Dissecting major signaling pathways in prostate cancer development and progression: Mechanisms and novel therapeutic targets

Alterations in Tumor Aggression Following Androgen Receptor Signaling Restoration in Canine Prostate Cancer Cell Lines

In prostate cancer (PCa), androgens upregulate tumorigenesis, whereas in benign tissue, the revival of androgen receptor (AR) signaling suppresses aggressive behaviors, suggesting therapeutic potential. Dogs, natural PCa models, often lack AR in PCa. We restored AR in dog PCa to investigate resultant characteristics. Three AR-null canine PCa lines (1508, Leo, 1258) were transfected with canine wild-type AR and treated with dihydrotestosterone (DHT). In 1508, AR restoration decreased clonogenicity (p = 0.03), viability (p = 0.004), migration (p = 0.03), invasion (p = 0.01), and increased expression of the tumor suppressor NKX3.1, an AR transcriptional target (p = 0.001). In Leo, AR decreased clonogenicity (p = 0.04) and the expression of another AR transcriptional target FOLH1 (p < 0.001) and increased the expression of NKX3.1 (p = 0.01). In 1258, AR increased migration (p = 0.006) and invasion (p = 0.03). Epithelial-mesenchymal transition (EMT) marker (Vimentin, N-cadherin, SNAIL1) expression increased with AR restoration in Leo and 1258 but not 1508; siRNA vimentin knockdown abrogated AR-induced 1258 migration only. Overall, 1508 showed AR-mediated tumor suppression; AR affected proliferation in Leo but not migration or invasion; and EMT and AR regulated migration and invasion in 1258 but not proliferation. This study highlights the heterogeneous nature of PCa in dogs and cell line-specific effects of AR abrogation on aggressive behaviors.

Epigenetic regulation of androgen dependent and independent prostate cancer

Prostate cancer is one of the most common malignancies among men worldwide. Besides genetic alterations, epigenetic modulations including DNA methylation, histone modifications and miRNA mediated alteration of gene expression are the key driving forces for the prostate tumor development and cancer progression. Aberrant expression and/or the activity of the epigenetic modifiers/enzymes, results in aberrant expression of genes involved in DNA repair, cell cycle regulation, cell adhesion, apoptosis, autophagy, tumor suppression and hormone response and thereby disease progression. Altered epigenome is associated with prostate cancer recurrence, progression, aggressiveness and transition from androgen-dependent to androgen-independent phenotype. These epigenetic modifications are reversible and various compounds/drugs targeting the epigenetic enzymes have been developed that are effective in cancer treatment. This chapter focuses on the epigenetic alterations in prostate cancer initiation and progression, listing different epigenetic biomarkers for diagnosis and prognosis of the disease and their potential as therapeutic targets. This chapter also summarizes different epigenetic drugs approved for prostate cancer therapy and the drugs available for clinical trials.

Excess weight, weight gain, and prostate cancer risk and prognosis: the PROCA-life study

BACKGROUND

Studies of excess weight and weight changes throughout adult life for prostate cancer (PCa) risk and prognosis have shown inconsistent results.

METHODS

In a population-based cohort, the Prostate Cancer Study throughout life (PROCA-life), 16,960 healthy men from the prospective cohort Tromsø Study (1994-2016) were included. Body mass index (BMI) and weight were measured at all four attendings, and weight change was calculated as the difference between the first and last of either Tromsø4, Tromsø5 or Tromsø6. Overall, 904 men developed PCa during 16 years of follow-up, and Poisson regression with fractional polynomials was used to investigate trends in incidence. Cox proportional hazard and logistic regression models were used to study associations between measurements of BMI and weight change and PCa risk, severity, and mortality.

RESULTS

At study entry, 46% of the participants (median age 44 years) were overweight, and 14% were obese (BMI > 30 kg/m2). We observed a 127% increase in overall age adjusted PCa incidence in the cohort during 1995 through 2019. No overall associations between BMI or weight change and PCa risk were observed. However, in sub-group analysis, weight gain among obese men was associated with a three-fold higher PCa risk (HR 3.03, 95% CI 1.39-6.58) compared with obese men with stable weight. Overweight was associated with lower risk of metastatic cancer (OR 0.48, 95% CI 0.30-0.75) at diagnosis. Men with obesity had higher risk of PCa-specific death (HR 1.72, 95% CI 1.03-2.88), while nonsmoking obese PCa cases had two times higher PCa-specific mortality compared with normal weighted PCa cases (HR 2.10, 95% CI 1.11-3.70).

INTERPRETATION

In our cohort, weight gain among obese men was associated with higher risk of PCa, and obesity was associated with higher PCa-specific mortality, especially among nonsmokers. The relationship between weight and risk for PCa remains complicated, and future studies are needed to determine clinical implications.

Inflammation in Prostate Cancer: Exploring the Promising Role of Phenolic Compounds as an Innovative Therapeutic Approach

Prostate cancer (PCa) remains a significant global health concern, being a major cause of cancer morbidity and mortality worldwide. Furthermore, profound understanding of the disease is needed. Prostate inflammation caused by external or genetic factors is a central player in prostate carcinogenesis. However, the mechanisms underlying inflammation-driven PCa remain poorly understood. This review dissects the diagnosis methods for PCa and the pathophysiological mechanisms underlying the disease, clarifying the dynamic interplay between inflammation and leukocytes in promoting tumour development and spread. It provides updates on recent advances in elucidating and treating prostate carcinogenesis, and opens new insights for the use of bioactive compounds in PCa. Polyphenols, with their noteworthy antioxidant and anti-inflammatory properties, along with their synergistic potential when combined with conventional treatments, offer promising prospects for innovative therapeutic strategies. Evidence from the use of polyphenols and polyphenol-based nanoparticles in PCa revealed their positive effects in controlling tumour growth, proliferation, and metastasis. By consolidating the diverse features of PCa research, this review aims to contribute to increased understanding of the disease and stimulate further research into the role of polyphenols and polyphenol-based nanoparticles in its management.

