The mRNA Expression Levels of FAM83A in Various Human Tumors
The FAM83A mRNA expression level was compared between human tumors and paired normal tissues across various cancer types based on the data from ONCOMINE. The results revealed that the FAM83A expression was higher in bladder, colorectal, head and neck, lung, pancreatic cancers, as well as myeloma tumors, compared with normal tissues; while a lower expression of FAM83A was only found in the esophageal cancer dataset (Fig. 2A). No significant difference in the FAM83A expression was observed in brain and central nervous system, cervical, kidney, liver, ovarian, prostate cancers, as well as leukemia, lymphoma, myeloma, sarcoma. The detailed results of FAM83A expression in different cancer datasets were summarized in Additional Table 1.
We also examined FAM83A expression with RNA-sequencing data from the Cancer Genome Atlas (TCGA) using TIMER. The expression levels of FAM83A across 39 tumor samples and matched normal tissues are displayed in Fig. 2B. The FAM83A expressed significantly lower in PRAD (prostate adenocarcinoma) than in the corresponding normal tissue (P < 0.001). On the contrary, BLCA (bladder urothelial carcinoma), BRCA (breast invasive carcinoma), COAD (colon adenocarcinoma), HNSC (head and neck squamous cell carcinoma), ESCA (esophageal carcinoma), KIRP (kidney renal papillary cell carcinoma), LUAD, LUSC, READ (rectum adenocarcinoma), STAD (stomach adenocarcinoma), and UCEC (uterine corpus endometrial carcinoma) revealed significantly higher expression of FAM83A compared with their adjacent normal tissues (P < 0.05). The meta-analysis from LCE database endorsed that FAM83A expression was significant difference both in LUAD (standard mean difference, SMD = 2.16, 95%CI 1.37 to 2.95) and LUSC (SMD = 1.53, 95%CI 1.05 to 2.01) across several studies (Fig. 3A, B).
Prognostic Value of FAM83A Expression in Cancers
The impact of FAM83A expression on survival was evaluated via PrognoScan. The results were summarized in Additional Table 2. FAM83A expression was significantly associated with prognosis in lung, breast, brain, and colorectal cancers (Fig. 4). Notably, compared with low FAM83A expression (The cut-off value of FAM83A mRNA expression was set as 50%.), high expression of FAM83A predicted worse RFS (GSE31210 HR = 1.79, Cox P < 0.001; GSE8894 HR = 1.17 Cox P = 0.020) and OS (GSE31210 HR = 1.99, Cox P < 0.001; GSE3141 HR = 1.30 Cox P = 0.004) in lung cancer (Fig. 4A-4D). Meanwhile, FAM83A also played a detrimental role in other three cancer types (Cox P < 0.05) (Fig. 4E-4H).
To further assess the prognostic value of FAM83A in different cancers, we analyzed the association between FAM83A mRNA expression and prognosis via Kaplan-Meier plotter, which is based on Affymetrix microarray information. Consistent with the above-mentioned results, the poor PPS and OS in lung cancer (PPS: HR = 1.89, 95%CI 1.22 to 2.91, log-rank p < 0.01; OS: HR = 1.27, 95%CI 1.08 to 1.50, log-rank p < 0.01) and gastric cancer (PPS: HR = 1.36, 95%CI 1.04 to 1.79, log-rank p < 0.05; OS: HR = 1.27, 95%CI 1.00 to 1.60, log-rank p < 0.05) correlated with higher FAM83A expression (Fig. 5A, B, E, F). However, in breast cancer, high mRNA expression of FAM83A was significantly associated with a better RFS (HR = 0.85, 95%CI 0.73 to 0.99, log-rank p < 0.05) but a worse OS (HR = 1.53, 95%CI 1.11 to 2.11, log-rank p < 0.01) (Fig. 5C, D). While high FAM83A expression significantly shortened the OS (HR = 1.43, 95%CI 1.18 to 1.73, log-rank p < 0.001) but not PFS in ovarian cancer (Fig. 5G, H).
