In present study, we divided the 944 cases with NSCLC into training set (473 cases) and validation set (471 cases) and obtained the gene set (REACTOME_CIRCADIAN_CLOCK) related to biological clock from Molecular Signatures Database. We established a prognostic model for clock-related lncRNAs in NSCLC cases, and explored its relationship with tumor immune microenvironment. The results indicated that patients in the low-risk group were significantly associated with better OS than patients in the high-risk group. In addition, the proportion of Neutrophils cells Macrophages M0, and Macrophages M1 in the high-risk group was significantly higher than that in the low-risk group.
Of these three risk factors of clock-related lncRNAs, 'ITGA9-AS1' is positively associated with the OS of patients with breast cancer, and ELOVL2-AS1 may be considered as a potential prognostic biomarker for patients with tamoxifen resistance16. Of the remaining nine protective factors, AC145124.1 showed valuable prognostic effects in BLCA patients17. MIR133A1HG is identified as a autophagy-related lncRNAs, and might be a novel biomarkers for predicting the survival of AML patients18. However, the importance of AC022165.1, AC026310.2 and other seven protective factors in NSCLC is rarely reported. Given the validated evidence of AC145124.1 and MIR133A1HG in previous studies, as well as our findings, these two lncRNAs might play important roles in NSCLC, which should be explored for their biological function in future research. In addition, our results found that the risk score of 12 clock-related lncRNAs showed great prognostic value in NSCLC cases, were presented at Table 2. Previous studies proposed that the risk score constructed based on four lncRNAs can effectively predict prognosis of glioblastoma19. Then, we performed
Table 2
Twelve prognostic clock-related lncRNAs identified from Pearson’s correlation analysis and multivariate Cox regression analysis.
id | coef | HR | HR.95L | HR.95H | pvalue |
AL133445.2 | -0.199 | 0.820 | 0.687 | 0.979 | 0.028 |
AC022165.1 | 0.328 | 1.388 | 1.204 | 1.600 | 6.091 |
AC037441.1 | -0.077 | 0.926 | 0.836 | 1.026 | 0.141 |
AC026310.2 | 0.181 | 1.199 | 1.085 | 1.323 | 0.000 |
AC022540.1 | -0.150 | 0.861 | 0.724 | 1.022 | 0.088 |
`ITGA9-AS1` | 0.235 | 1.264 | 1.033 | 1.547 | 0.023 |
MIR133A1HG | -0.269 | 0.764 | 0.637 | 0.917 | 0.004 |
AC114980.1 | -0.160 | 0.852 | 0.717 | 1.013 | 0.070 |
AL161757.5 | -0.289 | 0.749 | 0.635 | 0.883 | 0.001 |
AC145124.1 | -0.177 | 0.838 | 0.728 | 0.965 | 0.014 |
AC020765.2 | -0.141 | 0.868 | 0.762 | 0.990 | 0.035 |
AC007663.4 | -0.132 | 0.876 | 0.734 | 1.046 | 0.143 |
Kaplan-Meier survival curves analysis in the training set and validation set, and found that patients with high-risk scores were significantly related with worse OS than patients with low-risk scores (P < 0.001). The same results were obtained in the validation set (P < 0.05). ROC analysis indicated that the risk score clock-related lncRNAs showed great predictive value for prognosis of NSCLC cases. Moreover, the 1-year, 3-year and 5-year prognostic risk models constructed in other studies have shown that the predictive value of risk signature for 1-year OS for LUAD patients was better than that in the 3- and 5-year OS20. Although our study did not discuss prognostic differences in overall survival of NSCLC, it has been proved that this model has good sensitivity and specificity, and can reflect the prognosis of NSCLC patients to a certain extent, providing a basis for clinical prognosis diagnosis and treatment of NSCLC patients.
In KEGG enrichment analysis, the signaling pathways, including PI3K − Akt signaling pathway and Herpes simplex virus 1 infection, were significantly upregulated in clock-related lncRNAs. Previous studies indicated that the activated T lymphocytes were sensitive to HSV1 infection. Once infected by HSV1, T cells might leads to rapid elimination of antiviral T cells, followed by immune dysfunction. Much evidence has shown that lncRNAs are involved in the development of NSCLC and play a variety of roles in the cell regulation process, such as promoting cell growth, proliferation, apoptosis, migration, invasion and inducing epithelial-mesenchymal transformation21,22,23. The development of NSCLC involves in multiple signaling pathways, among which PI3K/protein kinase B, phosphatidylinositol-3 -kinase, PKB /Akt/mammalian target of rapamycin, which mTOR pathway is one of the most important regulatory pathways in NSCLC. It affects the development of NSCLC by inducing cell apoptosis, inhibiting cell proliferation, invasion, and migration, and regulating tumor angiogenesis24,25,26. In the GO analysis, the clock-related lncRNAs were significantly enriched in the cell-cell junction, transcriptional coregulator activities, and regulation of cell morphogenesis.
In recent years, more and more studies have discussed the effects of tumor immune microenvironment on the prognosis of lung cancer, but no consensus has been reached. In this study, B cell naive and Mast cells were significantly enriched in the low-risk groups (P < 0.01), indicating that it has a better prognosis than non-small cell lung cancer. While Macrophages M0, Macrophages M1 and Neutrophils cells showed high infiltration abundance in the high-risk groups (P < 0.01), indicating that its increase was a poor prognostic factor for NSCLC.
To our knowledge, few studies explore the relationship between clock-related lncRNAs and prognostic of NSCLC, our results identified a new biomarker to predict the prognosis of NSCLC. However, there are some limitations in our study. On the one hand, the prognostic risk signature of clock-related lncRNAs was constructed based on the bioinformatics analysis of large dataset from TCGA database. Although our results showed good sensitivity and specificity, the predictive value still needs to be validated by large number of clinical research. On the other hand, the study was analyzed using publicly available datasets, while it's impossible to obtain all clinical data from each patient.