Translationally Controlled Tumor Protein Expression Research Articles

Computational evaluation of new homologous down regulators of translationally controlled tumor protein (TCTP) targeted for tumor reversion

The Translationally Controlled Tumor Protein (TCTP) has been investigated for tumor reversion and is a target of cancer therapy. Down regulators which suppress the expression of TCTP can trigger the process of tumor reversion leading to the transformation of tumor cells into revertant cells. The present investigation is a novel protein-protein docking approach to target TCTP by a set of proteins similar to the protein: sorting nexin 6 (SNX6) which is an established down regulator of TCTP. The established down regulator along with its set of most similar proteins were modeled using the PYTHON based software - MODELLER v9.9, followed by structure validation using the Procheck Package. Further TCTP was docked with its established and prospective down regulators using the flexible docking protocol suite HADDOCK. The results were evaluated and ranked according to the RMSD values of the complex and the HADDOCK score, which is a weighted sum of van der Waal's energy, electrostatic energy, restraints violation energy and desolvation energy. Results concluded the protein sorting nexin 6 of Mus musculus to be a better down regulator of TCTP, as compared to the suggested down regulator (Homo sapiens snx6).

TCTP Is a Critical Factor in Shrimp Immune Response to Virus Infection

The translationally controlled tumor protein (TCTP) is an abundant, ubiquitous, and conserved protein which plays important roles in a number of biological processes. In the present study, the TCTP in shrimp Litopenaeus vannamei was analyzed. The TCTP of L.vannamei, a 168-amino-acid polypeptide, shares a high degree of similarity with TCTPs from other species, having two TCTP protein signatures at the 45–55 aa and 123–145 aa motif. The mRNA and protein levels from different tissues were detected with the highest in muscle and the lowest in heart among all examined tissues. In addition, temporal TCTP expression was significantly up-regulated at 16 h and 48 h following infection with white spot syndrome virus (WSSV). Lastly, silencing of TCTP with dsRNA led to a significant increase of WSSV loads. These results provide new insights into the importance of TCTP as an evolutionarily conserved molecule for shrimp innate immunity against virus infection.

The effect of Xuebijing on liver translationally controlled tumor protein expression in Acinetobacter baumannii sepsis rats

To study the effect of Xuebijing on liver expressing translationally controlled tumor protein (TCTP) in Acinetobacter baumannii sepsis rats. Among 42 healthy adult male Wistar rats of clean grade, 6 rats were randomly selected as the control group, others were randomly divided into two groups by the method of random digits table: sepsis group(n=18), Xuebijing group(n=18). Sepsis model was established through intraperitoneal injecting Acinetobacter baumannii suspension, and the Xuebijing injection was administrated through caudal vein 30 minutes later in Xuebijing group. After making model for 6, 12 and 24 hours, 6 rats were randomly selected from sepsis group and Xuebijing group, and then the rats were sacrificed, liver tissue samples were extracted for hematoxylin and eosin (HE) staining. Pathological changes of the liver were observed, and immunohistochemical analysis of liver tissue TCTP expression positive cells and the expression of TCTP in liver cells were detected by Western blotting method. HE staining of liver indicated that it was inflammatory injured in sepsis group, and inflammation decreased in Xuebijing group. Immunohistochemistry results showed that, compared with the control group, TCTP positive cells expression score at 6, 12 and 24 hours in sepsis group were significantly increased (7.33±0.82, 10.67±1.21, 7.67±1.21 vs. 2.50±1.05, all P<0.05). Compared with sepsis group, liver tissue TCTP positive cells expression score at 6, 12 and 24 hours in Xuebijing group (5.83±0.75, 7.50±1.05, 5.67±1.37) were significantly decreased (all P<0.05). Western blotting results showed that, compared with the control group, TCTP expression at 6, 12 and 24 hours in sepsis group were significantly increased (1.94±0.59, 3.20±0.72, 1.96±0.55 vs. 0.93±0.24, all P<0.05); compared with sepsis group, TCTP expression at 6, 12 and 24 hours in Xuebijing group (1.38±0.36, 2.03±0.49, 1.30±0.30) were significantly decreased (all P<0.05). Xuebijing can reduce inflammatory injury in liver of rats with Acinetobacter baumannii sepsis, and its mechanism may be associated with reduced hepatic cells expressed TCTP.

