IQ Motif-Containing GTPase-Activating Protein 2 Inhibits Breast Cancer Angiogenesis By Suppressing VEGFR2-AKT Signaling

Sinensetin Inhibits Angiogenesis in Lung Adenocarcinoma via the miR-374c-5p/VEGF-A/VEGFR-2/AKT Axis

Sinensetin is a product isolated from Orthosiphon aristatus, and its antitumor activities have been well established. This study focused on the role and mechanism of sinensetin in lung adenocarcinoma (LUAD). LUAD cells were treated with various concentrations of sinensetin. The proliferation, migration, invasion, and angiogenesis of LUAD cells were detected using colony formation, transwell, and tube formation assays, respectively. The protein levels of VEGF-A, VEGFR-2, and phosphorylated AKT (ser473) were measured by western blotting. The targeted relationship between VEGF-A and miR-374c-5p was verified by luciferase reporter assay. BALB/c nude mice inoculated with A549 cells were treated with sinensetin (40 mg/kg/day) by gavage for 21 days to investigate the effect of sinensetin on tumor growth and angiogenesis in vivo. We found that sinensetin reduced proliferation, migration, invasion, angiogenesis, and cancer stem characteristics of LUAD cells. Sinensetin also suppressed LUAD tumor growth and angiogenesis in vivo. Sinensetin downregulated VEGF-A expression in LUAD cells by enhancing miR-374c-5p expression. MiR-374c-5p inhibited the VEGF-A/VEGFR-2/AKT pathway in LUAD cells. The antitumor effect of sinensetin was reversed by overexpression of VEGF-A or inhibition of miR-374c-5p. Overall, sinensetin upregulates miR-374c-5p to inhibit the VEGF-A/VEGFR-2/AKT pathway, thereby exerting antitumor effect on LUAD.

N6-methyladenosine-modified ALDH9A1 modulates lipid accumulation and tumor progression in clear cell renal cell carcinoma through the NPM1/IQGAP2/AKT signaling pathway

Aldehyde dehydrogenases superfamily (ALDHs), which are ubiquitously present in various organisms with diverse subcellular localizations, play a crucial role in regulating malignant tumor progression; Nevertheless, their involvement in clear cell renal cell carcinoma (ccRCC) has not been elucidated. In this study, we performed comprehensive bioinformatics analyses on the 19 ALDHs genes, and identified ALDH9A1 as a key contributor in ccRCC. Expression patterns and clinical relevance of ALDH9A1 were determined using bioinformatics analyses, real-time PCR, western blotting, and immunohistochemistry. To explore the underlying mechanism behind the tumor suppressor role of ALDH9A1, RNA sequencing, methylated RNA immunoprecipitation, luciferase reporter assay, mass spectroscopy, immunoprecipitation, mutational studies and immunofluorescence were employed. The impact of ALDH9A1 in ccRCC progression and metabolic programming was assessed through both in vitro and in vivo. Here, this study revealed ALDH9A1 as a tumor suppressor gene in ccRCC. The fat mass and obesity associated protein (FTO) was identified as a demethylase for ALDH9A1 mRNA, resulting in its reduced stability and expression levels in ccRCC. Functional experiments demonstrated that the deficiency of ALDH9A1 in ccRCC promoted tumor proliferation, invasion, migration and lipid accumulation. Mechanistic insights illustrated that the diminished levels of ALDH9A1 resulted in the failure to sequester nucleophosmin 1 (NPM1) within cytoplasm, thereby suppressing the transcription of IQ motif containing the GTPase-activating protein 2 (IQGAP2), subsequently activating the AKT-mTOR signaling, ultimately fostering tumor progression and lipid accumulation. In conclusion, the present study highlights the robust prognostic significance of ALDH9A1 and delivers a comprehensive understanding of ALDH9A1-NPM1-IQGAP2-AKT axis in ccRCC. These findings established a solid research foundation for novel therapeutic strategies for ccRCC patients.

EEF1A2 promotes HIF1A mediated breast cancer angiogenesis in normoxia and participates in a positive feedback loop with HIF1A in hypoxia

BACKGROUND

The eukaryotic elongation factor, EEF1A2, has been identified as an oncogene in various solid tumors. Here, we have identified a novel function of EEF1A2 in angiogenesis.

METHODS

Chick chorioallantoic membrane, tubulogenesis, aortic ring, Matrigel plug, and skin wound healing assays established EEF1A2's role in angiogenesis.

RESULT

Higher EEF1A2 levels in breast cancer cells enhanced cell growth, movement, blood vessel function, and tubule formation in HUVECs, as confirmed by ex-ovo and in-vivo tests. The overexpression of EEF1A2 could be counteracted by Plitidepsin. Under normoxic conditions, EEF1A2 triggered HIF1A expression via ERK-Myc and mTOR signaling in TNBC and ER/PR positive cells. Hypoxia induced the expression of EEF1A2, leading to a positive feedback loop between EEF1A2 and HIF1A. Luciferase assay and EMSA confirmed HIF1A binding on the EEF1A2 promoter, which induced its transcription. RT-PCR and polysome profiling validated that EEF1A2 affected VEGF transcription and translation positively. This led to increased VEGF release from breast cancer cells, activating ERK and PI3K-AKT signaling in endothelial cells. Breast cancer tissues with elevated EEF1A2 showed higher microvessel density.

