Proteomic analysis of Tiam1-mediated metastasis in colorectal cancer

TIAM-1 regulates polarized protrusions during dorsal intercalation in the Caenorhabditis elegans embryo through both its GEF and N-terminal domains

Mediolateral cell intercalation is a morphogenetic strategy used throughout animal development to reshape tissues. Dorsal intercalation in the Caenorhabditis elegans embryo involves the mediolateral intercalation of two rows of dorsal epidermal cells to create a single row that straddles the dorsal midline, and thus is a simple model to study cell intercalation. Polarized protrusive activity during dorsal intercalation requires the C. elegans Rac and RhoG orthologs CED-10 and MIG-2, but how these GTPases are regulated during intercalation has not been thoroughly investigated. In this study, we characterized the role of the Rac-specific guanine nucleotide exchange factor (GEF) TIAM-1 in regulating actin-based protrusive dynamics during dorsal intercalation. We found that TIAM-1 can promote formation of the main medial lamellipodial protrusion extended by intercalating cells through its canonical GEF function, whereas its N-terminal domains function to negatively regulate the generation of ectopic filiform protrusions around the periphery of intercalating cells. We also show that the guidance receptor UNC-5 inhibits these ectopic filiform protrusions in dorsal epidermal cells and that this effect is in part mediated via TIAM-1. These results expand the network of proteins that regulate basolateral protrusive activity during directed rearrangement of epithelial cells in animal embryos.

TIAM-1 regulates polarized protrusions during dorsal intercalation in the C. elegans embryo through both its GEF and N-terminal domains

Mediolateral cell intercalation is a morphogenetic strategy used throughout animal development to reshape tissues. Dorsal intercalation in the C. elegans embryo involves the mediolateral intercalation of two rows of dorsal epidermal cells to create a single row that straddles the dorsal midline, and so is a simple model to study cell intercalation. Polarized protrusive activity during dorsal intercalation requires the C. elegans Rac and RhoG orthologs CED-10 and MIG-2, but how these GTPases are regulated during intercalation has not been thoroughly investigated. In this study, we characterize the role of the Rac-specific guanine nucleotide exchange factor (GEF), TIAM-1, in regulating actin-based protrusive dynamics during dorsal intercalation. We find that TIAM-1 can promote protrusion formation through its canonical GEF function, while its N-terminal domains function to negatively regulate this activity, preventing the generation of ectopic protrusions in intercalating cells. We also show that the guidance receptor UNC-5 inhibits ectopic protrusive activity in dorsal epidermal cells, and that this effect is in part mediated via TIAM-1. These results expand the network of proteins that regulate basolateral protrusive activity during directed cell rearrangement.

Summary statement

TIAM-1 activates the Rac pathway to promote protrusion formation via its GEF domain, while its N-terminal domains suppress ectopic protrusions during dorsal intercalation in the C. elegans embryo.

Fascin-1: Updated biological functions and therapeutic implications in cancer biology

Filopodia are cellular protrusions that respond to a variety of stimuli. Filopodia are formed when actin is bound to the protein Fascin, which may play a crucial role in cellular interactions and motility during cancer metastasis. Significantly, the noncanonical features of Fascin-1 are gradually being clarified, including the related molecular network contributing to metabolic reprogramming, chemotherapy resistance, stemness ac-tivity, and tumor microenvironment events. However, the relationship between biological characteristics and pathological features to identify effective therapeutic strategies needs to be studied further. The pur-pose of this review article is to provide a broad overview of the latest molecular networks and multiomics research regarding fascins and cancer. It also highlights their direct and indirect effects on available cancer treatments. With this multidisciplinary approach, researchers and clinicians can gain the most relevant in-formation on the function of fascins in cancer progression, which may facilitate clinical applications in the future.

