Promotes Prostate Cancer Growth Research Articles

Stromal-derived MAOB promotes prostate cancer growth and progression.

Prostate cancer (PC) develops in a microenvironment where the stromal cells modulate adjacent tumor growth and progression. Here, we demonstrated elevated levels of monoamine oxidase B (MAOB), a mitochondrial enzyme that degrades biogenic and dietary monoamines, in human PC stroma, which was associated with poor clinical outcomes of PC patients. Knockdown or overexpression of MAOB in human prostate stromal fibroblasts indicated that MAOB promotes cocultured PC cell proliferation, migration, and invasion and co-inoculated prostate tumor growth in mice. Mechanistically, MAOB induces a reactive stroma with activated marker expression, increased extracellular matrix remodeling, and acquisition of a protumorigenic phenotype through enhanced production of reactive oxygen species. Moreover, MAOB transcriptionally activates CXCL12 through Twist1 synergizing with TGFβ1-dependent Smads in prostate stroma, which stimulates tumor-expressed CXCR4-Src/JNK signaling in a paracrine manner. Pharmacological inhibition of stromal MAOB restricted PC xenograft growth in mice. Collectively, these findings characterize the contribution of MAOB to PC and suggest MAOB as a potential stroma-based therapeutic target.

Abstract C061: GNL3 promotes prostate cancer growth by regulating androgen receptor protein stability

Abstract Androgen receptor (AR) is a primary driver of prostate cancer growth and development. Changes in AR coregulatoractivity or expression have severe consequences on the development of the disease. Using ChIP-MS, we discover G Protein Nucleolar 3 (GNL3) as a new AR transcriptional coactivator. We show that GNL3 helps the recruitment of AR to chromatin to directly control genes that support prostate cancer growth. We also demonstrate that GNL3 stabilizes AR by protecting it from ubiquitination and proteasomal degradation. We further determine that GNL3 is required for tumor progression by preventing cell-cycle arrest and apoptosis. Moreover, depleting GNL3 causes prostate cancer cells to be more susceptible to AR antagonists. Our work also indicates that Palbociclib, a CDK4/6 inhibitor, can be combined with enzalutamide to suppress cancer cell growth by downregulating AR and GNL3 co-regulated genes. From patient analyses, we observe that GNL3 expression is significantly elevated in many clinical studies. Finally, we reveal an AR-GNL3 gene signature in prostate tumors that is highly expressed and predicts disease recurrence. In summary, our results highlightthat GNL3 is a novel coactivator of AR and a potential target for the treatment of prostate cancer. Citation Format: Edwin Cheung, Cuiting Zhang. GNL3 promotes prostate cancer growth by regulating androgen receptor protein stability [abstract]. In: Proceedings of the AACR-NCI-EORTC Virtual International Conference on Molecular Targets and Cancer Therapeutics; 2023 Oct 11-15; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2023;22(12 Suppl):Abstract nr C061.

Transposable elements are co-opted as oncogenic regulatory elements by lineage-specific transcription factors in prostate cancer.

Transposable elements hold regulatory functions that impact cell fate determination by controlling gene expression. However, little is known about the transcriptional machinery engaged at transposable elements in pluripotent and mature versus oncogenic cell states. Through positional analysis over repetitive DNA sequences of H3K27ac ChIP-seq data from 32 normal cell states, we report pluripotent/stem and mature cell state-specific "regulatory transposable elements". Pluripotent/stem elements are binding sites for pluripotency factors (e.g. NANOG, SOX2, OCT4). Mature cell elements are docking sites for lineage-specific transcription factors, including AR and FOXA1 in prostate epithelium. Expanding the analysis to prostate tumors, we identify a subset of regulatory transposable elements shared with pluripotent/stem cells, including Tigger3a. Using chromatin editing technology, we show how such elements promote prostate cancer growth by regulating AR transcriptional activity. Collectively, our results suggest that oncogenesis arises from lineage-specific transcription factors hijacking pluripotent/stem cell regulatory transposable elements.

