C-terminal binding protein-2 promotes cell proliferation and migration in breast cancer via suppression of p16INK4A

C-Terminal Binding Protein: Regulator between Viral Infection and Tumorigenesis

C-terminal binding protein (CtBP), a transcriptional co-repressor, significantly influences cellular signaling, impacting various biological processes including cell proliferation, differentiation, apoptosis, and immune responses. The CtBP family comprises two highly conserved proteins, CtBP1 and CtBP2, which have been shown to play critical roles in both tumorigenesis and the regulation of viral infections. Elevated CtBP expression is noted in various tumor tissues, promoting tumorigenesis, invasiveness, and metastasis through multiple pathways. Additionally, CtBP's role in viral infections varies, exhibiting differing or even opposing effects depending on the virus. This review synthesizes the advances in CtBP's function research in viral infections and virus-associated tumorigenesis, offering new insights into potential antiviral and anticancer strategies.

Oxidative stress regulation and related metabolic pathways in epithelial-mesenchymal transition of breast cancer stem cells

Epithelial-mesenchymal transition (EMT) is a cell remodeling process in which epithelial cells undergo a reversible phenotype switch via the loss of adhesion capacity and acquisition of mesenchymal characteristics. In other words, EMT activation can increase invasiveness and metastatic properties, and prevent the sensitivity of tumor cells to chemotherapeutics, as mesenchymal cells have a higher resistance to chemotherapy and immunotherapy. EMT is orchestrated by a complex and multifactorial network, often linked to episodic, transient, or partial events. A variety of factors have been implicated in EMT development. Based on this concept, multiple metabolic pathways and master transcription factors, such as Snail, Twist, and ZEB, can drive the EMT. Emerging evidence suggests that oxidative stress plays a significant role in EMT induction. One emerging theory is that reducing mitochondrial-derived reactive oxygen species production may contribute to EMT development. This review describes how metabolic pathways and transcription factors are linked to EMT induction and addresses the involvement of signaling pathways.

Proteomic Analysis of Zeb1 Interactome in Breast Carcinoma Cells

Breast cancer is the most frequently diagnosed malignant neoplasm and the second leading cause of cancer death among women. Epithelial-to-mesenchymal Transition (EMT) plays a critical role in the organism development, providing cell migration and tissue formation. However, its erroneous activation in malignancies can serve as the basis for the dissemination of cancer cells and metastasis. The Zeb1 transcription factor, which regulates the EMT activation, has been shown to play an essential role in malignant transformation. This factor is involved in many signaling pathways that influence a wide range of cellular functions via interacting with many proteins that affect its transcriptional functions. Importantly, the interactome of Zeb1 depends on the cellular context. Here, using the inducible expression of Zeb1 in epithelial breast cancer cells, we identified a substantial list of novel potential Zeb1 interaction partners, including proteins involved in the formation of malignant neoplasms, such as ATP-dependent RNA helicase DDX17and a component of the NURD repressor complex, CTBP2. We confirmed the presence of the selected interactors by immunoblotting with specific antibodies. Further, we demonstrated that co-expression of Zeb1 and CTBP2 in breast cancer patients correlated with the poor survival prognosis, thus signifying the functionality of the Zeb1–CTBP2 interaction.

LncRNA H19-Derived miR-675-5p Accelerates the Invasion of Extravillous Trophoblast Cells by Inhibiting GATA2 and Subsequently Activating Matrix Metalloproteinases

The invasion of extravillous trophoblast (EVT) cells into the maternal decidua, which plays a crucial role in the establishment of a successful pregnancy, is highly orchestrated by a complex array of regulatory mechanisms. Non-coding RNAs (ncRNAs) that fine-tune gene expression at epigenetic, transcriptional, and post-transcriptional levels are involved in the regulatory mechanisms of EVT cell invasion. However, little is known about the characteristic features of EVT-associated ncRNAs. To elucidate the gene expression profiles of both coding and non-coding transcripts (i.e., mRNAs, long non-coding RNAs (lncRNAs), and microRNAs (miRNAs)) expressed in EVT cells, we performed RNA sequencing analysis of EVT cells isolated from first-trimester placentae. RNA sequencing analysis demonstrated that the lncRNA H19 and its derived miRNA miR-675-5p were enriched in EVT cells. Although miR-675-5p acts as a placental/trophoblast growth suppressor, there is little information on the involvement of miR-675-5p in trophoblast cell invasion. Next, we evaluated a possible role of miR-675-5p in EVT cell invasion using the EVT cell lines HTR-8/SVneo and HChEpC1b; overexpression of miR-675-5p significantly promoted the invasion of both EVT cell lines. The transcription factor gene GATA2 was shown to be a target of miR-675-5p; moreover, small interfering RNA-mediated GATA2 knockdown significantly promoted cell invasion. Furthermore, we identified MMP13 and MMP14 as downstream effectors of miR-675-5p/GATA2-dependent EVT cell invasion. These findings suggest that miR-675-5p-mediated GATA2 inhibition accelerates EVT cell invasion by upregulating matrix metalloproteinases.

