p53 expression controls prostate cancer sensitivity to chemotherapy and the MDM2 inhibitor Nutlin-3

Neuroendocrine Prostate Cancer Drivers SOX2 and BRN2 Confer Differential Responses to Imipridones ONC201, ONC206, and ONC212 in Prostate Cancer Cell Lines

Prostate cancer (PCa) is the leading cause death from cancer in men worldwide. Approximately 30% of castrate-resistant PCa's become refractory to therapy due to neuroendocrine differentiation (NED) that is present in <1% of androgen-sensitive tumors. First-in-class imipridone ONC201/TIC10 has shown clinical activity against midline gliomas, neuroendocrine tumors and PCa. We explored the question of whether NED promotes sensitivity to imipridones ONC201 and ONC206 by inducible overexpression of SOX2 and BRN2, well-known neuroendocrine drivers, in human PCa cell lines DU145 or LNCaP. Slight protection from ONC201 or ONC206 with SOX2 and BRN2 overexpression was observed in the inducible LNCaP cells but not in the DU145 cells. At 2 months, there was an apparent increase in CLpP expression in LNCaP SOX2-overexpressing cells but this did not confer enhanced sensitivity to ONC201. DU145 SOX2-overexpressing cells had a significantly reduced ONC201 sensitivity than DU145 control cells. The results support the idea that treatment of castrate-resistant prostate cancer by imipridones may not be significantly impacted by neuroendocrine differentiation as a therapy-resistance mechanism. The results support further testing of imipridones across subtypes of androgen-sensitive and castrate-resistant prostate cancer.

Studying protein-protein interactions: Latest and most popular approaches

PPIs, or protein-protein interactions, are essential for many biological processes. According to the findings, abnormal PPIs have been linked to several diseases, such as cancer and infectious and neurological disorders. Consequently, focusing on PPIs is a path toward disease treatment and a crucial tool for producing novel medications. Many methods exist to investigate PPIs, including low- and high-throughput studies. Since many PPIs have been discovered using in vitro and in vivo experimental approaches, the use of computational methods to predict PPIs has grown due to the expanding scale of PPI data and the intrinsic complexity of interacting mechanisms. Recognizing PPI networks offers a systematic means of predicting protein functions, and pathways that are included. These investigations can help uncover the underlying molecular mechanisms of complex phenotypes and clarify the biological processes related to health and diseases. Therefore, our goal in this study is to provide an overview of the latest and most popular approaches for investigating PPIs. We also overview some important clinical approaches based on the PPIs and how these interactions can be targeted.

TRIM47 silencing inhibits the malignant biological behaviors of prostate cancer cells by regulating MDM2/p53 signaling

Prostate cancer (PCa) is a prevalent male malignancy globally. Tripartite motif 47 (TRIM47) has been reported to be associated with PCa. However, how TRIM47 acts on PCa is still incompletely understood. Here, we explored the biological roles of TRIM47 in PCa cells and investigated its potential regulatory mechanism. TRIM47 expression in PCa cells was detected by qRT-PCR and western blot. After TRIM47 silencing, the viability of PCa cells was measured using CCK-8 method. Flow cytometry was employed to estimate cell cycle. Cell apoptotic level was subjected to appraisement with TUNEL assay. Additionally, wound healing- and transwell assays were adopted for evaluation of migration and invasion of PCa cells. Moreover, the Biogrid database and HDOCK SERVER predicated that TRIM47 could interact with mouse double minute 2 (MDM2), which was detected using the Co-immunoprecipitation (co-IP) assay and glutathione S-transferase (GST) pull-down assay. The expression of proteins in MDM2/p53 signaling was detected by western blot analysis. Results indicated that TRIM47 expression was highly expressed in PCa cells. TRIM47 knockdown inhibited PCa proliferation and cell cycle whereas promoted cell apoptosis. Besides, TRIM47 knockdown significantly inhibited the migration and invasion of PCa cells. In addition, TRIM47 was proved to bind to MDM2 and regulated MDM2/p53 expression. Importantly, MDM2 overexpression counteracted the impacts of TRIM47 knockdown on cell viability, cell cycle, apoptosis, migration and invasion by regulating the MDM2/p53 pathway. Collectively, our results suggested that TRIM47 silencing inhibits the malignant biological behaviors of prostate cancer cells by regulating MDM2/p53 signaling, which may provide a novel therapeutic target for PCa treatment.

P53 together with ferroptosis: a promising strategy leaving cancer cells without escape

TP53, functioning as the keeper of the genome, assumes a pivotal function in the inhibition of tumorigenesis. Recent studies have revealed that p53 regulates ferroptosis pathways within tumor cells and is closely related to tumorigenesis. Therefore, we summarize the pathways and mechanisms by which p53 regulates ferroptosis and identify a series of upstream and downstream molecules involved in this process. Furthermore, we construct a p53-ferroptosis network centered on p53. Finally, we present the progress of drugs to prevent wild-type p53 (wtp53) degeneration and restore wtp53, highlighting the deficiencies of drug development and the prospects for p53 in cancer treatment. These findings provide novel strategies and directions for future cancer therapy.

Self-Assembled Molecular Complexes of 1,10-Phenanthroline and 2-Aminobenzimidazoles: Synthesis, Structure Investigations, and Cytotoxic Properties

Three new molecular complexes (phen)3(2-amino-Bz)2(H+)(BF4-)·3H2O 5, (phen)3(2-amino-5(6)-methyl-Bz)2(H+)(BF4-)·H2O 6, and (phen)(1-methyl-2-amino-Bz)(H+)(BF4-) 7, were prepared by self-assembly of 1,10-phenanthroline (phen) and various substituted 2-aminobenzimidazoles. Confirmation of their structures was established through spectroscopic methods and elemental analysis. The X-ray diffraction analysis revealed that the crystal structure of 7 is stabilized by the formation of hydrogen bonds and short contacts. In addition, the molecular geometry and electron structure of molecules 5 and 6 were theoretically evaluated using density functional theory (DFT) methods. According to the DFT B3LYP/6-311+G* calculations, the protonated benzimidazole (Bz) units act as NH hydrogen bond donors, binding two phenanthrolines and a BF4- ion. Non-protonated Bz unit form hydrogen bonds with the N-atoms of a third molecule phen. The molecular assembly is held together by π-π stacking between benzimidazole and phenanthroline rings, allowing for N-atoms to associate with water molecules. The complexes were tested in vitro for their tumor cell growth inhibitory effects on prostate (PC3), breast (MDA-MB-231 and MCF-7), and cervical (HeLa) cancer cell lines using MTT-dye reduction assay. The in vitro cytotoxicity analysis and spectrophotometric investigation in the presence of ct-DNA, showed that self-assembled molecules 5-7 are promising DNA-binding anticancer agents warranting further in-depth exploration.

The efficacy of natural bioactive compounds against prostate cancer: Molecular targets and synergistic activities

Globally, prostate cancer (PCa) is regarded as a challenging health issue, and the number of PCa patients continues to rise despite the availability of effective treatments in recent decades. The current therapy with chemotherapeutic drugs has been largely ineffective due to multidrug resistance and the conventional treatment has restricted drug accessibility to malignant tissues, necessitating a higher dosage resulting in increased cytotoxicity. Plant-derived bioactive compounds have recently attracted a great deal of attention in the field of PCa treatment due to their potent effects on several molecular targets and synergistic effects with anti-PCa drugs. This review emphasizes the molecular mechanism of phytochemicals on PCa cells, the synergistic effects of compound-drug interactions, and stem cell targeting for PCa treatment. Some potential compounds, such as curcumin, phenethyl-isothiocyanate, fisetin, baicalein, berberine, lutein, and many others, exert an anti-PCa effect via inhibiting proliferation, metastasis, cell cycle progression, and normal apoptosis pathways. In addition, multiple studies have demonstrated that the isolated natural compounds: d-limonene, paeonol, lanreotide, artesunate, and bicalutamide have potential synergistic effects. Further, a significant number of natural compounds effectively target PCa stem cells. However, further high-quality studies are needed to firmly establish the clinical efficacy of these phytochemicals against PCa.

