TPD52 represents a survival factor in ERBB2-amplified breast cancer cells

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.

Development and validation of a combined hypoxia and ferroptosis prognostic signature for breast cancer

Background

Hypoxia is involved in tumor biological processes and disease progression. Ferroptosis, as a newly discovered programmed cell death process, is closely related to breast cancer (BC) occurrence and development. However, reliable prognostic signatures based on a combination of hypoxia and ferroptosis in BC have not been developed.

Method

We set The Cancer Genome Atlas (TCGA) breast cancer cohort as training set and the Molecular Taxonomy of Breast Cancer International Consortium (METABRIC) BC cohort as the validation set. Least Absolute Shrinkage and Selection Operator (LASSO) and COX regression approaches were used to construct ferroptosis-related genes (FRGs) and hypoxia-related genes (HRGs) prognostic signature (HFRS). The CIBERSORT algorithm and ESTIMATE score were used to explore the relationship between HFRS and tumor immune microenvironment. Immunohistochemical staining was used to detect protein expression in tissue samples. A nomogram was developed to advance the clinical application of HFRS signature.

Results

Ten ferroptosis-related genes and hypoxia-related genes were screened to construct the HFRS prognostic signature in TCGA BC cohort, and the predictive capacity was verified in METABRIC BC cohort. BC patients with high-HFRS had shorter survival time, higher tumor stage, and a higher rate of positive lymph node. Moreover, high HFRS was associated with high hypoxia, ferroptosis, and immunosuppression status. A nomogram that was constructed with age, stage, and HFRS signature showed a strong prognostic capability to predict overall survival (OS) for BC patients.

Conclusion

We developed a novel prognostic model with hypoxia and ferroptosis-related genes to predict OS, and characterize the immune microenvironment of BC patients, which might provide new cures for clinical decision-making and individual treatment of BC patients.

Lipopolysaccharide and statin-mediated immune-responsive protein networks revealed in macrophages through affinity purification spacer-arm controlled cross-linking (AP-SPACC) proteomics

Toll-like receptor 4 (TLR4), a pattern recognition receptor, is activated by lipopolysaccharides (LPS) and induces the MyD88 pathway, which subsequently produces pro-inflammatory cytokines through activation of transcriptional nuclear factor (NF)-κB. Statins have been widely prescribed to reduce cholesterol synthesis for patients with cardiovascular disease. Statins may have pleiotropic effects, which include anti- and pro-inflammatory effects on cells. The molecular mechanism of the sequential influence of LPS and statin on the innate immune system remains unknown. We employed affinity purification-spacer-arm controlled cross-linking (AP-SPACC) MS-based proteomics analysis to identify the LPS- and statin-LPS-responsive proteins and their networks. LPS-stimulated RAW 264.7 macrophage cells singly and combined with the drug statin used in this study. Two chemical cross-linkers with different spacer chain lengths were utilized to stabilize the weak and transient interactors. Proteomic analysis identified 1631 differentially expressed proteins. We identified 151 immune-response proteins through functional enrichment analysis and visualized their interaction networks. Selected candidate protein-coding genes were validated, specifically squamous cell carcinoma antigens recognized by T cells 3, sphingosine-1-phosphate lyase 1, Ras-related protein Rab-35, and tumor protein D52 protein-coding genes through transcript-level expression analysis. The expressions of those genes were significantly increased upon statin treatment and decreased in LPS-stimulated macrophage cells. Therefore, we presumed that the expression changes of genes occurred due to immune response during activation of inflammation. These results highlight the immune-responsive proteins network, providing a new platform for novel investigations and discovering future therapeutic targets for inflammatory diseases.

Prostate cancer cell proliferation is influenced by LDL-cholesterol availability and cholesteryl ester turnover

BACKGROUND

Prostate cancer growth is driven by androgen receptor signaling, and advanced disease is initially treatable by depleting circulating androgens. However, prostate cancer cells inevitably adapt, resulting in disease relapse with incurable castrate-resistant prostate cancer. Androgen deprivation therapy has many side effects, including hypercholesterolemia, and more aggressive and castrate-resistant prostate cancers typically feature cellular accumulation of cholesterol stored in the form of cholesteryl esters. As cholesterol is a key substrate for de novo steroidogenesis in prostate cells, this study hypothesized that castrate-resistant/advanced prostate cancer cell growth is influenced by the availability of extracellular, low-density lipoprotein (LDL)-derived, cholesterol, which is coupled to intracellular cholesteryl ester homeostasis.