Emerging Role of Fascin-1 in the Pathogenesis, Diagnosis, and Treatment of the Gastrointestinal Cancers

Simple Summary

Gastrointestinal (GI) cancers, including esophageal, gastric, colorectal, liver, and pancreatic cancers, remain as one of the leading causes of death worldwide, with a large proportion accounting for fatalities related to metastatic disease. The active involvement of fascin-1 in forming membrane protrusions crucial for cellular movement has been identified as an important molecular mechanism behind the phenotypic switch from the localized to the metastatic tumor. Thus, fascin-1 expression status in the malignant tissue has been utilized as an important component in determining the patient’s clinicopathological outcomes. In this review, we provide an up-to-date literature review of the role of fascin-1 in the initiation and metastatic progression of GI tract cancers, its involvement in patients’ clinical outcomes, and its potential as a therapeutic target.

Abstract

Gastrointestinal (GI) cancers, including esophageal, gastric, colorectal, liver, and pancreatic cancers, remain as one of the leading causes of death worldwide, with a large proportion accounting for fatalities related to metastatic disease. Invasion of primary cancer occurs by the actin cytoskeleton remodeling, including the formation of the filopodia, stereocilia, and other finger-like membrane protrusions. The crucial step of actin remodeling in the malignant cells is mediated by the fascin protein family, with fascin-1 being the most active. Fascin-1 is an actin-binding protein that cross-links filamentous actin into tightly packed parallel bundles, giving rise to finger-like cell protrusions, thus equipping the cell with the machinery necessary for adhesion, motility, and invasion. Thus, fascin-1 has been noted to be a key component for determining patient diagnosis and treatment plan. Indeed, the overexpression of fascin-1 in GI tract cancers has been associated with a poor clinical prognosis and metastatic progression. Moreover, fascin-1 has received attention as a potential therapeutic target for metastatic GI tract cancers. In this review, we provide an up-to-date literature review of the role of fascin-1 in the initiation of GI tract cancers, metastatic progression, and patients’ clinical outcomes.

Penalized logistic regression based on L1/2 penalty for high-dimensional DNA methylation data

BACKGROUND:

DNA methylation is a molecular modification of DNA that is vital and occurs in gene expression. In cancer tissues, the 5’–C–phosphate–G–3’(CpG) rich regions are abnormally hypermethylated or hypomethylated. Therefore, it is useful to find out the diseased CpG sites by employing specific methods. CpG sites are highly correlated with each other within the same gene or the same CpG island.

OBJECTIVE:

Based on this group effect, we proposed an efficient and accurate method for selecting pathogenic CpG sites.

METHODS:

Our method aimed to combine a L1/2 regularized solver and a central node fully connected network to penalize group constrained logistic regression model. Consequently, both sparsity and group effect were brought in with respect to the correlated regression coefficients.

RESULTS:

Extensive simulation studies were used to compare our proposed approach with existing mainstream regularization in respect of classification accuracy and stability. The simulation results show that a greater predictive accuracy was attained in comparison to previous methods. Furthermore, our method was applied to over 20000 CpG sites and verified using the ovarian cancer data generated from Illumina Infinium HumanMethylation 27K Beadchip. In the result of the real dataset, not only the indicators of predictive accuracy are higher than the previous methods, but also more CpG sites containing genes are confirmed pathogenic. Additionally, the total number of CpG sites chosen is less than other methods and the results show higher accuracy rates in comparison to other methods in simulation and DNA methylation data.

CONCLUSION:

The proposed method offers an advanced tool to researchers in DNA methylation and can be a powerful tool for recognizing pathogenic CpG sites.

Omics technologies for improved diagnosis and treatment of colorectal cancer: Technical advancement and major perspectives

Colorectal cancer (CRC) ranks third among the most commonly occurring cancers worldwide, and it causes half a million deaths annually. Alongside mechanistic study for CRC detection and treatment by conventional techniques, new technologies have been developed to study CRC. These technologies include genomics, transcriptomics, proteomics, and metabolomics which elucidate DNA markers, RNA transcripts, protein and, metabolites produced inside the colon and rectum part of the gut. All these approaches form the omics arena, which presents a remarkable opportunity for the discovery of novel prognostic, diagnostic and therapeutic biomarkers and also delineate the underlying mechanism of CRC causation, which may further help in devising treatment strategies. This review also mentions the latest developments in metagenomics and culturomics as emerging evidence suggests that metagenomics of gut microbiota has profound implications in the causation, prognosis, and treatment of CRC. A majority of bacteria cannot be studied as they remain unculturable, so culturomics has also been strengthened to develop culture conditions suitable for the growth of unculturable bacteria and identify unknown bacteria. The overall purpose of this review is to succinctly evaluate the application of omics technologies in colorectal cancer research for improving the diagnosis and treatment strategies.

