Prostate Tumor Cells Research Articles

Development of a multiplex assay to assess activated p300/CBP in circulating prostate tumor cells.

Reduced SIRT2 deacetylation and increased p300 acetylation activity leads to a concerted mechanism of hyperacetylation at specific histone lysine sites (H3K9, H3K14, and H3K18) in castration-resistant prostate cancer (CRPC). We examined whether circulating tumor cells (CTCs) identify patients with altered p300/CBP acetylation. CTCs were isolated from 13 advanced PC patients using Exclusion-based Sample Preparation (ESP) technology. Bound cells underwent immunofluorescent staining for histone modifying enzymes (HMEs) of interest and image capture with NIS-Elements software. Using the cBioPortal PCF/SU2C dataset, the response of CRPC to androgen receptor signaling inhibitors (ARSI) was analyzed in 50 subjects. Staining optimization and specificity revealed clear expression of acetyl-p300, acetyl-H3K18, and SIRT2 on CTCs (CK positive, CD45 negative cells). Exposure to A-485, a selective p300/CBP catalytic inhibitor, reduced p300 and H3K18 acetylation. In CRPC patients, a-p300 strongly correlated with its target acetylated H3k18 (Pearson's R = 0.61), and SIRT2 expression showed robust negative correlation with a-H3k18 (R = -0.60). A subgroup of CRPC patients (6/11; 55%) demonstrated consistent upregulation of acetylation based on these markers. To examine the clinical impact of upregulation of the CBP/p300 axis, CRPC patients with reduced deacetylase SIRT2 expression demonstrate shorter response times to ARSI therapy (5.9 vs. 12 mo; p = 0.03). A subset of CRPC patients demonstrate increased p300/CBP activity based on a novel CTC biomarker assay. With further development, this biomarker suite may be used to identify candidates for CBP/p300 acetylation inhibitors in clinical development.

LINC01088/miR-22/CDC6 Axis Regulates Prostate Cancer Progression by Activating the PI3K/AKT Pathway.

Prostate cancer (PCa) harms the male reproductive system, and lncRNA may play an important role in it. Here, we report that the LINC01088/microRNA- (miRNA/miR-) 22/cell division cycle 6 (CDC6) axis regulated through the phosphatidylinositide 3-kinases- (PI3K-) protein kinase B (AKT) signaling pathway controls the development of PCa. lncRNA/miRNA/mRNA associated with PCa was downloaded and analyzed by Gene Expression Omnibus. The expression and correlation of LINC01088/miR-22/CDC6 in PCa were analyzed and verified by RT-qPCR. Dual-luciferase was used to analyze the binding between miR-22 and LINC01088 or CDC6. Cell Counting Kit-8 and Transwell were used to analyze the effects of LINC01088/miR-22/CDC6 interactions on PCa cell viability or migration/invasion ability. Localization of LINC01088 in cells was analyzed by nuclear cytoplasmic separation. The effect of LINC01088/miR-22/CDC6 interaction on downstream PI3K/AKT signaling was analyzed by Western blot. LINC01088 or CDC6 was upregulated in prostate tumor tissues or cells, whereas miR-22 was downregulated, miR-22 directly targets both LINC01088 and CDC6. si-LINC01088 inhibits the PCa process by suppressing the PI3K/AKT pathway. CDC6 reverses si-linc01088-mediated cell growth inhibition and reduction of PI3K and AKT protein levels. Our results demonstrate that the LINC01088/miR-22/CDC6 axis functions in PCa progression and provide a promising diagnostic and therapeutic target.

The Akt/mTOR and MNK/eIF4E pathways rewire the prostate cancer translatome to secrete HGF, SPP1 and BGN and recruit suppressive myeloid cells.

Cancer is highly infiltrated by myeloid-derived suppressor cells (MDSCs). Currently available immunotherapies do not completely eradicate MDSCs. Through a genome-wide analysis of the translatome of prostate cancers driven by different genetic alterations, we demonstrate that prostate cancer rewires its secretome at the translational level to recruit MDSCs. Among different secreted proteins released by prostate tumor cells, we identified Hgf, Spp1 and Bgn as the key factors that regulate MDSC migration. Mechanistically, we found that the coordinated loss of Pdcd4 and activation of the MNK/eIF4E pathways regulate the mRNAs translation of Hgf, Spp1 and Bgn. MDSC infiltration and tumor growth were dampened in prostate cancer treated with the MNK1/2 inhibitor eFT508 and/or the AKT inhibitor ipatasertib, either alone or in combination with a clinically available MDSC-targeting immunotherapy. This work provides a therapeutic strategy that combines translation inhibition with available immunotherapies to restore immune surveillance in prostate cancer.

