The strategies to control prostate cancer by chemoprevention approaches

Chemotherapeutic Potential of Saikosaponin D: Experimental Evidence

Saikosaponin D (SSD), an active compound derived from the traditional plant Radix bupleuri, showcases potential in disease management owing to its antioxidant, antipyretic, and anti-inflammatory properties. The toxicological effects of SSD mainly include hepatotoxicity, neurotoxicity, hemolysis, and cardiotoxicity. SSD exhibits antitumor effects on multiple targets and has been witnessed in diverse cancer types by articulating various cell signaling pathways. As a result, carcinogenic processes such as proliferation, invasion, metastasis, and angiogenesis are inhibited, whereas apoptosis, autophagy, and differentiation are induced in several cancer cells. Since it reduces side effects and strengthens anti-cancerous benefits, SSD has been shown to have an additive or synergistic impact with chemo-preventive medicines. Regardless of its efficacy and benefits, the considerations of SSD in cancer prevention are absolutely under-researched due to its penurious bioavailability. Diverse studies have overcome the impediments of inadequate bioavailability using nanotechnology-based methods such as nanoparticle encapsulation, liposomes, and several other formulations. In this review, we emphasize the association of SSD in cancer therapeutics and the discussion of the mechanisms of action with the significance of experimental evidence.

Root Extract of a Micropropagated Prunus africana Medicinal Plant Induced Apoptosis in Human Prostate Cancer Cells (PC-3) via Caspase-3 Activation

Prostate cancer is one of the major causes of cancer-related deaths among men globally. Medicinal plants have been explored as alternative treatment options. Herein, we assessed the in vitro cytotoxic effects of 70% ethanolic root extracts of six-month-old micropropagated Prunus africana (PIR) on PC-3 prostate cancer cells as an alternative to the traditionally used P. africana stem-bark extract (PWS) treatment. In vitro assays on PC-3 cells included annexin-V and propidium iodide staining, DAPI staining, and caspase-3 activity analysis through western blotting. PC-3 cells were exposed to PWS and PIR at different concentrations, and dose-dependent antiprostate cancer effects were observed. PC-3 cell viability was determined using CCK-8 assay, which yielded IC50 values of 52.30 and 82.40 μg/mL for PWS and PIR, respectively. Annexin-V and PI staining showed dose-dependent apoptosis of PC-3 cells. Significant (p < 0.001) percent of DAPI-stained apoptotic PC-3 cells were observed in PWS, PIR, and doxorubicin treatment compared with the negative control. PWS treatment substantially elevated cleaved caspase-3 levels in PC-3 cells compared with the PIR treatment. These results provide evidence for the antiprostate cancer potential of PIR and sets a basis for further research to enhance future utilization of roots of young micropropagated P. africana for prostate cancer treatment as an alternative to stem bark. Moreover, micropropagation approach may help provide the required raw materials and hence reduce the demand for P. africana from endangered wild population.

Leelamine suppresses cMyc expression in prostate cancer cells in vitro and inhibits prostate carcinogenesis in vivo

Aim

Leelamine (LLM) inhibits growth of human prostate cancer cells but the underlying mechanism is not fully understood. The present study was undertaken to determine the effect of LLM on cMyc, which is overexpressed in a subset of human prostate cancers.

Methods

The effect of LLM on cMyc expression and activity was determined by western blotting/confocal microscopy and luciferase reporter assay, respectively. A transgenic mouse model of prostate cancer (Hi-Myc) was used to determine chemopreventive efficacy of LLM.

Results

Exposure of androgen sensitive (LNCaP) and castration-resistant (22Rv1) human prostate cancer cells to LLM resulted in downregulation of protein and mRNA levels of cMyc. Overexpression of cMyc partially attenuated LLM-mediated inhibition of colony formation, cell viability, and cell migration in 22Rv1 and/or PC-3 cells. LLM treatment decreased protein levels of cMyc targets (e.g., lactate dehydrogenase), however, overexpression of cMyc did not attenuate these effects. A trend for a decrease in expression level of cMyc protein was discernible in 22Rv1 xenografts from LLM-treated mice compared with control mice. The LLM treatment (10 mg/kg body weight, 5 times/week) was well-tolerated by Hi-Myc transgenic mice. The incidence of high-grade prostatic intraepithelial neoplasia, adenocarcinoma in situ, and microinvasion was lower in LLM-treated Hi-Myc mice but the difference was not statistically significant.

