Mouse Model Of Prostate Cancer Research Articles

Cell-autonomous IL6ST activation suppresses prostate cancer development via STAT3/ARF/p53-driven senescence and confers an immune-active tumor microenvironment

BackgroundProstate cancer ranks as the second most frequently diagnosed cancer in men worldwide. Recent research highlights the crucial roles IL6ST-mediated signaling pathways play in the development and progression of various cancers, particularly through hyperactivated STAT3 signaling. However, the molecular programs mediated by IL6ST/STAT3 in prostate cancer are poorly understood.MethodsTo investigate the role of IL6ST signaling, we constitutively activated IL6ST signaling in the prostate epithelium of a Pten-deficient prostate cancer mouse model in vivo and examined IL6ST expression in large cohorts of prostate cancer patients. We complemented these data with in-depth transcriptomic and multiplex histopathological analyses.ResultsGenetic cell-autonomous activation of the IL6ST receptor in prostate epithelial cells triggers active STAT3 signaling and significantly reduces tumor growth in vivo. Mechanistically, genetic activation of IL6ST signaling mediates senescence via the STAT3/ARF/p53 axis and recruitment of cytotoxic T-cells, ultimately impeding tumor progression. In prostate cancer patients, high IL6ST mRNA expression levels correlate with better recurrence-free survival, increased senescence signals and a transition from an immune-cold to an immune-hot tumor.ConclusionsOur findings demonstrate a context-dependent role of IL6ST/STAT3 in carcinogenesis and a tumor-suppressive function in prostate cancer development by inducing senescence and immune cell attraction. We challenge the prevailing concept of blocking IL6ST/STAT3 signaling as a functional prostate cancer treatment and instead propose cell-autonomous IL6ST activation as a novel therapeutic strategy.

Voluntary Exercise Attenuates Tumor Growth in a Preclinical Model of Castration-Resistant Prostate Cancer.

To examine the effects of voluntary exercise training on tumor growth and explore the underlying intratumoral molecular pathways and processes responsible for the beneficial effects of VWR on tumor initiation and progression in a mouse model of Castration-Resistant Prostate Cancer (CRPC). Male immunodeficient mice (SCID) were castrated and subcutaneously inoculated with human CWR-22RV1 cancer cells to construct CRPC xenograft model before randomly assigned to either voluntary wheel running (VWR) or sedentary (SED) group (n=6/group). After three weeks, tumor tissues were collected. Tumor size was measured and calculated. mRNA expression of markers of DNA replication, Androgen Receptor (AR) signaling, and mitochondrial dynamics was determined by RT-PCR. Protein expression of mitochondrial content and dynamics was determined by western blotting. Finally, RNA-sequencing analysis was performed in the tumor tissues. Voluntary wheel running resulted in smaller tumor volume at the initial stage and attenuated tumor progression throughout the time course (P < 0.05). The reduction of tumor volume in VWR group was coincided with lower mRNA expression of DNA replication markers ( MCM2 , MCM6 , and MCM7 ), AR signaling ( ELOVL5 and FKBP5 ) and regulatory proteins of mitochondrial fission (Drp1 and Fis1) and fusion (MFN1 and OPA1) when compared to the SED group (P<0.05). More importantly, RNA sequencing data further revealed that pathways related to pathways related to angiogenesis, extracellular matrix formation and endothelial cell proliferation were downregulated. Three weeks of VWR was effective in delaying tumor initiation and progression, which coincided with reduced transcription of DNA replication, AR signaling targets and mitochondrial dynamics. We further identified reduced molecular pathways/processes related to angiogenesis that may be responsible for the delayed tumor initiation and progression by VWR.

Targeting IRE1α reprograms the tumor microenvironment and enhances anti-tumor immunity in prostate cancer

Unfolded protein response (UPR) is a central stress response pathway that is hijacked by tumor cells for their survival. Here, we find that IRE1α signaling, one of the canonical UPR arms, is increased in prostate cancer (PCa) patient tumors. Genetic or small molecule inhibition of IRE1α in syngeneic mouse PCa models and an orthotopic model decreases tumor growth. IRE1α ablation in cancer cells potentiates interferon responses and activates immune system related pathways in the tumor microenvironment (TME). Single-cell RNA-sequencing analysis reveals that targeting IRE1α in cancer cells reduces tumor-associated macrophage abundance. Consistently, the small molecule IRE1α inhibitor MKC8866, currently in clinical trials, reprograms the TME and enhances anti-PD-1 therapy. Our findings show that IRE1α signaling not only promotes cancer cell growth and survival but also interferes with anti-tumor immunity in the TME. Thus, targeting IRE1α can be a promising approach for improving anti-PD-1 immunotherapy in PCa.