siRNA-based approaches for castration-resistant prostate cancer therapy targeting the androgen receptor signaling pathway

Androgen deprivation therapy is a common treatment method for metastatic prostate cancer through lowering androgen levels; however, this therapy frequently leads to the development of castration-resistant prostate cancer (CRPC). This is attributed to the activation of the androgen receptor (AR) signaling pathway. Current treatments targeting AR are often ineffective mostly due to AR gene overexpression and mutations, as well as the presence of splice variants that accelerate CRPC progression. Thus there is a critical need for more specific medication to treat CRPC. Small interfering RNAs have shown great potential as a targeted therapy. This review discusses prostate cancer progression and the role of AR signaling in CRPC, and proposes siRNA-based targeted therapy as a promising strategy for CRPC.

ASCL1 is activated downstream of the ROR2/CREB signaling pathway to support lineage plasticity in prostate cancer

Lineage plasticity is a form of therapy-induced drug resistance. In prostate cancer, androgen receptor (AR) pathway inhibitors potentially lead to the accretion of tumor relapse with loss of AR signaling and a shift from a luminal state to an alternate program. However, the molecular and signaling mechanisms orchestrating the development of lineage plasticity under the pressure of AR-targeted therapies are not fully understood. Here, a survey of receptor tyrosine kinases (RTKs) identifies ROR2 as the top upregulated RTK following AR pathway inhibition, which feeds into lineage plasticity by promoting stem-cell-like and neuronal networks. Mechanistically, ROR2 activates the ERK/CREB signaling pathway to modulate the expression of the lineage commitment transcription factor ASCL1. Collectively, our findings nominate ROR2 as a potential therapeutic target to reverse the ENZ-induced plastic phenotype and potentially re-sensitize tumors to AR pathway inhibitors.

Molecular Similarities and Differences between Canine Prostate Cancer and Human Prostate Cancer Variants

Dogs are one of few species that naturally develop prostate cancer (PCa), which clinically resembles aggressive, advanced PCa in humans. Moreover, PCa-tumor samples from dogs are often androgen receptor (AR)-negative and may enrich our understanding of AR-indifferent PCa in humans, a highly lethal subset of PCa for which few treatment modalities are available This narrative review discusses the molecular similarities between dog PCa and specific human-PCa variants, underscoring the possibilities of using the dog as a novel pre-clinical animal model for human PCa, resulting in new therapies and diagnostics that may benefit both species.

Improving Whole Tomato Transformation for Prostate Health: Benign Prostate Hypertrophy as an Exploratory Model

It is well-established that the beneficial properties of single phytonutrients can be better attained when they are taken with the complex of the molecules present in their natural milieu. Tomato, the fruit providing the most comprehensive complex of prostate-health-preserving micronutrients, has been shown to be superior to its single-nutrient counterparts in decreasing the incidence of age-related prostate diseases. Herein, we describe a novel tomato food supplement enriched with olive polyphenols, containing cis-lycopene concentrations far exceeding those present in industry-produced tomato commodities. The supplement, endowed with antioxidant activity comparable to that of N-acetylcysteine, significantly reduced, in experimental animals, the blood levels of prostate-cancer-promoting cytokines. In prospective, randomized, double-blinded, placebo-controlled studies performed on patients affected by benign prostatic hyperplasia, its uptake significantly improved urinary symptoms and quality of life. Therefore, this supplement can complement and, in some cases, be an alternative to current benign prostatic hyperplasia management. Furthermore, the product suppressed carcinogenesis in the TRAMP mouse model of human prostate cancer and interfered with prostate cancer molecular signaling. Thus, it may offer a step forward in exploring the potential of tomato consumption to delay or prevent the onset of age-related prostate diseases in high-risk individuals.

Cabazitaxel-Loaded Nanoparticles Reduce the Invasiveness in Metastatic Prostate Cancer Cells: Beyond the Classical Taxane Function

Bone-metastatic prostate cancer symbolizes the beginning of the later stages of the disease. We designed a cabazitaxel-loaded, poly (lactic-co-glycolic acid) (PLGA) nanoparticle using an emulsion-diffusion-evaporation technique. Bis (sulfosuccinimidyl) suberate (BS3) was non-covalently inserted into the nanoparticle as a linker for the conjugation of a bone-targeting moiety to the outside of the nanoparticle. We hypothesized that the nanoparticles would have the ability to inhibit the epithelial-to-mesenchymal transition (EMT), invasion, and migration in prostate cancer cells. Targeted, cabazitaxel-loaded nanoparticles attenuated the EMT marker, Vimentin, and led to an increased E-cadherin expression. These changes impart epithelial characteristics and inhibit invasive properties in cancer progression. Consequently, progression to distant sites is also mitigated. We observed the reduction of phosphorylated Src at tyrosine 416, along with increased expression of phosphorylated cofilin at serine 3. These changes could affect migration and invasion pathways in cancer cells. Both increased p-120 catenin and inhibition in IL-8 expression were seen in targeted, cabazitaxel-loaded nanoparticles. Overall, our data show that the targeted, cabazitaxel-loaded nanoparticles can act as a promising treatment for metastatic prostate cancer by inhibiting EMT, invasion, and migration, in prostate cancer cells.

