UBE2C Human

What is UBE2C and what is its primary function in human cells?

UBE2C (Ubiquitin-conjugating enzyme E2C) is a key member of the ubiquitin-conjugating enzyme (E2) family located in both the nucleus and cytoplasm. Its primary function involves catalyzing the 26S proteasome-mediated degradation of proteins into smaller peptides and amino acid subunits . UBE2C plays an essential role in cell cycle progression, particularly during mitosis, as mutation of its active site (Cys 114 Ser) inhibits the destruction of mitotic cyclins . The enzyme possesses the ability to receive ubiquitin from a Ubiquitin-Activating Enzyme (E1) and subsequently interacts with a Ubiquitin ligase (E3) to conjugate ubiquitin to substrate proteins . Through this mechanism, UBE2C regulates key cellular processes including transcription, apoptosis, and cell cycle progression .

How is UBE2C expression regulated throughout the cell cycle?

UBE2C expression exhibits distinct temporal regulation across the cell cycle. Research indicates that UBE2C levels are low during G1 phase, gradually accumulate throughout S phase, and reach peak expression during G2 phase. Once cells exit from mitosis, UBE2C levels decrease sharply . This dynamic expression pattern aligns with UBE2C's critical role in regulating mitotic processes and cell division. Understanding this temporal regulation is essential for researchers examining cell cycle-dependent processes and determining optimal timepoints for experimental interventions targeting UBE2C.

What subcellular localization patterns does UBE2C exhibit in human cells?

UBE2C demonstrates a dual localization pattern, being present in both the nucleus and cytoplasm of human cells . Immunofluorescence studies in thyroid carcinoma tissues have confirmed this distribution pattern, with specific subcellular localization potentially varying between normal and cancerous cells . The nuclear localization is particularly important given UBE2C's role in cell cycle progression and mitotic events. For researchers studying UBE2C, immunohistochemistry and immunofluorescence techniques have proven effective for examining the expression pattern and subcellular localization in both cell lines and patient tissue samples .

How does UBE2C expression differ between normal and cancerous tissues?

UBE2C shows significant differential expression between normal and cancerous tissues across multiple cancer types. Pan-cancer analyses demonstrate that UBE2C is highly expressed in tumor tissues in almost all cancer types compared to their normal counterparts . In thyroid carcinoma (THCA), both independent and paired sample analyses confirmed significantly higher UBE2C expression in tumor tissues than in normal thyroid tissue . Similarly, in cutaneous squamous cell carcinoma (cSCC), integrated analyses revealed consistent upregulation of UBE2C . In hepatocellular carcinoma (HCC), elevated UBE2C levels were confirmed through both TCGA database analysis and examination of clinical specimens . Most notably, studies in thyroid cancer found that UBE2C was "barely detectable in normal thyroid cells" while being among the genes most upregulated in thyroid cancer cells with aggressive phenotypes .

Which clinical parameters correlate with UBE2C expression in cancer patients?

In thyroid carcinoma, UBE2C expression correlates with several important clinical parameters:

High UBE2C expression was significantly associated with lymph node metastasis (N stage), advanced clinical stage, tumor recurrence, and poorer disease-free survival . In cutaneous squamous cell carcinoma, immunohistochemistry demonstrated that high UBE2C expression was associated with poorer tumor histological grade . Similar correlations between elevated UBE2C levels and unfavorable clinical outcomes have been observed in hepatocellular carcinoma and pancreatic cancer .

What is the prognostic value of UBE2C in human cancers?

UBE2C has demonstrated significant prognostic value across multiple cancer types. Univariate and multivariate analyses in thyroid carcinoma patients revealed:

Through which signaling pathways does UBE2C promote cancer progression?

Research has identified several key signaling pathways through which UBE2C promotes cancer progression:

• Notch Signaling Pathway: In hepatocellular carcinoma, UBE2C activates the Notch signaling pathway by upregulating N1ICD and Hes1, crucial components of this pathway . This activation was confirmed through RBP-JK luciferase reporter assays. Importantly, treatment with the Notch inhibitor DAPT eliminated the oncogenic effects of UBE2C, while N1ICD overexpression rescued the anticarcinogenic impact of UBE2C knockdown .

• EGFR Signaling: In pancreatic cancer, UBE2C binds to EGFR (Epidermal Growth Factor Receptor) and induces downstream signaling, promoting metastatic progression .

