RacGAP1 promotes the malignant progression of cervical cancer by regulating AP-1 via miR-192 and p-JNK

The small GTPase Rap1A expedites the NOX2 oxidative burst by facilitating Rac and NOX2 autoactivations

Rac and Rap1A are small GTPases with the redox-sensitive GX4GK(S/T)C/ECS and NKCD motif. Of the known NADPH oxidase (NOX) isoforms, NOX1 and NOX2 function with the redox-sensitive Rac. Both exhibit an oxidative burst in which superoxide production is initially lagged but then accelerated. This burst is a reflection of NOX1 and NOX2 autoactivations occurring alongside the redox-dependent Rac autoactivation. NOX2 also contains the redox-sensitive Rap1A. However, its role in NOX2 function was unknown. In this study, we show that Rap1A is also autoactivated by its redox response, which is coupled to Rac and NOX2 autoactivations. This coupling is found to be mediated through the Rap1A-dependent recruitment of the Rac GEF P-REX1 to the NOX2 system. We further show that the initiation threshold and propagation rate of Rap1A autoactivation are lower and slower, respectively, than those of Rac and NOX2. The low-threshold Rap1A autoactivation recruits P-REX1 to the NOX2 system, resulting in the production of active Rac, thereby aiding the high-threshold initiation and propagation of Rac and NOX2 autoactivations. This results in the rapid completion of the NOX2 oxidative burst, which is specific to NOX2 because NOX1 lacks Rap1A. The redox response differences between the Rap1A NKCD motif and the Rac GX4GK(S/T)C/ECS motif appear to be the basis for the feature differences between Rap1A autoactivation and those of Rac and NOX2 autoactivations. The GX4GK(S/T)C/ECS and NKCD motifs are found in many redox-sensitive Rho/Rab and Ras family GTPases, respectively. Findings here shed light on previously unknown redox-dependent functional distinctions between these small GTPases.

Targeting RACGAP1 suppresses growth hormone pituitary adenoma growth

PURPOSE

Growth hormone pituitary adenoma (GHPA) is a major subtype of pituitary adenoma (PA), with tumor enlargement and abnormal secretion of growth hormone (GH) often causing complications. Rac GTPase-activating protein 1 (RACGAP1), a member of the guanine triphosphatase-activating protein family, is highly overexpressed in multiple tumors and promotes tumor growth. However, the role of RACGAP1 in GHPA remains unelucidated. Besides, specific inhibitors targeting RACGAP1 have not yet been developed. In this study, we aimed to determine the expression and function of RACGAP1 in GHPA and identify effective inhibitors against RACGAP1.

METHODS

Immunohistochemistry was used to detect the expression of RACGAP1 in GHPA and normal pituitary tissues. The effect of RACGAP1 on cell proliferation, apoptosis, and cell cycle was evaluated by knockdown of RACGAP1 in GH3 cells in vitro and xenograft models of GHPA in vivo. The downstream mechanism of RACGAP1 was explored by RNA sequencing, bioinformatic analysis, and Western blot. Inhibitors targeting RACGAP1 were screened and verified through a structure-based virtual docking method, cell viability assays, and surface plasmon resonance (SPR) experiments.

RESULTS

RACGAP1 expression was increased in GHPA compared with normal pituitary tissues. Knocking down RACGAP1 suppressed cell growth in vitro and in vivo. Preliminary mechanism studies indicated that inhibition of RACGAP1 led to the upregulation of p21 and the downregulation of several genes involved in the cell cycle signaling pathway, such as Cyclin A, CDK1, and CDK2. Moreover, DB07268 was identified for the first time as an effective RACGAP1 inhibitor that could prominently restrain the proliferation of GH3 cells.

CONCLUSION

This study demonstrates that RACGAP1 plays a critical role in GHPA, highlighting the novel inhibitor DB07268 as a promising therapeutic approach.

