Androgen-independent Prostate Cancer Cells Research Articles

2-Deoxy-d-glucose Promotes Buforin IIb-Induced Cytotoxicity in Prostate Cancer DU145 Cells and Xenograft Tumors.

Inhibition of the glycolytic pathway is a critical strategy in anticancer therapy because of the role of aerobic glycolysis in cancer cells. The glycolytic inhibitor 2-Deoxy-d-glucose (2-DG) has shown potential in combination with other anticancer agents. Buforin IIb is an effective antimicrobial peptide (AMP) with broad-spectrum anticancer activity and selectivity. The efficacy of combination treatment with 2-DG and buforin IIb in prostate cancer remains unknown. Here, we tested the efficacy of buforin IIb as a mitochondria-targeting AMP in the androgen-independent human prostate cancer cell line DU145. Combining 2-DG with buforin IIb had a synergistic toxic effect on DU145 cells and mouse xenograft tumors. Combination treatment with 2-DG and buforin IIb caused stronger proliferation inhibition, greater G1 cell cycle arrest, and higher apoptosis than either treatment alone. Combination treatment dramatically decreased L-lactate production and intracellular ATP levels, indicating severe inhibition of glycolysis and ATP production. Flow cytometry and confocal laser scanning microscopy results indicate that 2-DG may increase buforin IIb uptake by DU145 cells, thereby increasing the mitochondria-targeting capacity of buforin IIb. This may partly explain the effect of combination treatment on enhancing buforin IIb-induced apoptosis. Consistently, 2-DG increased mitochondrial dysfunction and upregulated Bax/Bcl-2, promoting cytochrome c release to initiate procaspase 3 cleavage induced by buforin IIb. These results suggest that 2-DG sensitizes prostate cancer DU145 cells to buforin IIb. Moreover, combination treatment caused minimal hemolysis and cytotoxicity to normal WPMY-1 cells. Collectively, the current study demonstrates that dual targeting of glycolysis and mitochondria by 2-DG and buforin IIb may be an effective anticancer strategy for the treatment of some advanced prostate cancer.

Betel Nut Arecoline Induces Different Phases of Growth Arrest between Normal and Cancerous Prostate Cells through the Reactive Oxygen Species Pathway.

Prostate cancer (PCa) is a reproductive system cancer in elderly men. We investigated the effects of betel nut arecoline on the growth of normal and cancerous prostate cells. Normal RWPE-1 prostate epithelial cells, androgen-independent PC-3 PCa cells, and androgen-dependent LNCaP PCa cells were used. Arecoline inhibited their growth in dose- and time-dependent manners. Arecoline caused RWPE-1 and PC-3 cell cycle arrest in the G2/M phase and LNCaP cell arrest in the G0/G1 phase. In RWPE-1 cells, arecoline increased the expression of cyclin-dependent kinase (CDK)-1, p21, and cyclins B1 and D3, decreased the expression of CDK2, and had no effects on CDK4 and cyclin D1 expression. In PC-3 cells, arecoline decreased CDK1, CDK2, CDK4, p21, p27, and cyclin D1 and D3 protein expression and increased cyclin B1 protein expression. In LNCaP cells, arecoline decreased CDK2, CDK4, and cyclin D1 expression; increased p21, p27, and cyclin D3 expression; had no effects on CDK1 and cyclin B1 expression. The antioxidant N-acetylcysteine blocked the arecoline-induced increase in reactive oxygen species production, decreased cell viability, altered the cell cycle, and changed the cell cycle regulatory protein levels. Thus, arecoline oxidant exerts differential effects on the cell cycle through modulations of regulatory proteins.

The Utilization of Poly(2-ethyl-2-oxazoline)-b-Poly(ε-caprolactone) Ellipsoidal Particles for Intracellular BIKDDA Delivery to Prostate Cancer.