Reduction of myeloid-derived suppressor cells in prostate cancer murine models and patients following white button mushroom treatment.

In a previously reported Phase I trial, we observed therapy-associated declines in circulating myeloid-derived suppressor cells (MDSCs) with the administration of white button mushroom (WBM) tablets in prostate cancer (PCa) patients. These observations led us to hypothesise that WBM could mitigate PCa progression by suppressing MDSCs. We performed bidirectional translational research to examine the immunomodulatory effects of WBM consumption in both syngeneic murine PCa models and patients with PCa participating in an ongoing randomised Phase II trial (NCT04519879). In murine models, WBM treatment significantly suppressed tumour growth with a reduction in both the number and function of MDSCs, which in turn promoted antitumour immune responses mediated by T cells and natural killer (NK) cells. In patients, after consumption of WBM tablets for 3 months, we observed a decline in circulating polymorphonuclear MDSCs (PMN-MDSCs), along with an increase in cytotoxic CD8+ T and NK cells. Furthermore, single immune cell profiling of peripheral blood from WBM-treated patients showed suppressed STAT3/IRF1 and TGFβ signalling in circulating PMN-MDSCs. Subclusters of PMN-MDSCs presented transcriptional profiles associated with responsiveness to fungi, neutrophil chemotaxis, leukocyte aggregation, and regulation of inflammatory response. Finally, in mouse models of PCa, we found that WBM consumption enhanced the anticancer activity of anti-PD-1 antibodies, indicating that WBM may be used as an adjuvant therapy with immune checkpoint inhibitors. Our results from PCa murine models and patients provide mechanistic insights into the immunomodulatory effects of WBM and provide a scientific foundation for WBM as a nutraceutical intervention to delay or prevent PCa progression. White button mushroom (WBM) treatment resulted in a reduction in pro-tumoural MDSCs, notably polymorphonuclear MDSCs (PMN-MDSCs), along with activation of anti-tumoural T and NK cells. Human single immune cell gene expression profiling shed light on the molecular alterations induced by WBM, specifically on PMN-MDSCs. A proof-of-concept study combining WBM with PD-1 blockade in murine models revealed an additive effect on tumour regression and survival outcomes, highlighting the clinical relevance of WBM in cancer management.

Genetically modified extracellular vesicles loaded with activated gasdermin D potentially inhibit prostate-specific membrane antigen-positive prostate carcinoma growth and enhance immunotherapy

Prostate cancer (PCa) is associated with poor immunogenicity and lymphocytic infiltration, and immunotherapy effective against PCa remains unavailable. Pyroptosis, a novel immunotherapeutic modality for cancer, promotes systemic immune responses leading to immunogenic cell death in solid tumors. This paper describes the preparation and analysis of PSMAscFv-EVN-GSDMD; this genetically engineered recombinant extracellular vesicle (EV) expresses a single-chain variable antibody fragment (scFv) with high affinity for prostate-specific membrane antigen (PSMA) on their surfaces and is loaded with the N-terminal domain of gasdermin D (GSDMD). Both in vitro and in vivo, PSMAscFv-EVN-GSDMD effectively targeted PSMA-positive PCa cells and induced pyroptosis through the carrier properties of EVs and the specificity of PSMAscFv. In the 22RV1 and PSMA-transfected RM-1-inoculated PCa mouse models, PSMAscFv-EVN-GSDMD efficiently inhibited tumor growth and promoted tumor immune responses. In conclusion, PSMAscFv-EVN-GSDMD can convert the immunosuppressive “cold” tumor microenvironment of PCa into an immunogenic “hot” tumor microenvironment.

New insights into the regulation and roles of phosphatidylinositol 3,4-bisphosphate.

Phosphoinositides (PIPs) are phospholipids and components of the cellular membrane. In mammals, seven phosphorylated derivatives of PIPs have been identified. Among them, phosphatidylinositol 3,4-bisphosphate [PI(3,4)P2] is produced by lipid phosphatases (e.g., SHIP2) or by lipid kinases PI3KC2α and PI3KC2β. Although PI(3,4)P2 is undetectable in normal mouse or human tissues and common cell lines, it appears in a mouse prostate cancer model and in cells exposed to oxidative stress, indicating that PI(3,4)P2 is involved in the pathogenesis of some diseases. Here, I summarize recent findings on the cellular roles and pathophysiological significance of PI(3,4)P2.

