Arrest In Prostate Cancer Cells Research Articles

A mononuclear N,N,N,O donor schiff base Cu(II) complex inhibits bacterial biofilm formation and promotes apoptosis and cell cycle arrest in prostate cancer cells

In this work, we report a distorted square pyramidal mononuclear copper(II) complex [Cu(L)(NCS)] (1) which was obtained by the reaction of the aqueous solution of ammonium thiocyanate to a methanolic solution of copper nitrate trihydrate and corresponding Schiff-base ligands. Schiff bases, HL (C12H19N3O) act as a tetradentate Schiff base, derived from 1:1 condensation of o-hydroxyacetophenone and diethylenetriamine. The synthesized complex has been successfully characterized based on elemental analysis and Infrared (IR) spectroscopy. The structure of complex 1 was confirmed by single-crystal X-ray diffraction study. In our study, we investigated synthesis, structural characterization, antimicrobial, anti-biofilm, and anti-cancer activity, and plausible mechanism of action of a novel mononuclear copper(II) schiff base complex. Increasing microbial resistance to several commercially available or traditional antimicrobial compounds has become a major global health concern at present time. The mononuclear copper(II) complex exhibited potential antibacterial activity against two strains of the gram-negative pathogen Pseudomonas aeruginosa. The copper compound dependent damage of bacterial cell membrane and inhibition of bacterial biofilm formation were also identified. Moreover, complex 1 inhibited prostate cancer cell growth, and migration by inducing apoptosis and arresting the cell cycle at the G2/M phase. Based on the results, we are suggesting our novel mononuclear copper(II) compound as a potential candidate for the development of new antibacterial and anti-cancer drugs.

NRP1 promotes prostate cancer progression via modulating EGFR-dependent AKT pathway activation

Prostate cancer (PCa) is the most common malignant tumor with a high global incidence in males. The mechanism underlying PCa progression is still not clear. This study observed that NRP1 was highly expressed in PCa and associated with poor prognosis in PCa patients. Functionally, NRP1 depletion attenuated the proliferation and migration ability of PCa cells in vitro and in vivo, while NRP1 overexpression promoted PCa cell proliferation and migration. Moreover, it was observed that NRP1 depletion induced G1 phase arrest in PCa cells. Mechanistically, HIF1α is bound to the specific promoter region of NRP1, thereby regulating its transcriptional activation. Subsequently, NRP1 interacted with EGFR, leading to EGFR phosphorylation. This study also provided evidence that the b1/b2 domain of NRP1 was responsible for the interaction with the extracellular domain of EGFR. Moreover, EGFR mediated NRP1-induced activation of the AKT signaling pathway, which promoted the malignant progression of PCa. In addition, the administration of NRP1 inhibitor EG01377 significantly inactivated the EGFR/AKT signaling axis, thereby suppressing PCa progression. In conclusion, the findings from this study highlighted the molecular mechanism underlying NRP1 expression in PCa and provide a potential predictor and therapeutic target for clinical prognosis and treatment of PCa.

CDT1 facilitates metastasis in prostate cancer and correlates with cell cycle regulation.

CDT1 is the essential regulator of the initiation of DNA replication. Overexpressed CDT1 can cause DNA damage through re-replication. However, the function of CDT1 in prostate cancer (PCa) development has not been established. Through bioinformatics, expression levels of CDT1 were found to be higher in metastatic PCa when compared to primary PCa. Then, immunohistochemical staining confirmed that the expression of CDT1 was significantly correlated with the occurrence of distant metastasis. For PCa cells, we established a stable clones knockdown CDT1. MTT was used in analyzing the proliferation ability of cells. Migration as well as invasion assays were performed. Effects of CDT1 knockdown on the cell cycle were evaluated by flow cytometry. Expression levels of EMT-associated markers in PCa cells were determined by Western blotting. And PI3K/AKT/GSK3β, a signaling molecule recognized in PCa that can regulate EMT, was detected in protein level. Over expression of CDT1 in PCa cells enhanced cell migration, invasion, tumor metastasis and was correlated with cell cycle regulation. Our results showed that knockdown of CDT1 inhibited G1 to S phase transition and induced the G1 phase cell cycle arrest in PCa cells. Moreover, it upregulated the expressions of epithelial markers (E-cadherin) and down-regulated mesenchymal markers (including Slug, N-cadherin, MMP2, vimentin, Snail, and MMP9) via regulating the phosphorylation level of PI3K, AKT and GSK3β. CDT1 promotes PCa cell metastasis by promoting cell cycle and PI3K/AKT/GSK3β mediated epithelial-mesenchymal transition (EMT) progression and may be a therapeutic target for metastatic PCa.

