Rho GTPase Activating Protein 24 (ARHGAP24) Silencing Promotes Lung Cancer Cell Migration and Invasion by Activating β-Catenin Signaling

Mechanisms of Rho GTPases in regulating tumor proliferation, migration and invasion

The occurrence of most cancers is due to the clonal proliferation of tumor cells, immune evasion, and the ability to spread to other body parts. Rho GTPases, a family of small GTPases, are key regulators of cytoskeleton reorganization and cell polarity. Additionally, Rho GTPases are key proteins that induce the proliferation and metastasis of tumor cells. This review focuses on the complex regulatory mechanisms of Rho GTPases, exploring their critical role in promoting tumor cell proliferation and dissemination. Regarding tumor cell proliferation, attention is given to the role of Rho GTPases in regulating the cell cycle and mitosis. In terms of tumor cell dissemination, the focus is on the role of Rho GTPases in regulating cell migration and invasion. Overall, this review elucidates the mechanisms of Rho GTPases members in the development of tumor cells, aiming to provide theoretical references for the treatment of mammalian tumor diseases and related applications.

HAGLR, A Long Non-coding RNA of Potential Tumor Suppressive Function in Clear Cell Renal Cell Carcinoma: Diagnostic and Prognostic Implications

Research works suggested the role of long non-coding RNAs (lncRNAs) in pathogenesis of clear cell renal cell carcinoma (ccRCC). lncRNA HAGLR is studied in several malignancies, but not in ccRCC. From The Cancer Genome Atlas Kidney Renal Clear Cell Carcinoma (TCGA-KIRC) dataset, we analyzed molecular alterations of HAGLR and constructed a competitive endogenous RNA (ceRNA) network with related miRNAs and mRNAs. Gene Ontology analysis was done to identify important pathways enriched with HAGLR recovered mRNAs. Clinical importance of HAGLR and related mRNAs was assessed and, the impact of selected mRNA-encoding genes on tumor immune infiltration was studied using TIMER. HAGLR expression was reduced in ccRCC than in normal kidneys, and correlated significantly with gene promoter methylation. Low HAGLR level in tumors showed diagnostic potency, and was associated with clinicopathological parameters (stage/grade/metastasis) and poor patient survival. The HAGLR-associated ceRNA network constituted 13 miRNAs and 23 mRNAs differentially expressed in the TCGA-KIRC dataset. From HAGLR recovered mRNA-encoding genes, we developed a 5-gene (PAQR5, ARHGAP24, HABP4, PDLIM5, and RPS6KA2) prognostic signature in the training dataset and validated it in testing as well as entire datasets. The expression level of signature genes showed negative correlation with tumor infiltration of immune cells having adverse impact on ccRCC prognosis and also with tumor derived chemokines facilitating the infiltration. In conclusion, HAGLR seemed to play a tumor suppressive role in ccRCC. HAGLR and associated gene signature may have implementation in improving existing prognostic measure and developing effective immunotherapeutic strategies for ccRCC.

A t(4;13)(q21;q14) translocation in B-cell chronic lymphocytic leukemia causing concomitant homozygous DLEU2/miR15a/miR16-1 and heterozygous ARHGAP24 deletions

