Phellodendron Amurense Bark Extract Research Articles

Involvement of PAR2 in inflammatory mediator release from human blood eosinophils

Proteinase Activated Receptors (PARs) are the members of G-protein-coupled receptor family and can be cleaved by certain serine proteases to expose a tethered ligand domain, which binds and activates the receptors to initiate multiple signaling cascades. There is some evidence that certain proteases may regulate target cells by activating PARs. There are many studies, in which PARs play important roles in inflammation. One study indicated that PAR2 inhibition and deletion significantly suppressed the degree of inflammation due to decreased IL-6 and IL-1 levels. Another study also showed that PARs activation could mediate reactive oxygen species production and MAPK signaling leading to alveolar inflammation. In addition, platelet-derived CAPN1 can trigger the vascular inflammation associated with diabetes via cleavage of PAR1 and the release of TNF from the endothelial cell surface, and sarsasapogenin may alleviate diabetic nephropathy by the downregulation of PAR1. Another Phellodendron amurense bark extract can suppress the particulate matter-induced Ca2+ influx caused by direct action upon PAR2, alleviating inflammation and maintaining homeostatic levels of cell adhesion components. There are also other two antagonists of I-287 and GB88, which can reduce the PAR2-mediated inflammatory reaction. In this study, we tested expression of PARs and IL-5, IL-6, RANTES and ECP release from human blood eosinophils using different enzymes and PAR agonists. The expression of PARs was assessed in human blood eosinophils by flow cytometry and RT-PCR, and the levels of cytokine and eosinophil cationic protein (ECP) in the cultured supernatants were determined with ELISA kits. Flow cytometry shows that human eosinophils express PAR2 protein and do not express PAR1, PAR3 and PAR4 proteins. RT-PCR analysis revealed expression of PAR2 and PAR3 genes in human eosinophils. Tryptase, trypsin and elastase can induce significant IL-5, IL-6 and ECP release. Trypsin and elastase may also stimulate RANTES secretion, but tryptase cannot induce the RANTES secretion. Tryptase, trypsin and elastase-induced cytokine and ECP release from human blood eosinophils most likely occurs via activation of PAR2.

Abstract PO-085: Therapeutic targeting of RPS6KB1/SQSTM1 axis to prevent biochemical recurrence

Abstract Radiation therapy (RT) is a standard treatment for organ confined prostate cancer (PCa). Given that both intrinsic and acquired resistance to radiation causes progression to advanced metastatic PCa, there is an unmet need for adjuvant therapies that synergize with radiation to improve therapeutic efficacy. Previously, we demonstrated strong synergistic tumor growth inhibitory activities for Phellodendron amurense bark extract in combination with radiation in part through downregulation of ribosomal protein S6K (encoded by RPS6KB1). Subsequently we identified berberine (Ber), one of the active constituents of Nexrutine as a potential pharmacological inhibitor of RPS6KB1. Given these findings, we hypothesized that targeting RPS6KB1 could be an approach to enhance sensitivity to radiation. We tested the efficacy of Ber alone and in combination with radiation using an orthotopic implantation model and the mechanism associated with radio-sensitization using prostate cancer cells stably silenced and deleted for RPS6KB1. We observed that (i) RPS6KB1 deletion in androgen responsive early stage LNCaP cells and (ii) stable silencing in castrate resistant C4-2B cells increased sensitization to radiation relative to respective parental or non-targeted cells. Furthermore, pharmacological inhibition of RPS6KB1 with Ber sensitized cells to radiation. Mechanistically, RPS6KB1 silencing increased autophagic activity as revealed by changes in proteins identified through reverse phase protein array (RPPA) and decreased expression and levels of SQSTM1 via downregulation of NFkB. Pretreatment with chloroquine (CQ) rescued the observed radio-sensitization effects. Treatment with Ber alone or Ber plus radiation decreased levels of PSA that was sustained during the course of the experiment in mice orthotopically implanted with C4-2B cells. On the other hand animals treated with radiation alone developed recurrent cancer as evidenced by a resurgence of PSA. Notably, RPS6KB1 mRNA levels increased in tumor samples in patients experiencing biochemical recurrence (BCR). Taken together, these findings demonstrate that RPS6KB1 is a clinically relevant target and that Ber sensitizes prostate cancer cells to radiation in vitro and in vivo. Therefore, targeting RPS6KB1 signaling is an attractive strategy to prevent progression to BCR; given that rising PSA following conventional therapeutic approaches such as radiation remain a major clinical challenge. This work is supported in part by CPRIT RP190012 (APK). Citation Format: Addanki P. Kumar, Alison Clark, Michelle R. Villarreal, Shih-Bo Huang, Suleman S. Hussain, Xiaoyu Yang, Roble G. Bedolla, Paul Rivas, Sridharan Jayamohan, Li-Ju Wang, Yidong Chen, Caroline Xavier Paul Ezhilan, Mohan Natarajan, Joel E. Michalek, Robert Reddick, Hiroshi Miyamoto, Rita Ghosh. Therapeutic targeting of RPS6KB1/SQSTM1 axis to prevent biochemical recurrence [abstract]. In: Proceedings of the AACR Virtual Special Conference on Radiation Science and Medicine; 2021 Mar 2-3. Philadelphia (PA): AACR; Clin Cancer Res 2021;27(8_Suppl):Abstract nr PO-085.

Phellodendron amurense Extract Protects Human Keratinocytes from PM2.5-Induced Inflammation via PAR-2 Signaling.

Dietary supplement and personal care products aiming to provide protection from air pollution have been of great interest for decades. Epidemiology demonstrated that PM10 and PM2.5 particulate matter (PM) are an actual threat to public health worldwide, but the detailed processes of how these particles attack the cells are not fully understood. Here, we report that the measurement of intracellular calcium concentration ([Ca2+]i) using human respiratory or skin cells can illustrate pollutant challenges by triggering Ca2+ influx in these cells. This signal was generated by proteinase-activated receptor-2 (PAR-2), confirmed by competition analyses, and Phellodendron amurense bark extract (PAE), a traditional medicine, was able to control the response and expression of PAR-2. Increase in proinflammatory cytokines and decrease in cell adhesion components could suggest a severe damage status by air pollutants and protection by PAE. Finally, we identified 4-O-feruloylquinic acid (FQA), an active compound of PAE, showing the same effects on Ca2+ influx and PAR-2 regulation. The results presented here should help understand the underlying mechanism of PM insults and the beneficial effect of standardized PAE as dietary supplement or cosmetical ingredient.

Abstract 4564: Elucidating the mechanism of the STAT3/NF-κB/EP4 signaling axis in pancreatic cancer

Abstract Despite recent advances to pancreatic cancer (PanCA) management, the 5 year survival rate remains only 7%. This poor survival rate highlights the importance of increasing our molecular understanding of PanCA pathogenesis to develop effective therapies to improve patient outcomes. We previously demonstrated that targeting the STAT3/NF-κB signaling axis with Nexrutine® (a Phellodendron amurense bark extract) was able to inhibit autophagy, ROS production, and proliferation in multiple PanCA cell lines. Our data also indicated the potential involvement of prostaglandin receptor EP4 in mediating these effects. To our surprise, we observed decreased levels of EP4 in human pancreatic tumors implicating a possible protective role. However, the mechanism behind STAT3/NF-κB signaling and its link to EP4 are still unknown. