Translationally Controlled Tumor Protein Expression Research Articles

Targeting inhibition of TCTP could inhibit proliferation and induce apoptosis in AML cells

Translationally controlled tumor protein (TCTP) is a highly conserved multifunctional protein, which participates in many important physiological processes. Recently, the roles of TCTP in cell proliferation and apoptosis, especially its close relationship with various tumors, have attracted widespread attention. In this study, we found that the protein level of TCTP was significantly reduced in acute promyelocytic leukemia cell line NB4 transfected with retinoic acid-induced gene G (RIG-G). The RIG-G was found in our previous work as a key mediator of anti-proliferative activity in retinoid/interferon-related pathways. Here, we tried to further explore the function of TCTP in the development of acute myeloid leukemia (AML) from different levels. Our results showed that inhibiting TCTP expression could attenuate AML cells proliferation and induce apoptosis both in AML cell lines and in xenograft of NOD-SCID mice. In addition, either compared with patients in complete remission or non-leukemia patients, we detected that the expression of TCTP was generally high in the fresh bone marrow of AML patients, suggesting that there was a certain correlation between TCTP and AML disease progression. Taken together, our study revealed the role of TCTP in AML development, and provided a potential target for AML treatment.

Elevated translationally controlled tumour protein promotes oral cancer progression and poor outcome.

Translationally controlled tumour protein (TCTP) is a multifunctional protein elevated in multiple cancers. However, studies on its role in oral carcinogenesis and prognosis are rare. We recently reported the role of its interacting partner, MCL1, in oral cancer progression and outcome. Hence, the present study aimed to assess TCTP expression in oral tumorigenesis and its association with patient outcomes alone and in combination with MCL1. TCTP expression was assessed by immunohistochemistry and immunoblotting in oral tissues and cells, respectively. Cell viability post siRNA/dihydroartemisinin treatment was analysed by tetrazolium salt assay. Cell survival, invasion and tumorigenic potential post TCTP knockdown were assessed by clonogenic, Matrigel and soft-agar assays, respectively. The association of TCTP with patient outcome was analysed by Kaplan-Meier and Cox regression. TCTP was significantly overexpressed in oral premalignant lesions (p < 0.0001), oral tumours (p < 0.0001) and oral dysplastic and cancer cells versus normal oral mucosa and also in recurrent (p < 0.05) versus non-recurrent oral tumours. Further, elevated TCTP was significantly (p < 0.05) associated with poor recurrence free survival (RFS) and poor overall survival (OS; hazard ratio = 2.29; p < 0.05). Intriguingly, the high co-expression of TCTP and MCL1 further reduced the RFS (p < 0.05) and OS (p < 0.05; hazard-ratio = 3.49; p < 0.05). Additionally, TCTP knockdown decreased survival (p < 0.05), invasion (p < 0.01) and in vitro tumorigenic potential (p < 0.0001). Dihydroartemisinin treatment reduced TCTP levels and viability of oral cancer cells. Our studies demonstrate an oncogenic role of TCTP in oral cancer progression and poor outcome. Thus, TCTP may be a potential prognostic marker and therapeutic target in oral cancers.

Prognostic value of translationally controlled tumor protein in colon cancer.

The translationally controlled tumor protein (TCTP) is a highly conserved protein involved in a variety of normal cell functions and disease processes. Preclinical studies revealed that TCTP has anti-apoptotic properties, promotes cell growth and division and is involved in cancer progression by promoting invasion and metastasis. The present study explored the potential value of TCTP as a prognostic marker in colon cancer. A retrospective analysis of 74 patients with colon cancer was performed. Using immunohistochemistry, TCTP levels in the primary tumor were assessed semi-quantitatively by the calculation of cytoplasmic and nuclear H-score. Cytoplasmic TCTP levels in the primary tumor had no statistically significant association with disease-free survival (DFS), progression-free survival (PFS) and overall survival (OS) in the present patient population. Patients whose primary tumors had a negative nuclear TCTP expression had significantly improved clinical outcomes. The PFS for the negative nuclear TCTP expression group was 7.7 months [95% confidence interval (CI), 5.8-9.5] compared with 5.5 months (95% CI, 3.2-7.8) in the group with positive nuclear expression (P=0.023, Mantel-Cox log-rank). Patients with a negative nuclear expression of TCTP had a significantly higher median OS (22.2 months; 95% CI, 16.1-28.3) compared with those with positive TCTP nuclear expression (median 13.2 months; 95% CI, 10.1-16.3; P=0.008, Mantel-Cox log-rank). In a multivariate Cox regression model, a positive nuclear TCTP H-score was an independent risk factor for worse PFS and OS. The 1-year OS rate in the group with negative nuclear TCTP expression was 86.3% compared with 56.5% in patients with positive nuclear TCTP expression (P=0.008). The present study suggested that semiquantitative H-score measurement of TCTP levels in the nuclei of tumor cells from the primary tumor is a potential prognostic marker for clinical outcomes in patients with colon cancer.

