Association between clinical characteristics and expression abundance of RTKN gene in human bladder carcinoma tissues from Chinese patients

Identification of tumor-antigen signatures and immune subtypes for mRNA vaccine selection in muscle-invasive bladder cancer

BACKGROUND

Muscle-invasive bladder cancer continues to lack reliable diagnostic and prognostic biomarkers. Recently, tumor vaccines targeting specific molecules have emerged as a promising treatment in inhibiting tumor progression, which was rekindled under the background of coronavirus disease-2019 pandemic. However, the application of mRNA vaccine targeting muscle-invasive bladder cancer-specific antigens remains limited, and there has been a lack of comprehensive studies or validations to identify suitable patient subgroups for vaccination. This study aims to explore novel muscle-invasive bladder cancer antigen signatures to identify patients most likely to benefit from vaccination.

METHODS

Gene expression profiles of muscle-invasive bladder cancer samples, along with corresponding clinical data, were retrieved from the Cancer Genome Atlas Program. The least absolute shrinkage and selection operator model was applied to develop signatures for stratifying muscle-invasive bladder cancer patients. Prognostic accuracy of each factor was assessed using receiver operating characteristic analysis. Tumor Immune Estimation Resource was employed to visualize the relationship between the proportion of antigen-presenting cells and the expression of selected genes. The CIBERSORT and WGCNA R packages were used to identify differences in immune infiltration levels across muscle-invasive bladder cancer subgroups. Additionally, the STRING database and Cytoscape were used to construct the protein-protein interaction network. CCK-8 and colony formation assays were employed in invitro experiments.

RESULTS

A total of 49 potential tumor antigens were identified. Using least absolute shrinkage and selection operator Cox regression, 14 tumor antigens were selected to develop a risk evaluation signature. The risk score signature can serve as a valuable tool for predicting the outcomes of muscle-invasive bladder cancer patients. Based on differential clinical, molecular, and immune-related gene profiles, muscle-invasive bladder cancer patients were classified into 2 subtypes: the immune "cold" subtype (immune score 1) and the immune "hot" subtype (immune score 2). The immune score signature, developed using a logistic score model, effectively distinguishes between patients more likely to belong to immune score 1 or 2. Notably, patients with a high risk score exhibited a higher proportion of immune score 2 compared to those with a low risk score. Additionally, the prognostic accuracy was significantly enhanced when the risk score and immune score were combined. Different tumor subtypes displayed distinct immune landscapes and signaling pathways. Moreover, novel tumor antigens associated with oxidative stress were identified.

CONCLUSION

The risk score and immune score signatures based on tumor antigens have identified potential effective neo-antigens for the development of mRNA vaccines targeting muscle-invasive bladder cancer. Patients with low risk score and immune score 1 subtype are more likely to benefit from mRNA vaccination. Additionally, this study highlights the critical role of oxidative stress in modulating the efficacy of the mRNA vaccine.

Conjoint analysis for hepatic carcinoma with hub genes and multi-slice spiral CT

Hepatic carcinoma (HCC) is a common malignant tumor, with insidious onset and poor prognosis. However, more hub genes associated with hepatocellular carcinoma are unknown. And there are few researches about the conjoint analysis with the hub genes and multi-slice spiral computerized tomography (CT).A total of 100 HCC participates were recruited, who all received the examination of multi-slice spiral CT. Two expression profile data sets (GSE101728 and GSE101685) were downloaded from the Gene Expression Omnibus (GEO) database. GEO2R can perform a command to compare gene expression profiles between groups in order to identify differently expressed genes (DEGs). Functional annotation of DEGs via Gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis was made with Database for Annotation, Visualization, and Integrated Discovery (DAVID). Construction and analysis of protein-protein interaction network were performed. Furthermore, the study could mine of hub genes and explore the correlation with the multi-slice CT. Real-time quantitative polymerase chain reaction (RT-qPCR) assay was used the exam the expression of hub genes.A total of 10 genes were identified as hub genes with degrees ≥10. The hub genes (NIMA Related Kinase 2 [NEK2], Anillin Actin Binding Protein [ANLN], DNA Topoisomerase II Alpha [TOP2A], Centromere Protein F [CENPF], Assembly Factor For Spindle Microtubules [ASPM], Cell Division Cycle 20 [CDC20], Cyclin Dependent Kinase 1 [CDK1], Cyclin B1 [CCNB1], Epithelial Cell Transforming 2 [ECT2], Cyclin B2 [CCNB2]) were identified from the Molecular Complex Detection (MCODE) network. These hub genes were highly expressed in HCC tissues, and when these genes were highly expressed, the survival prognosis of HCC patients was poor. The type of CT enhancement was significantly related with the expression of NEK2 (P < .001), ANLN (P < .001), and TOP2A (P = .006).The combination between the gene expression (NEK2, ANLN, and TOP2A) and type of CT enhancement might provide a new idea for future basic research and targeted therapy of HCC.

