Prognostic relevance of Tiam1 protein expression in prostate carcinomas

T-lymphoma invasion and metastasis 1 promotes invadopodia formation and is regulated by the PI3K/Akt signaling pathway in hepatocellular carcinoma

At present, there are still many poorly understood aspects of the mechanisms underlying hepatocellular carcinoma (HCC) invasion and metastasis. Invadopodia are important structures for cancer cell invasion and metastasis. We determined that high T-lymphoma invasion and metastasis 1 (Tiam1) expression is associated with HCC invasion and metastasis and poor patient prognosis after surgery. Gain- and loss-of-function studies confirmed that Tiam1 promotes invadopodia formation in HCC by activating Rac1. A series of biochemical experiments confirmed that this effect is regulated by the PI3K/Akt signaling pathway. We also confirmed that PIP2 facilitates this effect. In summary, these findings reveal that Tiam1 plays an important role in invadopodia formation in HCC.

Fibrinogen-like protein 2 promotes the accumulation of myeloid-derived suppressor cells in the hepatocellular carcinoma tumor microenvironment

The tumor microenvironment in hepatocellular carcinoma can be classified into cellular and non-cellular components. Myeloid-derived suppressor cells (MDSCs) are cellular components of this microenvironment that serve an important role in the progression of hepatocellular carcinoma. Fibrinogen-like protein 2 (FGL2) has been demonstrated to promote tumor progression by regulating cellular components of the tumor microenvironment in various types of malignant tumor. The present study aimed to determine the expression of FGL2 in hepatocellular carcinoma and its effect on the tumor microenvironment in order to determine novel targets for liver cancer treatment. Immunohistochemistry and reverse transcription quantitative PCR were performed to determine the expression level of FGL2 and the correlation with surface markers of human MDSCs in hepatocellular carcinoma. Furthermore, a mouse hepatocellular carcinoma cell line overexpressing FGL2 was established by stable transfection of a lentivirus expressing FGL2. In addition, fresh bone marrow cells extracted from mouse femurs were in vitro cultured using conditioned medium derived from the cell line overexpressing FGL2. An orthotopic hepatocellular carcinoma mouse model was also established. The results demonstrated that FGL2 expression level in hepatocellular carcinoma tissues was closely associated with tumor size. FGL2 level was positively correlated with the expression level of the MDSC surface markers CD11b and CD33 in hepatocellular carcinoma. The in vitro results demonstrated that FGL2 could maintain the undifferentiated state of bone marrow cells, therefore promoting MDSC accumulation. Furthermore, in the orthotopic hepatocellular carcinoma mouse model, we observed that overexpression of FGL2 could promote tumor growth and significantly increase the number of MDSCs in the tumors and spleen. Taken together, these findings suggested that FGL2 may promote hepatocellular carcinoma tumor growth by promoting the accumulation of MDSCs in the tumor microenvironment.

microRNA-1271-5p/TIAM1 suppresses the progression of ovarian cancer through inactivating Notch signaling pathway

Objective

Ovarian cancer (OC) has been regarded as the most malignant gynecological neoplasm and often confers grave outcomes owing to the frequent metastasis and high recurrence. A previous study has demonstrated that miR-1271-5p is implicated in OC progression, however, the possible mechanism of it remains unknown. The purpose of this investigation was to explore how miR-1271-5p regulates the progression of OC.

Methods

Gene Expression Omnibus (GEO) and The Cancer Genome Atlas (TCGA) databases were employed to analyze the differentially expressed miRNAs or genes as well as their corresponding prognostic values. miR-1271-5p expression in OC cells was examined by qRT-PCR. Cell counting kit 8 (CCK-8), colony formation, and transwell tests were conducted to evaluate the proliferation, migration and invasion potentials. Bioinformatics prediction and luciferase activity analysis were utilized to predict and verify the target gene of miR-1271-5p. Western blot assay was carried out to measure protein expression.

Results

miR-1271-5p was significantly decreased in OC and its down-regulation was associated with the grave outcome of OC patients. Upregulation of miR-1271-5p inhibited cell viability, but miR-1271-5p knockdown promoted the proliferation of OC cells. TIAM1 was a direct target gene of miR-1271-5p and expressed in OC tissues at higher level. High expression of TIAM1 induced the poorer prognosis of patients with OC. Further functional analyses showed that the suppressive role of miR-1271-5p on OC cell malignant behaviors was overturned by the upregulation of TIAM1. The protein levels of Cyclin D1, HES1, NOTCH and NUMB were remarkably changed due to the abnormal expression of miR-1271-5p and TIAM1.

Conclusion

To sum up, miR-1271-5p inhibits proliferation, invasion and migration of OC cells by directly repressing TIAM1 to inactivate the Notch signaling pathway, which provides an alternative therapeutic candidate for the advancement of OC treatment.

Low expression of organic anion-transporting polypeptide 1B3 predicts a poor prognosis in hepatocellular carcinoma

Objective

To detect the expression level of organic anion-transporting polypeptide 1B3 (OATP1B3) in hepatocellular carcinoma (HCC) and to determine the relationship between OATP1B3 expression, clinicopathological features, and prognosis.

Methods

Immunohistochemical (IHC) staining was performed to detect the expression of OATP1B3 in 131 HCC specimens and in 89 adjacent nontumorous tissues. Moreover, the expression levels of OATP1B3 in 30 pairs of tumor and matched adjacent nontumorous tissues were detected by quantitative real-time polymerase chain reaction, and 34 pairs of tumor and matched adjacent nontumorous tissues were detected by Western blotting. The χ² test was applied to analyze the correlation between OATP1B3 expression and the clinical parameters of HCC patients. The prognostic value of OATP1B3 in HCC patients was estimated by Kaplan-Meier survival analysis and the Cox stepwise proportional hazards model.

Results

Compared with that in adjacent nontumorous tissues (25.8%, 23/89), OATP1B3 expression was significantly downregulated in tumor tissues (59.5%, 78/131) (P < 0.0001). Moreover, OATP1B3 expression was markedly correlated with tumor size, recurrence, tumor differentiation, and tumor node metastasis (TNM) stage (P < 0.05 for each). However, age, sex, tumor capsule status, HBsAg, cirrhosis, tumor number, vascular invasion, and serum alpha fetoprotein were not associated with OATP1B3 expression. The overall survival (OS) and disease-free survival (DFS) of HCC patients who had high expression of OATP1B3 were significantly longer than those of patients with low expression (33.0% vs 12.9%, P = 0.001; 18.8% vs 5.3%, P < 0.0001). Cox multivariate analysis showed that OATP1B3, invasion, and TNM stage (P < 0.05 for each) were independent prognostic factors of OS in HCC patients and that OATP1B3 and TNM stage (both P < 0.05) were independent prognostic factors of DFS in HCC patients.

Conclusions

The expression of OATP1B3 in HCC patients was significantly lower than that in adjacent nontumorous tissues. OATP1B3 expression may be a potential prognostic marker in HCC patients.

High Tiam1 expression predicts positive lymphatic metastasis and worse survival in patients with malignant solid tumors: a systematic review and meta-analysis

Background

Many studies have explored the prognostic value of T-cell lymphoma invasion and metastasis inducing factor 1 (Tiam1) and its association with lymphatic metastasis in malignant solid tumors, but the conclusions remain controversial. Therefore, we performed a meta-analysis to systematically assess the prognostic value of Tiam1 expression and its association with lymphatic metastasis in malignant solid tumors.

Methods

We searched eligible studies in PubMed, Web of Science and EMBASE databases (from inception up to October 2018). The combined HR with 95% CI was used to estimate the prognostic value of Tiam1 expression. The correlation between Tiam1 expression and lymphatic metastasis was assessed using the combined odds ratio (OR) with 95% CI.

Results

A total of 17 studies with 2,228 patients with solid tumors were included in this meta-analysis. The overall estimated results showed that high Tiam1 expression was significantly associated with shorter overall survival (HR= 2.08, 95% CI: 1.62-2.68, P<0.01), and disease-free survival (HR = 1.86, 95% CI: 1.49-2.32, P<0.01). Besides, we also found that there was a close relationship between high Tiam1 expression and positive lymphatic metastasis (OR=2.63; 95% CI: 1.79-3.84, P<0.01).

Conclusion

High Tiam1 expression was significantly associated with shorter survival and positive lymphatic metastasis in patients with malignant solid tumors. Therefore, Tiam1 may be a promising prognostic biomarker and an effective therapeutic target for malignant solid tumors.