Gain-of-function mutant p53 together with ERG proto-oncogene drive prostate cancer by beta-catenin activation and pyrimidine synthesis

Whether TMPRSS2-ERG fusion and TP53 gene alteration coordinately promote prostate cancer (PCa) remains unclear. Here we demonstrate that TMPRSS2-ERG fusion and TP53 mutation / deletion co-occur in PCa patient specimens and this co-occurrence accelerates prostatic oncogenesis. p53 gain-of-function (GOF) mutants are now shown to bind to a unique DNA sequence in the CTNNB1 gene promoter and transactivate its expression. ERG and β-Catenin co-occupy sites at pyrimidine synthesis gene (PSG) loci and promote PSG expression, pyrimidine synthesis and PCa growth. β-Catenin inhibition by small molecule inhibitors or oligonucleotide-based PROTAC suppresses TMPRSS2-ERG- and p53 mutant-positive PCa cell growth in vitro and in mice. Our study identifies a gene transactivation function of GOF mutant p53 and reveals β-Catenin as a transcriptional target gene of p53 GOF mutants and a driver and therapeutic target of TMPRSS2-ERG- and p53 GOF mutant-positive PCa.

Retracted: mRNA-Modified FUS/NRF2 Signalling Inhibits Ferroptosis and Promotes Prostate Cancer Growth.

[This retracts the article DOI: 10.1155/2022/8509626.].

Abstract A031: A fat lot of good: A novel monounsaturated fatty acid promotes prostate cancer growth and survival

Abstract Advanced prostate cancer (PCa) is currently incurable, and development of novel treatments requires a greater understanding of key pathways that are altered during PCa progression. We have focussed on fatty acid metabolism, as the major source of energy for PCa cells, and have implicated a monounsaturated fatty acid (MUFA), cis-vaccenic acid (cVA), as a critical regulator of PCa cell homeostasis. Production of cVA requires stearoyl-CoA desaturase 1 (SCD1), the enzyme attributed to general MUFA production, and whose activity is important in a range of cancer types. Nonetheless, the specific role of cVA has not previously been studied, in PCa nor cancer more generally. To elucidate the role of cVA in PCa more precisely, we used SCD1 inhibition to study PCa responses to broad MUFA depletion and specific MUFA supplementation, comparing the responses of cVA with its more common structural isomer oleate. To accomplish these aims, we utilised cell line models of PCa (LNCaP, MR49F and V16D) and a benign prostate cell line (PNT1A) to perform cell viability, lipidomic and flow cytometric assays. In addition, responses in clinically-relevant patient-derived tumor explants were measured by proliferative (Ki67) and cell death (CC3) marker staining. Pharmacological SCD1 inhibition (SCDi; A939572) decreased cell viability and increased cell death in PCa cell lines and patient-derived tumor explants, while only minimally affecting the benign prostate cell line PNT1A. Phenotypically, analysis of mitochondrial function and lipidomic changes under SCDi suggested a role for MUFAs in regulating mitochondrial membrane composition via cardiolipins, and oxidative stress levels. This in turn has the potential to regulate cell death, control tumor burden, and influence overall PCa patient survival. Supplementation of cVA or oleate under SCDi demonstrated that only cVA was successful at rescuing cell viability, and cVA, but not oleate, could rescue changes observed in mitochondrial-related lipids, suggesting that cVA regulation of mitochondrial function was a major determinant of its effect on cell viability. Additionally, cVA alone dose-dependently increased PCa cell viability, implicating cVA as an important oncogenic factor. Together, these data identify cVA as a novel substrate required for PCa cell viability, likely via regulation of mitochondrial homeostasis and associated cell death pathways. In summary, this research has revealed more precise insights into the oncogenic effects of an overlooked MUFA, cVA, in PCa, and may uncover new druggable targets that are more selective, to improve treatment options for advanced PCa. Citation Format: Julia S. Scott, Reuben Young, Swati Irani, Jonas Dehairs, Stephen Blanksby, Johannes V. Swinnen, Zeyad D. Nassar, Lisa M. Butler. A fat lot of good: A novel monounsaturated fatty acid promotes prostate cancer growth and survival [abstract]. In: Proceedings of the AACR Special Conference: Advances in Prostate Cancer Research; 2023 Mar 15-18; Denver, Colorado. Philadelphia (PA): AACR; Cancer Res 2023;83(11 Suppl):Abstract nr A031.