Convergent alterations in the tumor microenvironment of MYC-driven human and murine prostate cancer

How prostate cancer cells and their precursors mediate changes in the tumor microenvironment (TME) to drive prostate cancer progression is unclear, in part due to the inability to longitudinally study the disease evolution in human tissues. To overcome this limitation, we perform extensive single-cell RNA-sequencing (scRNA-seq) and molecular pathology of the comparative biology between human prostate cancer and key stages in the disease evolution of a genetically engineered mouse model (GEMM) of prostate cancer. Our studies of human tissues reveal that cancer cell-intrinsic activation of MYC signaling is a common denominator across the well-known molecular and pathological heterogeneity of human prostate cancer. Cell communication network and pathway analyses in GEMMs show that MYC oncogene-expressing neoplastic cells, directly and indirectly, reprogram the TME during carcinogenesis, leading to a convergence of cell state alterations in neighboring epithelial, immune, and fibroblast cell types that parallel key findings in human prostate cancer.

Single Chelator-Minibody Theranostic Agents for 89Zr PET Imaging and 177Lu Radiopharmaceutical Therapy of PSMA-Expressing Prostate Cancer.

Here we describe an anti-prostate-specific membrane antigen (PSMA) minibody (IAB2MA) conjugated to an octadentate, macrocyclic chelator based on four 1-hydroxypyridin-2-one coordinating units (Lumi804 [L804]) labeled with 89Zr (PET imaging) and 177Lu (radiopharmaceutical therapy), with the goal of developing safer and more efficacious treatment options for prostate cancer. Methods: L804 was compared with the current gold standard chelators, DOTA and deferoxamine (DFO), conjugated to IAB2MA for radiolabeling with 177Lu and 89Zr in cell binding, preclinical biodistribution, imaging, dosimetry, and efficacy studies in the PSMA-positive PC3-PIP tumor-bearing mouse model of prostate cancer. Results: Quantitative radiolabeling (>99% radiochemical yield) of L804-IAB2MA with 177Lu or 89Zr was achieved at ambient temperature in under 30 min, comparable to 89Zr labeling of DFO-IAB2MA. In contrast, DOTA-IAB2MA was radiolabeled with 177Lu for 30 min at 37°C in approximately 90% radiochemical yield, requiring further purification. Using europium(III) as a luminescent surrogate, high binding affinity of Eu-L804-IAB2MA to PSMA was demonstrated in PC3-PIP cells (dissociation constant, 4.6 ± 0.6 nM). All 4 radiolabeled constructs showed significantly higher levels of internalization after 30 min in the PC3-PIP cells than in PSMA-negative PC3-FLU cells. The accumulation of 177Lu- and 89Zr-L804-IAB2MA in PC3-PIP tumors and all organs examined (i.e., heart, liver, spleen, kidney, muscle, salivary glands, lacrimal glands, carcass, and bone) was significantly lower than that of 177Lu-DOTA-IAB2MA and 89Zr-DFO-IAB2MA at 96 and 72 h after injection, respectively. Generally, SPECT/CT and PET/CT imaging data showed no significant difference in the SUVmean of the tumors or muscle between the radiotracers. Dosimetry analysis via both organ-level and voxel-level dose calculation methods indicated significantly higher absorbed doses of 177Lu-DOTA-IAB2MA in tumors, kidney, liver, muscle, and spleen than of 177Lu-L804-IAB2MA. PC3-PIP tumor-bearing mice treated with single doses of 177Lu-L804-IAB2MA (18.4 or 22.2 MBq) exhibited significantly prolonged survival and reduced tumor volume compared with unlabeled minibody control. No significant difference in survival was observed between groups of mice treated with 177Lu-L804-IAB2MA or 177Lu-DOTA-IAB2MA (18.4 or 22.2 MBq). Treatment with 177Lu-L804-IAB2MA resulted in lower absorbed doses in tumors and less toxicity than that of 177Lu-DOTA-IAB2MA. Conclusion: 89Zr- and 177Lu-L804-IAB2MA may be a promising theranostic pair for imaging and therapy of prostate cancer.