Nimbolide enhances the antitumor effect of docetaxel via abrogation of the NF-κB signaling pathway in prostate cancer preclinical models

Prostate cancer is the second most frequent type of cancer that affects men. Docetaxel (DTX) administration is the front-line therapy for patients with advanced prostate cancer and unfortunately, half of these patients develop resistance to DTX which could be due to its ability to activate the NF-κB pathway. The combinational effect of DTX and nimbolide on proliferation, apoptosis, activation of NF-κB, DNA binding ability of NF-κB, and expression of NF-κB-targeted gene products was investigated. The antitumor and antimetastatic effect of DTX or NL alone or in combination was also examined. The co-administration of NL and DTX resulted in a significant loss of cell viability with enhanced apoptosis in DTX-sensitive/resistant prostate cancer cells. NL abrogated DTX-triggered NF-κB activation and expression of its downstream antiapoptotic factors (survivin, Bcl-2, and XIAP). The combination of NL and DTX significantly reduced the DNA binding ability of NF-κB in both cell types. NL significantly enhanced the antitumor effect of DTX and reduced metastases in orthotopic models of prostate cancer. NL abolishes DTX-induced-NF-κB activation to counteract cell proliferation, tumor growth, and metastasis in the prostate cancer models.

Targeting aldehyde dehydrogenase for prostate cancer therapies

Prostate cancer (PCa) is the most common cancer in men in the United States. About 10 – 20% of PCa progress to castration-resistant PCa (CRPC), which is accompanied by metastasis and therapeutic resistance. Aldehyde dehydrogenase (ALDH) is famous as a marker of cancer stem-like cells in different cancer types, including PCa. Generally, ALDHs catalyze aldehyde oxidation into less toxic carboxylic acids and give cancers a survival advantage by reducing oxidative stress caused by aldehyde accumulation. In PCa, the expression of ALDHs is associated with a higher tumor stage and more lymph node metastasis. Functionally, increased ALDH activity makes PCa cells gain more capabilities in self-renewal and metastasis and reduces the sensitivity to castration and radiotherapy. Therefore, it is promising to target ALDH or ALDH^high cells to eradicate PCa. However, challenges remain in moving the ALDH inhibitors to PCa therapy, potentially due to the toxicity of pan-ALDH inhibitors, the redundancy of ALDH isoforms, and the lack of explicit understanding of the metabolic signaling transduction details. For targeting PCa stem-like cells (PCSCs), different regulators have been revealed in ALDH^high cells to control cell proliferation and tumorigenicity. ALDH rewires essential signaling transduction in PCa cells. It has been shown that ALDHs produce retinoic acid (RA), bind with androgen, and modulate diverse signaling. This review summarizes and discusses the pathways directly modulated by ALDHs, the crucial regulators that control the activities of ALDH^high PCSCs, and the recent progress of ALDH targeted therapies in PCa. These efforts will provide insight into improving ALDH-targeted treatment.

Expression of HER2/NEU in newly diagnosed metastatic carcinoma prostate on TRUS biopsy specimen and its clinical correlation and progression

Background:

Prostate cancer development and progression to androgen-independent disease is correlated with increased expression of growth factors and receptors capable of establishing autocrine and/or paracrine growth-stimulatory loops. Overexpression of the Her2/neu receptor tyrosine kinase has been associated with the progression to androgen independence in prostate cancer cells.

Objective:

Our primary aim was to investigate the frequency of HER2/neu amplification in prostate biopsy specimens in newly diagnosed metastatic carcinoma prostate and its correlation to progression of androgen independent carcinoma.

Materials and Methods:

In our study, expression of HER2/neu was carried out by immunohistochemical analysis in TRUS biopsy specimen of newly diagnosed metastatic carcinoma prostate.

Results:

Out of 36 patients, seven (19.4%) showed her2neu overexpression on immunohistochemical staining. Five out of seven (71%) were associated with higher histological grade >7 at diagnosis ( p < 0.05). Her2neu overexpression was not significantly associated with age and serum PSA at diagnosis. However progression to castration resistant stage was not dependant on Her2/neu status ( p > 0.05).

Conclusion:

Overexpression of her2/neu was associated with high grade carcinoma prostate at diagnosis, however progression to castration resistant stage was not related with her2neu expression.

Heterogeneous Expression and Subcellular Localization of Pyruvate Dehydrogenase Complex in Prostate Cancer

Background

Pyruvate dehydrogenase (PDH) complex converts pyruvate into acetyl-CoA by pyruvate decarboxylation, which drives energy metabolism during cell growth, including prostate cancer (PCa) cell growth. The major catalytic subunit of PDH, PDHA1, is regulated by phosphorylation/dephosphorylation by pyruvate dehydrogenase kinases (PDKs) and pyruvate dehydrogenase phosphatases (PDPs). There are four kinases, PDK1, PDK2, PDK3 and PDK4, which can phosphorylate and inactivate PDH; and two phosphatases, PDP1 and PDP2, that dephosphorylate and activate PDH.

Methods

We have analyzed by immunohistochemistry the expression and clinicopathological correlations of PDHA1, PDP1, PDP2, PDK1, PDK2, PDK3, and PDK4, as well as of androgen receptor (AR), in a retrospective PCa cohort of patients. A total of 120 PCa samples of representative tumor areas from all patients were included in tissue microarray (TMA) blocks for analysis. In addition, we studied the subcellular localization of PDK2 and PDK3, and the effects of the PDK inhibitor dichloroacetate (DCA) in the growth, proliferation, and mitochondrial respiration of PCa cells.

Results

We found heterogeneous expression of the PDH complex components in PCa tumors. PDHA1, PDP1, PDK1, PDK2, and PDK4 expression correlated positively with AR expression. A significant correlation of PDK2 immunostaining with biochemical recurrence and disease-free survival was revealed. In PCa tissue specimens, PDK2 displayed cytoplasmic and nuclear immunostaining, whereas PDK1, PDK3 and PDK4 showed mostly cytoplasmic staining. In cells, ectopically expressed PDK2 and PDK3 were mainly localized in mitochondria compartments. An increase in maximal mitochondrial respiration was observed in PCa cells upon PDK inhibition by DCA, in parallel with less proliferative capacity.

