Metastasis suppressor CC3 inhibits angiogenic properties of tumor cells in vitro

HTATIP2 Overexpression was Associated With a Good Prognosis in Gastric Cancer

Introduction: The purpose of this study was to compare the transcriptomes of poorly cohesive carcinoma (PCC; diffuse-type) and well-differentiated tubular adenocarcinoma (WD; intestinal-type) using gastric cancer (GC) tissues and cell lines and to evaluate the prognostic role of HIV-1 Tat Interactive Protein 2 (HTATIP2). Materials and Methods: We performed next-generation sequencing with 8 GC surgical samples (5 WD and 3 PCC) and 3 GC cell lines (1 WD: MKN74, and 2 PCC: KATOIII and SNU601). Immunohistochemistry was used to validate HTATIP2 expression. We performed functional analysis by HTATIP2 overexpression (OE). Kaplan-Meier survival plots and the PrognoScan database were used for survival analysis. Results: The genes with significantly reduced expression in PCC versus WD (in both tissues and cell lines) were HTATIP2, ESRP1, GRHL2, ARHGEF16, CKAP2L, and ZNF724. According to immunohistochemical staining, the HTATIP2-OE group had significantly higher number of patients with early GC (EGC) (T1) (P = .024), less lymph node (LN) metastasis (P = .008), and low TNMA stage (P = .017) than HTATIP2 underexpression (UE) group. Better survival rates were confirmed in the HTATIP2 OE group by Kaplan-Meir survival and PrognoScan analysis. In vitro, HTATIP2-OE in KATO III cells caused a significant decrease in cancer cell migration and invasion. Decreased Snail and Slug expression in HTATIP2 OE cells suggested that epithelial-mesenchymal transition is involved in this process. Conclusion: HTATIP2 might be a good prognostic marker and a candidate target for GC treatment.

HTATIP2 regulates arteriogenic activity in monocytes from patients with limb ischemia

Use of autologous cells isolated from elderly patients with multiple comorbidities may account for the modest efficacy of cell therapy in patients with chronic limb threatening ischemia (CLTI). We aimed to determine whether proarteriogenic monocyte/macrophages (Mo/MΦs) from patients with CLTI were functionally impaired and to demonstrate the mechanisms related to any impairment. Proarteriogenic Mo/MΦs isolated from patients with CLTI were found to have an impaired capacity to promote neovascularization in vitro and in vivo compared with those isolated from healthy controls. This was associated with increased expression of human HIV-1 TAT interactive protein-2 (HTATIP2), a transcription factor known to suppress angiogenesis/arteriogenesis. Silencing HTATIP2 restored the functional capacity of CLTI Mo/MΦs, which was associated with increased expression of arteriogenic regulators Neuropilin-1 and Angiopoietin-1, and their ability to enhance angiogenic (endothelial tubule formation) and arteriogenic (smooth muscle proliferation) processes in vitro. In support of the translational relevance of our findings, silencing HTATIP2 in proarteriogenic Mo/MΦs isolated from patients with CLTI rescued their capacity to enhance limb perfusion in the ischemic hindlimb by effecting greater angiogenesis and arteriogenesis. Ex vivo modulation of HTATIP2 may offer a strategy for rescuing the functional impairment of pro-angio/arteriogenic Mo/MΦs prior to autologous delivery and increase the likelihood of clinical efficacy.

First Characterization of the Transcriptome of Lung Fibroblasts of SSc Patients and Healthy Donors of African Ancestry

Systemic sclerosis (SSc) is a connective tissue disorder that results in fibrosis of the skin and visceral organs. SSc-associated pulmonary fibrosis (SSc-PF) is the leading cause of death amongst SSc patients. Racial disparity is noted in SSc as African Americans (AA) have a higher frequency and severity of disease than European Americans (EA). Using RNAseq, we determined differentially expressed genes (DEGs; q < 0.1, log2FC > |0.6|) in primary pulmonary fibroblasts from SSc lungs (SScL) and normal lungs (NL) of AA and EA patients to characterize the unique transcriptomic signatures of AA-NL and AA-SScL fibroblasts using systems-level analysis. We identified 69 DEGs in "AA-NL vs. EA-NL" and 384 DEGs in "AA-SScL vs. EA-SScL" analyses, and a comparison of disease mechanisms revealed that only 7.5% of DEGs were commonly deregulated in AA and EA patients. Surprisingly, we also identified an SSc-like signature in AA-NL fibroblasts. Our data highlight differences in disease mechanisms between AA and EA SScL fibroblasts and suggest that AA-NL fibroblasts are in a "pre-fibrosis" state, poised to respond to potential fibrotic triggers. The DEGs and pathways identified in our study provide a wealth of novel targets to better understand disease mechanisms leading to racial disparity in SSc-PF and develop more effective and personalized therapies.

Genome-wide association study of the age of onset of type 1 diabetes reveals HTATIP2 as a novel T cell regulator

Introduction

Type 1 diabetes, a disorder caused by autoimmune destruction of pancreatic insulin-producing cells, is more difficult to manage when it presents at a younger age. We sought to identify genetic correlates of the age of onset by conducting the first genome-wide association study (GWAS) treating the age of first diagnosis as a quantitative trait.

Methods

We performed GWAS with a discovery cohort of 4,014 cases and a replication cohort of 493 independent cases. Genome-wide significant SNPs were mapped to a causal variant by Bayesian conditional analysis and gel shift assay. The causal protein-coding gene was identified and characterized by RNA interference treatment of primary human pan-CD4+ T cells with RNA-seq of the transcriptome. The candidate gene was evaluated functionally in primary cells by CD69 staining and proliferation assays.

Results

Our GWAS replicated the known association of the age of diagnosis with the human leukocyte antigen complex (HLA-DQB1). The second signal identified was in an intron of the NELL1 gene on chromosome 11 and fine-mapped to variant rs10833518 (P < 1.54 × 10^-9). Homozygosity for the risk allele leads to average age of onset one year earlier. Knock-down of HIV TAT-interacting protein 2 (HTATIP2), but not other genes in the locus, resulted in alterations to gene expression in signal transduction pathways including MAP kinases and PI3-kinase. Higher levels of HTATIP2 expression are associated with increased viability, proliferation, and activation of T cells in the presence of signals from antigen and cytokine receptors.

Discussion

This study implicates HTATIP2 as a new type 1 diabetes gene acting via T cell regulation. Larger population sample sizes are expected to reveal additional loci.