Circular RNA circPFKP promotes cell proliferation by activating IMPDH2 in prostate cancer.

Prostate cancer (PCa), especially castration-resistant PCa, is a common and fatal disease. circRNAs had been confirmed to affect the proliferation of a variety of malignant tumors. Exploring the role of circRNAs in PCa progression and discovering new therapeutic targets are of great importance for the treatment of PCa. In the present study, we found that the expression of circPFKP was significantly increased in PCa tissues compared with adjacent noncancerous prostate tissues, and was correlated with the D'Amico risk classification, N stage, and prognostic stage group of PCa. CircPFKP promotes the proliferation of PCa cells in vitro and in vivo. Suppressing circPFKP induced the G1/S arrest of PCa cells. Mechanistically, circPFKP interacted with IMPDH2, promoted the biogenesis of guanine nucleotides. Moreover, the replenishment of intracellular guanine nucleotides pool reverses the inhibitory effect of knocking-down circPFKP on PCa cell proliferation. hnRNPF might promote circPFKP generation by binding to flanking Alu elements. Our results identify a novel functional interaction of circPFKP with IMPDH2, which promotes the proliferation of PCa cells.

Upregulated PPARG2 facilitates interaction with demethylated AKAP12 gene promoter and suppresses proliferation in prostate cancer

Prostate cancer (PCA) is one of the most common male genitourinary tumors. However, the molecular mechanisms involved in the occurrence and progression of PCA have not been fully clarified. The present study aimed to investigate the biological function and molecular mechanism of the nuclear receptor peroxisome proliferator-activated receptor gamma 2 (PPARG2) in PCA. Our results revealed that PPARG2 was downregulated in PCA, and overexpression of PPARG2 inhibited cell migration, colony formation, invasion and induced cell cycle arrest of PCA cells in vitro. In addition, PPARG2 overexpression modulated the activation of the Akt signaling pathway, as well as inhibited tumor growth in vivo. Moreover, mechanistic analysis revealed that PPARG2 overexpression induced increased expression level of miR-200b-3p, which targeted 3′ UTR of the downstream targets DNMT3A/3B, and facilitated interaction with demethylated AKAP12 gene promoter and suppressed cell proliferation in PCA. Our findings provided the first evidence for a novel PPARG2-AKAP12 axis mediated epigenetic regulatory network. The study identified a molecular mechanism involving an epigenetic modification that could be possibly targeted as an antitumoral strategy against prostate cancer.

Overexpression of IGFBP5 Enhances Radiosensitivity Through PI3K-AKT Pathway in Prostate Cancer.

BackgroundRadiotherapy is the main treatment for localized prostate cancer. The therapeutic effects of radiotherapy are highly dependent on radiosensitivity of target tumors. Here, we investigated the impact of insulin-like growth factor-binding protein 5 (IGFBP5) on irradiation therapy in prostate cancer.MethodsIGFBP5 gene was overexpressed in human prostate cancer cell lines, PC3 and DU145, with transfection of lentivirus expression vector. Radiosensitivity of the cell lines was assessed with colony formation, cell cycle and cell proliferation assays. The expression of proteins associated with the PI3K-AKT pathway was determined by Western blotting. The effect of IGFBP5 knockdown on PI3K-AKT pathway was tested using PI3K inhibitor.ResultsHigher expression of IGFBP5 improved the efficacy of radiotherapy for prostate cancer patients. The effects of IGFBP5 were linked to the PI3K-AKT signaling pathway. Overexpression of IGFBP5 enhanced radiosensitivity and induced G2/M phase arrest in prostate cancer cells. In contrast, it decreased PI3K, p-AKT expression and cell viability. These effects were reversed by IGFBP5 knockdown.ConclusionOur results reveal that IGFBP5 regulates radiosensitivity in prostate cancer via the PI3K-AKT pathway. It is, therefore, a potential biomarker of tumors that influences the therapeutic effect of radiotherapy.