Conclusion

The present study reveals that LLM inhibits cMyc expression in human prostate cancer cells in vitro but concentrations higher than 10 mg/kg may be required to achieve chemoprevention of prostate cancer.

Grape Powder Supplementation Attenuates Prostate Neoplasia Associated with Pten Haploinsufficiency in Mice Fed High-Fat Diet

SCOPE

Previous studies have identified potent anticancer activities of polyphenols in preventing prostate cancer. The aim of the current study is to evaluate the chemopreventive potential of grape powder (GP) supplemented diets in genetically predisposed and obesity-provoked prostate cancer.

METHODS AND RESULTS

Prostate-specific Pten heterozygous (Pten+/f ) transgenic mice are fed low- and high-fat diet (LFD and HFD, respectively) supplemented with 10% GP for 33 weeks, ad libitum. Prostate tissues are characterized using immunohistochemistry and western blots, and sera are analyzed by ELISA and qRT-PCR. Pten+/f mice fed LFD and HFD supplemented with 10% GP show favorable histopathology, significant reduction of the proliferative rate of prostate epithelial cells (Ki67), and rescue of PTEN expression. The most potent protective effect of GP supplementation is detected against HFD-induced increase in inflammation (IL-1β; TGF-β1), activation of cell survival pathways (Akt, AR), and angiogenesis (CD31) in Pten+/f mice. Moreover, GP supplementation reduces circulating levels of oncogenic microRNAs (miR-34a; miR-22) in Pten+/f mice. There are no significant changes in body weight and food intake in GP supplemented diet groups.

CONCLUSIONS

GP diet supplementation can be a beneficial chemopreventive strategy for obesity-related inflammation and prostate cancer progression. Monitoring serum miRNAs can facilitate the non-invasive evaluation of chemoprevention efficacy.

Fli-1 Activation through Targeted Promoter Activity Regulation Using a Novel 3', 5'-diprenylated Chalcone Inhibits Growth and Metastasis of Prostate Cancer Cells

The friend leukemia integration 1 (Fli-1) gene is involved in the expression control of key genes in multiple pathogenic/physiological processes, including cell growth, differentiation, and apoptosis; this implies that Fli-1 is a strong candidate for drug development. In our previous study, a 3′,5′-diprenylated chalcone, (E)-1-(2-hydroxy-4-methoxy-3,5-diprenyl) phenyl-3-(3-pyridinyl)-propene-1-one (C10), was identified as a novel anti-prostate cancer (PCa) agent. Here, we investigated the molecular mechanisms underlying the anti-cancer effects of C10 on the growth, metastasis, and invasion of PC3 cells in vitro. Our results show that C10 exhibited a strong inhibitory effect on proliferation and metastasis of PC3 cells via several cellular and flow cytometric analyses. Further mechanism studies revealed that C10 likely serves as an Fli-1 agonist for regulating the expression of Fli-1 target genes including phosphatidylinositol 3-kinase (P110), murine double minute2 (MDM2), B-cell lymphoma-2 (Bcl-2), Src homology-2 domain-containing inositol 5-phosphatase 1 (SHIP-1), and globin transcription factor-1 (Gata-1) as well as the phosphorylation of extracellular-regulated protein kinases 1 (ERK1). Further, we confirmed that C10 can regulate the expressions of vascular endothelial growth factor 1 (VEGF-1), transforming growth factor-β2 (TGF-β2), intercellular cell adhesion molecule-1 (ICAM-1), p53, and matrix metalloproteinase 1 (MMP-1) genes associated with tumor apoptosis, migration, and invasion. Thus, C10 exhibits stronger anticancer activity with novel molecular targets and regulatory molecular mechanisms, indicating its great potency for development as a novel targeted anticancer drug.

