IQGAP1 plays an important role in the invasiveness of thyroid cancer

IQGAP1 overexpression attenuates chemosensitivity through YAP-mediated ferroptosis inhibition in esophageal squamous cell cancer cells

Chemoresistance is one of the major hindrances to many cancer therapies, including esophageal squamous cell carcinoma (ESCC). Ferroptosis, a new programmed cell death, plays an essential role in chemoresistance. IQ-domain GTPase activating protein 1 (IQGAP1) is a scaffold protein and functions as an oncogene in various human malignancies. However, the underlying effect and molecular mechanisms of IQGAP1 on paclitaxel (PTX) resistance and ferroptosis in ESCC remain to be elucidated. In this study, we found that IQGAP1 was highly expressed in ESCC tissues and could as a potential biomarker for diagnosis and predicting the prognosis of ESCC. Functional studies revealed that IQGAP1 overexpression reduced the sensitivity of ESCC cells to PTX by enhancing ESCC cell viability and proliferation and inhibiting cell death, and protected ESCC cells from ferroptosis, whereas IQGAP1 knockdown exhibited contrary effects. Importantly, reductions of chemosensitivity and ferroptosis caused by IQGAP1 overexpression were reversed with ferroptosis inducer RSL3, while the increases of chemosensitivity and ferroptosis caused by IQGAP1 knockdown were reversed with ferroptosis inhibitor ferrostatin-1 (Fer-1) in ESCC cells, indicating that IQGAP1 played a key role in resistance to PTX through regulating ferroptosis. Mechanistically, we demonstrated that IQGAP1 overexpression upregulated the expression of Yes-associated protein (YAP), the central mediator of the Hippo pathway. YAP inhibitor Verteporfin (VP) could reverse the effects of IQGAP1 overexpression on ESCC chemoresistance and ferroptosis. Taken together, our findings suggest that IQGAP1 promotes chemoresistance by blocking ferroptosis through targeting YAP. IQGAP1 may be a novel therapeutic target for overcoming chemoresistance in ESCC.

Identification of disulfidptosis-associated genes and characterization of immune cell infiltration in thyroid carcinoma

OBJECTIVE

The primary objective of this study is to conduct a comprehensive screening and analysis of differentially expressed genes related to disulfidoptosis (DEDRGs) in thyroid carcinoma (THCA). This entails delving into the intricate characterization of immune cell infiltration within the THCA context and subsequently formulating and validating a novel prognostic model.

METHOD

To achieve our objectives, we first delineated two distinct subtypes of disulfidoptosis-related genes (DRGs) via consensus clustering methodology. Subsequently, employing the limma R package, we identified the DEDRGs critical for our investigation. These DEDRGs underwent meticulous validation across various databases, alongside an in-depth analysis of gene regulation. Employing functional enrichment techniques, we explored the potential molecular mechanisms underlying disulfidoptosis in THCA. Furthermore, we scrutinized the immune landscape within the two identified subtypes utilizing CIBERSORT and ESTIMATE algorithms. The construction of the prognostic model for THCA entailed intricate methodologies including univariate, multivariate Cox regression, and LASSO regression algorithms. The validity and efficacy of our prognostic model were corroborated through Kaplan-Meier survival curves and ROC curves. Additionally, a nomogram was meticulously formulated to facilitate the prediction of patient prognosis. To fortify our findings, we conducted a comprehensive Bayesian co-localization analysis coupled with rigorous in vitro experimentation, aimed at unequivocally establishing the validity of the identified DEDRGs.

RESULT

Our analyses unveiled Cluster C1, characterized by elevated expression levels of DEDRGs, as harboring a favorable prognosis accompanied by abundant immune cell infiltration. Correlation analyses underscored predominantly positive associations among the DEDRGs, further affirming their significance in THCA. Differential expression patterns of DEDRGs between tumor samples and normal tissues were evident across the GEPIA and HPA databases. Insights from the TIMER database underscored a robust correlation between DEDRGs and immune cell infiltration. KEGG analysis elucidated the enrichment of DEDRGs primarily in pivotal pathways including MAPK, PPAR signaling pathway, and Proteoglycans in cancer. Furthermore, analyses using CIBERSORT and ESTIMATE algorithms shed light on the crucial role played by DEDRGs in shaping the immune microenvironment. The prognostic model, anchored by five genes intricately associated with THCA prognosis, exhibited commendable predictive accuracy and was intricately linked to the tumor immune microenvironment. Notably, patients categorized with low-risk scores stood to potentially benefit more from immunotherapy. The validation of DEDRGs unequivocally underscores the protective role of INF2 in THCA.

CONCLUSION

In summary, our study delineates two discernible subtypes intricately associated with DRGs, revealing profound disparities in immune infiltration and survival prognosis within the THCA milieu. The implications of our findings extend to potential treatment strategies for THCA patients, which could entail targeted interventions directed towards DEDRGs and prognostic genes, thereby influencing disulfidptosis and the immune microenvironment. Moreover, the robust predictive capability demonstrated by our prognostic model, based on the five genes (ANGPTL7, FIRRE, ODAPH, PROKR1, SFRP5), underscores its potential clinical utility in guiding personalized therapeutic approaches for THCA patients.

Illuminating the role of lncRNAs ROR and MALAT1 in cancer stemness state of anaplastic thyroid cancer: An exploratory study

Background

Anaplastic thyroid cancer (ATC) is one of the most aggressive malignancies in humans that accounts for a considerable rate of cancer-associated mortality. Since conventional therapies are lacking sufficient efficacy, new treatment approaches are required. This goal could be achieved through a better understanding of the molecular pathogenesis of ATC. Thyroid tumorigenesis is initiated by a subpopulation of cells known as cancer stem cells (CSCs) with specific markers such as CD133 that confers to processes such as self-renewal and metastasis. Besides, some long non-coding RNAs (lncRNAs) promote tumorigenesis by mediating the aforementioned processes.

Methods

Here, we designed an exploratory study to investigate the role of lncRNAs ROR and MALAT1 and their related genes in CSC stemness. Using magnetic-activated cell sorting (MACS), the CD133^- and CD133⁺ subpopulations were separated in SW1736 and C643 ATC cell lines. Next, the expression profiles of the CD133 marker, MALAT1, and its associated genes (CCND1, NESTIN, MYBL2, MCL1, IQGAP1), as well as ROR and its related genes (POU5F1, SOX2, NANOG), were explored by qRT-PCR.

Results

We found significant up-regulation of ROR, POU5F1, SOX2, NANOG, CD133, MALAT1, IQGAP1, and MCL1 in CD133⁺ SW1736 cells compared to CD133^- cells. As for CD133⁺ C643 cells, CCND1, IQGAP1, POU5F1, SOX2, NANOG, and NESTIN were significantly up-regulated compared to CD133^- cells.

Conclusions

This study suggests that these lncRNAs in CD133-positive SW1736 and C643 cells might regulate stemness behaviors in ATC.

Molecular basis and targeted therapy in thyroid cancer: Progress and opportunities

Thyroid cancer (TC) is the most prevalent endocrine malignant tumor. Surgery, chemotherapy, radiotherapy, and radioactive iodine (RAI) therapy are the standard TC treatment modalities. However, recurrence or tumor metastasis remains the main challenge in the management of anaplastic thyroid cancer (ATC) and radioiodine (RAI) radioactive iodine-refractory differentiated thyroid cancer (RR-DTC). Several multi-tyrosine kinase inhibitors (MKIs), or immune checkpoint inhibitors in combination with MKIs, have emerged as novel therapies for controlling the progression of DTC, medullary thyroid cancer (MTC), and ATC. Here, we discuss and summarize the molecular basis of TC, review molecularly targeted therapeutic drugs in clinical research, and explore potentially novel molecular therapeutic targets. We focused on the evaluation of current and recently emerging tyrosine kinase inhibitors approved for systemic therapy for TC, including lenvatinib, sorafenib and cabozantinib in DTC, vandetanib, cabozantinib, and RET-specific inhibitor (selpercatinib and pralsetinib) in MTC, combination dabrafenib with trametinib in ATC. In addition, we also discuss promising treatments that are in clinical trials and may be incorporated into clinical practice in the future, briefly describe the resistance mechanisms of targeted therapies, emphasizing that personalized medicine is critical to the design of second-line therapies.

