Metastatic lesions of enough the lung were identified with hardened tissues, and those of the intestine formed white, small sized cysts. RT PCR results obtained using RNA from metastatic lesion tis sues indicated that these lesions contain the fLuc gene and therefore originate from C6L cells in the primary cancer located a distance away. Histological analysis with H E staining revealed that the metastatic lesions are typical cancerous lesions with poorly differentiated morphology, compared with those of healthy lung and intestine tissue. IHC examination with anti E cadherin and anti vimentin antibodies further showed that cancer Inhibitors,Modulators,Libraries sites in metastatic lesions contain low E cadherinhigh vimentin levels, while conversely, normal tissue sites present with high E cadherinlow vimentin expression levels.

These results were inconsistent with the typical EMT theory hypothesizing Inhibitors,Modulators,Libraries that Inhibitors,Modulators,Libraries increases in cancer cell migrationinvasion via induction of EMT promote can cer cell movement to a new site for metastasis formation and that mesenchymal to epithelial transition is required for settlement of cancer cells. However, several clinical reports indicate that loss of E cadherin in gastriccolorectal cancer and increased vimentin expres sion in NSCLCgastric Inhibitors,Modulators,Libraries cancer are markers for cancer progression, metastasis and poorer prognosis. Therefore, we could postulate that MET might be a transient event that is induced to promote formation of the metastasis site, followed by progression of metastatic lesions. However, there are other possibilities that EMT might not be the main or only cause of radiation induced metas tasis in our system, because Tarin et al.

reported no con firmative evidence that EMT can be induced in vivo. Instead, fused hybrids of macrophages and non metastatic cancer stem cells can metastasize in vivo. More Inhibitors,Modulators,Libraries over, Mor Vaknin et al. reported that activated macro phages induce secretion of vimentin and up regulate MMP proteins. Because radiation might be a cause of macrophage cancer cell fusion, fusion hybrids of macrophages and cancer cells in our system might be dis covered. According to Kliopp et al. irradiated tumors re cruit circulating mesenchymal stem cells into their microenvironment by increasing expression of several cytokines that might activate macrophages. These previous reports suggest that further studies on the rela tionship between the immune system and radiation related metastasis are needed to validate our animal model. EMT expression markers at distal metastatic lesions are also required to investigate the relationship with the immune system. Together, our results suggest that radiotherapy alone could promote metastasis as an undesired effect and IR induced metastasis in vivo is Wortmannin ATM evoked via the EMT pathway.