Castration-resistant Prostate Cancer Cells Research Articles

Role of non-coding RNA in lineage plasticity of prostate cancer.

The treatment of prostate cancer (PCa) has made great progress in recent years, but treatment resistance always develops and can even lead to fatal disease. Exploring the mechanism of drug resistance is of great significance for improving treatment outcomes and developing biomarkers with predictive value. It is increasingly recognized that mechanism of drug resistance in advanced PCa is related to lineage plasticity and tissue differentiation. Specifically, one of the mechanisms by which castration-resistant prostate cancer (CRPC) cells acquire drug resistance and transform into neuroendocrine prostate cancer (NEPC) cells is lineage plasticity. NEPC is a subtype of PCa that is highly aggressive and lethal, with a median survival of only 7 months. With the development of high-throughput RNA sequencing technology, more and more non-coding RNAs have been identified, which play important roles in different diseases through different mechanisms. Several ncRNAs have shown great potential in PCa lineage plasticity and as biomarkers. In the review, the role of ncRNA in PCa lineage plasticity and its use as biomarkers were reviewed.

Insufficient Effective Time of Suberanilohydroxamic Acid, a Deacetylase Inhibitor, Treatment Promotes PC3 Cell Growth.

Castration-resistant prostate cancer (CRPC) contributes mostly to prostate cancer-specific mortality, and conventional castration therapy is almost ineffective, new therapies are needed. As a new potential anti-cancer drug, histone deacetylases (HDACs) inhibitors were demonstrated to be effective in inhibiting drug-resistance cancers in preclinical studies, but the results from clinical trials on CRPC patients were disappointing, and the reasons are unknown. In this study, we investigated the effect of suberanilohydroxamic acid (SAHA), a broad-spectrum pan-HDAC inhibitor, on proliferation, apoptosis, cell cycle progression in PC3 cells, and found that, unlike significant inhibiting effects at high-dose, low-dose SAHA significantly promoted PC3 cell growth. Further colony formation assay showed that the inhibitory effect of SAHA is also dependent on the treatment time, high-dose SAHA also exhibited promoting effect on PC3 cells when the treatment time was insufficient. However, this effect was not observed in another CRPC cell line, DU145, or another HDAC inhibitor, Trichostatin A (TSA). Our results indicate that, instead of inhibitory effect, SAHA would promote PC3 cell growth if the dose is low or the treatment time is insufficient, but this effect has not been observed in other CRPC cell line or HDAC inhibitors.

MYO6 contributes to tumor progression and enzalutamide resistance in castration-resistant prostate cancer by activating the focal adhesion signaling pathway

BackgroundEnzalutamide (Enz) resistance is a poor prognostic factor for patients with castration-resistant prostate cancer (CRPC), which often involves aberrant expression of the androgen receptor (AR). Myosin VI (MYO6), one member of the myosin family, plays an important role in regulating cell survival and is highly expressed in prostate cancer (PCa). However, whether MYO6 is involved in Enz resistance in CRPC and its mechanism remain unclear.MethodsMultiple open-access databases were utilized to examine the relationship between MYO6 expression and PCa progression, and to screen differentially expressed genes (DEGs) and potential signaling pathways associated with the MYO6-regulated Enz resistance. Both in vitro and in vivo tumorigenesis assays were employed to examine the impact of MYO6 on the growth and Enz resistance of PCa cells. Human PCa tissues and related clinical biochemical data were utilized to identify the role of MYO6 in promoting PCa progression and Enz resistance. The molecular mechanisms underlying the regulation of gene expression, PCa progression, and Enz resistance in CRPC by MYO6 were investigated.ResultsMYO6 expression increases in patients with PCa and is positively correlated with AR expression in PCa cell lines and tissues. Overexpression of AR increases MYO6 expression to promote PCa cell proliferation, migration and invasion, and to inhibit PCa cell apoptosis; whereas knockdown of MYO6 expression reverses these outcomes and enhances Enz function in suppressing the proliferation of the Enz- sensitive and resistant PCa cells both in vitro and in vivo. Mechanistically, AR binds directly to the promoter region (residues − 503 to − 283 base pairs) of MYO6 gene and promotes its transcription. Furthermore, MYO6 activates focal adhesion kinase (FAK) phosphorylation at tyrosine-397 through integrin beta 8 (ITGB8) modulation to promote PCa progression and Enz resistance. Notably, inhibition of FAK activity by Y15, an inhibitor of FAK, can resensitize CRPC cells to Enz treatment in cell lines and mouse xenograft models.ConclusionsMYO6 has pro-tumor and Enz-resistant effects in CRPC, suggesting that targeting MYO6 may be beneficial for ENZ-resistant CRPC therapy through the AR/MYO6/FAK signaling pathway.

