Docetaxel-resistant Prostate Cancer Research Articles

Targeting XPO6 inhibits prostate cancer progression and enhances the suppressive efficacy of docetaxel

BackgroundAlthough XPO6, one of the Exportin family members, functions in malignant progression of certain types of cancer, its role in prostate cancer (PCa) has not been elucidated. Herein, we investigated the oncogenic effect and clarified the downstream mechanism of XPO6 in PCa cells.MethodsWe detected the expression level of XPO6 in PCa tissues by immunohistochemistry (IHC) and analyzed the correlation between clinicopathological characteristics and XPO6 level based on TCGA database. The effects of XPO6 in the proliferation and migration or resistance to docetaxel (DTX) in PCa cells were assessed using CCK8, colony formation, wound-healing and Transwell assays. Mice experiments were performed to investigate the role of XPO6 in tumor progression and DTX effect in vivo. Further, functional analysis of DEGs revealed the correlation of XPO6 with Hippo pathway and XPO6 could promote the expression and nuclear translocation of YAP1 protein. Furthermore, blocking Hippo pathway with YAP1 inhibitor leads to the loss of XPO6-mediated regulation of biological functions.ResultsXPO6 was highly expressed and positively correlated with the clinicopathological characteristics of PCa. Functional experiments indicated that XPO6 could promote tumor development and DTX resistance in PCa. Mechanistically, we further confirmed that XPO6 could regulate Hippo pathway via mediating YAP1 protein expression and nuclear translocation thereby promoting PCa progression and chemotherapeutic resistance.ConclusionIn conclusion, our research reveals that XPO6 potentially function as an oncogene and promotes DTX resistance of PCa, suggesting that XPO6 could be both a potential prognostic marker as well as a therapeutic target to effectively overcome DTX resistance.

Computer-aided analysis of quercetin mechanism of overcoming docetaxel resistance in docetaxel-resistant prostate cancer

BackgroundProstate cancer (PC) is a silent but potent killer among men. In 2018, PC accounted for more than 350, 000 death cases while more than 1.2 million cases were diagnosed. Docetaxel, a chemotherapeutic drug belonging to the taxane family of drugs, is one of the most potent drugs in combating advanced PC. However, PC cells often evolve resistance against the regimen. Hence, necessitating the search for complementary and alternative therapies. Quercetin, a ubiquitous phytocompound with numerous pharmacological properties, has been reported to reverse docetaxel resistance (DR) in docetaxel-resistant prostate cancer (DRPC). Therefore, this study aimed to explore the mechanism via which quercetin reverses DR in DRPC using an integrative functional network and exploratory cancer genomic data analyses. ResultsThe putative targets of quercetin were retrieved from relevant databases, while the differentially expressed genes (DEGs) in docetaxel-resistant prostate cancer (DRPC) were identified by analysing microarray data retrieved from the Gene Expression Omnibus (GEO) database. Subsequently, the protein-protein interaction (PPI) network of the overlapping genes between the DEGs and quercetin targets was retrieved from STRING, while the hub genes, which represent the key interacting genes of the network, were identified using the CytoHubba plug-in of Cytoscape. The hub genes were further subjected to a comprehensive analysis aimed at identifying their contribution to the immune microenvironment and overall survival (OS) of PC patients, while their alterations in PC patients were also revealed. The biological roles played by the hub genes in chemotherapeutic resistance include the positive regulation of developmental process, positive regulation of gene expression, negative regulation of cell death, and epithelial cell differentiation among others. ConclusionFurther analysis revealed epidermal growth factor receptor (EGFR) as the most pertinent target of quercetin in reversing DR in DRPC, while molecular docking simulation revealed an effective interaction between quercetin and EGFR. Ultimately, this study provides a scientific rationale for the further exploration of quercetin as a combinational therapy with docetaxel.