• Cell Cycle Regulation: Gene set enrichment analysis (GSEA) of UBE2C co-expressed genes indicates significant participation in cell cycle pathways . In thyroid carcinoma, UBE2C co-expressed genes were primarily involved in cell division processes and spindle formation .

• Immune-Related Pathways: High UBE2C expression is associated with upregulation of immune-related pathways in thyroid carcinoma , suggesting potential immunomodulatory effects.

Understanding these pathway interactions provides critical insights for researchers designing targeted therapeutic strategies against UBE2C-driven oncogenesis.

What functional gene sets are enriched in UBE2C-high cancer cells?

Gene Ontology (GO) and KEGG pathway analyses of UBE2C co-expressed genes in thyroid carcinoma revealed specific functional enrichments:

• Cellular Component (CC): Co-expressed genes were predominantly localized to the spindle .

• Biological Process (BP): The most significant biological process was cell division .

• Molecular Function (MF): The primary molecular function identified was tubule binding .

• KEGG Pathways: Co-expressed genes significantly participated in cell cycle and oocyte meiosis pathways , primarily involving cell growth and death processes.

Gene Set Enrichment Analysis (GSEA) further demonstrated that in UBE2C-high expression samples, cell growth and immune-related pathways were upregulated, while UBE2C-low expression correlated with metabolism-related pathways (including butanoate metabolism and beta-alanine metabolism) . These enrichment patterns provide valuable insights for researchers investigating the functional consequences of UBE2C dysregulation in cancer.

What are effective methods to detect and quantify UBE2C expression in clinical samples?

Multiple complementary approaches have proven effective for detecting and quantifying UBE2C expression in clinical samples:

• Quantitative RT-PCR: This technique has demonstrated superior detection efficiency for malignancy in thyroid fine-needle aspiration samples compared to immunohistochemistry . The high sensitivity of qRT-PCR makes it particularly valuable for detecting subtle expression differences or when working with limited sample material.

• Immunohistochemistry (IHC): This method allows visualization of UBE2C protein expression and localization within tissue sections. IHC has been successfully employed to examine UBE2C expression patterns in cutaneous squamous cell carcinoma , thyroid carcinoma , and other cancer types, enabling correlation with histological features.

• Immunofluorescence: This technique provides detailed subcellular localization information and has been used to confirm the dual nuclear and cytoplasmic distribution of UBE2C in cancer cells .

• Database Mining: Analysis of TCGA (The Cancer Genome Atlas) and GEO (Gene Expression Omnibus) repositories has proven valuable for investigating UBE2C expression patterns across large patient cohorts . The GEPIA database specifically has been utilized for mRNA expression analysis in pancreatic cancer research .

When designing UBE2C detection experiments, researchers should consider combining multiple detection methods to obtain comprehensive expression data at both mRNA and protein levels.

How can functional studies of UBE2C be designed in cancer models?

Effective functional studies of UBE2C in cancer models should incorporate multiple complementary approaches:

• Loss-of-function assays: UBE2C inhibition through siRNA, shRNA, or CRISPR/Cas9 systems has been successfully employed to investigate its role in cancer cell behavior . These approaches allow for targeted downregulation of UBE2C expression to assess its necessity in maintaining cancer phenotypes.

• Gain-of-function assays: Overexpression of UBE2C through transfection of expression vectors enables researchers to evaluate whether increased UBE2C levels are sufficient to induce malignant transformation or enhance aggressive phenotypes .

• Cellular phenotype assays:

  • Cell proliferation: CCK8 assays have been effectively used to assess UBE2C's impact on cancer cell growth .

  • Migration and invasion: Wound healing and Transwell assays provide insights into UBE2C's role in metastatic potential .

  • Apoptosis: Flow cytometry following UBE2C manipulation reveals its influence on cell survival mechanisms .

• Pathway analysis: Luciferase reporter assays (e.g., RBP-JK reporter for Notch signaling) can determine UBE2C's effects on specific signaling pathways .

• Rescue experiments: Combining UBE2C manipulation with pathway inhibitors (e.g., DAPT for Notch inhibition) or downstream effector overexpression (e.g., N1ICD) allows researchers to establish causal relationships between UBE2C and specific pathways .

For translational relevance, these in vitro findings should be validated in animal models to confirm UBE2C's role in tumor growth and metastasis in vivo.

How might UBE2C serve as a diagnostic or prognostic biomarker?