Silibinin Differentially Decreases the Aggressive Cancer Phenotype in an In Vitro Model of Obesity and Prostate Cancer

Aim: Obesity increases the risk for aggressive and fatal prostate cancer (PCa). The bioactive compound silibinin has been researched for its chemopreventative properties and may benefit obese or overweight individuals with PCa.Methods: This study used an in vitro model of obesity exposing prostate cancer cells to sera from obese, overweight, or normal weight males with or without the addition of silibinin. Molecular activity was assayed as well as the phenotype of PCa cells with various treatments.Results: Obesity increased the expression of proliferative signaling including COX-2, IL-6, AKT, ERK, and AR, which was attenuated with silibinin. Cell growth, and invasive capacity of prostate cancer cells was increased with obese and overweight sera, and silibinin was able to mitigate this affect. However, there are limitations to this study in that an in vivo model was not used to validate these in vitro results nor a co-culture model, which may better recapitulate the tumor microenvironment.Conclusions: Silibinin may be a safe intervention for those with or at risk for prostate cancer, and it may be the most beneficial for obese or overweight males.

Differential effect of grape seed extract and its active constituent procyanidin B2 3,3″-di-O-gallate against prostate cancer stem cells

The present study aimed to determine whether grape seed extract (GSE) procyanidin mix, and its active constituent procyanidin B2 3,3″-di-O-gallate (B2G2) have the potential to target cancer stem cells (CSCs) in prostate cancer (PCa). The CSC populations were isolated and purified based on CD44⁺ -α2β1^high surface markers in PCa cell lines LNCaP, C4-2B, 22Rv1, PC3, and DU145, and then subjected to prostasphere formation assays in the absence or presence of GSE or B2G2. Results indicated that at lower doses (<15 μg) , the GSE procyanidin mix produced activity in unsorted prostate cancer antigen (PCA) cells, but not in sorted; however, multiple treatments with low dose GSE over a course of time inhibited sphere formation by sorted PCA CSCs. Importantly, B2G2 demonstrated significant potential to target both unsorted and sorted CSCs at lower doses. As formation of spheroids, under specific in vitro conditions, is a measure of stemness, these results indicated the potential of both GSE and B2G2 to target the self-renewal of CSC in PCa cell lines, though B2G2 was more potent in its efficacy. Subsequent mechanistic studies revealed that both GSE procyanidins and B2G2 strongly decreased the constitutive as well as Jagged1 (Notch1 ligand)-induced activated Notch1 pathway. In totality, these in vitro studies warrant extensive dose-profiling-based assessments in vivo settings to conclusively determine the impact on CSC pool kinetics on the efficacy of both GSE and B2G2 to target PCa growth as well as tumor relapse.

Involvement of CXCR4 in Normal and Abnormal Development

CXC motif chemokine receptor type 4 (CXCR4) is associated with normal and abnormal development, including oncogenesis. The ligand of CXCR4 is stromal cell-derived factor (SDF), also known as CXC motif ligand (CXCL) 12. Through the SDF-1/CXCR4 axis, both homing and migration of hematopoietic (stem) cells are regulated through niches in the bone marrow. Outside of the bone marrow, however, SDF-1 can recruit CXCR4-positive cells from the bone marrow. SDF/CXCR4 has been implicated in the maintenance and/or differentiation of stemness, and tissue-derived stem cells can be associated with SDF-1 and CXCR4 activity. CXCR4 plays a role in multiple pathways involved in carcinogenesis and other pathologies. Here, we summarize reports detailing the functions of CXCR4. We address the molecular signature of CXCR4 and how this molecule and cells expressing it are involved in either normal (maintaining stemness or inducing differentiation) or abnormal (developing cancer and other pathologies) events. As a constituent of stem cells, the SDF-1/CXCR4 axis influences downstream signal transduction and the cell microenvironment.

Afrocyclamin A, a triterpene saponin, induces apoptosis and autophagic cell death via the PI3K/Akt/mTOR pathway in human prostate cancer cells

BACKGROUND

Afrocyclamin A, an oleanane-type triterpene saponin, was isolated from Androsace umbellata which used as a traditional herbal medicine.

PURPOSE

This study aimed to explore the anticancer activity of afrocyclamin A on human prostate cancer cells in vitro as well as in vivo.