The prognostic value of androgen to PSA ratio in predictive modeling of prostate cancer

Prostate specific antigen (PSA) is the ubiquitous biomarker used in mathematical and artificial intelligence models of prostate cancer. Yet, it is imperfect. The growth of prostate and cancer cells produces PSA, but their growth is dependent on androgen in most cases. Thus, looking at PSA by itself ignores the impact of androgen. Here, we propose the use of androgen as a reference framework for better integration of PSA in prostate cancer models. The binding of androgen to androgen receptors activates signals that promote prostate cancer growth and the production of PSA, so higher levels of androgen should correlate to higher growth of the tumor and higher production of PSA. Thus, PSA and androgen fall and rise almost synchronously during the start and stop of androgen deprivation therapy (ADT), respectively. Yet, when cancer cells become resistant to ADT, we observe a divergence to this trend, leading to a high level of PSA even during ADT. Therefore, we hypothesize that the cancer evolutionary dynamics can be represented by the ratio of androgen to PSA and its integration into prostate cancer models may help improve their predictive power.

Long noncoding RNA GHET1 promotes cell proliferation through oxidative stress in prostate cancer.

Gastric carcinoma high expressed transcript 1 (GHET1) is an oncogenic Long noncoding RNA. GHET1 expression promotes multiple levels of developing a complex molecular network. The main purpose of the study was to investigate the mechanism by which long noncoding RNA (lncRNA) GHET1 promotes prostate cancer cell proliferation and related metabolism. In vitro study, lncRNA GHET1 was overexpressed in LN-cap, PC-3, 22RV1, and C4-2 cells. The cell viability was measured by MTT and trans-well assay. A flow cytometer was also used to detect cell cycles and apoptosis. Western blot analysis was used for protein expression validation. mRNA expression was detected by real-time PCR. lncRNA GHET1 enhanced cell proliferation, migration, and could resist paclitaxel-induced apoptosis and cell cycle arrest GHET1 expression stimulates reactive oxygen species (ROS) level upregulated in prostate cancer cells, increased the expression of HIFα, IL-1B and IL-6, and activated ROS/STAT-3/Twsit1 signaling pathway. Knockdown GHET1 could reduce cell proliferation and migration due to the overexpression of GHET1. lncRNA GHET1 promotes prostate cancer growth through oxidative stress signaling pathways and resists the antineoplastic drug paclitaxel, which can be used as a target for antineoplastic therapy and drug resistance therapy in the future in clinics.

Abstract 1409: RNA sequencing reveals that African Americans carrying wild-type CYP3A5 differentially express genes known to promote aggressive prostate cancer

Abstract Background: African American men (AAs) have the highest incidence of prostate cancer (PC) and often develop therapeutic resistance leading to high mortality. The androgen receptor (AR) is paramount in the growth and progression of PC, and insufficient blockade of AR leads to therapeutic resistance. Our previous work shows that CYP3A5 facilitates the activation of AR, promoting the transcription of genes supporting PC growth. CYP3A5 is polymorphic, and the wild-type (wt; *1) variant encoding the full-length active protein is expressed in 73% of AAs and only in 5% of non-Hispanic White Americans (NHWA). The race-linked expression of wt-CYP3A5*1 in AAs can lead to hyperactive AR contributing to therapeutic resistance. We performed an RNA sequencing study utilizing samples from AAs and NWHA patients to understand the allelic influence of CYP3A5 on PC severity. Methods: Illumina RNA sequencing was performed using RNA from 13 AA and 12 NHWA prostatic adenocarcinomas. CYP3A5 genotyping separated them into two groups: a) carrying wt-CYP3A5 (*1/*1 and *1/*3; N=14); and b) mutant CYP3A5 (*3/*3; N=11) variants. The samples’ ancestry was confirmed using markers previously described. Differentially expressed genes (DEGs) between wt-*1 and mutant-*3 CYP3A5 carrying groups were identified using DESeq2, at a false discovery rate of adjusted p < 0.05. Alternately we also used the Kallisto method for quantifying the abundances of the transcript from RNA seq data. Results: Aligned RNA reads with the human genome using DESeq2 resulted in the identification of 30 DEGs between the two groups, of these, 14 genes are known to be dysregulated in PC and promote aggressive disease (SEMG2, ZNRF3, CCL18, U3, MT-ND6, SCARNA9, NRCAM, LINC00853, TCF4, SLC38A6, HHLA3, DECR1, THTPA, and NEFH). Aberrant TCF4 along with ZNRF3 is known to promote PC growth via Wnt-beta catenin signaling. SLC38A6 is a glutamine transporter and is often upregulated in PC to promote glutamine uptake in an AR-dependent manner. NEFH is an intermediate filament protein that is downregulated in PC metastasis. Kallisto method identified 84 DEGs, 11 of those genes overlap with the previous DFGs identified using the transcriptome alignment method. The additional DFGs identified with the Kallisto method include aberrant expression of multiple genes (MT-CO1/2, MT-ND1/6) involved in mitochondrial dysfunction known to contribute towards cell growth and tumorigenesis beyond the Warburg effect. The wt-*1 CYP3A5 expressing group also shows increased expression of several pseudogenes, dysregulation of pseudogenes has been observed in several cancers and can act as a master regulator for gene expression, promoting tumorigenesis. Conclusion: The presence of wt-*1 CYP3A5 may be one of the factors leading to aggressive PC in AAs as it shows differential expression of several genes known to accelerate PC growth. Citation Format: Jeetesh Sharma, Richard Tillett, Shirley Shen, Jabril Johnson, Rick A. Kittles, Mohammad Saleem Bhat, Oscar Goodman Jr, Edwin C. Oh, Ranjana Mitra. RNA sequencing reveals that African Americans carrying wild-type CYP3A5 differentially express genes known to promote aggressive prostate cancer [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 1409.

