Nuclear receptor NURR1 functions to promote stemness and epithelial-mesenchymal transition in prostate cancer via its targeting of Wnt/β-catenin signaling pathway

Dysregulated activation of Wnt/β-catenin signaling pathway is a frequent or common event during advanced progression of multiple cancers. With this signaling activation, it enhances their tumorigenic growth and facilitates metastasis and therapy resistance. Advances show that this signaling pathway can play dual regulatory roles in the control of cellular processes epithelial-mesenchymal transition (EMT) and cancer stemness in cancer progression. Aberrant activation of Wnt/β-catenin signaling pathway is shown to be common in prostate cancer and also castration-resistant prostate cancer (CRPC). However, the transcriptional regulators of this pathway in prostate cancer are still not well characterized. NURR1 (NR4A2) is an orphan nuclear receptor and plays an important role in the development of dopaminergic neurons. Previously, we have shown that NURR1 exhibits an upregulation in isolated prostate cancer stem-like cells (PCSCs) and a xenograft model of CRPC. In this study, we further confirmed that NURR1 exhibited an upregulation in prostate cancer and also enhanced expression in prostate cancer cell lines. Functional and molecular analyses showed that NURR1 could act to promote both in vitro (cancer stemness and EMT) and also in vivo oncogenic growth of prostate cancer cells (metastasis and castration resistance) via its direct transactivation of CTNNB1 (β-catenin) and activation of β-catenin to mediate the activation of Wnt/β-catenin signaling pathway. Moreover, we also demonstrated that NURR1 activity in prostate cancer cells could be modulated by small molecules, implicating that NURR1 could be a potential therapeutic target for advanced prostate cancer management.

Abstract 1456: An expression study of circadian clock-associated transcription factors and nuclear receptors in mouse prostate gland and tumor

The circadian clock lies in the suprachiasmatic nucleus of the hypothalamus and is regulated directly by the daily light/dark cycles, generating rhythmic expression of core circadian-controlled genes (CCCG) some belonging to the nuclear receptors (NR) superfamily. Recent advances show that the disruption of the circadian clock is identified as a risk factor for endocrine cancers, such as prostate cancer which is the most common hormone-related male cancer globally. Whether the prostate gland has its own circadian expression of CCCG and NR, and how the dysregulated circadian clock would influence the fate of the prostate tumors is not well studied. Thus, the present study aims to determine the circadian expression patterns of CCCG and NR in normal mouse prostate and further validate their disrupted circadian expression in a transgenic mouse adenocarcinoma prostate cancer model (TGMAP) with neuroendocrine phenotypes and suppressed androgen gene expression (AR), over the 12 hours light/dark cycle.

We establish the rhythmic expression patterns of multiple CCCG and the full class of NR by quantitative polymerase-chain reaction analysis in normal mouse prostate (C57BL/6 strain) and advanced prostate tumors derived from TGMAP in a 12-hours light/dark cycle with 4-hours interval. Our results showed that 30 out of 49 NR and several CCCG follow rhythmic expression patterns, followed by 10 NR with unidentifiable expression patterns and 9 NR showing very low expression in the mouse prostate tissue. The circadian expression of these transcription factors including the AR gene, could be divided into 2 categories with single peak or double peaks at specific time points throughout the light/dark cycle, linking them to the regulating function of the circadian clock in the normal prostate gland. In the advanced prostate tumors derived from TGMAP model that exhibit androgen independence and neuroendocrine trans-differentiation phenotype, the rhythmic cycles of the NR and CCCG showed disruption, and several transcription factors were upregulated in overall circadian expression in comparison to the normal prostate tissue. In summary, this study establishes two categories of rhythmic expression patterns in normal mouse prostate tissue that link the circadian expression of these transcription factors in the peripheral clock to that of androgen signaling axis that is responsible for the maintenance of prostate gland while disruption of such circadian expression patterns was demonstrated in the TGMAP tumors of which the AR signaling was either lost or disrupted. The upregulated circadian expression patterns as revealed in TGMAP model also provide insight into the significance of the dysregulation of circadian rhythm as regulated by CCCG and NR in the advanced prostate cancer. (Study supported by a Direct Grant for Research 2021-2022 Project No. 2021.062, CUHK)

Citation Format: Ria Chopra, Franky Leung Chan. An expression study of circadian clock-associated transcription factors and nuclear receptors in mouse prostate gland and tumor [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 1456.

Alterations of plasma exosomal proteins and motabolies are associated with the progression of castration-resistant prostate cancer

BACKGROUND

Current diagnosis tools for prostate cancer (PCa) such as serum PSA detection and prostate biopsy cannot distinguish dormant tumors from invasive malignancies, either be used as prognosis marker for castration resistant prostate cancer (CRPC), the lethal stage of PCa patients. Exosomes have been widely investigated as promising biomarkers for various diseases. We aim to characterize the proteomic and metabolomic profile of exosomes and to evaluate their potential value for the diagnosis of PCa, especially CRPC. We also investigate the functions of some specific exosome biomarkers in the progression of CRPC.

METHODS

Integrated proteomics and metabolomics analysis were performed for plasma-derived exosomes collected from tumor-free controls (TFC), PCa and CRPC patients. Expression of specific exosomal proteins were further validated by targeted 4D-parallel reaction monitoring (PRM) mass spectrometry among the three cohorts. Tissue distribution and functional role of exosomal protein LRG1 was studied in clinical PCa tissue samples and cell line models.

