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.

A tryptophan-based assay method to search regulatory compounds for transcriptionally controlled tumor protein.

Transcriptionally controlled tumor protein (TCTP) is a highly conserved protein performing a large number of cellular functions by binding with various partner proteins. The importance of its roles in many diseases requires an assay method to find regulatory compounds. However, the molecular characteristics of TCTP made it difficult to search for chemicals interacting with it. In this study, a tryptophan-based assay method was designed and Y151W mutant TCTP was constructed to search binding chemicals. Since there is no tryptophan in the native sequence of TCTP, the incorporation of tryptophan in the Y151W mutant was very effective to establish the method. A flavonoid library was employed to the assay with the method. With the native and Y151W mutant TCTPs, three flavonoids such as morin, myricetin and isobavachalcone have been found to interact with TCTP. Combined with native gel electrophoresis, the binding region of isobavachalcone was suggested to be the flexible loop of TCTP. This approach can be easily applicable to find binding compounds of proteins with similar molecular characteristics of TCTP.

Targeting the translationally controlled tumor protein by a monoclonal antibody improves allergic airway inflammation in mice.

Secretion of translationally controlled tumor protein (TCTP) was found in body fluids during the late phase of allergic reactions, implicating TCTP in allergic diseases. Furthermore, blocking TCTP has been shown to be helpful in treating asthma and allergies in animal models. The objectives of this study were to produce anti-TCTP monoclonal antibodies (mAbs), test their ability to inhibit the cytokine-like function of dimeric TCTP (dTCTP) in vitro and to assess their therapeutic effects in a murine model of ovalbumin (OVA)-induced airway inflammation. We first verified the inhibitory effects of 4 anti-TCTP mAbs on dTCTP-induced secretion of IL-8 in BEAS-2B cells. To investigate the anti-inflammatory effect of anti-TCTP mAbs on allergic airway inflammation, we treated OVA-sensitized mice with anti-TCTP mAbs before OVA challenge. The changes in bronchoalveolar lavage fluid (BALF) cells, IL-4, IL-5, and IL-13 levels in both BALF and lung homogenates, plasma levels of OVA-specific IgE, and lung tissues were analyzed. We found that JEW-M449 anti-TCTP mAb bound to the flexible loop of TCTP and significantly inhibited dTCTP-induced IL-8 release, making it the most effective inhibitor in our study. We also found that treatment with JEW-M449 significantly reduced the infiltration of inflammatory cells and suppressed the OVA-induced upregulation of type 2 cytokines in both BALF and lung homogenates in a dose-dependent manner. In addition, JEW-M449 significantly attenuated the degree of goblet cell hyperplasia and mucus secretion. Our results demonstrate that specific targeting of the flexible loop of TCTP is a potent strategy for treating airway inflammatory diseases.

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

BACKGROUND: 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. METHODS: 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. RESULTS: 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. CONCLUSION: 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.

Structural transitions in TCTP tumor protein upon binding to the anti-apoptotic protein family member Mcl-1.

Translationally Controlled Tumor Protein (TCTP) serves as a pro-survival factor in tumor cells, inhibiting the mitochondrial apoptosis pathway by enhancing the function of anti-apoptotic Bcl-2 family members Mcl-1 and Bcl-xL. TCTP specifically binds to Bcl-xL, preventing Bax-dependent Bcl-xL-induced cytochrome c release, and it reduces Mcl-1 turnover by inhibiting its ubiquitination, thereby decreasing Mcl-1-mediated apoptosis. TCTP harbors a BH3-like motif that forms a ß-strand buried in the globular domain of the protein. In contrast, the crystal structure of the TCTP BH3-like peptide in complex with the Bcl-2 family member Bcl-xL reveals an α-helical conformation for the BH3-like motif, suggesting significant structural changes upon complex formation. Employing biochemical and biophysical methods, including limited proteolysis, circular dichroism, NMR, and SAXS, we describe the TCTP complex with the Bcl-2 homolog Mcl-1. Our findings demonstrate that full-length TCTP binds to the BH3 binding groove of Mcl-1 via its BH3-like motif, experiencing conformational exchange at the interface on a micro- to milli-second timescale. Concurrently, the TCTP globular domain becomes destabilized, transitioning into a molten-globule state. Furthermore, we establish that the non-canonical residue D16 within the TCTP BH3-like motif reduces stability while enhancing the dynamics of the intermolecular interface. In conclusion, we detail the structural plasticity of TCTP and discuss its implications for partner interactions and future anticancer drug design strategies aimed at targeting TCTP complexes.

