N-acetylglucosaminyltransferase V modulates radiosensitivity and migration of small cell lung cancer through epithelial-mesenchymal transition.

Abstract

N-acetylglucosaminyltransferase V (Gnt-V) has been linked to the migration of various human cancers. Recently we have found that inhibition of Gnt-V increases the radiosensitivity of cancer cells. However, the mechanisms by which Gnt-V mediates radiosensitivity and migration, especially in small cell lung cancer (SCLC) remain unknown. In our study, two SCLC cell lines (H1688 and H146) were used to investigate whether Gnt-V modulated the radiosensitivity and migration of SCLC cells through the epithelial-mesenchymal transition (EMT). The results showed that the expression of Gnt-V correlated with the N stage in patients with SCLC. Overexpression of Gnt-V led to a further increase in the relative viable cell number and survival fraction with a decrease in apoptosis rate and Bax/Bcl-2 ratio, when the cells were treated with irradiation. By contrast, knockdown of Gnt-V with irradiation resulted in a further decrease in the relative viable cell number and survival fraction but an increase in apoptosis rate and Bax/Bcl-2 ratio. Cells expressing high levels of Gnt-V increased migration whereas low levels of Gnt-V suppressed cell migration. Besides, the transient knockdown of ZEB2 led to an increase in radiosensitivity and an inhibition in the migration of SCLC cells. Furthermore, Gnt-V was negatively correlated with E-cadherin expression but positively correlated with N-cadherin, vimentin and ZEB2 expression. Finally, an in vivo study revealed that upregulation of Gnt-V caused tumour growth more quickly, as well as the expression of EMT-related markers (N-cadherin, vimentin and ZEB2). Taken together, the study suggested that an elevation of Gnt-V could lead to the radiosensitivity and migration of SCLC cells by inducing EMT, thereby highlighting Gnt-V as a potential therapeutic target for the prevention of EMT-associated tumour radioresistance and migration.