Absence of HTATIP2 Expression in A549 Lung Adenocarcinoma Cells Promotes Tumor Plasticity in Response to Hypoxic Stress

HIV-1 Tat Interactive Protein 2 (HTATIP2) is a tumor suppressor, of which reduced or absent expression is associated with increased susceptibility to tumorigenesis and enhanced tumor invasion and metastasis. However, whether the absent expression of HTATIP2 is a tumor-promoting factor that acts through improving tumor adaptation to hypoxia is unclear. Here, we established a stable HTATIP2-knockdown A549 human lung adenocarcinoma cell line (A549shHTATIP2) using lentiviral-delivered HTATIP2-targeting short hairpin RNA (shRNA), employed a double subcutaneous xenograft model and incorporated photoacoustic imaging and metabolomics approaches to elucidate the impact of the absent HTATIP2 expression on tumor response to hypoxic stress. Results from the in vivo study showed that A549shHTATIP2 tumors exhibited accelerated growth but decreased intratumoral oxygenation and angiogenesis and reduced sensitivity to sorafenib treatment as compared with their parental counterparts. Moreover, results of the immunoblot and real-time PCR analyses revealed that the HIF2α protein and mRNA levels in vehicle-treated A549shHTATIP2 tumors were significantly increased (p < 0.01 compared with the parental control tumors). Despite the strong HIF2α-c-Myc protein interaction indicated by our co-immunoprecipitation data, the increase in the c-Myc protein and mRNA levels was not significant in the A549shHTATIP2 tumors. Nonetheless, MCL-1 and β-catenin protein levels in A549shHTATIP2 tumors were significantly increased (p < 0.05 compared with the parental control tumors), suggesting an enhanced β-catenin/c-Myc/MCL-1 pathway in the absence of HTATIP2 expression. The finding of significantly decreased E-cadherin (p < 0.01 compared with vehicle-treated A549shHTATIP2 tumors) and increased vimentin (p < 0.05 compared with sorafenib-treated A549 tumors) protein levels in A549shHTATIP2 tumors implicates that the absence of HTATIP2 expression increases the susceptibility of A549 tumors to sorafenib-activated epithelial-mesenchymal transition (EMT) process. Comparison of the metabolomic profiles between A549 and A549shHTATIP2 tumors demonstrated that the absence of HTATIP2 expression resulted in increased tumor metabolic plasticity that enabled tumor cells to exploit alternative metabolic pathways for survival and proliferation rather than relying on glutamine and fatty acids as a carbon source to replenish TCA cycle intermediates. Our data suggest a mechanism by which the absent HTATIP2 expression modulates tumor adaptation to hypoxia and promotes an aggressive tumor phenotype by enhancing the HIF2α-regulated β-catenin/c-Myc/MCL-1 signaling, increasing the susceptibility of tumors to sorafenib treatment-activated EMT process, and improving tumor metabolic plasticity.

Characterization of HTATIP2 and its role during hair follicle cycles in Angora rabbit

Hair follicle (HF) growth and cycling is a complex biological process that occurs in most mammals. As HF growth and cycling directly impacts rabbit wool yield, it is important to better understand the potential regulation pattern of HF development. Our previous study demonstrated that HTATIP2 may participate in regulating rabbit HF cycles, but the molecular mechanism of HTATIP2 remained unclear. In this study, the coding sequence of the HTATIP2 gene in Angora rabbit was cloned. The length of the coding region sequence was 840 bp, which could code 279 amino acids, and exhibited high homology in different mammals. Bioinformatics analyses indicated that the HTATIP2 protein is stable, hydrophilic, located around the cytoplasm, and has a putative signal peptide. Moreover, we verified that HTATIP2 is highly expressed during catagen and telogen of the HF cycle. The overexpression vector was constructed and siRNAs were designed. Overexpression and knockdown of HTATIP2 appeared to regulate JAK-STAT pathway genes, such as BCL2, CCND1, c-Myc, and STAT2. It is therefore likely that HTATIP2 promotes cell apoptosis and inhibits cell proliferation. Our results indicate that HTATIP2 is highly expressed during catagen and telogen and may play an important role in JAK-STAT signaling. This study provides a theoretical foundation for investigating HTATIP2 in biological processes.

Reduction of Tat-interacting Protein 30 Expression Could be a Prognostic Marker in Bladder Urothelial Cancer

Background:

Tat-interacting protein 30 (TIP30) has been reported to be a tumor suppressor, with reduced or absent expression in various tumors. However, its role in bladder urothelial cancer (BUC) has not been investigated. Therefore, herein, we investigated the expression of TIP30 protein in BUC and normal bladder mucosa and the clinical significance of TIP30 expression in the prognosis of BUC.

Methods:

We reviewed data from 79 cases of BUC and 15 adjacent tissue samples from 79 patients treated at our institution between 2004 and 2007. TIP30 expression was examined by immunohistochemistry. The relationship between TIP30 expression and tumor stage, histological grade, and survival was analyzed. Differences between groups were evaluated using the t-test or matched-pairs test, and differences in the survival rates were analyzed with the log-rank test.

Results:

TIP30 protein expression was significantly reduced in BUC tissue (t = −6.91, P < 0.05) compared with normal tissue samples, and in invasive bladder cancer (t = 10.89, P < 0.05) compared with superficial bladder cancer. TIP30 protein expression differed significantly among different differentiated groups classified either according to the World Health Organization (2004, F = 17.48, P < 0.01) or World Health Organization (1973, F = 10.68, P < 0.01). TIP30 protein expression was significantly reduced in high-grade papillary urothelial carcinoma compared with papillary urothelial neoplasm of low malignant potential (P < 0.05) and low-grade papillary urothelial carcinoma (P < 0.05). Meanwhile, TIP30 protein expression was significantly reduced in Grade III BUC, compared with Grade I (P < 0.05) and Grade II (P < 0.05). Patients with low TIP30 expression showed a higher incidence of disease progression than those with high TIP30 expression (t = 2.63, P < 0.05). Kaplan-Meier survival analysis showed a strong positive relationship between TIP30 expression and overall survival (OS) (χ² = 17.29, P < 0.05).

Conclusions:

TIP30 expression was associated with clinical tumor stage in BUC, suggesting that it might play an important role in disease progression. Furthermore, TIP30 might predict postoperative OS. Thus, its evaluation might be useful for predicting prognosis.

Aberrant methylation of HTATIP2 and UCHL1 as a predictive biomarker for cholangiocarcinoma