Abstract 1756: Targeting LIFR/c-Myc Axis to Overcome Docetaxel Resistance in Prostate Cancer

Abstract Background: Docetaxel has been the most effective chemotherapeutic option after the emergence of Castration-resistant prostate cancer (CRPC). However, more than 50% of patients develop Docetaxel Resistance (DoceR) within three years of treatment. It also shows severe adverse effects that lead to dose reduction and treatment failure. Thus, targeting the underlying mechanism of DoceR could improve survival benefits for CRPC patients. In this study, we identified leukemia inhibitory factor receptor (LIFR) as a candidate for DoceR. We targeted it with EC914, a first-in-class oral small molecule, to overcome DoceR in CRPC. Methods: We developed three DoceR (PC3-R60, 22Rv1-R110, and LNCaP(C-83)-R50) isogeneic sub-lines by chronic Docetaxel treatment for six months. We analyzed those cell lines for drug resistance markers using RT-PCR and western blot. We evaluated the effect of EC914 in overcoming DoceR using cytotoxicity assay in Incucyte® live imaging system, colony survival assay, apoptosis induction, and cell cycle arrest using FACS analysis. RNA-seq analysis revealed molecular pathways related to EC914-mediated Docetaxel- sensitivity. In addition, we utilized RT-PCR and western blot analysis to examine EC914-responsive cancer stem cell (CSC) and LIFR/STAT pathway-related genes and proteins. Finally, we adopted human and mouse syngeneic PCa cells and patient-derived xenograft models to test the in vivo efficacy of EC914 in combination with Docetaxel. Results: LIFR showed significantly high mRNA and protein expression in Docetaxel resistant PCa cell model. EC914 combined with Docetaxel reduced considerably in vitro tumorigenicity (proliferation (p<0 01), colony growth (p<0 01)), induced apoptosis (p<0 01), and arrested cells in the G2/M and S phase (p<0 01) of the cell cycle. The combination also affected the CSC population and markers expression in DoceR PCa cells. Expression of cleaved caspase 3, caspase 9, and PARP-1 further validated apoptosis induction. Global transcriptome analysis identified EC914 treatment targets c-Myc pathway enrichment. Specifically, we found sixteen c-Myc pathway-related genes downregulated significantly (p<0 05) in transcriptomic and qRT-PCR validation. Knockdown of LIFR reduces phospho-STAT3 and phospho c-Myc without altering total STAT and c-Myc proteins. Mice subcutaneous implantation of human (p<0 05) and mouse (p<0 05) syngeneic PCa cells and patient-derived tissue (p=0 003) reduced xenograft tumor growth upon treatment with EC914 combined with Docetaxel. Conclusion: For the first time, we identified c-Myc pathway genes as potential LIFR signaling targets to overcome docetaxel resistance. Our findings support a new role and mechanism(s) of LIFR in CRPC and could inhibit MYC-addicted tumors. Citation Format: Sushanta Halder, Sakthivel Muniyan, Ramakanth Chirravuri-Venkata, Rama Krishna Nimmakayala, Palanisamy Nallasamy, Hareesh B. Nair, Moorthy P Ponnusamy, Surinder K. Batra, Parthasarathy Seshacharyulu. Targeting LIFR/c-Myc Axis to Overcome Docetaxel Resistance 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 1756.

Sympathetic β2-adrenergic receptor blockade overcomes docetaxel resistance in prostate cancer

PurposeDue to the limited effective therapies, resistance to docetaxel is ordinarily fatal and remains a critical clinical challenge.β2-adrenergic receptor(β2-AR)can promote the metastasis and invasion of prostate cancer, but the role in chemotherapy-resistant prostate cancer remains unclear. MethodsBy downloading the GEO database in NCBI, the expression of β2-AR in different prostate tissues was analyzed. We constructed docetaxel-resistant prostate cancer cell lines by the method of dose-escalation. LC3B-labeled stable cells and shAtg5 knockdown stable cells were constructed by lentivirus infection. The molecular mechanism of β2-AR affecting docetaxel sensitivity through apoptosis and autophage were investigated by flow cytometry, mitochondrial membrane potential and western blot. Then we detected the interaction between autophagy and apoptotic by performing immunoprecipitation assay. ResultsWe show that restraining the activity of β2-AR sensitized the cell response and reduced the resistance to docetaxel. The mechanism involves the regulation of β2-AR in the cellular response to docetaxel through apoptosis and autophagy via caspase signaling and Atg5/AMPK/mTOR pathway as well as the effect of β2-AR on the crosstalk between apoptosis and autophagy via p38 MAPK and JNK/c-Jun/FOXO3a signaling pathways. ConclusionOur data demonstrate that β2-AR inhibitor-induced autophagy and apoptosis contribute to the effectiveness responses to docetaxel in castration-resistant prostate cancer, and in combination with pharmacological agents of β2-AR and autophagy inhibitors may provide a potential therapeutic strategy to enhance the limited capacity of docetaxel to control castration-resistant prostate cancer.