Immunohistochemical localization of translationally controlled tumor protein in the mouse digestive system

Translationally controlled tumor protein (TCTP) is a housekeeping protein, highly conserved among various species. It plays a major role in cell differentiation, growth, proliferation, apoptosis and carcinogenesis. Studies reported so far on TCTP expression in different digestive organs have not led to any understanding of the role of TCTP in digestion, so we localized TCTP in organs of the mouse digestive system employing immunohistochemical techniques. Translationally controlled tumor protein was found expressed in all organs studied: tongue, salivary glands, esophagus, stomach, small and large intestines, liver and pancreas. The expression of TCTP was found to be predominant in epithelia and neurons of myenteric nerve ganglia; high in serous glands (parotid, submandibular, gastric, intestinal crypts, pancreatic acini) and in neurons of myenteric nerve ganglia, and moderate to low in epithelia. In epithelia, expression of TCTP varied depending on its type and location. In enteric neurons, TCTP was predominantly expressed in the processes. Translationally controlled tumor protein expression in the liver followed porto-central gradient with higher expression in pericentral hepatocytes. In the pancreas, TCTP was expressed in both acini and islet cells. Our finding of nearly universal localization and expression of TCTP in mouse digestive organs points to the hitherto unrecognized functional importance of TCTP in the digestive system and suggests the need for further studies of the possible role of TCTP in the proliferation, secretion, absorption and neural regulation of the digestive process and its importance in the physiology and pathology of digestive process.

TCTP overexpression is associated with the development and progression of glioma

Upregulation of translationally controlled tumor protein (TCTP) has been reported in a variety of malignant tumors. However, the impact of TCTP in glioma remains unclear. The objective of this study was to investigate the expression and prognostic value of TCTP in glioma patients. Western blot analysis was used to characterize the expression patterns of TCTP in 45 glioma and 22 normal brain tissues. Immunohistochemistry on a tissue microarray containing 127 cases of glioma was performed to analyze the association between TCTP expression and clinicopathological features. Compared with normal brain tissues, TCTP expression was significantly higher in glioma tissues (p <0.001). In addition, high TCTP expression in glioma was significantly associated with advanced pathological grade (p = 0.018). Kaplan-Meier analysis showed that patients with glioma and higher TCTP expression tend to have shorter overall survival time (p <0.001). In multivariate analysis, TCTP expression was proved to be an independent prognostic factor for patients with glioma (p <0.001). In conclusion, this study confirmed the overexpression of TCTP and its association with tumor progression in glioma. It also provided the first evidence that TCTP expression in glioma was an independent prognostic factor of patients, which might be a potential diagnostic and therapeutic target of glioma.

Sann-Joong-Kuey-Jian-Tang decreases the protein expression of Mcl-1 and TCTP and increases that of TNF-α and Bax in BxPC-3 pancreatic carcinoma cells

Sann-Joong-Kuey-Jian-Tang (SJKJT), a traditional Chinese medicinal prescription, has been used for the treatment of lymphadenopathy and solid tumors, and has shown therapeutic potential in several human malignant tumor cell lines. However, the efficacy and molecular mechanisms of action of SJKJT in human pancreatic cancer have not yet been elucidated. In the present study, we evaluated the cytotoxic effects of SJKJT on BxPC-3 human pancreatic carcinoma cells by MTT assay. The protein expression levels of myeloid cell leukemia 1 protein (Mcl-1), translationally controlled tumor protein (TCTP), tumor necrosis factor-α (TNF‑α), caspase-8, caspase-3, Bax and Bcl-2 family in the BxPC-3 cells were measured by western blot analysis. The cell cycle was analyzed by flow cytometry. The protein expression of caspase-3 was also detected by immunocytochemistry (ICC). The results revealed that SJKJT inhibited the proliferation of BxPC-3 cells in a time- and dose-dependent manner. The protein expression levels of TNF-α, caspase-8, caspase-3 and Bax increased in the BxPC-3 cells treated with SJKJT; however, the levels of Mcl-1, TCTP and Bcl-xL decreased. The results also demonstrated that SJKJT increased the percentage of BxPC-3 cells in the sub-G1 phase. In addition, ICC staining indicated that the protein expression of caspase-3 was upregulated in the BxPC-3 cells treated with SJKJT. These findings indicate that SJKJT inhibits the proliferation of BxPC-3 cells through the extrinsic and intrinsic pathway, inducing apoptosis in vitro. Our study, using BxPC-3 human pancreatic cancer cells, demonstrates that SJKJT has potential as a chemotherapeutic agent for the treatment of pancreatic cancer. Further sutdies are warranted to fully elucidate its mechanisms of action.

