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Objective To provide a new putative target for immunotherapy on osteosarcoma and explore the effect of matrix metalloproteinase-9 (MMP-9) on the formation of soluble MICA protein in osteosarcoma cells. Methods MMP-9 antisense oligonucleotide was transfected to osteosarcoma cells with lipofectamine 2000. MMP-9 mRNA was assessed by RT-PCR. MMP-9 activity and soluble MICA (sMICA) in the culture supernatant was examined by zymography and quantified by ELISA, respectively. Results MMP-9 mRNA expression and gelatin enzymatic activity were inhibited in MMP-9 antisense oligonucleotide group. Comparing with the control group, lower concentration of sMICA was found in MMP-9 antisense oligonucleotide group (P = 0.011). Conclusion MMP-9 may have an effect on the formation of sMICA protein in osteosarcoma. MMP-9 could be regarded as a putative target for immunotherapy in osteosarcoma.
RESUMEN
[Objective] To investigate the expression of MICA mRNA and protein in osteosarcoma and give a more comprehensive understanding to its immune evasion.[Methods] RT-PCR was used to analyze MICA mRNA in 11 osteosarcoma tissues and 5 osteosarcoma cell lines.MICA expression was examined in 66 paraffin-embedded osteosarcoma tissues and 6 paraffin-embedded normal bone tissues by immunohistochemistry,and MICA protein in 9 fresh osteosarcoma tissues was detected by Western blot too.MICA surface expression was estimated by flow cytometry.[Results] Nine of eleven (81.8%) osteosarcoma specimens and all of the five cell lines consistently expressed MICA mRNA.Up-regulation of MICA expression was found in osteosarcoma (34/66,51.6%),compared with normal bone tissues (0/6,0%).The cell lines Saos-2,MG63,and HOS showed positive surface MICA expression,while the U2OS and OS732 showed very limited expression.[Conclusion] MICA mRNA and protein predominantly expressed on osteosarcoma tissues and cell lines.