A previous study has reported that frequent amplifications of the TG-interacting factor (TGIF) were observed in esophageal squamous cell carcinoma. suppressed EC109 cell proliferation, colony formation in soft agar and tumor growth in nude mice, induced cell cycle arrest in the G1 phase, and promoted cisplatin-induced apoptosis. In addition, TGIF knockdown significantly reduced the expression of phospho-Rb in EC109 cells. The reduced level of full length PARP expression and the increased level of cleaved caspase-3 expression were observed in EC109 cells with the treatment of cisplatin and TGIF knockdown. The results suggest that knockdown of TGIF attenuated the proliferation and tumorigenicity of EC109 cells, and advertised cisplatin-induced apoptosis. reported that frequent amplifications of TGIF were observed in esophageal squamous cell carcinoma (ESCC) (22), which suggests that TGIF might be associated with esophageal tumorigenesis. But, the potential part LY2109761 distributor of TGIF in the proliferation and tumorigenicity of esophageal malignancy cells is not clear. In the present study, we knocked down TGIF of EC109 cells with short hairpin RNA (shRNA) lentiviruses and observed the capabilities of proliferation and tumorigenicity of stable TGIF-knocked down EC109 cells and and were inhibited when the manifestation of TGIF was knocked down by shRNA specifically targeting TGIF, which suggests that TGIF may act as an oncogene in the development of esophageal malignancy. Knockdown of TGIF caught the cell cycle of EC109 cells in the G1 phase by downregulating phospho-Rb. In addition, knockdown of TGIF advertised cisplatin-induced apoptosis of EC109 cells. Cell cycle arrest is one of the major causes of malignancy cell proliferation inhibition (23,24). Dysregualtion of several important factors, including CDK4, cyclin D1, p21 and phospho-Rb could result in G1 phase arrest (25,26). In this study, we observed that knockdown of TGIF induced cell cycle arrest in the G1 phase accompanied with significantly decreased manifestation of phospho-Rb protein, while other proteins such as CDK4, cyclin D1 and p21 did not significantly switch. Studies have shown that activation of cyclin D1-CDK4 complex can phosphorylate Rb and keep Rb inactivation, therefore promote Rabbit Polyclonal to FGB G1/S phase transition (27,28). Our earlier data showed that silencing of TGIF induced G1 phase cell cycle arrest along with the decreased manifestation of phospho-Rb, cyclin D1 and CDK4 in lung malignancy cells (10). Collectively, the current observations suggests that knockdown of TGIF led to the decreased manifestation of phospho-Rb not through regulating CDK4 and cyclin D1 manifestation in esophageal malignancy cells. Further studies should focus on the mechanisms linking TGIF and phospho-Rb in esophageal malignancy. Previous studies have shown that wnt/-catenin pathway is definitely involved in the development of esophageal malignancy (29,30) and -catenin is the important regulator in the wnt/-catenin signaling pathway. Deng reported that aberrant manifestation of -catenin was recognized in 54.3% (114 of 265) of ESCC (31). The level of -catenin manifestation in ESCC was significantly higher than that in the adjacent non-cancerous cells (32,33). The overexpression of -catenin was aggressively associated with LY2109761 distributor lymph node metastasis, advanced pathological stage and prognosis of the individuals with ESCC (32). In addition, Xu and Lu reported that -catenin was involved in miR-214 inhibiting esophageal malignancy cell growth and invasion (33). Jia found that RAP1B activated wnt/-catenin signaling in ESCC (34). However, with this present study, we found that knockdown of TGIF experienced no obvious effects on the manifestation of -catenin and Axin1 proteins in esophageal malignancy cells, which suggests the wnt/-catenin signaling pathway is probably not involved in knockdown of TGIF inhibiting the tumorigenicity of esophageal malignancy cells. Previous studies showed that TGIF could regulate the manifestation of -catenin protein in breast malignancy (9) and lung malignancy (10,12). Taken together, the rules of -catenin by TGIF might be dependent on tumor types. With this study, we observed that knockdown of TGIF suppressed the tumorigenicity of esophageal malignancy cell of EC109 and cisplatin could repress the manifestation of TGIF protein. We further investigated the potential part of TGIF in cisplatin-induced apoptosis of EC109 cells. Our data showed that knockdown of TGIF advertised cisplatin-induced apoptosis of EC109 cells, along with the alterations of apoptosis-related markers, such as the decreased level of full length PARP protein manifestation and the improved level of cleaved caspase-3 protein manifestation. Studies suggested the cleavage of caspase-3 was an early event in apoptosis induced by chemotherapeutic LY2109761 distributor providers (35). Activation of caspase-3 was partially or totally responsible for proteolytic cleavage of many important proteins such as PARP (36,37). Liu reported that knockdown of TGIF enhanced arsenic trioxide-induced apoptosis in HepG2 cells (38). Collectively, our findings indicated that TGIF was likely to be a potential restorative target for the treatment of esophageal malignancy. To the best of our knowledge, only one published study reported the association of TGIF amplifications with esophageal malignancy (22). Although, in this study, we primarily acquired exciting data within LY2109761 distributor the potential part of TGIF in the proliferation and tumorigenicity of esophageal malignancy cells, some limitations should be acknowledged. First,.