MicroRNAs as biomarkers for early diagnosis, targeting and prognosis of prostate cancer

Globally, prostate cancer (PC) is leading cause of cancer-related mortality in men worldwide. Despite significant advances in the treatment and management of this disease, the cure rates for PC remains low, largely due to late detection. PC detection is mostly reliant on prostate-specific antigen (PSA) and digital rectal examination (DRE); however, due to the low positive predictive value of current diagnostics, there is an urgent need to identify new accurate biomarkers. Recent studies support the biological role of microRNAs (miRNAs) in the initiation and progression of PC, as well as their potential as novel biomarkers for patients' diagnosis, prognosis, and disease relapse. In the advanced stages, cancer-cell-derived small extracellular vesicles (SEVs) may constitute a significant part of circulating vesicles and cause detectable changes in the plasma vesicular miRNA profile. Recent computational model for the identification of miRNA biomarkers discussed. In addition, accumulating evidence indicates that miRNAs can be utilized to target PC cells. In this article, the current understanding of the role of microRNAs and exosomes in the pathogenesis and their significance in PC prognosis, early diagnosis, chemoresistance, and treatment are reviewed.

The CDK7 inhibitor CT7001 (Samuraciclib) targets proliferation pathways to inhibit advanced prostate cancer

BACKGROUND

Current strategies to inhibit androgen receptor (AR) are circumvented in castration-resistant prostate cancer (CRPC). Cyclin-dependent kinase 7 (CDK7) promotes AR signalling, in addition to established roles in cell cycle and global transcription, providing a rationale for its therapeutic targeting in CRPC.

METHODS

The antitumour activity of CT7001, an orally bioavailable CDK7 inhibitor, was investigated across CRPC models in vitro and in xenograft models in vivo. Cell-based assays and transcriptomic analyses of treated xenografts were employed to investigate the mechanisms driving CT7001 activity, alone and in combination with the antiandrogen enzalutamide.

RESULTS

CT7001 selectively engages with CDK7 in prostate cancer cells, causing inhibition of proliferation and cell cycle arrest. Activation of p53, induction of apoptosis, and suppression of transcription mediated by full-length and constitutively active AR splice variants contribute to antitumour efficacy in vitro. Oral administration of CT7001 represses growth of CRPC xenografts and significantly augments growth inhibition achieved by enzalutamide. Transcriptome analyses of treated xenografts indicate cell cycle and AR inhibition as the mode of action of CT7001 in vivo.

CONCLUSIONS

This study supports CDK7 inhibition as a strategy to target deregulated cell proliferation and demonstrates CT7001 is a promising CRPC therapeutic, alone or in combination with AR-targeting compounds.

Effect of the mycotoxin deoxynivalenol in combinational therapy with TRAIL on prostate cancer cells

Tumor necrosis factor-related apoptosis-induced ligand (TRAIL) is reported as a promising anti-cancer therapeutic target. Unfortunately, prostate cancer cells (PCa) are partially resistant to TRAIL-induced apoptosis limiting its therapeutic potential. The existing body of knowledge suggests that naturally produced compounds, such as mycotoxin deoxynivalenol (DON), might potentially sensitize cells to TRAIL treatment and improve the efficiency of therapy. Previously, we observed that DON induces oxidative stress and apoptosis in PCa cell lines. Thus we addressed here whether DON can sensitize PCa cells to TRAIL-induced apoptosis. Our data demonstrates that three out of four tested PCa cell lines pretreated with DON increased TRAIL-induced apoptosis detected with flow cytometry. This effect was associated with oxidative stress (LNCaP and DU-145 cell line) and elevated DNA damage (DU-145, LNCaP, and 22Rv1 cell lines). Next, in the animal model we inoculated PC tumor to SCKID mice followed by administration of DON intraperitoneally and/or TRIAL intravenously. During 21 days monitoring of tumor growth, the animals received 7 doses of DON, TRAIL, DON+TRAIL or control injections. No significant reduction in tumor mass was observed after combinational treatment of TRAIL and DON compared to 1 μg/kg of body weight DON treatment alone, which itself decreased the tumor growth. However, despite the lack of the TRAIL + DON effect, DON itself inducing apoptosis is an interesting compound worth investigating in the context of other combination therapies.

DDX5 mRNA-targeting antisense oligonucleotide as a new promising therapeutic in combating castration-resistant prostate cancer

The heat shock protein 27 (Hsp27) has emerged as a principal factor of the castration-resistant prostate cancer (CRPC) progression. Also, an antisense oligonucleotide (ASO) against Hsp27 (OGX-427 or apatorsen) has been assessed in different clinical trials. Here, we illustrate that Hsp27 highly regulates the expression of the human DEAD-box protein 5 (DDX5), and we define DDX5 as a novel therapeutic target for CRPC treatment. DDX5 overexpression is strongly correlated with aggressive tumor features, notably with CRPC. DDX5 downregulation using a specific ASO-based inhibitor that acts on DDX5 mRNAs inhibits cell proliferation in preclinical models, and it particularly restores the treatment sensitivity of CRPC. Interestingly, through the identification and analysis of DDX5 protein interaction networks, we have identified some specific functions of DDX5 in CRPC that could contribute actively to tumor progression and therapeutic resistance. We first present the interactions of DDX5 and the Ku70/80 heterodimer and the transcription factor IIH, thereby uncovering DDX5 roles in different DNA repair pathways. Collectively, our study highlights critical functions of DDX5 contributing to CRPC progression and provides preclinical proof of concept that a combination of ASO-directed DDX5 inhibition with a DNA damage-inducing therapy can serve as a highly potential novel strategy to treat CRPC.

CRISPR screens reveal genetic determinants of PARP inhibitor sensitivity and resistance in prostate cancer

Prostate cancer harboring BRCA1/2 mutations are often exceptionally sensitive to PARP inhibitors. However, genomic alterations in other DNA damage response genes have not been consistently predictive of clinical response to PARP inhibition. Here, we perform genome-wide CRISPR-Cas9 knockout screens in BRCA1/2-proficient prostate cancer cells and identify previously unknown genes whose loss has a profound impact on PARP inhibitor response. Specifically, MMS22L deletion, frequently observed (up to 14%) in prostate cancer, renders cells hypersensitive to PARP inhibitors by disrupting RAD51 loading required for homologous recombination repair, although this response is TP53-dependent. Unexpectedly, loss of CHEK2 confers resistance rather than sensitivity to PARP inhibition through increased expression of BRCA2, a target of CHEK2-TP53-E2F7-mediated transcriptional repression. Combined PARP and ATR inhibition overcomes PARP inhibitor resistance caused by CHEK2 loss. Our findings may inform the use of PARP inhibitors beyond BRCA1/2-deficient tumors and support reevaluation of current biomarkers for PARP inhibition in prostate cancer.

In Vitro Antiproliferative Effects and Phytochemical Characterization of Carissa edulis ((Forssk) Vahl) and Pappea capensis (Eckyl and Zeyh) Extracts

Cancer mortality is a global concern. The current therapeutic approaches despite showing efficacy are characterized by several limitations. Search for alternatives has led to the use of herbal plants including C. edulis and P. capensis. However, there is limited research on antiproliferative effects of these medicinal plants. The study sought to evaluate antiproliferative effects of the plants against human breast and prostate cancers using cell viability, and gene expression assays to determine modulation of apoptotic genes. Further, Liquid Chromatography Mass Spectrophotometer (LC-MS) and Gas Chromatography Mass Spectrophotometer (GC-MS) analyses were performed to confirm phytocompounds in the extracts. The results indicated that ethylacetate extracts of C. edulis and P. capensis had the highest activity against cancer cells with IC50 values of 2.12 ± 0.02, and 6.57 ± 0.03 μg/ml on HCC 1395 and 2.92 ± 0.17 and 5.00 ± 0.17 μg/ml on DU145, respectively. Moreover, the plants extracts exhibited relatively less cytotoxic activities against Vero cell lines (IC50 > 20 μg/ml). The extracts also exhibit selectivity against the cancer cells (SI > 3). Further, mRNA expression of p53 in the treated HCC 1395 was increased by 7 and 3-fold, whereas by 3 and 2-fold in DU145 cells, upon treatment with ethylacetate extracts of C. edulis and P. capensis, respectively. Similarly, several-fold increases were observed in the number of transcripts of Bax in HCC 1395 and HOXB13 in DU145 cells. Phytochemical analyses detected presence of phytocompounds including flavonoids, phenolics, tocopherols and terpenoids which are associated with anticancer activity. Findings from this study provide a scientific validation for the folklore use of these plants in management of cancer.