Structure, function and disease relevance of Omega-class glutathione transferases

The Omega-class cytosolic glutathione transferases (GSTs) have distinct structural and functional attributes that allow them to perform novel roles unrelated to the functions of other GSTs. Mammalian GSTO1-1 has been found to play a previously unappreciated role in the glutathionylation cycle that is emerging as significant mechanism regulating protein function. GSTO1-1-catalyzed glutathionylation or deglutathionylation of a key signaling protein may explain the requirement for catalytically active GSTO1-1 in LPS-stimulated pro-inflammatory signaling through the TLR4 receptor. The observation that ML175 a specific GSTO1-1 inhibitor can block LPS-stimulated inflammatory signaling has opened a new avenue for the development of novel anti-inflammatory drugs that could be useful in the treatment of toxic shock and other inflammatory disorders. The role of GSTO2-2 remains unclear. As a dehydroascorbate reductase, it could contribute to the maintenance of cellular redox balance and it is interesting to note that the GSTO2 N142D polymorphism has been associated with multiple diseases including Alzheimer's disease, Parkinson's disease, familial amyotrophic lateral sclerosis, chronic obstructive pulmonary disease, age-related cataract and breast cancer.

Circulating HMGB1 and RAGE as Clinical Biomarkers in Malignant and Autoimmune Diseases

High molecular group box 1 (HMGB1) is a highly conserved member of the HMG-box-family; abundantly expressed in almost all human cells and released in apoptosis; necrosis or by activated immune cells. Once in the extracellular space, HMGB1 can act as a danger associated molecular pattern (DAMP), thus stimulating or inhibiting certain functions of the immune system; depending on the “combinatorial cocktail” of the surrounding milieu. HMGB1 exerts its various functions through binding to a multitude of membrane-bound receptors such as TLR-2; -4 and -9; IL-1 and RAGE (receptor for advanced glycation end products); partly complex-bound with intracellular fragments like nucleosomes. Soluble RAGE in the extracellular space, however, acts as a decoy receptor by binding to HMGB1 and inhibiting its effects. This review aims to outline today’s knowledge of structure, intra- and extracellular functions including mechanisms of release and finally the clinical relevance of HMGB1 and RAGE as clinical biomarkers in therapy monitoring, prediction and prognosis of malignant and autoimmune disease.

Annexin A4 and cancer

Annexin A4 (Anxa4) is one of the Ca(2+)-regulated and phospholipid-binding annexin superfamily proteins. Anxa4 has a potential role in diagnosis, prognosis, and treatment of certain cancers. Studies indicate that Anxa4 up-regulation promotes the progression of tumor and chemoresistance of colorectal cancer (CRC), esophageal squamous cell carcinoma (ESCC), endometrial carcinoma (EC), gastric cancer (GC), chemoresistant lung cancer (LC), malignant mesothelioma (MM), renal cell carcinoma (RCC), ovarian clear cell carcinoma (OCCC), cholangiocarcinoma, hepatocellular carcinoma (HCC), breast cancer (BC), and laryngeal cancer. Interestingly, Anxa4 also might specifically function as a tumor suppressor for prostate cancer (PCa) and have a paradoxical role for pancreatic cancer (PCC). Differential expression of Anxa4 may distinguish major salivary gland tumor (MSGT) from thyroid cancer. In addition, its differential expression was linked to Sirt1-induced cisplatin resistance of oral squamous cell carcinoma (OSCC) and miR-7-induced migration and invasion inhibition of glioma. This current review summarizes and discusses the clinical significance of Anxa4 in cancer as well as its potential mechanisms of action. It may provide new integrative understanding for future studies on the exact role of Anxa4 in cancer.

Polymorphisms of glutathione S-transferase genes and survival of resected hepatocellular carcinoma patients

AIM: To investigate the effects of single nucleotide polymorphisms (SNPs) in glutathione S-transferase (GST) genes on survival of hepatocellular carcinoma (HCC) patients.

