Asparaginyl endopeptidase improves the resistance of microtubule-targeting drugs in gastric cancer through IQGAP1 modulating the EGFR/JNK/ERK signaling pathway

Abstract

PurposeIn recent years, understanding of the role of asparaginyl endopeptidase (AEP) in tumorigenesis has steadily increased. In this study, we investigated whether AEP expression correlates with sensitivity to chemotherapeutic drugs in gastric cancer and explored the mechanism.Patients and methodsAEP expression in the serum of patients’ peripheral blood was measured by enzyme-linked immunosorbent assay. Patient survival time was evaluated using univariate and multivariate analyses. Mass spectrometry and co-immunoprecipitation assays were utilized to discover proteins that interact with AEP. Gastric cancer cell lines were established, in which AEP was overexpressed or knocked out using lentiviral CRISPR. The proliferative abilities of these cell lines in response to chemotherapy agents were evaluated using the Cell Counting Kit-8 method. Gene expression changes in these lines were assessed by real-time polymerase chain reaction and Western blot.ResultsPatients with low expression of AEP were significantly more likely to have a good prognosis and experience complete response or partial response after treatment with docetaxel/S-1 regimen. Mass spectrum analysis showed that several proteins in the focal adhesion and mitogen-activated protein kinase signaling pathways interacted with AEP. IQGAP1 was confirmed to be one of the proteins interacting with AEP, and its protein level increased when AEP was knocked out. AEP knockout decreased resistance to microtubule inhibitors, including paclitaxel, docetaxel, and T-DM1. The expression levels of MDR1, p-EGFR, p-JNK, p-ERK, and p-Rac1/cdc42 were decreased in AEP knockout gastric cancer cell lines, and inhibitors of both JNK and ERK could block AEP-induced expression of MDR1.ConclusionAEP was not only a prognostic factor but also a predictive marker. AEP knockout could inhibit the activity of the EGFR/JNK/ERK signaling pathway and improve sensitivity to microtubule inhibitors through interacting with IQGAP1.

Cleavage of tropomodulin-3 by asparagine endopeptidase promotes cancer malignancy by actin remodeling and SND1/RhoA signaling

“…2 ). We found that plenty of cytoskeleton related proteins identified in our data, such as Vimentin, Cortactin, and IQ Motif Containing GTPase Activating Protein 1 (IQGAP1), also have been revealed in gastric cancer [ 43 ]. More, endogenic coimmunoprecipitation (co-IP) assays revealed that AEP interacted with Tmod3 in GBM cells (Fig.…”

Role of IQGAP1 in Carcinogenesis

“…Inhibiting IQGAP1 re-sensitized these cells to trastuzumab treatment in vitro, indicating a role of IQGAP1 in mediating trastuzumab resistance [155]. In patients treated with taxane-containing chemotherapy, levels of asparaginyl endopeptidase (AEP) increase and play an important role in acquired drug resistance [156]. AEP interacts with IQGAP1 and possibly contributes to drug resistance through IQGAP1-mediated RAS-MAPK signaling [156].…”

“…In patients treated with taxane-containing chemotherapy, levels of asparaginyl endopeptidase (AEP) increase and play an important role in acquired drug resistance [156]. AEP interacts with IQGAP1 and possibly contributes to drug resistance through IQGAP1-mediated RAS-MAPK signaling [156].…”

Identification of New Therapeutic Targets for Gastric Cancer With Bioinformatics

“…Gene Ontology Biological process (GO-BP) analysis showed that the differentially expressed genes were primarily involved in negative regulation of endopeptidase activity, cell adhesion, inflammatory response, and O-glycan processing (Figures 2C,D). These biological functions are closely related to the development and prognosis of GC (Duarte et al, 2016;Cui et al, 2017;Mukai et al, 2017;Geng et al, 2018).…”