In addition, we explored the relationship between FAM83A expression and clinical outcomes in 33 cancer types via GEPIA. We found that high expression of FAM83A was associated with both poor OS and DFS in KIRP, LUAD, PAAD. In CESC, KIRC, and PCPG, the higher FAM83A expression level yielded poorer OS but not associated with DFS. The prognostic value of FAM83A expression was not analyzed in KICH, LGG, and UVM due to the limited sample size. In the remaining cancer types, the expression level of FAM83A had no impact on OS and DFS, including ACC, BLCA, LUSC, etc. (Additional Fig. 1). Taken together, these results confirmed the prognostic value of FAM83A expression in several specific types of cancers, including LUAD.
FAM83A Expression with Poor Prognosis in Lung Cancer
We explored the correlation between the FAM83A expression level and clinical variables of lung cancer patients via Kaplan-Meier plotter databases (Table 1). The high level of FAM83A expression was associated with shorter OS and PPS in LUAD patients compared with the low expression level (OS: HR = 2.22, P < 0.001; PFS: HR = 2.01, P < 0.01) and female lung patients (OS: HR = 1.55, P < 0.05; PFS: HR = 2.70, P < 0.01). High expression of FAM83A was related to worse OS with stage I (HR = 1.48, P < 0.05), stage T1 (HR = 2.07, P < 0.001), stage N0 patients (HR = 1.61, P < 0.01). Moreover, FAM83A high expression was associated with worse PFS in stage 2 lung cancer cohorts (HR = 2.03, P < 0.05). FAM83A played a crucial role in the prognosis of LUAD, but not in LUSC, which was in line with the results of GEPIA analysis.
Table 1
Correlation of FAM83A mRNA expression and clinical prognosis with clinicopathological factors in lung cancer by Kaplan-Meier plotter.
Clinicopathological characteristics
|
Overall survival (n = 1927)
|
Post- progression survival (n = 344)
|
|
N
|
Hazard ratio
|
P-value
|
N
|
Hazard ratio
|
P-value
|
Gender
|
|
|
|
|
|
|
Female
|
714
|
1.55(1.10–2.18)
|
0.012
|
165
|
2.70(1.27–5.70)
|
0.0071
|
Male
|
1100
|
1.08(0.88–1.32)
|
0.45
|
179
|
1.14(0.66–1.95)
|
0.64
|
Smoking history
|
|
|
|
|
|
|
Smoked
|
820
|
1.91(1.26–2.89)
|
0.002
|
254
|
1.39(0.84–2.30)
|
0.2
|
Never smoked
|
205
|
4.99(1.70-14.63)
|
0.0012
|
67
|
1.37(0.57–3.32)
|
0.48
|
Histology
|
|
|
|
|
|
|
Adenocarcinoma
|
719
|
2.22(1.72–2.86)
|
3.30E-10
|
125
|
2.01(1.23–3.29)
|
0.0046
|
Squamous cell carcinoma
|
524
|
1.07(0.78–1.46)
|
0.67
|
20
|
0.30(0.08–1.09)
|
0.055
|
Stage
|
|
|
|
|
|
|
I
|
577
|
1.48(1.08–2.02)
|
0.014
|
78
|
1.71(0.93–3.14)
|
0.079
|
II
|
244
|
1.34(0.85–2.11)
|
0.2
|
58
|
2.03(1.01–4.07)
|
0.042
|
III
|
70
|
0.75(0.38–1.49)
|
0.41
|
10
|
*
|
*
|
IV
|
4
|
*
|
*
|
0
|
*
|
*
|
Stage T
|
|
|
|
|
|
|
1
|
437
|
2.07(1.38–3.11)
|
3.20E-04
|
61
|
1.25(0.21–7.53)
|
0.81
|
2
|
589
|
0.93(0.64–1.36)
|
0.71
|
169
|
1.63(0.78–3.40)
|
0.19
|
3
|
81
|
0.68(0.30–1.56)
|
0.36
|
17
|
*
|
*
|
4
|
46
|
0.99(0.42–2.31)
|
0.98
|
5
|
*
|
*
|
Stage N
|
|
|
|
|
|
|
0
|
781
|
1.61(1.18–2.21)
|
0.0028
|
146
|
1.81(0.80–4.09)
|
0.15
|
1
|
252
|
1.02(0.62–1.67)
|
0.95
|
71
|
2.43(0.70–8.37)
|
0.15
|
2
|
111
|
0.73(0.35–1.55)
|
0.42
|
0
|
*
|
*
|
Stage M
|
|
|
|
|
|
|
0
|
681
|
1.07(0.84–1.36)
|
0.59
|
59
|
1.82(0.93–3.56)
|
0.078
|
1
|
10
|
*
|
*
|
0
|
*
|
*
|
Chemotherapy
|
|
|
|
|
|
|
Yes
|
176
|
0.78(0.25–2.49)
|
0.68
|
88
|
1.85(0.46–7.41)
|
0.38
|
No
|
310
|
33.87(0.45–33.17)
|
0.18
|
97
|
0.29(0.02–4.65)
|
0.35
|
* Sample number too low for meaningful analysis. Bold values indicate P < 0.05. |
Multivariate Cox survival analyses of FAM83A mRNA expression with several clinicopathological factors in lung cancer and LUAD were shown in Additional Table 3, adjusting for gender, stage, American Joint Committee on Cancer (AJCC) stage T, AJCC stage N, and smoking history. FAM83A differential expression level and AJCC stage T were the independent prognostic factors for OS in lung cancer and LUAD patients.
