Suppresses Prostate Cancer Cell Growth Research Articles

Abstract 656: A novel dual-targeting peptide HS1002 enhances anti-tumor activity via GnRH/human telomerase reverse transcriptase (hTERT) interaction in human prostate cancer cells

Abstract Human telomerase reverse transcriptase (hTERT) is overexpressed in most human cancers. hTERT is considered as an important target for cancer therapy. In the present study, a new peptide HS1002 were synthesized with sequence of pGlu-His-Trp-Ser-Tyr-Arg-Leu-Arg-Phe-Ile-Pro-NHEt based on the GnRH agonist and hTERT. The aim of this study was to evaluate HS1002 for its anticancer activity by dual-targeting to GnRH/hTERT in prostate cancer cells. Upon comparison with different prostate cancer cell lines, HS1002 exhibited highest cytotoxicity against LNCaP cells. The hTERT expression correlated with telomerase activity in LNCaP cells, was significantly inhibited by HS1002, resulting in reduction of proliferation, metastasis and increase in apoptosis. Additionally, HS1002 suppressed c-Myc and AKT/ERK pathway in LNCaP cells. In the tumor-bearing nude mice model, HS1002 significantly inhibited tumor growth and downregulated the expression of hTERT and Ki-67 in tumor tissue as evidenced by western blot and immunohistochemistry analysis, respectively. Moreover, repeated subcutaneous injection of HS1002 resulted in the reduction of both serum testosterone levels and seminal vesicle weight. HS1002 also increased cytosolic calcium influx and CRE-luciferase activity in GnRHR-overexpressing HEK293 cells compared to mock-transfected transfected cells. Furthermore, a potent cytotoxicity in LNCaP cells was exhibited by HS1002-activated peripheral blood mononuclear cell (PBMC) with interleukin (IL)-2 using LDH release assay. In addition, a flow-cytometric analysis confirmed an elevation in the production of granzyme B and IFN-γ in CD8+ T cells in the MC38 syngeneic mouse model by HS1002. These data indicate that the inhibition of hTERT expression by HS1002 suppresses prostate cancer cell growth and induced anti-cancer immunity. Therefore, HS1002 might be used as a novel therapeutic drug for prostate cancer. Citation Format: Jae Hyeon Park, Ju Ri Kim, Hwa Young Cha, Hyung Sik Kim. A novel dual-targeting peptide HS1002 enhances anti-tumor activity via GnRH/human telomerase reverse transcriptase (hTERT) interaction in human prostate cancer cells [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 656.

LSD1 inhibitor hinders the demethylation of FOXA1 to inhibit prostate cancer progression

Abnormal activation of androgen receptor (AR) occurs in prostate cancer (PC) progression and metastasis. Lysine-specific demethylase 1 (LSD1), the first demethylating enzyme, regulates AR-mediated transcriptional activity. Considering the effect of Forkhead box protein A1 (FOXA1) on the expression of AR, estrogen receptor (ER) and tumor suppressor genes, this study investigated the demethylation of FOXA1 upon treatment with LSD1 inhibitors and assessed the biological behaviors of PC cells. PC cells were cultured and infected with viruses. After transient transfection, CWR22-RV1-Cas9 cells were selected by puromycin with expression of LSD1 detected by Western blot. Apart from measurement of formaldehyde production, immunoprecipitation and chromatin immunoprecipitation (ChIP) were performed, followed by ATAC-seq detection, and Western blot. The data indicated the association between LSD1-binding sites and high levels of FOXA1. LSD1 inhibitor treatment resulted in a dramatic decline in overall FOXA1 binding, significantly reducing chromosomal accessibility and also increasing lysine-methylated FOXA1 level, but it failed to affect H3K4me2 levels at LSD1-FOXA1 occupied sites. Overexpression of LSD1-WT obtained reverse outcome. Besides, LSD1 inhibition diminished binding of FOXA1 and restored lysine-methylation of FOXA1 in methylation-deficient cells with mutant K270R. Moreover, silencing of LSD1 suppressed CWR22-RV1 tumor growth, resulting in increased H3K4me2 and decreased AR-FL/V7 gene expression. K270me is demethylated by LSD1. LSD1 inhibitor disrupts FOXA1 chromatin association, blocks FOXA1 K270-demethylation and hinders AR binding, thereby suppressing PC cell growth.