Plumbagin-Serum Albumin Interaction: Spectral, Electrochemical, Structure-Binding Analysis, Antiproliferative and Cell Signaling Aspects with Implications for Anticancer Therapy.

Plumbagin (5-hydroxy-2-methyl-1,4-naphthoquinone) is a small molecule with potent anticancer activity. Like other 1,4-naphthoquinones, it exhibits electrophilic reactivity towards biological nucleophiles. We demonstrate that plumbagin and structurally related 1,4-naphthoquinones with at least one unsubstituted quinoid carbon (C2 or C3) bind to albumin, an ubiquitously present nucleophile, with minimum recovery of free drug. Extraction recovery of plumbagin from albumin in solution showed one-phase exponential decline with a half-live of 9.3 min at 10 μmol/L. In the presence of albumin, plumbagin exhibited instant changes in UV/Vis absorption bands. Electrochemical analysis using cyclic voltammetry showed a decrease in redox peak currents over time until electro-inactivity, thus suggesting the formation of a supramolecular adduct inaccessible for electron transfer. The adduct inhibited cell growth and caused cell-cycle arrest of prostate cancer cells, in part by decreasing levels of the cell-cycle regulator RBBP. The conjugate displayed similar cellular effects to those described for plumbagin, such as decreased levels of androgen receptor and protein kinase C epsilon. The effect of plumbagin-albumin on cancer cells was species-specific, suggesting a receptor-mediated mechanism. Furthermore, it was blocked by cathepsin inhibitor pepstatin A, indicating that lysosomal degradation is involved in the processing of plumbagin-albumin adduct. The spontaneously formed adduct of plumbagin with serum albumin is likely to mediate the biological activities of plumbagin in vivo and to fundamentally influence its pharmacodynamics.

Polyphyllin I induces cell cycle arrest in prostate cancer cells via the upregulation of IL6 and P21 expression.

Polyphyllin I has been reported to possess anticancer properties in various cancer types, including prostate cancer. However, little is known about the potential of Polyphyllin I in induction of prostate cancer cell cycle arrest and its underlying mechanisms. The anti-proliferation activity of Polyphyllin I was tested using cell counting kit-8 assay. The cell cycle arrest effects of Polyphyllin I were confirmed by flow cytometry. Western blot was used to test the effect of Polyphyllin I on cell cycle-related protein expression. Reverse transcription-polymerase chain reaction was used to test the expression of genes regulating P21 expression. Polyphyllin I induced prostate cancer cell cycle arrest in G0/G1 phase in concentration-dependent manner. Polyphyllin I induced cell cycle arrest by upregulating the expression of P21. Further studies showed that the upregulation of p21 expression induced by Polyphyllin I via the upregulation of IL6 expression. Polyphyllin I could induce cell cycle arrest in G0/G1 phase in prostate cancer cells by upregulating the expression of P21 and IL6.

Date Pit Carbon Dots Induce Acidic Inhibition of Peroxidase and Disrupt DNA Repair in Antibacteria Resistance.

Carbon nanodots (C‐dots) are emerging as a new type of promising agent in anticancer, imaging, and new energy. Reports as well as the previous research indicate that certain C‐dots can enhance targeted cancer therapy. However, in‐depth mechanisms for such anticancer effect remain unclear. In this work, treatment provided by the date pit‐derived C‐dots, exhibits significant DNA damage; Annexin V/7‐AAD‐mediated apoptosis, and G2/M cell cycle arrest in prostate cancer cells. The application of C‐dots to the cell generally leads to acidulation of the cell medium, cooperated with membrane compact. The date pit‐derived C‐dots are observed inhibiting the horseradish peroxidase. Moreover, the C‐dots disrupt likely through nucleotide excision DNA repair at low dose during DNA ligation step suggesting the antimicrobial effect and targeting Pim‐1, EGFR, mTOR, and DNA damage pathways in cancer cells. For the first time the detailed and novel mechanisms underlying the C‐dots, derived from the date‐pit, as an efficient, low‐cost, and green nanomaterial are reveled for cancer therapy and anti‐infection.

