Induction of tumorigenesis and metastasis by the murine orthologue of tumor protein D52

Overexpression of TPD52L2 in HNSCC: prognostic significance and correlation with immune infiltrates

BACKGROUND

Evidence has been presented that the tumor protein D52 (TPD52) family plays a critical role in tumor development and progression. As a member of the TPD52 family, the changes in TPD52L2 gene status are instrumental in kinds of cancer development. However, its effects on patient prognosis and immune infiltration in Head and Neck Squamous Carcinoma (HNSCC) are still poorly understood.

METHODS

The Tumor Genome Atlas (TCGA), Gene Expression Omnibus (GEO), and c-BioPortal database was used to explore the expression pattern, prognostic value, and variation of gene status in HNSCC. The LinkedOmics database was used to obtain the co-expression genes of TPD52L2 and identify the diagnostic value of TPD52L2 in HNSCC. The correlations between TPD52L2 expression and six main types of immune cell infiltrations and immune signatures were explored using Tumor Immune Estimation Resource (TIMER). The correlation between TPD52L2 expression and immune checkpoint genes (ICGs) was analyzed by TCGA database. Immunohistochemistry (IHC) was performed to validate the expression of three ICGs (PDL1, PDL2, EGFR) and TPD52L2 using 5 paired HNSCC and normal head and neck tissues. Polymerase Chain Reaction (PCR) and Western Blot (WB) of HNSCC and normal head and neck cell lines were performed to verify the high level of TPD52L2 mRNA and protein expression. protein expression of TPD52L2 in pan-cancer was also validated using UALCAN.

RESULTS

TPD52L2 was overexpressed in tumor tissues, and it predicted worse survival status in HNSCC. ROC analysis suggested that TPD52L2 had a diagnostic value. Multivariate Cox analysis identified TPD52L2 as an independent negative prognostic marker of overall survival. Functional network analysis suggested that TPD52L2 was associated with immune-related signaling pathways, cell migration pathways, and cancer-related pathways. High expression of TPD52L2 was associated with a more mutant frequency of TP53. Notably, we found that the expression of TPD52L2 was closely negatively correlated with the infiltration levels of 15 types of immune cells and positively correlated with several immune markers. PCR, WB experiments, and UALCAN database verified the high level of TPD52L2 mRNA and protein expression.

CONCLUSION

TPD52L2 is upregulated in HNSCC, which is an independent factor for adverse prognosis prediction. It probably plays a role in the negative regulation of immune cell infiltration. TPD52L2 might be a promising prognostic biomarker and therapeutic target in HNSCC.

Tumor protein D52 (isoform 3) induces NF-κB - STAT3 mediated EMT driving neuroendocrine differentiation of prostate cancer cells

In prostate cancer (PCa) patients, a proto-oncogene Tumor protein D52 (TPD52) is overexpressed, and it is involved in different cellular functions. In this study, we report that TPD52 expression is positively associated with the emergence of neuroendocrine PCa (NEPC). With overexpression of TPD52 in LNCaP cells, we found neuroendocrine differentiation (NED) of cells in in-vitro and distinct NED features confirmed by NE markers neuron-specific enolase (NSE) and chromogranin A (CHR-A). Further, we investigated the molecular mechanisms involved in TPD52 mediated NED of PCa cells. We found that TPD52 activates the NF- κB - STAT3 axis for the induction of NED in LNCaP cells. Indeed, inhibition of NF-κB - STAT3 attenuated the progression of NED in TPD52 positive LNCaP cells. Importantly, silencing of TPD52 expression or inhibition of NF-κB - STAT3 activity in a neuroendocrine cell line NCI-H660 showed a marked decrease in the expression of NSE and CHR-A, confirming the reversal of the NE properties. Notably, TPD52 overexpression in LNCaP cells induced expression of N-cadherin, Vimentin, ZEB1, and Snail1 indicating that TPD52 positively regulates epithelial to mesenchymal transition (EMT) of PCa cells towards NED. Moreover, silencing of Snail1 in TPD52 positive cells blocked the progression of NED and, in NCI-H660 cells reversed NE properties as expected. Of the few requirements of TPD52, activation of NF-κB - STAT3 is essential for promoting EMT compelling NED of LNCaP cells. Collectively, these results reveal that TPD52 is associated with the progression of NEPC and emphasizes the need for therapeutic targeting of TPD52 in PCa.

Preclinical support for tumor protein D52 as a cancer vaccine antigen

Overexpressed tumor-associated antigens (TAAs) are a large group that includes proteins found at increased levels in tumors compared to healthy cells. Universal tumor expression can be defined as overexpression in all cancers examined as has been shown for Tumor Protein D52. TPD52 is an over expressed TAA actively involved in transformation, leading to increased proliferation and metastasis. TPD52 overexpression has been demonstrated in many human adult and pediatric malignancies. The murine orthologue of TPD52 (mD52) parallels normal tissue expression patterns and known functions of human TPD52 (hD52). Here in we present our preclinical studies over the past 15 years which have demonstrated that vaccine induced immunity against mD52 is effective against multiple cancers in murine models, without inducing autoimmunity against healthy tissues and cells.

Vaccination with a shared oncogenic tumor-self antigen elicits a population of CD8+ T cells with a regulatory phenotype

Cancer immunotherapy is a powerful tool for inducing antigen-specific antitumor cytotoxic T lymphocytes (CTLs). Next-generation strategies may include vaccination against overexpressed oncogenic tumor-self antigens. Previously, we reported vaccination against the oncogenic tumor-self antigen D52 (D52) was effective in preventing tumor growth. We recently reported that D52-vaccinated IL-10-deficient mice generated a significant memory response against tumor recurrence compared to wild-type mice and that vaccine-induced CD8+ IL-10+ T cells may possess regulatory function. Herein, we extended these studies by testing the hypothesis that D52-vaccine-elicited CD8+ IL-10+ T cells represent a distinct T cell population with a regulatory phenotype. C57Black/6J mice deficient in IL-10 or IFN-γ were vaccinated with the murine orthologue of D52; vaccination of wild-type (wt) mice served as a control for comparison. T cells were isolated from all three groups of vaccinated mice, and RNA was extracted from purified CD8+ T cells for deep sequencing and expression analysis. Chemokine receptor 8 (CCR8) and inducible co-stimulator (ICOS) were overexpressed in CD8+ T cells that produced IL-10 but not IFN-γ. These surface markers are associated with IL-10 producing CD4+ T regulatory cells thus supporting the possibility that CD8+ IL-10+ T cells elicited by D52 vaccination represent a unique regulatory T cell subset. The current phenotypic analyses of D52 vaccine elicited CD8+ T cells strengthen our premise that CD8+ IL-10+ T cells elicited by D52 tumor-self protein vaccination likely contribute to the suppression of memory CTL responses and inhibition of durable tumor immunity.

Tumors carrying BRAF-mutations over-express NAMPT that is genetically amplified and possesses oncogenic properties

Background

Nicotinamide phosphoribosyltransferase (NAMPT), the rate-limiting enzyme in nicotinamide adenine dinucleotide (NAD) biosynthesis, is up-regulated in several cancers, including metastatic melanoma (MM). The BRAF oncogene is mutated in different cancer types, among which MM and thyroid carcinoma (THCA) are prominent. Drugs targeting mutant BRAF are effective, especially in MM patients, even though resistance rapidly develops. Previous data have linked NAMPT over-expression to the acquisition of BRAF resistance, paving the way for therapeutic strategies targeting the two pathways.

Methods

Exploiting the TCGA database and a collection of MM and THCA tissue microarrays we studied the association between BRAF mutations and NAMPT expression. BRAF wild-type (wt) cell lines were genetically engineered to over-express the BRAF V600E construct to demonstrate a direct relationship between over-activation of the BRAF pathway and NAMPT expression. Responses of different cell line models to NAMPT (i)nhibitors were studied using dose–response proliferation assays. Analysis of NAMPT copy number variation was performed in the TCGA dataset. Lastly, growth and colony forming assays were used to study the tumorigenic functions of NAMPT itself.

Results

The first finding of this work is that tumor samples carrying BRAF-mutations over-express NAMPT, as demonstrated by analyzing the TCGA dataset, and MM and THC tissue microarrays. Importantly, BRAF wt MM and THCA cell lines modified to over-express the BRAF V600E construct up-regulated NAMPT, confirming a transcriptional regulation of NAMPT following BRAF oncogenic signaling activation. Treatment of BRAF-mutated cell lines with two different NAMPTi was followed by significant reduction of tumor growth, indicating NAMPT addiction in these cells. Lastly, we found that several tumors over-expressing the enzyme, display NAMPT gene amplification. Over-expression of NAMPT in BRAF wt MM cell line and in fibroblasts resulted in increased growth capacity, arguing in favor of oncogenic properties of NAMPT.