Conclusion

Our findings support the notion that expression of specific PDH complex components is related with AR signaling in PCa tumors. Furthermore, PDK2 expression associated with poor PCa prognosis. This highlights a potential for PDH complex components as targets for intervention in PCa.

Dibutylstannanediyl (2Z,2'Z)-bis(4-(benzylamino)-4-oxobut-2-enoate inhibits prostate cancer progression by activating p38 MAPK/PPARα/SMAD4 signaling

Organotin (IV) compounds are a focus of research for potential use in cancer chemotherapy. Here, we established anticancer profile of dibutyltin (IV) carboxylate derivatives in prostate cancer (PCa) model. We determined cytotoxicity of a library of dibutyltin (IV) carboxylate derivatives and observed that dibutylstannanediyl (2Z,2'Z)-bis(4-(benzylamino)-4-oxobut-2-enoate (Ch-620; 10 μM) was minimally toxic to normal fibroblasts. Ch-620 (1-1.25 μM) inhibited proliferation of PCa and melanoma cells on short- and long-term exposures with induction of cell cycle arrest. Ch-620 treatment increased population of apoptotic cells, as assessed by flow cytometry, and activated caspase 3. Proteomics showed activation of PPARα, with repression of SMAD4 and integrin β5 (ITGB5) in Ch-620-treated PCa cells. Further analysis demonstrated that Ch-620 resulted in phosphorylation of p38 MAPK, upregulation of PPARα and decreased expression of SMAD4 and ITGB5 with reduced migration of PCa cells. In vivo studies in PC3M grafted athymic nude mice showed that Ch-620 (5 μg/week; 7 weeks) treatment reduced tumor growth as opposed to untreated controls. Immunoblot analysis of tumors demonstrated upregulated p-p38 MAPK and PPARα, followed by a decline in SMAD4 and ITGB5. Immunohistochemistry reinforced these results with increased caspase 3 and p-p38 MAPK and diminished Ki67 staining in Ch-620 treated animals. Taken together, our data indicate that Ch-620 inhibited proliferation of PCa through modulation of MAPK/PPARα/SMAD4 signaling. Organotin (IV) carboxylate compounds; specifically Ch-620 can be a potential anticancer agent for the treatment of PCa subject to detailed pre-clinical and clinical investigations. This unlocks prospects for the development of new tin-based drugs in cancer therapeutics.

Alisol B 23-Acetate Increases the Antitumor Effect of Bufalin on Liver Cancer through Inactivating Wnt/β-Catenin Axis

Objective

Liver cancer seriously threatens the health of people. Meanwhile, it has been reported that bufalin could act as an inhibitor in liver cancer. In addition, alisol B 23-acetate is a natural product derived from Alisma plantago-aquatica Linn which has an antitumor effect. In this study, we aimed to explore whether alisol B 23-acetate could increase the antitumor effect of bufalin on liver cancer.

Methods

In order to detect the effect of alisol B 23-acetate in combination with bufalin on liver cancer, human liver cancer SMMC-7721 and MHCC97 cells were used as subjects. Bufalin and alisol B 23-acetate were performed on cells. Cell viability was tested by MTT assay. In addition, flow cytometry was performed to assess the cell apoptosis. Autophagy-related protein levels were tested by western blotting.

Results

The data revealed that bufalin significantly decreased the viability of liver cancer cells, and the inhibitory effect was further increased by alisol B 23-acetate. In addition, alisol B 23-acetate notably enhanced the apoptotic effect of bufalin on liver cancer cells through mediation of Mcl-1, Bax, Bcl-2, and cleaved caspase-3. Meanwhile, alisol B 23-acetate in combination with bufalin induced the autophagy in liver cancer cells through mediation of Beclin-1 and p62. Furthermore, alisol B 23-acetate in combination with bufalin significantly downregulated the level of GSK-3β and increased the expression of β-catenin in liver cancer cells.

Conclusion

In summary, these findings provide the first evidence that alisol B 23-acetate improves the anticancer activity of bufalin on liver cancer through activation of the Wnt/β-catenin axis, and these outcomes might shed new lights on exploring the new methods against liver cancer.

Molecular Mechanisms of Coffee on Prostate Cancer Prevention

Prostate cancer (PCa) is one of the most common types of cancer among men, and coffee is associated with a reduced risk of developing PCa. Therefore, we aim to review possible coffee molecular mechanisms that contribute to PCa prevention. Coffee has an important antioxidant capacity that reduces oxidative stress, leading to a reduced mutation in cells. Beyond direct antioxidant activity, coffee stimulates phase II enzymatic activity, which is related to the detoxification of reactive metabolites. The anti-inflammatory effects of coffee reduce tissue damage related to PCa development. Coffee induces autophagy, regulates the NF-κB pathway, and reduces the expression of iNOS and inflammatory mediators, such as TNF-α, IL-6, IL-8, and CRP. Also, coffee modulates transcriptional factors and pathways. It has been shown that coffee increases testosterone and reduces sex hormone-binding globulin, estrogen, and prostate-specific antigen. Coffee also enhances insulin resistance and glucose metabolism. All these effects may contribute to protection against PCa development.