Prostate cancer is the most common cancer, which is about 15-20% among male cancers worldwide. As most common strategies such as radiotherapy, chemotherapy, or surgery alone can be unsuccessful in the treatment of prostate cancer, this study aims to develop a new approach to deliver newly generated proapoptotic gene, BIKDDA, to androgen independent prostate cancer cells, 22RV1, using new generation nanocarriers called ellipsoids. As far as it is known, this is the first study that assesses the ability of proapoptotic gene BIKDDA to induce apoptosis in prostate cancer cell. BIKDDA encapsulating PEtOx-b-PCL-based ellipsoids are fabricated by solvent-switch method, and their morphology, size, and BIKDDA content are characterized. Gene delivery efficiency of BIKDDA loaded PEtOx-b-PCL ellipsoids is demonstrated by analysis of BIK mRNA expression with real-time PCR. The apoptotic effect of PEtOx-b-PCL ellipsoids loaded with BIKDDA (EPs-BIKDDA) on 22RV1 is shown by Annexin V staining. The obtained results demonstrate that the treatment of 22RV1 cells with EPs-BIKDDA can significantly increase BIK mRNA levels by 4.5-fold leading to cell death. This study not only represents BIKDDA as a potential therapeutic strategy in prostate cancer but also the capacity of ellipsoids as promising in vivo gene delivery vehicles.

T-LAK cell-originated protein kinase (TOPK) enhances androgen receptor splice variant (ARv7) and drives androgen-independent growth in prostate cancer.

Despite impressive advances in the treatment of prostate cancer with various efficacious inhibitors along the androgen/androgen receptor axis, eventual development of incurable metastatic Castration-Resistant Prostate Cancer (mCRPC) is inevitable and remains a major clinical challenge. Constitutively active androgen receptor (AR) spliced variants have emerged as primary means of resistance to anti-androgens and androgen synthesis inhibitors. The alternatively spliced AR variant, ARv7, has attracted significant interest due to its constitutively active status in CRPC that drives androgen-independence. Factors that are involved in regulating ARv7 levels in CRPC are not clearly known. We recently demonstrated that a protein kinase, T-LAK cell-originated protein kinase (TOPK) level correlates with the aggressiveness of prostate cancer and its invasive behavior. In this study, we investigated whether TOPK plays a role in driving androgen-independence in prostate cancer cells. Our data demonstrate that TOPK overexpression in androgen-dependent LNCaP and VCaP induces ARv7 and drives androgen-independent growth. On the other hand, pharmacological inhibition of TOPK in androgen-independent LNCaP95 and 22Rv1 represses AR transactivation, and AR stability. In summary, this study illustrates a direct role of TOPK in regulating ARv7 and driving androgen-independence in prostate cancer cells.

Dextran-coated superparamagnetic nanoparticles modified with folate for targeted drug delivery of camptothecin

Drug delivery vehicles based on magnetic nanoparticles present a promising strategy for cancer treatment, due to controlled targeted treatment, high loading efficiency, and biosafety as compared to traditional drug delivery approaches. In the present study, superparamagnetic iron oxide (Fe3O4) nanoparticles (SPIONs) were synthesised by a co-precipitation approach, stabilised with dextran (DEX), and successfully conjugated with folate (FA) for delivery of camptothecin (CPT) in prostate cancer cells. Size and other characteristics of the modified nanoparticles were measured using scanning electron microscopy (SEM), transmission electron microscopy (TEM), dynamic light scattering (DLS), and zeta-potential. The results demonstrated that the prepared FA-DEX-SPIONs were spherical in shape with an average diameter of 63.31 nm. They had anticancer activity with high CPT loading efficiency in AT3B-1cancer cells, enabling the therapeutic activity of the drug via its active delivery and release at 37 °C in phosphate and citrate buffer solutions. MTT results exhibited no cytotoxicity on rat androgen independent prostate cancer (AT3B-1) and normal human prostate (RWPE-1) cells. In conclusion, FA-DEX-SPION composite is a promising candidate that could be used for the targeted release of CPT anti-cancer drug.

