Prostate Tumor Cells Research Articles

Effect of 5β-dihydrotestosterone on vasodilator function and on cell proliferation.

Aging is one of the main factors associated with cardiovascular diseases. Androgens exert beneficial effects on the cardiovascular system and testosterone (TES) replacement therapy improves cardiometabolic risk factors. However, TES is contraindicated in patients with prostate cancer due to its proliferative effects on prostatic tumor cells. Additionally, TES and its reduced metabolites 5α- and 5β-dihydrotestosterone (5α-DHT and 5β-DHT) exert vasodilatory effects. Since androgen levels decrease during aging and 5β-DHT lacks genomic effects, this study is focused on analyzing its effect on vasodilator function and the proliferation rate of prostatic tumor and vascular smooth muscle cells. To study the vascular function, mesenteric arteries from aged-orchidectomized Sprague-Dawley rats were used. Mesenteric segments were divided into one control (without treatment) and three groups with the androgens (10 nM, 30 min) to analyze: acetylcholine- and sodium nitroprusside-induced responses and nitric oxide and superoxide anion production. To analyze cell proliferation, the effect of androgens on cell viability was determined. The results showed that 5β-DHT improves vasodilator function in arteries from aged-orchidectomized rats and induces antioxidant action, while the proliferation rate of the androgen-dependent prostatic tumor cells remains unaltered. These results make 5β-DHT a promising therapeutic agent for the treatment of cardiovascular pathologies.

Dynamic reciprocal interactions between activated T cells and tumor associated macrophages drive macrophage reprogramming and proinflammatory T cell migration within prostate tumor models

Tumor-associated macrophages (TAMs) have been implicated as a tumor microenvironment (TME) cell population, which may be playing a vital role in the inhibition of effective T cell responses in the prostate TME. In this manuscript, we leverage a novel microscale cell culture platform, known as Stacks, to investigate mono-, co-, and tri-culture TME models comprised of prostate tumor cell lines, primary macrophages, and autologous T cells from patients with prostate cancer. Through multiplexed analysis of these multi-cellular prostate tumor models, we capture a dynamic interaction between primary TAMs and activated T cells that resulted in reciprocal proinflammatory activation of both cell populations upon interaction. These findings suggest that activated T cells are capable of reprogramming immunosuppressive TAMs in the context of prostate tumor models and that TAM reprogramming may play a key supportive role in restoring proinflammatory T cell tumor responses in the prostate TME.

MicroRNA-506 as a tumor suppressor in prostate cancer by regulation of Hippo signaling pathway

IntroductionProstate cancer (PCa) is considered as one of the leading causes of cancer related deaths among males globally. There is a high rate of tumor relapse and metastasis in PCa patients that is associated with chemo-resistance. Beside the elimination of tumor cells, chemotherapy has an adverse effect in normal cells. Therefore, it is required to clarify the molecular tumor biology to introduce novel markers to predict the drug response in PCa patients. Hippo signaling pathway is an important regulator of cell proliferation, migration, and drug response that can be modulated by microRNAs (miRNAs). Since, miR-506 deregulation has been reported in PCs, in the present study we assessed a probable role of miR-506 in regulation of Hippo signaling pathway during prostate tumor cell migration and drug resistance. Materials and methodsThe mRNA expression levels of Hippo signaling components were assessed in miR-506 ectopic expressed in comparison with control PC3 cells. Apoptosis assay, drug response, and cell migration were also assessed to find the role of miR-506 in prostate tumor cell aggressiveness. ResultsMiR-506 promoted the Hippo signaling pathway via TAZ and CTGF up regulations, while BIRC5, FAT, and C-MYC down regulations in PC3 cells. MiR-506 significantly reduced prostate tumor cell migration (p = 0.019) and Paclitaxel (TXL) resistance (p = 0.0006), while promoted apoptosis (p < 0.0001). ConclusionmiR-506 exerted a tumor suppressor role during PCa progression by activation of Hippo pathway. MiR-506 targeted the FAT to activate the YAP/TAZ and nuclear translocation where it can bind with TEAD to up regulate the CTGF that resulted in reduced PCa cell migration. The WNT inhibition and C-MYC down regulation by the CTGF resulted in BIRC5 down regulation that induced apoptosis in PCa cells. Therefore, miR-506 can be introduced as a therapeutic marker in PCa following the confirmation by the animal studies and further clinical trials.

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...

