The role of ARHGAP9: clinical implication and potential function in acute myeloid leukemia

Prognostic impact of ARHGAP43(SH3BP1) in acute myeloid leukemia

BACKGROUND

Acute myeloid leukemia (AML) is a hematological malignancy with a heterogeneous prognosis. Novel markers are required to accurately assess the prognosis and formulate treatment plans.

METHODS

The association of ARHGAP family genes with prognostic value in acute myeloid leukemia (AML) was assessed using public databases (CCLE, GEPIA, TCGA, and GEO).

RESULTS

Elevated expression of ARHGAP43 (SH3BP1) was associated with poor prognosis in patients with acute myeloid leukemia. ARHGAP43 (SH3BP1) expression was higher in the poor/adverse prognosis (P < 0.001) and TP53 mutation groups (P = 0.0093). Higher ARHGAP43 (SH3BP1) expression was found to be an independent prognostic predictor in multivariate COX regression analysis (HR = 1.317, 95% CI: 1.008-1.720, P = 0.044). Higher ARHGAP43 (SH3BP1) expression who did not receive hematopoietic stem cell transplantation (HSCT) had shorter overall survival (OS) and progression-free survival (PFS) (OS: median: 7.60 vs. 24.90 months; P = 0.006; PFS: median: 11.40 vs. 27.22 months; P = 0.0096), whereas OS and PFS of patients who received HSCT were unaffected, suggesting that HSCT is a better treatment option for patients with higher ARHGAP43 (SH3BP1) expression. KEGG and GSEA analyses revealed that high-expression ARHGAP43 (SH3BP1) was related to inflammation and immune response. Additionally, down-regulation of ARHGAP43 (SH3BP1) expression inhibited AML cell proliferation.

CONCLUSION

These findings highlight the clinical potential of ARHGAP43 (SH3BP1) as a novel biomarker of AML, with higher levels indicating a poor prognosis.

ARHGAP9 knockdown promotes lung adenocarcinoma metastasis by activating Wnt/β-catenin signaling pathway via suppressing DKK2

This study aims to elucidate the effect of ARHGAP9 on lung adenocarcinoma (LUAD) metastasis, and preliminarily explore its molecular mechanism. As a result, we found that ARHGAP9 was downregulated and correlated with poor prognosis of LUAD. ARHGAP9 knockdown promoted LUAD cell proliferation, migration and invasion, inhibited cell apoptosis and reduced G0G1 cell cycle arrest, in contrast to the results of ARHGAP9 overexpression. Further RNA sequencing analysis demonstrated that ARHGAP9 knockdown in H1299 cells significantly reduced DKK2 (dickkopf related protein 2) expression. Silencing ARHGAP9 in H1299 cells while overexpressing DKK2, DKK2 reversed the promoted effects of ARHGAP9 knockdown on LUAD cell proliferation, migration and invasion. Meanwhile, the activity of Wnt/β-catenin signaling pathway was also reduced. Taken together, these data indicated that ARHGAP9 knockdown promoted LUAD metastasis by activating Wnt/β-catenin signaling pathway via suppressing DKK2. This may provide a new strategy for LUAD treatment.

Identification of NAD+ Metabolism-Derived Gene Signatures in Ovarian Cancer Prognosis and Immunotherapy

Background: Nicotinamide adenine dinucleotide (NAD⁺) has emerged as a critical regulator of cell signaling and survival pathways, affecting tumor initiation and progression. In this study it was investigated whether circulating NAD⁺ metabolism-related genes (NMRGs) could be used to predict immunotherapy response in ovarian cancer (OC) patients.

Method: In this study, NMRGs were comprehensively examined in OC patients, three distinct NMRGs subtypes were identified through unsupervised clustering, and an NAD⁺-related prognostic model was generated based on LASSO Cox regression analysis and generated a risk score (RS). ROC curves and an independent validation cohort were used to assess the model’s accuracy. A GSEA enrichment analysis was performed to investigate possible functional pathways. Furthermore, the role of RS in the tumor microenvironment, immunotherapy, and chemotherapy was also investigated.

Result: We found three different subgroups based on NMRGs expression patterns. Twelve genes were selected by LASSO regression to create a prognostic risk signature. High-RS was founded to be linked to a worse prognosis. In Ovarian Cancer Patients, RS is an independent prognostic marker. Immune infiltrating cells were considerably overexpressed in the low-RS group, as immune-related functional pathways were significantly enriched. Furthermore, immunotherapy prediction reveal that patients with low-RS are more sensitive to immunotherapy.

