Human Prostate Tumor Research Articles

Sialylated glycoproteins suppress immune cell killing by binding to Siglec-7 and Siglec-9 in prostate cancer.

Prostate cancer is the second leading cause of male cancer death in the U.S. Current immune checkpoint inhibitor-based immunotherapies have improved survival for many malignancies; however, they have failed to prolong survival for prostate cancer. Siglecs (sialic acid-binding immunoglobulin-like lectins) are expressed on immune cells and regulate immune responses and function. Siglec-7 and Siglec-9 contribute to immune evasion by interacting with their ligands. However, the role of Siglec-7/9 receptors and their ligands in prostate cancer remains poorly understood. Here, we find that Siglec-7 and Siglec-9 are associated with poor prognosis in prostate cancer patients, and are highly expressed in myeloid cells, including macrophages, in prostate tumor tissues. Siglecs-7 and -9 ligands were expressed in prostate cancer cells and human prostate tumor tissues. Blocking the interactions between Siglec-7/9 and sialic acids inhibited prostate cancer xenograft growth and increased immune cell infiltration in humanized mice in vivo. Using a CRISPRi screen and mass spectrometry, we identified CD59 as a candidate Siglec-9 ligand in prostate cancer. The identification of Siglecs-7 and -9 as potential therapeutic targets, including CD59/Siglec-9 axis, opens up opportunities for immune-based interventions in prostate cancer.

Human intermediate prostate cancer stem cells contribute to the initiation and development of prostate adenocarcinoma

BackgroundIntermediate cells are present in the early stages of human prostate development and adenocarcinoma. While primary cells isolated from benign human prostate tissues or tumors exhibit an intermediate phenotype in vitro, they cannot form tumors in vivo unless genetically modified. It is unclear about the stem cell properties and tumorigenicity of intermediate cells.MethodsWe developed a customized medium to culture primary human intermediate prostate cells, which were transplanted into male immunodeficient NCG mice to examine tumorigenicity in vivo. We treated the cells with different concentrations of dihydrotestosterone (DHT) and enzalutamide in vitro and surgically castrated the mice after cell transplantation in vivo. Immunostaining, qRT-PCR, RNA sequencing, and western blotting were performed to characterize the cells in tissues and 2D and 3D cultures.ResultsWe found intermediate cells expressing AR+PSA+CK8+CK5+ in the luminal compartment of human prostate adenocarcinoma by immunostaining. We cultured the primary intermediate cells in vitro, which expressed luminal (AR+PSA+CK8+CK18+), basal (CK5+P63+), intermediate (IVL+), and stem cell (CK4+CK13+PSCA+SOX2+) markers. These cells resisted castration in vitro by upregulating the expression of AR, PSA, and proliferation markers KI67 and PCNA. The intermediate cells had high tumorigenicity in vivo, forming tumors in immunodeficient NCG mice in a month without any genetic modification or co-transplantation with embryonic urogenital sinus mesenchyme (UGSM) cells. We named these cells human castration-resistant intermediate prostate cancer stem cells or CriPCSCs and defined the xenograft model as patient primary cell-derived xenograft (PrDX). Human CriPCSCs resisted castration in vitro and in vivo by upregulating AR expression. Furthermore, human CriPCSCs differentiated into amplifying adenocarcinoma cells of luminal phenotype in PrDX tumors in vivo, which can dedifferentiate into CriPCSCs in vitro.ConclusionsOur study identified and established methods for culturing human CriPCSCs, which had high tumorigenicity in vivo without any genetic modification or UGSM co-transplantation. Human CriPCSCs differentiated into amplifying adenocarcinoma cells of luminal phenotype in the fast-growing tumors in vivo, which hold the potential to dedifferentiate into intermediate stem cells. These cells resisted castration by upregulating AR expression. The human CriPCSC and PrDX methods hold significant potential for advancing prostate cancer research and precision medicine.

Targeting a STING agonist to perivascular macrophages in prostate tumors delays resistance to androgen deprivation therapy

BackgroundAndrogen deprivation therapy (ADT) is a front-line treatment for prostate cancer. In some men, their tumors can become refractory leading to the development of castration-resistant prostate cancer (CRPC). This causes...