Sann-Joong-Kuey-Jian-Tang inhibits hepatocellular carcinoma Hep-G2 cell proliferation by increasing TNF-α, Caspase-8, Caspase- 3 and Bax but by decreasing TCTP and Mcl-1 expression in vitro

Hepatic cancer remains a challenging disease and there is a need to identify new treatments. Sann-Joong-Kuey-Jian-Tang (SJKJT), a traditional medicinal prescription, has been used to treat lymphadenopathy and exhibits cytotoxic activity in many types of human cancer cells. Our previous studies revealed that SJKJT is capable of inhibiting colon cancer colo 205 cells by inducing autophagy and apoptosis. However, the effects and molecular mechanisms of SJKJT in human hepatocellular carcinoma have not been clearly elucidated. In the present study we evaluated the effects of SJKJT in human hepatic cellular carcinoma Hep-G2 cells. The cytotoxicity of SJKJT in Hep-G2 cells was measured by MTT assay. The cell cycles were analyzed by fluorescence‑activated cell sorting (FACS). The protein expression of translationally controlled tumor protein (TCTP), Mcl-1, Fas, TNF-α, Caspase-8, Caspase-3 and Bax in Hep-G2 cells treated with SJKJT was evaluated by western blotting. The protein expression of Caspase-3 was also detected by immunofluorescence staining. The results showed that SJKJT inhibits Hep-G2 cells in a time- and dose‑dependent manner. During SJKJT treatment for 48 and 72h, the half-maximum inhibitory concentration (IC50) was 1.48 and 0.94mg/ml, respectively. The FACS results revealed that increased doses of SJKJT were capable of increasing the percentage of cells in the sub-G1 phase. Immunofluorescence staining showed that Hep-G2 treated with SJKJT had increased expression of Caspase-3. The western blot results showed that the protein expression of Fas, TNF-α, Caspase-8, Caspase- 3 and Bax was upregulated, but that of TCTP and Mcl-1 was downregulated in Hep-G2 cells treated with SJKJT. In conclusion, these findings indicated that SJKJT inhibits Hep-G2 cells. One of the molecular mechanisms responsible for this may be the increased Fas, TNF-α, Caspase-8, Caspase- 3 and Bax expression; another mechanism may be via decreasing TCTP and Mcl-1 expression in order to induce apoptosis.

TCTP increases stability of hypoxia‐inducible factor 1α by interaction with and degradation of the tumour suppressor VHL

The translationally controlled tumour protein (TCTP) plays an important role in maintaining cell proliferation and its high expression is associated with many tumours. The tumour suppressor von Hippel-Lindau protein (VHL) has been shown to function as an E3 ubiquitin ligase. Although great progress has been made, biological roles of these factors and relevant molecular mechanisms remain largely unknown. In this study, we have shown that TCTP specifically binds to VHL through its β domain and competes with hypoxia-inducible factor-1α (HIF1α). TCTP over-expression decreased the protein level of VHL and the inhibition of TCTP expression by miRNA resulted in an increase of the VHL protein level. Moreover, TCTP over-expression promoted the K48-linked ubiquitination of VHL, thus degradation through the ubiquitin-proteasome pathway. In addition, we showed that TCTP increased the protein level of HIF1α, which promoted both vascular endothelial growth factor-hypoxic response element-promoter-driven luciferase reporter and endogenous VEGF expression. These data have demonstrated that TCTP binds to the β domain of VHL through competition with HIF1α, which promotes VHL degradation by the ubiquitin-proteasome system and HIF1α stability.

Targeting TCTP as a New Therapeutic Strategy in Castration-resistant Prostate Cancer

Heat shock protein 27 (Hsp27) is highly overexpressed in castration-resistant prostate cancer (CRPC) and an antisense inhibitor (OGX-427) is currently in phase II clinical trials. In order to understand mechanisms of action of Hsp27 and find new therapeutic targets specific of CRPC, we screened for Hsp27 client proteins. Here, we report that translationally controlled tumor protein (TCTP) is a new Hsp27 client protein involved in Hsp27 cytoprotection. We found that TCTP expression is absent or weak in normal prostate cells, moderately expressed in 18.5% of treatment naive PC, and becomes uniformly and strongly expressed in 75% of CRPC. To define TCTP function, we developed and worldwide patented a TCTP antisense oligonucleotide (ASO). Interestingly, we found that CRPC progression correlates with TCTP overexpression and loss of P53. TCTP knockdown restored P53 expression and function, suggesting that castration-sensitivity is directly linked to P53 expression. Collectively, these findings provide a new Hsp27 cytoprotection mechanism in CRPC, and preclinical proof-of-concept that combining ASO-mediated TCTP knockdown with castration and/or docetaxel therapy could serve as a novel strategy to treat CRPC, with no or little toxicity for normal prostate cells.