Biflavonoids: Preliminary Reports on Their Role in Prostate and Breast Cancer Therapy.

Dimeric flavonoids, also called biflavonoids, are bioactive compounds that exhibit various activities described in the literature, including antibacterial, antifungal, antiviral, anti-inflammatory, analgesic, antioxidant, vasorelaxant, and anticancer properties. This work focuses on the anticancer action of naturally occurring dimeric flavonoids against prostate and breast cancer, as well as on the mechanisms of action involved in their activity and presents the most current information on this subject in the literature. In the present review, we summarize the latest findings on the antiproliferative activity of 33 dimeric flavonoid-based compounds selected from recently published studies. The tests conducted were in silico and in vitro and demonstrated the cytotoxic activity potential of biflavonoids against prostate and breast tumor cells. Biflavonoids were capable of interfering with the migration and replication of cancer cells and their mechanism of action is related to cell death pathways, especially apoptosis, necrosis, and ferroptosis. These compounds decreased mitochondrial membrane potential and significantly increased intracellular levels of reactive oxygen species (ROS). Additionally, they significantly upregulated the expression of p21, Bax, and cleaved caspase-3, while downregulating Bcl-2 and caspase-3 levels, indicating their cell death mechanism of action is through the Bcl-2/Bax/cleaved caspase-3 pathway and cell cycle arrest. The biflavonoids here related have shown promising anticancer activity and are considered potential drug candidates for prostate and breast cancer treatment.

Tumor Growth Inhibition and Induced the Immunogenic Death of Tumor Cells in Prostate Tumor Bone Metastases by Photothermal Therapy Mediated with Au Nanoparticles Modified with PDA

AbstractUpon progression to the metastatic stage, prostate tumors commonly exhibit multi‐drug resistance. Combining multiple treatment protocols can be beneficial in overcoming this resistance, which is often attributed to tumor heterogeneity. Recently, nano‐photosensitizer‐mediated photothermal therapy is shown to inhibit tumor growth through multiple pathways, including thermal ablation and activation of the antitumor immune response. In this study, gold nanoparticles (Au) are selected as the core photosensitizer. Then, the photothermal conversion of Au is augmented through dopamine coating, and the chemotherapy drug doxorubicin (DOX) is grafted to the dopamine coating. The release of DOX from DOX‐loaded dopamine‐modified gold nanoparticles (Au@PDA@DOX) occurred in response to an acidic environment. The combination of chemotherapy and thermal ablation better inhibits the growth, migration, and invasion of tumor cells and induced tumor cell apoptosis and necrosis in vitro. More importantly, thermal ablation induces the immunogenic death of prostate tumor cells (RM‐1) cells. The transition of prostate tumors from a “cold” to a “hot” tumor with immunogenicity is observed. The combination effectively activates the antitumor immune response, inhibits tumor growth, and alleviated bone damage by tumors in vivo. It is indicated that Au@PDA@DOX nanoparticles will offer a novel treatment protocol for prostate tumor bone metastases.

Unveiling the characteristics of D4 and R4 aptamers for their future use in prostate cancer clinical practice

The DNA and RNA aptamers D4 and R4, respectively, emerged from the modification of PC-3 cell-binding aptamer A4. Our objective was to characterize the aptamers in silico and in vitro and begin to identify their target molecules. We represented their structures using computational algorithms; evaluated their binding to several prostate cell lines and their effects on the viability and migration of these cells; and determined their dissociation constant by flow cytometry. We analyzed circulating prostate tumor cells from patients using D4, R4, anti-CD133 and anti-CD44. Finally, the target proteins of both aptamers were precipitated and identified by mass spectrometry to simulate their in silico docking. The aptamers presented similar structures and bound to prostate tumor cells without modifying the cellular parameters studied, but with different affinities. The ligand cells for both aptamers were CD44+, indicating that they could identify cells in the mesenchymal stage of the metastatic process. The possible target proteins NXPE1, ADAM30, and MUC6 need to be further studied to better understand their interaction with the aptamers. These results support the development of new assays to determine the clinical applications of D4 and R4 aptamers in prostate cancer.

Sequence of androgen receptor-targeted vaccination with androgen deprivation therapy affects anti-prostate tumor efficacy

RationaleAndrogen deprivation therapy (ADT) is the primary treatment for recurrent and metastatic prostate cancer. In addition to direct antitumor effects, ADT has immunomodulatory effects such as promoting T-cell infiltration and...