LncRNA LEF1-AS1 promotes metastasis of prostatic carcinoma via the Wnt/\u03b2-catenin pathway

BackgroundLong noncoding RNAs (lncRNAs) are important functional regulators of many biological processes of cancers. However, the mechanisms by which lncRNAs modulate androgen-independent prostate cancer (AIPC) development remain largely unknown.MethodsNext-generation sequencing technology and RT-qPCR were used to assess LEF1-AS1 expression level in AIPC tissues and adjacent normal tissues. Functional in vitro experiments, including colony formation, EDU and transwell assays were performed to assess the role of LEF1-AS1 in AIPC. Xenograft assays were conducted to assess the effect of LEF1-AS1 on cell proliferation in vivo. Chromatin immunoprecipitation (ChIP) and RNA binding protein immunoprecipitation (RIP) assays were performed to elucidate the regulatory network of LEF1-AS1.ResultsThe next-generation sequencing results showed that LEF1-AS1 is significantly overexpressed in AIPC. Furthermore, our RT-qPCR assay data showed that LEF1-AS1 is overexpressed in AIPC tissues. Functional experiments showed that LEF1-AS1 promotes the proliferation, migration, invasion and angiogenic ability of AIPC cells in vitro and tumour growth in vivo by recruiting the transcription factor C-myb to the promoter of FZD2, inducing its transcription. Furthermore, LEF1-AS1 was shown to function as a competing endogenous RNA (ceRNA) that sponges miR-328 to activate CD44.ConclusionIn summary, the results of our present study revealed that LEF1-AS1 acts as a tumour promoter in the progression of AIPC. Furthermore, the results revealed that LEF1-AS1 functions as a ceRNA and regulates Wnt/β-catenin pathway activity via FZD2 and CD44. Our results provide new insights into the mechanism that links the function of LEF1-AS1 with AIPC and suggests that LEF1-AS1 may serve as a novel potential target for the improvement of AIPC therapy.

Synthesis, molecular modeling, in vivo study and anticancer activity against prostate cancer of (+) (S)-naproxen derivatives

In this study, (S)-naproxen thiosemicarbazides (3a-d), 1,2,4-triazoles (4a-c), triazole-thioether hybride compounds (5a-p) were synthesized and their structures (3a, 3d, 4a and 5a-p) were confirmed by FT-IR, 1H NMR,13C NMR, HR-Mass spectra and elemental analysis. These compounds are designed to inhibit methionine amino peptidase-2 (MetAP2) enzyme in prostate cancer. These compounds (3d, 5a-p) evaluated against androgen-independent prostate adenocarcinoma (PC-3, DU-145) and androgen-dependent prostate adenocarcinoma (LNCaP) cell lines by using MTS method. Compounds 5a, 5b, 5d and 5e showed 14.2, 5.8, 10.8 and 8.4μM anticancer activity against PC-3cell lines, compounds 5e, 5g and 5n presented anticancer activity against DU-145cell lines 18.8, 12.25 and 10.2μM, and compounds 5g, 5m and 5n exhibited anticancer activity against LNCaP cell lines 12.25, 22.76 and 2.21μM, respectively. Consequently, of these results, compounds 5e and 5n showed the highest activities against androgen dependent and independent prostate cancer cell lines, so these compounds could be potent small molecules against prostate cancer. Furthermore, mitogen-activated protein kinase (MAPK) pathway activation, AKT (protein kinase B) phosphorylation and androgen receptor activation of compound 5n (SGK636) were investigated in LNCaP cells by using Western blot method. Compound 5n (SGK636) was also tested against mRNA expression analysis of the Bax, Bcl-2, Caspase 3, Caspase 9 by using real-time PCR analysis. Compound 5n was given to nude male mice with cancer in comparison to the control group. Compound 5n was found to reverse the malignant phenotype in the nude male mice, whereas the prostate cancer progressed in the control group. Analysis of some blood parameters in the study showed that they were within the normal values with respect to the control. The blood values of the animals treated according to the control group also exhibited compliance with the blood limit values. Molecular docking and dynamics simulation of compound 5n binding to Methionine Aminopeptidase 2 (MetAP2) enzyme rationalized its potential activity. In addition, inhibition assay MetAP2 enzyme of compound 5n was evaluated. Taken together, we suggest compound 5n to be a potential candidate for prostate cancer therapy.