METHODS: Twelve tagging SNPs in GST genes (including GSTA1, GSTA4, GSTM2, GSTM3, GSTO1, GSTO2 and GSTP1) were genotyped using Sequenom MassARRAY iPLEX genotyping method in a cohort of 214 Chinese patients with resected HCC. The Cox proportional hazards model and log-rank test were performed to determine the SNPs related to outcome. Additionally, stratified analysis was performed at each level of the demographic and clinical variables. An SNP-gene expression association model was further established to investigate the correlation between SNP and gene expression.

RESULTS: Two SNPs (GSTO2: rs7085725 and GSTP1: rs4147581) were significantly associated with overall survival in HCC patients (P = 0.035 and 0.042, respectively). In stratified analysis, they were more significantly associated with overall survival in patients with younger age, male gender and cirrhosis. We further investigated cumulative effects of these two SNPs on overall survival in HCC patients. Compared with the patients carrying no unfavorable genotypes, those carrying 2 unfavorable genotypes had a 1.70-fold increased risk of death (P < 0.001). The cumulative effects were more significant in those patients with younger age, male gender and cirrhosis (HR = 2.00, 1.94 and 1.97, respectively; all P < 0.001). Additionally, we found that heavy smoking resulted in a significantly worse overall survival in those patients carrying variant alleles of rs7085725 (HR = 2.07, 95%CI: 1.13-3.76, P = 0.018). The distributions of GSTO2: rs7085725 and GSTP1: rs4147581 genotypes were associated with altered gene expression and contributed to influences on overall survival.

CONCLUSION: Our study provides the first evidence that GSTO2 and GSTP1 gene polymorphisms may serve as independent prognostic markers for HCC 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.

Improving colorectal cancer management: the potential of proteomics

Colorectal cancer (CRC) is the third most common cancer worldwide. Successful treatment is heavily dependent on tumor stage at the time of detection, but unfortunately CRC is often only detected in advanced stages. New biomarkers in the form of genes or proteins that can be used for diagnosis, prognostication, follow-up, and treatment selection and monitoring could be of great benefit for the management of CRC. Furthermore, proteins could prove valuable new targets for therapy. Therefore, clinical proteomics has gained a lot of scientific interest in this regard. To get an overall insight into the extent to which this research has contributed to a better management of CRC, we give a comprehensive overview of the results of proteomics research on CRC, focusing on expression proteomics, in other words, protein profiling studies. Furthermore, we evaluate the potential of the discriminating proteins identified in this research for clinical use as biomarkers for (early) diagnosis, prognosis and follow-up of CRC or as targets for new therapeutic regimens.

Significance of Tiam1 and Rac1 expression in assessing remote organ metastasis of colorectal cancer

AIM: To observe the expression of T lymphoma invasion and metastasis-inducing factor1 (Tiam1) and Rac GT-Pase activating protein1 (Rac1) in colorectal cancer and to investigate the relationship between Tiam1/Rac1 expression and remote organ metastasis of postoperative colorectal cancer.

METHODS: Tiam1/Rac1 expression in 87 colorectal cancer specimens and 40 tumor-adjacent colorectal tissue specimens was detected by immunohistochemistry. Tiam1 mRNA expression was detected by competitive RT-PCR. Activity of Rac1 protein was detected by precipitation method.

RESULTS: Tiam1 and Rac1 were positively stained in colorectal tissue, and positive signals were mainly distributed in the nucleus. Tiam1 mRNA expression was significantly increased in colorectal cancer (0.6 ± 0.02 vs 0.24 ± 0.02, P < 0.0005), and Tiam1 expression was higher in postoperative patients with remote organ metastasis than in those without remote organ metastasis (0.91 ± 0.02 vs 0.52 ± 0.02, P < 0.0005). Activity of Rac1 was also significantly increased in colorectal cancer tissue (0.17±0.01 vs 0.07±0.05, P < 0.0005) and was higher in postoperative patients with remote organ metastasis than in those without remote organ metastasis (0.25 ± 0.02 vs 0.15 ± 0.01, P < 0.0005). There was no significant correlation between Tiam1/Rac1 expression and tumor differentiation in colorectal cancer (0.63 ± 0.04, 0.60 ± 0.04, 0.57 ± 0.04, P = 0.613; 0.18 ± 0.06, 0.17 ± 0.05, 0.15 ± 0.05, P = 0.558).

