Overexpression of asparaginyl endopeptidase is significant for esophageal carcinoma metastasis and predicts poor patient prognosis

Asparaginyl endopeptidase contributes to cetuximab resistance via MEK/ERK signaling in RAS wide-type metastatic colorectal cancer

BACKGROUND

Cetuximab, a monoclonal antibody targeting epidermal growth factor receptor (EGFR), is effective for RAS wild-type metastatic colorectal cancer (mCRC) patients. However, cetuximab resistance often occur and the mechanism has not been fully elucidated. The purpose of this study was to investigate the role of asparaginyl endopeptidase (AEP) in cetuximab resistance.

METHODS

Differentially expressed genes between cetuximab responders and non-responders were identified by analyzing the gene expression profile GSE5851, retrieved from Gene Expression Omnibus (GEO). The potential genes were further validated in cetuximab-resistant CRC cell lines. The expression of AEP in the peripheral blood and tumor tissues of mCRC patients in our hospital were detected by enzyme-linked immunosorbent assay (ELISA) and immunohistochemistry, respectively. The survival analysis was carried out by Kaplan-Meier method. The function and associated pathways of AEP were further investigated by lentivirus transfection, CCK8 assay, colony formation assay, real-time polymerase chain reaction (qPCR) and western blot.

RESULTS

Through bioinformatics analysis, we found that the expression of AEP gene was related to progress free survival (PFS) of mCRC patients treated with cetuximab alone (P = 0.00133). The expression of AEP was significantly higher in the cetuximab-resistant CRC cell lines, as well as in mCRC patients with shorter PFS treated with cetuximab-containing therapy. Furthermore, AEP could decrease the sensitivity of CRC cells to cetuximab in vitro. And the phosphorylation level of MEK and ERK1/2 was increased in AEP overexpression cells. The downregulation of AEP using specific inhibitors could partially restore the sensitivity of CRC cells to cetuximab.

CONCLUSION

The higher expression of AEP could contribute to the shorter PFS of cetuximab treatment in mCRC. The reason might be that AEP could promote the phosphorylation of MEK/ERK protein in the downstream signal pathway of EGFR.

The Mechanism of Asparagine Endopeptidase in the Progression of Malignant Tumors: A Review

Asparagine endopeptidase (AEP), also called legumain, is currently the only known cysteine protease that specifically cleaves peptide bonds in asparaginyl residue in the mammalian genome. Since 2003, AEP has been reported to be widely expressed in a variety of carcinomas and is considered a potential therapeutic target. In the following years, researchers intensively investigated the substrates of AEP and the mechanism of AEP in partial tumors. With the identification of substrate proteins such as P53, integrin αvβ3, MMP-2, and MMP-9, the biochemical mechanism of AEP in carcinomas is also more precise. This review will clarify the probable mechanisms of AEP in the progression of breast carcinoma, glioblastoma, gastric carcinoma, and epithelial ovarian carcinoma. This review will also discuss the feasibility of targeted therapy with AEP inhibitor (AEPI) in these carcinomas.

Extracellular Vesicles (EVs) and Pancreatic Cancer: From the Role of EVs to the Interference with EV-Mediated Reciprocal Communication

Pancreatic cancer is malignant and the seventh leading cause of cancer-related deaths worldwide. However, chemotherapy and radiotherapy are—at most—moderately effective, indicating the need for new and different kinds of therapies to manage this disease. It has been proposed that the biologic properties of pancreatic cancer cells are finely tuned by the dynamic microenvironment, which includes extracellular matrix, cancer-associated cells, and diverse immune cells. Accumulating evidence has demonstrated that extracellular vesicles (EVs) play an essential role in communication between heterogeneous subpopulations of cells by transmitting multiplex biomolecules. EV-mediated cell–cell communication ultimately contributes to several aspects of pancreatic cancer, such as growth, angiogenesis, metastasis and therapeutic resistance. In this review, we discuss the role of extracellular vesicles and their cargo molecules in pancreatic cancer. We also present the feasibility of the inhibition of extracellular biosynthesis and their itinerary (release and uptake) for a new attractive therapeutic strategy against pancreatic cancer.

Combination treatment with artemisinin and oxaliplatin inhibits tumorigenesis in esophageal cancer EC109 cell through Wnt/β-catenin signaling pathway

Background

Esophageal cancer (EC) is a prevalent malignant cancer worldwide. Interestingly, the antimalaria compound artemisinin (ART) is also reported to have anticancer potential, although its underlying mechanism in EC is unclear. In this study, we explored the anticancer role of ART in EC109 and further explored the combination of ART and oxaliplatin (OXA) for their synergetic anticancer functions.