Genome-Wide CRISPR-Cas9 Screening and Identification of Potential Genes Promoting Prostate Cancer Growth and Metastasis.

Identification and validation of genes that functionally account for the growth and metastasis of prostate cancer. DU145-KO cell line was constructed by transfecting DU145 cells with lentivirus packaged with the genome-wide knock-out library. The DU145-KO cells were transplanted into the armpits of immunocompromised Nu/Nu mice, followed by the tissue collection from the lung at week 3 (early lung tissue) or week 7 (late lung tissue with micro-metastasis), as well as from primary tumor site at week 7 (late primary tumor) after inoculation. Lung metastasis was retrieved at various time points for DNA sequencing analysis to identify enriched sgRNAs, thus candidate genes/miRNAs. Further bioinformatics analysis and limited functional validation studies were carried out. DU145-KO cells promoted the formation of transplanted tumors in mice and promoted the growth and metastasis of primary tumors, compared to the controls (DU145-NC cells). The analysis of sequence data showed that the abundance of sgRNAs significantly changed in the primary tumor and micro-metastasis site. Fifteen target genes (C1QTNF9B, FAM229A, hsa-mir-3929, KRT23, TARS2, CRADD, GRIK4, PLA2G15, LOXL1, SLITRK6, CDC42EP5, SLC2A4, PTGDS, MYL9 and ACOX2 for the enriched sgRNAs) have been selected for experimental validation, which showed that knock-out of any of these genes led to the enhanced potential of invasion and metastasis of DU145 cells. Genome-wide CRISPR-Cas9 knock-out screening technology combined with highthroughput sequencing analysis identified genes that potentially relate to prostate tumor invasion and metastasis. Analysis of these genes provided insights into biological pathways relevant to the disease and disclosed innovative markers for diagnosis or prognosis as well as potential targets for therapy.

CircROBO1 promotes prostate cancer growth and enzalutamide resistance via accelerating glycolysis.

Background and aim: As non-coding RNAs, circular RNAs (circRNAs) contribute to the progression of malignancies by regulating various biological processes. In prostate cancer, however, there is still a lack of understanding regarding the potential molecular pathways and roles of circRNAs. Methods: Loss-off function experiments were performed to investigate the potential biological function of circRNA in the progression of prostate cancer. Western blot, qRT-PCR, and IHC assay were used to examine the expression level of different genes or circRNAs. Further molecular biology experiments were conducted to uncover the molecular mechanism underlying circRNA in prostate cancer using dual luciferase reporter and RNA immunoprecipitation (RIP) assays. Results: A novel circRNA (hsa_circ_0124696, named circROBO1) was identified as a significantly upregulated circRNA in both prostate cancer cells and tissues. Suppression of circROBO1 significantly attenuated the proliferation of prostate cancer cells. In addition, we found that the knockdown of circROBO1 remarkably increased the sensitivity of prostate cancer to enzalutamide treatment. A deceleration in glycolysis rate was observed after inhibition of circROBO1, which could suppress prostate cancer growth and overcome resistance to enzalutamide. Our results revealed that circROBO1 promotes prostate cancer growth and enzalutamide resistance via accelerating glycolysis. Conclusion: Our study identified the biological role of the circROBO1-miR-556-5p-PGK1 axis in the growth and enzalutamide resistance of prostate cancer, which is the potential therapeutic target of prostate cancer.