CONCLUSION: Tiam1 and Rac1 expression positively correlates with remote organ metastasis of colorectal cancer and can be used to predict remote organ metastasis of postoperative patients with colorectal cancer.

Proteomic analysis of chronic restraint stress-induced Gan (肝)-stagnancy syndrome in rats

OBJECTIVE

To analyze the proteomic characteristics of Gan (肝)-stagnancy syndrome (GSS) by seeking the differential protein in blood and tissues of GSS model rats.

METHODS

GSS model rats were established by chronic restraint stress, keeping rats in restrain chamber for 6 h every day for 21 successive days. Their blood and liver samples were collected at the end of experiment for differential protein detection with methods of isoelectrofocusing and polyacrylamide SDS-PAGE, silver staining, and scanning. The gel images were analyzed with Imagemaster 2D Elite software, and the excavated differential protein spots were identified with matrix assistant laser resolving TOF mass spectrometry, Western blot, ELISA, and RT-PCR, respectively.

RESULTS

A method for isolating the protein in blood serum and tissues by two-dimensional gel electrophoresis was established and optimized. Six serum proteins and three liver proteins that differentially expressed were identified. The down-regulated differential proteins in serum of GSS model rats were serum albumin precursor, beta 1 globin, antibody against muscle acetylcholine receptor, Ig lambda-2 C region, and transthyretin (TTR), and those in liver tissue were aryl sulfotransferase, enoyl-CoA hydratase, and TTR. TTR down-regulation was found in both serum and liver. Preliminary biological information analysis showed that these differential proteins involved in immune, neuroendocrine, nutrition, and substance metabolism.

CONCLUSION

Proteomic analysis of differential proteins showed that TTR, aryl sulfotransferase, and enoyl-CoA hydratase expressions are downregulated in the GSS model rats, suggesting that the susceptibility of cancer could be enhanced by chronic stress.

High-mobility group box 1 and cancer

High-mobility group box 1 protein (HMGB1), a chromatin associated nuclear protein and extracellular damage associated molecular pattern molecule (DAMP), is an evolutionarily ancient and critical regulator of cell death and survival. Overexpression of HMGB1 is associated with each of the hallmarks of cancer including unlimited replicative potential, ability to develop blood vessels (angiogenesis), evasion of programmed cell death (apoptosis), self-sufficiency in growth signals, insensitivity to inhibitors of growth, inflammation, tissue invasion and metastasis. Our studies and those of our colleagues suggest that HMGB1 is central to cancer (abnormal wound healing) and many of the findings in normal wound healing as well. Here, we focus on the role of HMGB1 in cancer, the mechanisms by which it contributes to carcinogenesis, and therapeutic strategies based on targeting HMGB1.

Application of proteomics in colorectal cancer research

Colorectal cancer is one of the most common malignant tumors in China. Its morbidity and mortality are increasing year by year. The emergence of proteomics has pushed colorectal cancer research forward. In this article, we will review the application of proteomics in the study of the diagnosis, pathogenesis and treatment of colorectal cancer.

The PHCCEx domain of Tiam1/2 is a novel protein- and membrane-binding module

Tiam1 and Tiam2 (Tiam1/2) are guanine nucleotide-exchange factors that possess the PH-CC-Ex (pleckstrin homology, coiled coil and extra) region that mediates binding to plasma membranes and signalling proteins in the activation of Rac GTPases. Crystal structures of the PH-CC-Ex regions revealed a single globular domain, PHCCEx domain, comprising a conventional PH subdomain associated with an antiparallel coiled coil of CC subdomain and a novel three-helical globular Ex subdomain. The PH subdomain resembles the beta-spectrin PH domain, suggesting non-canonical phosphatidylinositol binding. Mutational and binding studies indicated that CC and Ex subdomains form a positively charged surface for protein binding. We identified two unique acidic sequence motifs in Tiam1/2-interacting proteins for binding to PHCCEx domain, Motif-I in CD44 and ephrinB's and the NMDA receptor, and Motif-II in Par3 and JIP2. Our results suggest the molecular basis by which the Tiam1/2 PHCCEx domain facilitates dual binding to membranes and signalling proteins.

