COAD ranks among the prevalent malignant neoplasms. For those in the later stages of stage II and stage III, undergoing surgery along with adjuvant chemotherapy is often advised to mitigate the likelihood of disease recurrence. However, even after radical surgery, roughly 50% of early-stage patients still experience relapse and metastasis[19]. Consequently, there is an imperative for the development of a personalized prognostic model that facilitates tailored treatment and precision medicine approaches for individuals with COAD.
The genesis and advancement of COAD involve the aggregation of numerous genetic and epigenetic changes within the colonic tissue[9]. RNA editing has come to the forefront as a pivotal epigenetic mechanism that contributes to the development and progression of multiple types of cancer[20]. The presence of ADAR1, functioning as either an oncogene or a tumor suppressor, has the potential to modify the properties of tumors, fostering a phenotype that is more aggressive[8]. A number of research studies have shown that RNA editing may serve as a potential therapeutic target across various solid malignancies [21–25]. Consequently, we developed and confirmed a prognostic model leveraging RERGs to forecast the outcomes for COAD patients.
In our quest to identify genes with differential expression tied to RNA editing in COAD, we gathered and scrutinized data from TCGA. This analysis was conducted using univariate Cox regression, multivariate Cox regression, and the LASSO algorithm. Five RERGs(GNL3L, NUP43, MAGT1, EMP2, and ARSD) were identified and utilized to formulate a prognostic risk assessment model. Guanine nucleotide-binding protein-like 3-like (GNL3L), a recently characterized nucleolar GTPase, is known to modulate the mitotic cycle of eukaryotic cells, thereby influencing cellular proliferation and apoptosis[26, 27]. Studies have highlighted GNL3L's substantial involvement in a spectrum of cancers, including renal, colorectal, esophageal, hepatic, rectal, and breast malignancies[28–30]. Overexpression of GNL3L was positively correlated with the progression of colon cancer and inhibition of GNL3L was an efficient therapeutic approach[28]. Overall, GNL3L could be a crucial marker for predicting patient outcomes and is believed to have an immunomodulatory effect in various cancers[31]. Magnesium transporter 1 (MAGT1), known for its high selectivity in transporting magnesium across the plasma membrane[32, 33]. is particularly noteworthy in T-lymphocytes, where it facilitates a swift influx of magnesium post-receptor activation. This function underscores MAGT1's role in mediating immune responses[32, 34, 35]. Recent study has demonstrated that an increase in the expression of the magnesium transporter MAGT1 has been associated with the development of drug resistance in colon cancer[36, 37]. Epithelial membrane protein-2 (EMP2), classified as a tetraspanin, has been detected in breast cancer metastasis and circulating tumor cells [38–40]. Nonetheless, the specific contribution of EMP2 to the pathogenesis of COAD remains largely unexplored. In recent studies, EMP2 has been observed to influence the recruitment of uterine natural killer (NK) cells in mice, suggesting an immunological impact[41]. Arylsulfatase D (ARSE), a member of the sulfatase enzyme family, is integral to the metabolic processes involving sphingolipids[42],whose aberrations have been reported to contribute to chemotherapy resistance in various cancers[43]. ARSD had been implicated in regulation the growth and metastasis of colon cancer[44]. The gene Nuclear Pore 43 (NUP43) is responsible for the production of the Nup107-160 complex, a component that resides at the centromere during mitosis and is instrumental in governing the processes of mitosis and the segregation of chromosomes [45]. NUP43 upregulation was related to DNA amplification[46]. An earlier investigation established that NUP43 functions as an oncogenic promoter in tumor progression[47]. To elucidate the predictive impact of these gene biomarkers on COAD, we advanced a nomogram for forecasting the prognosis of COAD patients. The findings confirmed that these RERGs serve as effective prognostic indicators, exhibiting commendable predictive performance.
The RNA editing enzyme ADAR1 has been found to be irregularly expressed across a spectrum of cancers. Recent studies have shown that elevated levels of ADAR1 are linked to different types of cancer, such as hepatocellular carcinoma, esophageal carcinoma, and colorectal carcinoma[48–50]. ADAR1's regulatory influence is exerted through nonsynonymous substitutions in oncoproteins and alterations in the microRNA interference pathway. These alterations, which can include modifications to protein codes and properties, suggest that increased ADAR1 activity can enhance the invasive and aggressive behavior of colorectal cancer cells[51]. The accuracy of our prediction mode model were further validated with ADAR1. These results indicated that the key role of RNA editing in predicting COAD and high-risk is linked to worse prognosis.
In this study, we conducted an analysis employing GSEA to compare the KEGG gene sets between the high-risk and low-risk cohorts. We found that staphylococcus aureus infection signaling, NOD-like receptor signaling pathway, GABAergic synapse signaling pathway, Fc gamma R-mediated phagocytosis signaling pathway and thiamine metabolism signaling pathway were significantly enriched through KEGG. Most of these enriched signaling pathways were related to immunity. It was known that immune infiltration was associated with COAD[52]. A growing body of evidence has highlighted the link between the immune status in colon cancer and patient outcomes[53]. Staphylococcus aureus, a gram-positive bacterium and an opportunistic pathogen in humans[54] poses a risk for serious infections, particularly when the immune defenses are weakened[55]. NOD-like receptors (NLRs) represent a recently identified class of pattern recognition receptors pivotal in modulating both innate and adaptive immune responses[56]. Their active participation in the regulation of inflammatory signals and the engagement of the adaptive immune system has been associated with their influence on disease progression and tumor development. Notably, the expression of NLRP3 mRNA has been found to be markedly elevated in COAD tumor tissues[57]. Gamma-aminobutyric acid (GABA), primarily recognized for its inhibitory role in the central nervous system by reducing neuronal excitability, is now understood to have additional roles. It is increasingly recognized as an influential factor in the regulation of cancer cell proliferation, spread, and the antitumor immune response[58]. GABA is synthesized and secreted by both mouse and human B cells, and research indicates that GABA derived from B cells or plasma cells is a critical determinant in the regulation of macrophage and CD8 + T cell responses, as well as tumor growth in a murine model of colon cancer[59]. Fc gamma R-mediated phagocytosis receptors are integral to the immune system, bridging the innate and adaptive immune components. They achieve this by linking the specific detection of IgG antibodies to the activation of phagocytic leukocytes, thereby enhancing the immune response against pathogens and other threats[60]. Thiamine (vitamin B1) was related with the immune system and diverse cancers[61, 62]. Our results suggested that the RERGs may mediate the development of tumors through the immune response. Thus, RNA editing may be involved in COAD through multiple targets and signaling pathways.
To sum up, we have developed a prognostic assessment model leveraging five RERGs that exhibit significant predictive power. This research offers a novel approach to personalized therapeutic strategies for individuals afflicted with COAD.