A robust 11-genes prognostic model can predict overall survival in bladder cancer patients based on five cohorts

Background

Bladder cancer is the tenth most common cancer globally, but existing biomarkers and prognostic models are limited.

Method

In this study, we used four bladder cancer cohorts from The Cancer Genome Atlas and Gene Expression Omnibus databases to perform univariate Cox regression analysis to identify common prognostic genes. We used the least absolute shrinkage and selection operator regression to construct a prognostic Cox model. Kaplan-Meier analysis, receiver operating characteristic curve, and univariate/multivariate Cox analysis were used to evaluate the prognostic model. Finally, a co-expression network, CIBERSORT, and ESTIMATE algorithm were used to explore the mechanism related to the model.

Results

A total of 11 genes were identified from the four cohorts to construct the prognostic model, including eight risk genes (SERPINE2, PRR11, DSEL, DNM1, COMP, ELOVL4, RTKN, and MAPK12) and three protective genes (FABP6, C16orf74, and TNK1). The 11-genes model could stratify the risk of patients in all five cohorts, and the prognosis was worse in the group with a high-risk score. The area under the curve values of the five cohorts in the first year are all greater than 0.65. Furthermore, this model's predictive ability is stronger than that of age, gender, grade, and T stage. Through the weighted co-expression network analysis, the gene module related to the model was found, and the key genes in this module were mainly enriched in the tumor microenvironment. B cell memory showed low infiltration in high-risk patients. Furthermore, in the case of low B cell memory infiltration and high-risk score, the prognosis of the patients was the worst.

Conclusion

The proposed 11-genes model is a promising biomarker for estimating overall survival in bladder cancer. This model can be used to stratify the risk of bladder cancer patients, which is beneficial to the realization of individualized treatment.

Association of leukocyte DNA methylation changes with dietary folate and alcohol intake in the EPIC study

Background

There is increasing evidence that folate, an important component of one-carbon metabolism, modulates the epigenome. Alcohol, which can disrupt folate absorption, is also known to affect the epigenome. We investigated the association of dietary folate and alcohol intake on leukocyte DNA methylation levels in the European Prospective Investigation into Cancer and Nutrition (EPIC) study. Leukocyte genome-wide DNA methylation profiles on approximately 450,000 CpG sites were acquired with Illumina HumanMethylation 450K BeadChip measured among 450 women control participants of a case-control study on breast cancer nested within the EPIC cohort. After data preprocessing using surrogate variable analysis to reduce systematic variation, associations of DNA methylation with dietary folate and alcohol intake, assessed with dietary questionnaires, were investigated using CpG site-specific linear models. Specific regions of the methylome were explored using differentially methylated region (DMR) analysis and fused lasso (FL) regressions. The DMR analysis combined results from the feature-specific analysis for a specific chromosome and using distances between features as weights whereas FL regression combined two penalties to encourage sparsity of single features and the difference between two consecutive features.

Results

After correction for multiple testing, intake of dietary folate was not associated with methylation level at any DNA methylation site, while weak associations were observed between alcohol intake and methylation level at CpG sites cg03199996 and cg07382687, with q_val = 0.029 and q_val = 0.048, respectively. Interestingly, the DMR analysis revealed a total of 24 and 90 regions associated with dietary folate and alcohol, respectively. For alcohol intake, 6 of the 15 most significant DMRs were identified through FL.

