Expression of the Newly Identified Gene CAC1 in the Hippocampus of Alzheimer’s Disease Patients

Emerging therapeutic targets for gastric cancer from a host-Helicobacter pylori interaction perspective

INTRODUCTION

Gastric cancer (GC) has the higher genetic, cytologic, and architectural heterogeneity compared to other gastrointestinal cancers. By inducing gastric inflammation, Helicobacter pylori (HP) may lead to GC through combining bacterial factors with host factors. In this regard, identification of the major therapeutic targets against the host-HP interactions plays a critical role in GC prevention, diagnosis, and treatment.

AREAS COVERED

This study offers new insights into the promising therapeutic targets against the angiogenesis, invasion, or metastasis of GC from a host-HP interaction perspective. To this end, MEDLINE, EMBASE, LILACS, AIM, and IndMed databases were searched for relevant articles since 1992.

EXPERT OPINION

Wnt signaling and COX pathway have a well-documented history in the genesis of GC by HP and might be considered as the most promising targets for early GC treatment. Destroying HP may decrease the risk of GC, but it cannot fully hinder the GC development induced by HP infection. Therefore, targeting HP-activated pathways, especially COX-2/Wnt/beta-catenin/VEGF, TLR2/TLR9/COX-2, COX2-PGE2, and NF-κB/COX-2, as well as EPHA2, MMPs, and miR-543/SIRT1 axis, can be an effective measure in the early treatment of GC. However, different clinical trials and large, multi-center cohorts are required to validate these potentially effective targets for GC therapy.

CDK-associated Cullin 1 promotes Cell Proliferation and inhibits Cell Apoptosis in Human Glioblastoma

BACKGROUND

Glioma is the most common intracranial primary tumour of adult humans, and its pathological mechanism and molecular characteristics are under investigation. CDK-associated cullin 1 (CACUL1) has been shown to regulate colorectal carcinoma, lung cancer and gastric cancer development.

OBJECTIVE

This study aims to explore the role of CACUL1 in the pathogenesis of human glioma.

METHODS

CACUL1 levels in human glioma tissue microarrays were detected by immunohistochemistry analysis. Two glioblastoma cell lines, namely, U87 and U251, were transfected with CACUL1 siRNA, and cell proliferation, cell cycle, cell apoptosis and regulating molecules including cyclin E1, cyclin A2, CDK2, p21, Bcl2 and Bax were assessed by CCK8, flow cytometry and Western blot.

RESULTS

CACUL1 expression in glioma tissue was significantly higher than that in normal brain tissue. CACUL1 knockdown impeded cell proliferation, induced cell apoptosis and caused G1/S transition arrest in glioblastoma cells. The cell cycle-related proteins CDK2, cyclin E1 and cyclin A2 were dramatically decreased in the CACUL1 siRNA group compared to the non-targeting siRNA group in both U87 and U251 cells, while the CDK inhibitory protein p21 was increased in U87 cells. Additionally, the Bcl-2/Bax ratio was significantly decreased.

CONCLUSION

CACUL1 can promote cell proliferation and suppress apoptosis of glioma cells and might serve as a potential oncogene for gliomas.

Investigating aberrantly expressed microRNAs in peripheral blood mononuclear cells from patients with treatment‑resistant schizophrenia using miRNA sequencing and integrated bioinformatics