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.

Overexpressed ZC3H13 suppresses papillary thyroid carcinoma growth through m6A modification-mediated IQGAP1 degradation

PURPOSE

The purpose of this study was to clarify the effect of ZC3H13 on the growth of papillary thyroid carcinoma (PTC).

METHODS

Firstly, we used qRT-PCR and Western blot to compare the difference in the expression of ZC3H13 between normal thyroid epithelial cells and PTC cell lines. Then, ZC3H13 overexpression/knockout thyroid cancer cells were constructed by lentivirus transfection, and the effects of overexpression of ZC3H13 on the proliferation, migration and invasion of PTC cells were detected by CCK8 and transwell experiments. Lastly, MeRIP-qPCR, RIP and o Actinomycin D were used to verify that ZC3H13 regulated the expression of downstream target gene IQGAP1 through m6A modification.

RESULTS

ZC3H13 expression was decreased in PTC cell lines BCPAP, KTC-1, k1, HTH83, and TPC-1. Proliferation, invasion, and migration of PTC cells were inhibited by overexpressed ZC3H13 but increased by knockdown of ZC3H13. IQGAP1 expression was suppressed by ZC3H13 overexpression but enhanced by ZC3H13 knockdown. In ZC3H13-overexpressed PTC cells, the m6A level of IQGAP1 mRNA was increased, and the IQGAP1 mRNA expression was decreased with the increasing time of Actinomycin D treatment. YTHDF2 enriched more IQGAP1 mRNA than IgG and knockdown of YTHDF2 reversed the effect of ZC3H13 overexpression on IQGAP1 mRNA stability. The xenograft tumor experiment in nude mice confirmed that the overexpression of ZC3H13 inhibited tumor growth, while overexpression of IQGAP1 could reverse the inhibitory effect of ZC3H13 overexpression on tumor growth.

CONCLUSION

ZC3H13 mediates IQGAP1 mRNA degradation by promoting m6A modification of IQGAP1 mRNA, this provides a prospective therapeutic target for PTC.

Genomic and epigenomic profile of thyroid cancer

Thyroid cancer is the most common malignancy of the endocrine system, and its incidence has been steadily increasing. Advances in sequencing have allowed analysis of the entire cancer genome, and has provided new information on the genetic lesions and modifications responsible for the onset, progression, dedifferentiation and metastasis of thyroid carcinomas. Moreover, integrated genomics has advanced our understanding of the development of cancer and its behavior, and has facilitated the identification of new genetic mutations and molecular pathways. The functional analysis of epigenetic modifications, such as DNA methylation, histone acetylation and non-coding RNAs, have contributed to define new regulatory mechanisms that control cell malignancy in thyroid cancer, especially aggressive forms. Here we review the most recent advances in genomics and epigenomics of thyroid cancer, which have resulted in a new classification and interpretation of the initiation and progression of thyroid tumors, providing new tools and opportunities for further investigation and for the clinical development of new treatment strategies.

Radiosensitivity-Specific Proteomic and Signaling Pathway Network of Non-Small Cell Lung Cancer (NSCLC)

PURPOSE

An unmet clinical need in non-small cell lung cancer (NSCLC) management is the accurate prediction of radiation response in patients receiving radical radiation therapy. We explored the intrinsic radiosensitivity of NSCLC from the proteomic profiles of NSCLC cell lines and paraffin-embedded human samples.

METHODS AND MATERIALS

To uncover radiosensitivity-specific proteomic and signaling pathways, we performed quantitative proteomics by data-independent acquisition mass spectrometry assay on 29 human NSCLC cell lines and 13 paraffin-embedded human NSCLC samples. We validated closely interacting radioresistant proteins by western blotting, immunofluorescence, real-time quantitative polymerase chain reaction in NSCLC cell lines, and immunohistochemistry in paraffin-embedded human samples. We validated the functions of 3 key hub proteins by lentivirus transfection, clonogenic survival assay, and flow cytometry.

RESULTS

The proteomic profiling of NSCLC showed that the intrinsic radiosensitivity of NSCLC is mainly modulated by signaling pathways of proteoglycans in cancer, focal adhesion, and regulation of the actin cytoskeleton. We identified 71 differentially expressed proteins and validated 8 closely interacting proteins as radioresistant proteins of NSCLC. Moreover, we also validated the functionality of integrin-linked protein kinase, p21-activated kinase 1, and Ras GTPase-activating-like protein IQGAP1 in the radiation response of NSCLC cell lines. Finally, with the NSCLC radiosensitivity-specific proteins, we delineated the atlas network of NSCLC radiosensitivity-related signaling pathways.

CONCLUSIONS

Radiosensitivity-specific proteins could guide individualized radiation therapy in clinical practice by predicting the radiation response of patients with NSCLC. Moreover, the NSCLC radiosensitivity-related signaling pathway atlas could guide further exploration of the underlying mechanism.

Akt scaffold proteins: the key to controlling specificity of Akt signaling

The phosphatidylinositol 3-kinase-Akt signaling pathway plays an essential role in regulating cell proliferation and apoptosis. Akt kinase is at the center of this signaling pathway and interacts with a variety of proteins. Akt is overexpressed in almost 80% of tumors. However, inhibiting Akt has serious clinical side effects so is not a suitable treatment for cancer. During recent years, Akt scaffold proteins have received increasing attention for their ability to regulate Akt signaling and have emerged as potential targets for cancer therapy. In this paper, we categorize Akt kinase scaffold proteins into four groups based on their cellular location: membrane-bound activator and inhibitor, cytoplasm, and endosome. We describe how these scaffolds interact with Akt kinase, how they affect Akt activity, and how they regulate the specificity of Akt signaling. We also discuss the clinical application of Akt scaffold proteins as targets for cancer therapy.

The interplay between IQGAP1 and small GTPases in cancer metastasis

The metastatic spread of tumor cells to distant anatomical locations is a critical cause for disease progression and leads to more than 90 % of cancer-related deaths. IQ motif-containing GTPase-activating protein 1 (IQGAP1), a prominent regulator in the cancer metastasis process, is a scaffold protein that interacts with components of the cytoskeleton. As a critical node within the small GTPase network, IQGAP1 acts as a binding partner of several small GTPases, which in turn function as molecular switches to control most cellular processes, including cell migration and invasion. Given the significant interaction between IQGAP1 and small GTPases in cancer metastasis, we briefly elucidate the role of IQGAP1 in regulating cancer metastasis and the varied interactions existing between IQGAP1 and small GTPases. In addition, the potential regulators for IQGAP1 activity and its interaction with small GTPases are also incorporated in this review. Overall, we comprehensively summarize the role of IQGAP1 in cancer tumorigenicity and metastasis, which may be a potential anti-tumor target to restrain cancer progression.

Effective Prediction of Prostate Cancer Recurrence through the IQGAP1 Network

IQGAP1 expression was analyzed in: (1) primary prostate cancer, (2) xenografts produced from LNCaP, DU145, and PC3 cells, 3) tumor of PTEN-/- and TRAMP mice, and (3) castration resistant PC (CRPC) produced by LNCaP xenografts and PTEN-/- mice. IQGAP1 downregulations occurred in CRPC and advanced PCs. The downregulations were associated with rapid PC recurrence in the TCGA PanCancer (n = 492, p = 0.01) and MSKCC (n = 140, p = 4 × 10-6) cohorts. Differentially expressed genes (n = 598) relative to IQGAP1 downregulation were identified with enrichment in chemotaxis, cytokine signaling, and others along with reductions in immune responses. A novel 27-gene signature (Sig27gene) was constructed from these DEGs through random division of the TCGA cohort into a Training and Testing population. The panel was validated using an independent MSKCC cohort. Sig27gene robustly predicts PC recurrence at (hazard ratio) HR 2.72 and p < 2 × 10-16 in two independent PC cohorts. The prediction remains significant after adjusting for multiple clinical features. The novel and robust nature of Sig27gene underlie its great translational potential as a prognostic biomarker to predict PC relapse risk in patients with primary PC.