Cholangiocarcinoma (CCA) is the most common primary liver cancer in Northeastern Thailand where liver fluke infection is highly endemic. Although aberrant DNA methylation in CCA has been reported by several investigators, little is known regarding the associations between them. In the present study, the results obtained from our previously published methylation array were analyzed and 10 candidate genes involved in DNA repair [protein phosphatase 4 catalytic subunit (PPP4C)], apoptosis [runt related transcription factor 3 (RUNX3), interferon regulatory factor 4 (IRF4), ubiquitin C‑terminal hydrolase L1 (UCHL1) and tumor protein p53 inducible protein 3 (TP53I3)], cell proliferation [cyclin D2 (CCND2) and Ras association domain family member 1 (RASSF1)], drug metabolism [aldehyde dehydrogenase 1 family member A3 (ALDH1A3) and solute carrier family 29 member 1 (SLC29A1)] and angiogenesis [human immunodeficiency virus‑1 tat interactive protein 2 (HTATIP2)] were selected for quantification of their methylation levels in 54 CCA and 19 adjacent normal tissues using methylation‑sensitive high‑resolution melting. The associations between the methylation status of the individual genes and clinical parameters were statistically analyzed. High methylation levels were observed in UCHL1, IRF4, CCND2, HTATIP2 and TP53I3. The median methylation level of UCHL1 was 57.3% (range, 3.15 to 88.7%) and HTATIP2 was 13.6% (range, 7.5 to 36.7%). By contrast, low methylation of HTATIP2 and UCHL1 was identified in adjacent normal tissues. The methylation status of HTATIP2 and UCHL1 was associated with patients' overall survival. CCA patients with high methylation of HTATIP2 and low methylation of UCHL1 exhibited longer overall survival. In addition, multivariate Cox regression analysis demonstrated that UCHL1 methylation was an independent factor for CCA with hazard ratio of 1.81 (95% confidence interval, 1.01‑3.25) in high methylation group. The combination of HTATIP2 and UCHL1 methylation status strongly supported their potential predictive biomarker in which patients with CCA who had high methylation of HTATIP2 and low methylation of UCHL1 showed longer overall survival than those with low HTATIP2 methylation and high UCHL1 methylation. In conclusion, the present study revealed the value of aberrant DNA methylation of HTATIP2 and UCHL1, which may serve as a potential predictive biomarker for CCA.

TIP30 regulates lipid metabolism in hepatocellular carcinoma by regulating SREBP1 through the Akt/mTOR signaling pathway

Lipid reprogramming has been considered as a crucial characteristic in hepatocellular carcinoma (HCC) initiation and progression. However, detailed molecular mechanisms have yet to be clearly defined. Here, we examined the effects of tumor suppressor TIP30 on the regulation of HCC lipid metabolism. We found that decreased TIP30 expression leads to elevated fatty acid synthesis and enhanced levels of lipogenic enzymes SCD and FASN in HCC cells. Moreover, SREBP1 is one of the key transcription factors regulating liver lipid metabolism, and TIP30 deficiency significantly increased SREBP1 expression and nuclear accumulation. Small interfering RNAs targeting SREBP1 could reverse fatty acid synthesis induced by TIP30 deficiency. Furthermore, downregulating TIP30 activated the Akt/mTOR signaling pathway to upregulate SREBP1 expression, which promoted lipid metabolism by activating gene transcription of lipogenesis, including fasn and scd. We also showed that TIP30 deficiency-regulated lipid metabolism promoted proliferation of HCC cells. Clinically, our data revealed that TIP30 expression significantly correlated with SREBP1 in patients with HCC and that a combination of TIP30 and SREBP1 is a powerful predictor of HCC prognosis. Together, our data suggested a novel function of TIP30 in HCC progression and indicate that TIP30 regulation of SREBP1 may represent a novel target for HCC treatment.

MCM2 and TIP30 are prognostic markers in squamous cell/adenosquamous carcinoma and adenocarcinoma of the gallbladder

The clinicopathological and biological characteristics of squamous cell/adenosquamous carcinoma (SC/ASC) of the gallbladder remain to be fully elucidated, due to the fact that it is a rare gallbladder cancer subtype. In the current study, the expression of minichromosome maintenance complex component 2 (MCM2) and HIV‑1 tat interactive protein 2 (TIP30) was measured in 46 cases of SC/ASC and 80 adenocarcinomas (AC) using immunohistochemistry. Positive MCM2 and negative TIP30 expression were significantly associated with large tumor size, high TNM stage, invasion, lymph node metastasis and lack of surgical curability in SC/ASC and AC. Positive MCM2 and negative TIP30 expression were significantly associated with poor differentiation in AC, whereas only MCM2 was correlated with differentiation in SC/ASC. Univariate Kaplan‑Meier analysis demonstrated that positive MCM2 and negative TIP30 expression, the degree of differentiation, tumor size, TNM stage, invasion, lymph node metastasis and surgical curability were significantly associated with post‑operative survival in patients with SC/ASC and AC. Multivariate Cox regression analysis demonstrated that positive MCM2 and negative TIP30 expression, the degree of differentiation, tumor size, TNM stage, invasion, lymph node metastasis and lack of surgical curability were also independent predictors of poor prognosis in patients with SC/ASC and AC. These data suggest that positive MCM2 and negative TIP30 expression are closely correlated with the clinical, pathological and biological parameters, in addition to poor prognosis in patients with gallbladder cancer.

TIP30: A Novel Tumor-Suppressor Gene

TIP30/CC3 was first identified and characterized as a "candidate" tumor-suppressor gene in 1997. Recently, the TIP30 tumor-suppressor status has been fully established since several studies have described that TIP30 protein expression is frequently downregulated in diverse types of human tumors, and the downregulation is often associated with tumor progression. TIP30 is involved in the control of cell apoptosis, growth, metastasis, angiogenesis, DNA repair, and tumor cell metabolism. Moreover, TIP30(-/-) mice spontaneously develop hepatocellular carcinoma and other tumors at a higher incidence than that of wild-type mice. In this review, we provide an overview of current knowledge concerning the role of TIP30 in tumor development and progression. To our knowledge, this is the first review about the role of novel tumor-suppressor gene TIP30 in tumor development and progression.

Association of TIP30 expression and prognosis of hepatocellular carcinoma in patients with HBV infection

Altered expression of TIP30, a tumor suppressor, has been observed in many cancers. In this study, we have evaluated the expression of TIP30 in the tissues of 209 hepatocellular carcinomas (HCC) and their adjacent tissues by using a high‐density tissue microarray, and analyzed its correlation with the clinical pathological parameters of the patients. The results revealed negative or weak expression of TIP30 in 43.5% (91/209) of the HCC tissues, and in only 27% (56/209) of the adjacent tissues. The expression level of TIP30 in HCC was inversely correlated with serum alpha‐fetoprotein (AFP) levels, HBV infection, and tumor differentiation. Multivariate analysis for survival indicated that serum HBV infection was the most significant predictor of poor prognosis in HCC (P = 0.0023), and TIP30 expression and tumor differentiation were also independent indicators in this respect (P = 0.0364 and P = 0.0397, respectively). Patients with medium or high expression levels of TIP30 (TIP30^++/+++) had a better 5‐year overall survival rate than those with low/negative (TIP30^+/−) expression (P < 0.001). TIP30^+/−/HBV⁺ patients had the worst 5‐year overall survival rate, whereas TIP30^++/+++/HBV⁻ patients had the best. To further explore the correlation between TIP30 and HBV infection in HCC, HBV⁺ hepatoblastoma cell‐line HepG2 2.2.15 and HCC cell‐line Hep3B were used. Upon silencing of HBV, we observed an upregulation of TIP30 and decreased cell proliferation. In the in vivo studies, we found that the mice inoculated with HepG2 2.2.15 cells with HBV silencing had a prolonged tumor latency and a longer life span, as compared to the control mice inoculated with untreated control cells. In conclusion, the results suggest that downregulation of TIP30 may result from HBV infection, and subsequently promotes the progression of HCC.