Crosstalk Between AR and Wnt Signaling Promotes Castration-Resistant Prostate Cancer Growth.

IntroductionProstate cancer (PCa) is the most commonly diagnosed cancer and the third leading cause of cancer-related death in males in the United States. Despite the initial efficacy of androgen deprivation therapy in prostate cancer (PCa) patients, most patients progress to castration-resistant prostate cancer. However, the mechanisms underlying the androgen-independent progression of PCa remain largely unknown.MethodsIn this study, we established a PCa cell line (LNCaP-AI) by maintaining LNCaP cells under androgen-depleted conditions. To explore the cellular and molecular mechanisms of androgen-independent growth of PCa, we analyzed the gene expression patterns in androgen-independent prostate cancer (AIPC) compared with that in androgen-dependent prostate cancer (ADPC). KEGG pathway analysis revealed that Wnt signaling pathways were activated after androgen deprivation therapy (ADT). In vitro experiments showed that the inhibition of Wnt pathway reduced AIPC cell growth by inhibiting cell cycle progression and promoting apoptosis. Furthermore, WNT5A, LEF1 were identified as direct targets of AR by chromatin immunoprecipitation (ChIP) assay and public ChIP-seq datasets analysis.ResultsIn the present study, we found a regulatory mechanism through which crosstalk between androgen receptor (AR) and Wnt signals promoted androgen-independent conversion of PCa. The Wnt pathway was inhibited by androgen in androgen-dependent prostate cancer cells, but this blocking effect was not elicited in androgen-independent prostate cancer (AIPC) cells. Moreover, Wnt pathway genes WNT5A and LEF1 were directly downregulated by AR. In vitro experiments showed that inhibition of the Wnt pathways repressed AIPC cell growth by inhibiting cell cycle progression and promoting apoptosis. We found that WNT5A and LEF1 were downregulated in low-grade PCa but upregulated in metastatic PCa.ConclusionIn summary, we revealed that crosstalk between AR and Wnt signaling pathways promotes androgen-independent growth of PCa, which may provide novel therapeutic opportunities for castration-resistant prostate cancer.

Anticancer Imidazoacridinone C-1311 is Effective in Androgen-Dependent and Androgen-Independent Prostate Cancer Cells.

The androgen receptor (AR) plays a critical role in prostate cancer (PCa) development and metastasis. Thus, blocking AR activity and its downstream signaling constitutes a major strategy for PCa treatment. Here, we report on the potent anti-PCa activity of a small-molecule imidazoacridinone, C-1311. In AR-positive PCa cells, C-1311 was found to inhibit the transcriptional activity of AR, uncovering a novel mechanism that may be relevant for its anticancer effect. Mechanistically, C-1311 decreased the AR binding to the prostate-specific antigen (PSA) promoter, reduced the PSA protein level, and, as shown by transcriptome sequencing, downregulated numerous AR target genes. Importantly, AR-negative PCa cells were also sensitive to C-1311, suggesting a promising efficacy in the androgen-independent PCa sub-type. Irrespective of AR status, C-1311 induced DNA damage, arrested cell cycle progression, and induced apoptosis. RNA sequencing indicated significant differences in the transcriptional response to C-1311 between the PCa cells. Gene ontology analysis showed that in AR-dependent PCa cells, C-1311 mainly affected the DNA damage response pathways. In contrast, in AR-independent PCa cells, C-1311 targeted the cellular metabolism and inhibited the genes regulating glycolysis and gluconeogenesis. Together, these results indicate that C-1311 warrants further development for the treatment of PCa.

