SH2D4A downregulation due to loss of chromosome 8p is associated with poor prognosis and low T cell infiltration in colorectal cancer

BEX4 inhibits the progression of clear cell renal cell carcinoma by stabilizing SH2D4A, which is achieved by blocking SIRT2 activity

Clear cell renal cell carcinoma (ccRCC) is one of the most common malignancies. Recently, the role of brain-expressed X-linked 4 (BEX4) in cancer progression has received increasing attention. This study aimed to investigate the function of BEX4 in ccRCC and to reveal the underlying mechanisms. We first confirmed that BEX4 was significantly downregulated in ccRCC by bioinformatics analysis and that patients with low BEX4 expression tended to have prolonged overall survival time. Subsequently, we confirmed that BEX4 inhibited ccRCC cell proliferation in vitro and tumorigenesis in vivo through a series of cell function assays and the establishment of a nude mouse xenograft model, respectively. Mechanistically, we found that BEX4 positively regulates the expression of Src homology 2 domain-containing 4A (SH2D4A), an inhibitor of the NOTCH pathway, which further promoted the tumor-suppressive effects of BEX4. In addition, our study confirmed that the promoting effect of BEX4 on SH2D4A was achieved by inhibiting the deacetylase sirtuin 2 (SIRT2) activity. On this basis, we found that there was a competition between acetylation and ubiquitination modifications at the K69 site of SH2DA4 and that BEX4-induced upregulation of acetylation at the k69 site stabilizes SH2D4A protein expression by inhibiting ubiquitination at the same site. In addition, dual-luciferase assays showed that the transcriptional activity of BEX4 was positively regulated by activation transcription factor 3 (ATF3). Our study suggests that BEX4 plays a role in inhibiting tumor progression in ccRCC and maybe a new diagnostic and therapeutic target for ccRCC patients.

Bioinformatics analysis of SH2D4A in glioblastoma multiforme to evaluate immune features and predict prognosis

Background

Glioblastoma multiforme (GBM) is the most common and aggressive primary brain cancer in adults. This study aimed to obtain data on immune cell infiltration based on public datasets and to examine the prognostic significance of SH2 domain containing 4A (SH2D4A) for GBM.

Methods

SH2D4A expression in GBM was analyzed using a Tumor Immunity Estimation Resource (TIMER) 2.0 dataset, and a gene expression profile interaction analysis (GEPIA), and the results were validated by quantitative reverse transcription polymerase chain reaction (qRT-PCR). The Chinese Glioma Genome Atlas (CGGA) dataset was used to assess the effect of SH2D4A on GBM patient survival. The SH2D4A co-expression network of the LinkedOmics dataset and GeneMANIA dataset was also investigated. Least absolute shrinkage and selection operator (LASSO) regression models and a nomogram were constructed to assess the prognosis of GBM patients. A Gene Set Enrichment Analysis (GSEA) was performed using The Cancer Genome Atlas (TCGA) dataset to find functional differences. The relationship between SH2D4A expression and tumor-infiltrating immune cells was analyzed using xCELL, the Cell Type Identification by Estimating Relative Subsets of RNA Transcripts (CIBERSORT) algorithm, and the TIMER dataset.

Results

We discovered that SH2D4A expression was upregulated in GBM patients, and elevated SH2D4A expression was also substantially correlated with tumor grade. The survival curve analysis and multivariate Cox regression analysis showed that high SH2D4A expression was a significant independent predictor of poor overall survival (OS) in GBM patients. The immunoassay results suggested that altered SH2D4A expression may affect the immune infiltration of GBM tissues and thus the survival outcomes of GBM patients.

Conclusions

In addition to being a possible prognostic marker and therapeutic target for GBM, SH2D4A may also accelerate the progression of GBM.

SH2D4A inhibits esophageal squamous cell carcinoma progression through FAK/PI3K/AKT signaling pathway

Esophageal squamous cell carcinoma (ESCC), one of the most common malignant tumors, is now afflicting approximately 80% of patients diagnosed with esophageal cancers. The therapeutic effect and prognosis of ESCC remain inadequate due to the unusual early symptoms and rapid malignant progression. SH2 Domain containing 4 A (SH2D4A) is downregulated in malignancies and is closely associated with tumor progression. However, neither the biological functions nor the fundamental mechanisms of SH2D4A on ESCC are known. In this study, it was found that SH2D4A is downregulated in ESCC tissues and cell lines. Incorporating immunohistochemistry and clinicopathological findings, we determined that decreased SH2D4A expression was substantially associated with adverse clinical outcomes. Overexpression of SH2D4A inhibited cell proliferation and migration, whereas suppressing SH2D4A has the opposite effect. SH2D4A mechanistically inhibited cells from proliferating and migrating through the FAK/PI3K/AKT signaling pathway. Furthermore, the results of xenograft tumor growth confirmed the preceding findings. In conclusion, our findings reveal that SH2D4A is a gene which can serve as a cancer suppressor in ESCC and may inhibits the ESCC progression by interfering with the FAK/PI3K/AKT signaling pathway. SH2D4A could act as a target for diagnostic or therapeutic purpose in ESCC.

SH2D4A promotes centrosome maturation to support spindle microtubule formation and mitotic progression

Mitotic progression requires the precise formation of spindle microtubules based on mature centrosomes. During the G2/M transition, centrosome maturation progresses, and associated microtubules bundle to form mitotic spindle fibers and capture the chromosomes for alignment at the cell equator. Mitotic kinases-induced phosphorylation signaling is necessary for these processes. Here, we identified SH2 domain-containing protein 4A (SH2D4A/PPP1R38) as a new mitotic regulator. SH2D4A knockdown delays mitotic progression. The time-lapse imaging analysis showed that SH2D4A specifically contributes to the alignment of chromosomes. The cold treatment assay and microtubule regrowth assay indicated that SH2D4A promotes microtubule nucleation to support kinetochore-microtubule attachment. This may be due to the centrosome maturation by SH2D4A via centrosomal recruitment of pericentriolar material (PCM) such as cep192, γ-tubulin, and PLK1. SH2D4A was found to be a negative regulator of PP1 phosphatase. Consistently, treatment with a PP1 inhibitor rescues SH2D4A-knockdown-induced phenotypes, including the microtubule nucleation and centrosomal recruitment of active PLK1. These results suggest that SH2D4A is involved in PCM recruitment to centrosomes and centrosome maturation through attenuation of PP1 phosphatases, accelerating the spindle formation and supporting mitotic progression.