Chaihu-Shugan-San ameliorates tumor growth in prostate cancer promoted by depression via modulating sphingolipid and glycerinphospholipid metabolism.

Background: Psychologic depression is a pivotal pathological characteristic and has been shown to promote prostate cancer (PCa) progression. Chaihu-Shugan-San (CSS), a well-known Chinese herbal decoction, exhibits efficacy in the treatment of stress-accelerated PCa. However, the underlying mechanism of CSS in resisting PCa growth is still unknown, and further study is needed. Objective: To evaluate the effects of CSS on stress-accelerated PCa in a BALB/C nude mice model and to investigate the underlying mechanisms. Methods: PC-3 cells were implanted into BALB/C nude mice, and the stressed mice were exposed to chronic unpredictable mild stress (CUMS) to study the effects of CSS. The PCa growth were evaluated by tumor volume and tumor weight. Analyses of depression-like behaviors were evaluated by sucrose consumption test, tail suspension test and open field test. Network pharmacology was used to analyze the potential targets and signaling pathways of CSS against PCa. Untargeted lipidomics were used to analyze the serum lipid profiles and further elucidate the possible mechanism. Results: In the CUMS stressed PCa mice, CSS can restrain tumor growth with reduced tumor volume and tumor weight, and depression-like behaviors with increased sucrose consumption, reduced immobility duration, and increased total distance and center distance. Network pharmacology suggested that the lipid metabolism-related pathways are the most likely potential targets of CSS against PCa. Using untargeted lipidomics analysis, 62 lipids were found to have significant changes in PCa mice under CUMS treatment. The levels of glycerophospholipids containing phosphatidylcholine (PC), phosphatidylethanolamine (PE), phosphatidylinositol (PI) and phosphatidylglycerol (PG), except PC (18:0_22:6) and PC (18:0_20:4), were significantly increased. Likewise, the levels of all sphingolipids (including sphingomyelin (SM), ceramides (Cer) and hexosyl-1-ceramide (Hex1Cer)) and diglyceride (DG) (32:1e) were significantly increased. CSS water extract was found to contribute to restore 32 lipids including 6 sphingolipids, 25 glycerophospholipids and 1 glyceride. Conclusion: This study is the first to delineate the lipid profile of stressed PCa BALB/C nude mice using untargeted lipidomics analysis. CSS restrained tumor growth and ameliorated depression-like behaviors by reprogramming lipid metabolism. Intervention of lipid metabolism could be a preventive and therapeutic approach for PCa patients with depression.

Extensive metabolic consequences of human glycosyltransferase gene knockouts in prostate cancer

BackgroundNaturally occurring germline gene deletions (KO) represent a unique setting to interrogate gene functions. Complete deletions and differential expression of the human glycosyltransferase UGT2B17 and UGT2B28 genes are linked to prostate cancer (PCa) risk and progression, leukaemia, autoimmune and other diseases.MethodsThe systemic metabolic consequences of UGT deficiencies were examined using untargeted and targeted mass spectrometry-based metabolomics profiling of carefully matched, treatment-naive PCa cases.ResultsEach UGT KO differentially affected over 5% of the 1545 measured metabolites, with divergent metabolic perturbations influencing the same pathways. Several of the perturbed metabolites are known to promote PCa growth, invasion and metastasis, including steroids, ceramides and kynurenine. In UGT2B17 KO, reduced levels of inactive steroid-glucuronides were compensated by sulfated derivatives that constitute circulating steroid reservoirs. UGT2B28 KO presented remarkably lower levels of oxylipins paralleled by reduced inflammatory mediators, but higher ceramides unveiled as substrates of the enzyme in PCa cells.ConclusionThe distinctive and broad metabolic rewiring caused by UGT KO reinforces the need to examine their unique and divergent functions in PCa biology.

Modulation of Plasma Lipidomic Profiles in Metastatic Castration-Resistant Prostate Cancer by Simvastatin.