Regulatory Networks of LncRNA MALAT-1 in Cancer

Long noncoding (lnc)RNAs are a group of RNAs with a length greater than 200 nt that do not encode a protein but play an essential role in regulating the expression of target genes in normal biological contexts as well as pathologic processes including tumorigenesis. The lncRNA metastasis-associated lung adenocarcinoma transcript (MALAT)-1 has been widely studied in cancer. In this review, we describe the known functions of MALAT-1; its mechanisms of action; and associated signaling pathways and their clinical significance in different cancers. In most malignancies, including lung, colorectal, thyroid, and other cancers, MALAT-1 functions as an oncogene and is upregulated in tumors and tumor cell lines. MALAT-1 has a distinct mechanism of action in each cancer type and is thus at the center of large gene regulatory networks. Dysregulation of MALAT-1 affects cellular processes such as alternative splicing, epithelial–mesenchymal transition, apoptosis, and autophagy, which ultimately results in the abnormal cell proliferation, invasion, and migration that characterize cancers. In other malignancies, such as glioma and endometrial carcinoma, MALAT-1 functions as a tumor suppressor and thus forms additional regulatory networks. The current evidence indicates that MALAT-1 and its associated signaling pathways can serve as diagnostic or prognostic biomarker or therapeutic target in the treatment of many cancers.

Integrative Analysis of the IQ Motif-Containing GTPase-Activating Protein Family Indicates That the IQGAP3-PIK3C2B Axis Promotes Invasion in Colon Cancer

Background

Colon cancer (CRC) is a common type of tumour, and IQGAP family proteins play an important role in many tumours. However, their roles in CRC remain unclear.

Methods

First, we searched many public databases to comprehensively analyze expression of IQGAPs in CRC. Next, real-time PCR, immunohistochemical (IHC), transwell, siRNA transfection and Western blot assays were used to evaluate relationships among IQGAP3 expression, clinical pathological parameters and CRC prognosis, and the underlying molecular mechanism was investigated.

Results

IQGAP3 was elevated in CRC tissues, whereas there was no significant change in expression of IQGAP1 or IQGAP2. Additionally, IQGAP3 expression in CRC tissues was associated with tumour progression, invasion and poor prognosis. In mechanistic studies, we found that IQGAP3 was positively coexpressed with PIK3C2B. In an in vitro assay, the PIK3C2B expression level was increased after exogenous overexpression of IQGAP3, resulting in the promotion of cell invasion, which was blocked by pretransfecting cells with PIK3C2B siRNA. Furthermore, we found that high expression of IQGAP3 and PIK3C2B correlated with tumour stage and vessel invasion in human CRC, whereby patients with high expression of both in tumours had a worse prognosis compared with patients with single-positive or double-negative tumours.

Conclusion

The results of our current study and corresponding previous studies provide evidence that IQGAP3 is elevated in CRC and promotes colon cancer growth and metastasis by regulating PIK3C2B activation.

High expression of IQGAP3 indicates poor prognosis in colorectal cancer patients

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.

Personalized treatment options for thyroid cancer: current perspectives

Thyroid cancer is one of the most common endocrine malignancies, with increasing incidence all over the world. In spite of good prognosis for differentiated thyroid carcinoma, for an unknown reason, about 5–10% of the patients, the cancer will show aggressive behavior, develop metastasis, and be refractory to treatment strategies like radioactive iodine. Regarding the genetic information, each thyroid cancer patient can be considered as an individual unique one, with unique genetic information. Contrary to standard chemotherapy drugs, target therapy components aim at one or more definite molecular pathway on cancer cells, so their selection is underlying patient’s genetic information. Nowadays, several mutations and rearrangements including BRAF, VEGF receptors, RET, and RET/PTC, KDR, KIT, PDGFRA, CD274, and JAK2 are taken into account for the therapeutic components like larotrectinib (TRK inhibitor), vemurafenib, sunitinib, sorafenib, selumetinib, and axitinib. With the new concept of personalized treatment of thyroid cancer diagnoses, planning treatment, finding out how well treatment will work, and estimating a prognosis has changed for the better over the last decade.

Regulators of the RAS-ERK pathway as therapeutic targets in thyroid cancer

Thyroid cancer is mostly an ERK-driven carcinoma, as up to 70% of thyroid carcinomas are caused by mutations that activate the RAS/ERK mitogenic signaling pathway. The incidence of thyroid cancer has been steadily increasing for the last four decades; yet, there is still no effective treatment for advanced thyroid carcinomas. Current research efforts are focused on impairing ERK signaling with small-molecule inhibitors, mainly at the level of BRAF and MEK. However, despite initial promising results in animal models, the clinical success of these inhibitors has been limited by the emergence of tumor resistance and relapse. The RAS/ERK pathway is an extremely complex signaling cascade with multiple points of control, offering many potential therapeutic targets: from the modulatory proteins regulating the activation state of RAS proteins to the scaffolding proteins of the pathway that provide spatial specificity to the signals, and finally, the negative feedbacks and phosphatases responsible for inactivating the pathway. The aim of this review is to give an overview of the biology of RAS/ERK regulators in human cancer highlighting relevant information on thyroid cancer and future areas of research.

IQGAP1 promotes pancreatic cancer progression and epithelial-mesenchymal transition (EMT) through Wnt/β-catenin signaling

IQ motif-containing GTPase-activating protein 1 (IQGAP1) is a scaffold protein that participates in several cellular functions, including cytoskeletal regulation, cell adhesion, gene transcription and cell polarization. IQGAP1 has been implicated in the tumorigenesis and progression of several human cancers. However, the role of IQGAP1 in pancreatic ductal adenocarcinoma (PDAC) is still unknown. We found that IQGAP1 expression was an independent prognostic factor for PDAC. IQGAP1 upregulation significantly promoted cell proliferation, migration, invasion and epithelial-mesenchymal transition (EMT), whereas IQGAP1 downregulation impaired its oncogenic functions. Overexpression of IQGAP1 increased the protein level of Dishevelled2 (DVL2) and enhanced canonical Wnt signaling as evidenced by increased DVL2 level, β-catenin transcriptional activity, β-catenin nuclear translocation and expression of the direct target genes of β-catenin (cyclin D1 and c-myc). In contrast, knockdown of IQGAP1 decreased the level of DVL2 and attenuated Wnt/β-catenin signaling. In vivo results revealed that IQGAP1 promoted tumor growth and metastasis. Co-immunoprecipitation studies demonstrated that IQGAP1 interacted with both DVL2 and β-catenin. Moreover, knockdown of DVL2 reversed IQGAP1-induced EMT. Our findings thus confirmed that IQGAP1 could be used as a potential target for PDAC treatment.

Ras GTPase-Activating-Like Protein IQGAP1 (IQGAP1) Promotes Breast Cancer Proliferation and Invasion and Correlates with Poor Clinical Outcomes

BACKGROUND Breast cancer is one of the most common female cancers in the world. As a key integrator of cell signaling pathways, IQGAP1 contributes to the development and progression of several cancers. However, the exact effects and molecular mechanisms of IQGAP1 in breast cancer progression remain poorly understood. MATERIAL AND METHODS In the present study, IQGAP1 expression was measured in 96 paired breast cancer samples and the corresponding adjacent non-cancerous tissues by immunohistochemistry and quantitative polymerase chain reaction. To further explore the biological function of IQGAP1 in breast cancer cells, we knocked down IQGAP1 expression in MCF-7 cells and overexpressed it in SK-BR-3 cells. RESULTS IQGAP1 was specifically upregulated in breast cancer tissues compared with the corresponding adjacent non-cancerous tissues. Moreover, IQGAP1 expression was positively correlated with breast cancer survival rate. IQGAP1 also promoted breast cancer cell proliferation and cell cycle progression and suppressed apoptosis. CONCLUSIONS In conclusion, our results suggest that IQGAP1 plays an important role in the cell proliferation and invasion of human breast cancer cells, thus indicating that IQGAP1 may be a potential therapeutic target for the treatment of human breast cancer.