Epigallocatechin-3-gallate mobilizes intracellular Ca2+ in prostate cancer cells through combined Ca2+ entry and Ca2+-induced Ca2+ release

AimsTo elucidate the mechanism by which (−)-epigallocatechin-3-gallate (EGCG) mediates intracellular Ca2+ increase in androgen-independent prostate cancer (PCa) cells. Main methodsFollowing exposure to different doses of EGCG, viability of DU145 and PC3 PCa cells was evaluated by MTT assay and the intracellular Ca2+ dynamics by the fluorescent Ca2+ chelator Fura-2. The expression of different channels was investigated by qPCR analysis and sulfhydryl bonds by Ellman's assay. Key findingsEGCG inhibited DU145 and PC3 proliferation with IC50 = 46 and 56 μM, respectively, and induced dose-dependent peaks of internal Ca2+ that were dependent on extracellular Ca2+. The expression of TRPC4 and TRPC6 channels was revealed by qPCR in PC3 cells, but lack of effect by modulators and blockers ruled out an exclusive role for these, as well as for voltage-dependent T-type Ca2+ channels. Application of dithiothreitol and catalase and sulfhydryl (SH) measurements showed that EGCG-induced Ca2+ rise depends on SH oxidation, while the effect of EGTA, dantrolene, and the PLC inhibitor U73122 suggested that EGCG-induced Ca2+ influx acts as a trigger for Ca2+-induced Ca2+ release, involving both ryanodine and IP3 receptors. Different from EGCG, ATP caused a rapid Ca2+ increase, which was independent of external Ca2+, but sensitive to U73122. SignificanceEGCG induces an internal Ca2+ increase in PCa cells by a multi-step mechanism. As dysregulation of cytosolic Ca2+ is directly linked to apoptosis in PCa cells, these data confirm the possibility of using EGCG as a synergistic adjuvant in combined therapies for recalcitrant malignancies like androgen-independent PCa.

Chelerythrine suppresses proliferation and metastasis of human prostate cancer cells via modulating MMP/TIMP/NF-κB system.

Chelerythrine is a natural benzo[c]phenanthridine alkaloid found in many herbs and displays a wide range of antitumor activities. Here, the present study tested their effects on prostate cancer cells. The addition of chelerythrine can significantly inhibit the proliferation of androgen-independent prostate cancer DU145 and PC-3 cells at the concentration of 5 and 10μM, but not on androgen-dependent prostate cancer LNCaP cells as well as normal prostate epithelial cell line PrEC cells. Wound migration and transwell invasion assay showed the similar inhibitory effect of chelerythrine on the migration and invasion of DU145 and PC-3 cells in the same condition. Western blot analysis further confirmed that chelerythrine not only dramatically decreased MMP-2, MMP-9, and uPA protein expression, but also augmented the expression of their endogenous inhibitors (TIMP-1 and TIMP-2) and plasminogen activator inhibitors (PAI-1 and PAI-2) in both cancer cells. Meanwhile, NF-κB and AP-1 transcription factors were all suppressed as evidenced by the decline of p-p65, c-Fos, and c-Jun protein expression in both cells. Taken together, these findings suggested that chelerythrine could reduce the metastasis of androgen-independent prostate cancer cells via modulation of MMP/TIMP system and inactivation of NF-κB pathway.

Stabilization of ADAM9 by N-\u03b1-acetyltransferase 10 protein contributes to promoting progression of androgen-independent prostate cancer

N-α-Acetyltransferase 10 protein (Naa10p) was reported to be an oncoprotein in androgen-dependent prostate cancer (PCa; ADPC) through binding and increasing transcriptional activity of the androgen receptor (AR). PCa usually progresses from an androgen-dependent to an androgen-independent stage, leading to an increase in the metastatic potential and an incurable malignancy. At present, the role of Naa10p in androgen-independent prostate cancer (AIPC) remains unclear. In this study, in silico and immunohistochemistry analyses showed that Naa10 transcripts or the Naa10p protein were more highly expressed in primary and metastatic PCa cancer tissues compared to adjacent normal tissues and non-metastatic cancer tissues, respectively. Knockdown and overexpression of Naa10p in AIPC cells (DU145 and PC-3M), respectively, led to decreased and increased cell clonogenic and invasive abilities in vitro as well as tumor growth and metastasis in AIPC xenografts. From the protease array screening, we identified a disintegrin and metalloprotease 9 (ADAM9) as a potential target of Naa10p, which was responsible for the Naa10p-induced invasion of AIPC cells. Naa10p can form a complex with ADAM9 to maintain ADAM9 protein stability and promote AIPC’s invasive ability which were independent of its acetyltransferase activity. In contrast to the Naa10p-ADAM9 axis, ADAM9 exerted positive feedback regulation on Naa10p to modulate progression of AIPC in vitro and in vivo. Taken together, for the first time, our results reveal a novel cross-talk between Naa10p and ADAM9 in regulating the progression of AIPC. Disruption of Naa10p–ADAM9 interactions may be a potential intervention for AIPC therapy.

