RESUMEN

Breast cancer is a heterogeneous disease that remains the most common malignancy among women worldwide. During genomic analysis of breast tumours, mRNA levels of IQGAP3 were found to be upregulated in triple negative tumours. IQGAP3 was subsequently found to be expressed across a panel of triple negative breast cancer (TNBC) cell lines. Depleting expression levels of IQGAP3 delivered elongated cells, disrupted cell migration, and inhibited the ability of cells to form specialised invasive adhesion structures, termed invadopodia. The morphological changes induced by IQGAP3 depletion were found to be dependent on RhoA. Indeed, reduced expression of IQGAP3 disrupted RhoA activity and actomyosin contractility. Interestingly, IQGAP3 was also found to interact with p-21 activated kinase 6 (PAK6); a protein already associated with the regulation of cell morphology. Moreover, PAK6 depletion phenocopied IQGAP3 depletion in these cells. Whereas PAK6 overexpression rescued the IQGAP3 depletion phenotype. Our work points to an important PAK6-IQGAP3-RhoA pathway that drives the cellular contractility of breast cancer cells promoting both cell migration and adhesive invasion of these cells. As this phenotype is relevant to the process of metastasis and re-seeding of metastasis, the pharmacological targeting of PAK6 could lead to clinical benefit in TNBC patients.

Asunto(s)

Movimiento Celular , Neoplasias de la Mama Triple Negativas , Quinasas p21 Activadas , Proteína de Unión al GTP rhoA , Humanos , Neoplasias de la Mama Triple Negativas/patología , Neoplasias de la Mama Triple Negativas/metabolismo , Neoplasias de la Mama Triple Negativas/genética , Línea Celular Tumoral , Proteína de Unión al GTP rhoA/metabolismo , Quinasas p21 Activadas/metabolismo , Quinasas p21 Activadas/genética , Femenino , Podosomas/metabolismo , Proteínas Activadoras de ras GTPasa/metabolismo , Proteínas Activadoras de ras GTPasa/genética , Adhesión Celular , Regulación Neoplásica de la Expresión Génica , Proteínas Activadoras de GTPasa

RESUMEN

Background: IQGAP3 plays a crucial role in regulating cell proliferation, division, and cytoskeletal organization. Abnormal expression of IQGAP3 has been linked to various tumors, but its function in glioma is not well understood. Methods: Various methods, including genetic differential analysis, single-cell analysis, ROC curve analysis, Cox regression, Kaplan-Meier analysis, and enrichment analysis, were employed to analyze the expression patterns, diagnostic potential, prognostic implications, and biological processes involving IQGAP3 in normal and tumor tissues. The impact of IQGAP3 on immune infiltration and the immune microenvironment in gliomas was evaluated using immunofluorescence. Additionally, the cBioPortal database was used to analyze copy number variations and mutation sites of IQGAP3. Experimental validation was also performed to assess the effects of IQGAP3 on glioma cells and explore underlying mechanisms. Results: High IQGAP3 expression in gliomas is associated with an unfavorable prognosis, particularly in wild-type IDH and 1p/19q non-codeleted gliomas. Enrichment analysis revealed that IQGAP3 is involved in regulating the cell cycle, PI3K/AKT signaling, p53 signaling, and PLK1-related pathways. Furthermore, IQGAP3 expression may be closely related to the immunosuppressive microenvironment of glioblastoma. BRD-K88742110 and LY-303511 are potential drugs for targeting IQGAP3 in anti-glioma therapy. In vitro experiments showed that downregulation of IQGAP3 inhibits the proliferation and migration of glioma cells, with the PLK1/PI3K/AKT pathway potentially playing a crucial role in IQGAP3-mediated glioma progression. Conclusion: IQGAP3 shows promise as a valuable biomarker for diagnosis, prognosis, and immunotherapeutic strategies in gliomas.

Asunto(s)

Neoplasias Encefálicas , Glioma , Humanos , Pronóstico , Neoplasias Encefálicas/patología , Variaciones en el Número de Copia de ADN , Fosfatidilinositol 3-Quinasas/genética , Proteínas Proto-Oncogénicas c-akt/genética , Glioma/patología , Microambiente Tumoral/genética , Proteínas Activadoras de GTPasa

RESUMEN

IQGAP3 (IQ Motif Containing GTPase Activating Protein 3) is member of the IQGAP family of scaffold proteins, which are essential for assembling multiprotein complexes that coordinate various intracellular signaling pathways. Previous research has shown that IQGAP3 is overexpressed in psoriatic skin lesions. Given its involvement in processes like cell proliferation and chemokine signaling, we sought to explore its molecular role in driving the psoriatic phenotype of keratinocytes. By conducting transcriptome profiling of HaCaT keratinocytes, we identified numerous psoriasis-associated pathways that were affected when IQGAP3 was knocked down. These included alterations in NFkB signaling, EGFR signaling, activation of p38/MAPK and ERK1/ERK2, lipid metabolism, cytokine production, and the response to inflammatory cytokine stimulation. Real-time analysis further revealed changes in cell growth dynamics, including proliferation and wound healing. The balance between cell proliferation and apoptosis was altered, as were skin barrier functions and the production of IL-6 and IFNγ. Despite these significant findings, the diversity of the alterations observed in the knockdown cells led us to conclude that IQGAP3 may not be the best target for the therapeutic inhibition to normalize the phenotype of keratinocytes in psoriasis.