Genomic and oncoproteomic advances in detection and treatment of colorectal cancer

Aims

We will examine the latest advances in genomic and proteomic laboratory technology. Through an extensive literature review we aim to critically appraise those studies which have utilized these latest technologies and ascertain their potential to identify clinically useful biomarkers.

Methods

An extensive review of the literature was carried out in both online medical journals and through the Royal College of Surgeons in Ireland library.

Results

Laboratory technology has advanced in the fields of genomics and oncoproteomics. Gene expression profiling with DNA microarray technology has allowed us to begin genetic profiling of colorectal cancer tissue. The response to chemotherapy can differ amongst individual tumors. For the first time researchers have begun to isolate and identify the genes responsible. New laboratory techniques allow us to isolate proteins preferentially expressed in colorectal cancer tissue. This could potentially lead to identification of a clinically useful protein biomarker in colorectal cancer screening and treatment.

Conclusion

If a set of discriminating genes could be used for characterization and prediction of chemotherapeutic response, an individualized tailored therapeutic regime could become the standard of care for those undergoing systemic treatment for colorectal cancer. New laboratory techniques of protein identification may eventually allow identification of a clinically useful biomarker that could be used for screening and treatment. At present however, both expression of different gene signatures and isolation of various protein peaks has been limited by study size. Independent multi-centre correlation of results with larger sample sizes is needed to allow translation into clinical practice.

Quantitative proteomics characterization of a mouse embryonic stem cell model of Down syndrome

Down syndrome, caused by the trisomy of chromosome 21, is a complex condition characterized by a number of phenotypic features, including reduced neuron number and synaptic plasticity, early Alzheimer disease-like neurodegeneration, craniofacial dysmorphia, heart development defects, increased incidence of childhood leukemia, and powerful suppression of the incidence of most solid tumors. Mouse models replicate a number of these phenotypes. The Tc1 Down syndrome model was constructed by introducing a single supernumerary human chromosome 21 into a mouse embryonic stem cell, and it reproduces a large number of Down syndrome phenotypes including heart development defects. However, little is still known about the developmental onset of the trisomy 21-induced mechanisms behind these phenotypes or the proteins that are responsible for them. This study determined the proteomic differences that are present in undifferentiated embryonic stem cells and are caused by an additional human chromosome 21. A total of 1661 proteins were identified using two-dimensional liquid chromatography followed by tandem mass spectrometry from whole embryonic stem cell lysates. Using isobaric tags for relative and absolute quantification, we found 52 proteins that differed in expression by greater than two standard deviations from the mean when an extra human chromosome 21 was present. Of these, at least 11 have a possible functional association with a Down syndrome phenotype or a human chromosome 21-encoded gene. This study also showed that quantitative protein expression differences in embryonic stem cells can persist to adult mouse as well as reproduce in human Down syndrome fetal tissue. This indicates that changes that are determined in embryonic stem cells of Down syndrome could potentially identify proteins that are involved in phenotypes of Down syndrome, and it shows that these cell lines can be used for the purpose of studying these pathomechanisms.

Overexpression of Tiam1 in hepatocellular carcinomas predicts poor prognosis of HCC patients

Little research has been done to test the usefulness of T-lymphoma invasion and metastasis 1 (Tiam1) as a prognostic marker for hepatocellular carcinoma (HCC). In this study, we investigated Tiam1 expression and its prognostic value for HCC. HCC surgical tissue samples were taken from 152 HCC patients who had been followed up for 5 years. Overexpression of Tiam1 (Tiam1 2+ to 3+) was shown in 63.8% of the cases. The Tiam1 expression level did not correlate with any clinicopathological parameters. However, survival analysis showed that the Tiam1 overexpression group had a significantly shorter overall survival time than the Tiam1 downexpression group (p=0.008). Multivariate analysis showed that Tiam1 expression was a significant and independent prognostic parameter (p=0.042) for HCC patients. Tiam1 expression may be a novel and independent predictor for the prognosis of HCC patients.

