Rho-GTPase activating-protein 18: a biomarker associated with good prognosis in invasive breast cancer

Scutellaria barbata D.Don extract regulates Ezrin-mediated triple negative breast cancer progress via suppressing the RhoA /ROCK1 signaling

Background

Triple-negative breast cancer (TNBC) lacks effective therapeutic targets. Scutellaria barbata D.Don (SB) has been revealed to have anti-breast cancer (BC) effect, but the effect of SB extract in TNBC is still unclear. Herein, this research delves into the underlying mechanism.

Methods

SB was extracted by solvent extraction, and the main components were identified using an Agilent 6,520 HPLC-Chip/Q-TOF (Chip/Q-TOF) MS system. In vitro cell experiments were conducted. The effects of SB extract alone, SB extract plus EGF, GSK alone, GSK plus Ezrin overexpression, or SB extract plus Ezrin overexpression on cell viability, invasion, migration, and apoptosis were examined by cell function experiments. The apoptosis- and RhoA/ROCK1 pathway-related protein levels were analyzed by western blot assay.

Results

Mass spectrometry analysis exhibited that SB extract mainly contains long-chain fatty acids and ursolic acid. SB extract mitigated TNBC cell biological phenotypes, apoptosis- and RhoA/ROCK1 pathway-related marker expressions, which were reversed by EGF. The further results found that GSK obviously weakens TNBC cell biological behaviors, apoptosis- and RhoA/ROCK1 signaling-related protein levels, while oe-Ezrin treatment reverses the effect of GSK on TNBC cells. Moreover, SB extract regulated Ezrin-mediated function of TNBC cells by impeding the RhoA/ROCK1 pathway.

Conclusion

Our findings demonstrated that SB extract regulated Ezrin-mediated proliferation, migration, invasion, and apoptosis of TNBC cells via suppressing the RhoA /ROCK1 signaling. Our results offer the experimental foundation for further investigation of the anti-cancer role of SB in TNBC cells.

Highlights

SB extract inhibits the biological phenotypes of TNBC cells.SB extract inhibits the biological behaviors of TNBC cells through the RhoA/ROCK1 pathway.SB extract modulates Ezrin-mediated TNBC cell proliferation, migration, invasion, and apoptosis via restraining the RhoA/ROCK1 signaling.

ARHGAP18 is Upregulated by Transcription Factor GATA1 Promotes the Proliferation and Invasion in Hepatocellular Carcinoma

Rho GTPase activating protein 18 (ARHGAP18), a member of the RhoGAP gene family that increases GTP hydrolysis and inhibits RhoGTPase, was recently discovered to play a role in the development of breast cancer. However, its exact biological role in hepatocellular carcinoma (HCC) remains unclear. In our present study, we comprehensively assessed ARHGAP18 expression and its correlation with the prognostic value of cancer patients in databases. Cell proliferation and colony formation assays were employed to monitor cell growth. Luciferase reporter assay, Chromatin immunoprecipitation qPCR (ChIP-qPCR), immunofluorescence were performed for mechanism research. The expression of genes and proteins was detected by real-time PCR and western blotting. According to the findings of this research, ARHGAP18 protein levels are increased in HCC tissues compared to adjacent nontumor tissues, and ARHGAP18 overexpression is associated with poor survival. The results of a gain- and loss-of-function experiment with HCC cells in vitro demonstrated that ARHGAP18 stimulated cell proliferation, migration, and invasion. Mechanistically, we found that the transcription factor GATA binding protein 1 (GATA1) could bind to the ARHGAP18 promoter and facilitate ARHGAP18 expression. Further studies revealed that the effects of ARHGAP18 silencing on HCCLM3 and Bel-7402 cells were blocked by GATA1 overexpression. In conclusion, GATA1-mediated ARHGAP18 up-regulation plays an important role in HCC tumorigenesis and might be a potential therapeutic target for HCC.