Inverse relationship between TCTP/RhoA and p53/ /cyclin A/actin expression in ovarian cancer cells

The translationally controlled tumor protein (TCTP) plays a role in cell growth, cell cycle and cancer progression. TCTP controls negatively the stability of the p53 tumor suppressor protein and interacts with the cellular cytoskeleton. The deregulation of the actin and cytokeratin cytoskeleton is responsible for the increased migratory activity of tumor cells and is linked with poor patient outcome. Recent studies indicate that cyclin A,a key regulator of cell cycle, controls actin organization and negatively regulates cell motility via regulation of RhoA expression. We studied the organization of actin and cytokeratin cytoskeleton and the expression of TCTP, p53,cyclin A, RhoA and actin in HIO180 non-transformed ovarian epithelial cells, and OVCAR3 and SKOV3 (expressing low level of inducible p53) ovarian epithelial cancer cells with different metastatic potential. Immunostaining and ultrastructural analyses illustrated a dramatic difference in the organization of the cytokeratin and actin filaments in non-transformed versus cancer cell lines. We also determined that there is an inverse relationship between the level of TCTP/RhoA and actin/p53/cyclin A expression in ovarian cancer cell lines. This previously unidentified negative relationship between TCTP/RhoA and actin/p53/cyclin A may suggest that this interaction is linked with the high aggressiveness of ovarian cancers.

Inverse relationship between TCTP/RhoA and p53/ /cyclin A/actin expression in ovarian cancer cells

The translationally controlled tumor protein (TCTP) plays a role in cell growth, cell cycle and cancer progression. TCTP controls negatively the stability of the p53 tumor suppressor protein and interacts with the cellular cytoskeleton. The deregulation of the actin and cytokeratin cytoskeleton is responsible for the increased migratory activity of tumor cells and is linked with poor patient outcome. Recent studies indicate that cyclin A,a key regulator of cell cycle, controls actin organization and negatively regulates cell motility via regulation of RhoA expression. We studied the organization of actin and cytokeratin cytoskeleton and the expression of TCTP, p53,cyclin A, RhoA and actin in HIO180 non-transformed ovarian epithelial cells, and OVCAR3 and SKOV3 (expressing low level of inducible p53) ovarian epithelial cancer cells with different metastatic potential. Immunostaining and ultrastructural analyses illustrated a dramatic difference in the organization of the cytokeratin and actin filaments in non-transformed versus cancer cell lines. We also determined that there is an inverse relationship between the level of TCTP/RhoA and actin/p53/cyclin A expression in ovarian cancer cell lines. This previously unidentified negative relationship between TCTP/RhoA and actin/p53/cyclin A may suggest that this interaction is linked with the high aggressiveness of ovarian cancers.

Expression of translationally controlled tumor protein in squamous cell carcinoma tissue and cell lines A431 and SCL-1

Objective To detect the expression of translationally controlled tumor protein (TCTP) in squamous cell carcinoma (SCC) tissue and cell lines A431 and SCL-1,and to evaluate the effect of TCTP on apoptosis in and proliferation of SCC cells.Methods An immunohistochemical method was used to measure the expression of TCTP in tissue specimens from 65 patients with SCC.Western blot was performed to detect the expression of TCTP in A431 and SCL-1 cells.Three small interference RNAs (siRNAs) targeting the TPT1 gene were designed,synthesized,and transfected into A431 cells.Then,reverse transcription (RT)-PCR and Western blot were conducted to measure the expression of TPT1 mRNA and TCTP,respectively,methyl thiazolyl tetrazolium (MTT) assay and flow cytometry were carried out to detect cell proliferation and apoptosis,respectively.Results TCTP was overexpressed in SCC tissue specimens,and the expression level was positively correlated with the histologic grading of SCC (P ＜ 0.05).Western blot showed that TCTP was expressed in both A431 and SCL-1 cells,and the expression was relatively high in A431 cells.The transfection efficiency of siRNAs varied from 90％ to 95％.A decrease in the expression of TPT1 mRNA and TCTP was induced by the siRNAs in A375 cells (all P ＜ 0.05).Conclusion The downregulation of TCTP expression may increase the apoptosis in and suppress the proliferation of A431 cells. Key words: TCTP; Neoplasms, squamous cell; RNA interference