Exosomal lincROR Promotes Docetaxel Resistance in Prostate Cancer through a β-catenin/HIF1α Positive Feedback Loop.

Our findings suggest that targeting hypoxia stress and chemoresistance for therapeutic purposes and lincROR could promote the improvement of treatment responses in patients with DTX-resistant prostate cancer.

Comprehensive Evaluation of Multiple Approaches Targeting ABCB1 to Resensitize Docetaxel-Resistant Prostate Cancer Cell Lines.

Docetaxel (DTX) is a mainstay in the treatment of metastatic prostate cancer. Failure of DTX therapy is often associated with multidrug resistance caused by overexpression of efflux membrane transporters of the ABC family such as the glycoprotein ABCB1. This study investigated multiple approaches targeting ABCB1 to resensitize DTX-resistant (DTXR) prostate cancer cell lines. In DU145 DTXR and PC-3 DTXR cells as well as age-matched parental controls, the expression of selected ABC transporters was analyzed by quantitative PCR, Western blot, flow cytometry and immunofluorescence. ABCB1 effluxing activity was studied using the fluorescent ABCB1 substrate rhodamine 123. The influence of ABCB1 inhibitors (elacridar, tariquidar), ABCB1-specific siRNA and inhibition of post-translational glycosylation on DTX tolerance was assessed by cell viability and colony formation assays. In DTXR cells, only ABCB1 was highly upregulated, which was accompanied by a strong effluxing activity and additional post-translational glycosylation of ABCB1. Pharmacological inhibition and siRNA-mediated knockdown of ABCB1 completely resensitized DTXR cells to DTX. Inhibition of glycosylation with tunicamycin affected DTX resistance partially in DU145 DTXR cells, which was accompanied by a slight intracellular accumulation and decreased effluxing activity of ABCB1. In conclusion, DTX resistance can be reversed by various strategies with small molecule inhibitors representing the most promising and feasible approach.

Small ankyrin 1 (sANK1) promotes docetaxel resistance in castration-resistant prostate cancer cells by enhancing oxidative phosphorylation.

Docetaxel (DTX) plays an important role in treating advanced prostate cancer (PCa). However, nearly all patients receiving DTX therapy ultimately progress to DTX resistance. How to address DTX resistance in PCa remains a key challenge for all urologists. Small ankyrin 1 (sAnk1) is an integral membrane protein in the endoplasmic reticulum. In the present study, we identified that sAnk1 is upregulated in PCa tissues and is positively associated with DTX therapy resistance in PCa. Further investigation demonstrated that overexpression of sAnk1 can significantly increase the DTX-resistant ability of PCa cells in vitro and in vivo. In addition, overexpression of sAnk1 could enhance oxidative phosphorylation (OXPHOS) levels in PCa cells, which was consistent with the higher OXPHOS levels observed in DTX-resistant PCa cells as compared to DTX-sensitive PCa cells. sAnk1 was also found to interact with polypyrimidine-tract binding protein (PTBP1), an alternative splicing factor, and suppressed PTBP1-mediated alternative splicing of the pyruvate kinase gene (PKM). Thus, overexpression of sAnk1decreased the ratio of PKM2/PKM1, enhanced the OXPHOS level, and ultimately promoted the resistance of PCa cells to DTX. In summary, our data suggest that sAnk1 enhances DTX resistance in PCa cells.

Salvage Chemotherapy with Cisplatin, Ifosfamide, and Paclitaxel in Aggressive Variant of Metastatic Castration-Resistant Prostate Cancer.

Significant progress has been achieved in the treatment of metastatic castration-resistant prostate cancer (mCRPC). However, results in patients with aggressive variant prostate cancer (AVPC) have been disappointing. Here, we report retrospectively collected data from intensively pretreated AVPC patients (n = 17; 88.2% visceral metastases; 82% elevation of neuroendocrine markers) treated with salvage chemotherapy consisting of cisplatin, ifosfamide, and paclitaxel (TIP). At the interim analysis, 60% of patients showed radiographic response or stable disease (PFS = 2.5 months; OS = 6 months). In men who responded to chemotherapy, an OS > 15 months was observed. Preclinical analyses confirmed the high activity of the TIP regimen, especially in docetaxel-resistant prostate cancer cells. This effect was primarily mediated by increased cisplatin sensitivity in the emergence of taxane resistance. Proteomic and functional analyses identified a lower DNA repair capacity and cell cycle machinery deficiency to be causative. In contrast, paclitaxel showed inconsistent effects, partially antagonizing cisplatin and ifosfamide in some AVPC models. Consequently, paclitaxel has been excluded from the TIP combination for future patients. In summary, we report for the first time the promising efficacy of TIP as salvage therapy in AVPC. Our preclinical data indicate a pivotal role for cisplatin in overcoming docetaxel resistance.