Sertraline as a potential cancer therapeutic approach: Biological relevance of TCTP in breast cancer cell lines and tumors

PurposeThis study aimed to evaluate the role of Translationally Controlled Tumor Protein (TCTP) in breast cancer (BC) and investigate the effects of sertraline, a serotonin selective reuptake inhibitor (SSRI), on BC cells. The objective was to assess the potential of sertraline as a therapeutic agent in BC treatment by examining its ability to inhibit TCTP expression and exert antitumor effects. Material and MethodsWe utilized five different BC cell lines representing the molecular heterogeneity and distinct subtypes of BC, including luminal, normal-like, HER2-positive, and triple-negative BC. These subtypes play a crucial role in determining clinical treatment strategies and prognosis. ResultsThe highest levels of TCTP were observed in triple-negative BC cell lines, known for their aggressive behavior. Sertraline treatment reduced TCTP expression in BC cell lines, significantly impacting cell viability, clonogenicity, and migration. Additionally, sertraline sensitized triple-negative BC cell lines to cytotoxic chemotherapeutic drugs (doxorubicin and cisplatin) suggesting its potential as an adjunctive therapy to enhance the chemotherapeutic response. Bioinformatic analysis of TCTP mRNA levels in TCGA BC data revealed a negative correlation between TCTP levels and patient survival, as well as between TCTP/tpt1 and Ki67. These findings contradict our data and previous studies indicating a correlation between TCTP protein levels and aggressiveness and poor prognosis in BC. ConclusionsSertraline shows a promise as a potential therapeutic option for BC, particularly in triple-negative BC. Its ability to inhibit TCTP expression, enhance chemotherapeutic response, highlights its potential clinical utility in BC treatment, specifically in triple-negative BC subtype.

Translationally controlled tumor protein as a prognostic marker in metastatic colon cancer.

e15513 Background: The translationally controlled tumor protein (TCTP) is a highly conserved protein present in virtually all eukaryotic organisms. TCTP is involved in a variety of normal cell functions and disease processes. Preclinical studies reveal that TCTP has anti-apoptotic properties, promotes cell growth and division, and is involved in cancer progression by promoting invasion and metastasis. Our study explores the potential value of TCTP as a prognostic marker in metastatic colon cancer. Methods: A retrospective analysis of 54 patients with primary metastatic colon cancer was performed. Using immunohistochemistry, TCTP levels in the primary tumor were assessed semiquantitatively via the calculation of cytoplasmic and nuclear H-score. Results: Cytoplasmic TCTP levels in the primary tumor had no statistically significant association with progression-free survival in first-line therapy (PFS1) and overall survival (OS) in our patient population. Patients whose primary tumors had a negative nuclear TCTP expression had significantly better clinical outcomes. The PFS1 for the negative nuclear TCTP expression group was 7.4 months (95% CI, 5.3-9.6) vs 4.5 months (95% CI, 3.4-5.6) in the group with positive nuclear expression (p = 0.023). Patients with a negative nuclear expression of TCTP had a significantly higher median OS (17.1 months; 95% CI, 13.5–20.6) compared to those with positive TCTP nuclear expression (median 11.5 months; 95% CI, 8.5-14.5) (p = 0.031). In Cox regression analyses, a positive nuclear TCTP H-score conferred a higher risk for worse PFS1 (HR 1.960; 95% CI, 1.086-3.537; p = 0.025) and OS (HR 1.882; 95% CI, 1.050-3.371; p = 0.034). The 1-year OS rate in the group with negative nuclear TCTP expression was 80.0% compared to 47.4% in patients with positive nuclear TCTP expression (p = 0.03). Conclusions: The present study suggests that semiquantitative H-score measurement of TCTP levels in the nuclei of tumor cells from the primary tumor is a potential prognostic marker for clinical outcomes in patients with metastatic colon cancer.