Resistomycin Suppresses Prostate Cancer Cell Growth by Instigating Oxidative Stress, Mitochondrial Apoptosis, and Cell Cycle Arrest

Globally, prostate cancer is among the most threatening and leading causes of death in men. This study, therefore, aimed to search for an ideal antitumor strategy with high efficacy, low drug resistance, and no or few adverse effects. Resistomycin is a natural antibiotic derived from marine actinomycetes, and it possesses various biological activities. Prostate cancer cells (PC3) were treated with resistomycin (IC12.5: 0.65 or IC25: 1.3 µg/mL) or 5-fluorouracil (5-FU; IC25: 7 µg/mL) for 24 h. MTT assay and flow cytometry were utilized to assess cell viability and apoptosis. Oxidative stress, apoptotic-related markers, and cell cycle were also assessed. The results revealed that the IC50 of resistomycin and 5-FU on PC3 cells were 2.63 µg/mL and 14.44 µg/mL, respectively. Furthermore, treated cells with the high dose of resistomycin showed an increased number of apoptotic cells compared to those treated with the lower dose. Remarkable induction of reactive oxygen species generation and lactate dehydrogenase (LDH) leakage with high malondialdehyde (MDA), carbonyl protein (CP), and 8-hydroxyguanosine (8-OHdG) contents were observed in resistomycin-treated cells. In addition, marked declines in glutathione (GSH), superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx) in PC3 cells subjected to resistomycin therapy were observed. Resistomycin triggered observable cell apoptosis by increasing Bax, caspase-3, and cytosolic cytochrome c levels and decreasing Bcl-2 levels. In addition, notable downregulation of proliferating cell nuclear antigen (PCNA) and cyclin D1 was observed in resistomycin-treated cancerous cells. According to this evaluation, the antitumor potential of resistomycin, in a concentration-dependent manner, in prostate cancer cells was achieved by triggering oxidative stress, mitochondrial apoptosis, and cell cycle arrest in cancer cells. In conclusion, our investigation suggests that resistomycin can be considered a starting point for developing new chemotherapeutic agents for human prostate cancer.

Exploring the role of differentially expressed metabolic genes and their mechanisms in bone metastatic prostate cancer.

Approximately 10-20% of patients diagnosed with prostate cancer (PCa) evolve into castration-resistant prostate cancer (CRPC), while nearly 90% of patients with metastatic CRPC (mCRPC) exhibit osseous metastases (BM). These BM are intimately correlated with the stability of the tumour microenvironment. This study aspires to uncover the metabolism-related genes and the underlying mechanisms responsible for bone metastatic prostate cancer (BMPCa). Gene Expression Omnibus (GEO) and The Cancer Genome Atlas (TCGA) datasets of PCa and BM were analyzed through R Studio software to identify differentially expressed genes (DEGs). The DEGs underwent functional enrichment via Kyoto Encyclopedia of Genes and Genomes (KEGG) and Gene Ontology (GO), with key factors screened by a random forest utilized to establish a prognostic model for PCa. The study explored the relationship between DEGs and the stability of the immune microenvironment. The action and specificity of CRISP3 in PCa was validated through western blot analysis, CCK-8 assay, scratch assay, and cellular assay. The screening of GEO and TCGA datasets resulted in the identification of 199 co-differential genes. Three DEGs, including DES, HBB, and SLPI, were selected by random forest classification model and cox regression model. Immuno-infiltration analysis disclosed that a higher infiltration of naïve B cells and resting CD4 memory T cells occurred in the high-expression group of DES, whereas infiltration of resting M1 macrophages and NK cells was greater in the low-expression group of DES. A significant infiltration of neutrophils was observed in the high-expression group of HBB, while greater infiltration of gamma delta T cells and M1 macrophages was noted in the low-expression group of HBB. Resting dendritic cells, CD8 T cells, and resting T regulatory cells (Tregs) infiltrated significantly in the high-expression group of SLPI, while only resting mast cells infiltrated significantly in the low-expression group of SLPI. CRISP3 was established as a critical gene in BMPCa linked to DES expression. Targeting CRISP3, d-glucopyranose may impact tumour prognosis. During the mechanistic experiments, it was established that CRISP3 can advance the proliferation and metastatic potential of PCa by advancing epithelial-to-mesenchymal transition (EMT). By modulating lipid metabolism and maintaining immunological and microenvironmental balance, DES, HBB, and SLPI suppress prostate cancer cell growth. The presence of DES-associated CRISP3 is a harbinger of unfavorable outcomes in prostate cancer and may escalate tumor proliferation and metastatic capabilities by inducing epithelial-mesenchymal transition.

AMPK targets a proto-oncogene TPD52 (isoform 3) expression and its interaction with LKB1 suppress AMPK-GSK3β signaling axis in prostate cancer.