Antrodia salmonea Extracts Regulate p53-AR Signaling and Apoptosis in Human Prostate Cancer LNCaP Cells

Antrodia salmonea (AS) is a genus of Antrodia, an epiphyte of Cunninghamia konishii in Taiwan. AS has been reported to have potential therapeutic effects on different diseases, including diarrhea, abdominal pain, and hypertension. AS has been reported to have anticancer effects on numerous cancer types, such as ovarian carcinoma and triple-negative breast cancer. Our previous studies demonstrated that antrocins and triterpenoids are possibly bioactive compositions. However, the effects of AS on prostate cancer remain unknown. Therefore, we investigated the role of AS in prostate cancer growth, apoptosis, and cell cycle regulation. The results showed that AS extracts significantly inhibited the proliferation of prostate cancer LNCaP cells in a dose-dependent manner and increased the levels of apoptotic markers (cleaved PARP and cleaved caspase 3/8/9). In addition, the cell cycle-related proteins CDK1, CDK2, CDK4, and their respective specific regulators Cyclin B1, Cyclin A, and Cyclin D were also affected. Besides, AS treatment increased p53 protein levels and slowed its degradation in LNCaP cells. Interestingly, we found that AS treatment reduced both total protein and Ser-81 phosphorylation levels of the androgen receptor (AR). Notably, the increase of nuclear p53 was accompanied by the down-regulation of AR, suggesting a reverse regulation between p53 and AR in LNCaP cells was triggered by AS treatment. These findings suggest that AS extracts trigger the apoptosis of prostate cancer cells through the reverse regulation of p53 and AR and elucidate that AS extracts might be a potential treatment for androgen-dependent prostate cancer in the near future.

Exosome secretion and cellular response of DU145 and PC3 after exposure to alpha radiation

Exosomes are spherical membrane nanovesicles secreted from cells, and they play an important role in tumor immune response, metastasis, angiogenesis, and survival. Studies investigating exosomes isolated from cells exposed to photon radiation commonly used in conventional radiotherapy demonstrate the influence of this type of radiation on exosome characteristics and secretion. There is currently no research investigating the effects of densely ionizing particles such as protons and alpha radiation on exosomes. Thus we have evaluated the cellular response of human prostate cancer cells exposed to 0, 2, and 6 Gy of alpha radiation emitted from the Am-241 source. Irradiated PC3 and DU145 cell lines, characterized by differences in radiosensitivity, were studied using apoptosis, LDH, and IL-6 assays. Additionally, the corresponding concentration and size of isolated exosomes were measured using NTA. We found that exposure to ionizing radiation resulted in gross changes in viability and cell damage. There were increased amounts of apoptotic or necrotic cells as a function of radiation dose. We demonstrated that irradiated PC3 cells secrete higher quantities of exosomes compared to DU145 cells. Additionally, we also found no statistical difference in exosome size for control and irradiated cells.

Biological Response of Human Cancer Cells to Ionizing Radiation in Combination with Gold Nanoparticles

Simple Summary

Various types of metallic nanoparticles and especially gold nanoparticles (AuNPs) have been utilized in radiation studies to enhance the radiosensitization of cancer cells while minimizing detrimental effects in normal tissue. The aim of our study was to investigate the biological responses of various human cancer cells to gold-nanoparticle-induced radiosensitization. This was accomplished by using different AuNPs and several techniques in order to provide valuable insights regarding the multiple adverse biological effects, following ionizing radiation (IR) in combination with AuNPs. Insightful methodologies such as transmission electron microscopy were employed to identify comprehensively the complexity of the biological damage occurrence. Our findings confirm that AuNP radiosensitization may occur due to extensive and/or complex DNA damage, cell death, or cellular senescence. This multiparameter study aims to further elucidate the biological mechanisms and at the same time provide new information regarding the use of AuNPs as radiosensitizers in cancer treatment.

Abstract

In the context of improving radiation therapy, high-atomic number (Z) metallic nanoparticles and, more importantly, gold-based nanostructures are developed as radiation enhancers/radiosensitizers. Due to the diversity of cell lines, nanoparticles, as well as radiation types or doses, the resulting biological effects may differ and remain obscure. In this multiparameter study, we aim to shed light on these effects and investigate them further by employing X-irradiation and three human cancer cell lines (PC3, A549, and U2OS cells) treated by multiple techniques. TEM experiments on PC3 cells showed that citrate-capped AuNPs were found to be located mostly in membranous structures/vesicles or autophagosomes, but also, in the case of PEG-capped AuNPs, inside the nucleus as well. The colony-forming capability of cancer cells radiosensitized by AuNPs decreased significantly and the DNA damage detected by cytogenetics, γH2AX immunostaining, and by single (γH2AX) or double (γH2AX and OGG1) immunolocalization via transmission electron microscopy (TEM) was in many cases higher and/or persistent after combination with AuNPs than upon individual exposure to ionizing radiation (IR). Moreover, different cell cycle distribution was evident in PC3 but not A549 cells after treatment with AuNPs and/or irradiation. Finally, cellular senescence was investigated by using a newly established staining procedure for lipofuscin, based on a Sudan Black-B analogue (GL13) which showed that based on the AuNPs’ concentration, an increased number of senescent cells might be observed after exposure to IR. Even though different cell lines or different types and concentrations of AuNPs may alter the levels of radiosensitization, our results imply that the complexity of damage might also be an important factor of AuNP-induced radiosensitization.

Silibinin Radiosensitizes EGF Receptor-knockdown Prostate Cancer Cells by Attenuating DNA Repair Pathways

Emergence of radioresistance in prostate cancer (PCa) cells is a major obstacle in cancer therapy and contributes to the relapse of the disease. EGF receptor (EGFR) signaling plays an important role in the development of radioresistance. Herein, we have assessed the modulatory effects of silibinin on radiation-induced resistance via DNA repair pathways in EGFR-knockdown DU145 cells. shRNA-based silencing of EGFR was done in radioresistant human PCa DU145 cells and effects of ionizing radiation (IR) and silibinin were assessed using clonogenic and trypan blue assays. Furthermore, radiosensitizing effects of silibinin on PCa in context with EGFR were analyzed using flow cytometry, comet assay, and immunoblotting. Silibinin decreased the colony formation ability with an increased death of DU145 cells exposed to IR (5 Gray), with a concomitant decrease in Rad51 protein expression. Silibinin (25 μM) augmented the IR-induced cytotoxic effect in EGFR-knockdown PCa cells, along with induction of G2/M phase cell cycle arrest. Further, we studied homologous recombination (HR) and non-homologous end joining (NHEJ) pathways in silibinin-induced DNA double-strand breaks in EGFR-knockdown DU145 cells. Silibinin down-regulated the expression of Rad51 and DNA-dependent protein kinase proteins without any considerable effect on Ku70 and Ku80 in IR-exposed EGFR-knockdown PCa cells. The pro-survival signaling proteins, phospho-extracellular signal-regulated kinases (ERK)1/2, phospho-Akt and phospho-STAT3 were decreased by silibinin in EGFR-deficient PCa cells. These findings suggest a novel mechanism of silibinin-induced radiosensitization of PCa cells by targeting DNA repair pathways, HR and NHEJ, and suppressing the pro-survival signaling pathways, ERK1/2, Akt and STAT3, in EGFR-knockdown PCa cells.

Based on network pharmacology and molecular docking to predict the mechanism of Huangqi in the treatment of castration-resistant prostate cancer

Background

As a kind of traditional Chinese medicine, HQ is widely mentioned in the treatment of cancerous diseases in China, which has been proven to have a therapeutic effect on cancerous diseases, such as prostate cancer. To predict the specific mechanism of HQ in the treatment of CRPC, we will conduct preliminary verification and discussion based on a comprehensive consideration of network pharmacology and molecular docking.

Methods

TCMSP was used to obtain the compounds and reach the effective targets of HQ. The targets of CRPC were reached based on GeneCards database and CTD database. GO and KEGG were utilized for the analysis of overlapping targets. The software of Openbabel was used to convert the formats of ligands and reporters. In addition, molecular docking studies were performed by using the software of Autodock Vina.

Result

It can be seen from the database results that there were 87 active compounds (20 key active compounds) in HQ, and 33 targets were screened out for CRPC treatment. GO and KEGG pathway enrichment analyses identified 81 significant GO terms and 24 significant KEGG pathways. There is a difference in terms of the expression of core protein between cancer patients and healthy people. The expression of core protein in patients also has an impact on the life cycle. The results of molecular docking showed that the docking activity of drug molecules and core proteins was better.

Conclusions

It is concluded from the results of this network pharmacology and molecular docking that HQ makes a multi-target and multi-biological process, and results in the multi-channel synergistic effect on the treatment of CRPC by regulating cell apoptosis, proliferation and metastasis, which still needs further verification by experimental research.