Conclusions

Overall, the association between BRAF mutations and NAMPT expression identifies a subset of tumors more sensitive to NAMPT inhibition opening the way for novel combination therapies including NAMPTi with BRAFi/MEKi, to postpone and/or overcome drug resistance. Lastly, the over-expression of NAMPT in several tumors could be a key and broad event in tumorigenesis, substantiated by the finding of NAMPT gene amplification.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12967-022-03315-9.

Intracellular nanovesicles mediate α5β1 integrin trafficking during cell migration

Membrane traffic is an important regulator of cell migration through the endocytosis and recycling of cell surface receptors such as integrin heterodimers. Intracellular nanovesicles (INVs) are transport vesicles that are involved in multiple membrane trafficking steps, including the recycling pathway. The only known marker for INVs is tumor protein D54 (TPD54/TPD52L2), a member of the TPD52-like protein family. Overexpression of TPD52-like family proteins in cancer has been linked to poor prognosis and an aggressive metastatic phenotype, which suggests cell migration may be altered under these conditions. Here, we show that TPD54 directly binds membrane and associates with INVs via a conserved positively charged motif in its C terminus. We describe how other TPD52-like proteins are also associated with INVs, and we document the Rab GTPase complement of all INVs. Depletion of TPD52-like proteins inhibits cell migration and invasion, while their overexpression boosts motility. We show that inhibition of migration is likely due to altered recycling of α5β1 integrins in INVs.

Tumor protein D52 is upregulated in oral squamous carcinoma cells under hypoxia in a hypoxia-inducible-factor-independent manner and is involved in cell death resistance

Background

Tumor protein D52 (TPD52) reportedly plays an important role in the proliferation and metastasis of various cancer cells, including oral squamous cell carcinoma (OSCC) cells, and is expressed strongly at the center of the tumor, where the microenvironment is hypoxic. Thus, the present study investigated the roles of TPD52 in the survival and death of OSCC cells under hypoxia, and the relationship with hypoxia-inducible factor (HIF). We examined the expression of TPD52 in OSCC cells under hypoxic conditions and analyzed the effects of HIF on the modulation of TPD52 expression. Finally, the combinational effects of TPD52 knockdown and HIF inhibition were investigated both in vitro and in vivo.

Results

The mRNA and protein levels of TPD52 increased in OSCC cells under hypoxia. However, the increase was independent of HIF transcription. Importantly, the observation was due to upregulation of mRNA stability by binding of mRNA to T-cell intercellular antigen (TIA) 1 and TIA-related protein (TIAR). Simultaneous knockdown of TPD52 and inhibition of HIF significantly reduced cell viability. In addition, the in vivo tumor-xenograft experiments showed that TPD52 acts as an autophagy inhibitor caused by a decrease in p62.

Conclusions

This study showed that the expression of TPD52 increases in OSCC cells under hypoxia in a HIF-independent manner and plays an important role in the proliferation and survival of the cells in concordance with HIF, suggesting that novel cancer therapeutics might be led by TPD52 suppression.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13578-021-00634-0.

Tissue microarray profiling and integrative proteomics indicate the modulatory potential of Maytenus royleanus in inhibition of overexpressed TPD52 in prostate cancers

Maytenus roylanus (MEM) is a plant with anti-proliferative effects against prostate cancer. We aimed to explore the mechanism of action of MEM in prostate cancer (PCa) by employing an in vitro global proteome approach to get useful information of various signaling pathways and effected genes to define the mechanism of MEM action in prostate cancer. We conducted a global proteome analysis of CWR22Rv1after treatment with methanolic extract of MEM. The result of the proteomic profiling of in vitro PCa cells demonstrated the reduction in tumor protein D52 (TPD52) expression after treatment with methanolic extract of MEM. Down-regulation of TPD52 expression at mRNA level was observed by MEM treatment in CWR22Rν1 and C4-2 cells in a dose-dependent fashion probably by cleavage of Caspase 3 and PARP, or by modulation of cyclin-dependent kinases in CWR22Rν1 and C4-2 cells. The progressive character of the TRAMP model demonstrates a chance to evaluate the potential of chemo-preventive agents for both initial and late stages of prostate cancer development, and induction in TPD52 protein expression with development as well as the progression of prostate cancer was observed in the TRAMP model. Analyses of the tissue microarray collection of 25 specimens confirmed the clinical significance of our findings identifying TPD52 as a potential marker for PCa progression. We determined that knockdown of TPD52 (CWR22Rν1 cells), a considerable downregulation was seen at the protein level. Downregulation of TPD52 inhibited the migration and invasive behavior of prostate cancer cells as observed. Moreover, we observed that the siRNA-TPD52 transfection of CWR22Rν1 cells resulted in tumor growth inhibition with a marked reduction in the secretion of prostate-specific antigen (PSA) in the serum. Intraperitoneal injection of MEM considerably slowed tumor growth in athymic mice, inhibited TPD52 expression, and caused a marked reduction in PSA levels of serum as demonstrated by immunoblot screening and immune-histochemical staining. This report illustrates a molecular overview of pathological processes in PCa, indicating possible new disease biomarkers and therapeutic targets.

Analysis of the CD8+ IL-10+ T cell response elicited by vaccination with the oncogenic tumor-self protein D52

Development of cancer vaccines targeting tumor self-antigens is complex and challenging due to the difficulty of overcoming immune tolerance to self-proteins. Vaccination against tumor self-protein D52 (D52) has been successful, although complete protection appears impaired by immune regulation. Our previous studies suggest that vaccine elicited CD8 + T cells producing interleukin 10 (IL-10) may have a negative impact on tumor protection. Understanding the role CD8+ IL-10 + T cells play in the immune response following vaccination with D52 could result in a more potent vaccine. To address this, we vaccinated IL-10 deficient mice with the murine orthologue of D52; vaccination of wild type (wt) C57BL/6J served as a control for comparison. In separate experiments, D52 vaccinated wt mice were administered IL-10R-specific mAb to neutralize IL-10 function. Interestingly, we observed similar protection against primary tumor challenge in the experimental groups compared to the controls. However, individual IL-10 deficient mice that rejected the primary tumor challenge were re-challenged 140 days post-primary challenge to access vaccine durability and immunologic memory against tumor recurrence. Mice deficient in IL-10 demonstrated a memory response in which 100% of the mice were protected from secondary tumor challenge, while wt mice had diminished recall response (25%) against tumor recurrence. These results with analysis of vaccine-elicited CD8 + T cells for tumor-specific killing and regulatory cell marker expression, add further support to our premise that CD8+ IL-10 + T cells elicited by D52 tumor-self protein vaccine contribute to the suppression of a memory CTL responses and durable tumor immunity.

Tumor protein D52 (isoform 3) interacts with and promotes peroxidase activity of Peroxiredoxin 1 in prostate cancer cells implicated in cell growth and migration

Tumor protein D52 (TPD52) is overexpressed in multiple cancers including prostate cancer due to gene amplification and investigations to understand its role in the pathophysiology of different cancers are continuing. GST pull-down assays and Tandem affinity purification of TPD52 as bait identified novel prey Peroxiredoxin 1 (PRDX1) in prostate cancer (PCa) cells. PRDX1 interaction with TPD52 was confirmed in immunoprecipitation and affinity interaction assays. Mapping of interaction domain indicated that PRDX1 interacts with C-terminal region of TPD52 containing PEST domain between 152 and 179 amino acids, a new binding region of TPD52. Here we show that TPD52 interaction with PRDX1 increased its peroxidase activity and ectopic expression of TPD52 induced dimerization of PRDX1 in PCa cells. Moreover, H₂O₂ exposure evoked the interaction between TPD52 and PRDX1 while depletion of both proteins led to the accumulation of H₂O₂ suggesting peroxidase activity is important to maintain oxidative capacity in PCa cells. We also observed that overexpression or downregulation of TPD52 and PRDX1 individually or together affecting PCa cells growth, survival, and migration. Altogether, our results show a novel interaction partner of TPD52 providing new insights of its functions and ascertain the role of TPD52-PRDX1 interaction in PCa progression.

The novel function of tumor protein D54 in regulating pyruvate dehydrogenase and metformin cytotoxicity in breast cancer

Background

The role of tumor protein D54 in breast cancer has not been studied and its function in breast cancer remains unclear. In our previous pharmacogenomic studies using lymphoblastoid cell line (LCL), this protein has been identified to affect metformin response. Although metformin has been widely studied as a prophylactic and chemotherapeutic drug, there is still a lack of biomarkers predicting the response to metformin in breast cancer. In this study, we revealed the novel function of TPD54 in breast cancer through understanding how TPD54 altered the cancer cell sensitivity to metformin.

