The expression of IL-11RA is down-regulated in lung adenocarcinoma
To evaluate the IL-11RA expression in various tumours, we searched Transcriptome-seq data in the TIMER database (Fig. 1A). The result revealed that the IL-11RA mRNA expression in liver hepatocellular carcinoma (LIHC), pheochromocytoma, and paraganglioma (PCPG) were higher compared to normal tissues, while it was considerably lower in bladder urothelial carcinoma (BLCA), invasive breast carcinoma (BRCA), cervical squamous cell carcinoma and endocervical adenocarcinoma (CESC), colon adenocarcinoma (COAD), esophageal carcinoma (ESCA), kidney chromophobe (KICH), kidney renal clear cell carcinoma (KIRC), kidney renal papillary cell carcinoma (KIRP), lung adenocarcinoma (LUAD), lung squamous cell carcinoma (LUSC), prostate adenocarcinoma (PRAD), rectum adenocarcinoma (READ), stomach adenocarcinoma (STAD), thyroid carcinoma (THCA) and uterine corpus endometrial carcinoma (UCEC) than in the normal tissue. These data show that IL-11RA has a significant differential expression between tumour tissues and normal tissues, and it may be regarded as oncogenic gene, particularly in LUAD. To further investigate the relevance of IL-11RA expression level with human LUAD, we performed a detailed analysis of RNA-Seq data from the GEPIA and TCGA databases. The quantitative evaluation of the expression level of IL-11RA mRNA in LUAD tissues was significantly lower than that in normal tissues (Fig. 1B and Fig. 1C). Data from tumor and matched normal tissues of LUAD patients in the TCGA further verified these results (Fig. 1D). Besides, we further analyzed the protein level of IL-11RA in LUAD tissues from the Human Protein Atlas (HPA) database. Immunohistochemical results indicated that the protein expression level of IL-11RA exhibited significant upregulation in LUAD tissues. Overall, these results suggest that the expression of IL-11RA is decreased in various types of cancer, particularly in LUAD, demonstrating that IL-11RA may suppress LUAD tumorigenesis.
The correlation between IL-11RA mRNA expression level and clinicopathological parameters of LUAD
In order to clarify the correlation between IL-11RA mRNA expression level and clinicopathological parameters of LUAD, we investigated IL-11RA expression on the basis of patients’ different clinical pathological parameters, such as age, gender, stage, lymph -node status, smoking habits using UALCAN database. Results showed that IL-11RA expression was much lower in LUAD patients than normal tissues in subgroup analysis based on age and gender (Fig. 2A and Fig. 2B). For cancer stages and lymph node status, IL-11RA expression was lower expressed in different subclasses than that in normal lung tissues (Fig. 2C and Fig. 2D). It is highly intriguing that the expression of IL-11RA decreases as the stage increases between stage 1 and stage 3 (Fig. 2C), and IL11RA also decreases with the increase of the lymph node stage between N0 and N2 (Fig. 2D). Besides, IL-11RA expression was closely associated with smoking habits (Fig. 2E). An analysis of subclass showed that IL-11RA expression was much lower in lung adenocarcinoma patients who smoke or those who have smoked for more than 15 years than lung adenocarcinoma patients who do not smoke or those who have smoked for less than 15 years. All these data together indicated that low IL-11RA expression was widely correlated with lung adenocarcinoma.
Low expression of IL-11RA is associated with poor prognosis of LUAD
The Kaplan-Meier plotter database was utilized to explore the correlation between IL-11RA expression and prognosis in LUAD. Firstly, according to the IL-11RA expression median value, LUAD samples were divided into IL-11RA high (top 50%) expression group and IL-11RA low (bottom 50%) expression group. Low expression of IL-11RA was associated with poor overall survival (OS) in patients with LUAD (hazard ratio [HR] = 0.54, 95% confidence interval [CI] = 0.42–0.69, log-rank P = 4.7e-07) (Fig. 3A). Similarly, low IL-11RA expression was significantly associated with reduced progression-free survival (PFS) (Fig. 3B, HR = 0.37, 95% CI = 0.26–0.57, log-rank P = 8.8e-10). Furthermore, low expression of IL-11RA, which was capable of predicting poor OS, was also validated in TCGA database (Fig. 3C, HR = 0.64, 95% CI = 0.48–0.85, P = 0.001) and GSE72094 database (Fig. 3D, HR = 0.37, 95% CI = 0.25–0.54, P < 0.001). Based on this large-sample validation analysis, these results suggest that low IL-11RA expression implies reduced survival in LUAD.