Inhibitors of dimerized translationally controlled tumor protein, a histamine releasing factor, may serve as anti-allergic drug candidates.

It has been established that translationally controlled tumor protein (TCTP), also called histamine releasing factor (HRF), exhibits cytokine-like activities associated with initiation of allergic responses only after forming dimers (dTCTP). Agents that inhibit dTCTP by preventing its dimerization or otherwise block its function, also block development of allergic reactions, thereby serving as potential drugs to treat allergic diseases. Several lines of evidence have proven that peptides and antibodies that specifically inhibit the interactions between dTCTP and either its putative receptor or immunoglobulins exhibit significant in vivo efficacy as potential anti-inflammatory agents in murine models of allergic inflammatory diseases. This review highlights the development of several inhibitors targeting dTCTP and discusses how they affect the pathophysiological processes of allergic and inflammatory diseases in several animal models and offers new perspectives on anti-allergic drug discovery.

Translationally controlled tumor protein restores impaired memory and altered synaptic protein expression in animal models of dementia.

This study describes the effects of translationally controlled tumor protein (TCTP) on mice with memory impairment caused by scopolamine (SCO) administration. Specifically, memory functions and expression levels of hippocampal synaptic proteins in 7- to 12-month-old SCO-treated wild-type (WT-SCO) mice were compared to those of TCTP-overexpressing (TG) and TCTP knocked-down (KD) mice similarly treated with SCO. Passive-avoidance tasks were performed with WT, TG, and KD mice for four weeks after intraperitoneal injection of SCO or saline followed by an acquisition test. After completing behavioral studies, hippocampi of all mice groups were collected and their synaptic protein contents were subjected to Western blotting or immunohistochemical analyses, and compared with those of 5x familial Alzheimer's disease (5xFAD) mice and postmortem AD patients. Results of passive avoidance tests revealed that SCO-induced memory impairment was repaired in TCTP-TG mice, but not in TCTP-KD mice. Hippocampal expression levels of synaptophysin, synapsin-1, and PSD-95 were increased in TCTP-TG mice treated with SCO (TG-SCO) but decreased in TCTP-KD mice treated with SCO (KD-SCO). Decreased levels of TCTP, synaptophysin, and PSD-95 were also found in hippocampi of 5xFAD mice and AD patients. Expression levels of p-CREB/CREB and brain-derived neurotrophic factor (BDNF) in TCTP-TG and TG-SCO mice were similar to or increased compared to those in WT mice, but decreased in TCTP-KD and KD-SCO mice. BDNF immunoreactivity was restored in CA1 regions of hippocampi of TG-SCO mice, but not in KD-SCO mice. These results suggest that TCTP can restore damaged memory in mice possibly through restored synaptic protein expression.

METTL13 promotes nasopharyngeal carcinoma progression through regulating the ZEB1/TPT1 axis.