METHODS

Cytotoxicity, cell cycle distribution, apoptosis, and autophagic cell death were measured following exposure to afrocyclamin A. In vivo antitumor activity of afrocyclamin A was assessed in a xenograft model. The protein levels of p-Akt, p-mTOR, Bax, Bcl-2, caspase-3, and caspase-9 were quantified using western blot analysis.

RESULTS

In DU145 cells, afrocyclamin A increased cytotoxicity, caused changes in cell morphology, and induced sub-G0/G1 phase indicating increased apoptosis. Afrocyclamin A robustly induced autophagic cell death as demonstrated by the conversion of LC3B-I to LC3B-II, and the formation of autophagic vacuoles as revealed by western blot analysis and fluorescence staining, respectively. Afrocyclamin A also inhibited the phosphorylation of PI3K, Akt, and mTOR, suggesting their role in afrocyclamin A induced cell death. In addition, afrocyclamin A inhibited cell migration and invasion in concentration and time-dependent manners. In an in vivo xenograft model, afrocyclamin A inhibited the growth of DU145 cells.

CONCLUSION

Afrocyclamin A has anticancer activity via the PI3K/Akt/mTOR pathway, which leads to cell death.

Nutraceuticals in prostate cancer therapeutic strategies and their neo-adjuvant use in diverse populations

Prostate cancer (PCa) is the most frequently diagnosed malignancy and second leading cause of cancer mortality in American males. Notably, men of African descent in the United States and Caribbean have the highest PCa mortality rates compared to men with European ancestry. Although current therapeutics are quite potent and effective, disease resistance, progression to metastasis, therapy-associated toxicities and efficacy-related issues in diverse populations develop over time. Thus, non-toxic and efficacious therapeutic strategies are needed to address these major obstacles for the clinical treatment and management of PCa. In this regard, preclinical and population-based efficacy studies have shown the potential of natural non-toxic nutraceuticals as potent anti-PCa agents. Accordingly, the implementation of nutraceutical intervention and genetic testing in diverse populations might aid in the development and design of precision medicine strategies to reduce the burden of chemotherapy-associated toxicities, suppress disease resistance, and treat both localized and advanced PCa. Consequently, additional large-scale and inclusive clinical studies are required to fully assess efficacy and therapeutic limitations of these agents in PCa. This review discusses the most current clinical research on selected nutraceutical agents and their efficacy in the context of clinico-pathological outcomes and disease susceptibility in diverse PCa clinical and epidemiological studies.

Inhibition of Glycolysis in Prostate Cancer Chemoprevention by Phenethyl Isothiocyanate

We have shown previously that dietary administration of phenethyl isothiocyanate (PEITC), a small molecule from edible cruciferous vegetables, significantly decreases the incidence of poorly differentiated prostate cancer in Transgenic Adenocarcinoma of Mouse Prostate (TRAMP) mice without any side effects. In this study, we investigated the role of c-Myc-regulated glycolysis in prostate cancer chemoprevention by PEITC. Exposure of LNCaP (androgen-responsive) and 22Rv1 (castration-resistant) human prostate cancer cells to PEITC resulted in suppression of expression as well as transcriptional activity of c-Myc. Prostate cancer cell growth inhibition by PEITC was significantly attenuated by stable overexpression of c-Myc. Analysis of the RNA-Seq data from The Cancer Genome Atlas indicated a significant positive association between Myc expression and gene expression of many glycolysis-related genes, including hexokinase II and lactate dehydrogenase A Expression of these enzyme proteins and lactate levels were decreased upon PEITC treatment in prostate cancer cells, and these effects were significantly attenuated by ectopic expression of c-Myc. A normal prostate stromal cell line (PrSC) was resistant to lactic acid suppression by PEITC treatment. Prostate cancer chemoprevention by PEITC in TRAMP mice was associated with a significant decrease in plasma lactate and pyruvate levels. However, a 1-week intervention with 10 mg PEITC (orally, 4 times/day) was not sufficient to decrease lactate levels in the serum of human subjects. These results indicated that although prostate cancer prevention by PEITC in TRAMP mice was associated with suppression of glycolysis, longer than 1-week intervention might be necessary to observe such an effect in human subjects. Cancer Prev Res; 11(6); 337-46. ©2018 AACR.

