Role of N-cadherin in proliferation, migration, and invasion of germ cell tumours

Chemotherapy Assessment in Advanced Multicellular 3D Models of Pancreatic Cancer: Unravelling the Importance of Spatiotemporal Mimicry of the Tumor Microenvironment

Pancreatic ductal adenocarcinoma (PDAC) is a challenge for global health with very low survival rate and high therapeutic resistance. Hence, advanced preclinical models for treatment screening are of paramount importance. Herein, chemotherapeutic (gemcitabine) assessment on novel (polyurethane) scaffold-based spatially advanced 3D multicellular PDAC models is carried out. Through comprehensive image-based analysis at the protein level, and expression analysis at the mRNA level, the importance of stromal cells is confirmed, primarily activated stellate cells in the chemoresistance of PDAC cells within the models. Furthermore, it is demonstrated that, in addition to the presence of activated stellate cells, the spatial architecture of the scaffolds, i.e., segregation/compartmentalization of the cancer and stromal zones, affect the cellular evolution and is necessary for the development of chemoresistance. These results highlight that, further to multicellularity, mapping the tumor structure/architecture and zonal complexity in 3D cancer models is important for better mimicry of the in vivo therapeutic response.

Cell adhesion molecule immobilized gold surfaces for enhanced neuron-electrode interfaces

To provide a long-term solution for increasing the biocompatibility of neuroprosthetics, approaches to reduce the side effects of invasive neuro-implantable devices are still in need of improvement. Physical, chemical, and bioactive design aspects of the biomaterials are proven to be important for providing proper cell-to-cell, cell-to-material interactions. Particularly, modification of implant surfaces with bioactive cues, especially cell adhesion molecules (CAMs) that capitalize on native neural adhesion mechanisms, are promising candidates in favor of providing efficient interfaces. Within this concept, this study utilized specific CAMs, namely N-Cadherin (Neural cadherin, N-Cad) and neural cell adhesion molecule (NCAM), to enhance neuron-electrode contact by mimicking the cell-to-ECM interactions for improving the survival of cells and promoting neurite outgrowth. For this purpose, representative gold electrode surfaces were modified with N-Cadherin, NCAM, and the mixture (1:1) of these molecules. Modifications were characterized, and the effect of surface modification on both differentiated and undifferentiated neuroblastoma SH-SY5Y cell lines were compared. The findings demonstrated the successful modification of these molecules which subsequently exhibited biocompatible properties as evidenced by the cell viability results. In cell culture experiments, the CAMs displayed promising results in promoting neurite outgrowth compared to conventional poly-l-lysine coated surfaces, especially NCAM and N-Cad/NCAM modified surfaces clearly showed significant improvement. Overall, this optimized approach is expected to provide an insight into the action mechanisms of cells against the local environment and advance processes for the fabrication of alternative neural interfaces.

Bone Marrow Mesenchymal Stem Cells Release miR-378a-5p-Carried Extracellular Vesicles to Alleviate Rheumatoid Arthritis

This study investigates whether bone marrow mesenchymal stem cell (BMSC)-derived extracellular vesicles (EVs) can affect rheumatoid arthritis (RA) by delivering microRNA (miR)-378a-5p to regulate the interferon regulatory factor 1/signal transducer and transcription 1 (IRF1/STAT1) axis. We identified RA-associated miRNAs using the GEO microarray dataset GSE121894. We found the most important miRNAs in RA synovial tissues using RT-qPCR. BMSC-derived EVs were ultracentrifuged and cocultured with human synovial microvascular endothelial cells (HSMECs) in vitro. Dual-luciferase and RNA immunoprecipitation studies examined miR-378a-5p's specific binding to IRF1. We also measured angiogenesis, migration, and proliferation using CCK-8, Transwell, and tube formation assays. Collagen-induced arthritis (CIA) mice models were created by inducing arthritis and scoring it. RA synovial tissues had low miR-378a-5p expression, whereas BMSC-derived EVs had high levels. The transfer of miR-378a-5p by BMSC-derived EVs to HSMECs boosted proliferation, migration, and angiogenesis. miR-378a-5p inhibited IRF1. MiR-378a-5p-containing BMSC-derived EVs decreased STAT1 phosphorylation and HSMEC IRF1 expression. EVs with miR-378a-5p mimic promoted HSMEC proliferation, migration, and angiogenesis, whereas dexmedetomidine inhibited STAT1 phosphorylation. In CIA mice, BMSC-derived EVs containing miR-378a-5p enhanced synovial vascular remodeling and histopathology. Thus, miR-378a-5p from BMSC-derived EVs promotes HSMEC proliferation, migration, and angiogenesis, inactivating the IRF1/STAT1 axis and preventing RA.