METHODS

C4-2B and PC3 prostate cancer cells were cultured in media supplemented with fetal calf serum (FCS), charcoal-stripped FCS (CS-FCS), lipoprotein-deficient FCS (LPDS), or charcoal-stripped LPDS (CS-LPDS) and analyzed by a variety of biochemical techniques. Cell viability and proliferation were measured by MTT assay and Incucyte, respectively.

RESULTS

Reducing lipoprotein availability led to a reduction in cholesteryl ester levels and cell growth in C4-2B and PC3 cells, with concomitant reductions in PI3K/mTOR and p38MAPK signaling. This reduced growth in LPDS-containing media was fully recovered by supplementation of exogenous low-density lipoprotein (LDL), but LDL only partially rescued growth of cells cultured with CS-LPDS. This growth pattern was not associated with changes in androgen receptor signaling but rather increased p38MAPK and MEK1/ERK/MSK1 activation. The ability of LDL supplementation to rescue cell growth required cholesterol esterification as well as cholesteryl ester hydrolysis activity. Further, growth of cells cultured in low androgen levels (CS-FCS) was suppressed when cholesteryl ester hydrolysis was inhibited.

CONCLUSIONS

Overall, these studies demonstrate that androgen-independent prostate cancer cell growth can be influenced by extracellular lipid levels and LDL-cholesterol availability and that uptake of extracellular cholesterol, through endocytosis of LDL-derived cholesterol and subsequent delivery and storage in the lipid droplet as cholesteryl esters, is required to support prostate cancer cell growth. This provides new insights into the relationship between extracellular cholesterol, intracellular cholesterol metabolism, and prostate cancer cell growth and the potential mechanisms linking hypercholesterolemia and more aggressive prostate cancer.

Hsa_circ_0007637 Facilitates Nasopharyngeal Carcinoma Progression by Sponging miR-636/TPD52 Axis

Purpose

Hsa_circ_0007637 was discovered to be differentially expressed in nasopharyngeal carcinoma (NPC). However, the exact function and mechanism of Hsa_circ_0007637 on NPC have not been studied. This study firstly researched the function and mechanism of Hsa_circ_0007637 on NPC progression.

Methods

Hsa_circ_0007637, miR-636 and TPD52 expressions in 80 NPC patients were detected by quantitative real-time polymerase chain reaction. Hsa_circ_0007637 effect on NPC cell proliferation, apopticosis, invasion and migration was investigated by cell counting kit-8 assay, flow cytometry, transwell experiment and wound healing assay accordingly. Dual-luciferase reporter gene assay, RNA immunoprecipitation experiment and RNA fluorescence in situ hybridization experiment were performed to identify the binding between Hsa_circ_0007637 and miR-636. Dual-luciferase reporter gene assay and RNA pull down assay were conducted to verify the binding between miR-636 and TPD52. TPD52 protein expression in NPC cells was determined by Western blot. In vivo study was performed using nude mice. Immunohistochemistry was performed to assess TPD52 and Ki67 expression in tissues.

Results

Hsa_circ_0007637 was overexpressed in NPC tissues and cells. High Hsa_circ_0007637 expression predicted a poor outcome for NPC patients. Hsa_circ_0007637 knockdown decreased proliferation, invasion, migration and increased apoptosis of NPC cells (P < 0.01). Hsa_circ_0007637 could enhance TPD52 expression via sponging miR-636. miR-636 overexpression or TPD52 knockdown weakened the promoting effect of Hsa_circ_0007637 on NPC cells malignant phenotype (P < 0.01). Hsa_circ_0007637 knockdown suppressed NPC cells growth in vivo (P < 0.01).

Conclusion

Hsa_circ_0007637 facilitates NPC progression by sponging miR-636/TPD52 axis.

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.

