Association of mRNA expression levels of Cullin family members with prognosis in breast cancer: An online database analysis

Association of CUL4B with the pathogenesis of age-related cataract

PURPOSE

Age-related cataract (ARC) is the most common cause of visual impairment and blindness in older adults. However, the role of CUL4B in the ARC remains unclear. Therefore, we investigated CUL4B expression and its effects on apoptosis.

MATERIALS AND METHODS

CUL4B expression levels were detected by a quantitative real-time polymerase chain reaction from the anterior lens capsules of patients with ARC and HLE-B3 cells treated with different concentrations of H2O2. CUL4B expression was silenced by siRNA transfection to evaluate apoptosis. CUL4B and apoptotic proteins B cell lymphoma 2 (Bcl-2), myeloid cell leukemia 1 (Mcl-1), caspase-3, cleaved caspase-3, Bax, Bak, and Bid were assessed using western blot analysis. Apoptosis was monitored using the TUNEL assay.

RESULTS

CUL4B expression was downregulated in the anterior lens capsules (P < 0.0001) and H2O2-treated HLE-B3 cells (P = 0.0405). CUL4B protein levels were significantly lower in 100 µmol/L (P = 0.0012) and 200 µmol/L (P = 0.0041) H2O2-treated HLE-B3 cells than in the untreated cells. CUL4B expression was significantly knocked down at the mRNA (P = 0.0043) and protein levels (P = 0.0002) in HLE-B3 cells. Bcl-2 (P = 0.0199), Mcl-1 (P = 0.0042), and caspase-3 (P = 0.0142) were significantly downregulated, whereas cleaved caspase-3 (P = 0.0089) and Bak (P = 0.009) were significantly upregulated in the knockdown group. The TUNEL assay showed a greater induction of apoptosis.

CONCLUSIONS

CUL4B downregulation promotes the apoptosis of lens epithelial cells. Our study may help in understanding the role of CUL4B in ARC pathogenesis.

Bioinformatics Analysis of the Prognostic Significance of CAND1 in ERα-Positive Breast Cancer

The identification of novel prognostic biomarkers for breast cancer is an unmet clinical need. Cullin-associated and neddylation-dissociated 1 (CAND1) has been implicated in mediating carcinogenesis in prostate and lung cancers. In addition, CAND1 is an established prognostic biomarker for worse prognosis in liver cancer. However, the prognostic significance of CAND1 in breast cancer has not yet been explored. In this study, Breast Cancer Gene-Expression Miner (Bc-GenExMiner) and TIMER2.0 were utilized to explore the mRNA expression of CAND1 in ERα-positive breast cancer patients. The Kaplan–Meier plotter was used to explore the relationship between CAND1 expression and several prognostic indicators. The Gene Set Cancer Analysis (GSCA) web server was then used to explore the pathways of the genes that correlate with CAND1 in ERα-positive breast cancer. Immune infiltration was investigated using Bc-GenExMiner. Our bioinformatics analysis illustrates that breast cancer patients have higher CAND1 compared to normal breast tissue and that ERα-positive breast cancer patients with a high expression of CAND1 have poor overall survival (OS), distant metastasis-free survival (DMFS), and relapse-free survival (RFS) outcomes. Higher CAND1 expression was observed in histologic grade 3 compared to grades 2 and 1. Our results revealed that CAND1 positively correlates with lymph nodes and negatively correlates with the infiltration of immune cells, which is in agreement with published reports. Our findings suggest that CAND1 might mediate invasion and metastasis in ERα-positive breast cancer, possibly through the activation of estrogen and androgen signaling pathways; however, experiments should be carried out to further explore the role of CAND1 in activating the androgen and estrogen signaling pathways. In conclusion, the results suggest that CAND1 could be used as a potential novel biomarker for worse prognosis in ERα-positive breast cancer.

MicroRNA-574-3p Regulates HIF-α Isoforms Promoting Gastric Cancer Epithelial-Mesenchymal Transition via Targeting CUL2

BACKGROUND

Gastric cancer (GC) is the third leading cause of cancer-related deaths worldwide. MicroRNAs (miRNAs) have been widely validated as potential biomarkers for cancer treatment and diagnosis.

AIMS

This paper intends to study the effect and specific mechanism of miR-574-3p/CUL2 axis in GC.

METHODS

The miR-574-3p expression in GC tissues and cell lines was analyzed by reverse transcription polymerase chain reaction (RT-PCR). GC cell (N87) proliferation, migration and invasion were determined by the Brdu assay and Transwell assay, respectively. The tumor xenotransplantation model was established in vivo to test the effect of miR-574-3p or Cullin 2 (CUL2) on tumor growth. The relationship between miR-574-3p and CUL2 was predicated by bioinformatic analysis and verified by dual-luciferase reporter assay and RIP experiment. The expression of CUL2, hypoxia-induced transcription factor-1α (HIF-1α) as well as E-cadherin, Snail and Vimentin was monitored by western blot and immunohistochemistry.

RESULTS

miR-574-3p was overexpressed in GC tissues and cells. Forced upregulation of miR-574-3p enhanced proliferation, migration, invasion and epithelial-mesenchymal transition (EMT) of GC cells (N87), while downregulation of miR-574-3p resulted in reverse effects. Additionally, miR-574-3p promoted N87 cells growth and EMT in vivo. CUL2 was negatively regulated by miR-574-3p in N87 cells, and upregulation of CUL2 repressed the malignant behaviors of N87 cells. Moreover, CUL2 directly interacted with HIF-1α and suppressed HIF-1α expression both in vitro and in vivo.

CONCLUSIONS

miR-574-3p targeted CUL2 to upregulate HIF-1α, thus facilitating the progression of GC.