The metastasis-promoting P1597L mutation in PlexinB1 enhances Ras activity

BackgroundMetastatic prostate cancer is a leading cause of cancer-related morbidity and mortality in men, yet the underlying molecular mechanisms are poorly understood. Plexins are transmembrane receptors for semaphorins with divergent roles in many forms of cancer. We recently found that a single clinically relevant specific amino acid change (Proline1597Leucine, (P1597L)), found in metastatic deposits of prostate cancer patients, converts PlexinB1 from a metastasis suppressor to a gene that drives prostate cancer metastasis in vivo. However, the mechanism by which PlexinB1(P1597L) promotes metastasis is not known.MethodsPull down assays using GST-RalGDS or -GSTRaf1-RBD were used to reveal the effect of mutant or wild-type PlexinB1 expression on Rap and Ras activity respectively. Protein–protein interactions were assessed in GST pulldown assays, Akt/ERK phosphorylation by immunoblotting and protein stability by treatment with cycloheximide. Rho/ROCK activity was monitored by measuring MLC2 phosphorylation and actin stress fiber formation. PlexinB1 function was measured using cell-collapse assays.ResultsWe show here that the single clinically relevant P1597L amino acid change converts PlexinB1 from a repressor of Ras to a Ras activator. The PlexinB1(P1597L) mutation inhibits the RapGAP activity of PlexinB1, promoting a significant increase in Ras activity. The P1597L mutation also blocks PlexinB1-mediated reduction in Rho/ROCK activity, restraining the decrease in MLC2 phosphorylation and actin stress fiber formation induced by overexpression of wild-type PlexinB1. PlexinB1(P1597L) has little effect on the interaction of PlexinB1 with small GTPases or receptor tyrosine kinases and does not inhibit PlexinB1-stimulated Akt or ERK phosphorylation. These results indicate that the mutation affects Rho signalling via the Rap/Ras pathway. The PlexinB1(P1597L) mutation inhibits morphological cell collapse induced by wild-type PlexinB1 expression, suggesting that the mutation induces a loss of an inhibitory tumour suppressor function.ConclusionThese results suggest that the clinically relevant P1597L mutation in PlexinB1 may transform PlexinB1 from a suppressor to a driver of metastasis in mouse models of prostate cancer by reducing the RapGAP activity of PlexinB1, leading to Ras activation. These findings highlight the PlexinB1-Rap-Ras pathway for therapeutic intervention in prostate cancer.

METTL14 inhibits the proliferation, migration and invasion of prostate cancer cells by increasing m6A methylation of CDK4.

Methyltransferase-like (METTL) plays an important role in various biological processes, but its role in prostate cancer (PCa) is still unclear. This study aimed to explore the mechanism by which methyltransferase-like 14 (METTL14) inhibits the physiological activity of PCa cells by increasing the N6-methyladenosine (m6A) modification of cyclin-dependent kinase 4 (CDK4). Clinical samples were collected for bioinformatics analysis. A PCa mouse model was constructed. Cell counting kit-8 (CCK-8), flow cytometry, colony formation assays, scratch assays, Transwell assays, real-time quantitative polymerase chain reaction (RT-qPCR), immunofluorescence and western blotting were used to detect the corresponding indicators. METTL14 was found to be beneficial to inhibit the proliferation, invasion, and migration of PCa cells. When the m6A RNA increased, the half-life of CDK4 mRNA decreased after oe-METTL14 (overexpression of METTL14). Overexpression of CDK4 reversed the effect of oe-METTL14. Coimmunoprecipitation experiments revealed there were interactions between CDK4 and forkhead box M1 (FOXM1). Transfection of si-CDK4 was similar to transfection of oe-METTL14. After transfection with oe-FOXM1, the invasion and migration ability of cells increased, and cell apoptosis decreased. After transfection with si-FOXM1 alone, autophagy related 7 (ATG7) expression was significantly downregulated, and autophagy levels were reduced. The overexpression of ATG7 reversed the effect of si-FOXM1. The tumor volume and weight of the oe-METTL14 group mice were significantly reduced, and tumor proliferation was decreased in comparison to untreated tumor-bearing mice. METTL14 inhibits the invasion and migration of PCa cells and induces cell apoptosis by inhibiting CDK4 stability and FOXM1/ATG7-mediated autophagy.