500 Translationally Controlled Tumor Protein (TCTP) Revealed by Proteomic Analysis of Patient-Specific Blood outgrowth Endothelial Cells in Heritable Pulmonary Arterial Hypertension

BACKGROUND: Pulmonary arterial hypertension (PAH) is a lethal disease, characterized by excessive proliferation of pulmonary vascular cells. Hereditary PAH is mainly caused by “lossof-function” mutations in the bone morphogenetic protein type II receptor (Bmpr2). However, the mechanisms by which these mutations cause PAH remain unclear. AIM: To identify dysregulated proteins in blood-derived endothelial cells of PAH patients with Bmpr2 mutations compared with healthy controls that may contribute to the pathogenesis of this disease. METHODS: Blood-outgrowth endothelial cells (ECs) were expanded ex vivo from peripheral blood mononuclear cell samples of four patients with heritable PAH and four healthy subjects. Protein isolates were subjected to 2D gel electrophoresis and stained for total proteins with Sypro Ruby. Gels were scanned and subjected to quantitative computer-assisted analysis (PDQuest software) and differentially regulated proteins determined by statistical tests (p-value 0.05) were identified by mass spectrometry (LC-MS/MS). RESULTS: Of the 416 proteins detected, 11 were significantly downregulated in PAH cells, including proteins in pathways previously implicated in PAH (i.e. PKA and guanine nucleotide-binding protein). 11 proteins were significantly upregulated, including a number of cell growth regulatory proteins, notably translationally controlled tumor protein (TCTP). TCTP has previously been shown to be enriched in EC apoptotic nanovesicles and to mediate pro-survival signaling in adjacent cells. Increased expression of TCTP in PAH compared to healthy control cells was demonstrated in patient-derived blood outgrowth ECs in vitro. In addition, the potential role of TCTP in PAH was studied in vivo in the SU5416 (SU) rat model of severe, angioproliferative PAH. SU is a VEGFR2inhibitor which induces EC apoptosis followed by reactive pulmonary vascular cell proliferation causing obliterative pulmonary vascular lesions closely mimicking the human condition. Immunofluorescence staining revealed high expression of TCTP in arteriolar ECs of PAH lungs tightly localized to proliferating cells within occlusive intimal lesions; whereas, only minimal TCTP expression was seen in vascular ECs of normal lungs. CONCLUSIONS: Bmpr2 mutant ECs exhibited dysregulation of key proteins controlling vasodilation and EC growth. TCTP could play an important role in PAH, possibly mediating prosurvival signaling in smooth muscle cells in response to EC apoptosis and thereby contributing to the process of pulmonary vascular remodeling. CIHR, FRQS, Cambridge NIHR Biomedical Research Centre, UK

Translationally Controlled Tumour Protein (TCTP) is present in human cornea and increases in herpetic keratitis

BackgroundTranslationally Controlled Tumour protein is a multifunctional calcium binding protein which has an important role in apoptosis, calcium levels balance and immunological response. The aim of this study was to evaluated the presence and distribution of TCTP in healthy human corneas and to identify and characterize the presence and distribution of this protein in human normal cornea. Since recent studies suggest that apoptosis, calcium levels and immunological mechanisms play a role in the pathogenesis of herpetic stromal keratitis, we studied TCTP expression in this disease.MethodsWe evaluated the expression of TCTP at both RNA messanger and protein level by using reverse transcriptase analysis, immunoblotting and immunohistochemistry in 10 healthy samples cornea: four obtained after penetrating keratoplasty and six from eyes enucleated for other pathologies. Finally, we analysed by immunohistochemistry ten paraffin-embedded samples of Herpes simplex virus keratitis collected at Siena Department of Human Pathology and Oncology: 5 had clinically quiescent disease and 5 had active corneal inflammation.ResultsReverse transcriptase and immunoblotting demonstrated TCTP expression in cornea as a 22,000 Da molecular weight band corresponding to the molecular weight of this protein. Immunohistochemically, all the layers of normal corneal epithelium showed TCTP cytoplasmic expression. TCTP was, also, observed in keratocytes and in the endothelium. In Herpes simplex virus keratitis samples, strong expression of TCTP was evident in stromal cells, in the inflammatory infiltrate and in neo-vessels.ConclusionsIn this preliminary study we demonstrated, for the first time, the presence of TCTP in human cornea, suggesting a potential role in the pathogenesis of herpes virus keratitis.Virtual SlidesThe virtual slide(s) for this article can be found here: http://www.diagnosticpathology.diagnomx.eu/vs/3306813447428149

