Prostate Cancer Cell Line LNCaP Research Articles

The androgen receptor as a potential regulator of prostate cancer contractility.

Prostate cancer (PCa) is a common health hazard for men that displays androgen-dependent growth at early stages through signalling mediated by the Androgen Receptor (AR). This has inspired androgen deprivation therapy (ADT) to be the gold standard treatment; however, in later stages, PCa displays a transition to androgen-independence and loss of AR, accompanied by a drastic increase in invasiveness. Critically, both the loss of AR and ADT have been shown to induce PCa invasiveness by promoting the epithelial-to-mesenchymal transition (EMT) which has been associated with biophysical changes in other cell models. Indeed, during metastasis cancers cells change their biophysical properties (reduced cell stiffness, increased contractility) facilitating migration through crowded microenvironments. Given AR's essential role in mediating PCa progression, we suspect that AR signalling may also regulate mechanical transitions required for PC metastasis and directed cell migration. In this study we characterize PCa biophysics in response to changes in AR signalling and expression. First, we applied Traction Force Microscopy on the metastatic PCa cell line LNCaP (AR-positive) to quantify contractile changes from androgen deprivation and supplementation, observing a non-monotonic contractile response with increasing androgen dose. These results suggest that the androgen-induced biophysical response shifts depending on the androgen availability, a finding consistent with past reports demonstrating that distinct pathways depend on both androgen concentration and AR expression. Regarding the latter, we then evaluated how AR expression and activity (nuclear localization) affects PCa biophysics by quantifying the contractility of highly metastatic PC3 cells with and without AR expression under varying androgen concentrations. We find that cell contractility is positively correlated with AR nuclear localization in androgen-containing media, yet negatively correlated in androgen-deprived media. These results complement emerging trends suggesting AR may have an important mechanobiological role in PCa migration and metastasis.

Bacterial RNA virus MS2 exposure increases the expression of cancer progression genes in the LNCaP prostate cancer cell line.

Bacteriophages effectively counteract diverse bacterial infections, and their ability to treat most types of cancer has been explored using phage engineering or phage-virus hybrid platforms. In the present study, it was demonstrated that the bacteriophage MS2 can affect the expression of genes associated with the proliferation and survival of LNCaP prostate epithelial cells. LNCaP cells were exposed to bacteriophage MS2 at a concentration of 1×107 plaque forming units/ml for 24-48 h. After exposure, various cellular parameters, including cell viability, morphology, and changes in gene expression, were examined. MS2 affected cell viability adversely, reducing viability by 25% in the first 4 h of treatment; however, cell viability recovered within 24-48 h. Similarly, the AKT, androgen receptor, integrin α5, integrin β1, MAPK1, MAPK3, STAT3, and peroxisome proliferator-activated receptor-γ coactivator 1α genes, which are involved in various normal cellular processes and tumor progression, were significantly upregulated, whereas the expression levels of HSP90, ITGB5, ITGB3, HSP27, ITGAV, and PI3K genes were unchanged. Therefore, based on viability and gene expression changes, bacteriophage MS2 severely impaired LNCaP cells by reducing anchorage-dependent survival and androgen signaling. A caveolin-mediated endocytosis mechanism for MS2-mediated signaling in prostate cancer cells was proposed based on reports involving bacteriophages T4, M13, and MS2, and their interactions with LNCaP and PC3 cell lines.

Delivery of curcumin within emulsome nanoparticles enhances the anti-cancer activity in androgen-dependent prostate cancer cell.