Molecular mechanisms of miR-192 in cancer: a biomarker and therapeutic target

Cancer remains a major global health challenge due to its rising prevalence and high mortality rates. The field of microRNAs (miRNAs) has made significant progress in the understanding of tumorigenesis and has broadened our knowledge of their targeting, especially in cancer therapy. miRNAs, a class of small non-coding RNAs, participate in post-transcriptional gene regulation by translational inhibition or mRNA degradation. Among these, microRNA-192 (miR-192) is located on human chromosome 11q13.1, and is highly correlated with the occurrence and development of various human cancers. Dysregulation of miR-192 has been extensively studied in various pathological processes, including tumorigenesis, making it a valuable biomarker for cancer diagnosis and prognosis. The functional role of miR-192 varies across cancer types, acting as either a tumor suppressor or as an oncogene through the modulation of multiple gene expressions and downstream signaling pathways. However, the roles of miR-192 in cancer appear inconsistent across types, with current research often focused on specific genes or pathways, limiting insight into its broader impact on cellular signaling networks. Therefore, this review aims to provide a comprehensive overview of miR-192 research. The paper reviews differences in miR-192 expression in cancer and systematically summarizes the role of miR-192 in cancers. The review further explores the complex roles of miR-192 in various pathological processes, emphasizing its regulatory pathways, interaction networks, and association with tumor progression. This review also illustrates the clinical application of miR-192 as a diagnostic and prognostic biomarker for non-invasive cancer detection, as it is consistently present in both serum and exosomes. A comprehensive summary and analysis of the relationship between miR-192 and various cancers may provide valuable insights, potentially guiding novel approaches in clinical diagnosis, therapeutic strategies, and foundational cancer research.

The Expression Regulation and Cancer-Promoting Roles of RACGAP1

RACGAP1 is a Rho-GTPase-activating protein originally discovered in male germ cells to inactivate Rac, RhoA and Cdc42 from the GTP-bound form to the GDP-bound form. GAP has traditionally been known as a tumor suppressor. However, studies increasingly suggest that overexpressed RACGAP1 activates Rac and RhoA in multiple cancers to mediate downstream oncogene overexpression by assisting in the nuclear translocation of signaling molecules and to promote cytokinesis by regulating the cytoskeleton or serving as a component of the central spindle. Contradictorily, it was also reported that RACGAP1 in gastric cancer could inactivate Rac and RhoA. In addition, studies have revealed that RACGAP1 can be a biomarker for prognosis, and its role in reducing doxorubicin sensitivity poses difficulties for treatment, while the current drug targets mainly focus on its downstream molecule. This article mainly reviews the expression regulation of RACGAP1 and its cancer-promoting functions through oncogene expression mediation and Rho-GTPase activation.

The role of JNK signaling pathway in organ fibrosis

BACKGROUND

Fibrosis is a tissue damage repair response caused by multiple pathogenic factors which could occur in almost every apparatus and leading to the tissue structure damage, physiological abnormality, and even organ failure until death. Up to now, there is still no specific drugs or strategies can effectively block or changeover tissue fibrosis. JNKs, a subset of mitogen-activated protein kinases (MAPK), have been reported that participates in various biological processes, such as genetic expression, DNA damage, and cell activation/proliferation/death pathways. Increasing studies indicated that abnormal regulation of JNK signal pathway has strongly associated with tissue fibrosis.

AIM OF REVIEW

This review designed to sum up the molecular mechanism progresses in the role of JNK signal pathway in organ fibrosis, hoping to provide a novel therapy strategy to tackle tissue fibrosis.

KEY SCIENTIFIC CONCEPTS OF REVIEW

Recent evidence shows that JNK signaling pathway could modulates inflammation, immunoreaction, oxidative stress and Multiple cell biological functions in organ fibrosis. Therefore, targeting the JNK pathway may be a useful strategy in cure fibrosis.

Reciprocal regulation between RACGAP1 and AR contributes to endocrine therapy resistance in prostate cancer

BACKGROUND

Endocrine resistance driven by sustained activation of androgen receptor (AR) signaling pathway in advanced prostate cancer (PCa) is fatal. Characterization of mechanisms underlying aberrant AR pathway activation to search for potential therapeutic strategy is particularly important. Rac GTPase-activating protein 1 (RACGAP1) is one of the specific GTPase-activating proteins. As a novel tumor proto-oncogene, overexpression of RACGAP1 was related to the occurrence of various tumors.

METHODS

Bioinformatics methods were used to analyze the relationship of expression level between RACGAP1 and AR as well as AR pathway activation. qRT-PCR and western blotting assays were performed to assess the expression of AR/AR-V7 and RACGAP1 in PCa cells. Immunoprecipitation and immunofluorescence experiments were conducted to detect the interaction and co-localization between RACGAP1 and AR/AR-V7. Gain- and loss-of-function analyses were conducted to investigate the biological roles of RACGAP1 in PCa cells, using MTS and colony formation assays. In vivo experiments were conducted to evaluate the effect of RACGAP1 inhibition on the tumor growth.

