RNA Editing Enzyme ADAR1 Regulates METTL3 in an Editing Dependent Manner to Promote Breast Cancer Progression via METTL3/ARHGAP5/YTHDF1 Axis.

A-to-I RNA editing and m6A modification are two of the most prevalent types of RNA modifications controlling gene expression in mammals and play very important roles in tumorigenesis and tumor progression. However, the functional roles and correlations of these two RNA modifications remain to be further investigated in cancer. Herein, we show that ADAR1, an A-to-I RNA-editing enzyme, interacts with METTL3 and increases its protein level to promote the proliferation, migration and invasion of breast cancer cells through a mechanism connecting ADAR1, METTL3 and YTHDF1. We show that both ADAR1 and METTL3 are upregulated in breast cancer samples, and ADAR1 positively correlates with METTL3; ADAR1 edits METTL3 mRNA and changes its binding site to miR532-5p, leading to increased METTL3 protein, which further targets ARHGAP5, recognized by YTHDF1. Additionally, we show that loss of ADAR1 significantly inhibits breast cancer growth in vivo. Collectively, our findings identify the ADAR1-METTL3 axis as a novel, important pathway that connects A-to-I editing and m6A RNA modifications during breast cancer progression.

MsrB1 Promotes Proliferation and Invasion of Colorectal Cancer Cells via GSK-3ß/ß-catenin Signaling Axis.

Methionine sulfoxide reductase B1 (MsrB1) can catalyze both free and protein-bound R-methionine sulfoxides (R-MetO) to methionine (Met). It has been reported that MsrB1 plays an important role in the development of HCC and human bone osteosarcoma. However, little is known about the functions of MsrB1 in human colorectal cancer (CRC). Herein, we detected MsrB1 expression level in CRC tissue and cell lines, and investigated the effect of MsrB1 knockdown on CRC phenotypes and possible mechanisms involved in. The results showed that MsrB1 was highly expressed in both CRC tissues and cell lines, and that cell proliferation, migration and invasion were significantly inhibited, but apoptosis was increased after MsrB1 knockdown in colorectal cancer HCT116 and RKO cell lines, compared to control siRNA group. In addition, E-cadherin protein level was increased, vimentin and Snail protein were greatly decreased after knockdown of MsrB1 in cells. Furthermore, pGSK-3ß (Ser9) and ß-catenin protein levels were reduced, the promoter activity of TCF/LEF construction was inhibited after MsrB1 knockdown in cells, suggesting that GSK-3ß/ß-catenin signaling axis was involved in the tumorigenesis of CRC. In conclusion, the oncogenic role and related mechanisms of MsrB1 in CRC discovered in our work determined the potential role of MsrB1 as a biomarker and may provide a new target for clinical therapy of CRC.

Up-regulation of Krüppel-like factor 8 promotes tumor invasion and indicates poor prognosis for hepatocellular carcinoma.

BACKGROUND & AIMS: The transcription factor Krüppel-like factor 8 (KLF8) has a role in tumor development, growth, and metastasis, but its role in hepatocellular carcinoma (HCC) is not clear. METHODS: KLF8 expression in human HCC cell lines and tumor tissues was measured by quantitative real-time polymerase chain reaction, immunoblot, and immunochemical analyses. The effects of KLF8 depletion or overexpression in HCC cells were observed in cultured cells and in mice. Changes in gene expression patterns in HCC cells in which levels of KLF8 were reduced using small interfering RNA were investigated by microarray analysis. The clinical significance of KLF8 expression levels were validated using tissue microarray analysis of surgical samples from 314 HCC patients. RESULTS: KLF8 was overexpressed in highly metastatic HCC cell lines and in samples from patients with recurrent HCC. In cultured cells, KLF8 up-regulation promoted cell proliferation and invasion; inhibited apoptosis; down-regulated N-cadherin, vimentin, and fibronectin; and up-regulated E-cadherin. In mice, overexpression of KLF8 increased HCC progression and metastasis. Microarray analysis showed that reduction of KLF8 in HCC cells down-regulated expression of multiple genes involved in tumor progression and metastasis. KLF8 expression was a significant predictor of overall survival (P = .040) and time to HCC recurrence (P = .006) and was associated with early tumor recurrence (P = .001). CONCLUSIONS: KLF8 promotes HCC cell proliferation and invasion, inhibits apoptosis, and induces the epithelial-to-mesenchymal transition. KLF8 up-regulation might be used to indicate poor prognosis or early recurrence of cancer in patients who have had surgery for HCC.

Small interference RNA targeting Krüppel-like factor 8 inhibits the renal carcinoma 786-0 cells growth in vitro and in vivo.