Methods

The role of TPD54 in altering cellular sensitivity to metformin treatment was carried out by either knockdown or overexpression of TPD54, followed by measuring cell viability and reactive oxygen species (ROS) production in MCF7 breast cancer cell line and breast cancer patient-derived xenografts. Functional analysis of TPD54 in breast cancer cells was demonstrated by studying TPD54 protein localization and identification of potential binding partners of TPD54 through immunoprecipitation followed by mass spectrometry. The effect of TPD54 on pyruvate dehydrogenase (PDH) protein regulation was demonstrated by western blot, immunoprecipitation, and site-directed mutagenesis.

Results

TPD54 inhibited colony formation and enhanced cellular sensitivity to metformin treatment in MCF7 cells and breast cancer patient-derived xenografts. Mechanistic study indicated that TPD54 had mitochondrial localization, bound to and stabilized pyruvate dehydrogenase E1α by blocking pyruvate dehydrogenase kinase 1 (PDK1)-mediated serine 232 phosphorylation. TPD54 knockdown increased PDH E1α protein degradation and led to decreased PDH enzyme activity, which reduced mitochondrial oxygen consumption and reactive oxygen species (ROS) production, thus contributing to the resistance of breast cancer cells to metformin treatment.

Conclusion

We have discovered a novel mechanism by which TPD54 regulates pyruvate dehydrogenase and affects the sensitivity of breast cancer to metformin treatment. Our findings highlight the important post-translational regulation of PDK1 on PDH E1α and the potential application of TPD54 as a biomarker for selecting tumors that may be sensitive to metformin therapy. These provide new insights into understanding the regulation of PDH complexes and the resistance mechanisms of cancer cells to metformin treatment.

Electronic supplementary material

The online version of this article (10.1186/s40170-018-0193-4) contains supplementary material, which is available to authorized users.

SIRT1 at the crossroads of AKT1 and ERβ in malignant pleural mesothelioma cells

In this report, we show that malignant pleural mesothelioma (MPM) patients whose tumors express high levels of AKT1 exhibit a significantly worse prognosis, whereas no significant correlation with AKT3 expression is observed. We provide data that establish a phosphorylation independent role of AKT1 in affecting MPM cell shape and anchorage independent cell growth in vitro and highlight the AKT1 isoform-specific nature of these effects.

We describe that AKT1 activity is inhibited by the loss of SIRT1-mediated deacetylation and identify, by mass spectrometry, 11 unique proteins that interact with acetylated AKT1.

Our data demonstrate a role of the AKT1/SIRT1/FOXM1 axis in the expression of the tumor suppressor ERβ. We further demonstrate an inhibitory feedback loop by ERβ, activated by the selective agonist KB9520, on this axis both in vitro and in vivo.

Our data broaden the current knowledge of ERβ and AKT isoform-specific functions that could be valuable in the design of novel and effective therapeutic strategies for MPM.

Tumor protein D52 (isoform 3) contributes to prostate cancer cell growth via targeting nuclear factor-κB transactivation in LNCaP cells

Our previous study showed that TPD52 overexpression could increase migration and proliferation of LNCaP cells contributing to the development of prostate cancer. However, mechanism of TPD52 in prostate cancer initiation and progression remains elusive. In this study, we investigated the possible underlying mechanism of TPD52 in prostate cancer progression. In LNCaP cells, TPD52 expression was altered by transfecting with either EGFP-TPD52 or specific short hairpin RNA. Overexpression of TPD52 protected LNCaP cells from apoptosis through elevated anti-apoptotic proteins XIAP, Bcl-2, and Cyclin D1, whereas Bax was downregulated. Mechanistically, we found that TPD52 confers transactivation of nuclear factor-κB, thereby enhancing its target gene expression in LNCaP cells. TPD52 promotes LNCaP cell invasion probably via increased matrix metalloproteinase 9 expression and its activity while tissue inhibitor of metalloproteinase expression is significantly downregulated. Notably, TPD52 might be involved in cell adhesion, promoting tumor metastasis by inducing loss of E-cadherin, expression of vimentin and vascular cell adhesion molecule, and additionally activation of focal adhesion kinase. Furthermore, TPD52 directly interacts with nuclear factor-κB p65 (RelA) and promotes accumulation of phosphorylated nuclear factor-κB (p65)^S536 that is directly linked with nuclear factor-κB transactivation. Indeed, depletion of TPD52 or inhibition of nuclear factor-κB in TPD52-positive cells inhibited secretion of tumor-related cytokines and contributes to the activation of STAT3, nuclear factor-κB, and Akt. Interestingly, in TPD52 overexpressing LNCaP cells, nuclear factor-κB inhibition prevented the autocrine/paracrine activation of STAT3. TPD52 activates STAT3 through ascertaining a cross talk between the nuclear factor-κB and the STAT3 signaling systems. Collectively, these results reveal mechanism by which TPD52 is associated with prostate cancer progression and highlight the approach for therapeutic targeting of TPD52 in prostate cancer.

The four-transmembrane protein MAL2 and tumor protein D52 (TPD52) are highly expressed in colorectal cancer and correlated with poor prognosis

The four-transmembrane protein MAL2 and tumor protein D52 (TPD52) have been shown to be involved in tumorigenesis of various cancers. However, their roles in colorectal cancer (CRC) remain unclear. In this study, we explored the expressions of MAL2 and TPD52 in tumor specimens resected from 123 CRC patients and the prognostic values of the two proteins in CRC. Immunohistochemical analyses showed that MAL2 (P<0.001) and TPD52 (P<0.001) were significantly highly expressed in primary carcinoma tissues compared with adjacent non-cancerous mucosa tissues. And TPD52 exhibited frequent overexpression in liver metastasis tissues relative to primary carcinoma tissues (P = 0.042), while MAL2 in lymphnode and liver metastasis tissues showed no significant elevation. Real-time quantitative PCR (RT-qPCR) showed the identical results. Correlation analyses by Pearson's chi-square test demonstrated that MAL2 in tumors was positively correlated with tumor status (pathological assessment of regional lymph nodes (pN, P = 0.024)), and clinic stage (P = 0.017). Additionally, the expression of TPD52 was detected under the same condition and was shown to be positively correlated withtumor status (pathological assessment of the primary tumor (pT, P = 0.035), distant metastasis (pM, P = 0.001)) and CRC clinicopathology(P = 0.024). Kaplan-Meier survival curves indicated that positive MAL2 (P<0.001) and TPD52 (P<0.001) expressions were associated with poor overall survival (OS) in CRC patients. Multivariate analysis showed that MAL2 and TPD52 expression was an independent prognostic factor for reduced OS of CRC patients. Moreover, overexpression of TPD52 in CRC SW480 cells showed an increased cell migration (P = 0.023) and invasion (P = 0.012) through inducing occurrence of epithelial-mesenchymal transition (EMT) and activating focal adhesion kinase (FAK)-mediated integrin signalling and PI3K⁄Akt signalling.Whereas TPD52-depleted cells showed the reverse effect. These data suggested that MAL2 and TPD52 might be potential biomarkers for clinical prognosis and might be a promising therapeutic target for CRC.

All-Trans-Retinoic Acid Stimulates Overexpression of Tumor Protein D52 (TPD52, Isoform 3) and Neuronal Differentiation of IMR-32 Cells

Tumor protein D52 (TPD52), a proto-oncogene is overexpressed in a variety of epithelial carcinomas and plays an important role in cell proliferation, migration, and cell death. In the present study we found that the treatment of IMR-32 neuroblastoma (NB) cells with retinoic acid (RA) stimulates an increase in expression of TPD52. TPD52 expression is detectable after 72 h, can be maintained till differentiation of NB cells suggesting that TPD52 is involved in differentiation. Here, we demonstrate that TPD52 is essential for RA to promote differentiation of NB cells. Our results show that exogenous expression of EGFP-TPD52 in IMR-32 cells resulted cell differentiation even without RA. RA by itself and with overexpression of TPD52 can increase the ability of NB cells differentiation. Interestingly, transfection of IMR-32 cells with a specific small hairpin RNA for efficient knockdown of TPD52 attenuated RA induced NB cells differentiation. Transcriptional and translational level expression of neurotropic (BDNF, NGF, Nestin) and differentiation (β III tubulin, NSE, TH) factors in NB cells with altered TPD52 expression and/or RA treatment confirmed essential function of TPD52 in cellular differentiation. Furthermore, we show that TPD52 protects cells from apoptosis and arrest cell proliferation by varying expression of p27Kip1, activation of Akt and ERK1/2 thus promoting cell differentiation. Additionally, inhibition of STAT3 activation by its specific inhibitor arrested NB cells differentiation by EGFP-TPD52 overexpression with or without RA. Taken together, our data reveal that TPD52 act through activation of JAK/STAT signaling pathway to undertake NB cells differentiation induced by RA. J. Cell. Biochem. 118: 4358-4369, 2017. © 2017 Wiley Periodicals, Inc.