Rac1b Supports Ligand-Independent Androgen Receptor Activation in Prostate Cancer Progression

Prostate cancer represents one of the leading causes of morbidity and mortality of men worldwide. In precision medicine, tumors are screened for specific genetic alterations known as predictive markers for targeted therapy. In androgen-independent prostate cancer cells and in tissue samples of a prostate cancer patient treated with Goserelin, we identified the self-activating splice variant Rac1b. Importantly, the expression of Rac1b was sufficient to induce AR-dependent gene synthesis. We hypothesized that Rac1b antagonizes androgen depletion induced cancer cell death by blocking pro-apoptotic signalling pathways. In line with that selective knockdown of Rac1b or inhibition of Rac-dependent signalling pathways reinduced apoptosis in androgen-independent prostate cancer cells suggesting Rac1b inhibition as a potential novel therapeutic add on strategy against prostate cancer.

Inhibition on JNK Mimics Silencing of Wnt-11 Mediated Cellular Response in Androgen-Independent Prostate Cancer Cells.

Prostate cancer (PCa) is one of the most common cancers among men, and one of the leading causes of cancer death for men. The c-Jun N-terminal kinase (JNK) pathway is required for several cellular functions, such as survival, proliferation, differentiation, and migration. Wnt-11, a member of the Wnt family, has been identified for its upregulation in PCa; however, downstream signalling of Wnt-11 remains to be fully characterized. In this study, we investigated the role of the JNK pathway as a potential downstream factor for Wnt-11 signalling. For this purpose, LNCaP, DU145, and PC-3 PCa cells and normal epithelial PNT1A cells were treated with a specific JNK kinase inhibitor: JNKVIII. Our results showed that JNK inhibition decreased mitochondrial membrane potential and promoted cell death in a cell type-dependent manner. We found that JNK inhibition led to an increase in autophagy and prevented epithelial–mesenchymal transition (EMT) in independently growing androgen cells. JNK inhibition and the silencing of Wnt-11 showed similar responses in DU145 and PC-3 cells and decreased metastasis-related biomarkers, cell migration, and invasion. Overall, our results suggest that JNK signalling plays a significant role in the pathophysiology of PCa by mediating Wnt-11 induced signals. Our data highlights that both the JNK pathway and Wnt-11 could be a useful therapeutic target for the combinatory application of current PCa.

Cabazitaxel exhibits more favorable molecular changes compared to other taxanes in androgen-independent prostate cancer cells.

Taxane-based chemotherapy drugs (cabazitaxel, docetaxel, and paclitaxel) are microtubule inhibitors, which are effectively and frequently used to treat metastatic prostate cancer (PCa). Among these, cabazitaxel is offered as a new therapeutic option for patients with metastatic castration-resistant PC as that are resistant to other taxanes. Here, we investigated the cellular and molecular changes in response to cabazitaxel in comparison withdocetaxel and paclitaxel in androgen-independent human PCas. The androgen-independent human PCa cell lines, PC3 and DU145, were treated with 1 to 5nM cabazitaxel, docetaxel, or paclitaxel, and assessed for cell viability (MTT assay), colony forming ability and migration (scratch assay). The induction of apoptosis was determined through measurement of mitochondrial membrane potential (JC-1 assay) and caspase-3 activity assay. The protein expression changes (caspase-3, caspase-8, Bax, Bcl-2, β-tubulin, nuclear factor-κB [NF-κB/p50, NF-κB/p65], vascular endothelial growth factor, WNT1-inducible signaling pathway protein-1 [WISP1], transforming growth factor β [TGF-β]) in response to drug treatment were screened via western blotting. Under our experimental conditions, all taxanes significantly reduced WISP1 and TGF-β expressions, suggesting an anti-metastatic/antiangiogenic effect for these drugs. On the other hand, cabazitaxel induced more cell death and inhibited colony formation compared to docetaxel or paclitaxel. The highest fold change in caspase-3 activity and Bax/Bcl-2 ratio wasalso detected in response to cabazitaxel. Furthermore, the induction of β-tubulin expression was lower in cabazitaxel-treated cells relative to the other taxanes. In summary, cabazitaxel shows molecular changes in favor of killing PCa cells compared to other taxanes, at least for the parameters analyzed herein. The differences with other taxanes may be important while designing other studies or in clinical settings.

