Immunogenomic analyses between CCR7_H and CCR7_L
The ssGSEA score was conducted to analyze the 29 sets of immune-associated genes of LIHC samples, which represent levels of immune cells, functions or pathways. The ssGSEA results show that in CCR7_H group immune cells, functions and pathways enriched (Fig. 1A). The Immune score, Stromal score and ESTAMATE score are higher in CCR_H group, while tumor purity higher in CCR_L group (P < 0.001) (Fig. 1A,1C). In general, the level of immune status contraries to tumor purity.
The expression of HLA genes and immune checkpoint genes were also analyzed for understand immunogenomic of LIHC. The HLA genes expressed higher in CCR7_H group, as well as immune chick point genes (P < 0.001) (Fig. 1B, 1D). The survival curve between CCR7_H and CCR7_L was also printed, and the results showed favorable survival rate in CCR7_H group (Fig. 1E), which has higher immune score and lower tumor purity than CCR7_L group. This means immunocompromising condition of LIHC patients in CCR7_H group and potent positive effect of immune checkpoint inhibitors in LIHC patients in CCR7_H group.
Identification of differential expressed immune genes
After analyzed the expression levels of immune genes, there are 903 DEIGs were identified by limma package (Fig. 2A). Then, the functions and pathways enrichment of DEIGs was achieved through pooling those genes into Metascape and DAVID website. Results showed that the DEIGs mainly enriched in complement activation, adaptive immune response, T cell activation, lymphocyte differentiation and cytokine-cytokine receptor interaction (Fig. 2B). We also made a network of those terms to clarify the relationship among them, the terms with a similarity of > 0.3 was chosen and connected by edges (Fig. 2C). besides, when the criteria of no more than 15 items per cluster and no more than 250 items in total were met, the item with the best P value was selected from each of the 20 clusters (Fig. 2D).
Construction of the CCR7-related immune prognostic signature
The samples in train set were performed by LASSO Cox regression and the risk score (Fig. 3A, 3B) for patients can be calculated through coefficients in Table 1. The prognostic signature has a good model recognition ability with the C-index (0.755). According to the risk score, patients were divided into high risk group and low risk group both in train set and test set. The survival rate of LIHC patients with low risk score have favorable survival rate in train set, as well as in test set (Fig. 3C). The ROC curve analysis of IPS showed hopeful prognostic ability for LIHC patients with AUC of 0.763 in train set and 0.706 in test set (Fig. 3D). In addition, the risk curve and expression pattern of DEIGs in IPS were conducted, the result showed patients with high risk score suffer from shorter survival time and higher mortality rate (Fig. 3E, 3F).
Table 1
The coefficients of genes in IPS.
| coef | HR | HR.95L | HR.95H | pvalue |
IGHV4-59 | -0.001234 | 0.998767 | 0.997577 | 0.999959 | 0.042554 |
SCML4 | -0.003202 | 0.996803 | 0.993533 | 1.000085 | 0.056235 |
AKR1B10 | 5.59E-06 | 1.000006 | 1.000001 | 1.00001 | 0.018331 |
LINC00426 | -0.015754 | 0.98437 | 0.964057 | 1.005111 | 0.138659 |
TRGC1 | -0.004025 | 0.995983 | 0.989235 | 1.002777 | 0.245863 |
F2RL2 | 0.001597 | 1.001598 | 1.000604 | 1.002594 | 0.001623 |
TRBV10-3 | -0.066678 | 0.935496 | 0.869104 | 1.00696 | 0.07585 |
SAMD9L | 0.001694 | 1.001696 | 1.000896 | 1.002497 | 3.24E-05 |
SLC4A10 | -0.026015 | 0.97432 | 0.940706 | 1.009136 | 0.146428 |
ROR2 | 0.00103 | 1.001031 | 1.000352 | 1.001709 | 0.002893 |
Establishment an IPS-based nomogram model
Before construct the nomogram model, Univariate Cox analysis and Multivariate Cox analysis were performed. The result showed that the IPS correlated with OS of LIHC patients (Hazard ratio: 1.059(1.040–1.079), P < 0.001) and is an independent prognostic factor (Hazard ratio: 1.056 (1.034–1.078), P < 0.001) (Fig. 4A, 4B and Table 2). The nomogram model was constructed based on Multivariate Cox analysis (Fig. 4C). A good consistency was showed by the 1-, 3- and 5- year calibration diagram (Fig. 4D).
Table 2
Univariate and multivariate Cox analyses indicated that IPS was an independent prognostic factor.
| ID | HR | HR.95L | HR.95H | pvalue |
UniCox | age | 1.010933 | 0.99593 | 1.026163 | 0.154063 |
gender | 0.81371 | 0.551799 | 1.199937 | 0.298229 |
grade | 1.113202 | 0.861773 | 1.437988 | 0.411626 |
stage | 1.66902 | 1.356537 | 2.053485 | 1.28E-06 |
riskScore | 1.059423 | 1.040005 | 1.079204 | 9.61E-10 |
MultiCox | age | 1.014899 | 0.999657 | 1.030373 | 0.055429 |
gender | 0.933891 | 0.623707 | 1.398336 | 0.73983 |
grade | 1.135503 | 0.860345 | 1.498663 | 0.369434 |
stage | 1.591535 | 1.283261 | 1.973864 | 2.33E-05 |
riskScore | 1.055509 | 1.03394 | 1.077528 | 2.92E-07 |