Treatment-resistant schizophrenia (TRS) is a common phenotype of schizophrenia that places a considerable burden on patients as well as on society. TRS is known for its tendency to relapse and uncontrollable nature, with a poor response to antipsychotics other than clozapine. Therefore, it is urgent to identify objective biological markers, so as to guide its treatment and associated clinical work. In the present study, the peripheral blood mononuclear cells (PBMCs) of patients with TRS and a healthy control group, which were gender-, age- and ethnicity-matched, were subjected to microRNA (miRNA/miR) sequencing to screen out the top three miRNAs with the highest fold change values. These were then validated in the TRS (n=34) and healthy control (n=31) groups by reverse transcription-quantitative PCR. For two of the top three miRNAs, the PCR results were in accordance with the sequencing result (P<0.01), while the third miRNA exhibited the opposite trend (P<0.01). To elucidate the functions of these two miRNAs, Homo sapiens (hsa)-miR-218-5p and hsa-miR-1262 and their regulatory network, target gene prediction was first performed using online TargetScan and Diana-micro T software. Bioinformatics analysis was then performed using functional enrichment analysis to determine the Gene Ontology terms in the category biological process and the Kyoto Encyclopedia of Genes and Genomes pathways. It was revealed that these target genes were markedly associated with the nervous system and brain function, and it was obvious that the differentially expressed miRNAs most likely participated in the pathogenesis of TRS. A receiver operating characteristic curve was generated to confirm the distinct diagnostic value of these two miRNAs. It was concluded that aberrantly expressed miRNAs in PMBCs may be implicated in the pathogenesis of TRS and may serve as specific peripheral blood-based biomarkers for the early diagnosis of TRS.

CAC1 knockdown reverses drug resistance through the downregulation of P-gp and MRP-1 expression in colorectal cancer

CDK2-associated cullin domain 1 (CAC1) is as a novel cell cycle regulator widely expressed in colorectal cancer (CRC). However, its expression and function in drug resistant CRC cells remains elusive. Therefore, the present study aimed to assess the biochemical function and relevance of CAC1 in drug resistant CRC cells, and detect the potential mechanism. For this purpose, a total of 83 CRC cases were collected for the immunohistochemical analysis of CAC1 expression. Functional studies (stable transfection, flow cytometry, colony formation, and invasion and migration assays) were performed in SW480, LoVo and their corresponding 5-FU resistant cells. In addition, a nude mice xenograft model was established for further observation in vivo. In the present study, CAC1 protein expression was higher in CRC tissues than that in normal tissues (P<0.05). Furthermore, CAC1 protein expression was higher in SW480/5-FU cells than in SW480 cells. CAC1 knockdown arrested 5-FU resistant cells at the G1/S phase and increased the sensitivity of 5-FU resistant cells to 5-FU by inducing apoptosis. In addition, CAC1 reduced the invasive and migration ability of SW480/5-FU and LoVo/5-FU cells in vitro, and reduced their tumorigenicity and metastatic ability in vivo. Finally, CAC1 knockdown resulted in decreased P-glycoprotein and MRP-1 protein expression. Based on these results, it can be concluded that CAC1 plays an important role in the occurrence and promotion of drug resistance in CRC. Therefore, the knockdown of CAC1 may be considered as a new strategy for the development of CRC drug resistance treatments in the future.

Screening the expression of several miRNAs from TaqMan Low Density Array in traumatic brain injury: miR-219a-5p regulates neuronal apoptosis by modulating CCNA2 and CACUL1

Circulating microRNAs (miRNAs) have emerged as diagnostic and prognostic biomarkers for traumatic brain injury (TBI). However, a comprehensive characterization of the serum miRNA profile in patients with TBI and the roles of these potential markers in neuronal regulation have rarely been reported. In this study, the levels of 754 serum miRNAs were initially determined in two pooled samples of 15 severe traumatic brain injury (sTBI) patients and 15 healthy controls using a TaqMan Low Density Array. The markedly upregulated miRNAs in sTBI patients were subsequently validated individually by quantitative reverse-transcription PCR (RT-qPCR) in another larger cohort consisting of 81 sTBI patients, 81 mild traumatic brain injury (mTBI) patients and 82 age/sex-matched healthy controls. Seven miRNAs, including miR-103a-3p, miR-219a-5p, miR-302d-3p, miR-422a, miR-518f-3p, miR-520d-3p and miR-627, were significantly upregulated in both sTBI and mTBI patients compared with their expression in controls. Among these miRNAs, miR-219a-5p not only discriminated sTBI and mTBI patients from controls but also discriminated between sTBI and mTBI patients. We further show here that in the neuronal cell injury model, upregulated miR-219a-5p inhibits the expression of CCNA2 and CACUL1 and further regulates akt/Foxo3a and p53/Bcl-2 signaling pathways, causing a notable change in the expression of cleaved caspase-3, thereby inducing neuronal apoptosis. These results indicate that these seven selected miRNAs could serve as novel biomarkers for TBI. In particular, miR-219a-5p is a potentially valuable indicator of the diagnosis, prognosis of TBI and appears to regulate neuronal apoptosis and death.