Impairment of SK-MEL-28 Development—A Human Melanoma Cell Line—By the Crataeva tapia Bark Lectin and Its Sequence-Derived Peptides

Melanoma is difficult to treat with chemotherapy, prompting the need for new treatments. Protease inhibitors have emerged as promising candidates as tumor cell proteases promote metastasis. Researchers have developed a chimeric form of the Bauhinia bauhinioides kallikrein inhibitor, rBbKIm, which has shown negative effects on prostate tumor cell lines DU145 and PC3. Crataeva tapia bark lectin, CrataBL, targets sulfated oligosaccharides in glycosylated proteins and has also demonstrated deleterious effects on prostate and glioblastoma tumor cells. However, neither rBbKIm nor its derived peptides affected the viability of SK-MEL-28, a melanoma cell line, while CrataBL decreased viability by over 60%. Two peptides, Pep. 26 (Ac-Q-N-S-S-L-K-V-V-P-L-NH2) and Pep. 27 (Ac-L-P-V-V-K-L-S-S-N-Q-NH2), were also tested. Pep. 27 suppressed cell migration and induced apoptosis when combined with vemurafenib, while Pep. 26 inhibited cell migration and reduced nitric oxide and the number of viable cells. Vemurafenib, a chemotherapy drug used to treat melanoma, was found to decrease the release of interleukin 8 and PDGF-AB/BB cytokines and potentiated the effects of proteins and peptides in reducing these cytokines. These findings suggest that protease inhibitors may be effective in blocking melanoma cells and highlight the potential of CrataBL and its derived peptides.

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.

Inducing apoptosis by using microRNA in radio-resistant prostate cancer: an in-silico study with an in-vitro validation.

One of the problems with radiation therapy (RT) is that prostate tumor cells are often radio-resistant, which results in treatment failure. This study aimed to determine the procedure involved in radio-resistant prostate cancer apoptosis. For a deeper insight, we devoted a novel bioinformatics approach to analyze the targeting between microRNAs and radio-resistant prostate cancer genes. This study uses the Tarbase, and the Mirtarbase databases as validated experimental databases and mirDIP as a predicted database to identify microRNAs that target radio-resistant anti-apoptotic genes. These genes are used to construct the radio-resistant prostate cancer genes network using the online tool STRING. The validation of causing apoptosis by using microRNA was confirmed with flow cytometry of Annexin V. The anti-apoptotic gene of radio-resistant prostate cancer included BCL-2, MCL1, XIAP, STAT3, NOTCH1, REL, REL B, BIRC3, and AKT1 genes. These genes were identified as anti-apoptotic genes for radio-resistant prostate cancer. The crucial microRNA that knockdown all of these genes was hsa-miR-7-5p. The highest rate of apoptotic cells in a cell transfected with hsa-miR-7-5p was (32.90 ± 1.49), plenti III (21.99 ± 3.72), and the control group (5.08 ± 0.88) in 0Gy (P < 0.001); also, this rate was in miR-7-5p (47.01 ± 2.48), plenti III (33.79 ± 3.40), and the control group (16.98 ± 3.11) (P < 0.001) for 4Gy. The use of this new treatment such as gene therapy to suppress genes involved in apoptosis can help to improve the treatment results and increase the quality of life of patients with prostate cancer.

Abstract B035: Leveraging therapy-induced senescence for prostate cancer immunotherapy