New Guanidine Alkaloids Batzelladines O and P from the Marine Sponge Monanchora pulchra Induce Apoptosis and Autophagy in Prostate Cancer Cells.

Two new guanidine alkaloids, batzelladines O (1) and P (2), were isolated from the deep-water marine sponge Monanchora pulchra. The structures of these metabolites were determined by NMR spectroscopy, mass spectrometry, and ECD. The isolated compounds exhibited cytotoxic activity in human prostate cancer cells PC3, PC3-DR, and 22Rv1 at low micromolar concentrations and inhibited colony formation and survival of the cancer cells. Batzelladines O (1) and P (2) induced apoptosis, which was detected by Western blotting as caspase-3 and PARP cleavage. Additionally, induction of pro-survival autophagy indicated as upregulation of LC3B-II and suppression of mTOR was observed in the treated cells. In line with this, the combination with autophagy inhibitor 3-methyladenine synergistically increased the cytotoxic activity of batzelladines O (1) and P (2). Both compounds were equally active in docetaxel-sensitive and docetaxel-resistant prostate cancer cells, despite exhibiting a slight p-glycoprotein substrate-like activity. In combination with docetaxel, an additive effect was observed. In conclusion, the isolated new guanidine alkaloids are promising drug candidates for the treatment of taxane-resistant prostate cancer.

P09 - Role of mitochondrial dynamics in tumorigenic potential and docetaxel resistance in prostate cancer

P09 - Role of mitochondrial dynamics in tumorigenic potential and docetaxel resistance in prostate cancer

O11 - Telaglenastat as a potential therapy in docetaxel resistant prostate cancer with a mesenchymal phenotype

O11 - Telaglenastat as a potential therapy in docetaxel resistant prostate cancer with a mesenchymal phenotype

306 (PB086) - Reversal of resistance to docetaxel and cabazitaxel in prostate cancer cells with ritonavir

Background: The taxanes docetaxel and cabazitaxel are indicated for treatment of metastatic castration-resistant prostate cancer (mCRPC). Resistance to docetaxel often develops during treatment, which can be due to an increased efflux of docetaxel via P-glycoprotein (P-gp) from the intracellular site of action. Ritonavir is an inhibitor of both cytochrome P4503A4 (CYP3A4) and P-gp. In this study we investigated whether ritonavir could improve the efficacy of docetaxel through inhibition of P-gp in docetaxel-resistant prostate cancer cells. Methods: Prostate cancer cell lines DU-145 and 22Rv1 were exposed to increasing doses of docetaxel to generate resistant sublines, DU145-DOC10 and 22Rv1DOC8 respectively. Gene expression of the resistant clones was compared to that of the parental cell lines. The parental cell lines and the docetaxel resistant cell lines were treated with several drug combinations in an 8*2 matrix 3D tumor clonogenic assay. The following drug combinations were tested: docetaxel/ritonavir, docetaxel/elacridar and cabazitaxel/ritonavir. The IC50 values of single agent drugs and drug combinations as well as combination effects between drugs (using a Bliss independence dose-response evaluation) were determined in all cell lines. Results: The most differentially upregulated gene in the resistant cell lines was ABCB1 (P-gp). Western blotting showed that both resistant cell lines expressed more P-gp than the parental cell lines. A comparison of the observed docetaxel and cabazitaxel IC50 values has been summarized in the below table.Table(abstract: 306 (PB086))DU-145DU-145DOC10DU-145DOC1022Rv122Rv1DOC822Rv1DOC8Docetaxel IC50 (nM)2.99.52.8*with 10 μM ritonavir,1.354.63.0**with 32 μM ritonavir.Cabazitaxel IC50 (nM)0.61.50.6*with 10 μM ritonavir,0.79.50.7**with 32 μM ritonavir.* with 10 μM ritonavir,** with 32 μM ritonavir. Open table in a new tab We found that docetaxel resistance conferred cross-resistance to cabazitaxel. With the addition of 10 μM ritonavir (DU-145DOC10) and 32 μM ritonavir (22Rv1DOC8) the cytoxicity of docetaxel and cabazitaxel returned to the level of observed in the parental cell lines. A similar experiment with the specific P-gp inhibitor elacridar showed that a concentration of 0.3 μM was sufficient to reverse docetaxel resistance to the same level as in the parental cell lines, confirming this as an important mechanism-of-action. In DU-145-DOC10 and 22Rv1DOC8 cells strong synergistic effects were seen of the docetaxel/ritonavir as well as the cabazitaxel/ritonavir combination, in contrast to the lack of synergy seen in the parental cell lines with these combinations. Conclusions: We demonstrated the potential for the combination of docetaxel and ritonavir to reverse or offset resistance to docetaxel (and, by implication due to its cross-resistance, also to cabazitaxel), primarily mediated through inhibition of P-gp. This provides a strong rationale to clinically test these taxanes in combination with ritonavir in patients with mCRPC. Conflict of interest: Ownership: Jos Beijnen is a shareholder of Modra Pharmaceuticals. Board of Directors: Colin Freund and Eric van der Putten are directors of Modra Pharmaceuticals.

