Overexpression of SKA Complex Is Associated With Poor Prognosis in Gliomas

SKA1 promotes oncogenic properties in oral dysplasia and oral squamous cell carcinoma, and augments resistance to radiotherapy

Oral squamous cell carcinoma (OSCC) is a malignancy associated with high morbidity and mortality, yet treatment options are limited. In addition to genetic alterations, aberrant gene expression contributes to the pathology of malignant diseases. In the present study, we identified 629 genes consistently dysregulated between OSCC and normal oral mucosa across nine public gene expression datasets. Among them, mitosis-related genes were significantly enriched, including spindle and kinetochore-associated complex subunit 1 (SKA1), whose roles in OSCC had been studied only to a very limited extent. We show that SKA1 promoted proliferation and colony formation in 2D and 3D, shortened the duration of metaphase, and increased the migration of OSCC cell lines. In addition, high SKA1 expression enhanced radioresistance, a previously unknown effect of this gene, which was accompanied by a reduction of radiation-induced senescence. SKA1 was also upregulated in a subset of advanced oral premalignancies and promoted tumor-relevant properties in a corresponding cell line. Gene expression patterns evoked by SKA1 overexpression confirmed that this gene is able to advance properties required for both early and advanced stages of tumorigenesis. In summary, our data show that SKA1 contributes to malignant progression in OSCC and may be a useful marker of radioresistance in this disease.

Oncogenic role of SKA2 and its ceRNA network in hepatocellular carcinoma based on a comprehensive analysis

Background

Genetic alterations have important roles in cancer development and progression. SKA2 (spindle and kinetochore associated complex subunit 2) is a mitotic component that plays a critical role in maintaining the silence of the metaphase plate and spindle checkpoint. However, the exact role of SKA2 in hepatocellular carcinoma (HCC) remains unclear. The current study aimed to comprehensively identify the function of SKA2 in HCC.

Methods

We utilized various databases and bioinformatics tools, such as The Cancer Genome Atlas (TCGA), survminer package, Tumor Immune Estimation Resource (TIMER), cBioPortal website, clusterProfiler package, gene set enrichment analysis (GSEA), miRWalk, TargetScanHuman8.0, miRDB, DIANA and Cytoscape to identify the role of SKA2 in HCC.

Results

Our results showed that patients with HCC exhibited a high SKA2 expression. Further, the SKA2 high expression group had a worse overall survival (OS). And SKA2 was associated with tumor stage and the immune system. In addition, 188 co-expression genes of SKA2 participated in some processes including cell cycle, DNA replication and so on. The tumor had a lower hsa-miR-19b-1-5p and hsa-miR-378a-5p expression, and these two microRNAs (miRNAs) were also correlated with OS. SNHG14, SNHG15, and SPCA6P-AS were significantly negatively correlated with hsa-378a-5p, and these three long non-coding RNAs (lncRNAs) showed a positive correlation with SKA2 (P<0.05). SKA2 is a member of competing endogenous RNA (ceRNA). Moreover, it is related to SPACA6P-AS/hsa-miR-378a-5p/SKA2, SNHG14/hsa-miR-378a-5p/SKA2, and SNHG15/hsa-miR-378a-5p/SKA2, which play significant roles in tumor progression.

Conclusions

SKA2 is associated with OS, tumor stage, and immune infiltrating cells in HCC. Thus, we propose that SKA2 functions as a ceRNA and influences tumorigenesis. These findings lay the foundation for future research in the field of HCC.