Analysis of connexin 43, connexin 45 and N-cadherin in the human sertoli cell line FS1 and the human seminoma-like cell line TCam-2 in comparison with human testicular biopsies

BACKGROUND

Germ cell tumors are relatively common in young men. They derive from a non-invasive precursor, called germ cell neoplasia in situ, but the exact pathogenesis is still unknown. Thus, further understanding provides the basis for diagnostics, prognostics and therapy and is therefore paramount. A recently developed cell culture model consisting of human FS1 Sertoli cells and human TCam-2 seminoma-like cells offers new opportunities for research on seminoma. Since junctional proteins within the seminiferous epithelium are involved in cell organization, differentiation and proliferation, they represent interesting candidates for investigations on intercellular adhesion and communication in context with neoplastic progression.

METHODS

FS1 and TCam-2 cells were characterized regarding gap-junction-related connexin 43 (Cx43) and connexin 45 (Cx45), and adherens-junction-related N-cadherin using microarray, PCR, Western blot, immunocytochemistry and immunofluorescence. Results were compared to human testicular biopsies at different stages of seminoma development via immunohistochemistry to confirm the cell lines' representativeness. Furthermore, dye-transfer measurements were performed to investigate functional cell coupling.

RESULTS

Cx43, Cx45 and N-cadherin mRNA and protein were generally detectable in both cell lines via qualitative RT-PCR and Western blot. Immunocytochemistry and immunofluorescence revealed a mainly membrane-associated expression of N-cadherin in both cell lines, but gene expression values were higher in FS1 cells. Cx43 expression was also membrane-associated in FS1 cells but barely detectable in TCam-2 cells. Accordingly, a high gene expression value of Cx43 was measured for FS1 and a low value for TCam-2 cells. Cx45 was primary located in the cytoplasm of FS1 and TCam-2 cells and revealed similar low to medium gene expression values in both cell lines. Overall, results were comparable with corresponding biopsies. Additionally, both FS1 and TCam-2 cells showed dye diffusion into neighboring cells.

CONCLUSION

The junctional proteins Cx43, Cx45 and N-cadherin are expressed in FS1 and TCam-2 cells at mRNA and/or protein level in different amounts and localizations, and cells of both lines are functionally coupled among each other. Concerning the expression of these junctional proteins, FS1 and TCam-2 cells are largely representative for Sertoli and seminoma cells, respectively. Thus, these results provide the basis for further coculture experiments evaluating the role of junctional proteins in context with seminoma progression.

The transcription factors Junb and Fosl2 cooperate to regulate Cdh3 expression in 15P-1 Sertoli cells

