Crebanine N-oxide, a natural aporphine alkaloid isolated from Stephania hainanensis, induces apoptosis and autophagy in human gastric cancer SGC-7901 cells

Objective: To investigate the cytotoxic effects and the potential mechanisms of crebanine N-oxide in SGC-7901 gastric adenocarcinoma cells. Methods: The cytotoxicity of crebanine N-oxide was evaluated by 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2-H-tetrazolium bromide assay and cellular morphology was observed under a microscope. Cell apoptosis was determined by flow cytometry using propidium iodide staining. The expression levels of apoptotic-related proteins, cleaved caspase-3, cytochrome C, p53 and Bax, and autophagyrelated proteins p62, beclin1 and LC3 were detected by Western blotting assays. Results: Crebanine N-oxide treatment significantly inhibited the proliferation of SGC-7901 cells in a dose-dependent and timedependent manner via induction of G2-phase cell cycle arrest, apoptosis, and autophagy in SGC-7901 cells. Conclusions: Crebanine N-oxide could inhibit the growth of gastric cancer cells by promoting apoptosis and autophagy and could be used as a potential agent for treating gastric cancer.

[TALEN-mediated MYH9 Knock-down and its influence on cell cycle and apoptosis of MGC803 cell line].

OBJECTIVE: To construct a MYH9 gene knockout model in MGC803 cell line using transcription activator-like effector nuclease (TALEN) and observe its effect on cell cycle and apoptosis. METHODS: According to FastTALE(TM) TALEN Kit, we designed TALEN pairs and constructed the plasmids targeting to MYH9 gene. After detecting their activity in MGC803 cells by plasmid transfection, DNA sequencing, RT-PCR and western blot, we selected the monoclonal cells and studied the changes in the cell cycle and apoptosis. RESULTS: MYH9 gene could not be knocked out but knocked down in selected MGC803 monoclonal cells, which caused cell cycle arrested at G2/M phase (P<0.05) and a significant increase in the cell number with early apoptosis (P<0.01). CONCLUSION: We successfully generated a MYH9 knockdown model in MGC803 cell lines by TALEN, which could be in favor of MYH9 function study in gastric cancer.

SP1-mediated microRNA-520d-5p suppresses tumor growth and metastasis in colorectal cancer by targeting CTHRC1.

Recent evidence suggests that miR-520 family has an important role in regulating tumorigenesis and development of various types of solid cancers. However, as one of the most common cancers in the world, there is little known about the underlying regulatory mechanisms of miR-520 in colorectal cancer (CRC). In the present study, we investigated the expression of microRNA-520d-5p (miR-520d-5p) in CRC specimens and then explored its potential role and mechanism in CRC progression. We found that miR-520d-5p was markedly down-regulated in CRC clinical specimens compared with adjacent normal tissues by real-time PCR. Dual-luciferase assays confirmed that miR-520d-5p directly targeting CTHRC1 and SP1 transactivate miR-520d-5p by binding to its upstream promoter region. The biological functional experiments showed that ectopic re-expression of miR-520d-5p suppressed CRC cell proliferation, migration and invasion, whereas the inhibition of miR-520d-5p displayed an inverse effect in vitro and in vivo. Western blot shown that miR-520d-5p abrogated the epithelial-mesenchymal transition by inactivating the phosphorylation of Erk1/2. In conclusion, our findings indicate that miR-520d-5p is significantly down-expressed and involved in CRC progression and metastasis by targeting CTHRC1 and regulated by SP1, which provide new support for miR-520d-5p maybe as a novel anti-onco molecular target for the treatment of CRC in the future.

[Role of CTHRC1 in proliferation, migration and invasion of human colorectal cancer cells].

OBJECTIVE: To explore the expression of collagen triple helix repeat containing 1 (CTHRC1) in colorectal cancer and study its role in regulating the biological behaviors of colorectal cancer LoVo cells in vitro. METHODS: Real-time PCR and Western blotting were used to detect the expressions of CTHRC1 in colorectal cancer tissue and paired adjacent nontumorous tissue and in 5 colorectal cancer cells. pGPU6-CTHRC1-shRNA was transfected into LoVo cells and the changes in cell proliferation was assessed using cell counting kit-8 (CCK8) assay; the changes in cell migration and invasion were investigated using Transwell assay; plate colony forming test was used to evaluate the adhesion and colony forming activity of the cells. Western blotting was used to analyze the changes in the expressions of the related pathway markers. RESULTS: The relative expression of CTHRC1 mRNA in the cancer tissue specimens was 0.0411∓0.054, significantly higher than that in the adjacent tissues (P=0.016); this result was consistent with that of the protein assay. SW620 and LoVo cells showed obviously higher expressions of CTHRC1 than HT29 and SW480 cells at both mRNA and protein levels. LoVo cells transfected with CTHRC1 shRNA exhibited significantly suppressed proliferation, migration, invasion and colony-forming ability (P<0.05) and lowered expression of phosphorylated ERK1/2 (P-ERK1/2), but the expression of total ERK1/2 showed no obvious changes. CTHRC1 inhibition caused reverse epithelial-mesenchymal transition LoVo cells shown by increased E-cadherin expression and decreased expressions of N-cadherin, vimentin, and ß-catenin. CONCLUSION: CTHRC1 is up-regulated in colorectal cancer tissues and SW620 and LoVo cells to promote the cell proliferation, migration, invasion and colony formation. CTHRC1 can enhance epithelial-mesenchymal transition of colorectal cancer cells by activating ERK1/2 to promote tumor cell metastasis and invasion.

Identification of the interplay between SOX9 and S100P in the metastasis and invasion of colon carcinoma.

Elevated expression of S100P has been detected in several tumor types and suggested to be responsible for tumor metastasis and invasion, but the upstream regulatory mechanisms promoting S100P overexpression are largely unknown. Here, we report that SOX9 was predicted and verified as a transcription factor of S100P. SOX9 and S100P were both overexpressed in colon cancer. SOX9 bound to and activated the S100P promoter. Knockdown of SOX9 expression down-regulated S100P expression, resulting in reduced invasiveness and metastasis of colon cancer cells by inhibiting the activation of receptor for advanced glycation end products (RAGE)/ERK signaling and epithelial-mesenchymal transition (EMT). Further, decreased expression of SOX9 dramatically inhibited the tumor growth and peritoneal metastasis in nude mice. More importantly, S100P was found to be critical for SOX9-mediated metastasis and invasion in colon cancer. Knockdown of S100P in SOX9-overexpressing colon cancer cells dramatically suppressed metastasis and invasion both in vitro and in mice. We also detected SOX9 and S100P expression in a tissue microarray with 90 colon cancer cases to provide their clinical relevance. There was a strong correlation between SOX9 and S100P expression in colon carcinomas. In conclusion, our results suggest that SOX9 promotes tumor metastasis and invasion through regulation of S100P expression.