Novel MDM2 Inhibitor XR-2 Exerts Potent Anti-Tumor Efficacy and Overcomes Enzalutamide Resistance in Prostate Cancer

Background: The inactivation of tumor-suppressor p53 plays an important role in second generation anti-androgens (SGAs) drug resistance and neuroendocrine differentiation in castration-resistant prostate cancer (CRPC). The reactivation of p53 by blocking the MDM2–p53 interaction represents an attractive therapeutic remedy in cancers with wild-type or functional p53. Whether MDM2-p53 inhibitor could overcome SGAs drug resistance in CRPC is still needed further research. Here, we investigated the anti-tumor efficacy and mechanisms of a novel MDM2-p53 inhibitor XR-2 in CRPC.

Methods: To investigate the functions and mechanisms of XR-2 in prostate cancer, in vitro and in vivo biofunctional assays were performed. Western blot and qRT-PCR assay were performed to detect the protein and mRNA expression levels of indicated genes. CCK8, colony formation, flow cytometry and senescence assays were performed for cell function identifications. RNA-sequencing and bioinformatics analysis were mainly used to identify the influence of XR-2 on prostate cancer cells transcriptome. Subcutaneous 22Rv1 derived xenografts mice model was used to investigate the in vivo anti-tumor activity of XR-2. In addition, the broad-spectrum anti-tumor activities in vivo of XR-2 were evaluated by different xenografts mice models.

Results: XR-2 could directly bind to MDM2, potently reactivate the p53 pathway and thus induce cell cycle arrest and apoptosis in wild-type p53 CRPC cell lines. XR-2 also suppresses the AR pathway as p53 regulates AR transcription inhibition and MDM2 participates in AR degradation. As a result, XR-2 efficiently inhibited CRPC cell viability, showed a synergistic effect with enzalutamide and overcame enzalutamide resistance both in vitro and in vivo. Moreover, results illustrated that XR-2 possesses broad-spectrum anti-tumor activities in vivo with favourable safety.

Conclusion: MDM2-p53 inhibitor (XR-2) possesses potently prostate cancer progresses inhibition activity both in vitro and in vivo. XR-2 shows a synergistic effect with enzalutamide and overcomes enzalutamide resistance.

Statins and prostate cancer-hype or hope? The biological perspective

Growing evidence suggests that men prescribed a statin for cholesterol control have a lower risk of advanced prostate cancer (PCa) and improved treatment outcomes; however, the mechanism by which statins elicit their anti-neoplastic effects is not well understood and is likely multifaceted. Statins are potent and specific inhibitors of 3-hydroxy-3-methylglutaryl coenzyme A reductase (HMGCR), the rate-limiting enzyme of the mevalonate (MVA) metabolic pathway. This two-part series is a review of the observational and experimental data on statins as anti-cancer agents in PCa. In this article, we describe the functional role that deregulated MVA metabolism plays in PCa progression and summarize the biological evidence and rationale for targeting the MVA pathway, with statins and other agents, for the treatment of PCa.

S-Adenosylmethionine affects ERK1/2 and STAT3 pathway in androgen-independent prostate cancer cells

Background

The most critical point in the treatment of prostate cancer is the progression towards a hormone-refractory tumour, making research on alternative therapies necessary. This study focused on the methyl donor S-adenosylmethionine (SAM), which is known to act as an antitumourigenic in several cancer cell lines. Though a genome-wide downregulation of proto-oncogenes in prostate cancer cell lines treated with SAM is obvious, the anticancer effects remain elusive. Thus, in this study, the impact of SAM treatment on the cell cycle, apoptosis and cancer-related pathways was investigated.

Methods and results

After performing SAM treatment on prostate cancer cell lines (PC-3 and DU145), a cell-cycle arrest during the S-phase, a downregulation of cyclin A protein levels and an upregulation of p21 cell cycle inhibitor were observed. The proapoptotic Bax/Bcl-2 ratio and the caspase-3 activity were elevated; additionally, the apoptosis rate of SAM treated cells increased significantly in a time-dependent manner. Moreover, immunoblots displayed a downregulation of Erk1/2 and STAT3 phosphorylation accompanied by a reduced expression of the STAT3 protein.

Conclusion

SAM caused changes in cancer-related pathways, probably leading to the effects on the cell cycle and apoptosis rate. These results provide deeper insights into the anticancer effects of SAM on prostate cancer cells.

RB1 loss overrides PARP inhibitor sensitivity driven by RNASEH2B loss in prostate cancer

Current targeted cancer therapies are largely guided by mutations of a single gene, which overlooks concurrent genomic alterations. Here, we show that RNASEH2B, RB1, and BRCA2, three closely located genes on chromosome 13q, are frequently deleted in prostate cancer individually or jointly. Loss of RNASEH2B confers cancer cells sensitivity to poly(ADP-ribose) polymerase (PARP) inhibition due to impaired ribonucleotide excision repair and PARP trapping. When co-deleted with RB1, however, cells lose their sensitivity, in part, through E2F1-induced BRCA2 expression, thereby enhancing homologous recombination repair capacity. Nevertheless, loss of BRCA2 resensitizes RNASEH2B/RB1 co-deleted cells to PARP inhibition. Our results may explain some of the disparate clinical results from PARP inhibition due to interaction between multiple genomic alterations and support a comprehensive genomic test to determine who may benefit from PARP inhibition. Last, we show that ATR inhibition can disrupt E2F1-induced BRCA2 expression and overcome PARP inhibitor resistance caused by RB1 loss.

Electrochemical LAMP-based assay for detection of RNA biomarkers in prostate cancer

Current molecular diagnostics of prostate cancer relies on detection of elevated levels of PSA protein in serum, but its specificity has been questioned due to its higher levels also in non-malignant prostate diseases. A long non-coding RNA biomarker, PCA3, demonstrated excellent specificity for prostate cancer, and thus has become an interesting alternative to PSA monitoring. Its detection utilizes mostly reverse transcription PCR with optical detection, making the protocol longer and more expensive. To avoid PCR, we have developed an electrochemical assay coupled with LAMP, an isothermal amplification technique showing high sensitivities at constant temperatures and shorter reaction times. We amplified PCA3 RNA as well as PSA mRNA (serving as a control), hybridized LAMP products on magnetic beads and measured them with chronoamperometry at carbon electrode chips. We show good sensitivity and specificity for both biomarkers in prostate cancer cell lines, and successful detection of PCA3 in clinical samples, i.e., urine samples from 11 prostate cancer patients and 7 healthy controls, where we obtained excellent correlation with clinical data. This is to our knowledge a first such attempt to apply electrochemistry to determine two RNA biomarkers directly in urine samples of prostate cancer patients in a minimally invasive diagnostics format.

What Do We Have to Know about PD-L1 Expression in Prostate Cancer? A Systematic Literature Review (Part 6): Correlation of PD-L1 Expression with the Status of Mismatch Repair System, BRCA, PTEN, and Other Genes

Pembrolizumab (anti-PD-1) is allowed in selected metastatic castration-resistant prostate cancer (PC) patients showing microsatellite instability/mismatch repair system deficiency (MSI-H/dMMR). BRCA1/2 loss-of-function is linked to hereditary PCs and homologous recombination DNA-repair system deficiency: poly-ADP-ribose-polymerase inhibitors can be administered to BRCA-mutated PC patients. Recently, docetaxel-refractory metastatic castration-resistant PC patients with BRCA1/2 or ATM somatic mutations had higher response rates to pembrolizumab. PTEN regulates cell cycle/proliferation/apoptosis through pathways including the AKT/mTOR, which upregulates PD-L1 expression in PC. Our systematic literature review (PRISMA guidelines) investigated the potential correlations between PD-L1 and MMR/MSI/BRCA/PTEN statuses in PC, discussing few other relevant genes. Excluding selection biases, 74/677 (11%) PCs showed dMMR/MSI; 8/67 (12%) of dMMR/MSI cases were PD-L1+. dMMR-PCs included ductal (3%) and acinar (14%) PCs (all cases tested for MSI were acinar-PCs). In total, 15/39 (39%) PCs harbored BRCA1/2 aberrations: limited data are available for PD-L1 expression in these patients. 13/137 (10%) PTEN- PCs were PD-L1+; 10/29 (35%) PD-L1+ PCs showed PTEN negativity. SPOP mutations may increase PD-L1 levels, while the potential correlation between PD-L1 and ERG expression in PC should be clarified. Further research should verify how the efficacy of PD-1 inhibitors in metastatic castration-resistant PCs is related to dMMR/MSI, DNA-damage repair genes defects, or PD-L1 expression.