Asunto(s)

Proliferación Celular , Proteínas Activadoras de GTPasa , Queratinocitos , Psoriasis , Humanos , Queratinocitos/metabolismo , Queratinocitos/patología , Psoriasis/metabolismo , Psoriasis/patología , Psoriasis/genética , Proteínas Activadoras de ras GTPasa/metabolismo , Proteínas Activadoras de ras GTPasa/genética , Transducción de Señal , Células HaCaT , Citocinas/metabolismo , Apoptosis , Piel/metabolismo , Piel/patología , Línea Celular , Perfilación de la Expresión Génica

RESUMEN

BACKGROUND: The primary reason for tumor-related deaths worldwide is lung adenocarcinoma (LUAD). The oncogene IQ motif-containing GTPase activating protein 3 (IQGAP3) is crucial for contributing to tumor initiation and progression. However, the precise function and molecular mechanism of IQGAP3 in LUAD remain unknown. The present study aimed to investigate the expression, prognosis, mechanism and tumor immunity associated with IQGAP3 in LUAD. METHODS: The relationship between IQGAP3 and the poor prognosis of LUAD was analyzed using The Cancer Genome Atlas (TCGA) database. This analysis was further validated on lung cancer tissues and cell lines. The function of IQGAP3 was investigated by silencing it in LUAD cell lines. To predict microRNA (miRNA) and long non-coding RNA associated with IQGAP3, the starBase database was utilized, and the predictions were verified by enhancing the function of miRNA. Finally, the relationship between IQGAP3 and tumor immunity was evaluated using Spearman's correlation analysis. RESULTS: TCGA database revealed that higher levels of IQGAP3 were associated with advanced tumor stage, N stage and poor prognosis in LUAD patients. To confirm that, we conducted experiments on lung cancer tissues and cell lines and found that silencing IQGAP3 significantly inhibited tumor cell proliferation and migration. The expression of IQGAP3 showed a negative correlation with has-miR-101-3p and has-miR-135a-5p, whereas it showed a positive correlation with GSEC, AC005034.3 and TYMSOS. Furthermore, the introduction of miRNA-mimics into lung cancer cell resulted in a significant inhibition of cancer cell growth and migration. Following that, the level of IQGAP3 showed a positive correlation with the infiltration of immune cells in tumors. CONCLUSIONS: These results reveal that IQGAP3 significantly promotes LUAD progression and could serve as a prognostic biomarker for LUAD. Furthermore, IQGAP3 is most likely regulated by the GSEC/TYMSOS-hsa-miR-101-3p axis and the AC005034.3-hsa-miR-135a-5p axis in LUAD.

Asunto(s)

Adenocarcinoma del Pulmón , Neoplasias Pulmonares , MicroARNs , Humanos , Adenocarcinoma del Pulmón/genética , MicroARNs/genética , Neoplasias Pulmonares/genética , Línea Celular , Proliferación Celular/genética , Transformación Celular Neoplásica , Regulación Neoplásica de la Expresión Génica , Proteínas Activadoras de GTPasa

RESUMEN

INTRODUCTION: Pancreatic ductal adenocarcinoma (PDAC) is one of the most lethal types of malignancy, with poor prognosis and rising incidence. IQ motif containing GTPase-activating protein 3 (IQGAP3) is a member of the IQGAPs family of scaffolding proteins that govern multiple cellular activities like cytoskeletal remodeling and cellular signal transduction. This study aimed to analyze the expression and biological function of IQGAP3 in PDAC. METHODS: We analyzed IQGAP3 expression in 81 PDAC samples by immunohistochemistry. RNA interference was used to inhibit IQGAP3 expression in PDAC cell lines. RESULTS: Immunohistochemical analysis of IQGAP3 showed that 54.3% of PDACs were positive for cytoplasmic expression of IQGAP3, with no expression found in non-neoplastic tissue. Furthermore, IQGAP3 expression was an independent poor prognostic factor in our immunostaining-based studies and analyses of public databases. Our cohort and the Cancer Genome Atlas database indicated that IQGAP3 is co-localized with kinesin family member C1 (KIFC1), which we previously reported as a cancer stem cell-associated protein. IQGAP3 small interfering RNA treatment decreased PDAC cell proliferation and spheroid colony formation via ERK and AKT pathways. DISCUSSION/CONCLUSION: These results suggest that IQGAP3, a transmembrane protein, is involved in survival and stemness and may be a promising new therapeutic target for PDAC.

