1. The CFL1 expression level in different human cancers
By the Oncomine database usage, we speculated the CFL1 expression in human cancers and normal tissues. Figure 1A showed, CFL1 is higher in bladder, head and neck, lung, pancreatic, breast, ovarian, kidney, liver cancers, and leukemia, myeloma, lymphoma. The detailed p-value, fold change, and reference information of CFL1 expression in different cancers was listed in Supplemental Table 1.
We analyzed the CFL1 expression in tumor and normal tissues combining two databases, TCGA and GTEx. Figure 1B showed, the CFL1 expression levels in BLCA (bladder urothelial carcinoma), CHOL (cholangiocarcinoma), KIRP (kidney renal papillary cell carcinoma), KIRC (kidney renal clear cell carcinoma), HNSC (head and neck cancer), BRCA (breast invasive carcinoma), STAD (stomach adenocarcinoma), GBM (glioblastoma), LIHC (liver hepatocellular carcinoma), OV (ovarian serous cystadenocarcinoma), LUSC (lung squamous cell carcinoma), PAAD (pancreatic adenocarcinoma), and UCEC (uterine Corpus Endometrial Carcinoma) are higher than their peritumoral normal tissues (P < 0.001). On the contrary, CFL1 was significantly lower expressed in ACC (adrenocortical carcinoma), ESCA (esophageal carcinoma), LUAD (lung adenocarcinoma), LAML (acute myeloid leukemia), SKCM (skin cutaneous melanoma), and THCA (thyroid carcinoma) (P < 0.001). In addition, the CFL1 expression in CESC (cervical squamous cell carcinoma and endocervical adenocarcinoma), COAD (colon adenocarcinoma), LGG (low-grade glioma), READ (rectum adenocarcinoma), and UCS (uterine carcinosarcoma) were equal with adjusted normal tissues.
2. CFL1 prognostic potential in different cancer types
A relevant survival analysis on pan-cancer patients was done for assessing the CFL1 expression and prognosis correlation. It included overall survival (OS), progression-free interval (PFI), progression-free survival (PFS), and disease-specific survival (DSS). To evaluate the CFL1 and OS link in 33 tumor types, univariate cox regression had been utilized. As shown in Fig. 2A, the CFL1 high expression affects the survival of ACC (p = 0.000006), BLCA (p = 0.017), CESC (p = 0.014), HNSC (p = 0.036), KICH (p = 0.0016), LAML (p = 0.00005), LGG (p = 0.033), LIHC (p = 5.9*10− 8), LUAD (p = 1.8*10− 6), MESO (p = 0.000002), PAAD (p = 0.005), THYM (p = 0.037) and UVM (p = 0.013). The CFL1 high levels were related to a poor OS.
Between patients with ACC (F. 2B;p<0.0001), BLCA (F. 2C;p = 0.004), CESE (F. 2D;p<0.0001), HNSC (F. 2E;p = 0.00096), KICH (F. 2F;p = 0.0013), LAML (F. 2G;p<0.0001), LGG (F. 2H;p = 0.0051), LIHC (F. 2I;p<0.0001), LUAD (F. 2J;p<0.0001), MESO (F. 2K;p<0.0001), PAAD (F. 2L;p = 0.0025), UVW (F. 2N;p = 0.002), the Kaplan-Meier survival analysis showed, the patients who had high CFL1 levels, had poorer OS, yet patients with THYM (F. 2M;p = 0.018) and high CFL1 levels had longer OS. Considering the influence of non-tumor factors during follow-up, we analyzed in 33 tumors the connection between CFL1 expression and disease-specific survival (DS-S). The CFL1 high expression in tumor samples is correlated to prognosis, in ACC (p = 0.000022), BLCA(p = 0.012), BRCA(p = 0.044), CESC(p = 0.049), HNSC(p = 0.017), KICH(p = 0.0028), KIRC(p = 0.0016), KIRP(p = 0.00044), LIHC(p = 0.00051), LUAD(p = 0.00009), MESO(p = 0.00011), PAAD(p = 0.0081) and UVM(p = 0.01), as the univariate analysis showed. (F. 3A). The Kaplan-Meier analysis shows that patients with ACC(p<0.0001),BLCA(p<0.0001), BRCA(p = 0.025), CESE(p = 0.0021),HNSC(p = 0.00011), KICH(p = 0.00081),KIRP(p = 0.00051), LIHC(p = 0.018), LUAD(p = 0.00019), MESO(p = 0.0018), PAAD(p = 0.00071), UVM(p = 0.002), as shown from Fig. 3B-Figure3N.