Exosomal circRNA Scm-like with four malignant brain tumor domains 2 (circ-SFMBT2) enhances the docetaxel resistance of prostate cancer via the microRNA-136-5p/tribbles homolog 1 pathway.

Exosomal circular RNA was found to mediate cancer chemoresistance. However, whether exosomal circRNA Scm-like with four malignant brain tumor domains 2 (circ-SFMBT2) was involved in the chemoresistance of prostate cancer (PCa) remains unclear. The docetaxel (DTX) resistance of PCa cells was analyzed by Cell Counting Kit 8 assay. Quantitative real-time PCR was used to measure circSFMBT2, microRNA (miR)-136-5p and tribbles homolog 1 (TRIB1) expression. Cell proliferation, apoptosis, migration and invasion were analyzed by 5-ethynyl-2'-deoxyuridine (EdU) assay, flow cytometry, wound-healing assay and transwell assay. RNA interaction was verified by dual-luciferase reporter assay and RNA immunoprecipitation (RIP) assay. Protein expression was measured by western blot analysis. Exosomes-extracted from cells were identified by transmission electron microscope, nanoparticles tracking analysis and western blot. Xenograft mice models were constructed to analyze the effect of exosomal circSFMBT2 on the DTX sensitivity of PCa tumors in vivo. CircSFMBT2 was upregulated in DTX-resistant PCa cells, and its knockdown enhanced the DTX sensitivity of DTX-resistant PCa cells by suppressing cell proliferation, migration, invasion and enhancing apoptosis. CircSFMBT2 severed as miR-136-5p sponge to positively regulate TRIB1. The regulation of circSFMBT2 knockdown on the DTX sensitivity of DTX-resistant PCa cells could be reversed by miR-136-5p inhibitor or TRIB1 overexpression. Exosomal circSFMBT2 from DTX-resistant PCa could increase the DTX resistance of normal PCa cells. In addition, exosomal circSFMBT2 also enhanced the DTX resistance of PCa tumors in vivo, and it was highly expressed in the serum of DTX-resistance PCa patients. Exosomal circSFMBT2 enhanced the DTX resistance of PCa by miR-136-5p/TRIB1 axis, indicating that circSFMBT2 might be a potential target for the treatment of PCa chemoresistance.

Active Targeting of P-Selectin by Fucoidan Modulates the Molecular Profiling of Metastasis in Docetaxel-Resistant Prostate Cancer.