Regulating Cdc42 and Its Signaling Pathways in Cancer: Small Molecules and MicroRNA as New Treatment Candidates

Despite great improvements in the diagnosis and treatment of neoplasms, metastatic disease is still the leading cause of death in cancer patients, with mortality rates still rising. Given this background, new ways to treat cancer will be important for development of improved cancer control strategies. Cdc42 is a member of the Rho GTPase family and plays an important role in cell-to-cell adhesion, formation of cytoskeletal structures, and cell cycle regulation. It thus influences cellular proliferation, transformation, and homeostasis, as well as the cellular migration and invasion processes underlying tumor formation. Cdc42 acts as a collection point for signal transduction and regulates multiple signaling pathways. Moreover, recent studies show that in most human cancers Cdc42 is abnormally expressed and promoting neoplastic growth and metastasis. Regarding possible new treatments for cancer, miRNA and small molecules targeting Cdc42 and related pathways have been recently found to be effective on cancer. In this review, we analyze the newly recognized regulation mechanisms for Cdc42 and Cdc42-related signal pathways, and particularly new treatments using small molecules and miRNAs to inhibit the abnormal overexpression of Cdc42 that may slow down the metastasis process, improve cancer therapy and lead to novel strategies for development of antineoplastic drugs.

Caveolin-1 promotes Ewing sarcoma metastasis regulating MMP-9 expression through MAPK/ERK pathway

Ewing sarcoma (ES) is a bone and soft tissue sarcoma affecting mostly children and young adults. Caveolin-1 (CAV1) is a well-known target of EWS/FLI1, the main driver of ES, with an oncogenic role in ES. We have previously described how CAV1 is able to induce metastasis in ES via matrix metalloproteinase-9 (MMP-9). In the present study we showed how CAV1 silencing in ES reduced MEK1/2 and ERK1/2 phosphorylation. Accordingly, chemical inhibition of MEK1/2 resulted in reduction in MMP-9 expression and activity that correlated with reduced migration and invasion. IQ Motif Containing GTPase Activating Protein 1 (IQGAP1) silencing reduced MEK1/2 and ERK1/2 phosphorylation and MMP-9 expression. Furthermore, IQGAP1 silenced cells showed a marked decrease in their migratory and invasive capacity. We demonstrated that CAV1 and IQGAP1 localize in close proximity at the cellular edge, thus IQGAP1 could be the connecting node between CAV1 and MEK/ERK in ES metastatic phenotype. Analysis of the phosphorylation profile of CAV1-silenced cells showed a decrease of p-ribosomal protein S6 (RPS6). RPS6 can be phosphorylated by p90 ribosomal S6 kinases (RSK) proteins. CAV1-silenced cells showed reduced levels of p-RSK1 and treatment with U0126 provoked the same effect. Despite not affecting ERK1/2 and RPS6 phosphorylation status neither MMP-9 expression nor activity, RSK1 silencing resulted in a reduced migratory and invasive capacity in vitro and reduced incidence of metastases in vivo in a novel orthotopic model. The present work provides new insights into CAV1-driven metastatic process in ES unveiling novel key nodes.

Reactivation of epigenetically silenced miR-124 reverses the epithelial-to-mesenchymal transition and inhibits invasion in endometrial cancer cells via the direct repression of IQGAP1 expression

Overexpression of IQGAP1 and microRNA (miRNA) dysregulation are frequent in human tumors, but little is known about the role of IQGAP1 and its relationship to miRNA in endometrial carcinogenesis. We demonstrate that IQGAP1 activates the epithelial–mesenchymal transition (EMT) program and that miR-124 directly represses IQGAP1 expression in endometrial cancer (EC) cells. The overexpression of IQGAP1 stimulates EMT features and enhances migration, invasion and proliferation of EC cells, whereas knocking down IQGAP1 expression reverses EMT and inhibits these malignant properties. Using miRNA microarray profiling, we identified 29 miRNAs (let-7b, let-7f, miR-10b, miR-15b, miR-23a, miR-24, miR-25, miR-27a, miR-29b, miR-30a-5p, miR-34a, miR-124, miR-127, miR-130b, miR-148a, miR-155, miR-191*, miR-194, miR-224, miR-362, miR-409-3p, miR-422b, miR-424, miR-453, miR-497, miR-518d, miR-518f*, miR-526a and miR-656) that are significantly down-regulated in an in vitro-selected highly invasive derivative cell line (HEC-50-HI) relative to the parental HEC-50 cells. We further identified miR-124 as a direct regulator of IQGAP1 in EC cells. Enforced expression of miR-124 suppresses EC cell invasion and proliferation. The expression of IQGAP1 mRNA was significantly elevated in EC tissues, while the expression of miR-124 was decreased. The downregulation of miR-124 correlates with a poor survival outcome for patients with EC. Treating EC cells with the demethylating agent 5-aza-2′-deoxycytidine increased miR-124 expression and down-regulated IQGAP1 levels. Our data suggest that IQGAP1 promotes EMT, migration and invasion of EC cells. MiR-124, a novel tumor suppressor miRNA that is epigenetically silenced in EC, can reverse EMT and the invasive properties, by attenuating the expression of the IQGAP1 oncogene.

Proteomic analysis reveals differential protein expression in variants of papillary thyroid carcinoma

Introduction

Fine Needle Aspiration Biopsy (FNAB) allows the cytological differentiation of benign and malignant thyroid nodules. However, the method itself is not adequate in determining some cases. For example, the diagnosis of Follicular Variant Papillary Thyroid Carcinoma (FV-PTC) can be challenging. In the current study we investigate the protein profiles of FV-PTC and classical variant PTC (CV-PTC) with no lymph node metastasis and compare it with benign thyroid tissue.

Method

We used CV-PTC (n = 6), FV-PTC (n = 6) and benign thyroid tissues (n = 6) to prepare tissue lysates. Proteins from each group were trypsin and lys-C digested. The samples were analyzed on a Q Exactive Orbitrap mass spectrometer.

Results

We identified 2560 proteins across all 18 specimens. Protein profiles revealed that there was no clear distinction between benign and FV-PTC samples. However, further examination of our data showed that proteins in energy metabolism have altered in FV-PTC. Proteomic pathway analysis showed marked alteration of the actin cytoskeleton proteins, especially several members of Arp2/3 complex were significantly increased in CV-PTC. We made the novel observation that IQGAP1 protein was significantly increased in CV-PTC, whereas IQGAP2 protein was highly expressed in FV-PTC lesions, suggesting differential roles of IQGAP proteins in thyroid pathology.

Conclusion

In the present study, mass spectrometry based label free quantification approach was applied to investigate the protein profiles of FV-PTC, CV-PTC and benign thyroid tissues. This study pointed out that actin cytoskeleton proteins, IQGAP proteins and changes in energy metabolism play predominant roles in thyroid pathology.

IQGAP1 silencing suppresses the malignant characteristics of laryngeal squamous cell carcinoma cells

Background:

Laryngeal squamous cell carcinoma (LSCC) has a poor prognosis due to recurrence and metastasis. IQ-domain GTPase-activating protein 1 (IQGAP1), a scaffold protein, plays an important role in tumorigenesis and malignant development. In this study, we aimed to explore the role of IQGAP1 in LSCC.

Methods:

Expression of IQGAP1 in human LSCC specimens was assessed by immunohistochemistry. We also evaluated the roles of IQGAP1 in cell proliferation, migration and invasion and epithelial-to-mesenchymal transition (EMT) in Hep-2 cells.