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.

Cytotoxicity, anti-inflammatory effect, and acute oral toxicity of a novel Attalea phalerata kernel oil-loaded nanocapsules

The kernel oil of the Attalea phalerata Mart. Ex Spreng (Acurí) is traditionally used in several Latin American countries to treat respiratory problems, inflammation, and fever. However, it cannot be found on the literature any attend to use this oil in pharmaceutical formulation. In this paper, it was developed Acurí oil-loaded nanocapsules, and it was evaluated the cytotoxicity against cancer cells, the antinflammatory activity and the oral acute toxicity in rats. Acurí oil contains lauric acid as the predominant saturated fatty acid (433.26 mg/g) and oleic acid as the main unsaturated fatty acid (180.06 mg/g). The Acurí oil-loaded nanocapsules showed a size of 237 nm, a polydispersity index of 0.260, and a high ζ-potential of −78.75 mV. It was obtained an encapsulation efficiency of 88.77%, and the nanocapsules remain stable on the shelf for 180 days. The nanocapsules showed a rapid release profile (98.25% in 40 minutes). Nanocapsules at a dose of 10 mg/kg exhibit an anti-inflammatory effect similar to indomethacin at the same dose. The nanocapsules showed excellent antiproliferative effect and selectivity index against prostate tumor cells (IC50 2.09 µg/mL, SI=119.61) and kidney tumor cells (IC50 3.03 µg/mL, SI=82.50). Both Acurí oil and Acurí oil-loaded nanocapsules are nontoxic at a dose of 2000 mg/kg. Additionally, they reduce serum triglyceride and total cholesterol levels in rat and could find application in nutraceutical formulations. The Acurí oil-loaded nanocapsules emerge as a promising candidate for new antitumor therapies.

Regulation of Molecular Biomarkers Associated with the Progression of Prostate Cancer.

Androgen receptor signaling regulates the normal and pathological growth of the prostate. In particular, the growth and survival of prostate cancer cells is initially dependent on androgen receptor signaling. Exposure to androgen deprivation therapy leads to the development of castration-resistant prostate cancer. There is a multitude of molecular and cellular changes that occur in prostate tumor cells, including the expression of neuroendocrine features and various biomarkers, which promotes the switch of cancer cells to androgen-independent growth. These biomarkers include transcription factors (TP53, REST, BRN2, INSM1, c-Myc), signaling molecules (PTEN, Aurora kinases, retinoblastoma tumor suppressor, calcium-binding proteins), and receptors (glucocorticoid, androgen receptor-variant 7), among others. It is believed that genetic modifications, therapeutic treatments, and changes in the tumor microenvironment are contributing factors to the progression of prostate cancers with significant heterogeneity in their phenotypic characteristics. However, it is not well understood how these phenotypic characteristics and molecular modifications arise under specific treatment conditions. In this work, we summarize some of the most important molecular changes associated with the progression of prostate cancers and we describe some of the factors involved in these cellular processes.

Abstract LB217: Novel organoid models of lineage plasticity in castration resistant prostate cancer

