Inhibition of OTUB2 suppresses colorectal cancer cell growth by regulating ß-Catenin signaling.

In the effort to identify deubiquitinating enzymes required for the growth of colorectal cancer (CRC) cells, we found that OTUB2 knockdown markedly inhibited the viability of these cancer cells in culture and in xenografted mice. It was also found that the level of OTUB2 was elevated in primary CRCs, and its high expression was a poor prognostic indicator for the patients. Interestingly, immunoprecipitation and LC-MS/MS analyses suggested that ß-Catenin was an OTUB2-interacting protein, and there was a positive correlation between OTUB2 and ß-Catenin expression in both CRC tissues and cell lines. We then performed reciprocal co-immunoprecipitations and demonstrated that OTUB2 and ß-Catenin bound to each other. Enforced expression of OTUB2 decreased ubiquitination of ß-Catenin and increased the half-life and intracellular level of ß-Catenin, whereas the catalytic inactive OTUB2 did not. OTUB2 also enhanced ß-Catenin-mediated transactivation as measured by TCF-luciferase and expression of endogenous CCND1 and MYC in CRC cells. These results indicated that OTUB2 was a potential target for therapeutic intervention for CRC.

Learning curve for endoscopic resection of gastric gastrointestinal stromal tumors: a single-center experience.

BACKGROUND: endoscopic resection (ER) is widely used in the treatment of gastric gastrointestinal stromal tumors (gGISTs). However, no studies have previously described the learning curve (LC) for ER of gGISTs. This study aimed to evaluate the LC based on multifarious operative outcomes. METHODS: one hundred consecutive patients who underwent ER of gGISTs by a single endoscopist from January 2017 to December 2022 were included. Patients were analyzed in groups of ten to minimize demographic differences, and operative time (OT), conversion rate, intraoperative and postoperative complication were assessed to evaluate the LC. Meanwhile, for the OT, the LC was further analyzed using the cumulative sum (CUSUM) method and patients were organized chronologically in three phases. RESULT: there was a statistically significant decrease in OT, conversion to laparoscopic surgery, and postoperative complication after 30 cases (median 80.0 min vs 56.0 min, p < 0.001; 10.0 % vs 0 %, p = 0.025; 33.3 % vs 10.0 %, p = 0.004), rate of intraoperative complications after 20 cases (15.0 % vs 1.3 %, p = 0.025). CUSUM chart demonstrated that OT increased dramatically before around 30 cases (phase 1) and decreased after 60 cases (phase 3), with a plateau phase in the middle 30 cases (phase 2). Among the three phases, the R0 resection and conversion rate were not significantly different. However, OT, intraoperative and postoperative complications were gradually decreased (p < 0.05). CONCLUSIONS: the LC of ER of gGISTs is approximately 60 cases. However, about 30 cases were sufficient to acquire skills to reduce complications and conversion rate during the ER procedure.

Learning curve for endoscopic resection of gastric gastrointestinal stromal tumors: a single-center experience

Background: endoscopic resection (ER) is widely used in the treatment of gastric gastrointestinal stromal tumors (gGISTs). However, no studies have previously described the learning curve (LC) for ER of gGISTs. This study aimed to evaluate the LC based on multifarious operative outcomes. Methods: one hundred consecutive patients who underwent ER of gGISTs by a single endoscopist from January 2017 to December 2022 were included. Patients were analyzed in groups of ten to minimize demographic differences, and operative time (OT), conversion rate, intraoperative and postoperative complication were assessed to evaluate the LC. Meanwhile, for the OT, the LC was further analyzed using the cumulative sum (CUSUM) method and patients were organized chronologically in three phases. Result: there was a statistically significant decrease in OT, conversion to laparoscopic surgery, and postoperative complication after 30 cases (median 80.0 min vs 56.0 min, p < 0.001; 10.0 % vs 0 %, p = 0.025; 33.3 % vs 10.0 %, p = 0.004), rate of intraoperative complications after 20 cases (15.0 % vs 1.3 %, p = 0.025). CUSUM chart demonstrated that OT increased dramatically before around 30 cases (phase 1) and decreased after 60 cases (phase 3), with a plateau phase in the middle 30 cases (phase 2). Among the three phases, the R0 resection and conversion rate were not significantly different. However, OT, intraoperative and postoperative complications were gradually decreased (p < 0.05). Conclusions: the LC of ER of gGISTs is approximately 60 cases. However, about 30 cases were sufficient to acquire skills to reduce complications and conversion rate during the ER procedure (AU)

The Deubiquitinating Enzyme USP4 Functions as an Oncoprotein in Gastric Cancer and Mediates NF-κB Signaling by Regulating PRL-3 Expression.