Conclusions

Alcohol intake was associated with methylation levels at two CpG sites. Evidence from DMR and FL analyses indicated that dietary folate and alcohol intake may be associated with genomic regions with tumor suppressor activity such as the GSDMD and HOXA5 genes. These results were in line with the hypothesis that epigenetic mechanisms play a role in the association between folate and alcohol, although further studies are warranted to clarify the importance of these mechanisms in cancer.

Electronic supplementary material

The online version of this article (10.1186/s13148-019-0637-x) contains supplementary material, which is available to authorized users.

Expression and biological function of rhotekin in gastric cancer through regulating p53 pathway

Background/aim

Gastric cancer (GC) is one of a most threatening cancer globally. Rhotekin (RTKN), a Rho effector, has been reported to be upregulated in GC tissues. This study aimed to investigate the underlying regulatory roles of RTKN in the biological behavior of GC.

Methods

Real-time PCR and Western blotting were carried out to detect the mRNA and protein expression, respectively. Cell Counting Kit-8 and xenograft nude mice model were used to evaluate cell proliferation. Flow cytometry analysis was performed to assess cell cycle distribution and cell apoptosis.

Results

RTKN had high expression level in GC compared with normal tissues. RTKN expression strongly associated with tumor size, TNM stage, lymphnode metastasis and the poor prognosis of patients with GC. Downregulation of RTKN significantly repressed GC cell proliferation, but increased cell population in G1/S phase and induced cell apoptosis. Moreover, the RTKN expression level was related to the p53 signaling pathway and histone deacetylase (HDAC) Class I pathway. RTKN knockdown caused a notable increment in the acetylation level of p53 (Lys382), and the expression of p53-target genes (p21, Bax, and PUMA), as well as a reduction in the expression of a potential deacetylase for p53, HDAC1. Notably, downregulation of HDAC1 had similar effects as RTKN knockdown, and RTKN overexpression could hardly abrogate the effects of HDAC1 knockdown on GC cells.

Conclusion

RTKN could work as an oncogene via regulating HDAC1/p53 and may become a promising treatment strategy for GC.

Functions of Rhotekin, an Effector of Rho GTPase, and Its Binding Partners in Mammals

Rhotekin is an effector protein for small GTPase Rho. This protein consists of a Rho binding domain (RBD), a pleckstrin homology (PH) domain, two proline-rich regions and a C-terminal PDZ (PSD-95, Discs-large, and ZO-1)-binding motif. We, and other groups, have identified various binding partners for Rhotekin and carried out biochemical and cell biological characterization. However, the physiological functions of Rhotekin, per se, are as of yet largely unknown. In this review, we summarize known features of Rhotekin and its binding partners in neuronal tissues and cancer cells.

Knockdown of Rhotekin 2 expression suppresses proliferation and induces apoptosis in colon cancer cells

Colon cancer is one of the most common malignant tumors in the human body, ranking second as a gastrointestinal tumor. It has a high incidence in Europe, America and China and more than 1 million new cases of colon cancer are reported worldwide each year. The incidence of colon cancer in China has increased from 12/0.1 million in the early 1970s to 56/0.1 million at present with an annual growth rate of 4.2%, which far exceeds the international level (2%). Rhotekin (RTKN) 2, a Rho-guanosine triphosphatase (GTPase) effector, has been reported to be anti-apoptotic. However, the molecular mechanism underlying the biological function of RTKN2 in colon cancer remains unknown. The present study investigated whether the mRNA expression level of RTKN2 was markedly higher in 30 human colon cancer specimens compared with adjacent non-cancerous tissues. The results showed that the protein expression level of RTKN2 was significantly higher in SW480 and HCT116 cells, compared with HIEC cells. Knockdown of RTKN2 in the SW480 and HCT116 colon cancer cells, by lentivirus-mediated RNA interference led to the notable inhibition of cell proliferation and cell cycle progression, by reducing the expression levels of the PCDA, Cyclin D1 and c-myc cell cycle-associated proteins. The inhibitory effect of RTKN2 silencing on the proliferation of colon cancer cells may be partially realized by inhibiting the Wnt/β-catenin signaling pathway. Furthermore, the silencing of RTKN2 in the cells induced apoptosis by reducing the expression level of Bax and increasing the expression level of Bcl2. These results show that RTKN2 is involved in the carcinogenesis and progression of human colon cancer, indicating that RTKN2 may be a molecular target in colon cancer therapy.