Unravelling Structure, Localization, and Genetic Crosstalk of KLF3 in Human Breast Cancer

Breast cancer is the most prevailing disease among women. It actually develops from breast tissue and has heterogeneous and complex nature that constitutes multiple tumor quiddities. These features are associated with different histological forms, distinctive biological characteristics, and clinical patterns. The predisposition of breast cancer has been attributed to a number of genetic factors, associated with the worst outcomes. Unfortunately, their behavior with relevance to clinical significance remained poorly understood. So, there is a need to further explore the nature of the disease at the transcriptome level. The focus of this study was to explore the influence of Krüppel-like factor 3 (KLF3), tumor protein D52 (TPD52), microRNA 124 (miR-124), and protein kinase C epsilon (PKCε) expression on breast cancer. Moreover, this study was also aimed at predicting the tertiary structure of KLF3 protein. Expression of genes was analyzed through real-time PCR using the delta cycle threshold method, and statistical significance was calculated by two-way ANOVA in Graphpad Prism. For the construction of a 3D model, various bioinformatics software programs, Swiss Model and UCSF Chimera, were employed. The expression of KLF3, miR-124, and PKCε genes was decreased (fold change: 0.076443, 0.06969, and 0.011597, respectively). However, there was 2-fold increased expression of TPD52 with p value < 0.001 relative to control. Tertiary structure of KLF3 exhibited 80.72% structure conservation with its template KLF4 and was 95.06% structurally favored by a Ramachandran plot. These genes might be predictors of stage, metastasis, receptor, and treatment status and used as new biomarkers for breast cancer diagnosis. However, extensive investigations at the tissue level and in in vivo are required to further strengthen their role as a potential biomarker for prognosis of breast cancer.

Cholesterol and Mevalonate: Two Metabolites Involved in Breast Cancer Progression and Drug Resistance through the ERRα Pathway

Breast cancer is the second greatest cause of cancer-related death in women. Resistance to endocrine treatments or chemotherapy is a limiting drawback. In this context, this work aims to evaluate the effects of cholesterol and mevalonate during tumor progression and their contribution in the onset of resistance to clinical treatments in use today. In this study, we demonstrated that cholesterol and mevalonate treatments were able to activate the estrogen-related receptor alpha (ERRα) pathway, increasing the expression levels of peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC-1α), ERbB2/human epithelial receptor (HER2), tumor protein D52 (TPD52), and NOTCH2 proteins in breast cancer cells. The activation of this pathway is shown to be responsible for intense metabolic switching, higher proliferation rates, sustained motility, the propagation of cancer stem-like cells (CSCs), and lipid droplet formation. All of these events are related to greater tumor propagation, aggressiveness, and drug resistance. Furthermore, the activation and expression of proteins induced by the treatment with cholesterol or mevalonate are consistent with those obtained from the MCF-7/TAMr cell line, which is largely used as a breast cancer model of acquired endocrine therapy resistance. Altogether, our data indicate that cholesterol and mevalonate are two metabolites implicated in breast cancer progression, aggressiveness, and drug resistance, through the activation of the ERRα pathway. Our findings enable us to identify the ERRα receptor as a poor prognostic marker in patients with breast carcinoma, suggesting the correlation between cholesterol/mevalonate and ERRα as a new possible target in breast cancer treatment.

miR-103a-3p Suppresses Cell Proliferation and Invasion by Targeting Tumor Protein D52 in Prostate Cancer

Growing evidence points at an association between microRNAs and tumor development. Although dysregulation of microRNA-103a-3p (miR-103a-3p) in multiple human cancers has been reported, its expression in prostate cancer (PCa) remains unknown and there is currently no research on the relationship between miR-103a-3p and tumor protein D52 (TPD52) in PCa. Our aim in this study was to explore the effect and potential mechanism of miR-103a-3p in PCa. qRT-PCR was performed to detected the level of miR-103a-3p in PCa tissues and cells, and in normal tissues. Colony, wound-healing, invasion, proliferation, and apoptosis assays were performed in search miR-103a-3p effect in PCa. TargetScan was used to predict potential targets of miR-103a-3p. Additionally, dual-luciferase reporter, western blot, and immunofluorescence assays were performed to detected the target gene of miR-103a-3p. Finally, we explore the differences in tumor xenograft experiments between nude mice injected with stably miR-103a-3p expressing cells and those expressing a miR-negative control. Low level of miR-103a-3p was detected in PCa tissues and cells, when compared with normal tissues. Enhancement of miR-103a-3p significantly inhibited migration and invasion of PCa cells, and negatively regulated expression of the oncogenic tumor protein D52 (TPD52) through direct binding to its 3'-UTR. Interestingly, overexpression of TPD52 significantly attenuated the effect of mir-103a-3p on PCa. Our study provides the first evidence that miR-103a-3p directly targets TPD52 and inhibits the proliferation and invasion of PCa. This finding helps clarify the role of mir-103a-3p-TPD52 axis in PCa and may provide new therapeutic targets for the disease.