Abstract Most prostate cancers are immunologically “cold” with poor tumor immunogenicity and a lack of cytotoxic T cells, and as such are generally unresponsive to immune checkpoint blockade (ICB) therapies that can reactivate T cell immunity and lead to durable and curative responses in other treatment-refractory solid tumors. We recently demonstrated that therapeutic induction of a durable growth arrest phenotype known as cellular senescence in the setting of pancreatic cancer can be novel approach to make “cold” tumors “hot” and sensitize them to anti-PD-1 ICB (Ruscetti et al. Cell 2020). This senescence-driven immunological effect is mediated through induction of immunomodulatory cell surface molecules, including MHC-I expression required for antigen presentation to T cells, and activation of the senescence-associated secretory phenotype (SASP), a collection of pleiotropic cytokines, chemokines, and other growth factors that can remodel the surrounding tumor-immune landscape. While this acute SASP activation can promote cytotoxic CD8+ T and Natural Killer (NK) cell anti-tumor immunity in some contexts, chronic SASP can alternatively lead to immune suppression and tumor cell invasion and metastasis that contributes to relapse after therapy. Here we set out to characterize the senescence-inducing capacity of chemotherapies, DNA repair inhibitors, and cell cycle targeting agents implicated in cellular senescence and used in the treatment of castration-resistant prostate cancer (CRPC), and the impact of their subsequent SASPs on immune responses and therapy outcomes. Using a suite of genetically-defined murine prostate cancer cell lines and an in vitro pipeline to rapidly define senescence phenotypes following treatment, we found that many commonly used cancer therapeutics can induce cellular senescence, with chemotherapies, Aurora kinase inhibitors, and CDK inhibitors producing the most robust senescence-induced cell cycle arrest across conditions. Prostate tumor cells harboring compound tumor suppressor losses such as Pten, p53, and Rb1 were more susceptible to therapeutic senescence induction. Strikingly, only a subset of therapies that induce senescence-associated growth arrest produced an inflammatory SASP and induction of activating NK cell ligands and antigen presentation and processing genes necessary for NK and T cell immunity. Moreover, whereas most SASPs induced NK cell activity in vitro, they also polarized macrophages toward a pro-tumorigenic and immune suppressive M2 phenotype that may limit their anti-tumor efficacy. CDK inhibitors produced a SASP that could activate lymphocytes without inducing suppressive myeloid populations in MYC-driven tumors, suggesting their use may be a promising approach to target prostate cancers harboring the currently “undruggable” MYC oncogene. Collectively, our studies demonstrate that induction of senescence and its non-cell autonomous arm, the SASP, could be a unique approach to treat CRPC and create new immunological dependencies that can be potentially harnessed for prostate cancer immunotherapy. Citation Format: Lin Zhou, Katherine C. Murphy, Jarin Snyder, Kelly D. DeMarco, Boyang Ma, Marcus Ruscetti. Leveraging therapy-induced senescence for prostate cancer immunotherapy [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 B035.

A Triazaspirane Derivative Inhibits Migration and Invasion in PC3 Prostate Cancer Cells.

Cancer is a serious health problem due to the complexity of establishing an effective treatment. The purpose of this work was to evaluate the activity of a triazaspirane as a migration and invasion inhibitor in PC3 prostatic tumor cells through a possible negative regulation of the FAK/Src signal transduction pathway and decreased secretion of metalloproteinases 2 and 9. Molecular docking analysis was performed using Moe 2008.10 software. Migration (wound-healing assay) and invasion (Boyden chamber assay) assays were performed. In addition, the Western blot technique was used to quantify protein expression, and the zymography technique was used to observe the secretion of metalloproteinases. Molecular docking showed interactions in regions of interest of the FAK and Src proteins. Moreover, the biological activity assays demonstrated an inhibitory effect on cell migration and invasion, an important suppression of metalloproteinase secretion, and a decrease in the expression of p-FAK and p-Src proteins in treated PC3 cells. Triazaspirane-type molecules have important inhibitory effects on the mechanisms associated with metastasis in PC3 tumor cells.

Abstract B024: Nuclear size and nuclear shape instability in prostate cancer epithelial cells during metastatic progression

Abstract Very small nuclear (vsn) circulating tumor cells (CTCs) are detected in a subgroup of metastatic, castration resistant prostate cancer (mCRPC) patients who develop visceral metastasis following intensive androgen receptor suppression. In addition, we have previously observed that nuclear shape instability (characterized by the loss and/or mis-localization of the nuclear envelop protein emerin) is present in human prostate cancer tissues, and in CTCs from patients with metastatic disease. Herein, we investigated the biological and clinical implications of the vsn phenotype in prostate CTCs. Patients with vsnCTCs had poor overall survival and low PSA response to androgen receptor suppression compared with non-vsnCTC patients. The vsnCTCs exhibited a loss/downregulation of emerin (EMD) and we found a direct correlation between emerin loss and nuclear size reduction in CTC from mCRPC patients. Further, in vitro studies revealed that the vsn phenotype was characterized by high invasive capacity, enhanced cellular plasticity, and resistance to AR target therapy. Finally, depletion of EMD in prostate tumor cells resulted in the vsn phenotype. Together, these findings demonstrate that the vsnCTC phenotype is characterized by deregulation of EMD expression, and the presence of these cells result in poor clinical outcomes in prostate cancer. Citation Format: Karen Cavassani, Edwin Posadas, Pai-Chi Teng, Sadaf Pustchi Pustchi, Minhyung Kim, Neil Bhowmick, Sungyong You, Michael Freeman, Leigh Ellis, Dolores Di Vizio, Hsian-Rong Tseng, Leland W. Chung, Susan Yao, Catherine Grasso. Nuclear size and nuclear shape instability in prostate cancer epithelial cells during metastatic progression [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 B024.