Vanillin improves scopolamine‑induced memory impairment through restoration of ID1 expression in the mouse hippocampus

4-Hydroxy-3-methoxybenzaldehyde (vanillin), contained in a number of species of plant, has been reported to display beneficial effects against brain injuries. In the present study, the impact of vanillin on scopolamine‑induced alterations in cognition and the expression of DNA binding protein inhibitor ID‑1 (ID1), one of the inhibitors of DNA binding/differentiation proteins that regulate gene transcription, in the mouse hippocampus. Mice were treated with 1 mg/kg scopolamine with or without 40 mg/kg vanillin once daily for 4 weeks. Scopolamine‑induced cognitive impairment was observed from 1 week and was deemed to be severe 4 weeks following the administration of scopolamine. However, treatment with vanillin in scopolamine‑treated mice markedly attenuated cognitive impairment 4 weeks following treatment with scopolamine. ID1‑immunoreactive cells were revealed in the hippocampus of vehicle‑treated mice, and were hardly detected 4 weeks following treatment with scopolamine. However, treatment with vanillin in scopolamine‑treated mice markedly restored ID1‑immunoreactive cells and expression 4 weeks subsequent to treatment. The results of the present study suggested that vanillin may be beneficial for cognitive impairment, by preventing the reduction of ID1 expression which may be associated with cognitive impairment.

Effects of chronic scopolamine treatment on cognitive impairment and neurofilament expression in the mouse hippocampus

Neurofilaments (NFs) including neurofilament-200 kDa (NF-H), neurofilament-165 kDa (NF-M) and neurofilament-68 kDa (NF-L) are major protein constituents of the brain, and serve important roles in the regulation of axonal transport. NF alteration is a key feature in the pathogenesis of neurological disorders involving cognitive dysfunction. In the present study, cognitive impairments were investigated, via assessments using the Morris water maze and passive avoidance tests, in mice following chronic systemic treatment with 1 mg/kg scopolamine (SCO) for 4 weeks. SCO-induced cognitive impairments were significantly observed 1 week following the SCO treatment, and these cognitive deficits were maintained for 4 weeks. However, the NF immunoreactivities and levels were altered differently according to the hippocampal subregion following SCO treatment. NF-H immunoreactivity and levels were markedly altered in all hippocampal subregions, and were significantly increased 1 week following the SCO treatment; thereafter, the immunoreactivity and levels significantly decreased with time. NF-M immunoreactivity and levels gradually decreased in the hippocampus and were significantly decreased 4 weeks following SCO treatment. NF-L immunoreactivity and levels gradually decreased in the hippocampus, and were significantly decreased 2 and 4 weeks following SCO treatment. In conclusion, the results of the present study demonstrated that chronic systemic treatment with SCO induced cognitive impairment from 1 week following SCO treatment, and NF expression was diversely altered according to the hippocampal subregion from 1 week following SCO treatment. These results suggest that SCO-induced changes in NF expression may be associated with cognitive impairment.

CACUL1/CAC1 attenuates p53 activity through PML post-translational modification

Promyelocytic leukaemia (PML) is a tumor suppressor protein covalently conjugated with SUMO family proteins, leading to the formation of PML nuclear bodies (NBs). PML-NBs provide a platform for efficient posttranslational modification of targets and protein-protein interaction, contributing to the adjustment of gene expression and chromatin integrity. Although PML SUMOylation is thought to play important roles in diverse cellular functions, the control mechanisms of adequate modification levels have remained unsolved. Here, we report that Cullin-related protein CACUL1/CAC1 (CACUL1) inhibits PML posttranslational modification. CACUL1 interacts with PML and suppresses PML SUMOylation, leading to the regulation of PML-NB size in the nucleus. We also found that Ubc9, a SUMO-conjugating enzyme, binds to CACUL1 and antagonizes the interaction between CACUL1 and PML. Furthermore, CACUL1 attenuates p53 transcriptional activity. These data suggest that CACUL1 is a novel regulator that negatively controls p53 activity through the regulation of PML SUMOylation.

