Gene Summary

Gene:TIAM1; T cell lymphoma invasion and metastasis 1
Aliases: TIAM-1
Summary:This gene encodes a RAC1-specific guanine nucleotide exchange factor (GEF). GEFs mediate the exchange of guanosine diphosphate (GDP) for guanosine triphosphate (GTP). The binding of GTP induces a conformational change in RAC1 that allows downstream effectors to bind and transduce a signal. This gene thus regulates RAC1 signaling pathways that affect cell shape, migration, adhesion, growth, survival, and polarity, as well as influencing actin cytoskeletal formation, endocytosis, and membrane trafficking. This gene thus plays an important role in cell invasion, metastasis, and carcinogenesis. In addition to RAC1, the encoded protein activates additional Rho-like GTPases such as CDC42, RAC2, RAC3 and RHOA. This gene encodes multiple protein isoforms that experience a diverse array of intramolecular, protein-protein, and phosphorylation interactions as well as phosphoinositide binding. Both the longer and shorter isoforms have C-terminal Dbl homology (DH) and pleckstrin homology (PH) domains while only the longer isoforms of this gene have the N-terminal myristoylation site and the downstream N-terminal PH domain, ras-binding domain (RBD), and PSD-95/DlgA/ZO-1 (PDZ) domain. [provided by RefSeq, Jul 2017]
Databases:OMIM, HGNC, Ensembl, GeneCard, Gene
Protein:T-lymphoma invasion and metastasis-inducing protein 1
Source:NCBIAccessed: 29 August, 2019


What does this gene/protein do?
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Pathways:What pathways are this gene/protein implicaed in?
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Cancer Overview

Research Indicators

Publications Per Year (1994-2019)
Graph generated 29 August 2019 using data from PubMed using criteria.

Literature Analysis

Mouse over the terms for more detail; many indicate links which you can click for dedicated pages about the topic.

Tag cloud generated 29 August, 2019 using data from PubMed, MeSH and CancerIndex

Specific Cancers (2)

Data table showing topics related to specific cancers and associated disorders. Scope includes mutations and abnormal protein expression.

Note: list is not exhaustive. Number of papers are based on searches of PubMed (click on topic title for arbitrary criteria used).

Latest Publications: TIAM1 (cancer-related)

Yu M, Xu Y, Pan L, et al.
miR-10b Downregulated by DNA Methylation Acts as a Tumor Suppressor in HPV-Positive Cervical Cancer via Targeting Tiam1.
Cell Physiol Biochem. 2018; 51(4):1763-1777 [PubMed] Related Publications
BACKGROUND/AIMS: microRNAs (miRNAs) are known to act as oncogenes or tumor suppressors in diverse cancers. Although miR-10b is an oncogene implicated in many tumors, its role in cervical cancer (CC) remains largely unclear. Here, we investigated the function and underlying mechanisms of miR-10b in human CC.
METHODS: Quantitative RT-PCR was used to measure miR-10b expression in CC and normal tissues, and its association with clinicopathologic features was analyzed. Methylation of CpG sites in the miR-10b promoter was analyzed by methylation sequencing. Cell proliferation, apoptosis, migration, and invasion assays were used to elucidate the biological effects of miR-10b and expression of the target gene was assayed with Western blot.
RESULTS: miR-10b was downregulated in CC tissues compared with normal tissues, and less miR-10b expression was associated with larger tumors, vascular invasion and HPV-type 16 positivity. miR-10b expression decreased in HeLa (HPV18-positive) and SiHa (HPV16-positive) cells compared with C-33A (HPV-negative), but increased after treatment with 5-Aza-CdR. Methylation ratio of site -797 in the miR-10b promoter in C-33A was lower than that in HeLa and SiHa. Further analysis indicates that site -797 is located within a transcription factor AP-2A (TFAP2A) binding element. Functionally, overexpression of miR-10b in HeLa and SiHa suppressed cell proliferation, migration and invasion, and induced apoptosis and miR-10b downregulation had opposite effects. Mechanistically, T-cell lymphoma invasion and metastasis 1 (Tiam1) was identified as a direct and functional target of miR-10b.
CONCLUSION: miR-10b acts as a tumor suppressor in CC by suppressing oncogenic Tiam1, and its expression may be downregulated through methylation of TFAP2A binding element by HPV.

He JH, Li YG, Han ZP, et al.
The CircRNA-ACAP2/Hsa-miR-21-5p/ Tiam1 Regulatory Feedback Circuit Affects the Proliferation, Migration, and Invasion of Colon Cancer SW480 Cells.
Cell Physiol Biochem. 2018; 49(4):1539-1550 [PubMed] Related Publications
BACKGROUND/AIMS: Circular RNAs (circRNAs), a type of RNA that is widely expressed in human cells, have essential roles in the development and progression of cancer. CircRNAs contain microRNA (miRNA) binding sites and can function as miRNA sponges to regulate gene expression by removing the inhibitory effect of an miRNA on its target gene.
METHODS: We used the bioinformatics software TargetScan and miRanda to predict circRNA-miRNA and miRNAi-Mrna interactions. Rate of inhibiting of proliferation was measured using a WST-8 cell proliferation assay. Clone formation ability was assessed with a clone formation inhibition test. Cell invasion and migration capacity was evaluated by performing a Transwell assay. Relative gene expression was assessed using quantitative real-time polymerase chain reaction and relative protein expression levels were determined with western blotting. circRNA and miRNA interaction was confirmed by dual-luciferase reporter and RNA-pull down assays.
RESULTS: In the present study, the miRNA hsa-miR-21-5p was a target of circRNA-ACAP2, and T lymphoma invasion and metastasis protein 1 (Tiam1) was identified as a target gene of hsa-miR-21-5p. CircRNA-ACAP2 and Tiam1 were shown to be highly expressed in colon cancer tissue and colon cancer SW480 cells, but miR-21-5p was expressed at a low level. SW480 cell proliferation was suppressed when the expression of circRNA-ACAP2 and Tiam1 was decreased and the expression of miR-21-5p was increased in vivo and in vitro. SW480 cell migration and invasion were also inhibited under the same circumstance. The circRNA-ACAP2 interaction regulated the expression of miR-21-5p, and miR-21-5p regulated the expression of Tiam1. Down-regulation of circRNA-ACAP2 promoted miR-21-5p expression, which further suppressed the transcription and translation of Tiam1.
CONCLUSION: The present study shows that the circRNA-ACAP2/hsa-miR-21-5p/Tiam1 regulatory feedback circuit could affect the proliferation, migration, and invasion of colon cancer SW480 cells. This was probably due to the fact that circRNA-ACAP2 could act as a miRNA sponge to regulate Tiam1 expression by removing the inhibitory effect of miR-21-5p on Tiam1 expression. The results from this study have revealed new insights into the pathogenicity of colon cancer and may provide novel therapeutic targets for the treatment of colon cancer.