Cancer‐cell‐biomimetic nanoparticles for enhanced prostate cancer therapy

AbstractBACKGROUNDThe targeted delivery of traditional chemotherapeutic drugs by nanocarriers has become an effective way to reduce drug toxicity and improve antitumor effects. However, nanocarriers are easily recognized and cleared by the immune system after entering the body, thereby reducing their therapeutic effect.RESULTSIn this work, based on the biomimetic design concept, a tumor cell membrane‐coated nanoplatform (TCM/SCM/DTX) was fabricated for evading the clearance of the immune system and efficiently targeting tumor tissues to achieve efficient drug accumulation in tumor tissues. In vitro cell experiments, TCM/SCM/DTX could effectively enter prostate tumor cells and showed a good in vitro anti‐tumor effect. After administration, TCM/SCM/DTX could efficiently accumulate into tumor tissue while achieving long‐term blood circulation. The in vivo anti‐tumor results proved its effective tumor growth inhibitory effect, and the immunohistochemical results also proved that TCM/SCM/DTX significantly reduced the tissue and organ toxicity of DTX.CONCLUSIONSThis study shows that the prostate tumor cell membrane‐coated biomimetic nanocarriers can effectively deliver traditional chemotherapeutic drugs to prostate cancer tissue, which provides a new strategy for precise and efficient chemotherapy of prostate cancer, especially advanced prostate cancer. © 2023 Society of Chemical Industry (SCI).

Hypoxia‐inducible factor 1A inhibition overcomes castration resistance of prostate tumors

Androgen deprivation therapy (ADT) is a cornerstone of prostate cancer (PCa) management. Although tumors initially regress, many progress to a hormone‐independent state termed castration‐resistant PCa (CRPC), for which treatment options are limited. We here report that the major luminal cell population in tumors of Pten(i)pe−/− mice, generated by luminal epithelial cell‐specific deletion of the tumor suppressor PTEN after puberty, is castration‐resistant and that the expression of inflammation and stemness markers is enhanced in persistent luminal cells. In addition, hypoxia‐inducible factor 1 (HIF1) signaling, which we have previously demonstrated to be induced in luminal cells of Pten(i)pe−/− mice and to promote malignant progression, is further activated. Importantly, we show that genetic and pharmacological inhibition of HIF1A sensitizes Pten‐deficient prostatic tumors to castration and provides durable therapeutic responses. Furthermore, HIF1A inhibition induces apoptotic signaling in human CRPC cell lines. Therefore, our data demonstrate that HIF1A in prostatic tumor cells is a critical factor that enables their survival after ADT, and identify it as a target for CRPC management.

Antibacterial and Cytotoxic Silica-Polycaprolactone-Chlorogenic Acid Hybrids by Sol-Gel Route.

Organic-inorganic hybrid materials were synthesized by a sol-gel route, using silicon alkoxide together with low molecular weight polycaprolactone and caffetannic acid. The synthesized hybrids were characterized by scanning Fourier-transform infrared (FTIR) spectroscopy, and their surface morphology was acquired by scanning electron microscopy (SEM) analysis. The hybrids were investigated for their antiradical capacity using the DPPH and ABTS tests, while the Kirby-Bauer test was used to evaluate their effects on the growth of Escherichia coli and Enterococcus faecalis. Furthermore, a biologically active hydroxyapatite layer has been observed to form on the surface of intelligently synthesized materials. The MTT direct test showed that the hybrid materials are biocompatible with NIH-3T3 fibroblast cells, while they were cytotoxic towards colon, prostate, and brain tumor cell lines. These results shed new light on the suitability of the synthesized hybrids in the medical field, thus affording knowledge on the features of the bioactive silica-polycaprolactone-chlorogenic acid hybrids.

Abstract 2877: Profiling of myeloid-derived suppressor cells in Pten-deficient in prostate cancer progression