MicroRNA-107 inhibits proliferation of prostate cancer cells by targeting cyclin E1.

Previous studies have reported that miR-107 could be utilized as a potential peripheral biomarker in prostate cancer (PCa). However, the specific functions of miR-107 in prostate cancer and its relevant mechanisms are still unknown. The aim of this research was to investigate the cellular functions of miR-107 in PCa and reveal the relevant mechanisms. MicroRNA tailing quantitative real-time PCR (qRT-PCR) was adopted to measure the expression of miR-107 in PCa cell line DU145 and PC3, as well as in normal prostate cell line RWPE-1. The miR-107 expression pattern in PCa tissues and paired peritumoral tissues were determined by Chromogenic In Situ Hybridization (CISH). Cell viability, colony formation, flow cytometry cell cycle and apoptosis, wound healing and Transwell migration assays were performed to study the miR-107 functions in PCa cells. Further, qRT-PCR, western blot analysis and dual-luciferase reporter assays were conducted to verify the target of miR-107 in PCa. Results demonstrated that miR-107 was downregulated in PCa cells and tissues in comparison with normal prostate cells and peritumoral tissues, and the over-expression of miR-107 suppressed proliferation and induced G1/S arrest of PCa cells but had no effects on apoptosis or cell motility of PCa cells. MiR-107 was found to target cyclin E1 (CCNE1) in PCa cells by directly binding to its 3'-UTR. In conclusion, miR-107 could be a potential tumor suppressor in PCa, and the restoration of miR-107 might provide a new therapeutic option for PCa.

Exendin-4 enhances radiation response of prostate cancer.

Exendin-4, one of the most widely used antidiabetic drugs, has recently been reported to have potential antitumor effects in cancers. Prostate cancer (PC) is one of the most common cancers in male patients with type 2 diabetes mellitus, and radiotherapy plays a vital role in the therapy of PC. Whether exendin-4 has the potential to enhance PC response to ionizing radiation (IR) remains unknown. We aimed to explore whether exendin-4 radiosensitizes PC cells. GLP-1 receptor (GLP-1R) expression in PC tissue samples and cell lines were analyzed, Human prostate cancer cells (PC3 and LNCap) were treated with IR and exendin-4, and subjected to proliferation, clone formation, cell cycle, immunoblotting, and immunohistochemical analysis. An in situ prostate tumor of animal model was established. We found that GLP-1R was expressed in human PC tissues and cell lines. 1-100 nM exendin-4 promoted the anti-proliferation effects of IR in vitro and in vivo, and enhanced radiation-induced G2/M cycle arrest in PC cells in a dose-dependent manner. Furthermore, Ex-4 increased AMPK phosphorylation, decrease the levels of p-mTOR, cyclin B, and p34cdc2 . Our study suggested exendin-4 radiosensitizes PC cells via activation of AMPK A and subsequent inhibition of p-mTOR, cyclin B, and p34cdc2 activation.

MiR-206 inhibits proliferation and migration of prostate cancer cells by targeting CXCL11.