RESULTS

Three potential exosomal protein markers were identified. The apolipoprotein E level in PCa samples was 1.7-fold higher than that in TFC (receiver operating characteristic value, 0.74). Similarly, the levels of exosome-derived leucine-rich alpha2-glycoprotein 1 (LRG1) and inter-alpha-trypsin inhibitor heavy chain H3 (ITIH3) in the CRPC group were 1.7 and 2.04 times, respectively, higher than those in the PCa group (ROC values, 0.84 and 0.85, respectively), indicating that LRG1 and ITIH3 could serve as predictive markers for CRPC. For metabolomic evaluation of exosomes, a series of differentially expressed metabolites were identified, and a combined metabolite panel showed ROC value of 0.94 for distinguishing PCa from TFC and 0.97 for distinguishing CRPC from PCa. Immunohistochemistry of tissue microarray showed that LRG1 protein was significantly upregulated in advanced prostate cancer and functional assay revealed that ectopic expression of LRG1 can significantly enhance the malignant phenotype of prostate cancer cells. More importantly, PCa cell derived LRG1-overexpressed exosomes remarkably promoted angiogenesis.

CONCLUSION

Integration of proteomics and metabolomics data generated proteomic and metabolic signatures of plasma exosomes that may facilitate discrimination of CRPC from PCa and TFC patients, suggesting the potential of exosomal proteins and metabolites as CRPC markers. The study also confirmed the important role of exosomal protein LRG1 in PCa malignant progression.

Endothelial nitric oxide synthase (eNOS)-NO signaling axis functions to promote the growth of prostate cancer stem-like cells

BACKGROUND

Accumulating evidence supports that prostate cancer stem-like cells (PCSCs) play significant roles in therapy resistance and metastasis of prostate cancer. Many studies also show that nitric oxide (NO) synthesized by NO synthases can function to promote tumor progression. However, the exact roles of NOSs and NO signaling in the growth regulation of PCSCs and castration-resistant prostate cancer (CRPC) are still not fully understood.

METHODS

The regulatory functions of NOS-NO signaling were evaluated in prostate cancer cells, especially in PCSCs enriched by 3D spheroid culture and CD133/CD44 cell sorting. The molecular mechanisms of NOS-NO signaling in PCSCs growth regulation and tumor metastasis were investigated in PCSCs and mice orthotopic prostate tumor model.

RESULTS

Endothelial NOS (eNOS) exhibited a significant upregulation in high-grade prostate cancer and metastatic CRPC. Xenograft models of CRPC exhibited notable increased eNOS expression and higher intracellular NO levels. PCSCs isolated from various models displayed significant enhanced eNOS-NO signaling. Functional analyses demonstrated that increased eNOS expression could promote in vivo tumorigenicity and metastatic potential of prostate cancer cells. Characterization of eNOS-NO involved downstream pathway which confirmed that enhanced eNOS signaling could promote the growth of PCSCs and antiandrogen-resistant prostate cancer cells via an activated downstream NO-sGC-cGMP-PKG effector signaling pathway. Interestingly, eNOS expression could be co-targeted by nuclear receptor ERRα and transcription factor ERG in prostate cancer cells and PCSCs.

CONCLUSIONS

Enhanced eNOS-NO signaling could function to promote the growth of PCSCs and also the development of metastatic CRPC. Besides eNOS-NO as potential targets, targeting its upstream regulators (ERRα and ERG) of eNOS-NO signaling could also be the therapeutic strategy for the management of advanced prostate cancer, particularly the aggressive cancer carrying with the TMPRSS2:ERG fusion gene.

Hsa_circ_0003258 promotes prostate cancer metastasis by complexing with IGF2BP3 and sponging miR-653-5p

Background

More and more studies have shown that circular RNAs (circRNAs) play a critical regulatory role in many cancers. However, the potential molecular mechanism of circRNAs in prostate cancer (PCa) remains largely unknown.

Methods

Differentially expressed circRNAs were identified by RNA sequencing. The expression of hsa_circ_0003258 was evaluated using quantitative real-time PCR and RNA in situ hybridization. The impacts of hsa_circ_0003258 on the metastasis of PCa cells were investigated by a series of in vitro and in vivo assays. Lastly, the underlying mechanism of hsa_circ_0003258 was revealed by Western blot, biotin-labeled RNA pulldown, RNA immunoprecipitation, luciferase assays and rescue experiments.

Results

Increased expression of hsa_circ_0003258 was found in PCa tissues and was associated with advanced TNM stage and ISUP grade. Overexpression of hsa_circ_0003258 promoted PCa cell migration by inducing epithelial mesenchymal transformation (EMT) in vitro as well as tumor metastasis in vivo, while knockdown of hsa_circ_0003258 exerts the opposite effect. Mechanistically, hsa_circ_0003258 could elevate the expression of Rho GTPase activating protein 5 (ARHGAP5) via sponging miR-653-5p. In addition, hsa_circ_0003258 physically binds to insulin like growth factor 2 mRNA binding protein 3 (IGF2BP3) in the cytoplasm and enhanced HDAC4 mRNA stability, in which it activates ERK signalling pathway, then triggers EMT programming and finally accelerates the metastasis of PCa.

Conclusions

Upregulation of hsa_circ_0003258 drives tumor progression through both hsa_circ_0003258/miR-653-5p/ARHGAP5 axis and hsa_circ_0003258/IGF2BP3 /HDAC4 axis. Hsa_circ_0003258 may act as a promising biomarker for metastasis of PCa and an attractive target for PCa intervention.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12943-021-01480-x.