BACKGROUND: Globally, nasopharyngeal carcinoma (NPC) is a prevalent and deadly malignancy. Despite the role of methyltransferase like 13 (METTL13) having been highlighted in a majority of human cancers, its function and mechanism in NPC is indistinct. METHODS: The expression level of METTL13 in NPC cell lines and normal cells was detected using a quantitative real-time polymerase chain reaction. Gain- and loss-of function experiments were conducted. Cell counting kit-8, 5-ethynyl-2'-deoxyuridine, wound-healing, Transwell and tube formation assays, respectively, appraised the proliferative, migratory, invasive and angiogenic cellular responses. Corresponding protein expression was measured by western blotting. A chromatin immunoprecipitation assay was applied to verify the association between ZEB1 and the TPT1 promoter. Eventually, to substantiate the critical role of METTL13 in NPC, the establishment of an in vivo tumorigenesis model was accomplished. RESULTS: METTL13 possessed fortified expression in NPC cells. METTL13 silencing markedly suppressed NPC cellular phenotypes in vitro, including proliferative, migratory, invasive and angiogenic events, as well as hindered tumorigenesis in vivo. Additionally, METTL13 positively regulated ZEB1, whereas ZEB1 could bind to TPT1 promoter and transcriptionally regulate TPT1. TPT1 was also found to be upregulated in NPC cells. TPT1 silencing suppressed NPC cellular phenotypes in vitro. TPT1 overexpression partly weakened the anti-tumor effect of METTL13 in NPC. CONCLUSIONS: In summary, METTL13 up-regulated ZEB1, which facilitated the transcriptional activation of TPT1, ultimately promoting NPC growth and metastasis, providing a potential therapeutic strategy for NPC treatment.

Polymorphisms in TPT1 Pathways in Pediatric Astrocytomas.

Central nervous system tumors, especially astrocytomas, are the solid neoplasms with the highest incidence and mortality rates in childhood. The diagnosis is based on histopathological characteristics, but molecular methods have been increasingly used. Translationally controlled tumor protein (TCTP) protein, encoded by the tumor protein, translationally controlled 1 (TPT1) gene, is a multifunctional protein with an important physiological role in the cell cycle. Expression of this protein has been associated with several neoplasms, including astrocytomas in adults. However, the role of this protein in pediatric astrocytomas is largely unknown. We aim to evaluate in cases of pediatric astrocytomas, the frequency of polymorphisms in the TPT1 gene and other genes associated with its molecular pathways, such as MTOR, MDM2, TP53, and CDKN1A, correlating it with protein expression and clinical variables, in formalin-fixed, paraffin-embedded (FFPE) samples. These samples were submitted to genotyping and immunohistochemistry analyses. The most revealing results refer to the MDM2 gene, rs117039649 [G/C], in which C polymorphic allele was observed only in the glioblastomas (p = .028). The CDKN1A gene, rs3176334 [T/C] presented a homozygous polymorphic genotype only in high-grade astrocytomas, when infiltrating tumors were compared (p = .039). The immunohistochemical expression of cytoplasmic MDM2 correlated with better survival rates in patients with glioblastoma (p = .018). The presence of polymorphisms in the MDM2 and CDKN1A genes, as well as a specific correlation between MDM2 expression, suggests a likely association with risk in pediatric astrocytomas. This study sought the probable role involved in the TCTP pathway, and associated proteins, in the tumorigenesis of pediatric astrocytomas, and some could have potential impact as prognostic markers in these patients.

Meclizine, a piperazine-derivative antihistamine, binds to dimerized translationally controlled tumor protein and attenuates allergic reactions in a mouse model.

Translationally controlled tumor protein (TCTP), a highly conserved protein present in most eukaryotes, is involved in numerous biological processes. Only the dimeric form of TCTP (dTCTP) formed during inflammatory conditions exhibits cytokine-like activity. Therefore, dTCTP is considered as a therapeutic target for allergic diseases. Because monomeric TCTP (mTCTP) and dTCTP share a high topological similarity, we hypothesized that small molecules interacting with mTCTP would also bind to dTCTP and interfere with dTCTP-based cellular processes. In this study, nine compounds listed in the literature as interacting with mTCTP were investigated for their ability to suppress the activity of extracellular dTCTP in bronchial epithelial cells. It was found that one of the nine, meclizine, a piperazine-derivative antihistamine, significantly reduced IL-8 release and suppressed the NF-κB pathway. The direct interaction of meclizine with dTCTP was confirmed by surface plasmon resonance (SPR). Also, we found that meclizine can attenuate ovalbumin (OVA)-induced airway inflammation in mice. Therefore, meclizine might be a potential anti-allergic drug as an inhibitor for dTCTP.