Abstract The development of next-generation AR-targeted drugs, such as abiraterone and enzalutamide, has improved survival of patients with castration-resistant prostate cancer (CRPC). However, many patients eventually progress to therapy-resistant lethal prostate cancer. CRPC exhibits variant cellular states, including AR-pathway active prostate cancer (ARPC), AR activity-low prostate cancer (ARLPC), neuroendocrine prostate cancer (NEPC), amphicrine prostate cancer co-expressing AR and neuroendocrine genes (AMPC), and double-negative prostate cancer (DNPC) lacking both AR expression and neuroendocrine differentiation, indicating that lineage plasticity facilitates therapeutic resistance. While molecular characteristics of ARPC and NEPC are well described, other common forms of CRPC, such as DNPC which occurs in 20-25% of CRPC patients, remain poorly understood. Therefore, characterization of pre-clinical models of DNPC and identification of novel regulators of lineage plasticity in DNPC are urgent necessities for the development of effective treatment for lethal prostate cancer.In our studies, we have generated a new mouse model of CRPC in which Pten and Smad4 are deleted in distal luminal cells upon tamoxifen administration (Nkx3.1CreERT2/+; Ptenfl/fl; Smad4fl/fl; R26R-eYFP/+, NPS). We observed a molecular transition from ARPC to ARLPC and DNPC in the prostate tumors derived from NPS mice during tumor progression. Moreover, a combination of castration and enzalutamide treatment promoted a partial epithelial-mesenchymal transition (EMT) in DNPC. To identify the evolutionary trajectories of cancer progression and drivers of lineage plasticity in CRPC, we have established organoid lines from the prostate tumor cells of NPS mice. Single-cell RNA-sequencing (scRNA-seq) and marker validation analyses shown that these organoid lines display overt lineage plasticity, corresponding to ARPC, ARLPC, partial EMT-absent DNPC, and partial EMT-present DNPC. Orthotopic grafts derived from the established NPS organoid lines show consistent molecular phenotypes and confirm that AR-targeted therapies facilitate partial EMT in vivo. Furthermore, cross-species bioinformatic analyses using scRNA-seq datasets indicate that the established NPS organoid lines partially recapitulate the spectrum of lineage plasticity in human CRPC.In summary, we have established prostate cancer organoid lines from a novel mouse model of CRPC, which not only provide large and reproducible sources of two distinct forms of DNPC (partial EMT-absent DNPC and partial EMT-present DNPC) for molecular analyses, but also can capture the regulatory complexity of lineage plasticity in human CRPC. Therefore, NPS mice provide an excellent pre-clinical model of CRPC, especially DNPC, to identify novel regulators that drive lineage plasticity and to pursue assays for development of candidate drugs that can inhibit or even possibly convert therapy-resistant forms of CRPC to therapy-sensitive ones. Citation Format: Jinqiu Lu, Michael M. Shen. Novel organoid models of lineage plasticity in castration resistant prostate cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 2 (Late-Breaking, Clinical Trial, and Invited Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(7_Suppl):Abstract nr LB217.

The design, synthesis and bioactivity evaluation of novel androgen receptor degraders based on hydrophobic tagging

Prostate Cancer (PCa) easily progress to metastatic Castration-Resistant Prostate Cancer (mCRPC) that remains a significant cause of cancer-related death. Androgen receptor (AR)-dependent transcription is a major driver of prostate tumor cell proliferation. Proteolysis-targeting chimaera (PROTAC) technology based on Hydrophobic Tagging (HyT) represents an intriguing strategy to regulate the function of therapeutically androgen receptor proteins. In the present study, we have designed, synthesized, and evaluated a series of PROTAC-HyT AR degraders using AR antagonists, RU59063, which were connected with adamantane-based hydrophobic moieties by different alkyl chains. Compound D-4–6 exhibited significant AR protein degradation activity, with a degradation rate of 57 % at 5 μM and nearly 90 % at 20 μM in 24 h, and inhibited the proliferation of LNCaP cells significantly with an IC50 value of 4.77 ± 0.26 μM in a time-concentration-dependent manner. In conclusion, the present study lays the foundation for the development of a completely new class of therapeutic agents for the treatment of mCRPC, and further design and synthesis of AR-targeting degraders are currently in progress for better degradation rate.

Abstract 6348: Unveiling diverse trimeric forms of STEAP1 in human prostate cancer cells: Exploring STEAP1-STEAP2 interdependence for expression and plasma membrane localization