Expression and localization of translationally controlled tumor protein in rat urinary organs

This study describes the very first assessment of the expression and localization of translationally controlled tumor protein (TCTP) in adult rat urinary organs. TCTP expression levels in kidneys, urinary bladder, and urethra were evaluated by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) and Western blotting, and its cellular localization was examined immunohistochemically in paraffin sections of various urinary organs. TCTP was found in all urinary organs. Its expression was high in the urethra and low in the bladder. TCTP was localized in glomerular podocytes, epithelium of proximal and distal renal tubules, in the loop of Henle, and in the transitional epithelium of the bladder and urethra, mostly in basal cell layers). The subcellular localization of TCTP in these urinary organs was cytoplasmic. These findings suggest that TCTP may be involved in urine formation and excretion.

Abstract 541: Cadmium activates translationally controlled tumor protein (TCTP) and p38 MAPK as possible pathways for prostate cancer cell aggressiveness

Abstract Cadmium is a known cause of lung cancer, but in the prostate there is conflicting evidence for the role of cadmium as a causative agent in the prostate. Recent lines of evidence however suggest that cadmium overburden is associated with more aggressive prostate cancer. Since cadmium does not appear to cause direct genotoxic damage, its mechanism of action on cancer progression is not clear. Here we address the hypothesis that cadmium activates two key molecules: p38 MAP kinase and Translationally Controlled Tumor Protein (TCTP). The hypothesis was tested in in vitro with PC-3 prostate cancer cells and clinically relevant, sub micro molar concentrations of cadmium at various time points. Activation of p38 MAPK was analyzed using phospho- specific antibodies against p38 MAPK by western blot analysis. Results of this study showed that p38 MAPK was phosphorylated within 45 minutes following cadmium treatment. This activation of p38 MAPK by cadmium in PC-3 cells was inhibited TCTP in presence of a p38 MAPK inhibitor (SB203580). This inhibitor also markedly attenuated cadmium-induced invasion and migration of PC-3 cells in Boyden chamber experiments. In addition, our mechanistic studies show that treatment of PC-3 cells with cadmium activated a novel stress related gene, namelyTCTP, which was recently identified as an anti-apoptotic protein and target for tumor reversion process. The cadmium- mediated expression of TCTP in PC-3 cells was confirmed by real time PCR and western blot analysis. From our previous experiments, we know that overexpression of TCTP in LNCaP prostate cancer cells enhanced its migratory rates in a Transwell chamber assay and we are now testing the role of TCTP in cadmium-induced PC-3 cells invasion. Thus, results of our study suggest that TCTP and p38 MAPK may have a prominent role in cadmium mediated cell migration and prostate cancer progression. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 541. doi:1538-7445.AM2012-541

TCTP as a Regulator of Rheb: Impact on mTOR Signaling

TCTP (Translationally Controlled Tumor Protein) is a highly conserved protein that has been suggested as a tumor associated antigen as shown by its deregulation in many different types of cancers. TCTP has been shown to interact with Rheb, a key player of the PI3 Kinase/mTOR signal transduction cascade. This pathway regulates cell growth, cell proliferation, cell motility, cell survival, protein synthesis, and transcription. In this study the contribution of TCTP toward the mTOR pathway was investigated by over‐expression and gene silencing of TCTP in HEK293 and HeLa cells. The role of TCTP as a guanine nucleotide exchange factor (GEF) for Rheb has been controversial and this study highlights potential contribution of TCTP as a regulator of Rheb. Random mutant forms of TCTP were made and over‐expressed in cell lines. Additionally, cells were treated with multiple TCTP siRNAs in a dose and time dependent manner. The effects of TCTP over‐expression and silencing on mTOR signaling were monitored via analysis of S6 phosphorylation and cell viability assays. Results were compared to wild‐type TCTP expression and treatment with non‐specific siRNAs respectively. The impact of TCTP expression on cell viability under serum starved conditions was also explored.This work was supported by a Faculty Development Minigrant to Nitika Parmar.