Prostate Cancer Xenograft Inhibitory Activity and Pharmacokinetics of Decursinol, a Metabolite of Angelica gigas Pyranocoumarins, in Mouse Models

We have previously shown that the ethanol extract of dried Angelica gigas Nakai (AGN) root exerts anticancer activity against androgen receptor (AR)-negative human DU145 and PC-3 prostate cancer xenografts and primary carcinogenesis in the transgenic adenocarcinoma of mouse prostate (TRAMP) model. The major pyranocoumarin isomers decursin (D) and decursinol angelate (DA), when provided at equi-molar intake to that provided by AGN extract, accounted for the inhibitory efficacy against precancerous epithelial lesions in TRAMP mice. Since we and others have shown in rodents and humans that D and DA rapidly and extensively convert to decursinol, here we tested whether decursinol might be an in vivo active compound for suppressing xenograft growth of human prostate cancer cells expressing AR. In SCID-NSG mice carrying subcutaneously inoculated human LNCaP/AR-Luc cells overexpressing the wild type AR, we compared the efficacy of 4.5[Formula: see text]mg decursinol per mouse with equi-molar dose of 6[Formula: see text]mg D/DA per mouse. The result showed that decursinol decreased xenograft tumor growth by 75% and the lung metastasis, whereas D/DA exerted a much less effect. Measurement of plasma decursinol concentration, at 3[Formula: see text]h after the last dose of respective dosing regimen, showed higher circulating level in the decursinol-treated NSG mice than in the D/DA-treated mice. In a subsequent single-dose pharmacokinetic experiment, decursinol dosing led to 3.7-fold area under curve (AUC) of plasma decursinol over that achieved by equi-molar D/DA dosing. PK advantage notwithstanding, decursinol represents an active compound to exert in vivo prostate cancer growth and metastasis inhibitory activity in the preclinical model.

Procyanidin B2 3,3″-di-O-gallate induces oxidative stress-mediated cell death in prostate cancer cells via inhibiting MAP kinase phosphatase activity and activating ERK1/2 and AMPK

Neoplastic cells exhibit higher oxidative stress compared to normal cells; however, antioxidants based clinical trials have mostly failed. Another attractive therapeutic approach is to further increase the oxidative stress in cancer cells leading to cell death. Herein, we show that Procyanidin B2 3,3″-di-O-gallate (B2G2), the most active constituent of grape seed extract, treatment causes cell death in human prostate cancer (PCa) cells (LNCaP and 22Rv1) via increasing the reactive oxygen species (ROS) generation. Mechanistically, B2G2 treatment decreased the mitochondrial electron transport chain complex III activity leading to enhanced mitochondrial superoxide generation and decreased ATP production in LNCaP cells. Additional molecular studies revealed that B2G2-induced cell death was mediated mainly through ROS-induced sustained activation of ERK1/2, which was due to inhibition of MAP kinase phosphatase (MKP) activity as over-expression of MKP3 in LNCaP cells conferred significant protection against B2G2-induced cell death. Along with ERK1/2, AMP-activated protein kinase α (AMPKα) was also activated by B2G2 treatment, and pre-treatment with AMPKα inhibitor compound C significantly reversed the cytotoxic effects of B2G2 in LNCaP cells. Furthermore, pre-treatment of MKP3 over-expressing LNCaP cells with compound C further reduced the B2G2-induced cell death, suggesting the involvement of AMPKα along with MKP3 and ERK1/2 in the biological effects of B2G2. Together, these results for the first time identified that oxidative stress and MKP3 inhibition play a critical role in B2G2-induced cell death in PCa cells through sustained activation of both ERK1/2 and AMPKα. These results offer a unique opportunity to control this deadly malignancy through B2G2 use.