BACKGROUND: It has been reported that ubiquitin specific peptidase 4 (USP4) was functional in several tumors, but its function and mechanism in gastric cancer were still unknown. METHODS: Bioinformatic tools were used to predict the prognosis of gastric cancer patients and the expression levels of USP4 in gastric cancer. Quantitative real-time polymerase chain reaction (qRT-PCR) and immunoblotting were carried out to detect the messenger RNA (mRNA) and protein levels. Cell viability of gastric cancer was evaluated by Cell Counting Kit-8 (CCK-8) assay. Cell line-derived xenograft models were established to evaluate the tumor growth of gastric cancer. Luciferase assay and immunoblotting were used to determine the activation of nuclear factor kappa B (NF-κB) signaling. RESULTS: The public database Kaplan-Meier Plotter showed that gastric cancer patients with high USP4 expression had a shorter overall survival or post-progression survival than the patients with decreased USP4. Further studies indicated that USP4 was elevated in gastric cancer tumor tissues. In contrast, knockdown of USP4 markedly inhibited gastric cancer cell growth, and suppressed the tumor growth of gastric cancer. Further studies revealed that USP4 knockdown significantly suppressed NF-κB-driven luciferase activity, and inhibited the phosphorylation of NF-κB p65 in gastric cancer cells. Additionally, qRT-PCR analysis showed that USP4 knockdown significantly downregulated the expressions of cyclin D2 (CCND2) and B cell leukemia/lymphoma 2 (BCL2). We also found that USP4 knockdown decreased the expressions of phosphatase of regenerating liver-3 (PRL-3), in contrast, overexpression of PRL-3 attenuated the inhibitory effects of USP4 knockdown on NF-κB signaling and cell viability in gastric cancer cells. Finally, PR-619, which has been proven to inhibit the activities of USP4 and other deubiquitinases, could inhibit cell viability and NF-κB signaling in gastric cancer cells. CONCLUSIONS: This study indicated that elevated USP4 predicted a poor index for gastric cancer patients, and mediated gastric cancer cell growth by regulating PRL-3/NF-κB signaling, which suggested USP4 may be a novel therapeutic target for gastric cancer.

miR-502-5p affects gastric cancer progression by targeting PD-L1.

BACKGROUND: Studies have shown that miR-502-5p functions as a tumor suppressor and is associated with tumor growth and metastasis. This study intends to uncover the potential mechanism of miR-502-5p functioning as a tumor suppressor in gastric cancer. METHODS: Expression levels of miR-502-5p and PD-L1 were measured by using qRT-PCR. Cell proliferation abilities were examined by EDU incorporation assay. Cell migration, invasion and cell cycle analysis of cells were determined by transwell assay, transwell-matrigel assay and flow cytometry, respectively. The relationship between miR-502-5p expression and the overall survival of xenograft tumor mice was statistically analyzed. Bioinformatics analysis and luciferase reporter assays were applied to analyze the relationship between miR-502-5p and CD40, STAT3 or PD-L1. Expressions of CD40, STAT3 and PD-L1 at protein level were detected by western blot. RESULTS: The results showed that miR-502-5p was significantly downregulated in gastric cancer tumor tissues compared with adjacent normal tissues. Overexpression of miR-502-5p significantly attenuated the proliferation, migration/invasion and induced the G1 phase arrest of gastric cancer cells. Consistently, miR-502-5p suppressed tumor growth and metastasis in vivo. Mechanically, we demonstrated that miR-502-5p had inhibited the malignant behaviour of gastric cancer by down-regulating PD-L1 expression at transcriptional level and post-transcriptional levels. CONCLUSIONS: These findings suggest that miR-502-5p acts as a tumor suppressor in gastric cancer (GC). MiR-502-5p/PD-L1 may be a novel therapeutic target in GC treatment.

MiR-152-5p as a microRNA passenger strand special functions in human gastric cancer cells.

Gastric cancer (GC) is one of the most common malignancies with high mortality rate. MiR-152 may exert the function of tumor suppressor by regulating its target gene, including PIK3CA. Nevertheless, all of the described functions are referred explicitly to miR-152-3p, while miR-152-5p as a passenger strand is poorly realized and entirely ignored. We previously selected miR-152-5p as a candidate using cell migration inhibition screening for GC cells and predicted that miR-152-5p might also target PIK3CA. In this study, we found an abnormal proportion of miR-152-3p / miR-152-5p in GC (gastric cancer) tissues and cells and demonstrated that miR-152-5p had poorer stability in GC cells, revealing the possibility that miR-152-5p is abnormally "suppressed" in gastric cancer. We also investigated and confirmed the role of miR-152-5p in GC by a series of experiments, and found that miR-152-5p modulated cell viability, migration, invasion, and cell-cycle progression of human GC cells, and also inhibited tumor growth and metastasis in vivo partially by targeting PIK3CA. More interestingly, it was proved that miR-152-3p and miR-152-5p had synergistic effects on the inhibition of PIK3CA in GC cells. The results of this study suggest that miR-152-5p may act as a tumor suppressor in SGC-7901 gastric cancer cells via targeting PIK3CA. Further, the study provides a novel insight into the roles of miRNA* during carcinogenesis.

High-Throughput Screening Identifies miR-451 as a Pleiotropic Modulator That Suppresses Gastric Cancer Metastasis.

MicroRNAs (miRNAs) are globally dysregulated in human carcinomas. However, the specific miRNAs that mediate gastric cancer metastasis have not been identified. We identified 100 miRNAs that are dysregulated in gastric cancer and used a self-assembled cell microarray method to systematically evaluate their capacity to regulate cell migration. MiR-451, which is down-regulated in human gastric cancer samples, potently modulated multiple metastatic phenotypes including cell migration, invasion, proliferation, and epithelial-mesenchymal transition. These effects were achieved via down-regulation of the miR-451 target gene, ERK2. These findings provide new insight into the physiological effects of and potential therapeutic uses for miRNAs in gastric cancer.