Abstract Myeloid-derived suppressor cells (MDSCs) are a heterogenous population of immature immune cells that expand during cancer and can induce potent immune suppression. These cells play critical roles in supporting tumor growth and progression and their induction has been associated with the inactivation of PTEN. To date, few therapies targeting these cells are available which is partly due to their increasingly complex nature and context-dependent functions. Moreover, there is no clear definition to identify these cells. Enhancing our understanding of this cell population will aid in developing more effective cancer therapies. Here, we used gene expression profiling, flow cytometry, and quantitative immunohistochemistry to characterize tumor-infiltrating and circulating MDSCs in prostate carcinogenesis and progression in transgenic mouse models of prostate cancer driven by the conditional inactivation of Pten and Trp53. Transcriptomic profiling revealed enrichment of various myeloid-derived cell signatures in the early stages of prostate cancer including MDSCs, macrophages, and neutrophils. Flow cytometric analysis confirmed the increased infiltration of CD11b+/Ly6G+ (polymorphonuclear MDSCs (pMDSCs)) and CD11b+/Ly6C+ (monocytic MDSCs (mMDSCs)) cells in prostate tumors. The temporal dynamics of tumor-infiltrating myeloid cells were further profiled and showed that pMDSC and mMDSC abundances were 1.6 and 5.7-fold higher, respectively, in older mice with late-stage locally invasive adenocarcinomas (AdCa) compared to younger mice with early-stage prostatic intraepithelial neoplasia (PIN). In both instances, pMDSCs comprised most of the leukocyte infiltrate, however, mMDSCs tended to be positively correlated with tumor burden in AdCa but not PIN. In peripheral blood, CD44+/CD62L+ immature neutrophils were associated with high tumor burden in aged mice. Treatments targeting the androgen receptor (AR) signaling further exacerbated pMDSC infiltration in tumors and was associated with resistance to second androgen receptor-targeted agent (ARTA) therapy in a model of castration resistant prostate cancer. Our findings indicate that MDSCs are a prominent population in Pten-null prostate cancer and are implicated with resistance to prostate cancer treatment. MDSCs constitute a potentially targetable population and these models serve as viable platforms to further investigate their biological activity and further evaluate novel MDSC-directed therapies. Citation Format: Marco A. De Velasco, Yurie Kura, Noriko Sako, Naomi Ando, Kazuko Sakai, Eri Banno, Shogo Adomi, Mitsuhisa Nishimoto, Takafumi Minami, Yasunori Mori, Kazutoshi Fujita, Masahiro Nozawa Nozawa, Kazuhiro Yoshimura, Kazuto Nishio, Hirotsugu Uemura. Profiling of myeloid-derived suppressor cells in Pten-deficient in prostate cancer progression [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 2877.

Abstract 1705: SPOP: An essential gene for normal and prostate tumor cells

Abstract Background: Prostate cancer (PC) is the single most common and second-most lethal cancer in men, with over 268,000 estimated cases and over 34,500 estimated deaths in the US in 2022. The Speckle-Type POZ protein (SPOP) mutant subclass of PC accounts for 10% to 15% of all primary PC cases. SPOP is an adaptor for Cullin3/Ring (CUL3-RING)-type E3 ubiquitin ligase complexes and provides substrate specificity. The Cancer Genome Atlas (TCGA) studies show that SPOP is the most frequently mutated gene in primary prostate cancer (PC). Interestingly, PC-associated SPOP mutations are always missense and occur in a heterozygous fashion. The current gap in knowledge is the lack of understanding of the role of wildtype SPOP in PC. Methods: By utilizing prostate specific SPOP knockout (KO) mice, we recently reported increased levels of AR and MYC protein and increased cellular turnover (both proliferation and apoptosis) in the prostate luminal epithelium compared to wildtype prostates. We now characterized these mice for the expression of Cre protein and SPOP mRNA at different age using immunohistochemistry and RNA in situ hybridization. Furthermore, we performed RNA-sequencing analysis in the SPOP knockout mice and matched control littermates. Moreover, we performed RNA-seq in LNCaP, LNCaP-Abl, and RWPE1 cells following SPOP inhibition via siRNA targeting SPOP. Finally, we compared our SPOP inhibition signature from in vitro cell lines and prostate specific SPOP knockout murine model to gain insights about the role of wildtype SPOP protein in the prostate epithelium. Result: Using our Spopfl/fl;PBCre+ model, we observed SPOP floxed cells are rapidly lost and the murine prostate epithelium was repopulated with SPOP wildtype carrying cells. Similarly, knockdown (KD) of SPOP through siRNA treatment in a panel of PC cell lines resulted in a significant reduction in cell viability. These observations suggest that SPOP is important for the normal prostate cell viability. Further transcriptomic profiling of SPOP KO (from transgenic murine model) as well as siSPOP treated in vitro prostate cell lines revealed a significant reduction in the transcriptional activity of the AR. Conclusion: Our data illustrate for the first time a critical role for SPOP in the growth and survival of the prostate epithelium and prostate cancer cell. Our findings further validates SPOP as a important therapeutic target for the treatment of prostate cancer. Citation Format: Kinza Rizwan, Darlene Skapura, Cammy Mason, Cristian Coarfa, Nicholas Mitsiades, Damian Young, Salma Kaochar. SPOP: An essential gene for normal and prostate tumor cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 1705.