Zhang X, Liu L, Deng X, et al.
MicroRNA 483-3p targets Pard3 to potentiate TGF-β1-induced cell migration, invasion, and epithelial-mesenchymal transition in anaplastic thyroid cancer cells.
Oncogene. 2019; 38(5):699-715 [PubMed] Related Publications
Anaplastic thyroid cancer (ATC) is associated with poor prognosis and is often untreatable. MicroRNA 483-3p (miR-483) and partitioning-defective 3 (Pard3), a member of the Pard family, have functions and regulatory mechanisms in ATC. The abnormal regulation of miR-483 may play an important role in tumorigenesis, and Par3 is known to regulate cell polarity, cell migration, and cell division. Tumor proliferation promoted by the regulation of miRNA expression can be regulated in thyroid cancer by upregulating transforming growth factor-β1 (TGF-β1), which is thought to interact with Pard3. When compared with adjacent non-tumor tissues, we found that miR-483 was upregulated and Pard3 was downregulated in 80 thyroid tumor samples. Disease-free survival was decreased when expression of miR-483 was upregulated and Pard3 expression was downregulated. Cell growth, migration, and invasion were induced by overexpression of miR-483. However, knockdown of miR-483 resulted in a loss of cell invasion and viability, both in vitro and in vivo. The expression of Pard3 was increased by the inhibition of miR-483, but TGF-β1-induced cell migration and invasion were decreased by miR-483 inhibition. A dual-luciferase reporter assay determined that Pard3 expression was downregulated when targeted with miR-483. The epithelial-mesenchymal transition (EMT), as well as Tiam1-Rac signaling, was induced by TGF-β1, which was decreased by the overexpression of Pard3. Pard3 decreased the inhibition of EMT and Tiam-Rac1 signaling, which resulted from transfection of ATC cells with miR-483. Overall, the results showed that downregulation of Pard3 resulted in increased cell invasion and EMT in ATC, which was promoted by treatment with miR-483. These findings suggest novel therapeutic targets and treatment strategies for this disease.

Kim MK, Moon YA, Song CK, et al.
Tumor-suppressing miR-141 gene complex-loaded tissue-adhesive glue for the locoregional treatment of hepatocellular carcinoma.
Theranostics. 2018; 8(14):3891-3901 [PubMed] Free Access to Full Article Related Publications
microRNAs (miRNAs) regulate gene expression post-transcriptionally and have been extensively tested as therapeutic molecules against several human diseases.

Zhang Y, Huang J, Li Q, et al.
Histone methyltransferase SETDB1 promotes cells proliferation and migration by interacting withTiam1 in hepatocellular carcinoma.
BMC Cancer. 2018; 18(1):539 [PubMed] Free Access to Full Article Related Publications
BACKGROUND: SETDB1 is a histone H3K9 methyltransferase, which plays a significant role in the occurrence and progression of tumors. Previous studies have confirmed that T-lymphom invasion and metastasis gene (Tiam1) is a protein associated with the metastasis of hepatocellular carcinoma (HCC); however, we have not yet been successful in elucidating the specific mechanism of HCC.
METHODS: Yeast two-hybrid test was conducted to screen proteins that interacted with Tiam1 gene. Glutathione-S-transferase (GST) pull-down and crosslinking-immunoprecipitation (CLIP) assays were performed to determine whether SETDB1 can interact with Tiam1 gene. A series of related experiments were performed to explore role of SETDB1 on cell proliferation, migration, and invasion in HCC. Recovery experiment was performed to investigate the effect of Tiam1 knockdown on cell proliferation and migration, which was caused by SETDB1 overexpression in HCC cells. The expression of SETDB1 was frequently upregulated in HCC tissues and positively correlated with Tiam1.
RESULTS: GST pull-down and CLIP assays were performed to elucidate the interaction between SETDB1 and Tiam1. Cell proliferation, migration, and epithelial mesenchymal transformation (EMT) in HCC cells was promoted with the overexpression of SETDB1. Following the knockdown of Tiam1 gene, the effect of SETDB1 on cell proliferation and migration was reversed in HCC cells. The expression of SETDB1 was frequently up-regulated in HCC tissues, and it was positively correlated with Tiam1 gene.
CONCLUSIONS: Ours is the first study to prove that SETDB1 promotes the proliferation and migration of cells by forming SETDB1-Tiam1 compounds. We found that SETDB1-Tiam1 compounds were involved in a novel pathway, which regulated epigenetic modification of gene expression in HCC samples.

Liu L, Wu B, Cai H, et al.
Tiam1 promotes thyroid carcinoma metastasis by modulating EMT via Wnt/β-catenin signaling.
Exp Cell Res. 2018; 362(2):532-540 [PubMed] Related Publications
Aberrant expression of the guanine nucleotide exchange factor Tiam1 is implicated in the invasive phenotype of many cancers. However, its involvement in thyroid carcinoma and downstream molecular events remains largely undefined. Here, we examined the effects of Tiam1 on the invasiveness and metastasis of thyroid carcinoma in vitro and in vivo and explored the underlying mechanisms by investigating the regulation of Tiam1 expression and the downstream pathways affected. Our results showed that Tiam1 knockdown inhibited the migratory and invasive capacity of thyroid cancer cells, suppressed epithelial-mesenchymal transition (EMT), and inhibited Wnt/β-catenin signaling in vitro. Moreover, Tiam1 knockdown suppressed liver metastasis development in vivo. The effects of Tiam1 on metastasis and EMT mediated by the Wnt/β-catenin pathway were reversed by Rac1 silencing, suggesting that the prometastatic effect of Tiam1 is mediated by the activation of Rac1. These results indicate that Tiam1 may be a prognostic factor and potential therapeutic target for the treatment of thyroid cancers.