Effect of Jardiance on glucose uptake into astrocytomas

PurposeSGLT2, the sodium glucose cotransporter two, is expressed in human pancreatic, prostate and brain tumors, and in a mouse cancer model SGLT2 inhibitors reduce tumor glucose uptake and growth. In this study we have measured the effect of a specific SGLT2 inhibitor, Jardiance® (Empagliflozin), on glucose uptake into astrocytomas in patients.MethodsWe have used a specific SGLT glucose tracer, α-methyl-4-[18F]fluoro-4-deoxy-α-D-glucopyranoside (Me4FDG), and Positron Emission Tomography (PET) to measure glucose uptake. Four of five patients enrolled had WHO grade IV glioblastomas, and one had a low grade WHO Grade II astrocytoma. Two dynamic brain PET scans were conducted on each patient, one before and one after treatment with a single oral dose of Jardiance, a specific SGLT2 inhibitor. As a control, we also determined the effect of oral Jardiance on renal SGLT2 activity.ResultsIn all five patients an oral dose (25 or 100 mg) of Jardiance reduced Me4FDG tumor accumulation, highly significant inhibition in four, and inhibited SGLT2 activity in the kidney.ConclusionsThese initial experiments show that SGLT2 is a functional glucose transporter in astocytomas, and Jardiance inhibited glucose uptake, a drug approved by the FDA to treat type 2 diabetes mellitus (T2DM), heart failure, and renal failure. We suggest that clinical trials be initiated to determine whether Jardiance reduces astrocytoma growth in patients.

Single-cell analysis of treatment-resistant prostate cancer: Implications of cell state changes for cell surface antigen–targeted therapies

Targeting cell surface molecules using radioligand and antibody-based therapies has yielded considerable success across cancers. However, it remains unclear how the expression of putative lineage markers, particularly cell surface molecules, varies in the process of lineage plasticity, wherein tumor cells alter their identity and acquire new oncogenic properties. A notable example of lineage plasticity is the transformation of prostate adenocarcinoma (PRAD) to neuroendocrine prostate cancer (NEPC)-a growing resistance mechanism that results in the loss of responsiveness to androgen blockade and portends dismal patient survival. To understand how lineage markers vary across the evolution of lineage plasticity in prostate cancer, we applied single-cell analyses to 21 human prostate tumor biopsies and two genetically engineered mouse models, together with tissue microarray analysis on 131 tumor samples. Not only did we observe a higher degree of phenotypic heterogeneity in castrate-resistant PRAD and NEPC than previously anticipated but also found that the expression of molecules targeted therapeutically, namely PSMA, STEAP1, STEAP2, TROP2, CEACAM5, and DLL3, varied within a subset of gene-regulatory networks (GRNs). We also noted that NEPC and small cell lung cancer subtypes shared a set of GRNs, indicative of conserved biologic pathways that may be exploited therapeutically across tumor types. While this extreme level of transcriptional heterogeneity, particularly in cell surface marker expression, may mitigate the durability of clinical responses to current and future antigen-directed therapies, its delineation may yield signatures for patient selection in clinical trials, potentially across distinct cancer types.

Targeting S6K/NFκB/SQSTM1/Polθ signaling to suppress radiation resistance in prostate cancer

In this study we have identified POLθ-S6K-p62 as a novel druggable regulator of radiation response in prostate cancer. Despite significant advances in delivery, radiotherapy continues to negatively affect treatment outcomes and quality of life due to resistance and late toxic effects to the surrounding normal tissues such as bladder and rectum. It is essential to develop new and effective strategies to achieve better control of tumor. We found that ribosomal protein S6K (RPS6KB1) is elevated in human prostate tumors, and contributes to resistance to radiation. As a downstream effector of mTOR signaling, S6K is known to be involved in growth regulation. However, the impact of S6K signaling on radiation response has not been fully explored. Here we show that loss of S6K led to formation of smaller tumors with less metastatic ability in mice. Mechanistically we found that S6K depletion reduced NFκB and SQSTM1 (p62) reporter activity and DNA polymerase θ (POLθ) that is involved in alternate end-joining repair. We further show that the natural compound berberine interacts with S6K in a in a hitherto unreported novel mode and that pharmacological inhibition of S6K with berberine reduces Polθ and downregulates p62 transcriptional activity via NFκB. Loss of S6K or pre-treatment with berberine improved response to radiation in prostate cancer cells and prevented radiation-mediated resurgence of PSA in animals implanted with prostate cancer cells. Notably, silencing POLQ in S6K overexpressing cells enhanced response to radiation suggesting S6K sensitizes prostate cancer cells to radiation via POLQ. Additionally, inhibition of autophagy with CQ potentiated growth inhibition induced by berberine plus radiation. These observations suggest that pharmacological inhibition of S6K with berberine not only downregulates NFκB/p62 signaling to disrupt autophagic flux but also decreases Polθ. Therefore, combination treatment with radiation and berberine inhibits autophagy and alternate end-joining DNA repair, two processes associated with radioresistance leading to increased radiation sensitivity.