MicroRNA-152 inhibits tumor cell growth by directly targeting RTKN in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is the most common form of adult liver cancer and accounts for approximately 90% of all cases of primary liver cancer annually. Rhotekin (RTKN), which functions as a cancer promoter, can be frequently detected in many human cancers, including gastric cancer, colorectal carcinoma and bladder carcinoma. The aim of this study was to investigate the role of RTKN in HCC. Using HCC cells and tissues from patients with liver cancer, we demonstrated that RTKN was significantly increased in HCC. To examine the effect of RTKN on HCC, RTKN overexpressed or silenced HepG2 and Hep3B cells were constructed. Cell proliferation and apoptosis were measured by RT-PCR and flow cytometry. The results showed that RTKN can function as an oncogene and promote the proliferation, while inhibiting apoptosis, of HepG2 and Hep3B cells. Furthermore, we identified that RTKN is a direct gene target of miR-152. miR-152 can reverse the growth promoting effect of RTKN on HCC cells through G2/M phase arrest and nuclear factor-κB (NF-κB) signal inhibition. In conclusion, our research identified that miRNA-152 can inhibit tumor cell growth by targeting RTKN in HCC.

Inhibition of rhotekin exhibits antitumor effects in lung cancer cells

Lung cancer is the leading cause for cancer-related death, however, the pathogenesis mechanism is poorly understood. Although the rhotekin (RTKN) gene has been reported to encode an effector for the Rho protein that has critical roles in regulating cell growth, the role of RTKN in lung cancer has not been investigated. In clinical lung cancer patient tumor samples, we identified that the RTKN gene expression level was significantly higher in tumor tissues compared to that of the adjacent normal tissues. To investigate the molecular mechanisms of RTKN in lung cancer, we established RTKN stable knock-down A549 and SPC-A-1 lung adenocarcinoma cell lines using lentiviral transfection of RTKN shRNA and evaluated the antitumor effects. The results showed that RTKN knock-down inhibited lung adenocarcinoma cell viability, induced S phase arrest and increased cell apoptosis. In addition, RTKN knock-down inhibited lung cancer cell invasion and adhesion. Further analysis showed that the S phase promoting factors cyclin-dependent kinase (CDK)1 and CDK2 levels were decreased in RTKN knock-down cells, and that the DNA replication initiation complex proteins Minichromosome maintenance protein complex (MCM)2 and MCM6 were decreased as well in RTKN knock-down cells. These results indicated that the RTKN protein was associated with lung cancer in clinic samples and exerted anticancer activity in lung adenocarcinoma cells through inhibiting cell cycle progression and the DNA replication machinery. These findings suggest that RTKN inhibition may be a novel therapeutic strategy for lung adenocarcinoma.

Protein kinase D regulates RhoA activity via rhotekin phosphorylation

The members of the protein kinase D (PKD) family of serine/threonine kinases are major targets for tumor-promoting phorbol esters, G protein-coupled receptors, and activated protein kinase C isoforms (PKCs). The expanding list of cellular processes in which PKDs exert their function via phosphorylation of various substrates include proliferation, apoptosis, migration, angiogenesis, and vesicle trafficking. Therefore, identification of novel PKD substrates is necessary to understand the profound role of this kinase family in signal transduction. Here, we show that rhotekin, an effector of RhoA GTPase, is a novel substrate of PKD. We identified Ser-435 in rhotekin as the potential site targeted by PKD in vivo. Expression of a phosphomimetic S435E rhotekin mutant resulted in an increase of endogenous active RhoA GTPase levels. Phosphorylation of rhotekin by PKD2 modulates the anchoring of the RhoA in the plasma membrane. Consequently, the S435E rhotekin mutant displayed enhanced stress fiber formation when expressed in serum-starved fibroblasts. Our data thus identify a novel role of PKD as a regulator of RhoA activity and actin stress fiber formation through phosphorylation of rhotekin.