He PY, Yip WK, Chai BL, et al.
Inhibition of cell migration and invasion by miR‑29a‑3p in a colorectal cancer cell line through suppression of CDC42BPA mRNA expression.
Oncol Rep. 2017; 38(6):3554-3566 [PubMed] Related Publications
The objective of this study was to determine the effect of miR‑29a‑3p inhibitor on the migration and invasion of colorectal cancer cell lines (CRC) and the underlying molecular mechanisms. miR‑29a‑3p was detected using reverse transcription-quantitative polymerase chain reaction (RT‑qPCR) in the CRC cell lines HCT11, CaCo2, HT29, SW480 and SW620. An invasive subpopulation designated SW480‑7 was derived from the parental cell line, detected by Transwell and Transwell Matrigel assays. Cytoskeleton Regulators RT2 profiler PCR array and western blot analysis were utilized to identify the alterations in expression of downstream mRNAs. siRNA against CDC42BPA was transfected into SW480‑7 and effects on cell migration and invasion were investigated. Data obtained showed that miR‑29a‑3p was detected in these five CRC cell lines. miR‑29a‑3p inhibitor had no effect on viability but stimulated cell migration and invasion of SW480‑7 cells. In contrast, miR‑29a‑3p mimic suppressed cell migration and invasion. TargetScan miRBD and DIANA were employed to identify the potential direct target genes of miR‑29a‑3p in the Cytoskeleton Regulators RT2-Profiler PCR array. Cytoskeleton Regulators RT2-Profiler PCR array data showed that 3 out of the 5 predicted targets genes, CDC42BPA (2.33-fold), BAIAP2 (1.79-fold) and TIAM1 (1.77-fold), in the array were upregulated by miR‑29a‑3p. A significant increase in expression IQGAP2, PHLDB2, SSH1 mRNAs and downregulation of PAK1 mRNA was also detected with miR‑29a‑3p inhibition. Increase in CDC42BPA, SSH1 and IQGAP2 mRNA expression correlated with increased protein level in miR‑29a‑3p transfected SW-480-7 cells. Silencing of CDC42BPA (an enhancer of cell motility) partially abolished miR‑29a‑3p inhibitor-induced stimulation of cell migration and invasion. miR‑29a‑3p expression in stage II and III CRC is relatively lower than that of stage I CRC. However, the data need to be interpreted with caution due to the small sample size. In conclusion, inhibition of miR‑29a‑3p stimulates SW480‑7 cell migration and invasion and downstream expression IQGAP2, PHLDB2, SSH1 mRNAs are upregulated whilst PAK1 mRNA is downregulated. Silencing of CDC42BPA expression partially reduces miR29a‑3p inhibitor-induced migration and invasion of SW480‑7 cells.

Song B, Wang LF, Fan XH, et al.
Expression of T-lymphoma invasion and metastasis factor on the occurrence of oral squamous cell carcinoma.
J Biol Regul Homeost Agents. 2017 Apr-Jun; 31(2):289-295 [PubMed] Related Publications
In recent years, many studies have found that tumor metastasis-related gene T-lymphoma invasion and metastasis-inducing factor 1 (TIAM1) had abnormal high expression in a variety of tumor cells; however, there are few studies regarding its expression in oral squamous cell carcinoma (OSCC). This study aimed to observe the expression of TIAM1 in OSCC and investigated its clinical significance. The expression of TIAM1 in tissues from 120 cases of OSCC and oral mucosa from 40 normal cases was detected by immunohistochemistry, and the relationship between the expression of TIAM1 and the clinicopathological parameters of OSCC was analyzed. The positive expression rate of TIAM1 in the OSCC tissues was significantly higher than that in the normal oral mucosa (92.5% vs 0%). With the decrease of histological differentiation of OSCC, the increase of tumor node metastasis (TNM) stage and the occurrence of lymph node metastasis, the TIAM1 staining positive rate was gradually increased, and the difference was statistically significant (P less than 0.05). However, the expression of TIAM1 in the OSCC tissues was in no correlation with the gender and age of the patients. The expression of TIAM1 is closely related to the occurrence, development and metastasis of OSCC, and it can be used as a new marker for reflecting its biological behaviors.

Morrison Joly M, Williams MM, Hicks DJ, et al.
Two distinct mTORC2-dependent pathways converge on Rac1 to drive breast cancer metastasis.
Breast Cancer Res. 2017; 19(1):74 [PubMed] Free Access to Full Article Related Publications
BACKGROUND: The importance of the mTOR complex 2 (mTORC2) signaling complex in tumor progression is becoming increasingly recognized. HER2-amplified breast cancers use Rictor/mTORC2 signaling to drive tumor formation, tumor cell survival and resistance to human epidermal growth factor receptor 2 (HER2)-targeted therapy. Cell motility, a key step in the metastatic process, can be activated by mTORC2 in luminal and triple negative breast cancer cell lines, but its role in promoting metastases from HER2-amplified breast cancers is not yet clear.
METHODS: Because Rictor is an obligate cofactor of mTORC2, we genetically engineered Rictor ablation or overexpression in mouse and human HER2-amplified breast cancer models for modulation of mTORC2 activity. Signaling through mTORC2-dependent pathways was also manipulated using pharmacological inhibitors of mTOR, Akt, and Rac. Signaling was assessed by western analysis and biochemical pull-down assays specific for Rac-GTP and for active Rac guanine nucleotide exchange factors (GEFs). Metastases were assessed from spontaneous tumors and from intravenously delivered tumor cells. Motility and invasion of cells was assessed using Matrigel-coated transwell assays.
RESULTS: We found that Rictor ablation potently impaired, while Rictor overexpression increased, metastasis in spontaneous and intravenously seeded models of HER2-overexpressing breast cancers. Additionally, migration and invasion of HER2-amplified human breast cancer cells was diminished in the absence of Rictor, or upon pharmacological mTOR kinase inhibition. Active Rac1 was required for Rictor-dependent invasion and motility, which rescued invasion/motility in Rictor depleted cells. Rictor/mTORC2-dependent dampening of the endogenous Rac1 inhibitor RhoGDI2, a factor that correlated directly with increased overall survival in HER2-amplified breast cancer patients, promoted Rac1 activity and tumor cell invasion/migration. The mTORC2 substrate Akt did not affect RhoGDI2 dampening, but partially increased Rac1 activity through the Rac-GEF Tiam1, thus partially rescuing cell invasion/motility. The mTORC2 effector protein kinase C (PKC)α did rescue Rictor-mediated RhoGDI2 downregulation, partially rescuing Rac-guanosine triphosphate (GTP) and migration/motility.
CONCLUSION: These findings suggest that mTORC2 uses two coordinated pathways to activate cell invasion/motility, both of which converge on Rac1. Akt signaling activates Rac1 through the Rac-GEF Tiam1, while PKC signaling dampens expression of the endogenous Rac1 inhibitor, RhoGDI2.

Sanmartín E, Yáñez Y, Fornés-Ferrer V, et al.
TIAM1 variants improve clinical outcome in neuroblastoma.
Oncotarget. 2017; 8(28):45286-45297 [PubMed] Free Access to Full Article Related Publications
Identification of tumor driver mutations is crucial for improving clinical outcome using a personalized approach to the treatment of cancer. Neuroblastoma is a tumor of the peripheral sympathetic nervous system for which only a few driver alterations have been described including MYCN amplification and ALK mutations. We assessed 106 primary neuroblastoma tumors by next generation sequencing using a customized amplicon-based gene panel. Our results reveal that genetic variants in TIAM1 gene associate with better clinical outcome, suggesting a role for these TIAM1 variants in preventing progression of this disease. The detected variants are located within the different domains of TIAM1 that signal to the upstream regulator RAS and downstream effector molecules MYC and RAC, which are all implicated in neuroblastoma etiology and progression. Clinical outcome was improved in tumors where a TIAM1 variant was present concomitantly with either ALK mutation or MYCN amplification. Given the function of these signaling molecules in cell survival, proliferation, differentiation and neurite outgrowth, our data suggest that the TIAM1-mediated network is essential to neuroblastoma and thus, inhibiting TIAM1 reflects a rational strategy for improving therapy efficacy in neuroblastoma.