Immune Cell Infiltration of FAM83A Level in Patients with Lung Cancer
To better understand the underlying mechanisms, we investigated the relationship between immune infiltration and FAM83A expression in 39 cancer types using data from TIMER. The results showed that the FAM83A expression level was significantly associated with tumor purity in 13 types of cancers and there were significant correlations with infiltrating levels of immune cells, including B cells, CD4+ T cells, CD8+ T cells, macrophages, neutrophils, and dendritic cells, in various types of tumors (Additional Fig. 2).
Furthermore, based on the differences of FAM83A mRNA expression levels and the prognostic value of FAM83A expression in tumors, we ultimately selected lung cancer and for further research on immune infiltration via TIMER (Fig. 6). FAM83A expression had a significantly negative correlation with infiltrating levels of B cell (r = -0.276, P < 0.001) and dendritic cell (r = -0.107, P < 0.05), but not with tumor purity and infiltrating levels of CD8+ T cell, CD4+ T cell, macrophage, and neutrophil in LUAD. While in LUSC, the FAM83A expression showed significantly negative correlations with tumor purity (r = -0.215, P < 0.001) and infiltrating levels of B cell (r = -0.287, P < 0.001) and CD8+ T cell (r = -0.141, P < 0.01), but it did not correlate with infiltrating levels of CD4+ T cell, macrophage, neutrophil, or dendritic cell.
Correlations Between FAM83A Expression and Immune Marker Sets
The potential correlations between FAM83A and immune cell markers of various infiltrating FAM83A expression and immune marker genes of innate and adaptive immune cells, included monocytes, TAMs, M1 and M2 macrophages, neutrophils, NK cells, DCs, CD8+ T cells, general T cells, B cells, as well as the different functional T cells were studied. FAM83A expression level significantly correlated with most of the immune marker sets in both LUSC and LUAD, after adjustment for purity (Table 2 and Table 3).
Table 2
Correlation analysis between FAM83A and relate genes and markers of innate immunity cells in TIMER.