Tumor protein D52 (TPD52) is a proto-oncogene overexpressed in prostate cancer (PCa) due to gene amplification and it is involved in the cancer progression of many cancers including PCa. However, the molecular mechanisms underlying the role of TPD52 in cancer progression are still under investigation. In this study, we report that the activation of AMP-activated protein kinase (AMPK) by AICAR (5-Aminoimidazole-4-carboxamide ribonucleotide) inhibited the LNCaP and VCaP cells growth by silencing TPD52 expression. Activation of AMPK inhibited the proliferation and migration of LNCaP and VCaP cells. Interestingly, AICAR treatment to LNCaP and VCaP cells led to the downregulation of TPD52 via activation of GSK3β by a decrease of inactive phosphorylation at Ser9. Moreover, in AICAR treated LNCaP cells, inhibition of GSK3β by LiCl attenuated downregulation of TPD52 indicating that AICAR acts via GSK3β. Furthermore, we found that TPD52 interacts with serine/threonine kinase 11 or Liver kinase B1 (LKB1) a known tumor suppressor and an upstream kinase for AMPK. The molecular modeling and MD simulations indicates that the interaction between TPD52 and LKB1 leads to inhibition of the kinase activity of LKB1 as its auto-phosphorylation sites were masked in the complex. Consequently, TPD52-LKB1 interaction may lead to inactivation of AMPK. Moreover, overexpression of TPD52 is found to be responsible for the reduction of pLKB1 (Ser428) and pAMPK (Thr172). Therefore, TPD52 may be playing its oncogenic role via suppressing the AMPK activation. Altogether, our results revealed a new mechanism of PCa progression in which TPD52 overexpression inhibits AMPK activation by interacting with LKB1. These results support that the use of AMPK activators and/or small molecules that could disrupt the TPD52-LKB1 interaction might be useful to suppress PCa cell growth. TPD52 interacts LKB1 and interfere with activation of AMPK in PCa cells.

Soy Isoflavones Induce Cell Death by Copper-Mediated Mechanism: Understanding Its Anticancer Properties

Cancer incidence varies around the globe, implying a relationship between food and cancer risk. Plant polyphenols are a class of secondary metabolites that have recently attracted attention as possible anticancer agents. The subclass of polyphenols, known as isoflavones, includes genistein and daidzein, which are present in soybeans and are regarded as potent chemopreventive agents. According to epidemiological studies, those who eat soy have a lower risk of developing certain cancers. Several mechanisms for the anticancer effects of isoflavones have been proposed, but none are conclusive. We show that isoflavones suppress prostate cancer cell growth by mobilizing endogenous copper. The copper-specific chelator neocuproine decreases the apoptotic potential of isoflavones, whereas the iron and zinc chelators desferroxamine mesylate and histidine do not, confirming the role of copper. Reactive oxygen species (ROS) scavengers reduce isoflavone-induced apoptosis in these cells, implying that ROS are cell death effectors. Our research also clearly shows that isoflavones interfere with the expression of the two copper transporter genes, CTR1 and ATP7A, in cancerous cells. Copper levels are widely known to be significantly raised in all malignancies, and we confirm that isoflavones can target endogenous copper, causing prooxidant signaling and, eventually, cell death. These results highlight the importance of copper dynamics within cancer cells and provide new insight into the potential of isoflavones as cancer-fighting nutraceuticals.

Targeted PEGylated Chitosan Nano-complex for Delivery of Sodium Butyrate to Prostate Cancer: An In Vitro Study.

Introduction: Cancer remains a challenging issue against human health throughout the world; As a result, introducing novel approaches would be beneficial for cancer treatment. In this research, sodium butyrate (Sb) is one of the effective anti-cancer therapeutics (also a potent survival factor for normal cells) that was used for prostate cancer suppression in the platform of modified chitosan (CS) nano-complex (polyethylene glycol (PEG)-folic acid (FA)-Sb-CS). Methods: Different analytical devices including Fourier transform infrared, dynamic light scattering, high-performance liquid chromatography, scanning electron microscopy, and transmission electron microscopy were applied for the characterization of synthetics. On the other hand, biomedical tests including cell viability assay, molecular and functional assay of apoptosis/autophagy pathways, and cell cycle arrest analysis were potentially implemented on human PC3 (folate receptor-negative prostate cancer) and DU145 (folate receptor-positive prostate cancer) and HFF-1 normal cell lines. Results: The quality of the syntheses was effectively verified, and the size range from 140 to 170 nm was determined for the PEG-CS-FA-Sb sample. Also, 75 ± 5% of drug entrapment efficiency with controlled drug release manner (Sb release of 54.21% and 74.04% for pHs 7.4 and 5.0) were determined for nano-complex. Based on MTT results, PEG-CS-FA-Sb has indicated 72.07% and 33.53% cell viability after 24 h of treatment with 9 mM on PC3 and DU145 cell lines, respectively, which is desirable anti-cancer performance. The apoptotic and autophagy genes overexpression was 15-fold (caspase9), 2.5-fold (BAX), 11-fold (ATG5), 2-fold (BECLIN1), and 3-fold (mTORC1) genes in DU145 cancer cells. More than 50% of cell cycle arrest and 45.05% of apoptosis were obtained for DU145 cancer cells after treatment with nano-complex. Conclusion: Hence, the synthesized Sb-loaded nano-complex could specifically suppress prostate cancer cell growth and induce apoptosis and autophagy in the molecular and cellular phases.