Abstract 5151: Enzalutamide resistance results in immunosuppressive alterations in prostate tumor immune microenvironment

Abstract Background: Emerging data suggested that enzalutamide-treated prostate cancer patients with increased programmed death-ligand 1 (PD-L1) expression may benefit from anti-PD-L1 treatment. Unfortunately, the Phase III IMbassador250 trial revealed that the combination of atezolizumab (PD-L1 inhibitor) and enzalutamide failed to extend overall survival in patients with castration-resistant prostate cancer (CRPC). The mechanisms underlying treatment failure remain unknown. In this study, we investigated the regulation of immunosuppressive signaling in enzalutamide resistant prostate cancer and characterized the immune infiltrating cells in murine prostate tumors. Methods: The expression of interferon gamma-related genes was determined using qRT-PCR and/or western blotting. Androgen receptor (AR) and AR-V7 levels were downregulated using specific siRNA. Myc-CaP cells were chronically exposed to increasing concentrations of enzalutamide (5-50 μM) for &amp;gt;12 months, and the cells resistant to enzalutamide were referred to as Myc-CaP MDVR. The gene-regulating mechanisms in drug-resistant prostate cancer cells were determined by RNA sequencing analyses. Myc-CaP and Myc-CaP MDVR xenograft tumors were established in FVB mice, and tumor-infiltrating lymphocytes were isolated using Ficoll. The stained immune cells were determined by flow cytometry, and the data were analyzed using Flowjo. Results: Immune-related signaling pathways (interferon alpha/gamma response, T cell activation, and cell chemotaxis pathways) were suppressed in C4-2B MDVR cells. However, PD-L1 expression was highly upregulated and negatively regulated by AR in C4-2B MDVR cells. Enzalutamide treatment decreased CD8+ T cell but increased monocytic myeloid-derived suppressor cell (M-MDSC) population and PD-L1 expression in murine Myc-CaP tumors. Consistently, chemotaxis and immune response-regulating signaling pathways were suppressed, and PD-L1 expression was increased in enzalutamide-resistant Myc-CaP MDVR cells. Notably, MDSC populations were significantly increased in Myc-CaP MDVR orthotopic tumors compared with those in Myc-CaP parental tumors. Co-culturing bone marrow cells with Myc-CaP MDVR cells significantly promoted MDSC differentiation and polarized macrophages from the M1 to M2 phase. Conclusions: Immunosuppressive signaling is activated in enzalutamide resistant prostate cancer cells. The activated immune-related signatures involved in T cells, MDSC, and macrophages may reduce the efficacy of immune checkpoint inhibitors in enzalutamide-resistant prostate cancer. Grant Support: This work was supported in part by grants NIH/NCI R37CA249108 (C, Liu) and R01CA251253 (C, Liu). Citation Format: Pengfei Xu, Joy C. Yang, Bo Chen, Christopher Nip, Jonathan E. Van Dyke, Christopher P. Evans, William J. Murphy, Chengfei Liu. Enzalutamide resistance results in immunosuppressive alterations in prostate tumor immune microenvironment. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 5151.

Abstract 5281: Role of TMEM97/Sigma-2 receptor in prostate cancer

Abstract Introduction: Prostate cancer is the most common cancer in men. About one in eight men will be diagnosed with prostate cancer in his lifetime, and one in forty-one men will die of it. Sigma 2 receptor (σ2R) has been implicated in carcinogenesis including prostate cancer. Its molecular identity remained elusive until 2017 that transmembrane protein 97 (TMEM97) was identified as the bona fide sigma 2 receptor. Past studies have shown that σ2R is highly expressed in various mammalian tumors and TMEM97 works as an oncogene in different cancers. In this study, we examined the expression of TMEM97/σ2 receptor in prostate cancer, evaluated its interaction with androgen receptor (AR), and determined its functions in tumor cell growth and progression. Methods: The expression of TMEM97 at mRNA levels and its association with clinical parameters were queried in the TCGA database using cBioportal. Its expression pattern in prostate tumor tissues was examined by IHC using a commercially validated antibody. A correlation analysis of TMEM97 with AR was conducted utilizing both PCTA and TCGA databases. To determine its roles in tumor proliferation, clonogenicity, and responses to hormone deprivation and chemo-therapy, TMEM97 expression was overexpressed and knocked down, and the subsequent effects were determined by cell proliferation MTS assay, colony formation assay with and without enzalutamide treatment. A xenograft model of nu/nu mice was used to assess the impact of TMEM97 overexpression on tumor formation and growth in vivo. The effects of TMEM97 overexpression and knockdown on AR transcriptional activity were examined. Results: A significant elevation of TMEM97 mRNA levels, with a Z-Score above 2.0, was found in 5% of the prostate cancer patients and was associated with significantly reduced survival. TMEM97 protein was detected in prostate tumor tissues of all stages and grades. Its expression is highly correlated with the expression of AR in prostate cancer. Prostate cancer cells with TMEM97 overexpression showed growth advantage over the control cells both in normal culture conditions and also under treatment of enzalutamide. TMEM97 knockdown weakened growth, and sensitized castration resistant 22Rv1 toward enzalutamide, which is linked to the decrease of AR-V7. TMEM97 overexpression in LNCaP cells also significantly increased tumor formation and growth when xenografted into nu/nu mice. In LNCaP cells, TMEM97 overexpression elevated AR target genes expression. Parallelly, these genes were all significantly downregulated in TMEM97 knockdown cells. A compound with a high affinity to TMEM97 was found to induce apoptosis of prostate cancer cells with preferential degradation of AR-V7. Conclusion: The observations suggest that TMEM97/sigma2 receptor plays a role in prostate tumor cell proliferation and the increased expression of TMEM97 can elevate AR activity and stimulate prostate tumor formation and growth. Citation Format: Xiangwei Fang, Yuanqin Zhang, Jiuhui Wang, Paul Cacioppo, Michael Crider, Daotai Nie. Role of TMEM97/Sigma-2 receptor in prostate cancer. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 5281.