Fatty Acid Synthesis Intermediates Represent Novel Noninvasive Biomarkers of Prostate Cancer Chemoprevention by Phenethyl Isothiocyanate

Increased de novo synthesis of fatty acids is a distinctive feature of prostate cancer, which continues to be a leading cause of cancer-related deaths among American men. Therefore, inhibition of de novo fatty acid synthesis represents an attractive strategy for chemoprevention of prostate cancer. We have shown previously that dietary feeding of phenethyl isothiocyanate (PEITC), a phytochemical derived from edible cruciferous vegetables such as watercress, inhibits incidence and burden of poorly differentiated prostate cancer in transgenic adenocarcinoma of mouse prostate (TRAMP) model. The current study was designed to test the hypothesis of whether fatty acid intermediate(s) can serve as noninvasive biomarker(s) of prostate cancer chemoprevention by PEITC using archived plasma and tumor specimens from the TRAMP study as well as cellular models of prostate cancer. Exposure of prostate cancer cells (LNCaP and 22Rv1) to pharmacologic concentrations of PEITC resulted in downregulation of key fatty acid metabolism proteins, including acetyl-CoA carboxylase 1 (ACC1), fatty acid synthase (FASN), and carnitine palmitoyltransferase 1A (CPT1A). The mRNA expression of FASN and CPT1A as well as acetyl-CoA levels were decreased by PEITC treatment in both cell lines. PEITC administration to TRAMP mice also resulted in a significant decrease in tumor expression of FASN protein. Consistent with these findings, the levels of total free fatty acids, total phospholipids, triglyceride, and ATP were significantly lower in the plasma and/or prostate tumors of PEITC-treated TRAMP mice compared with controls. The current study is the first to implicate inhibition of fatty acid synthesis in prostate cancer chemoprevention by PEITC. Cancer Prev Res; 10(5); 279-89. ©2017 AACR.

A Review of the Potential of Phytochemicals from Prunus africana (Hook f.) Kalkman Stem Bark for Chemoprevention and Chemotherapy of Prostate Cancer

Prostate cancer remains one of the major causes of death worldwide. In view of the limited treatment options for patients with prostate cancer, preventive and treatment approaches based on natural compounds can play an integral role in tackling this disease. Recent evidence supports the beneficial effects of plant-derived phytochemicals as chemopreventive and chemotherapeutic agents for various cancers, including prostate cancer. Prunus africana has been used for generations in African traditional medicine to treat prostate cancer. This review examined the potential roles of the phytochemicals from P. africana, an endangered, sub-Saharan Africa plant in the chemoprevention and chemotherapy of prostate cancer. In vitro and in vivo studies have provided strong pharmacological evidence for antiprostate cancer activities of P. africana-derived phytochemicals. Through synergistic interactions between different effective phytochemicals, P. africana extracts have been shown to exhibit very strong antiandrogenic and antiangiogenic activities and have the ability to kill tumor cells via apoptotic pathways, prevent the proliferation of prostate cancer cells, and alter the signaling pathways required for the maintenance of prostate cancer cells. However, further preclinical and clinical studies ought to be done to advance and eventually use these promising phytochemicals for the prevention and chemotherapy of human prostate cancer.

Masquelier's grape seed extract: from basic flavonoid research to a well-characterized food supplement with health benefits

Careful characterization and standardization of the composition of plant-derived food supplements is essential to establish a cause-effect relationship between the intake of that product and its health effect. In this review we follow a specific grape seed extract containing monomeric and oligomeric flavan-3-ols from its creation by Jack Masquelier in 1947 towards a botanical remedy and nutraceutical with proven health benefits. The preparation's research history parallels the advancing insights in the fields of molecular biology, medicine, plant and nutritional sciences during the last 70 years. Analysis of the extract's flavanol composition emerged from unspecific colorimetric assays to precise high performance liquid chromatography - mass spectrometry and proton nuclear magnetic resonance fingerprinting techniques. The early recognition of the preparation's auspicious effects on the permeability of vascular capillaries directed research to unravel the underlying cellular and molecular mechanisms. Recent clinical data revealed a multitude of favorable alterations in the vasculature upon an 8 weeks supplementation which summed up in a health benefit of the extract in healthy humans. Changes in gene expression of inflammatory pathways in the volunteers' leukocytes were suggested to be involved in this benefit. The historically grown scientific evidence for the preparation's health effects paves the way to further elucidate its metabolic fate and molecular action in humans.