MiR-145-5p inhibits the proliferation of glioma stem cells by targeting translationally controlled tumor protein.

Glioma stem cells (GSCs) have potential for proliferation, self-renewal, and differentiation-the properties that play decisive roles in the process of malignancy in glioma. MicroRNAs (miRNAs) have been shown to regulate the characteristics of cancer stem cells. In this study, we show that miR-145-5p, a recently discovered miRNA, is expressed at low levels in primary GSCs (pGSCs). Upregulation of miR-145-5p resulted in the inhibition of proliferation and increased apoptosis of pGSCs. Furthermore, its overexpression resulted in reduced expression of translationally controlled tumor protein (TCTP). Bioinformatics analysis and luciferase targeting assay revealed that miR-145-5p exerts its effects by directly targeting TCTP. The expression of TCTP was significantly upregulated in pGSCs, and its silencing suppressed the proliferation and increased the apoptosis of pGSCs. Moreover, upregulation of TCTP attenuated the effect of miR-145-5p overexpression on the viability and apoptosis of pGSCs. The results of in vitro studies were corroborated in vivo using an orthotopic mouse model. Taken together, these results suggest that miR-145-5p could be a novel therapeutic target for gliomas through the suppression of TCTP in GSCs.

The involvement of translationally controlled tumor protein during lamb rumen epithelium development

Early weaning is usually applied to improve the reproductive efficiency of sheep in mutton production, while the development of rumen is of vital importance for sheep weaning age. Translationally controlled tumor protein (TCTP) is a highly conserved protein which participates in multiple tissue and organ development. Thus, we hypothesized that TCTP was involved in sheep rumen development. Histological analyses of sheep rumen epithelium showed that the epithelium formed tough shaped papillae without growing from birth to day 15 of age, after which it rapidly developed to functional epithelia on day 45 of age. We then found TCTP expressed in stratum basale, stratum spinosum and stratum granulosum of rumen epithelium. TCTP protein expression remained at a relative low level from day 0 to day 15 of age, it then significantly increased on day 30 (p < 0.05) and gradually decreased until day 60. Furthermore, to explore the role of TCTP in sheep rumen and its regulation, we found the ratio of Ki67 positive cell in stratum basale cells followed the similar pattern as the expression of TCTP. We also found the ratio of acetate:propionate in rumen fluid decreased from day 30 to day 60 of age (p < 0.05). To conclude, our data indicated that TCTP participated in rumen papillae growth by promoting rumen stratum basale cell proliferation.

A novel ligand of the translationally controlled tumor protein (TCTP) identified by virtual drug screening for cancer differentiation therapy

SummaryIntroduction Differentiation therapy is a promising strategy for cancer treatment. The translationally controlled tumor protein (TCTP) is an encouraging target in this context. By now, this field of research is still at its infancy, which motivated us to perform a large-scale screening for the identification of novel ligands of TCTP. We studied the binding mode and the effect of TCTP blockade on the cell cycle in different cancer cell lines. Methods Based on the ZINC-database, we performed virtual screening of 2,556,750 compounds to analyze the binding of small molecules to TCTP. The in silico results were confirmed by microscale thermophoresis. The effect of the new ligand molecules was investigated on cancer cell survival, flow cytometric cell cycle analysis and protein expression by Western blotting and co-immunoprecipitation in MOLT-4, MDA-MB-231, SK-OV-3 and MCF-7 cells. Results Large-scale virtual screening by PyRx combined with molecular docking by AutoDock4 revealed five candidate compounds. By microscale thermophoresis, ZINC10157406 (6-(4-fluorophenyl)-2-[(8-methoxy-4-methyl-2-quinazolinyl)amino]-4(3H)-pyrimidinone) was identified as TCTP ligand with a KD of 0.87 ± 0.38. ZINC10157406 revealed growth inhibitory effects and caused G0/G1 cell cycle arrest in MOLT-4, SK-OV-3 and MCF-7 cells. ZINC10157406 (2 × IC50) downregulated TCTP expression by 86.70 ± 0.44% and upregulated p53 expression by 177.60 ± 12.46%. We validated ZINC10157406 binding to the p53 interaction site of TCTP and replacing p53 by co-immunoprecipitation. Discussion ZINC10157406 was identified as potent ligand of TCTP by in silico and in vitro methods. The compound bound to TCTP with a considerably higher affinity compared to artesunate as known TCTP inhibitor. We were able to demonstrate the effect of TCTP blockade at the p53 binding site, i.e. expression of TCTP decreased, whereas p53 expression increased. This effect was accompanied by a dose-dependent decrease of CDK2, CDK4, CDK, cyclin D1 and cyclin D3 causing a G0/G1 cell cycle arrest in MOLT-4, SK-OV-3 and MCF-7 cells. Our findings are supposed to stimulate further research on TCTP-specific small molecules for differentiation therapy in oncology.