Exploring the potential biomarkers for prognosis of glioblastoma via weighted gene co-expression network analysis

BACKGROUND

Glioblastoma (GBM) is the most common malignant tumor in the central system with a poor prognosis. Due to the complexity of its molecular mechanism, the recurrence rate and mortality rate of GBM patients are still high. Therefore, there is an urgent need to screen GBM biomarkers to prove the therapeutic effect and improve the prognosis.

RESULTS

We extracted data from GBM patients from the Gene Expression Integration Database (GEO), analyzed differentially expressed genes in GEO and identified key modules by weighted gene co-expression network analysis (WGCNA). GSE145128 data was obtained from the GEO database, and the darkturquoise module was determined to be the most relevant to the GBM prognosis by WGCNA (r =  - 0.62, p = 0.01). We performed enrichment analysis of Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) to reveal the interaction activity in the selected modules. Then Kaplan-Meier survival curve analysis was used to extract genes closely related to GBM prognosis. We used Kaplan-Meier survival curves to analyze the 139 genes in the darkturquoise module, identified four genes (DARS/GDI2/P4HA2/TRUB1) associated with prognostic GBM. Low expression of DARS/GDI2/TRUB1 and high expression of P4HA2 had a poor prognosis. Finally, we used tumor genome map (TCGA) data, verified the characteristics of hub genes through Co-expression analysis, Drug sensitivity analysis, TIMER database analysis and GSVA analysis. We downloaded the data of GBM from the TCGA database, the results of co-expression analysis showed that DARS/GDI2/P4HA2/TRUB1 could regulate the development of GBM by affecting genes such as CDC73/CDC123/B4GALT1/CUL2. Drug sensitivity analysis showed that genes are involved in many classic Cancer-related pathways including TSC/mTOR, RAS/MAPK.TIMER database analysis showed DARS expression is positively correlated with tumor purity (cor = 0.125, p = 1.07e-02)), P4HA2 expression is negatively correlated with tumor purity (cor =-0.279, p = 6.06e-09). Finally, GSVA analysis found that DARS/GDI2/P4HA2/TRUB1 gene sets are closely related to the occurrence of cancer.

CONCLUSION

We used two public databases to identify four valuable biomarkers for GBM prognosis, namely DARS/GDI2/P4HA2/TRUB1, which have potential clinical application value and can be used as prognostic markers for GBM.

Cullin-5 (CUL5) as a potential prognostic marker in a pan-cancer analysis of human tumors

There is some evidence supporting an association between Cullin-5 (CUL5) and cancer, but no research using pan-cancer analysis has been conducted previously. We therefore investigated the oncogenic role of CUL5 in 33 tumors from the Gene Expression Omnibus and The Cancer Genome Atlas databases. Many cancers reduce CUL5 levels, and the prognosis of certain cancers is vitally linked with CUL5 expression. CUL5 expression is associated with CD8 + T-cell infiltration levels in uveal melanomas and head and neck squamous cell carcinomas, and we observed a positive relationship between CUL5 and Tcm (T central memory) cells, and a negative relationship between T helper (Th) cells and pDC (plasmacytoid DC). CUL5 had negative associations with NK cells, NK CD56^bright cells, NK CD56^dim cells, Tregs, cytotoxic cells, and Th17 cells. Functions relating to protein processing and ubiquitin were included in the CUL5 functional mechanisms. The top 100 genes that are most strongly related to CUL5 were identified, and enrichment analysis indicated that the biological process with the closest relationship was neddylation, related pathways included the TGF-beta signaling pathway and intracellular receptor signaling pathway. CUL5 is related to biological cell behaviors such as chromosome segregation and positive regulation of chromosome organization. As the first study to perform a pan-cancer analysis of CUL5, the present findings will improve the understanding of the oncogenic role of CUL5 in different tumors.

Cullin 3 overexpression inhibits lung cancer metastasis and is associated with survival of lung adenocarcinoma

Cullin 3 (CUL3), a molecular scaffold of Cullin-RING ubiquitin ligase, plays an important role in regulating biological processes through modulating the ubiquitylation and degradation of various protein substrates. Dysfunction of CUL3 is implicated in the development of several human diseases. However, the clinical significance and prognostic value of CUL3 in lung cancer have not been investigated. This study investigated the CUL3-modulating potential of non-small cell lung cancer cell lines, H1299, H358, H2170 and H520, by using immunoblotting, MTT, migration, invasion, colony formation and in vivo tumorigenicity assays. The prognostic significance of CUL3 was measured by public KM plotter database (http://kmplot.com/analysis/index.php?p=service&cancer=breast) and tissue immunohistochemistry analysis. The public online database analysis revealed that elevated mRNA expression of CUL3 was associated with better prognosis for non-small cell lung cancer and lung adenocarcinoma. In vitro experiments showed that ectopic overexpression of CUL3 significantly inhibited lung adenocarcinoma cell proliferation and migration, and the tumor-suppressive effect of CUL3 was dependent on the Nrf2/RhoA axis. In vivo mice model demonstrated that overexpression of CUL3 lead to a significant reduction of lung adenocarcinoma growth and metastasis. Importantly, tissue immunohistochemistry analysis showed that about 47% of non-small cell lung cancer tissues were expressed of CUL3 at high levels. Overexpression of CUL3 predicted favorable overall survival in non-small cell lung cancer patients, especially in lung adenocarcinoma, but not in lung squamous cell carcinoma patients. CUL3 could serve as a prognostic biomarker for lung adenocarcinoma. Loss of CUL3 might be driving tumorigenesis by activating the Nrf2/RhoA pathway.