Asunto(s)

Carcinoma Ductal Pancreático , Proliferación Celular , Cinesinas , Células Madre Neoplásicas , Neoplasias Pancreáticas , Humanos , Carcinoma Ductal Pancreático/genética , Carcinoma Ductal Pancreático/patología , Carcinoma Ductal Pancreático/metabolismo , Neoplasias Pancreáticas/genética , Neoplasias Pancreáticas/patología , Neoplasias Pancreáticas/metabolismo , Línea Celular Tumoral , Femenino , Células Madre Neoplásicas/metabolismo , Células Madre Neoplásicas/patología , Masculino , Persona de Mediana Edad , Pronóstico , Cinesinas/genética , Cinesinas/metabolismo , Anciano , Proteínas Activadoras de ras GTPasa/genética , Proteínas Activadoras de ras GTPasa/metabolismo , Transducción de Señal , Biomarcadores de Tumor/metabolismo , Biomarcadores de Tumor/genética , Inmunohistoquímica , Proteínas Activadoras de GTPasa

RESUMEN

The IQGAP family of proteins plays a crucial role in cytokinesis across diverse organisms, but the underlying mechanisms are not fully understood. In this study, we demonstrate that IQGAPs in budding yeast, fission yeast, and human cells use a two-domain module to regulate their localization as well as the assembly and disassembly of the actomyosin ring during cytokinesis. Strikingly, the calponin homology domains (CHDs) in these IQGAPs bind to distinct cellular F-actin structures with varying specificity, whereas the non-conserved domains immediately downstream of the CHDs in these IQGAPs all target the division site, but differ in timing, localization strength, and binding partners. We also demonstrate that human IQGAP3 acts in parallel to septins and myosin-IIs to mediate the role of anillin in cytokinesis. Collectively, our findings highlight the two-domain mechanism by which IQGAPs regulate cytokinesis in distantly related organisms as well as their evolutionary conservation and divergence.

Asunto(s)

Citocinesis , Schizosaccharomyces , Humanos , Citocinesis/fisiología , Actomiosina/metabolismo , Actinas/metabolismo , Citoesqueleto de Actina/metabolismo , Miosinas/metabolismo , Schizosaccharomyces/metabolismo , Proteínas Activadoras de GTPasa/metabolismo

RESUMEN

As a transcriptional factor, the Forkhead box (FOX) gene family is closely connected with apoptosis, proliferation, and other cellular processes. FOXD2, as one descendant of the FOX gene family, has been mentioned in many articles to show a high expression in several cancers. However, whether FOXD2 has a connection with gastric adenocarcinoma remains an unanswered question. Expression of FOXD2 and IQGAP3 in gastric adenocarcinoma was evaluated by bioinformatics analysis, which was further detected by real-time quantitative PCR (qRT-PCR) and western blot. The downstream target genes of FOXD2 were also mined by bioinformatics analysis. Pathway enrichment analysis was then performed on the target genes. Chromatin immunoprecipitation assay (ChIP) and dual-luciferase reporter assay were conducted to validate the regulatory relationship between FOXD2 and its downstream target gene IQGAP3. Methyl thiazolyl tetrazolium assay (MTT), combined with cell colony formation assay, was employed to assess the effect of FOXD2 and IQGAP3 on the proliferation of gastric adenocarcinoma cells. Intracytoplasmic Ca2+ concentration was measured by Fluo-3 fluorescence staining. FOXD2 showed a high expression in gastric adenocarcinoma tissues and cells, and FOXD2 silencing considerably attenuated gastric adenocarcinoma cell proliferation. IQGAP3, a downstream target gene of FOXD2, had a positive connection with the expression of FOXD2. The binding relationship between FOXD2 and the promoter region of IQGAP3 was further verified by ChIP and dual-luciferase reporter assays. The results of cell function experiments indicated that FOXD2 could promote gastric adenocarcinoma cell proliferation by transcriptionally activating IQGAP3 to induce an increase in intracellular Ca2+ level. This study confirmed that FOXD2 increased intracellular Ca2+ level through transcriptional activation of IQGAP3, which in turn propelled the proliferation of gastric adenocarcinoma cells, revealing the considerable significance of FOXD2 in the development of gastric adenocarcinoma.