Results:

The expression of IQGAP1 protein was significantly up-regulated in LSCC tissues compared with normal laryngeal tissues (p = 0.002). Furthermore, the knockdown of IQGAP1 in Hep-2 cells inhibited cell growth, migration and invasion. Moreover, we found that IQGAP1 silencing reversed EMT.

Conclusions:

These results show for the first time that IQGAP1 is up-regulated in LSCC tissues and plays an important role in LSCC cell proliferation and invasiveness, which indicates that IQGAP1 could work as an oncogene and may serve as a promising molecular target for treatment of LSCC.

Knockdown of IQGAP1 inhibits proliferation and epithelial-mesenchymal transition by Wnt/β-catenin pathway in thyroid cancer

Background

Thyroid cancer is the most common endocrine malignant disease with a high incidence rate. The expression of IQGAP1 is upregulated in various cancers, including thyroid cancer. However, the role and underlying mechanism of IQGAP1 in thyroid cancer are still not clear.

Materials and methods

The expression of IQGAP1 in thyroid cancer tissues and cells was determined by reverse transcription polymerase chain reaction and Western blot analysis. Cells were transfected with different siRNAs using Lipofectamine 2000 or were treated with various concentrations of XAV939. The effects of IQGAP1 knockdown on proliferation and epithelial–mesenchymal transition (EMT) of thyroid cancer cells were determined by MTT assay and Western blot analysis. Animal experiments were performed to investigate the effects of IQGAP1 knockdown on the growth of tumors in vivo.

Results

High IQGAP1 expression is found in thyroid cancer tissues and cells. Knockdown of IQGAP1 had inhibitory effects on cell proliferation and EMT, as well as on the Wnt/β-catenin pathway. Additionally, inactivation of the Wnt/β-catenin pathway by XAV939 or si-β-catenin suppressed cell proliferation and EMT. Furthermore, suppression of the Wnt/β-catenin pathway reversed the positive effects of pcDNA-IQGAP1 on cell proliferation and EMT in vitro. Moreover, downregulation of IQGAP1 suppressed tumor growth and EMT in SW579 tumor xenografts through the Wnt/β-catenin pathway in vivo.

Conclusion

Our study demonstrated that knockdown of IQGAP1 inhibited cell proliferation and EMT through blocking the Wnt/β-catenin pathway in thyroid cancer.

Overexpression and biological function of IQGAP3 in human pancreatic cancer

IQGAP3 (IQ motif containing GTPase activating protein3) belongs to IQGAP family. Recent studies have investigated that IQGAP3 was overexpressed in several tumor tissues. This study was designed to explore the expression and role of IQGAP3 in pancreatic cancer, a highly lethal disease. IQGAP3 mRNA expression was significantly increased in pancreatic cancer tissues, compared with non-cancerous tissues. Moreover, its expression was strongly associated with tumor size, differentiation, lymph node metastasis and patients' overall survival. Gene set enrichment analysis (GSEA) on The Cancer Genome Atlas (TCGA) dataset showed that cell apoptosis, metastasis and Cdc42 pathways were strongly associated with IQGAP3 expression in pancreatic cancer patients. Knocking down of IQGAP3 in two pancreatic cancer cell lines with high level of IQGAP3 (BXPC-3 and SW1990) significantly inhibited cell proliferation, migration and invasion, and induced cell apoptosis. Moreover, silencing of IQGAP3 also affected the expression of cell apoptosis-, metastasis- and Cdc42 pathway-related proteins. Cdc42 knockdown had similar inhibitory effects on the cellular behavior of BXPC-3 cells. In conclusion, IQGAP3 may act as an oncogene in pancreatic cancer through regulating Cdc42 expression. Our data suggest IQGAP3 might be a novel diagnostic marker and therapeutic target for this cancer.

Diet-induced hypercholesterolemia promotes androgen-independent prostate cancer metastasis via IQGAP1 and caveolin-1

Obesity and metabolic syndrome are associated with several cancers, however, the molecular mechanisms remain to be fully elucidated. Recent studies suggest that hypercholesterolemia increases intratumoral androgen signaling in prostate cancer, but it is unclear whether androgen-independent mechanisms also exist. Since hypercholesterolemia is associated with advanced, castrate-resistant prostate cancer, in this study, we aimed to determine whether and how hypercholesterolemia affects prostate cancer progression in the absence of androgen signaling. We demonstrate that diet-induced hypercholesterolemia promotes orthotopic xenograft PC-3 cell metastasis, concomitant with elevated expression of caveolin-1 and IQGAP1 in xenograft tumor tissues. In vitro cholesterol treatment of PC-3 cells stimulated migration and increased IQGAP1 and caveolin-1 protein level and localization to a detergent-resistant fraction. Down-regulation of caveolin-1 or IQGAP1 in PC-3 cells reduced migration and invasion in vitro, and hypercholesterolemia-induced metastasis in vivo. Double knock-down of caveolin-1 and IQGAP1 showed no additive effect, suggesting that caveolin-1 and IQGAP1 act via the same pathway. Taken together, our data show that hypercholesterolemia promotes prostate cancer metastasis independent of the androgen pathway, in part by increasing IQGAP1 and caveolin-1. These results have broader implications for managing metastasis of cancers in general as IQGAP1 and hypercholesterolemia are implicated in the progression of several cancers.

Molecular Aberrance in Papillary Thyroid Microcarcinoma Bearing High Aggressiveness: Identifying a "Tibetan Mastiff Dog" From Puppies

Today the most common differentiated thyroid cancer in many countries is papillary thyroid microcarcinoma (PTMC). Although the majority of PTMCs exhibit an indolent clinical course, a few possess high risk for aggressiveness with tumor invasion, metastasis, and even patient mortality. This imposes significant confusion and often dilemma in the clinical management of PTMC. The present review summarizes the molecular pathogenesis, particularly the major genetic alterations, of PTMC that may have prognostic values in assisting risk stratification of this cancer and identification of the most aggressive cases from the many well-behaving cases. J. Cell. Biochem. 117: 1491-1496, 2016. © 2016 Wiley Periodicals, Inc.

Pharmacological targeting of AKAP-directed compartmentalized cAMP signalling

The second messenger cyclic adenosine monophosphate (cAMP) can bind and activate protein kinase A (PKA). The cAMP/PKA system is ubiquitous and involved in a wide array of biological processes and therefore requires tight spatial and temporal regulation. Important components of the safeguard system are the A-kinase anchoring proteins (AKAPs), a heterogeneous family of scaffolding proteins defined by its ability to directly bind PKA. AKAPs tether PKA to specific subcellular compartments, and they bind further interaction partners to create local signalling hubs. The recent discovery of new AKAPs and advances in the field that shed light on the relevance of these hubs for human disease highlight unique opportunities for pharmacological modulation. This review exemplifies how interference with signalling, particularly cAMP signalling, at such hubs can reshape signalling responses and discusses how this could lead to novel pharmacological concepts for the treatment of disease with an unmet medical need such as cardiovascular disease and cancer.

IQGAP1 modulates the proliferation and invasion of thyroid cancer cells in response to estrogen

Thyroid cancer is an endocrine malignancy with a high incidence rate, which is affected by female hormones, particularly estrogens, in its growth and progression. IQ-domain GTPase-activating protein 1 (IQGAP1) is overexpressed in a range of types of cancer and is reported to interact with estrogen receptor α (ERα) in breast cancer cells. However, the association between IQGAP1 and ERα in thyroid cancer cells remains to be elucidated. In this study, the role of IQGAP1 in thyroid cancer cells was examined. The expression of IQGAP1 (190 kDa) was analyzed using western blot analysis, which indicated that IQGAP1 was overexpressed in thyroid cancer tissues and FTC133 cells. However, IQGAP1 knockdown in the FTC133 cells led to a significant downregulation in ERα transcriptional activity, cell proliferation, cell adhesion and cell invasion under 17β-estradiol (E2) conditions. Furthermore, ERα knockdown inhibited the enhanced protein expression levels of phosphorylated ERK1/2 and cyclin D1, which were induced by the overexpression of IQGAP1. Co-immunoprecipitation was also performed in thyroid cancer cells and the results suggested that IQGAP1 directly interacted with ERα in the FTC133 cells and the co-transfected COS-7 cells. Taken together, these findings revealed that IQGAP1 may directly interact with ERα and serve as a signal integrator, mediating ERα transcriptional activity, cell proliferation and cell invasion during the progression of thyroid cancer.