Curcumin, a dietary polyphenol isolated from turmeric, is a potent phytochemical possessing intrinsic anticancer activities against various cancer types including prostate cancer. However, low water solubility and bioavailability of the compound are major challenges against its medical use. The objective of this study is to evaluate the therapeutic potential of curcumin-loaded emulsome nanoparticular system, i.e. CurcuEmulsomes, for the treatment of androgen dependent LNCaP prostate cancer cell line. The antiproliferative effect of both free curcumin and CurcuEmulsome were investigated comparatively on LNCaP and PNT1A cells. Cell viability data indicates that the inhibition in proliferation of LNCaP cells becomes more effective when curcumin is provided with its emulsome formulation rather than its free form. Corresponding to a therapeutic index of 2.25, Half maximal inhibitory (IC50) and cytotoxic (CC50) concentrations of CurcuEmulsomes for LNCaP and PNT1A cells were estimated as 17.1µM and 38.6µM, respectively. The fluorescence signal of autofluorescence curcumin was preserved within the CurcuEmulsomes at72h after the treatment. Thus, CurcuEmulsomes prolonged biological activity of curcumin. Induced apoptotic cell death and stimulated cell cycle arrest at G2/M phase were attributed to antiproliferative activity of CurcuEmulsomes. Treatment of LNCaP cells with CurcuEmulsomes increased expression of caspase-3 significantly by 11.76-fold, whereas decreased cyclin D1, Bcl-2 and AR expression levels significantly by of 0.18, 0.06 and 0.46-fold, respectively. Presented safety and anticancer activity of CurcuEmulsomes on LNCaP cell line highlights the potential of CurcuEmulsomes to benefit intrinsic anticancer activities of curcumin in androgen dependent prostate cancer therapy.

Antiproliferative and Antibacterial Activities of Four Commer-cial Essential Oil Samples from Boswellia carteri, B. serrata, and two chemotypes of Canarium luzonicum

The chemical compositions of four commercial essential oils were investigated using gas chromatography (GC) and gas chromatography-mass spectrometry (GC/MS) in this study. The prostate cancer cell lines PC3 and LNCaP were used to test the antiproliferative activities of the four essential oils using crystal violet staining. p-Cymene (14.2%), limonene (11.6%), and elemol (10.8%) were identified as the main compounds in Elemi-A. Limonene (36.4%), terpinolene (11.2%), and α-phellandrene (10.3%) were the major constituents in Elemi-B. α-Pinene (22.9%) and α-thujone (14.5%) were the main compounds of Frankincense-A. α-Thujone (35.4%) was the main compound in Frankincense-B. Three essential oil samples (Elemi-A, Elemi-B, and Frankincense-A) had minimum inhibitory concentration (MIC) values under 2 mg/mL against Bacillus subtilis and displayed noteworthy antibacterial activity. Additionally, Elemi-A had MIC values under 2 mg/mL against B. cereus and Pseudomonas aeruginosa. Moreover, Elemi-B had MIC values under 2 mg/mL against P. aeuroginosa. Elemi-B and Frankincense-B had dose-dependent and significant antiproliferative effects with IC50 values of 266.7 μg/mL and 230 μg/mL, respectively, against PC3 cells. The IC50 values of Elemi-A and Frankincense-A in the PC3 cells were 821.6 and 537.7 μg/mL, respectively. Only Elemi-B displayed a dose-dependent antiproliferative effect in the LNCaP cells with an IC50 value of 235.4 μg/mL. The present study determined the chemical composition of the essential oil of Elemi of French origin for the first time. Additionally, the antiproliferative activities of four essential oils against PC3 and LNCaP cells were first reported. Elemi-B, with the lowest IC50 values in the LNCaP and PC3 cells, had promising anticancer potential.

Anti-Biofilm, Anti-Quorum Sensing, and Anti-Proliferative Activities of Methanolic and Aqueous Roots Extracts of <i>Carica papaya</i> L. and <i>Cocos nucifera</i> L.