CACUL1/CAC1 Regulates the Antioxidant Response by Stabilizing Nrf2

Nrf2 is the pre-dominant transcription activator responsible for coordinated up-regulation of ARE-driven antioxidant and detoxification genes. The activity of Nrf2 is tightly regulated at basal levels through its ubiquitination by Cul3-Keap1 and consequential degradation. Upon exposure to stress, the Cul3-Keap1 ligase is inhibited, leading to Nrf2 stabilization and activation. Here we describe CACUL1/CAC1 as a positive regulator of the Nrf2 pathway. We found that CACUL1 is up-regulated by Nrf2-activating oxidative stresses in cells and in mice. The association of CACUL1 with the Cul3-Keap1 complex led to a decrease in Nrf2 ubiquitination levels at non-stressed as well as stressed conditions, and sensitized cells for higher Nrf2 activation. Furthermore, CACUL1 knock-down led to a decrease in Nrf2 activity and cell viability under stress. Our results show that CACUL1 is a regulator of Nrf2 ubiquitination, adding another regulatory layer to the Nrf2 antioxidant stress response.

Helicobacter pylori promotes invasion and metastasis of gastric cancer cells through activation of AP-1 and up-regulation of CACUL1

Infection with Helicobacter pylori is important in the development and progression of gastric cancer. However, the mechanisms that regulate this activation in gastric tumors remain elusive. CACUL1 has been cloned and identified as a novel gene that is expressed in many types of cancer and is involved in cell cycle regulation and tumor growth. The current study aimed to examine the expression of CACUL1 in gastric cancer samples and analyze its correlation with H. pylori infection. We found that CACUL1 was highly expressed in gastric cancer tissues and negatively correlated with gastric cancer differentiation and TNM stage. In addition, CACUL1 expression was high in H. pylori-infected tissues compared with H. pylori non-infected tissue. We found that H. pylori could up-regulate CACUL1 expression through activating protein 1. The up-regulation of CACUL1 expression could promote matrix metalloproteinase 9 and Slug expression to increase invasion and metastasis of tumor cells. These results suggested that H. pylori-triggered CACUL1 production occurred in an activating protein 1-dependent manner and regulated matrix metalloproteinase 9 and Slug expression to affect the invasion and metastasis of tumor cells. Therefore, CACUL1 is a potential therapeutic target for the treatment of aggressive gastric cancer.

The deoxycholic acid targets miRNA-dependent CAC1 gene expression in multidrug resistance of human colorectal cancer

There is evidence indicating that bile acid is a promoter of colorectal cancer. Deoxycholic acid modifies apoptosis and proliferation by affecting intracellular signaling and gene expression. We are interested in revealing the relationship between deregulated miRNAs and deoxycholic acid in colorectal cancer development. We found that miR-199a-5p was expressed at a low level in human primary colonic epithelial cells treated with deoxycholic acid compared with control, and miR-199a-5p was significantly down-regulated in colorectal cancer tissues. The miR-199a-5p expression in colorectal cancer cells led to the suppression of tumor cell growth, migration and invasion. We further identified CAC1, a cell cycle-related protein expressed in colorectal cancer, as a miR-199a-5p target. We demonstrated that CAC1 is over-expressed in malignant tumors, and cellular CAC1 depletion resulted in cancer growth suppression. HCT-8 cells transfected with a miR-199a-5p mimic or inhibitor had a decrease or increase in CAC1 protein levels, respectively. The results of the luciferase reporter gene analysis demonstrated that CAC1 was a direct miR-199a-5p target. The high miR-199a-5p expression and low CAC1 protein expression reverse the tumor cell drug resistance. We conclude that miR-199a-5p can regulate CAC1 and function as a tumor suppressor in colorectal cancer. Therefore, the potential roles of deoxycholic acid in carcinogenesis are to decrease miR-199a-5p expression and/or increase the expression of CAC1, which contributes to tumorigenesis in patients with CRC. These findings suggest that miR-199a-5p is a useful therapeutic target for colorectal cancer.