Overexpression of TIP30 inhibits the growth and invasion of glioma cells

Glioma is an aggressive malignancy with limited effective treatment and poor prognosis. Therefore, the identification of novel prognostic markers and effective therapeutic targets is important for the treatment of human glioma. TIP30 is a tumor suppressor involved in the regulation of numerous cellular processes, including tumor cell growth, metastasis, and angiogenesis in various human cancers. The present study investigated whether Tat-interacting protein (TIP)30 was able to regulate tumorigenesis and predict the clinical outcome of patients with glioma. A total of 92 human glioma tissue samples and 10 normal brain tissue samples were examined by immunostaining. The results indicated that the expression levels of TIP30 significantly decreased in glioma tissue samples. as compared with normal brain tissue samples. Furthermore, TIP30 expression was inversely correlated with tumor histological classification, pathological grade, tumor size, and epidermal growth factor receptor (EGFR) expression; however, no association was detected between TIP30 expression and patient age and gender. In addition, patients with positive TIP30 expression exhibited significantly longer median overall survival rates, as compared with those with negative TIP30 expression. In vitro experiments revealed that upregulation of TIP30 expression by lentiviral vector transfection inhibited cell growth and induced cell apoptosis, as determined by MTT assay and Annexin V-fluorescein isothiocyanate staining, respectively. In addition, TIP30 expression markedly attenuated cell migration and invasion, as determined by wound healing and transwell assays. Upregulation of TIP30 expression in glioma cells decreased the expression levels of EGFR and its associated downstream molecules phosphorylated extracellular signal-regulated kinases (ERK) and phosphorylated AKT, as determined by western blot analysis. The results of the present study indicated that TIP30 may suppress oncogenesis and glioma progression, thereby improving the prognosis of patients with glioma. Therefore, TIP30 may prove useful as a prognostic biomarker, and as a potential target for glioma therapy.

The combination of HTATIP2 expression and microvessel density predicts converse survival of hepatocellular carcinoma with or without sorafenib

Our previous studies have demonstrated that sorafenib can promote the dissemination of hepatocellular carcinoma (HCC) through downregulation of HTATIP2, a suppressor of tumor growth and metastasis that is associated with inhibition of angiogenesis. Here, we investigated the predictive values of the HTATIP2 level and microvessel density (MVD) with or without sorafenib administration for HCC. Three independent cohorts were included. Using tissue microarray, we assessed the relationship between HTATIP2 expression/MVD and overall survival. The results showed that high HTATIP2 expression and a low MVD value were independent protective prognostic factors after curative HCC resection (297 cases/cohort 1); however, both parameters were converted to independent negative prognostic indicators for patients with postsurgical sorafenib treatment (69/143 cases/cohort 2; P<0.05 for all). This same relationship was observed in patients that received sorafenib treatment for advanced HCC (83 cases/cohort 3; efficacy measures and survival analyses, P<0.05 for all). Moreover, the combination of HTATIP2 and MVD had better power to predict patient death and disease recurrence (P<0.001 for both). We conclude that the combination of HTATIP2 and MVD predicts the converse survival of HCC with or without sorafenib intervention. Our findings can assist in the selection of candidates for personalized treatment with sorafenib.

Contribution of TIP30 to chemoresistance in laryngeal carcinoma

Laryngeal squamous cell carcinoma (LSCC) is one of the most common carcinomas of the head and neck. Despite advances in diagnosis and treatment, the survival of patients with LSCC has not improved in the past two decades. TIP30, a newly identified tumour suppressor, appears to be involved in multiple processes during tumour development. Here, we investigated the involvement of TIP30 in chemoresistance of LSCC in vitro and in vivo. We showed that TIP30 expression decreased significantly in drug-selected cells (DSCs) of laryngeal carcinoma. Suppressing TIP30 enhanced resistance capability to multiple chemotherapy drugs, cell proliferation and self-renewal in Hep2 cells. Additionally, decreased self-renewal capacity and chemotherapeutic resistance were observed in DSCs overexpressing TIP30. Furthermore, TIP30 negatively regulated tumourigenesis and chemoresistance in LSCC cells subcutaneously transplanted into nude mice. Moreover, decreased TIP30 expression contributed to chemoresistance, self-renewal and proliferation of LSCC cells via nuclearlisation of β-catenin, a cell–cell adhesion and stem cell renewal regulator. Consistently, Kaplan–Meier and Cox proportional hazards regression modelling analyses showed that decreased TIP30 expression independently predicted poor survival in patients with LSCC. Taken together, our results reveal that TIP30 has a crucial role in chemoresistance of LSCC through the AKT/glycogen synthase kinase-3β/β-catenin signalling pathway and may be a promising candidate for improving LSCC chemotherapy.

Decreased TIP30 promotes Snail-mediated epithelial-mesenchymal transition and tumor-initiating properties in hepatocellular carcinoma

The poor prognosis of hepatocellular carcinoma (HCC) is mainly due to tumor recurrence and metastases. Recently, epithelial-mesenchymal transition (EMT) has been implicated in tumor invasion and metastasis. However, the underlying molecular mechanisms are yet to be elucidated. Here, we show that 30-kDa Tat-interacting protein (TIP30), also called CC3, is significantly downregulated during transforming growth factor-β-induced EMT. In our in vitro and in vivo studies, we show that decreased TIP30 expression leads to EMT, as well as enhanced motility and invasion of HCC cells. Also, increased self-renewal ability and chemotherapeutic resistance are observed with TIP30 depletion. Moreover, Snail is one of the key transcription factors promoting EMT, and overexpression of TIP30 greatly decreased nucleic accumulation in Snail through the regulation of intracellular localization. Small interfering RNAs targeting Snail attenuated EMT and tumor-initiating properties induced by TIP30 deficiency. We further confirmed that TIP30 competitively interrupted the interaction of Snail with importin-β2 to block the nuclear import of Snail. Consistently, TIP30 expression significantly correlates with E-cadherin expression in HCC patients. TIP30 or combination of E-cadherin is a powerful marker in predicting the prognosis of HCC. Taken together, our results suggest a novel and critical role of TIP30 involved in HCC progression and aggressiveness.

Decreased TIP30 expression predicts poor prognosis in pancreatic cancer patients

Pancreatic ductal adenocarcinoma (PDAC) is known for its aggressive growth, and is characterized by early tissue invasion and metastasis with poor prognosis. Identifying prognostic markers and delineating the underlying mechanisms that promote progression of PDAC are important for the treatment of pancreatic cancer. TIP30, a newly identified tumor suppressor, appears to be involved in multiple processes during tumor development and metastasis. Here, we investigated the expression of TIP30 in PDAC and its prognostic value in PDAC patients. We examined the expression of TIP30 by immunohistochemistry in tissue microarrays containing 106 surgically resected PDAC. Kaplan-Meier analysis and Cox proportional hazards regression modeling analysis showed that TIP30 expression independently predicted better survival in pancreatectomy patients (p < 0.01). Moreover, decreased TIP30 expression was associated with lymph node metastasis (p < 0.05) and loss of E-cadherin expression (r = 0.329, p < 0.01). Suppression of TIP30 resulted in upregulation of Snail and subsequent downregulation of E-cadherin in SW1990 cells containing high-level of endogenous TIP30. However, in the PANC-1 cells containing low level of endogenous TIP30, suppressing TIP30 caused upregulation of Slug instead of Snail, followed by upregulation of MMP9 rather than E-cadherin. Taken together, our work reveals that decreased TIP30 expression is able to enhance invasion and metastasis of pancreatic cancer cells through upregulation of the Snail family members and may serve as an independent predictor for poor outcomes in PDAC patients.