Association of TCTP with centrosome and microtubules.

Translationally Controlled Tumour Protein (TCTP) associates with microtubules (MT), however, the details of this association are unknown. Here we analyze the relationship of TCTP with MTs and centrosomes in Xenopus laevis and mammalian cells using immunofluorescence, tagged TCTP expression and immunoelectron microscopy. We show that TCTP associates both with MTs and centrosomes at spindle poles when detected by species-specific antibodies and by Myc-XlTCTP expression in Xenopus and mammalian cells. However, when the antibodies against XlTCTP were used in mammalian cells, TCTP was detected exclusively in the centrosomes. These results suggest that a distinct pool of TCTP may be specific for, and associate with, the centrosomes. Double labelling for TCTP and γ-tubulin with immuno-gold electron microscopy in Xenopus laevis oogonia shows localization of TCTP at the periphery of the γ-tubulin-containing pericentriolar material (PCM) enveloping the centriole. TCTP localizes in the close vicinity of, but not directly on the MTs in Xenopus ovary suggesting that this association requires unidentified linker proteins. Thus, we show for the first time: (1) the association of TCTP with centrosomes, (2) peripheral localization of TCTP in relation to the centriole and the γ-tubulin-containing PCM within the centrosome, and (3) the indirect association of TCTP with MTs.

Upregulation of TCTP expression in human skin squamous cell carcinoma increases tumor cell viability through anti-apoptotic action of the protein

The translationally controlled tumor protein (TCTP) is an anti-apoptotic protein, which is highly expressed in several human cancer types. However, the role of TCTP in skin cancers, including squamous cell carcinoma (SCC), has not been investigated. In this study, we analyzed the expression of TCTP in cutaneous SCC samples using immunohistochemistry in two epidermoid SCC cell lines, A431 and SCL-1, using western blot analysis. We further investigated the role of TCTP in skin cancinogenesis by silencing the TPT1 gene using small interfering RNA (siRNA) in the SCC cell line A431. Our results demonstrated that TCTP was overexpressed in cutaneous SCC cells, compared to normal skin keratinocytes. In addition, the expression of TCTP in skin SCC significantly increased with the grade of malignancy. Western blot analysis further confirmed that the expression of TCTP in the cell lines, A431 and SCL-1, was significantly higher compared to that in the normal keratinocyte cell line, HaCaT. The expression of TCTP in A431 cells was significantly downregulated by transfection with our specifically designed TCTP siRNA. We found that downregulation of TCTP expression was associated with decreased cell proliferation and increased apoptosis in A431 cells. These results suggest that the TPT1 gene may be a potential therapeutic target in skin SCC through a siRNA approach.

Expression of translationally controlled tumor protein (TCTP) in the uterus of mice of early pregnancy and its possible significance during embryo implantation

Translationally controlled tumor protein (TCTP) is a highly conserved, growth-related protein. Previous studies showed that TCTP is involved in many biological processes and it is essential for early embryo development and proliferation of embryonic stem cells. However, whether TCTP plays a role during embryo implantation remains unclear. This paper examines the expression and the role of TCTP in the uterus of mice during early pregnancy. The expression of TCTP in the uterus of mice during early pregnancy was examined by quantitative real-time PCR, immunohistochemistry and western blot. A functional study of TCTP in embryo implantation of mice was also performed by intrauterine injection with antisense oligodeoxynucleotides (A-ODNs) of TCTP on day 3 (D3) of pregnancy. The TCTP mRNA levels were significantly upgraded from D3 to D5 of pregnancy and reached maximum levels on D5, then dramatically decreased on D6 and D7. The levels of the TCTP protein detected by western blot were consistent with those of the mRNA. Immunohistochemistry analysis showed that the TCTP protein was mainly located in the luminal and the glandular epithelium on D1 and D2 of pregnancy and reached maximum levels on D5 in the luminal and glandular epithelium and in the stromal cells. The levels of TCTP in the pseudo-pregnant uterus of mice were lower than those of pregnant mice on D4 and D6. Furthermore, inhibiting the TCTP expression by intrauterine injection with A-ODNs of TCTP on D3 of pregnancy significantly reduced the number of the implanted embryos compared with the control. This study demonstrated that TCTP may play a significant role in embryo implantation in mice.