Tumor-suppressive microRNA-10a inhibits cell proliferation and metastasis by targeting Tiam1 in esophageal squamous cell carcinoma

Aberrant microRNAs (miRNAs) expressions could contribute to the progression of numerous cancers, including esophageal squamous cell carcinoma, while miR-10a participates in multiple biological processes on cancers. However, the molecular mechanism of miR-10a in esophageal squamous cell carcinoma (ESCC) has not been investigated. Herein, miR-10a was significantly reduced in ESCC clinical tissues and ESCC cell lines (EC109 and TE-3). In addition, immunohistochemistry indicated that the expressions of α-SMA, Ki-67, and PCNA in tumor tissues were higher than that of controls. In vitro, overexpression of miR-10a dramatically suppressed cell proliferation and enhanced cell apoptosis, while the decrease of miR-10a expressed the opposite outcome. Specially, overexpression of miR-10a caused a G0/G1 peak accumulation. Moreover, miR-10a also negatively regulated ESCC cell migration and invasion. Furthermore, targetscan bioinformatics predictions and the dual-luciferase assay confirmed that Tiam1 was a direct target gene of miR-10a. The statistical analysis showed Tiam1 was negatively in correlation with miR-10a in ESCC patient samples. And silencing Tiam1 could lead to a decline on cell growth, invasion, and migration in ESCC cell lines, while it could enhance cell apoptosis and cause a G0/G1 peak accumulation. In vivo, it revealed that miR-10a notably decreased the tumor growth and metastasis in xenograft model and pulmonary metastasis model. And it showed a lower expressions of Tiam1 in the miR-10a mimics group by immunohistochemistry. Taken together the results, they indicated that miR-10a might function as a novel tumor suppressor in vitro and in vivo via targeting Tiam1, suggesting miR-10a to be a candidate biomarker for the ESCC therapy.

Emerging Themes in PDZ Domain Signaling: Structure, Function, and Inhibition

Post-synaptic density-95, disks-large and zonula occludens-1 (PDZ) domains are small globular protein-protein interaction domains widely conserved from yeast to humans. They are composed of ∼90 amino acids and form a classical two α-helical/six β-strand structure. The prototypical ligand is the C-terminus of partner proteins; however, they also bind internal peptide sequences. Recent findings indicate that PDZ domains also bind phosphatidylinositides and cholesterol. Through their ligand interactions, PDZ domain proteins are critical for cellular trafficking and the surface retention of various ion channels. In addition, PDZ proteins are essential for neuronal signaling, memory, and learning. PDZ proteins also contribute to cytoskeletal dynamics by mediating interactions critical for maintaining cell-cell junctions, cell polarity, and cell migration. Given their important biological roles, it is not surprising that their dysfunction can lead to multiple disease states. As such, PDZ domain-containing proteins have emerged as potential targets for the development of small molecular inhibitors as therapeutic agents. Recent data suggest that the critical binding function of PDZ domains in cell signaling is more than just glue, and their binding function can be regulated by phosphorylation or allosterically by other binding partners. These studies also provide a wealth of structural and biophysical data that are beginning to reveal the physical features that endow this small modular domain with a central role in cell signaling.

Rac GTPases in Hematological Malignancies

Emerging evidence suggests that crosstalk between hematologic tumor cells and the tumor microenvironment contributes to leukemia and lymphoma cell migration, survival, and proliferation. The supportive tumor cell-microenvironment interactions and the resulting cellular processes require adaptations and modulations of the cytoskeleton. The Rac subfamily of the Rho family GTPases includes key regulators of the cytoskeleton, with essential functions in both normal and transformed leukocytes. Rac proteins function downstream of receptor tyrosine kinases, chemokine receptors, and integrins, orchestrating a multitude of signals arising from the microenvironment. As such, it is not surprising that deregulation of Rac expression and activation plays a role in the development and progression of hematological malignancies. In this review, we will give an overview of the specific contribution of the deregulation of Rac GTPases in hematologic malignancies.

Clinical evaluation of integrated panel testing by next-generation sequencing for somatic mutations in neuroblastomas with MYCN unamplification

Neuroblastomas (NBs) exhibit heterogeneity and show clinically significant prognosis classified by genetic alterations. Among prognostic genes or genome factors, MYCN amplification (MNA) is the most established genomic marker of poor prognosis in patients with NB. However, the prognostic classification of more than 60% of patients without MNA has yet to be clarified. In this study, the application of target next-generation sequencing (NGS) was extended on the basis of a comprehensive panel of regions where copy number variations (CNVs) or point mutations occurred to improve the prognostic evaluation of these patients and obtain the sequence of 33 patients without MNA. A mean coverage depth of 887× was determined in the target regions in all of the samples, and the mapped read percentage was more than 99%. Somatic mutations in patients without MNA could be precisely defined on the basis of these findings, and 17 unique somatic aberrations, including 14 genes, were identified in 11 patients. Among these variations, most were CNVs with a number of 13. The 3-year event-free survival (EFS) of CNV(−) patients was 60.0% compared with the EFS (16.7%) of CNV(+) patients (P = 0.015, HR = 0.1344, 95%, CI = 0.027 to 0.678). CNVs were also associated with unfavorable histological characteristics (P = 0.003) and likely to occur in stage 4 (P = 0.041). These results might further indicate the role of CNVs in NB chemotherapy resistance (P = 0.059) and show CNVs as a therapeutic target. In multivariate analysis, the presence of CNVs was a clinically negative prognostic marker that impaired the outcome of patients without MNA and associated with poor prognosis in this tumor subset. Comprehensive genetic/genomic profiling instead of focusing on single genetic marker should be performed through in-depth NGS that could reveal prognostic information, improve NB target therapy, and provide a basis for investigations on NB pathogenesis.

Overexpression of epithelial cell transforming 2 protein in colorectal carcinoma predicts a poor prognosis

Epithelial cell transforming 2 (Ect2) protein is a member of the human diffuse B-cell lymphoma family of guanine nucleotide exchange factors, which activate the Ras homolog gene family of small GTPases; however, the clinical implications of Ect2 in colorectal carcinoma (CRC) are unclear. The present study aimed to determine the relationship between Ect2 expression and prognosis in patients with CRC. Western blot analysis and immunohistochemistry assays were used to determine the expression of Ect2 in CRC and paired non-cancerous tissues from 66 patients. The correlation between Ect2 expression and clinicopathological parameters was assessed using χ² tests. Patient survival was determined using the Kaplan-Meier method and log-rank test. Cox regression was used for multivariate analysis of prognostic factors. Results demonstrated that Ect2 protein was highly expressed in human CRC samples [29/45 (64.45%)] and significantly correlated with a poor prognosis (P<0.05). Compared with normal tissues, CRC tissues demonstrated higher expression levels of Ect2 mRNA [44/66 (66.67%)]. In addition, highly-expressed Ect2 was significantly associated with recurrence (P=0.023) and invasion (P=0.008) of CRC. High Ect2 expression levels in patients were associated with poorer overall survival (OS) and disease-free survival (DFS) compared with lower expression levels of Ect2. Based on multivariate analysis, Ect2 overexpression was significantly correlated with OS and DFS (P=0.015 and 0.020, respectively). In conclusion, Ect2 overexpression is an independent and important prognostic factor for OS and DFS in patients with CRC.

TIAM1 inhibits lung fibroblast differentiation in pulmonary fibrosis

The differentiation of fibroblasts to myofibroblasts is critical for the development of idiopathic pulmonary fibrosis (IPF). T-cell lymphoma invasion and metastasis 1 (TIAM1) is known to be associated with amyotrophic lateral sclerosis 1 and colorectal cancer; however, its role in IPF is unclear. The aim of the present study was to investigate the expression and roles of TIAM1 in lung fibroblasts during pulmonary fibrosis. It was demonstrated that TIAM1 expression was significantly increased in fibrotic lung tissue and lung fibroblasts from bleomycin (BLM)-treated mice compared with control mice (P<0.05). TIAM1 expression and differentiation were significantly upregulated in human lung fibroblasts challenged with transforming growth factor-β (TGF-β) compared with unchallenged cells (P<0.05). Furthermore, inhibition of the nuclear factor (NF)-κB signaling pathway significantly attenuated TGF-β-induced TIAM1 expression and decreased fibroblast differentiation in human lung fibroblasts (P<0.05). Similarly, overexpression of TIAM1 significantly inhibited TGF-β-induced fibroblast differentiation, as indicated by decreased expression of fibronectin and α-smooth muscle actin (SMA; P<0.05). The results of the present study also demonstrated that TIAM1 knockdown increased TGF-β-induced fibroblast differentiation (P<0.05). These findings suggest that TIAM1 expression is associated with lung fibroblast differentiation in pulmonary fibrosis via an NF-κB-dependent pathway, and that TIAM1 inhibits lung fibroblast differentiation in pulmonary fibrosis.