RNA-sequence-based microRNA expression signature in breast cancer: tumor-suppressive miR-101-5p regulates molecular pathogenesis

Aberrantly expressed microRNA (miRNA) are known to disrupt intracellular RNA networks in cancer cells. Exploring miRNA-dependent molecular networks is a major challenge in cancer research. In this study, we performed RNA-sequencing of breast cancer (BrCa) clinical specimens to identify tumor-suppressive miRNA in BrCa. In total, 64 miRNA were identified as candidate tumor-suppressive miRNA in BrCa cells. Analysis of our BrCa signature revealed that several miRNA duplexes (guide strand/passenger strand) derived from pre-miRNA were downregulated in BrCa tissues (e.g. miR-99a-5p/-3p, miR-101-5p/-3p, miR-126-5p/-3p, miR-143-5p/-3p, and miR-144-5p/-3p). Among these miRNA, we focused on miR-101-5p, the passenger strand of pre-miR-101, and investigated its tumor-suppressive roles and oncogenic targets in BrCa cells. Low expression of miR-101-5p predicted poor prognosis in patients with BrCa (overall survival rate: P = 0.0316). Ectopic expression of miR-101-5p attenuated aggressive phenotypes, e.g. proliferation, migration, and invasion, in BrCa cells. Finally, we identified seven putative oncogenic genes (i.e. High Mobility Group Box 3, Epithelial splicing regulatory protein 1, GINS complex subunit 1 (GINS1), Tumor Protein D52, Serine/Arginine-Rich Splicing Factor Kinase 1, Vang-like protein 1, and Mago Homolog B) regulated by miR-101-5p in BrCa cells. The expression of these target genes was associated with the molecular pathogenesis of BrCa. Furthermore, we explored the oncogenic roles of GINS1, whose function had not been previously elucidated, in BrCa cells. Aberrant expression of GINS1 mRNA and protein was observed in BrCa clinical specimens, and high GINS1 expression significantly predicted poor prognosis in patients with BrCa (overall survival rate: P = 0.0126). Knockdown of GINS1 inhibited the malignant features of BrCa cells. Thus, identification of tumor-suppressive miRNA and molecular networks controlled by these miRNA in BrCa cells may be an effective strategy for elucidation of the molecular pathogenesis of this disease.

Star-PAP regulates tumor protein D52 through modulating miR-449a/34a in breast cancer

Tumor protein D52 (TPD52) is an oncogene amplified and overexpressed in various cancers. Tumor-suppressive microRNA-449a and microRNA-34a (miR-449a/34a) were recently reported to inhibit breast cancer cell migration and invasion via targeting TPD52. However, the upstream events are not clearly defined. Star-PAP is a non-canonical poly (A) polymerase which could regulate the expression of many miRNAs and mRNAs, but its biological functions are not well elucidated. The present study aimed to explore the regulative roles of Star-PAP in miR-449a/34a and TPD52 expression in breast cancer. We observed a negative correlation between the expression of TPD52 and Star-PAP in breast cancer. Overexpression of Star-PAP inhibited TPD52 expression, while endogenous Star-PAP knockdown led to increased TPD52. Furthermore, RNA immunoprecipitation assay suggested that Star-PAP could not bind to TPD52, independent of the 3′-end processing. RNA pull-down assay showed that Star-PAP could bind to 3′region of miR-449a. In line with these results, blunted cell proliferation or cell apoptosis caused by Star-PAP was rescued by overexpression of TPD52 or downregulation of miR-449a/34a. Our findings identified that Star-PAP regulates TPD52 by modulating miR-449a/34a, which may be an important molecular mechanism underlying the tumorigenesis of breast cancer and provide a rational therapeutic target for breast cancer treatment.