UBE2C enhances temozolomide resistance by regulating the expression of p53 to induce aerobic glycolysis in glioma

UBE2C is overexpressed in gliomas, and its overexpression has been reported to be correlated with the drug resistance of gliomas to some extent. In this study, we explore the role of UBE2C in regulating temozolomide (TMZ) resistance in glioma and investigate the underlying mechanisms involved. Twenty normal brain tissues and 100 glioma tissues from 50 TMZ-resistant patients and 50 TMZ-sensitive patients are included in this study. TMZ-resistant cell lines are constructed to explore the role of UBE2C in regulating glioma cell viability and TMZ resistance. Our results show that both the mRNA and protein levels of UBE2C are significantly elevated in the brain tissues of glioma patients, especially in those of TMZ-resistant patients. Consistently, UBE2C expression is markedly upregulated in TMZ-resistant cell lines. Overexpression of UBE2C rescues glioma cells from TMZ-mediated apoptosis and enhances cell viability. In contrast, downregulation of UBE2C expression further enhances TMZ function, increases cell apoptosis and decreases cell viability. Mechanistically, UBE2C overexpression decreases p53 expression and enhances aerobic glycolysis level by increasing ATP level, lactate production, and glucose uptake. Downregulation of p53 level abolishes the role of UBE2C downregulation in inhibiting TMZ resistance and aerobic glycolysis in glioma cells. Moreover, an animal assay confirms that downregulation of UBE2C expression further suppresses tumor growth in the context of TMZ treatment. Collectively, this study reveals that downregulation of UBE2C expression enhances the sensitivity of glioma cells to TMZ by regulating the expression of p53 to inhibit aerobic glycolysis.

SKA3 Expression as a Prognostic Factor for Patients with Pancreatic Adenocarcinoma

The spindle and kinetochore-associated complex subunit 3 (SKA3) is a protein essential for proper chromosome segregation during mitosis and thus responsible for maintaining genome stability. Although its involvement in the pathogenesis of various cancer types has been reported, the potential clinicopathological significance of SKA3 in pancreatic ductal adenocarcinoma (PDAC) has not been fully elucidated. Therefore, this study aimed to assess clinicopathological associations and prognostic value of SKA3 in PDAC. For this purpose, in-house immunohistochemical analysis on tissue macroarrays (TMAs), as well as a bioinformatic examination using publicly available RNA-Seq dataset, were performed. It was demonstrated that SKA3 expression at both mRNA and protein levels was significantly elevated in PDAC compared to control tissues. Upregulated mRNA expression constituted an independent unfavorable prognostic factor for the overall survival of PDAC patients, whereas altered SKA3 protein levels were associated with significantly better clinical outcomes. The last observation was particularly clear in the early-stage tumors. These findings render SKA3 a promising prognostic biomarker for patients with pancreatic ductal adenocarcinoma. However, further studies are needed to confirm this conclusion.

Single-cell RNA sequencing reveals tumor heterogeneity, microenvironment, and drug-resistance mechanisms of recurrent glioblastoma

Glioblastomas are highly heterogeneous brain tumors. Despite the availability of standard treatment for glioblastoma multiforme (GBM), i.e., Stupp protocol, which involves surgical resection followed by radiotherapy and chemotherapy, glioblastoma remains refractory to treatment and recurrence is inevitable. Moreover, the biology of recurrent glioblastoma remains unclear. Increasing evidence has shown that intratumoral heterogeneity and the tumor microenvironment contribute to therapeutic resistance. However, the interaction between intracellular heterogeneity and drug resistance in recurrent GBMs remains controversial. The aim of this study was to map the transcriptome landscape of cancer cells and the tumor heterogeneity and tumor microenvironment in recurrent and drug-resistant GBMs at a single-cell resolution and further explore the mechanism of drug resistance of GBMs. We analyzed six tumor tissue samples from three patients with primary GBM and three patients with recurrent GBM in which recurrence and drug resistance developed after treatment with the standard Stupp protocol using single-cell RNA sequencing. Using unbiased clustering, nine major cell clusters were identified. Upregulation of the expression of stemness-related and cell-cycle-related genes was observed in recurrent GBM cells. Compared with the initial GBM tissues, recurrent GBM tissues showed a decreased proportion of microglia, consistent with previous reports. Finally, vascular endothelial growth factor A expression and the blood-brain barrier permeability were high, and the O⁶ -methylguanine DNA methyltransferase-related signaling pathway was activated in recurrent GBM. Our results delineate the single-cell map of recurrent glioblastoma, tumor heterogeneity, tumor microenvironment, and drug-resistance mechanisms, providing new insights into treatment strategies for recurrent glioblastomas.