Gadd45α affects retinal ganglion cell injury in chronic ocular hypertension rats by regulating p38MAPK pathway

OBJECTIVE

To investigate the impact and the mechanism of Gadd45α mediating p38MAPK pathway on the retinal ganglion cells (RGCs) injury in chronic ocular hypertension (COH) rats.

METHODS

COH model in rats were established and intraocular pressure (IOP) was tested. Retrograde labeling was used for counting RGCs and TUNEL staining was performed for RGCs apoptosis. Western Blotting was conducted to examine the expression of Gadd45α and p38MAPK pathway. Besides, RGC-5 cells cultured in vitro were treated with H₂O₂. Cell viability was detected by CCK-8, ROS level tested by DCFH-DA assay, and cell apoptosis examined by flow cytometry.

RESULTS

COH rats had increased expression of Gadd45α and p-p38/p38 protein 1-4 weeks after surgery. Rats in COH group enhanced obviously in IOP, RGC apoptosis rate and the protein expression of Gadd45α, p-p38/p38, Bax/Bcl-2 and cleaved caspase-3, but declined appreciably in RGC counting. However, the above indicators of COH rats were effectively improved by Gadd45α shRNA treatment. Additionally, RGC-5 cells in H₂O₂ group reduced in cell viability and went up in ROS level and apoptosis rate. The H₂O₂-induced RGC-5 cells treated with Gadd45α shRNA were improved apparently in those indicators, and cells treated with pcDNA Gadd45α showed an opposite trend. Moreover, p38 MAPK inhibitor SB203580 can effectively reverse the damage of pcDNA Gadd45α from H₂O₂-induced RGC-5 cells.

CONCLUSION

Silencing Gadd45α can reduce the RGC damage in COH rats by inhibiting p38MAPK pathway and such a protective role may be associated with the suppression of RGC apoptosis and the mitigation of oxidative stress.

CtBP2 interacts with ZBTB18 to promote malignancy of glioblastoma

OBJECTIVE

To investigate how the interaction of CtBP2 with ZBTB18 affect glioblastoma (GBM).

METHODS

Western blotting was performed to detect CtBP2 and ZBTB18 expression in GBM and normal brain tissues (NBT). U-87 MG cells were transfected with ZBTB18 CRISPR activation plasmid, CtBP2 shRNA with/without ZBTB18 shRNA. The biological characteristics were detected by EdU assay, MTT, Wound-healing, Transwell, TUNEL staining, and Flow cytometry. Furthermore, U-87 MG cells transfected with CtBP2 shRNA and/or ZBTB18 shRNA were injected into the flank region of mice and the tumor volume was measured. The mRNA and protein expression was quantified by qRT-PCR or Western blotting.

RESULTS

GBM tissues exhibited increased CtBP2 expression and decreased ZBTB18 expression, which demonstrated a negative correlation in GBM tissues and showed the combined effect on prognosis. Based on immunoprecipitation and immunofluorescence, there was an interaction between CtBP2 and ZBTB18 in U-87 MG cells. CtBP2 shRNA counteracted the effect of ZBTB18 shRNA on inhibiting U-87 MG cell apoptosis, as well as promoting cell proliferation and viability with increased EMT, invasion and migration. Meanwhile, CtBP2 shRNA interact with ZBTB18 to block cells at phase G0/G1 and suppress SHH-GLI1 pathway. CtBP2 shRNA decreased tumor volume, increase ZBTB18 expression in tumor tissues, and inhibit SHH-GLI1 pathway in mice, which could be reversed by ZBTB18 shRNA.

CONCLUSION

CtBP2 elevation and ZBTB18 down-regulation were found in GBM, both of which were associated with prognosis of GBM patients. CtBP2 interacted with ZBTB18 to affect biological characteristics of GBM cells, and the tumor growth, which may be related to the SHH-GLI1 pathway.