Abstract Six-Transmembrane Epithelial Antigen of the Prostate 1 (STEAP1) is an emerging therapeutic target that is a member of the STEAP1-4 family of metalloreductases. We recently reported the preclinical characterization of xaluritamig (AMG 509), a STEAP1 XmAb® 2+1 T-cell engager molecule that is being developed for the treatment of prostate cancer (Nolan-Stevaux et al, 2023). Xaluritamig is designed to preferentially target tumor cells that express high levels of STEAP1. However, prostate tumor cells also express high levels of STEAP2. Here, we characterize the interactions between STEAP1 and STEAP2 in prostate cancer cell lines and the impact to xaluritamig activity. Bulk mRNA as well as single-cell gene expression data (scRNAseq) reveal a strong correlation between STEAP1 and STEAP2 expression in human prostate cancer, suggesting that the STEAP proteins may form both homotrimers and heterotrimers in prostate tumors. To test this idea, we investigated the structural behavior of STEAP1/2 trimers in human prostate cancer cell lines that endogenously express STEAP1 and STEAP2. Using xaluritamig and the parental anti-STEAP1 antibody, we show that STEAP1 primarily forms heterotrimers with STEAP2 in prostate cancer cells but can also assemble as homotrimers in the absence of STEAP2. Both STEAP1/2 heterotrimers and STEAP1 homotrimers can be targeted by xaluritamig, leading to T cell-dependent cellular cytotoxicity. Similarly, we found that anti-STEAP2 antibodies detected STEAP2 homotrimers when STEAP1 expression was ablated in cells, and that both STEAP1/2 heterotrimers and STEAP2 homotrimers were targeted by a STEAP2-specific T-cell engager molecule. We also demonstrate that neither STEAP1 nor STEAP2 significantly influences the mRNA or protein expression of the other. Our data elucidates the versatility of STEAP family members in forming both homotrimers and heterotrimers on the plasma membrane of human prostate cancer cells and the potential for therapeutic targeting with STEAP1/2-directed therapies. Characterizing the capability of existing STEAP1 or STEAP2 targeting therapeutics to bind their respective targets, whether within a homotrimer or heterotrimer, is crucial for a comprehensive understanding of the therapeutic potential of these drugs. Further research will help delineate the mechanism underlying the formation of STEAP1/2 trimers in cancer cells and continue advancing our understanding of this intriguing biological relationship. Citation Format: Cong Li, Lingming Liang, Joonhee Park, Olga Pryshchep, Binnaz Staley, Peng Li, Ben Alba, Xuan Liu, Fei Li, Gregory L. Moore, Matthew J. Bernett, Umesh Muchhal, John Desjarlais, Angela Coxon, Julie M. Bailis. Unveiling diverse trimeric forms of STEAP1 in human prostate cancer cells: Exploring STEAP1-STEAP2 interdependence for expression and plasma membrane localization [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 6348.

Abstract 6356: Novel antibody targeting tumor NKG2D ligand MIC: Preclinical studies and clinical development plan for mCRPC

Abstract In response to genomic insults and DNA double-strand breaks, the stressed epithelial cells express the MHC I-chain related molecule (MIC) on the surface as a byproduct of activating the ATM pathway. The MIC molecule itself has no known impact on tumor survival or growth. In the context of immune microenvironment, tumor cell surface MIC can activate NK cells and co-stimulate CD8 T cells by engaging in the activating receptor NKG2D to hinder the early tumorigenesis. However, in established malignancies, in particular metastatic diseases, tumor cells shed surface MIC to release the soluble form MIC (sMIC). It has been well demonstrated that, in contrary to cell surface MIC, sMIC is highly immune suppressive by disturbing NK cell homeostasis and repolarizing NK cells function, impairing antigen-specific CD8 T cell function by downmodulating NKG2D expression and CD3z expression, and facilitating immune suppression of MDSCs and TAMs in tumor microenvironment. We have demonstrated that MIC is prevalently expressed by prostate tumor cells and significantly upregulated in mCRPC tumors. We have shown significantly elevated levels of serum sMIC in prostate cancer patients with metastatic diseases. We have developed a novel class of clinical candidate monoclonal antibody huB10G5 that can target both sMIC and surface MIC to re-invigorate both NK and CD8 T cell function and inhibit MDSCs and TAMs in preclinical models. The huB10G5 has an acceptable safety profile and is currently completing CMC for IND enabling. We hypothesize that huB10G5 is a novel immune therapeutic reagent for mCRPC patients. To test our hypothesis, we first conducted serial studies of the clinical candidate huB10G5 in pre-clinical models of prostate cancers. We found that huB10G5 can effectively induce 100% long-term tumor complete regression (CR) as low as 1.0 mg/KG. These animals are fully protected from tumor re-challenge. The anti-tumor effect is mediated by the combined action of NK and CD8 T cells. With the support of our pre-clinical efficacy and safety data, we have planned to initiate Phase I clinical trial with huB10G5 for mCRPC patients in 2024. Citation Format: Jennifer Donglan Wu, Jeff Sosman, Masha Kocherginsky, Anthony Serritella, Maha Hussian, David J. Vanderweele. Novel antibody targeting tumor NKG2D ligand MIC: Preclinical studies and clinical development plan for mCRPC [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 6356.