Upregulation of pERK and c-JUN by \u03b3-tocotrienol and not \u03b1-tocopherol are essential to the differential effect on apoptosis in prostate cancer cells

Backgroundα-tocopherol (AT) and γ-tocotrienol (GT3) are vitamin E isoforms considered to have potential chemopreventive properties. AT has been widely studied in vitro and in clinical trials with mixed results. The latest clinical study (SELECT trial) tested AT in prostate cancer patients, determined that AT provided no benefit, and could promote cancer. Conversely, GT3 has shown antineoplastic properties in several in vitro studies, with no clinical studies published to date. GT3 causes apoptosis via upregulation of the JNK pathway; however, inhibition results in a partial block of cell death. We compared side by side the mechanistic differences in these cells in response to AT and GT3.MethodsThe effects of GT3 and AT were studied on androgen sensitive LNCaP and androgen independent PC-3 prostate cancer cells. Their cytotoxic effects were analyzed via MTT and confirmed by metabolic assays measuring ATP. Cellular pathways were studied by immunoblot. Quantitative analysis and the determination of relationships between cell signaling events were analyzed for both agents tested. Non-cancerous prostate RWPE-1 cells were also included as a control.ResultsThe RAF/RAS/ERK pathway was significantly activated by GT3 in LNCaP and PC-3 cells but not by AT. This activation is essential for the apoptotic affect by GT3 as demonstrated the complete inhibition of apoptosis by MEK1 inhibitor U0126. Phospho-c-JUN was upregulated by GT3 but not AT. No changes were observed on AKT for either agent, and no release of cytochrome c into the cytoplasm was detected. Caspases 9 and 3 were efficiently activated by GT3 on both cell lines irrespective of androgen sensitivity, but not in cells dosed with AT. Cell viability of non-cancerous RWPE-1 cells was affected neither by GT3 nor AT.Conclusionsc-JUN is a recognized master regulator of apoptosis as shown previously in prostate cancer. However, the mechanism of action of GT3 in these cells also include a significant activation of ERK which is essential for the apoptotic effect of GT3. The activation of both, ERK and c-JUN, is required for apoptosis and may suggest a relevant step in ensuring circumvention of mechanisms of resistance related to the constitutive activation of MEK1.

The Antiproliferation Activity of Ganoderma formosanum Extracts on Prostate Cancer Cells

Androgen-independent prostate cancer accounts for mortality in the world. In this study, various extracts of a medical fungus dubbed Ganoderma formosanum were screened for inhibition of DU145 cells, an androgen-independent prostate cancer cell line. Results demonstrated that both hexane (GF-EH) and butanol (GF-EB) fraction of G. formosanum ethanol extract inhibited DU145 cell viability in a dose-dependent manner. GF-EH induced cell-cycle arrest in G1 phase of DU145 cells via downregulation of cyclin E2 protein expression. In addition, GF-EB triggered extrinsic apoptosis of DU145 cells by activating caspase 3 gene expression resulting in programed cell death. Above all, both GF-EH and GF-EB show lower toxicity to normal human fibroblast cell line compared to DU145 cell, implying that they possess specific drug action on cancer cells. This study provides a molecular basis of G. formosanum extract as a potential ingredient for treatment of androgen-independent prostate cancer.