Opposite effects of tumor protein D (TPD) 52 and TPD54 on oral squamous cell carcinoma cells

The tumor protein D52 (TPD52) protein family includes TPD52, -53, -54 and -55. Several reports have shown important roles for TPD52 and TPD53, and have also suggested the potential involvement of TPD54, in D52-family physiological effects. Therefore, we performed detailed expression analysis of TPD52 family proteins in oral squamous cell carcinoma (OSCC). Towards this end, TPD54-overexpressing or knocked-down cells were constructed using OSCC-derived SAS, HSC2 and HSC3 cells. tpd52 or tpd53 was expressed or co-expressed in these cells by transfection. The cells were then analyzed using cell viability (MTT), colony formation, migration, and invasion assays. In OSCC-xenograft experiments, the cells were transplanted into nude mice together with injection of anti-tpd siRNAs. MTT assay of cell monolayers showed little differences in growth of the transfected cells. tpd54 overexpression in SAS cells significantly decreased colony formation in an anchorage-independent manner. Additionally, knock-down of tpd54 enhanced the number of colonies formed and overexpression of tpd52 in tpd54 knock-down cells increased the size of the colonies formed. The chemotaxis assay showed that tpd54 overexpression decreased cell migration. In the OSCC-xenograft in vivo study, tpd54 overexpression slightly attenuated tumor volume in vivo, despite the fact that tumor metastasis or cell survival was not involved. Our results showed that TPD54 not only downregulated anchorage-independent growth and cell migration in vitro, but also attenuated tumor growth in vivo. Based on these results, it is considered that TPD54 might act as a negative regulator of tumor progression in OSCC cells.

Regulation of TPD52 by antitumor microRNA-218 suppresses cancer cell migration and invasion in lung squamous cell carcinoma

The development of targeted molecular therapies has greatly benefited patients with lung adenocarcinomas. In contrast, these treatments have had little benefit in the management of lung squamous cell carcinoma (lung SCC). Therefore, new treatment options based on current genomic approaches are needed for lung SCC. Aberrant microRNA (miRNA) expression has been shown to promote lung cancer development and aggressiveness. Downregulation of microRNA-218 (miR-218) was frequently observed in our miRNA expression signatures of cancers, and previous studies have shown an antitumor function of miR-218 in several types of cancers. However, the impact of miR-218 on lung SCC is still ambiguous. The present study investigated the antitumor roles of miR-218 in lung SCC to identify the target genes regulated by this miRNA. Ectopic expression of miR-218 greatly inhibited cancer cell migration and invasion in the lung SCC cell lines EBC-1 and SK-MES-1. Through a combination of in silico analysis and gene expression data searching, tumor protein D52 (TPD52) was selected as a putative target of miR-218 regulation. Moreover, direct binding of miR-218 to the 3'-UTR of TPD52 was observed by dual luciferase reporter assay. Overexpression of TPD52 was observed in lung SCC clinical specimens, and knockdown of TPD52 significantly suppressed cancer cell migration and invasion in lung SCC cell lines. Furthermore, the downstream pathways mediated by TPD52 involved critical regulators of genomic stability and mitotic checkpoint genes. Taken together, our data showed that downregulation of miR-218 enhances overexpression of TPD52 in lung SCC cells, promoting cancer cell aggressiveness. Identification of tumor-suppressive miRNA-mediated RNA networks of lung SCC will provide new insights into the potential mechanisms of the molecular pathogenesis of the disease.

DNA methylome changes by estradiol benzoate and bisphenol A links early-life environmental exposures to prostate cancer risk

Developmental exposure to endocrine-disrupting chemicals (EDCs), 17β-estradiol-3-benzoate (EB) and bisphenol A (BPA), increases susceptibility to prostate cancer (PCa) in rodent models. Here, we used the methylated-CpG island recovery assay (MIRA)-assisted genomic tiling and CpG island arrays to identify treatment-associated methylome changes in the postnatal day (PND)90 dorsal prostate tissues of Sprague-Dawley rats neonatally (PND1, 3, and 5) treated with 25 µg/pup or 2,500 µg EB/kg body weight (BW) or 0.1 µg BPA/pup or 10 µg BPA/kg BW. We identified 111 EB-associated and 86 BPA-associated genes, with 20 in common, that have significant differentially methylated regions. Pathway analysis revealed cancer as the top common disease pathway. Bisulfite sequencing validated the differential methylation patterns observed by array analysis in 15 identified candidate genes. The methylation status of 7 (Pitx3, Wnt10b, Paqr4, Sox2, Chst14, Tpd52, Creb3l4) of these 15 genes exhibited an inverse correlation with gene expression in tissue samples. Cell-based assays, using 5-aza-cytidine-treated normal (NbE-1) and cancerous (AIT) rat prostate cells, added evidence of DNA methylation-mediated gene expression of 6 genes (exception: Paqr4). Functional connectivity of these genes was linked to embryonic stem cell pluripotency. Furthermore, clustering analyses using the dataset from The Cancer Genome Atlas revealed that expression of this set of 7 genes was associated with recurrence-free survival of PCa patients. In conclusion, our study reveals that gene-specific promoter methylation changes, resulting from early-life EDC exposure in the rat, may serve as predictive epigenetic biomarkers of PCa recurrence, and raises the possibility that such exposure may impact human disease.

Tumor-suppressive microRNA-34a inhibits breast cancer cell migration and invasion via targeting oncogenic TPD52

The tumor protein D52 (TPD52) is an oncogene overexpressed in breast cancer. Although the oncogenic effects of TPD52 are well recognized, how its expression and the role in migration/invasion is still not clear. This study tried to explore the regulative role of microRNA-34a (miR-34a), a tumor suppressive miRNA, on TPD52 expression in breast cancer. The expression of miR-34a was found significantly decreased in breast cancer specimens with lymph node metastases and breast cancer cell lines. The clinicopathological characteristics analyzed showed that lower expression levels of miR-34a were associated with advanced clinical stages. Moreover, TPD52 was demonstrated as one of miR-34a direct targets in human breast cancer cells. miR-34a was further found significantly repress epithelial-mesenchymal transition (EMT) and inhibit breast cancer cell migration and invasion via TPD52. These findings indicate that miR-34a inhibits breast cancer progression and metastasis through targeting TPD52. Consequently, our data strongly suggested that oncogenic TPD52 pathway regulated by miR-34a might be useful to reveal new therapeutic targets for breast cancer.

Tumour-promoting activity of polycyclic aromatic hydrocarbons and their oxygenated or nitrated derivatives

Various types of polycyclic aromatic compounds (PACs) in diesel exhaust particles are thought to contribute to carcinogenesis in mammals. Although the carcinogenicity, mutagenicity and tumour-initiating activity of these compounds have been evaluated, their tumour-promoting activity is unclear. In the present study, to determine the tumour-inducing activity of PACs, including previously known mutagenic compounds in atmospheric environments, a transformation assay for promoting activity mediated by the release of contact inhibition was conducted for six polycyclic aromatic hydrocarbons (PAHs), seven oxygenated PAHs (oxy-PAHs) and seven nitrated PAHs (nitro-PAHs) using mouse embryonic fibroblast cells transfected with the v-Ha-ras gene (Bhas 42 cells). Of these, two PAHs [benzo[k]fluoranthene (B[k]FA) and benzo[b]fluoranthene (B[b]FA)], one oxy-PAH [6H-benzo[cd]pyren-6-one (BPO)] and two nitro-PAHs (3-nitro-7H-benz[de]anthracen-7-one and 6-nitrochrysene) were found to exhibit particularly powerful tumour-promoting activity (≥10 foci following exposure to <100nM). In addition, clear mRNA expression of CYP1A1, which is associated with aryl hydrocarbon receptor (AhR)-mediated activation, was observed following the exposure of cells to two PAHs (B[k]FA and B[b]FA) and three oxy-PAHs (1,2-naphthoquinone, 11H-benzo[b]fluoren-11-one and BPO). Further, an HO-1 antioxidant response activation was observed following exposure to B[k]FA, B[b]FA and BPO, suggesting that the induction of tumour-promoting activity in these compounds is correlated with the dysfunction of signal transduction via AhR-mediated responses and/or oxidative stress responses.