A Novel Role of Silibinin as a Putative Epigenetic Modulator in Human Prostate Carcinoma

Silibinin, extracted from milk thistle (Silybum marianum L.), has exhibited considerable preclinical activity against prostate carcinoma. Its antitumor and chemopreventive activities have been associated with diverse effects on cell cycle, apoptosis, and receptor-dependent mitogenic signaling pathways. Here we hypothesized that silibinin's pleiotropic effects may reflect its interference with epigenetic mechanisms in human prostate cancer cells. More specifically, we have demonstrated that silibinin reduces gene expression levels of the Polycomb Repressive Complex 2 (PRC2) members Enhancer of Zeste Homolog 2 (EZH2), Suppressor of Zeste Homolog 12 (SUZ12), and Embryonic Ectoderm Development (EED) in DU145 and PC3 human prostate cancer cells, as evidenced by Real Time Polymerase Chain Reaction (RT-PCR). Furthermore immunoblot and immunofluorescence analysis revealed that silibinin-mediated reduction of EZH2 levels was accompanied by an increase in trimethylation of histone H3 on lysine (Κ)-27 residue (H3K27me3) levels and that such response was, in part, dependent on decreased expression levels of phosphorylated Akt (ser473) (pAkt) and phosphorylated EZH2 (ser21) (pEZH2). Additionally silibinin exerted other epigenetic effects involving an increase in total DNA methyltransferase (DNMT) activity while it decreased histone deacetylases 1-2 (HDACs1-2) expression levels. We conclude that silibinin induces epigenetic alterations in human prostate cancer cells, suggesting that subsequent disruptions of central processes in chromatin conformation may account for some of its diverse anticancer effects.

Suppression of β-catenin Signaling Pathway in Human Prostate Cancer PC3 Cells by Delphinidin

Delphinidin possesses strong anti-oxidant, anti-inflammatory, and anti-cancer properties. Suppression of the Wnt/β-catenin signaling pathway is a potential strategy for chemoprevention and therapy. As aberrant activation of the β-catenin signaling pathway contributes to prostate cancer progression, we evaluated the effect of delphinidin on this pathway in human PC3 prostate cancer cells. An MTT assay showed that treatment with delphinidin (15–180 μM, 72 hours) resulted in a dose-dependent growth inhibition of cells. Treatment with delphinidin increased the phosphorylation of serine or threonine residues on β-catenin and decreased the levels of cytoplasmic β-catenin. Moreover, treatment with delphinidin inhibited the nuclear translocation of β-catenin and the expression of β-catenin target genes such as cyclin D1, c-myc, Axin-2, and T cell factor-1. Delphinidin also induced the phosphorylation of glycogen synthase kinase 3β and the expression of adenomatous polyposis coli and Axin proteins. Our results indicate that inhibition of cell growth by delphinidin is mediated, at least in part, through modulation of the β-catenin signaling pathway. We suggest that delphinidin is a potent inhibitor of Wnt/β-catenin signaling in prostate cancer cells.

Chemoprevention of Low-Molecular-Weight Citrus Pectin (LCP) in Gastrointestinal Cancer Cells

Background & Aims: Low-molecular-weight citrus pectin (LCP) is a complex polysaccharide that displays abundant galactosyl (i.e., sugar carbohydrate) residues. In this study, we evaluated the anti-tumor properties of LCP that lead to Bcl-xL -mediated dampening of apoptosis in gastrointestinal cancer cells.

Methods: We used AGS gastric cancer and SW-480 colorectal cancer cells to elucidate the effects of LCP on cell viability, cell cycle and apoptosis in cultured cells and tumor xenografts.

Results: Significantly decreased cell viabilities were observed in LCP treated AGS and SW-480 cells (P<0.05). Cell cycle-related protein expression, such as Cyclin B1, was also decreased in LCP treated groups as compared to the untreated group. The AGS or SW-480 cell-line tumor xenografts were significantly smaller in the LCP treated group as compared the untreated group (P<0.05). LCP treatment decreased Galectin-3 (GAL-3) expression levels, which is an important gene in cancer metastasis that results in reversion of the epithelial-mesenchymal transition (EMT), and increased suppression of Bcl-xL and Survivin to promote apoptosis. Moreover, results demonstrated synergistic tumor suppressor activity of LCP and 5-FU against gastrointestinal cancer cells both in vivo and in vitro.