Histone demethylase PHF8 promotes prostate cancer metastasis via the E2F1-SNAI1 axis.

Metastasis is the primary culprit behind cancer-related fatalities in multiple cancer types, including prostate cancer. Despite great advances, the precise mechanisms underlying prostate cancer metastasis are far from complete. By using a transgenic mouse prostate cancer model (TRAMP) with and without Phf8 knockout, we have identified a crucial role of PHF8 in prostate cancer metastasis. By complexing with E2F1, PHF8 transcriptionally upregulates SNAI1 in a demethylation-dependent manner. The upregulated SNAI1 subsequently enhances epithelial-to-mesenchymal transition (EMT) and metastasis. Given the role of the abnormally activated PHF8/E2F1-SNAI1 axis in prostate cancer metastasis and poor prognosis, the levels of PHF8 or the activity of this axis could serve as biomarkers for prostate cancer metastasis. Moreover, targeting this axis could become a potential therapeutic strategy for prostate cancer treatment. © 2024 The Pathological Society of Great Britain and Ireland.

Integration of photomagnetic bimodal imaging to monitor an autogenous exosome loaded platform: unveiling strong targeted retention effects for guiding the photothermal and magnetothermal therapy in a mouse prostate cancer model

BackgroundProstate cancer (PCa) is the most prevalent cancer among males, emphasizing the critical need for precise diagnosis and treatment to enhance patient prognosis. Recent studies have extensively utilized urine exosomes from patients with cancer for targeted delivery. This study aimed to employ highly sensitive magnetic particle imaging (MPI) and fluorescence molecular imaging (FMI) to monitor the targeted delivery of an exosome-loaded platform at the tumour site, offering insights into a potential combined photothermal and magnetic thermal therapy regime for PCa.ResultsMPI and FMI were utilized to monitor the in vivo retention performance of exosomes in a prostate tumour mouse model. The exosome-loaded platform exhibited robust homologous targeting ability during imaging (SPIONs@EXO-Dye:66·48%±3·85%; Dye-SPIONs: 34·57%±7·55%, **P<0·01), as verified by in vitro imaging and in vitro tissue Prussian blue staining.ConclusionsThe experimental data underscore the feasibility of using MPI for in vivo PCa imaging. Furthermore, the exosome-loaded platform may contribute to the precise diagnosis and treatment of PCa.Graphical

Evaluation of a bimodal, matched pair theranostic agent targeting prostate-specific membrane antigen

BackgroundProstate cancer affects 1 in 6 men, and it is the second‑leading cause of cancer-related death in American men. Surgery is one of the main treatment modalities for prostate cancer, but it often results in incomplete resection margins or complete resection that leads to nerve damage and undesirable side effects. In the present work, we have developed a new bimodal tracer, NODAGA-sCy7.5 PSMAi (prostate-specific membrane antigen inhibitor), labeled with the true matched theranostic pair 64Cu/67Cu and a near-infrared fluorescent dye. This agent could potentially be used for concomitant PET imaging, optical surgical navigation, and targeted radiopharmaceutical therapy. MethodsA prostate-specific membrane antigen (PSMA)-targeting urea derivative was conjugated to NODAGA for copper radiolabeling and to the near-infrared fluorophore sulfo-Cy7.5 (sCy7.5). Binding studies were performed in PSMA-positive PC-3 PIP cells, as well as uptake and internalization assays in PC-3 PIP cells and PSMA-negative PC-3 wild type cells. Biodistribution studies of the 64Cu-labeled compound were performed in PC-3 PIP- and PC-3 tumor-bearing mice, and 67Cu biodistributions of the agent were obtained in PC-3 PIP tumor-carrying mice. PET imaging and fluorescence imaging were also performed, using the same molar doses, in the two mouse models. ResultsThe PSMA conjugate bound with high affinity to PSMA-positive prostate cancer cells, as opposed to cells that were PSMA-negative. Uptake and internalization were rapid and PSMA-mediated in PC-3 PIP cells, while only minimal non-specific uptake was observed in PC-3 cells. Biodistribution studies showed specific uptake in PC-3 PIP tumors, while accumulation in PC-3 tumor-bearing mice was low. Furthermore, tumor uptake of the 67Cu-labeled agent in the PC-3 PIP model was statistically equivalent to that of 64Cu. PET and fluorescence imaging at 0.5 nmol per mouse also demonstrated that PC-3 PIP tumors could be clearly detected, while PC-3 tumors showed no tumor accumulation. ConclusionsNODAGA-sCy7.5-PSMAi was specific and selective in detecting PSMA-positive, as opposed to PSMA-negative, tumors in mouse models of prostate cancer. This bioconjugate could potentially be used for PET staging with 64Cu, targeted radiopharmaceutical therapy with 67Cu, and/or image-guided surgery with sCy7.5.

