The prognostic value and immunological role of SULF2 in adrenocortical carcinoma

Abstract

Background: Adrenocortical carcinoma (ACC) represents the rare urological epithelial cancer of urinary tract, which has a large mass and is usually diagnosed at the advanced stage, thus inducing the poor prognosis. As a result, early detection and diagnosis are more important for the prognosis rather than the treatment of ACC. There is evidence supporting the association of Sulfatase2 (SULF2) with bladder cancer. However, the relationships of SULF2 with the clinical features and immune infiltration of ACC remain unclear.

Methods: This work comprehensively investigated the different expression levels of SULF2 within ACC and its prognostic significance through various databases including Gene Expression Profiling Interaction Analysis (GEPIA), Tumor Immune Estimation Resource (TIMER), The Cancer Genome Atlas (TCGA), Gene Expression Omnibus (GEO), Kaplan-Meier (KM) plotter and UALCAN. Besides, SULF2 levels within different tumor and paraneoplastic tissues were examined based on Human Protein Atlas (HPA) and TIMER. Afterwards, this study identified differentially expressed genes (DEGs) in high-compared with low-SULF2-expression groups. To predict the possible interaction between SULF2 and its targets, a protein-protein interaction (PPI) network was constructed based on relevant data collected in STRING database. Besides, the SULF2 functional annotation was carried out, including Gene Ontology (GO), Kyoto Encyclopedia of Genes and Genomes (KEGG) and GSEA. In addition, gene mutation analysis was also performed based on the cBioPortal database. The relation of SULF2 with immune infiltration was analyzed from various aspects by using the resources of various databases including TIMER, TISIDB, and GEPIA, which was first reported in this work. Finally, R package was utilized to plot the receiver operating characteristic (ROC) curves of diagnosis, time-dependent survival, and the association of SULF2 with cancer stage and the nomogram model. Finally, CellMiner dataset was adopted for SULF2 correlation as well as drug sensitivity analysis.

Results: Relative to healthy people, SULF2 level markedly elevated within ACC tissues. Besides, SULF2 up-regulation significantly predicted the dismal prognostic outcome, which may be an important prognostic factor. Afterwards, the PPI network was constructed, and the possible link of SULF2 with the corresponding targets was predicted. Besides, up-regulated SULF2 expression was tightly related to immune regulation and tumor-infiltration immune cell (TIICs), including CD8⁺, CD4⁺ and mast cells. Finally, SULF2 expression was speculated to help determine the sensitivity of certain drugs.

Conclusions: SULF2 may offer a new therapeutic target for ACC patients and become an important potential prognostic biomarker.

Keywords: Adrenocortical carcinoma (ACC); Prognosis; Sulfatase2 (SULF2); Tumor immune regulation.

Fig. 1

Sulfatase2 (SULF2) expression levels in different human cancers. (A) Different expression level of SULF2 in normal human tissues from The Human Protein Atlas (HPA) database. (B) Immunohistochemical (IHC) staining of normal adrenal tissue SULF2 in a 71-year-old female from HPA database. (C) high expression SULF2 in different tumor types from Tumor Immune Estimation Resource (TIMER2.0) database (*p < 0.05, **p < 0.01, ***p < 0.001). (D) Increased SULF2 in Adrenocortical carcinoma (ACC) compared with normal tissues in Gene Expression Profiling Interaction Analysis (GEPIA). (E, F) SULF2 expression was higher in ACC than in the normal tissue in GSE14922 and GSE12368 (**p < 0.01). (G) The correlation analysis between SULF2 and PD1 mRNA level.

Fig. 2

Correlation between SULF2 expression level and clinicopathological parameters of Adrenocortical carcinoma through the UALCAN database. (A) Cancer stages (stage 1, 2, 3, 4). (B) Lymph node stage (N 0, 1). (C) Patient's gender (male and female). (D) TP53 mutation status (TP53-Mutant and TP53-NonMutant). S1, stage 1; S2, stage 2; S3, stage 3; S4, stage 4; ACC, adrenocortical carcinoma.

Fig. 3

Differentially expressed genes. (A) Volcanic plot of differentially expressed genes in the high-SULF2 expression group and the low-SULF2 expression group. (B) Gene Oncology and KEGG pathway. (C) Gene set enrichment analysis: KEGG_NEUROACTIVE_LIGAND_RECEPTOR_INTERACTION. (D) Gene set enrichment analysis: REACTOME_G_ALPHA_I_SIGALLING_EVENTS.

Fig. 4

Enrichment analysis of SULF2 in adrenocortical carcinoma. (A) SULF2-interaction proteins in ACC from STRING database. (B) The gene-gene network of SULF2 performed by GeneMANIA database. (C, D) The relevance between SULF2 and functional partner genes. (E) Gene Oncology. (F) KEGG pathway. (G) Gene set enrichment analysis (GSEA). ACC, adrenocortical carcinoma.

Fig. 5

Mutation feature of SULF2 in ACC from TCGA cohort based on the cBioPortal database. (A) The alteration frequency with mutation type of SULF2 in ACC samples from TCGA cohorts. (B) Mutation sites of SULF2 in ACC from TCGA cohort. (C) K-M survival analysis of OS with or without SULF2 alteration. (D) K-M survival analysis of disease-specific survival with or without SULF2 alteration. (E) K-M survival analysis of progress-free survival with or without SULF2 alteration. ACC, adrenocortical carcinoma. OS, overall survival.

Fig. 6

Correlation of SULF2 expression with immune infiltration in ACC. (A) Correlation between the expression of SULF2 and the abundance of TILs in ACC through TISIDB database. (B) Correlation of SULF2 expression with infiltration levels of TILs in ACC available at TIMER2.0 database. ACC, adrenocortical carcinoma. TILs, tumor-infiltrating lymphocytes.

Fig. 7

The correlation of SULF2 expression with immunomodulators in ACC. (A) Correlation between the expression of SULF2 and immune inhibitors through TISIDB database. (B) Correlation of SULF2 expression with immune stimulators in ACC available at TISIDB database. ACC, adrenocortical carcinoma.

Fig. 8

Correlation between SULF2 expression and chemokine and receptor in ACC. (A) Correlation between the expression of SULF2 and chemokine through TISIDB database. (B) Correlation of SULF2 expression with receptor in ACC available at TISIDB database. ACC, adrenocortical carcinoma.

Fig. 9

Nomogram and Cox hazard analysis of SULF2 in ACC. (A) Nomogram model, based on clinicopathologic factors to predict survival probability at 3-, and 5-years. (B) Nomogram model, integrating clinicopathologic factors and SULF2 level to predict survival probability at 2-, 3-, and 5-years. (C) Single-factor cox analysis of ACC. (D) Multivariate cox analysis of ACC.

Fig. 10

ROC analysis and Kaplan-Meier survival curves. (A) The ROC curve of diagnosis to distinguish tumor from normal tissue. (B) Time-dependent survival ROC curve analysis to predict 1-, 3- and 5-year survival rates. (C, D) The overall survival and disease-free survival curves comparing patients with high and low SULF2 expression in ACC.

Fig. 11

The relationship between SULF2 expression levels and drug sensitivity. (A–O) The correlation between SULF2 expression and Fludarabine, LY-2835219, Rapamycin, Everolimus, Midostaurin, DACARBAZINE, Idelalisib, IPI-145, Copanlisib, Abiraterone, 6-MERCAPTOPURINE, RAPAMYCIN, Cladribine, Raltitrexed and Irofulven.