PINK1-Mediated Mitochondrial Activity Confers Olaparib Resistance in Prostate Cancer Cells.

Olaparib, a PARP inhibitor, is a targeted therapy used in treating various cancers including castration-resistant prostate cancer (CRPC). Despite its efficacy, resistance to Olaparib remains a significant challenge. Understanding the molecular mechanisms underpinning this resistance is crucial for developing more effective treatment strategies. This study focuses on elucidating the role of mitochondrial alterations and the PINK1 gene in conferring Olaparib resistance in CRPC cells. We investigated the transcriptomic and functional differences in mitochondrial activity between Olaparib-resistant (2B-OlapR, LN-OlapR) and treatment naïve prostate cancer (PCa) cells (C4-2B, LNCaP) in both castration sentitive and resistant settings. Through RNA sequencing and Gene Set Enrichment Analysis (GSEA), we identified significant enrichment of mitochondrial and oxidative phosphorylation-related gene sets in Olaparib Resistant derived cell lines. Resistant lines exhibited enhanced mitochondrial functionality including increased basal and maximal respiration rates, as well as elevated ATP production and spare respiratory capacity compared to parental cells. Subsequent investigations revealed a substantial increase in mitochondrial mass and electron transport chain complex I activity in Olaparib-resistant cells. Furthermore, overexpression of the PINK1 gene was observed in resistant cells, which was correlated with resistance to Olaparib and poor clinical outcomes in prostate cancer patients. Inhibition of PINK1 expression significantly reduced mitochondrial function and mass, impaired cell growth, and decreased resistance to Olaparib. These findings suggest that PINK1 plays a crucial role in modulating mitochondrial dynamics that confer therapeutic resistance, highlighting its potential as a therapeutic target for overcoming Olaparib resistance in PCa.

The Hexosamine Biosynthetic Pathway alters the cytoskeleton to modulate cell proliferation and migration in metastatic prostate cancer.

Castration-resistant prostate cancer (CRPC) progresses despite androgen deprivation therapy, as cancer cells adapt to grow without testosterone, becoming more aggressive and prone to metastasis. CRPC biology complicates the development of effective therapies, posing challenges for patient care. Recent gene-expression and metabolomics studies highlight the Hexosamine Biosynthetic Pathway (HBP) as a critical player, with key components like GNPNAT1 and UAP1 being downregulated in metastatic CRPC. GNPNAT1 knockdown has been shown to increase cell proliferation and metastasis in CRPC cell lines, though the mechanisms remain unclear. To investigate the cellular basis of these CRPC phenotypes, we generated a CRISPR-Cas9 knockout model of GNPNAT1 in 22Rv1 CRPC cells, analyzing its impact on metabolomic, glycoproteomic, and transcriptomic profiles of cells. We hypothesize that HBP inhibition disrupts the cytoskeleton, altering mitotic progression and promoting uncontrolled growth. GNPNAT1 KO cells showed reduced levels of cytoskeletal filaments, such as actin and microtubules, leading to cell structure disorganization and chromosomal mis-segregation. GNPNAT1 inhibition also activated PI3K/AKT signaling, promoting proliferation, and impaired cell adhesion by mislocalizing EphB6, enhancing migration via the RhoA pathway and promoting epithelial-to-mesenchymal transition. These findings suggest that HBP plays a critical role in regulating CRPC cell behavior, and targeting this pathway could provide a novel therapeutic approach.

Stimulating Soluble Guanylyl Cyclase with the Clinical Agonist Riociguat Restrains the Development and Progression of Castration-Resistant Prostate Cancer.