Asunto(s)

Adenocarcinoma , Neoplasias Gástricas , Humanos , Proliferación Celular/genética , Regulación Neoplásica de la Expresión Génica , Transducción de Señal/genética , Neoplasias Gástricas/genética , Adenocarcinoma/genética , Luciferasas/metabolismo , Línea Celular Tumoral , Proteínas Activadoras de GTPasa/genética , Proteínas Activadoras de GTPasa/metabolismo

RESUMEN

Identification of unique gene markers of normal and cancer stem cells is an effective strategy to study cells of origin and understand tumor behavior. Lineage tracing experiments using the Cre recombinase driven by a stem cell-specific promoter in the CreERT2 reporter mouse model enables identification of adult stem cells and delineation of stem cell activities in vivo. In our recent research on the mouse stomach, Iqgap3 was identified as a homeostatic stem cell marker located in the isthmus of the stomach epithelium. Lineage tracing with the Iqgap3-2A-CreERT2;Rosa26-LSL-tdTomato mouse model demonstrated stem cell activity in Iqgap3-expressing cells. Using the Iqgap3-2A-CreERT2 mouse model to target oncogenic KrasG12D expression to Iqgap3-expressing cells, we observed the rapid development of precancerous metaplasia in the stomach and proposed that aberrant Iqgap3-expressing cells may be critical determinants of early carcinogenesis. In this chapter, we detail a lineage tracing protocol to assess stem cell activity in the murine stomach. We also describe the procedure of inducing KrasG12D expression in Iqgap3-expressing homeostatic stem cells to explore their role as cells of origin and to trace the early cellular changes that precede neoplastic transformation.

Asunto(s)

Células Madre Adultas , Neoplasias Gástricas , Ratones , Animales , Ratones Transgénicos , Proteínas Proto-Oncogénicas p21(ras)/metabolismo , Neoplasias Gástricas/patología , Mucosa Gástrica/metabolismo , Células Madre Neoplásicas/metabolismo , Células Madre Adultas/metabolismo

RESUMEN

INTRODUCTION: IQGAP3 possesses oncogenic actions; its impact on prostate cancer (PC) remains unclear. OBJECTIVE: We will investigate IQGAP3's association with PC progression, key mechanisms, prognosis, and immune evasion. METHODS: IQGAP3 expression in PC was examined by immunohistochemistry and using multiple datasets. IQGAP3 network was analyzed for pathway alterations and used to construct a multigene signature (SigIQGAP3NW). SigIQGAP3NW was characterized using LNCaP cell-derived castration-resistant PCs (CRPCs), analyzed for prognostic value in 26 human cancer types, and studied for association with immune evasion. RESULTS: Increases in IQGAP3 expression associated with PC tumorigenesis, tumor grade, metastasis, and p53 mutation. IQGAP3 correlative genes were dominantly involved in mitosis. IQGAP3 correlated with PLK1 and TOP2A expression at Spearman correlation/R = 0.89 (p ≤ 3.069e-169). Both correlations were enriched in advanced PCs and Taxane-treated CRPCs and occurred at high levels (R > 0.8) in multiple cancer types. SigIQGAP3NW effectively predicted cancer recurrence and poor prognosis in independent PC cohorts and across 26 cancer types. SigIQGAP3NW stratified PC recurrence after adjustment for age at diagnosis, grade, stage, and surgical margin. SigIQGAP3NW component genes were upregulated in PC, metastasis, LNCaP cell-produced CRPC, and showed an association with p53 mutation. SigIQGAP3NW correlated with immune cell infiltration, including Treg in PC and other cancers. RELT, a SigIQGAP3NW component gene, was associated with elevations of multiple immune checkpoints and the infiltration of Treg and myeloid-derived suppressor cells in PC and across cancer types. RELT and SigIQGAP3NW predict response to immune checkpoint blockade (ICB) therapy. CONCLUSIONS: In multiple cancers, IQGAP3 robustly correlates with PLK1 and TOP2A expression, and SigIQGAP3NW and/or RELT effectively predict mortality risk and/or resistance to ICB therapy. PLK1 and TOP2A inhibitors should be investigated for treating cancers with elevated IQGAP3 expression. SigIQGAP3NW and/or RELT can be developed for clinical applications in risk stratification and management of ICB therapy.