13q14 deletion is the most recurrent chromosomal aberration reported in B-CLL, having a favorable prognostic significance when occurring as the sole cytogenetic alteration. However, its clinical outcome is also related to the deletion size and number of cells with the del(13)(q14) deletion. In 10% of cases, 13q14 deletion arises following a translocation event with multiple partner chromosomes, whose oncogenic impact has not been investigated so far due to the assumption of a possible role as a passenger mutation. Here, we describe a t(4;13)(q21;q14) translocation occurring in a B-CLL case from the diagnosis to spontaneous regression. FISH and SNP-array analyses revealed a heterozygous deletion at 4q21, leading to the loss of the Rho GTPase Activating Protein 24 (ARHGAP24) tumor suppressor gene, down-regulated in the patient RNA, in addition to the homozygous deletion at 13q14 involving DLEU2/miR15a/miR16-1 genes. Interestingly, targeted Next Generation Sequencing analysis of 54 genes related to B-CLL indicated no additional somatic mutation in the patient, underlining the relevance of this t(4;13)(q21;q14) aberration in the leukemogenic process. In all tested RNA samples, RT-qPCR experiments assessed the downregulation of the PCNA, MKI67, and TOP2A proliferation factor genes, and the BCL2 anti-apoptotic gene as well as the up-regulation of TP53 and CDKN1A tumor suppressors, indicating a low proliferation potential of the cells harboring the aberration. In addition, RNA-seq analyses identified four chimeric transcripts (ATG4B::PTMA, OAZ1::PTMA, ZFP36::PTMA, and PIM3::BRD1), two of which (ATG4B::PTMA and ZFP36::PTMA) failed to be detected at the remission, suggesting a possible transcriptional remodeling during the disease course. Overall, our results indicate a favorable prognostic impact of the described chromosomal aberration, as it arises a permissive molecular landscape to the spontaneous B-CLL regression in the patient, highlighting ARHGAP24 as a potentially relevant concurrent alteration to the 13q14 deletion in delineating B-CLL disease evolution.

A Single-Nucleotide Polymorphism in the Promoter of Porcine ARHGAP24 Gene Regulates Aggressive Behavior of Weaned Pigs After Mixing by Affecting the Binding of Transcription Factor p53

Pigs are important biomedical model animals for the study of human neurological diseases. Similar to human aggressive behavior in children and adolescents, weaned pigs also show more aggressive behavior after mixing, which has negative effects on animal welfare and growth performance. The identification of functional single-nucleotide polymorphisms (SNPs) related to the aggressive behavior of pigs would provide valuable molecular markers of the aggressive behavioral trait for genetic improvement program. The Rho GTPase–activating protein 24 (ARHGAP24) gene plays an important role in regulating the process of axon guidance, which may impact the aggressive behavior of pigs. By resequencing the entire coding region, partially adjacent introns and the 5′ and 3′ flanking regions, six and four SNPs were identified in the 5′ flanking region and 5′ untranslated region (UTR) of the porcine ARHGAP24 gene, respectively. Association analyses revealed that nine SNPs were significantly associated with aggressive behavioral traits (p = < 1.00 × 10^–4–4.51 × 10^–2), and their haplotypes were significantly associated with aggressive behavior (p = < 1.00 × 10^–4–2.99 × 10^–2). The core promoter region of the ARHGAP24 gene has been identified between −670 and −1,113 bp. Furthermore, the luciferase activity of allele A of rs335052970 was significantly less than that of allele G, suggesting that the transcriptional activity of the ARHGAP24 gene was inhibited by allele A of rs335052970. It was identified that the transcription factor p53 bound to the transcription factor binding sites (TFBSs) containing allele A of rs335052970. In porcine primary neural cells, p53 binds to the target promoter region of the ARHGAP24 gene, reduces its promoter transcriptional activity, and then reduces its messenger RNA (mRNA) and protein expression. The results demonstrated that the ARHGAP24 gene had significant genetic effects on aggressive behavioral traits of pigs. Therefore, rs335052970 in the ARHGAP24 gene can be used as a molecular marker to select the less aggressive pigs.