Examination of the PET in vivo generator 134Ce as a theranostic match for 225Ac.

The radionuclide pair cerium-134/lanthanum-134 (134Ce/134La) was recently proposed as a suitable diagnostic counterpart for the therapeutic alpha-emitter actinium-225 (225Ac). The unique properties of 134Ce offer perspectives for developing innovative in vivo investigations that are not possible with 225Ac. In this work, 225Ac- and 134Ce-labelled tracers were directly compared using internalizing and slow-internalizing cancer models to evaluate their in vivo comparability, progeny meandering, and potential as a matched theranostic pair for clinical translation. Despite being an excellent chemical match, 134Ce/134La has limitations to the setting of quantitative positron emission tomography imaging. The precursor PSMA-617 and a macropa-based tetrazine-conjugate (mcp-PEG8-Tz) were radiolabelled with 225Ac or 134Ce and compared in vitro and in vivo using standard (radio)chemical methods. Employing biodistribution studies and positron emission tomography (PET) imaging in athymic nude mice, the radiolabelled PSMA-617 tracers were evaluated in a PC3/PIP (PC3 engineered to express a high level of prostate-specific membrane antigen) prostate cancer mouse model. The 225Ac and 134Ce-labelled mcp-PEG8-Tz were investigated in a BxPC-3 pancreatic tumour model harnessing the pretargeting strategy based on a trans-cyclooctene-modified 5B1 monoclonal antibody. In vitro and in vivo studies with both 225Ac and 134Ce-labelled tracers led to comparable results, confirming the matching pharmacokinetics of this theranostic pair. However, PET imaging of the 134Ce-labelled precursors indicated that quantification is highly dependent on tracer internalization due to the redistribution of 134Ce's PET-compatible daughter 134La. Consequently, radiotracers based on internalizing vectors like PSMA-617 are suited for this theranostic pair, while slow-internalizing 225Ac-labelled tracers are not quantitatively represented by 134Ce PET imaging. When employing slow-internalizing vectors, 134Ce might not be an ideal match for 225Ac due to the underestimation of tumour uptake caused by the in vivo redistribution of 134La. However, this same characteristic makes it possible to estimate the redistribution of 225Ac's progeny noninvasively. In future studies, this unique PET in vivo generator will further be harnessed to study tracer internalization, trafficking of receptors, and the progression of the tumour microenvironment.

Emerging Perspectives in Zinc Transporter Research in Prostate Cancer: An Updated Review.

Dysregulation of zinc and zinc transporters families has been associated with the genesis and progression of prostate cancer. The prostate epithelium utilizes two types of zinc transporters, the ZIP (Zrt-, Irt-related Protein) and the ZnTs (Zinc Transporter), to transport zinc from the blood plasma to the gland lumen. ZIP transporters uptake zinc from extracellular space and organelle lumen, while ZnT transporters release zinc outside the cells or to organelle lumen. In prostate cancer, a commonly observed low zinc concentration in prostate tissue has been correlated with downregulations of certain ZIPs (e.g., ZIP1, ZIP2, ZIP3, ZIP14) and upregulations of specific ZnTs (e.g., ZnT1, ZnT9, ZnT10). These alterations may enable cancer cells to adapt to toxic high zinc levels. While zinc supplementation has been suggested as a potential therapy for this type of cancer, studies have yielded inconsistent results because some trials have indicated that zinc supplementation could exacerbate cancer risk. The reason for this discrepancy remains unclear, but given the high molecular and genetic variability present in prostate tumors, it is plausible that some zinc transporters-comprising 14 ZIP and 10 ZnT members-could be dysregulated in others patterns that promote cancer. From this perspective, this review highlights novel dysregulation, such as ZIP-Up/ZnT-Down, observed in prostate cancer cell lines for ZIP4, ZIP8, ZnT2, ZnT4, ZnT5, etc. Additionally, an in silico analysis of an available microarray from mouse models of prostate cancer (Nkx3.1;Pten) predicts similar dysregulation pattern for ZIP4, ZIP8, and ZnT2, which appear in early stages of prostate cancer progression. Furthermore, similar dysregulation patterns are supported by an in silico analysis of RNA-seq data from human cancer tumors available in cBioPortal. We discuss how these dysregulations of zinc transporters could impact zinc supplementation trials, particularly focusing on how the ZIP-Up/ZnT-Down dysregulation through various mechanisms might promote prostate cancer progression.