Asunto(s)

Neoplasias de la Próstata , Proteína p53 Supresora de Tumor , Masculino , Humanos , Recurrencia Local de Neoplasia , Neoplasias de la Próstata/genética , Neoplasias de la Próstata/metabolismo , Neoplasias de la Próstata/patología , Pronóstico , Proteínas Activadoras de GTPasa/genética , Proteínas Activadoras de GTPasa/metabolismo

RESUMEN

Background: Clear cell renal clear cell carcinoma (ccRCC) is resistant to most chemotherapeutic drugs and the molecular mechanisms have not been fully revealed. Genomic instability and the abnormal activation of bypass DNA repair pathway is the potential cause of tumor resistance to radiotherapy and chemotherapy. IQ-motif GTPase activating protein 3 (IQGAP3) regulates cell migration and intercellular adhesion. This study aims to analysis the effects of IQGAP3 expression on cell survival, genome stability and clinical prognosis in ccRCC. Methods: Multiple bioinformatics analysis based on TCGA database and IHC analysis on clinical specimens were included. Quantitative real-time polymerase chain reaction (qRT-PCR) and western blot (WB) were used to determine protein expression level. MTT assay and 3D spheroid cell growth assay were used to assess cell proliferation and drug resistance in RNAi transfected ccRCC cells. Cell invasion capacity was evaluated by transwell assay. The influence of IQGAP3 on genome instability was revealed by micronuclei number and γ H2AX recruitment test. Results: The highly expressed IQGAP3 in multiple subtypes of renal cell carcinoma has a clear prognostic value. Deletion of IQGAP3 inhibits cell growth in 3D Matrigel. IQGAP3 depletion lso increases accumulated DNA damage, and improves cell sensitivity to ionizing radiation and chemotherapeutic drugs. Therefore, targeting DNA damage repair function of IQGAP3 in tumorigenesis can provide ideas for the development of new targets for early diagnosis.

Asunto(s)

Carcinoma de Células Renales , Neoplasias Renales , Humanos , Carcinoma de Células Renales/genética , Proteínas Activadoras de GTPasa/genética , Neoplasias Renales/genética , Resistencia a Medicamentos , Inestabilidad Genómica/genética

RESUMEN

Bladder cancer (BC) is the most common malignant tumour of the urinary system. The current conventional treatments for BC have certain limitations. It is very urgent and necessary to find new treatment strategies for BC. Our study elucidated the underlying regulatory mechanisms of cell division control protein 42 homologue (CDC42) to regulate the development of BC. Quantitative real-time polymerase chain reaction, Western blot, immunofluorescence and immunohistochemistry were used to assess the expression of CDC42 and IQ motif-containing GTPase-activating protein 3 (IQGAP3) in BC tissues and BC cells. We induced the knockdown or overexpression by transfecting sh-CDC42 or oe-IQGAP3 into BC cells. In addition, cell proliferation and apoptosis were evaluated by cell counting kit-8 and flow cytometry assays, respectively. Moreover, proteins involved in the rat sarcoma (Ras)/extracellular regulated protein kinase (ERK) pathway were determined by Western blot. The expression of CDC42 and IQGAP3 was markedly upregulated in both BC tissues and BC cells. CDC42 silencing downregulated the expression of IQGAP3 and suppressed the Ras/ERK pathway. In addition, CDC42 silencing markedly promoted apoptosis and inhibited proliferation in BC cells. Further experiments showed that overexpression of IQGAP3 dramatically abolished the bioeffects mediated by CDC42 silencing on the proliferation and apoptosis of BC cells. All our results suggested that CDC42 promoted the Ras/ERK pathway by regulating IQGAP3, thus enhancing cell proliferation and suppressing cell apoptosis in BC cells and ultimately participating in the pathogenesis of BC.

Asunto(s)

Proteínas Activadoras de GTPasa , Neoplasias de la Vejiga Urinaria , Proteína de Unión al GTP cdc42 , Humanos , Apoptosis , Línea Celular Tumoral , Proliferación Celular , Regulación Neoplásica de la Expresión Génica , Proteínas Activadoras de GTPasa/genética , Proteínas Activadoras de GTPasa/metabolismo , Sistema de Señalización de MAP Quinasas , Proteínas Quinasas , Neoplasias de la Vejiga Urinaria/genética , Proteína de Unión al GTP cdc42/genética , Proteína de Unión al GTP cdc42/metabolismo

RESUMEN

IQ motif containing GTPase-activating protein 3 (IQGAP3) is a member of the Rho family of guanosine-5'-triphosphatases (GTPases). IQGAP3 plays a crucial part in the development and progression of several types of cancer. However, the prognostic, upstream-regulatory, and immunological roles of IQGAP3 in human cancer types are not known. We found that IQGAP3 expression was increased in different types of human cancer. The high expression of IQGAP3 was correlated with tumor stage, lymph node metastasis, and a poor prognosis in diverse types of human cancer. The DNA methylation of IQGAP3 was highly and negatively correlated with IQGAP3 expression in diverse cancer types. High DNA methylation in IQGAP3 was correlated with better overall survival in human cancer types. High mRNA expression of IQGAP3 was associated with tumor mutational burden, microsatellite instability, immune cell infiltration, and immune modulators. Analyses of signaling pathway enrichment showed that IQGAP3 was involved in the cell cycle. IQGAP3 expression was associated with sensitivity to a wide array of drugs in cancer cells lines. We revealed that polypyrimidine tract-binding protein 1 (PTBP1) and an IQGAP3-associated lncRNA (IQGAP3AR)/let-7c-5p axis were potential regulations for IQGAP3 expression. We provided the first evidence to show that an IQGAP3AR/let-7c-5p/IQGAP3 axis has indispensable roles in the progression and immune response in different types of human cancer.