Notably, Univariate Cox analysis revealed the prognostic impact of CFL1 in ACC(p = 6.4*10− 5), HNSC(p = 0.021), KICH(p = 0.01), KIRC(p = 0.0041), KIRP(p = 0.0071), LUAD(p = 0.026), LUSC(p = 0.021), MESO(p = 0.0063), PAAD(p = 0.0078), PCPG(p = 0.046), PRAD(p = 0.0038), TGTC(p = 0.008), UVM(p = 0.026) (Fig. 4A). The Kaplan-Meier analysis shows the same trend, CFL1 expression significantly impacts 13 type cancers in the analysis of PFI, including ACC (F. 4B; p<0.0001), HNSC (F. 4C; p<0.0001), KICH (F. 4D; p = 0.006), KIRC (F. 4E; p = 0.0028), KIRP (F. 4F; p = 0.0077), LUAD (F. 4G; p = 0.0037), LUSC (F. 4H; p = 0.0031), MESO (F. 4I; p = 0.0014), PAAD (F. 4J; p = 0.0034), PCPG (F. 4K; p = 0.035), PRAD (F. 4L; p<0.0001), TGCT (F. 4M; p = 0.063), UVM (F. 4N; p = 0.024).
The results gained using Cox regression analyses are presented as forest maps (F. 5A), which show a link between CFL1 expression, prognosis and patients’ survival with ACC (p = 0.0076), CESE (p = 0.042), CHOL (p = 0.023), KIRP (p = 0.038), MESO (p = 0.039), PRAD (p = 0.034). Higher CFL1 expression is significantly linked with increased DFI in ACC (F. 5B; p = 0.00051), CESC (F. 5C; p = 0.0049), CHOL (F. 5D; p = 0.011), ESCA (F. 5E; p = 0.019), KIRP (F. 5F; p = 0.006), MESO (F. 5G; p = 0.01) and PRAD (F. 5H; p = 0.00026).
3. CFL1 Expression and Immune Infiltration Level correlation in pan-cancers
In the cancer microenvironment, two main non-tumor components should be considered in tumor diagnosis and prognosis, the immune and stromal cells. Tumor infiltrating lymphocytes are white blood cells that enter the tumor in the bloodstream. The body initiates an immune response against tumors when there are a large number of tumors infiltrating lymphocytes. We assessed the CFL1 expression and the immune infiltration level within 32 cancers detected using TIMER (Table 1). There is a significant link between the CFL1 expression and CD4+ T cells infiltrating levels within 14 different cancers, CD8+ T cells within 10 different cancers, neutrophils within 14 different cancers, macrophages within 17 different cancers, B cell within 17 different cancers, and dendritic cells within 17 different cancers. KIRC, KIRP and LIHC are the three cancer types most related to CFL1 expression at the immune infiltration level (Fig. 6). In KIRC, CFL1 expression was positively related to B cell (r = 0.312, p = 1.87e− 13), CD4+T cell (r = 0.319, p = 5.22e− 14), CD8+T cell (r = 0.319, p = 5.22e− 14), Dendrific (r = 0.499, p = 1.02e− 34), Macrophage (r = 0.327, p = 1.01e− 14), Neutrophil (r = 0.355, p = 2.93e− 17). In KIRP, the level of CFL1 expression was positively related to B cell (r = 0.187, p = 0.00143), CD4+T cell (r = 0.203, p = 0.000532), CD8+T cell (r = 0.183, p = 0.00178), Dendrific (r = 0.369, p = 1.22e− 10), Macrophage (r = 0.176, p = 0.00262), Neutrophil (r = 0.266, p = 5.05e− 6). In LIHC, CFL1 expression was positively related to B cell (r = 0.454, p = 2.09e− 20), CD4+T cell (r = 0.419, p = 2.64e− 17), CD8+T cell (r = 0.385, p = 1.29e− 14), Dendrific (r = 0.498, p = 8e− 25), Macrophage (r = 0.504, p = 1.81e− 25), Neutrophil (r = 0.411, p = 1.14e− 16).
