Prognostic Value of the Immunohistochemical Expression of RAD51 and BRCA2 in Gastric Adenocarcinoma

XRCC2 driven homologous recombination subtypes and therapeutic targeting in lung adenocarcinoma metastasis

Lung adenocarcinoma (LUAD) is a leading cause of cancer mortality, with many patients facing poor prognosis, particularly those with metastatic or drug-resistant tumors. Homologous recombination genes (HRGs) are crucial in tumor progression and therapy resistance, but their clinical significance in LUAD is not well understood. In this study, we systematically characterize key HRGs in LUAD patients, identifying two distinct HR subtypes associated with different outcomes and biological functions. We establish a 5-gene scoring system (XRCC2, RAD51, BRCA1, FANCA, and CHEK1) that reliably predicts patient outcomes and immunotherapy responses in LUAD. Bioinformatics analysis and clinical validation highlight XRCC2 as a crucial biomarker in LUAD. Functional investigations through in vivo and in vitro experiments reveal the role of XRCC2 in promoting lung cancer migration and invasion. Mechanistically, XRCC2 stabilizes vimentin (VIM) protein expression through deubiquitylation. We predict c-MYC as a potential regulator of XRCC2 and demonstrate that inhibiting c-MYC with compound 10058-F4 reduces XRCC2 and VIM expression. Preclinical studies show the synergistic inhibition of metastasis in vivo when combining 10058-F4 with doxorubicin (Dox). Our findings present a potential personalized predictive tool for LUAD prognosis, identifying XRCC2 as a critical biomarker. The c-Myc-XRCC2-VIM axis emerges as a promising therapeutic target for overcoming lung metastasis. This study provides valuable insights into LUAD, proposing a prognostic tool for further clinical validation and unveiling a potential therapeutic strategy for combating lung metastasis by targeting c-Myc-XRCC2-VIM.

mRNA Expression and Methylation of the RAD51, ATM, ATR, BRCA1, and BRCA2 Genes in Gastric Adenocarcinoma

Background

Immunohistochemical prognostic significance of the homologous recombination-related proteins RAD51, ATM, BRCA1, and BRCA2 is known in gastric adenocarcinoma, one of the deadliest cancers.

Objective and design

This retrospective cohort study aimed to evaluate mRNA expression and promoter methylation of some homologous recombination-related genes in this neoplasm.

Methods

We evaluated mRNA expression and methylation of RAD51, ATM, ATR, BRCA1, and BRCA2 in tumor and non-tumor frozen samples from gastrectomy specimens by RT-qPCR and MS-HRM, correlating our results with previous immunohistochemistry data and prognostic features.

Results

RAD51, ATR, BRCA1, BRCA2, and ATM mRNA expression was detected in 93.75% (45/48), 93.75% (45/48), 91.67% (44/48), 83.33% (40/48), and 89.58% (43/48) of the tumors; partial or complete methylation, in 94.87% (37/39), 0 (0/42), 97.56% (40/41), 100% (41/41), and 0 (0/40), respectively. Most gene pairs showed significant weak to moderate positive correlations of tumoral mRNA expression with each other: RAD51 with ATR (P = .027), BRCA1 (P < .001), and BRCA2 (P < .001); ATR with BRCA1 (P = .007), and ATM (P = .001); BRCA1 with BRCA2 (P = 0.001). BRCA1 mRNA was reduced in tumors compared with non-neoplastic mucosa (0.345 vs 1.272, P = .015) and, excluding neoadjuvant therapy cases, in T3 to T4 tumors compared with T2 (0.414 vs 0.954, P = .035). Greater tumoral RAD51 mRNA levels correlated with perineural invasion (1.822 vs 0.725, P = .010) and death (1.664 vs 0.929, P = .036), but not with survival time. There was an inverse association between nuclear immunohistochemical positivity for ATR and its mRNA levels (0.487 vs 0.907, P = .032), and no significant correlation for the other markers.

Conclusions

Our results suggest RAD51, BRCA1, and BRCA2 methylation as a frequent epigenetic mechanism in gastric cancer, support the hypothesis that reduced BRCA1 expression participates in disease progression, and show an association between RAD51 mRNA and perineural invasion and mortality that may be considered unexpected, considering the former immunohistochemical studies. The lack of correlation between immunohistochemistry and mRNA, and even the inverse association, for ATR, can be seen as indicative of action of post-transcriptional or post-translational regulatory mechanisms, to be better investigated.

A nine-gene signature as prognostic biomarker in gastric cancer by bioinformatics analysis

PURPOSE

The prognosis of advanced gastric cancer (GC) remains poor. It is urgent and necessary to find suitable prognostic markers. miR-619-5p is highly expressed in GC. However, the value of miR-619-5p and its target genes as prognostic biomarkers of GC is unclear.

METHODS

RT-PCR was performed to verify the expression of miR-619-5p in GC cell lines and their exosomes. Western blotting and transmission electron microscope were used to identify exosomes. The target genes of miR-619-5p were predicted by RNA22 and TargetScan. The differentially expressed genes (DEGs) and prognosis-related genes (PRGs) were obtained using The Cancer Genome Atlas (TCGA) database. The DAVID database was used to analyse pathway enrichment and functional annotation of common target genes. The STRING database and Cytoscape software were used to screen key genes and visualize their functional modules. The survival analysis was conducted using TCGA and Kaplan-Meier Plotter (KMP) databases. Finally, a prognostic model was constructed on the foundation of the key genes to assess the reliability of the screening process.