UBE2C demonstrates significant potential as both a diagnostic and prognostic biomarker across multiple cancer types:

For optimal clinical utility, researchers should develop standardized cut-off values for UBE2C expression and validate these thresholds in large, prospective clinical cohorts.

What therapeutic strategies targeting UBE2C are being developed?

While the search results don't explicitly detail specific UBE2C inhibitors in clinical development, several therapeutic approaches emerge from the mechanistic insights:

• Direct UBE2C inhibition: Research focusing on small molecule inhibitors targeting UBE2C's catalytic site (particularly Cys 114) could disrupt its ubiquitin-conjugating activity . The availability of recombinant UBE2C protein facilitates in vitro screening assays for such inhibitors .

• Pathway-mediated approaches: The established link between UBE2C and the Notch signaling pathway suggests that Notch inhibitors (like DAPT) might effectively counteract UBE2C-driven oncogenesis . Research demonstrated that DAPT treatment eliminated the oncogenic effects of UBE2C in hepatocellular carcinoma .

• Combination strategies: Given UBE2C's involvement in cell cycle regulation, combining UBE2C inhibition with existing chemotherapeutic agents targeting the cell cycle might yield synergistic effects. This approach could potentially address chemoresistance issues in cancers like pancreatic cancer .

• Gene therapy approaches: siRNA or shRNA-mediated knockdown of UBE2C has demonstrated anti-cancer effects in experimental models , suggesting potential for RNA interference-based therapeutic strategies.

Researchers pursuing UBE2C-targeted therapies should prioritize cancer types showing the strongest association between UBE2C overexpression and poor clinical outcomes, such as thyroid carcinoma, hepatocellular carcinoma, and pancreatic cancer.

How does UBE2C interact with the tumor microenvironment and immune system?

Gene Set Enrichment Analysis (GSEA) of UBE2C-high expression in thyroid carcinoma revealed upregulation of immune-related pathways , suggesting significant interactions between UBE2C and the tumor immune microenvironment. While the search results don't provide detailed mechanisms of these interactions, this finding opens several important research directions:

• Immune cell infiltration: Researchers should investigate whether UBE2C expression levels correlate with specific immune cell populations within tumors (T cells, macrophages, etc.).

• Immunomodulatory effects: Studies examining how UBE2C might influence cytokine production, immune checkpoint expression, or antigen presentation would provide valuable mechanistic insights.

• Immunotherapy response: Given the immune pathway enrichment in UBE2C-high tumors, exploring whether UBE2C expression predicts response to immunotherapies (e.g., checkpoint inhibitors) represents an important translational direction.

• Stromal interactions: Beyond immune cells, research examining UBE2C's effects on cancer-associated fibroblasts, endothelial cells, and extracellular matrix composition would provide a more comprehensive understanding of its role in shaping the tumor microenvironment.

These investigations would extend our understanding of UBE2C beyond its intrinsic cellular functions to its broader influence on the complex tumor ecosystem.

What technical challenges exist in studying UBE2C protein interactions and substrates?

Investigating UBE2C protein interactions and substrate specificity presents several technical challenges:

• Dynamic nature of ubiquitination: The transient nature of E2-substrate interactions makes them difficult to capture using standard protein-protein interaction techniques. Researchers should consider using crosslinking approaches or enzyme-dead mutants (e.g., Cys 114 Ser) to stabilize these interactions.

• Context-dependent activity: UBE2C likely has different substrates and interaction partners depending on cell type, cell cycle phase, and disease state. Synchronizing cells at specific cell cycle stages when studying UBE2C is therefore critical .

• Distinguishing direct from indirect effects: As UBE2C influences multiple signaling pathways (Notch, EGFR, etc.) , distinguishing its direct ubiquitination targets from downstream pathway effects requires careful experimental design, potentially utilizing ubiquitin remnant profiling (K-ε-GG) proteomics.

• Reconstitution of enzymatic activity: While recombinant UBE2C protein is available , reconstituting its full enzymatic activity in vitro requires appropriate E1 enzymes, E3 ligases, and physiological substrates. The search results note that "reaction conditions will need to be optimized for each specific application" with a recommended initial UBE2C concentration of 0.1-1 μM .

Addressing these challenges requires integrating multiple complementary approaches, including proteomics, biochemical assays, and cellular studies, to build a comprehensive understanding of UBE2C's interactome and substrate landscape.