Summary: Star-PAP is an important regulator of miR-449a/34a and was first identified indirectly regulating TPD52 via modulating miR-449a/34a. Furthermore, Star-PAP-miR-449a/34a-TPD52 axis is involved in proliferation and apoptosis of breast cancer cells.

Delayed recruiting of TPD52 to lipid droplets - evidence for a "second wave" of lipid droplet-associated proteins that respond to altered lipid storage induced by Brefeldin A treatment

Tumor protein D52 (TPD52) is amplified and overexpressed in breast and prostate cancers which are frequently characterised by dysregulated lipid storage and metabolism. TPD52 expression increases lipid storage in mouse 3T3 fibroblasts, and co-distributes with the Golgi marker GM130 and lipid droplets (LDs). We examined the effects of Brefeldin A (BFA), a fungal metabolite known to disrupt the Golgi structure, in TPD52-expressing 3T3 cells, and in human AU565 and HMC-1-8 breast cancer cells that endogenously express TPD52. Five-hour BFA treatment reduced median LD numbers, but increased LD sizes. TPD52 knockdown decreased both LD sizes and numbers, and blunted BFA's effects on LD numbers. Following BFA treatment for 1-3 hours, TPD52 co-localised with the trans-Golgi network protein syntaxin 6, but after 5 hours BFA treatment, TPD52 showed increased co-localisation with LDs, which was disrupted by microtubule depolymerising agent nocodazole. BFA treatment also increased perilipin (PLIN) family protein PLIN3 but reduced PLIN2 detection at LDs in TPD52-expressing 3T3 cells, with PLIN3 recruitment to LDs preceding that of TPD52. An N-terminally deleted HA-TPD52 mutant (residues 40-184) almost exclusively targeted to LDs in both vehicle and BFA treated cells. In summary, delayed recruitment of TPD52 to LDs suggests that TPD52 participates in a temporal hierarchy of LD-associated proteins that responds to altered LD packaging requirements induced by BFA treatment.

Extracellular Fatty Acids Are the Major Contributor to Lipid Synthesis in Prostate Cancer

Prostate cancer cells exhibit altered cellular metabolism but, notably, not the hallmarks of Warburg metabolism. Prostate cancer cells exhibit increased de novo synthesis of fatty acids (FA); however, little is known about how extracellular FAs, such as those in the circulation, may support prostate cancer progression. Here, we show that increasing FA availability increased intracellular triacylglycerol content in cultured patient-derived tumor explants, LNCaP and C4-2B spheroids, a range of prostate cancer cells (LNCaP, C4-2B, 22Rv1, PC-3), and prostate epithelial cells (PNT1). Extracellular FAs are the major source (∼83%) of carbons to the total lipid pool in all cell lines, compared with glucose (∼13%) and glutamine (∼4%), and FA oxidation rates are greater in prostate cancer cells compared with PNT1 cells, which preferentially partitioned extracellular FAs into triacylglycerols. Because of the higher rates of FA oxidation in C4-2B cells, cells remained viable when challenged by the addition of palmitate to culture media and inhibition of mitochondrial FA oxidation sensitized C4-2B cells to palmitate-induced apoptosis. Whereas in PC-3 cells, palmitate induced apoptosis, which was prevented by pretreatment of PC-3 cells with FAs, and this protective effect required DGAT-1-mediated triacylglycerol synthesis. These outcomes highlight for the first-time heterogeneity of lipid metabolism in prostate cancer cells and the potential influence that obesity-associated dyslipidemia or host circulating has on prostate cancer progression. IMPLICATIONS: Extracellular-derived FAs are primary building blocks for complex lipids and heterogeneity in FA metabolism exists in prostate cancer that can influence tumor cell behavior.