RSV-induced changes in a 3-dimensional organoid model of human fetal lungs

We have shown that respiratory syncytial virus (RSV) can spread hematogenously from infected airways of a pregnant woman to the developing fetal lungs in utero. This study sought to measure RSV replication, cytopathic effects, and protein expression in human lung organoids (HLOs) reproducing architecture and transcriptional profiles of human fetal lungs during the 1st trimester of gestation. HLOs derived from human pluripotent stem cells were microinjected after 50 or 100 days in culture with medium or recombinant RSV-A2 expressing the red fluorescent protein gene (rrRSV). Infection was monitored by fluorescent microscopy and PCR. Immunohistochemistry and proteomic analysis were performed. RSV infected HLOs in a dose- and time-dependent manner. RSV-infected HLOs increased expression of CC10 (Club cells), but had sparse FOXJ1 (ciliated cells). Disruption of F-actin cytoskeleton was consistent with proteomic data showing a significant increase in Rho GTPases proteins. RSV upregulated the transient receptor potential vanilloid 1 (TRPV1) channel and, while β2 adrenergic receptor (β2AR) expression was decreased overall, its phosphorylated form increased. Our data suggest that prenatal RSV infection produces profound changes in fetal lungs' architecture and expression profiles and maybe an essential precursor of chronic airway dysfunction. expression profiles, and possibly be an important precursor of chronic airway dysfunction.

Gene Expression Analysis Provides New Insights into the Mechanism of Intramuscular Fat Formation in Japanese Black Cattle

Japanese Black cattle (Japanese Wagyu) have a unique phenotype in which ectopic intramuscular fat accumulates in skeletal muscle, producing finely marbled beef. However, the mechanism of intramuscular fat formation in Japanese Black cattle remains unclear. To investigate the key genes involved in intramuscular fat accumulation, we comprehensively analyzed mRNA levels in subcutaneous and intramuscular fat tissues using RNA sequence (RNA-seq) analysis, which detected 27,606 genes. We identified eight key genes, namely carboxypeptidase E, tenascin C, transgelin, collagen type IV alpha 5 (COL4A5), cysteine and glycine-rich protein 2, PDZ, and LIM domain 3, phosphatase 1 regulatory inhibitor subunit 14A, and regulator of calcineurin 2. These genes were highly and specifically expressed in intramuscular fat tissue. Immunohistochemical analysis revealed a collagen network, including COL4A5, in the basement membrane around the intramuscular fat tissue. Moreover, pathway analysis revealed that, in intramuscular fat tissue, differentially expressed genes are related to cell adhesion, proliferation, and cancer pathways. Furthermore, pathway analysis showed that the transforming growth factor-β (TGF-β) and small GTPases regulators RASGRP3, ARHGEF26, ARHGAP10, ARHGAP24, and DLC were upregulated in intramuscular fat. Our study suggests that these genes are involved in intramuscular fat formation in Japanese Black cattle.

RSV attenuates epithelial cell restitution by inhibiting actin cytoskeleton-dependent cell migration

The airway epithelium's ability to repair itself after injury, known as epithelial restitution, is an essential mechanism enabling the respiratory tract's normal functions. Respiratory Syncytial Virus (RSV) is the leading cause of lower respiratory tract infections worldwide. We sought to determine whether RSV delays the airway epithelium wound repair process both in vitro and in vivo. We found that RSV infection attenuated epithelial cell migration, a step in wound repair, promoted stress fiber formation, and mediated assembly of large focal adhesions (FA). Inhibition of Rho kinase (ROCK), a master regulator of actin function, reversed these effects. There was increased RhoA and phospho-myosin light chain (pMLC2) following RSV infection. In vivo, mice were intraperitoneally inoculated with naphthalene to induce lung injury, followed by RSV infection. RSV infection delayed re-epithelialization. There were increased concentrations of pMLC2 in day 7 naphthalene plus RSV animals which normalized by day 14. This study suggests a key mechanism by which RSV infection delays wound healing.

ARHGAP24 ameliorates inflammatory response through inactivating Rac1/Akt/NF-κB pathway in acute pneumonia model of rat

Background

ARHGAP24 might play a protective effect in the development of acute pneumonia, but the underlying mechanism remained a mystery. We aimed to investigate the effect of ARHGAP24 and explore the protective mechanism based on the acute pneumonia model of rats.