Encapsulation of doxorubicin prodrug in heat-triggered liposomes overcomes off-target activation for advanced prostate cancer therapy

L-377,202 prodrug consists of doxorubicin (Dox) conjugated to a prostate-specific antigen (PSA) peptide substrate that can be cleaved by enzymatically active PSA at the tumor site. Despite the initial promise in phase I trial, further testing of L-377,202 (herein called Dox-PSA) was ceased due to some degree of non-specific activation and toxicity concerns. To improve safety of Dox-PSA, we encapsulated it into low temperature-sensitive liposomes (LTSL) to bypass systemic activation, while maintaining its biological activity upon controlled release in response to mild hyperthermia (HT). A time-dependent accumulation of activated prodrug in the nuclei of PSA-expressing cells exposed to mild HT was observed, showing that Dox-PSA was efficiently released from the LTSL, cleaved by PSA and entering the cell nucleus as free Dox. Furthermore, we have shown that Dox-PSA loading in LTSL can block its biological activity at 37°C, while the combination with mild HT resulted in augmented cytotoxicity in both 2D and 3D PC models compared to the free Dox-PSA. More importantly, Dox-PSA encapsulation in LTSL prolonged its blood circulation and reduced Dox accumulation in the heart of C4-2B tumor-bearing mice over the free Dox-PSA, thus significantly improving Dox-PSA therapeutic window. Finally, Dox-PSA-loaded LTSL combined with HT significantly delayed tumor growth at a similar rate as mice treated with free Dox-PSA in both solid and metastatic PC tumor models. This indicates this strategy could block the systemic cleavage of Dox-PSA without reducing its efficacy in vivo, which could represent a safer option to treat patients with locally advanced PC. STATEMENT OF SIGNIFICANCE: This study investigates a new tactic to tackle non-specific cleavage of doxorubicin PSA-activatable prodrug (L-377,202) to treat advanced prostate cancer. In the present study, we report a nanoparticle-based approach to overcome the non-specific activation of L-377,202 in the systemic circulation. This includes encapsulating Dox-PSA in low temperature-sensitive liposomes to prevent its premature hydrolysis and non-specific cleavage. This class of liposomes offers payload protection against degradation in plasma, improved pharmacokinetics and tumor targeting, and an efficient and controlled drug release triggered by mild hyperthermia (HT) (∼42°C). We believe that this strategy holds great promise in bypassing any systemic toxicity concerns that could arise from the premature activation of the prodrug whilst simultaneously being able to control the spatiotemporal context of Dox-PSA cleavage and metabolism.

AT-rich interaction domain 5A regulates the transcription of interleukin-6 gene in prostate cancer cells

BACKGROUND

Interleukin-6 (IL-6) is a pleiotropic cytokine that confers androgen-independence and aggressiveness in prostate cancer (PCa); however, the molecular mechanisms regulating IL-6 expression remain unclear. The expression of ARID5A, an AT-rich interaction domain (ARID) DNA-binding motif-containing transcription factor is positively correlated with IL-6 expression in human PCa. We, therefore, hypothesized that ARID5A could regulate IL-6 expression in PCa.

METHODS

The relationship between ARID5A and IL-6 in PCa patients was analyzed using statistical analyses of multiple clinical microarray data sets. To investigate whether ARID5A regulates IL-6 expression, CRISPR-driven ARID5A knockout clones were established in DU145 and PC-3 cells.

RESULTS

Analysis of three microarray data sets showed a positive correlation between ARID5A and IL-6 expression. The expression of IL-6 in ARID5A knockout clones was significantly reduced compared with control clones in both PCa cell lines. Knockout of ARID5A did not result in any loss of IL-6 mRNA stability. Instead, we observed a significant decrease in the occupancy of both active RNA Polymerase II and the active histone mark, H3K4me3 at the IL-6 transcriptional start site in ARID5A knockout PCa cells, suggesting a role for transcriptional regulation.

CONCLUSIONS

Our study demonstrated that loss of ARID5A downregulates the expression of IL-6 at the transcriptional level.

Natural Product-Based Studies for the Management of Castration-Resistant Prostate Cancer: Computational to Clinical Studies

Background: With prostate cancer being the fifth-greatest cause of cancer mortality in 2020, there is a dire need to expand the available treatment options. Castration-resistant prostate cancer (CRPC) progresses despite androgen depletion therapy. The mechanisms of resistance are yet to be fully discovered. However, it is hypothesized that androgens depletion enables androgen-independent cells to proliferate and recolonize the tumor. Objectives: Natural bioactive compounds from edible plants and herbal remedies might potentially address this need. This review compiles the available cheminformatics-based studies and the translational studies regarding the use of natural products to manage CRPC. Methods: PubMed and Google Scholar searches for preclinical studies were performed, while ClinicalTrials.gov and PubMed were searched for clinical updates. Studies that were not in English and not available as full text were excluded. The period of literature covered was from 1985 to the present. Results and Conclusion: Our analysis suggested that natural compounds exert beneficial effects due to their broad-spectrum molecular disease-associated targets. In vitro and in vivo studies revealed several bioactive compounds, including rutaecarpine, berberine, curcumin, other flavonoids, pentacyclic triterpenoids, and steroid-based phytochemicals. Molecular modeling tools, including machine and deep learning, have made the analysis more comprehensive. Preclinical and clinical studies on resveratrol, soy isoflavone, lycopene, quercetin, and gossypol have further validated the translational potential of the natural products in the management of prostate cancer.

Pharmacological Effects of Polyphenol Phytochemicals on the JAK-STAT Signaling Pathway

The JAK-STAT signaling pathway is a common pathway of many cytokine signal transductions, closely related to cell proliferation, apoptosis, differentiation, and inflammatory response. It is essential for inhibiting the inflammatory response, initiating innate immunity, and coordinating adaptive immune mechanisms. Owing to the nature of this pathway and its potential cross-epitopes with multiple alternative pathways, the long-term efficacy of monotherapy-based adaptive targeting therapy is limited, and the majority of drugs targeting STATs are still in the preclinical phase. Meanwhile, curcumin, quercetin, and several kinds of plant polyphenol chemicals play roles in multiple sites of the JAK-STAT pathway to suppress abnormal activation. Polyphenol compounds have shown remarkable effects by acting on the JAK-STAT pathway in anti-inflammatory, antitumor, and cardiovascular disease control. This review summarizes the pharmacological effects of more than 20 kinds of phytochemicals on JAK-STAT signaling pathway according to the chemical structure of polyphenolic phytochemicals.