Heterogeneity of fatty acid metabolism in breast cancer cells underlies differential sensitivity to palmitate-induced apoptosis

Breast cancer (BrCa) metabolism is geared toward biomass synthesis and maintenance of reductive capacity. Changes in glucose and glutamine metabolism in BrCa have been widely reported, yet the contribution of fatty acids (FAs) in BrCa biology remains to be determined. We recently reported that adipocyte coculture alters MCF-7 and MDA-MB-231 cell metabolism and promotes proliferation and migration. Since adipocytes are FA-rich, and these FAs are transferred to BrCa cells, we sought to elucidate the FA metabolism of BrCa cells and their response to FA-rich environments. MCF-7 and MDA-MB-231 cells incubated in serum-containing media supplemented with FAs accumulate extracellular FAs as intracellular triacylglycerols (TAG) in a dose-dependent manner, with MDA-MB-231 cells accumulating more TAG. The differences in TAG levels were a consequence of distinct differences in intracellular partitioning of FAs, and not due to differences in the rate of FA uptake. Specifically, MCF-7 cells preferentially partition FAs into mitochondrial oxidation, whereas MDA-MB-231 cells partition FAs into TAG synthesis. These differences in intracellular FA handling underpin differences in the sensitivity to palmitate-induced lipotoxicity, with MDA-MB-231 cells being highly sensitive, whereas MCF-7 cells are partially protected. The attenuation of palmitate-induced lipotoxicity in MCF-7 cells was reversed by inhibition of FA oxidation. Pretreatment of MDA-MB-231 cells with FAs increased TAG synthesis and reduced palmitate-induced apoptosis. Our results provide novel insight into the potential influences of obesity on BrCa biology, highlighting distinct differences in FA metabolism in MCF-7 and MDA-MB-231 cells and how lipid-rich environments modulate these effects.

Androgen-dependent alternative mRNA isoform expression in prostate cancer cells

Background: Androgen steroid hormones are key drivers of prostate cancer. Previous work has shown that androgens can drive the expression of alternative mRNA isoforms as well as transcriptional changes in prostate cancer cells. Yet to what extent androgens control alternative mRNA isoforms and how these are expressed and differentially regulated in prostate tumours is unknown. Methods: Here we have used RNA-Seq data to globally identify alternative mRNA isoform expression under androgen control in prostate cancer cells, and profiled the expression of these mRNA isoforms in clinical tissue. Results: Our data indicate androgens primarily switch mRNA isoforms through alternative promoter selection. We detected 73 androgen regulated alternative transcription events, including utilisation of 56 androgen-dependent alternative promoters, 13 androgen-regulated alternative splicing events, and selection of 4 androgen-regulated alternative 3' mRNA ends. 64 of these events are novel to this study, and 26 involve previously unannotated isoforms. We validated androgen dependent regulation of 17 alternative isoforms by quantitative PCR in an independent sample set. Some of the identified mRNA isoforms are in genes already implicated in prostate cancer (including LIG4, FDFT1 and RELAXIN), or in genes important in other cancers (e.g. NUP93 and MAT2A). Importantly, analysis of transcriptome data from 497 tumour samples in the TGCA prostate adenocarcinoma (PRAD) cohort identified 13 mRNA isoforms (including TPD52, TACC2 and NDUFV3) that are differentially regulated in localised prostate cancer relative to normal tissue, and 3 ( OSBPL1A, CLK3 and TSC22D3) which change significantly with Gleason grade and  tumour stage. Conclusions: Our findings dramatically increase the number of known androgen regulated isoforms in prostate cancer, and indicate a highly complex response to androgens in prostate cancer cells that could be clinically important.

Engineered Exosomes for Targeted Transfer of siRNA to HER2 Positive Breast Cancer Cells

Exosomes are the best options for gene targeting, because of their natural, nontoxic, non-immunogenic, biodegradable, and targetable properties. By engineering exosome-producing cells, ligands can be expressed fusing with exosomal surface proteins for targeting cancer cell receptors. In the present study, HER2-positive breast cancer cells were targeted with a modified exosome producing engineered HEK293T cell. For this purpose, the HEK293T cells were transduced by a lentiviral vector bearing-LAMP2b-DARPin G3 chimeric gene. Stable cells expressing the fusion protein were selected, and the exosomes produced by these cells were isolated from the culture medium, characterized, and then loaded with siRNA for subsequent delivery to the SKBR3 cells. Our results showed that stable HEK293T cells produced DARPin G3 on the surface of exosomes. These exosomes can bind specifically to HER2/Neu and are capable of delivering siRNA molecules against TPD52 gene into SKBR3 cell line down-regulating the gene expression up to 70%. Present approach is envisaged to facilitate genes and drugs transfer to HER2 cancer cells providing additional option for gene therapy and drug delivery.