In Sertoli cells of the testis, cadherins (Cdh) are important cell-to-cell interaction proteins and contribute to the formation of the blood-testis barrier being essential for germ cells' protection. P-cadherin or Cdh3 is only expressed in Sertoli cells from embryonic to prepubertal development. Interestingly, the expression profile of Cdh3 correlates with that of activating protein-1 (AP-1) transcription factors during Sertoli cells development. To assess their potential implications in the regulation of Cdh3, different AP-1 transcription factors were overexpressed in 15P-1 Sertoli cells. We found that the overexpressions of Junb and Fosl2 activated Cdh3 promoter. ChIP-qPCR assay and luciferase reporter assay with 5' promoter deletions and site-directed mutagenesis confirmed the recruitment of Junb and Fosl2 to an AP-1 regulatory element at -47 bp in the proximal region of Cdh3 promoter in 15P-1 cells. These findings were further supported by histone modification markers and chromatin accessibility surrounding Cdh3 promoter in mouse testis. Moreover, the knockdowns of Junb and/or Fosl2 by siRNA decreased Cdh3 protein levels. Taken together, these data suggest that in 15P-1 Sertoli cells, the AP-1 family members Junb and Fosl2 are responsible for the regulation of Cdh3 expression, which requires the recruitment of both factors to the proximal region of the Cdh3 promoter.

Role of Neural (N)-Cadherin in Breast Cancer Cell Stemness and Dormancy in the Bone Microenvironment

Breast cancer cells that interact with spindle-shaped N-Cadherin+ Osteoblasts (SNOs) are recognised to become dormant through a Notch2-dependent mechanism. We found that Notch2High human BrCa MDA-MB231 (MDA) cells also expressed high level of N-Cadherin. This prompted us to hypothesize that N-Cadherin could have a role in MDA-SNO interaction. Of note, the expression of N-Cadherin in MDA cells reduced tumour incidence and bone osteolysis in BrCa mouse model. Moreover, similarly to Notch2High MDA cells, the N-CadherinHigh MDA cells revealed a high expression of the canonical Haematopoietic Stem cell (HSC) markers, suggesting an HSC mimicry, associated with higher ability to form mammospheres. Interestingly, N-CadherinHigh MDA cells showed greater capacity to adhere to SNOs, while the inhibition of SNO-mediating MDA cell proliferation was unremarkable. To investigate whether these features were shared by mouse BrCa, we used the 4T1 cell line in which N-Cadherin expression was abolished and then rescued. At variance with MDA cells, 4T1 cells expressing N-Cadherin revealed that the latter was associated with a lower expression of the HSC marker, Cxcr4, along with a lower capacity to form mammospheres. Furthermore, the rescue of N-Cadherin expression increased cell-cell adhesion and reduced proliferation of 4T1 cells when they were co-plated with SNOs. In conclusion, we demonstrated that: (i) N-CadherinHigh and Notch2High MDA cells showed similar HSC mimicry and dormancy features; (ii) N-Cadherin mediated BrCa-SNO adhesion; (iii) N-Cadherin had a positive Notch2-dependent role on SNO-induced dormancy and HSC mimicry in MDA cells, and a negative role in 4T1 cell stemness and HSC mimicry.

Human giant larvae-1 promotes migration and invasion of malignant glioma cells by regulating N-cadherin

Human giant larvae-1 (Hugl-1) is a human homologue of Drosophila tumor suppressor lethal (2)-giant larvae and has been reported to be involved in the development of human malignancies. Previous studies performed by our group demonstrated that Hugl-1 inhibits glioma cell proliferation in an intracranial model of nude mice. However, the exact molecular mechanisms underlying the participation of Hugl-1 in glioma invasion and migration, and in the depolarizing process remain largely unknown. Utilizing the U251-MG cells with stable expression of Hugl-1, the present study used wound healing, Transwell invasion and western blot assays to explore the role and specific mechanism of Hugl-1 in glioma invasion and migration. The results of the present study demonstrated that overexpression of Hugl-1 decreased cell-cell adhesion and increased cell-cell extracellular matrix adhesion. In addition, overexpression of Hugl-1 promoted pseudopodia formation, glioma cell migration and invasion. The molecular mechanism of action involved the negative regulation of N-cadherin protein levels by Hugl-1. Overexpression or knockdown of N-cadherin partially suppressed or enhanced the effects of Hugl-1 on glioma cell migration and invasion, respectively. Furthermore, Hugl-1 inhibited cell proliferation, while promoting cell migration, which suggests that it may serve a two-sided biological role in cellular processes. Taken together, these results suggest that Hugl-1 promotes the migration and invasion of malignant glioma cells by decreasing N-cadherin expression. Thus, Hugl-1 may be applied in the development of targeted and personalized treatment.