ARHGAP39 is a prognostic biomarker involved in immune infiltration in breast cancer

BACKGROUND

Current studies on the role of ARHGAP39 mainly focused on its effect on neurodevelopment. However, there are few studies on the comprehensive analysis of ARHGAP39 in breast cancer.

METHODS

ARHGAP39 expression level was analyzed based on the Cancer Genome Atlas (TCGA), the Genotype-Tissue Expression Project (GTEx), and the Clinical Proteomic Tumor Analysis Consortium (CPTAC) database and validated by qPCR in various cell lines and tumor tissues. The prognostic value was analyzed using Kaplan-Meier curve analysis. CCK-8 and transwell assays were conducted to identify the biological function of ARHGAP39 in tumorigenesis. Signaling pathways related to ARHGAP39 expression were identified by the GO and KEGG enrichment analysis and gene set enrichment analysis (GSEA). The correlations between ARHGAP39 and cancer immune infiltrates were investigated via TIMER, CIBERSORT, ESTIMATE and tumor-immune system interactions database (TISIDB).

RESULTS

ARHGAP39 was overexpressed in breast cancer and associated with poor survival outcomes. In vitro experiments revealed that ARHGAP39 could facilitate the proliferation, migration, and invasion capability of breast cancer cells. GSEA analysis showed that the main enrichment pathways of ARHGAP39 was immunity-related pathways. Considering the immune infiltration level, ARHGAP39 was negatively associated with infiltrating levels of CD8 + T cell and macrophage, and positively associated with CD4 + T cell. Furthermore, ARHGAP39 was significantly negatively correlated with immune score, stromal score, and ESTIMATE score.

CONCLUSIONS

Our findings suggested that ARHGAP39 can be used as a potential therapeutic target and prognostic biomarker in breast cancer. ARHGAP39 was indeed a determinant factor of immune infiltration.

Ras superfamily GTPase activating proteins in cancer: Potential therapeutic targets?

To search more therapeutic strategies for Ras-mutant tumors, regulators of the Ras superfamily involved in the GTP/GDP (guanosine triphosphate/guanosine diphosphate) cycle have been well concerned for their anti-tumor potentials. GTPase activating proteins (GAPs) provide the catalytic group necessary for the hydrolysis of GTPs, which accelerate the switch by cycling between GTP-bound active and GDP-bound inactive forms. Inactivated GAPs lose their function in activating GTPase, leading to the continuous activation of downstream signaling pathways, uncontrolled cell proliferation, and eventually carcinogenesis. A growing number of evidence has shown the close link between GAPs and human tumors, and as a result, GAPs are believed as potential anti-tumor targets. The present review mainly summarizes the critically important role of GAPs in human tumors by introducing the classification, function and regulatory mechanism. Moreover, we comprehensively describe the relationship between dysregulated GAPs and the certain type of tumor. Finally, the current status, research progress, and clinical value of GAPs as therapeutic targets are also discussed, as well as the challenges and future direction in the cancer therapy.

ARHGAP44 expression is associated with the metastasis of osteosarcoma and is a promising prognostic biomarker

Osteosarcoma (OS) is the most domain primary malignant bone tumor. Treatment resistances and metastases result in a decreasing 5-year overall survival rate of OS. However, Rho GTPase-activating protein 44 (ARHGAP44) has not been well studied in OS. The OS patient data were obtained from Therapeutically Applicable Research to Generate Effective Treatments and Gene Expression Omnibus databases. We utilized Survival and Survminer package for survival analysis based on Kaplan-Meier method. The association between ARHGAP44 expression with the prognosis of OS was determined by Wilcoxon rank-sum test and multivariate Cox regression analysis. The real-time polymerase chain reaction and western blotting were conducted to validate the results. Gene set enrichment analysis was done to find significant Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways. The OS sample ARHGAP44 expression level was significantly higher than that in normal samples, which was validated in cell lines. High ARHGAP44 expression was associated with metastasis of OS. The OS patients with high ARHGAP44 expression had worse prognosis compared with low ARHGAP44 expression OS patients. In total, 10 KEGG pathways significantly activated in high ARHGAP44 expression OS patients, such as Hedgehog signaling pathway, Steroid biosynthesis, and so on. In summary, high ARHGAP44 expression was closely correlated with the metastasis and poor prognosis of OS. ARHGAP44 was a potential prognostic biomarker for OS.