Mutational profiles of breast cancer metastases from a rapid autopsy series reveal multiple evolutionary trajectories

Heterogeneity within and among tumors in a metastatic cancer patient is a well-established phenomenon that may confound treatment and accurate prognosis. Here, we used whole-exome sequencing to survey metastatic breast cancer tumors from 5 patients in a rapid autopsy program to construct the origin and genetic development of metastases. Metastases were obtained from 5 breast cancer patients using a rapid autopsy protocol and subjected to whole-exome sequencing. Metastases were evaluated for sharing of somatic mutations, correlation of copy number variation and loss of heterozygosity, and genetic similarity scores. Pathological features of the patients' disease were assessed by immunohistochemical analyses. Our data support a monoclonal origin of metastasis in 3 cases, but in 2 cases, metastases arose from at least 2 distinct subclones in the primary tumor. In the latter 2 cases, the primary tumor presented with mixed histologic and pathologic features, suggesting early divergent evolution within the primary tumor with maintenance of metastatic capability in multiple lineages. We used genetic and histopathological evidence to demonstrate that metastases can be derived from a single or multiple independent clones within a primary tumor. This underscores the complexity of breast cancer clonal evolution and has implications for how best to determine and implement therapies for early- and late-stage disease.

Global proteomic profiling in multistep hepatocarcinogenesis and identification of PARP1 as a novel molecular marker in hepatocellular carcinoma

The more accurate biomarkers have long been desired for hepatocellular carcinoma (HCC). Here, we characterized global large-scale proteomics of multistep hepatocarcinogenesis in an attempt to identify novel biomarkers for HCC. Quantitative data of 37874 sequences and 3017 proteins during hepatocarcinogenesis were obtained in cohort 1 of 75 samples (5 pooled groups: normal livers, hepatitis livers, cirrhotic livers, peritumoral livers, and HCC tissues) by iTRAQ 2D LC-MS/MS. The diagnostic performance of the top six most upregulated proteins in HCC group and HSP70 as reference were subsequently validated in cohort 2 of 114 samples (hepatocarcinogenesis from normal livers to HCC) using immunohistochemistry. Of seven candidate protein markers, PARP1, GS and NDRG1 showed the optimal diagnostic performance for HCC. PARP1, as a novel marker, showed comparable diagnostic performance to that of classic markers GS and NDRG1 in HCC (AUCs = 0.872, 0.856 and 0.792, respectively). A significant higher AUC of 0.945 was achieved when three markers combined. For diagnosis of HCC, the sensitivity and specificity were 88.2% and 81.0% when at least two of the markers were positive. Similar diagnostic values of PARP1, GS and NDRG1 were confirmed by immunohistochemistry in cohort 3 of 180 HCC patients. Further analysis indicated that PARP1 and NDRG1 were associated with some clinicopathological features, and the independent prognostic factors for HCC patients. Overall, global large-scale proteomics on spectrum of multistep hepatocarcinogenesis are obtained. PARP1 is a novel promising diagnostic/prognostic marker for HCC, and the three-marker panel (PARP1, GS and NDRG1) with excellent diagnostic performance for HCC was established.

Widespread alternative exon usage in clinically distinct subtypes of Invasive Ductal Carcinoma

Cancer cells can have different patterns of exon usage of individual genes when compared to normal tissue, suggesting that alternative splicing may play a role in shaping the tumor phenotype. The discovery and identification of gene variants has increased dramatically with the introduction of RNA-sequencing technology, which enables whole transcriptome analysis of known, as well as novel isoforms. Here we report alternative splicing and transcriptional events among subtypes of invasive ductal carcinoma in The Cancer Genome Atlas (TCGA) Breast Invasive Carcinoma (BRCA) cohort. Alternative exon usage was widespread, and although common events were shared among three subtypes, ER+ HER2−, ER− HER2−, and HER2+, many events on the exon level were subtype specific. Additional RNA-seq analysis was carried out in an independent cohort of 43 ER+ HER2− and ER− HER2− primary breast tumors, confirming many of the exon events identified in the TCGA cohort. Alternative splicing and transcriptional events detected in five genes, MYO6, EPB41L1, TPD52, IQCG, and ACOX2 were validated by qRT-PCR in a third cohort of 40 ER+ HER2− and ER− HER2− patients, showing that these events were truly subtype specific.