Abstract PR010: CDK12 loss promotes prostate cancer development while exposing vulnerabilities to paralog-based synthetic lethality

Abstract Biallelic loss of cyclin-dependent kinase 12 (CDK12) defines a unique molecular subtype of metastatic castration-resistant prostate cancer (mCRPC). It remains unclear, however, whether CDK12 loss per se is sufficient to drive prostate cancer development—either alone, or in the context of other genetic alterations—and whether CDK12-mutant tumors exhibit sensitivity to specific pharmacotherapies. Here, we demonstrate that tissue-specific Cdk12 ablation is sufficient to induce preneoplastic lesions and robust T cell infiltration in the mouse prostate. Allograft-based CRISPR screening demonstrated that Cdk12 loss is positively associated with Trp53 inactivation but negatively associated with Pten inactivation—akin to what is observed in human mCRPC. Consistent with this, ablation of Cdk12 in prostate organoids with concurrent Trp53 loss promotes their proliferation and ability to form tumors in mice, while Cdk12knockout in the Pten-null prostate cancer mouse model abrogates tumor growth. Bigenic Cdk12 and Trp53 loss allografts represent a new syngeneic model for the study of androgen receptor (AR)-positive, luminal prostate cancer. Notably, Cdk12/Trp53 loss prostate tumors are sensitive to immune checkpoint blockade. Cdk12-null organoids (either with or without Trp53 co-ablation) and patient-derived xenografts from tumors with CDK12 inactivation are highly sensitive to inhibition or degradation of its paralog kinase, CDK13. Together, these data identify CDK12 as a bona fidetumor suppressor gene with impact on tumor progression and lends support to paralog-based synthetic lethality as a promising strategy for treating CDK12-mutant mCRPC. Citation Format: Jean C. Tien, Yu Chang, Yuping Zhang, Jonathan Chou, Yunhui Cheng, Xiaoju Wang, Jianzhang Yang, Rahul Mannan, Palak Shah, Xiao-Ming Wang, Abbey Todd, Sanjana Eyunni, Caleb Cheng, Xuhong Cao, Yi Bao, James Neiswender, Rachel Brough, Stephen Pettitt, Estefania Labanca, Yuzhuo Wang, Marcin Cieslik, Christopher J. Lord, Ke Ding, Arul M. Chinnaiyan. CDK12 loss promotes prostate cancer development while exposing vulnerabilities to paralog-based synthetic lethality [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Expanding and Translating Cancer Synthetic Vulnerabilities; 2024 Jun 10-13; Montreal, Quebec, Canada. Philadelphia (PA): AACR; Mol Cancer Ther 2024;23(6 Suppl):Abstract nr PR010.

Decorrelation Time Mapping as an Analysis Tool for Nanobubble-Based Contrast Enhanced Ultrasound Imaging.

Nanobubbles (NBs; ~100-500 nm diameter) are preclinical ultrasound (US) contrast agents that expand applications of contrast enhanced US (CEUS). Due to their sub-micron size, high particle density, and deformable shell, NBs in pathological states of heightened vascular permeability (e.g. in tumors) extravasate, enabling applications not possible with microbubbles (~1000-10,000 nm diameter). A method that can separate intravascular versus extravascular NB signal is needed as an imaging biomarker for improved tumor detection. We present a demonstration of decorrelation time (DT) mapping for enhanced tumor NB-CEUS imaging. In vitro models validated the sensitivity of DT to agent motion. Prostate cancer mouse models validated in vivo imaging potential and sensitivity to cancerous tissue. Our findings show that DT is inversely related to NB motion, offering enhanced detail of NB dynamics in tumors, and highlighting the heterogeneity of the tumor environment. Average DT was high in tumor regions (~9 s) compared to surrounding normal tissue (~1 s) with higher sensitivity to tumor tissue compared to other mapping techniques. Molecular NB targeting to tumors further extended DT (11 s) over non-targeted NBs (6 s), demonstrating sensitivity to NB adherence. From DT mapping of in vivo NB dynamics we demonstrate the heterogeneity of tumor tissue while quantifying extravascular NB kinetics and delineating intra-tumoral vasculature. This new NB-CEUS-based biomarker can be powerful in molecular US imaging, with improved sensitivity and specificity to diseased tissue and potential for use as an estimator of vascular permeability and the enhanced permeability and retention (EPR) effect in tumors.

