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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]

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. [ABSTRACT FROM AUTHOR]

Background: There is increasing evidence that circular RNAs (circRNAs) have significant regulatory roles in cancer development and progression; however, the expression patterns and biological functions of circRNAs in renal cell carcinoma (RCC) remain largely elusive. Method: Bioinformatics methods were applied to screen for circRNAs differentially expressed in RCC. Analysis of online circRNAs microarray datasets and our own patient cohort indicated that circSDHC (hsa_circ_0015004) had a potential oncogenic role in RCC. Subsequently, circSDHC expression was measured in RCC tissues and cell lines by qPCR assay, and the prognostic value of circSDHC evaluated. Further, a series of functional in vitro and in vivo experiments were conducted to assess the effects of circSDHC on RCC proliferation and metastasis. RNA pull-down assay, luciferase reporter and fluorescent in situ hybridization assays were used to confirm the interactions between circSDHC, miR-127-3p and its target genes. Results: Clinically, high circSDHC expression was correlated with advanced TNM stage and poor survival in patients with RCC. Further, circSDHC promoted tumor cell proliferation and invasion, both in vivo and in vitro. Analysis of the mechanism underlying the effects of circSDHC in RCC demonstrated that it binds competitively to miR-127-3p and prevents its suppression of a downstream gene, CDKN3, and the E2F1 pathway, thereby leading to RCC malignant progression. Furthermore, knockdown of circSDHC caused decreased CDKN3 expression and E2F1 pathway inhibition, which could be rescued by treatment with an miR-127-3p inhibitor. Conclusion: Our data indicates, for the first time, an essential role for the circSDHC/miR-127-3p/CDKN3/E2F1 axis in RCC progression. Thus, circSDHC has potential to be a new therapeutic target in patients with RCC. [ABSTRACT FROM AUTHOR]