Diamantopoulou Z, White G, Fadlullah MZH, et al.
TIAM1 Antagonizes TAZ/YAP Both in the Destruction Complex in the Cytoplasm and in the Nucleus to Inhibit Invasion of Intestinal Epithelial Cells.
Cancer Cell. 2017; 31(5):621-634.e6 [PubMed] Free Access to Full Article Related Publications
Aberrant WNT signaling drives colorectal cancer (CRC). Here, we identify TIAM1 as a critical antagonist of CRC progression through inhibiting TAZ and YAP, effectors of WNT signaling. We demonstrate that TIAM1 shuttles between the cytoplasm and nucleus antagonizing TAZ/YAP by distinct mechanisms in the two compartments. In the cytoplasm, TIAM1 localizes to the destruction complex and promotes TAZ degradation by enhancing its interaction with βTrCP. Nuclear TIAM1 suppresses TAZ/YAP interaction with TEADs, inhibiting expression of TAZ/YAP target genes implicated in epithelial-mesenchymal transition, cell migration, and invasion, and consequently suppresses CRC cell migration and invasion. Importantly, high nuclear TIAM1 in clinical specimens associates with increased CRC patient survival. Together, our findings suggest that in CRC TIAM1 suppresses tumor progression by regulating YAP/TAZ activity.

Li B, Li B, Sun H, Zhang H
The predicted target gene validation, function, and prognosis studies of miRNA-22 in colorectal cancer tissue.
Tumour Biol. 2017; 39(3):1010428317692257 [PubMed] Related Publications
MicroRNAs are known as small, non-coding, and single-stranded RNAs which can regulate cell proliferation, differentiation, and apoptosis and involve in the development of tumors. In this study, colorectal cancer tissue morphological change in different prognosis in patients was observed by hematoxylin and eosin staining. Thereafter, differentially expressed miR-22 and TIAM1 gene were detected using quantitative polymerase chain reaction and western blot in different colorectal cancer tissues. Meanwhile, luciferase reporter gene system was used to verify the relationship between miR-22 and TIAM1. Eventually, the survival curve was plotted according to follow-up records of patients with colorectal cancer and the expression levels of miR-22 and TIAM1 in different tumor tissues. The hematoxylin and eosin results showed the poor pathological features in the 1-year survival group. The expression level of miR-22 was upregulated and TIAM1 was inhibited, correlating with the extension of patients' survival time. Our results indicated that miR-22 and TIAM1 might play a regulatory role in the occurrence and development of colorectal cancer which were consistent with the survival curve analysis results. Furthermore, the luciferase in miR-22 co-transfected with pmiR-RB-REPORT- TIAM1 group was significantly lower than pmiR-RB-REPORT- TIAM1-mut and Si groups. Collectively, these data suggest that miR-22 may suppress the expression of its target gene TIAM1. The low miR-22 level or the high TIAM1 level will indicate the poor prognosis in colorectal cancer patients.

Zhou H, Kann MG, Mallory EK, et al.
Recruitment of Tiam1 to Semaphorin 4D Activates Rac and Enhances Proliferation, Invasion, and Metastasis in Oral Squamous Cell Carcinoma.
Neoplasia. 2017; 19(2):65-74 [PubMed] Free Access to Full Article Related Publications
The semaphorins and the plexins are a family of large, cysteine-rich proteins originally identified as regulators of axon growth and lymphocyte activation that are now known to provide motility and positional information for a number of cell and tissue types. For example, our group and others have shown that some malignancies over express Semaphorin 4D (S4D), which acts through its receptor Plexin-B1 (PB1) on endothelial cells to attract blood vessels from the surrounding stroma for the purpose of supporting tumor growth. While plexins are the known functional receptors for the semaphorins, there is evidence that transmembrane semaphorins may transmit a signal themselves through their short cytoplasmic tail, a phenomenon known as 'reverse signaling.' We used computational methods based upon correlated evolution of sequences of interacting proteins, mutational analysis and in vitro and in vivo measurements of tumor aggressiveness to show that when bound to PB1, transmembrane S4D associates with the Rac GTPase exchange factor T lymphoma invasion and metastasis (Tiam) 1, which activates Rac and promotes proliferation, invasion and metastasis in oral squamous cell carcinoma (OSCC) cells. These results suggest that not only can S4D production by tumor cells affect the microenvironment, but engagement of this semaphorin at the cell surface activates a reverse signaling mechanism that influences tumor aggressiveness in OSCC.

Li A, Li J, Lin J, et al.
COL11A1 is overexpressed in gastric cancer tissues and regulates proliferation, migration and invasion of HGC-27 gastric cancer cells in vitro.
Oncol Rep. 2017; 37(1):333-340 [PubMed] Related Publications
The role of COL11A1 in carcinogenesis is increasingly recognized. However, the biological role and potential mechanisms of COL11A1 in gastric cancer have not been elucidated. In the present study, the COL11A1 mRNA expression in 57 patients with gastric cancer was measured by reverse transcription quantitative PCR (RT-qPCR), and the biological effects of COL11A1 suppression were determined using MTS, monolayer colony formation, flow cytometry and Transwell assays. In addition, the potential molecular mechanisms of COL11A1 in gastric cancer were analyzed by western blotting and cDNA microarray analysis. Compared with matched adjacent non-tumor tissue, COL11A1 mRNA was significantly overexpressed in tumor tissue and was positively related to age, tumor invasion depth, tumor size and lymph node positivity. Moreover, in vitro experiments demonstrated that COL11A1 suppression by short hairpin RNA (shRNA) significantly inhibited the proliferation, migration and invasion of HGC-27 cells and that COL11A1 suppression promoted cell apoptosis, induced G1-phase cell cycle arrest and led to a significant downregulation of cyclin D1 and upregulation of p21 and cleaved caspase-3. In addition, the cDNA microarray analysis of HGC-27 cells with and without COL11A1 suppression indicated that COL11A1 may regulate multiple genes responsible for cell growth and/or invasion, including downregulation of CDK6, TIAM1, ITGB8 and WNT5A and upregulation of RGS2 and NEFL following suppression of COL11A1 expression in HGC-27 cells, validated with RT-qPCR assays. Taken together, our findings demonstrate that COL11A1 might be an oncogene in GC and is a promising therapeutic target in cancer treatment.