Conclusion: For a patient with OC, NMRGs are promising biomarkers. Our prognostic signature has potential predictive value for OC prognosis and immunotherapy response. The results of this study may help improve our understanding of NMRG in OCs.

CDK19 regulates the proliferation of hematopoietic stem cells and acute myeloid leukemia cells by suppressing p53-mediated transcription of p21

The cell cycle progression of hematopoietic stem cells (HSCs) and acute myeloid leukemia (AML) cells is precisely controlled by multiple regulatory factors. However, the underlying mechanisms are not fully understood. Here, we find that cyclin-dependent kinase 19 (CDK19), not its paralogue CDK8, is relatively enriched in mouse HSCs, and its expression is more significantly increased than CDK8 after proliferative stresses. Furthermore, SenexinB (a CDK8/19 inhibitor) treatment impairs the proliferation and self-renewal ability of HSCs. Moreover, overexpression of CDK19 promotes HSC function better than CDK8 overexpression. Using CDK19 knockout mice, we observe that CDK19^-/- HSCs exhibit similar phenotypes to those of cells treated with SenexinB. Interestingly, the p53 signaling pathway is significantly activated in HSCs lacking CDK19 expression. Further investigations show that CDK19 can interact with p53 to inhibit p53-mediated transcription of p21 in HSCs and treatment with a specific p53 inhibitor (PFTβ) partially rescues the defects of CDK19-null HSCs. Importantly, SenexinB treatment markedly inhibits the proliferation of AML cells. Collectively, our findings indicate that CDK19 is involved in regulating HSC and AML cell proliferation via the p53-p21 pathway, revealing a new mechanism underlying cell cycle regulation in normal and malignant hematopoietic cells.

GATA binding protein 5 (GATA5) induces Rho GTPase activating protein 9 (ARHGAP9) to inhibit the malignant process of lung adenocarcinoma cells

Lung adenocarcinoma is the main cause of the excessive mortality for patients who lives with lung cancers. According to the GEPIA database analysis, GATA5 and ARHGAP9 were found to be low expressed in lung adenocarcinoma, and they were positively correlated, and in addition ARHGAP9 low expression was associated with poor prognosis in lung adenocarcinoma. Therefore, the present study focused on the effect of promoting GATA5 to induce ARHGAP9 on the malignant process of lung adenocarcinoma cells. The expressions of GATA5 and ARHGAP9 were measured with Western blot and RT-qPCR. With the adoption of CCK-8, EDU staining, transwell and colony formation, the cell viability, proliferation, invasion and tumorigenesis ability were detected, respectively. In addition, the wound healing and Western blot were employed to evaluate migration and metastasis-related proteins individually. Moreover, the luciferase activity as well as the binding of GATA5 and ARHGAP9 promoters were detected by luciferase report and ChIP. After further comprehensive assessments, the results confirmed that GATA5 could successfully activate ARHGAP9. Moreover, ARHGAP9 upregulation remarkably inhibited lung adenocarcinoma cell proliferation, invasion and migration as compared to the control group. More importantly, GATA5 silencing reversed the inhibitory effect of ARHGAP9 upregulation on the malignant progression of lung adenocarcinoma cells. To conclude, the present study successfully demonstrated for the first time that GATA5-induced ARHGAP9 upregulation has a protective effect on lung adenocarcinoma cells.

Synthesis and antitumour evaluation of indole-2-carboxamides against paediatric brain cancer cells