A novel ferroptosis-related gene prognostic index for prognosis and response to immunotherapy in patients with prostate cancer

BACKGROUND

Prostate cancer (PCa) is among the leading causes of cancer death worldwide. Ferroptosis refers to an iron-dependent form of regulated cell death and is involved in prostate tumorigenesis. A few ferroptosis-related gene signatures have been developed to predict the prognosis for PCa patients. However, previous signatures were typically established based on biochemical recurrence-free survival, which has proven not to be a good surrogate for overall survival (OS). This study aimed to construct a novel ferroptosis-related gene prognostic index (FRGPI) to predict disease-free survival (DFS) and response to immunotherapy for PCa patients after radical prostatectomy.

METHODS

Gene expression and clinicopathological data on PCa patients were obtained from the TCGA database. Ferroptosis-related hub genes associated with DFS of PCa patients were identified by an in-depth bioinformatics analysis using a novel and comprehensive algorithm based on functional enrichment, consensus clustering, weighted gene co-expression network analysis (WGCNA), and protein-protein interaction (PPI) network construction. The FRGPI was established on the basis of the genes selected using multivariate cox regression analysis and further validated in two additional PCa cohorts. Next, the clinicopathological, molecular, and immune profiles were characterized and compared between FRGPI-high and FRGPI-low subgroups. Finally, the predictive role of the FRGPI in response to immunotherapy was estimated using a metastatic urothelial cancer cohort treated with an anti-PD-L1 agent.

RESULTS

The FRGPI was constructed based on four genes (E2F1, CDC20, TYMS, and NUP85), and FRGPI-high patients had worse DFS than FRGPI-low patients. Multivariate cox regression analysis revealed that FRGPI could act as an independent prognostic factor for PCa patients after radical prostatectomy. A prognostic nomogram comprising the FRGPI and other clinicopathological parameters was established to predict the DFS for PCa patients quantitatively. In addition, comprehensive results demonstrated that high FRGPI scores showed a significantly positive correlation with worse clinicopathological features, higher mutation counts, increased frequency of copy number variations (CNVs), higher homologous recombination deficiency (HRD) and immune scores, higher mRNAsi, and more importantly, enhanced sensitivity to immunotherapy.

CONCLUSIONS

FRGPI is not only a promising and robust prognostic biomarker, but also a potential indicator of immunotherapeutic outcomes for PCa patients after radical prostatectomy.

Orphan nuclear receptors as regulators of intratumoral androgen biosynthesis in castration-resistant prostate cancer

Castration-resistant prostate cancer (CRPC) almost invariably occurs after androgen-deprivation therapy (ADT) for the advanced metastatic disease. It is generally believed that among multiple mechanisms and signaling pathways, CRPC is significantly driven by the reactivation of androgen receptor (AR) signaling in ADT-treated patients with castrate levels of androgen, partially at least mediated by the androgen biosynthesis within the tumor, also known as intratumoral or intraprostatic androgen biosynthesis. Steroidogenic enzymes, such as CYP11A1, CYP17A1, HSD3B1, AKR1C3 and SRD5A, are essential to catalyze the conversion of the initial substrate cholesterol into potent androgens that confers the CRPC progression. Accumulating evidences indicate that many steroidogenic enzymes are upregulated in the progression setting; however, little is known about the dysregulation of these enzymes in CRPC. Orphan nuclear receptors (ONRs) are members of the nuclear receptor superfamily, of which endogenous physiological ligands are unknown and which are constitutively active independent of any physiological ligands. Studies have validated that besides AR, ONRs could be the potential therapeutic targets for prostate cancer, particularly the lethal CRPC progression. Early studies reveal that ONRs play crucial roles in the transcriptional regulation of steroidogenic enzyme genes. Notably, we and others show that three distinct ONRs, including liver receptor homolog-1 (LRH-1, NR5A2), steroidogenic factor 1 (SF-1, AD4BP, NR5A1) and estrogen-related receptor α (ERRα, NR3B1), can contribute to the CRPC progression by promotion of the intratumoral androgen synthesis via their direct transcriptional regulation on multiple steroidogenic enzymes. This review presents an overview of the current understanding on the intratumoral androgen biosynthesis in CRPC, with a special focus on the emerging roles of ONRs in this process.

Interplay between orphan nuclear receptors and androgen receptor-dependent or-independent growth signalings in prostate cancer

It is well-established that both the initial and advanced growth of prostate cancer depends critically on androgens and thus on the activated androgen receptor (AR) -mediated signaling pathway. The unique hormone-dependent feature of prostate cancer forms the biological basis of hormone or androgen-deprivation therapy (ADT) that aims to suppress the AR signaling by androgen depletion or AR antagonists. ADT still remains the mainstay treatment option for locally advanced or metastatic prostate cancer. However, most patients upon ADT will inevitably develop therapy-resistance and progress to relapse in the form of castration-resistant disease (castration-resistant prostate cancer or CRPC) or even a more aggressive androgen-independent subtype (therapy-related neuroendocrine prostate cancer or NEPC). Recent advances show that besides AR, some ligand-independent members of nuclear receptor superfamily-designated as orphan nuclear receptors (ONRs), as their endogenous physiological ligands are either absent or not yet identified to date, also play significant roles in the growth regulation of prostate cancer via multiple AR-dependent or -independent (AR-bypass) pathways or mechanisms. In this review, we summarize the recent progress in the newly elucidated roles of ONRs in prostate cancer, with a focus on their interplay in the AR-dependent pathways (intratumoral androgen biosynthesis and suppression of AR signaling) and AR-independent pathways or cellular processes (hypoxia, oncogene- or tumor suppressor-induced senescence, apoptosis and regulation of prostate cancer stem cells). These ONRs with their newly characterized roles not only can serve as novel biomarkers but also as potential therapeutic targets for management of advanced prostate cancer.