High serum HTATIP2/TIP30 level in serous ovarian cancer as prognostic or diagnostic marker

BACKGROUND

Human HIV-1 TAT interactive protein 2 (HTATIP2/TIP30) is an evolutionarily conserved gene that is expressed ubiquitously in human tissues and some tumor tissues. This protein has been found to be associated with some gynecological cancers; as such, this study aimed to investigate blood HTATIP2/TIP30 levels in patients with ovarian cancer.

METHODS

Twenty-three women with ovarian cancer and 18 patients with various non-cancerous gynecological complaints (for example, dysfunctional uterine bleeding, fibroids, and urinary incontinence) were included in the study. The pathological diagnosis of ovarian cancer was adenocarcinoma. HTATIP2/TIP30 concentration in the patients' blood samples was determined using ELISA kits.

RESULTS

The HTATIP2/TIP30 level was significantly higher in the cancer group than in the control group (1.84 ± 0.82 versus 0.57 ± 0.13 ng/ml, mean ± SD).

CONCLUSIONS

We demonstrated the potential role of HTATIP2/TIP30 in ovarian cancer for the first time, thereby enlightening future studies targeting HTATIP2/TIP30 in ovarian cancer treatment, diagnosis, and prevention.

Age-specific signatures of glioblastoma at the genomic, genetic, and epigenetic levels

Age is a powerful predictor of survival in glioblastoma multiforme (GBM) yet the biological basis for the difference in clinical outcome is mostly unknown. Discovering genes and pathways that would explain age-specific survival difference could generate opportunities for novel therapeutics for GBM. Here we have integrated gene expression, exon expression, microRNA expression, copy number alteration, SNP, whole exome sequence, and DNA methylation data sets of a cohort of GBM patients in The Cancer Genome Atlas (TCGA) project to discover age-specific signatures at the transcriptional, genetic, and epigenetic levels and validated our findings on the REMBRANDT data set. We found major age-specific signatures at all levels including age-specific hypermethylation in polycomb group protein target genes and the upregulation of angiogenesis-related genes in older GBMs. These age-specific differences in GBM, which are independent of molecular subtypes, may in part explain the preferential effects of anti-angiogenic agents in older GBM and pave the way to a better understanding of the unique biology and clinical behavior of older versus younger GBMs.

Sorafenib down-regulates expression of HTATIP2 to promote invasiveness and metastasis of orthotopic hepatocellular carcinoma tumors in mice

BACKGROUND & AIMS

Antiangiogenic agents can sometimes promote tumor invasiveness and metastasis, but little is known about the effects of the antiangiogenic drug sorafenib on progression of hepatocellular carcinoma (HCC).

METHODS

Sorafenib was administered orally (30 mg · kg(-1) · day(-1)) to mice with orthotopic tumors grown from HCC-LM3, SMMC7721, or HepG2 cells. We analyzed survival times of mice, along with tumor growth, metastasis within liver and to lung, and induction of the epithelial-mesenchymal transition. Polymerase chain reaction arrays were used to determine the effects of sorafenib on gene expression patterns in HCC cells. We analyzed regulation of HIV-1 Tat interactive protein 2 (HTATIP2) by sorafenib and compared levels of this protein in tumor samples from 75 patients with HCC (21 who received sorafenib after resection and 54 who did not).

RESULTS

Sorafenib promoted invasiveness and the metastatic potential of orthotopic tumors grown from SMMC7721 and HCC-LM3 cells but not from HepG2 cells. In gene expression analysis, HTATIP2 was down-regulated by sorafenib. HCC-LM3 cells that expressed small hairpin RNAs against HTATIP2 (knockdown) formed less invasive tumors in mice following administration of sorafenib than HCC-LM3 without HTATIP2 knockdown. Alternatively, HepG2 cells that expressed transgenic HTATIP2 formed more invasive tumors in mice following administration of sorafenib. Sorafenib induced the epithelial-mesenchymal transition in HCC cell lines, which was associated with expression of HTATIP2. Sorafenib regulated expression of HTATIP2 via Jun-activated kinase (JAK) and signal transducer and activator of transcription (STAT)3 signaling. Sorafenib therapy prolonged recurrence-free survival in patients who expressed lower levels of HTATIP2 compared with higher levels.

CONCLUSIONS

Sorafenib promotes invasiveness and the metastatic potential of orthotopic tumors from HCC cells in mice, down-regulating expression of HTATIP2 via JAK-STAT3 signaling.

TIP30 directly binds p53 tumor suppressor protein in vitro

TIP30 (30 kDa HIV-1 TAT-interacting protein), also called HTATIP2 or CC3, is a tumor suppressor protein that acts as an angiogenesis inhibitor. TIP30 blocks nuclear import of the mRNA-binding protein HuR, and thereby promotes the cytoplasmic accumulation of HuR by binding to importin-β, which is known to facilitate the cytoplasm-tonuclear transport of HuR. Accumulation of HuR in the cytoplasm, in turn, enhances the expression of the transcription factor p53, a tumor suppressor that plays an essential role in preserving genome stability and inhibiting cancer growth. In addition to such a post-transcriptional mechanism via which TIP30 increases the p53 level, it has been proposed that TIP30 may regulate p53 protein at the protein level by directly binding to it. In order to investigate the possibility of direct interaction between p53 and TIP30, we have used on three functional regions in p53 and examined their interactions with TIP30 using GST pull-down assay and surface plasmon resonance technique. The results show that that TIP30 binds to the DNA-binding domain and the C-terminal domain of p53.

Analysis of VEGF--a regulated gene expression in endothelial cells to identify genes linked to angiogenesis

Angiogenesis is important for many physiological processes, diseases, and also regenerative medicine. Therapies that inhibit the vascular endothelial growth factor (VEGF) pathway have been used in the clinic for cancer and macular degeneration. In cancer applications, these treatments suffer from a “tumor escape phenomenon” where alternative pathways are upregulated and angiogenesis continues. The redundancy of angiogenesis regulation indicates the need for additional studies and new drug targets. We aimed to (i) identify novel and missing angiogenesis annotations and (ii) verify their significance to angiogenesis. To achieve these goals, we integrated the human interactome with known angiogenesis-annotated proteins to identify a set of 202 angiogenesis-associated proteins. Across endothelial cell lines, we found that a significant fraction of these proteins had highly perturbed gene expression during angiogenesis. After treatment with VEGF-A, we found increasing expression of HIF-1α, APP, HIV-1 tat interactive protein 2, and MEF2C, while endoglin, liprin β1 and HIF-2α had decreasing expression across three endothelial cell lines. The analysis showed differential regulation of HIF-1α and HIF-2α. The data also provided additional evidence for the role of endothelial cells in Alzheimer's disease.