Overexpressed oncogenic tumor-self antigens

Overexpressed tumor-self antigens represent the largest group of candidate vaccine targets. Those exhibiting a role in oncogenesis may be some of the least studied but perhaps most promising. This review considers this subset of self antigens by highlighting vaccine efforts for some of the better known members and focusing on TPD52, a new promising vaccine target. We shed light on the importance of both preclinical and clinical vaccine studies demonstrating that tolerance and autoimmunity (presumed to preclude this class of antigens from vaccine development) can be overcome and do not present the obstacle that might have been expected. The potential of this class of antigens for broad application is considered, possibly in the context of low tumor burden or adjuvant therapy, as is the need to understand mechanisms of tolerance that are relatively understudied.

TPD52 expression increases neutral lipid storage within cultured cells

Tumor protein D52 (TPD52) is amplified and/or overexpressed in cancers of diverse cellular origins. Altered cellular metabolism (including lipogenesis) is a hallmark of cancer development, and protein-protein associations between TPD52 and known regulators of lipid storage, and differential TPD52 expression in obese versus non-obese adipose tissue, suggest that TPD52 might regulate cellular lipid metabolism. We found increased lipid droplet numbers in BALB/c 3T3 cell lines stably expressing TPD52, compared with control and TPD52L1-expressing cell lines. TPD52-expressing 3T3 cells showed increased fatty acid storage in triglyceride (from both de novo synthesis and uptake) and formed greater numbers of lipid droplets upon oleic acid supplementation than control cells. TPD52 colocalised with Golgi, but not endoplasmic reticulum (ER), markers and also showed partial colocalisation with lipid droplets coated with ADRP (also known as PLIN2), with a proportion of TPD52 being detected in the lipid droplet fraction. Direct interactions between ADRP and TPD52, but not TPD52L1, were demonstrated using the yeast two-hybrid system, with ADRP-TPD52 interactions confirmed using GST pulldown assays. Our findings uncover a new isoform-specific role for TPD52 in promoting intracellular lipid storage, which might be relevant to TPD52 overexpression in cancer.

Novel prognostic markers revealed by a proteomic approach separating benign from malignant insulinomas

The prognosis of pancreatic neuroendocrine tumors is related to size, histology and proliferation rate. However, this stratification needs to be refined further. We conducted a proteome study on insulinomas, a well-defined pancreatic neuroendocrine tumor entity, in order to identify proteins that can be used as biomarkers for malignancy. Based on a long follow-up, insulinomas were divided into those with metastases (malignant) and those without (benign). Microdissected cells from six benign and six malignant insulinomas were subjected to a procedure combining fluorescence dye saturation labeling with high-resolution two-dimensional gel electrophoresis. Differentially expressed proteins were identified using nano liquid chromatography-electrospray ionization/multi-stage mass spectrometry and validated by immunohistochemistry on tissue microarrays containing 62 insulinomas. Sixteen differentially regulated proteins were identified among 3000 protein spots. Immunohistochemical validation revealed that aldehyde dehydrogenase 1A1 and voltage-dependent anion-selective channel protein 1 showed significantly stronger expression in malignant insulinomas than in benign insulinomas, whereas tumor protein D52 (TPD52) binding protein was expressed less strongly in malignant insulinomas than in benign insulinomas. Using multivariate analysis, low TPD52 expression was identified as a strong independent prognostic factor for both recurrence-free and overall disease-related survival.

Tumor protein D52 (TPD52) and cancer-oncogene understudy or understudied oncogene?

The Tumor protein D52 (TPD52) gene was identified nearly 20 years ago through its overexpression in human cancer, and a substantial body of data now strongly supports TPD52 representing a gene amplification target at chromosome 8q21.13. This review updates progress toward understanding the significance of TPD52 overexpression and targeting, both in tumors known to be characterized by TPD52 overexpression/amplification, and those where TPD52 overexpression/amplification has been recently or variably reported. We highlight recent findings supporting microRNA regulation of TPD52 expression in experimental systems and describe progress toward deciphering TPD52's cellular functions, particularly in cancer cells. Finally, we provide an overview of TPD52's potential as a cancer biomarker and immunotherapeutic target. These combined studies highlight the potential value of genes such as TPD52, which are overexpressed in many cancer types, but have been relatively understudied.

Patterns of TPD52 overexpression in multiple human solid tumor types analyzed by quantitative PCR

Tumor protein D52 (TPD52) is located at chromosome 8q21, a region that is frequently gained or amplified in multiple human cancer types. TPD52 has been suggested as a potential target for new anticancer therapies. In order to analyze TPD52 expression in the most prevalent human cancer types, we employed quantitative PCR to measure TPD52 mRNA levels in formalin-fixed tissue samples from more than 900 cancer tissues obtained from 29 different human cancer types. TPD52 was expressed at varying levels in all tested normal tissues, including skin, lymph node, lung, oral mucosa, breast, endometrium, ovary, vulva, myometrium, liver, pancreas, stomach, kidney, prostate, testis, urinary bladder, thyroid gland, brain, muscle and fat tissue. TPD52 was upregulated in 18/29 (62%) tested cancer types. Strongest expression was found in non-seminoma (56-fold overexpression compared to corresponding normal tissue), seminoma (42-fold), ductal (28-fold) and lobular breast cancer (14-fold). In these tumor types, TPD52 upregulation was found in the vast majority (>80%) of tested samples. Downregulation was found in 11 (38%) tumor types, most strongly in papillary renal cell cancer (-8-fold), leiomyosarcoma (-6-fold), clear cell renal cell cancer (-5-fold), liposarcoma (-5-fold) and lung cancer (-4-fold). These results demonstrate that TPD52 is frequently and strongly upregulated in many human cancer types, which may represent candidate tumor types for potential anti-TPD52 therapies.

Tumor protein D52 represents a negative regulator of ATM protein levels

Tumor protein D52 (TPD52) is a coiled-coil motif bearing hydrophilic polypeptide known to be overexpressed in cancers of diverse cellular origins. Increased TPD52 expression is associated with increased proliferation and invasive capacity in different cell types. Recent studies have reported a correlation between TPD52 transcript levels and G 2 chromosomal radiosensitivity in lymphocytes of women at risk of hereditary breast cancer, and that TPD52 knockdown significantly reduced the radiation sensitivity of multiple cancer cell lines. In this study, we investigated possible roles for TPD52 in DNA damage response, and found that increased TPD52 expression in breast cancer and TPD52-expressing BALB/c 3T3 cells compromised ATM-mediated cellular responses to DNA double-strand breaks induced by γ-ray irradiation, which was associated with downregulation of steady-state ATM protein, but not transcript levels, regardless of irradiation status. TPD52-expressing 3T3 cells also showed significantly increased radiation sensitivity compared with vector cells evaluated by clonogenic assays. Furthermore, direct interactions between exogenous and endogenous ATM and TPD52 were detected by GST pull-down and co-immunoprecipitation assays. We also identified the interaction domains involved in this binding as TPD52 residues 111-131, and ATM residues 1-245 and 772-1102. Taken together, our results suggest that TPD52 may represent a novel negative regulator of ATM protein levels.