PURPOSE: Krüppel-like factor 8 (KLF8) plays an important role in oncogenic transformation and is highly overexpressed in several types of human cancer. We investigated the expression of KLF8 in renal cell carcinoma (RCC) tissues and the role of small interference RNA targeting KLF8 on growth, cell cycle, and apoptosis of human renal carcinoma cell line 786-0 in vitro and in vivo. METHODS: The expression of KLF8 protein and mRNA in human renal carcinoma samples was detected by immunochemistry and reverse transcription polymerase chain reaction (RT-PCR). The effects of small interference RNA (siRNA) targeting KLF8 on growth, invasiveness, cell cycle, and apoptosis of 786-0 cells were evaluated by MTT assay, Matrigel Invasion Assay, and flow cytometry in vitro. We also investigated effect of siRNA targeting KLF8 on growth of 786-0 cells in nude mice in vivo. RESULTS: Immunohistochemistry and RT-PCR results showed the expression of KLF8 protein and mRNA in RCC specimens was significantly higher than that in the adjacent non-tumorous renal tissues (P < 0.001). KLF8-siRNA depressed the cellular growth and invasion of 786-0 cells in vitro. The flow cytometry results revealed that KLF8-siRNA could induce an increase in G0/G1 phase cells and induce cell apoptosis. Intratumor injection of siRNA targeting KLF8 inhibited the growth of 786-0 cells in vivo in nude mice tumor model. CONCLUSIONS: KLF8 possibly involved in regulating the cell growth, invasion, apoptosis, and proliferation of renal carcinoma cancer cells. Blocking the KLF8 channel might be a potential therapeutic strategy for RCC.

CD24 is a novel predictor for poor prognosis of hepatocellular carcinoma after surgery.

PURPOSE: To investigate the role of CD24 in tumor invasion and prognostic significance in hepatocellular carcinoma (HCC). EXPERIMENTAL DESIGN: CD24 expression was measured in stepwise metastatic HCC cell lines, tumor, peritumoral tissues, and normal liver tissues by quantitative real-time PCR and Western blot. The role of CD24 in HCC was investigated by CD24 depletion using small interfering RNA. Tumor tissue microarrays of 314 HCC patients who underwent resection between 1997 and 2000 were used to detect expression of CD24, beta-catenin, and proliferating cell nuclear antigen. Prognostic significance was assessed using Kaplan-Meier survival estimates and log-rank tests. RESULTS: CD24 was overexpressed in the highly metastatic HCC cell line and in tumor tissues of patients with recurrent HCC. Depletion of CD24 caused a notable decrease in cell proliferation, migration, and invasiveness in vitro. Univariate and multivariate analyses revealed that CD24 was a significant predictor for overall survival and relapse-free survival. CD24 expression was correlated with poor prognosis independent of alpha-fetoprotein, tumor-node-metastasis stage, and Edmondson stage. High CD24 expression was significantly associated with cytoplasmic and nuclear accumulation of beta-catenin (P = 0.023), high tumor proliferative status (P = 0.018), and diffused intrahepatic recurrence and distant metastasis (P = 0.026). Adjuvant transcatheter arterial chemoembolization after surgery reduced the rate of early recurrence (

Role of overexpression of CD151 and/or c-Met in predicting prognosis of hepatocellular carcinoma.

UNLABELLED: It has been reported that tetraspanin CD151 acts as a promoter of metastasis in several tumors and plays an important role in c-Met/hepatocyte growth factor signaling. However, the role of CD151 alone and coexpression of CD151/c-Met in hepatocellular carcinoma (HCC) remains unclear. We found that expression of CD151 was positively related to metastatic potential of HCC cell lines, and modified cells with CD151(high) showed higher secretion of matrix metalloproteinase 9 and aggressiveness in vitro and higher metastatic ability in vivo. Furthermore, HCC patients with vascular invasion, large tumors, multiple tumors, high tumor-node-metastasis stage, and undifferentiated tumor were prone to have higher CD151 expression. The postoperative 3-, 5-, and 7-year overall survival (OS) of patients in HCCs with CD151(high) were significantly lower than those in the CD151(low) group, and correspondingly cumulative recurrence rates in HCCs with CD151(high) were significantly higher than those in the CD151(low) group. Both CD151 and c-Met were remarkably overexpressed in HCCs, compared with adjacent nontumorous and normal liver tissues. Pearson correlation analysis showed a slight correlation between CD151 and c-Met in HCCs. Importantly, the 5- and 7-year OS rates in CD151(high)/c-Met(high) patients were 50.5% and 37.8%, respectively, significantly lower than those of CD151(low)/c-Met(low) patients (63.9% and 54.6%, respectively). Five- and 7-year cumulative recurrence rates in CD151(high)/c-Met(high) patients were 53.3% and 71.9%, respectively, markedly higher than those of CD151(low)/c-Met(low) patients (39.0% and 52.5%, respectively). Multivariate analysis revealed that CD151 and combination of CD151/c-Met were independent prognostic indicators for OS and cumulative recurrence. CONCLUSION: CD151 is positively associated with invasiveness of HCC, and CD151 or combination of CD151/c-Met is a novel marker in predicting the prognosis of HCC and a potential therapeutic target.