The Tiam1 guanine nucleotide exchange factor is auto-inhibited by its pleckstrin homology coiled-coil extension domain

T-cell lymphoma invasion and metastasis 1 (Tiam1) is a Dbl-family guanine nucleotide exchange factor (GEF) that specifically activates the Rho-family GTPase Rac1 in response to upstream signals, thereby regulating cellular processes including cell adhesion and migration. Tiam1 contains multiple domains, including an N-terminal pleckstrin homology coiled-coiled extension (PHn-CC-Ex) and catalytic Dbl homology and C-terminal pleckstrin homology (DH-PHc) domain. Previous studies indicate that larger fragments of Tiam1, such as the region encompassing the N-terminal to C-terminal pleckstrin homology domains (PHn-PHc), are auto-inhibited. However, the domains in this region responsible for inhibition remain unknown. Here, we show that the PHn-CC-Ex domain inhibits Tiam1 GEF activity by directly interacting with the catalytic DH-PHc domain, preventing Rac1 binding and activation. Enzyme kinetics experiments suggested that Tiam1 is auto-inhibited through occlusion of the catalytic site rather than by allostery. Small angle X-ray scattering and ensemble modeling yielded models of the PHn-PHc fragment that indicate it is in equilibrium between "open" and "closed" conformational states. Finally, single-molecule experiments support a model in which conformational sampling between the open and closed states of Tiam1 contributes to Rac1 dissociation. Our results highlight the role of the PHn-CC-Ex domain in Tiam1 GEF regulation and suggest a combinatorial model for GEF inhibition and activation of the Rac1 signaling pathway.

Clinical implication of Tiam1 overexpression in the prognosis of patients with serous ovarian carcinoma

T lymphoma invasion and metastasis 1 (Tiam1), a guanine nucleotide exchange factor, was originally identified as an invasion- and metastasis-inducing gene in T lymphoma cells. High expression levels of the human Tiam1 gene have been found in numerous human malignancies, suggesting a potential role as a modifier of tumor initiation and progression. However, little is known about the status of Tiam1 in ovarian carcinoma. The present study aimed to investigate the clinicopathological significance of high Tiam1 expression in serous ovarian carcinoma. Immunohistochemical staining for Tiam1 was performed in 182 patients with serous ovarian carcinoma, in 76 patients with ovarian borderline tumors and in 72 patients with benign ovarian tumors. Immunofluorescence staining was also performed to detect the subcellular localization of Tiam1 protein in SK-OV-3 ovarian carcinoma cells. The correlations between high Tiam1 expression and the clinicopathological features of the ovarian carcinomas were evaluated by the χ² test and Fisher's exact test. The overall survival (OS) rates were calculated by the Kaplan-Meier method, and the association between prognostic factors and patient survival was analyzed by the Cox proportional hazard model. Tiam1 protein showed a cytoplasmic and nuclear staining pattern in ovarian carcinoma. Strongly-positive Tiam1 protein expression was observed in 59.3% (108/182) of ovarian carcinomas, which was significantly higher than in benign serous tumors (12.5%; 9/72). Moreover, the rate of strongly-positive Tiam1 expression in borderline serous tumors (31.6%; 24/76) was also significantly higher than that in benign serous tumors. High Tiam1 protein expression was closely associated with a high histological grade, metastasis, advanced clinical stage and lower OS rates in ovarian carcinoma. Multivariate analysis indicated that Tiam1 was an independent prognostic factor, along with metastasis and clinical stage, in patients with ovarian carcinoma. In conclusion, Tiam1 expression is strongly associated with grade and outcome in ovarian carcinoma, and may serve as a useful molecular marker for clinical management.

Clinicopathological implications of Tiam1 overexpression in invasive ductal carcinoma of the breast

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.

By downregulating TIAM1 expression, microRNA-329 suppresses gastric cancer invasion and growth

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

The fibroblast Tiam1-osteopontin pathway modulates breast cancer invasion and metastasis

Background

The tumor microenvironment has complex effects in cancer pathophysiology that are not fully understood. Most cancer therapies are directed against malignant cells specifically, leaving pro-malignant signals from the microenvironment unaddressed. Defining specific mechanisms by which the tumor microenvironment contributes to breast cancer metastasis may lead to new therapeutic approaches against advanced breast cancer.

Methods

We use a novel method for manipulating three-dimensional mixed cell co-cultures, along with studies in mouse xenograft models of human breast cancer and a histologic study of human breast cancer samples, to investigate how breast cancer-associated fibroblasts affect the malignant behaviors of breast cancer cells.

Results

Altering fibroblast Tiam1 expression induces changes in invasion, migration, epithelial-mesenchymal transition, and cancer stem cell characteristics in associated breast cancer cells. These changes are both dependent on fibroblast secretion of osteopontin and also long-lasting even after cancer cell dissociation from the fibroblasts, indicating a novel Tiam1-osteopontin pathway in breast cancer-associated fibroblasts. Notably, inhibition of fibroblast osteopontin with low doses of a novel small molecule prevents lung metastasis in a mouse model of human breast cancer metastasis. Moreover, fibroblast expression patterns of Tiam1 and osteopontin in human breast cancers show converse changes correlating with invasion, supporting the hypothesis that this pathway in tumor-associated fibroblasts regulates breast cancer invasiveness in human disease and is thus clinically relevant.

Conclusions

These findings suggest a new therapeutic paradigm for preventing breast cancer metastasis. Pro-malignant signals from the tumor microenvironment with long-lasting effects on associated cancer cells may perpetuate the metastatic potential of developing cancers. Inhibition of these microenvironment signals represents a new therapeutic strategy against cancer metastasis that enables targeting of stromal cells with less genetic plasticity than associated cancer cells and opens new avenues for investigation of novel therapeutic targets and agents.

Electronic supplementary material

The online version of this article (doi:10.1186/s13058-016-0674-8) contains supplementary material, which is available to authorized users.

Effects of transcutaneous acupoint electrical stimulation on the imbalance of Th1, Th2, Th17 and Treg cells following thoracotomy of patients with lung cancer

An imbalance in the various T lymphocytes, including T-helper (Th)₁, Th₂ and Th₁₇ cells, and regulatory T (T_reg) cells, has been associated with immune dysfunction, and may occur following thoracotomy of patients with lung cancer. The use of transcutaneous acupoint electrical stimulation (TAES) has previously been demonstrated to exert immunoregulatory effects; therefore, the present study aimed to evaluate whether TAES was able to attenuate postoperative immune suppression in patients with lung cancer. Thoracic surgical patients with lung cancer (n=27) underwent TAES (frequency, 2/100 Hz; intensity, 4-12 mA) at the bilateral large intestine 4, pericardium 6, small intestine 3 and San Jiao 6 acupuncture points for 30 min, prior to incision, and at 20, 44, 68, 92 and 116 h following thoracotomy. The number of Th₁, Th₂, Th₁₇ and T_reg cells, and the protein and mRNA expression levels of related cytokines were measured by flow cytometry, ELISA and polymerase chain reaction, respectively. The balance of Th₁, Th₂, Th₁₇ and T_reg cells in the peripheral blood of patients with lung cancer was disrupted following thoracotomy. TAES administration increased the percentage of Th₁ and Th₁₇ cells, the protein expression levels of interleukin (IL)-2 and interferon-γ, the mRNA expression levels of T-bet and RAR-related orphan receptor-γt, and decreased the percentage of Th₂ cells, IL-10 protein expression levels, and GATA binding protein 3 mRNA expression levels. The results of the present study demonstrated that TAES was able to partially attenuate the postoperative immune depression of patients with lung cancer, by regulating the balance of Th₁, Th₂, Th₁₇ and T_reg cells, and the expression levels of related cytokines and transcription factors; therefore, TAES may be considered to be a promising strategy for treating postoperative immune dysfunction in patients with lung cancer.