The Cells and Extracellular Matrix of Human Amniotic Membrane Hinder the Growth and Invasive Potential of Bladder Urothelial Cancer Cells

Bladder cancer is one of the most common cancers among men in industrialized countries and on the global level incidence and mortality rates are increasing. In spite of progress in surgical treatment and chemotherapy, the prognosis remains poor for patients with muscle-invasive bladder cancer. Therefore, there is a great need for the development of novel therapeutic approaches. The human amniotic membrane (hAM) is a multi-layered membrane that comprises the innermost part of the placenta. It has unique properties that make it suitable for clinical use, such as the ability to promote wound healing and decrease scarring, low immunogenicity, and immunomodulatory, antimicrobial and anticancer properties. This study aimed to investigate the effect of (i) hAM-derived cells and (ii) hAM scaffolds on the growth dynamics, proliferation rate, and invasive potential of muscle-invasive bladder cancer T24 cells. Our results show that 24 and 48 h of co-culturing T24 cells with hAM-derived cells (at 1:1 and 1:4 ratios) diminished the proliferation rate of T24 cells. Furthermore, when seeded on hAM scaffolds, namely (1) epithelium of hAM (e-hAM), (2) basal lamina of hAM (denuded; d-hAM), and (3) stroma of hAM (s-hAM), the growth dynamic of T24 cells was altered and proliferation was reduced, even more so by the e-hAM scaffolds. Importantly, despite their muscle-invasive potential, the T24 cells did not disrupt the basal lamina of hAM scaffolds. Furthermore, we observed a decrease in the expression of epithelial-mesenchymal transition (EMT) markers N-cadherin, Snail and Slug in T24 cells grown on hAM scaffolds and individual T24 cells even expressed epithelial markers E-cadherin and occludin. Our study brings new knowledge on basic mechanisms of hAM affecting bladder carcinogenesis and the results serve as a good foundation for further research into the potential of hAM-derived cells and the hAM extracellular matrix to serve as a novel bladder cancer treatment.

Global transcriptome study of Dip2B-deficient mouse embryonic lung fibroblast reveals its important roles in cell proliferation and development

Disco-interacting protein 2 homolog B (Dip2B) is a member of Dip2 family encoded by Dip2b gene. Dip2B has been reported to regulate murine epithelial KIT⁺ progenitor cell expansion and differentiation epigenetically via exosomal miRNA targeting during salivary gland organogenesis. However, its molecular functions, cellular activities and biological process remain unstudied. Here, we investigated the transcriptome of Dip2B-deficient mouse embryonic lung fibroblasts (MELFs) isolated from E14.5 embryos by RNA-Seq. Expression profiling identified 1369 and 1104 differentially expressed genes (DEGs) from Dip2b^−/− and Dip2b^+/− MELFs in comparisons to wild-type (Dip2b^+/+). Functional clustering of DEGs revealed that many gene ontology terms belong to membrane activities such as ‘integral component of plasma membrane’, and ‘ion channel activity’, suggesting possible roles of Dip2B in membrane integrity and membrane function. KEGG pathway analysis revealed that multiple metabolic pathways are affected in Dip2b^−/− and Dip2b^+/− when compared to Dip2b^+/+ MELFs. These include ‘protein digestion and absorption’, ‘pancreatic secretion’ and ‘steroid hormone synthesis pathway’. These results suggest that Dip2B may play important roles in metabolism. Molecular function analysis shows transcription factors including Hox-genes, bHLH-genes, and Forkhead-genes are significantly down-regulated in Dip2b^−/− MELFs. These genes are critical in embryo development and cell differentiation. In addition, Dip2B-deficient MELFs demonstrated a reduction in cell proliferation and migration, and an increase in apoptosis. All results indicate that Dip2B plays multiple roles in cell proliferation, migration and apoptosis during embryogenesis and may participate in control of metabolism. This study provides valuable information for further understanding of the function and regulatory mechanisms of Dip2B.