Abstract 1007: Orphan nuclear receptor TLX regulates the antitumor immune response through transcriptional regulation of programmed death ligand 1 in glioma

High-grade gliomas are rapidly progressing tumors of the central nervous system (CNS) with a very poor prognosis and novel treatment are urgently needed to improve patient outcomes. Clinical trials of immunotherapies for glioma including PD1/PD-L1 inhibition have performed but the outcome was not optimistic. In this study, we found that orphan nuclear recepter TLX and PD-L1 were both significantly upregulated in glioma lesions and the expression of TLX and PD-L1 in glioma was positively correlated. Moreover, the expression pattern of TLX also associated with a suppression microenvironment in glioma. Functional study revealed that suppression of TLX inhibited glioma cell growth and immune response, which accompanied with down-regulation of PD-L1. We also characterized that TLX could bind directly to PD-L1 promoter and activate PD-L1 gene transcription. Together, our present study shows, for the first time, that TLX can contribute to glioma immune escape via promoting the expression of PD-L1, targeting the druggable TLX may have a potential therapeutic significance in glioma immune therapy.

Citation Format: Jiayi Zhou, Xiaojuan Pei, Zhu Wang, Weijie Gao, Franky Leung Chan, Xin Li, Jie Mao, Dinglan Wu. Orphan nuclear receptor TLX regulates the antitumor immune response through transcriptional regulation of programmed death ligand 1 in glioma [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 1007.

Targeting prostate cancer stem-like cells by an immunotherapeutic platform based on immunogenic peptide-sensitized dendritic cells-cytokine-induced killer cells

Background

Autologous cellular immunotherapy or immune enhancement therapy has demonstrated some promising benefits for prostate cancer. T cell-based immunotherapy or sipuleucel-T therapy has yielded certain beneficial responses and a slight improvement on the overall survival of patients with metastatic castration-resistant prostate cancer (mCRPC) as shown in some clinical trials, suggesting that prostate cancer is immunoresponsive.

Methods

In this study, we developed an adaptive cytokine-induced killer cell (CIK)-based immunotherapeutic application targeting the prostate cancer stem-like cells (PCSCs). In this therapeutic platform, dendritic cells (DC) were isolated from the peripheral blood mononuclear cells (PBMCs) and preloaded or sensitized with immunogenic peptides derived from two PCSC-associated cell membrane molecules, CD44 and EpCAM, followed by co-culture with the expanded peripheral blood lymphocyte (PBL)-derived CIK cells. The in vitro cytotoxic activity of DC-activated CIK cells against PCSCs was determined by CCK8 and TUNEL assays, and the in vivo anti-tumor effect of DC-activated CIK cells on prostate cancer xenograft tumors was evaluated in subcutaneous and orthotopic xenograft models.

Results

Our results showed that the peptide-sensitized DC-CIK cell preparation manifested significant in vitro cytotoxic activity against the PCSC-enriched prostatospheroids and also in vivo anti-tumor effect against prostate cancer xenografts derived from the PCSC-enriched prostatospheroids.

Conclusions

Together, our established immunogenic peptide-sensitized DC-CIK-based cell preparation platform manifests its potential immunotherapeutic application in targeting the PCSCs and also prostate cancer.

Nuclear receptor ERRα contributes to castration-resistant growth of prostate cancer via its regulation of intratumoral androgen biosynthesis

Enhanced intratumoral androgen biosynthesis and persistent androgen receptor (AR) signaling are key factors responsible for the relapse growth of castration-resistant prostate cancer (CRPC). Residual intraprostatic androgens can be produced by de novo synthesis of androgens from cholesterol or conversion from adrenal androgens by steroidogenic enzymes expressed in prostate cancer cells via different steroidogenic pathways. However, the dysregulation of androgen biosynthetic enzymes in CRPC still remains poorly understood. This study aims to elucidate the role of the nuclear receptor, estrogen-related receptor alpha (ERRα, ESRRA), in the promotion of androgen biosynthesis in CRPC growth. Methods: ERRα expression in CRPC patients was analyzed using Gene Expression Omnibus (GEO) datasets and validated in established CRPC xenograft model. The roles of ERRα in the promotion of castration-resistant growth were elucidated by overexpression and knockdown studies and the intratumoral androgen levels were measured by UPLC-MS/MS. The effect of suppression of ERRα activity in the potentiation of sensitivity to androgen-deprivation was determined using an ERRα inverse agonist. Results: ERRα exhibited an increased expression in metastatic CRPC and CRPC xenograft model, could act to promote castration-resistant growth via direct transactivation of two key androgen synthesis enzymes CYP11A1 and AKR1C3, and hence enhance intraprostatic production of dihydrotestosterone (DHT) and activation of AR signaling in prostate cancer cells. Notably, inhibition of ERRα activity by an inverse agonist XCT790 could reduce the DHT production and suppress AR signaling in prostate cancer cells. Conclusion: Our study reveals a new role of ERRα in the intratumoral androgen biosynthesis in CRPC via its transcriptional control of steroidogenic enzymes, and also provides a novel insight that targeting ERRα could be a potential androgen-deprivation strategy for the management of CRPC.

