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Chemoresistance is one of the leading causes of therapeutic failure in gastric cancer (GC) treatment. Recent studies have shown lncRNAs play pivotal roles in regulating GC chemoresistance. Nanocarriers delivery of small interfering RNAs (siRNAs) to silence cancer-related genes has become a novel approach to cancer treatment research. However, finding target genes and developing nanosystems capable of selectively delivering siRNAs for disease treatment remains a challenge. In this study, a novel lncRNA TMEM44-AS1 that is related to 5-FU resistance is identified. TMEM44-AS1 has the ability to bind to and sponge miR-2355-5p, resulting in the upregulated PPP1R13L expression and P53 pathway inhibition. Next, a new nanocarrier called chitosan-gelatin-EGCG (CGE) is developed, which has a higher gene silencing efficiency than lipo2000, to aid in the delivery of a si-TMEM44-AS1 can efficiently silence TMEM44-AS1 expression to synergistically reverse 5-FU resistance in GC, leading to a markedly enhanced 5-FU therapeutic effect in a xenograft mouse model of GC. These findings indicate that TMEM44-AS1 may estimate 5-FU therapy outcome among GC cases, and that systemic si-TMEM44-AS1 delivery combined with 5-FU therapy is significant in the treatment of patients with recurrent GC., (© 2022 The Authors. Advanced Science published by Wiley-VCH GmbH.)

Aberrant expression of circular RNAs (circRNAs) has been reported to play an important biological regulatory role in gastric cancer (GC). For the purpose of silencing cancer‐related genes, a new approach for cancer treatment using nanocarriers to deliver siRNA has been proposed. In this study, abundantly expressed circMAP2K2 (hsa_circRNA_102415) is identified in GC cells. CircMAP2K2 regulates the PCBP1/GPX1 axis through proteasome‐mediated degradation, which further mediates the activation of the AKT/GSK3β/epithelial‐to‐mesenchymal transition (EMT) signaling pathway and enhances the proliferation and metastatic ability of GC cells. To establish novel GC treatment, epigallocatechin‐3‐gallate‐lysozyme (EGCG‐LYS) fibrils are synthesized, and in vitro experiments demonstrate that EGCG‐LYS has a higher siRNA delivery efficiency than Lipofectamine 2000 (lipo2000), which effectively silences the expression of circMAP2K2. Further studies show that EGCG‐LYS carrying siRNA can successfully achieve lysosome escape, which allows it to be located in the cytoplasm to achieve post‐transcriptional gene silencing. In addition, EGCG‐LYS carrying si‐circMAP2K2 has good circulating stability, excellent biosafety and antitumor ability in vivo. The EGCG‐LYS fibrils delivery system provides a new tool and approach for the treatment of GC. [ABSTRACT FROM AUTHOR]