Our study was aimed at detecting the expression levels of miR-206 in prostate cancer (PCa) tissues and PCa cell lines, and exploring the potential functions of miR-206 by targeting chemokine ligand 11 (CXCL11). RT-qPCR was applied to detect the expressions of miR-206 and CXCL11 in PCa tissues and in PCa cell lines. Expression of the CXCL11 protein was detected using Western blot. After manipulating the expression of miR-206 and CXCL11 in PC-3 and DU-145 cells, the changes of cell proliferation and cell cycle were observed through cell counting kit-8 (CCK-8) and flow cytometry. Wound healing and transwell assay were conducted for cell migration and invasion examination in vitro. The luciferase reporter assay was applied to validate the association between miR-206 and CXCL11. MiR-206 was significantly under-expressed in PCa tissues and in PCa cell lines. Up-regulation of miR-206 could inhibit proliferation, migration, invasion and induced G1/G0 arrest of PCa cells, and vice versa. MiR-206 bound to the 3'-UTR of CXCL11 and significantly repressed the luciferase activity. Overexpression of miR-206 decreased the expression level of CXCL11 significantly. CXCL11 mRNA and protein levels were significantly decreased in PCa cells. Downregulation of CXCL11 presented tumor-suppressing effects on PCa cells as miR-206 mimics did. And co-transfection miR-206 attenuated the tumor-promoting effects induced by CXCL11 overexpression. Our current finding demonstrated that miR-206 negatively regulated PCa cell proliferation and migration, and arrested cell cycle by targeting CXCL11 as a tumor suppressor in prostate cancer.

APE1/Ref-1 redox-specific inhibition decreases survivin protein levels and induces cell cycle arrest in prostate cancer cells.

A key feature of prostate cancer progression is the induction and activation of survival proteins, including the Inhibitor of Apoptosis (IAP) family member survivin. Apurinic/apyrimidinic endonuclease 1/redox effector factor 1 (APE1/Ref-1) is a multifunctional protein that is essential in activating oncogenic transcription factors. Because APE1/Ref-1 is expressed and elevated in prostate cancer, we sought to characterize APE1/Ref-1 expression and activity in human prostate cancer cell lines and determine the effect of selective reduction-oxidation (redox) function inhibition on prostate cancer cells in vitro and in vivo. Due to the role of oncogenic transcriptional activators NFĸB and STAT3 in survivin protein expression, and APE1/Ref-1 redox activity regulating their transcriptional activity, we assessed selective inhibition of APE1/Ref-1’s redox function as a novel method to halt prostate cancer cell growth and survival. Our study demonstrates that survivin and APE1/Ref-1 are significantly higher in human prostate cancer specimens compared to noncancerous controls and that APE1/Ref-1 redox-specific inhibition with small molecule inhibitor, APX3330 and a second-generation inhibitor, APX2009, decreases prostate cancer cell proliferation and induces cell cycle arrest. Inhibition of APE1/Ref-1 redox function significantly reduced NFĸB transcriptional activity, survivin mRNA and survivin protein levels. These data indicate that APE1/Ref-1 is a key regulator of survivin and a potentially viable target in prostate cancer.

MicroRNA-193a-3p inhibits cell proliferation in prostate cancer by targeting cyclin D1.

MicroRNAs (miRNAs) are small non-coding RNAs that affect various biological processes by altering the expression of a target gene. An miRNA microarray analysis has previously revealed a significant decrease in miR-193a-3p levels in prostate cancer tissues compared with that in their benign prostate hyperplasia counterparts. However, the role of miR-193a-3p has yet to be elucidated. In the present study, reverse transcription-quantitative polymerase chain reaction (RT-qPCR) was used to evaluate the expression levels of miR-193a-3p in two human prostate cancer cell lines. Forced overexpression of miR-193a-3p was established by transfecting mimics into DU-145 and PC3 cell lines. Cell proliferation and the cell cycle were assessed using a cell viability assay, flow cytometry and a colony formation assay. In addition, the target gene of miR-193a-3p was determined by a luciferase assay, RT-qPCR and western blot analysis. The regulation of the cell cycle by miR-193a-3p was also evaluated by western blotting. The results demonstrated that miR-193a-3p expression levels were lower in prostate cancer cell lines as compared with the RWPE normal prostate epithelium cell line. Subsequent gain-of-function studies revealed that stable miR-193a-3p transfection inhibited cell viability, proliferation and colony formation, and induced G1 phase arrest in prostate cancer cells. A luciferase assay and western blot analysis identified cyclin D1 (CCND1) as a direct target gene of miR-193a-3p. In addition, the forced expression of CCND1 was able to counter the inhibitory effects of miR-193a-3p transfection in the prostate cancer cells. In summary, the results suggest that miR-193a-3p may inhibit the viability, proliferation and survival of prostate cancer cells by regulating the expression profile of CCND1, and that miR-193a-3p may be a novel therapeutic biomarker for prostate cancer.