RESULTS

RACGAP1 was a gene activated by AR, which was markedly upregulated in PCa patients with CRPC and enzalutamide resistance. AR transcriptionally activated RACGAP1 expression by binding to its promoter region. Reciprocally, nuclear RACGAP1 bound to the N-terminal domain (NTD) of both AR and AR-V7, blocking their interaction with the E3 ubiquitin ligase MDM2. Consequently, this prevented the degradation of AR/AR-V7 in a ubiquitin-proteasome-dependent pathway. Notably, the positive feedback loop between RACGAP1 and AR/AR-V7 contributed to endocrine therapy resistance of CRPC. Combination of enzalutamide and in vivo cholesterol-conjugated RIG-I siRNA drugs targeting RACGAP1 induced potent inhibition of xenograft tumor growth of PCa.

CONCLUSION

In summary, our results reveal that reciprocal regulation between RACGAP1 and AR/AR-V7 contributes to the endocrine resistance in PCa. These findings highlight the therapeutic potential of combined RACGAP1 inhibition and enzalutamide in treatment of advanced PCa.

Elevated RACGAP1 Expression Enhances Malignant Potential in Lung Adenocarcinoma and Serves as a Prognostic Factor

Background: While RACGAP1 is identified as a potential oncogene, its specific role in lung adenocarcinoma (LUAD) remains unclear. Methods: First, we conducted a comprehensive analysis of the role of RACGAP1 across 33 types of cancer. Subsequently, we investigated the expression levels of RACGAP1 and its impact on prognosis using data from The Cancer Genome Atlas (TCGA) database. We utilized single-cell sequencing data to explore the tumor-related processes of RACGAP1 in LUAD and validated our findings through experimental verification. Employing a consensus clustering (CC) approach, we subdivided LUAD patients into two subtypes based on RACGAP1 cell cycle-related genes (RrCCGs). These subtypes exhibited significant differences in tumor characteristics, lymph node metastasis, and recurrence. Furthermore, we evaluated the prognostic influence of RrCCGs using univariate Cox regression and least absolute shrinkage and selection operator regression models (LASSO), successfully establishing a prognostic model. Results: RACGAP1 is frequently overexpressed in various tumors and can impact the prognosis of patients with LUAD. Additionally, experimental evidence has demonstrated that low expression of RACGAP1 favors tumor cell apoptosis and restoration of the cell cycle, while high expression promotes invasion and metastasis. Through CC analysis of RrCCGs, patients were classified into two groups, with survival analysis revealing distinct prognoses and stages between the two groups. Furthermore, Cox and LASSO regression successfully constructed a prognostic model with robust predictive capability.

RACGAP1 knockdown synergizes and enhances the effects of chemotherapeutics on ovarian cancer

Among the three most prevalent cancers affecting the female reproductive system, ovarian cancer (OV) ranks as the second most frequently diagnosed. It is important to investigate the genomic complexity of OV to develop diagnostic and therapeutic strategies. Through the utilization of bioinformatics analysis, it was determined that RacGTPase Activating Protein 1 (RACGAP1) holds significant significance in the field of OV chemotherapeutics, an aspect that has not been thoroughly explored in prior investigations. In our study, a notable increase in RACGAP1 expression was detected in ovarian cancer, demonstrating a robust association with clinicopathological features and patient prognosis. In vivo and in vitro testing revealed that RACGAP1 acts synergistically with chemotherapeutics to enhance their effects on ovarian cancer. Furthermore, an interaction between RACGAP1 and the subunit G2 of the condensin II complex, known as non-SMC condensin II complex subunit G2 (NCAPG2), has been identified. Our findings may provide new insight for improving therapeutic strategies for OV.

FOXM1 transcriptional regulation of RacGAP1 activates the PI3K/AKT signaling pathway to promote the proliferation, migration, and invasion of cervical cancer cells

BACKGROUND

Cervical cancer (CC) is the most common gynecological tumor disease in women, which occurs at the junction of cervical squamous columnar epithelium. We investigated the effect and mechanism of transcription factor FOXM1 synergizing RacGAP1 in the proliferation, migration, and invasion of CC cells.

