Tip30-induced apoptosis requires translocation of Bax and involves mitochondrial release of cytochrome c and Smac/DIABLO in hepatocellular carcinoma cells

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.

ILP-2: A New Bane and Therapeutic Target for Human Cancers

Inhibitor of apoptosis protein-related-like protein-2 (ILP-2), also known as BIRC-8, is a member of the inhibitor of apoptosis protein (IAPs) family, which mainly encodes the negative regulator of apoptosis. It is selectively overexpressed in a variety of human tumors and can help tumor cells evade apoptosis, promote tumor cell growth, increase tumor cell aggressiveness, and appears to be involved in tumor cell resistance to chemotherapeutic drugs. Several studies have shown that downregulation of ILP-2 expression increases apoptosis, inhibits metastasis, reduces cell growth potential, and sensitizes tumor cells to chemotherapeutic drugs. In addition, ILP-2 inhibits apoptosis in a unique manner; it does not directly inhibit the activity of caspases but induces apoptosis by cooperating with other apoptosis-related proteins. Here, we review the current understanding of the various roles of ILP-2 in the apoptotic cascade and explore the use of interfering ILP-2, and the combination of related anti-tumor agents, as a novel strategy for cancer therapy.

A low serum Tat-interacting protein 30 level is a diagnostic and prognostic biomarker for hepatocellular carcinoma

The present study aimed to evaluate the diagnostic and prognostic value of Tat-interacting protein 30 (HTATIP2/TIP30) levels alone and in combination with α-fetoprotein (AFP) for the evaluation of hepatocellular carcinoma (HCC) patients. ELISA and immunohistochemical measurements on the serum and tissue of HTATIP2/TIP30 protein from HCC patients and normal controls were made. Receiver operating characteristic (ROC) curve analyses of AFP and HTATIP2/TIP30 were performed, as well as logistic regression analysis of APF combined with HTATIP2/TIP30. Log-rank analysis was used to correlate the prognosis with various levels of HTATIP2/TIP30. HTATIP2/TIP30 levels were significantly lower in the HCC group compared with the control group (4.50±2.63 vs. 9.50±2.04 ng/ml, P<0.001). ROC analysis revealed an optimal cut-off point at 7.27 ng/ml HTATIP2/TIP30 for separating the HCC from the control groups. The sensitivity and specificity were 84.6 and 93.7% (P<0.001), respectively. ROC areas of HTATIP2/TIP30 (0.928, P<0.001) were significantly higher than those for AFP (P<0.001). The area under the curve of the HTATIP2/TIP30 and AFP combination was 0.950 (P<0.001). Log-rank tests revealed that the recurrence-free survival time of the group with HTATIP2/TIP30>5.71 ng/ml was significantly higher than that of the control group (P<0.001). This is the first study to demonstrate that HTATIP2/TIP30 levels in serum may be an effective biomarker for the diagnosis and prognosis of HCC.

BLID: A Novel Tumor-Suppressor Gene

BLID (BH3-like motif containing, cell death inducer), also known as breast cancer cell 2 (BRCC2), was first reported in the human breast cancer cell line in 2004. BLID is a BH3-like motif containing apoptotic member of the Bcl-2 family. Recently, the BLID tumor-suppressor roles have been fully established. Several studies have found that BLID is frequently downregulated in many human cancers and the downregulation is often associated with tumor progression. Multivariate analysis indicated that BLID is an independent prognostic factor for overall survival and distant metastasis-free survival. Moreover, BLID can inhibit breast cancer cell growth and metastasis and promote apoptosis. BLID can regulate the expression of various tumor-related genes and proteins, such as AKT and MMP. In this review, we provide an overview of current knowledge concerning the role of BLID in tumor development and progression. To our knowledge, this is the first review about the role of this novel tumor-suppressor gene in tumor development and progression.

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.

MCL-1 is the key target of adjuvant chemotherapy to reverse the cisplatin-resistance in NSCLC

Cisplatin is one of the most effective chemotherapeutic agents for the treatment of lung cancer. However, the acquired resistance occurred in cancer cells limits the clinical application of cisplatin. MCL-1, which is an important member in the pro-survival Bcl-2 family, plays a critical role in multidrug resistance (MDR). The aim of the present study is to investigate the value of Pan-Bcl-2 inhibitor as sensitizer for the chemotherapy of cisplatin-resistant non-small cell lung cancer (NSCLC) cells. We found the obatoclax but not the ABT-737 significantly decreased the IC50 (half maximal inhibitory concentration) of cisplatin in cisplatin-resistant NSCLC cells. Furthermore, we demonstrated that the mechanism of obatoclax-promoted cell death induced by cisplatin was dependent on the inhibition of MCL-1, which couldn't be inhibited by ABT-737 but is the target of obatoclax. Moreover, inhibition of MCL-1 recovered the function of NOXA and BAK in cisplatin-resistant NSCLC cells, leading to the promotion of mitochondrial apoptosis induced by cisplatin. Interestingly, our date indicated the obatoclax also reversed the cross-resistance in cisplatin-resistant NSCLC cells. Therefore, we demonstrated that the targeted therapy with MCL-1 inhibitors, such as obatoclax, may represent a novel strategy for cancer therapy.