Targeting mutant p53 for cancer therapy: direct and indirect strategies

TP53 is a critical tumor-suppressor gene that is mutated in more than half of all human cancers. Mutations in TP53 not only impair its antitumor activity, but also confer mutant p53 protein oncogenic properties. The p53-targeted therapy approach began with the identification of compounds capable of restoring/reactivating wild-type p53 functions or eliminating mutant p53. Treatments that directly target mutant p53 are extremely structure and drug-species-dependent. Due to the mutation of wild-type p53, multiple survival pathways that are normally maintained by wild-type p53 are disrupted, necessitating the activation of compensatory genes or pathways to promote cancer cell survival. Additionally, because the oncogenic functions of mutant p53 contribute to cancer proliferation and metastasis, targeting the signaling pathways altered by p53 mutation appears to be an attractive strategy. Synthetic lethality implies that while disruption of either gene alone is permissible among two genes with synthetic lethal interactions, complete disruption of both genes results in cell death. Thus, rather than directly targeting p53, exploiting mutant p53 synthetic lethal genes may provide additional therapeutic benefits. Additionally, research progress on the functions of noncoding RNAs has made it clear that disrupting noncoding RNA networks has a favorable antitumor effect, supporting the hypothesis that targeting noncoding RNAs may have potential synthetic lethal effects in cancers with p53 mutations. The purpose of this review is to discuss treatments for cancers with mutant p53 that focus on directly targeting mutant p53, restoring wild-type functions, and exploiting synthetic lethal interactions with mutant p53. Additionally, the possibility of noncoding RNAs acting as synthetic lethal targets for mutant p53 will be discussed.

Ceramide Regulates Anti-Tumor Mechanisms of Erianin in Androgen-Sensitive and Castration-Resistant Prostate Cancers

Prostate cancer is the second most prevalent malignancy worldwide. In the early stages, the development of prostate cancer is dependent on androgens. Over time with androgen deprivation therapy, 20% of prostate cancers progress to a castration-resistant form. Novel treatments for prostate cancers are still urgently needed. Erianin is a plant-derived bibenzyl compound. We report herein that erianin exhibits anti-tumor effects in androgen-sensitive and castration-resistant prostate cancer cells through different mechanisms. Erianin induces endoplasmic reticulum stress-associated apoptosis in androgen-sensitive prostate cancer cells. It also triggers pro-survival autophagic responses, as inhibition of autophagy predisposes to apoptosis. In contrast, erianin fails to induce apoptosis in castration-resistant prostate cancer cells. Instead, it results in cell cycle arrest at the M phase. Mechanistically, C16 ceramide dictates differential responses of androgen-sensitive and castration-resistant prostate cancer cells to erianin. Erianin elevates C16 ceramide level in androgen-sensitive but not castration-resistant prostate cancer cells. Overexpression of ceramide synthase 5 that specifically produces C16 ceramide enables erianin to induce apoptosis in castration-resistant prostate cancer cells. Our study provides both experimental evidence and mechanistic data showing that erianin is a potential treatment option for prostate cancers.

miR-425-5p as an exosomal biomarker for metastatic prostate cancer

Prostate cancer-related deaths are mostly caused by metastasis, which indicates the importance of identifying clinical prognostic biomarkers. In this study, we evaluated the expression profile of exosomal microRNAs (miRNAs) derived from metastatic prostate cancer (mPCa) cell lines (LNCaP and PC-3). miRNA signatures in exosomes and cells were evaluated by miRNA microarray analysis. Fourteen miRNAs were identified as candidates for specific noninvasive biomarkers. The expression of five miRNAs was validated using RT-qPCR, which confirmed that miR-205-5p, miR-148a-3p, miR-125b-5p, miR-183-5p, and miR-425-5p were differentially expressed in mPCa exosomes. Bioinformatic analyses showed that miR-425-5p was associated with residual tumor, pathologic T and N stages, and TP53 status in PCa samples. Gene ontology analysis of negatively correlated and predicted targeted genes showed enrichment of genes related to bone development pathways. The LinkedOmics database indicated that the potential target HSPB8 has a significant negative correlation with miR-425-5p. In conclusion, this study identified a panel of exosomal miRNAs with potential value as prognostic biomarkers for prostate cancer.

Androgen Receptor Signaling in Prostate Cancer Genomic Subtypes

While many prostate cancer (PCa) cases remain indolent and treatable, others are aggressive and progress to the metastatic stage where there are limited curative therapies. Androgen receptor (AR) signaling remains an important pathway for proliferative and survival programs in PCa, making disruption of AR signaling a viable therapy option. However, most patients develop resistance to AR-targeted therapies or inherently never respond. The field has turned to PCa genomics to aid in stratifying high risk patients, and to better understand the mechanisms driving aggressive PCa and therapy resistance. While alterations to the AR gene itself occur at later stages, genomic changes at the primary stage can affect the AR axis and impact response to AR-directed therapies. Here, we review common genomic alterations in primary PCa and their influence on AR function and activity. Through a meta-analysis of multiple independent primary PCa databases, we also identified subtypes of significantly co-occurring alterations and examined their combinatorial effects on the AR axis. Further, we discussed the subsequent implications for response to AR-targeted therapies and other treatments. We identified multiple primary PCa genomic subtypes, and given their differing effects on AR activity, patient tumor genetics may be an important stratifying factor for AR therapy resistance.

Dispirooxindoles Based on 2-Selenoxo-Imidazolidin-4-Ones: Synthesis, Cytotoxicity and ROS Generation Ability

A regio- and diastereoselective synthesis of two types of dispiro derivatives of 2-selenoxoimidazolidin-4-ones, differing in the position of the nitrogen atom in the central pyrrolidine ring of the spiro-fused system-namely, 2-selenoxodispiro[imidazolidine-4,3'-pyrrolidine-2',3″-indoline]-2″,5-diones (5a-h) and 2-senenoxodispiro[imidazolidine-4,3'-pyrrolidine-4',3″-indoline]-2″,5-diones (6a-m)-were developed based on a 1,3-dipolar cycloaddition of azomethine ylides generated from isatin and sarcosine or formaldehyde and sarcosine to 5-arylidene or 5-indolidene-2-selenoxo-tetrahydro-4H-imidazole-4-ones. Selenium-containing dispiro indolinones generally exhibit cytotoxic activity near to the activity of the corresponding oxygen and sulfur-containing derivatives. Compounds 5b, 5c, and 5e demonstrated considerable in vitro cytotoxicity in the 3-(4,5-dimethylthiazol-2-yl)2,5-diphenyl tetrazolium bromide (MTT) test (concentration of compounds that caused 50% death of cells (CC₅₀) 7.6-8.7 μM) against the A549 cancer cell line with the VA13/A549 selectivity index 5.2-6.9; some compounds (5 and 6) increased the level of intracellular reactive oxygen species (ROS) in the experiment on A549 and PC3 cells using platinized carbon nanoelectrode. The tests for p53 activation for compounds 5 and 6 on the transcriptional reporter suggest that the investigated compounds can only have an indirect p53-dependent mechanism of action. For the compounds 5b, 6b, and 6l, the ROS generation may be one of the significant mechanisms of their cytotoxic action.

In Vivo Imaging of Methionine Aminopeptidase II for Prostate Cancer Risk Stratification

Prostate cancer is one of the most common malignancies worldwide, yet limited tools exist for prognostic risk stratification of the disease. Identification of new biomarkers representing intrinsic features of malignant transformation and development of prognostic imaging technologies are critical for improving treatment decisions and patient survival. In this study, we analyzed radical prostatectomy specimens from 422 patients with localized disease to define the expression pattern of methionine aminopeptidase II (MetAP2), a cytosolic metalloprotease that has been identified as a druggable target in cancer. MetAP2 was highly expressed in 54% of low-grade and 59% of high-grade cancers. Elevated levels of MetAP2 at diagnosis were associated with shorter time to recurrence. Controlled self-assembly of a synthetic small molecule enabled design of the first MetAP2-activated PET imaging tracer for monitoring MetAP2 activity in vivo. The nanoparticles assembled upon MetAP2 activation were imaged in single prostate cancer cells with post-click fluorescence labeling. The fluorine-18-labeled tracers successfully differentiated MetAP2 activity in both MetAP2-knockdown and inhibitor-treated human prostate cancer xenografts by micro-PET/CT scanning. This highly sensitive imaging technology may provide a new tool for noninvasive early-risk stratification of prostate cancer and monitoring the therapeutic effect of MetAP2 inhibitors as anticancer drugs. SIGNIFICANCE: This study defines MetAP2 as an early-risk stratifier for molecular imaging of aggressive prostate cancer and describes a MetAP2-activated self-assembly small-molecule PET tracer for imaging MetAP2 activity in vivo.