Development and clinical validation of a novel 9-gene prognostic model based on multi-omics in pancreatic adenocarcinoma

The prognoses of patients with pancreatic adenocarcinoma (PAAD) remain poor due to the lack of biomarkers for early diagnosis and effective prognosis prediction. RNA sequencing, single nucleotide polymorphism, and copy number variation data were downloaded from The Cancer Genome Atlas (TCGA). Univariate Cox regression was used to identify prognosis-related genes. GISTIC 2.0 was used to identify significantly amplified or deleted genes, and Mutsig 2.0 was used to analyze the mutation data. The Lasso method was used to construct a risk prediction model. The Rms package was used to evaluate the overall predictive performance of the signature. Finally, Western blot and polymerase chain reaction were performed to evaluate gene expression. A total of 54 candidate genes were obtained after integrating the genomic mutated genes and prognosis-related genes. The Lasso method was used to ascertain 9 characteristic genes, including UNC13B, TSPYL4, MICAL1, KLHDC7B, KLHL32, AIM1, ARHGAP18, DCBLD1, and CACNA2D4. The 9-gene signature model was able to help stratify samples at risk in the training and external validation cohorts. In addition, the overall predictive performance of our model was found to be superior to that of other models. KLHDC7B, AIM1, DCBLD1, TSPYL4, and MICAL1 were significantly highly expressed in tumor tissues compared to normal tissues. ARHGAP18 and CACNA2D4 had no difference in expression between tumor and normal tissues. UNC13B and KLHL32 expression in the normal group was higher than in the tumor group. The 9-gene signature constructed in this study can be used as a novel prognostic marker to predict the survival of patients with pancreatic adenocarcinoma.

A Screen for PKN3 Substrates Reveals an Activating Phosphorylation of ARHGAP18

Protein kinase N3 (PKN3) is a serine/threonine kinase implicated in tumor progression of multiple cancer types, however, its substrates and effector proteins still remain largely understudied. In the present work we aimed to identify novel PKN3 substrates in a phosphoproteomic screen using analog sensitive PKN3. Among the identified putative substrates we selected ARHGAP18, a protein from RhoGAP family, for validation of the screen and further study. We confirmed that PKN3 can phosphorylate ARHGAP18 in vitro and we also characterized the interaction of the two proteins, which is mediated via the N-terminal part of ARHGAP18. We present strong evidence that PKN3-ARHGAP18 interaction is increased upon ARHGAP18 phosphorylation and that the phosphorylation of ARHGAP18 by PKN3 enhances its GAP domain activity and contributes to negative regulation of active RhoA. Taken together, we identified new set of potential PKN3 substrates and revealed a new negative feedback regulatory mechanism of Rho signaling mediated by PKN3-induced ARHGAP18 activation.

Rho GTPases: Big Players in Breast Cancer Initiation, Metastasis and Therapeutic Responses

Rho GTPases, a family of the Ras GTPase superfamily, are key regulators of the actin cytoskeleton. They were originally thought to primarily affect cell migration and invasion; however, recent advances in our understanding of the biology and function of Rho GTPases have demonstrated their diverse roles within the cell, including membrane trafficking, gene transcription, migration, invasion, adhesion, survival and growth. As these processes are critically involved in cancer initiation, metastasis and therapeutic responses, it is not surprising that studies have demonstrated important roles of Rho GTPases in cancer. Although the majority of data indicates an oncogenic role of Rho GTPases, tumor suppressor functions of Rho GTPases have also been revealed, suggesting a context and cell-type specific function for Rho GTPases in cancer. This review aims to summarize recent progresses in our understanding of the regulation and functions of Rho GTPases, specifically in the context of breast cancer. The potential of Rho GTPases as therapeutic targets and prognostic tools for breast cancer patients are also discussed.