Biphasic transcriptional and posttranscriptional regulation of MYB by androgen signaling mediates its growth control in prostate cancer

MYB, a proto-oncogene, is overexpressed in prostate cancer (PCa) and promotes its growth, aggressiveness, and resistance to androgen-deprivation therapy. Here, we examined the effect of androgen signaling on MYB expression and delineated the underlying molecular mechanisms. Paralleling a dichotomous effect on growth, low-dose androgen induced MYB expression at both transcript and protein levels, whereas it was suppressed in high-dose androgen-treated PCa cells. Interestingly, treatment with both low- and high-dose androgen transcriptionally upregulated MYB by increasing the binding of androgen receptor to the MYB promoter. In a time-course assay, androgen induced MYB expression at early time points followed by a sharp decline in high-dose androgen-treated cells due to decreased stability of MYB mRNA. Additionally, profiling of MYB-targeted miRNAs demonstrated significant induction of miR-150 in high-dose androgen-treated PCa cells. We observed a differential binding of androgen receptor on miR-150 promoter with significantly greater occupancy recorded in high-dose androgen-treated cells than those treated with low-dose androgen. Functional inhibition of miR-150 relieved MYB suppression by high-dose androgen, while miR-150 mimic abolished MYB induction by low-dose androgen. Furthermore, MYB-silencing or miR-150 mimic transfection suppressed PCa cell growth induced by low-dose androgen, whereas miR-150 inhibition rescued PCa cells from growth repression by high-dose androgen. Similarly, we observed that MYB silencing suppressed the expression of androgen-responsive, cell cycle-related genes in low-dose androgen-treated cells, while miR-150 inhibition increased their expression in cells treated with high-dose androgen. Overall, these findings reveal novel androgen-mediated mechanisms of MYB regulation that support its biphasic growth control in PCa cells.

PD07-02 TARGETING WNT5A/FZD2 SIGNALING OVERCOMES RESISTANCE TO ENZALUTAMIDE IN ADVANCED PROSTATE CANCER

You have accessJournal of UrologyCME1 May 2022PD07-02 TARGETING WNT5A/FZD2 SIGNALING OVERCOMES RESISTANCE TO ENZALUTAMIDE IN ADVANCED PROSTATE CANCER Shu Ning, Chengfei Liu, Wei Lou, Alan Lombard, Leandro D'Abronzo, Aiming Yu, Christopher Evans, and Allen Gao Shu NingShu Ning More articles by this author , Chengfei LiuChengfei Liu More articles by this author , Wei LouWei Lou More articles by this author , Alan LombardAlan Lombard More articles by this author , Leandro D'AbronzoLeandro D'Abronzo More articles by this author , Aiming YuAiming Yu More articles by this author , Christopher EvansChristopher Evans More articles by this author , and Allen GaoAllen Gao More articles by this author View All Author Informationhttps://doi.org/10.1097/JU.0000000000002526.02AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookLinked InTwitterEmail Abstract INTRODUCTION AND OBJECTIVE: Androgen receptor (AR) blockade using antiandrogens is a mainstay for the treatment of castration resistant prostate cancer (CRPC). Unfortunately, drug resistance occurs frequently due to mechanisms that are not completely understood. Wnt5a, a representative ligand of non-canonical Wnt signaling, is expressed in circulating tumor cells from CRPC patients treated with enzalutamide. FZD2, the cognate frizzled receptor for Wnt5a, is the most commonly co-upregulated non-canonical Wnt receptor in prostate cancer. Here we determine the contribution of non-canonical Wnt5a/FZD2 to enzalutamide treatment resistance, and explore the potential of targeting Wnt5a/FZD2 to overcome antiandrogen resistance in castration resistant prostate cancer. METHODS: Wnt5a/FZD2 expression was examined in enzalutamide resistant C4-2B MDVR cells. Wnt5a and FZD2 expression were modulated using specific siRNAs. Cell growth, colony formation, migration and invasion were determined in vitro. RNA sequencing was analyzed on C4-2B MDVR cells with WNT5a/FZD2 knocked down; gene expression of non-canonical Wnt signaling, AR and AR-V7 signature genes were analyzed. A novel RNA bioengineered Wnt5a siRNA (tRNA-siWnt5A) was developed to target Wnt5a/FZD2 signaling. The effect of tRNA-siWnt5a on tumor growth and sensitivity to enzalutamide was evaluated in vitro and in vivo. RESULTS: Wnt5a and FZD2 are highly co-upregulated in CRPC patients and enzalutamide resistant C4-2B MDVR cells compared to parental C4-2B cells. Knocking down Wnt5a and FZD2 abrogates the increase of full-length AR and AR variant expression and diminishes the enrichment of genes involved in the non-canonical Wnt signaling pathway. Blocking Wnt5a and FZD2 using specific siRNAs suppresses prostate cancer cell growth, colony formation, migration and invasion. Wnt5a and FZD2 knockdown with siRNA resensitized C4-2B MDVR cells to enzalutamide treatment. Targeting Wnt5a using the bioengineered tRNA-siWnt5A inhibited the growth of enzalutamide resistant prostate cancer cells and resensitized cells to enzalutamide in vitro, and resistant CRPC LuCaP35CR PDX tumor growth in vivo. CONCLUSIONS: Our studies suggest that Wnt5a/FZD2 confers enzalutamide resistance and prostate cancer survival and proliferation. Targeting the non-canonical Wnt5a/FZD2 pathway suppresses tumors expressing high level of Wnt5a and FZD2, not only overcoming resistance but potentiating anti-tumor effects of enzalutamide in CRPC patients. Source of Funding: CA250082, CA 225836, DOD PC180180 © 2022 by American Urological Association Education and Research, Inc.FiguresReferencesRelatedDetails Volume 207Issue Supplement 5May 2022Page: e98 Advertisement Copyright & Permissions© 2022 by American Urological Association Education and Research, Inc.MetricsAuthor Information Shu Ning More articles by this author Chengfei Liu More articles by this author Wei Lou More articles by this author Alan Lombard More articles by this author Leandro D'Abronzo More articles by this author Aiming Yu More articles by this author Christopher Evans More articles by this author Allen Gao More articles by this author Expand All Advertisement PDF DownloadLoading ...