RESUMEN

Phenotypic heterogeneity and molecular diversity make diffuse large B-cell lymphoma (DLBCL) a challenging disease. We recently illustrated that amoeboid movement plays an indispensable role in DLBCL dissemination and inadvertently identified that the inhibitor of bromodomain and extra-terminal (BET) proteins JQ1 could repress DLBCL migration. To explore further, we dissected the impacts of BET inhibition in DLBCL. We found that JQ1 abrogated amoeboid movement of DLBCL cells through both restraining RAS signaling and suppressing MYC-mediated RhoA activity. We also demonstrated that BET inhibition resulted in the upregulation of a GTPase regulatory protein, the IQ motif containing GTPase activating protein 3 (IQGAP3). IQGAP3 similarly exhibited an inhibitory effect on RAS activity in DLBCL cells. Through barcoded mRNA/protein profiling in clinical samples, we identified a specific subgroup of DLBCL tumors with enhanced phosphatidylinositol-3-kinase (PI3K) activity, which led to an inferior survival in these patients. Strikingly, a lower IQGAP3 expression level further portended those with PI3K-activated DLBCL a very dismal outcome. The inhibition of BET and PI3K signaling activity led to effective suppression of DLBCL dissemination in vivo. Our study provides an important insight into the ongoing efforts of targeting BET proteins as a therapeutic approach for DLBCL.

RESUMEN

AIM: The study was designed to mine the expression and roles of IQGAP3 in clear cell renal cell carcinoma (ccRCC). METHODS: Expression profiles and clinical information were obtained from the Cancer Genome Atlas (TCGA) to estimate IQGAP3 expression in ccRCC, its relationship with patients' clinicopathological variables and prognosis, and the potential biological mechanisms. RESULTS: IQGAP3 was highly expressed in ccRCC and indicated advanced clinical outcome and poor prognosis. IQGAP3 affected the progression of ccRCC through several cancer-related pathways. IQGAP3 might play a vital role in the ccRCC tumor microenvironment. CONCLUSION: IQGAP3 could serve as a promising prognostic biomarker and therapeutic target.

RESUMEN

The voltage-dependent potassium channel Kv1.3 has been implicated in proliferation in many cell types, based on the observation that Kv1.3 blockers inhibited proliferation. By modulating membrane potential, cell volume, and/or Ca2+ influx, K+  channels can influence cell cycle progression. Also, noncanonical channel functions could contribute to modulate cell proliferation independent of K+ efflux. The specificity of the requirement of Kv1.3 channels for proliferation suggests the involvement of molecule-specific interactions, but the underlying mechanisms are poorly identified. Heterologous expression of Kv1.3 channels in HEK cells has been shown to increase proliferation independently of K+ fluxes. Likewise, some of the molecular determinants of Kv1.3-induced proliferation have been located in the C-terminus region, where individual point mutations of putative phosphorylation sites (Y447A and S459A) abolished Kv1.3-induced proliferation. Here, we investigated the mechanisms linking Kv1.3 channels to proliferation exploring the correlation between Kv1.3 voltage-dependent molecular dynamics and cell cycle progression. Using transfected HEK cells, we analyzed both the effect of changes in resting membrane potential on Kv1.3-induced proliferation and the effect of mutated Kv1.3 channels with altered voltage dependence of gating. We conclude that voltage-dependent transitions of Kv1.3 channels enable the activation of proliferative pathways. We also found that Kv1.3 associated with IQGAP3, a scaffold protein involved in proliferation, and that membrane depolarization facilitates their interaction. The functional contribution of Kv1.3-IQGAP3 interplay to cell proliferation was demonstrated both in HEK cells and in vascular smooth muscle cells. Our data indicate that voltage-dependent conformational changes of Kv1.3 are an essential element in Kv1.3-induced proliferation.