Effects of orlistat combined with enzalutamide and castration through inhibition of fatty acid synthase in a PC3 tumor-bearing mouse model

Androgen deprivation therapy (ADT) is one of the typical treatments used for patients with prostate cancer (PCa). ADT, however, may fail when PCa develops castration-resistance. Fatty acid synthase (FASN), a critical enzyme involved in fatty acid synthesis, is found to be up-regulated in PCa. Since enzalutamide and ADT are frequently used for the treatment of PCa, the present study aimed to unravel the underlying mechanism of combination of orlistat, an FASN inhibitor, and enzalutamide using PC3 cell line; and orlistat and castration in PC3 tumor-bearing animal model. Cytotoxicity was determined by AlamarBlue assay. Drug effects on the cell cycle and protein expressions were assayed by the flow cytometry and Western blot. Electromobility shift assay was used to evaluate the NF-κB activity. The tumor growth delay, expressions of the signaling-related proteins, and histopathology post treatments of orlistat and castration were evaluated in PC3 tumor-bearing mouse model. The results showed that orlistat arrested the PC3 cells at the G₁ phase of the cell cycle and enhanced the cytotoxic effects of enzalutamide synergistically. Pretreatment with orlistat combined with castration inhibited the tumor growth significantly compared with those of castration and orlistat treatments alone in PC3 tumor-bearing mice. Combination treatment reduced both FASN and NF-κB activities and their downstream effector proteins. The present study demonstrated the synergistic effects of orlistat combined with enzalutamide in vitro and castration in vivo on human PCa.

Advancement and properties of circular RNAs in prostate cancer: An emerging and compelling frontier for discovering

Prostate cancer (PC) is the most common carcinoma among men worldwide which results in 26% of leading causes of cancer-related death. However, the ideal and effective molecular marker remains elusive. CircRNA, initially observed in plant-infected viruses and Sendai virus in 1979, is generated from pre-mRNA back-splicing and comes in to play by adequate expression. The differential expression in prostate tissues compared with the control reveals the promising capacity in modulating processes including carcinogenesis and metastasis. However, the biological mechanisms of regulatory network in PC needs to systemically concluded. In this review, we enlightened the comprehensive studies on the definite mechanisms of circRNAs affecting tumor progression and metastasis. What's more, we validated the potential clinical application of circRNAs serving as diagnostic and prognostic biomarker. The discussion and analysis in circRNAs will broaden our knowledge of the pathogenesis of PC and further optimize the current therapies against different condition.

Aldehyde Dehydrogenases and Prostate Cancer: Shedding Light on Isoform Distribution to Reveal Druggable Target

Prostate cancer represents the most common malignancy diagnosed in men, and is the second-leading cause of cancer death in this population. In spite of dedicated efforts, the current therapies are rarely curative, requiring the development of novel approaches based on innovative molecular targets. In this work, we validated aldehyde dehydrogenase 1A1 and 1A3 isoform expressions in different prostatic tissue-derived cell lines (normal, benign and malignant) and patient-derived primary prostate tumor epithelial cells, demonstrating their potential for therapeutic intervention using a small library of aldehyde dehydrogenase inhibitors. Compound 3b, 6-(4-fluorophenyl)-2-phenylimidazo [1,2-a]pyridine exhibited not only antiproliferative activity in the nanomolar range against the P4E6 cell line, derived from localized prostate cancer, and PC3 cell lines, derived from prostate cancer bone metastasis, but also inhibitory efficacy against PC3 colony-forming efficiency. Considering its concomitant reduced activity against normal prostate cells, 3b has the potential as a lead compound to treat prostate cancer by means of a still untapped molecular target.

Determining the prognostic significance of IKKα in prostate cancer

BACKGROUND

As the survival of castration-resistant prostate cancer (CRPC) remains poor, and the nuclear factor-κB (NF-κB) pathways play key roles in prostate cancer (PC) progression, several studies have focused on inhibiting the NF-κB pathway through generating inhibitory κB kinase subunit α (IKKα) small molecule inhibitors. However, the identification of prognostic markers able to discriminate which patients could benefit from IKKα inhibitors is urgently required. The present study investigated the prognostic value of IKKα, IKKα phosphorylated at serine 180 (p-IKKα S180) and threonine 23 (p-IKKα T23), and their relationship with the androgen receptor (AR) and Ki67 proliferation index to predict patient outcome.

METHODS

A cohort of 115 patients with hormone-naïve PC (HNPC) and CRPC specimens available were used to assess tumor cell expression of proteins within both the cytoplasm and the nucleus by immunohistochemistry. The expression levels were dichotomized (low vs high) to determine the associations between IKKα, AR, Ki67, and patients'Isurvival. In addition, an analysis was performed to assess potential IKKα associations with clinicopathological and inflammatory features, and potential IKKα correlations with other cancer pathways essential for CRPC growth.

RESULTS

High levels of cytoplasmic IKKα were associated with a higher cancer-specific survival in HNPC patients with low AR expression (hazards ratio [HR], 0.33; 95% confidence interval [CI] log-rank, 0.11-0.98; P = .04). Furthermore, nuclear IKKα (HR, 2.60; 95% CI, 1.27-5.33; P = .01) and cytoplasmic p-IKKα S180 (HR, 2.10; 95% CI, 1.17-3.76; P = .01) were associated with a lower time to death from recurrence in patients with CRPC. In addition, high IKKα expression was associated with high levels of T-cells (CD3+ P = .01 and CD8+ P = .03) in HNPC; however, under castration conditions, high IKKα expression was associated with high levels of CD68+ macrophages (P = .04), higher Gleason score (P = .01) and more prostate-specific antigen concentration (P = .03). Finally, we identified crosstalk between IKKα and members of the canonical NF-κB pathway in the nucleus of HNPC. Otherwise, IKKα phosphorylated by noncanonical NF-κB and Akt pathways correlated with members of the canonical NF-κB pathway in CRPC.