Use of peripheral blood transcriptomic biomarkers to distinguish high-grade cervical squamous intraepithelial lesions from low-grade lesions

It is crucial to classify cervical lesions into high-grade squamous intraepithelial lesions (HSILs) and low-grade SILs (LSILs), as LSILs are conservatively treated by observation, based on an expectation of natural regression, whereas HSILs usually require electrosurgical excision. In the present study, peripheral blood gene expression profiles were analyzed to identify transcriptomic biomarkers distinguishing HSILs from LSILs. A total of 102 blood samples were collected from women with cervical SILs (66 HSIL and 36 LSIL) for microarray hybridization. Candidate gene signatures were identified using AdaBoost algorithms, and a predictive model was constructed using logistic regression to differentiate HSILs from LSILs. To correct for possible bias as a result of the limited sample size and to verify the stability of the predictive model, a two-fold cross validation and null set analysis was conducted over 1,000 iterations. The functions of the transcriptomic biomarkers were then analyzed to elucidate the pathogenesis of cervical SIL. A total of 10 transcriptomic genes (STMN3, TRPC4AP, DYRK2, AGK, KIAA0319L, GRPEL1, ZFC3H1, LYL1, ITGB1 and ARHGAP18) were identified. The predictive model based on the 10-gene panel exhibited well-discriminated power. A cross validation process using known disease status exhibited almost the same performance as that of the predictive model, whereas null-set analysis with randomly reassigned disease status exhibited much lower predictive performance for distinguishing HSILs from LSILs. These biomarkers were involved in the 'Rho GTPase cycle', 'mitochondrial protein import', 'oncogenic MAPK signaling', 'integrin cell surface interaction' and 'signaling by BRAF and RAF fusions'. In conclusion, peripheral blood gene expression analysis is a promising method for distinguishing HSILs from LSILs. The present study proposes 10 candidate genes that could be used in the future as diagnostic biomarkers and potential therapeutic targets for cervical SILs. A simple, non-invasive blood test would be clinically useful in the diagnosis and classification of patients with cervical SILs.

The prognostic significance of BMI1 expression in invasive breast cancer is dependent on its molecular subtypes

Purpose

BMI1, which is a major component of the polycomb group complex 1, is an essential epigenetic repressor of multiple regulatory genes and has been identified as a cancer stem cell (CSC) marker in several cancers. However, its role in breast cancer (BC) remains to be defined. In this study, we have evaluated the prognostic significance of BMI1 among the different molecular subtypes and assessed its association with other breast CSC markers (BCSC).

Material and method

BMI1 copy number and mRNA was assessed in large and well-characterised cohorts of early-stage BC patients [METABRIC (n = 1980) and the Bc-GenExMiner (n = 9616) databases]. BMI1 protein expression was assessed using tissue microarray and immunohistochemistry in a cohort of 870 invasive BC patients with long-term outcome data and the expression of a panel of BCSC markers was monitored.

Result

BMI1 expression, prognostic significance and its association with BCSC markers were differed between molecular classes. In the luminal oestrogen receptor-positive (ER+) BC, BMI1 showed significantly higher expression compared to ER− tumours. BMI1 showed positive correlation with favourable prognostic features and it was negatively associated with the expression of key BCSC markers (ALDH1A1, CD24, CD44, CD133, SOX10 and SOX9). High expression of BMI1 was associated with longer breast cancer-specific survival (BCSS) independent of other prognostic variables. In the basal triple negative BC subtype, BMI1 expression showed positive association with CD133 and SOX10 and it was significantly associated with shorter BCSS.

Conclusion

High BMI1 expression is associated with clinicopathological variables and outcome in BC. However, this association is dependent on the molecular subtypes. Further functional assessment to detect its underlying mechanistic roles in BC subtypes is warranted.