Palmitic acid inhibits prostate cancer cell proliferation and metastasis by suppressing the PI3K/Akt pathway

AimsProstate cancer is one of the most frequent causes of cancer death in men worldwide, and novel drugs for prostate cancer therapies are still being developed. Palmitic acid is a common saturated long-chain fatty acid that is known to exhibit anti-inflammatory and metabolic regulatory effects and antitumor activities in several types of tumors. The present study aims to explore the antiproliferative and antimetastatic activities of palmitic acid on human prostate cancer cells and the underlying mechanism. Main methodsMTT and colony formation assays were utilized to determine the antiproliferative effect of palmitic acid. Cell metastasis was evaluated by wound healing, Transwell migration and invasion assay. The in vivo anticancer effect was assessed by a nude mouse xenograft model of prostate cancer. The involved molecular mechanisms were investigated by flow cytometry and Western blot analysis. Key findingsPalmitic acid significantly suppressed prostate cancer cell growth in vitro and in vivo. Treatment with palmitic acid induced G1 phase arrest, which was associated with downregulation of cyclin D1 and p-Rb and upregulation of p27. In addition, palmitic acid could inhibit prostate cancer cell metastasis, in which suppression of PKCζ and p-Integrinβ1 and an increase in E-cadherin expression might be involved. Furthermore, a mechanistic study indicated that palmitic acid inhibited the key molecules of the PI3K/Akt pathway to block prostate cancer proliferation and metastasis. SignificanceOur findings suggested the antitumor potential of palmitic acid for prostate cancer by targeting the PI3K/Akt pathway.

Total Flavonoids of Litchi Seed Attenuate Prostate Cancer Progression Via Inhibiting AKT/mTOR and NF-kB Signaling Pathways.

Litchi seeds have been traditionally used in Chinese herbal formula for urologic neoplasms including prostate cancer (PCa). However, the effective components of Litchi seeds and the mechanisms of their actions on PCa cell growth and metastasis remain unclear. In this study, we investigated the effects and molecular mechanisms of the Total Flavonoid of Litchi Seed (TFLS) in PCa PC3 and DU145 cell lines. We found that TFLS significantly inhibited the PCa cell proliferation, induced apoptosis, and prevented cell migration and invasion. Furthermore, we observed that TFLS upregulated the expression of epithelial biomarker E-cadherin and downregulated mesenchymal biomarker Vimentin. TFLS also increased the expression of cleaved-PRAP and Bax, and decreased the expression of Bcl-2 in both PC3 and DU145 cells. Besides, TFLS inhibited AKT signaling pathway by reducing the phosphorylation of AKT and activities of downstream signal transducers including mTOR, IκBα and NF-kB. Finally, TFLS treated mice exhibited a significant decrease in tumor size without toxicity in major organs in vivo. These results indicated that TFLS could suppress PCa cell growth in vivo and inhibit PCa cell proliferation and metastasis in vitro through induction of apoptosis and phenotypic reversal of EMT, which may be achieved by inhibiting the AKT/mTOR and NF-κB signaling pathways. Taken together, our data provide new insights into the role of TFLS as a novel potent anti-cancer agent for the treatment of PCa.