Abstract 5821: DXC008, a novel STEAP1 antibody-tubulysin analog conjugate with a function linker, demonstrates a potential to broaden therapeutic opportunities for prostate tumors

Abstract Six-transmembrane epithelial antigen of the prostate 1 (STEAP1), is a cell surface protein frequently expressed in prostate cancer, with limited expression in non-prostate tissues. A Steap1 antibody called Vandortuzumab conjugated with MMAE (DSTP3086S) was in the clinical phase I trial for treating STEAP1-expressing metastatic castration-resistant prostate cancer and showed acceptable safety at 2.4 mg/kg once every 3 weeks. However, many patients are nonresponsive to DSTP3086S due to low target expression levels and common treatment-related AEs which were caused by MMAE payloads. DXC008 was generated through screening the therapeutical index in vitro of conjugates of an anti-Steap1 antibody with varieties of payloads of tubulysin B analogs through function peptide spacer linkers. The generated DXC008 exhibited not only good affinity for Steap1 but also moderate affinity for Prostate-specific membrane antigen (PSMA) which is as well specifically overexpressed in most prostate cancer with limited expression in normal tissue. DXC008 demonstrated couple tens to a hundred of picomolar concentration (pM) of potency against several prostate tumor cells and over 60% internalization rate within 90 min in vitro. And in vivo it showed very good durable antitumor response as low dose as 1 mg/kg one injection in both high and moderate of both Steap1 and PSMA expression xenograft models. Pharmacokinetic profiles of DXC008 were favorable and the safety of Maximal Tolerable Dose (MTD) was over 120 mg/kg in single injection in mice. DXC008 has been forward to NHP toxicity study and it has potential to be a good STEAP1/PSMA-targeting ADC with a wide therapeutic window for prostate cancers. Citation Format: Qingliang Yang, Yuanyuan Huang, Junxiang Jia, Huihui Guo, Lingli Zhang, You Zhou, Zhicang Ye, Hangbo Ye, Yifang Xu, WenJun Li, Zhiyu Zhao, Lingyao Zhao, Lu Bai, Jun Zheng, Robert Y. Zhao. DXC008, a novel STEAP1 antibody-tubulysin analog conjugate with a function linker, demonstrates a potential to broaden therapeutic opportunities for prostate tumors [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 5821.

Abstract 371: Hypoxia-induced centrosome loss as a driver of chromosomal instability in prostate cancer

Abstract PURPOSE: This study aims to identify a causal mechanism of centrosome loss previously observed in primary prostate cancer. Prostate cancer progression is accompanied by bursts of chromosomal instability (CIN), including chromosomal translocations, oncogene amplifications, and chromothripsis. While high CIN correlates with most metrics of aggressive disease, we lack a mechanistic understanding of how CIN originates in prostate cancer. Recently, we discovered that cells in primary prostate tumors lack centrosomes, cytoplasmic organelles that ensure the fidelity of chromosome segregation by organizing the shape of the mitotic spindle. Experimental elimination of centrosomes in immortalized, non-tumorigenic prostate cell lines was sufficient to generate extensive CIN, resulting in oncogenic transformation of these lines when sub-cutaneously injected into NSG mice. Because we identified centrosome loss as a potential driver of CIN, we sought to understand mechanisms that can trigger centrosome loss in the prostate. Although centrosome loss naturally occurs during the development of some tissues, for example centrosome elimination during oogenesis, the mechanisms that trigger loss are not known. Therefore, we first investigated microenvironmental changes in early prostate cancer as a potential cause. Hypoxia, pathologically low oxygen concentration, is common in the aging prostate due to loss of vasculature and is associated with poor prostate cancer prognosis and high CIN. Therefore, we hypothesized that hypoxic exposure induces centrosome loss in prostate cells. Indeed, we found that exposure to 1% oxygen concentrations leads to progressive centrosome loss in non-tumorigenic, immortalized prostate epithelial cell lines. Using immunofluorescence of centrosomes in cultured cells, we found that hypoxia-induced centrosome loss is independent of HIF transcription but requires activation of the confluence-dependent Hippo signaling pathway. Mechanistically, we found that centrosome disassembly begins with the removal of the pericentriolar material (PCM), the outer shell of the centrosome that nucleates microtubules. We were able to block centrosome disassembly by over-expressing a constitutively-active mutant of Polo-like Kinase 1, which normally strengthens the PCM during mitosis to promote centrosome maturation. Furthermore, centrosome loss was prevented by treatment with the Protein Phosphatase 2A (PP2A) inhibitor Okadaic Acid. Using RNAseq, we have identified potential PP2A regulatory subunits that are up-regulated in cells undergoing hypoxia-induced centrosome loss. Our model is that hypoxia induces dephosphorylation of the PCM, mechanically weakening the centrosome and leaving it vulnerable to disassembly. Together with previous findings, we conclude that hypoxia-induced centrosome disassembly is a plausible driver of CIN in early prostate cancer. Citation Format: John M. Ryniawec, Gregory C. Rogers, Anne E. Cress. Hypoxia-induced centrosome loss as a driver of chromosomal instability in prostate cancer [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 371.