Cytostatic Action of Novel Histone Deacetylase Inhibitors in Androgen Receptor-Null Prostate Cancer Cells

Androgen receptor (AR)-null prostate tumors have been observed in 11-24% of patients. Histone deacetylases (HDACs) are overexpressed in prostate tumors. Therefore, HDAC inhibitors (Jazz90 and Jazz167) were examined in AR-null prostate cancer cell lines (PC3 and DU145). Both Jazz90 and Jazz167 inhibited the growth of PC3 and DU145 cells. Jazz90 and Jazz167 were more active in PC3 cells and DU145 cells in comparison to normal prostate cells (PNT1A) and showed a 2.45- and 1.30-fold selectivity and higher cytotoxicity toward DU145 cells, respectively. Jazz90 and Jazz167 reduced HDAC activity by ~60% at 50 nM in PC3 lysates. At 4 μM, Jazz90 and Jazz167 increased acetylation in PC3 cells by 6- to 8-fold. Flow cytometry studies on the cell phase distribution demonstrated that Jazz90 causes a G0/G1 arrest in AR-null cells, whereas Jazz167 leads to a G0/G1 arrest in DU145 cells. However, apoptosis only occurred at a maximum of 7% of the total cell population following compound treatments in PC3 and DU145 cells. There was a reduction in cyclin D1 and no significant changes in bcl-2 in DU145 and PC3 cells. Overall, the results showed that Jazz90 and Jazz167 function as cytostatic HDAC inhibitors in AR-null prostate cancer cells.

Sensitivity of pancreatic cancer cells to chemotherapeutic drugs, signal transduction inhibitors and nutraceuticals can be regulated by WT-TP53

Pancreatic ductal adenocarcinoma (PDAC) is a highly metastatic malignancy. Approximately 85% of pancreatic cancers are classified as PDACs. The survival of PDAC patients is very poor and only 5-10% of patients survive 5 years after diagnosis. Mutations at the KRAS and TP53 gene are frequently observed in PDAC patients. The PANC-28 cell line lacks wild-type (WT) TP53. In the following study, we have investigated the effects of restoration of WT TP53 activity on the sensitivity of PANC-28 pancreatic cancer cells to various drugs which are used to treat PDAC patients as well as other cancer patients. In addition, we have examined the effects of signal transduction inhibitors which target critical pathways frequently deregulated in cancer. The effects of the anti-diabetes drug metformin and the anti-malarial drug chloroquine were also examined as these drugs may be repurposed to treat other diseases. Finally, the effects of certain nutraceuticals which are used to treat various ailments were also examined. Introduction of WT-TP53 activity in PANC-28 PDAC cells, can increase their sensitivity to various drugs. Attempts are being made clinically to increase TP53 activity in various cancer types which will often inhibit cell growth by multiple mechanisms.

tRNALys-Derived Fragment Alleviates Cisplatin-Induced Apoptosis in Prostate Cancer Cells

Cisplatin is a standard treatment for prostate cancer, which is the third leading cause of cancer-related deaths among men globally. However, patients who have undergone cisplatin can rxperience relapse. tRNA-derived fragments (tRFs) are small non-coding RNAs generated via tRNA cleavage; their physiological activities are linked to the development of human diseases. Specific tRFs, including tRF-315 derived from tRNA^Lys, are highly expressed in prostate cancer patients. However, whether tRF-315 regulates prostate cancer cell proliferation or apoptosis is unclear. Herein, we confirmed that tRF-315 expression was higher in prostate cancer cells (LNCaP, DU145, and PC3) than in normal prostate cells. tRF-315 prevented cisplatin-induced apoptosis and alleviated cisplatin-induced mitochondrial dysfunction in LNCaP and DU145 cells. Moreover, transfection of tRF-315 inhibitor increased the expression of apoptotic pathway-related proteins in LNCaP and DU145 cells. Furthermore, tRF-315 targeted the tumor suppressor gene GADD45A, thus regulating the cell cycle, which was altered by cisplatin in LNCaP and DU145 cells. Thus, tRF-315 protects prostate cancer cells from mitochondrion-dependent apoptosis induced by cisplatin treatment.

Aneuploidy increases resistance to chemotherapeutics by antagonizing cell division

Aneuploidy, defined as whole chromosome gains and losses, is associated with poor patient prognosis in many cancer types. However, the condition causes cellular stress and cell cycle delays, foremost in G1 and S phase. Here, we investigate how aneuploidy causes both slow proliferation and poor disease outcome. We test the hypothesis that aneuploidy brings about resistance to chemotherapies because of a general feature of the aneuploid condition-G1 delays. We show that single chromosome gains lead to increased resistance to the frontline chemotherapeutics cisplatin and paclitaxel. Furthermore, G1 cell cycle delays are sufficient to increase chemotherapeutic resistance in euploid cells. Mechanistically, G1 delays increase drug resistance to cisplatin and paclitaxel by reducing their ability to damage DNA and microtubules, respectively. Finally, we show that our findings are clinically relevant. Aneuploidy correlates with slowed proliferation and drug resistance in the Cancer Cell Line Encyclopedia (CCLE) dataset. We conclude that a general and seemingly detrimental effect of aneuploidy, slowed proliferation, provides a selective benefit to cancer cells during chemotherapy treatment.

Etoposide Loaded SPION-PNIPAM Nanoparticles Improve the in vitro Therapeutic Outcome on Metastatic Prostate Cancer Cells via Enhanced Apoptosis

Prostate cancer is among the leading causes of death worldwide because its metastatic form is a deadly disease. Therefore, the development of new chemotherapeutics is of immense importance. Nanoparticle technology seems to provide diverse options in this regard. Therefore, poly(N-isopropylacrylamide) (PNIPAM) coated superparamagnetic iron oxide nanoparticles (SPION) loaded with Etoposide were prepared in small sizes (57 nm) and with 3.5 % drug content to improve the efficiency of Etoposide in prostate cancer therapy. Sustained release of the drug was achieved, which found to be sensitive to low pH and high temperature. The anti-growth activity of SPION-PNIPAM-Etoposide formulation against metastatic prostate cancer cells (PC-3, LNCaP) were investigated by SRB assay, then, confirmed by ATP assay. Mode of cell death was evaluated by using flow cytometry analyses. A significant improvement of nanoformulated drug was observed at 5-10 μg/ml doses of the drug in both cell lines. More importantly, this formulation enhanced the cytotoxic effect of Etoposide on PC-3 cells, which is considered more resistant to Etoposide than LNCaP and reduced the IC₅₀ value by 55 % reaching to 4.5 μg drug/ml, which is a very significant improvement in the literature. It was clearly shown that nanoformulated drug provided about 3-fold increases in caspase-dependent early apoptotic cells in PC-3 cells. The novel formulation seems to successfully cause cell death of especially PC-3 metastatic prostate cancer cells. It should therefore be taken into consideration for further animal studies as a novel potent anticancer agent.

Serum deprivation initiates adaptation and survival to oxidative stress in prostate cancer cells

Inadequate nutrient intake leads to oxidative stress disrupting homeostasis, activating signaling, and altering metabolism. Oxidative stress serves as a hallmark in developing prostate lesions, and an aggressive cancer phenotype activating mechanisms allowing cancer cells to adapt and survive. It is unclear how adaptation and survival are facilitated; however, literature across several organisms demonstrates that a reversible cellular growth arrest and the transcription factor, nuclear factor-kappaB (NF-κB), contribute to cancer cell survival and therapeutic resistance under oxidative stress. We examined adaptability and survival to oxidative stress following nutrient deprivation in three prostate cancer models displaying varying degrees of tumorigenicity. We observed that reducing serum (starved) induced reactive oxygen species which provided an early oxidative stress environment and allowed cells to confer adaptability to increased oxidative stress (H₂O₂). Measurement of cell viability demonstrated a low death profile in stressed cells (starved + H₂O₂), while cell proliferation was stagnant. Quantitative measurement of apoptosis showed no significant cell death in stressed cells suggesting an adaptive mechanism to tolerate oxidative stress. Stressed cells also presented a quiescent phenotype, correlating with NF-κB nuclear translocation, suggesting a mechanism of tolerance. Our data suggests that nutrient deprivation primes prostate cancer cells for adaptability to oxidative stress and/or a general survival mechanism to anti-tumorigenic agents.