Cell type
|
Gene
marker
|
LUAD
|
LUSC
|
Purity
|
None
|
Purity
|
None
|
Cor
|
P
|
Cor
|
P
|
Cor
|
P
|
Cor
|
P
|
Monocyte
|
CD14
|
0.052
|
2.46E-01
|
0.085
|
5.48E-02
|
0.104
|
*
|
0.017
|
7.10E-01
|
|
CD115
(CSF1R)
|
-0.056
|
2.12E-01
|
-0.018
|
6.79E-01
|
-0.131
|
**
|
-0.015
|
7.44E-01
|
TAM
|
CCL2
|
-0.052
|
2.46E-01
|
-0.028
|
5.28E-01
|
-0.158
|
***
|
-0.072
|
1.10E-01
|
M1 Macrophage
|
INOS
(NOS2)
|
0.082
|
6.83E-02
|
0.097
|
*
|
-0.158
|
***
|
-0.152
|
***
|
|
IRF5
|
0.08
|
7.59E-02
|
0.099
|
*
|
-0.137
|
**
|
-0.116
|
**
|
M2 Macrophage
|
CD206
(MRC1)
|
-0.139
|
**
|
-0.106
|
*
|
-0.061
|
1.86E-01
|
0.044
|
3.28E-01
|
|
CD163
|
0.064
|
1.59E-01
|
0.091
|
*
|
-0.117
|
*
|
-0.018
|
6.90E-01
|
|
VSIG4
|
-0.038
|
4.02E-01
|
-0.009
|
8.38E-01
|
-0.111
|
*
|
-0.017
|
7.04E-01
|
|
MS4A4A
|
-0.076
|
9.39E-02
|
-0.031
|
4.81E-01
|
-0.138
|
**
|
-0.034
|
4.47E-01
|
Neutrophils
|
CD11b
(ITGAM)
|
-0.07
|
1.23E-01
|
-0.036
|
4.16E-01
|
-0.152
|
***
|
-0.043
|
3.41E-01
|
|
CD15
(FUT4)
|
0.039
|
3.88E-01
|
0.042
|
3.42E-01
|
-0.145
|
**
|
-0.101
|
*
|
Natural killer cell
|
KIR2DL1
|
0.036
|
4.29E-01
|
0.044
|
3.16E-01
|
-0.037
|
4.14E-01
|
0.009
|
8.33E-01
|
|
KIR2DL3
|
0.083
|
6.70E-02
|
0.093
|
*
|
-0.059
|
2.01E-01
|
-0.035
|
4.36E-01
|
|
KIR3DL1
|
0.093
|
*
|
0.103
|
*
|
-0.128
|
**
|
-0.084
|
6.10E-02
|
|
KIR3DL2
|
0.056
|
2.13E-01
|
0.069
|
1.19E-01
|
-0.083
|
6.96E-02
|
-0.041
|
3.60E-01
|
Dendritic cell
|
BDCA-1 (CD1C)
|
-0.285
|
***
|
-0.252
|
***
|
-0.048
|
2.95E-01
|
0.067
|
1.32E-01
|
|
BDCA-4 (NRP1)
|
0.225
|
***
|
0.228
|
***
|
0.079
|
8.41E-02
|
0.142
|
**
|
|
HLA-DPB1
|
-0.334
|
***
|
-0.264
|
***
|
-0.184
|
***
|
-0.059
|
1.87E-01
|
|
HLA-DPA1
|
-0.3
|
***
|
-0.241
|
***
|
-0.191
|
***
|
-0.079
|
7.82E-02
|
LUAD, lung adenocarcinoma; LUSC, lung squamous cell carcinoma; TAM, tumor associated macrophage; Cor, R value of Spearman’s correlation; None, correlation without adjustment. Purity, correlation adjusted by purity. *P < 0.05, **P < 0.01, ***P < 0.001. |
Table 3
Correlation analysis between FAM83A and related genes and markers of adaptive immunity cells in TIMER.
Cell type
|
Gene
marker
|
LUAD
|
LUSC
|
Purity
|
None
|
Purity
|
None
|
Cor
|
P
|
Cor
|
P
|
Cor
|
P
|
Cor
|
P
|
CD8+T cell
|
CD8A
|
0.007
|
8.80E-01
|
0.045
|
3.09E-01
|
-0.225
|
***
|
-0.166
|
***
|
|
CD8B
|
-0.044
|
3.30E-01
|
-0.012
|
7.94E-01
|
-0.266
|
***
|
-0.218
|
***
|
|
CD45
(PTPRC)
|
-0.148
|
***
|
-0.092
|
8.68E-02
|
-0.246
|
***
|
-0.109
|
*
|
T cell (general)
|
CD3D
|
-0.057
|
2.07E-01
|
-0.002
|
9.66E-01
|
-0.221
|
***
|
-0.097
|
*
|
|
CD3E
|
-0.112
|
*
|
-0.043
|
3.31E-01
|
-0.228
|
***
|
-0.101
|
*
|
|
CD2
|
-0.14
|
**
|
-0.072
|