Simple SummaryMen with metastatic castration-resistant prostate cancer (mCRPC) have shorter overall survival and resist therapy faster if their blood have a poor lipid profile. This poor lipid profile includes high levels of sphingolipids, thus reducing these sphingolipids may slow prostate cancer growth. The aim of our study is to determine if simvastatin can change a poor lipid profile (high sphingolipids) into a better profile (low sphingolipids) in mCRPC. Twenty-seven men with mCRPC were given simvastatin together with their standard treatment for 12 weeks. We found that 11 men had the poor lipid profile at the start of the study. After 12 weeks of treatment, 40% of these 11 men no longer had the poor lipid profile and their sphingolipids were reduced, regardless of changes in their blood cholesterol, LDL or triglycerides. In conclusion, simvastatin can modify the poor lipid profile in some men with mCRPC.Elevated circulating sphingolipids are associated with shorter overall survival and therapeutic resistance in metastatic castration-resistant prostate cancer (mCRPC), suggesting that perturbations in sphingolipid metabolism promotes prostate cancer growth. This study assessed whether addition of simvastatin to standard treatment for mCRPC can modify a poor prognostic circulating lipidomic profile represented by a validated 3-lipid signature (3LS). Men with mCRPC (n = 27) who were not on a lipid-lowering agent, were given simvastatin for 12 weeks (40 mg orally, once daily) with commencement of standard treatment. Lipidomic profiling was performed on their plasma sampled at baseline and after 12 weeks of treatment. Only 11 men had the poor prognostic 3LS at baseline, of whom five (45%) did not retain the 3LS after simvastatin treatment (expected conversion rate with standard treatment = 19%). At baseline, the plasma profiles of men with the 3LS displayed higher levels (p < 0.05) of sphingolipids (ceramides, hexosylceramides and sphingomyelins) than those of men without the 3LS. These plasma sphingolipids were reduced after statin treatment in men who lost the 3LS (mean decrease: 23–52%, p < 0.05), but not in men with persistent 3LS, and were independent of changes to plasma cholesterol, LDL-C or triacylglycerol. In conclusion, simvastatin in addition to standard treatment can modify the poor prognostic circulating lipidomic profile in mCRPC into a more favourable profile at twice the expected conversion rate.

A positive feedback loop between tryptophan hydroxylase 1 and β-Catenin/ZBP-89 signaling promotes prostate cancer progression.

Alterations in tryptophan (Trp) metabolism facilitate the continuous modulation of tumor progression, including tumor growth, distant metastasis, and chemoresistance development. Although there is a high correlation between Trp metabolism and tumor progression, it is unknown whether and how Trp metabolism affects the development of prostate cancer. In this study, we reported that the overexpression of Trp hydroxylase 1 (TPH1) caused the upregulation of Trp hydroxylation and mediated the production of 5-hydroxytryptamine (5-HT), contributing to tumor growth and poor prognosis in patients with prostate cancer. An increase in 5-HT levels triggered the activation of the Axin 1/β-catenin signaling pathway, thus enhancing cell proliferation and migration. Consequently, β-catenin cooperated with the Krüppel-type zinc finger family transcription factor ZBP-89 to upregulate TPH1 expression, further promoting Trp hydroxylation and forming the TPH1/5-HT/β-catenin/ZBP-89/THP1 positive feedback signaling loop. Interruption of the signaling loop by the THP1 inhibitor 4-chloro-dl-phenylalanine (PCPA) significantly improved anticancer effects and suppressed lung metastasis in prostate cancer–bearing mice. Our findings revealed a mechanism by which TPH1 promotes prostate cancer growth by inducing Trp hydroxylation and identified a novel THP1 target for an innovative prostate cancer therapeutic strategy.

MRNA-Modified FUS/NRF2 Signalling Inhibits Ferroptosis and Promotes Prostate Cancer Growth.

Objective Regarding the imperfect mechanism of occurrence and development of prostate adenocarcinoma (PRAD), this study investigated mRNA-modified FUS/NRF2 signalling to inhibit ferroptosis and promote prostate adenocarcinoma growth. Methods Bioinformatics analysis was used to obtain the expression of FUS and its mRNA modification in PRAD. The expression of FUS in prostate cells (CRPC) and the level of m6A methylation modification, ferroptosis (P53 and GPX4), apoptosis (Caspase3), ferroptosis (P53 and GPX4), and apoptosis (Caspase3) in CRPC after ferroptosis inducer Erastin, ferroptosis inhibitor, and FUS knockdown were detected. Autophagy (LC3B), oxidative stress (GSH and ROS), and expression of NRF2/HO-1 pathway are indicators. Results FUS was highly expressed in PRAD and phenomenally reduced the survival rate of patients. After knocking down FUS, the level of m6A methylation was significantly reduced, and the expressions of ferroptosis markers P53 and GPX4 were phenomenally reduced, while the levels of apoptosis and autophagy markers Caspase3 and LC3B remained unchanged. Upregulated and NRF2/HO-1 pathway indicators were upregulated. It shows that m6A methylation modification is reduced when FUS is the low expression, inhibits the expression of P53 and GPX4, downregulates GSH, upregulates ROS, activates the NRF2/HO-1 pathway, and promotes ferroptosis to inhibit the occurrence of RPAD. Conclusions The increase of m6A methylation modification can increase the expression of FUS, thereby promoting the expression of P53 and GPX4, upregulating GSH, downregulating ROS, inhibiting the NRF2/HO-1 pathway, inhibiting ferroptosis, and promoting the growth of PRAD.