Effects of Sarcoptes scabiei Translationally Controlled Tumor Protein (TCTP) on Histamine Release and Degranulation of KU812 Cells.

Scabies is a common parasitic dermatological infection worldwide that is often neglected. Scabies mites stimulate host inflammatory symptoms via secreted and excreted proteins, which induce basophil and mast cell degranulation and host histamine release. However, the mechanism of degranulation and histamine release is unclear. Moreover, the Sarcoptes scabiei translationally controlled tumor protein (TCTP) is predicted as an excreted protein, which may be involved in host inflammatory response regulation. First, we evaluated S. scabiei TCTP gene (SsTCTP) transcription in larvae, nymphs, and adults by qRT-PCR, and SsTCTP transcription was highest in larvae, followed by nymphs. Second, we found that the S. scabiei TCTP recombinant protein (rSsTCTP) promoted mice histamine release in vivo by Evans blue Miles assay. Therefore, to further explore the possible role of S. scabiei TCTP in host inflammatory response regulation, we established a degranulation model of KU812 cells. The results of the degranulation model suggested that rSsTCTP could induce enhanced degranulation of KU812 cells and increase the secretion of histamine and the expression of IL-4, IL-6, and IL-13 in vitro. In conclusion, we speculate that scabies mites could stimulate host histamine release and Th2 response by excreting S. scabiei TCTP.

Histamine-Releasing Factor Is a Novel Alarmin Induced by House Dust Mite Allergen, Cytokines, and Cell Death.

Histamine-releasing factor (HRF) is a multifunctional protein with fundamental intracellular functions controlling cell survival and proliferation. HRF is also secreted during allergic reactions and promotes IgE-mediated activation of mast cells and basophils. In this study, we investigated HRF secretion and its relevance to airway inflammation. HRF monomers were constitutively secreted from BEAS-2B human bronchial epithelial cells (HBECs) and converted to oligomers over the course of culture. Stimulation with house dust mite (HDM) extract increased HRF secretion substantially. Several cytokines involved in asthma pathogenesis showed moderate effects on HRF secretion but dramatically enhanced HDM-induced HRF secretion. HDM-induced HRF secretion from BEAS-2B cells and normal HBECs proceeded via TLR2. Consistent with this, multiple TLR2 ligands, including Der p 2, Der p 5, Der p 13, and Der p 21, induced HRF secretion. Der p 10 (tropomyosin) also promoted HRF secretion. Cell death or incubation with adenosine and ATP, compounds released upon cell death, also enhanced HRF secretion. Furthermore, intranasal administration of recombinant HRF elicited robust airway inflammation in HDM-sensitized mice in an FcεRI-dependent manner. Therefore, we conclude that HRF is a novel alarmin that promotes allergic airway inflammation.

Protein transduction domain of translationally controlled tumor protein: characterization and application in drug delivery.