CONCLUSION

The present study reports that patients with CRPC expressing high levels of nuclear IKKα or cytoplasmic p-IKKα S180, which associated with a lower time to death from recurrence, may benefit from IKKα inhibitors.

Moringa oleifera methanolic leaves extract induces apoptosis and G0/G1 cell cycle arrest via downregulation of Hedgehog Signaling Pathway in human prostate PC-3 cancer cells

The inadequacy of effective treatment approaches for prostate cancer enlightens the crucial necessity for the search and emergence of novel and multitasking anticancer substances. Several experimental studies suggested the role of natural compounds in prostate cancer growth inhibition by Hedgehog signaling modulation. In the current study, we suggested the anticancer and apoptosis inducing effects of Moringa oleifera (M. oleifera) were linked to downregulation of Hedgehog pathway in PC-3 prostate cancer cells. We found that M. oleifera leaves methanolic extract exhibited significant anticancerous potential by inducing ROS-mediated apoptosis and activation of caspase-3 activity in prostate cancer. We also observed a dose-dependent G0/G1 cell cycle arrest as well as significant alteration in mRNA expression of apoptosis related and Hedgehog signaling pathway genes by M. oleifera extract treatment. Altogether, these experimental findings demonstrated that M. oleifera may exert antiproliferative apoptosis inducing effects by Hedgehog signaling pathway downregulation. PRACTICAL APPLICATIONS: Moringa oleifera plant, a rich nutrional source, has extensive range of pharmacological applications including antioxidant, anti-inflammatory, and anticancer activity. To best of our knowledge, this could be the first intensive report which presented the inhibitory potential of M. oleifera leaves extract against PC-3 prostate cancer cells via targeting key molecules of Hedgehog signaling. Decreased mRNA expression of GLI1 transcription factor and SMO protein of Hedgehog signaling pathway may be involved in antiproliferative effects of M. oleifera leaves extract against prostate cancer cells. Our study suggested that M. oleifera supplementation might be beneficial for the development and improvement of targeted therapeutic strategies in prostate cancer cells.

Targeting the Immune system and Epigenetic Landscape of Urological Tumors

In the last years, we have witnessed remarkable advances in targeted therapies for cancer patients. There is a growing effort to either replace or reduce the dose of unspecific, systemic (chemo)therapies, given the associated short- and long-term side effects, by introducing more specific targeted therapies as single or combination agents. Due to the well-known implications of the immune system and epigenetic landscape in modulating cancer development, both have been explored as potential targets in several malignancies, including those affecting the genitourinary tract. As the immune system function is also epigenetically regulated, there is rationale for combining both strategies. However, this is still rather underexplored, namely in urological tumors. We aim to briefly review the use of immune therapies in prostate, kidney, bladder, and testicular cancer, and further describe studies providing supporting evidence on their combination with epigenetic-based therapies.

New steroidal oxazolines, benzoxazoles and benzimidazoles related to abiraterone and galeterone

Seven new oxazoline, benzoxazole and benzimidazole derivatives were synthesized from 3β-acetoxyandrosta-5,16-dien-17-carboxylic, 3β-acetoxyandrost-5-en-17β-carboxylic and 3β-acetoxypregn-5-en-21-oic acids. Docking to active site of human 17α-hydroxylase/17,20-lyase revealed that all oxazolines, as well as benzoxazoles and benzimidazoles comprising Δ¹⁶ could form stable complexes with enzyme, in which steroid moiety is positioned similarly to that of abiraterone and galeterone, and nitrogen atom coordinates heme iron, while 16,17-saturated benzoxazoles and benzimidazoles could only bind in a position where heterocycle is located nearly parallel to heme plane. Modeling of the interaction of new benzoxazole and benzimidazole derivatives with androgen receptor revealed the destabilization of helix 12, constituting activation function 2 (AF2) site, by mentioned compounds, similar to one induced by known antagonist galeterone. The synthesized compounds inhibited growth of prostate carcinoma LNCaP and PC-3 cells at 96 h incubation; the potency of 2'-(3β-hydroxyandrosta-5,16-dien-17-yl)-4',5'-dihydro-1',3'-oxazole and 2'-(3β-hydroxyandrosta-5,16-dien-17-yl)-benzimidazole was superior and could inspire further investigations of these compounds as potential anti-cancer agents.

Personalization of prostate cancer therapy through phosphoproteomics

Castration-resistant prostate cancer (CRPC) remains incurable despite the approval of several new treatments. Identification of new biomarkers and therapeutic targets to enable personalization of CRPC therapy, with the aim of maximizing therapeutic responses and minimizing toxicity in patients, is urgently needed. Prostate cancer progression and therapeutic resistance are frequently driven by aberrantly activated kinase signalling pathways that are amenable to pharmacological inhibition. Personalized phosphoproteomics, which enables the analysis of signalling networks in individual tumours, is a promising approach to advance personalized therapy by discovering biomarkers of pathway activity and clinically actionable targets. Several technologies for global and targeted phosphoproteomic analysis exist, each with its own strengths and shortcomings. Global discovery phosphoproteomics is predominantly conducted using liquid chromatography-tandem mass spectrometry coupled with data-dependent or data-independent acquisition technologies. Multiplexed targeted phosphoproteomics can be divided into platforms based on mass spectrometry or antibodies, including selected or parallel reaction monitoring and triggered by offset, multiplexed, accurate mass, high-resolution, absolute quantification (known as TOMAHAQ) or forward-phase or reverse-phase protein arrays, respectively. Several obstacles still need to be overcome before the full potential of phosphoproteomics can be realized in routine clinical practice, but a future phosphoproteomics-centric trans-omic profiling approach should enable optimized personalized CRPC management through improved biomarkers and targeted treatments.