To better understand the effect of decreased expression of IL-11RA on survival, the Kaplan-Meier plotter database was accessed to analyze the correlation between IL-11RA expression and clinical characteristics of patients by univariate cox regression analysis (Table 1). The low expression of IL-11RA corresponded with worse OS and PFS in women, male, smoking or nonsmoking patients (P < 0.05). For clinical staging, downregulation of IL-11RA was linked to worse OS in stage 1, stage N0, and stage M0 in LUAD (P < 0.05) and worse PFS in stage 1 (P < 0.05).
Table 1. Correlation of IL-11RA mRNA expression and clinical prognosis in LUAD by Kaplan-Meier plotter
|
Overall survival (n = 719)
|
Progression-free survival (n = 641)
|
N
|
HR (95% CI)
|
p-value
|
N
|
HR (95% CI)
|
p-value
|
Gender
|
|
|
|
|
|
|
Female
|
317
|
0.45 (0.3-0.68)
|
8.4e-05
|
235
|
0.51 (0.32-0.82)
|
0.0043
|
Male
|
344
|
0.51 (0.36-0.71)
|
7.1e-05
|
226
|
0.3 (0.19-0.49)
|
1.5e-07
|
Stage
|
|
|
|
|
|
|
1
|
370
|
0.21 (0.13-0.35)
|
8.7e-12
|
283
|
0.38 (0.23-0.63)
|
0.00011
|
2
|
136
|
0.76 (0.47-1.22)
|
0.25
|
103
|
0.9 (0.52-1.55)
|
0.69
|
3
|
24
|
0.7 (0.26-1.87)
|
0.47
|
10
|
-
|
-
|
4
|
4
|
-
|
-
|
0
|
-
|
-
|
T stage
|
|
|
|
|
|
|
1
|
123
|
0.55 (0.29-1.03)
|
0.057
|
47
|
0.73 (0.16-3.25)
|
0.67
|
2
|
105
|
0.72 (0.41-1.26)
|
0.25
|
93
|
1.39 (0.74-2.64)
|
0.31
|
3
|
4
|
-
|
-
|
2
|
-
|
-
|
4
|
0
|
-
|
-
|
0
|
-
|
-
|
N stage
|
|
|
|
|
|
|
0
|
184
|
0.54 (0.33-0.89)
|
0.013
|
102
|
0.87 (0.4-1.87)
|
0.72
|
1
|
44
|
0.83 (0.38-1.81)
|
0.63
|
38
|
1.1 (0.44-2.76)
|
0.83
|
2
|
3
|
-
|
-
|
2
|
-
|
-
|
M stage
|
|
|
|
|
|
|
0
|
231
|
0.51 (0.34-0.77)
|
0.0011
|
142
|
0.77 (0.44-1.37)
|
0.38
|
1
|
1
|
-
|
-
|
0
|
-
|
-
|
Smoke
|
|
|
|
|
|
|
Ever
|
246
|
0.37 (0.22-0.61)
|
5.8e-05
|
243
|
0.43 (0.27-0.68)
|
0.00021
|
Never
|
143
|
0.19 (0.07-0.56)
|
0.00079
|
143
|
0.4 (0.21-0.77)
|
0.0047
|
Table 2
Correlation analysis between IL-11RA and relate genes and markers of immune cells in TIMER
Description
|
Gene Markers
|
None adjusted
|
Tumor purity adjusted
|
Cor
|
P-value
|
Cor
|
P-value
|
Activated B cell
|
CD19
|
0.21
|
1.52e-06
|
0.226
|
4.11e-07
|
|
CD79A
|
0.105
|
1.74e-02
|
0.101
|
2.52e-02
|
|
GNG7
|
0.456
|
8.78e-28
|
0.456
|
1.02e-26
|
|
BLK
|
0.301
|
3.09e-12
|
0.323
|
1.88e-13
|
|
CLEC9A
|
0.242
|
2.73e-08
|
0.232
|
1.96e-07
|
Immature B cell
|
CD22
|
0.388
|
5.62e-20
|
0.425
|
4.57e-23
|
|
FCRL1
|
0.329
|
1.9e-14
|
0.349
|
1.52e-15
|
|
FAM129C
|
0.345
|
7.45e-16
|
0.374
|
9.05e-18
|
|
TXNIP
|
0.284
|
5.19e-11
|
0.281
|
2.01e-10
|
|
STAP1
|
0.276
|
1.98e-10
|
0.277
|
4.02e-10
|
Memory B cell
|
FCER1A
|
0.309
|
6.95e-13
|
0.305
|
4.39e-12
|
|
SOX5
|
0.228
|
1.67e-07
|
0.232
|
1.99e-07
|
|
TLR9
|
0.137
|
1.77e-03
|
0.134
|
2.82e-03
|
|
CCNA2
|
-0.408
|
4.95e-22
|
-0.42
|
1.53e-22
|
|
CDKN3
|
-0.389
|
4.39e-20
|
-0.407
|
4.03e-21
|
Th1
|
T-bet (TBX21)
|
0.199
|
5.07e-06
|
0.19
|
2.15e-05
|
|
STAT4