METHODS

Here, we analyzed the correlation between FOXM1 and RacGAP1 and the clinicopathological features of 68 CC patients. RT-qPCR was used to assess FOXM1 and RacGAP1 mRNA expression in CC tissues and cells. Cell proliferation was assessed by CCK-8 and EDU assays. Transwell assay was applied to test migration and invasion. Cell apoptosis was evaluated utilizing flow cytometry. ChIP and dual-luciferase reporter assays confirmed the interaction of FOXM1 and RacGAP1. Protein levels of FOXM1 and RacGAP1, as well as PI3K/AKT, were analyzed by Western blot.

RESULTS

FOXM1 expression was correlated with FIGO stage and histological grade, and RacGAP1 expression was correlated with histological grade. FOXM1 and RacGAP1 levels were increased in CC tissues, and higher expressed in human CC cell lines than that in an immortalized HPV-negative skin keratinocyte line (HaCaT). Depleted RacGAP1 suppressed CC cell proliferation, migration and invasion, and promoted apoptosis. RacGAP1 was a target gene of FOXM1, and FOXM1 positively regulated RacGAP1 expression. FOXM1 had a synergistic effect with RacGAP1 to exert oncogenic function in CC by activating the PI3K/AKT signaling.

CONCLUSION

FOXM1 cooperates with RacGAP1 to induce CC cell proliferation, migration and invasion, inhibit apoptosis, and regulate PI3K/AKT signaling to promote CC progression.

Oncogenic and immunological roles of RACGAP1 in pan-cancer and its potential value in nasopharyngeal carcinoma

A particular GTPase-activating protein called RACGAP1 is involved in apoptosis, proliferation, invasion, metastasis, and drug resistance in a variety of malignancies. Nevertheless, the role of RACGAP1 in pan-cancer was less studied, and its value of the expression and prognostic of nasopharyngeal carcinoma (NPC) has not been explored. Hence, the goal of this study was to investigate the oncogenic and immunological roles of RACGAP1 in various cancers and its potential value in NPC. We comprehensively analyzed RACGAP1 expression, prognostic value, function, methylation levels, relationship with immune cells, immune infiltration, and immunotherapy response in pan-cancer utilizing multiple databases. The results discovered that RACGAP1 expression was elevated in most cancers and suggested poor prognosis, which could be related to the involvement of RACGAP1 in various cancer-related pathways such as the cell cycle and correlated with RACGAP1 methylation levels, immune cell infiltration and reaction to immunotherapy, and chemoresistance. RACGAP1 could inhibit anti-tumor immunity and immunotherapy responses by fostering immune cell infiltration and cytotoxic T lymphocyte dysfunction. Significantly, we validated that RACGAP1 mRNA and protein were highly expressed in NPC. The Gene Expression Omnibus database revealed that elevated RACGAP1 expression was associated with shorter PFS in patients with NPC, and RACGAP1 potentially influenced cell cycle progression, DNA replication, metabolism, and immune-related pathways, resulting in the recurrence and metastasis of NPC. This study indicated that RACGAP1 could be a potential biomarker in pan-cancer and NPC.

ARAP1 negatively regulates stress fibers formation and metastasis in lung adenocarcinoma via controlling Rho signaling

Small GTPases regulate multiple important cellular behaviors and their activities are strictly controlled by a mass of regulators. The dysfunction or abnormal expression of small GTPases or their regulators was frequently observed in various cancers. Here, we analyzed the expression and prognostic correlation of several GTPases and related regulators based on the TCGA database and found that Ankyrin Repeat and PH Domain 1 (ARAP1), a GTPase activating protein (GAP), is reduced in lung adenocarcinoma tissues compared to normal tissues and displays a positive correlation with overall survival (OS) and progression-free survival (PFS) of patients with lung adenocarcinoma. qPCR and western blot verified that ARAP1 is frequently downregulated in lung adenocarcinoma tumor tissues and cancer cells, and its downregulation might be mediated by epigenetic modification. Moreover, metastatic assays showed that overexpression of ARAP1 significantly inhibits metastasis of lung adenocarcinoma in vitro and in vivo. We further demonstrated that Rho signaling inhibition, mediated by RhoGAP activity of ARAP1, majorly contributes to suppressing migration and invasion of lung adenocarcinoma cancer cells via inhibiting stress fibers formation. In summary, this study indicates that ARAP1 may serve as a potential prognostic predictor and a metastatic suppressor in lung adenocarcinoma via its RhoGAP activity.