Injection site and regulatory T cells influence durable vaccine-induced tumor immunity to an over-expressed self tumor associated antigen

Tumor protein D52 (D52) is constitutively expressed in healthy tissues and overexpressed in multiple cancers, including (but not limited to) breast, prostate and ovarian carcinomas. Although the normal functions of D52 are unknown, it is clear that increased D52 expression levels not only stimulate cell proliferation and metastasis, but also correlate with poor prognosis in a subset of breast cancer patients. The murine orthologs of D52 (mD52) shares 86% identity with its human counterpart (hD52) and mirrors hD52 expression patterns. The forced overexpression of mD52 induces anchorage-independent growth in vitro and promotes tumor formation as well as spontaneous metastasis in vivo. We have previously reported that the intramuscular administration of recombinant mD52 elicits immune responses capable of rejecting a challenge with tumor cells and preventing spontaneous metastasis only in 50% of mice. We hypothesized that mechanisms of peripheral tolerance dampen immune responses against mD52, thus limiting the protective effects of vaccination. To test this hypothesis, mice were depleted of CD25⁺ regulatory T cells (Tregs) and subcutaneously immunized with mD52 prior to a tumor challenge. The subcutaneous immunization failed to induce protective antitumor immunity unless accompanied by Treg depletion, which resulted in a rate of protection of 70% as compared with

Altered miRNA and gene expression in acute myeloid leukemia with complex karyotype identify networks of prognostic relevance

Recently, the p53-miR-34a network has been identified to have an important role in tumorigenesis. As in acute myeloid leukemia with complex karyotype (CK-AML) TP53 alterations are the most common known molecular lesion, we further analyzed the p53-miR-34a axis in a large cohort of CK-AML with known TP53 status (TP53(altered), n=57; TP53(unaltered), n=31; altered indicates loss and/or mutation of TP53). Profiling microRNA (miRNA) expression delineated TP53 alteration-associated miRNA profiles, and identified miR-34a and miR-100 as the most significantly down- and upregulated miRNA, respectively. Moreover, we found a distinct miR-34a expression-linked gene expression profile enriched for genes belonging to p53-associated pathways, and implicated in cell cycle progression or apoptosis. Clinically, low miR-34a expression and TP53 alterations predicted for chemotherapy resistance and inferior outcome. Notably, in TP53(unaltered) CK-AML, high miR-34a expression predicted for inferior overall survival (OS), whereas in TP53(biallelic altered) CK-AML, high miR-34a expression pointed to better OS. Thus, detailed molecular profiling links impaired p53 to decreased miR-34a expression, but also identifies p53-independent miR-34a induction mechanisms as shown in TP53(biallelic altered) cell lines treated with 15-deoxy-Δ(12,14)-prostaglandin. An improved understanding of this mechanism might provide novel therapeutic options to restore miR-34a function and thereby induce cell cycle arrest and apoptosis in TP53(altered) CK-AML.

Secretion of novel SEL1L endogenous variants is promoted by ER stress/UPR via endosomes and shed vesicles in human cancer cells

We describe here two novel endogenous variants of the human endoplasmic reticulum (ER) cargo receptor SEL1LA, designated p38 and p28. Biochemical and RNA interference studies in tumorigenic and non-tumorigenic cells indicate that p38 and p28 are N-terminal, ER-anchorless and more stable relative to the canonical transmembrane SEL1LA. P38 is expressed and constitutively secreted, with increase after ER stress, in the KMS11 myeloma line and in the breast cancer lines MCF7 and SKBr3, but not in the non-tumorigenic breast epithelial MCF10A line. P28 is detected only in the poorly differentiated SKBr3 cell line, where it is secreted after ER stress. Consistently with the presence of p38 and p28 in culture media, morphological studies of SKBr3 and KMS11 cells detect N-terminal SEL1L immunolabeling in secretory/degradative compartments and extracellularly-released membrane vesicles. Our findings suggest that the two new SEL1L variants are engaged in endosomal trafficking and secretion via vesicles, which could contribute to relieve ER stress in tumorigenic cells. P38 and p28 could therefore be relevant as diagnostic markers and/or therapeutic targets in cancer.

Estrogen receptor β exerts tumor repressive functions in human malignant pleural mesothelioma via EGFR inactivation and affects response to gefitinib

BACKGROUND

The role of estrogen and estrogen receptors in oncogenesis has been investigated in various malignancies. Recently our group identified estrogen receptor beta (ERβ) expression as an independent prognostic factor in the progression of human Malignant Pleural Mesothelioma (MMe), but the underlying mechanism by which ERβ expression in tumors determines clinical outcome remains largely unknown. This study is aimed at investigating the molecular mechanisms of ERβ action in MMe cells and disclosing the potential translational implications of these results.

METHODS

We modulated ERβ expression in REN and MSTO-211H MMe cell lines and evaluated cell proliferation and EGF receptor (EGFR) activation.

RESULTS

Our data indicate that ERβ knockdown in ER positive cells confers a more invasive phenotype, increases anchorage independent proliferation and elevates the constitutive activation of EGFR-coupled signal transduction pathways. Conversely, re-expression of ERβ in ER negative cells confers a more epithelioid phenotype, decreases their capacity for anchorage independent growth and down-modulates proliferative signal transduction pathways. We identify a physical interaction between ERβ, EGFR and caveolin 1 that results in an altered internalization and in a selective reduced activation of EGFR-coupled signaling, when ERβ is over-expressed. We also demonstrate that differential expression of ERβ influences MMe tumor cell responsiveness to the therapeutic agent: Gefitinib.

CONCLUSIONS

This study describes a role for ERβ in the modulation of cell proliferation and EGFR activation and provides a rationale to facilitate the targeting of a subgroup of MMe patients who would benefit most from therapy with Gefitinib alone or in combination with Akt inhibitors.

A role for tumor protein TPD52 phosphorylation in endo-membrane trafficking during cytokinesis

Tumor protein D52 is expressed at high levels in exocrine cells containing large secretory granules where it regulates Ca(2+)-dependent protein secretion; however, D52 expression is also highly induced in multiple cancers. The present study investigated a role for the Ca(2+)-dependent phosphorylation of D52 at the single major phospho-acceptor site serine 136 on cell division. Ectopic expression of wild type D52 (D52wt) and the phosphomutants serine 136/alanine (S136A) or serine 136/glutamate (S136/E) resulted in significant multinucleation of cells. D52wt and S136/E each resulted in a greater than 2-fold increase in multinucleated cells compared to plasmid-transfected controls whereas the S136/A phospho-null mutant caused a 9-fold increase in multinucleation at 48h post-transfection. Electron microscopy revealed D52 expression induced a marked accumulation of vesicles along the mid-line between nuclei where the final stages of cell abscission normally occurs. Supporting this, D52wt strongly colocalized on vesicular structures containing the endosomal regulatory protein vesicle associated membrane protein 8 (VAMP 8) and this colocalization significantly increased with elevations in cellular Ca(2+). As VAMP 8 is known to be necessary for the endo-membrane fusion reactions that mediate the final stages of cytokinesis, these data indicate that D52 expression and phosphorylation at serine 136 play an important role in supporting the Ca(2+)-dependent membrane trafficking events necessary for cytokinesis in rapidly proliferating cancer cells.

Radiation pharmacogenomics: a genome-wide association approach to identify radiation response biomarkers using human lymphoblastoid cell lines

Radiation therapy is used to treat half of all cancer patients. Response to radiation therapy varies widely among patients. Therefore, we performed a genome-wide association study (GWAS) to identify biomarkers to help predict radiation response using 277 ethnically defined human lymphoblastoid cell lines (LCLs). Basal gene expression levels and 1.3 million genome-wide single nucleotide polymorphism (SNP) markers from both Affymetrix and Illumina platforms were assayed for all 277 human LCLs. MTS [3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium] assays for radiation cytotoxicity were also performed to obtain area under the curve (AUC) as a radiation response phenotype for use in the association studies. Functional validation of candidate genes, selected from an integrated analysis that used SNP, expression, and AUC data, was performed with multiple cancer cell lines using specific siRNA knockdown, followed by MTS and colony-forming assays. A total of 27 loci, each containing at least two SNPs within 50 kb with P-values less than 10(-4) were associated with radiation AUC. A total of 270 expression probe sets were associated with radiation AUC with P < 10(-3). The integrated analysis identified 50 SNPs in 14 of the 27 loci that were associated with both AUC and the expression of 39 genes, which were also associated with radiation AUC (P < 10(-3)). Functional validation using siRNA knockdown in multiple tumor cell lines showed that C13orf34, MAD2L1, PLK4, TPD52, and DEPDC1B each significantly altered radiation sensitivity in at least two cancer cell lines. Studies performed with LCLs can help to identify novel biomarkers that might contribute to variation in response to radiation therapy and enhance our understanding of mechanisms underlying that variation.

MAL2 and tumor protein D52 (TPD52) are frequently overexpressed in ovarian carcinoma, but differentially associated with histological subtype and patient outcome

BACKGROUND

The four-transmembrane MAL2 protein is frequently overexpressed in breast carcinoma, and MAL2 overexpression is associated with gain of the corresponding locus at chromosome 8q24.12. Independent expression microarray studies predict MAL2 overexpression in ovarian carcinoma, but these had remained unconfirmed. MAL2 binds tumor protein D52 (TPD52), which is frequently overexpressed in ovarian carcinoma, but the clinical significance of MAL2 and TPD52 overexpression was unknown.

METHODS

Immunohistochemical analyses of MAL2 and TPD52 expression were performed using tissue microarray sections including benign, borderline and malignant epithelial ovarian tumours. Inmmunohistochemical staining intensity and distribution was assessed both visually and digitally.

