Osteosarcoma (OS) is the most common primary malignancy of bone, with up to 80% of patients suffering from metastatic or micrometastatic disease at the time of diagnosis. For the metastatic potential of tumours invasiveness plays an important role. This study intends to determine new candidate genes for cell invasiveness.

Eight OS cell lines (MNNG, HOS, MG63, SJSA1, OST, ZK58, U2OS, SAOS) were analysed using a modified Boyden Chamber Assay to separate invasive and non-invasive cells. Total RNA isolation and Illumina hybridisation Arrays (V3 bead arrays) were performed for both fractions.

Out of the eight cell lines, five (MNNG, HOS, MG63, SJSA1, OST) displayed an invasive fraction between 1.76 and 0.02%, which proved sufficient for subsequent RNA analysis. Pair wise comparison yielded 161 differently expressed genes between invasive and non-invasive cells. These are involved in important pathways such as cell motility, cell communication or signal transduction.

The generated new candidate genes might play an important role in metastasis of OS. Their functional characterization has been started combining knockdown experiments (RNAi) with the invasion assay. Validation will be done by RT-PCR and immunohisto-chemistry on a larger sample using OS-TMAs. Determined genes and pathways will be correlated with clinical parameters like metastasis, survival and chemotherapy sensitivity in order to improve understanding of the biology of OS.