P53 and Protein Phosphorylation Regulate the Oncogenic Role of Epithelial Cell Transforming 2 (ECT2)

GINS2 regulates temozolomide chemosensitivity via the EGR1/ECT2 axis in gliomas

Temozolomide (TMZ), a DNA alkylating agent, has become the primary treatment for glioma, the most common malignancy of the central nervous system. Although TMZ-containing regimens produce significant clinical response rates, some patients inevitably suffer from inferior treatment outcomes or disease relapse, likely because of poor chemosensitivity of glioma cells due to a robust DNA damage response (DDR). GINS2, a subunit of DNA helicase, contributes to maintaining genomic stability and is highly expressed in various cancers, promoting their development. Here, we report that GINS2 was upregulated in TMZ-treated glioma cells and co-localized with γH2AX, indicating its participation in TMZ-induced DDR. Furthermore, GINS2 regulated the malignant phenotype and TMZ sensitivity of glioma cells, mostly by promoting DNA damage repair by affecting the mRNA stability of early growth response factor 1 (EGR1), which in turn regulates the transcription of epithelial cell-transforming sequence 2 (ECT2). We constructed a GINS2-EGR1-ECT2 prognostic model, which accurately predicted patient survival. Further, we screened Palbociclib/BIX-02189 which dampens GINS2 expression and synergistically inhibits glioma cell proliferation with TMZ. These findings delineate a novel mechanism by which GINS2 regulates the TMZ sensitivity of glioma cells and propose a promising combination therapy to treat glioma.

miRNA-223-3p regulates ECT2 to promote proliferation, invasion, and metastasis of gastric cancer through the Wnt/β-catenin signaling pathway

PURPOSE

Expression of the guanine nucleotide exchange factor epithelial cell transforming 2 (ECT2) is elevated in gastric cancer (GC) but its biological function in GC is poorly understood. MicroRNAs (miRNAs) have great potential as therapeutic targets for GC through their ability to modulate gene expression. In the present study, we sought to identify potential miRNA-mRNA-protein regulatory pathways that might control ECT2 expression and function in GC.

METHODS

ECT2 expression was examined in clinical GC specimens by immunohistochemical staining, and protein levels were correlated with clinicopathological features and prognosis. TargetScan was used to identify potential ECT2 mRNA-complementary miRNAs, and the roles of ECT2 and miRNA-223-3p (miR-223-3p) in GC cell biology and signaling pathway activation were examined by targeted knockdown (KD) or overexpression (OE) of ECT2 and miR-223-3p in GC cell lines. A murine GC xenograft model was developed to explore the impact of ECT2 OE on tumor growth in vivo.

RESULTS

ECT2 expression was significantly elevated in GC specimens compared with normal gastric tissues and the level correlated positively with depth of invasion, ulceration, vascular tumor thrombus, neural invasion, and lymph node metastasis (p < 0.05). ECT2 was an independent prognostic factor for overall survival of GC patients (high ECT2 expression v.s. low ECT2 expression: χ² = 29.831, p < 0.001). ECT2 KD or miR-223-3p OE markedly suppressed the proliferation, migration, and invasion of GC cells in vitro, whereas ECT2 OE had the opposite effects. ECT2 OE also promoted the growth of GC tumors in vivo. Tumor expression of Wnt2, β-catenin, and several downstream target proteins in GC cells were decreased by ECT2 KD or miR-223-3p OE but increased by ECT2 OE.

CONCLUSIONS

miR-223-3p regulates ECT2 expression to promote tumorigenic behavior of GC via activation of the Wnt/β-catenin signaling pathway, suggesting that ECT2 and miR-223-3p as potential therapeutic targets for GC.

Upregulation of ECT2 Predicts Adverse Clinical Outcomes and Increases 5-Fluorouracil Resistance in Gastric Cancer Patients

Background

The abnormal expression and prognosis prediction of epithelial cell transforming sequence 2 (ECT2) in gastric cancer (GC) has been reported. However, the effect of ECT2 on 5-fluorouracil (5-Fu) resistance in GC is unclear. This research aims to solve the abovementioned problems.

Methods

Gene expression was detected by RT-qPCR and Western blot analysis. Cell viability was evaluated by the colony formation assay, MTT assay, and flow cytometric analysis. Transwell and wound healing assays were used to detect cell metastasis.

Results

Upregulation of ECT2 was found in stomach adenocarcinoma (STAD) and GC tissues. In addition, high ECT2 expression can predict adverse clinical outcomes in GC patients. More importantly, ECT2 knockdown weakened the resistance of 5-FU in GC cells. ECT2 silencing reduced the cell migratory and invasive abilities of GC cells treated with 5-FU. We also found that downregulation of ECT2 increased 5-FU sensitivity in GC cells by downregulating P-gp, MRP1, and Bcl-2.