Asunto(s)

Proliferación Celular , Activación del Canal Iónico , Canal de Potasio Kv1.3/metabolismo , Músculo Liso Vascular/metabolismo , Miocitos del Músculo Liso/metabolismo , Proteínas Activadoras de GTPasa/genética , Proteínas Activadoras de GTPasa/metabolismo , Células HEK293 , Humanos , Canales KATP/genética , Canales KATP/metabolismo , Canal de Potasio Kv1.3/química , Canal de Potasio Kv1.3/genética , Potenciales de la Membrana , Mutación , Conformación Proteica , Transducción de Señal , Relación Estructura-Actividad

RESUMEN

IQ motif containing GTPase-activating protein 3 (IQGAP3) has been implicated in diverse cellular processes, including neuronal morphogenesis, cell proliferation and motility, and epithelial-mesenchymal transition. However, its role in cancer radioresistance is completely unknown. Here, we report that IQGAP3 is overproduced in lung cancer patients and correlates with poor clinical outcomes. Functionally, we demonstrate that depletion of IQGAP3 impairs oncogenesis and overcomes radioresistance in lung cancer in vitro and in vivo. Mechanistically, we uncover that IQGAP3 interacts with Rad17 and controls its expression to activate the ATM/Chk2 and ATR/Chk1 signaling pathways by recruiting the Mre11-Rad50-Nbs1 (MRN) complex in response to DNA damage. Moreover, Rad17 is identified as the major downstream effector that mediates the functions of IQGAP3 in lung cancer. Clinically, IQGAP3 overexpression positively correlates with Rad17 upregulation in human lung cancer tissues. Collectively, these data support key role for IQGAP3 in promoting lung cancer radioresistance by interacting with Rad17 and suggest that targeting IQGAP3 may be an attractive strategy for lung cancer radiotherapy.

Asunto(s)

Proteínas de Ciclo Celular/metabolismo , Proteínas Activadoras de GTPasa/metabolismo , Neoplasias Pulmonares/patología , Tolerancia a Radiación , Regulación hacia Arriba , Células A549 , Ácido Anhídrido Hidrolasas/metabolismo , Animales , Línea Celular Tumoral , Proteínas de Unión al ADN/metabolismo , Transición Epitelial-Mesenquimal , Femenino , Proteínas Activadoras de GTPasa/genética , Eliminación de Gen , Regulación Neoplásica de la Expresión Génica , Humanos , Neoplasias Pulmonares/metabolismo , Neoplasias Pulmonares/terapia , Proteína Homóloga de MRE11/metabolismo , Ratones , Trasplante de Neoplasias , Proteínas Nucleares/metabolismo , Pronóstico , Transducción de Señal

RESUMEN

Although gastric cancer is one of the most common causes of cancer death in the world, mechanisms underlying this type of tumor have not been fully understood. In this study, we found that IQGAP3, a member of the IQGAP gene family, was significantly up-regulated in human gastric cancer starting from the early stages of tumor progression. Overexpression of IQGAP3 in 293T and NIH3T3 cells, which have no endogenous IQGAP3 expression, resulted in morphological change with multiple dendritic-like protrusions and enhanced migration. Overexpression of IQGAP3 also led to reduced cell-cell adhesion in 293T cells, likely as a result of its interactions with e-cadherin or ß-catenin proteins. Additionally, IQGAP3 accumulated along the leading edge of migrating cells and at the cleavage furrow of dividing cells. In contrast, suppression of IQGAP3 by short-interfering RNA (siRNA) markedly reduced invasion and anchorage-independent growth of MKN1 and TMK-1 gastric cancer cells. We further confirmed that IQGAP3 interacted with Rho family GTPases, and had an important role in cytokinesis. Taken together, we demonstrated that IQGAP3 plays critical roles in migration and invasion of human gastric cancer cells, and regulates cytoskeletal remodeling, cell migration and adhesion. These findings may open a new avenue for the diagnosis and treatment of gastric cancer.

Asunto(s)

Proteínas Activadoras de GTPasa/genética , Proteínas Activadoras de GTPasa/metabolismo , Neoplasias Gástricas/patología , Regulación hacia Arriba , Animales , Línea Celular Tumoral , Movimiento Celular , Regulación Neoplásica de la Expresión Génica , Células HEK293 , Humanos , Ratones , Células 3T3 NIH , Clasificación del Tumor , Invasividad Neoplásica , Neoplasias Gástricas/genética , Neoplasias Gástricas/metabolismo