Significance of the TMPRSS2:ERG gene fusion in prostate cancer.

The transmembrane protease serine 2:v-ets erythroblastosis virus E26 oncogene homolog (TMPRSS2:ERG) gene fusion is common in prostate cancer, while its functional role is not fully understood. The present study aimed to investigate the significance of the TMPRSS2:ERG gene fusion in human prostate cancers using bioinformatics tools. Comprehensive alteration analysis of TMPRSS2 and ERG in 148 different human cancer studies was performed by cBioPortal, and the mRNA expression level of the ERG gene was evaluated using Oncomine analysis. Furthermore, lentiviral short hairpin (sh)RNA-mediated knockdown of TMPRSS2:ERG was performed to study the impact of ERG silencing on cell proliferation and cell cycle distribution in prostate cancer cells. The results demonstrated that the TMPRSS2 and ERG genes were mostly altered in prostate cancer, and the most frequent alteration was gene fusion. Oncomine analysis demonstrated that the ERG gene was significantly upregulated in prostate clinical samples compared with the normal prostate gland in four independent datasets, and a positive association was observed between potassium inwardly-rectifying channel subfamily J member 15, down syndrome critical region gene 4, potassium inwardly-rectifying channel subfamily J member 6 and ERG gene expression. There were 272 mutations of the ERG gene identified in the cBioPortal database; among the mutations, 2 missense mutations (R367C and P401H) were regarded as functional mutations (functional impact score >1.938). Furthermore, the present study successfully knocked down ERG gene expression through a lentiviral-mediated gene silencing approach in VCaP prostate cancer cells. The ERG mRNA and protein expression levels were both suppressed significantly, and a cell-cycle arrest at G0/G1 phase was observed after ERG gene silencing. In conclusion, these bioinformatics analyses provide novel insights for TMPRSS2:ERG fusion gene study in prostate cancer. Target inhibition of ERG expression could significantly cause cell growth arrest in prostate cancer cells, which could be a potentially valuable target for prostate cancer treatment. However, the precise mechanism of these results remains unclear; therefore, further studies are required.

Lgr4 promotes prostate tumorigenesis through the Jmjd2a/AR signaling pathway

Lgr4 (leucine-rich repeat domain containing G protein-coupled receptor 4) is implicated in the transcriptional regulation of multiple histone demethylases in the progression of diverse cancers, but there are few reports concerning the molecular mechanism by which Lgr4 regulates histone demethylase activation in prostate cancer (PCa) progression. As Jmjd2a is a histone demethylase, in the current study, we investigated the relationship between interaction Lgr4 with Jmjd 2a and Jmjd2a/androgen receptor (AR) signaling pathway in PCa progression. Firstly, Lgr4 was overexpressed by transfecting pcDNA3.1(+)/Lgr4 plasmids into PCa (LNCaP and PC-3) cell lines. Next, we found that Lgr4 overexpression promoted Jmjd2a mRNA expression, reduced cell apoptosis and arrested cell cycle in the S phase, these effects were reversed by Jmjd2a silencing. Moreover, Lgr4 overexpression markedly elevated AR levels and its interaction with Jmjd2a, which was tested by co-immunoprecipitation and luciferase reporter assays. Furthermore, interaction AR with PSA promoter (containing an AR response element) was obviously improved by Lgr4 overexpression, and PSA silencing reduced Lgr4-induced cell apoptosis and cell cycle arrest in PCa cells. Taken together, Lgr4 may be a novel tumor marker providing new mechanistic insights into PCa progression. Lgr4 activates Jmjd2a/AR signaling pathway to promote interaction AR with PSA promoter, causing reduction of PCa apoptosis and cell cycle arrest.