Castration-resistant prostate cancer (CRPC) is incurable and fatal, making prostate cancer the second-leading cancer-related cause of death for American men. CRPC results from therapeutic resistance to standard-of-care androgen deprivation (AD) treatments, through incompletely understood molecular mechanisms, and lacks durable therapeutic options. Here, we identified enhanced soluble guanylyl cyclase (sGC) signaling as a mechanism that restrains CRPC initiation and growth. Patients with aggressive, fatal CRPC exhibited significantly lower serum levels of the sGC catalytic product cyclic GMP (cGMP) compared to their castration-sensitive stage. In emergent castration-resistant cells isolated from castration-sensitive prostate cancer (CSPC) populations, the obligate sGC heterodimer was repressed via methylation of its beta subunit. Genetically abrogating sGC complex formation in CSPC cells promoted evasion of AD-induced senescence and concomitant castration-resistant tumor growth. In established castration-resistant cells, the sGC complex was present but in a reversibly oxidized and inactive state. Subjecting CRPC cells to AD regenerated the functional complex, and co-treatment with riociguat, an FDA-approved sGC agonist, evoked redox stress-induced apoptosis. Riociguat decreased castration-resistant tumor growth and increased apoptotic markers, with elevated cGMP levels correlating significantly with lower tumor burden. Riociguat treatment reorganized tumor vasculature and eliminated hypoxic tumor niches, decreasing CD44+ tumor progenitor cells and increasing the radiosensitivity of castration-resistant tumors. Thus, this study showed that enhancing sGC activity can inhibit CRPC emergence and progression through tumor cell-intrinsic and extrinsic effects. Riociguat can be repurposed to overcome CRPC, with noninvasive monitoring of cGMP levels as a marker for on-target efficacy.

Metformin in Overcoming Enzalutamide Resistance in Castration-Resistant Prostate Cancer.

Androgen deprivation is the standard treatment for prostate cancer (PCa) patients. However, the disease eventually progresses as castration-resistant PCa (CRPC). Enzalutamide, an AR inhibitor, is a typical drug to treating CRPC and due to continuous reliance on the drug, can lead to Enzalutamide-resistance (ENZ-r). This highlights the necessity for developing novel therapeutic targets to combat the gain of resistance. Metformin has been recently investigated for its potential anti-tumorigenic effects in many cancer types. In this study, we used enzalutamide and metformin in combination to explore the possible rescued efficacy of enzalutamide in the treatment of ENZ-r CRPC. We first tested the effects of this combination treatment on cell viability, drug synergy, and cell proliferation in ENZ-r CRPC cell lines. After combination treatment, we observed a decrease in cell proliferation and viability as well as a synergistic effect of both enzalutamide and metformin in vitro Following these results, we sought to explore how combination treatment effected mitochondrial fitness utilizing mitochondrial stress test analysis and mitochondrial membrane potential (MMP) shifts due to metformin's action in inhibiting Complex I of oxidative phosphorylation. We employed 2 different strategies of in vivo testing using 22Rv1 and LuCaP35CR xenograft models. Finally, RNA sequencing revealed a potential link in the downregulation of Ras/MAPK signaling following combination treatment. Significance Statement Increasing evidence suggests that oxidative phosphorylation might play a critical role in the development of resistance to cancer therapy. We showed that targeting oxidative phosphorylation with metformin can enhance the efficacy of enzalutamide in castration-resistant prostate cancer in vitro.

NFYA-mediated promotion of castration-resistant prostate cancer progression through EGR4 regulation

This research investigates the intricate involvement of nuclear Transcription Factor Y Subunit Alpha (NFYA) in the advancement of castration-resistant prostate cancer (CRPC) and its consequential impact on early Growth Response 4 (EGR4) expression. NFYA demonstrates a significant elevation in CRPC tissues and cell lines, displaying robust upregulation in metastatic prostate cancer (mPCa) samples, closely associated with the Gleason score. Immunohistochemistry validates heightened nuclear staining of NFYA in CRPC patients, highlighting its crucial role in the progression of advanced prostate cancer. Silencing NFYA through siRNA in androgen-independent cell lines markedly impedes cell growth and migration, emphasizing NFYA’s pivotal role in promoting CRPC behavior. RNA-seq analysis identifies EGR4 as a downstream target of NFYA, with both genes consistently upregulated in CRPC. Validating this finding, heightened expression of EGR4 is observed in CRPC samples. In vivo studies utilizing a mouse model demonstrate that NFYA silencing substantially inhibits LNCaP-AI/22RV1shNFYA xenograft tumor growth, accompanied by reduced expression of EGR4 and Ki67. This comprehensive study reveals the multifaceted role of NFYA in CRPC progression, elucidates its downstream impact on EGR4, and underscores the therapeutic potential of targeting NFYA to inhibit CRPC growth in vivo. These findings contribute valuable insights into potential therapeutic strategies for managing CRPC.