De P, Carlson JH, Jepperson T, et al.
RAC1 GTP-ase signals Wnt-beta-catenin pathway mediated integrin-directed metastasis-associated tumor cell phenotypes in triple negative breast cancers.
Oncotarget. 2017; 8(2):3072-3103 [PubMed] Free Access to Full Article Related Publications
The acquisition of integrin-directed metastasis-associated (ID-MA) phenotypes by Triple-Negative Breast Cancer (TNBC) cells is caused by an upregulation of the Wnt-beta-catenin pathway (WP). We reported that WP is one of the salient genetic features of TNBC. RAC-GTPases, small G-proteins which transduce signals from cell surface proteins including integrins, have been implicated in tumorigenesis and metastasis by their role in essential cellular functions like motility. The collective percentage of alteration(s) in RAC1 in ER+ve BC was lower as compared to ER-ve BC (35% vs 57%) (brca/tcga/pub2015). High expression of RAC1 was associated with poor outcome for RFS with HR=1.48 [CI: 1.15-1.9] p=0.0019 in the Hungarian ER-veBC cohort. Here we examined how WP signals are transduced via RAC1 in the context of ID-MA phenotypes in TNBC. Using pharmacological agents (sulindac sulfide), genetic tools (beta-catenin siRNA), WP modulators (Wnt-C59, XAV939), RAC1 inhibitors (NSC23766, W56) and WP stimulations (LWnt3ACM, Wnt3A recombinant) in a panel of 6-7 TNBC cell lines, we studied fibronectin-directed (1) migration, (2) matrigel invasion, (3) RAC1 and Cdc42 activation, (4) actin dynamics (confocal microscopy) and (5) podia-parameters. An attenuation of WP, which (a) decreased cellular levels of beta-catenin, as well as its nuclear active-form, (b) decreased fibronectin-induced migration, (c) decreased invasion, (d) altered actin dynamics and (e) decreased podia-parameters was successful in blocking fibronectin-mediated RAC1/Cdc42 activity. Both Wnt-antagonists and RAC1 inhibitors blocked fibronectin-induced RAC1 activation and inhibited the fibronectin-induced ID-MA phenotypes following specific WP stimulation by LWnt3ACM as well as Wnt3A recombinant protein. To test a direct involvement of RAC1-activation in WP-mediated ID-MA phenotypes, we stimulated brain-metastasis specific MDA-MB231BR cells with LWnt3ACM. LWnt3ACM-stimulated fibronectin-directed migration was blocked by RAC1 inhibition in MDA-MB231BR cells. In the light of our previous report that WP upregulation causes ID-MA phenotypes in TNBC tumor cells, here we provide the first mechanism based evidence to demonstrate that WP upregulation signals ID-MA tumor cell phenotypes in a RAC1-GTPase dependent manner involving exchange-factors like TIAM1 and VAV2. Our study demonstrates for the first time that beta-catenin-RAC1 cascade signals integrin-directed metastasis-associated tumor cell phenotypes in TNBC.

Lin L, You J, Qian Y, et al.
The prognostic value of T Lymphoma Invasion and Metastasis 1 (TIAM1) expression in oral squamous cell carcinoma.
J Biochem Mol Toxicol. 2017; 31(4) [PubMed] Related Publications
Oral squamous cell carcinoma (OSCC) is the most common malignant neoplasm with high rate of lymph node metastasis and recurrence. The aim of this study is to evaluate the expression profile of T Lymphoma Invasion and Metastasis 1 (TIAM1) in OSCC and its correlation with clinical outcomes including lymph node metastasis and recurrence. Detection of TIAM1 expression in tumor samples from 56 OSCC patients and oral mucosa samples from 20 healthy people was performed by immunohistochemistry. Then immunostaining score of each patient was calculated. The results revealed that TIAM1 was aberrantly expressed in the OSCC group compared with the normal group. Furthermore, high expression of TIAM1 was significantly correlated with lymph node metastasis and the timing of recurrence. Assessment of TIAM1 expression might represent a valid tool in clinical practice for prediction of metastasis, recurrence, and prognosis of OSCC.

Li F, Fang Z, Zhang J, et al.
Identification of TRA2B-DNAH5 fusion as a novel oncogenic driver in human lung squamous cell carcinoma.
Cell Res. 2016; 26(10):1149-1164 [PubMed] Free Access to Full Article Related Publications
Lung squamous cell carcinoma (SCC) is one of the major subtypes of lung cancer. Our current knowledge of oncogenic drivers in this specific subtype of lung cancer is largely limited compared with lung adenocarcinoma (ADC). Through exon array analyses, molecular analyses and functional studies, we here identify the TRA2B-DNAH5 fusion as a novel oncogenic driver in lung SCC. We found that this gene fusion occurs exclusively in lung SCC (3.1%, 5/163), but not in lung ADC (0/119). Through mechanistic studies, we further revealed that this TRA2B-DNAH5 fusion promotes lung SCC malignant progression through regulating a SIRT6-ERK1/2-MMP1 signaling axis. We show that inhibition of ERK1/2 activation using selumetinib efficiently inhibits the growth of lung SCC with TRA2B-DNAH5 fusion expression. These findings improve our current knowledge of oncogenic drivers in lung SCC and provide a potential therapeutic strategy for lung SCC patients with TRA2B-DNAH5 fusion.

Song T, Tian X, Kai F, et al.
Loss of Par3 promotes lung adenocarcinoma metastasis through 14-3-3ζ protein.
Oncotarget. 2016; 7(39):64260-64273 [PubMed] Free Access to Full Article Related Publications
Partitioning defective protein 3 (Par3) can activate the Tiam1/Rac pathway to inhibit invasion and metastasis in many cancers; however, the role of Par3 in lung adenocarcinoma remains unknown. Here we show that Par3 is downregulated in lung adenocarcinoma tissues and is associated with higher rates of lymph node metastasis and recurrence. Our functional study demonstrated that knock-down of Par3 promoted lung adenocarcinoma cell growth, cell migration, tumor formation, and metastasis, all of which were effectively inhibited when 14-3-3ζ was silenced. We found that Par3 binded with 14-3-3ζ protein and also showed that Par3 abrogated the binding of 14-3-3ζ to Tiam1, which was responsible for Rac1 activation. Knock-down of 14-3-3ζ inhibited Tiam1/Rac-GTP activation and blocked the invasive behavior of cells lacking Par3. These data suggest that loss of Par3 promotes metastatic behavior in lung adenocarcinoma cells through 14-3-3ζ protein.