Conclusions: LCP effectively inhibits the growth and metastasis of gastrointestinal cancer cells, and does so in part by down-regulating Bcl-xL and Cyclin B to promote apoptosis, and suppress EMT. Thus, LCP alone or in combination with other treatments has a high potential as a novel therapeutic strategy to improve the clinical therapy of gastrointestinal cancer.

Molecular mechanisms of curcumin and its semisynthetic analogues in prostate cancer prevention and treatment

Primary prostate cancer, also known as prostate adenocarcinoma (PCa), is a devastating cancer in men worldwide. Europe and developing countries of Asia have fewer reported cases of prostate cancer compared to increasing cases in the United States with higher incidence in Black men. Risk factors associated with prostate cancer are aging, genetics, lifestyle, high body mass index as well as carcinogenic exposure to carbon-containing fuels, tobacco, and charbroiled meats. Hormone therapy and radical prostatectomy are commonly implemented treatments. The >20.000 prostate cancer deaths of 2013 suggest that there exists a need for enhanced chemopreventive and therapeutic agents for prostate cancer treatment. Fruits, vegetables, and red wines contain high levels of polyphenolic levels. Consumption of these products may provide chemoprevetion of PCa. Curcumin, the major compound from the turmeric rhizome Curcuma longa has long been used for medicinal purposes as an antiseptic and wound healing. This review focuses on curcumin's therapeutic effectiveness in vitro and in vivo in prostate cancer models. The review will highlight the mechanisms of actions of curcumin in the signaling pathways of prostate cancer.

Chemoprevention of cancer: current evidence and future prospects

Cancer chemoprevention refers to the use of agents for the inhibition, delay, or reversal of carcinogenesis before invasion. In the present review, agents examined in the context of cancer chemoprevention are classified in four major categories—hormonal, medications, diet-related agents, and vaccines—and the main representatives of each category are presented. Although there are serious constraints in the documentation of effectiveness of chemopreventive agents, mainly stemming from the long latency of the condition they are addressing and the frequent lack of intermediate biomarkers, there is little disagreement about the role of aspirin, whereas a diet rich in vegetables and fruits appears to convey more protection than individual micronutrients. Among categories of cancer chemopreventive agents, hormonal ones and vaccines might hold more promise for the future. Also, the identification of individuals who would benefit most from chemopreventive interventions on the basis of their genetic profiles could open new prospects for cancer chemoprevention.

Silibinin inhibits aberrant lipid metabolism, proliferation and emergence of androgen-independence in prostate cancer cells via primarily targeting the sterol response element binding protein 1

Prostate cancer (PCA) kills thousands of men every year, demanding additional approaches to better understand and target this malignancy. Recently, critical role of aberrant lipogenesis is highlighted in prostate carcinogenesis, offering a unique opportunity to target it to reduce PCA. Here, we evaluated efficacy and associated mechanisms of silibinin in inhibiting lipid metabolism in PCA cells. At physiologically achievable levels in human, silibinin strongly reduced lipid and cholesterol accumulation specifically in human PCA cells but not in non-neoplastic prostate epithelial PWR-1E cells. Silibinin also decreased nuclear protein levels of sterol regulatory element binding protein 1 and 2 (SREBP1/2) and their target genes only in PCA cells. Mechanistically, silibinin activated AMPK, thereby increasing SREBP1 phosphorylation and inhibiting its nuclear translocation; AMPK inhibition reversed silibinin-mediated decrease in nuclear SREBP1 and lipid accumulation. Additionally, specific SREBP inhibitor fatostatin and stable overexpression of SREBP1 further confirmed the central role of SREBP1 in silibinin-mediated inhibition of PCA cell proliferation and lipid accumulation and cell cycle arrest. Importantly, silibinin also inhibited synthetic androgen R1881-induced lipid accumulation and completely abrogated the development of androgen-independent LNCaP cell clones via targeting SREBP1/2. Together, these mechanistic studies suggest that silibinin would be effective against PCA by targeting critical aberrant lipogenesis.