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.

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.

Dropping in on the lipid droplet- tumor protein D52 (TPD52) as a new regulator and resident protein

Lipid droplets are essential for both the storage and retrieval of excess cellular nutrients, and their biology is regulated by a diverse range of cellular proteins, some of which function at the lipid droplet. Numerous studies have characterized lipid droplet proteomes in different organisms and cell types, and RNAi whole genome screening studies have examined the genetic regulation of lipid storage in C. elegans and D. melanogaster. While tumor protein D52 (TPD52) did not emerge from earlier studies as a strong candidate, exogenous expression of human TPD52 in cultured cells resulted in significantly increased numbers of lipid droplets, and oleic acid supplementation increased TPD52 detection at both lipid droplets and the Golgi apparatus. These results suggest that direct testing of proteins that are infrequently but recurrently identified in proteomic and RNAi screening studies may identify novel lipid droplet regulators. While the analysis of these possibly lower-abundance or itinerant lipid droplet proteins may be more technically challenging, such proteins could facilitate a more detailed interrogation of emerging aspects of lipid droplet biology.

Decreased TPD52 expression is associated with poor prognosis in primary hepatocellular carcinoma

Tumor protein D52 (TPD52) has been indicated to be involved in tumorigenesis of various malignancies. But its role in hepatocellular carcinoma (HCC) is unknown. This study aimed to explore the expression of TPD52 in HCC samples and cell lines using real-time quantitative PCR, western blotting, and immunohistochemistry. The prognostic value of TPD52 in HCC was also analysed. Meanwhile, the mechanism of TPD52 in hepatocarcinogenesis was further investigated by western blotting, immunohistochemistry, over-express and knockdown studies. We found that TPD52 expression was significantly decreased in the HCC tissues and HCC cell lines. TPD52 expression was significantly correlated with tumor-nodes-metastasis (TNM) stage. Kaplan-Meier survival curves showed that high TPD52 expression was associated with improved overall survival (OS) and disease-free survival (DFS) in HCC patients. Multivariate analysis indicated that TPD52 expression was an independent prognostic marker for the OS and DFS of patients. In addition, TPD52 expression was positively correlated with p21 and p53 expression, and was negatively correlated with MDM2, BCL2 and P-GSK-3β expression in HCC. In conclusions, our findings suggested that TPD52 is a potential tumor suppressor in HCC. It may be a novel prognostic biomarker and molecular therapy target for HCC.

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.

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.

Determination of the protein expression profiles of breast cancer cell lines by quantitative proteomics using iTRAQ labelling and tandem mass spectrometry

Breast cancer is the principal cancer in women worldwide. Although there are serum tumor markers such as CEA and HER2, they are detected in advanced stages of the disease and used as progression and recurrence markers. Therefore, there is a necessity for the identification of new markers that might lead to an early detection and also provide evidence of an effective treatment. The aim of this work was to determine the differential protein expression profiles of four breast cancer cell lines in comparison to a normal control cell line by iTRAQ labelling and tandem mass spectrometry, in order to identify putative biomarkers of the disease. We identified 1,020 iTRAQ-labelled polypeptides with at least one peptide identified with more than 95% in confidence. Overexpressed polypeptides in all cancer cell lines were 78, whilst the subexpressed were 128. We categorised them with PANTHER program into biological processes, being the metabolic pathways the most affected. We detected six groups of proteins with the STRING program involved in DNA topology, glycolysis, translation initiation, splicing, pentose pathway, and proteasome degradation. The main subexpressed protein network included mitochondrial proteins involved in oxidative phosphorylation. We propose BAG6, DDX39, ANXA8 and COX4 as putative biomarkers in breast cancer.

BIOLOGICAL SIGNIFICANCE

We report a set of differentially expressed proteins in the MCF7 and T47D (Luminal A), MDA-MB-231 (Claudin low) and SK-BR-3 (HER2(+)) breast cancer cell lines that have not been previously reported in breast cancer disease. From these proteins, we propose BAG6, DDX39, ANXA8 and COX4 as putative biomarkers in breast cancer. On the other hand, we propose sets of unique polypeptides in each breast cancer cell line that can be useful in the classification of different subtypes of breast cancer.

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.