Prostate tumor RON receptor signaling mediates macrophage recruitment to drive androgen deprivation therapy resistance through Gas6-mediated Axl and RON signaling.

Androgen deprivation therapy (ADT), or chemical castration, is the first-line therapy for prostate cancer; however, resistance leaves few treatment options. Prostatic tumor-associated macrophages (TAMs) have been shown to promote prostate cancer growth and are abundant in castration-resistant prostate cancer (CRPC), suggesting a role in promoting CRPC. We recently showed a tumor cell-intrinsic mechanism by which RON promotes CRPC. Given previous reports that RON alters prostate cancer cell chemokine productionand RON-overexpressing tumors alter macrophage function, we hypothesized that a macrophage-dependent mechanism regulated by tumor cell intrinsic RON also promotes CRPC. Using RON-modulated genetically engineered mouse models (GEMMs) and GEMM-derived cell lines and co-cultures with bone marrow-derived macrophages, we show functional and molecular characteristics of signaling pathways in supporting CRPC. Further, we used an unbiased phosphokinase array to identify pathway interactions regulated by RON. Finally, using human prostate cancer cell lines and prostate cancer patient data sets, we show the relevance of our findings to human prostate cancer. Studies herein show that macrophages recruited into the prostate tumor microenvironment (TME) serve as a source for Gas6 secretion which serves to further enhance RON and Axl receptor activation in prostate tumor cells thereby driving CRPC. Further, we show targeting RON and macrophages in a murine model promotes CRPC sensitization to ADT. We discovered a novel role for the RON receptor in prostate cancer cells in promoting CRPC through the recruitment of macrophages into the prostate TME. Macrophage-targeting agents in combination with RON/Axl inhibition are likely to provide clinical benefits for patients with CRPC.

A mitochondrial unfolded protein response inhibitor suppresses prostate cancer growth in mice via HSP60.

Mitochondrial proteostasis, regulated by the mitochondrial unfolded protein response (UPRmt), is crucial for maintenance of cellular functions and survival. Elevated oxidative and proteotoxic stress in mitochondria must be attenuated by the activation of a ubiquitous UPRmt to promote prostate cancer (PCa) growth. Here we show that the 2 key components of the UPRmt, heat shock protein 60 (HSP60, a mitochondrial chaperonin) and caseinolytic protease P (ClpP, a mitochondrial protease), were required for the development of advanced PCa. HSP60 regulated ClpP expression via c-Myc and physically interacted with ClpP to restore mitochondrial functions that promote cancer cell survival. HSP60 maintained the ATP-producing functions of mitochondria, which activated the β-catenin pathway and led to the upregulation of c-Myc. We identified a UPRmt inhibitor that blocked HSP60’s interaction with ClpP and abrogated survival signaling without altering HSP60’s chaperonin function. Disruption of HSP60-ClpP interaction with the UPRmt inhibitor triggered metabolic stress and impeded PCa-promoting signaling. Treatment with the UPRmt inhibitor or genetic ablation of Hsp60 inhibited PCa growth and progression. Together, our findings demonstrate that the HSP60-ClpP–mediated UPRmt is essential for prostate tumorigenesis and the HSP60-ClpP interaction represents a therapeutic vulnerability in PCa.