AMG900 as novel inhibitor of the translationally controlled tumor protein

IntroductionCancer is one of the leading causes of death worldwide. Classical cytotoxic chemotherapy exerts high side effects and low tumor selectivity. Translationally controlled tumor protein (TCTP) is a target for differentiation therapy, a promising, new therapeutic approach, which is expected to be more selective and less toxic than cytotoxic chemotherapy. The aim of the present investigation was to identify novel TCTP inhibitors. MethodsWe performed in silico screening and molecular docking using a chemical library of more than 31,000 compounds to identify a novel inhibitor of TCTP. We tested AMG900 in vitro for binding to TCTP by microscale thermophoresis and co-immunoprecipitation. Additionally, we examined the effect of TCTP blockade on cell cycle progression by flow cytometry and Western blotting and cancer cell survival by resazurin assays in MCF-7, SK-OV3 and MOLT-4 cell lines. ResultsWe identified AMG900 as new inhibitor of TCTP. AMG900 bound to the p53 binding site of TCTP with a free binding energy of −9.63 ± 0.01 kcal/mol. This compound decreased TCTP expression to 23.4 ± 1.59% and increased p53 expression to 194.29 ± 24.27%. Furthermore, AMG900 induced G0/G1 arrest as shown by flow cytometry and Western blot of relevant cell cycle proteins. AMG900 decreased CDK2, CDK4, CDK6, cyclin D1 and cyclin D3 expression, whereas p18, p21 and p27 expression increased. Moreover, AMG900 disturbed TCTP-p53 complexation as shown by co-immunoprecipitation and increased expression of free p53. DiscussionAMG900 may serve as novel lead compound for the development of differentiation therapy approaches against cancer.

The mRNA of TCTP functions as a sponge to maintain homeostasis of TCTP protein levels in hepatocellular carcinoma

Translationally controlled tumor protein (TCTP) is a highly conserved protein that accumulated in the tumorigenesis of various malignancies. Despite the important role of TCTP protein in tumor progression, the precise function and underlying mechanistic regulation of TCTP mRNA in hepatocellular carcinoma (HCC) remain unclear. In this study, we found that TCTP protein was overexpressed in HCC patients but TCTP mRNA expression levels were reversed. TCTP knockout HCC cells exhibited attenuated abilities of proliferation, migration, and invasion. The knockdown of TCTP by siRNA effectively reduced TCTP mRNA levels but not protein levels in HCC cells. Moreover, although the constitutive knockdown of TCTP inhibited almost 80% of TCTP protein expression levels in tumors of wildtype transgenic mice (TCTP KD/WT), partial restoration of TCTP protein expression was observed in the tumors of heterozygous TCTP mice (TCTP KD/TCTP±). The blockage of mRNA synthesis with ActD stimulated TCTP protein expression in HCC cells. In contrast, combined treatment with ActD and CHX or MG132 treatment alone did not lead to the TCTP protein accumulation in cells. Furthermore, following the introduction of exogenous TCTP in cells and orthotopic HCC tumor models, the endogenous TCTP protein did not change with the recombinational TCTP expression and kept a rather stable level. Dual-luciferase assays revealed that the coding sequence of TCTP mRNA functions as a sponge to regulate the TCTP protein expression. Collectively, our results indicated that the TCTP mRNA and protein formed a closed regulatory circuit and works as a buffering system to keep the homeostasis of TCTP protein levels in HCC.

