. 특히 10M 이내의 ibandronate는 세포독성이 나타나지 않았다. 젤라틴 융해능과 MMP-2 및 MT1-MMP의 단백 및 mRNA 정도역시 ibandronate 농도가 증가할수록 감소하였다. 결론: Ibandronate는 골육종 세포주의 MMP-2 및 MT1-MMP의 발현을 억제하였으며, 종양세포의 침습력을 감소시켰다. Bisphosphate의 종양세포 침습 억제 능력은 새로운 전이 억제제의 개발에 도움이 될 것으로 사료된다.