Methods

Western blotting analysis was conducted to measure the expression of ARHGAP24 in the rat model of bacillus pyocyaneus-induced acute pneumonia after 12, 24, 36, and 48 h modeling. In the acute pneumonia model of rat, lung histopathological change, lung edema, and levels of inflammatory cytokines in the broncho alveolar lavage fluid (BALF) were respectively measured to comprehensively evaluate the beneficial effect of overexpression of ARHGAP24 mediated by adenovirus. The western blotting analysis was conducted to evaluate Rac1/Akt/NF-κB pathway-related protein expression change with ARHGAP24 overexpression.

Results

We found that ARHGAP24 expression tended to be lower in the acute pneumonia model of the rat after bacillus pyocyaneus treated 12, 24, 36, and 48 h. High expression of ARHGAP24 and a substantial ARHGAP24 positive area was found in the western blotting analysis and immunohistochemical staining in rats transfected with ARHGAP24. In the meantime, overexpression of ARHGAP24 suppressed the development of acute pneumonia through alleviating lung histopathological deterioration, lung edema, and levels of inflammatory cytokines in the BALF of the lung. What is more critical, ARHGAP24 overexpression inhibits the activation of Rac1, Akt, and NF-κB.

Conclusions

Thus, we conclude that ARHGAP24 ameliorated the inflammatory response in the acute pneumonia model of the rat through inactivating the Rac1/Akt/NF-κB pathway.

ARHGAP24 inhibits cell proliferation and cell cycle progression and induces apoptosis of lung cancer via a STAT6-WWP2-p27 axis

Rho GTPase-activating proteins (RhoGAPs) have been reported to be of great importance in the initiation and development of many different cancers. However, their biological roles and regulatory mechanisms in lung cancer development and progression are poorly defined. Real-time PCR or western blotting analysis was used to detect Rho GTPase-activating protein 24 (ARHGAP24), WWP2, p27, p-STAT6 and STAT6 expression levels as well as the activity of RhoA and Rac1 in lung cancer. Cell proliferation, apoptosis and cell cycle were measured by CCK-8 and flow cytometry analysis. Tumor growth of lung cancer cells was measured using a nude mouse xenograft experiment model in vivo. The correlation between WWP2 and p27 was measured by co-immunoprecipitation and ubiquitination analysis. We found that ARHGAP24 expression was lower in lung cancer tissues collected from the The Cancer Genome Atlas and independent hospital database. Overexpression of ARHGAP24 significantly suppressed cell proliferation and the activity of RhoA and Rac1, induced cell apoptosis and arrested cell cycle at the G₀–G₁ phase. ARHGAP24 overexpression also inhibited tumor growth in nude mice, whereas knockdown of ARHGAP24 significantly promoted cell proliferation and WWP2 expression and inhibited cell cycle arrest at G₁ phase through activating STAT6 signaling. ARHGAP24 overexpression inhibited WWP2 overexpression-induced cell proliferation, cell cycle progression and the decreased p27 expression. Moreover, WWP2 was found interacted with p27, and WWP2 overexpression promoted the ubiquitination of p27. In conclusion, our findings suggest that ARHGAP24 inhibits cell proliferation and cell cycle progression and induces cell apoptosis of lung cancer via a STAT6-WWP2-p27 axis.

The Association Between Heat-Shock Protein Polymorphisms and Prognosis in Lung Cancer Patients Treated With Platinum-Based Chemotherapy

Objective

Lung cancer is one of the most prevalent cancers and the leading cause of cancer-related death in the world. Platinum-based chemotherapy plays an important role in lung cancer treatment, but the therapeutic effect varies from person to person. Heat shock proteins (HSPs) have been reported to be associated with the survival time of lung cancer patients, which may be a potential biomarker in lung cancer treatment. The aim of this study was to investigate the association between genetic polymorphisms and the prognosis in lung cancer patients treated with platinum-based chemotherapy.

Methods

We performed genotyping in 19 single nucleotide polymorphisms (SNPs) of HSP genes and Rho family genes of 346 lung cancer patients by SequenomMassARRAY. We used Cox proportional hazard models, state and plink to analyze the associations between SNPs and the prognosis of lung cancer patients.