TCTP participates in hepatic metabolism by regulating gene expression involved in insulin resistance.

Translationally controlled tumor protein (TCTP) has various cellular functions and molecular interactions, many related to its growth-promoting and antiapoptotic properties. Recently, TCTP expression was reported to increases in insulin-resistant mice fed with high-fat diet. TCTP is a multifunctional protein, but its role in liver metabolism is unclear. Here, we investigated the function and mechanism of TCTP in HepG2 cells. Knock-down of TCTP led to 287 differentially expressed genes (DEGs) that were highly associated with cellular apoptosis and signal response, TNF and NF-κB signaling pathways, glycolysis/gluconeogenesis, insulin resistance, FoxO and insulin signaling pathways, adipocytokine and AMPK signaling pathways. shTCTP downregulated the expression of the key gluconeogenesis enzyme phosphoenolpyruvate carboxykinase (PCK1). Furthermore, TCTP regulated the alternative splicing of genes enriched in the phospholipid biosynthetic process and glycerophospholipid metabolism. We further showed that shTCTP down-regulated the intracellular levels of triglyceride and total cholesterol. Our results showed that TCTP regulates the liver cell transcriptome at both the transcriptional and alternative splicing levels. The TCTP regulatory network predicts the biological functions of TCTP in glucose and lipid metabolism, and also insulin resistance, which may be associated with liver metabolism and diseases such as nonalcoholic fatty liver disease.

Downregulation of transcription factor TCTP elevates microRNA-200a expression to restrain Myt1L expression, thereby improving neurobehavior and oxidative stress injury in cerebral palsy rats

ABSTRACT Transcription factors have already been proposed to work on some human diseases. Yet the role of translationally controlled tumor protein (TCTP) in cerebral palsy (CP) remains elusive. This study intends to examine the mechanism of TCTP on CP by regulating microRNA-200a (miR-200a). CP models of rats were established referring to the internationally recognized improved hypoxic ischemic encephalopathy modeling method. The neuroethology of rats, ultrastructure and pathological condition in brain tissues of rats were observed through several assays. The expression of TCTP, miR-200a, myelin transcription factor 1-like (Myt1L), tyrosine hydroxylase (TH) and inducible nitric oxide synthase (iNOS) along with apoptosis in brain tissues of rats was detected. The levels of reactive oxygen species (ROS), malondialdehyde (MDA), glutathione (GSH), glutathione peroxidase (GSH-Px), superoxide dismutase (SOD), tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6) in brain tissues of rats were determined. The binding site between miR-200a and Myt1L was analyzed. TCTP and Myt1L were overexpressed and miR-200a was under-expressed in CP rats. Elevated miR-200a ameliorated neurobehavior of CP rats and pathological injury in brain tissues. Elevated miR-200a up-regulated TH, GSH, GSH-Px, and SOD levels, down-regulated iNOS, ROS, MDA, TNF-α, and IL-6 levels, and attenuated neuronal apoptosis in brain tissues of CP rats. Myt1L was a target gene of miR-200a. Altogether, our study suggested that diminution of transcription factor TCTP up-regulates miR-200a to limit Myt1L expression, thereby improving neurobehavior and oxidative stress injury in CP rats.

Combination of dihydroartemisinin and resveratrol effectively inhibits cancer cell migration via regulation of the DLC1/TCTP/Cdc42 pathway.