Clinically Relevant Humanized Mouse Models of Metastatic Prostate Cancer Facilitate Therapeutic Evaluation.

There is tremendous need for improved prostate cancer models. Anatomically and developmentally, the mouse prostate differs from the human prostate and does not form tumors spontaneously. Genetically engineered mouse models lack the heterogeneity of human cancer and rarely establish metastatic growth. Human xenografts are an alternative but must rely on an immunocompromised host. Therefore, we generated prostate cancer murine xenograft models with an intact human immune system (huNOG and huNOG-EXL mice) to test whether humanizing tumor-immune interactions would improve modeling of metastatic prostate cancer and the impact of androgen receptor-targeted and immunotherapies. These mice maintain multiple human immune cell lineages, including functional human T-cells and myeloid cells. Implications: To the best of our knowledge, results illustrate the first model of human prostate cancer that has an intact human immune system, metastasizes to clinically relevant locations, responds appropriately to standard-of-care hormonal therapies, and can model both an immunosuppressive and checkpoint-inhibition responsive immune microenvironment.

Fibroblast growth factor pathway promotes glycolysis by activating LDHA and suppressing LDHB in a STAT1-dependent manner in prostate cancer

BackgroundThe initiation of fibroblast growth factor 1 (FGF1) expression coincident with the decrease of FGF2 expression is a well-documented event in prostate cancer (PCa) progression. Lactate dehydrogenase A (LDHA) and LDHB are essential metabolic products that promote tumor growth. However, the relationship between FGF1/FGF2 and LDHA/B-mediated glycolysis in PCa progression is not reported. Thus, we aimed to explore whether FGF1/2 could regulate LDHA and LDHB to promote glycolysis and explored the involved signaling pathway in PCa progression.MethodsIn vitro studies used RT‒qPCR, Western blot, CCK-8 assays, and flow cytometry to analyze gene and protein expression, cell viability, apoptosis, and cell cycle in PCa cell lines. Glycolysis was assessed by measuring glucose consumption, lactate production, and extracellular acidification rate (ECAR). For in vivo studies, a xenograft mouse model of PCa was established and treated with an FGF pathway inhibitor, and tumor growth was monitored.ResultsFGF1, FGF2, and LDHA were expressed at high levels in PCa cells, while LDHB expression was low. FGF1/2 positively modulated LDHA and negatively modulated LDHB in PCa cells. The depletion of FGF1, FGF2, or LDHA reduced cell proliferation, induced cell cycle arrest, and inhibited glycolysis. LDHB overexpression showed similar inhibitory effect on PCa cells. Mechanistically, we found that FGF1/2 positively regulated STAT1 and STAT1 transcriptionally activated LDHA expression while suppressed LDHB expression. Furthermore, the treatment of an FGF pathway inhibitor suppressed PCa tumor growth in mice.ConclusionThe FGF pathway facilitates glycolysis by activating LDHA and suppressing LDHB in a STAT1-dependent manner in PCa.

Effects of bipolar irreversible electroporation with different pulse durations in a prostate cancer mouse model.

Irreversible electroporation (IRE) is a non-thermal ablation technique for local tumor treatment known to be influenced by pulse duration and voltage settings, affecting its efficacy. This study aims to investigate the effects of bipolar IRE with different pulse durations in a prostate cancer mouse model. The therapeutic effectiveness was assessed with in vitro cell experiments, in vivo tumor volume changes with magnetic resonance imaging, and gross and histological analysis in a mouse model. The tumor volume continuously decreased over time in all IRE-treated groups. The tumor volume changes, necroptosis (%), necrosis (%), the degree of TUNEL-positive cell expression, and ROS1-positive cell (%) in the long pulse duration-treated groups (300μs) were significantly increased compared to the short pulse duration-treated groups (100μs) (all p < 0.001). The bipolar IRE with a relatively long pulse duration at the same voltage significantly increased IRE-induced cell death in a prostate cancer mouse model.