Identification of candidate miRNAs in early-onset and late-onset prostate cancer by network analysis

The incidence of patients under 55 years old diagnosed with Prostate Cancer (EO-PCa) has increased during recent years. The molecular biology of PCa cancer in this group of patients remains unclear. Here, we applied weighted gene coexpression network analysis of the expression of miRNAs from 24 EO-PCa patients (38–45 years) and 25 late-onset PCa patients (LO-PCa, 71–74 years) to identify key miRNAs in EO-PCa patients. In total, 69 differentially expressed miRNAs were identified. Specifically, 26 and 14 miRNAs were exclusively deregulated in young and elderly patients, respectively, and 29 miRNAs were shared. We identified 20 hub miRNAs for the network built for EO-PCa. Six of these hub miRNAs exhibited prognostic significance in relapse‐free or overall survival. Additionally, two of the hub miRNAs were coexpressed with mRNAs of genes previously identified as deregulated in EO-PCa and in the most aggressive forms of PCa in African-American patients compared with Caucasian patients. These genes are involved in activation of immune response pathways, increased rates of metastasis and poor prognosis in PCa patients. In conclusion, our analysis identified miRNAs that are potentially important in the molecular pathology of EO-PCa. These genes may serve as biomarkers in EO-PCa and as possible therapeutic targets.

Pheophorbide a-mediated sonodynamic, photodynamic and sonophotodynamic therapies against prostate cancer

Anticancer efficiencies and mechanisms of Pheophorbide-a-mediated photodynamic, sonodynamic and sonophotodynamic therapies were investigated in vitro using androgen-sensitive (LNCaP) and androgen insensitive (PC3) prostate cancer cell lines. The cells were incubated in RPMI-1640 media at various concentrations of Pheophorbide-a. The media was treated with 0.5 W/cm² ultrasound and/or 0.5 mJ/cm² light irradiation. Cell proliferation in both cell lines was inhibited most effectively by sonophotodynamic therapy in comparison to that of both monotherapies. LNCaP cells were more sensitive to the applied treatments and the cell survival in LNCaP cell line was observed to be less than that of PC3 cell line. The results of histochemical analysis showed that there were more apoptotic cells in the treatment groups in comparison to control group. Additionally, the treatments induced apoptosis deduced by the overexpressed levels of caspase-3, caspase-8, PARP, and Bax proteins, while the expression levels of caspase-9 and Bcl-2 proteins were observed to be lower than those of control group. Treatments led to an increase in the oxidative stress markers, ROS and MDA, but a decrease in the activities of antioxidant enzymes, SOD, CAT and GSH. The results of this study revealed that Pheophorbide a-mediated sonophotodynamic therapy more efficiently activates the apoptotic mechanisms in prostate cancer cells and thus may provide a promising approach for treatment.

Influences of TP53 and the anti-aging DDR1 receptor in controlling Raf/MEK/ERK and PI3K/Akt expression and chemotherapeutic drug sensitivity in prostate cancer cell lines

Background: TP53 plays critical roles in sensitivity to chemotherapy, and aging. Collagen is very important in aging. The molecular structure and biochemical properties of collagen changes during aging. The discoidin domain receptor (DDR1) is regulated in part by collagen. Elucidating the links between TP53 and DDR1 in chemosensitivity and aging could improve therapies against cancer and aging.

Results: Restoration of WT-TP53 activity resulted in increased sensitivity to chemotherapeutic drugs and elevated expression of key components of the Raf/MEK/ERK, PI3K/Akt and DDR1 pathways. DDR1 could modulate the levels of Raf/MEK/ERK and PI3K/Akt pathways as well as sensitize the cells to chemotherapeutic drugs. In contrast, suppression of WT TP53 with a dominant negative (DN) TP53 gene, suppressed DDR1 protein levels and increased their chemoresistance.

Conclusion: Restoration of WT TP53 activity or increased expression of the anti-aging DDR1 collagen receptor can result in enhanced sensitivity to chemotherapeutic drugs. Our innovative studies indicate the important links between WT TP53 and DDR1 which can modulate Raf/MEK/ERK and PI3K/Akt signaling as well as chemosensitivity and aging.

Methods: We investigated the roles of wild type (WT) and mutant TP53 on drug sensitivity of prostate cancer cells and the induction of Raf/MEK/ERK, PI3K/Akt and DDR1 expression and chemosensitivity.

Synthesis and biological activity of 5-aryliden-2-thiohydantoin S-aryl derivatives

Three new and complementary approaches to S-arylation of 2-thiohydantoins have been developed: copper-catalyzed cross coupling with either arylboronic acids or aryl iodides under mild conditions, or direct nucleophilic substitution in activated aryl halides. For 38 diverse compounds, reaction yields for all three methods have been determined. Selected by molecular docking, they have been tested on androgen receptor activation, and p53-Mdm2 regulation, and A549, MCF7, VA13, HEK293T, PC3, LnCAP cell lines for cytotoxicity, Two of them turned out to be promising as androgen receptor activators (likely by allosteric regulation), and another one is shown to activate the p53 cascade. It is hoped that 2-thiohydantoin S-arylidenes are worth further studies as biologically active compounds.

p53/PGC‑1α‑mediated mitochondrial dysfunction promotes PC3 prostate cancer cell apoptosis

Data for p53 mutation in prostate cancer in The Cancer Genome Atlas database revealed that >85% of p53 mutations occurred in the p53 DNA binding domain. These mutations not only severely damage the function of the p53 protein, but also reduce the disease-free survival of patients. Peroxisome proliferator-activated receptor γ coactivator-1α (PGC-1α) is involved in the regulation of mitochondrial function and is highly expressed in prostate cancer PC3 and DU145 cells with p53 deletion or mutation. However, whether p53 negatively regulates PGC-1α in prostate cancer cells remains to be elucidated. In the present study, p53 overexpression was induced in prostate cancer PC3 cells. Subsequently, the expression levels of PGC-1α and alterations to mitochondrial function were assessed. Moreover, PGC-1α was activated in prostate cancer PC3 cells using ZLN005 to investigate alterations to mitochondrial function and cell apoptosis. The present study revealed that p53 decreased the expression and nuclear localization of the PGC-1α protein and induced mitochondrial dysfunction. Activation of PGC-1α partially reversed p53-mediated mitochondrial dysfunction. Inhibition of the p53/PGC-1α pathway on mitochondrial biogenesis and fission-/fusion-associated gene and protein expression were associated with mitochondrial dysfunction. p53/PGC-1α-mediated mitochondrial dysfunction promoted apoptosis of PC3 prostate cancer cells. The results indicated that PGC-1α is an essential target of p53-induced apoptosis in prostate cancer cells and indicated that targeting PGC-1α may provide a new therapeutic strategy for prostate cancer.

ATM-Deficient Cancers Provide New Opportunities for Precision Oncology

Poly-ADP ribose polymerase (PARP) inhibitors are currently used in the treatment of several cancers carrying mutations in the breast and ovarian cancer susceptibility genes BRCA1 and BRCA2, with many more potential applications under study and in clinical trials. Here, we discuss the potential for extending PARP inhibitor therapies to tumours with deficiencies in the DNA damage-activated protein kinase, Ataxia-Telangiectasia Mutated (ATM). We highlight our recent findings that PARP inhibition alone is cytostatic but not cytotoxic in ATM-deficient cancer cells and that the combination of a PARP inhibitor with an ATR (ATM, Rad3-related) inhibitor is required to induce cell death.

Cancer Cells Employ Nuclear Caspase-8 to Overcome the p53-Dependent G2/M Checkpoint through Cleavage of USP28

Cytosolic caspase-8 is a mediator of death receptor signaling. While caspase-8 expression is lost in some tumors, it is increased in others, indicating a conditional pro-survival function of caspase-8 in cancer. Here, we show that tumor cells employ DNA-damage-induced nuclear caspase-8 to override the p53-dependent G2/M cell-cycle checkpoint. Caspase-8 is upregulated and localized to the nucleus in multiple human cancers, correlating with treatment resistance and poor clinical outcome. Depletion of caspase-8 causes G2/M arrest, stabilization of p53, and induction of p53-dependent intrinsic apoptosis in tumor cells. In the nucleus, caspase-8 cleaves and inactivates the ubiquitin-specific peptidase 28 (USP28), preventing USP28 from de-ubiquitinating and stabilizing wild-type p53. This results in de facto p53 protein loss, switching cell fate from apoptosis toward mitosis. In summary, our work identifies a non-canonical role of caspase-8 exploited by cancer cells to override the p53-dependent G2/M cell-cycle checkpoint.