MP20-11 ENZALUTAMIDE RESISTANCE RESULTS IN IMMUNOSUPPRESSIVE ALTERATIONS IN PROSTATE TUMOR IMMUNE MICROENVIRONMENT

You have accessJournal of UrologyCME1 Apr 2023MP20-11 ENZALUTAMIDE RESISTANCE RESULTS IN IMMUNOSUPPRESSIVE ALTERATIONS IN PROSTATE TUMOR IMMUNE MICROENVIRONMENT Pengfei Xu, Joy C. Yang, Bo Chen, Christopher Nip, Jonathan E Van Dyke, Christopher P. Evans, William J. Murphy, and Chengfei Liu Pengfei XuPengfei Xu More articles by this author , Joy C. YangJoy C. Yang More articles by this author , Bo ChenBo Chen More articles by this author , Christopher NipChristopher Nip More articles by this author , Jonathan E Van DykeJonathan E Van Dyke More articles by this author , Christopher P. EvansChristopher P. Evans More articles by this author , William J. MurphyWilliam J. Murphy More articles by this author , and Chengfei LiuChengfei Liu More articles by this author View All Author Informationhttps://doi.org/10.1097/JU.0000000000003245.11AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookLinked InTwitterEmail Abstract INTRODUCTION AND OBJECTIVE: Emerging data suggested that enzalutamide-treated prostate cancer patients with increased programmed death-ligand 1 (PD-L1) expression may benefit from anti-PD-L1 treatment. Unfortunately, the Phase III IMbassador250 trial revealed that the combination of atezolizumab (PD-L1 inhibitor) and enzalutamide failed to extend overall survival in patients with castration-resistant prostate cancer (CRPC). The mechanisms underlying treatment failure remain unknown. In this study, we investigated the regulation of immunosuppressive signaling in enzalutamide resistant prostate cancer and characterized the immune infiltrating cells in murine prostate tumors. METHODS: The expression of interferon gamma-related genes was determined using qRT-PCR and/or western blotting. Androgen receptor (AR) and AR-V7 levels were downregulated using specific siRNA. Myc-CaP cells were chronically exposed to increasing concentrations of enzalutamide (5-50 μM) for >12 months, and the cells resistant to enzalutamide were referred to as Myc-CaP MDVR. The gene-regulating mechanisms in drug-resistant prostate cancer cells were determined by RNA sequencing analyses. Myc-CaP and Myc-CaP MDVR xenograft tumors were established in FVB mice, and tumor-infiltrating lymphocytes were isolated using Ficoll. The stained immune cells were determined by flow cytometry, and the data were analyzed using Flowjo. RESULTS: Immune-related signaling pathways (interferon alpha/gamma response, T cell activation, and cell chemotaxis pathways) were suppressed in C4-2B MDVR cells (p<0.001). However, PD-L1 expression was highly upregulated and negatively regulated by AR in C4-2B MDVR cells. Enzalutamide treatment decreased CD8+ T cell (14.8% vs. 10.3%, p<0.05) but increased monocytic myeloid-derived suppressor cell (M-MDSC) population (23.0% vs. 34.2%, p<0.05) and PD-L1 expression in murine Myc-CaP tumors. Consistently, chemotaxis and immune response-regulating signaling pathways were suppressed, and PD-L1 expression was increased in enzalutamide-resistant Myc-CaP MDVR cells. Notably, MDSC populations were significantly increased in Myc-CaP MDVR orthotopic tumors compared with those in Myc-CaP parental tumors (4.0% vs. 1.6%, p<0.01). Co-culturing bone marrow cells with Myc-CaP MDVR cells significantly promoted MDSC differentiation and polarized macrophages from the M1 to M2 phase. CONCLUSIONS: Immunosuppressive signaling is activated in enzalutamide resistant prostate cancer cells. The activated immune-related signatures involved in T cells, MDSC, and macrophages may reduce the efficacy of immune checkpoint inhibitors in enzalutamide-resistant prostate cancer. Source of Funding: This work was supported in part by grants NIH/NCI R37CA249108 (C, Liu) and R01CA251253 (C, Liu) © 2023 by American Urological Association Education and Research, Inc.FiguresReferencesRelatedDetails Volume 209Issue Supplement 4April 2023Page: e279 Advertisement Copyright & Permissions© 2023 by American Urological Association Education and Research, Inc.MetricsAuthor Information Pengfei Xu More articles by this author Joy C. Yang More articles by this author Bo Chen More articles by this author Christopher Nip More articles by this author Jonathan E Van Dyke More articles by this author Christopher P. Evans More articles by this author William J. Murphy More articles by this author Chengfei Liu More articles by this author Expand All Advertisement PDF downloadLoading ...