Objective: This study focused on the antibacterial and anti-proliferative activity of extracts from Carica papaya and Cocos nucifera roots. Methodology: The minimum inhibitory concentration and the minimum bactericidal concentration of the extracts on Escherichia coli, Pseudomonas aeruginosa, Streptococcus mutans, and Staphylococcus aureus were deduced by the microdilution method. The anti-biofilm activity was determined on all four strains and anti-quorum sensing activity by inhibition of violacein production in Chromobacterium violaceum. Anti-proliferative activity on prostate cultured cancer cells was evaluated by MTT assay. Sterols and triterpenes were also assayed in this study. Results: The methanolic extract of Carica papaya showed the best anti-biofilm effect with a percentage inhibition of 66.10 ± 1.79. The methanolic extract of Cocos nucifera had the strongest inhibition on the production of quorum sensing (61.42 ± 0.28). In addition, the methanolic extract of Cocos nucifera roots showed the best cytotoxic effect on prostate cancer LNCaP cell lines (IC50 = 26.98 ± 2.6 μg/mL) and Carica papaya on the PC-3 lines (IC50 = 127.20 ± 5.99 μg/mL). The extracts were also rich in triterpenes and sterols. Conclusion: This study provides support for the ethnomedical use of Carica papaya and Cocos nucifera roots as an antimicrobial and anticancer.

Increased expression of androgen receptor and PSA genes in LNCaP (prostate cancer) cell line due to high concentrations of EGCG, an active ingredient in green tea.

Androgen receptor (AR) play a key role in the onset and progression of prostate cancer. Epigallocatechin-3-gallate (EGCG) is a polyphenolic compound and the active ingredient in green tea, which is involved in modulating gene expression through epigenetic alterations. Previous studies have shown that EGCG at low concentrations reduces the expression of AR and prostate-specific antigen (PSA) in the LNCaP cell line of prostate cancer. In this study, the effect of higher EGCG concentrations on AR and PSA expression in LNCaP prostate cancer cell line was investigated. In this study, LNCaP prostate cancer cell line was used and after MTT test, concentrations of 40, 60 and 80μg/mL EGCG were used for treatment. Then, the expression of AR and PSA genes was evaluated by RT-PCR. AR protein expression was also assessed by Western blotting. The present study showed that treatment of LNCaPs cells by EGCG reduces cell proliferation. The IC50 value was 42.7μg/mL under experimental conditions. It was also observed that EGCG at concentrations of 40 and 80μg/mL increased the expression of AR and PSA (p<0.05). The present study showed that the effect of EGCG on AR expression was different at different concentrations, so that unlike previous studies, higher concentrations of EGCG (80 and 40μg/mL) increased AR and PSA expression. It seems that due to the toxic effects of EGCG in high concentrations on cancer cells and the possibility of its effect on normal cells, more caution should be exercised in its use.

Therapeutic targeting of histone lysine demethylase KDM4B blocks the growth of castration-resistant prostate cancer

Epigenetics is an emerging mechanism for tumorigenesis. Treatment that targets epigenetic regulators is becoming an attractive strategy for cancer therapy. The role of epigenetic therapy in prostate cancer (PCa) remains elusive. Previously we demonstrated that upregulation of histone lysine demethylase KDM4B correlated with the appearance of castration resistant prostate cancer (CRPC) and identified a small molecular inhibitor of KDM4B, B3. In this study, we further investigated the role of KDM4B in promoting PCa progression and tested the efficacy of B3 using clinically relevant PCa models including PCa cell line LNCaP and 22Rv1 and xenografts derived from these cell lines. In loss and gain-functional studies of KDM4B in PCa cells, we found that overexpression of KDM4B in LNCaP cells enhanced its tumorigenicity whereas knockdown of KDM4B in 22Rv1 cells reduced tumor growth in castrated mice. B3 suppressed the growth of 22Rv1 xenografts and sensitized tumor to anti-androgen receptor (AR) antagonist enzalutamide inhibition. B3 also inhibited 22Rv1 tumor growth synergistically with rapamycin, leading to cell apoptosis. Comparative transcriptomic analysis performed on KDM4B knockdown and B3-treated 22Rv1 cells revealed that B3 inhibited both H3K9me3 and H3K27me3 demethylase activities. Our studies establish KDM4B as a target for CRPC and B3 as a potential therapeutic agent. B3 as monotherapy or in combination with other anti-PCa therapeutics offers proof of principle for the clinical translation of epigenetic therapy targeting KDMs for CRPC patients.