9316 Modulation Of Intracellular Lipid Access By ATGL Determines Ferroptosis Sensitivity In Castration-resistant Prostate Cancer

Abstract Disclosure: P. Cao: None. D. Awad: None. J. Han: None. D.E. Frigo: Grant Recipient; Self; GTx, Inc.. Other; Self; Familial relationship with Biocity Biopharmaceuticals, Hummingbird Bioscience, Bellicum Pharmaceuticals, Maia Biotechnology, Alms Therapeutics, Hinova Pharmaceuticals and Barricade Therapeutics. Ferroptosis induction has recently been recognized as a novel therapeutic approach to alter the outcomes of drug-resistant cancer. Ferroptosis is cell death that is caused by the intracellular accumulation of toxic lipid hydroperoxides. Due to their elevated metabolism, castration-resistant prostate cancer (CRPCs) are highly prone to ferroptosis; yet, many of them manage to avert this cellular fate. We have identified a key enzyme involved in lipid metabolism, adipose triglyceride lipase (ATGL), that engenders CRPCs with the ability to resist ferroptosis. Our data has shown that ATGL deletion by CRISPR-Cas9 knockout method sensitized human CRPC cell lines such as C4-2, C4-2BLT, and PC3 cells to the ferroptosis inducer RSL3. In all cases, RSL3-mediated cell death could be blocked by the antioxidant Ferrostatin-1, confirming ferroptosis as the mechanism of cell death. Knocking out ATGL also augmented the ferroptosis inducer-mediated increase in lipid peroxides as indicated by the increased ratio of oxidized to non-oxidized C11-BODIPY 581/591. With regards to the mechanism for the sensitivity of ATGL KO to ferroptosis induction, previous research has established that the enzyme long-chain acyl-CoA synthetase 4 (ACSL4) is universally essential to facilitate ferroptosis. More specifically, ATGL(PNPLA2) was found to inversely correlate with ACSL4 in the Taylor et al., the TCGA PanCancer Atlas, and Metastatic Prostate Adenocarcinoma (SU2C/PCF Dream Team) datasets in both primary and metastatic tumors. qPCR and western blot analysis of ACSL4 levels further showed that ACSL4 expression is closely tied to the lipase activity of ATGL. Addition of arachidonic acid significantly induced ferroptosis when combined with RSL3 in a dose-dependent manner only in ATGL KO cells. This indicates that PUFAs can render ATGL KO cells even more sensitive to RSL3-induced ferroptosis while cells with functional ATGL remain highly resistant, further reinforcing that ATGL is an essential safeguard of CRPC against ferroptosis. ATGL KO cells also demonstrated sensitivity to the antiandrogen Enzalutamide. The combination of Enzalutamide and RSL3 substantially decreased cell viability in ATGL KO cells as compared to control cells, indicating a strong synergy effect particularly seen in ATGL KO cells. In summary, this work demonstrates that ATGL is an important and novel regulator of ferroptosis in CRPC and supports the use of ferroptosis inducer as a new therapeutic approach in CRPC. Presentation: 6/2/2024

Evaluation of glucocorticoid-related genes reveals GPD1 as a therapeutic target and regulator of sphingosine 1-phosphate metabolism in CRPC

Prostate cancer (PCa) is an androgen-dependent disease, with castration-resistant prostate cancer (CRPC) being an advanced stage that no longer responds to androgen deprivation therapy (ADT). Mounting evidence suggests that glucocorticoid receptors (GR) confer resistance to ADT in CRPC patients by bypassing androgen receptor (AR) blockade. GR, as a novel therapeutic target in CRPC, has attracted substantial attention worldwide. This study utilized bioinformatic analysis of publicly available CRPC single-cell data to develop a consensus glucocorticoid-related signature (Glu-sig) that can serve as an independent predictor for relapse-free survival. Our results revealed that the signature demonstrated consistent and robust performance across seven publicly accessible datasets and an internal cohort. Furthermore, our findings demonstrated that glycerol-3-phosphate dehydrogenase 1 (GPD1) in Glu-sig can significantly promote CRPC progression by mediating the cell cycle pathway. Additionally, GPD1 was shown to be regulated by GR, with the GR antagonist mifepristone enhancing the anti-tumorigenic effects of GPD1 in CRPC cells. Mechanistically, targeting GPD1 induced the production of sphingosine 1-phosphate (S1P) and enhanced histone acetylation, thereby inducing the transcription of p21 that involved in cell cycle regulation. In conclusion, Glu-sig could serve as a robust and promising tool to improve the clinical outcomes of PCa patients, and modulating the GR/GPD1 axis that promotes tumor growth may be a promising approach for delaying CRPC progression.

Selective killing of castration-resistant prostate cancer cells by formycin A via the ATF4-CHOP axis.