Expression of microRNA-10a, microRNA-342-3p and their predicted target gene TIAM1 in extranodal NK/T-cell lymphoma, nasal type

MicroRNAs (miRNAs) may act as oncogenes or tumor suppressor genes in different types of human cancer. T-lymphoma invasion and metastasis inducing factor 1 (TIAM1) participates in the development of several types of human cancer. However, the expression of miRNAs and TIAM1 in extranodal natural killer (NK)/T-cell lymphoma, nasal type (ENKTCL) remains poorly understood. In the present study, the association between the expression levels of miR-10a and miR-342-3p and the protein expression levels of TIAM1 was examined in ENKTCL tissues. The expression levels of miR-10a, miR-22, miR-340, miR-342-3p and miR-590-5p in 15 primary ENKTCL tissues were analyzed using quantitative polymerase chain reaction, and the protein expression levels of TIAM1 in 21 primary ENKTCL tissues were analyzed using immunohistochemistry. The expression levels of miR-10a and miR-342-3p were lower in ENKTCL tissues than in normal NK cells, but no significant differences were observed in the expression levels of miR-22, miR-340 and miR-590-5p in ENKTCL tissues, compared with normal NK cells. The low expression levels of miR-10a detected in the tissues of patients with ENKTCL were inversely correlated with the age of the patients, whereas the low expression levels of miR-342-3p measured in these samples were not correlated with any demographic or clinical features of the patients. The protein expression levels of TIAM1 were higher in ENKTCL tissues than in normal and reactive lymph node hyperplasia tissues, and positively correlated with the Ann Arbor stage and international prognostic index score of the tumors. Furthermore, the expression levels of miRNA-10a and miRNA-342-3p were inversely correlated with the protein expression levels of TIAM1 in ENKTCL tissues. These data suggest that TIAM1 may contribute to the pathogenesis of ENKTCL, and miRNA-10a and miRNA-342-3p may be involved in the development of ENKTCL via the TIAM1 pathway.

The prognostic value of Tiam1 protein expression in head and neck squamous cell carcinoma: a retrospective study

Introduction

Head and neck squamous cell carcinoma (HNSCC) is a common cancer worldwide and has a poor prognosis. A biomarker predicting the clinical outcome of HNSCC patients could be useful in guiding treatment planning. Overexpression of the T lymphoma invasion and metastasis 1 (Tiam1) protein has been implicated in the migration and invasion of neoplasms. However, its role in HNSCC progression needs to be further validated. We detected the expression of Tiam1 in normal and tumor tissues and determined its association with clinical outcomes in patients with HNSCC.

Methods

We measured the expression of Tiam1 in normal and cancerous tissue samples from the patients with HNSCC treated at Sun Yat-sen University Cancer Center between 2001 and 2008. The Tiam1 expression was scored from 0 to 12 based on the percentage of positively stained cells and the staining intensity. We then determined the diagnostic performance of this score in predicting overall survival (OS) and disease-free survival (DFS).

Results

Of the 194 evaluable patients, those with advanced disease, lymph node metastasis at diagnosis, and recurrence or metastasis during follow-up had a higher tendency of having high Tiam1 expression as compared with their counterparts (P < 0.05). The proportion of samples with high Tiam1 expression was also higher in cancerous tissues than in non-cancerous tissues (57.7% vs. 13.9%, P < 0.001). Cox proportional hazards regression analysis revealed that Tiam1 expression scores of 5 and greater independently predicted short OS and DFS.

Conclusion

The Tiam1 expression is shown as a promising biomarker of clinical outcomes in patients with HNSCC and should be evaluated in prospective trials.

The Downregulation of MiR-182 Is Associated with the Growth and Invasion of Osteosarcoma Cells through the Regulation of TIAM1 Expression

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.

MicroRNA-377 suppresses cell proliferation and invasion by inhibiting TIAM1 expression in hepatocellular carcinoma

Increasing evidence has suggested that microRNAs (miRNAs) play an important role in the initiation and progression of hepatocellular carcinoma (HCC). Here, we identified a novel tumor suppressive miRNA, miR-377, and investigated its role in HCC. The expression of miR-377 in HCC tissues and cell lines was detected by real-time reverse-transcription PCR. The effects of miR-377 on HCC cell proliferation and invasion were also investigated. Western blot and luciferase reporter assay were used to identify the direct and functional target of miR-377. The expression of miR-377 was markedly downregulated in human HCC tissues and cell lines. MiR-377 can dramatically inhibit cell growth and invasion in HCC cells. Subsequent investigation revealed that T lymphoma invasion and metastasis 1 (TIAM1) was a direct and functional target of miR-377 in HCC cells. Overexpression of miR-377 impaired TIAM1-induced promotion of proliferation and invasion in HCC cells. Finally, miR-377 is inversely correlated with TIAM1 expression in human HCC tissues. These findings reveal that miR-377 functions as a tumor suppressor and inhibits the proliferation and invasion of HCC cells by targeting TIAM1, which may consequently serve as a therapeutic target for HCC patients.

PI3K regulation of RAC1 is required for KRAS-induced pancreatic tumorigenesis in mice

BACKGROUND & AIMS

New drug targets are urgently needed for the treatment of patients with pancreatic ductal adenocarcinoma (PDA). Nearly all PDAs contain oncogenic mutations in the KRAS gene. Pharmacological inhibition of KRAS has been unsuccessful, leading to a focus on downstream effectors that are more easily targeted with small molecule inhibitors. We investigated the contributions of phosphoinositide 3-kinase (PI3K) to KRAS-initiated tumorigenesis.

METHODS

Tumorigenesis was measured in the Kras(G12D/+);Ptf1a(Cre/+) mouse model of PDA; these mice were crossed with mice with pancreas-specific disruption of genes encoding PI3K p110α (Pik3ca), p110β (Pik3cb), or RAC1 (Rac1). Pancreatitis was induced with 5 daily intraperitoneal injections of cerulein. Pancreata and primary acinar cells were isolated; acinar cells were incubated with an inhibitor of p110α (PIK75) followed by a broad-spectrum PI3K inhibitor (GDC0941). PDA cell lines (NB490 and MiaPaCa2) were incubated with PIK75 followed by GDC0941. Tissues and cells were analyzed by histology, immunohistochemistry, quantitative reverse-transcription polymerase chain reaction, and immunofluorescence analyses for factors involved in the PI3K signaling pathway. We also examined human pancreas tissue microarrays for levels of p110α and other PI3K pathway components.

RESULTS

Pancreas-specific disruption of Pik3ca or Rac1, but not Pik3cb, prevented the development of pancreatic tumors in Kras(G12D/+);Ptf1a(Cre/+) mice. Loss of transformation was independent of AKT regulation. Preneoplastic ductal metaplasia developed in mice lacking pancreatic p110α but regressed. Levels of activated and total RAC1 were higher in pancreatic tissues from Kras(G12D/+);Ptf1a(Cre/+) mice compared with controls. Loss of p110α reduced RAC1 activity and expression in these tissues. p110α was required for the up-regulation and activity of RAC guanine exchange factors during tumorigenesis. Levels of p110α and RAC1 were increased in human pancreatic intraepithelial neoplasias and PDAs compared with healthy pancreata.

CONCLUSIONS

KRAS signaling, via p110α to activate RAC1, is required for transformation in Kras(G12D/+);Ptf1a(Cre/+) mice.

Multi-dose parecoxib provides an immunoprotective effect by balancing T helper 1 (Th1), Th2, Th17 and regulatory T cytokines following laparoscopy in patients with cervical cancer

Analgesic treatment with anti‑inflammatory drugs may aid the prevention of postoperative pain and the attenuation of the postoperative immune inflammatory response. The current study presents a randomized, double‑blind controlled study, which was performed to investigate the levels of Th1, Th2, Th17 and Treg cytokines, including interleukin (IL)‑2, interferon (IFN)‑γ, IL‑4, IL‑10, IL‑17, IL‑23 and transforming growth factor (TGF)‑β in the peripheral blood of patients with cervical cancer following laparoscopy. The effects of perioperative multi‑dose parecoxib on postoperative immune function was evaluated. A total of 80 patients with cervical cancer (stage IB/IIA, ASA I‑III, aged 18‑65 years) that were scheduled for laparoscopy were randomly assigned into either the parecoxib (I; n=40) or control (II; n=40) groups. Group I received 40 mg parecoxib 30 min prior to surgery and then every 12 h subsequent to surgery for 60 h, and group II received normal saline at the corresponding time points. Intravenous tramadol (100 mg) was prescribed for pain relief as required. The mRNA and protein expression levels of cytokines in the peripheral blood were detected by quantitative polymerase chain reaction and ELISA. Pain visual analog scales (VAS) and incidence, analgesic relief, adverse events and the length of hospital stay were recorded. It was demonstrated that the mRNA and protein levels of IL‑2, IFN‑γ and IL‑17 in the two groups were reduced subsequent to surgery, while mRNA and protein expression levels of IL‑4, IL‑10 and TGF‑β were enhanced. Administration of multi‑dose parecoxib may diminish the increase in postoperative IL‑2, IFN‑γ and IL‑17 levels, and suppress the excessive production of IL‑4, IL‑10 and TGF‑β. This effect is accompanied by lower VAS scores, pain incidence, postoperative nausea/vomiting and infections. In conclusion, perioperative multi‑dose parecoxib was able to alleviate postoperative pain and ameliorate surgery‑induced immune suppression by balancing Th1, Th2, Th17 and Treg cytokines following laparoscopy in patients with cervical cancer. The current study provides support to the hypothesis that parecoxib may be a more effective therapeutic strategy than the currently available options, for postoperative pain and immune function management of patients with cancer.