Nonmalignant AR-positive prostate epithelial cells and cancer cells respond differently to androgen.

Prostate cancer research suffers from the lack of suitable models to study the role of normal cells in prostate carcinogenesis. To address this challenge, we developed a cell line model mimicking luminal prostate epithelial cells by modifying the immortalized prostate epithelial cell line RWPE-1 to constitutively express the androgen receptor (AR). RWPE-1-AR cells express known AR target genes, and exhibit coexpression of luminal and basal markers characteristic of transient amplifying cells, and an RNA signature resembling prostate luminal progenitor cells. Under unstimulated conditions, constitutive AR expression does not have a biologically significant effect on the proliferation of RWPE-1 cells, but when stimulated by androgens, growth is retarded. The transcriptional response of RWPE-1-AR cells to androgen stimulation involves suppression of the growth-related KRAS pathway and is thus markedly different from that of the prostate cancer cell line LNCaP and its derivative AR-overexpressing LNCaP-ARhi cells, in which growth- and cancer-related pathways are upregulated. Hence, the nonmalignant AR-positive RWPE-1-AR cell line model could be used to study the transformation of the prostate epithelium.

Ginsenoside compound K suppresses tumour growth in the 22Rv1 xenograft model and inhibits androgenic responses via the transcriptional mechanism in human prostate cancer cells.

Androgen receptor (AR) signalling is known to be dispensable for the biology of castration-resistant prostate cancer (CRPC), whereas the AR itself and the residual androgens after castration are crucial for the growth and progression of CRPC. Therefore, there is high demand for novel therapeutic candidates targeting AR itself or aberrant AR signalling to suppress the progression to or the growth of CPRC. Here, we report that ginsenoside compound K (GCK), the primary bioactive metabolite biotransformed from protopanaxadiol (PPD) ginsenoside, acts as a novel AR signalling inhibitor by transcriptionally suppressing AR expression and tumour growth in athymic nude mice. GCK inhibited cell growth in LNCaP, PC-3 and 22Rv1 prostate cancer cell lines and suppressed the expression levels of cell cycle regulators. GCK down-regulated epithelial-mesenchymal transition markers such as vimentin and matrix metalloproteinase 9 (MMP9), whereas E-cadherin was significantly increased in GCK-stimulated LNCaP and 22Rv1 cells. Moreover, GCK treatment markedly decreased both AR and AR-V7 protein levels in LNCaP and 22Rv1 cells, possibly by decreasing AR promoter activity. Experiments with AR promoter-deleted constructs revealed that the region between -412 and -227 is critical for GCK regulation. GCK treatment in athymic nude mice implanted with 22Rv1 CRPC cell lines significantly suppressed tumour growth and AR expression levels in tumour tissues. Collectively, our results suggest that GCK, as a novel AR inhibitor, could be a potential therapeutic agent against prostate cancer and an effective chemopreventive agent to delay the progression to CRPC.

HSPB8 facilitates prostate cancer progression via activating the JAK/STAT3 signaling pathway.

Prostate cancer (PC) is a clinically and biologically heterogeneous disease that lacks effective treatment. Heat shock protein B8 (HSPB8) is an important factor in the progression of various types of cancer. However, the clinical significance and biological role of HSPB8 in PC are still unclear. In this study, we determined HSPB8 expression in PC tissues by immunohistochemical staining and explored the in vitro functions of HSPB8 using HSPB8 knockdown DU145 and LNcap PC cell lines. The in vivo effect of HSPB8 was explored by a subcutaneous xenograft mice model. The human phospho-kinase array and signal transducer and activator of transcription (STAT) 3 activator were utilized to explore the potential mechanism of HSPB8-induced PC progression. As a result, we found that HSPB8 was abundantly expressed in PC tissues and cell lines. HSPB8 knockdown inhibited cell proliferation and migration, promoted apoptosis and cycle repression, as well as weakened tumorigenesis ability. Mechanistically, we demonstrated that HSPB8 facilitates the malignant phenotypes of PC by activating the Janus kinase/STAT3 signaling pathway. These results proposed that HSPB8 seems to be an attractive therapeutic target for PC patients.