Pinocembrin inhibits the proliferation and migration and promotes the apoptosis of ovarian cancer cells through down-regulating the mRNA levels of N-cadherin and GABAB receptor

There is no previous study on the effect of pinocembrin on ovarian cancer to the best of our knowledge. Moreover, the effects of pinocembrin on the expression of GABAB1 and GABAB2 genes are not studied before. Therefore, this study aimed to investigate effects of pinocembrin on the growth of ovarian cancer cells and the expression of cadherin and GABAB receptor to explore whether pinocembrin was helpful in the treatment of epithelial ovarian cancer. SKOV3 cells were divided into six groups: Control (blank control), DDP (cisplatin as positive control; cells were incubated with 15 μg/ml DDP), 25 μM (cells were incubated with 25 μM pinocembrin), 50 μM (cells were incubated with 50 μM pinocembrin), 100 μM (cells were incubated with 100 μM pinocembrin), and 200 μM (cells were incubated with 200 μM pinocembrin). CCK8 assay, cell scratch assay and Annexin V-FITC/PI staining found that when pinocembrin concentration reached 100 μM and the treatment time reached 48 h, pinocembrin could inhibit the cell proliferation and migration and promote the cell apoptosis, and this effect was enhanced with the increase of pinocembrin concentration. Western blotting found that the protein expression of E-cadherin, N-cadherin, GABAB1 and GABAB2 was not significantly affected by pinocembrin. RT-PCR found that pinocembrin also had no significant influence on the E-cadherin mRNA level, but it could reduce the mRNA levels of N-cadherin, GABAB1 and GABAB2. In conclusion, pinocembrin inhibited the proliferation and migration and promoted the apoptosis of ovarian cancer cells through down-regulating the mRNA levels of N-cadherin and GABAB receptor.

Proteomic Comparison of Malignant Human Germ Cell Tumor Cell Lines

Malignant germ cell tumors (GCT) are the most common malignant tumors in young men between 18 and 40 years. The correct identification of histological subtypes, in difficult cases supported by immunohistochemistry, is essential for therapeutic management. Furthermore, biomarkers may help to understand pathophysiological processes in these tumor types. Two GCT cell lines, TCam-2 with seminoma-like characteristics, and NTERA-2, an embryonal carcinoma-like cell line, were compared by a quantitative proteomic approach using high-resolution mass spectrometry (MS) in combination with stable isotope labelling by amino acid in cell culture (SILAC). We were able to identify 4856 proteins and quantify the expression of 3936. 347 were significantly differentially expressed between the two cell lines. For further validation, CD81, CBX-3, PHF6, and ENSA were analyzed by western blot analysis. The results confirmed the MS results. Immunohistochemical analysis on 59 formalin-fixed and paraffin-embedded (FFPE) normal and GCT tissue samples (normal testis, GCNIS, seminomas, and embryonal carcinomas) of these proteins demonstrated the ability to distinguish different GCT subtypes, especially seminomas and embryonal carcinomas. In addition, siRNA-mediated knockdown of these proteins resulted in an antiproliferative effect in TCam-2, NTERA-2, and an additional embryonal carcinoma-like cell line, NCCIT. In summary, this study represents a proteomic resource for the discrimination of malignant germ cell tumor subtypes and the observed antiproliferative effect after knockdown of selected proteins paves the way for the identification of new potential drug targets.