Resveratrol (RES) is a polyphenolic plant antitoxin that increases the level of the tumor suppressor gene deleted in liver cancer 1 (DLC1) to suppress cancer progression. Dihydroartemisinin (DHA), a main active metabolite of anti-malarial drug artemisinin (ART), inhibits cancer cell invasion and migration by decreasing the translationally controlled tumor protein (TCTP), as reported in a few literature studies. Compelling evidence has shown that combination therapy with two or more compounds is more effective than treatment with a compound alone. However, the mechanism of combination of DHA and RES on inhibition of cancer cell migration has not been reported. In this study, our results showed that combination of DHA and RES, compared to each compound alone, synergistically inhibited migration along with the decrease of wound closures and F-actin formation in HepG2 and MDA-MB-231 cancer cells. This combination treatment up-regulated DLC1 and down-regulated TCTP expressions significantly. The two proteins were identified to colocalize in focal adhesions and form a complex. Depletion of DLC1 increased TCTP expression, and transfection with either GFP-DLC1-WT or GFP-DLC1-R718A (GAP-dead mutant) decreased the TCTP level markedly, indicating that DLC1 negatively regulated TCTP in a RhoGAP-independent manner. Furthermore, this combination treatment impeded the migration of HepG2 and MDA-MB-231 cancer cells via Cdc42 regulating JNK/NF-κB and N-WASP signaling pathways, and knockdown of DLC1 obviously increased the levels of Cdc42 and the molecules related to both signaling pathways in MDA-MB-231 cells. The combination also effectively inhibited the growth of xenograft tumors in an avian embryo model. In sum, we reveal a novel combination of DHA and RES that inhibits cancer cell migration by modulating the DLC1/TCTP axis to hinder the Cdc42 related signaling pathway. This combination treatment may be a promising therapeutic strategy to inhibit cancer cell migration by targeting DLC1 and TCTP.

Translationally controlled tumor protein (TCTP) plays a pivotal role in cardiomyocyte survival through a Bnip3-dependent mechanism

Prevention of cardiomyocyte death is an important therapeutic strategy for heart failure. In this study, we focused on translationally controlled tumor protein (TCTP), a highly conserved protein that is expressed ubiquitously in mammalian tissues, including heart. TCTP plays pivotal roles in survival of certain cell types, but its function in cardiomyocytes has not been examined. We aimed to clarify the role of TCTP in cardiomyocyte survival and the underlying mechanism. Here, we demonstrated that downregulation of TCTP with siRNA induced cell death of cardiomyocytes with apoptotic and autophagic features, accompanied with mitochondrial permeability transition pore (mPTP) opening. TCTP loss did not induce cell death of cardiac fibroblasts. Bcl-2/adenovirus E1B 19-kDa interacting protein 3 (Bnip3) was found to mediate the TCTP-loss-induced cardiomyocyte death. In exploring the clinical significance of the TCTP expression in the heart, we found that DOX treatment markedly downregulated the protein expression of TCTP in cultured cardiomyocytes and in mouse heart tissue. Exogenous rescue of TCTP expression attenuated DOX-induced cardiomyocyte death. In mice, cardiomyocyte-specific overexpression of TCTP resulted in decreased susceptibility to DOX-induced cardiac dysfunction, accompanied with attenuated induction of Bnip3. Dihydroartemisinin, a pharmacological TCTP inhibitor, induced development of heart failure and cardiomyocyte death in control mice, but not in mice with cardiomyocyte-specific TCTP overexpression. Our findings revealed TCTP has a pivotal role in cardiomyocyte survival, at least in part through a Bnip3-dependent mechanism. TCTP could be considered as a candidate therapeutic target to prevent DOX-induced heart failure.

A Potential Role for Exosomal Translationally Controlled Tumor Protein Export in Vascular Remodeling in Pulmonary Arterial Hypertension.

Pulmonary arterial hypertension (PAH) is characterized by increased proliferation and resistance to apoptosis of pulmonary vascular cells. Increased expression of translationally controlled tumor protein (TCTP), a prosurvival and antiapoptotic mediator, has recently been demonstrated in patients with heritable PAH; however, its role in the pathobiology of PAH remains unclear. Silencing of TCTP in blood outgrowth endothelial cells (BOECs) isolated from control subjects led to significant changes in morphology, cytoskeletal organization, increased apoptosis, and decreased directionality during migration. Because TCTP is also localized in extracellular vesicles, we isolated BOEC-derived extracellular vesicles (exosomes and microparticles) by sequential ultracentrifugation. BOECs isolated from patients harboring BMPR2 mutations released more exosomes than those derived from control subjects in proapoptotic conditions. Furthermore, TCTP expression was significantly higher in exosomes than in microparticles, indicating that TCTP is mainly exported via exosomes. Coculture assays demonstrated that exosomes transferred TCTP from ECs to pulmonary artery smooth muscle cells, suggesting a role for endothelial-derived TCTP in conferring proliferation and apoptotic resistance. In an experimental model of PAH, rats treated with monocrotaline demonstrated increased concentrations of TCTP in the lung and plasma. Consistent with this finding, we observed increased circulating TCTP levels in patients with idiopathic PAH compared with control subjects. Therefore, our data suggest an important role for TCTP in regulating the critical vascular cell phenotypes that have been implicated in the pathobiology of PAH. In addition, this research implicates TCTP as a potential biomarker for the onset and development of PAH.