|
0.231
|
1.19e-07
|
0.221
|
6.95e-07
|
|
TNF-a (TNF)
|
0.17
|
1.01e-04
|
0.148
|
9.77e-04
|
|
STAT1
|
-0.082
|
6.17e-02
|
-0.125
|
5.39e-03
|
Th2
|
STAT6
|
0.257
|
3.15e-09
|
0.269
|
1.22e-09
|
|
STAT5A
|
0.278
|
1.3e-10
|
0.27
|
1.11e-09
|
|
IL13
|
0.165
|
1.67e-04
|
0.144
|
1.39e-03
|
|
GATA3
|
0.104
|
1.82e-02
|
0.072
|
1.12e-01
|
Tfh
|
BCL6
|
0.236
|
6.11e-08
|
0.232
|
1.89e-07
|
|
IL21
|
-0.042
|
3.39e-01
|
-0.069
|
1.26e-01
|
Th17
|
STAT3
|
0.129
|
3.28e-03
|
0.126
|
4.92e-03
|
|
IL17A
|
-0.063
|
1.51e-01
|
-0.07
|
1.23e-01
|
Treg
|
STAT5B
|
0.329
|
1.89e-14
|
0.333
|
3.26e-14
|
|
FOXP3
|
0.135
|
2.16e-03
|
0.12
|
7.81e-03
|
|
CCR8
|
0.084
|
5.65e-02
|
0.063
|
1.64e-01
|
T cell exhaustion
|
CTLA4
|
0.147
|
7.97e-04
|
0.12
|
7.55e-03
|
|
TIM-3 (HAVCR2)
|
0.12
|
6.61e-03
|
0.082
|
7.03e-02
|
|
GZMB
|
-0.186
|
2.25e-05
|
-0.243
|
4.76e-08
|
|
PD-1 (PDCD1)
|
0.073
|
9.91e-02
|
0.045
|
3.24e-01
|
CD8+ T cell
|
CD8A
|
0.043
|
3.35e-01
|
0.013
|
7.74e-01
|
|
CD8B
|
0.055
|
2.17e-01
|
0.031
|
4.92e-01
|
M1 Macrophage
|
IRF5
|
0.213
|
1.02e-06
|
0.195
|
1.27e-05
|
|
INOS (NOS2)
|
0.058
|
1.9e-01
|
0.044
|
3.27e-01
|
|
COX2 (PTGS2)
|
-0.094
|
3.27e-02
|
-0.115
|
1.06e-02
|
M2 Macrophage
|
CD163
|
0.103
|
1.89e-02
|
0.063
|
1.6e-01
|
|
VSIG4
|
0.143
|
1.18e-03
|
0.112
|
1.24e-02
|
|
MS4A4A
|
0.156
|
3.72e-04
|
0.123
|
6.32e-03
|
Neutrophil
|
CD66b (CEACAM8)
|
0.278
|
1.33e-10
|
0.279
|
2.7e-10
|
|
CD11b (ITGAM)
|
0.256
|
3.89e-09
|
0.234
|
1.54e-07
|
|
CCR7
|
0.271
|
3.9e-10
|
0.289
|
6.16e-11
|
Dendritic cell
|
HLA-DPB1
|
0.382
|
2.36e-19
|
0.39
|
2.35e-19
|
|
HLA-DPA1
|
0.326
|
3.13e-14
|
0.326
|
1.15e-13
|
|
BDCA-1 (CD1C)
|
0.329
|
1.95e-14
|
0.323
|
2.07e-13
|
|
CD11C (ITGAX)
|
0.315
|
2.45e-13
|
0.308
|
2.84e-12
|
TAM
|
IL10
|
0.17
|
1.04e-04
|
0.144
|
1.37e-03
|
|
CCL2
|
0.075
|
8.93e-02
|
0.045
|
3.16e-01
|
|
CD68
|
0.098
|
2.64e-02
|
0.071
|
1.13e-01
|
Analysis of IL-11RA methylation profile in LUAD patients
To further identify the potential mechanism leading to the downregulation of IL-11RA in LUAD, we firstly analyzed the DNA methylation levels of IL-11RA in the 471 LUAD samples and 32 normal samples from TCGA database. We found that the DNA methylation levels of IL-11RA were significantly higher in LUAD tissues than in normal lung tissues (Fig. 4A, P = 2.079e-12). Consecutively, the correlation between DNA methylation level and expression of IL-11RA in LUAD was assessed. The result indicates that the mRNA expression level of IL-11RA was negatively correlated with its DNA methylation level (Fig. 4B, Cor = -0.22, P = 2.2e-06). These results showed that the hypermethylation of IL-11RA might contribute to the downregulation of IL-11RA in LUAD. Furthermore, we discovered that LUAD patients with the higher methylation level of CpG sites cg14609668 (Fig. 4C) and cg21504624 (Fig. 4D) had a worse OS. These results suggest that the methylation and expression level of IL-11RA could influence the prognosis of LUAD patients.