Paediatric glioblastomas are rapidly growing, devastating brain neoplasms with an invasive phenotype. Radiotherapy and chemotherapy, which are the current therapeutic adjuvant to surgical resection, are still associated with various toxicity profiles and only marginally improve the course of the disease and life expectancy. A considerable body of evidence supports the antitumour and apoptotic effects of certain cannabinoids, such as WIN55,212-2, against a wide spectrum of cancer cells, including gliomas. In fact, we previously highlighted the potent cytotoxic activity of the cannabinoid ligand 5 against glioblastoma KNS42 cells. Taken together, in this study, we designed, synthesised, and evaluated several indoles and indole bioisosteres for their antitumour activities. Compounds 8a, 8c, 8f, 12c, and 24d demonstrated significant inhibitory activities against the viability (IC50 = 2.34-9.06 μM) and proliferation (IC50 = 2.88-9.85 μM) of paediatric glioblastoma KNS42 cells. All five compounds further retained their antitumour activities against two atypical teratoid/rhabdoid tumour (AT/RT) cell lines. When tested against a medulloblastoma DAOY cell line, only 8c, 8f, 12c, and 24d maintained their viability inhibitory activities. The viability assay against non-neoplastic human fibroblast HFF1 cells suggested that compounds 8a, 8c, 8f, and 12c act selectively towards the panel of paediatric brain tumour cells. In contrast, compound 24d and WIN55,212-2 were highly toxic toward HFF1 cells. Due to their structural resemblance to known cannabimimetics, the most potent compounds were tested in cannabinoid 1 and 2 receptor (CB1R and CB2R) functional assays. Compounds 8a, 8c, and 12c failed to activate or antagonise both CB1R and CB2R, whereas compounds 8f and 24d antagonised CB1R and CB2R, respectively. We also performed a transcriptional analysis on KNS42 cells treated with our prototype compound 8a and highlighted a set of seven genes that were significantly downregulated. The expression levels of these genes were previously shown to be positively correlated with tumour growth and progression, indicating their implication in the antitumour activity of 8a. Overall, the drug-like and selective antitumour profiles of indole-2-carboxamides 8a, 8c, 8f, and 12c substantiate the versatility of the indole scaffold in cancer drug discovery.

Rho GTPase Activating Protein 9 (ARHGAP9) in Human Cancers

BACKGROUND

In recent years, targeted therapy combined with traditional chemoradiotherapy and surgery has brought new opportunities for cancer treatment. However, the complex characteristics of cancer, such as heterogeneity and diversity, limit the clinical success of targeted drugs. The discovery of new cancer targets and deepening the understanding of their functional mechanisms will bring additional promising application prospects for the research and development of personalized cancer-targeted drugs.

OBJECTIVE

This study aimed to summarize the role of the Rho GTPase activating protein 9 (ARHGAP9) gene in tumorigenesis and development to discover therapeutic targets for cancer in the future.

METHODS

For this review, we collected patents from the databases of Espacenet and WIPO and articles from PubMed that were related to the ARHGAP9 gene.

RESULTS

Genetic/epigenetic variations and abnormal expression of the ARHGAP9 gene are closely associated with a variety of diseases, including cancer. ARHGAP9 can inactivate Rho GTPases by hydrolyzing GTP into GDP and regulate cancer cellular events, including proliferation, differentiation, apoptosis, migration and invasion, by inhibiting JNK/ERK/p38 and PI3K/AKT signaling pathways. In addition to reviewing these mechanisms, we assessed various patents on ARHGAP9 to determine whether ARHGAP9 might be used as a predictive biomarker for diagnosis/prognosis evaluation and a druggable target for cancer treatment.

CONCLUSION

In this review, the current knowledge of ARHGAP9 in cancer is summarized with an emphasis on its molecular function, regulatory mechanism and disease implications. Its characterization is crucial to understanding its important roles during different stages of cancer progression and therapy as a predictive biomarker and/or target.

SOX4-induced upregulation of ARHGAP9 promotes the progression of acute myeloid leukemia

Acute myeloid leukemia (AML) is the most common acute leukemia. Rho GTPase activating protein 9 (ARHGAP9) has been reported to be positively correlated with overall survival of AML patients, but the specific molecular function remains unclear. This study aims to further explore the functional role and the molecular mechanism of ARHGAP9 in AML cells. The expression level of ARHGAP9 in AML cells was measured using quantitative real-time PCR (qRT-PCR) and western blot. Cell transfection was performed to interfere ARHGAP9. CCK-8, flow cytometry and TUNEL assays were conducted to detect cell viability, cell cycle distribution and apoptosis, respectively. The binding relationship between SOX4 and ARHGAP9 promoter was verified using luciferase reporter assay and chromatin immunoprecipitation. The results showed that ARHGAP9 was upregulated in AML cells. Interference of ARHGAP9 greatly reduced cell viability and induced cell cycle arrest in G1 phase, accompanied with the reduction of Ki67, PCNA, cyclin D1, cyclin E1, CDK4 and CDK6. In addition, Interference of ARHGAP9 greatly promoted cell apoptosis, accompanied with the decreased protein expression of Bcl-2 and the increased protein expression of Bax, cleaved caspase 3 and cleaved caspase 9. Furthermore, SOX4 directly bound to ARHGAP9 promoter and regulated ARHGAP9 expression. In conclusion, this study suggested that ARHGAP9 interference exerted an anti-tumor effect through inhibiting cell proliferation, blocking cell cycle progression, and promoting cell apoptosis in AML cells. ARHGAP9 may serve as a novel therapeutic target for AML.