The standard of care for prostate cancer (PCa) is androgen deprivation therapy (ADT). Although hormone-sensitive PCa is curable by ADT, most conditions progress to castration-resistant prostate cancer (CRPCa) and metastatic CRPCa (mCRPCa). Front-line docetaxel has been administered to patients with CRPCa and mCRPCa. Nevertheless, docetaxel resistance after half a year of therapy has emerged as an urgent clinical concern in patients with CRPCa and mCRPCa. We verified the mechanism by which docetaxel-resistant PCa cells (DU/DX50) exhibited significant cell migration and expression of malignant tumor-related proteins. Our study shows that the biological activity of fucoidan has an important application for docetaxel-resistant PCa cells, inhibiting IL-1R by binding to P-selectin and reducing the expression levels of NF-κB p50 and Cox2 in this metastasis-inhibiting signaling pathway. Furthermore, the combined treatment of fucoidan and docetaxel showed significant anticancer and synergistic effects on the viability of DU/DX50 cells, which is relevant for overcoming the current limitations and improving treatment outcomes. Overall, fucoidan-based combination chemotherapy may exert beneficial effects and facilitate the treatment of docetaxel-resistant PCa.

CircCYP24A1 promotes Docetaxel resistance in prostate Cancer by Upregulating ALDH1A3

BackgroundDocetaxel (DTX) is the most widely prescribed first-line chemotherapy for advanced prostate cancer (PCa). Unfortunately, DTX resistance invariably emerges, leading to worse prognosis of PCa. Growing evidence has shown that circRNAs had complex spatiotemporal specificity during the tumor development and oncogenesis. This study was designed to investigate the biological functions and possible molecular mechanisms of circRNAs in DTX resistance of PCa.MethodscircRNAs in established DTX-resistant DU145 cell line were identified by RNA sequencing. Biological function of circCYP24A1 was verified in vitro and in vivo. The potential role of circCYP24A1 in the development of DTX-resistant PCa was investigated via dual-luciferase reporter assays, RIP assays and RNA pull-down assays. Univariate and multivariate logistic regression analyses was used to predict DTX-chemotherapy response based on patients’ clinical and biological information.ResultsCircCYP24A1 was identified to be upregulated in DTX-resistant DU145 cells. Upregulated circCYP24A1 was found to suppress the DTX chemosensitivity in vitro and in vivo. Furthermore, we found that circCYP24A1 promoted DTX resistance in PCa via regulating ALDH1A3 expression by sponging miR-1301-3p and activating PI3K/AKT/mTOR signaling pathway. Statistical analyses elucidated that circCYP24A1 was an independent risk factor to predict DTX response (OR = 0.165; 95% CI: 0.038–0.723; P = 0.017).ConclusionsThis study demonstrated that circCYP24A played an essential role in DTX resistance in PCa, suggesting that circCYP24A1 could be a promising biomarker to predict DTX response and a potential therapeutic target in PCa patients resistant to DTX chemotherapy.

Abstract 5332: Prostate cancer targeting therapy using PSA promoter-driven perforin expression vector encapsulated in liposomes conjugated with anti-PSMA antibody

Abstract Perforin secreted from cytotoxic T cells and natural killer cells play important roles in anti-tumor immunoreaction leading to cancer cell apoptosis. The aim of this study is to investigate whether perforin-rich tumor microenvironment could inhibit tumor growth. Advanced prostate cancer (PC) expresses high amount of prostate-specific antigen (PSA) that is a possible therapeutic target, therefore, we constructed a PSA promoter-driven perforin expression vector for its predominant expression in tumor microenvironment of PC. Prostate membrane-specific antigen (PSMA) expressed on PC cell surface is also an attractive therapeutic target. To deliver perforin expression vector to PC, it was encapsulated in liposomes conjugated with anti-PSMA antibody (PSMA-pLipo), then the anti-tumor effect of PSMA-pLipo was evaluated using docetaxel-resistant PC cell line, 22Rv1DR, expressing both PSA and PSMA. The conjugated anti-PSMA antibody on PSMA-pLipo recognized recombinant PSMA protein, and incubation with PSMA-pLipo induced perforin expression in 22Rv1DR cells but not in PC-3 cells not expressing both PSA and PSMA. Growth of 22Rv1DR and PC-3 cells was barely inhibited by PSMA-pLipo alone. Perforin functions in concert with cytotoxic lymphocytes, therefore anti-tumor effect of PSMA-pLipo was analyzed in the presence of human peripheral blood mononuclear cells (PBMCs). Low concentration of PSMA-pLipo with human PBMCs significantly inhibited growth of 22Rv1DR cells but not PC-3 cells. High concentration of PSMA-pLipo with human PBMCs showed nearly complete inhibition of 22Rv1DR cell growth. In a mouse xenograft model implanted with 22Rv1DR cells, PSMA-pLipo was intravenously administrated via tale vein and tumor volume was monitored. PSMA-pLipo inhibited growth of 22Rv1DR cells compared to injection of anti-PSMA antibody alone. The data presented here suggest that gene therapy expressing perforin specifically in PC cells could be a novel therapy for advanced PC. Citation Format: Kosuke Mizutani, Kyojiro Kawakami, Yasunori Fujita, Taku Kato, Manabu Takai, Daiki Kato, Koji Iinuma, Takuya Koie, Masafumi Ito. Prostate cancer targeting therapy using PSA promoter-driven perforin expression vector encapsulated in liposomes conjugated with anti-PSMA antibody [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 5332.