CONCLUSION

EEF1A2 exhibits angiogenic potential in both normoxic and hypoxic conditions, underscoring its dual role in promoting EMT and angiogenesis, rendering it a promising target for cancer therapy.

Upregulation of IQGAP2 by EBV transactivator Rta and its influence on EBV life cycle

Epstein-Barr virus (EBV) is a human oncogenic γ-herpesvirus that establishes persistent infection in more than 90% of the world's population. EBV has two life cycles, latency and lytic replication. Reactivation of EBV from latency to the lytic cycle is initiated and controlled by two viral immediate-early transcription factors, Zta and Rta, encoded by BZLF1 and BRLF1, respectively. In this study, we found that IQGAP2 expression was elevated in EBV-infected B cells and identified Rta as a viral gene responsible for the IQGAP2 upregulation in both B cells and nasopharyngeal carcinoma cell lines. Mechanistically, we showed that Rta increases IQGAP2 expression through direct binding to the Rta-responsive element in the IQGAP2 promoter. We also demonstrated the direct interaction between Rta and IQGAP2 as well as their colocalization in the nucleus. Functionally, we showed that the induced IQGAP2 is required for the Rta-mediated Rta promoter activation in the EBV lytic cycle progression and may influence lymphoblastoid cell line clumping morphology through regulating E-cadherin expression. IMPORTANCE Elevated levels of antibodies against EBV lytic proteins and increased EBV DNA copy numbers in the sera have been reported in patients suffering from Burkitt's lymphoma, Hodgkin's lymphoma, and nasopharyngeal carcinoma, indicating that EBV lytic cycle progression may play an important role in the pathogenesis of EBV-associated diseases and highlighting the need for a more complete mechanistic understanding of the EBV lytic cycle. Rta acts as an essential transcriptional activator to induce lytic gene expression and thus trigger EBV reactivation. In this study, scaffolding protein IQGAP2 was found to be upregulated prominently following EBV infection via the direct binding of Rta to the RRE in the IQGAP2 promoter but not in response to other biological stimuli. Importantly, IQGAP2 was demonstrated to interact with Rta and promote the EBV lytic cycle progression. Suppression of IQGAP2 was also found to decrease E-cadherin expression and affect the clumping morphology of lymphoblastoid cell lines.

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.

The Antithetic Roles of IQGAP2 and IQGAP3 in Cancers

The scaffold protein family of IQ motif-containing GTPase-activating proteins (IQGAP1, 2, and 3) share a high degree of homology and comprise six functional domains. IQGAPs bind and regulate the cytoskeleton, interact with MAP kinases and calmodulin, and have GTPase-related activity, as well as a RasGAP domain. Thus, IQGAPs regulate multiple cellular processes and pathways, affecting cell division, growth, cell-cell interactions, migration, and invasion. In the past decade, significant evidence on the function of IQGAPs in signal transduction during carcinogenesis has emerged. Compared with IQGAP1, IQGAP2 and IQGAP3 were less analyzed. In this review, we summarize the different signaling pathways affected by IQGAP2 and IQGAP3, and the antithetic roles of IQGAP2 and IQGAP3 in different types of cancer. IQGAP2 expression is reduced and plays a tumor suppressor role in most solid cancer types, while IQGAP3 is overexpressed and acts as an oncogene. In lymphoma, for example, IQGAPs have partially opposite functions. There is considerable evidence that IQGAPs regulate a multitude of pathways to modulate cancer processes and chemoresistance, but some questions, such as how they trigger this signaling, through which domains, and why they play opposite roles on the same pathways, are still unanswered.

Reduced IQGAP2 Promotes Bladder Cancer through Regulation of MAPK/ERK Pathway and Cytokines

The progression of non-muscle-invasive bladder cancer (NMIBC) to muscle-invasive bladder cancer (MIBC) is a major challenge in urologic oncology. However, understanding of the molecular processes remains limited. The dysregulation of IQGAP2 is becoming increasingly evident in most tumor entities, and it plays a role in multiple oncogenic pathways, so we evaluated the role of IQGAP2 in bladder cancer. IQGAP2 was downregulated in tumors compared with normal urothelium tissues and cells. IQGAP2 effectively attenuated bladder cancer cell growth independently from apoptosis. Reduced IQGAP2 promoted EMT in bladder cancer cells via activation of the MAPK/ERK pathway. In addition, IQGAP2 might influence key cellular processes, such as proliferation and metastasis, through the regulation of cytokines. In conclusion, we suggest that IQGAP2 plays a tumor-suppressing role in bladder cancer, possibly via inhibiting the MAPK/ERK pathway and reducing cytokines.

Role of IQ Motif-Containing GTPase-Activating Proteins in Hepatocellular Carcinoma

IQ motif-containing GTPase-activating proteins (IQGAPs) are a class of scaffolding proteins, including IQGAP1, IQGAP2, and IQGAP3, which govern multiple cellular activities by facilitating cytoskeletal remodeling and cellular signal transduction. The role of IQGAPs in cancer initiation and progression has received increasing attention in recent years, especially in hepatocellular carcinoma (HCC), where the aberrant expression of IQGAPs is closely related to patient prognosis. IQGAP1 and 3 are upregulated and are considered oncogenes in HCC, while IQGAP2 is downregulated and functions as a tumor suppressor. This review details the three IQGAP isoforms and their respective structures. The expression and role of each protein in different liver diseases and mainly in HCC, as well as the underlying mechanisms, are also presented. This review also provides a reference for further studies on IQGAPs in HCC.