Methods

Human EC cell line EC109 was used. After ART or oxaliplatin (OXA) treatment, cell proliferation, migration, and invasion were measured by MTT, transwell, and scratch wound assays, respectively. Flow cytometry was performed to examine the cell cycle and apoptosis. The mRNA and protein levels were determined using qRT‐PCR and western blotting.

Results

The migration and invasion abilities of EC109 were suppressed by ART. This was due to the inhibitory effect of ART on the Wnt/β‐catenin signaling pathway. The levels of β‐catenin, c‐myc, and survivin were also downregulated by ART. ART inhibits the proliferation of EC109 cells by arresting the cells in the G1‐phase of cell cycle. By using LiCl, an activator of the Wnt/β‐catenin pathway, we further verified that the inhibition of the Wnt/β‐catenin pathway was indeed due to ART. Remarkably, ART enhanced the anticancer effects of OXA in EC109 cells. OXA combined with ART was found to be more efficient in decreasing tumor growth compared to the individual drugs.

Conclusions

ART could suppress tumor progression by inhibiting Wnt/β‐catenin signaling pathway, and it may also enhance the antitumor effect of OXA in EC. Thus, ART could be a novel anticancer drug for EC treatment.

Key points

Significant findings of the study

ART could be a novel anticancer drug for esophageal cancer (EC) treatment.

What this study adds

Combination treatment with artemisinin and oxaliplatin inhibits tumorigenesis in esophageal cancer EC109 cells through the Wnt/β‐catenin signaling pathway.

Silencing lncRNAs PVT1 Upregulates miR-145 and Confers Inhibitory Effects on Viability, Invasion, and Migration in EC

Long non-coding RNA (lncRNA) plasmacytoma variant translocation 1 (PVT1) is correlated to various malignant tumors. Consequently, we explored effects of lncRNA PVT1 on esophageal carcinoma (EC) targeting microRNA-145 (miR-145). EC tissues, adjacent normal tissues, and EC-related cell lines were collected and cultured. Expression of lncRNA PVT1, miR-145, fascin-1 (FSCN1), and related genes with intervening expression of PVT1 and miR-145 was determined. Bioinformatic website, dual-luciferase reporter assay, and RNA immunoprecipitation (RIP) were carried to verify target relationship among lncRNA PVT1, FSCN1, and miR-145. Scratch test, Transwell assay, 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay, and flow cytometry were performed for detection of migration, invasion, viability, and apoptosis of transfected cells, respectively. Finally, tumor formation in nude mice was measured. After database analysis, lncRNA PVT1, miR-145, and FSCN1 were selected for study. lncRNA PVT1 and FSCN1 can bind to miR-145. After overexpressing miR-145 or inhibiting lncRNA PVT1, EC cell viability, migration, and invasion were inhibited, while volume and weight of tumor formation in nude mice decreased. Expression of lncRNA PVT1, FSCN1, Bcl-2, CD147, VEGFR2, and MTA1 decreased and expression of miR-145 and Bax increased. Silencing lncRNA PVT1 can upregulate miR-145, which is a tumor suppressor in EC via knockdown of FSCN1. Thus, we might provide a potential theoretical basis for EC treatment.

Down-regulation of long noncoding RNA PVT1 inhibits esophageal carcinoma cell migration and invasion and promotes cell apoptosis via microRNA-145-mediated inhibition of FSCN1

Accumulating evidence has established that long noncoding RNA (lncRNA) plasmacytoma variant translocation 1 (PVT1) is a tumor regulator in many cancers. Here, we aimed to investigate the possible function of lncRNA PVT1 in esophageal carcinoma (EC) via targeting of microRNA-145 (miR-145). Initially, microarray-based gene expression profiling of EC was employed to identify differentially expressed genes. Moreover, the expression of lncRNA PVT1 was examined and the cell line presenting with the highest level of lncRNA PVT1 expression was selected for subsequent experiments. We then proceeded to examine interaction among lncRNA PVT1, FSCN1, and miR-145. The effect of lncRNA PVT1 on viability, migration, invasion, apoptosis, and tumorigenesis of transfected cells was examined with gain-of-function and loss-of-function experiments. We observed that lncRNA PVT1 was robustly induced in EC. lncRNA PVT1 could bind to miR-145 and regulate its expression, and FSCN1 is a target gene of miR-145. Overexpression of miR-145 or silencing of lncRNA PVT1 was revealed to suppress cell viability, migration, and invasion abilities, while also stimulating cell apoptosis. Furthermore, our in vivo results showed that overexpression of miR-145 or silencing of lncRNA PVT1 resulted in decreased tumor growth in nude mice. In conclusion, our research reveals that down-regulation of lncRNA PVT1 could potentially promote expression of miR-145 to repress cell migration and invasion, and promote cell apoptosis through the inhibition of FSCN1. This highlights the potential of lncRNA PVT1 as a therapeutic target for EC treatment.