Our research group reported in 2011 the discovery of a novel cell-penetrating moiety in the N-terminus of the human translationally controlled tumor protein (TCTP). This moiety was responsible for the previously noted membrane translocating ability of purified full-length TCTP. The hydrophobic nature of TCTP-derived protein transduction domain (TCTP-PTD) endowed it with unique characteristics compared to other well-known cationic PTDs, such as TAT-PTD. TCTP-PTD internalizes partly through lipid-raft/caveolae-dependent endocytosis and partly by macropinocytosis. After cell entry, caveosome-laden TCTP-PTD appears to move to the cytoplasm and cytoskeleton except for the nucleus possibly through the movement to endoplasmic reticulum (ER). TCTP-PTD efficiently facilitates delivery of various types of cargos, such as peptides, proteins, and nucleic acids in vitro and in vivo. It is noteworthy that TCTP-PTD and its variants promote intranasal delivery of antidiabetics including, insulin and exendin-4 and of antigens for immunization in vivo, suggesting its potential for drug delivery. In this review, we attempted to describe recent advances in the understanding regarding the identification of TCTP-PTD, the characteristics of its cellular uptake, and the usefulness as a vehicle for delivery into cells of a variety of drugs and macromolecules. Our investigative efforts are continuing further to delineate the details of the functions and the regulatory mechanisms of TCTP-PTD-mediated cellular penetration and posttranslational modification of TCTP in physiologic and pathological processes. This is a review of what we currently know regarding TCTP-PTD and its use as a vehicle for the transduction of drugs and other molecules.

Translationally controlled tumor protein: the mediator promoting cancer invasion and migration and its potential clinical prospects.

Translationally controlled tumor protein (TCTP) is a highly conserved multifunctional protein localized in the cytoplasm and nucleus of eukaryotic cells. It is secreted through exosomes and its degradation is associated with the ubiquitin-proteasome system (UPS), heat shock protein 27 (Hsp27), and chaperone-mediated autophagy (CMA). Its structure contains three α|-helices and eleven ß|-strands, and features a helical hairpin as its hallmark. TCTP shows a remarkable similarity to the methionine-R-sulfoxide reductase B (MsrB) and mammalian suppressor of Sec4 (Mss4/Dss4) protein families, which exerts guanine nucleotide exchange factor (GEF) activity on small guanosine triphosphatase (GTPase) proteins, suggesting that some functions of TCTP may at least depend on its GEF action. Indeed, TCTP exerts GEF activity on Ras homolog enriched in brain (Rheb) to boost the growth and proliferation of Drosophila cells. TCTP also enhances the expression of cell division control protein 42 homolog (Cdc42) to promote cancer cell invasion and migration. Moreover, TCTP regulates cytoskeleton organization by interacting with actin microfilament (MF) and microtubule (MT) proteins and inducing the epithelial-mesenchymal transition (EMT) process. In essence, TCTP promotes cancer cell movement. It is usually highly expressed in cancerous tissues and thus reduces patient survival; meanwhile, drugs can target TCTP to reduce this effect. In this review, we summarize the mechanisms of TCTP in promoting cancer invasion and migration, and describe the current inhibitory strategy to target TCTP in cancerous diseases.

PEGylation improves the therapeutic potential of dimerized translationally controlled tumor protein blocking peptide in ovalbumin-induced mouse model of airway inflammation.

Dimerized translationally controlled tumor protein (dTCTP) initiates a variety of allergic responses in mouse models and that dTCTP-binding peptide 2 (dTBP2) attenuates the allergic inflammation by targeting dTCTP. However, the usefulness of peptide-based drugs is often limited due to their short half-lives, rapid degradation, and high levels of clearance after systemic administration. In this study, we chemically conjugated dTBP2 with 10 kDa polyethylene glycol (PEG) to improve its therapeutic potential. N-terminal mono-PEGylated dTBP2 (PEG-dTBP2) was characterized by in vitro bioactivity assay, pharmacokinetics study, and in vivo efficacy. When compared to the unmodified dTBP2, PEG-dTBP2 reduced proinflammatory cytokine IL-8 secretion in human bronchial cells by 10 to 15% and increased plasma half-life by approximately 2.5-fold in mice. This study specifically demonstrated that PEG-dTBP2 shows higher inhibitory action against ovalbumin (OVA)-induced airway inflammation in mice compared to dTBP2. Importantly, PEG-dTBP2, when administered once at 1 mg/kg, significantly reduced the migration of inflammatory cells and the levels of cytokines in the bronchoalveolar lavage fluids as well as OVA-specific IgE levels in serum. In addition, the degree of goblet cell hyperplasia and mucus secretion were significantly attenuated in the PEG-dTBP2 group compared with the control group. These results suggest that PEG-dTBP2 can be considered a potential candidate drug for regulating allergic inflammation.