Functionalized Selenium Nanotherapeutics Synergizes With Zoledronic Acid to Suppress Prostate Cancer Cell Growth Through Induction of Mitochondria-Mediated Apoptosis and Cell Cycle S Phase Arrest.

The use of established drugs in new therapeutic applications has great potential for the treatment of cancers. Nanomedicine has the advantages of efficient cellular uptake and specific cell targeting. In this study, we investigate using lentinan-functionalized selenium nanoparticles (LET-SeNPs) for the treatment of prostate cancer (PCa). We used assays to demonstrate that a combination of LET-SeNPs and zoledronic acid (ZOL) can reduce PCa cell viability in vitro. Stability and hemocompatibility assays were used to determine the safety of the combination of LET-SeNPs and ZOL. The localization of LET-SeNPs was confirmed using fluorescence microscopy. JC-1 was used to measure the mitochondrial membrane potential, while the cellular uptake, cell cycle and apoptosis were evaluated by flow cytometry. Finally, cell migration and invasion assays were used to evaluate the effects of the combination treatment on cell migration and invasion. Under optimized conditions, we found that LET-SeNPs has good stability. The combination of LET-SeNPs and ZOL can effectively inhibit metastatic PCa cells in a concentration-dependent manner, as evidenced by cytotoxicity testing, flow cytometric analysis, and mitochondria functional test. The enhanced anti-cancer effect of LET-SeNPs and ZOL may be related to the regulation of BCL2 family proteins that could result in the release of cytochrome C from the inner membranes of mitochondria into the cytosol, accompanied by induction of cell cycle arrest at the S phase, leading to irreversible DNA damage and killing of PCa cells. Collectively, the results of this study suggest that the combination of SeNPs and ZOL can successfully inhibit the growth of PCa cells.

Rutaecarpine administration inhibits cancer cell growth in allogenic TRAMP-C1 prostate cancer mice correlating with immune balance in vivo

BackgroundRutaecarpine (Rut) is a plant alkaloid abundant in Euodia ruticarpa which is a Chinese herbal medicine used for treating various cancers. However, the Rut administration effect on prostate cancer in vivo remains unclear. AimIn the present study we established an allogenic TRAMP-C1 prostate cancer mouse model to evaluate the Rut administration effect and mechanism in vivo. MethodsTo unravel the Rut administration effect on prostate cancer in vivo, C57BL/6J male mice (8 weeks old) were randomly grouped (n = 9), subcutaneously loaded with TRAMP-C1 prostate cancer cells and immediately given daily by gavage with Rut dissolved in soybean oil at 7 mg (low dose), 35 mg (medium dose), and 70 mg/kg b.w./day (high dose) for successive 39 days. ResultsRut administration significantly and dose-dependently reduced both tumor volume and solid prostate cancer weight in allogenic TRAMP-C1 male mice. Rut administration markedly increased (TNF-α+IFN-γ) (Th1-)/IL-10 (Th2-) cytokine secretion ratios by splenocytes and TNF-α (M1-)/IL-10 (M2-) cytokine secretion ratios by macrophages as compared to those of dietary control group, suggesting that Rut administration in vivo regulates the immune balance toward Th1- and M1-polarized characteristics. Decreased CD19+, CD4+ and CD8+ lymphocytes in the peripheral blood of allogenic TRAMP-C1 mice were significantly elevated by Rut administration. Tumor weights positively correlated with TNF-α secretions by splenocytes, suggesting that there is a tumor cachexia in the tumor-bearing mice. Tumor weights negatively correlated with IgG (Th1-antibody) levels in the sera, suggesting that Th1-polarized immune balance may inhibit prostate cancer cell growth. ConclusionsOur results evidenced that Rut administration suppresses prostate cancer cell growth in mice subcutaneously loaded with TRAMP-C1 cells and correlated the anti-cancer effects with Th1-polarized immune balance in vivo.