Abstract 6816: Prevention of cancer cachexia by inhibition of soluble epoxide hydrolase

Abstract Background: Cancer cachexia is a devastating syndrome characterized by progressive muscle wasting and hyperinflammation. The underlying mechanisms remain poorly understood with no treatment options available. Cachexia is driven by systemic inflammation, pro-inflammatory cytokines, and apoptotic cell death (debris). The resolution of inflammation as an active biochemical process is regulated by novel pro-resolving lipid mediators. Arachidonic acid-derived epoxyeicosatrienoic acids (EETs) are lipid mediators stimulating inflammation resolution. EETs are rapidly metabolized by the enzyme soluble epoxide hydrolase (sEH). sEH is a critical cause of inflammation and a biomarker in several chronic inflammatory diseases. sEH inhibitors promote tissue regeneration and counter-regulate pro-inflammatory cytokines. We hypothesized that pharmacological inhibition of the sEH may prevent cachexia. Methods: We investigated murine cancer cachexia models using genetically engineered pancreatic (KPC) and prostate (TRAMP C1) tumor cell lines, and “TRAMP” mice (transgenic adenocarcinoma of the mouse prostate). We performed LC-MS/MS-based profiling of bioactive lipids in plasma from KPC and colon cancer (CT26)-induced cachectic mice. Results: KPC cells injected intraperitoneally induced 19.7% and 54.1% reduction in muscle weight in the tibialis anterior and soleus, respectively, in immunocompetent C57BL/6 mice compared to non-tumor bearing (NTB) mice. LC-MS/MS revealed KPC and CT26 cachexia induced a pro-inflammatory eicosanoid-driven cytokine storm. The human sEH inhibitor EC5026 delayed the onset of cachexia, leading to sustained survival over 250 days post-injection in the KPC model (n=15 mice/group). sEH expression was increased in the gastrocnemius of KPC mice by day 22 post-tumor cell injection vs. NTB. EC5026 counter-regulated sEH expression compared to vehicle-treated. In the TRAMP model, 5/5 of mice treated with EC5026 survived 230 days post-treatment compared to no survival of vehicle-treated mice (n=5). The transplanted KPC and TRAMP showed reduced CD4+ and CD8+ T lymphocytes and B lymphocytes in the tibialis anterior and gastrocnemius vs. NTB after flow cytometry analysis. EC5026 stimulated a general increase in CD3+ T lymphocytes and counter-regulated an eicosanoid-driven cytokine storm as shown by cytokine assays. EC5026 treatment increased tibialis anterior and gastrocnemius muscle weights and body weights compared to vehicle-treated KPC and TRAMP mice. Conclusions: sEH inhibition may be a novel therapeutic approach to cachexia by targeting the immune response via stimulation of resolution of inflammation without toxicity or immunosuppression. Since sEH inhibitors have proven safe and effective in clinical trials for controlling multiple inflammatory diseases, this study provides a basis for the rapid clinical translation of sEH inhibitors to prevent/reverse cachexia in cancer patients. Citation Format: Rachel L. Bayer, Sarina Virani, Michael Gillespie, Jacqueline Capuano, Keira Smith, Katherine Quinlivan, Kimberly Vasquez, Jun Yang, Haixia Yang, Nicholas Mitsiades, Bruce D. Hammock, Dipak Panigrahy. Prevention of cancer cachexia by inhibition of soluble epoxide hydrolase [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 6816.