Rac GTPase activating protein 1 promotes the glioma growth by regulating the expression of MCM3

Glioma is the most common tumor of the nervous system. The diffuse growth and proliferation of glioma poses great challenges for its treatment. Here, Transcriptomic analysis revealed that Rac GTPase activating protein 1 (RACGAP1) is highly expressed in glioma. RACGAP1 has been shown to play an important role in the malignant biological progression of a variety of tumors. However, the underlying role and mechanism in glioma remain poorly understood. By using quantitative real-time polymerase chain reaction (qRT-PCR), western blot, immunohistochemistry and Orthotopic mouse xenografts, we confirmed that knockdown of RACGAP1 impeded cell proliferation in glioma and prolonged the survival of orthotopic mice. Interestingly, we also found that inhibiting the expression of RACGAP1 reduced the expression of minichromosome maintenance 3 (MCM3) through RNA-seq and rescue assay, while Yin Yang 1 (YY1) transcriptionally regulated RACGAP1 expression. Furthermore, T7 peptide-decorated exosome (T7-exo) is regard as a promising delivery modality for targeted therapy of glioma, and the T7-siRACGAP1-exo significantly improved the survival time of glioma bearing mice. These results suggested that targeting RACGAP1 may be a potential strategy for glioma therapy.

PLAGL2 promotes bladder cancer progression via RACGAP1/RhoA GTPase/YAP1 signaling

PLAGL2 is upregulated in various tumors, including bladder cancer (BCa). However, the mechanisms underlying the tumorigenic effects of PLAGL2 in BCa remain unclear. In our study, we proved that PLAGL2 was overexpressed in BCa tissues and correlated with decreased survival. Functionally, PLAGL2 deficiency significantly suppressed the proliferation and metastasis of BCa cells in vitro and in vivo. RNA sequencing, qRT‒PCR, immunoblotting, immunofluorescence staining, luciferase reporter, and ChIP assays revealed that overexpressed PLAGL2 disrupted the Hippo pathway and increased YAP1/TAZ activity by transactivating RACGAP1. Further investigations demonstrated that PLAGL2 activated YAP1/TAZ signaling via RACGAP1-mediated RhoA activation. Importantly, the RhoA inhibitor simvastatin or the YAP1/TAZ inhibitor verteporfin abrogated the proproliferative and prometastatic effects of BCa enhanced by PLAGL2. These findings suggest that PLAGL2 promotes BCa progression via RACGAP1/RhoA GTPase/YAP1 signaling. Hence, the core nodes of signaling may be promising therapeutic targets for BCa.

Prognostic risk factors of serous ovarian carcinoma based on mesenchymal stem cell phenotype and guidance for therapeutic efficacy

BACKGROUND

Epithelial ovarian cancer is the leading cause of death from gynecologic cancer, in which serous ovarian carcinoma (SOC) is the most common histological subtype. Although PARP inhibitors (PARPi) and antiangiogenics have been accepted as maintenance treatment in SOC, response to immunotherapy of SOC patients is limited.

METHODS

The source of transcriptomic data of SOC was from the Cancer Genome Atlas database and Gene Expression Omnibus. The abundance scores of mesenchymal stem cells (MSC scores) were estimated for each sample by xCell. Weighted correlation network analysis is correlated the significant genes with MSC scores. Based on prognostic risk model construction with Cox regression analysis, patients with SOC were divided into low- and high-risk groups. And distribution of immune cells, immunosuppressors and pro-angiogenic factors in different risk groups was achieved by single-sample gene set enrichment analysis. The risk model of MSC scores was further validated in datasets of immune checkpoint blockade and antiangiogenic therapy. In the experiment, the mRNA expression of prognostic genes related to MSC scores was detected by real-time polymerase chain reaction, while the protein level was evaluated by immunohistochemistry.

RESULTS

Three prognostic genes (PER1, AKAP12 and MMP17) were the constituents of risk model. Patients classified as high-risk exhibited worse prognosis, presented with an immunosuppressive phenotype, and demonstrated high micro-vessel density. Additionally, these patients were insensitive to immunotherapy and would achieve a longer overall survival with antiangiogenesis treatment. The validation experiments showed that the mRNA of PER1, AKAP12, and MMP17 was highly expressed in normal ovarian epithelial cells compared to SOC cell lines and there was a positive correlation between protein levels of PER1, AKAP12 and MMP17 and metastasis in human ovarian serous tumors.

CONCLUSION

This prognostic model established on MSC scores can predict prognosis of patients and provide the guidance for patients receiving immunotherapy and molecular targeted therapy. Because the number of prognostic genes was fewer than other signatures of SOC, it will be easily accessible on clinic.