Adipose-derived stem cells and cancer cells fuse to generate cancer stem cell-like cells with increased tumorigenicity

Adipose-derived stem cells (ADSCs) are a type of mesenchymal stem cells isolated from adipose tissue and have the ability to differentiate into adipogenic, osteogenic, and chondrogenic lineages. Despite their great therapeutic potentials, previous studies showed that ADSCs could enhance the proliferation and metastatic potential of breast cancer cells (BCCs). In this study, we found that ADSCs fused with BCCs spontaneously, while breast cancer stem cell (CSC) markers CD44⁺ CD24^-/low EpCAM⁺ were enriched in this fusion population. We further assessed the fusion hybrid by multicolor DNA FISH and mouse xenograft assays. Only single nucleus was observed in the fusion hybrid, confirming that it was a synkaryon. In vivo mouse xenograft assay indicated that the tumorigenic potential of the fusion hybrid was significantly higher than that of the parent tumorigenic triple-negative BCC line MDA-MB-231. We had compared the fusion efficiency between two BCC lines, the CD44-rich MDA-MB-231 and the CD44-poor MCF-7, with ADSCs. Interestingly, we found that the fusion efficiency was much higher between MDA-MB-231 and ADSCs, suggesting that a potential mechanism of cell fusion may lie in the dissimilarity between these two cell lines. The cell fusion efficiency was hampered by knocking down the CD44. Altogether, our findings suggest that CD44-mediated cell fusion could be a potential mechanism for generating CSCs.

Chromogranin A is a predictor of prognosis in patients with prostate cancer: a systematic review and meta-analysis

Background: The prognostic value of chromogranin-A (CHGA) as a biomarker of prostate cancer (PCa) has been evaluated extensively. However, to date the results still remain controversial. This study aims to perform a meta-analysis on previous studies in order to determine whether CHGA would be a biomarker for survival in PCa patients. Methods: MEDLINE, Embase, Web of Science, and Cochrane Library databases were searched to identify eligible studies published before September 2018, regarding the association of CHGA gene expression with survival outcomes in patients with PCa. Multivariate adjusted HRs and associated 95% CIs were calculated using random effects models. Results: Ten cohort studies involving 3,172 patients were finally included. According to the included studies, circulating CHGA levels were tested in serum, plasma, and tissues. The results showed an association between high CHGA expression and worse overall survival (OS) (HR=1.24, 95% CI: 1.07-1.44; P=0.004; I ²=77.6%) in PCa patients. However, no significant association was observed between increasing CHGA expression and shorter progression-free survival (HR=1.73, 95% CI: 0.92-3.28; P=0.090; I ²=73.9%). The results of sensitivity analysis validated the rationality and reliability of our analysis. Conclusion: Current evidence indicates that high CHGA expression is a potential marker for poor OS in PCa. Future studies are needed to explore tailored treatments that directly target CHGA for the improvement of survival in men with PCa.

Health survey of employees regularly using 3D printers

Background

3D printers emit potentially hazardous ultrafine particles and volatile organic compounds. Workers using 3D printing technologies may be at risk of respiratory illness from occupational exposure.

Aims

To assess whether 3D printing is associated with health effects in occupational users.

Methods

This was a preliminary survey. Workers in 17 companies using 3D printing, including commercial prototyping businesses, educational institutions and public libraries, in the Greater Toronto Area, Canada, were asked to complete survey questionnaires concerning demographic, occupational and health information. Associations between self-reported health history variables and occupational characteristics were examined by chi-square and Fisher's exact tests.

Results

Among 46 surveyed workers, 27 (59% of participants) reported having respiratory symptoms at least once per week in the past year. Working more than 40 h per week with 3D printers was significantly associated with having been given a respiratory-related diagnosis (asthma or allergic rhinitis) (P < 0.05). We observed a wide variation in occupational hygiene practices in the 17 printing workplaces that we surveyed.

Conclusions

Our finding of frequently reported respiratory symptoms suggests a need for additional studies on exposed workers in this field.

Nuclear receptor ERRα and transcription factor ERG form a reciprocal loop in the regulation of TMPRSS2:ERG fusion gene in prostate cancer

The TMPRSS2:ERG (T:E) fusion gene is generally believed to be mainly regulated by the activated androgen receptor (AR) signaling in androgen-dependent prostate cancer. However, its persistent expression in castration-resistant and neuroendocrine prostate cancers implies that other transcription factors might also regulate its expression. Here, we showed that up-regulation of nuclear receptor estrogen-related receptor alpha (ERRα) was closely associated with the oncogenic transcription factor ERG expression in prostate cancer, and their increased coexpression patterns were closely associated with high Gleason scores and metastasis in patients. Both ERRα and ERG exhibited a positive expression correlation in a castration-resistant prostate cancer (CRPC) xenograft model VCaP-CRPC. We showed that ERRα could directly transactivate T:E fusion gene in both AR-positive and -negative prostate cancer cells via both ERR-binding element- and AR-binding element-dependent manners. Ectopic T:E expression under ERRα regulation could promote both in vitro invasion and in vivo metastasis capacities of AR-negative prostatic cells. Intriguingly, ERG expressed by the T:E fusion could also transactivate the ERRα (ESRRA) gene. Hereby, ERRα and ERG can synergistically regulate each other and form a reciprocal regulatory loop to promote the advanced growth of prostate cancer. Inhibition of ERRα activity by ERRα inverse agonist could suppress T:E expression in prostate cancer cells, implicating that targeting ERRα could be a potential therapeutic strategy for treating the aggressive T:E-positive prostate cancer.