BATF-dependent Th17 cells act through the IL-23R pathway to promote prostate adenocarcinoma initiation and progression.

The role of Th17 cells in prostate cancer is not fully understood. The transcription factor BATF controls the differentiation of Th17 cells. Mice deficient in Batf do not produce Th17 cells. In this study, we aimed to characterize the role of Batf-dependent Th17 cells in prostate cancer by crossbreeding Batf knockout mice with mice conditionally mutant for Pten. We found that Batf knockout mice had changes in the morphology of prostate epithelial cells compared with normal mice, and Batf knockout mice deficient in Pten (called Batf-) had smaller prostate size and developed fewer invasive prostate adenocarcinomas than Pten-deficient mice with Batf expression (called Batf+). The prostate tumors in Batf- mice showed reduced proliferation, increased apoptosis, decreased angiogenesis and inflammatory cell infiltration, and activation of nuclear factor-κB signaling. Moreover, Batf- mice showed significantly reduced interleukin 23 (IL-23)-IL-23R signaling. In the prostate stroma of Batf- mice, IL-23R-positive cells were decreased considerably compared with Batf+ mice. Splenocytes and prostate tissues from Batf- mice cultured under Th17 differentiation conditions expressed reduced IL-23/IL-23R than cultured cells from Batf+ mice. Anti-IL-23p19 antibody treatment of Pten-deficient mice reduced prostate tumors and angiogenesis compared with control immunoglobulin G-treated mice. In human prostate tumors, BATF messenger RNA level was positively correlated with IL-23A and IL-23R but not RORC. Our novel findings underscore the crucial role of IL-23-IL-23R signaling in mediating the function of Batf-dependent Th17 cells, thereby promoting prostate cancer initiation and progression. This finding highlights the BATF-IL-23R axis as a promising target for the development of innovative strategies for prostate cancer prevention and treatment.

Sensitivity of magnetic resonance elastography to extracellular matrix and cell motility in human prostate cancer cell line-derived xenograft models

Prostate cancer (PCa) is a significant health problem in the male population of the Western world. Magnetic resonance elastography (MRE), an emerging medical imaging technique sensitive to mechanical properties of biological tissues, detects PCa based on abnormally high stiffness and viscosity values. Yet, the origin of these changes in tissue properties and how they correlate with histopathological markers and tumor aggressiveness are largely unknown, hindering the use of tumor biomechanical properties for establishing a noninvasive PCa staging system.To infer the contributions of extracellular matrix (ECM) components and cell motility, we investigated fresh tissue specimens from two PCa xenograft mouse models, PC3 and LNCaP, using magnetic resonance elastography (MRE), diffusion-weighted imaging (DWI), quantitative histology, and nuclear shape analysis. Increased tumor stiffness and impaired water diffusion were observed to be associated with collagen and elastin accumulation and decreased cell motility. Overall, LNCaP, while more representative of clinical PCa than PC3, accumulated fewer ECM components, induced less restriction of water diffusion, and exhibited increased cell motility, resulting in overall softer and less viscous properties. Taken together, our results suggest that prostate tumor stiffness increases with ECM accumulation and cell adhesion - characteristics that influence critical biological processes of cancer development.MRE paired with DWI provides a powerful set of imaging markers that can potentially predict prostate tumor development from benign masses to aggressive malignancies in patients. Statement of significanceXenograft models of human prostate tumor cell lines, allowing correlation of microstructure-sensitive biophysical imaging parameters with quantitative histological methods, can be investigated to identify hallmarks of cancer.