Translationally controlled tumor protein affects colorectal cancer metastasis through the high mobility group box 1-dependent pathway.

Recently, accumulating evidence from clinical and experimental researches have suggested that translationally controlled tumor protein (TCTP) and high mobility group box 1 (HMGB1) are implicated in colorectal cancer (CRC) metastasis. However, whether there is an interconnection between these two tumor-promoting proteins and how they affect CRC metastasis remain to be fully elucidated. In the present study, the expression level of TCTP in CRC tissues was assessed by immunohistochemical staining and immunoblotting, and the serum concentration of HMGB1 in patients with CRC was detected by enzyme-linked immunosorbent assay. In vitro, following the modulation of TCTP expression in colon cancer LoVo cells, the translocation behavior of HMGB1 was observed by immunofluorescence assay. Furthermore, the activity of nuclear factor-κB (NF-κB) in LoVo cells was evaluated by immunoblotting and luciferase assay, and the invasion ability of LoVo cells after different treatments was determined using cell invasion assay. In vivo, xenograft tumor model was established and the correlation of TCTP and HMGB1 expression in xenografted tumors was studied by immunohistochemical examination. The results revealed that the expression level of TCTP in CRC tissue and the serum concentration of HMGB1 in patients with CRC were significantly increased, and there was a strong positive correlation between them. In vitro experiments showed that the overexpression of TCTP on LoVo cells resulted in the release of HMGB1 from the nucleus to the cytoplasm and into the extracellular space. In addition, the overexpression of TCTP led to the activation of NF-κB in LoVo cells, and this effect was reversed by treatment with antibodies targeting HMGB1 or to its receptors Toll-like receptor 4 (TLR4) and receptor for advanced glycation end products advanced glycation end products (RAGE). Furthermore, inhibition of the HMGB1-TLR4/RAGE-NF-κB pathway significantly inhibited the TCTP-stimulated invasion of LoVo cells. In vivo experiments demonstrated that the over-expression of TCTP in nude mice promoted the development and spread of xenografted tumors, and concurrently enhanced the expression of HMGB1 in tumor tissues. Collectively, these findings suggested that TCTP promotes CRC metastasis through regulating the behaviors of HMGB1 and the downstream activation of the NF-κB signaling pathway.

Abstract 2905: Deciphering and blocking the mechanisms of cadmium induction of TCTP in prostate cancer cells

Abstract While cadmium is a well-known lung carcinogen, its role in prostate cancer is yet to be understood. Recently, a meta-analysis study showed that cadmium did not increase the risk of prostate cancer. It is not known whether cadmium exposure at environmentally relevant concentrations increases aggressiveness of already existing prostate cancer. Although our lab previously showed that the 75th percentile of cadmium concentration in prostate cancer was associated with biochemical recurrence, more evidence is needed to substantiate this finding. We also showed evidence that cadmium promotes prostate cancer cells migration and invasion via inducing the expression of translationally controlled tumor protein (TCTP). Furthermore, it was demonstrated that cadmium induces the phosphorylation of p38, and that the p38 inhibitor SB203580 (SB) blocks the effects of cadmium on migration and invasion. In this study, we aimed to delineate the signaling events upon cadmium treatment; whether p38 or TCTP is upstream. We addressed this via inhibition of p38 using SB203580 and by inducing TCTP degradation via dihydroartemisinin (DHA) followed by measurement of TCTP expression and phosphorylation of p38 respectively. p38 inhibition led to the increased expression of TCTP on both mRNA and protein levels. Pretreatment with DHA led to less TCTP expression and less phosphorylation of p38. We also aimed to understand the effect of cadmium on cell proliferation, survival and migration. While DHA lowered the colony count and EdU incorporation, cadmium did not alter these functions. In addition, DHA abrogated the cadmium-mediated migration of PC3-Inv prostate cancer cell line. Furthermore, we aimed to determine the effect of nanomolar cadmium concentrations on the phosphorylation of PlK1, which is well established to be upstream of TCTP. Our results demonstrated that nanomolar concentrations of cadmium resulted in increased phosphorylation of PlK1 in both PC3 and LNCaP cells. Altogether, our results suggest that environmentally relevant exposures of cadmium induce TCTP expression through several pathways, and that there is a feedback mechanism between p38 and TCTP. Citation Format: Rama Saad, Gnanasekar Munirathinam, Theresa Kucynda, Marta Ribeiro, Paul Lindholm, Andre Balla. Deciphering and blocking the mechanisms of cadmium induction of TCTP in prostate cancer cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 2905.