Curcumin and Its Derivatives Induce Apoptosis in Human Cancer Cells by Mobilizing and Redox Cycling Genomic Copper Ions.

Turmeric spice contains curcuminoids, which are polyphenolic compounds found in the Curcuma longa plant's rhizome. This class of molecules includes curcumin, demethoxycurcumin, and bisdemethoxycurcumin. Using prostate cancer cell lines PC3, LNCaP, DU145, and C42B, we show that curcuminoids inhibit cell proliferation (measured by MTT assay) and induce apoptosis-like cell death (measured by DNA/histone ELISA). A copper chelator (neocuproine) and reactive oxygen species scavengers (thiourea for hydroxyl radical, superoxide dismutase for superoxide anion, and catalase for hydrogen peroxide) significantly inhibit this reaction, thus demonstrating that intracellular copper reacts with curcuminoids in cancer cells to cause DNA damage via ROS generation. We further show that copper-supplemented media sensitize normal breast epithelial cells (MCF-10A) to curcumin-mediated growth inhibition, as determined by decreased cell proliferation. Copper supplementation results in increased expression of copper transporters CTR1 and ATP7A in MCF-10A cells, which is attenuated by the addition of curcumin in the medium. We propose that the copper-mediated, ROS-induced mechanism of selective cell death of cancer cells may in part explain the anticancer effects of curcuminoids.

GPX2 predicts recurrence-free survival and triggers the Wnt/β-catenin/EMT pathway in prostate cancer.

ObjectiveThis study aimed to establish a prognostic model related to prostate cancer (PCa) recurrence-free survival (RFS) and identify biomarkers.MethodsThe RFS prognostic model and key genes associated with PCa were established using Least Absolute Shrinkage and Selection Operator (LASSO) and Cox regression from the Cancer Genome Atlas (TCGA)-PRAD and the Gene Expression Omnibus (GEO) GSE46602 datasets. The weighted gene co-expression network (WGCNA) was used to analyze the obtained key modules and genes, and gene set enrichment analysis (GSEA) was performed. The phenotype and mechanism were verified in vitro.ResultsA total of 18 genes were obtained by LASSO regression, and an RFS model was established and verified (TCGA, AUC: 0.774; GSE70768, AUC: 0.759). Three key genes were obtained using multivariate Cox regression. WGCNA analysis obtained the blue module closely related to the Gleason score (cor = –0.22, P = 3.3e − 05) and the unique gene glutathione peroxidase 2 (GPX2). Immunohistochemical analysis showed that the expression of GPX2 was significantly higher in patients with PCa than in patients with benign prostatic hyperplasia (P < 0.05), but there was no significant correlation with the Gleason score (GSE46602 and GSE6919 verified), which was also verified in the GSE46602 and GSE6919 datasets. The GSEA results showed that GPX2 expression was mainly related to the epithelial–mesenchymal transition (EMT) and Wnt pathways. Additionally, GPX2 expression significantly correlated with eight kinds of immune cells. In human PCa cell lines LNCaP and 22RV1, si-GPX2 inhibited proliferation and invasion, and induced apoptosis when compared with si-NC. The protein expression of Wnt3a, glycogen synthase kinase 3β (GSK3β), phosphorylated (p)-GSK3β, β-catenin, p-β-catenin, c-myc, cyclin D1, and vimentin decreased; the expression of E-cadherin increased; and the results for over-GPX2 were opposite to those for over-NC. The protein expression of GPX2 decreased, and β-catenin was unchanged in the si-GPX2+ SKL2001 group compared with the si-NC group.ConclusionWe successfully constructed the PCa RFS prognostic model, obtained RFS-related biomarker GPX2, and found that GPX2 regulated PCa progression and triggered Wnt/β-catenin/EMT pathway molecular changes.