Table 1
Relationship between CFL1 expression and immune cell infiltration in pan-cancer
|
B cell
(P-value/cor)
|
CD4 T cell
(P-value/cor)
|
CD8 T cell
(P-value/cor)
|
Neutrophil
(P-value/cor)
|
Marcophage
(P-value/cor)
|
Dendritic
(P-value/cor)
|
ACC
|
***/0.496
|
0.015
|
-0.046
|
**/0.304
|
0.12
|
***/0.376
|
BLCA
|
-0.069
|
***/0.184
|
***/0.209
|
***/0.325
|
***/0.171
|
0.41
|
BRCA
|
*/0.077
|
0.041
|
**/-0.096
|
0.037
|
-0.059
|
**/0.095
|
CESC
|
-0.019
|
-0.004
|
-0.081
|
0.033
|
-0.036
|
0.083
|
CHOL
|
0.079
|
0.003
|
0.057
|
0.213
|
0.218
|
0.216
|
COAD
|
-0.065
|
0.017
|
-0.048
|
0.016
|
-0.019
|
0.004
|
DLBC
|
0.202
|
-0.249
|
-0.117
|
-0.009
|
0.067
|
-0.088
|
ESCA
|
*/-0.195
|
-0.034
|
-0.09
|
-0.05
|
*/-0.169
|
-0.066
|
GBM
|
-0.095
|
-0.09
|
-0.022
|
-0.118
|
***/-0.337
|
0.131
|
HNSC
|
***/-0.151
|
0.041
|
**/-0.118
|
***/0.165
|
*/0.089
|
0.078
|
KICH
|
**/0.355
|
0.215
|
0.233
|
-0.03
|
***/0.54
|
***/0.497
|
KICR
|
***/0.312
|
***/0.319
|
***/0.343
|
***/0.355
|
***/0.327
|
***/0.499
|
KIRP
|
**/0.187
|
***/0.203
|
**/0.183
|
***/0.266
|
***/0.176
|
***/0.369
|
LGG
|
*/0.096
|
***/0.159
|
-0.034
|
*/0.097
|
0.073
|
***/0.232
|
LIHC
|
***/0.454
|
***/0.419
|
***/0.358
|
***/0.411
|
***/0.504
|
***/0.498
|
LUAD
|
***/-0.222
|
0.025
|
-0.064
|
**/0.137
|
0.064
|
0.055
|
LUSC
|
*/-0.1
|
*/0.105
|
-0.061
|
*/0.107
|
0.016
|
*/0.1
|
MESO
|
0.211
|
**/0.326
|
0.086
|
-0.185
|
0.023
|
***/0.431
|
OV
|
0.048
|
*/0.133
|
-0.002
|
***/0.186
|
*/0.121
|
**/0.142
|
PAAD
|
0.137
|
0.109
|
0.016
|
0.145
|
0.003
|
***/0.26
|
PCPG
|
***/0.332
|
***/0.274
|
0.005
|
0.128
|
***/0.321
|
0.495
|
PRAD
|
-0.007
|
-0.088
|
*/-0.11
|
-0.052
|
*/-0.112
|
0.002
|
READ
|
-0.058
|
0.028
|
-0.104
|
-0.041
|
0.1
|
0.041
|
SARC
|
***/0.239
|
**/0.173
|
0.074
|
0.023
|
***/0.218
|
***/0.398
|
SKCM
|
0.032
|
0.036
|
-0.074
|
-0.034
|
-0.004
|
0.07
|
STAD
|
***/-0.311
|
***/-0.228
|
0.033
|
0.01
|
***/-0.183
|
0.012
|
TGCT
|
-0.071
|
0.023
|
-0.21
|
-0.013
|
0.005
|
-0.002
|
THCA
|
**/0.143
|
**/0.122
|
*/0.096
|
***/0.197
|
-0.003
|
***/0.204
|
THYM
|
***/0.628
|
***/0.769
|
***/0.49
|
***/-0.305
|
***/0.465
|
0.815
|
UCEC
|
-0.056
|
-0.039
|
0.018
|
***/0.155
|
**/-0.137
|
0.04
|
USC
|
0.206
|
0.174
|
-0.031
|
-0.016
|
-0.037
|
0.16
|
UVM
|
***/-0.479
|
0.106
|
0.186
|
***/-0.372
|
0.205
|
**/0.311
|
*p < 0.05,**p < 0.01, and***p < 0.001. |
The ESTIMATE algorithm uses the transcription profile of cancer patient samples to infer infiltrating immune cells and stromal cells. The BLCA, LIHC, THCA, LGG, KIRC, LAML, PCPG, SARC, KIRP, UVM and OV had a positive correlation with the Immune, Stromal, and ESTIMATE Scores (Table 2). The top three cancers with a significant correlation to CFL1 expression were KIRC, THCA, and BLCA (Stromal Score), KIRC, LIHC and LGG (Immune Score), and KIRC, THCA and BLCA (ESTIMATE score) (Fig. 7).