Prostate cancer is initially androgen-dependent but often relapses to an androgen-independent state called castration-resistant prostate cancer (CRPC). Currently approved therapies have limited efficacy against CRPC, highlighting the need for novel therapeutic strategies. To address this need, we conducted a drug screen in our previously established aggressive CRPC cell model. We found that formycin A induced cell death in CRPC model cells but not in parental prostate cancer cells. In addition, formycin A upregulated death receptor 5 through the induction of endoplasmic reticulum stress, activating the "extrinsic" apoptosis pathway in CRPC model cells. Moreover, formycin A showed invivo antitumor efficacy against CRPC xenografts in castrated nude mice. Thus, our findings highlight the potential of formycin A as a CRPC therapeutic.

Design, synthesis and biological evaluation of dual inhibitors targeting AR/AR-Vs and PARP1 in castration resistant prostate cancer therapy

The combination of androgen signaling inhibitors and PARP inhibitors has shown promising results in clinical trials for the treatment of castration-resistant prostate cancer (CRPC). Multi-target inhibitors can inhibit tumors through different pathways, addressing the limitations of traditional single target inhibitors. We designed and synthesized dual inhibitors targeting AR/AR-Vs and PARP1 using a pharmacophore hybridization strategy. The most potent compound, II-3, inhibits AR/AR-Vs signaling and induces DNA damage by inhibiting PARP1. The IC50 values of II-3 in the castration-resistant prostate cancer cell lines 22RV1 and C4–2 are 4.38 ± 0.56 µM, and 3.44 ± 0.63 µM, respectively. II-3 not only suppresses the proliferation and migration of 22RV1 and C4–2 cells, but also promotes their apoptosis. Intraperitoneal injection of II-3 effectively inhibits tumor growth in 22RV1 xenograft nude mice without evident drug-induced toxicity. Overall, a series of novel dual inhibitors targeting AR/AR-Vs and PARP1 were designed and synthesized, and meanwhile the in vivo and in vitro effects were comprehensively explored, which provided a potential new therapeutic strategy for CRPC.

Abstract C049: Aryl hydrocarbon receptor activity promotes cancer progression and drug resistance in castration-resistant prostate cancer cells

Abstract The aryl hydrocarbon receptor (AhR) is a nuclear transcription factor, xenobiotic sensor, and has a role in regulating diet-induced obesity. We report constitutive overexpression and activity of AhR promotes progression to androgen independence, proliferation, and mediates drug resistance in metastatic castration-resistant prostate cancer (CRPC) in vitro models. RNAseq analysis identified differentially expressed genes (DEGS) which may further implicate the role of AhR in prostate cancer progression. Recent evidence demonstrates significant changes in the expression profile of these genes in response to treatment with chemotherapeutics, specifically bromocriptine (Wu et al 2023). We also confirmed AhR inhibits drug-induced apoptosis in C4-2 cells. Further understanding of the molecular mechanisms governing AhR-mediated cancer progression and drug resistance should expand treatment options and improve patient outcomes. Citation Format: Kofi K. Khamit-Kush, Nathan J. Bowen, Jeffrey A. Handy, Joann B. Powell. Aryl hydrocarbon receptor activity promotes cancer progression and drug resistance in castration-resistant prostate cancer cells [abstract]. In: Proceedings of the 17th AACR Conference on the Science of Cancer Health Disparities in Racial/Ethnic Minorities and the Medically Underserved; 2024 Sep 21-24; Los Angeles, CA. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2024;33(9 Suppl):Abstract nr C049.

Abstract C052: Proteomics analysis of enzalutamide-treated castration-sensitive and castration-resistant prostate cancer cell lines