Circ_0004087 interaction with SND1 promotes docetaxel resistance in prostate cancer by boosting the mitosis error correction mechanism

BackgroundAcquisition of the chemoresistance to docetaxel (DTX), a microtubule-targeting agent, has been a huge obstacle in treatment for metastatic castration-resistant prostate cancer (mCRPC). Recently, strategies targeting the mitosis error correction mechanism including chromosomal passenger complex (CPC) were reported to reverse the resistance to microtubule-targeting anticancer agents. Meanwhile, accumulating evidence indicated the important roles of circRNAs in DTX resistance of prostate cancer (PCa). However, whether circRNAs could regulate DTX chemosensitivity by affecting the mitosis error correction mechanism remains unclear.MethodsExpression patterns of circ_0004087 and BUB1 were determined through mining the public circRNA datasets and performing western blot and qRT-PCR assays. Agarose gel electrophoresis, Sanger sequencing, and RNase R treatment were conducted to examine the circular characteristics of circ_0004087. CircRNA pull-down, mass spectrometry analysis, Co-IP, and dual-luciferase reporter assays were performed to uncover the interaction among circ_0004087, SND1, and MYB. The effects of circ_0004087 and BUB1 on docetaxel-based chemotherapy were explored by flow cytometry and in vivo drug studies upon xenografted tumor model.ResultsIn the present study, we revealed the profound interaction between a novel circRNA, circ_0004087, and the mitosis error correction mechanism. Mechanistically, circ_0004087 binding with transcriptional coactivator SND1 could stimulate the transactivation of MYB and enhance the expression of downstream target BUB1. In turn, elevated BUB1 expression further recruited CPC to centromeres and guaranteed the error-free mitosis of PCa cells. Biologically, the overexpression of circ_0004087 conferred while the knockdown impaired DTX resistance in PCa cells.ConclusionsOur study uncovered the crucial role of circ_0004087/SND1/MYB/BUB1 axis in modulating the error mitosis correction mechanism and DTX chemoresistance, suggesting that circ_0004087 may serve as a valuable prognostic biomarker and a potential therapeutic target in DTX-resistant PCa patients.

Itraconazole Reverts ABCB1-Mediated Docetaxel Resistance in Prostate Cancer.

Docetaxel (DTX) was the first chemotherapeutic agent to demonstrate significant efficacy in the treatment of men with metastatic castration-resistant prostate cancer. However, response to DTX is generally short-lived, and relapse eventually occurs due to emergence of drug-resistance. We previously established two DTX-resistant prostate cancer cell lines, LNCaPR and C4-2BR, derived from the androgen‐dependent LNCaP cell line, and from the LNCaP lineage-derived androgen-independent C4-2B sub-line, respectively. Using an unbiased drug screen, we identify itraconazole (ITZ), an oral antifungal drug, as a compound that can efficiently re-sensitize drug-resistant LNCaPR and C4-2BR prostate cancer cells to DTX treatment. ITZ can re-sensitize multiple DTX-resistant cell models, not only in prostate cancer derived cells, such as PC-3 and DU145, but also in docetaxel-resistant breast cancer cells. This effect is dependent on expression of ATP-binding cassette (ABC) transporter protein ABCB1, also known as P-glycoprotein (P-gp). Molecular modeling of ITZ bound to ABCB1, indicates that ITZ binds tightly to the inward-facing form of ABCB1 thereby inhibiting the transport of DTX. Our results suggest that ITZ may provide a feasible approach to re-sensitization of DTX resistant cells, which would add to the life-prolonging effects of DTX in men with metastatic castration-resistant prostate cancer.