RESUMEN

Background: IQ motif-containing GTPase activating protein 3 (IQGAP3), the latest identified member of the IQGAP family, may act as a crucial factor in cancer development and progression; however, its clinical value in breast cancer remains unestablished. We explored the correlation between IQGAP3 expression profile and the clinicopathological features in breast cancer. Methods: IQGAP3 mRNA and protein levels were detected in breast cancer cell lines and tumor tissues by real-time PCR and western blotting and compared to the normal control groups. Protein expression of IQGAP3 was also evaluated immunohistochemically in archived paraffin-embedded specimens from 257 breast cancer patients, and the associations between IQGAP3 expression level, clinical characteristics, and prognosis were analyzed. We assessed the relationship between IQGAP3 expression and sensitivity to radiation therapy which was determined by subgroup analysis. Results: IQGAP3 was significantly upregulated in breast cancer cell lines and human tumor tissues at both the mRNA and protein level compared to controls. Additionally, high levels of IQGAP3 expression were detected in 110/257 (42.8%) of archived paraffin-embedded breast cancer specimens. High IQGAP3 expression level was significantly related to clinical stage (p = 0.001), T category (p = 0.002), N category (p = 0.001), locoregional recurrence (p = 0.002), distant metastasis (p = 0.001), and vital status (p = 0.001). Univariate and multivariate statistical analysis showed that IQGAP3 expression was an independent prognostic factor among all 257 breast cancer patients in our cohort (p = 0.003, p = 0.001). Subgroup analysis revealed IQGAP3 expression correlated with radioresistance and was also an independent predictor of radiotherapy outcome. Conclusion: Our findings suggest that high IQGAP3 expression predicts poor prognosis and radioresistance in breast cancer. Therefore, IQGAP3 may be a reliable prognostic biomarker in breast cancer and could be used to identify patients who may benefit from radiotherapy.

RESUMEN

BACKGROUND: The oncogene IQ motif-containing GTPase activating protein 3 (IQGAP3) is ubiquitously overexpressed in several human cancers. This study was designed to explore the expression and role of IQGAP3 in colorectal cancer. METHODS: We first assessed the IQGAP3 expression level in colorectal cancer. The correlation of IQGAP3 expression with the clinicopathological characteristics and prognosis was then assessed. At last, we investigated the function of IQGAP3 in colorectal cancer by knocking down its expression in colorectal cancer cell lines. RESULTS: Consistent with the conclusions drawn from The Cancer Genome Atlas database, IQGAP3 was upregulated in colorectal cancer at the tissue level and cellular level. Based on immunohistochemistry results of the tissue microarrays, we demonstrated that higher expression of IQGAP3 was associated with higher tumor node metastasis stage (P = 0.005), higher incidence of lymph node metastasis (P = 0.004), and shorter overall survival (P = 0.022). Knockdown of IQGAP3 in colorectal cancer cell lines remarkably decreased their proliferation and migration abilities. CONCLUSION: Our data provide evidence that IQGAP3 significantly promote malignant progression of colorectal cancer and could serve as a potential therapeutic target.

Asunto(s)

Neoplasias Colorrectales/metabolismo , Proteínas Activadoras de GTPasa/biosíntesis , Movimiento Celular/fisiología , Proliferación Celular/fisiología , Neoplasias Colorrectales/diagnóstico , Neoplasias Colorrectales/patología , Progresión de la Enfermedad , Femenino , Proteínas Activadoras de GTPasa/genética , Técnicas de Silenciamiento del Gen , Humanos , Masculino , Persona de Mediana Edad , Pronóstico

RESUMEN

BACKGROUND: The IQ-motif-containing GTPase-activating protein (IQGAP) family comprises three members, IQGAP1, IQGAP2 and IQGAP3. IQGAP3 is the latest addition to the family. This study mainly investigated the novel marker IQGAP3 at serum and tumor tissue levels compared with the markers B7-H4 and cyclooxygenase-2 (COX-2) in patients with colorectal cancer (CRC) and in healthy individuals, aiming to evaluate the diagnostic and prognostic value of IQGAP3 for CRC. MATERIALS AND METHODS: Serum samples were collected prior to any therapy in 118 CRC patients and as part of a routine examination in 85 healthy individuals. Serum IQGAP3, B7-H4 and COX-2 levels were measured using commercially available ELISA kits. Immunohistochemistry was performed to detect the IQGAP3, B7-H4 and COX-2 in tumor tissues and normal para-carcinoma tissues. The receiver operating characteristics (ROC) curve and the area under the curve (AUC) were used to evaluate and compare the diagnostic value of different serum tumor markers. Univariate and multivariate analyses were performed to identify the prognostic risk factors for CRC. RESULTS: IQGAP3, B7-H4 and COX-2 showed low or high expression in tumor tissues while no expression in normal para-carcinoma tissues. Serum levels of IQGAP3 in CRC group were significantly higher than those in healthy control group (P < 0.001). The IQGAP3 AUC was 0.799, while the B7-H4 AUC was 0.795 and the COX-2 AUC was 0.796. IQGAP3 seemed to be superior to B7-H4 and COX-2 in detecting CRC, with the highest sensitivity among the three markers. Multivariate analysis showed that T stage, N stage, differentiation degree, TNM stage and both serum and tissue IQGAP3, B7-H4 and COX-2 levels were significant prognostic factors for CRC. CONCLUSIONS: IQGAP3 has a better diagnostic efficacy than B7-H4 and COX-2 in detecting CRC and it has value in predicting the prognosis of patients with CRC.