Abstract 7418: LongFuse: Detecting gene fusion transcripts from high throughput long-read single cell RNA sequencing data

Abstract Gene fusion resulted from genomic translocation plays important oncogenic roles including but not limited to gene activation and changing protein coding sequences. Historically, fusion gene analysis has been limited to bulk levels resulting in mixed oncogene activation models. Single cell Nanopore RNA sequencing (scNanoRNAseq) has the unique strength in detecting full-length chimeric transcripts in thousands of single cells in parallel. However, robust computational tools for detecting fusion genes in single cells from scNanoRNAseq data are missing. Here, we developed LongFuse, a fast and accurate tool, to detect fusion genes and their splicing isoforms in single cells from scNanoRNAseq data. LongFuse implements an XOR logic gate algorithm to speed up fusion candidate searching and stringent criteria to eliminate false discoveries due to trans-splicing events and randomly ligated chimeras. We applied LongFUSE onto scNanoRNAseq data of both human prostate cancer cell line, VCaP, and tumor tissues with known TMPRSS2-ERG fusion. Our results showed that both cancer cell line and prostate tumors harbored a mixture of fusion positive and fusion negative tumor cells. Gene expression analysis revealed transcriptional differences between fusion positive and negative cells including genes involved in cancer cell proliferation and invasion programs such as ELL2, ZBTB16, IGF1R, ANK3, MYPOP and PLPP1 genes. LongFUSE also calculates the splicing isoforms of fusion gene transcripts, allowing prediction of protein sequences of fusion gene transcripts. Taken together, our data demonstrated that LongFUSE is a robust computational tool for detecting gene fusions and their splicing isoforms at single cell level from scNanoRNAseq data. Citation Format: Cheng-Kai Shiau, Yueying He, Hsiao-Yun Lin, Lina Lu, Xiao-Dong Lu, Jindan Yu, Ruli Gao. LongFuse: Detecting gene fusion transcripts from high throughput long-read single cell RNA sequencing data [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 7418.

Targeting prostate tumor low-molecular weight tyrosine phosphatase for oxidation-sensitizing therapy.

Protein tyrosine phosphatases (PTPs) play major roles in cancer and are emerging as therapeutic targets. Recent reports suggest low-molecular weight PTP (LMPTP)-encoded by the ACP1 gene-is overexpressed in prostate tumors. We found ACP1 up-regulated in human prostate tumors and ACP1 expression inversely correlated with overall survival. Using CRISPR-Cas9-generated LMPTP knockout C4-2B and MyC-CaP cells, we identified LMPTP as a critical promoter of prostate cancer (PCa) growth and bone metastasis. Through metabolomics, we found that LMPTP promotes PCa cell glutathione synthesis by dephosphorylating glutathione synthetase on inhibitory Tyr270. PCa cells lacking LMPTP showed reduced glutathione, enhanced activation of eukaryotic initiation factor 2-mediated stress response, and enhanced reactive oxygen species after exposure to taxane drugs. LMPTP inhibition slowed primary and bone metastatic prostate tumor growth in mice. These findings reveal a role for LMPTP as a critical promoter of PCa growth and metastasis and validate LMPTP inhibition as a therapeutic strategy for treating PCa through sensitization to oxidative stress.

Cationic solid lipid nanoparticles (SLN) complexed with plasmid DNA enhance prostate cancer cells (PC-3) migration

Nanotechnology applications in biomedicine have increased in recent decades, primarily as therapeutic agents, drugs, and gene delivery systems. Among the nanoparticles used in medicine, we highlight cationic solid lipid nanoparticles (SLN). Given their nontoxic properties, much research has focused on the beneficial effects of SLN for drug or gene delivery system. However, little attention has been paid to the adverse impacts of SLN on the cellular environment, particularly their influence on intracellular signaling pathways. In this work, we investigate the effects triggered by cationic SLN on human prostate non-tumor cells (PNT1A) and tumor cells (PC-3). Our results demonstrate that cationic SLN enhances the migration of PC-3 prostate cancer cells but not PNT1A non-tumor prostate cells, an unexpected and unprecedented development. Furthermore, we observed that the enhanced cell migration velocity is a concentration-dependent and nanoparticle-dependent effect, and not related to any individual nanoparticle component. Moreover, cationic SLN increased vimentin expression (p < 0.05) but SLN did not affect Smad2 nuclear translocation. Meanwhile, EMT-related (epithelial-to-mesenchymal transition) proteins, such as ZEB1, underwent nuclear translocation when treated with cationic SLN, thereby affecting PC-3 cell motility through ZEB1 and vimentin modulation. From a therapeutic perspective, cationic SLN could potentially worsen a patient’s condition if these results were reproduced in vivo. Understanding the in vitro molecular mechanisms triggered by nanomaterials and their implications for cell function is crucial for defining their safe and effective use.

