Mouse Testicular Teratoma F9 Transfer Screening And Identification Of Key Genes

Cancer is among the leading causes of death in human, while more than90%of cancer patients die from cancer metastasis. Currently there is no effective treatment for cancer metastasis, this is mainly due to our lack of understanding of pathogensis, and especially the molecular mechanism of metastasis.To identify the critical genes that play causal roles in cancer metastasis, we applied a piggybac transposon based genome-wide mutagenesis platform, which contains a tetracycline mediated gene regulation system that allows reversible gene mutations. Therefore by screening of the reversible conversion from non-metastatic tumor cells to metastatic tumor cells as the results of genome-wide mutageneses, we can determine the critical genes with causal relationship with tumor metastasis. Clinical pathology studies showed that tumor metastatic potential is closely associated with tumor histological differentiation, and poorly differentiated tumors are often highly metastatic. We used a mouse F9teratoma cell line, which has stem cell properties and low metastatic potential, as model system for genome-wide screening of genes involved in metastasis.We have successfully established an efficient genome-wide mutagenesis system and metastasis models in F9teratoma cell line, and generated a libraries of F9cells containing more than1.09million gene mutations. We carried out a series of in vivo screening for metastatic tumor cells, and initially88highly metastatic cell lines were acquired. Following further validation with Doxycycline mediated gene regulation, we confirmed114highly metastatic tumor cell lines. Molecular cloning identified32genes whose mutations played causal roles in metastases of F9teratoma cells.Among these32genes, several genes had been showed to play important roles in tumor metastasis, such as Smadl, Tgfbr3and Ccnd3. Most of the newly identified genes are novel for tumor metastasis, such as WDR44, TSC22D1, Fam69and Pfas. These results verified the key roles of TGF-β signal pathway in tumor metastasis, and uncovered a novel down stream regulator of TGF-β pathway in tumor metastasis-TSC22D1, which plays critical roles in cell growth, apoptosis, senescence and cell differentiation. The critical role of TSC22D1in multiple organ metastases, including the lung, liver, muscle and kidney metastases, and the predicted role of TSC22D1as a gene specifc transcription repressor provides a novel mechanism of pathogenesis of tumor metastasis and implicates TSC22D1as potential biomark and therapeutical target for the diagnosis, treatment and prevention of cancer metastasis.