Abstract INTRODUCTION: Androgen deprivation therapy (ADT) is the standard treatment for metastatic prostate cancer, a disease that disproportionately affects African Americans. However, tumors often progress to metastatic castration-resistant prostate cancer (mCRPC). Enzalutamide (ENZ) and other treatments initially work well for mCRPC, but their effectiveness decreases due to the evolution of tumor resistance. OBJECTIVE: Our study investigates how ENZ alters biological pathways in castration-sensitive (CS) and castration-resistant (CR) cell lines. We aim to compare whole-proteome expression profiles of two metastatic prostate cancer cell lines, LNCaP (CS) and C4-2B (CR), following ENZ exposure. METHODS: Both cell lines were treated with dihydrotestosterone alone (DHT group), ENZ alone (ENZ group), or a combination of DHT + ENZ. All cell lines were grown in Charcoal-stripped serum for 24 hours prior to ENZ and DHT exposure to remove trace androgens in the growth media. Proteins were analyzed using LC-MS/MS (Liquid Chromatography multi-stage mass spectrometry) shotgun proteomics. PEAKS Studio software (version 11) was used for proteomics-based expression analysis against the UniProt human reference proteome database (UP000005640). The differentially expressed protein lists were mapped to corresponding biological pathways in KEGG and REACTOME databases for enrichment analysis using the WEBGESTALT web-app. RESULTS: In total, 2,344 proteins were identified with high ID stringency (Q-value > 20) in the C4-2B cell line. Using Label-Free Quantitation, we observed 32 Differentially Expressed Proteins (DEPs) in the ENZ group, 7 DEPs in the DHT group, and 82 DEPs in the combined DHT + ENZ group. DEPs were mapped to biological pathways in KEGG and REACTOME databases for enrichment analysis using the WEBGESTALT web-app. Notable pathways with significant enrichment score values included “mRNA degradation (KEGG Hsa03018)”, “Rho-GTPase-based activation (REACTOME #R-HSA-5625900; #R-HSA-5627117)", and “Interleukin-12 (IL-12) (REACTOME #R-HSA-9020591)” pathways. CONCLUSION: The “mRNA degradation pathway” was significantly enriched in the ENZ group. This suggests direct effects on protein expression regulation, potentially leading to adaptive protein synthesis that supports resistance. The “Rho-GTPase” and “IL-12" pathways were significantly enriched in the DHT + ENZ group, suggesting potential complex changes in cell signaling and immune interactions that may promote resistance by altering the tumor microenvironment and enabling cancer cells to adapt or evade the immune system. NEXT STEPS: Ongoing analysis of LNCaP (CS) proteomics data aims to reveal significant protein expression changes and affected cellular pathways following ENZ exposure. The goal is to identify proteome-wide cellular pathway alterations in elucidating castration-sensitive and -resistant prostate cancer subtypes. Citation Format: Lincoln E. Liburd II, Victor Paromov, Siddharth Pratap, LaMonica Stewart. Proteomics analysis of enzalutamide-treated castration-sensitive and castration-resistant prostate cancer cell lines [abstract]. In: Proceedings of the 17th AACR Conference on the Science of Cancer Health Disparities in Racial/Ethnic Minorities and the Medically Underserved; 2024 Sep 21-24; Los Angeles, CA. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2024;33(9 Suppl):Abstract nr C052.

Targeting proliferating cell nuclear antigen enhances ionizing radiation-induced cytotoxicity in prostate cancer cells.

Proliferating cell nuclear antigen (PCNA) is essential for DNA replication and repair, cell growth, and survival. PCNA also enhances androgen receptor (AR) signaling in prostate cancer (PC) cells. We identified a PCNA interaction protein (PIP) box at the N-terminal domain of AR and developed a small peptide PCNA inhibitor R9-AR-PIP containing AR PIP-box. We also identified a series of small molecule PCNA inhibitors (PCNA-Is) that bind directly to PCNA and interrupt PCNA functions. The present study investigated the effects of the PCNA inhibitors on the sensitivity of PC cells to X-ray radiation. The effects of targeting PCNA on radio sensitivity of PC cells were investigated in four lines of castration-resistant PC (CRPC) cells with different AR expression statuses. The cells were treated with the PCNA inhibitors and X-ray radiation alone or in combination. The effects of the treatment on expression of AR target genes, DNA damage response, DNA damage, homologous recombination repair (HRR), and cytotoxicity were evaluated. We found that the androgen response element (ARE) occupancy of the DNA damage response gene PARP1 by AR is significantly attenuated by PCNA-I1S or R9-AR-PIP combined with X-ray radiation, while X-ray radiation alone does not enhance the ARE occupancy. PCNA-I1S or R9-AR-PIP alone significantly inhibits occupancy of the AR-occupied regions (AROR) in PRKDC and XRCC2 genes. R9-AR-PIP and PCNA-I1S inhibit expression of AR-Vs target gene cyclin A2 and show the additive effects with radiation in AR-positive CRPC cells. Targeting PCNA by PCNA-I1S and R9-AR-PIP downregulates expression of DNA damage response genes EXO1, Rad54L, Rad51, and/or PARP1 and shows the additive effects with radiation as compared with their respective controls in AR-positive CRPC LNCaP-AI, 22Rv1, and R1-D567 cells, but not in AR-negative PC-3 cells. R9-AR-PIP and PCNA-I1S elevate the levels of phospho-DNA-PKcs(S2056) and γH2AX, indicating DNA damage in response to radiation in AR-positive cells. The HRR is significantly attenuated by PCNA inhibitors PCNA-I1S, R9-AR-PIP, and T2AA in all four CRPC cells examined, and inhibited by Enzalutamide (Enz) only in 22RV1 cells. The cytotoxicity induced by X-ray radiation in androgen-dependent LNCaP cells is enhanced by Enz and a lower concentration of R9-AR-PIP in the colony formation assay. R9-AR-PIP at higher concentration reduces the colony formation and has an additive effect with X-ray radiation in all AR expressing cells, regardless of AR-FL and AR-Vs, but does not significantly alter the colony formation in AR-negative PC-3 cells. PCNA-I1S attenuates colony formation and has an additive effect with ionizing radiation in all four CRPC cells, regardless of AR expression status. These data provide a strong rationale for the therapy studies using PCNA-I1S or R9-AR-PIP in combination with X-ray radiation against CRPC tumors in preclinical models.