Development of a novel and economical agar-based non-adherent three-dimensional culture method for enrichment of cancer stem-like cells

BACKGROUND

Non-adherent or ultra-low attachment three-dimensional (3D) culture, also called sphere formation assay, has been widely used to assess the malignant phenotype and stemness potential of transformed or cancer cells. This method is also popularly used to isolate the cancer stem-like cells (CSCs) or tumor-initiating cells based on their unique anchorage-independent growth or anoikis-resistant capacity. Different non-adhesive coating agents, such as poly-2-hydroxyethyl methacrylate (poly-HEMA) and synthetic hydrogels, have been used in this non-adherent 3D culture. However, preparation of non-adherent culture-ware is labor-intensive and technically demanding, and also costs of commercial non-adherent culture-ware prepared with various coating agents are relatively expensive and the culture-ware cannot be used repeatedly.

METHODS

In this study, we developed a non-adherent 3D culture method based on agar coating for growing tumor spheres derived from various cancer cell lines and primary prostate cancer tissues under a non-adherent and serum-free condition. The tumor spheres generated by this 3D culture method were analyzed on their expression profiles of CSC-associated markers by reverse transcription quantitative polymerase chain reaction, presence and relative proportion of CSCs by fluorescence-activated cell sorting (CD133⁺/CD44⁺ cell sorting) and also a CSC-visualizing reporter system responsive to OCT4 and SOX2 (SORE6), and in vivo tumorigenicity. The repeated use of agar-coated plates for serial passages of tumor spheres was also evaluated.

RESULTS

Our results validated that the multicellular tumor spheres generated by this culture method were enriched of CSCs, as evidenced by their enhanced expression profiles of CSC markers, presence of CD133⁺/CD44⁺ or SORE6⁺ cells, enhanced self-renewal capacity, and in vivo tumorigenicity, indicating its usefulness in isolation and enrichment of CSCs. The agar-coated plates could be used multiple times in serial passages of tumor spheres.

CONCLUSIONS

The described agar-based 3D culture method offers several advantages as compared with other methods in isolation of CSCs, including its simplicity and low-cost and repeated use of agar-coated plates for continuous passages of CSC-enriched spheres.

LRH-1 drives hepatocellular carcinoma partially through induction of c-myc and cyclin E1, and suppression of p21

Background

To explore potential therapeutic target is one of the areas of great interest in both clinical and basic hepatocellular carcinoma (HCC) studies. Nuclear receptor liver receptor homolog-1 (LRH-1, NR5A2) is proved to play a positive role in several cancers including breast cancer, pancreatic cancer and intestinal cancer in recent years. However, the exact role of LRH-1 in the development and progression of HCC is not fully elucidated.

Methods

The LRH-1 expression level in HCC clinical samples was examined by immunohis-tochemistry (IHC). Stable LRH-1-suppressed HepG2 clones (HepG2^LRH-1/-) were generated by transcription activator-like effector nucleases (TALENs) and both in vitro and in vivo experiments were conducted.

Results

We confirmed that LRH-1 showed an increased expression pattern in HCC clinical samples. Our in vitro and in vivo results indicated that suppression of LRH-1 in HepG2 significantly attenuated its proliferation rate and tumorigenic capacity. Gene expression microarray analysis indicated that LRH-1mostly regulated gene expression involved in cell cycle. In addition, our gain-of-function experiments indicated that ectopic expression of LRH-1 dramatically induced the mRNA and protein levels of c-myc and cyclin E1, while attenuating the expression of p21.

Conclusion

Our results suggest that LRH-1 might be a potential therapeutic target for clinical HCC treatment.

Abstract 2000: The regulatory role of endothelial nitric oxide synthase signaling in the growth of prostate cancer stem-like cells

Cumulative studies indicate that there is a small subpopulation of cancer cells present in cancers or solid tumors referred as cancer stem-like cells (CSCs) as they share some common characteristics with stem cells, particularly self-renewal and multipotency, and these CSCs may contribute to the tumor initiation, treatment resistance and relapse. Recent advances also indicate that prostate cancer stem-like cells (PCSCs) may play a critical role in the development of castration-resistant prostate cancer (CRPC) and also its metastasis. Here, we demonstrated using an established CRPC xenograft model (VCaP-CRPC) that both the xenograft tumors and a xenograft-derived cell line contained more PCSC population, which showed higher expression levels of endothelial nitric oxide synthase (eNOS) and elevated intracellular NO production. PCSCs, isolated from prostaspheres derived from prostate cancer cell lines (DU145, LNCaP and VCaP) using a newly developed agar-based non-attachment 3D-culture method, exhibited up-regulation of eNOS and increased intracellular NO levels. Interruption of eNOS signaling by NOS inhibitors and shRNA-knockdown could significantly suppress the sphere formation capability of prostate cancer cells. Exogenous overexpression of eNOS could promote the tumor growth capacity of prostate cancer cells and their metastasis in vivo, while knockdown of eNOS could prevent the tumor growth and metastasis. Combined transcriptome-sequencing analysis and qPCR validation of prostaspheres upon eNOS-knockdown identified some potential targets of eNOS/NO signaling in the PCSC-enriched prostaspheres. In summary, our results suggest that eNOS/NO signaling may play a positive role in the growth regulation of PCSCs and eNOS might be a potential target for advanced prostate cancer. This study is supported by a General Research Fund from the Research Grants Council of Hong Kong (project code 14107617) and an Innovation and Technology Fund (GHP/003/16GD) from the Innovation and Technology Commission of Hong Kong.