Electronic supplementary material

The online version of this article (10.1007/s10549-020-05719-x) contains supplementary material, which is available to authorized users.

LncRNA CDKN2BAS predicts poor prognosis in patients with hepatocellular carcinoma and promotes metastasis via the miR-153-5p/ARHGAP18 signaling axis

Background: Growing evidence shows that long noncoding RNAs (lncRNAs) play a crucial role in cancer progression. However, whether lncRNA CDKN2BAS is involved in human hepatocellular carcinoma (HCC) metastasis remains unclear.

Methods: Human lncRNA microarray analysis was performed to detect differential expression levels of lncRNAs in metastatic HCC tissues. Effects of CDKN2BAS on cell proliferation, migration, and apoptosis were determined by MTT assay, colony formation assay, migration assay, scratch assay, and flow cytometry. The xenograft experiment was used to confirm the effect of CDKN2BAS on HCC in vivo. qRT-PCR and Western blot were performed to determine the expression levels of mRNAs and proteins. Luciferase reporter assay was used to identify the specific target relationships.

Results: CDKN2BAS was remarkably up-regulated in metastatic HCC tissues compared with the adjacent non-tumor tissues. CDKN2BAS promotes HCC cell growth and migration in vitro and in vivo. Additionally, CDKN2BAS upregulated the expression of Rho GTPase activating protein 18 (ARHGAP18) by sponging microRNA-153-5p (miR-153-5p), and thus promoted HCC cell migration. Besides, CDKN2BAS downregulated the expression of Krüppel-like factor 13 (KLF13) and activated MEK-ERK1/2 signaling, thus reducing apoptosis in HCC cells.

Conclusions: Our study revealed that lncRNA CDKN2BAS promotes HCC metastasis by regulating the miR-153-5p/ARHGAP18 signaling.

Clinicopathological significance of lipocalin 2 nuclear expression in invasive breast cancer

PURPOSE

The epithelial-mesenchymal transition (EMT) plays a key role in breast cancer progression and metastasis. Lipocalin 2 (LCN2) is involved in the regulation of EMT. The aim of this study was to investigate the clinicopathological significance of LCN2 expression in breast cancer.

METHODS

The expression of LCN2 protein was immunohistochemically assessed in two well-characterised annotated cohorts of breast cancer (discovery cohort, n = 612; validation cohort, n = 1363). The relationship of LCN2 expression and subcellular location with the clinicopathological factors and outcomes of patients was analysed.

RESULTS

Absent or reduced nuclear LCN2 expression was associated with features of aggressive behaviour, including high histological grade, high Nottingham Prognostic Index, high Ki67 labelling index, hormone receptor negativity and human epidermal growth factor receptor 2 positivity. The high cytoplasmic expression of LCN2 was correlated with lymph node positivity. The nuclear downregulation of LCN2 was correlated with the overexpression of EMT associated proteins (N-cadherin and Twist-related protein 2) and basal biomarkers (cytokeratin 5/6 and epidermal growth factor receptor). Unlike the cytoplasmic expression of LCN2, the loss of nuclear expression was a significant predictor of poor outcome. The combinatorial expression tumours with high cytoplasmic and low nuclear expression were associated with the worst prognosis.

CONCLUSIONS

Tumour cell expression of LCN2 plays a role in breast cancer progression with loss of its nuclear expression which is associated with aggressive features and poor outcome. Further functional analysis is warranted to confirm the relationship between the subcellular localisation LCN2 and behaviour of breast cancer.