Overexpression of Tiam1 is associated with malignant phenotypes of nasopharyngeal carcinoma

The aim of the present study was to analyze the roles of T lymphoma invasion and metastasis 1 (Tiam1) in nasopharyngeal carcinoma (NPC) progression and its correlation with clinicopathological features, including the survival of patients with NPC. Tiam1 protein expression in NPC tissues was examined using immunohistochemistry. Reverse transcription-polymerase chain reaction (RT-PCR) and immunofluorescence staining were performed to detect the expression of Tiam1 in 6 NPC cell lines. Stable Tiam1-overexpressing NPC cells using a transfection technique and Tiam1-silencing NPC cells using short hairpin RNA were constructed. Subsequently, MTT assay, plate and soft agar colony formation assays, cell adhesion, migration, invasion assays and experimental animal models were carried out to detect the biological functions of Tiam1 in vitro and in vivo. Immunohistochemical analysis revealed that Tiam1 had high expression in 96 of 140 (68.6%) paraffin-embedded archival NPC biopsies. Tiam1 overexpression was significantly associated with N classification (P=0.004), distant metastasis (P=0.042) and clinical stage (P=0.042). Patients with higher levels of Tiam1 expression had poorer overall survival (P=0.002). Multivariate analysis revealed that Tiam1 expression is an independent prognostic indicator for the overall survival of NPC patients. Using the approaches of exogenous overexpression and the knockdown of Tiam1 expression, respectively, it was confirmed that Tiam1 promoted cell proliferation, adhesion, invasion and migration in vitro and in vivo. These data support the notion that Tiam1 plays an important role in the progression of NPC, and the overexpression of Tiam1 is associated with malignant phenotypes of NPC.

Expression of Tiam1 predicts lymph node metastasis and poor survival of lung adenocarcinoma patients

BACKGROUND

To assess the value of Tiam1 in predicting lymph node metastasis and survival after curative resection in patients with lung adenocarcinoma.

METHODS

Immunohistochemical staining for Tiam1 was performed on 98 adenocarcinoma and 30 normal lung tissues. The association of Tiam1 protein expression with the clinicopathological characteristics and the prognosis of lung adenocarcinoma were subsequently assessed.

RESULTS

Immunohistochemical analysis showed that 60 of 98 (61.22%) adenocarcinoma tissues showed high expression of Tiam1, and high Tiam1 expression was significantly associated with advanced TNM stage (P < 0.0005) and lymph node status (P < 0.0005) of lung adenocarcinoma. Moreover, the lung adenocarcinoma patients with low Tiam1 expression had higher overall survival than patients with high Tiam1 expression (log rank value = 10.805, P = 0.001). High expression of Tiam1 predicted poor overall survival of patients in stages I + II (P = 0.006). Furthermore, multivariate analysis indicated that high expression of Tiam1 protein was an independent prognostic factor for overall survival (P = 0.011) in patients with lung adenocarcinoma.

CONCLUSION

These findings suggest for the first time that Tiam1 expression may be beneficial in predicting lymph node metastasis and survival of patients with lung adenocarcinoma. A future study will investigate whether Tiam1 can serve as a novel therapeutic target in lung adenocarcinoma.

VIRTUAL SLIDES

The virtual slide(s) for this article can be found here: http://www.diagnosticpathology.diagnomx.eu/vs/1377798917111123.

MiR-141 suppresses the migration and invasion of HCC cells by targeting Tiam1

Background

We have demonstrated that T lymphoma invasion and metastasis 1 (Tiam1) gene is associated with the poor prognosis of patients with hepatocellular carcinoma (HCC), and we used a computational approach to identify miR-141 as a Tiam1-targeting microRNA (miRNA). Here, we explored the function of miR-141 and the relationship between miR-141 and Tiam1 gene in HCC.

Methods

The miR-141 expression in HCC tissues and cell lines was detected and its roles in regulation of HCC cell proliferation, migration and invasion and target gene expression was investigated. Tiam1 was identified as a novel target of miR-141. Ethics statement: our study was approved by the Nanfang Hospital Medical Ethics Committee Ethics statement. Written informed consent was obtained before collection.

Results

Based on in situ hybridization (ISH) analysis, miR-141 was down-regulated in the same HCC samples. Kaplan-Meier analysis demonstrated that patients with low miR-141 expression had poorer overall survival rate than that of the patients with high miR-141 expression. Furthermore, multivariate Cox regression analysis indicated that miR-141 could serve as an independent prognostic factor in HCC. MiR-141 significantly inhibited in vitro cell proliferation, migration and invasion as proved by gain- and loss- of function studies, while the mRNA and protein levels of Tiam1 were reduced in cells over-expressing miR-141. Moreover, Tiam1 treatment antagonized this effect, while knockdown of Tiam1 by Tiam1 short hairpin RNA (shTiam1) induced inhibitory effects.

Conclusions

These findings indicated that miR-141 functions as a tumor suppressor and inhibits the migration and invasion of HCC cells by targeting Tiam1, which may provide novel prognostic and treatment strategies for HCC patients.

Elevated expression of T-lymphoma invasion and metastasis inducing factor 1 in squamous-cell carcinoma of the head and neck and its clinical significance

PURPOSE

T-lymphoma invasion and metastasis inducing factor 1 (Tiam1) overexpression has been reported in a variety of human cancers. However, the investigation of Tiam1 in squamous-cell carcinoma of the head and neck (SCCHN) is extremely rare. The aim of the present study is to assess Tiam1 expression and to explore its role in SCCHN.

METHODS

Tiam1 expression in 119 primary SCCHN tissue specimens was analysed by immunohistochemistry and correlated with clinicopathological parameters and patients' survival. Additionally, 12 paired SCCHN tissues were evaluated for Tiam1 expression by Western blotting.

RESULTS

Western blotting indicated that Tiam1 expression levels in SCCHN carcinomas were significantly higher than those in the corresponding paraneoplastic tissues (P<0.001). Immmunohistochemistry staining revealed that Tiam1 was detected in all primary tumour samples, moreover, Tiam1 overexpression was significantly correlated with lymph node metastasis (P<0.001), clinical stage (P<0.001), histological grade (P=0.001) and recurrence (P<0.001). Survival analysis demonstrated that high Tiam1 expression was significantly correlated with shorter disease-free survival and overall survival (both P<0.001). When combining the Tiam1 expression and lymph node status, Kaplan-Meier survival showed that patients with Tiam1 overexpression/lymph node metastasis (+) had both shorter disease-free and overall survival than others (both P<0.001). Multivariate Cox proportional hazards model analysis confirmed that lymph node metastasis, histological grade and Tiam1 overexpression were statistically significant, independent predictor of prognosis for patients with SCCHN.

CONCLUSION

Tiam1 may contribute to SCCHN progression, and represent as a novel prognostic indicator as well as a potential therapeutic target for SCCHN.

Rho guanine nucleotide exchange factors: regulators of Rho GTPase activity in development and disease

The aberrant activity of Ras homologous (Rho) family small GTPases (20 human members) has been implicated in cancer and other human diseases. However, in contrast to the direct mutational activation of Ras found in cancer and developmental disorders, Rho GTPases are activated most commonly in disease by indirect mechanisms. One prevalent mechanism involves aberrant Rho activation via the deregulated expression and/or activity of Rho family guanine nucleotide exchange factors (RhoGEFs). RhoGEFs promote formation of the active GTP-bound state of Rho GTPases. The largest family of RhoGEFs is comprised of the Dbl family RhoGEFs with 70 human members. The multitude of RhoGEFs that activate a single Rho GTPase reflects the very specific role of each RhoGEF in controlling distinct signaling mechanisms involved in Rho activation. In this review, we summarize the role of Dbl RhoGEFs in development and disease, with a focus on Ect2 (epithelial cell transforming squence 2), Tiam1 (T-cell lymphoma invasion and metastasis 1), Vav and P-Rex1/2 (PtdIns(3,4,5)P3 (phosphatidylinositol (3,4,5)-triphosphate)-dependent Rac exchanger).