Citation Format: Weijie Gao, Dinglan Wu, Yuliang Wang, Zhu Wang, Taiyang Ma, Franky Leung Chan. The regulatory role of endothelial nitric oxide synthase signaling in the growth of prostate cancer stem-like cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 2000.

Nuclear Receptor LRH-1 Functions to Promote Castration-Resistant Growth of Prostate Cancer via Its Promotion of Intratumoral Androgen Biosynthesis

Targeting of steroidogenic enzymes (e.g., abiraterone acetate targeting CYP17A1) has been developed as a novel therapeutic strategy against metastatic castration-resistant prostate cancer (CRPC). However, resistance to steroidal inhibitors inevitably develops in patients, the mechanisms of which remain largely unknown. Liver receptor homolog-1 (LRH-1, NR5A2) is a nuclear receptor, originally characterized as an important regulator of some liver-specific metabolic genes. Here, we report that LRH-1, which exhibited an increased expression pattern in high-grade prostate cancer and CRPC xenograft models, functions to promote de novo androgen biosynthesis via its direct transactivation of several key steroidogenic enzyme genes, elevating intratumoral androgen levels and reactivating AR signaling in CRPC xenografts as well as abiraterone-treated CRPC tumors. Pharmacologic inhibition of LRH-1 activity attenuated LRH-1-mediated androgen deprivation and anti-androgen resistance of prostate cancer cells. Our findings not only demonstrate the significant role of LRH-1 in the promotion of intratumoral androgen biosynthesis in CRPC via its direct transcriptional control of steroidogenesis, but also suggest targeting LRH-1 could be a potential therapeutic strategy for CRPC management.Significance: These findings not only demonstrate the significant role of the nuclear receptor LRH-1 in the promotion of intratumoral androgen biosynthesis in CRPC via its direct transcriptional control of steroidogenesis, but also suggest targeting LRH-1 could be a potential therapeutic strategy for CRPC management. Cancer Res; 78(9); 2205-18. ©2018 AACR.

Abstract 4576: Hepatocyte nuclear factor 4 alpha suppresses cell proliferation and induces cellular senescence and apoptosis in prostate cancer cells

Hepatocyte nuclear factor 4α (HNF4α, NR2A1) is a highly conserved member of the nuclear receptor superfamily of ligand-dependent transcription factors. Recent advances show that it is a key transcriptional regulator of many genes, involved in xenobiotic and drug metabolism and also cancers of gastrointestinal tract. However, the exact functional roles of HNF4α gene in prostate cancer progression are still not fully understood. In this study we used the overexpression (gain-of-function) and knockdown (loss-of-function) approaches to determine the functional roles of HNF4α in prostate cancer. Our results showed that HNF4α exhibited a reduced expression pattern in many prostate cancer cells compared to immortalized prostatic cell lines. Its overexpression could significantly inhibit the cell proliferation of prostate cancer cells, and trigger the cellular senescence and apoptosis by activation of p21 signal pathway in a p53-independent manner. We showed that stable overexpression of HNF4α could significantly induce G2/M arrest in PC3 cells, while shRNA-mediated knockdown of HNF4α could induce G1 growth arrest, suggesting that HNF4α might play a negative role in the cell cycle regulation of PC3 cells. Moreover, stable HNF4α knockdown could confer resistance to paclitaxel treatment and enhance colony formation capacity in prostate cancer cells. Together, our results suggest that HNF4α may play a tumor suppressor function in prostate cancer progression.This work was supported by a Direct Grant for Research 2015-2016 (2015. 1. 064), CUHK.

Citation Format: Zhu WANG, Franky Leung Chan. Hepatocyte nuclear factor 4 alpha suppresses cell proliferation and induces cellular senescence and apoptosis in prostate cancer cells. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 4576.

Collapsin response mediator protein-1 (CRMP1) acts as an invasion and metastasis suppressor of prostate cancer via its suppression of epithelial-mesenchymal transition and remodeling of actin cytoskeleton organization

The cancer cells can acquire migration and invasion capacities during the metastasis process through the developmental regulatory program epithelial–mesenchymal-transition (EMT), and through its reverse process mesenchymal–epithelial transition cancer cells can recolonize at distant metastatic sites. Among the multifaceted effects exerted by this program, reorganization of actin cytoskeleton is the key mechanical drive for the invasive properties gained by cancer cells. Collapsin response mediator protein-1 (CRMP1) is a cytosolic phosphoprotein and originally characterized as the mediator of semaphorin 3A signaling involved in axon differentiation during neural development. Here we report that CRMP1 can act as a suppressor of tumorigenicity and metastasis in prostate cancer cells. We demonstrated that CRMP1 exhibited a decreased expression pattern in high-grade prostate cancer tissues and many prostate cancer cell lines, and its downregulation in cancer cells was attributed to histone deacetylation and direct repression of its gene by the EMT regulator Snail. Functional analyses revealed that CRMP1 suppressed EMT in prostate cancer cells, as its knockdown could trigger EMT and enhance in vitro invasion capacity, whereas its overexpression could inhibit EMT and suppress both in vitro invasion and in vivo metastasis capacities of prostate cancer cells. Moreover, CRMP1 overexpression could significantly confer resistance to EMT induced by Snail or transforming growth factor-β1 in prostatic epithelial cells and prostate cancer cells. Finally, we demonstrated that CRMP1 could associate with actin and WAVE1, an activator of actin nucleation complex Arp2/3, and also its knockdown could stabilize F-actin and trigger the formation of stress fibers in prostate cancer cells. Together, our study shows that CRMP1 acts an EMT and metastasis suppressor in prostate cancer cells via its regulation of actin polymerization and also suggests that targeting the CRMP1-actin signaling in actin organization could be a potential strategy for management of prostate cancer metastasis.