RESULTS

MAL2 and TPD52 were significantly overexpressed in high-grade serous carcinomas compared with serous borderline tumours. MAL2 expression was highest in serous carcinomas relative to other histological subtypes, whereas TPD52 expression was highest in clear cell carcinomas. MAL2 expression was not related to patient survival, however high-level TPD52 staining was significantly associated with improved overall survival in patients with stage III serous ovarian carcinoma (log-rank test, p < 0.001; n = 124) and was an independent predictor of survival in the overall carcinoma cohort (hazard ratio (HR), 0.498; 95% confidence interval (CI), 0.34-0.728; p < 0.001; n = 221), and in serous carcinomas (HR, 0.440; 95% CI, 0.294-0.658; p < 0.001; n = 182).

CONCLUSIONS

MAL2 is frequently overexpressed in ovarian carcinoma, and TPD52 overexpression is a favourable independent prognostic marker of potential value in the management of ovarian carcinoma patients.

Adiponectin represses colon cancer cell proliferation via AdipoR1- and -R2-mediated AMPK activation

In obesity, dysregulation of adipocytokines is involved in several pathological conditions including diabetes and certain cancers. As a member of the adipocytokines, adiponectin plays crucial roles in whole-body energy homeostasis. Recently, it has been reported that the level of plasma adiponectin is reduced in several types of cancer patients. However, it is largely unknown whether and how adiponectin affects colon cancer cell growth. Here, we show that adiponectin suppresses the proliferation of colon cancer cells including HCT116, HT29, and LoVo. In colon cancer cells, adiponectin attenuated cell cycle progression at the G(1)/S boundary and concurrently increased expression of cyclin-dependent kinase inhibitors such as p21 and p27. Adiponectin stimulated AMP-activated protein kinase (AMPK) phosphorylation whereas inhibition of AMPK activity blunted the effect of adiponectin on the proliferation of colon cancer cells. Furthermore, knockdown of adiponectin receptors such as AdipoR1 and AdipoR2 relieved the suppressive effect of adiponectin on the growth of colon cancer cells. In addition, adiponectin repressed the expression of sterol regulatory element binding protein-1c, which is a key lipogenic transcription factor associated with colon cancers. These results suggest that adiponectin could inhibit the growth of colon cancer cells through stimulating AMPK activity.

Comparative proteomic analysis of anti-benzo(a)pyrene-7,8-dihydrodiol-9,10-epoxide-transformed and normal human bronchial epithelial G0/G1 cells

In the present study, we investigated the proteomic profiling of anti-benzo(a)pyrene-7,8-dihydrodiol-9,10-epoxide (anti-BPDE)-transformed human bronchial epithelial cell line (16HBE-C) and its parental cell line (16HBE) G0/G1 cells. Differential analysis of proteomic profiling indicated that 67 polypeptides were down-regulated and 77 polypeptides were up-regulated in 16HBE-C G0/G1 cells compared to 16HBE G0/G1 cells. Then 16 differentially expressed protein spots were analyzed with Q-TOF MS/MS. Of these spots, 3 down-regulated polypeptides were identified as sorcin, small ubiquitin-related modifier 2 precursor and eukaryotic translation initiation factor 5A-1, and 9 up-regulated polypeptides were identified as calmodulin, myosin light polypeptide 6, eukaryotic translation initiation factor 6, proliferating cell nuclear antigen (PCNA), tumor protein D52 (TPD52), superoxide dismutase [Cu-Zn], prohibitin, nuclear protein Hcc-1 and vimentin. These proteins are involved in cell proliferation, protein synthesis, signal transduction and carcinogenesis. Western blotting analysis verified the increased expression levels of PCNA and TPD52 in 16HBE-C G0/G1 cells. Based on the clues from proteomic analysis, the migration and invasion capabilities of 16HBE-C and 16HBE cells were tested. The results indicated that 16HBE-C cells showed much higher migration and invasion capabilities than 16HBE cells, and moreover, the suppression of TPD52 by RNAi resulted in significant decrease of migration and invasion capabilities of 16HBE-C cells. These results will be valuable for further investigating and understanding the mechanisms underlying BaP-induced carcinogenesis.

Tumor protein D52 expression and Ca2+-dependent phosphorylation modulates lysosomal membrane protein trafficking to the plasma membrane

Tumor protein D52 (also known as CRHSP-28) is highly expressed in multiple cancers and tumor-derived cell lines; however, it is normally abundant in secretory epithelia throughout the digestive system, where it has been implicated in Ca(2+)-dependent digestive enzyme secretion (41). Here we demonstrate, using site-specific mutations, that Ca(2+)-sensitive phosphorylation at serine 136 modulates the accumulation of D52 at the plasma membrane within 2 min of cell stimulation. When expressed in Chinese hamster ovary CHO-K1 cells, D52 colocalized with adaptor protein AP-3, Rab27A, vesicle-associated membrane protein VAMP7, and lysosomal-associated membrane protein LAMP1, all of which are present in lysosome-like secretory organelles. Overexpression of D52 resulted in a marked accumulation of LAMP1 on the plasma membrane that was further enhanced following elevation of cellular Ca(2+). Strikingly, mutation of serine 136 to alanine abolished the Ca(2+)-stimulated accumulation of LAMP1 at the plasma membrane whereas phosphomimetic mutants constitutively induced LAMP1 plasma membrane accumulation independent of elevated Ca(2+). Identical results were obtained for endogenous D52 in normal rat kidney and HeLA cells, where both LAMP1 and D52 rapidly accumulated on the plasma membrane in response to elevated cellular Ca(2+). Finally, D52 induced the uptake of LAMP1 antibodies from the cell surface in accordance with both the level of D52 expression and phosphorylation at serine 136 demonstrating that D52 altered the plasma membrane recycling of LAMP1-associated secretory vesicles. These findings implicate both D52 expression and Ca(2+)-dependent phosphorylation at serine 136 in lysosomal membrane trafficking to and from the plasma membrane providing a novel Ca(2+)-sensitive pathway modulating the lysosome-like secretory pathway.

Memory and cellular immunity induced by a DNA vaccine encoding self antigen TPD52 administered with soluble GM-CSF

Tumor protein D52 (TPD52) is involved in cellular transformation, proliferation and metastasis. TPD52 over expression has been demonstrated in several cancers including prostate, breast, and ovarian carcinomas. Murine TPD52 (mD52) has been shown to induce anchorage independent growth in vitro and metastasis in vivo, and mirrors the function and normal tissue expression patterns of the human orthologue of TPD52. We believe TPD52 represents a self, non-mutated tumor associated antigen (TAA) important for maintaining a transformed and metastatic cellular phenotype. The transgenic adeno-carcinoma of the mouse prostate (TRAMP) model was employed to study mD52 as a vaccine antigen. Naïve mice were immunized with either recombinant mD52 protein or plasmid DNA encoding the full-length cDNA of mD52. Following immunization, mice were challenged with a subcutaneous, tumorigenic dose of mD52 positive, autochthonous TRAMP-C1 tumor cells. Sixty percent of mice were tumor free 85 days post challenge with TRAMP-C1 when immunized with mD52 as a DNA-based vaccine admixed with soluble granulocyte-macrophage colony stimulating factor (GM-CSF). Survivors of the initial tumor challenge rejected a second tumor challenge given in the opposite flank approximately 150 days after the first challenge, and remained tumor free for more than an additional 100 days. The T cell cytokine secretion patterns from tumor challenge survivors indicated that a T(H)1-type cellular immune response was involved in tumor protection. These data suggest that mD52 vaccination induced a memory, cellular immune response that resulted in protection from murine prostate tumors that naturally over express mD52 protein.

Overlapping synthetic peptides encoding TPD52 as breast cancer vaccine in mice: prolonged survival

Peptide-based vaccines, one of several anti-tumor immunization strategies currently under investigation, can elicit both MHC Class I-restricted (CD8(+)) and Class II-restricted (CD4(+)) responses. However, the need to identify specific T-cell epitopes in the context of MHC alleles has hampered the application of this approach. We have tested overlapping synthetic peptides (OSP) representing a tumor antigen as a novel approach that bypasses the need for epitope mapping, since OSP contain all possible epitopes for both CD8(+) and CD4(+) T cells. Here we report that vaccination of inbred and outbred mice with OSP representing tumor protein D52 (TPD52-OSP), a potential tumor antigen target for immunotherapy against breast, prostate, and ovarian cancer, was safe and induced specific CD8(+) and CD4(+) T-cell responses, as demonstrated by development of specific cytotoxic T cell (CTL) activity, proliferative responses, interferon (IFN)-gamma production and CD107a/b expression in all mice tested. In addition, TPD52-OSP-vaccinated BALB/c mice were challenged with TS/A breast carcinoma cells expressing endogenous TPD52; significant survival benefits were noted in vaccine recipients compared to unvaccinated controls (p<0.001). Our proof-of-concept data demonstrate the safety and efficacy of peptide library-based cancer vaccines that obviates the need to identify epitopes or MHC backgrounds of the vaccinees. We show that an OSP vaccination approach can assist in the disruption of self-tolerance and conclude that our approach may hold promise for immunoprevention of early-stage cancers in a general population.