Dimeric translationally controlled tumor protein-binding peptide 2 attenuates imiquimod-induced psoriatic inflammation through induction of regulatory T cells.

Psoriasis is a chronic skin inflammation caused by a dysfunctional immune system, which causes systemic inflammation in various organs and tissues. Due to the risk of systemic inflammation and recurrence of psoriasis, it is important to identify the critical targets in the pathogenesis of psoriasis and develop targeted therapeutics. Dimerized translationally controlled tumor protein (dTCTP) promotes immune cell activation as a pro-inflammatory cytokine and plays a role in developing allergic diseases such as asthma and rhinitis. Here, we sought to explore whether dTCTP and its inhibition contributed to the development and control of imiquimod (IMQ)-induced psoriasis. Topical application of IMQ inflamed the skin of the back and ear, increased inflammatory cytokines, and decreased regulatory T cell markers. Interestingly, TCTP was significantly increased in inflamed skin and immune cells such as T cells, B cells, and macrophages after IMQ treatment and was secreted into the serum to undergo dimerization. Extracellular dTCTP treatment selectively suppressed regulatory T (Treg) cells, not other effector T helper (Th) cells, and increased M1 macrophages. Moreover, dTCTP-binding peptide 2 (dTBP2), a dTCTP inhibitor peptide, effectively attenuated the systemic inflammatory responses, including Th17 cell response, and alleviated psoriatic skin inflammation. dTBP2 blocked dTCTP-mediated Treg suppression and stimulated the expression of Treg cell markers in the spleen and inflammatory skin lesions. These results suggest that dTCTP dysregulated immune balance through Treg suppression in psoriatic inflammation and that functional inhibition of dTCTP by dTBP2 maintained immune homeostasis and attenuated inflammatory skin diseases by expanding Treg cells.

TPT1 Supports Proliferation of Neural Stem/Progenitor Cells and Brain Tumor Initiating Cells Regulated by Macrophage Migration Inhibitory Factor (MIF).

One of the key areas in stem cell research is the identification of factors capable of promoting the expansion of Neural Stem Cell/Progenitor Cells (NSPCs) and understanding their molecular mechanisms for future use in clinical settings. We previously identified Macrophage Migration Inhibitory Factor (MIF) as a novel factor that can support the proliferation and/or survival of NSPCs based on in vitro functional cloning strategy and revealed that MIF can support the proliferation of human brain tumor-initiating cells (BTICs). However, the detailed downstream signaling for the functions has largely remained unknown. Thus, in the present study, we newly identified translationally-controlled tumor protein-1 (TPT1), which is expressed in the ventricular zone of mouse embryonic brain, as a downstream target of MIF signaling in mouse and human NSPCs and human BTICs. Using gene manipulation (over or downregulation of TPT1) techniques including CRISPR/Cas9-mediated heterozygous gene disruption showed that TPT1 contributed to the regulation of cell proliferation/survival in mouse NSPCs, human embryonic stem cell (hESC) derived-NSPCs, human-induced pluripotent stem cells (hiPSCs) derived-NSPCs and BTICs. Furthermore, gene silencing of TPT1 caused defects in neuronal differentiation in the NSPCs in vitro. We also identified the MIF-CHD7-TPT1-SMO signaling axis in regulating hESC-NSPCs and BTICs proliferation. Intriguingly, TPT1suppressed the miR-338 gene, which targets SMO in hESC-NSPCs and BTICs. Finally, mice with implanted BTICs infected with lentivirus-TPT1 shRNA showed a longer overall survival than control. These results also open up new avenues for the development of glioma therapies based on the TPT1 signaling pathway.