Conclusion

Upregulation of ECT2 can predict adverse clinical outcomes and increase 5-FU resistance in GC patients.

Small Proline-Rich Protein 2B Facilitates Gastric Adenocarcinoma Proliferation via MDM2-p53/p21 Signaling Pathway

Background

The small proline-rich protein 2B (SPRR2B) was firstly reported as a member of the cross-linked envelope protein in keratinocytes. The effect of SPRR2B in gastric adenocarcinoma (GC) remains unclear. This study initially explored the clinical significance of SPRR2B in GC patients as well as its role in tumor progression.

Methods

Immunohistochemistry was performed to characterize the expression of SPRR2B in GC tissues and adjacent tissues. The relationship between SPRR2B expression and clinicopathological features of GC patients was analyzed by Chi-square test. Kaplan-Meier method and Cox regression analyses were utilized to identify the prognostic factors of GC. Overexpression and knockdown assays were conducted to investigate possible signaling pathways downstream of SPRR2B. Flow cytometry assays were performed to evaluate cell cycle and apoptosis. Xenograft experiments were performed to validate tumor-related role of SPRR2B in vivo.

Results

Both mRNA and protein levels of SPRR2B in cancerous tissue were significantly higher than those in non-cancerous tissues. Meanwhile, SPRR2B expression was significantly associated with tumor size and tumor stage. Survival analysis revealed SPRR2B as one of the independent prognosis factors for overall survival of GC patients. Cellular and xenografts data implicated that silencing SPRR2B blocked the cell cycle of GC cells perhaps through MDM2-p53/p21-CDK1 pathway, while overexpressing SPRR2B exhibited opposite effects.

Conclusion

Our data suggest that SPRR2B may serve as a novel prognostic marker in GC, which functions at least partially by MDM2-p53/p21-CDK1 signaling pathway.

Role of Small GTPase RhoA in DNA Damage Response

Accumulating evidence has suggested a role of the small GTPase Ras homolog gene family member A (RhoA) in DNA damage response (DDR) in addition to its traditional function of regulating cell morphology. In DDR, 2 key components of DNA repair, ataxia telangiectasia-mutated (ATM) and flap structure-specific endonuclease 1 (FEN1), along with intracellular reactive oxygen species (ROS) have been shown to regulate RhoA activation. In addition, Rho-specific guanine exchange factors (GEFs), neuroepithelial transforming gene 1 (Net1) and epithelial cell transforming sequence 2 (Ect2), have specific functions in DDR, and they also participate in Ras-related C3 botulinum toxin substrate 1 (Rac1)/RhoA interaction, a process which is largely unappreciated yet possibly of significance in DDR. Downstream of RhoA, current evidence has highlighted its role in mediating cell cycle arrest, which is an important step in DNA repair. Unraveling the mechanism by which RhoA modulates DDR may provide more insight into DDR itself and may aid in the future development of cancer therapies.

Comprehensive Analysis of Differential Gene Expression to Identify Common Gene Signatures in Multiple Cancers

Background

With the development of research on cancer genomics and microenvironment, a new era of oncology focusing on the complicated gene regulation of pan-cancer research and cancer immunotherapy is emerging. This study aimed to identify the common gene expression characteristics of multiple cancers – lung cancer, liver cancer, kidney cancer, cervical cancer, and breast cancer – and the potential therapeutic targets in public databases.

Material/Methods

Gene expression analysis of GSE42568, GSE19188, GSE121248, GSE63514, and GSE66272 in the GEO database of multitype cancers revealed differentially expressed genes (DEGs). Then, GO analysis, KEGG function, and path enrichment analyses were performed. Hub-genes were identified by using the degree of association of protein interaction networks. Moreover, the expression of hub-genes in cancers was verified, and hub-gene-related survival analysis was conducted. Finally, infiltration levels of tumor immune cells with related genes were explored.

Results

We found 12 cross DEGs in the 5 databases (screening conditions: “adj p<0.05” and “logFC>2 or logFC<–2”). The biological processes of DEGs were mainly concentrated in cell division, regulation of chromosome segregation, nuclear division, cell cycle checkpoint, and mitotic nuclear division. Furthermore, 10 hub-genes were obtained using Cytoscape: TOP2A, ECT2, RRM2, ANLN, NEK2, ASPM, BUB1B, CDK1, DTL, and PRC1. The high expression levels of the 10 genes were associated with the poor survival of these multiple cancers, as well as ASPM, may be associated with immune cell infiltration.

Conclusions

Analysis of the common DEGs of multiple cancers showed that 10 hub-genes, especially ASPM and CDK1, can become potential therapeutic targets. This study can serve as a reference to understand the characteristics of different cancers, design basket clinical trials, and create personalized treatments.