Stabilization of C-terminal binding protein 2 by cellular inhibitor of apoptosis protein 1 via BIR domains without E3 ligase activity

C-terminal binding protein 2 (CtBP2) is a transcriptional co-repressor that regulates many genes involved in normal cellular events. Because CtBP2 overexpression has been implicated in various human cancers, its protein levels must be precisely regulated. Previously, we reported that CtBP1 and CtBP1-mediated transcriptional repression are regulated by X-linked inhibitor of apoptosis protein (XIAP). In the present study, we sought to investigate whether CtBP2 is also regulated by XIAP or any other human IAP. We found that cIAP1 interacts with CtBP2 via through BIR domains to regulates the steady-state levels of CtBP2 protein in the nucleus. The levels of CtBP2 were gradually increased upon cIAP1 overexpression and downregulated upon cIAP1 depletion. Interestingly, the RING domain of cIAP1 responsible for E3 ligase activity was not required for this regulation. Finally, the levels of CtBP2 modulated by cIAP1 affected the transcription of CtBP2 target genes and subsequent cell migration. Taken together, our data demonstrate a novel function of cIAP1 which involves protecting CtBP2 from degradation to stabilize its steady-state level. These results suggest that cIAP1 might be a useful target in strategies aiming to downregulate the steady-state level of CtBP2 protein in treating human cancers.

C-terminal binding protein-2 is a prognostic marker for lung adenocarcinomas

C-terminal binding protein-2 (CtBP2) a transcriptional corepressor, has been reported to involve in tumorigenesis and progression and predict a poor prognosis in several human cancers. However, few studies on CtBP2 in lung cancer tissues have been performed. In the present study, we first explored the CtBP2 gene expression profile from the the cancer genome atlas (TCGA) datasets, then western blot analysis and immunohistochemistry were performed to investigate and verified whether lung adenocarcinoma (LUAD) tissues exhibit deregulated CtBP2 expression. We evaluated the correlations between CtBP2 expression and the clinicopathological characteristics, and Kaplan-Meier survival analyses were performed to estimate the effect of CtBP2 expression on prognosis of LUAD patients. The results revealed that CtBP2 expression was significantly upregulated in LUAD tissues compared with normal lung tissues. Furthermore, increasing CtBP2 expression in LUAD was significantly associated with tumor differentiation (P = .028), tumor node metastasis (TNM) stage (P = .042). CtBP2 expression was significantly correlated with LUAD patients' survival (P = .028). In conclusion, the present study revealed that CtBP2 protein is a novel prognostic marker for LUAD. A further large-scale study is needed to confirm the present results.

Association between genetic variants at 9p21 locus with risk of breast cancer: A systematic review and meta-analysis

Breast cancer (BC) is the most frequent tumor in women and genetic factors are among the main risk factors contributing to this malignancy. Chromosome 9p21 contains important regulatory non-coding RNAs and is associated with multiple malignancies including BC. The current meta-analysis aimed to investigate the association between genetic variants within the 9p21 locus and risk of breast cancer. A literature search was performed using PubMed, Web of Science, Embase, MEDLINE, Scopus and Clinical key databases. Nine studies containing 23,726 subjects were eligible for the final analysis and specific odds ratios (OR) and confidence intervals (95% CI) were evaluated to assess the strength of the associations. In the pooled analysis, there was an association between the genetic variations in 9p21 locus (CDKN2A/2B) with risk of breast cancer with a standard OR of 1.22 (95% CI: 1.04-1.45, P = 0.016; random-effects model), supporting the significance of this locus as a novel risk factor for breast cancer patients. In conclusion, our results showed that 9p21 region is positively associated with risk of BC and its polymorphisms may be a candidate marker for BC susceptibility.

Effects of gametogenetin-binding protein 2 on proliferation, invasion and migration of prostate cancer PC-3 cells

We aimed to assess the effects of gametogenetin-binding protein 2 (GGNBP2) on the proliferation, invasion and migration of prostate cancer PC-3 cells. PcDNA3-HisC-GGNBP2 was transfected to overexpress GGNBP2. Proliferation was tested by MTT assay, and migration and invasion were detected by Transwell assay. Cell cycle was detected by flow cytometry. The protein expressions of COX-2, cyclin D1, PI3K, Akt and p-Akt were detected by Western blot. A subcutaneous xenograft model of prostate cancer was established. Mice were randomly divided into three groups (n = 9) and intratumorally injected with pcDNA3-HisC-GGNBP2, pcDNA3-HisC and normal saline respectively. The xenograft tumour volume was measured every 3 days, and weight was measured after 2 weeks. After GGNBP2 overexpression, the proliferation, migration and invasion capacities of PC-3 cells decreased, and cell cycle was arrested in the G1 phase. The protein expressions of COX-2, cyclin D1, PI3K, Akt and p-Akt all reduced. The tumour volume and weight of pcDNA3-HisC-GGNBP2 group were significantly lower than those of pcDNA3-HisC group (p < .05). The proliferation capacity of GGNBP2-overexpressing prostate cancer cells is significantly attenuated, tumour growth is significantly inhibited, and cell cycle is arrested in the G1 phase. GGNBP2 overexpression affects the growth of castration-resistant prostate cancer via the PI3K/Akt signalling pathway.