RESULTS

The expression of miR-619-5p in GC cells and their exosomes was proved to be significantly higher than that in normal cell lines. There are 129 common target genes involved in 3 pathways and 28 functional annotations. Finally, nine key target genes of GC (BRCA1, RAD51, KIF11, ERCC6L, BRIP1, TIMELESS, CDC25A, CLSPN and NCAPG2) were identified, and a prognostic model was successfully constructed with a good predictive ability.

CONCLUSIONS

The model of 9-gene signature could effectively predict the prognosis of GC, and have great potential to be novel prognostic factors and therapeutic targets for patients with GC.

Advancements and Obstacles of PARP Inhibitors in Gastric Cancer

Gastric cancer (GC) is a common and aggressive cancer of the digestive system, exhibiting high aggressiveness and significant heterogeneity. Despite advancements in improving survival rates over the past few decades, GC continues to carry a worrisome prognosis and notable mortality. As a result, there is an urgent need for novel therapeutic approaches to address GC. Recent targeted sequencing studies have revealed frequent mutations in DNA damage repair (DDR) pathway genes in many GC patients. These mutations lead to an increased reliance on poly (adenosine diphosphate-ribose) polymerase (PARP) for DNA repair, making PARP inhibitors (PARPi) a promising treatment option for GC. This article presents a comprehensive overview of the rationale and development of PARPi, highlighting its progress and challenges in both preclinical and clinical research for treating GC.

The DNA damage repair-related lncRNAs signature predicts the prognosis and immunotherapy response in gastric cancer

Background

Gastric cancer (GC) is one of the most prevalent cancers, and it has unsatisfactory overall treatment outcomes. DNA damage repair (DDR) is a complicated process for signal transduction that causes cancer. lncRNAs can influence the formation and incidence of cancers by influencing DDR-related mRNAs/miRNAs. A DDR-related lncRNA prognostic model is urgently needed to improve treatment strategies.

Methods

The data of GC samples were obtained from The Cancer Genome Atlas (TCGA) and Gene Expression Omnibus (GEO) datasets. A total of 588 mRNAs involved in DDR were selected from MSigDB, 62 differentially expressed mRNAs from TCGA-STAD were obtained, and 137 lncRNAs were correlated with these mRNAs. Univariate Cox regression and least absolute shrinkage and selection operator (LASSO) regression analyses were used to develop a DDR-related lncRNA prognostic model. Based on the risk model, the differentially expressed gene signature A/B in the low-risk and high-risk groups of TCGA-STAD was identified for further validation.

Results

The prognosis model of 5 genes (AC145285.6, MAGI2-AS3, AL590705.3, AC007405.3, and LINC00106) was constructed and classified into two risk groups. We found that GC patients with a low-risk score had a better OS than those with a high-risk score. We found that the high-risk group tended to have higher TME scores. We also found that patients in the high-risk group had a higher proportion of resting CD4 T cells, monocytes, M2 macrophages, resting dendritic cells, and resting mast cells, whereas the low-risk subgroup had a greater abundance of activated CD4 T cells, follicular helper T cells, M0 macrophages, and M1 macrophages. We observed significant differences in the T-cell exclusion score, T-cell dysfunction, MSI, and TMB between the two risk groups. In addition, we found that patients treated with immunotherapy in the low-RS score group had a longer survival and a better prognosis than those in the high-RS score group.

Conclusion

The prognostic model has a significant role in the TME, clinicopathological characteristics, prognosis, MSI, and drug sensitivity. We also discovered that patients treated with immunotherapy in the low-RS score group had a better prognosis. This work provides a foundation for improving the prognosis and response to immunotherapy among patients with GC.

Gastric Cancer Risk and Pathogenesis in BRCA1 and BRCA2 Carriers

Carriers of a pathogenic germline variant (PV) in BRCA1 or BRCA2 are at increased risk for a number of malignancies, including breast, ovarian, pancreatic, and prostate cancer. In this review, we discuss emerging evidence that BRCA2 PV carriers, and likely also BRCA1 PV carriers, are also at increased risk for gastric cancer (GC), highlighting that GC may be part of the BRCA1/2 cancer risk spectrum. While the pathogenesis of GC among BRCA1/2 PV carriers remains unclear, increasing evidence reveals that GCs are often enriched with mutations in homologous recombination-associated genes such as BRCA1/2, and that GC prognosis and response to certain therapies can depend on BRCA1/2 expression. Given the strength of data published to date, a risk management strategy for GC among BRCA1/2 PV carriers is needed, and herein we also propose a potential strategy for GC risk management in this population. Moving forward, further study is clearly warranted to define the mechanistic relationship between BRCA1/2 PVs and development of GC as well as to determine how GC risk management should be factored into the clinical care of BRCA1/2 carriers.

DNA Damage Repair and Current Therapeutic Approaches in Gastric Cancer: A Comprehensive Review

DNA in cells is frequently damaged by endogenous and exogenous agents. However, comprehensive mechanisms to combat and repair DNA damage have evolved to ensure genomic stability and integrity. Improper DNA damage repair may result in various diseases, including some types of tumors and autoimmune diseases. Therefore, DNA damage repair mechanisms have been proposed as novel antitumor drug targets. To date, numerous drugs targeting DNA damage mechanisms have been developed. For example, PARP inhibitors that elicit synthetic lethality are widely used in individualized cancer therapies. In this review, we describe the latent DNA damage repair mechanisms in gastric cancer, the types of DNA damage that can contribute to the development of gastric cancer, and new therapeutic approaches for gastric cancer that target DNA damage repair pathways.