The complex world of oligodendroglial differentiation inhibitors

Myelination is a central nervous system (CNS) process wherein oligodendrocyte-axon interactions lead to the establishment of myelin sheaths that stabilize, protect, and electrically insulate axons. In inflammatory demyelinating diseases such as multiple sclerosis (MS), the degeneration and eventual loss of functional myelin sheaths slows and blocks saltatory conduction in axons, which results in clinical impairment. However, remyelination can occur, and lesions can be partially repaired, resulting in clinical remission. The recruitment and activation of resident oligodendrocyte precursor cells (OPCs) play a critical role in the repair process because these cells have the capacity to differentiate into functional myelinating cells. Mature oligodendrocytes, however, are thought to have lost the capacity to develop new myelin sheaths and frequently undergo programmed cell death in MS. The endogenous capacity to generate new oligodendrocytes in MS is limited, and this is predominantly due to the presence of inhibitory components that block OPC differentiation and maturation. Here, we present an overview of recently identified negative regulators of oligodendroglial differentiation and their potential relevance for CNS repair in MS. Because currently available immunomodulatory drugs for MS mainly target inflammatory cascades outside the brain and fail to repair existing lesions, achieving more efficient lesion repair constitutes an important goal for future MS therapies.

CC3/TIP30 regulates metabolic adaptation of tumor cells to glucose limitation

CC3/TIP30 is a metastasis and tumor suppressor, with reduced or absent expression in a variety of aggressive tumors. Overexpression of CC3 in tumor cells predisposes them to apoptosis in response to different death signals. We found that silencing of CC3 expression does not increase apoptotic resistance of cells. However, it strongly improves survival of tumor cells in response to glucose limitation. HeLa cells with silenced CC3 survive long-term in low glucose, and, in comparison to control HeLa cells, show superior metabolic adaptation to glucose limitation. First, unlike the parental HeLa cells, HeLa with silenced CC3 activate and maintain high levels of mitochondrial respiration that is critical for their ability to thrive in low glucose. Second, silencing of CC3 leads to higher expression levels of mitochondrial proteins in respiration complexes when cells are continuously cultured in limiting glucose. Third, HeLa cells with silenced CC3 maintain higher levels of c-MYC and the M2 isoform of pyruvate kinase in low glucose, contributing to more efficient glycolysis. Fourth, HeLa cells with silenced CC3 fail to fully activate AMPK in response to glucose limitation. Inhibition of AMPK, either pharmacologic or via siRNA, protects control HeLa cells from death in low glucose. The metabolic flexibility acquired by cells after silencing of CC3 could be directly relevant to the development of metastatic and aggressive human tumors that frequently have low or absent expression of CC3.

CC3/TIP30 affects DNA damage repair

Background

The pro-apoptotic protein CC3/TIP30 has an unusual cellular function as an inhibitor of nucleocytoplasmic transport. This function is likely to be activated under conditions of stress. A number of studies support the notion that CC3 acts as a tumor and metastasis suppressor in various types of cancer. The yeast homolog of CC3 is likely to be involved in responses to DNA damage. Here we examined the potential role of CC3 in regulation of cellular responses to genotoxic stress.

Results

We found that forced expression of CC3 in CC3-negative cells strongly delays the repair of UV-induced DNA damage. Exogenously introduced CC3 negatively affects expression levels of DDB2/XPE and p21CIP1, and inhibits induction of c-FOS after UV exposure. In addition, exogenous CC3 prevents the nuclear accumulation of P21CIP in response to UV. These changes in the levels/localization of relevant proteins resulting from the enforced expression of CC3 are likely to contribute to the observed delay in DNA damage repair. Silencing of CC3 in CC3-positive cells has a modest delaying effect on repair of the UV induced damage, but has a much more significant negative affect on the translesion DNA synthesis after UV exposure. This could be related to the higher expression levels and increased nuclear localization of p21CIP1 in cells where expression of CC3 is silenced. Expression of CC3 also inhibits repair of oxidative DNA damage and leads to a decrease in levels of nucleoredoxin, that could contribute to the reduced viability of CC3 expressing cells after oxidative insult.

Conclusions

Manipulation of the cellular levels of CC3 alters expression levels and/or subcellular localization of proteins that exhibit nucleocytoplasmic shuttling. This results in altered responses to genotoxic stress and adversely affects DNA damage repair by affecting the recruitment of adequate amounts of required proteins to proper cellular compartments. Excess of cellular CC3 has a significant negative effect on DNA repair after UV and oxidant exposure, while silencing of endogenous CC3 slightly delays repair of UV-induced damage.

A mouse mammary gland involution mRNA signature identifies biological pathways potentially associated with breast cancer metastasis

Mouse mammary gland involution resembles a wound healing response with suppressed inflammation. Wound healing and inflammation are also associated with tumour development, and a 'wound-healing' gene expression signature can predict metastasis formation and survival. Recent studies have shown that an involuting mammary gland stroma can promote metastasis. It could therefore be hypothesised that gene expression signatures from an involuting mouse mammary gland may provide new insights into the physiological pathways that promote breast cancer progression. Indeed, using the HOPACH clustering method, the human orthologues of genes that were differentially regulated at day 3 of mammary gland involution and showed prolonged expression throughout the first 4 days of involution distinguished breast cancers in the NKI 295 breast cancer dataset with low and high metastatic activity. Most strikingly, genes associated with copper ion homeostasis and with HIF-1 promoter binding sites were the most over-represented, linking this signature to hypoxia. Further, six out of the ten mRNAs with strongest up-regulation in cancers with poor survival code for secreted factors, identifying potential candidates that may be involved in stromal/matrix-enhanced metastasis formation/breast cancer development. This method therefore identified biological processes that occur during mammary gland involution, which may be critical in promoting breast cancer metastasis that could form a basis for future investigation, and supports a role for copper in breast cancer development.

Decreased TIP30 expression promotes tumor metastasis in lung cancer

The HIV Tat-interacting protein (TIP30), also called CC3 or HTIP2, is encoded by Tip30, a putative tumor-suppressor gene located on human chromosome 11p15.1. In this study, we investigated the role of TIP30 in the progression and metastasis of lung cancer. TIP30 expression was analyzed in 206 paired lung cancers and adjacent non-tumor tissues, as well as in 70 matched lymph node metastases using a high-density tissue microarray. Results were compared with the clinicopathologic features of the patients from whom the tissues were taken. Low TIP30 expression levels were found in all 9 cases of small cell lung cancer and in 36.5% (72/197) of non-small cell lung cancer, which were correlated with lymph node metastasis in non-small cell lung cancer and with poor differentiation and advanced stage of tumor cells in squamous cell carcinoma. The immunostaining scores were significantly lower in the metastatic lesions than in the primary lesions. Down-regulation of TIP30 by a short hairpin RNA enhanced cell survival, migration, and invasion through Matrigel in vitro, and promoted lung metastasis and vascularization in nude mice. Further studies revealed that the down-regulation of TIP30 enhanced the expression of osteopontin, as well as matrix metalloproteinase-2 and vascular endothelial growth factor. Our results suggest that the down-regulation of TIP30 promotes metastatic progression of lung cancer, hence it could serve as a potential target for the development of lung cancer therapies.