Phage display screening identifies a prostate specific antigen (PSA)–/lo prostate cancer cell specific peptide to retard castration resistance of prostate cancer

Patients with prostate cancer (PCa) will eventually progress to castrate-resistant prostate cancer (CRPC) after androgen deprivation therapy (ADT) treatment. Prostate-specific antigen (PSA)−/lo cells which harbor self-renewing long-term tumor-propagating cells that can be enriched using ALDH+CD44+α2β1+ and can initiate tumor development may represent a critical source of CRPC cells. Our purpose was to find a peptide that specifically targets PSA−/lo PCa cells to retard the development of CRPC. PSA+ and PSA−/lo cells were successfully separated from LNCaP xenograft tumors after prostate- PSAP-GFP vector infection and FACS. A variety of PSA−/lo cells specifically targeting peptide (named as “TAP1” targeted affinity peptide 1) was identified by using phage display library screening. The highest binding rate in TAP1 binding cell subpopulations are identified to be among ALDH+CD44+CXCR4+CD24+ cells. TAP1 significantly inhibited PCa growth both in vitro and in vivo. TAP1 significantly improved the anti-proliferation effect of the anti-androgens (Charcoal dextran-stripped serum (CDSS)+Bicalutamide, Enzalutamide) and chemotherapeutic agents (Abiraterone, Docetaxel, Etoposide) in vitro. TAP1 treatment shortens the length of telomeres in ALDH+CD44+CXCR4+CD24+ cells and significantly reduces the expression of Homeobox B9 (HOXB9) and TGF-β2. In conclusion, PSA−/lo PCa cell-specific targeting peptide (TAP1) that suppressed PCa cell growth both in vitro and in vivo and improved the drug sensitivities of anti-androgens and chemotherapeutic agents at least through shortening the length of telomere and reducing the expression of HOXB9 and TGF-β2. Therapeutic peptides that specifically target prostate cancer stem cell might be a very valuable and promising approach to overcome chemoresistance and prevent recurrence in patients with PCa.

Steroid Sulfatase Stimulates Intracrine Androgen Synthesis and is a Therapeutic Target for Advanced Prostate Cancer.

Most patients with prostate cancer receiving enzalutamide or abiraterone develop resistance. Clinical evidence indicates that serum levels of dehydroepiandrosterone sulfate (DHEAS) and biologically active DHEA remain in the high range despite antiandrogen treatment. The conversion of DHEAS into DHEA by steroid sulfatase (STS) may contribute to sustained intracrine androgen synthesis. Here, we determine the contribution of STS to treatment resistance and explore the potential of targeting STS to overcome resistance in prostate cancer. STS expression was examined in patients and cell lines. In vitro, STS activity and expression were modulated using STS-specific siRNA or novel STS inhibitors (STSi). Cell growth, colony formation, androgen production, and gene expression were examined. RNA-sequencing analysis was conducted on VCaP cells treated with STSi. Mice were treated with STSis with or without enzalutamide to determine their effects in vivo. STS is overexpressed in patients with castration-resistant prostate cancer (CRPC) and resistant cells. STS overexpression increases intracrine androgen synthesis, cell proliferation, and confers resistance to enzalutamide and abiraterone. Inhibition of STS using siRNA suppresses prostate cancer cell growth. Targeting STS activity using STSi inhibits STS activity, suppresses androgen receptor transcriptional activity, and reduces the growth of resistant C4-2B and VCaP prostate cancer cells. STSis significantly suppress resistant VCaP tumor growth, decrease serum PSA levels, and enhance enzalutamide treatment in vitro and in vivo. These studies suggest that STS drives intracrine androgen synthesis and prostate cancer proliferation. Targeting STS represents a therapeutic strategy to treat CRPC and improve second-generation antiandrogen therapy.

AR phosphorylation and CHK2 kinase activity regulates IR-stabilized AR-CHK2 interaction and prostate cancer survival.

We have previously demonstrated that checkpoint kinase 2 (CHK2) is a critical negative regulator of androgen receptor (AR) transcriptional activity, prostate cancer (PCa) cell growth, and androgen sensitivity. We have now uncovered that the AR directly interacts with CHK2 and ionizing radiation (IR) increases this interaction. This IR-induced increase in AR-CHK2 interactions requires AR phosphorylation and CHK2 kinase activity. PCa associated CHK2 mutants with impaired kinase activity reduced IR-induced AR-CHK2 interactions. The destabilization of AR - CHK2 interactions induced by CHK2 variants impairs CHK2 negative regulation of cell growth. CHK2 depletion increases transcription of DNAPK and RAD54, increases clonogenic survival, and increases resolution of DNA double strand breaks. The data support a model where CHK2 sequesters the AR through direct binding decreasing AR transcription and suppressing PCa cell growth. CHK2 mutation or loss of expression thereby leads to increased AR transcriptional activity and survival in response to DNA damage.

KLF16 Affects the MYC Signature and Tumor Growth in Prostate Cancer.