Discovery of a Dual Tubulin and Neuropilin-1 (NRP1) Inhibitor with Potent In Vivo Anti-Tumor Activity via Pharmacophore-based Docking Screening, Structure Optimization, and Biological Evaluation.

Dual inhibition of tubulin and neuropilin-1 (NRP1) may become an effective method for cancer treatment by simultaneously killing tumor cells and inhibiting tumor angiogenesis. Herein, we identified dual tubulin/NRP1-targeting inhibitor TN-2, which exhibited good inhibitory activity against both tubulin polymerization (IC50 = 0.71 ± 0.03 μM) and NRP1 (IC50 = 0.85 ± 0.04 μM). Importantly, it significantly inhibited the viability of several human prostate tumor cell lines. Further mechanism studies indicated that TN-2 could inhibit tubulin polymerization and cause G2/M arrest, thereby inducing cell apoptosis. It could also suppress cell tube formation, migration, and invasion. Moreover, TN-2 showed obvious antitumor effects on the PC-3 cell-derived xenograft model with negligible side effects and good pharmacokinetic profiles. These data demonstrate that TN-2 could be a promising dual-target chemotherapeutic agent for the treatment of prostate cancer.

Natriuretic Peptides in Gastrointestinal Cancer: Biomarkers and Potential Therapeutic Targets.

Gastrointestinal (GI) cancers are an important health problem globally. Natriuretic peptides are hormones that have a crucial role in human physiology. There are a variety of treatments for GI cancer, but conventional therapies have side effects and low efficacy. Studies have demonstrated that natriuretic peptides are therapeutic in different cancer types. Natriuretic peptides are best known for their involvement in regulating blood pressure and blood volume. The anti-tumor effect exerted by natriuretic peptides is via their inhibitory effects on DNA synthesis and by their effects on apoptosis. The anti-proliferative role of natriuretic peptides has been shown in human breast cancer, prostate, colon, pancreatic, lung, ovarian, and other tumors. The roles of natriuretic peptides in these cancers are diverse and not well understood. Therefore, we have reviewed the recent literature on natriuretic peptides in GI cancers as a common malignancy in adults to assess the pathways that NPs are involved in the progression of GI cancers and its effect on the prevention or treatment of GI cancers.

Protein Kinase C Epsilon Overexpression in Prostate Adenocarcinoma is Associated with Oncogenesis

Background: PKCε, an isozyme of serine-threonine kinase, has been implicated in epithelial cancer metastasis and progression. This study investigates the impact of the oncogenic PKCε, overexpressed abnormally in human Prostate tumor samples and cell lines, to understand its efficacy. Methods: The microarray dataset, GSE86257, was processed for normalization. The identification of upregulated and downregulated genes was based on FDR &gt;1 and p &lt;0.05 values. Cytoscape analysis and functional enrichment of significant genes were done. The identified genes were validated on the TCGA dataset and survival analysis was performed by Kaplan-Meier analysis. Results: A total of 1524 DEGs were identified with 728 upregulated genes and 818 downregulated genes. The two significant modules with MCODE score:9.0 and Venn analysis provided cyclin-dependent kinase inhibitor protein (CDK1), Cyclin B1 (CCNB1), Phospholipase C Gamma 1 (PLCG1), Cyclin Dependent Kinase 9 (CDK9), Phosphoinositide-3-Kinase Regulatory Subunit 3 (PIK3R3), H4 Clustered Histone 6 (H4C6), Phospholipase C Gamma 2 (PLCG2) as most interacting genes. TCGA data analysis and Prognostic analysis revealed CCNBI, CDK9, and PLCG1 associated with poor prognosis. Conclusion: PKCε regulates genes that are responsible for cancer progression. Therefore, targeting PKCε in Prostate cancer may serve as an important regulatory effect and may improve the prognosis of the disease.

Cysteine Counting via Isotopic Chemical Labeling for Intact Mass Proteoform Identifications in Tissue.