The Quantitative-Phase Dynamics of Apoptosis and Lytic Cell Death

Cell viability and cytotoxicity assays are highly important for drug screening and cytotoxicity tests of antineoplastic or other therapeutic drugs. Even though biochemical-based tests are very helpful to obtain preliminary preview, their results should be confirmed by methods based on direct cell death assessment. In this study, time-dependent changes in quantitative phase-based parameters during cell death were determined and methodology useable for rapid and label-free assessment of direct cell death was introduced. The goal of our study was distinction between apoptosis and primary lytic cell death based on morphologic features. We have distinguished the lytic and non-lytic type of cell death according to their end-point features (Dance of Death typical for apoptosis versus swelling and membrane rupture typical for all kinds of necrosis common for necroptosis, pyroptosis, ferroptosis and accidental cell death). Our method utilizes Quantitative Phase Imaging (QPI) which enables the time-lapse observation of subtle changes in cell mass distribution. According to our results, morphological and dynamical features extracted from QPI micrographs are suitable for cell death detection (76% accuracy in comparison with manual annotation). Furthermore, based on QPI data alone and machine learning, we were able to classify typical dynamical changes of cell morphology during both caspase 3,7-dependent and -independent cell death subroutines. The main parameters used for label-free detection of these cell death modalities were cell density (pg/pixel) and average intensity change of cell pixels further designated as Cell Dynamic Score (CDS). To the best of our knowledge, this is the first study introducing CDS and cell density as a parameter typical for individual cell death subroutines with prediction accuracy 75.4% for caspase 3,7-dependent and -independent cell death.

Topological properties and in vitro identification of essential nodes of the Paclitaxel and Vincristine interactomes in PC-3 cells

Background

Microtubule-targeting agents (MTAs) disrupt microtubule dynamics, thereby inducing apoptosis via mitochondrial pathway activation through the modulation in the expression of the Bcl-2 family.

Methods

To describe topological features of the MTAs networks associated to intrinsic apoptosis induction in p53-null prostate cancer cells, we predicted and compared the interactomes and topological properties of Paclitaxel and Vincristine, and thus, the essential nodes corresponding with the pro- and anti-apoptotic proteins and their kinetics were subjected to experimental analysis in PC-3 cell line.

Results

The essential nodes of the apoptotic pathways, TP53, and CASP3, were identified in both, Paclitaxel and Vincristine networks, but the intrinsic pathway markers BCL2, BAX, and BCL2L1 were identified as hub nodes only in the Paclitaxel network. An in vitro analysis demonstrated an increase in BimEL and the cleaved-caspase-3 proteins in PC-3 cells exposed to both treatments. Immunoprecipitation analysis showed that treatments induced the releasing of Bax from the anti-apoptotic complex with Bcl-2 protein and the role of BimEL as a de-repressor from sequestering complexes, in addition, new protein complexes were identified between BimEL or Bcl-2 and cleaved-caspase-3, contributing data to the Vincristine network for p53-null cells in response to MTAs.

Conclusion

The differences in sensitivities, protein profiles, and protein complex kinetics observed between the drugs confirmed that the selectivity and stimulation of the apoptotic system vary depending on the cell's genotype, the drug used and its exposure period.

An integrated enrichment system to facilitate isolation and molecular characterization of single cancer cells from whole blood

Circulating tumor cells (CTCs) carry valuable biological information. While enumeration of CTCs in peripheral blood is an FDA-approved prognostic indicator of survival in metastatic prostate and other cancers, analysis of CTC phenotypic and genomic markers is needed to identify cancer origin and elucidate pathways that can guide therapeutic selection for personalized medicine. Given the emergence of single-cell mRNA sequencing technologies, a method is needed to isolate CTCs with high sensitivity and specificity as well as compatibility with downstream genomic analysis. Flow cytometry is a powerful tool to analyze and sort single cells, but pre-enrichment is required prior to flow sorting for efficient isolation of CTCs due to the extreme low frequency of CTCs in blood (one in billions of blood cells). While current enrichment technologies often require many steps and result in poor recovery, we demonstrate a magnetic separator and acoustic microfluidic focusing chip integrated system that enriches rare cells in-line with FACS™ (fluorescent activated cell sorting) and single-cell sequencing. This system analyzes, isolates, and index sorts single cells directly into 96-well plates containing reagents for Molecular Indexing (MI) and transcriptional profiling of single cells. With an optimized workflow using the integrated enrichment-FACS system, we performed a proof-of-concept experiment with spiked prostate cancer cells in peripheral blood and achieved: (i) a rapid one-step process to isolate rare cancer cells from lysed whole blood; (ii) an average of 92% post-enrichment cancer cell recovery (R² = 0.9998) as compared with 55% recovery for a traditional benchtop workflow; and (iii) detection of differentially expressed genes at a single cell level that are consistent with reported cell-type dependent expression signatures for prostate cancer cells. These model system results lay the groundwork for applying our approach to human blood samples from prostate and other cancer patients, and support the enrichment-FACS system as a flexible solution for isolation and characterization of CTCs for cancer diagnosis. © 2018 International Society for Advancement of Cytometry.

Sweet Cherry Extract Targets the Hallmarks of Cancer in Prostate Cells: Diminished Viability, Increased Apoptosis and Suppressed Glycolytic Metabolism

The present work evaluated the anticancer properties of sweet cherry (Prunus avium) extract on human prostate cells. Several sweet cherry cultivars from Fundão (Portugal) were methanol-extracted and their phytochemical composition characterized. The Saco "late harvest" extract was highly-enriched in anthocyanins and selected for use in biological assays. Non-neoplastic (PNT1A) and neoplastic (LNCaP and PC3) human prostate cells were treated with 0-2,000 μg/ml of extract for 48-96 h. Cell viability was evaluated by the MTT assay. Apoptosis, oxidative stress, and glycolytic metabolism were assessed by Western blotting and enzymatic assays. Glucose consumption and lactate production were measured spectrophotometrically. Saco cherry extract diminished the viability of neoplastic and non-neoplastic cells, whereas enhancing apoptosis in LNCaP. Cherry extract-treatment also diminished oxidative damage and suppressed glycolytic metabolism in LNCaP cells. These findings widened the knowledge on the mechanisms by which cherry extract modulate cell physiology, demonstrating their broad action over the hallmarks of cancer.

Human SP-D Acts as an Innate Immune Surveillance Molecule Against Androgen-Responsive and Androgen-Resistant Prostate Cancer Cells

Surfactant Protein D (SP-D), a pattern recognition innate immune molecule, has been implicated in the immune surveillance against cancer. A recent report showed an association of decreased SP-D expression in human prostate adenocarcinoma with an increased Gleason score and severity. In the present study, the SP-D expression was evaluated in primary prostate epithelial cells (PrEC) and prostate cancer cell lines. LNCaP, an androgen dependent prostate cancer cell line, exhibited significantly lower mRNA and protein levels of SP-D than PrEC and the androgen independent cell lines (PC3 and DU145). A recombinant fragment of human SP-D, rfhSP-D, showed a dose and time dependent binding to prostate cancer cells via its carbohydrate recognition domain. This study, for the first time, provides evidence of significant and specific cell death of tumor cells in rfhSP-D treated explants as well as primary tumor cells isolated from tissue biopsies of metatstatic prostate cancer patients. Viability of PrEC was not altered by rfhSP-D. Treated LNCaP (p53+/+) and PC3 (p53 -/-) cells exhibited reduced cell viability in a dose and time dependent manner and were arrested in G2/M and G1/G0 phase of the cell cycle, respectively. rfhSP-D treated LNCaP cells showed a significant upregulation of p53 whereas a significant downregulation of pAkt was observed in both PC3 and LNCaP cell lines. The rfhSP-D-induced apoptosis signaling cascade involved upregulation of Bax:Bcl2 ratio, cytochrome c and cleaved products of caspase 7. The study concludes that rfhSP-D induces apoptosis in prostate tumor explants as well as in androgen dependent and independent prostate cancer cells via p53 and pAkt pathways.