Results

We found that the polymorphisms of HSPB1 rs2070804 and HSPA4 rs3088225 were significantly associated with lung cancer survival (p=0.015, p=0.049*, respectively). We also discovered the statistically significant differences between rs2070804 with age, gender, histology and stage, rs3088225 with gender and stage, which can affect lung cancer prognosis.

Conclusion

The results of our study suggest that HSPB1 rs2070804 (G>T) and HSPA4 rs3088225 (A>G) may be useful biomarkers for predicting the prognosis of lung cancer patients treated with platinum-based chemotherapy.

Genomic profiling of colorectal cancer with isolated lung metastasis

BACKGROUND

Metastasis is a major cause of failed colorectal cancer (CRC) treatment. While lung metastasis (LM) is observed in 10-15% of patients with CRC, the genetic mechanisms that cause CRC to metastasize to the lung remain unclear.

METHODS

In this study, we employed whole exome sequencing (WES) of primary CRC tumors and matched isolated LM lesions to compare their genomic profiles. Comprehensive genomic analyses of five freshly frozen primary tumor lesions, five paired LM lesions, and matched non-cancerous tissues was achieved by WES.

RESULTS

An integrated analysis of somatic mutations, somatic copy number alterations, and clonal structures revealed that genomic alterations were present in primary and metastatic CRCs with various levels of discordance, indicating substantial levels of intertumor heterogeneity. Moreover, our results suggest that the founder clone of the primary tumor was responsible for the formation of the metastatic lesion. Additionally, only a few metastasis-specific mutations were identified, suggesting that LM-promoting mutations might be pre-existing in primary tumors.

CONCLUSIONS

Primary and metastatic CRC show intertumor heterogeneity; however, both lesions were founded by the same clone. These results indicate that malignant clones contributing to disease progression should be identified during the genetic prognosis of cancer metastasis.

HOTAIRM1 suppresses cell proliferation and invasion in ovarian cancer through facilitating ARHGAP24 expression by sponging miR-106a-5p

AIMS

Ovarian cancer (OC) is the most lethal gynecologic malignant tumors all over the world. HOX antisense intergenic RNA myeloid 1 (HOTAIRM1) has been reported as an important regulator in multiple tumors. However, the functions of HOTAIRM1 in OC and its possible molecular mechanisms remain unclear.

MAIN METHODS

qRT-PCR analysis was performed to detect the expression levels of HOTAIRM1, miR-106a-5p and ARHGAP24 mRNA in OC tissues and cells. The functional effects of HOTAIRM1, miR-106a-5p and ARHGAP24 on OC cells were determined by MTT, colony formation, flow cytometry and Transwell assays. Luciferase reporter, RIP and RNA pull-down assays were used to examine the interaction between miR-106a-5p and HOTAIRM1 or ARHGAP24. Tumor xenografts were constructed in nude mice to confirm the roles of HOTAIRM1 in OC in vivo.

KEY FINDINGS

HOTAIRM1 expression was lowered in OC tumor tissues and cells. Decreased HOTAIRM1 expression was associated with advanced FIGO stages and lymphatic metastasis. Up-regulation of HOTAIRM1 suppressed OC cell proliferation and invasion, and promoted apoptosis. Also, HOTAIRM1 slowed OC tumor growth in vivo. Moreover, HOTAIRM1 could serve as a competing endogenous RNA (ceRNA) of miR-106a-5p to derepress ARHGAP24 expression. HOTAIRM1-mediated inhibitory effect on OC progression was partly reversed following the restoration of miR-106a-5p expression. Furthermore, ARHGAP24 overexpression repressed OC progression in vitro.

SIGNIFICANCE

In conclusion, our study showed that HOTAIRM1 suppressed OC progression through derepression of ARHGAP24 by sponging miR-106a-5p. This finding provides novel insights into the mechanisms of HOTAIRM1 in OC and highlights a potential therapeutic strategy for the treatment of OC.