1.03E-01
|
-0.254
|
***
|
-0.132
|
**
|
B cell
|
CD19
|
-0.156
|
***
|
-0.097
|
*
|
-0.229
|
***
|
-0.088
|
5.00E-02
|
|
CD20
(MS4A1)
|
-0.22
|
***
|
-0.154
|
***
|
-0.26
|
***
|
-0.119
|
**
|
|
CD79A
|
-0.095
|
*
|
-0.046
|
2.94E-01
|
-0.235
|
***
|
-0.088
|
5.00E-02
|
Th1
|
T-bet
(TBX21)
|
-0.051
|
2.60E-01
|
-0.005
|
9.02E-01
|
-0.222
|
***
|
-0.112
|
*
|
|
STAT4
|
-0.064
|
1.57E-01
|
-0.013
|
7.64E-01
|
-0.066
|
1.51E-01
|
0.042
|
3.49E-01
|
|
STAT1
|
0.196
|
***
|
0.213
|
***
|
-0.117
|
*
|
-0.057
|
2.00E-01
|
Th2
|
GATA3
|
-0.083
|
6.49E-02
|
-0.041
|
3.58E-01
|
0.043
|
3.43E-01
|
0.091
|
*
|
|
STAT6
|
-0.037
|
4.14E-01
|
-0.04
|
3.70E-01
|
0.075
|
1.04E-01
|
0.081
|
6.96E-02
|
|
IL13
|
-0.102
|
*
|
-0.085
|
5.43E-02
|
-0.125
|
**
|
-0.182
|
***
|
Tfh
|
BCL6
|
0.11
|
*
|
0.117
|
**
|
-0.016
|
7.17E-01
|
0.016
|
7.21E-01
|
|
IL21
|
0.086
|
5.56E-02
|
0.101
|
2.18E-02
|
-0.169
|
***
|
-0.099
|
*
|
Th17
|
STAT3
|
0.102
|
*
|
0.094
|
*
|
-0.02
|
6.66E-01
|
0.013
|
7.71E-01
|
|
IL17A
|
0.044
|
3.27E-01
|
0.067
|
1.30E-01
|
-0.058
|
2.09E-01
|
-0.008
|
8.55E-01
|
Treg
|
FOXP3
|
-0.007
|
8.77E-01
|
0.035
|
4.23E-01
|
-0.18
|
***
|
-0.062
|
1.67E-01
|
|
CCR8
|
-0.005
|
9.18E-01
|
0.023
|
6.05E-01
|
-0.162
|
***
|
-0.061
|
1.71E-01
|
|
STAT5B
|
-0.057
|
2.07E-01
|
-0.059
|
1.81E-01
|
-0.289
|
***
|
-0.278
|
***
|
|
CD25
(IL2RA)
|
0.099
|
*
|
0.12
|
**
|
-0.187
|
***
|
-0.077
|
8.40E-02
|
T cell exhaustion
|
PD-1
(PDCD1)
|
0.058
|
1.97E-01
|
0.095
|
*
|
-0.231
|
***
|
-0.12
|
**
|
|
CTLA4
|
-0.034
|
4.57E-01
|
0.014
|
7.52E-01
|
-0.229
|
***
|
-0.105
|
*
|
|
LAG3
|
0.031
|
4.97E-01
|
0.055
|
2.12E-01
|
-0.233
|
***
|
-0.152
|
***
|
|
TIM-3
(HAVCR2)
|
-0.023
|
6.18E-01
|
0.022
|
6.18E-01
|
-0.172
|
***
|
-0.062
|
1.69E-01
|
|
GZMB
|
0.221
|
***
|
0.234
|
***
|
-0.172
|
***
|
-0.08
|
7.48E-02
|
LUAD, lung adenocarcinoma; LUSC, lung squamous cell carcinoma; Th, T helper cell; Tfh, Follicular helper T cell; Treg, regulatory T cell; Cor, R value of Spearman’s correlation; None, correlation without adjustment. Purity, correlation adjusted by purity. *P < 0.05, **P < 0.01, ***P < 0.001. |
We found that the FAM83A expression level significantly correlated to markers of B cells (CD19, CD20, CD79A), DCs (BDCA-1, BDCA-4, HLA-DPB1, HLA-DPA1), Th1 (STAT1), and Th17 (STAT3) in LUAD. The associations between FAM83A expression and the above markers of B cells and DCs in LUAD and LUSC were validated via GEPIA database (Additional Table 4). The FAM83A expression level positively correlated with CD274 (R = 0.18, P-value < 0.001), STAT1 (R = 0.18, P-value < 0.001), STAT3 (R = 0.1, P-value < 0.05), and JAK1 (R = 0.11, P-value < 0.05) (Fig. 7).