Exogenous interleukin-1α signaling negatively impacts acquired chemoresistance and alters cell adhesion molecule expression pattern in colorectal carcinoma cells HCT116

Proinflammatory cytokine and chemokine signaling from the tumor microenvironment is thought to be crucial for developing and sustaining colorectal cancer by regulating a multitude of pathways associated with a variety of cellular mechanisms. Among these pathways there is acquired chemoresistance, which is usually a major obstacle in the way towards successful chemotherapeutic treatment of advanced colorectal cancer cases. Despite of an emerging body of data published on the role of cytokine signaling network in cancer, little is known about the effects of the upstream cytokine interleukin-1α (IL-1α) signaling to the cancer cells. In this study we have shown that the increase in exogenous IL-1α signaling increases chemosensitivity of both chemosensitive and chemoresistant colorectal cancer cell lines, treated with a widely used cytotoxic antimetabolite 5-fluorouracil (5-FU). This was a result of increased cell death but not of the changes in 5-FU-induced cell cycle arrest. Noticeably, combined exogenous IL-1α and 5-FU treatment had significant effects on the expression of cell adhesion molecules, suggesting a decrease in adhesion-dependent chemoresistance and, on the other hand, an increase in metastatic potential of the cells. These results lead to a conclusion that modulation of IL-1 receptor activity could have applications as a part of combination therapy for advanced and highly metastatic colorectal cancers.

SIRT6 inhibits proliferation and invasion in osteosarcoma cells by targeting N-cadherin

SIRT6, is a member of the NAD-dependent sirtuin family of enzymes, and has been reported as a novel tumor suppressor gene or oncogene, dependent on the type of cancer. However, the role of SIRT6 in osteosarcoma has not been investigated. The present study demonstrated that the expression of SIRT6 was downregulated in osteosarcoma tissues and osteosarcoma cell lines when compared with adjacent tissues or osteoblastic cell lines. Kaplan-Meier analysis was performed to evaluate the prognostic significance of SIRT6. The overall survival of patients with higher expression of SIRT6 was significantly longer than patients with lower expression. Subsequently, MTT and invasion assays were performed to detect the biological functions of SIRT6 in osteosarcoma cells in vitro. The results revealed that overexpression of SIRT6 inhibited SAOS-2 and MG-63 cell proliferation and invasion. Knockdown of SIRT6 enhanced cell ability for the proliferation and invasion. A qChIP assay, luciferase reporter assay, reverse transcription-quantitative polymerase chain reaction and western blotting confirmed that CDH2 (N-cadherin) was a target of SIRT6. SIRT6 overexpression suppressed N-cadherin on the mRNA and protein levels. In addition, it was confirmed that the promotional effect of Si-SIRT6 on OS cell growth and invasion was suppressed by downregulating N-cadherin. The present study suggested that SIRT6 may serve as a tumor suppressor during the development of osteosarcoma. In addition, N-cadherin may be a promising therapeutic target for osteosarcoma.

[Identification of diagnostic tumour markers and therapeutic targets in testicular tumours]

Today, tumour classification has been expanded due to immunohistochemical and molecular-pathological analyses due to corresponding patterns/profiles of protein and gene expression. The latter analyses often include growth factors and their ligands, intracellular signalling pathways, DNA-binding proteins, and oncogenes and suppressor genes, thus functionally including primarily the regulation of growth including angiogenesis and apoptosis as well as the induction of metastases to adhesion and migration disorders. Based on observations that testicular tumours often show microcalcifications, possibly due to impaired calcium metabolism, we focused on calcium-dependent transmembrane proteins, particularly cadherins, in the search for new tumour markers and therapeutic targets. N‑cadherin is expressed differently in the various subtypes of germ cell tumours and is useful in N‑cadherin-positive germ cell tumours as a novel therapeutic targeting structure, particularly in cisplatin resistance, due to functional analysis. In the tumours of the sex cord stroma beta-catenin and the transcription factor SOX-9 give a clear classification of these tumours. Thus, morphological investigations prove to be pilot experiments to purposefully narrow the spectrum of functionally important proteins and thus to establish promising new differential diagnostic markers or target structures.