Selected Articles from This Issue

Highlights| April 01 2023 Selected Articles from This Issue Author & Article Information Online ISSN: 1557-3125 Print ISSN: 1541-7786 ©2023 American Association for Cancer Research2023American Association for Cancer Research Mol Cancer Res (2023) 21 (4): 291. https://doi.org/10.1158/1541-7786.MCR-21-4-HI Related Content A commentary has been published: Multi-substrate Metabolic Tracing Reveals Marked Heterogeneity and Dependency on Fatty Acid Metabolism in Human Prostate Cancer A commentary has been published: Targeting ULK1 Decreases IFNγ-Mediated Resistance to Immune Checkpoint Inhibitors A commentary has been published: Evolutionary Characteristics and Immunologic Divergence of Lung and Brain Metastasis Lesions in NSCLC View more A commentary has been published: Scaffolding Protein Connector Enhancer of Kinase Suppressor of Ras 1 (CNKSR1) Regulates MAPK Inhibition Responsiveness in Pancreas Cancer via Crosstalk with AKT Signaling View less Views Icon Views Article contents Figures & tables Video Audio Supplementary Data Peer Review Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Cite Icon Cite Search Site Article Versions Icon Versions Version of Record April 1 2023 Citation Selected Articles from This Issue. Mol Cancer Res 1 April 2023; 21 (4): 291. https://doi.org/10.1158/1541-7786.MCR-21-4-HI Download citation file: Ris (Zotero) Reference Manager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest Search Advanced Search While metabolic reprogramming is an established hallmark of cancer, specific metabolic pathways that are altered in human prostate tumors — as well as the degree of heterogeneity to which they are altered among tumors — remain largely unsolved. In their study, Fidelito and colleagues performed radiometric and stable isotope tracing using serially transplantable patient-derived xenografts (PDXs) to define the metabolic landscape of human prostate tumors. The authors found that the PDXs oxidize diverse substrates including glucose, glutamine, lactate, and fatty acids, and to a greater degree than do benign prostate tissues. Isotope tracing revealed that prostate tumor cells tend to use glucose for acetyl-CoA production, and process glutamine via the tricarboxylic acid cycle. Notably, substrate utilization exhibited marked heterogeneity among samples, and, correspondingly, responses to pharmacologic inhibitors targeting diverse metabolic pathways varied among samples. However, adenocarcinoma, neuroendocrine, primary, and metastatic PDX-derived organoids all displayed dependencies on fatty acid uptake and... You do not currently have access to this content.

Polyphotosensitizer-Based Nanoparticles with Michael Addition Acceptors Inhibiting GST Activity and Cisplatin Deactivation for Enhanced Chemotherapy and Photodynamic Immunotherapy.

Glutathione S-transferase (GST), which is a key enzyme in the conjugation reaction of glutathione (GSH), is overexpressed in cancer cells, leading to cisplatin deactivation and ultimately drug resistance. In addition, many tumors are immune "cold tumors," limiting the application of immune checkpoint inhibitors. Herein, a reactive oxygen species (ROS)-responsive polyphotosensitizer-based nanoparticle (NP2) with Michael addition acceptors inhibiting GST activity and cisplatin deactivation is designed. Under the 808nm light irradiation, on the one hand, the Michael addition acceptor in NP2 can react with GST and inhibit its activity, thereby decreasing the GSH conjugation and reducing the GSH-mediated deactivation of cisplatin and improving its chemotherapeutic effect. On the other hand, NP2+L induces more ROS production in prostate tumor cells, which can further induce type II immunogenic cell death (ICD) and stimulate a stronger antitumor immune response. It is found that NP2 under the 808nm light irradiation (NP2+L) can increase PD-L1 expression on the surface of prostate cancer cells. Subsequently, NP2+L combined with PD-L1 treatment is found to simultaneously enhance the efficacies of chemotherapy and photodynamic immunotherapy in prostate tumors, providing a new paradigm for the clinical multimodal treatment of tumors.

The APOE-TREM2 Axis Mediates Senescent Neutrophils in Prostate Cancer.

Prostate tumor cell secretion of APOE promotes senescence of TREM2+ immunosuppressive neutrophils.