L1CAM mediates neuroendocrine phenotype acquisition in prostate cancer cells.

A specific type of prostate cancer (PC) that exhibits neuroendocrine (NE) differentiation is known as NEPC. NEPC has little to no response to androgen deprivation therapy and is associated with the development of metastatic castration-resistant PC (CRPC), which has an extremely poor prognosis. Our understanding of genetic drivers and activated pathways in NEPC is limited, which hinders precision medicine approaches. L1 cell adhesion molecule (L1CAM) is known to play an oncogenic role in metastatic cancers, including CRPC. However, the impact of L1CAM on NEPC progression remains elusive. L1CAM expression level was investigated using public gene expression databases of PC cohorts and patient-derived xenograft models. L1CAM knockdown was performed in different PC cells to study in vitro cell functions. A subline of CRPC cell line CWR22Rv1 was established after long-term exposure to abiraterone to induce NE differentiation. The androgen receptor-negative cell line PC3 was cultured under the tumor sphere-forming condition to enrich cancer stemness features. Several oxidative stress inducers were tested on PC cells to observe L1CAM-mediated gene expression and cell death. L1CAM expression was remarkably high in NEPC compared to CRPC or adenocarcinoma tumors. L1CAM was also correlated with NE marker expressions and associated with the adenocarcinoma-to-NEPC progression in gene expression databases and CRPC cells with NE differentiation. L1CAM also promoted cancer stemness and NE phenotypes in PC3 cells under cancer stemness enrichment. L1CAM was also identified as a reactive oxygen species-induced gene, by which L1CAM counteracted CRPC cell death triggered by ionizing radiation. Our results unveiled a new role of L1CAM in the acquisition of the NE phenotype in PC, contributing to the NE differentiation-related therapeutic resistance of CRPC.

YTHDF3 Regulates the Degradation and Stability of m6A-Enriched Transcripts to Facilitate the Progression of Castration-Resistant Prostate Cancer.

RNA N6-methyladenosine (m6A) readers mediate cancer progression. However, the functional role and potential mechanisms of the m6A readers in prostate cancer tumorigenicity remain to be elucidated. In this study, we demonstrate that YTHDF3 expression is elevated in castration-resistant prostate cancer (CRPC) and positively correlated to high grade, bone metastasis and poor survival. YTHDF3 expression promoted CRPC cell proliferation, epithelial to mesenchymal transition (EMT) and tumour progression. Mechanistically, YTHDF3 promoted the RNA degradation of SPOP and NXK3.1 but stabilized RNA expressions of TWIST1 and SNAI2 dependent on m6A to facilitate cell proliferation and EMT. Additionally, YTHDF3 expression enhanced AKT activity via degrading SPOP in an m6A-dependent manner. Importantly, we found that melatonin can compete with m6A to occupy the m6A-binding cage of YTHDF3, leading to inhibition of YTHFD3 and its target expressions as well as CRPC tumour growth. Our findings uncover an essential role of YTHDF3 in the progression of CRPC and highlight the role of melatonin in anti-CRPC activity.

