Prognostic and immunological role of alpha-L-fucosidase 2 (FUCA2) in hepatocellular carcinoma.

Background: This study investigated the prognostic and immunological significance of alpha-L-fucosidase 2 (FUCA2) in hepatocellular cancer (HCC). Methods: The expression of FUCA2 and its clinical and prognostic values were explored across several databases, namely the University of Alabama Cancer Database, The Cancer Genome Atlas, Gene Expression Profiling Interactive Analysis, and the Human Protein Atlas. The prognostic relevance of FUCA2 was investigated using Kaplan-Meier curves, nomograms, and Cox analysis. The "limma" package in R was used to identify differentially expressed genes between high and low FUCA2 expression. A protein interaction network was established using the Search Tool for the Retrieval of Interacting Genes (STRING), whereas hub genes and clustering modules were identified using Cytoscape. "clusterProfiler", an R package, was used to examine the potential function of FUCA2. Using gene set enrichment analysis, signaling pathways associated with FUCA2 expression were identified. Cell-type Identification by Estimating Relative Subsets of RNA Transcripts (CIBERSORT), Tumor Immune Estimation Resource (TIMER) 2.0, and Tumor and Immune System Interaction Database (TISIDB) were used to examine immune infiltration and FUCA2 in HCC. Results: Many datasets indicated that FUCA2 expression is higher in HCC, and that this is related to age and overall survival (OS). With the cutoff value of 50% as the dividing threshold, the patients were divided into a high-FUCA2 expression group (n=167) and a low-FUCA2 expression group (n=168). High levels of FUCA2 expression coincided with decreased OS. FUCA2 expression in HCC was associated with immune infiltrates. The functional mechanisms of FUCA2 depend on signal release, extracellular matrix collagen, and neuroactive ligands and receptors. Conclusions: In HCC, increased FUCA2 expression is associated with a poor prognosis and immune infiltration. FUCA2 may serve as an immunological and predictive biomarker for HCC.

Cancer-associated adipocytes release FUCA2 to promote aggressiveness in TNBC.

Cancer-associated adipocytes (CAAs) have been suggested to promote tumor progression. Yet, the role of CAAs in triple-negative breast cancer (TNBC) is poorly investigated. We compared the expression of secretory protein-encoding genes in CAAs and control adipocytes. The effect of key secretory protein(s) on TNBC cell behaviors was explored. CAAs expressed and secreted FUCA2 at greater levels than control adipocytes. When FUCA2 activity was blocked with a neutralizing antibody, TNBC cell proliferation and migration induced by CAA-conditioned medium was impaired. In contrast, supplement of exogenous FUCA2 protein reinforced the proliferation, colony formation, and migration of TNBC cells. In vivo studies confirmed that FUCA2 exposure enhanced tumorigenesis and metastasis of TNBC cells. Mechanistic investigation revealed that FUCA2 induced TNBC aggressiveness through TM9SF3-dependent signaling. Depletion of TM9SF3 blocked CAA- and FUCA2-induced TNBC cell proliferation and migration. Compared to adjacent breast tissues, TNBC tissues had increased expression of TM9SF3. Moreover, high TM9SF3 expression was associated with advanced TNM stage, lymph node metastasis, and shorter overall survival of TNBC patients. Altogether, CAAs secrete FUCA2 to promote TNBC growth and metastasis through interaction with TM9SF3. Inhibition of TM9SF3 may represent a potential therapeutic strategy in the treatment of TNBC.

FUCA2 Is a Prognostic Biomarker and Correlated With an Immunosuppressive Microenvironment in Pan-Cancer.

Background: The expression of Fucosidase, alpha-L-2 (FUCA2) varies across tumors. However, its role in various tumor types and relationship with the tumor immune microenvironment (TIME) is poorly defined. Methods: We analyzed profiles of FUCA2 expression using datasets from The Cancer Genome Atlas (TCGA) and Genotype-Tissue Expression (GTEx) databases. Next, gene alteration, clinical characteristics and prognostic values of FUCA2 were elucidated based on TCGA pan-cancer data. This was followed by gene set enrichment analysis by R software. Relationships between FUCA2 expression and immune infiltration and immune-related genes were also evaluated. Moreover, the association of immune cell infiltration with FUCA2 expression was evaluated across three different sources of immune cell infiltration data, namely the TIMER online, ImmuCellAI databases, as well as a published study. In addition, MTT assays was also conducted to validate the oncogene role of FUCA2 in lung cancer cells. Results: FUCA2 was upregulated in most tumors, and this was significantly associated with poor survival rates. Gene set enrichment analysis uncovered that FUCA2 correlated with immune pathways in different tumor types. FUCA2 expression was positively related to tumor associated macrophages (TAMs), especially M2-like TAMs. Moreover, FUCA2 level showed a positive relationship with most immunosuppression genes, including programmed death-ligand 1 (PD-L1), transforming growth factor beta 1 (TGFB1), and interleukin-10 (IL10) in most cancer types. FUCA2 knockdown inhibited the cell viability in lung cancer cells. Conclusions: Our study reveals that FUCA2 is a potential oncogene and is indicative biomarker of a worse prognosis in pan-cancer. High FUCA2 expression may contribute to increased infiltration of TAMs and associates with an immunosuppressive microenvironment, providing a potential target for tumor therapy.