Li Z, Liu Q, Piao J, et al.
Clinicopathological implications of Tiam1 overexpression in invasive ductal carcinoma of the breast.
BMC Cancer. 2016; 16(1):681 [PubMed] Free Access to Full Article Related Publications
BACKGROUND: T-lymphoma invasion and metastasis-inducing protein 1 (Tiam1) has been implicated in tumor occurrence and progression. Recent studies have shown that high expression levels of Tiam1 protein appear to be associated with the progression of numerous human tumors. This study attempted to explore the role of Tiam1 protein in tumor progression and the prognostic evaluation of breast cancer.
METHODS: The localization of the Tiam1 protein was determined in the MDA-MB-231 breast cancer cell line using immunofluorescence (IF) staining. In addition, a total of 283 breast tissue samples, including 153 breast cancer tissues, 67 ductal carcinoma in situ (DCIS) and 63 adjacent non-tumor breast tissues, were analyzed by immunohistochemical (IHC) staining of the Tiam1 protein. The correlation between Tiam1 expression and clinicopathological characteristics was evaluated by Chi-square test and Fisher's exact tests. Disease-free survival (DFS) and 10-year overall survival (OS) rates were calculated by the Kaplan-Meier method. Additionally, univariate and multivariate analyses were performed by the Cox proportional hazards regression models.
RESULTS: Tiam1 protein showed a mainly cytoplasmic staining pattern in breast cancer cells; however, nuclear staining was also observed. Tiam1 protein expression was significantly higher in breast cancers (42.5 %, 65/153) and DCIS (40.3 %, 27/67) than in adjacent non-tumor tissues (12.7 %, 8/63). In addition, Tiam1 associated with tumor stage and Ki-67 expression, but negatively correlated with receptor tyrosine-protein kinase erbB-2 (Her2) expression. Moreover, survival analyses showed that DFS and 10-year OS rates were significantly lower in breast cancer patients with high Tiam1 expression than those with low Tiam1 expression. Univariate analysis suggested that molecular types, clinical stage, Her2 expression levels and Tiam1 expression levels were also significantly associated with DFS and 10-year OS rates of breast cancer patients. Furthermore, multivariate analysis suggested that Tiam1 expression is a significant independent prognostic factor along with tumor stage in patients with breast cancer.
CONCLUSIONS: Tiam1 expression is frequently up-regulated in breast cancer. Tiam1 expression correlated with clinicopathological parameters, suggesting that it may be a useful prognostic biomarker and potential therapeutic target for patients with breast cancer.

Bracalente C, Ibañez IL, Berenstein A, et al.
Reprogramming human A375 amelanotic melanoma cells by catalase overexpression: Upregulation of antioxidant genes correlates with regression of melanoma malignancy and with malignant progression when downregulated.
Oncotarget. 2016; 7(27):41154-41171 [PubMed] Free Access to Full Article Related Publications
Reactive oxygen species (ROS) are implicated in tumor transformation. The antioxidant system (AOS) protects cells from ROS damage. However, it is also hijacked by cancers cells to proliferate within the tumor. Thus, identifying proteins altered by redox imbalance in cancer cells is an attractive prognostic and therapeutic tool. Gene expression microarrays in A375 melanoma cells with different ROS levels after overexpressing catalase were performed. Dissimilar phenotypes by differential compensation to hydrogen peroxide scavenging were generated. The melanotic A375-A7 (A7) upregulated TYRP1, CNTN1 and UCHL1 promoting melanogenesis. The metastatic A375-G10 (G10) downregulated MTSS1 and TIAM1, proteins absent in metastasis. Moreover, differential coexpression of AOS genes (EPHX2, GSTM3, MGST1, MSRA, TXNRD3, MGST3 and GSR) was found in A7 and G10. Their increase in A7 improved its AOS ability and therefore, oxidative stress response, resembling less aggressive tumor cells. Meanwhile, their decrease in G10 revealed a disruption in the AOS and therefore, enhanced its metastatic capacity.These gene signatures, not only bring new insights into the physiopathology of melanoma, but also could be relevant in clinical prognostic to classify between non aggressive and metastatic melanomas.

Hemminki K, Chen B, Kumar A, et al.
Germline genetics of cancer of unknown primary (CUP) and its specific subtypes.
Oncotarget. 2016; 7(16):22140-9 [PubMed] Free Access to Full Article Related Publications
Cancer of unknown primary site (CUP) is a fatal cancer diagnosed through metastases at various organs. Little is known about germline genetics of CUP which appears worth of a search in view of reported familial associations in CUP. In the present study, samples from CUP patients were identified from 2 Swedish biobanks and a German clinical trial, totaling 578 CUP patients and 7628 regionally matched controls. Diagnostic data specified the organ where metastases were diagnosed. We carried out a genome-wide association study on CUP cases and controls. In the whole sample set, 6 loci reached an allelic p-value in the range of 10-7 and were supported by data from the three centers. Three associations were located next to non-coding RNA genes. rs2660852 flanked 5'UTR of LTA4H (leukotriene A4 hydrolase), rs477145 was intronic to TIAM1 (T-cell lymphoma invasion and metastases) and rs2835931 was intronic to KCNJ6 (potassium channel, inwardly rectifying subfamily J, member 6). In analysis of subgroups of CUP patients (smokers, non-smokers and CUP with liver metastases) genome-wide significant associations were noted. For patients with liver metastases associations on chromosome 6 and 11, the latter including a cluster of genes DHCR7 and NADSYN1, encoding key enzymes in cholesterol and NAD synthesis, and KRTAP5-7, encoding a keratin associated protein. This first GWAS on CUP provide preliminary evidence that germline genes relating to inflammation (LTA4H), metastatic promotion (TIAM1) in association with lipid metabolic disturbance (chromosome 11 cluster) may contribute to the risk of CUP.

