HDAC inhibitor ITF2357 reduces resistance of mutant-KRAS non-small cell lung cancer to pemetrexed through a HDAC2/miR-130a-3p-dependent mechanism

BACKGROUND

Histone deacetylases (HDAC) contribute to oncogenic program, pointing to their inhibitors as a potential strategy against cancers. We, thus, studied the mechanism of HDAC inhibitor ITF2357 in resistance of mutant (mut)-KRAS non-small cell lung cancer (NSCLC) to pemetrexed (Pem).

METHODS

We first determined the expression of NSCLC tumorigenesis-related HDAC2 and Rad51 in NSCLC tissues and cells. Next, we illustrated the effect of ITF2357 on the Pem resistance in wild type-KARS NSCLC cell line H1299, mut-KARS NSCLC cell line A549 and Pem-resistant mut-KARS cell line A549R in vitro and in xenografts of nude mice in vivo.

RESULTS

Expression of HDAC2 and Rad51 was upregulated in NSCLC tissues and cells. Accordingly, it was revealed that ITF2357 downregulated HDAC2 expression to diminish the resistance of H1299, A549 and A549R cells to Pem. HDAC2 bound to miR-130a-3p to upregulate its target gene Rad51. The in vitro findings were reproduced in vivo, where ITF2357 inhibited the HDAC2/miR-130a-3p/Rad51 axis to reduce the resistance of mut-KRAS NSCLC to Pem.

CONCLUSION

Taken together, HDAC inhibitor ITF2357 restores miR-130a-3p expression by inhibiting HDAC2, thereby repressing Rad51 and ultimately diminishing resistance of mut-KRAS NSCLC to Pem. Our findings suggested HDAC inhibitor ITF2357 as a promising adjuvant strategy to enhance the sensitivity of mut-KRAS NSCLC to Pem.

Cation Lipid-Assisted PEG6-PLGA Polymer Nanoparticles Encapsulated Knocking Down Long ncRNAs Reverse Non-Coding RNA of Xist Through the Support Vector Machine Model to Regulate the Molecular Mechanisms of Gastric Cancer Cell Apoptosis

Gastric adenocarcinoma (GAC) is one kind of gastric cancer with a high incidence rate and mortality. It is essential to study the etiology of GAC and provide theoretical guidance for the prevention and treatment of GAC. Bioinformatics was used via differential expression analysis, weighted gene co-expression network analysis, gene set enrichment analysis, and a training support vector machine (SVM) model to construct a TSIX/mir-320a/Rad51 network as the research index of GAC disease. On the basis of CRISPR/Cas9 gene editing technology, the present study utilizes the Cation lipid-assisted PEG-6-PLGA polymer nanoparticle (CLAN) drug carrier system to prepare the target knock-out TSIX drug with CRISPR/CaS9 nucleic acid. Knocking down lncRNA TSIX restored the suppression role of miR-320a on Rad51 and inhibited the Rad51 expression. Simultaneously, this ceRNA network activated the ATF6 signaling pathway after endoplasmic reticulum stress to promote GAC cells' apoptosis and inhibit the disease. TSIX/miR-320a/Rad51 network may be a potential biological target of GAC disease and provides a new strategy for treating GAC disease.

(-)-Guaiol regulates RAD51 stability via autophagy to induce cell apoptosis in non-small cell lung cancer

(-)-Guaiol, generally known as an antibacterial compound, has been found in many medicinal plants. Its roles in tumor suppression are still under investigation. In the study, we mainly focused on exploring its applications in dealing with non-small cell lung cancer (NSCLC) and the underlying mechanisms. Here, we show that (-)-Guaiol significantly inhibits cell growth of NSCLC cells both in vitro and in vivo. Further high throughput analysis reveals that RAD51, a pivotal factor in homologous recombination repair, is a potential target for it. The following mechanism studies show that (-)-Guaiol is involved in cell autophagy to regulate the expression of RAD51, leading to double-strand breaks triggered cell apoptosis. Moreover, targeting RAD51, which is highly overexpressed in the lung adenocarcinoma tissues, can significantly increase the chemosensitivity of NSCLC cells to (-)-Guaiol both in vitro and in vivo. All in all, our studies provide an attractive insight in applying (-)-Guaiol into NSCLC treatments and further suggest that knockdown of oncogenic RAD51 will greatly enhance the chemosensitivity of patients with NSCLC.

RAD51 regulates CHK1 stability via autophagy to promote cell growth in esophageal squamous carcinoma cells

The serine/threonine protein kinase CHK1 has been reported to bind to the recombinase RAD51 and facilitates its assembly in DNA damage sites via phosphorylation. However, the role of RAD51 in regulating the expression of CHK1 has never been explored. Here, we show that RAD51 is highly upregulated in esophageal squamous tumor tissues and its DMC1 domain significantly promotes cell growth of esophageal cancer (EC) cells through CHK1. To gain the mechanistic insights, firstly, in the presence of 3-methyladenine (3MA), an autophagy inhibitor, we found that the reduction of CHK1 and the inhibition of cell growth in RAD51-deficient EC109 cells were strikingly restored. Subsequently, the autophagy-related experiments revealed that RAD51 negatively participated in autophagy. Moreover, results from in vitro clonogenic survival assays showed that RAD51 depletion greatly enabled EC cells to resist the autophagy inhibitors 3MA and hydroxychloroquine (HCQ) treatments. Above all, our studies firstly highlight a direct role of RAD51 in autophagy process and characterize its functional domain in cell growth regulation. Moreover, our data firstly shed insights into the possible application of autophagy inhibitors in treating RAD51 overexpressed EC patients.