Tiam1 transgenic mice display increased tumor invasive and metastatic potential of colorectal cancer after 1,2-dimethylhydrazine treatment

Background

T lymphoma invasion and metastasis 1 (Tiam1) is a potential modifier of tumor development and progression. Our previous study in vitro and in nude mice suggested a promotion role of Tiam1 on invasion and metastasis of colorectal cancer (CRC). In the present study, we generated Tiam1/C1199-CopGFP transgenic mice to investigate the tumorigenetic, invasive and metastatic alterations in the colon and rectum of wild-type and Tiam1 transgenic mice under 1,2-dimethylhydrazine (DMH) treatment.

Methods

Transgenic mice were produced by the method of pronuclear microinlectlon. Whole-body fluorescence imaging (Lighttools, Edmonton, Alberta, Canada), PCR, and immunohistochemical techniques (IHC) were applied sequentially to identify the transgenic mice. The carcinogen DMH (20 mg/kg) was used to induce colorectal tumors though intraperitoneal (i.p.) injections once a week for 24 weeks from the age of 4 weeks on Tiam1 transgenic or non-transgenic mice.

Results

We successfully generated Tiam1/C1199-CopGFP transgenic mice and induced primary tumors in the intestine of both wild type and Tiam1 transgenic mice by DMH treatment. In addition, Tiam1 transgenic mice developed larger and more aggressive neoplasm than wild-type mice. Moreover, immunohistochemical staining revealed that upregulation of Tiam1 was correlated with increased expression of β-Catenin and Vimentin, and downregulation of E-Cadherin in these mice.

Conclusions

Our study has provided in vivo evidence supporting that Tiam1 promotes invasion and metastasis of CRC, most probably through activation of Wnt/β-catenin signaling pathway, in a Tiam1 transgenic mouse model.

Combined general and regional anesthesia and effects on immune function in patients with benign ovarian tumors treated by laparoscopic therapy

OBJECTIVE

Anesthesia has been shown to suppress immune function, which can negatively affect the treatment of patients with various tumors. Here, we assessed two different anesthesia methods, general versus combined regional/general, in treatment of benign ovarian tumor by laparoscopic therapy.

METHODS

Out of 160 patients with benign ovarian tumors treated by laparoscopic therapy, 80 received general anesthesia combined with thoracic epidural anesthesia during surgery, and 80 received general anesthesia only. Venous blood samples were obtained at the following time points: before induction of anesthesia (T0), 2 hours after anesthesia, during operation, 3 days (d) after operation, 5 d after operation, and 7 d after operation. Percentages of CD3(+), CD4(+), and CD4(+)/CD8(+) T lymphocytes were determined at these time points by flow cytometry to assess immune function.

RESULTS

For both groups, percentages of CD3(+), CD4(+), and CD4(+)/CD8(+) T cells decreased significantly from T0 to 2 hr after anesthesia (P < 0.05). These percentages decreased again during surgery. However, T cell percentages in patients receiving combined anesthesia returned to normal levels 5 d after surgery, and those receiving only intravenous anesthesia returned to normal by 7 d after surgery. There were no significant differences in CD3(+), CD4(+), or CD4(+)/CD8(+) T cell percentages between the two anesthesia groups at T0 and 7 d. However, significant differences in these percentages were observed between the two groups at all other time points. Interestingly, the decrease observed within the combined group were less dramatic than those observed within the intravenous-only group (P < 0.05).

CONCLUSIONS

These findings indicate that, while any anesthesia may suppress immune function of patients treated by laparoscopic therapy, the effect of general anesthesia combined with thoracic epidural anesthesia on immune function was less than that produced by general anesthesia alone.

RNAi mediated Tiam1 gene knockdown inhibits invasion of retinoblastoma

T lymphoma invasion and metastasis protein (Tiam1) is up-regulated in variety of cancers and its expression level is related to metastatic potential of the type of cancer. Earlier, Tiam1 was shown to be overexpressed in retinoblastoma (RB) and we hypothesized that it was involved in invasiveness of RB. This was tested by silencing Tiam1 in RB cell lines (Y79 and Weri-Rb1) using siRNA pool, targeting different regions of Tiam1 mRNA. The cDNA microarray of Tiam1 silenced cells showed gene regulations altered by Tiam1 were predominantly on the actin cytoskeleton interacting proteins, apoptotic initiators and tumorogenic potential targets. The silenced phenotype resulted in decreased growth and increased apoptosis with non-invasive characteristics. Transfection of full length and N-terminal truncated construct (C1199) clearly revealed membrane localization of Tiam1 and not in the case of C580 construct. F-actin staining showed the interaction of Tiam1 with actin in the membrane edges that leads to ruffling, and also imparts varying invasive potential to the cell. The results obtained from our study show for the first time that Tiam1 modulates the cell invasion, mediated by actin cytoskeleton remodeling in RB.

Low RIN1 expression in HCC is associated with tumor invasion and unfavorable prognosis

OBJECTIVES

To explore the association between the expression of Ras and Rab interactor 1 (RIN1) and the prognosis of hepatocellular carcinoma (HCC).

METHODS

RIN1 expression was detected in paired HCC tissues by real-time polymerase chain reaction, Western blot analysis, and immunohistochemistry. Transfection was applied to analyze the RIN1 function.

RESULTS

We found that expression of the RIN1 protein was downregulated in the HCC samples compared with the corresponding normal tissues. Downregulation of RIN1 expression was also associated with invasion and poor overall survival (OS). The results of our multivariate analysis indicated that the RIN1 status is a significant prognostic factor for OS. RIN1 overexpression also inhibited cell invasion in HepG2 cells. The expression between RIN1 and ABL2 may present a positive correlation.

CONCLUSIONS

Our results demonstrate that RIN1 suppresses tumor invasion in HCC patients and that a poor prognosis for HCC is expected when RIN1 expression is downregulated.

RNA-aptamers that modulate the RhoGEF activity of Tiam1

Rho GTPases regulate the actin cytoskeleton and thereby control cell migration, cell morphology, cell motility, and other cellular functions. The gene product of the oncogene Tiam1 acts as a guanine nucleotide exchange factor (GEF) for the Rho GTPase Rac. Like other RhoGEFs, Tiam1 is involved in cancer progression, but it also counteracts invasion in different cancer cell types. Hence, further investigations are required to unravel the functions of Tiam1 in the context of cancer initiation and progression, which appear to be cell specific. Although RhoGEFs in general seem to be attractive therapeutic targets, not many inhibitors have been described, yet. Here we report the identification and characterization of inhibitory RNA aptamers that specifically target Tiam1. After 16 selection rounds three aptamers sharing a 15 nucleotides consensus motif were identified. The clones K91 and K11 inhibited the Tiam1-mediated activation of the GTPase Rac2 in vitro. The tightest binder K91 neither bound the Rho GEF Vav1 nor the Arf GEF Cytohesin-2. In the presence of Rac1, the binding of K91 to Tiam1 was impaired indicating that the binding motif on Tiam1 overlaps with the GTPase binding site. K91 and K11 are the first reported inhibitory molecules targeting the GEF function of Tiam1. Due to their specificity over related GEF proteins they may represent promising tools for further elucidation of the biological functions of Tiam1. We anticipated that these aptamers will prove useful in validating the ambiguous roles of Tiam1 in cancer biology.

The microRNA -23b/-27b cluster suppresses the metastatic phenotype of castration-resistant prostate cancer cells

MicroRNAs (miRs) are small, endogenous, non-coding RNAs that regulate the stability and/or translation of complementary mRNA targets. MiRs have emerged not only as critical modulators of normal physiologic processes, but their deregulation may significantly impact prostate and other cancers. The expression of miR-23b and miR-27b, which are encoded by the same miR cluster (miR-23b/-27b), are downregulated in metastatic, castration-resistant tumors compared to primary prostate cancer and benign tissue; however, their possible role in prostate cancer progression is unknown. We found that ectopic expression of miR-23b/-27b in two independent castration-resistant prostate cancer cell lines resulted in suppression of invasion and migration, as well as reduced survival in soft agar (a measure of anoikis). However, there was no effect of miR-23b/-27b on cell proliferation suggesting that these miRs function as metastasis (but not growth) suppressors in prostate cancer. Conversely, inhibition of miR-23b/-27b in the less aggressive androgen-dependent LNCaP prostate cancer cell line resulted in enhanced invasion and migration also without affecting proliferation. Mechanistically, we found that introduction of miR-23b/-27b in metastatic, castration-resistant prostate cancer cell lines resulted in a significant attenuation of Rac1 activity without affecting total Rac1 levels and caused increased levels of the tumor suppressor E-cadherin. Inhibition of these miRs had the opposite effect in androgen-dependent LNCaP cells. These results suggest that miR-23b/-27b are metastasis suppressors that might serve as novel biomarkers and therapeutic agents for castration-resistant disease.