Comparison of the clinicopathological behavior of the follicular variant of papillary thyroid carcinoma and classical papillary thyroid carcinoma: A systematic review and meta-analysis

The follicular variant of papillary thyroid carcinoma (FV-PTC) is the second most common type of papillary thyroid carcinoma (PTC), and it has been increasingly diagnosed in recent years. However, whether FV-PTC behaves differently from classical PTC (C-PTC) remains controversial. To address this controversy, a meta-analysis was performed to determine the potential differences between FV-PTC and C-PTC in their clinicopathological behavior. The relevant published studies between January 1, 2003 and August 31, 2014 were reviewed according to the defined selection criteria using the PubMed database. Review Manager was used to calculate the pooled odds ratio (OR) or the mean difference (MD) with a 95% confidence interval (CI), using a random- or fixed-effect model for all analyses. In total, 112 studies were identified and examined; finally, only 36 studies met the inclusion criteria. In the 36 studies, compared to the clinicopathological behavior of patients with C-PTC, patients with FV-PTC had the following parameters: Similar mean age and similar prevalence of gender, tumor size ≥10 mm, multifocality, capsular invasion, vascular invasion, lymphocytic and/or Hashimoto's thyroiditis, and clinical stage; a larger mean tumor size and higher prevalence of age ≥45 years; and lower prevalence of extrathyroidal extensions, lymph node metastases, BRAF mutation and recurrence. The meta-analysis suggested that patients with FV-PTC have a more favorable clinicopathological behavior and improved prognosis compared to patients with C-PTC. Thus, patients with FV-PTC and C-PTC may be managed differently, and the two types of PTC should be clearly distinguished in future retrospective or prospective studies.

Experimental study of nasopharyngeal carcinoma radionuclide imaging and therapy using transferred human sodium/iodide symporter gene

Purpose

The aim of this study was to design a method of radionuclide for imaging and therapy of nasopharyngeal carcinoma (NPC) using the transferred human sodium/iodide symporter (hNIS) gene.

Methods

A stable NPC cell line expressing hNIS was established (CNE-2-hNIS). After ¹³¹I treatment, we detected proliferation and apoptosis of NPC cells, both in vitro and vivo. In vivo, the radioactivity of different organs of nude mice was counted and ^99mTc imaging using SPECT was performed. The apparent diffusion coefficient (ADC) value changes of tumor xenografts were observed by diffusion-weighted magnetic resonance imaging (DW-MRI) within 6–24 days of ¹³¹I treatment. The correlation of ADC changes with apoptosis and proliferation was investigated. Post-treatment expression levels of P53, Bax, Bcl-2, Caspase-3, and Survivin proteins were detected by western blotting.

Results

¹³¹I uptake was higher in CNE-2-hNIS than in CNE-2 cells. The proliferation and apoptosis rate decreased and increased respectively both in vitro and vivo in the experimental group after ¹³¹I treatment. The experimental group tumors accumulated ^99mTc in vivo, leading to a good visualization by SPECT. DW-MRI showed that ADC values increased in the experimental group 6 days after treatment, while ADC values were positively and negatively correlated with the apoptotic and Ki-67 proliferation indices, respectively. After treatment, CNE-2-hNIS cells up-regulated the expression of P53 and Survivin proteins and activated Caspase-3, and down-regulated the expression of Bcl-2 proteins.

Conclusions

The radionuclide imaging and therapy technique for NPC hNIS-transfected cell lines can provide a new therapy strategy for monitoring and treatment of NPC.

IQGAPs choreograph cellular signaling from the membrane to the nucleus

Since its discovery in 1994, recognized cellular functions for the scaffold protein IQGAP1 have expanded immensely. Over 100 unique IQGAP1-interacting proteins have been identified, implicating IQGAP1 as a critical integrator of cellular signaling pathways. Initial research established functions for IQGAP1 in cell-cell adhesion, cell migration, and cell signaling. Recent studies have revealed additional IQGAP1 binding partners, expanding the biological roles of IQGAP1. These include crosstalk between signaling cascades, regulation of nuclear function, and Wnt pathway potentiation. Investigation of the IQGAP2 and IQGAP3 homologs demonstrates unique functions, some of which differ from those of IQGAP1. Summarized here are recent observations that enhance our understanding of IQGAP proteins in the integration of diverse signaling pathways.

MicroRNA-mediated networks underlie immune response regulation in papillary thyroid carcinoma

Papillary thyroid carcinoma (PTC) is a common endocrine malignancy with low death rate but increased incidence and recurrence in recent years. MicroRNAs (miRNAs) are small non-coding RNAs with diverse regulatory capacities in eukaryotes and have been frequently implied in human cancer. Despite current progress, however, a panoramic overview concerning miRNA regulatory networks in PTC is still lacking. Here, we analyzed the expression datasets of PTC from The Cancer Genome Atlas (TCGA) Data Portal and demonstrate for the first time that immune responses are significantly enriched and under specific regulation in the direct miRNA--target network among distinctive PTC variants to different extents. Additionally, considering the unconventional properties of miRNAs, we explore the protein-coding competing endogenous RNA (ceRNA) and the modulatory networks in PTC and unexpectedly disclose concerted regulation of immune responses from these networks. Interestingly, miRNAs from these conventional and unconventional networks share general similarities and differences but tend to be disparate as regulatory activities increase, coordinately tuning the immune responses that in part account for PTC tumor biology. Together, our systematic results uncover the intensive regulation of immune responses underlain by miRNA-mediated networks in PTC, opening up new avenues in the management of thyroid cancer.

Targeted knockdown of IQGAP1 inhibits the progression of esophageal squamous cell carcinoma in vitro and in vivo

IQGAP1 is a scaffolding protein that can regulate several distinct signaling pathways. The accumulating evidence has demonstrated that IQGAP1 plays an important role in tumorigenesis and tumor progression. However, the function of IQGAP1 in esophageal squamous cell carcinoma (ESCC) has not been thoroughly investigated. In the present study, we showed that IQGAP1 was overexpressed in ESCC tumor tissues, and its overexpression was correlated with the invasion depth of ESCC. Importantly, by using RNA interference (RNAi) technology we successfully silenced IQGAP1 gene in two ESCC cell lines, EC9706 and KYSE150, and for the first time found that suppressing IQGAP1 expression not only obviously reduced the tumor cell growth, migration and invasion in vitro but also markedly inhibited the tumor growth, invasion, lymph node and lung metastasis in xenograft mice. Furthermore, Knockdown of IQGAP1 expression in ESCC cell lines led to a reversion of epithelial to mesenchymal transition (EMT) progress. These results suggest that IQGAP1 plays crucial roles in regulating ESCC occurrence and progression. IQGAP1 silencing may therefore develop into a promising novel anticancer therapy.