The Oxidative and Cytotoxic Effects of Resveratrol Compared With Cisplatin in the LNCap Prostate Cancer Cell Line

Introduction: Prostate cancer is one of the most common diseases worldwide, and many efforts are made to treat this disease; however, these efforts seem to be futile. Accordingly, this study tends to compare the cytotoxic and oxidative (as shown by the production of reactive oxygen species (ROS)) effects of resveratrol in comparison with cisplatin in a prostate cancer cell line (LNCap). Methods: After treatment of LNCap cells with the concentrations of 1, 10, 100, 500, and 1000 µg/mL of resveratrol, and 1, 5, 10, and 50 µg/mL of cisplatin, the viability percentage of cells was analyzed using MTT and spectrophotometry. Also, ROS production in this cell line at the IC50 concentrations of cisplatin and resveratrol was analyzed using flow cytometry. Results: The results of the MTT test showed that cisplatin and resveratrol could both reduce cell viability at high concentrations because of increased cytotoxicity. Measurement of ROS production showed that cisplatin and resveratrol increased ROS levels compared to control cells.Conclusion: The results obtained from this study showed that resveratrol, as a plant derivative, had anticancer and antioxidant properties against the LNCap prostate cancer cell line. Because of the side effects of cisplatin, it can be replaced by resveratrol as a good candidate to be used in chemotherapy.

YAP1-TEAD1 mediates the perineural invasion of prostate cancer cells induced by cancer-associated fibroblasts

Perineural invasion (PNI) driven by the tumor microenvironment (TME) has emerged as a key pattern of metastasis of prostate cancer (PCa), while its underlying mechanism is still elusive. Here, we identified increased CAFs and YAP1 expression levels in patients with metastatic PCa. In the cultured PCa cell line LNCaP, co-culture with cancer-associated fibroblasts (CAFs) could upregulate YAP1 protein expression. Either ectopic overexpression of YAP1 or co-culture with CAFs could promote the infiltration of LNCaPs towards dorsal root ganglia (DRG). This effect could be blocked using an YAP1 inhibitor. In vivo, overexpression of YAP1 could increase PNI in a mouse model of sciatic nerve tumor invasion. Mechanistically, TEAD1 binds to the NGF promotor and YAP1/TEAD1 activates its transcription and consequently increases NGF secretion. In turn, PCa cells treated with CM from CAFs or stable YAP1 overexpression can stimulate DRG to secrete CCL2. The epithelial-to-mesenchymal transition (EMT) of PCa cells is thus activated via CCL2/CCR2. Overall, our data demonstrate that CAFs can activate YAP1/TEAD1 signaling and increase the secretion of NGF, therefore promoting PCa PNI. In addition, EMT induced by PNI suggests a feedback loop is present between neurons and PCa cells.

Synthesis of carbohydrate analogues of the THF-acetogenin 4-deoxyannomontacin and their cytotoxicity against human prostate cancer cell lines

The THF containing acetogenin 4-deoxyannonmontacin (4-DAN) has attracted interest for its potent cytotoxicity against a broad range of human tumor cell lines, and relatively simple structure. Herein is described the synthesis and cytotoxicity of C-10 epimers of 4-DAN and analogues thereof comprising carbohydrate and thiophene substitutes for the THF and butenolide moieties respectively. The key synthetic ploy was the union of THF and butenolide segments or their substitutes, via an alkene cross metathesis. The different analogues showed cytotoxicity in the low micromolar to nanomolar range against the human prostate cancer cell lines LNCaP and PC3. A relatively simple mannose-linked thiophene analog was found to be similar in activity to 4-DAN.

CARD14 Signalling Ensures Cell Survival and Cancer Associated Gene Expression in Prostate Cancer Cells.