Cheng W, Liu Y, Zuo Z, et al.
Biological effects of RNAi targeted inhibiting Tiam1 gene expression on cholangiocarcinoma cells.
Int J Clin Exp Pathol. 2015; 8(12):15511-26 [PubMed] Free Access to Full Article Related Publications
OBJECTIVE: To investigate the characteristics of Tiam1 gene expression in human cholangiocarcinoma tissues and benign bile duct tissues, and to analyze the correlations between Tiam1 gene expression and the degree of tumor differentiation, invasive and metastatic abilities. To explore the effect of targeted inhibiting Tiam1 gene expression on proliferation and migration activity of human cholangiocarcinoma cells.
METHODS: Expression of Tiam1 in 83 cases of cholangiocarcinoma tissues and 25 cases of benign bile tissues was detected using immunohistochemistry. The clinical data of patients with cholangiocarcinoma were collected. The correlations between Tiam1 gene expression and the clinicopathologic features in patients with cholangiocarcinoma were analyzed. The human cholangiocarcinoma RBE cells were divided into 3 groups. Cells in experimental group and control group were respectively transfected with Tiam1 shRNA lentiviral vectors and negative shRNA lentiviral control vectors. Cells in blank group received no treatment. Real-time PCR endogenesis was used to verify Tiam1 gene expression. Cell cycle experiments and MTT assay were used to measure cell proliferation activity. Transwell test was used to detect cell migration activity.
RESULTS: The negative rate Tiam1 protein expression in cholangiocarcinoma tissues was significantly higher than that in benign bile tissues (P<0.001). Tiam1 protein expression in cholangiocarcinoma tissues had correlations with cholangiocarcinoma differentiation degree, TNM stage and lymph node metastasis (P<0.05), and had no significant correlations with gender, age and distant metastasis (P>0.05). Real-time PCR detection indicated that Tiam1 expression of experimental group was significantly lower than that in control group and blank group (P<0.05), demonstrating that Tiam1 shRNA was effective on Tiam1 gene silencing in RBE cells. Cell cycle experiment showed that the percentage of S phase in cell cycle in experimental group was lower than that in control group and blank group (P<0.05), demonstrating that after the down-regulation of Tiam1 gene expression, the speed of cell proliferation was inhibited. MTT assay results showed that the total growth speed in experimental group was significantly lower than that in control group and blank group (P<0.05), indicating that the proliferation activity of cholangiocarcinoma cells was inhibited after targeted inhibition of Tiam1 gene expression. Transwell detection results showed that the metastasis rate in experimental group was significantly lower than that in control group and blank group (P<0.05), demonstrating that targeted inhibition of Tiam1 gene expression could significantly inhibit migration ability of RBE cells.
CONCLUSION: Tiam1 expression significantly increased in cholangiocarcinoma tissues, and increased along with the degree of malignancy of cholangiocarcinoma. Targeted silencing Tiam1 expression could inhibit proliferation and migration activity of cholangiocarcinoma cells.

Zheng L, Zhang Y, Lin S, et al.
Down-regualtion of miR-106b induces epithelial-mesenchymal transition but suppresses metastatic colonization by targeting Prrx1 in colorectal cancer.
Int J Clin Exp Pathol. 2015; 8(9):10534-44 [PubMed] Free Access to Full Article Related Publications
Accumulating evidence identified that epithelial-mesenchymal transition (EMT) is acquired during progression to metastatic, but whether it is an absolute requirement is still controversial. MiR-106b has been confirmed to promote cancer cell proliferation; however few studies are available on its functions in EMT and metastasis in colorectal cancer (CRC). In this study, we found that knocking down miR-106b induced EMT conferring migratory and invasive properties. MiR-106b knockdown induced cytoskeletal reorganization through staining intracellular F-actin. The expression of Rho GTPases (Rac1 and Cdc42) and Tiam1 was significantly enforced after miR-106b down-regulation. However, miR-106b knocking down could suppress metastatic colonization in vivo. Correspondingly, over expression of miR-106b obtained an opposite effect. We identified Prrx1 was a direct target of miR-106b through using target prediction algorithms and dual-Luciferase reporter assay. Moreover, Moreover, we also found TGF-β1 could down-regulate miR-106b, and simultaneously miR-106b also influences the expression of TGF-β1, establishing a negative feedback loop to regulate the expression of Prrx1 together. Taken together, these findings demonstrated that miR-106b knockdown could induce EMT which conferring cells migratory and invasive properties but could not accomplish distant metastatic colonization efficiently.

Guo X, Wang M, Zhao Y, et al.
Par3 regulates invasion of pancreatic cancer cells via interaction with Tiam1.
Clin Exp Med. 2016; 16(3):357-65 [PubMed] Related Publications
The conserved polarity complex, which comprises partitioning-defective proteins Par3, Par6, and the atypical protein kinase C, affects various cell-polarization events, including assembly of tight junctions. Control of tight junction assembly is closely related to invasion and migration potential. However, as the importance of conserved polarity complexes in regulating pancreatic cancer invasion and metastasis is unclear, we investigated their role and mechanism in pancreatic cancers. We first detect that the key protein of the conserved polarity complex finds that only Par3 is down-regulated in pancreatic cancer tissues while Par6 and aPKC show no difference. What is more, Par3 tissues level was significantly and positively associated with patient overall survival. Knocking-down Par3 promotes pancreatic cancer cells invasion and migration. And Par3 requires interaction with Tiam1 to affect tight junction assembly, and then affect invasion and migration of pancreatic cancer cells. Then, we find that tight junction marker protein ZO-1 and claudin-1 are down-regulated in pancreatic cancer tissues. And the relationship of the expression of Par3 and ZO-1 in pancreatic cancer tissue is linear correlation. We establish liver metastasis model of human pancreatic cancer cells in Balb/c nude mice and find that knocking down Par3 promotes invasion and metastasis and disturbs tight junction assembly in vivo. Taken together, these results suggest that the Par3 regulates invasion and metastasis in pancreatic cancers by controlling tight junction assembly.

Hu J, Lv G, Zhou S, et al.
The Downregulation of MiR-182 Is Associated with the Growth and Invasion of Osteosarcoma Cells through the Regulation of TIAM1 Expression.
PLoS One. 2015; 10(5):e0121175 [PubMed] Free Access to Full Article Related Publications
BACKGROUND: Osteosarcoma is the most common primary bone malignancy in children and young adults. Increasing results suggest that discovery of microRNAs (miRNAs) might provide a novel therapeutical target for osteosarcoma.
METHODS: MiR-182 expression level in osteosarcoma cell lines and tissues were assayed by qRT-PCR. MiRNA mimics or inhibitor were transfected for up-regulation or down-regulation of miR-182 expression. Cell function was assayed by CCK8, migration assay and invasion assay. The target genes of miR-182 were predicated by bioinformatics algorithm (TargetScan Human).
RESULTS: MiR-182 was down-regulated in osteosarcoma tissues and cell lines. Overexpression of miR-182 inhibited tumor growth, migration and invasion. Subsequent investigation revealed that TIAM1 was a direct and functional target of miR-182 in osteosarcoma cells. Overexpression of miR-182 impaired TIAM1-induced inhibition of proliferation and invasion in osteosarcoma cells.
CONCLUSIONS: Down-expression of miR-182 in osteosarcoma promoted tumor growth, migration and invasion by targeting TIAM1. MiR-182 might act as a tumor suppressor gene whose down-regulation contributes to the progression and metastasis of osteosarcoma, providing a potential therapy target for osteosarcoma patients.