STAT3 Post-Translational Modifications Drive Cellular Signaling Pathways in Prostate Cancer Cells

STAT3 is an oncoprotein overexpressed in different types of tumors, including prostate cancer (PCa), and its activity is modulated by a variety of post-translational modifications (PTMs). Prostate cancer represents the most common cancer diagnosed in men, and each phase of tumor progression displays specific cellular conditions: inflammation is predominant in tumor’s early stage, whereas oxidative stress is typical of clinically advanced PCa. The aim of this research is to assess the correspondence between the stimulus-specificity of STAT3 PTMs and definite STAT3-mediated transcriptional programs, in order to identify new suitable pharmacological targets for PCa treatment. Experiments were performed on less-aggressive LNCaP and more aggressive DU-145 cell lines, simulating inflammatory and oxidative-stress conditions. Cellular studies confirmed pY705-STAT3 as common denominator of all STAT3-mediated signaling. In addition, acK685-STAT3 was found in response to IL-6, whereas glutC328/542-STAT3 and pS727-STAT3 occurred upon tert-butyl hydroperoxyde (tBHP) treatment. Obtained results also provided evidence of an interplay between STAT3 PTMs and specific protein interactors such as P300 and APE1/Ref-1. In accordance with these outcomes, mRNA levels of STAT3-target genes seemed to follow the differing STAT3 PTMs. These results highlighted the role of STAT3 and its PTMs as drivers in the progression of PCa.

The role of protein tyrosine phosphatases in prostate cancer biology

Prostate cancer (PCa) is the most frequent malignancy in the male population of Western countries. Although earlier detection and more active surveillance have improved survival, it is still a challenge how to treat advanced cases. Since androgen receptor (AR) and AR-related signaling pathways are fundamental in the growth of normal and neoplastic prostate cells, targeting androgen synthesis or AR activity constitutes the basis of the current hormonal therapies in PCa. However, resistance to these treatments develops, both by AR-dependent and -independent mechanisms. Thus, alternative therapeutic approaches should be developed to target more efficiently advanced disease. Protein tyrosine phosphatases (PTPs) are direct regulators of the protein- and residue-specific phosphotyrosine (pTyr) content of cells, and dysregulation of the cellular Tyr phosphorylation/dephosphorylation balance is a major driving event in cancer, including PCa. Here, we review the current knowledge on the role of classical PTPs in the growth, differentiation, and survival of epithelial prostate cells, and their potential as important players and therapeutic targets for modulation in PCa.

The retinamide VNLG-152 inhibits f-AR/AR-V7 and MNK-eIF4E signaling pathways to suppress EMT and castration-resistant prostate cancer xenograft growth

VNLG-152 is a novel retinamide (NR) shown to suppress growth and progression of genetically diverse prostate cancer cells via inhibition of androgen receptor signaling and eukaryotic initiation factor 4E (eIF4E) translational machinery. Herein, we report therapeutic effects of VNLG-152 on castration-resistant prostate cancer (CRPC) growth and metastatic phenotype in a CRPC tumor xenograft model. Administration of VNLG-152 significantly and dose-dependently suppressed the growth of aggressive CWR22Rv1 tumors by 63.4% and 76.3% at 10 and 20 mg·kg^-1 bw, respectively (P < 0.0001), vs. vehicle with no host toxicity. Strikingly, the expression of full-length androgen receptor (f-AR)/androgen receptor splice variant-7 (AR-V7), mitogen-activated protein kinase-interacting kinases 1 and 2 (MNK1/2), phosphorylated eIF4E and their associated target proteins, including prostate-specific antigen, cyclin D1 and Bcl-2, were strongly decreased in VNLG-152-treated tumors signifying inhibition of f-AR/AR-V7 and MNK-eIF4E signaling in VNLG-152-treated CWR22Rv1 tumors as observed in vitro. VNLG-152 also suppressed the epithelial to mesenchymal transition in CWR22Rv1 tumors as evidenced by repression of N-cadherin, β-catenin, claudin, Slug, Snail, Twist, vimentin and matrix metalloproteinases (MMP-2 and MMP-9) with upsurge in E-cadherin. These results highlight the promising use of VNLG-152 in CRPC therapy and justify its further development towards clinical trials.

Artesunate suppresses the viability and mobility of prostate cancer cells through UCA1, the sponge of miR-184

Artesunate (ART) is a sesquiterpene lactone isolated from the leafy portions of the Chinese herb Artemisia annua. Here, we evaluated the effect of ART on the prostate cancer (PCa) cell lines DU145 and LNCaP and explored its potential mechanisms. ART inhibited the viability and mobility of DU145 and LNCaP cells. Mechanistically, we found that UCA1, one of the most important lncRNAs in malignancies of the urinary system, may be a potential mediator contributing to the tumor suppressor function of ART. First, the UCA1 level was reduced significantly after being exposed to ART. In addition, UCA1 was up-regulated in prostate cancer tissues compared to hyperplastic prostatic tissues, and a higher UCA1 level predicted poor prognosis in PCa patients. Furthermore, reintroduction of UCA1 into PCa cells reversed the effect of ART on apoptosis and metastatic ability. Then we determined that the miR-184/Bcl-2 axis might be the downstream signaling pathway of UCA1 upon ART treatment. UCA1 binds to miR-184 through its seed sequences and may function as a sponge for miR-184.