CIP2A is highly expressed in hepatocellular carcinoma and predicts poor prognosis

BACKGROUND

Cancerous inhibitor of protein phosphatase 2A (CIP2A) is highly expressed in hepatocellular carcinoma (HCC) and promotes cell proliferation, cell invasion, and aggressive tumor behavior. However, there have been few studies on the usefulness of CIP2A as an independent prognostic index of HCC. In the current study, the aim was to explore the association between CIP2A expression and prognosis in HCC.

METHODS

The expression of CIP2A and c-MYC was examined by immunohistochemistry in 136 HCC specimens. CIP2A mRNA expression in 27 HCC tissues was also analyzed using quantitative reverse-transcription polymerase chain reaction. The prognostic significance was analyzed by the Kaplan-Meier survival method and log-rank test. Cox regression was adopted for univariate and multivariate analysis of prognostic factors.

RESULTS

CIP2A protein was found to be highly expressed in human liver cancer samples (85/136, 62.5%) and correlated with poor survival (P<0.05). The liver cancer tissues examined exhibited much higher levels of CIP2A mRNA compared with their corresponding normal tissues (19/27, 70.3%). Furthermore, CIP2A mRNA levels were correlated with c-MYC mRNA levels. In addition, the highly expressed CIP2A was associated with recurrence (P=0.014) and invasion (P=0.017) of HCC. Patients with high CIP2A expression had both poorer overall survival (OS) and disease-free survival (DFS). On multivariate analysis, the CIP2A status was a significant prognostic factor for OS and DFS (P=0.017, P=0.026, respectively).

CONCLUSIONS

CIP2A overexpression may be useful as an independent prognostic biomarker for OS and DFS of HCC.

MiR-29c suppresses invasion and metastasis by targeting TIAM1 in nasopharyngeal carcinoma

Based on microarray analysis, we previously reported that miR-29c is significantly downregulated in nasopharyngeal carcinoma (NPC). However, little is known about the effect and molecular mechanisms of action of miR-29c deregulation during the development and progression of NPC. Quantitative RT-PCR demonstrated that miR-29c was significantly downregulated in NPC cell lines and clinical specimens. Wound healing, Transwell migration and lung metastasis assays demonstrated that ectopic expression of miR-29c inhibited NPC cell migration and invasion in vitro and suppressed the formation of lung metastases in vivo. T cell lymphoma invasion and metastasis 1 (TIAM1) was confirmed as a miR-29c target gene using luciferase reporter assays, quantitative RT-PCR and Western blotting. Ectopic expression of TIAM1 significantly promoted the migration and invasion of SUNE-1 cell line stably overexpressing miR-29c. The prognostic value of TIAM1 was analyzed in 217 NPC patients using immunohistochemistry. Strikingly, patients with high TIAM1 expression had poorer overall, disease-free and distant metastasis-free survival than patients with low TIAM1 expression. Furthermore, multivariate Cox regression analysis revealed that TIAM1 could serve as an independent prognostic factor in NPC. The newly identified miR-29c/TIAM1 pathway further elucidates the molecular mechanisms regulating invasion and metastasis in NPC, and may provide novel prognostic and treatment strategies for NPC patients.

β2-syntrophin and Par-3 promote an apicobasal Rac activity gradient at cell-cell junctions by differentially regulating Tiam1 activity

Although Rac and its activator Tiam1 are known to stimulate cell-cell adhesion, the mechanisms regulating their activity in cell-cell junction formation are poorly understood. Here, we identify β2-syntrophin as a Tiam1 interactor required for optimal cell-cell adhesion. We show that during tight-junction (TJ) assembly β2-syntrophin promotes Tiam1-Rac activity, in contrast to the function of the apical determinant Par-3 whose inhibition of Tiam1-Rac activity is necessary for TJ assembly. We further demonstrate that β2-syntrophin localizes more basally than Par-3 at cell-cell junctions, thus generating an apicobasal Rac activity gradient at developing cell-cell junctions. Targeting active Rac to TJs shows that this gradient is required for optimal TJ assembly and apical lumen formation. Consistently, β2-syntrophin depletion perturbs Tiam1 and Rac localization at cell-cell junctions and causes defects in apical lumen formation. We conclude that β2-syntrophin and Par-3 fine-tune Rac activity along cell-cell junctions controlling TJ assembly and the establishment of apicobasal polarity.

Expression of Tiam1 in lung cancer and its clinical significance

The aim of this study was to analyze T-cell lymphoma invasion and metastasis-inducing factor 1 (Tiam1) expression in lung cancer patients. A total of 204 patients with lung cancer tissue lesions were enrolled in the present study, along with 40 cases of normal lung tissue and 40 of normal fetal lung tissue. Tiam1 protein expression level was determined using intensity quantitative analysis, for comparison in lung cancer, metastatic, normal lung, and fetal lung tissue. The positive unit (PU) of Tiam1 was 13.5 ± 5.42 in lung cancer, 5.67 ± 1.56 in normal epithelial cells, and 5.89 ± 1.45 in fetal lung epithelial cells. The value in the lung cancer tissue was significantly higher than that in the normal lung tissue and the fetal lung tissue (P<0.01). The Tiam1 PU values with lymph node metastasis and without lymph node metastasis were 15.2 ± 4.34 and 12.5 ± 4.23, respectively, and the difference was statistically significant (P<0.05). The Tiam1 PU values in different tumor, nodes, metastasis (TNM) stages, III-IV period, and I-II phase were 14.7 ± 4.14 and 11.0 ± 5.34 (P <0.05). A correlation was found between Tiam1 expression and the age of patient, tumor size, tumor type, and tumor differentiation. Tiam1 protein expression in the lung tumor tissue is significantly higher than that in the normal lung tissue and fetal lung tissue. Tiam1 expression may be closely related to lung cancer development and metastasis.

SGEF is overexpressed in prostate cancer and contributes to prostate cancer progression

The purpose of this study was to investigate the potential roles of the SH3-containing guanine nucleotide exchange factor (SGEF) in human prostate cancer. Experimental data showed that SGEF was overexpressed in human prostate cancer cells and specimens. The reduction of SGEF expression through an SGEF-targeting siRNA in androgen-independent C4-2 and C4-2B cells suppressed both anchorage-dependent and anchorage-independent growth. In addition, the androgen receptor (AR) antagonist bicalutamide further strengthened this inhibitory effect due to the suppression of the elevated AR transactivation after knockdown of SGEF. Collectively, our results provide the first demonstration that SGEF is a novel promoter of human prostate cancer progression and development.

Prognostic significance of Tiam1 expression in papillary thyroid carcinoma

T lymphoma and metastasis gene 1 (Tiam1) is a guanine nucleotide exchange factor (GNEF) that regulates the guanosine triphosphatase to facilitate the exchange of guanosine diphosphate for guanosine triphosphate. It specifically activates Rac1, a member of the Rho family of GTPases. Tiam1 is involved in cell proliferation, cytoskeletal organization, cellular adhesion, and transcriptional activation. It has been suggested that alterations in Tiam1 expression might contribute to the progression of various human cancers. The usefulness of Tiam1 expression as a prognostic marker in papillary thyroid carcinoma (PTC) has not been investigated yet. The aim of this study was to analyze the expression of Tiam1 in PTC as well as its association with the clinicopathologic features and prognostic significance. Surgical tissue samples were taken from 106 PTC patients who had been followed up for at least 9.3 years. Strong expression of Tiam1 was detected in 54% of the cases. Tiam1 expression was associated significantly with various clinicopathologic parameters, such as gender (P=0.039), tumor multicentricity (P=0.0124), histologic subtype (P=0.0427), TNM stage (P=0.0151), and distant metastases at diagnosis (P=0.0001). Survival analysis showed that the Tiam1 low-expression group had a significantly shorter overall survival time than Tiam1 high-expression group (P=0.0007). Multivariate analysis showed that Tiam1 expression was a significant and independent prognostic indicator (P=0.0090) for PTC patients. Tiam1 expression may be a novel and independent prognostic marker of PTC patients.