C-terminal binding protein‑2 mediates cisplatin chemoresistance in esophageal cancer cells via the inhibition of apoptosis

C-terminal binding protein‑2 (CtBP2) is a transcriptional co-repressor that is associated with tumorigenesis and tumor progression. It has been reported to predict a poor prognosis in several human cancers, including esophageal squamous cell carcinoma (ESCC). The present study aimed to investigate the involvement of CtBP2 in the cisplatin (DDP) resistance of the ECA109 ESCC cell line and its effect on the expression of apoptosis-associated proteins. Constructed recombinant lentiviruses were used for the knockdown or overexpression of CtBP2 in ECA109 cells, and the expression of CtBP2 was measured using reverse transcription-quantitative polymerase chain reaction and western blotting following transfection. MTT assays, Hoechst 33342 staining and flow cytometry (FCM) were applied to detect the influence of CtBP2 on the DDP-induced viability and apoptosis of the transfected ECA109 cells. In addition, the levels of apoptosis-associated proteins, including p53, B‑cell lymphoma 2 (Bcl‑2), Bcl‑2‑associated X protein (Bax) and activated caspase-3 were investigated in the transfected ECA109 cells. Stable ECA109 cells with CtBP2 overexpression or knockdown were successfully established. The results of the MTT, Hoechst 33342 and FCM assays demonstrated that overexpression of CtBP2 attenuated the reduction of cell viability and inhibited the cell apoptosis induced by DDP. Furthermore, the western blotting results indicated that CtBP2 overexpression inhibited the DDP-induced apoptosis of ECA109 cells via the reduction of p53, activated caspase-3 and Bax expression, and promotion of Bcl‑2 expression. Therefore, the present study indicated that CtBP2 reduced the susceptibility of ECA109 cells to DDP by regulating the expression of apoptosis-related proteins, suggesting that it may be a promising therapeutic target in ESCC in the future.

The 9p21 locus: A potential therapeutic target and prognostic marker in breast cancer

Breast cancer is an important cause of cancer related mortality in women. Despite extensive efforts to identify valid biomarkers for risk stratification, there are relatively few with proven clinical utility. It is recognized that genetic factors play a major role in determining susceptibility to breast cancer. Recent genome-wide-association-studies and gene expression analysis have demonstrated that a locus on chromosome 9p21, which contains three genes; CDKN2B (encoding p15ink4b), CDKN2A (encoding p16ink4a and p14ARF) and the 3' end of CDKN2BAS (an antisense noncoding RNA in the INK4 locus [ANRIL]) are associated with an increased risk of this malignancy. ANRIL has a post transcriptional modulatory activity, which has been shown to perturb the expression of nearby genes and may play an important role in coordinating tissue remodeling through regulation of cell proliferation, apoptosis, aging, extra-cellular matrix remodeling, and inflammatory response. However, the role of ANRIL is not well understood in breast cancer. Hypermethylation of the p14^ARF and p16^INK4a genes is found in some tumor types. Nevertheless, further studies are necessary to confirm the clinical utility of these putative markers in risk stratification, or assessing prognosis. In this review, we have summarized the prognostic and therapeutic potential of the p14^ARF and p16^INK4a genes in patients with breast cancer.

LncRNA NEAT1 Regulates Cell Viability and Invasion in Esophageal Squamous Cell Carcinoma through the miR-129/CTBP2 Axis

Background

Long noncoding RNA nuclear paraspeckle assembly transcript 1 (NEAT1) was reported to be aberrantly upregulated and promote esophageal squamous cell carcinoma (ESCC) cell progression. Nevertheless, the molecular mechanism of NEAT1 involved in the competing endogenous RNA (ceRNA) regulatory network in ESCC progression remains poorly defined.

Methods

The expressions of NEAT1, miR-129, and C-terminal-binding protein 2 (CTBP2) in ESCC cells were examined by qRT-PCR. The effects of NEAT1 knockdown and miR-129 overexpression, or along with CTBP2 upregulation, on ESCC cell viability and invasion were explored by CCK-8 and transwell invasion assays, respectively. Luciferase reporter assay in combination with RIP was performed to confirm the interaction between NEAT1, miR-129, and CTBP2.

Results

NEAT1 and CTBP2 were upregulated and miR-129 was downregulated in ESCC cells. Either NEAT1 knockdown or miR-129 overexpression suppressed ESCC cell viability and invasion. Moreover, NEAT1 functioned as an endogenous sponge to downregulate miR-129 by competitively binding to miR-129, thereby leading to the derepression of CTBP2, a target of miR-129. CTBP2 restoration overturned cell viability and invasion suppression mediated by NEAT1 knockdown or miR-129 overexpression.

Conclusion

LncRNA NEAT1 regulated ESCC cell viability and invasion via the miR-129/CTBP2 axis, contributing to the better understanding of the molecular mechanism of ESCC pathogenesis and progression.