Cadherin- and Rigidity-Dependent Growth of Lung Cancer Cells in a Partially Confined Microenvironment

During tumor development, cancer cells constantly confront different types of extracellular barriers. However, fundamental questions like whether tumor cells will continue to grow against confinement or away from it and what key factors govern this process remain poorly understood. To address these issues, here we examined the growth dynamics of human lung epithelial carcinoma A549 cells partially confined in micrometer-sized cylindrical pores with precisely controlled wall stiffness. It was found that, after reaching confluency, the cell monolayer enclosed by a compliant wall was able to keep growing and pushing the boundary, eventually leading to a markedly enlarged pore. In contrast, a much reduced in-plane growth and elevated strain level among cells were observed when the confining wall becomes stiff. Furthermore, under such circumstance, cells switched their growth from within the monolayer to along the out-of-plane direction, resulting in cell stacking. We showed that these observations can be well explained by a simple model taking into account the deformability of the wall and the threshold stress for inhibiting cell growth. Interestingly, cadherins were found to play an important role in the proliferation and stress buildup within the cell monolayer by aggregating at cell-cell junctions. The stiff confinement led to an elevated expression level of cadherins. Furthermore, inhibition of N-cadherin resulted in a significantly suppressed cell growth under the same confining conditions.

Alterations in androgen deprivation enhanced prostate-specific membrane antigen (PSMA) expression in prostate cancer cells as a target for diagnostics and therapy. EJNMMI Res. 2015;5:66. [PMID: 26576996 PMCID: PMC4648835 DOI: 10.1186/s13550-015-0145-8]

BACKGROUND

Prostate-specific membrane antigen (PSMA) is a promising target for diagnostics and therapy of prostate carcinoma (PCa). Based on the hypothesis that PSMA expression can be modulated by variations in androgen deprivation therapy (ADT), we investigated the binding of a PSMA-directed radiopharmaceutical in vitro in order to get an insight of the interactions between altered premedication and PSMA expression before repetitive PSMA-directed PET/CT for therapy response and targeted therapy implementation.

METHODS

The human castration-resistant PCa cell line VCaP (CRPC) was treated with either 1 nmol/L testosterone (T) over 20 passages yielding the androgen-sensitive cell line (revCRPC) or with 5 μmol/L abiraterone acetate (AA) generating the abiraterone-tolerant subtype CRPCAA. In these cell lines, T and AA were varied by either supply or withdrawal of T and AA. PSMA expression of the three cell culture models was detected by Western blot and immunohistochemical staining. For quantitative measurement of tracer uptake, 0.3 nmol/L (68)Ga-labelled PSMA-HBED-CC peptide (100-300 kBq/ml) was added to different treated parallel cultures (n = 9 each). Time-dependent uptake per 10(6) cells of each culture was calculated and evaluated. PSMA mRNA expression was investigated by qPCR.

RESULTS

PSMA expression increased dependently on intensified ADT in all three basic cell lines. (68)Ga-PSMA-HBED-CC uptake almost doubled during 3 h in all cell lines (p < 0.01). Compared to the basic cells, pre-incubation with abiraterone for 48 h resulted in a significant increased uptake in CRPC (p < 0.001). In revCRPC, 48-h AA pre-incubation resulted in an eightfold higher uptake after 3 h (p < 0.001). Additional withdrawal of external testosterone increased the uptake up to tenfold (p < 0.01). The increase of PSMA expression upon ADT and AA treatments was confirmed by qPCR and Western blot data. Furthermore, in CRPCAA, 48-h AA withdrawal increased the uptake up to fivefold (p < 0.01).

CONCLUSIONS

The investigated three PCa cell culture subtypes represent a serial preclinical model of androgen deprivation therapy as a proxy for clinical situations with differing basal PSMA expression. The uptake of PSMA-binding tracers could be stimulated by therapeutic effective short-term variation in premedication in all stages of ADT response. These complex interactions have to be considered in the interpretation of diagnostic imaging using PSMA ligands as well as in the optimal timing of PSMA-based therapies.