Long non-coding RNA NEAT1 decreases the chemosensitivity of gastric cancer cells via regulating P-glycoprotein expression

Long noncoding RNAs as potential targets for overcoming chemoresistance in upper gastrointestinal cancers

In the last decade, researchers have paid much attention to the role of noncoding RNA molecules in human diseases. Among the most important of these molecules are LncRNAs, which are RNA molecules with a length of more than 200 nucleotides. LncRNAs can regulate gene expression through various mechanisms, such as binding to DNA sequences and interacting with miRNAs. Studies have shown that LncRNAs may be valuable therapeutic targets in treating various cancers, including upper-gastrointestinal cancers. Upper gastrointestinal cancers, mainly referring to esophageal and gastric cancers, are among the deadliest gastrointestinal cancers. Despite notable advances, traditional chemotherapy remains a common strategy for treating these cancers. However, chemoresistance poses a significant obstacle to the effective treatment of upper gastrointestinal cancers, resulting in a low survival rate. Chemoresistance arises from various events, such as the enhancement of efflux and detoxification of chemotherapy agents, reduction of drug uptake, alteration of drug targeting, reduction of prodrug activation, strengthening of EMT and stemness, and the attenuation of apoptosis in cancerous cells. Tumor microenvironment also plays an important role in chemoresistance. Interestingly, a series of studies have revealed that LncRNAs can influence important mechanisms associated with some of the aforementioned events and may serve as promising targets for mitigating chemoresistance in upper gastrointestinal cancers. In this review paper, following a concise overview of chemoresistance mechanisms in upper gastrointestinal cancers, we will review the most intriguing findings of these investigations in detail.

Non-coding RNAs underlying chemoresistance in gastric cancer

BACKGROUND

Gastric cancer (GC) is a major health issue in the Western world. Current clinical imperatives for this disease include the identification of more effective biomarkers to detect GC at early stages and enhance the prevention and treatment of metastatic and chemoresistant GC. The advent of non-coding RNAs (ncRNAs), particularly microRNAs (miRNAs) and long-non coding RNAs (lncRNAs), has led to a better understanding of the mechanisms by which GC cells acquire features of therapy resistance. ncRNAs play critical roles in normal physiology, but their dysregulation has been detected in a variety of cancers, including GC. A subset of ncRNAs is GC-specific, implying their potential application as biomarkers and/or therapeutic targets. Hence, evaluating the specific functions of ncRNAs will help to expand novel treatment options for GC.

CONCLUSIONS

In this review, we summarize some of the well-known ncRNAs that play a role in the development and progression of GC. We also review the application of such ncRNAs in clinical diagnostics and trials as potential biomarkers. Obviously, a deeper understanding of the biology and function of ncRNAs underlying chemoresistance can broaden horizons toward the development of personalized therapy against GC.

MiR-876-3p regulates cisplatin resistance and stem cell-like properties of gastric cancer cells by targeting TMED3

BACKGROUND AND AIM

Gastric cancer (GC), a prevalent tumor, exerts a major economic burden, and we aimed to explore miR-876-3p's effects on GC and related mechanisms.

METHODS

Cell viability was analyzed via CCK-8 and colony formation assay. Stem cell-like properties were examined via spheroid colony formation assay. mRNA abundance of key genes was analyzed via quantitative polymerase chain reaction. Protein level of TMED3 and stem cell markers was examined by western blot. TargetScan, luciferase, and biotin-miRNA pulldown assay were used to identify miR-876-3p's target.

RESULTS

MiR-876-3p was downregulated in GC, and its mRNA level had negative relationship with cisplatin resistance of GC. Moreover, decreased miR-876-3p expression level suggested poor prognosis of GC patients. MiR-876-3p inhibited drug resistance of cisplatin-resistant cell line SGC-7901/DDP and MKN-45/DDP, as shown by decreased cell viability, IC₅₀ , and colony formation ability. MiR-876-3p inhibited stem cell-like features and downregulated the expressions of Sox-2, Oct-4, CD133, and CD44 in GC cells. Luciferase and biotin-miRNA pulldown assay confirmed that TMED3 was miR-876-3p's direct target. TMED3 siRNA inhibited miR-876-3p's effects on cisplatin resistance and stem cell-like features of SGC-7901/DDP cells.

CONCLUSION

MiR-876-3p enhanced cisplatin sensitivity and restricted stem cell-like features of GC through targeting TMED3.