IL-11RA is involved in immune infiltration and proliferation in LUAD
To further explore the biological function of IL-11RA in LUAD, we performed Gene Set Enrichment Analysis (GSEA) analysis. Previously, research has shown that the occurrence and development of tumor are closely related to immune infiltration levels [16]. Therefore, we utilize GSEA to explore the correlation of IL-11RA and immune infiltration. Enrichment results showed that many gene sets related to immune activation, such as activation of immune response (Fig. 5A), immune receptor activity (Fig. 5B), leukocyte mediated cytotoxicity (Fig. 5C), T cell activation (Fig. 5D), B cell activation (Fig. 5E), Macrophage activation (Fig. 5F), were enriched in the IL-11RA high expression group, which suggests that IL-11RA low expression may promote the progression of LUAD through immune inhibition. Furthermore, we found that several cell cycle-related gene sets were enriched in the IL-11RA low expression group (Fig. 5G-5I), which indicates that IL-11RA low expression may also be involved in facilitating cell proliferation in LUAD.
Correlation analysis between IL-11RA expression and six main infiltrating immune cells and its immune marker genes
To further clarify the correlation between IL-11RA expression and immune infiltration of LUAD, we firstly calculated the immune scores of the LUAD samples by the ESTIMATE algorithm using the data from TCGA database to predict the presence of infiltrating immune cells. The results found that the immune scores were lower in the IL-11RA low group (Fig. 6A), which indicated that IL-11RA low expression might be involved in the immune inhibition of LUAD.
Then, considering that IL-11RA is a crucial mediator of immune cell activation, a correlation analysis between IL-11RA expression and six types of immune-infiltrating cells, including B cells, CD4+ T cells, macrophages, CD8+ T cells, neutrophil and myeloid dendritic cell was performed via the TIMER database. The results showed that IL-11RA expression levels were significantly positively correlated with levels of infiltrating B cells, CD4+ T cells, and myeloid dendritic cell in LUAD (Fig. 6B-6H). Taken all together, the above evidence indicates that IL-11RA may be involved in the immune response of patients with LUAD by affecting the immune cells.
Lastly, to expand the understanding of the crosstalk between IL-11RA and multiple marker genes of immune cells, we did correlation analysis between them via the TIMER database. The results found that 44/52 (84.62%) immune cell markers were significantly associated with IL-11RA expression (P < 0.05), of which the number of positive correlations was 40/52 (76.92%), and the negative was 4/52 (7.69%). The results showed that the expression level of IL-11RA was significantly correlated with most immune markers of immune cells in LUAD.