Snail promotes metastasis of nasopharyngeal carcinoma partly by down-regulating TEL2

Background:Metastasis is the major cause of treatment failure in patients with nasopharyngeal carcinoma(NPC).We previously reported that TEL2,a negative regulator of SERPINE1,could inhibit NPC metastasis to lymph nodes.Method:A series of in vivo and in vitro assays were performed to elucidate the regulation between Snail and TEL2.TEL2 expression was analyzed in three representative NPC cell lines expressing low levels of Snail(S26,6-10B,HK1)and two cell lines expressing high levels of Snail(S18,5-8F).Luciferase and chromatin immunoprecipitation assays were used to analyze the interaction between Snail and TEL2.The roles of the Snail/TEL2 pathway in cell migration and invasion of NPC cells were examined using transwell assays.Metastasis to the lungs was examined using nude mouse receiving NPC cells injection through the tail vein.Results:Ectopic Snail expression down-regulated TEL2 at the mRNA and protein levels,whereas knockdown of Snail using short hairpin RNA up-regulated TEL2.Luciferase and chromatin immunoprecipitation assays indicated that Snail binds directly to the TEL2 promoter.Ectopic Snail expression enhanced migration and invasion of NPC cells,and such effects were mitigated by TEL2 overexpression.TEL2 overexpression also attenuated hypoxia-induced cell migration and invasion,and increased the number of metastatic pulmonary nodules.Snail overexpression reduced the number of metastatic pulmonary nodules.Conclusions:TEL2 is a novel target of Snail and suppresses Snail-induced migration,invasion and metastasis in NPC.

Quantitative comparisons between relaxation enhanced compressed sensing 3D MERGE and conventional 3D MERGE for vessel wall imaging in equal scan time: preliminary studies

In this study, we quantitatively compared relaxation enhanced compressed sensing(RECS-3D MERGE) with conventional 3D MERGE techniques on blood suppression efficiency, wall-lumen contrast and plaque burden measurement for carotid atherosclerotic imaging in equal scan time. Twelve patients were recruited in the study. RECS-3D MERGE and conventional 3D MERGE were implemented. 2D DIR-FSE was carried out as a reference standard. The lumen signal-to-tissue ratio(STR) was used as the quantitative measure of blood suppression efficiency. The contrast-to-tissue ratio(CTR) was used as the quantitative measure of wall-lumen contrast. Vessel lumen area(LA) and wall area(WA) were measured for morphological comparisons. The lumen STR of RECS-3D MERGE was significantly lower than that of 3D MERGE while the wall-lumen CTR of RECS-3D MERGE was significantly higher. There were no significant differences in plaque burden measurements between RECS-3D MERGE and 2D DIR-FSE. For comparison between conventional 3D MERGE and 2D DIR-FSE, there were no significant differences in LA measurement. However, the WA of 3D MERGE was significantly larger. The RECS-3D MERGE sequence achieved more sufficient blood suppression and higher image contrast without prolonging the scan time. These improvements lead to more accurate morphological measurements of carotid atherosclerotic imaging.