Prostate cancer (PCa) is one of the most common cancer types in men and represents an increasing global problem due to the modern Western lifestyle. The signalling adapter protein CARD14 is specifically expressed in epithelial cells, where it has been shown to mediate NF-κB signalling, but a role for CARD14 in carcinoma has not yet been described. By analysing existing cancer databases, we found that CARD14 overexpression strongly correlates with aggressive PCa in human patients. Moreover, we showed that CARD14 is overexpressed in the LNCaP PCa cell line and that knockdown of CARD14 severely reduces LNCaP cell survival. Similarly, knockdown of BCL10 and MALT1, which are known to form a signalling complex with CARD14, also induced LNCaP cell death. MALT1 is a paracaspase that mediates downstream signalling by acting as a scaffold, as well as a protease. Recent studies have already indicated a role for the scaffold function of MALT1 in PCa cell growth. Here, we also demonstrated constitutive MALT1 proteolytic activity in several PCa cell lines, leading to cleavage of A20 and CYLD. Inhibition of MALT1 protease activity did not affect PCa cell survival nor activation of NF-κB and JNK signalling, but reduced expression of cancer-associated genes, including the cytokine IL-6. Taken together, our results revealed a novel role for CARD14-induced signalling in regulating PCa cell survival and gene expression. The epithelial cell type-specific expression of CARD14 may offer novel opportunities for more specific therapeutic targeting approaches in PCa.

The STAT3 inhibitor GPB730 enhances the sensitivity to enzalutamide in prostate cancer cells

Enzalutamide is a second-generation anti-androgen which has shown increased survival in patients with metastatic prostate cancer. However, some patients do not respond to this therapy or will develop resistance to treatment over time. Signal Transducer and Activator of Transcription 3 (STAT3) is known to be involved in castration-resistant prostate cancer and to interact with androgen receptor (AR)-signaling. This study aims to investigate the combination enzalutamide and the small molecule STAT3 inhibitor GPB730 for enhanced therapeutic effect in advanced prostate cancer in vitro. The prostate cancer cell lines LNCaP (androgen dependent) and C4–2 (androgen insensitive) were used. The effect of enzalutamide and GPB730, alone and in combination, was investigated on viability and IC50 values calculated. Enzalutamide and GPB730 treated LNCaP and C4–2 cells were subjected to western blot and QPCR analyses in order to investigate the expression of AR, STAT3 and down-stream targets. C4–2 were less sensitive to growth inhibition by enzalutamide than LNCaP cells. GPB730 enhanced the growth inhibitory effect of enzalutamide in LNCaP and C4–2 cells. The addition of GPB730 to enzalutamide decreased the IC50 values for enzalutamide by 3.3-fold for LNCaP and by 12-fold for C4–2. In C4–2 cells, GPB730 alone decreased PSA expression and enhanced the enzalutamide induced decrease in NKX3.1 expression. GPB730 and enzalutamide in combination enhanced inhibition of c-myc and survivin expression. This study suggests that enzalutamide may be combined with the STAT3 inhibitor GPB730 in order to enhance the efficacy of enzalutamide, offering a new therapeutic approach in advanced prostate cancer.

Preclinical Assessment of the Combination of PSMA-Targeting Radionuclide Therapy with PARP Inhibitors for Prostate Cancer Treatment.

Prostate specific membrane antigen targeted radionuclide therapy (PSMA-TRT) is a promising novel treatment for prostate cancer (PCa) patients. However, PSMA-TRT cannot be used for curative intent yet, thus additional research on how to improve the therapeutic efficacy is warranted. A potential way of achieving this, is combining TRT with poly ADP-ribosylation inhibitors (PARPi), which has shown promising results for TRT of neuroendocrine tumor cells. Currently, several clinical trials have been initiated for this combination for PCa, however so far, no evidence of synergism is available for PCa. Therefore, we evaluated the combination of PSMA-TRT with three classes of PARPi in preclinical PCa models. In vitro viability and survival assays were performed using PSMA-expressing PCa cell lines PC3-PIP and LNCaP to assess the effect of increasing concentrations of PARPi veliparib, olaparib or talazoparib in combination with PSMA-TRT compared to single PARPi treatment. Next, DNA damage analyses were performed by quantifying the number of DNA breaks by immunofluorescent stainings. Lastly, the potential of the combination treatments was studied in vivo in mice bearing PC3-PIP xenografts. Our results show that combining PSMA-TRT with PARPi did not synergistically affect the in vitro clonogenic survival or cell viability. DNA-damage analysis revealed only a significant increase in DNA breaks when combining PSMA-TRT with veliparib and not in the other combination treatments. Moreover, PSMA-TRT with PARPi treatment did not improve tumor control compared to PSMA-TRT monotherapy. Overall, the data presented do not support the assumption that combining PSMA-TRT with PARPi leads to a synergistic antitumor effect in PCa. These results underline that extensive preclinical research using various PCa models is imperative to validate the applicability of the combination strategy for PCa, as it is for other cancer types.