TIP30 is associated with progression and metastasis of prostate cancer

Tat-interacting protein 30 (TIP30), a transcriptional repressor for ERalpha-mediated transcription, possesses several characteristics of a tumor suppressor in certain human and mouse cells. It is reported that deletion of TIP30 gene preferentially increases tumorigenesis in the female knockout mice. Here, we analyzed TIP30 gene expression in the databases of several DNA microarray studies of human prostate cancer and show that TIP30 is specifically overexpressed in metastatic prostate cancers. We demonstrate that TIP30 nuclear expression is associated with prostate cancer progression and metastasis by immunohistochemical analysis in primary and metastatic prostate cancers. Consistent with these data, we also show that knockdown of TIP30 expression, through use of a short hairpin RNA-expressing plasmid, suppresses the cellular growth of PC3 and LNCaP prostate cancer cells. Ectopic overexpression of TIP30 stimulates metastatic potential of prostate cancer cells in an in vitro invasion assay, whereas knockdown of TIP30 inhibits the prostate cancer cells invasion. Finally, we demonstrate that ectopic overexpression of TIP30 enhances androgen receptor mediated transcription, whereas knockdown of TIP30 results in a decreased transcription activity. These data provide evidence that TIP30 plays a role in prostate cancer progression and that TIP30 overexpression may promote prostate cancer cell growth and metastasis.

Thirty-kilodalton Tat-interacting protein suppresses tumor metastasis by inhibition of osteopontin transcription in human hepatocellular carcinoma

It has been previously demonstrated that the 30-kDa Tat-interacting protein (TIP30) plays an important role in the suppression of hepatocarcinogenesis by acting as a tumor suppressor. Here we report that TIP30 suppresses metastasis of hepatocellular carcinoma (HCC) through inhibiting the transcription of osteopontin (OPN), a key molecule in the development of tumor metastasis. The expression of TIP30 messenger RNA was reverse to that of OPN messenger RNA in HCC cell lines. Ectopic expression of TIP30 greatly suppressed OPN expression, inhibited invasion of HCC cells through extracellular matrix (ECM) and adhesion with fibronectin in vitro, whereas down-regulation of TIP30 by RNA-mediated interference enhanced OPN expression and promoted metastatic abilities of HCC cells in vitro. Moreover, overexpression of TIP30 significantly inhibited the growth and lung metastases of HCC cells in nude mice. In contrast, down-regulation of TIP30 greatly promoted tumor cell growth and metastases in vivo. TIP30 repressed OPN transcription through interaction with Ets-1 and suppressed the transcriptional activity of Ets-1 and synergistic actions of Ets-1 and alkaline phosphatase-1. Thus, TIP30 may act as an Ets-1 modulator and inhibit tumor metastasis through abrogating Ets-1-dependent transcription. Moreover, expression of TIP30 was inversely associated with OPN expression in HCC tissue samples as detected by immunohistochemistry assay.

CONCLUSION

Our results reveal a novel pathway by which OPN and possibly other Ets-1 target genes involved in tumor metastasis are regulated by TIP30 and elucidate a mechanism for metastasis promoted by TIP30 deficiency.

Cloning, expression, purification, and characterization of AmphiTip30, a member of short-chain dehydrogenases/reductases family from the amphioxus Branchiostoma belcheri tsingtauense

In this paper we describe the cloning, expression and identification study of the TIP30 gene from amphioxus (Branchiostoma belcheri). The amphioxus TIP30 cDNA is comprised of 1499 bp and is translated in one open-reading frame to give a protein of 237 amino acids, with a predicted 23 amino acids signal peptide, a 147 bp 5'-UTR and a 638 bp 3'-UTR. A multiple alignment of TIP30 from amphioxus with other known TIP30 sequences shows the conservation of most amino acid residues involved in the peculiar structural domains found within TIP30's. Phylogenetic analysis places AmphiTIP30 at the base of the phylogenetic tree, suggesting that AmphiTIP30 is the archetype of the vertebrate TIP30 genes. We express the amphioxus TIP30 gene in Escherichia coli. driven by T7 promoter. The recombinant amphioxus TIP30 protein was purified by HisTrap affinity column. Subsequently, the binding constant and enzyme activity was mensurated. Western blot and immunohistochemistry analysis confirmed that amphioxus has a native molecular mass of approximately 26 kDa, and TIP30 was strongly expressed in ovary. Finally, the initial function of TIP30 is discussed.

TIP30 mutant derived from hepatocellular carcinoma specimens promotes growth of HepG2 cells through up-regulation of N-cadherin

TIP30 is a tumor suppressor whose expression is altered in human liver, prostate, lung, colon, and breast cancers. Mice lacking TIP30 spontaneously developed hepatocellular carcinomas (HCC) and other tumors at a higher incidence than wild-type mice. Somatic missense mutations in the TIP30 gene were identified in human HCC tissue specimens, which resulted in instability or abnormal cellular distribution of TIP30 protein in cells. Here, we show that TIP30 mutants are able to promote cell growth and invasion and inhibit cisplatin-induced apoptosis in the HCC cell line HepG2 negative for endogenous TIP30. Moreover, one of the TIP30 mutants can dramatically accelerate tumor formation in immunodeficient mice. Analysis of gene expression in HepG2 cells, ectopically expressing either wild-type TIP30 or mutant TIP30, by Affymetrix GeneChip array, real-time quantitative PCR, and Western blotting assays reveals that TIP30 mutants can alter expression of genes involved in the regulation of tumorigenesis. This includes up-regulation of expression of N-cadherin and c-MYC and down-regulation of expression of p53 and E-cadherin. N-cadherin knockdown with small interfering RNA in HepG2 cells expressing mutant TIP30 resulted in a profound reduction in cell viability. Taken together, our data indicate that somatic mutations in the TIP30 gene may abolish its native tumor-suppressor activity and gain oncogenic activities partially through up-regulation of N-cadherin, thereby potentiating the pathogenesis of HCC in patients.