BackgroundKLF16, a member of the Kruppel-like factor (KLF) family, functions in the regulation of dopaminergic transmission, metabolism, and endocrinology. However, the role of KLF16 in prostate cancer (PCa) remains unknown.MethodsWe screened the expression of KLFs in PCa based on bioinformatics analysis. The protein levels of KLF16 in PCa specimens were confirmed by immunohistochemistry. Inhibiting KLF16 by RNA interference with shRNA was used to determine the effects of KLF16 on PCa cell growth in vitro and in vivo. RNA sequencing was used to investigate the signaling regulated by KLF16 in PCa. Bioinformatics analysis was also used to determine the possible correlations of KLF16 and signaling in PCa cohorts.ResultsBioinformatics analysis showed that KLF16 may be required for PCa development. Notably, the expression of KLF16 was elevated in human PCa tissues. In vitro and in vivo experiments both demonstrated that depleting KLF16 significantly inhibited the growth of PCa cells. Downregulation of KLF16 significantly decreased the expression of MYC signaling in PCa cells. Furthermore, KLF16 expression was correlated with MYC signaling activity.ConclusionKLF16 was overexpressed in PCa tissues compared to normal tissues. KLF16 knockdown suppressed PCa cell growth in vitro and in vivo, and a deficiency of KLF16 inhibited activation of MYC signaling.

Mechanisms by Which MnTE-2-PyP Suppresses Prostate Cancer Cell Growth

Mechanisms by Which MnTE-2-PyP Suppresses Prostate Cancer Cell Growth

MicroRNA-487a-3p functions as a new tumor suppressor in prostate cancer by targeting CCND1.

Prostate cancer (PCa) is one of the major health problems of the aging male. The roles of dysregulated microRNAs in PCa remain unclear. In this study, we mined the public published data and found that miR-487a-3p was significantly downregulated in 38 pairs of clinical prostate tumor tissues compared with the normal tissues. We further verified this result by in situ hybridization on tissue chip and quantitative real-time polymerase chain reaction (qRT-PCR) in PCa/normal cells. miR-487a-3p targeting of cyclin D1 (CCND1) was identified using bioinformatics, qRT-PCR and western blot analyses. The cellular proliferation, cell cycle, migration, and invasion were assessed by cell counting kit-8, flow cytometry analysis and transwell assay. We discovered that overexpression of miR-487a-3p suppressed PCa cell growth, migration, invasion by directly targeting CCND1. Knockdown of CCND1 in PCa cells showed similar results. Meanwhile, the expression level of CCND1 was significantly upregulated in the PCa tissues and cell lines, which presented negative correlation with the expression of miR-487a-3p. More important, we demonstrated significantly reduced growth of xenograft tumors of stable miR-487a-3p-overexpressed human PCa cells in nude mice. Taken together, for the first time, our results revealed that miR-487a-3p as a tumor suppressor of PCa could target CCND1. Our finding might reveal miR-487a-3p could be potentially contributed to the pathogenesis and a clinical biomarker or the new potential therapeutic target of PCa.

Abstract 1022: The role of dopamine signaling in prostate cancer disparities

Abstract Prostate cancer is the second leading cause of cancer-related deaths among men in western countries. Majority of prostate tumors often evolves as metastatic castration-resistant prostate cancer (CRPC) following hormonal therapy. Metastatic prostate cancer is the major cause of mortalities from this disease. African-American (AA) men have the highest incidence and mortality rate compared to any other race such as Caucasian American (CA). Despite recent advances, the cellular and molecular mechanisms that contribute to this disparity are unknown, obstructing the development of an effective therapy for this disease. Genetic and epigenetic studies have indicated that the biology of prostate cancer in AA men is substantially different from CA. Here, we investigate the dopamine (DA) signaling to better understand the mechanism of prostate cancer disparity. Our analysis of the prostate cancer public data sets showed that the dopamine receptor (DR) genes were amplified in up to 18% prostate cancer clinical cases. We have demonstrated that the levels of DR transcripts were significantly higher in the metastatic prostate cancer cell lines with African genetic ancestry than CA counters. We also demonstrate that the efficacy of pimozide, a potent DRD inhibitor and an FDA-approved antipsychotic, on AA cells was significantly higher than CA cells. In addition, we have found that L-dopa, an immediate precursor of DA differentially regulates the growth of AA and CA prostate cancer cells in a dose dependent manner. We also found that carbidopa, a potent inhibitor of the dopa decarboxylase, suppressed prostate cancer cell growth by L-dopa and showed that carbidopa re-sensitized CRPC cell line to enzalutamide, a potent inhibitor of androgen receptor (AR) signaling. These observations suggest that DA/DR signaling plays a critical role in prostate cancer disparity, making the DA/DR-AR axis a viable therapeutic target to reduce disparities in cancer mortality. Citation Format: Isaiah R. Pickett, Ava M. Boston, Marwah M. Almathkour, Camille Ragin, Mehmet A. Bilen, Adeboye O. Osunkoya, Bekir Cinar. The role of dopamine signaling in prostate cancer disparities [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 1022.