Abstract 6362: The bispecific antibody KA-3002, targeting PSMA and 4-1BB, specifically enhances T cell activity within prostate tumors

Abstract Cancer immunotherapy with 4-1BB agonists has faced limitations in further clinical development due to dose-limiting toxicity. PSMA, highly expressed in normal prostate tissue and prostate cancer, is a clinically validated target for prostate cancer treatment. In this study, we developed a bispecific antibody (BsAb), KA-3002, targeting PSMA and human 4-1BB, with the aim of restricting 4-1BB stimulation to the interior of tumors. KA-3002 was developed based on our nanobody antibody discovery platform. KA-3002, in IgG1 format, features mutations in the Fc domain to eliminate ADCC, ADCP, and CDC activity. It contains two identical nanobodies at the C-terminal against 4-1BB to stimulate 4-1BB signaling in T cells and binds to PSMA with two Fabs at the N-terminal. KA-3002 exhibits high avidity binding to prostate tumor cells expressing PSMA (EC50&amp;lt;1nM) and also binds to 4-1BB expressed on 293T cells and activated human T cells. In the presence of a low concentration of CD3 antibody to stimulate T cell activation, co-culture of tumor cells expressing PSMA with primary T cells isolated from human PBMC enhances T cell activation and proliferation. In PBMC humanized immunodeficient mouse tumor models, KA-3002 effectively suppresses the growth of 22Rv1 tumors, which highly express PSMA. The antibody also demonstrates a half-life of more than five days in the blood of Balb/c mice. Finally, we assessed the developability of this antibody with different treatments such as high concentration, low pH, repeated freezing and thawing, and high temperature. KA-3002 shows neither aggregation nor degradation. In conclusion, the BsAb KA-3002, developed with our nanobody antibody discovery platform, emerges as a promising pre-clinical candidate drug for the treatment of prostate cancer. Citation Format: Guojin Wu, Jiabei Liang, Hao Peng, Feng Hao, Tongtong Liu, Jinying Ning. The bispecific antibody KA-3002, targeting PSMA and 4-1BB, specifically enhances T cell activity within prostate tumors [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 6362.

Abstract 4102: Treatment with androgen receptor targeting vaccines provides an overall survival benefit in AR-V7 expressing tumor models

Abstract Background: Androgen receptor (AR) signaling inhibition is part of the mechanism behind many effective prostate cancer therapies, including androgen deprivation and next generation anti-androgens. However in castration resistant prostate cancer up to 50% of treatment resistance has been linked to AR amplification or expression of the constitutively active RNA splice variant, AR-V7. Although the use of immune checkpoint blockade has failed to demonstrate clinical success, immunotherapeutic interventions remain attractive as prostate cancer’s relatively slow progression provides time for anti-tumor immune responses to develop. Cancer specific vaccines have the potential to enable and enhance tumor specific immune responses by stimulating and directing T cell immunity to important oncologic targets. We hypothesized that a cancer vaccine designed to induce a T cell response against cells expressing high levels of AR would result in an anti-tumor effect and potentially prevent or delay the development of therapeutic resistance. Methods: Adenoviral vaccines against AR (Ad-AR) or AR splice variant 7 (Ad-AR-V7) were used to evaluate the potential of AR targeting vaccination in mouse models. We evaluated AR and AR variant specific adaptive responses produced by our vaccines with naïve and tumor-bearing mice by ex vivo peptide restimulation. We challenged vaccinated mice with multiple syngeneic subcutaneous tumor models that we engineered to express AR-V7, including a PTEN-/- p53-/- prostate tumor cell line. Finally we tested our vaccines in a therapeutic regimen, vaccinating mice after implanting our subcutaneous AR-V7 expressing models. Results: Across multiple strains of mice, AR or AR-V7 targeting adenoviral vaccination induced robust adaptive immune responses against the N-terminal domain of AR. Vaccination with either Ad-AR or Ad-AR-V7 resulted in significant anti-tumor responses, providing a significant overall survival benefit and complete tumor rejection by the majority of mice vaccinated against AR or AR-V7. Similarly tumor bearing mice treated with Ad-AR or Ad-AR-V7 vaccination displayed tumor growth inhibition or complete tumor regression resulting in an overall survival benefit. Additionally, we found that vaccine responses were unaffected by the use of the approved antiandrogen drug enzalutamide, suggesting that vaccinations could be deployed in tandem with standard-of-care therapies. Conclusions: Vaccination against AR and AR splice variants can induce AR specific adaptive immune responses capable of inhibiting the growth of AR-V7 expressing tumor models, illustrating the potential of AR and its splice variants as immunologic targets in prostate cancer. Citation Format: Robert D. Marek, Junping Wei, Tao Wang, Xiao-Yi Yang, Gangjun Lei, Zachary C. Hartman. Treatment with androgen receptor targeting vaccines provides an overall survival benefit in AR-V7 expressing tumor models [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 4102.