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.

Non-additive hepatic gene expression elicited by 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) and 2,2',4,4',5,5'-hexachlorobiphenyl (PCB153) co-treatment in C57BL/6 mice

Interactions between environmental contaminants can lead to non-additive effects that may affect the toxicity and risk assessment of a mixture. Comprehensive time course and dose-response studies with 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), non-dioxin-like 2,2',4,4',5,5'-hexachlorobiphenyl (PCB153) and their mixture were performed in immature, ovariectomized C57BL/6 mice. Mice were gavaged once with 30 μg/kg TCDD, 300 mg/kg PCB153, a mixture of 30 μg/kg TCDD with 300 mg/kg PCB153 (MIX) or sesame oil vehicle for 4,12, 24,72 or 168 h. In the 24h dose-response study, animals were gavaged with TCDD (0.3,1, 3, 6, 10, 15, 30, 45 μg/kg), PCB153 (3,10, 30, 60, 100, 150, 300, 450 mg/kg), MIX (0.3+3, 1+10, 3+30, 6+60, 10+100, 15+150, 30+300, 45 μg/kg TCDD+450 mg/kg PCB153, respectively) or vehicle. All three treatments significantly increased relative liver weights (RLW), with MIX eliciting significantly greater increases compared to TCDD and PCB153 alone. Histologically, MIX induced hepatocellular hypertrophy, vacuolization, inflammation, hyperplasia and necrosis, a combination of TCDD and PCB153 responses. Complementary lipid analyses identified significant increases in hepatic triglycerides in MIX and TCDD samples, while PCB153 had no effect on lipids. Hepatic PCB153 levels were also significantly increased with TCDD co-treatment. Microarray analysis identified 167 TCDD, 185 PCB153 and 388 MIX unique differentially expressed genes. Statistical modeling of quantitative real-time PCR analysis of Pla2g12a, Serpinb6a, Nqo1, Srxn1, and Dysf verified non-additive expression following MIX treatment compared to TCDD and PCB153 alone. In summary, TCDD and PCB153 co-treatment elicited specific non-additive gene expression effects that are consistent with RLW increases, histopathology, and hepatic lipid accumulation.

Astaxanthin protects against MPTP/MPP+-induced mitochondrial dysfunction and ROS production in vivo and in vitro

Astaxanthin (AST) is a powerful antioxidant that occurs naturally in a wide variety of living organisms. We have investigated the role of AST in preventing 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced apoptosis of the substantia nigra (SN) neurons in the mouse model of Parkinson's disease (PD) and 1-methyl-4-phenylpyridinium (MPP+)-induced cytotoxicity of SH-SY5Y human neuroblastoma cells. In in vitro study, AST inhibits MPP+-induced production of intracellular reactive oxygen species (ROS) and cytotoxicity in SH-SY5Y human neuroblastoma cells. Preincubation of AST (50 μM) significantly attenuates MPP+-induced oxidative damage. Furthermore, AST is able to enhance the expression of Bcl-2 protein but reduce the expression of α-synuclein and Bax, and suppress the cleavage of caspase-3. Our results suggest that the protective effects of AST on MPP+-induced apoptosis may be due to its anti-oxidative properties and anti-apoptotic activity via induction of expression of superoxide dismutase (SOD) and catalase and regulating the expression of Bcl-2 and Bax. Pretreatment with AST (30 mg/kg) markedly increases tyrosine hydroxylase (TH)-positive neurons and decreases the argyrophilic neurons compared with the MPTP model group. In summary, AST shows protection from MPP+/MPTP-induced apoptosis in the SH-SY5Y cells and PD model mouse SN neurons, and this effect may be attributable to upregulation of the expression of Bcl-2 protein, downregulation of the expression of Bax and α-synuclein, and inhibition of the activation of caspase-3. These data indicate that AST may provide a valuable therapeutic strategy for the treatment of progressive neurodegenerative disease such as Parkinson's disease.

Expression of TIP30 tumor suppressor gene is down-regulated in human colorectal carcinoma

PURPOSE

Human TIP30 was initially identified as a candidate metastasis suppressor gene whose expression was down-regulated in human liver, lung, breast, and prostate cancers, and recently the role of this gene was examined in colorectal cancer. The aim of this study was to determine the level of TIP30 expression in colorectal carcinoma (CRC).

RESULTS

TIP30 protein levels were lower in colorectal carcinomas compared to normal tissue from the control group (P < 0.001). The frequencies of hypermethylation of TIP30 in tumor were 36%, while there was no aberrant methylation in paired adjacent non-tumor tissue. A statistically significant inverse association was found between TIP30 methylation status and expression of the TIP30 protein in tumor tissues (P = 0.006). Somatic missense mutations in the TIP30 gene were identified in human CRC tissue specimens.

CONCLUSIONS

Our results demonstrate that promoter methylation is involved in the decreased expression of TIP30 tumor suppressor gene in human colorectal carcinoma.