Top-down proteomics, the tandem mass spectrometric analysis of intact proteoforms, is the dominant method for proteoform characterization in complex mixtures. While this strategy produces detailed molecular information, it also requires extensive instrument time per mass spectrum obtained and thus compromises the depth of proteoform coverage that is accessible on liquid chromatography time scales. Such a top-down analysis is necessary for making original proteoform identifications, but once a proteoform has been confidently identified, the extensive characterization it provides may no longer be required for a subsequent identification of the same proteoform. We present a strategy to identify proteoforms in tissue samples on the basis of the combination of an intact mass determination with a measured count of the number of cysteine residues present in each proteoform. We developed and characterized a cysteine tagging chemistry suitable for the efficient and specific labeling of cysteine residues within intact proteoforms and for providing a count of the cysteine amino acids present. On simple protein mixtures, the tagging chemistry yields greater than 98% labeling of all cysteine residues, with a labeling specificity of greater than 95%. Similar results are observed on more complex samples. In a proof-of-principle study, proteoforms present in a human prostate tumor biopsy were characterized. Observed proteoforms, each characterized by an intact mass and a cysteine count, were grouped into proteoform families (groups of proteoforms originating from the same gene). We observed 2190 unique experimental proteoforms, 703 of which were grouped into 275 proteoform families.

An in situ fluorescent copolymer dots-based kit for the specific detection of monoamine oxidase-A in cell/tissue/human prostate cancer

Currently, the development of simple, fast, low-cost, and environmentally friendly MAO-A specific detection methods remains a huge challenge. Herein, a simple in situ fluorescent copolymer dots (FCDs)-based kit is constructed for the specific detection of monoamine oxidase-A in cell, tissue and human prostate cancer. The developed kit is depended on the high reaction activity between epinephrine and polyethyleneimine to form FCDs and the selective catalyzing activity of MAO-A on epinephrine. The gained FCDs are identified and characterized by high-resolution TEM, absorption and fluorescence spectrum. The present kit achieves highly sensitive detection of MAO-A with a limit of detection (LOD) of 20 ng/mL as well as screening of inhibitor with an IC50 (the concentration responding to 50% inhibition) of 1.071 μM by using clorgyline as a model. The MAO-A and MAO-B as the two isoforms of MAO are discriminated successfully, demonstrating the excellent selectivity of our kit. Noteworthy, the proposed method is applicable for measuring MAO-A not only from serum samples, but also for endogenous MAO-A in cells, mouse tissues and human prostate tumors with satisfied results. The proposed kit will be a great potential tool for human prostate cancer (PCa) diagnosis and the development of anti-PCa drug screening.

FOXP2 confers oncogenic effects in prostate cancer.

Identification oncogenes is fundamental to revealing the molecular basis of cancer. Here, we found that FOXP2 is overexpressed in human prostate cancer cells and prostate tumors, but its expression is absent in normal prostate epithelial cells and low in benign prostatic hyperplasia. FOXP2 is a FOX transcription factor family member and tightly associated with vocal development. To date, little is known regarding the link of FOXP2 to prostate cancer. We observed that high FOXP2 expression and frequent amplification are significantly associated with high Gleason score. Ectopic expression of FOXP2 induces malignant transformation of mouse NIH3T3 fibroblasts and human prostate epithelial cell RWPE-1. Conversely, FOXP2 knockdown suppresses the proliferation of prostate cancer cells. Transgenic overexpression of FOXP2 in the mouse prostate causes prostatic intraepithelial neoplasia. Overexpression of FOXP2 aberrantly activates oncogenic MET signalling and inhibition of MET signalling effectively reverts the FOXP2-induced oncogenic phenotype. CUT&Tag assay identified FOXP2-binding sites located in MET and its associated gene HGF. Additionally, the novel recurrent FOXP2-CPED1 fusion identified in prostate tumors results in high expression of truncated FOXP2, which exhibit a similar capacity for malignant transformation. Together, our data indicate that FOXP2 is involved in tumorigenicity of prostate.

Pre-Clinical Models to Study Human Prostate Cancer.