Retraction.

This article has been retracted at the request of: Editor-in-Chief and Co-author 'Down-regulation of Jagged-1 induces cell growth inhibition and S phase arrest in prostate cancer cells' by Zhang, Y., Wang, Z., Ahmed, F., Banerjee, S., Li, Y. and Sarkar, F. H. The above article, published online on 5 July 2006, in Wiley Online Library (wileyonlinelibrary.com), has been retracted by agreement between the authors, the journal Editor-in-Chief, Professor Peter Lichter, and Wiley Periodicals, Inc. A university investigation involving the second and the corresponding author determined that histone bands in Fig. 4 in this paper were manipulated and that β-actin bands in Fig. 1C were duplicated from another publication. Therefore, the authors are retracting the paper in its entirety although they maintain that these issues did not affect the major conclusions. They apologize for any inconvenience this may have caused. Reference Zhang, Y., Wang, Z., Ahmed, F., Banerjee, S., Li, Y. and Sarkar, F. H. (2006), Down-regulation of Jagged-1 induces cell growth inhibition and S phase arrest in prostate cancer cells. Int. J. Cancer, 119: 2071-2077. doi: 10.1002/ijc.22077.

Abstract 2603: Discovery of chemopreventive agents from licorice (Glycyrrhiza Uralensis)

Abstract Traditional Chinese Medicine (TCM) provides a rich resource of potential chemoprevention agents; however, the complexity arise from its multi-components and multi-targets nature hindered in-depth investigations and translations. Licorice is one of the most commonly utilized TCM herbal medicine which possesses many pharmacological activities including cancer prevention. We isolated over 120 licorice-derived compounds and systemically screened these compounds using cellular and molecular models including cytotoxicity, nitric oxide production, NF-κB and ARE luciferase reporters, and other models. Isoangustone A (IAA) is an isoprenyled isoflavonoid which has been reported to induce apoptosis and cell cycle arrest in prostate cancer cells, and it was identified as a NF-κB inhibitor in our assays. IAA significantly inhibited NF-κB signaling in SW480 colorectal adenocarcinoma cells, and decreased the expression of Cox-2 and iNOS. Overexpression of constitutively activated IKKβ potently stimulated NF-κB signaling and reversed IAA-mediated inhibition. Oral administration of IAA significantly inhibited dextran sodium sulfate-induced NF-κB signaling and the expression of Cox-2 and iNOS in mouse colon tissue, and alleviated symptoms of colitis without observable acute toxicity. IAA and similar compounds also induced autophagy in various cancer cells, and inhibition of autophagy significant reversed IAA-induced cell death, suggesting the existence of autophagic cell death. IAA caused cleavage and aggregation of LC-3 accompanied with p62 degradation, and typical autophagic morphology was observed by transmission electronic microscopy. Overexpression of dominant negative AMPK or treatment with AMPK inhibitor demonstrated that activation of AMPK was important for IAA-induced autophagy, while inhibition of Akt was not. Further studies suggest that metabolic stresses is essential for the pharmacological activities of IAA, and primary molecular target were identified. Notably, IAA significantly inhibited tumor growth in nude mice xenograft model. These results suggest that IAA is potentially an anti-inflammatory bowel disease and anti- colorectal cancer agent. Based on the structural similarity, several other compounds were found to possess even stronger anti-inflammation, pro-apoptotic and autophagy-inducing activities. The present work discovered several promising chemopreventive compounds from licorice that deserve future study, and provides an example of study on TCM in chemoprevention. Several other compounds were identified as Nrf2/ARE signaling modulators or apoptosis/autophagy inducers and further investigated. The present works were supported by the National Natural Science Foundation of China (No. 81272468, 81472657). Citation Format: Shunan Tang, Shuai Ji, Yongrui Wang, Ye Min, Siwang Yu, Tony A-N. Kong. Discovery of chemopreventive agents from licorice (Glycyrrhiza Uralensis). [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 2603.