TCEB1 promotes invasion of prostate cancer cells

Amplification of the long arm of chromosome 8 is one of the most recurrent findings in prostate cancer and it is associated with poor prognosis. Several minimal regions of amplification suggest multiple target genes which are yet to be identified. We have previously shown that TCEB1, EIF3S3, KIAA0196 and RAD21 are amplified and overexpressed in prostate cancer and they are located in the 8q area. In this study, we examined the functional effects of these genes to prostate cancer cell phenotype. We overexpressed and inhibited the genes by lentivirus mediated overexpression and RNA interference, respectively. shRNA mediated TCEB1 silencing decreased significantly cellular invasion of PC-3 and DU145 cells through Matrigel. TCEB1 silencing reduced the anchorage-independent growth of PC-3 cells. Similar effects were not seen with any other genes. When overexpressed in NIH 3T3 cells, TCEB1 and EIF3S3 increased the growth rate of the cells. Transcriptional profiling of TCEB1 silenced PC-3 cells revealed decrease of genes involved in invasion and metastasis. Finally, we also confirmed here the overexpression of TCEB1 in hormone-refractory prostate tumors. This study indicates that TCEB1 promotes invasion of prostate cancer cells, is involved in development of hormone-refractory prostate cancer and is thereby a strong candidate to be one of the target genes for the 8q gain.

Altered expression of tumor protein D52 regulates apoptosis and migration of prostate cancer cells

Tumor protein D52 (TPD52) is a protein found to be overexpressed in prostate and breast cancer due to gene amplification. However, its physiological function remains under investigation. In the present study, we investigated the response of the LNCaP human prostate carcinoma cell line to deregulation of TPD52 expression. Proteomic analysis of prostate biopsies showed TPD52 overexpression at the protein level, whereas its transcriptional upregulation was demonstrated by real-time PCR. Transfection of LNCaP cells with a specific small hairpin RNA giving efficient knockdown of TPD52 resulted in significant cell death of the carcinoma LNCaP cells. As demonstrated by activation of caspases (caspase-3 and -9), and by the loss of mitochondrial membrane potential, cell death occurs due to apoptosis. The disruption of the mitochondrial membrane potential indicates that TPD52 acts upstream of the mitochondrial apoptotic reaction. To study the effect of TPD52 expression on cell proliferation, LNCaP cells were either transfected with enhanced green fluorescence protein-TPD52 or a specific small hairpin RNA. Enhanced green fluorescence protein-TPD52 overexpressing cells showed an increased proliferation rate, whereas TPD52-depleted cells showed the reverse effect. Additionally, we demonstrate that exogenous expression of TPD52 promotes cell migration via alphav beta3 integrin in prostate cancer cells through activation of the protein kinase B/Akt signaling pathway. From these results, we conclude that TPD52 plays an important role in various molecular events, particularly in the morphological diversification and dissemination of prostate carcinoma cells, and may be a promising target with respect to developing new therapeutic strategies to treat prostate cancer.

Nonredundant functions for tumor protein D52-like proteins support specific targeting of TPD52

PURPOSE

Tumor protein D52 (TPD52 or D52) is frequently overexpressed in breast and other cancers and present at increased gene copy number. It is, however, unclear whether D52 amplification and overexpression target specific functional properties of the encoded protein.

EXPERIMENTAL DESIGN

The expression of D52-like genes and MAL2 was compared in breast tissues using quantitative reverse transcription-PCR. The functions of human D52 and D53 genes were then compared by stable expression in BALB/c 3T3 fibroblasts and transient gene knockdown in breast carcinoma cell lines. In situ D52 and MAL2 protein expression was analyzed in breast tissue samples using tissue microarray sections.

RESULTS

The D52 (8q21.13), D54 (20q13.33), and MAL2 (8q24.12) genes were significantly overexpressed in breast cancer tissue (n = 95) relative to normal breast (n = 7; P </= 0.005) unlike the D53 gene (6q22.31; P = 0.884). Subsequently, D52-expressing but not D53-expressing 3T3 cell lines showed increased proliferation and anchorage-independent growth capacity, and reduced D52 but not D53 expression in SK-BR-3 cells significantly increased apoptosis. High D52 but not MAL2 expression was significantly associated with reduced overall survival in breast carcinoma patients (log-rank test, P < 0.001; n = 357) and was an independent predictor of survival (hazard ratio, 2.274; 95% confidence interval, 1.228-4.210; P = 0.009; n = 328).

CONCLUSION

D52 overexpression in cancer reflects specific targeting and may contribute to a more proliferative, aggressive tumor phenotype in breast cancer.

Characterization of dental pulp stem cells of human tooth germs

In previous studies, human dental pulp stem cells (hDPSCs) were mainly isolated from adults. In this present study, we characterized hDPSCs isolated from an earlier developmental stage to evaluate the potential usage of these cells for tissue-regenerative therapy. hDPSCs isolated at the crown-completed stage showed a higher proliferation rate than those isolated at a later stage. When the cells from either group were cultured in medium promoting differentiation toward cells of the osteo/odontoblastic lineage, both became alkaline-phosphatase-positive, produced calcified matrix, and were also capable of forming dentin-like matrix on scaffolds in vivo. However, during long-term passage, these cells underwent a change in morphology and lost their differentiation ability. The results of a DNA array experiment showed that the expression of several genes, such as WNT16, was markedly changed with an increasing number of passages, which might have caused the loss of their characteristics as hDPSCs.

Expression of chloride intracellular channel protein 1 (CLIC1) and tumor protein D52 (TPD52) as potential biomarkers for colorectal cancer

OBJECTIVES

Unequivocal biomarkers are needed to predict susceptibility and progression of colorectal cancer.

DESIGN AND METHODS

Paired samples of tumor and normal tissue from six patients with colorectal cancer of different localization, pTNM stage and grade were employed in the present study. MS analysis was used to identify differentially regulated proteins after 2-DE separation and densitometric analysis.

RESULTS

Densitometric analysis revealed differential abundance of 55 spots in tumor as compared to normal tissues. Thirty nine out of 55 spots were unambiguously identified by MS representing 32 different proteins. CLIC1, TPD52 and FABPL were consistently overexpressed (>3-fold, P<0.05) in all tumor tissue samples, while TPM1, TPM2, TPM3, TAGL and MLRN were consistently down-regulated (>3-fold, P<0.05) compared to normal tissue.

CONCLUSIONS

CLIC1 and TPD52 were significantly (P<0.05) up-regulated in all cases of colorectal cancer investigated, irrespective of localization, pTNM stage and grade of colon cancer highlighting their potential to serve as new biomarkers.

Vaccination with metastasis-related tumor associated antigen TPD52 and CpG/ODN induces protective tumor immunity

Tumor protein D52 (TPD52) is involved in transformation and metastasis and has been shown to be over-expressed in tumor cells compared to normal cells and tissues. Murine TPD52 (mD52) shares 86% protein identity with the human TPD52 orthologue (hD52). To study TPD52 protein as a target for active vaccination recombinant, mD52 was administered as a protein-based vaccine. Naïve mice were immunized with either mD52 protein and CpG/ODN as a molecular adjuvant or CpG/ODN alone. Two weeks following the final immunization, mice were challenged s.c. with syngeneic tumor cells that over-express mD52. Two distinct murine tumor cell lines were used for challenge in this model, mKSA and 3T3.mD52. Half of the mice immunized with mD52 and CpG/ODN rejected or delayed onset of mKSA s.c. tumor cell growth, and 40% of mice challenged with 3T3.mD52 rejected s.c. tumor growth, as well as the formation of spontaneous lethal lung metastases. Mice immunized with mD52 and CpG/ODN generated detectable mD52-specific IgG antibody responses indicating that mD52 protein vaccination induced an adaptive immune response. In addition, mice that rejected tumor challenge generated tumor-specific cytotoxic T lymphocytes' responses. Importantly, microscopic and gross evaluation of organs from mD52 immunized mice revealed no evidence of autoimmunity as assessed by absence of T cell infiltration and absence of microscopic pathology. Together, these data demonstrate that mD52 vaccination induces an immune response that is capable of rejecting tumors that over-express mD52 without the induction of harmful autoimmunity.