Zhu G, Fan Z, Ding M, et al.
An EGFR/PI3K/AKT axis promotes accumulation of the Rac1-GEF Tiam1 that is critical in EGFR-driven tumorigenesis.
Oncogene. 2015; 34(49):5971-82 [PubMed] Related Publications
Epidermal growth factor receptor (EGFR) signaling regulates cell growth and survival, and its overactivation drives cancer development. One important branch of EGFR signaling is through activation of GTPase Rac1, which further promotes cell proliferation, survival and cancer metastasis. Here, we show that EGFR activates Rac1 via inducing the accumulation of its specific guanine nucleotide exchange factor, T-cell lymphoma invasion and metastasis 1 (Tiam1) in non-small-cell lung cancer and colon cancer cells. Conversely, elevated Tiam1 is required for EGFR-induced tumorigenesis. In human lung adenocarcinoma and colon cancer specimens, Tiam1 expression strongly correlates with EGFR expression. We further reveal that AKT, a key downstream protein kinase of EGFR, phosphorylates Tiam1 at several consensus sites, facilitates the interaction of Tiam1 with scaffold proteins 14-3-3 and leads to an increase of Tiam1 stability. Subsequently, Tiam1 is dephosporylated and destabilized by PP2A. Together, our study identifies a bidirectional (phosphorylation and dephosphorylation) regulatory mechanism controlling Tiam1 stability and provides new insights on how EGFR signaling triggers Rac1 activation and cancer development.

Zhu H, Yang M, Zhang H, et al.
Genome-wide association pathway analysis to identify candidate single nucleotide polymorphisms and molecular pathways for gastric adenocarcinoma.
Tumour Biol. 2015; 36(7):5635-9 [PubMed] Related Publications
To demonstrate candidate single nucleotide polymorphisms that might affect susceptibility to gastric adenocarcinoma as well as their potential mechanisms and pathway hypotheses, we performed a genome-wide association study dataset of gastric adenocarcinoma. Our study included 472,342 single nucleotide polymorphisms from 2766 cases of gastric cardia adenocarcinoma cases and 11,013 subjects from north central China as control groups. The identify candidate causal SNPs and pathways (ICSNPathway) analysis was employed to identify 13 candidate single nucleotide polymorphisms, nine genes, and 15 pathways. The top three candidate SNPs were rs3765524 (-log10(p) = 8.556), rs2274223 (-log10(p) = 8.633), and rs2076472 (-log10(p) = 3.205). The strongest mechanism involved the modulation of rs4745 and rs12904, thereby affecting their regulatory roles in ephrin receptor binding (p = 0.001; FDR = 0.005). The second strongest hypothetical biological mechanism was that rs932972 and rs1052177 alters the regulatory role of the glycolysis pathway (p < 0.001; FDR = 0.013). The most significant pathway was the regulation of the ephrin receptor binding pathway, which involved EFNA1, TIAM1, EFNA5, EFNB2, and EFNB3.

Wang S, Li S, Tang Q, et al.
Overexpression of Tiam1 promotes the progression of laryngeal squamous cell carcinoma.
Oncol Rep. 2015; 33(4):1807-14 [PubMed] Related Publications
T-lymphoma invasion and metastasis‑inducing factor 1 (Tiam1) has been reported in various types of human cancer, which play important roles in facilitating the meta-stasis of malignant tumor. However, the investigation of Tiam1 in laryngeal squamous-cell carcinoma is extremely rare. The aim of the present study was to assess Tiam1 expression and examine its function in tumorigenesis and the metastasis of laryngeal squamous cell carcinoma (LSCC) in vitro. Tiam1 expression in 98 primary LSCC tissue specimens was analyzed by immunohistochemistry and correlated with clinicopathological parameters and patients' survival. To investigate the effects of Tiam1 on the progression of LSCC, Tiam1/C1199 plasmid was transfected into LSCC, and proliferation, apoptosis, migration and invasion of transfected cells were examined using MTT, flow cytometry, wound-healing and Transwell assay, respectively. The results showed that, Tiam1 was detected in all primary LSCC samples. Additionally, Tiam1 overexpression was closely correlated with tumor progression and patient survival. Tiam1 overexpression was statistically significant, and served as an independent predictor of prognosis for patients with LSCC. The upregulation of Tiam1 by Tiam1/C1199 plasmid had no effect on the prolife-ration of transfected cells, but decreased the apoptotic rate of transfected cells, while the ability of migration and invasion was increased. These results suggested that Tiam1 overexpression in LSCC is possibly involved in the promotion of migration and invasion, and is a promising therapeutic target in the prevention of the progression of LSCC.

Li Z, Yu X, Wang Y, et al.
By downregulating TIAM1 expression, microRNA-329 suppresses gastric cancer invasion and growth.
Oncotarget. 2015; 6(19):17559-69 [PubMed] Free Access to Full Article Related Publications
Gastric cancer (GC) is one of the most common malignant tumors worldwide. Emerging evidence has shown that abnormal microRNAs (miRNAs) expression is involved in tumorigenesis. MiR-329 was previously reported to act as a tumor suppressor or oncogene in some types of cancer. However, its function in gastric cancer (GC) is unclear. Here, we found that miR-329 was down-regulated in GC compared with adjacent controls. Enforced expression of miR-329 inhibited proliferation, migration and invasion of gastric cancer cells in vitro. We identified T lymphoma invasion and metastasis 1 (TIAM1) gene as potential target of miR-329. MiR-329 levels inversely correlated with TIAM1 expression in GC. Importantly, TIAM1 rescued the miR-329-mediated inhibition of cell invasion and proliferation. Finally, reintroduction of miR-329 significantly inhibited tumor formation of GC in the xenograft mice. Our findings suggest that miR-329 is a tumor suppressor and potential therapeutic target of GC.

Vaughan L, Tan CT, Chapman A, et al.
HUWE1 ubiquitylates and degrades the RAC activator TIAM1 promoting cell-cell adhesion disassembly, migration, and invasion.
Cell Rep. 2015; 10(1):88-102 [PubMed] Free Access to Full Article Related Publications
The E3 ubiquitin ligase HUWE1, deregulated in carcinoma, has been implicated in tumor formation. Here, we uncover a role for HUWE1 in cell migration and invasion through degrading the RAC activator TIAM1, implying an additional function in malignant progression. In MDCKII cells in response to HGF, HUWE1 catalyzes TIAM1 ubiquitylation and degradation predominantly at cell-cell adhesions, facilitating junction disassembly, migration, and invasion. Depleting HUWE1 or mutating the TIAM1 ubiquitylation site prevents TIAM1 degradation, antagonizing scattering, and invasion. Moreover, simultaneous depletion of TIAM1 restores migration and invasion in HUWE1-depleted cells. Significantly, we show that HUWE1 stimulates human lung cancer cell invasion through regulating TIAM1 stability. Finally, we demonstrate that HUWE1 and TIAM1 protein levels are inversely correlated in human lung carcinomas. Thus, we elucidate a critical role for HUWE1 in regulating epithelial cell-cell adhesion and provide additional evidence that ubiquitylation contributes to spatiotemporal control of RAC.

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