RSPO-LGR4 functions via IQGAP1 to potentiate Wnt signaling

R-spondins (RSPOs) and their receptor leucine-rich repeat-containing G-protein coupled receptor 4 (LGR4) play pleiotropic roles in normal and cancer development as well as the survival of adult stem cells through potentiation of Wnt signaling. Current evidence indicates that RSPO-LGR4 functions to elevate levels of Wnt receptors through direct inhibition of two membrane-bound E3 ligases (RNF43 and ZNRF3), which otherwise ubiquitinate Wnt receptors for degradation. Whether RSPO-LGR4 is coupled to intracellular signaling proteins to regulate Wnt pathways remains unknown. We identified the intracellular scaffold protein IQ motif containing GTPase-activating protein 1 (IQGAP1) as an LGR4-interacting protein that mediates RSPO-LGR4's interaction with the Wnt signalosome. IQGAP1 binds to and modulates the activities of a plethora of signaling molecules, including MAP kinases, Rho GTPases, and components of the Wnt signaling pathways. Interaction of LGR4 with IQGAP1 brings RSPO-LGR4 to the Wnt signaling complex through enhanced IQGAP1-DVL interaction following RSPO stimulation. In this configuration, RSPO-LGR4-IQGAP1 potentiates β-catenin-dependent signaling by promoting MEK1/2-medidated phosphorylation of LRP5/6 as well as β-catenin-independent signaling through regulation of actin dynamics. Overall, these findings reveal that RSPO-LGR4 not only induces the clearance of RNF43/ZNRF3 to increase Wnt receptor levels but also recruits IQGAP1 into the Wnt signaling complex, leading to potent and robust potentiation of both the canonical and noncanonical pathways of Wnt signaling.

Prognostic biomarkers in thyroid cancer

Thyroid carcinomas represent a challenging problem from the prognostic standpoint. Despite an overall good prognosis of the most frequent endocrine malignancy, 10-15 % of papillary thyroid carcinomas (PTCs) turn refractory to radioactive iodine therapy. The increased incidence of thyroid cancer has led to the search for solid prognostic biomarkers that predict the behaviour of these tumours. Clinical and histopathological prognostic factors remain the only safe elements to be used for diagnosis and prognosis of patients with thyroid tumours. Despite the huge amount of genetic information of thyroid tumours, very few new markers revealed diagnostic or prognostic value per se. BRAF mutation can have some value if associated to other clinico-pathological parameters, or in the particular setting of iodine refractory tumours. Others can prove interesting in the future as predictive biomarkers of therapeutic response, but more studies are needed to confirm these potential biomarkers.

IQGAP1 plays an important role in the cell proliferation of multiple myeloma via the MAP kinase (ERK) pathway

The present study was designed to explore the role of IQ motif-containing GTPase activating protein 1 (IQGAP1) in the cell proliferation of multiple myeloma (MM) via the MAP kinase (ERK) pathway. Reverse transcription‑polymerase chain reaction (RT-PCR) and western blot analysis were carried out to evaluate the expression of IQGAP1 in RPMI8226, U266 and KM3 cell lines and in primary MM cells from 4 MM patients. shRNA-expressing plasmids were used in RPMI8226 cells to knock down IQGAP1 and an MTT assay was used to examine the proliferative activity of the RPMI8226-shIQGAP1 (clone 1), RPMI8226-shRNA negative and untransfected RPMI8226 cells in subgroups stimulated with VEGF/IL-6 or without. Western blot analyses were then performed to examine the protein levels of p-ERK1/2, ERK1/2, AKT, p-AKT, STAT3, p-STAT3 in the RPMI8226-shIQGAP1 (clone 1), RPMI8226-shRNA negative and untransfected RPMI8226 cells. Co-immunoprecipitation was used to verify the interaction between the IQGAP1 scaffold and the MAP ERK kinase. We found that IQGAP1 was overexpressed in the human myeloma cell lines and in the patient MM cells. The proliferation rate in the RPMI8226 cells was decreased when IQGAP1 was knocked down with shRNA. IQGAP1 was found to affect RPMI8226 cell proliferation by regulation of the MAP kinase (ERK1/2) pathway; IQGAP1 scaffold-MAP kinase (ERK) interaction was noted in the human myeloma RPMI8226 cell lines. In conclusion, IQGAP1 plays an important role in the cell proliferation of MM via the MAP kinase (ERK) pathway.

Overexpression of IQGAP1 in human pancreatic cancer

BACKGROUND

Pancreatic cancer is a highly aggressive malignant tumor with the lowest survival rate. A better understanding of the molecular mechanisms which contribute to pancreatic cancer occurrence and progression will aid in the development of new approaches to the early diagnosis, prevention, and treatment of this deadly disease. The scaffold protein IQGAP1 shows elevated levels in a variety of cancer types. Currently, we investigated whether or not IQGAP1 is also overexpressed in pancreatic cancer.

METHODS

IQGAP1 expression was examined in pancreatic cancer and normal tissues adjacent to cancerous tissues (adjacent tissues) by Western blotting and real-time RT-PCR as well as in paraffin sections of tissue microarray by immunohistochemistry. The correlations between IQGAP1 expression and various clinicopathological characteristics were analyzed.

RESULTS

Western blotting and real-time RT-PCR revealed that the levels of IQGAP1 protein and mRNA expression in pancreatic cancer tissues were significantly increased compared with adjacent tissues. Immunohistochemistry analysis on tissue microarray showed that IQGAP1 protein expression was significantly higher in pancreatic cancer (80.0%, 48/60) compared with adjacent tissues (18.3%, 11/60) (P<0.001). Moreover, overexpression of IQGAP1 was shown to be associated with the grades of tumor differentiation (P<0.05).

CONCLUSION

The overexpression of IQGAP1 may play an important role in pancreatic cancer occurrence and progression, and IQGAP1 may serve as a novel molecular target for the diagnosis and treatment of pancreatic cancer.

High-throughput screen identifies disulfiram as a potential therapeutic for triple-negative breast cancer cells: interaction with IQ motif-containing factors

Triple-negative breast cancer (TNBC) represents an aggressive subtype, for which radiation and chemotherapy are the only options. Here we describe the identification of disulfiram, an FDA-approved drug used to treat alcoholism, as well as the related compound thiram, as the most potent growth inhibitors following high-throughput screens of 3185 compounds against multiple TNBC cell lines. The average IC₅₀ for disulfiram was ~300 nM. Drug affinity responsive target stability (DARTS) analysis identified IQ motif-containing factors IQGAP1 and MYH9 as direct binding targets of disulfiram. Indeed, knockdown of these factors reduced, though did not completely abolish, cell growth. Combination treatment with 4 different drugs commonly used to treat TNBC revealed that disulfiram synergizes most effectively with doxorubicin to inhibit cell growth of TNBC cells. Disulfiram and doxorubicin cooperated to induce cell death as well as cellular senescence, and targeted the ESA⁺/CD24^-/low/CD44⁺ cancer stem cell population. Our results suggest that disulfiram may be repurposed to treat TNBC in combination with doxorubicin.

A molecular rheostat at the interface of cancer and diabetes

Epidemiology studies revealed the connection between several types of cancer and type 2 diabetes (T2D) and suggested that T2D is both a symptom and a risk factor of pancreatic cancer. High level of circulating insulin (hyperinsulinemia) in obesity has been implicated in promoting aggressive types of cancers. Insulin resistance, a symptom of T2D, pressures pancreatic β-cells to increase insulin secretion, leading to hyperinsulinemia, which in turn leads to a gradual loss of functional β-cell mass, thus indicating a fine balance and interplay between β-cell function and mass. While the mechanisms of these connections are unclear, the mTORC1-Akt signaling pathway has been implicated in controlling β-cell function and mass, and in mediating the link of cancer and T2D. However, incomplete understating of how the pathway is regulated and how it integrates body metabolism has hindered its efficacy as a clinical target. The IQ motif containing GTPase activating protein 1 (IQGAP1)-Exocyst axis is a growth factor- and nutrient-sensor that couples cell growth and division. Here we discuss how IQGAP1-Exocyst, through differential interactions with Rho-type of small guanosine triphosphatases (GTPases), acts as a rheostat that modulates the mTORC1-Akt and MAPK signals, and integrates β-cell function and mass with insulin signaling, thus providing a molecular mechanism for cancer initiation in diabetes. Delineating this regulatory pathway may have the potential of contributing to optimizing the efficacy and selectivity of future therapies for cancer and diabetes.