Translationally Controlled Tumor Protein-Mediated Stabilization of Host Antiapoptotic Protein MCL-1 Is Critical for Establishment of Infection by Intramacrophage Parasite Leishmania donovani.

In the early phase of infection, the intramacrophage pathogen Leishmania donovani protects its niche with the help of the antiapoptotic protein myeloid cell leukemia-1 (MCL-1). Whether Leishmania could exploit MCL-1, an extremely labile protein, at the late phase is still unclear. A steady translational level of MCL-1 observed up to 48 h postinfection and increased caspase-3 activity in MCL-1-silenced infected macrophages documented its importance in the late hours of infection. The transcript level of MCL-1 showed a sharp decline at 6 h postinfection, and persistent MCL-1 expression in cyclohexamide-treated cells negates the possibility of de novo protein synthesis, thereby suggesting infection-induced stability. Increased ubiquitination, a prerequisite for proteasomal degradation of MCL-1, was also found to be absent in the late hours of infection. Lack of interaction with its specific E3 ubiquitin ligase MULE (MCL-1 ubiquitin ligase E3) and specific deubiquitinase USP9X prompted us to search for blockade of the ubiquitin-binding site in MCL-1. To this end, TCTP (translationally controlled tumor protein), a well-known binding partner of MCL-1 and antiapoptotic regulator, was found to be strongly associated with MCL-1 during infection. Phosphorylation of TCTP, a requirement for MCL-1 binding, was also increased in infected macrophages. Knockdown of TCTP decreased MCL-1 expression and short hairpin RNA-mediated silencing of TCTP in an infected mouse model of visceral leishmaniasis showed decreased parasite burden and induction of liver cell apoptosis. Collectively, our investigation revealed a key mechanism of how L. donovani exploits TCTP to establish infection within the host.

Overexpression of IncRNA TPT1-AS1 Suppresses Hepatocellular Carcinoma Cell Proliferation by Downregulating CDK2.

TPT1 Antisense RNA 1 (TPT1-AS1) is a recently identified tumor oncogenic long non-coding RNA (lncRNA) in ovarian cancer and cervical cancer. This study was carried out to study the role of lncRNA TPT1-AS1 in hepatocellular carcinoma (HCC). Samples of HCC and non-tumor tissues derived from 62 HCC patients were subjected to RNA isolation and reverse transcription quantitative polymerase chain reaction to detect the differential expression of TPT1-AS1 and cyclin dependent kinase 2 (CDK2) in HCC. Correlations between the expression of TPT1-AS1 and CDK2 were analyzed by linear regression. TPT1-AS1 and CDK2 were overexpressed in SNU-398 and SU.86.86 cells to explore their relationship. The role of TPT1-AS1 and CDK2 in regulating the cell cycle progression and proliferation of SNU-398 and SU.86.86 cells was explored by cell cycle assay and cell proliferation assay, respectively. In addition, xenograft tumor formation was also carried out to further verify the TPT1-AS1 role in HCC in vivo. It was found that TPT1-AS1 was downregulated in HCC and inversely correlated with CDK2. The expression of TPT1-AS1 in HCC tissues was not affected by age, sex, AFP, HBV, HCV, and cirrhosis infection but was downregulated by clinical stages. In HCC cells, overexpression of TPT1-AS1 mediated the downregulation of CDK2, while silencing of TPT1-AS1 mediated the upregulation of CDK2. In cell proliferation assay, overexpression of TPT1-AS1 mediated the decreased proliferation rates, while silencing of TPT1-AS1 mediated the increased proliferation rates of HCC cells, while overexpression of CDK2 played an opposite role. In addition, overexpression of TPT1-AS1 reduced tumor growth in vivo. Therefore, overexpression of TPT1-AS1 may suppress HCC cell proliferation by downregulating CDK2.