lincRNA-p21 Mediates the Anti-Cancer Effect of Ginkgo Biloba Extract EGb 761 by Stabilizing E-Cadherin Protein in Colon Cancer.

BACKGROUND Ginkgo biloba extract EGb 761 is a putative antioxidant and has been used for thousands of years to treat a variety of ailments, including cancer. While it is known that cell behavior can be modulated by long non-coding RNAs (lncRNAs), the contributions of lncRNAs in EGb 761-induced anti-cancer effects are largely unknown. MATERIAL AND METHODS Colon cancer cell lines HT29 and HCT116 were used in this study. RT-qPCR was used to detect the relative expression of lincRNA-p21 in colon cancer cells. Wound-healing assay and Matrigel Transwell assay were performed to investigate the migration and invasion of colon cancer cells. Immunoprecipitation and Western blot experiments were used to verify ubiquitination and the interaction between lincRNA-p21 and E-cadherin, or E-cadherin and b-transducin repeat containing (BTRC) E3 ubiquitin protein ligase. RESULTS Cell function assay verified that treatment with EGb 761 suppressed the migratory and invasive abilities of colon cancer cells in a dose-dependent manner via the suppression of E-cadherin expression level. lincRNA-p21 was upregulated in colon cancer cells after treatment with EGb 761, and knockdown of lincRNA-p21 reversed the EGb 761-induced anti-metastatic effect. Furthermore, lincRNA-p21 was localized in cytoplasm of colon cells and regulated E-cadherin expression at a post-transcriptional level. Specifically, lincRNA-p21 promotes E-cadherin stability by preventing the interaction between BTRC and E-cadherin, which leads to the inhibition of E-cadherin ubiquitination. CONCLUSIONS We demonstrated that lincRNA-p21 mediates the anti-cancer effect of Ginkgo biloba extract EGb 761 by stabilizing E-cadherin protein in colon cancer, which may help define the functional role of EGb 761 in cancer treatment.

Ginkgo biloba extract EGb 761-induced upregulation of LincRNA-p21 inhibits colorectal cancer metastasis by associating with EZH2.

EGb 761, the standard ginkgo biloba extract, is frequently prescribed in traditional Chinese medicine. Currently, there is no research focusing on its role in human colorectal cancer progression. In our study, we determined the anti-metastatic effect of EGb 761 on colorectal cancer cells and further explored the potential underlying regulatory mechanism. The cell migration and invasion assay indicated that EGb 761 treatment of colorectal cancer cells induced inhibition of cell migration and invasion ability in a concentration-dependent manner. To further explore the underlying regulatory mechanisms that may account for these findings, we performed quantitative real-time PCR (RT-qPCR), western blotting and immunoprecipitation analysis. The results showed that EGb 761 induced upregulation of LincRNA-p21 expression in a dose- and time-dependent manner. Overexpression of LincRNA-p21 also suppressed colorectal cancer cell metastasis. Furthermore, EGb 761 as well as LincRNA-p21 inhibited the expression of extracellular matrix protein, fibronectin. More importantly, RNA immunoprecipitation (RIP) and Chromatin immunoprecipitation (ChIP) assays showed that LincRNA-p21 directly interacted with EZH2, and this interaction suppressed the expression of fibronectin. Finally, the gain and loss function assay revealed that EGb 761 inhibited migration, invasion and fibronctin expression by the LincRNA-p21/EZH2 pathway in colorectal cancer cells. Hence, EGb 761 may be a promising treatment regimen for colorectal cancer and restoration of LincRNA-p21 levels may be helpful for enhancing the anti-cancer effect of EGb 761.