Future Oncotargets: Targeting Overexpressed Conserved Protein Targets in Androgen Independent Prostate Cancer Cell Lines.

Targeting evolutionarily conserved proteins in malignant cells and the adapter proteins involved in signalling that generates from such proteins may play a cardinal role in the selection of anti-cancer drugs. Drugs targeting these proteins could be of importance in developing anti-cancer drugs. We inferred that drugs like loperamide and promethazine that act as antagonists of proteins conserved in cancer cells like voltage-gated Calcium channels (Cav), Calmodulin (CaM) and drug efflux (ABCB1) pump may have the potential to be re-purposed as an anti-cancer agent in Prostate Cancer (PCa). Growth and cytotoxic assays were performed by selecting loperamide and promethazine to target Cav, CaM and drug efflux (ABCB1) pumps to elucidate their effects on androgen-independent PC3 and DU145 PCa cell lines. We show that loperamide and promethazine in doses of 80-100μg/ml exert oncocidal effects when tested in DU145 and PC3 cell lines. Diphenhydramine, which shares its targets with promethazine, except the CaM, failed to exhibit oncocidal effects. Anti-cancer effects can be of significance if structural analogues of loperamide and promethazine that specifically target Cav, CaM and ABCB1 drug efflux pumps can be synthesized, or these two drugs could be re-purposed after human trials in PCa.

Combination therapy for metastatic hormone-sensitive prostate cancer: What? When? For whom?

Novel combination therapies are currently the standard systemic treatment for metastatic hormone-sensitive prostate cancer. As aresult, the overall survival of patients can be extended by approximately 1.5years. The taxane docetaxel, the CYP17 inhibitor abiraterone and the second generation antiandrogen apalutamide can currently be used as acombination partner for classic androgen deprivation. While the de novo synthesis of testosterone is the rationale for abiraterone or apalutamide combination, taxanes offer apromising approach in the presence of primarily androgen-independent prostate cancer cells. Due to the increased rate of side effects caused by combination therapy, it is important to clarify in daily clinical practice which patient group benefits in particular from the respective combination therapy. Hereby, the metastatic pattern, general condition and age play an important role. While there is good evidence of the use of docetaxel or abiraterone in visceral metastasis, apalutamide offers avery wide range of uses. Ultimately, the recommendation for combination therapy is always an individual decision that needs to be discussed with the patient, considering the benefits and risks.

Estrogen Receptors Promote Migration, Invasion and Colony Formation of the Androgen-Independent Prostate Cancer Cells PC-3 Through β-Catenin Pathway.

Prostate cancer is initially dependent on the androgen, gradually evolves into an androgen-independent form of the disease, also known as castration-resistant prostate cancer (CRPC). At this stage, current therapies scantily improve survival of the patient. Androgens and estrogens are involved in normal prostate and prostate cancer development. The mechanisms by which estrogens/estrogen receptors (ERs) induce prostate cancer and promote prostate cancer progression have not yet been fully identified. Our laboratory has shown that androgen-independent prostate cancer cells PC-3 express both ERα and ERβ. The activation of ERβ increases the expression of β-catenin and proliferation of PC-3 cells. We now report that the activation of ERβ promotes the increase of migration, invasion and anchorage-independent growth of PC-3 cells. Furthermore, the activation of ERα also plays a role in invasion and anchorage-independent growth of PC-3 cells. These effects are blocked by pretreatment with PKF 118–310, compound that disrupts the complex β-catenin/TCF/LEF, suggesting that ERs/β-catenin are involved in all cellular characteristics of tumor development in vitro. Furthermore, PKF 118–310 also inhibited the upregulation of vascular endothelial growth factor A (VEGFA) induced by activation of ERs. VEGF also is involved on invasion of PC-3 cells. In conclusion, this study provides novel insights into the signatures and molecular mechanisms of ERβ in androgen-independent prostate cancer cells PC-3. ERα also plays a role on invasion and colony formation of PC-3 cells.