Table 2
ImmuneScore、StromalScore and ESTIMATEScore relate with CFL1 expression
|
ImmuneScore
(p-value/cox)
|
StromalScore
(p-value/cox)
|
ESTIMATEScore
(p-value/cox)
|
ACC
|
-0.086
|
-0.006
|
-0.045
|
BLCA
|
***/0.264
|
***/0.264
|
***/0.279
|
BRCA
|
***/0.125
|
-0.005
|
*/0.074
|
CESE
|
-0.037
|
0.078
|
0.016
|
CHOL
|
0.269
|
0.301
|
0.31
|
COAD
|
-0.035
|
0.019
|
-0.002
|
DLBC
|
-0.063
|
0.166
|
0.084
|
ESCA
|
-0.033
|
-0.117
|
-0.075
|
GBM
|
-0.132
|
-0.115
|
-0.12
|
HNSC
|
0.023
|
**/0.143
|
*/0.097
|
KICH
|
*/0.313
|
0.239
|
*/0.299
|
KIRC
|
***/0.271
|
***/0.387
|
***/0.368
|
KIRP
|
*/0.146
|
**/0.161
|
***/0.165
|
LAML
|
***/0.419
|
*/0.201
|
***/0.344
|
LGG
|
***/0.237
|
***/0.14
|
***/0.204
|
LIHC
|
***/0.304
|
***/0.179
|
***/0.204
|
LUAD
|
0.002
|
0.057
|
0.033
|
LUSC
|
-0.021
|
0.008
|
0.009
|
MESO
|
0.111
|
*/0.267
|
0.182
|
OV
|
**/0.153
|
**/0.155
|
**/0.167
|
PAAD
|
-0.002
|
0.027
|
0.014
|
PCPG
|
***/0.268
|
***/0.227
|
***/0.265
|
PRAD
|
0.011
|
-0.064
|
-0.022
|
READ
|
-0.073
|
0.103
|
0.031
|
SARC
|
***/0.319
|
**/0.16
|
***/0.276
|
SKCM
|
0.01
|
0.009
|
0.008
|
STAD
|
0.039
|
-0.064
|
-0.022
|
TGCT
|
0.012
|
***/0.321
|
*/0.174
|
THCA
|
***/0.227
|
***/0.296
|
***/0.265
|
THYM
|
***/0.355
|
***/-0.358
|
0.018
|
UCEC
|
-0.083
|
-0.043
|
0.069
|
UCS
|
0.161
|
0.024
|
0.083
|
UVM
|
***/0.46
|
***/0.497
|
***/0.489
|
*p < 0.05, **p < 0.01, and***p < 0.001. |
4. Relationship between Immune Marker Sets, TMB, and MSI with CFL1 expression in pan-cancer
To clarify the CFL1 and immunotherapy efficacy’s correlation, a CFL1 gene co-expression analysis was conducted. The analyzed 44 genes encoded Immune checkpoint proteins. Almost all genes involved in the immune system were co-expressed with CFL1 (Fig. 8A), and most of them had a positive correlation with CFL1 in different cancers, except COAD, DLBC, ESCA, GBM, HNSC, LUSC, PRAD, UCEC, STAD, READ, SKCM, UCS, TGCT, SARC, MESO, OV, and UVM (* p < 0.05, ** p < 0.01, *** p < 0.001).
The CFL1, tumor mutation burden (TMB), and microsatellite instability (MSI) correlation with immunotherapy sensitivity were assessed. The CFL1 expression and TMB were linked in 14 different cancers, including breast, colorectal, lung, kidney cancers, and glioma (Fig. 8B). In another six different cancers, CFL1 was negatively correlated with microsatellite instability in gliomas, while positively related with Melanoma, UCEC (Uterine Corpus Endometrial Carcinoma, kidney cancer and liver cancer (Fig. 8C).
5. Gene set enrichment analysis
We investigated the CFL1 expression’s biological role in tumor tissue. We conducted GSEA to analyze KEGG and HALLMARK pathways, as shown in Fig. 9. The result of KEGG indicates that CFL1 positively regulates TASTE Transduction, ABC Transporters, Nitrogen Metabolism and LINOLEIC Acid Metabolism. Then, the data of the HALLMARK pathway indicates that CFL1 positively regulates UV Response, PANCREAS Beta, Bile Acid Metabolism and KRAS Signaling. In contrast, CFL1 is predicated as a negative regulator of PYRIMIDINE METABOLISM, PATHOGENIC ESCHERICHIA COLQ_INFECTION and PROTEASOME by KEGG. Furthermore, CFL1 is also predicated negative regulator of GLYCOLYSIS, DNA REPAIR and MTORC1 SIGNALING.