Proteomic analysis reveals that pheophorbide a-mediated photodynamic treatment inhibits prostate cancer growth by hampering GDP-GTP exchange of ras-family proteins.

We previously reported that pheophorbide a (PhA), excited by 630 nm light, significantly inhibited the growth of prostate cancer cells. In this study, we employed whole-cell proteomics to investigate photodynamic treatment (PDT)-related proteins. Two-dimensional gel electrophoresis (2-DE) coupled with tandem mass spectrometry was employed to reveal the proteins involved in PhA-mediated PDT in LNCaP and PC-3 prostate cancer cells. After PhA-PDT treatment, decreased expression of translationally-controlled tumor protein (TCTP) was found in both PC-3 and LNCaP whole-cell proteomes. In contrast, human rab GDP dissociation inhibitor (GDI) in LNCaP cells and ras-related homologs GDI in PC-3 cells were up-regulated. GDP-GTP exchange is an underlying target of photodynamic treatment in prostate cancer cells.

Distinct 3' UTRs regulate the life-cycle-specific expression of two TCTP paralogs in Trypanosoma brucei.

ABSTRACTThe translationally controlled tumor protein (TCTP; also known as TPT1 in mammals) is highly conserved and ubiquitously expressed in eukaryotes. It is involved in growth and development, cell cycle progression, protection against cellular stresses and apoptosis, indicating the multifunctional role of the protein. Here, for the first time, we characterize the expression and function of TCTP in the human and animal pathogen, Trypanosoma brucei. We identified two paralogs (TCTP1 and TCTP2) that are differentially expressed in the life cycle of the parasite. The genes have identical 5′ untranslated regions (UTRs) and almost identical open-reading frames. The 3′UTRs differ substantially in sequence and length, and are sufficient for the exclusive expression of TCTP1 in procyclic- and TCTP2 in bloodstream-form parasites. Furthermore, we characterize which parts of the 3′UTR are needed for TCTP2 mRNA stability. RNAi experiments demonstrate that TCTP1 and TCTP2 expression is essential for normal cell growth in procyclic- and bloodstream-form parasites, respectively. Depletion of TCTP1 in the procyclic form cells leads to aberrant cell and mitochondrial organelle morphology, as well as enlarged, and a reduced number of, acidocalcisomes.

Translationally controlled tumor protein (TCTP) is required for TGF-β1 induced epithelial to mesenchymal transition and influences cytoskeletal reorganization

Epithelial-mesenchymal transition (EMT) is a programed course of developmental changes resulting in the acquisition of invasiveness and mobility in cells. In cancer, this course is used by epithelial cells to attain movability. Translationally controlled tumor protein (TCTP) has been extensively characterized following the observation on tumor reversion ensuing its depletion. However, the role of TCTP in cancer progression is still elusive. Here, we demonstrate for the first time that TCTP is a target of transforming growth factor-β1 (TGF-β1), a key regulator of EMT in A549 cells. We here present changes in expression patterns of intermediate filament markers (vimentin and cytokeratin 18a) of EMT following TCTP knockdown or over expression. The TCTP over-expression in cancer cells is associated with mesenchymal characters, while downregulation promotes the epithelial markers in the cells. Interaction of TCTP with β-catenin seems to stabilize β-catenin, preparative to its nuclear localization highlighting a role for β-catenin signaling in EMT. Moreover, the induction of urokinase plasminogen activator (uPA) following ectopic expression of TCTP leads to destabilization of ECM. The cells knocked down for TCTP show diminished invasiveness and migration under TGF-β1 treatment. The present results for the first time demonstrate that TGF-β1 dependent TCTP expression is required for EMT in cells.