Fibronectin Modulates the Expression of miRNAs in Prostate Cancer Cell Lines.

Prostate cancer (PCa) is a significant cause of cancer-related deaths among men and companion animals, such as dogs. However, despite its high mortality and incidence rates, the molecular mechanisms underlying this disease remain to be fully elucidated. Among the many factors involved in prostate carcinogenesis, the extracellular matrix (ECM) plays a crucial role. This ECM in the prostate is composed mainly of collagen fibers, reticular fibers, elastic fibers, proteoglycans and glycoproteins, such as fibronectin. Fibronectin is a glycoprotein whose dysregulation has been implicated in the development of multiple types of cancer, and it has been associated with cell migration, invasion, and metastasis. Furthermore, our research group has previously shown that fibronectin induces transcriptional changes by modulating the expression of protein coding genes in LNCaP cells. However, potential changes at the post-transcriptional level are still not well understood. This study investigated the impact of exposure to fibronectin on the expression of a key class of regulatory RNAs, the microRNAs (miRNAs), in prostate cancer cell lines LNCaP and PC-3. Five mammalian miRNAs (miR-21, miR-29b, miR-125b, miR-221, and miR-222) were differentially expressed after fibronectin exposure in prostate cell lines. The expression profile of hundreds of mRNAs predicted to be targeted by these miRNAs was analyzed using publicly available RNA-Sequencing data (GSE64025, GSE68645, GSE29155). Also, protein-protein interaction networks and enrichment analysis were performed to gain insights into miRNA biological functions. Altogether, these functional analyzes revealed that fibronectin exposure impacts the expression of miRNAs potentially involved in PCa causing changes in critical signaling pathways such as PI3K-AKT, and response to cell division, death, proliferation, and migration. The relationship here demonstrated between fibronectin exposure and altered miRNA expression improves the comprehension of PCa in both men and other animals, such as dogs, which naturally develop prostate cancer.

Abstract LB082: Genome-wide CRISPR activation screen identifies PRRX2 as an enzalutamide resistance gene in prostate cancer

Abstract Androgen receptor pathway inhibitors are the mainstay treatment for advanced prostate cancer, but resistance is common. Here, we used a CRISPR activation screen to identify genes that promote enzalutamide resistance in the metastatic castration-sensitive prostate cancer cell line LNCaP. We found that activation of the TGF-β target gene, PRRX2, promoted enzalutamide resistance. PRRX2 expression is highest in double negative prostate cancer (DNPC) patients and a PRRX2-related gene signature identified a subset of DNPC patients with lower overall survival. PRRX2 expressing cells showed alterations in the CDK4/6/Rb/E2F and BCL2 pathways. Accordingly, CDK4/6 and BCL2 inhibitors sensitized PRRX2-expressing enzalutamide-resistant tumors to enzalutamide. High PRRX2 expression/signature in prostate cancer merit investigation as markers of enzalutamide resistance that could be reversed with CDK4/6 and BCL2 inhibitors. Citation Format: Yara R. Rodriguez, Kenji Unno, Mihai Truica, Zachary R. Chalmers, Young A Yoo, Rajita Vatapalli, Vinay Sagar, Jindan Yu, Barbara Lysy, Huiying Han, Sarki A. Abdulkadir. Genome-wide CRISPR activation screen identifies PRRX2 as an enzalutamide resistance gene in prostate cancer [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 LB082.