IQGAP1 scaffold-kinase interaction blockade selectively targets RAS-MAP kinase-driven tumors

Upregulation of the ERK1 and ERK2 (ERK1/2) MAP kinase (MAPK) cascade occurs in >30% of cancers, often through mutational activation of receptor tyrosine kinases or other upstream genes, including KRAS and BRAF. Efforts to target endogenous MAPKs are challenged by the fact that these kinases are required for viability in mammals. Additionally, the effectiveness of new inhibitors of mutant BRAF has been diminished by acquired tumor resistance through selection for BRAF-independent mechanisms of ERK1/2 induction. Furthermore, recently identified ERK1/2-inducing mutations in MEK1 and MEK2 (MEK1/2) MAPK genes in melanoma confer resistance to emerging therapeutic MEK inhibitors, underscoring the challenges facing direct kinase inhibition in cancer. MAPK scaffolds, such as IQ motif-containing GTPase activating protein 1 (IQGAP1), assemble pathway kinases to affect signal transmission, and disrupting scaffold function therefore offers an orthogonal approach to MAPK cascade inhibition. Consistent with this, we found a requirement for IQGAP1 in RAS-driven tumorigenesis in mouse and human tissue. In addition, the ERK1/2-binding IQGAP1 WW domain peptide disrupted IQGAP1-ERK1/2 interactions, inhibited RAS- and RAF-driven tumorigenesis, bypassed acquired resistance to the BRAF inhibitor vemurafenib (PLX-4032) and acted as a systemically deliverable therapeutic to significantly increase the lifespan of tumor-bearing mice. Scaffold-kinase interaction blockade acts by a mechanism distinct from direct kinase inhibition and may be a strategy to target overactive oncogenic kinase cascades in cancer.

Molecular pathogenesis and mechanisms of thyroid cancer

Thyroid cancer is a common endocrine malignancy. There has been exciting progress in understanding its molecular pathogenesis in recent years, as best exemplified by the elucidation of the fundamental role of several major signalling pathways and related molecular derangements. Central to these mechanisms are the genetic and epigenetic alterations in these pathways, such as mutation, gene copy-number gain and aberrant gene methylation. Many of these molecular alterations represent novel diagnostic and prognostic molecular markers and therapeutic targets for thyroid cancer, which provide unprecedented opportunities for further research and clinical development of novel treatment strategies for this cancer.

BRAF mutation in papillary thyroid cancer and its value in tailoring initial treatment: a systematic review and meta-analysis

Clinicians have long sought to characterize biological markers of neoplasia as objective indicators of tumor presence, pathogenicity, and prognosis. Armed with data that correlate biomarker activity with disease presence and progression, clinicians can develop treatment strategies that address risks of disease recurrence or persistence and progression. The B-type Raf kinase (BRAF V600E) mutation in exon 15 of the BRAF gene has been noted to be a putative prognostic marker of the most prevalent form of thyroid cancer, papillary thyroid cancer (PTC)--a tumor type with high proclivity for recurrence or persistence. There has been a remarkable interest in determining the association of BRAF mutation with PTC recurrence or persistence. Using many new studies that have been published recently, we performed a meta-analysis to investigate correlations of BRAF mutation status with PTC prognosis, focusing on the recurrence or persistence of the disease after initial treatment. The study was based on published studies included in the PubMed and Embase databases addressing the BRAF mutation and the frequency of recurrence of PTC. We selected studies with data that enabled measurement of the risk ratio for recurrent disease. We also analyzed the factors that are classically known to be associated with recurrence. These factors included lymph node metastasis, extrathyroidal extension, distant metastasis, and American Joint Committee on Cancer (AJCC) stages III/IV. We used 14 articles that included an analysis of these factors as well as PTC recurrence data, with a total of 2470 patients from 9 different countries. The overall prevalence of the BRAF mutation was 45%. The risk ratios in BRAF mutation-positive patients were 1.93 (95% confidence interval [CI], 1.61-2.32; Z = 7.01; p < 0.00001) for PTC recurrence, 1.32 (95% CI, 1.20-1.45; Z = 5.73; p < 0.00001) for lymph node metastasis, 1.71 (95% CI, 1.50-1.94; Z = 8.09; p < 0.00001) for extrathyroidal extension, 0.95 (95% CI, 0.63-1.44; Z = 0.23; p = 0.82) for distant metastasis, and 1.70 (95% CI, 1.45-1.99; Z = 6.46; p < 0.00001) for advanced stage AJCC III/IV. Thus, in this meta-analysis, the BRAF mutation in PTC was significantly associated with PTC recurrence, lymph node metastasis, extrathyroidal extension, and advanced stage AJCC III/IV. Patients with PTC harboring mutated BRAF are likely to demonstrate factors that are associated with an increased risk for recurrence of the disease, offering new prospects for optimizing and tailoring initial treatment strategies to prevent recurrence.

Induction of sodium/iodide symporter (NIS) expression and radioiodine uptake in non-thyroid cancer cells

BACKGROUND

This study was designed to explore the therapeutic potential of suppressing MAP kinase and PI3K/Akt pathways and histone deacetylase (HDAC) to induce the expression of sodium/iodide symporter (NIS) and radioiodine uptake in non-thyroid cancer cells.

METHODS

We tested the effects of the MEK inhibitor RDEA119, the Akt inhibitor perifosine, and the HDAC inhibitor SAHA on NIS expression in thirteen human cancer cell lines derived from melanoma, hepatic carcinoma, gastric carcinoma, colon carcinoma, breast carcinoma, and brain cancers. We also examined radioiodine uptake and histone acetylation at the NIS promoter in selected cells.

RESULTS

Overall, the three inhibitors could induce NIS expression, to various extents, in melanoma and all the epithelial carcinoma-derived cells but not in brain cancer-derived cells. SAHA was most effective and its effect could be significantly enhanced by RDEA119 and perifosine. The expression of NIS, at both mRNA and protein levels, was most robust in the melanoma cell M14, hepatic carcinoma cell HepG2, and the gastric carcinoma cell MKN-7 cell. Radioiodine uptake was correspondingly induced, accompanied by robust increase in histone acetylation at the NIS promoter, in these cells when treated with the three inhibitors.

CONCLUSIONS

This is the first demonstration that simultaneously suppressing the MAP kinase and PI3K/Akt pathways and HDAC could induce robust NIS expression and radioiodine uptake in certain non-thyroid human cancer cells, providing novel therapeutic implications for adjunct radioiodine treatment of these cancers.

IQGAP1 and its binding proteins control diverse biological functions

IQGAP proteins have been identified in a wide spectrum of organisms, ranging from yeast to humans. The most extensively studied family member is the ubiquitously expressed scaffold protein IQGAP1, which participates in multiple essential aspects of mammalian biology. IQGAP1 mediates these effects by binding to and regulating the function of numerous interacting proteins. Over ninety proteins have been reported to associate with IQGAP1, either directly or as part of a larger complex. In this review, we summarise those IQGAP1 binding partners that have been identified in the last five years. The molecular mechanisms by which these interactions contribute to the functions of receptors and their signalling cascades, small GTPase function, cytoskeletal dynamics, neuronal regulation and intracellular trafficking are evaluated. The evidence that has accumulated recently validates the role of IQGAP1 as a scaffold protein and expands the repertoire of cellular activities in which it participates.

Managing anaplastic thyroid carcinoma

Anaplastic thyroid cancer is one of the most lethal malignancies, with dismal prognosis, resistance to multimodal treatments and a median survival of only 5-6 months. Advances in the discovery of genetic pathway aberrations involved in this aggressive disease have been made, and multiple novel therapies targeting these pathways are undergoing clinical trials. So far, there is no single effective treatment for this disease; however, multimodal therapies with a combination of surgery, radiation and chemotherapy hold some promise. We conducted a PubMed search using the words thyroid neoplasm, anaplastic thyroid carcinoma, anaplastic thyroid cancer and anaplastic thyroid neoplasm, revealing 1673 publications. We review the pathophysiology, current treatments and advances made in identifying the alterations in genetic pathways, as well as novel therapies targeting these pathways.