Bioinformatics analysis of potential therapeutic targets among ARHGAP genes in breast cancer

GTPase activating proteins (RhoGAPs) serve significant roles in multiple aspects of tumor biology. Genes encoding RhoGAPs (ARHGAP), which switch off Rho-like GTPases, are responsible for breast cancer biogenesis. However, the identification of suitable and novel biomarkers for precision treatment and prognosis remains challenging. The present study aimed to evaluate the expression of ARHGAP family genes in breast cancer and investigate the survival data using the Oncomine, Kaplan-Meier Plotter, bcGenExMiner and cBioPortal online databases. The results demonstrated low expression of ARHGAP6, 7, 10, 14, 19, 23 and 24 and high expression of ARHGAP9, 11, 15, 18 and 30 in patients with breast cancer compared with that in healthy individuals. The survival analysis revealed that low expression levels of ARHGAP6, 7 and 19 were associated with poor relapse-free survival (RFS) and overall survival (OS), whereas high expression levels of ARHGAP9, 15 and 30 were associated with preferable RFS and OS. Metastatic relapse data demonstrated that higher expression of ARHGAP9, 15, 18, 19, 25 and 30 were associated with better prognosis and increased expression of ARHGAP11A and 14 exerted negative effects on patient prognosis. The overlapping genes ARHGAP9, 15, 19 and 30 obtained from these bioinformatics analysis tools exhibited significant association with clinical parameters including age, the presence of estrogen receptor, progesterone receptor and epidermal growth factor receptor-2, Scarff-Bloom-Richardson grade and Nottingham prognostic index. In conclusion, bioinformatics analysis revealed that ARHGAP9, 15, 19 and 30, but not other ARHGAP family genes may be promising targets with prognostic value and biological function for precision treatment of breast cancer.

The role of microtubules in the regulation of epithelial junctions

The cytoskeleton is crucially important for the assembly of cell-cell junctions and the homeostatic regulation of their functions. Junctional proteins act, in turn, as anchors for cytoskeletal filaments, and as regulators of cytoskeletal dynamics and signalling proteins. The cross-talk between junctions and the cytoskeleton is critical for the morphogenesis and physiology of epithelial and other tissues, but is not completely understood. Microtubules are implicated in the delivery of junctional proteins to cell-cell contact sites, in the differentiation and spatial organization of the cytoplasm, and in the stabilization of the barrier and adhesive functions of junctions. Here we focus on the relationships between microtubules and junctions of vertebrate epithelial cells. We highlight recent discoveries on the molecular underpinnings of microtubule-junction interactions, and report new data about the interaction of cingulin and paracingulin with microtubules. We also propose a possible new role of junctions as “molecular sinks” for microtubule-associated signalling proteins.

Saccharomyces cerevisiae-like 1 (SEC14L1) is a prognostic factor in breast cancer associated with lymphovascular invasion

Lymphovascular invasion is strongly related to breast cancer metastasis. However, the underlying mechanisms of lymphovascular invasion and its driver molecules in breast cancer remain to be defined. In this study, we explore differential expression of genes in large molecularly characterized and clinically annotated datasets of invasive breast cancer patients (n = 8056) coupled with histological review and strict definition for lymphovascular invasion status. The METABRIC series was used to identify genes associated with lymphovascular invasion, as defined using hematoxylin and eosin staining supplemented by immunohistochemistry, at the genomic/transcriptomic levels. Saccharomyces cerevisiae-like 1 (SEC14L1) was identified as one of the most significant genes associated with lymphovascular invasion. The prognostic significance of SEC14L1 gene copy number and mRNA expression was further investigated in the METABRIC series and externally validated using the Breast Cancer Gene-Expression Miner v4.0. Protein expression of SEC14L1 was also assessed using immunohistochemistry in series of early stage breast cancer using tissue microarrays. SEC14L1 gene copy number gain was significantly associated with high histological grade and poor outcome. SEC14L1 mRNA expression showed positive association with higher grade, lymph node metastasis, and poor outcome. SEC14L1 protein overexpression was significantly associated with lymphovascular invasion (p < 0.0001), higher grade (p = 0.011), HER2 positivity (p = 0.036), and shorter survival (p = 0.00075). Our findings specify SEC14L1 as an independent prognostic factor in breast cancer. Its association, at both transcriptome and protein expression levels, with lymphovascular invasion and outcome could imply an important role in tumor progression. A further mechanistic insight into its molecular roles including potential therapeutic utility is warranted.