Genetic Mutation Landscape of LRGs in COAD
Somatic mutations were identified by examining the occurrence rates of 31 LRGs. As shown in Figure A1, among 454 COAD samples, 116 (25.55%) had gene mutations. The results revealed that NPC1 had the highest mutation rate among the 31 LRGs, followed by GAA and GNPTAB. We also discussed the occurrence rates of CNV mutations, where significant variations were observed in CNV mutations of the 31 LRGs (Fig. 1B). In addition, we constructed a protein-protein interaction (PPI) analysis through the STRING website to illustrate the interactions between LRGs (Fig. 1C). The transcript abundance of the 31 LRGs in tumor and normal tissues was determined using the TCGA-COAD dataset, and 24 DEGs were identified, most of which were abundant in tumors (Fig. 1D). Our study suggests that LRGs have potential roles in the formation and advancement of COAD, as they exhibit significant differences in expression levels and genomic background between cancerous and normal tissues.
Generation of Lysosomes Subgroups in COAD
A total of 424 COAD individuals from the TCGA-Coad repository were included as subjects in this research. the correlation between lysosomes and cancer was evaluated by analyzing the selected patients. Table S1 displays the complete data for the patients. In 31 COAD patients, we evaluated the prognostic value of LRGs using uniCox. Subsequently, using consensus clustering analysis, we additionally explored the connection between the expression patterns of LRCs and COAD subtypes. Based on the expression levels of LRG, COAD patients were classified. According to the research findings, the optimal value for the clustering variable was 2, enabling an effective distribution of patients across the entire cohort between C1 (n = 246) and C2 (n = 178) (Fig. 2A). Next, we assessed the overall survival (OS)of both patient groups and discovered a substantial distinction in the survival rate between them (Fig. 2B). Finally, through genome comparison, significant differences were observed in the expression of LRGs in the clinical and pathological characteristics of the two clusters, as presented in Fig. 2C.
Features of the TME in Various Subgroups
To evaluate the penetration levels of 22 distinct human immune cell categories in the two clusters utilizing the CIBERSORT approach to investigate the association between LRGs and the TME in COAD patients (Fig. 3A). The study revealed significant variations in the abundance of immune cells between the two clusters. The C1 group was significantly better than the C2 group in terms of plasma cells, CD4 + memory-activated T cells, CD4 + memory-activated T cell concentration, and expression reversal of regulatory T cells (Tregs), NK cell activation, macrophages, and so on, while the opposite was true for M0 dendritic cells at rest, dendritic cell activation, and eosinophils expression. As the TME score can assess the levels of immune and matrix components in the TME, we utilized estimation algorithms to obtain the TME score in all clusters. Based on the study, we found that the TME score of cluster C2 was notably greater than that of cluster C1 (Fig. 3C).
Gene Subgroup Identification Using DEGs and Functional Analysis
Utilizing the "limma" package, we identified 1,601 differentially expressed genes (DEGs) associated with lysosomes. To further explore this, we conducted a functional enrichment analysis on the potential biological activities of these DEGs (Table S2). GO enrichment indicated that DEGs are enriched in leukocyte-mediated immunity, positive regulation of cell activation, negative regulation of immune system activity, leukocyte migration, endocytic vesicles, and immune receptor activity (Fig. 4A). Similarly, KEGG enrichment analysis also identified several immune and lysosome-related processes, signaling pathways, and diseases, including phagosome, rheumatoid arthritis, cell adhesion molecules, the IgA-mediated intestinal immune network, and chemokine signaling pathways (Fig. 4B). the GO and KEGG functional analyses demonstrated significant correlations between these processes and tumor development and immunity, emphasizing the potential association between lysosomal function and immunoregulation in COAD.
Establishment of LRG-Based Risk Model.
To assess the prognostic significance of LRGs in COAD, a risk model was developed. First, by using LASSO-COX analysis, identified candidate genes were for developing a risk model. and the selected genes were then evaluated (Fig. 5A). Through calculation, we identified six key genes: CTSD, IDUA, GLA, FUCCA1, NAGLU, and M6PR, and demonstrated via Kaplan-Meier analysis that these genes could be crucial prognostic indicators for COAD patients, As shown in Fig. 5B. Furthermore, the established risk model could effectively stratify COAD patients into high-risk and low-risk groups based on the expression levels of identified genes, with higher expression observed in the high-risk group as compared to the low-risk group. (Fig. 5C). Generally, patients in the low-risk group are expected to have longer survival than those in the high-risk group. As illustrated in Fig. 5D, the performance evaluation results of the risk model were represented using the ROC curve. The analysis indicated that the established risk model had high accuracy for predicting patient prognosis within five years, with corresponding areas under the ROC curve at one, three, and five years being 0.701, 0.677, and 0.775, respectively (Fig. 5E). To evaluate the prediction stability of the risk model, we studied the risk model for both test and training cohorts. Patients were stratified into different subgroups based on the median of the training cohort. The subsequent survival analysis revealed a significantly higher OS rate in the low-risk group of patients compared to the high-risk group, which was based on the median of the training cohort. The high AUC value of this risk model indicates its effectiveness in assessing the prognosis of COAD patients. Finally, we also predicted the survival probabilities for one, two, and three years.
Clinical Analysis of the Prognostic
Using uniCox and multiCox analyses to investigate the prognostic independence of various clinical parameters, in order to evaluate the independent prognostic significance of LRGs in COAD patients. The study showed that age, T stage, and risk scores were independent factors that could be used for effectively assessing the prognosis of COAD patients, as illustrated in Fig. 6A. Subsequently, a nomogram was created as a clinically relevant quantitative method, and this nomogram can be used in conjunction with various prognostic factors to help clinicians predict the 1, 3, and 5-year OS of COAD patients (Fig. 6B). The Nomogram's Calibration Curve Showed a High Degree of Accuracy in Predictions. (Fig. 6C).
Features of the TME in Various Risk Scores
The CIBERSORT algorithm is used to evaluate the relationship between the risk group and immune cell infiltration. As demonstrated in Fig. 7A, a positive correlation is observed between the risk group and the infiltration of macrophage M0, resting NK cells, and regulatory T cells (Tregs), but is negatively correlated with follicle-assisted plasma cells and resting CD4 memory T cells. Furthermore, the research identified a strong correlation between the immune score and matrix score within the risk group. (Fig. 7B). Next, we investigate the connection between immune cell enrichment and prognostic genes. The research results indicate that the selected genes exhibited a close association with the majority of immune cells. (Fig. 7C).
Association of Risk scores with TMB
Our findings demonstrated that the high-risk group had a greater Tumor Mutational Burden (TMB) compared to the low-risk group. (Fig. 8A), Implying that high-risk patients may derive greater benefits from immunotherapy. We also examined the distribution of somatic mutations in the TCGA-COAD dataset according to the risk scores model. The mutation rates of APC, TP53, TTN, KRAS, PIK3CA, SYNE1, MUC16, and FAT4 were observed to be equal to or greater than 20% among COAD patients in both risk groups. as shown in Figs. 8B and C.
Drug Sensitivity Analysis
Through computation of IC50 values of 138 drugs in TCGA-COAD patients. we identified the risk scores as a biomarker to predict treatment response among COAD patients. The research indicates that patients with low-risk scores could potentially respond favorably to ABT263, AZD6244, BI2536, Elesclomol, MS.275, NVPTAE684, Pazopanib, and Roscovitine (Figs. 9A-H). Overall, these findings suggest a relationship between LRGs and drug sensitivity.