Molecular Pathology of Rat Osteosarcoma and Malignant Fibrous Histiocytoma

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1) We investigated TGF- β isoforms by Multi-probe RNA protection assay in COS1NR, COS2NR, COS4NR, MFH1NR and MFH2NR. The results showed TGF- β1to be strongly expressed and no TGF- β2 and 3 detected in MEHs, while TGF-β1 and 2 was found to be moderately and 3 weakly expressed in OS cell lines. No changes in TGF- βtype II receptor expression, and no mutations of TGF- β type II receptor, Smad2 and 4 genes were detected by RT-PCR and RT-PCR restricted SSCP analysis.2) The effect of STI571 was investigated on rat osteosarcoma and MFH cell lines. The cell growth of all cell lines was inhibited in a time- and dose-dependent manner. The inhibition rate were greater for MFH cell lines, about 40%, while about 20% for osteosarcoma cell lines. The difference of effectiveness was depend on PDGFR α expression.3) We investigated the expression and methylation status of 16^<INK4a> gene in rat osteosarcoma and malignant fibrous histiocytoma as well as rat lung adenocarcinoma cell lines. The PCR-SSCP analysis showed no expression of p16 gene in lung adenocarcinoma, while similar expression in ostesarcomas and MFHs as normal fibroblasts. The region close to coding region was hypermethylated in osteosarcoma, in contrast, the region nearby TATA box was consistently methylated in lung adenocarcinoma, MFHs and fibroblasts were hypomethylated in both regions.4) The effect of HMR1275 was investigated on rat osteosarcoma, MFH cell lines and lung adenocarcinoma cell lines. The cell growth of all cell lines was inhibited in a time- and dose-dependent manner. The inhibition rate were the greatest for lung adenocarcinoma cell lines, about 80%, while about 60% for osteosarcoma and MFH cell lines. The induction of p16 gene by the treatment of 5-aza 2'-deoxycytidine enhances the effects of HMR1275.