Abstract 3266: The KDM5 inhibitor PBIT reduces proliferation of castration-resistant prostate cancers via the induction of senescence

Abstract The members of the KDM5 family of lysine demethylases are best known for their ability to demethylate di- and trimethylated histone H3 at lysine 4 (H3K4me3). However, recent studies suggest at least three family members (KDM5A, KDM5B and KDM5C) promote prostate cancer growth and progression and may serve as effective therapeutic targets for this disease. Previous work from our laboratory has shown that 2-4(4-methylphenyl)-1,2-benzisothiazol-3(2H)-one (PBIT), a compound that inhibits the enzymatic activity of multiple KDM5 isoforms, reduces the viability of castration-resistant prostate cancer cells. The goal of this study was to further characterize the anti-tumor effects of PBIT within human prostate cancers. Two models of human castration-resistant prostate cancer were used to define the effects of PBIT: the androgen receptor (AR) positive C4-2B cells and the PC3 cells, which express little to no AR. Our group initially demonstrated via quantitative RT-PCR analysis that PC3 and C4-2B cells express varying amounts of KDM5A, KDM5B, and KDM5C, the therapeutic targets of PBIT. Presto Blue assays were next performed to determine the extent to which PBIT alters cell proliferation. Micromolar concentrations of PBIT significantly reduced prostate cancer cell proliferation in a time- and concentration-dependent manner. Data from Cell Death ELISAs suggest that PBIT at a concentration of 10 μM did not significantly induce apoptosis within C4-2B or PC3 cells. However, PBIT does appear to induce cellular senescence within the PC3 cell line. The level of senescence associated beta-galactosidase staining was increased in PC3 cells following treatment with 10 μM PBIT. Furthermore, PBIT increased protein levels of a second senescence marker, lamin B1. Together, these data suggest that the induction of senescence contributes to the anti-proliferative effect of PBIT. Citation Format: Tunde M. Smith, Zhenbang Chen, LaMonica V. Stewart. The KDM5 inhibitor PBIT reduces proliferation of castration-resistant prostate cancers via the induction of senescence [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 3266.

Abstract 6156: High-fat diet-induced gut dysbiosis promotes prostate cancer growth through mast cells and histamine 1 receptor

Abstract Introduction and Objective High-fat diet (HFD) induce prostate inflammation and promote cancer growth. However, the mechanism of this inflammation has not been entirely clear. We provide the evidence of new histamine-mediated mechanism and the crucial role of the gut microbiota on HFD-induced prostate cancer (PCa) growth. Methods We compared between HFD-fed and control diet (CD)-fed prostate-specific Pten KO mice at 22 weeks of age as PCa models. HFD-fed mice were given histamine receptor antagonist. Tumor growth was evaluated by prostate weight and Ki67 staining. Gut microbiota compositions were analyzed by 16S rRNA gene sequencing. Histamine signaling in PCa was assessed at gene and protein level. Results HFD significantly increased prostate weight (0.25 vs. 0.46g, P = 0.01) and Ki67-positive cancer cell ratio (0.15 vs. 0.36, P = 0.01). cDNA microarray of PCa showed that expression of Hdc encoding histidine decarboxylase (HDC), which is responsible for histamine production, was upregulated in HFD-fed mice (Fold change = 2.71). The elevated expression of Hdc was also confirmed by quantitative PCR (P &amp;lt; 0.01). Infiltrating mast cells highly produced HDC protein, and mast cell counts around cancer foci were significantly increased in HFD-fed mice. Fexofenadine (Fexo), an H1 blocker, inhibited HFD-induced PCa growth, while ranitidine, an H2 blocker, had no inhibitory effect. Fexo reduced MDSC counts and suppressed IL6-STAT3 signaling in PCa of HFD-fed mice. In vitro, both histamine and Fexo did not affect the proliferation of DU145. HFD altered the composition of gut microbiota, and Shannon index suggesting diversity of gut microbiota was reduced in HFD-fed mice. Serum lipopolysaccharide (LPS) levels were elevated in 11-week-old HFD-fed mice, and LPS injection resulted in upregulation of Hdc in PCa. Conclusions We found that HFD caused gut microbiota dysbiosis and elevated systemic LPS level, which could promote inflammatory PCa progression through mast cells and histamine H1 receptor signaling. These results suggest the existence of “Gut-Prostate Axis.” Citation Format: Kazutoshi Fujita, Makoto Matsushita, Daisuke Motooka, Takuaki Hase, Eri Banno, Marco De Velasco, Taigo Kato, Atsunari Kawashima, Motohide Uemura, Shota Nakamura, Kazutake Tsujikawa, Eiichi Morii, Kazuhiro Yoshimura, Hirotsugu Uemura. High-fat diet-induced gut dysbiosis promotes prostate cancer growth through mast cells and histamine 1 receptor [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 6156.