Silencing of STRN4 suppresses the malignant characteristics of cancer cells.
Bottom Line: We previously reported that STRN4 directly associated with protein kinases, such as MINK1, TNIK and MAP4K4, which are associated with tumor suppression or tumor progression.However, it remains unclear whether STRN4 is associated with tumor progression.Our results demonstrate a possible role of STRN4 in tumor progression.
Affiliation: Department of Gastroenterology and Hepatology, Nagoya University Graduate School of Medicine, Nagoya, Japan.Show MeSH
Related in: MedlinePlus
Mentions: We next investigated whether STRN4 knockdown affects cell migration and invasion. To assess changes in cell migration, we first performed a wound healing assay. Confluent monolayers of KP4, HCT116, TE1 and SKOV3 cells transfected with siRNA were scratched, and the migration of the cells into the free space was observed 24 h later. The migration of STRN4-depleted cells was clearly delayed compared with that of the control siRNA-transfected cells (Fig. 2a). To further confirm this result, we used a modified Boyden chamber assay. Cells transfected with siRNA were placed on the upper surface of the filter and allowed to migrate to the bottom surface, which was coated with fibronectin. Cells that migrated to the bottom surface were quantified. The migration of STRN4-depleted cells was suppressed compared with that of the control siRNA-transfected cells (Figs 2b, S2a). To investigate the effect that STRN4 suppression had on cell invasion, we used a Matrigel-coated Boyden chamber. The invasion of cancer cells was significantly reduced by STRN4 knockdown (Figs 2c, S2b). To exclude the possibility that the suppression of cell migration and invasion was an off-target effect of siRNA, we performed a rescue experiment using KP4 cells. We first established KP4 cell lines that constitutively expressed a Flag tag (Flag-KP4) or STRN4 (STRN4-KP4) by retroviral infection. We then used siRNA that targeted the 3′ UTR of STRN4 (siSTRN4-3). Transfection of siSTRN4-3 efficiently suppressed the endogenous STRN4 in Flag-KP4 cells but not the exogenously expressed STRN4 in STRN4-KP4 cells (Fig. 2d). The expression of exogenous STRN4 clearly rescued the suppression of migration and the invasion induced by siSTRN4-3 transfection (Fig. 2e). These results indicate that STRN4 depletion suppresses cell migration and invasion.
Affiliation: Department of Gastroenterology and Hepatology, Nagoya University Graduate School of Medicine, Nagoya, Japan.