Abstract A21: Orphan nuclear receptor TLX recruits lysine-specific demethylase 1 to repress androgen receptor gene transcription and functions to promote hormone-resistant growth of prostate cancer cells

Prostate cancer (PCa) is the most frequently diagnosed type of cancer and the second leading cause of death from cancer in males in the United States. The initial growth of most localized PCa is slow and androgen-dependent. Thus, surgical treatment (prostatectomy) and hormone therapy (androgen deprivation) are effective initially. However, many patients relapse and progress to a fatal androgen-independent and bone-metastatic stage shortly when both primary and secondary hormone therapies fail. Unfortunately, the current options for the metastatic hormone-refractory PCa are still limited and mostly ineffective, resulting in high mortality of this disease. Although dysregulated androgen receptor (AR) signaling pathway has been proposed to contribute to the development of hormone-resistance, the involved mechanisms are still not fully defined. Our present findings revealed that the orphan nuclear receptor TLX (NR2E1) exhibited increased expression patterns in androgen-independent and antiandrogen-resistant PCa cells, and also the high-grade and hormone-refractory clinical PCa tissues. Stable overexpression of TLX in AR-positive LNCaP cells could promote both androgen-independent and antiandrogen-resistant cell growth in vitro, and enhance tumor growth capacity in castrated male SCID mice in vivo. Decreased expression of AR and AR target genes in LNCaP-TLX cells were identified, while results of AR-promoter driven luciferase reporter assay also revealed that TLX overexpression could suppress the AR transcription in non-prostatic HEK293 cells. Furthermore, we also identified the direct binding site of TLX on the AR promoter by chromatin immunoprecipitation analyses in TLX-transfected HEK293 cells. The molecular mechanism may involve the TLX-mediated recruitment of lysine-specific demethylase 1 (LSD1) as treatment with an inhibitor of LSD1 pargyline could reverse the transrepressive regulation of TLX on AR-promoter driven luciferase activity and restore AR gene expression levels in LNCaP cells. In summary, our results showed for the first time that overexpression of TLX might contribute to the hormone-resistant PCa cell growth and advanced progression of PCa. LSD1 might serve as a corepressor in TLX-mediated direct transrepression on AR gene expression.

This work is partly supported by an RGC-General Research Fund CUHK461012.

Citation Format: Lin Jia, Dinglan Wu, Shan Yu, Franky Leung Chan. Orphan nuclear receptor TLX recruits lysine-specific demethylase 1 to repress androgen receptor gene transcription and functions to promote hormone-resistant growth of prostate cancer cells. [abstract]. In: Proceedings of the AACR Special Conference on Chromatin and Epigenetics in Cancer; Jun 19-22, 2013; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2013;73(13 Suppl):Abstract nr A21.

Abstract 4771: Regulatory role of an orphan nuclear receptor LRH-1 in castration-resistant growth of prostate cancer cells

The advanced development of castration-resistant prostate cancer (CRPC) in patients upon androgen-deprivation therapy is generally believed to be mostly mediated by reactivation of androgen receptor (AR) signaling or its bypass with mechanisms involved, including clonal selection of androgen-independent or stem cell-like cell populations, AR hypersensitivity due to AR overexpression, and ligand promiscuity or independence by AR mutations, intratumoral conversion of adrenal androgens to high affinity AR ligands. Besides, the de novo steroid synthesis from cholesterol in CRPC has also been proposed. In this study, we found that the nuclear receptor liver receptor homolog-1 (LRH-1) might contribute to the CRPC growth or de novo steroid synthesis in prostate cancer cells through its positive regulation on expression of several critical enzymes in steroidogenesis, including CYP17A1, HSD3B1, HSD3B2 and StAR. Functional analyses showed that overexpression of LRH-1 could induce higher resistance to antiandrogen bicalutamide and steroid-depleted culture condition in AR-positive androgen-sensitive (LNCaP) but not in AR-negative androgen-insensitive (DU145) prostate cancer cells. In vivo tumorigenicity study showed that LNCaP-LRH-1 cells grew more aggressively in castrated or intact SCID mice, contrary to LNCaP-vector control cells that did not grow in castrated mice. Importantly, liquid chromatography-tandem mass spectrometry showed that intratumoral androgen concentrations (testosterone and DHT) were significantly higher in tumors formed by LNCaP-LRH-1 cells than those by LNCaP-vector control cells. Treatment of LNCaP-LRH-1 cells with a CYP17A1 inhibitor abiraterone could restore their sensitivity to bicalutamide and steroid-depleted culture condition. Gene knockdown of endogenous LRH-1 in AR-positive VCaP prostate cancer cells could not only suppress the mRNA expression of steroidogenic enzymes but also enhance their sensitivity to antiandrogen. Together, our results indicated that LRH-1 might play a regulatory role in advanced castration-resistant growth of prostate cancer via positive control on de novo steroid synthesis in prostate cancer cells.

(This work was supported by a Direct Grant for Research 2011/2012 and a RGC-GRF grant 2009/2010)

Citation Format: Lijia Xiao, Shan Yu, Wendy W.L. Hsiao, Franky Leung Chan. Regulatory role of an orphan nuclear receptor LRH-1 in castration-resistant growth of prostate cancer cells. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 4771. doi:10.1158/1538-7445.AM2013-4771