Prostate cancer is a common cancer among men and typically progresses slowly for several decades before becoming aggressive and spreading to other organs, leaving few treatment options. While large animals have been studied, the dog's prostate is anatomically similar to humans and has been used to study spontaneous prostate cancer. However, most research currently focuses on the mouse as a model organism due to the ability to genetically modify their prostatic tissues for molecular analysis. One milestone in this research was the identification of the prostate-specific promoter Probasin, which allowed for the prostate-specific expression of transgenes. This has led to the generation of mice with aggressive prostatic tumors through overexpression of the SV40 oncogene. The Probasin promoter is also used to drive Cre expression and has allowed researchers to generate prostate-specific loss-of-function studies. Another landmark moment in the process of modeling prostate cancer in mice was the orthoptic delivery of viral particles. This technology allows the selective overexpression of oncogenes from lentivirus or the use of CRISPR to generate complex loss-of-function studies. These genetically modified models are complemented by classical xenografts of human prostate tumor cells in immune-deficient mice. Overall, pre-clinical models have provided a portfolio of model systems to study and address complex mechanisms in prostate cancer for improved treatment options. This review will focus on the advances in each technique.

Sulforaphane Combined with Vitamin D Induces Cytotoxicity Mediated by Oxidative Stress, DNA Damage, Autophagy, and JNK/MAPK Pathway Modulation in Human Prostate Tumor Cells.

Prostate cancer ranks second in incidence worldwide. To date, there are no available therapies to effectively treat advanced and metastatic prostate cancer. Sulforaphane and vitamin D alone are promising anticancer agents in vitro and in vivo, but their low bioavailability has limited their effects in clinical trials. The present study examined whether sulforaphane combined with vitamin D at clinically relevant concentrations improved the cytotoxicity of the compounds alone towards DU145 and PC-3 human prostate tumor cells. To assess the anticancer activity of this combination, we analyzed cell viability (MTT assay), oxidative stress (CM-H2DCFDA), autophagy (fluorescence), DNA damage (comet assay), and protein expression (Western blot). The sulforaphane-vitamin D combination (i) decreased cell viability, induced oxidative stress, DNA damage, and autophagy, upregulated BAX, CASP8, CASP3, JNK, and NRF2 expression, and downregulated BCL2 expression in DU145 cells; and (ii) decreased cell viability, increased autophagy and oxidative stress, upregulated BAX and NRF2 expression, and downregulated JNK, CASP8, and BCL2 expression in PC-3 cells. Therefore, sulforaphane and vitamin D in combination have a potential application in prostate cancer therapy, and act to modulate the JNK/MAPK signaling pathway.

Abstract A023: RNF185 modulates prostate cancer metastatic potential through regulation of epithelial-mesenchymal transition

Abstract RNF185 is a RING finger domain-containing ubiquitin ligase which is anchored to the ER and resemble RNF5, a ubiquitin ligase implicated in ER associated degradation. In prostate cancer, deregulation of the expression or activity of several ubiquitin ligases has been shown to contribute to disease progression (e.g., Siah2, SPOP, RNF6). Analysis of prostate tumor patient data revealed a negative correlation between RNF185 expression and prostate adenocarcinoma progression and metastasis. Supporting these observations, several prostate cancer cell lines exhibited greater migration and invasion capabilities upon RNF185 depletion, in vitro. Subcutaneous inoculation of mouse prostate cancer MPC3 cells, stably expressing shRNA against RNF185, resulted in larger tumors and more frequent lung metastases in NSG mice. These results suggest that the increased metastatic potential associated with lower RNF185 levels may depend on molecular changes intrinsic to the tumors cells. RNA-sequencing and Ingenuity Pathway Analysis of RNF185-depleted compared to control MPC3 cells identified wound healing and cellular movement among the most significantly upregulated pathways in RNF185-depleted cells. Transcription regulators of Epithelial-Mesenchymal Transition (EMT) Snai2 and Zeb1 were among the most upregulated genes that were predicted to be activated based on the expression of their target genes. Comparison between differentially expressed genes in patients with low RNF185 expression, and RNF185-depleted cell lines (from mouse and human prostate tumors) confirmed deregulation of genes implicated in EMT. Taken together, our results identify RNF185 as gatekeeper of prostate cancer metastasis, via its control of EMT genes implicated in cell motility and metastasis. Citation Format: Benjamin Van Espen, Ladan Fazli, Htoo Z. Oo, Rabi Murad, Martin Gleave, Ze'ev A. Ronai. RNF185 modulates prostate cancer metastatic potential through regulation of epithelial-mesenchymal transition [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 A023.