Silencing of LINC01963 enhances the chemosensitivity of prostate cancer cells to docetaxel by targeting the miR-216b-5p/TrkB axis

AbstractDocetaxel (DTX) treatment effectively prolongs the overall survival of patients with prostate cancer. However, most patients eventually develop resistance to chemotherapy and experience tumor progression or even death. Long noncoding RNAs (lncRNAs) affect docetaxel chemosensitivity. However, the biological role and regulatory mechanisms of lncRNAs in docetaxel-resistant prostate cancer remain unclear. Differences in lncRNAs were evaluated by lncRNA sequencing and evaluated using quantitative real-time polymerase chain reaction, and TrkB expression was measured through western blot analysis. Proliferation was measured using the MTS, while apoptosis and cell cycle were measured using flow cytometry. In addition, migration and invasion were measured using transwell assays. Forty-eight female BALB/c nude mice were used for subcutaneous tumorigenicity and lung metastasis assays. We found that LINC01963 was overexpressed in the PC3-DR cells. LINC01963 silencing enhanced the chemosensitivity of PC3-DR to docetaxel and inhibited tumorigenicity and lung metastasis, while LINC01963 overexpression enhanced the chemoresistance of PC3 cells to docetaxel. It was found that LINC01963 bind to miR-216b-5p. The miR-216b-5p inhibitor reversed the suppressive effect of sh-LINC01963 on PC3-DR cell proliferation, migration, and invasion. Furthermore, miR-216b-5p can bind to the 3′-UTR of NTRK2 and inhibit TrkB protein levels. TrkB enhances docetaxel resistance in prostate cancer and reverses the effects of LINC01963 silencing and miR-216b-5p overexpression. In conclusion, silencing LINC01963 inhibited TrkB protein level to enhance the chemosensitivity of PC3-DR to docetaxel by means of competitively binding to miR-216b-5p. This study illustrates that LINC01963 is a novel therapeutic target for treating prostate cancer patients with DTX resistance.

Differential gene screening and functional analysis in docetaxel-resistant prostate cancer cell lines*

Abstract Objective Docetaxel-based combination chemotherapy has traditionally been the standard treatment for metastatic castration-resistant prostate cancer (PCa). However, most patients eventually develop resistance to this treatment, which further reduces their survival. This study aimed to determine key molecular genes in docetaxel-resistant PCa cell lines using bioinformatic approaches. Methods The analysis of microarray data GSE33455 (including DU-145/DU-145R and PC-3/PC-3R cell lines) obtained from the Gene Expression Omnibus (GEO) database was performed using GEO2R. Differentially expressed genes (DEGs) of DU-145/DU-145R and PC-3/PC-3R cell lines were selected, and the intersection of DEGs between the two groups was obtained. DEGs were annotated with the Gene Ontology (GO) function and enriched with the Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway using an online platform (https://cloud.oebiotech.cn/task/detail/array_enrichment/). The online tool Search Tool for the Retrieval of Interacting Genes (https://string-db.org/) was used to obtain the DEG network graph and matrix list, which was imported into Cytoscape 3.6.1 and analyzed using the Molecular Complex Detection plug-in to detect potential functional modules in the network. Results A total of 131 intersection DEGs were identified between non-treated and docetaxel-resistant PCa cell lines. GO functional annotation showed that the main genes involved were present in the plasma membrane and were involved in positive regulation of ubiquitin-protein transferase activity, positive regulation of pseudopodium assembly, centriolar subdistal appendage, and heterophilic cell-cell adhesion via plasma membrane cell adhesion molecules. KEGG pathway enrichment analysis revealed that DEGs were mainly involved in IL-17 signaling pathway, cytokine-cytokine receptor interaction, rheumatoid arthritis, legionellosis, and folate biosynthesis. We identified two distinct hubs of DEGs: (1) CD274, C-X-C motif chemokine ligand (CXCL)1, DExD/H-box helicase 58, CXCL2, CXCL8, colony-stimulating factor 2, C-X-C motif chemokine receptor 4 (CXCR4), CXCL5, and CXCL6 and (2) argininosuccinate lyase, argininosuccinate synthase 1, and asparagine synthetase. Except for the CXCR4 gene that was downregulated, the other 11 genes showed upregulated expression. Conclusion Certain differential genes may be potential targets for predicting and treating metastatic docetaxel-resistant PCa.