Clinicopathological and prognostic significance of epithelial cell transforming sequence 2 expression in cancers: a systematic review and meta-analysis

Numerous studies have investigated the prognostic significance of ECT2 (epithelial cell transforming sequence 2) expression in patients with cancer. Nevertheless, conflicting results have been obtained. We thus performed a meta-analysis to systematically assess the prognostic significance of ECT2 in cancer. Electronic databases (PubMed and EMBASE) were searched for eligible studies. Hazard ratios (HR) and odds ratios (OR) with 95% confidence intervals (CIs) were used to estimate effect sizes. A total of 5,305 patients from 19 articles and 21 studies were included. The pooled results revealed that high ECT2 expression was correlated with advanced TNM stage (OR = 2.17; 95% CI: 1.42-3.32), positive lymph node metastasis (OR = 2.98; 95% CI: 2.28-3.89), distant metastasis (OR = 2.25; 95% CI: 1.03-4.92), and poor tumour differentiation (OR = 2.25; 95% CI: 1.03-4.92). More importantly, high ECT2 expression was significantly associated with poor overall survival (HR = 2.26; 95% CI, 1.84-2.78) and recurrence-free survival (HR = 1.52; 95% CI, 1.24-1.86). Our results suggested that ECT2 is a promising prognostic indicator and therapeutic target for cancer.

Reduced Expression of Deubiquitinase USP33 Is Associated with Tumor Progression and Poor Prognosis of Gastric Adenocarcinoma

Background

Ubiquitin-specific peptidase 33 (USP33) is a deubiquitinase that balances the ubiquitin status of proteins. It has been reported to act as a tumor suppressor in colorectal cancer and lung cancer. However, the expression pattern and clinical significance of USP33 have not been investigated in gastric adenocarcinoma (GAC).

Material/Methods

We explored the USP33 protein and RNA levels by immunohistochemistry (IHC), Western blot analysis, and qRT-PCR. The Pearson chi-square test was performed to evaluate the statistical associations between USP33 level and patient characteristics. Additionally, the relationship between USP33 expression and patient survival was investigated. Cellular studies, including proliferation assay, migration assay, and invasion assay, were conducted to demonstrate the underlying mechanisms of USP33 in GAC progression.

Results

This study included 121 patients with GAC. USP33 showed a decreased expression in GAC tissues compared to adjacent normal gastric tissues. Low expression of USP33 was correlated with invasion depth and advanced TNM stage. According to survival analysis, upper location of tumor (P=0.003), invasion depth (P=0.048), advanced TNM stage (P=0.001), and low USP33 level (P=0.001) were all associated with poor overall survival of GAC patients. Cox analysis confirmed the independent role of USP33 in predicting patient survival. Cell experiments showed that USP33 overexpression significantly inhibited the proliferation, migration, and invasion of GAC cells.

Conclusions

USP33 was downregulated in GAC, and was an independent prognostic factor. In vitro results demonstrated the role of USP33 in suppressing tumor progression, suggesting that the developing an agonist of USP33 may be a novel direction for chemotherapy development.

Usnic Acid Induces Cycle Arrest, Apoptosis, and Autophagy in Gastric Cancer Cells In Vitro and In Vivo

Background

Usnic acid (UA), a secondary metabolite, is mainly derived from certain lichen species. Growing evidence suggests that UA has antitumor, anti-oxidative, anti-inflammatory, and other activities in a variety of cancer cells. However, the antitumor effect of UA in gastric cancer cells (GC) is unclear. The aim of this investigation was to assess the antitumor effect of UA in GC cells in vitro and in vivo, and to explore the underlying mechanisms.

Material/Methods

Cell proliferation was measured by CCK8 assay, the arrest of cell cycle was assessed by flow cytometry, and cellular apoptosis was observed via Hoechst 33258 staining assay. Expression levels of apoptosis-related proteins (activated caspase-3 and PARP, Bax, Bcl2) and autophagy-associated proteins (LC3-II and p62) were verified through Western blot analysis. H&E staining and immunohistochemistry were carried out in the subcutaneously implanted BGC823 tumor model in a nude mouse experiment.

Results

In vitro, we demonstrated that UA was significantly effective in inducing morphological changes, inhibiting the cell proliferation dose- and time-dependently, arresting the cell cycle phase, promoting cancer cellular apoptosis, and inducing autophagy activity. In vivo, compared to mice treated with 5-FU alone, UA treatment was significantly more effective in suppressing the tumor growth without affecting body weight, and in regulating the amount of Bax and Bcl2 in tumor tissues.

Conclusions

UA induces cell cycle arrest and autophagy and exerts anti-proliferative and apoptotic effects by modulating expression of apoptosis-related proteins in stomach neoplasm cells, and has a better antitumor effect compared to 5-Fu in the xenograft model.