Pentoxifylline modulates the AKT/mTOR/AMPK pathway: potential role as an adjunct in cancer chemotherapy

Targeting specific pathways involved in the growth and death of cells, such as AKT (signal transduction pathway promoting growth), mTOR (intracellular signaling pathway regulating cell cycle), and AMPK (coordination of growth, autophagy, and metabolism), is an established, effective strategy to inhibit cancer cell growth. Previously, we have shown that pentoxifylline (PTX), a clinically‐utilized non‐specific phosphodiesterase inhibitor, can inhibit growth and induce G1 arrest in prostate cancer cells. In the present studies, we examined the mechanism of PTX induced growth inhibition via modulation of growth/metabolic pathways, and the potential use of PTX as an adjunct in cancer chemotherapy. In prostate adenocarcinoma cells (LNCaP), we show PTX modulates the AKT pathway, as evidenced by the decreased phosphorylation of AKT. Downstream modulation of the mTOR pathway is indicated by decreased phosphorylation of mTOR, ribosomal S6K, and 4EBP1, and total cyclin D1. P‐mTOR levels return to baseline by 24h, while p‐S6K, p‐4EBP1, and cyclin D1 levels are suppressed for at least 48h, indicating a sustained decrease in the activity of cell growth pathway proteins. PTX also modulates the AMPK pathway, as revealed by modulation of downstream p‐RAPTOR, p‐ACC and p‐ULK. Both the AKT and AMPK pathways regulate the activation of cellular autophagy, an intracellular degradation system and determinant of cell survival. Treatment of LNCaP cells with PTX alone, and in combination with bafilomycin, a lysosomal degradation inhibitor, increased LC3‐II expression, indicating an induction of autophagic flux. Overall, PTX modulates both AKT and AMPK pathways, decreasing cell growth and increasing autophagy. Moreover, LNCaP cells treated with PTX were more susceptible to docetaxel (DOC; first‐line chemotherapy) induced cytotoxicity than DOC alone. Interestingly, the PTX/DOC combination decreased the expression of LC3 relative to PTX alone, suggesting activation of an alternate cell death pathway. Indeed, assessment of caspase cleavage, pBcl‐2, and annexin staining revealed a synergistic effect of PTX/DOC treatment on the induction of apoptosis. In summary, the findings provide a mechanistic basis for the potential use of PTX as an adjunct in the chemotherapy of prostate cancer. The ability of PTX to potentiate the effects of DOC on tumor growth inhibition in a mouse xenograft model is currently being assessed.Support or Funding InformationASPET SURF, P30ES006694, T32ES006694

G protein-coupled receptor GPR160 is associated with apoptosis and cell cycle arrest of prostate cancer cells.

G protein-coupled receptors (GPCRs) represent the largest membrane protein family implicated in the therapeutic intervention of a variety of diseases including cancer. Exploration of biological actions of orphan GPCRs may lead to the identification of new targets for drug discovery. This study investigates potential roles of GPR160, an orphan GPCR, in the pathogenesis of prostate cancer. The transcription levels of GPR160 in the prostate cancer tissue samples and cell lines, such as PC-3, LNCaP, DU145 and 22Rv1 cells, were significantly higher than that seen in normal prostate tissue and cells. Knockdown of GPR160 by lentivirus-mediated short hairpin RNA constructs targeting human GPR160 gene (ShGPR160) resulted in prostate cancer cell apoptosis and growth arrest both in vitro and in athymic mice. Differential gene expression patterns in PC-3 cells infected with ShGPR160 or scramble lentivirus showed that 815 genes were activated and 1193 repressed. Functional annotation of differentially expressed genes (DEGs) revealed that microtubule cytoskeleton, cytokine activity, cell cycle phase and mitosis are the most evident functions enriched by the repressed genes, while regulation of programmed cell death, apoptosis and chemotaxis are enriched significantly by the activated genes. Treatment of cells with GPR160-targeting shRNA lentiviruses or duplex siRNA oligos increased the transcription of IL6 and CASP1 gene significantly. Our data suggest that the expression level of endogenous GPR160 is associated with the pathogenesis of prostate cancer.