Investigating miR-6880-5p in extracellular vesicle from plasma as a prognostic biomarker in endocrine therapy-treated castration-resistant prostate cancer

BackgroundAdvancements in the diagnosis, treatment, and surveillance of castration-resistant prostate cancer (CRPC) have progressed considerably, but a new biomarker that combines existing clinical and pathological data could be useful for a more precise diagnosis and prognosis. Some investigations have found that extracellular vesicle (EV)-derived miRNAs play crucial roles in various types of malignant tumors. The objective of this study was to explore EV miRNA and identify its biologic function as a biomarker for the diagnosis and prognosis of CRPC.MethodsPlasma samples were collected from five healthy donors (Control, CT) and 17 CRPC patients, categorizing into two groups based on their endocrine treatment response: partial response (PR; n = 10) and progressive disease (PD; n = 7). Candidate extracellular vesicle (EV) miRNAs were identified using miRNA microarray and RT-qPCR. The biological functions of the selected miRNAs were evaluated using the MTT assay, wound healing assay, trans-well assay, and RNA sequencing in CRPC cells after transient miRNA expression.ResultsMicroarray analysis revealed a significant downregulation of EV-miR-6880-5p in the PD samples compared to both CT and PR samples (p < 0.01). The expression of EV-miR-6880-5p in CRPC patients was decreased compared with that CT group (p = 0.0336) using RT-qPCR. In the PR group, EV-miR-6880-5p was increased at follow-up compared with the baseline (p = 0.2803), while in the PD group, it decreased at follow-up compared with the baseline samples (p = 0.4356). Furthermore, overexpression of miR-6880-5p hampered cell proliferation, migration, and invasion, downregulated pathways associated with tumor progression, and simultaneously upregulated pathways associated with cell growth and apoptosis in CRPC cells.ConclusionsEV-miR-6880-5p shows promise as a prognostic biomarker in patients with CRPC. Further, prospective validations are necessary to evaluate the potential of these candidate miRNAs.

DNA aptamer-conjugated lipid nanoparticle for targeted PTEN mRNA delivery to prostate cancer cells

The use of messenger RNA (mRNA) as a cancer vaccine and gene therapy requires targeted vehicle delivery to the site of disease. Here, we designed a mRNA-encapsulating lipid nanoparticle (LNP) conjugated with anti-programmed death-ligand 1 (PD-L1) DNA aptamer that delivers mRNA encoding a tumor suppressor gene, namely phosphatase and tensin homolog (PTEN), to castration-resistant prostate cancer (CRPC) cells expressing PD-L1 on the cell surface. The DNA aptamer-conjugated LNP-based mRNA delivery system (Apt-LNP[PTEN mRNA]) mediated efficient mRNA delivery and transfection in CRPC cells than LNPs without targeting ligands. Cancer-targeted PTEN mRNA delivery using Apt-LNPs achieved significantly higher PTEN expression via aptamer-mediated endocytosis in target cancer cells compared with non-targeted LNP delivery, resulting in significant downregulation of AKT phosphorylation. This enhanced PI3K/AKT pathway regulation, and in turn reduced cell migration after two days along with a 70 % decrease in cell viability, leading to effective apoptotic cell death. In a CRPC xenograft model, Apt-LNP[PTEN mRNA] led to an approximate 60 % reduction in tumor growth, which was attributable to the effective PTEN restoration and PI3K/AKT signaling pathway regulation. PTEN expression was significantly enhanced in CRPC tumor tissues, which abolished cancer cell tumorigenicity. These findings demonstrated the potential of Apt-LNPs for targeted mRNA delivery to cancer cells, thus providing a promising tool for targeted mRNA delivery to a range of cancers and tissues using a conventional LNP systems.

A Zwitterionic Detergent and Catalyst-Based Single-Cell Proteomics Using a Loss-Free Microhole-Collection Disc.

Recent advances in single-cell proteomics have solved many bottlenecks, such as throughput, sample recovery, and scalability via nanoscale sample handling. In this study, we aimed for a sensitive mass spectrometry (MS) analysis capable of handling single cells with a conventional mass spectrometry workflow without additional equipment. We achieved seamless cell lysis and TMT labeling in a micro-HOLe Disc (microHOLD) by developing a mass-compatible single solution based on a zwitterionic detergent and a catalyst for single-cell lysis and tandem mass tag labeling without a heat incubation step. This method was developed to avoid peptide loss by surface adsorption and buffer or tube changes by collecting tandem mass tag-labeled peptide through microholes placed in the liquid chromatography injection vials in a single solution. We successfully applied the microHOLD single-cell proteomics method for the analysis of proteome reprogramming in hormone-sensitive prostate cells to develop castration-resistant prostate cancer cells. This novel single-cell proteomics method is not limited by cutting-edge nanovolume handling equipment and achieves high throughput and ultrasensitive proteomics analysis of limited samples, such as single cells.