Identification of metastasis associated proteins in human lung squamous carcinoma using two-dimensional difference gel electrophoresis and laser capture microdissection

A quantitative proteomic approach was used to discover potential protein markers associated with lymph node metastasis (LNM) in human lung squamous carcinoma (LSC). Laser capture microdissection was performed to purify LSC cells with LNM (LNM LSC) and LSC without LNM (non-LNM LSC). The differentially expressed proteins between pooled microdissected non-LNM LSC and LNM LSC cells were identified by two-dimensional difference gel electrophoresis (2D-DIGE) coupled with mass spectrometry (MS). 14 proteins were found to be differentially expressed between non-LNM LSC and LNM LSC. Among these proteins, ten proteins were overexpressed in LNM LSC compared with non-LNM LSC, and four proteins were downregulated in LNM LSC. Some of these identified proteins (Annexin A2, HSP27, CK19, and 14-3-3sigma) were further confirmed by Western blotting and immunohistochemical analysis. These results show the value of LCM coupled with 2D-DIGE in identifying potential markers for lymph node metastasis of LSC, and also provide further insights into the prognosis of LSC.

Increased expression of high mobility group box 1 (HMGB1) is associated with progression and poor prognosis in human nasopharyngeal carcinoma

High mobility group box 1 (HMGB1) is a versatile protein with intranuclear and extracellular functions that is involved in numerous biological and pathological processes, such as transcription, DNA repair, and response to infection and inflammation. The expression of HMGB1 has been described in many types of cancers, but the role of HMGB1 in nasopharyngeal carcinoma (NPC) is unknown. The aim of this study was to analyse the roles of HMGB1 in NPC progression and clinical outcome using NPC clinical samples. In an immunohistochemical study, HMGB1 had high expression in 89 of 166 cases of NPC (53.6%). HMGB1 overexpression was significantly associated with T classification (p = 0.01), N classification (p = 0.003), distant metastasis (p = 0.046), and clinical stage (p < 0.001). Patients with higher levels of HMGB1 expression had poorer overall survival and disease-free survival, whereas patients with lower levels of HMGB1 expression had better survival. Multivariate analysis showed that HMGB1 expression was an independent prognostic indicator for patient survival. Disruption of endogenous HMGB1 using small interfering RNAs suppressed NPC cell invasive ability. These data support the notion that HMGB1 overexpression has a role in the progression of NPC and hence its poor clinical outcome.

Tiam1-deficiency impairs mammary tumor formation in MMTV-c-neu but not in MMTV-c-myc mice

BACKGROUND

Rho-like small GTPases, including RhoA, Rac1 and Cdc42, are crucial for the regulation of a large variety of biological processes such as the cytoskeletal organization and gene transcription. The activities of Rho GTPases are predominantly controlled by guanine nucleotide exchange factors (GEFs), which activate GTPases by catalyzing the exchange of bound GDP for GTP. Earlier, we have identified the Tiam1 gene as an invasion-inducing gene that encodes a specific activator (GEF) of the Rac GTPase. We found that Tiam1-mediated Rac signaling functions in various aspects of tumorigenicity including the formation and progression of Ras-induced skin tumors and Wnt-induced intestinal tumors. Here, we further distinguish the oncogenic pathways that depend on Tiam1 signaling in the mammary gland.

MATERIAL AND METHODS

We crossed Tiam1 knockout mice with MMTV-c-myc and MMTV-c-neu transgenic mice, in which the expression of both oncogenes is targeted to the mammary gland leading to mammary tumorigenesis.

RESULTS

We found Tiam1 important for Neu-induced tumor formation and progression but not for Myc-induced tumors. Tiam1-deficiency delayed Neu-induced tumor initiation and reduced metastasis but had no effect on the growth of the MMTV-c-neu tumors.

CONCLUSION

Our data indicate that the Rac activator Tiam1 contributes to tumorigenicity induced by specific oncogenic signaling pathways only.