Pan-Cancer Analysis of AHSA1 Expression
We first evaluated AHSA1 expression using RNA sequence data combined with TCGA and GTEx expression profilers. The results revealed that AHSA1 was overexpressed in 27 cancer types, including ACC (Adrenocortical carcinoma), BLCA (Bladder Urothelial Carcinoma), BRCA (Breast invasive carcinoma), CESC (Cervical squamous cell carcinoma and endocervical adenocarcinoma), CHOL (Cholangiocarcinoma), COAD (Colon adenocarcinoma), DLBC (Lymphoid Neoplasm Diffuse Large B-cell Lymphoma), ESCA (Esophageal carcinoma), GBM (Glioblastoma multiforme), HNSC (Head and Neck squamous cell carcinoma), KICH (Kidney Chromophobe), KIRP (Kidney renal papillary cell carcinoma), LGG (Brain Lower Grade Glioma), LIHC (Liver hepatocellular carcinoma), LUAD (Lung adenocarcinoma), LUSC (Lung squamous cell carcinoma), OV (Ovarian serous cystadenocarcinoma), PAAD (Pancreatic adenocarcinoma), PRAD (Prostate adenocarcinoma), READ (Rectum adenocarcinoma), SKCM (Skin Cutaneous Melanoma), STAD (Stomach adenocarcinoma), TGCT (Testicular Germ Cell Tumor), THCA (Thyroid carcinoma), THYM (Thymoma), UCEC (Uterine Corpus Endometrial Carcinoma), and UCS (Uterine Carcinosarcoma). In comparison, low AHSA1 expression was observed in only 2 cancer types, KIRC (Kidney renal clear cell carcinoma) and LAML (Acute Myeloid Leukemia) (Fig. 1a). In tumor tissues derived from TCGA, AHSA1 expression was highest in TGCT and lowest in KIRC (Fig. 1b). In normal tissues from GTEx, the highest AHSA1 expression was detected in the testis, with the lowest observed in the pancreas (Fig. 1c).
For paired tumors and normal tissues from TCGA cohort, AHSA1 was highly expressed in BLCA, BRCA, CHOL, COAD, ESCA, HNSC, LIHC, LUAD, LUSC, PAAD, READ, and STAD, while low expression was observed in KIRC (Fig. 2a–m). We further assessed AHSA1 expression in different WHO tumor classifications. We observed that AHSA1 expression was higher in markedly malignant stages of BLCA, ESCA, HNSC, LIHC, LUAD, LUSC, KIRC, and KIRP (Fig. 3a–h). Furthermore, we evaluated the AHSA1 protein levels using the Ualcan database. The results revealed that AHSA1 level was higher in breast cancer, colon cancer, ovarian cancer, and UCEC, but lower in KIRC (Fig. 3i).
Genetic Alteration of AHSA1
Genetic and epigenetic alterations induce changes in gene expression. We explored genetic alterations in AHSA1 using cBioPortal and observed that patients with high AHSA1 expression presented gene alterations in uterine and cervical cancers, as well as DLBC (Fig. 4a). Copy number values were positively correlated with AHSA1 expression (Fig. 4b). In addition, the methylation level of the AHSA1 promoter was negatively correlated with AHSA1 expression (Fig. 4c). These results suggest that high copy number values and low methylation levels contribute to the high expression of AHSA1 observed in pan-cancer analysis.
Prognostic Significance of AHSA1
To evaluate the significance of AHSA1 in predicting the prognosis of patients with tumors, we performed univariate Cox regression analysis and Kaplan-Meier survival analysis using TCGA pan-cancer data. Results of the univariate Cox regression analysis indicate that AHSA1 is a risk factor for patients with ACC, HNSC, KIRP, LIHC, LUAD, MESO, PRAD, and UVM and a protective factor in LGG and OV (Fig. 5a). Kaplan-Meier survival analysis revealed that high AHSA1 expression predicted worse overall survival of patients with ACC, HNSC, KIRP, LIHC, LUAD, and UVM (Fig. 5b). We further assessed the significance of AHSA1 in predicting the disease-free interval (DFI), progression-free interval (PFI), and disease-specific survival (DSS) in patients with tumors, using univariate Cox regression analysis. DFI analysis revealed that AHSA1 acts as a risk factor for ACC, KIRP, LIHC, LUAD, and MESO and a protective factor for OV (Fig. 6a). PFI analysis revealed that AHSA1 acts as a risk factor in ACC, BLCA, ESCA, HNSC, KIRP, LIHC, LUAD, PRAD, and UVM, while serving as a protective factor in LGG, OV, and STAD (Fig. 6b). Finally, the DSS analysis showed that AHSA1 acts as a risk factor in ACC, ESCA, HNSC, KIRP, LIHC, LUAD, LUSC, MESO, and UVM and a protective factor in LGG and OV (Fig. 6c).
Enrichment Analysis of AHSA1
To predict the functions of AHSA1, we performed GSEA using TCGA pan-cancer data. The results suggested that AHSA1 was significantly associated with cell cycle-related and immune regulation-related pathways in ACC, HNSC, KIRP, LIHC, LUAD, and UVM (Fig. 7a–f). For example, AHSA1 was predicted to be involved in pathways such as “Cell Cycle,” “Cell Cycle, Mitotic,” “Adaptive Immune System,” and “Innate Immune System” (Fig. 7d). These results suggest that AHSA1 is strongly associated with tumor cell cycle arrest and tumor immune microenvironment regulation.
Tumor Immune Microenvironment Analysis
We further downloaded the immune cell infiltration score of TCGA pan-cancer from a previously published article [6]. We divided each tumor into two groups according to the median expression of AHSA1 to compare possible differences in immune cell infiltration. We observed that macrophage infiltration levels were significantly higher in the high AHSA1 expression groups of BRCA, CESC, HNSC, KIRC, LIHC, SKCM, and STAD. Simultaneously, the number of CD8 + T cells were lower in the high AHSA1 expression groups of these tumor types (Fig. 8a–g). These results suggest that high AHSA1 expression is associated with the tumor suppressor microenvironment.