TIP30/CC3 expression in breast carcinoma: relation to metastasis, clinicopathologic parameters, and P53 expression

Metastasis is the most frequent cause of death in patients with breast cancer. Tip30/CC3 gene is a putative metastasis suppressor gene, which was first identified by a differential display analysis of messenger RNA from the highly metastatic human variant small cell lung carcinoma (SCLC) versus less metastatic classic SCLC cell lines. The aim of this study was to analyze the relationship between expression of TIP30/CC3 and clinical prognosis in 87 patients with surgically removed breast carcinoma. Tumor tissues were stained immunohistochemically with anti-TIP30/CC3 antibody. We demonstrated that the expression of TIP30/CC3 was inversely associated with axillary lymph node metastasis (P = .0008) and vascular invasion (P = .0016). Expression of TIP30/CC3 was not correlated with tumor grade, estrogen, progesterone, and P53 expression. Inhibition of TIP30/CC3 expression by RNA-mediated interference greatly enhanced breast cancer cell invasion through the extracellular matrix, whereas overexpression of TIP30/CC3 by adenovirus vector suppressed invasion through the extracellular matrix. These data supported the theory that the expression of TIP30/CC3 had a suppressive function on tumor metastasis. In summary, the decrease in expression of TIP30/CC3 is related to metastasis and may represent a new prognosticator in breast carcinoma.

TIP30 inhibits growth of HCC cell lines and inhibits HCC xenografts in mice in combination with 5-FU

Hepatocellular carcinoma (HCC) is an aggressive cancer with a poor prognosis. The specific cellular gene alterations responsible for hepatocarcinogenesis are not well known. Previous works showed that loss of TIP30, also called CC3, a putative tumor suppressor, increased the incidence of hepatocellular carcinoma in mice, and some clinical samples of human HCC tissues had aberrant expression of TIP30. Here, we report that the introduction of TIP30 by an adenovirus vector into HCC cell lines that had decreased expressions of TIP30 inhibited cell proliferation, decreased anchorage-dependent growth, suppressed invasion through the extracellular matrix, and inhibited tumorigenesis in nude mice. Moreover, exogenous expression of Tip30 sensitized HCC cells to cytotoxic drugs and to apoptosis induced by tumor necrosis factor-related ligands in vitro. Ectopic expression of TIP30 in HCC cells enhanced p53 expression and decreased Bcl-2/Bcl-xL expression. Treatment of nude mice bearing subcutaneously established HCC tumors with a combination of an adenovirus expressing TIP30 and the cytotoxic drug 5-fluorouracil completely suppressed tumor growth and prolonged survival. In conclusion, TIP30 may play an important role in the suppression of hepatocarcinogenesis by acting as a tumor suppressor. Overexpression of TIP30 might be a promising candidate as a treatment for HCC that would increase sensitivity to chemotherapeutic drugs.

Overexpression of CC3/TIP30 is associated with HER-2/neu status in breast cancer

PURPOSE

The human CC3/TIP30 gene is a putative metastasis suppressor gene, based on the results of experimental studies using lung, colon and melanoma cell lines. However, there is very little evidence from studies on clinical material, in support of such a role for the gene. In this study, we evaluated the expression of CC3/TIP30 in human breast cancer tissue and investigated the possible associations with the clinicopathological parameters.

METHODS

Total RNA and proteins were extracted from the frozen breast tumor and matched normal tissues. Evaluation of CC3/TIP30 expression was assessed by reverse transcription (RT)-PCR and reverse phase protein array. Immunohistochemistry of CC3/TIP30 on breast tissue microarrays was also analyzed.

RESULTS

We have found that CC3/TIP30 expression is significantly associated with positive HER-2/neu status at both mRNA (P=0.023) and protein (P=0.016) levels. Immunohistochemical analysis on tissue microarrays also shows a positive correlation between CC3 expression and HER-2/neu status (P=0.0028).

CONCLUSION

Our findings suggest a potential link between the expression of CC3/TIP30 gene and the HER-2/neu oncogene-mediated signal pathway.These findings could not have been predicted from previous experimental studies, and suggest that CC3/TIP30 may play a complex role in breast cancer.

Inhibition of nuclear import by the proapoptotic protein CC3

We report here that the normal cellular protein CC3/TIP30, when in excess, inhibits nuclear import in vitro and in vivo. CC3 binds directly to the karyopherins of the importin beta family in a RanGTP-insensitive manner and associates with nucleoporins in vivo. CC3 inhibits the nuclear import of proteins possessing either the classical nuclear localization signal or the M9 signal recognized by transportin. CC3 also inhibits nuclear translocation of transportin itself. Cells modified to express higher levels of CC3 have a slower rate of nuclear import and, as described earlier, show an increased sensitivity to death signals. A mutant CC3 protein lacking proapoptotic activity has a lower affinity for transportin, is displaced from it by RanGTP, and fails to inhibit nuclear import in vitro and in vivo. Together, our results support a correlation between the ability of CC3 to form a RanGTP-resistant complex with importins, inhibit nuclear import, and induce apoptosis. Significantly, a dominant-negative form of importin beta1 shown previously to inhibit multiple transport pathways induces rapid cell death, strongly indicating that inhibition of nuclear transport serves as a potent apoptotic signal.

TIP30 interacts with an estrogen receptor alpha-interacting coactivator CIA and regulates c-myc transcription

Deregulation of c-myc expression is implicated in the pathogenesis of many neoplasias. Estrogen receptor alpha (ERalpha) can increase the rate of c-myc transcription through the recruitment of a variety of cofactors to the promoter, yet the precise roles of these cofactors in transcription and tumorigenesis are largely unknown. We show here that a putative tumor suppressor TIP30, also called CC3 or Htatip2, interacts with an ERalpha-interacting coactivator CIA. Using chromatin immunoprecipitation assays, we demonstrate that TIP30 and CIA are distinct cofactors that are dynamically associated with the promoter and downstream regions of the c-myc gene in response to estrogen. Both TIP30 and CIA are recruited to the c-myc gene promoter by liganded ERalpha in the second transcription cycle. TIP30 overexpression represses ERalpha-mediated c-myc transcription, whereas TIP30 deficiency enhances c-myc transcription in both the absence and presence of estrogen. Ectopic CIA cooperates with TIP30 to repress ERalpha-mediated c-myc transcription. Moreover, virgin TIP30 knockout mice exhibit increased c-myc expression in mammary glands. Together, these results reveal an important role for TIP30 in the regulation of ERalpha-mediated c-myc transcription and suggest a mechanism for tumorigenesis promoted by TIP30 deficiency.

Angiogenesis in cutaneous melanoma: pathogenesis and clinical implications

Neovacularization is an essential step in the multistage progression of malignant melanoma. The onset of new blood vessel formation is ushered in by the release of VEGF and numerous other angiogenic molecules by the tumor cells. Human melanoma is unique among neoplasms that both avascular (early horizontal growth phase characterized by very slow progression and 99%, 10-year survival) and vascular (late radial and vertical growth phase associated with rapid growth, metastasis and death in many cases), phases are discernible by the naked eye. Although cell biologists have made great strides in unraveling the mechanisms involved in the laying down of tumor vasculature and the factors that inhibit it, clinicians treating melanoma have been rather slow to realize and utilize the full potential of suppressing the tumor blood flow to the best advantage of the patient. We suggest a consorted endeavor by all the melanoma experts across the globe to establish an "angiogenesis database" wherein they pool the blood flow and vascularity information along with Breslow's thickness, Clark's level of invasion, lymphatic and vascular invasion, regression, and outcome of their patients.