The genomic relationship between primary breast carcinomas and their nodal metastases

We screened the whole tumor genome to identify DNA copy number gains and losses that discriminate between primary breast carcinomas (MP) and their nodal metastases (ML). Six candidate genes were confirmed by quantitative PCR to have differentially distributed copy number changes. Three of the genes (ERRγ, DDX6, and TIAM1) were more commonly amplified in nodal metastases. Principal component analysis revealed that MP-ML pairs varied markedly in their genomic divergence. The latter was larger in PR-negative tumors. Nodal metastases may form early or late in the development of breast carcinomas and PR-negative tumors may metastasize earlier or are genomically less stable.

Statins and prostate cancer: role of cholesterol inhibition vs. prevention of small GTP-binding proteins

Prostate cancer (PCa) is initially regulated by androgens, such as testosterone and dihydrotestosterone, which regulates cell proliferation and survival by activating the androgen receptor (AR), but later progresses to an aggressive, metastatic, androgen-independent stage for which, currently, there is no cure. Here, we argue that prevention of PCa progression is a better strategy compared to trying to cure the disease once it has already progressed. Statins inhibit the mevalonate pathway, thus preventing the synthesis of cholesterol, geranylgeranyl pyrophosphate and farnesyl pyrophosphate. Multiple clinical studies have shown an inverse relationship between statin use and PCa risk, especially the risk for developing advanced metastatic cancer. Biochemical investigations have largely corroborated the positive effect of statins on PCa risk, showing that statins inhibited cell proliferation, induced apoptosis, and decreased cell migration and invasion in PCa cells in vitro. However, investigations of the biochemical mechanism of statin action in preventing advanced/high risk PCa remains inconclusive, as statins can act through cholesterol, geranylgeranyl, or farnesyl mediated signals. This review discusses the current clinical and biochemical findings on the use of statins in preventing PCa. Evidence of statin action through cholesterol as well as geranylgeranylation and farnesylation has been discussed. As cholesterol is a precursor of androgen production, it can reduce PCa risk by decreasing the levels of circulating testosterone, which in turn reduces the levels of interprostatic dihydrotestosterone, a strong ligand for the AR. Cholesterol was also shown to accumulate in lipid rafts and regulate the activation of the phosphatidylinositol 3-kinase/Akt pathway. However, clinical evidence from multiple studies also point to the existence of cholesterol-independent pathways mediating statin action in PCa patients. In particular, ligand-activated AR activation is seen in early stage PCa and activation of the cholesterol pathway did not indicate an effect on metastasis. Cell migration and invasion, on the other hand, is regulated strongly by members of the Ras superfamily of small GTPases, especially the Rho family, which is geranylgeranylated. This review, therefore, also compares the effects of statins on both cholesterol and geranylgeranylated and farnesylated small GTPases regulating tumor progression and metastasis in biochemical and clinical studies.

Distinct ligand specificity of the Tiam1 and Tiam2 PDZ domains

Guanine nucleotide exchange factor proteins of the Tiam family are activators of the Rho GTPase Rac1 and critical for cell morphology, adhesion, migration, and polarity. These proteins are modular and contain a variety of interaction domains, including a single post-synaptic density-95/discs large/zonula occludens-1 (PDZ) domain. Previous studies suggest that the specificities of the Tiam1 and Tiam2 PDZ domains are distinct. Here, we sought to conclusively define these specificities and determine their molecular origin. Using a combinatorial peptide library, we identified a consensus binding sequence for each PDZ domain. Analysis of these consensus sequences and binding assays with peptides derived from native proteins indicated that these two PDZ domains have overlapping but distinct specificities. We also identified residues in two regions (S(0) and S(-2) pockets) of the Tiam1 PDZ domain that are important determinants of ligand specificity. Site-directed mutagenesis of four nonconserved residues in these two regions along with peptide binding analyses confirmed that these residues are crucial for ligand affinity and specificity. Furthermore, double mutant cycle analysis of each region revealed energetic couplings that were dependent on the ligand being investigated. Remarkably, a Tiam1 PDZ domain quadruple mutant had the same specificity as the Tiam2 PDZ domain. Finally, analysis of Tiam family PDZ domain sequences indicated that the PDZ domains segregate into four distinct families based on the residues studied here. Collectively, our data suggest that Tiam family proteins have highly evolved PDZ domain-ligand interfaces with distinct specificities and that they have disparate PDZ domain-dependent biological functions.

Clinicopathological significance of Tiam1 and Rac1 protein expression in esophageal squamous cell carcinoma

AIM: To detect the expression of T-cell lymphoma invasion and metastasis factor1 (Tiam1) and Rac GTPase activating protein 1 (Rac1) proteins in esophageal squamous cell carcinoma (ESCC) and to analyze their correlation with the development, progression, invasion and metastasis of ESCC.

METHODS: The expression of TIAM1 and Rac1 proteins was detected by immunohistochemistry in 62 ESCC specimens, 20 tumor-adjacent atypical hyperplastic epithelial specimens, and 20 normal esophageal epithelial specimens.

RESULTS: The expression of Tiam1 protein was closely correlated with tumor grade, infiltration, lymph node metastasis, and TNM grade in ESCC (χ² = 8.779, 7.680, 4.502 and 4.987, all P < 0.05). There is a significant difference in the positive rate of Tiam1 protein expression among normal esophageal epithelium, tumor-adjacent atypical hyperplastic epithelium and carcinoma [15.0% (3/20), 55.0% (11/20) and 72.6% (45/62), respectively; χ² = 20.643, P < 0.05]. The expression of Rac1 protein was closely correlated with tumor grade, infiltration, lymph node metastasis, and TNM grade in ESCC (χ² = 8.652, 6.884, 8.276 and 6.371, all P < 0.05). There is a significant difference in the positive rate of Rac1 protein expression among normal esophageal epithelium, adjacent atypical hyperplastic epithelium and carcinoma [25.0% (5/20), 70.0% (14/20) and 70.0% (44/62), respectively; χ² = 57.621, P < 0.01]. There is a positive correlation between the expression of Tiam1 and Rac1 proteins (γ_p = 0.642, P < 0.05).

CONCLUSION: Combined detection of Tiam1 and Rac1 expression can be used for early diagnosis and prognostic evaluation of ESCC.

Regulation of breast cancer cell motility by T-cell lymphoma invasion and metastasis-inducing protein

Introduction

T-cell lymphoma invasion and metastasis-inducing protein (Tiam1) is an Ras-related C3 botulinum toxin substrate (Rac)-specific guanine nucleotide exchange factor that was isolated based on its ability to induce a metastatic phenotype. In polarized migrating keratinocytes, Tiam1 is found at the leading edge, where it cooperates with the protease-activated receptor 1 (Par1) complex to establish front-to-rear polarity. Although a positive correlation has been observed between Tiam1 expression and tumor grade in a variety of human malignancies, including breast, its role in breast cancer cells has not yet been examined.

Methods

Tiam1 expression and Rac activity were examined in a panel of human breast cancer cell lines that exhibit different degrees of cell motility. The contribution of Tiam1 to cell motility was directly examined by using transwell motility and wound-healing assays.

Results

Although we observed a striking, positive correlation between Tiam1 expression and cell motility in the panel of breast cancer cell lines, we did not observe a correlation between Tiam1 expression and overall levels of Rac activity. Consistent with this, small interfering ribonucleic acid (siRNA)-mediated suppression of Tiam1 expression limits the motility of cell lines in which Tiam1 expression is high (MDA-MB-231 and MDA-MB-453) but does not substantially alter the overall levels of activated Rac. Tiam1 overexpression is also not sufficient to increase the motility of more poorly motile cells (T-47D) or to increase Rac activity. Immunofluorescence and cellular fractionations indicate that Tiam1 is found predominantly in the Golgi of breast cancer cells, and in the latter case, Tiam1 was shown to co-fractionate with a limited pool of Rac1. Consistent with this Golgi localization, Tiam1 supports cell motility and Golgi reorientation in response to serum in a wound-healing assay using MDA-MB-231 and MDA-MB-435S cells.

Conclusions

Tiam1 expression correlates with cell motility in human breast cancer cells and is required to support the motile phenotype. Localization of endogenous Tiam1 to the Golgi, and its demonstrated role in Golgi reorientation, suggest that it may support motility through a mechanism that is discrete from its known function in leading-edge dynamics.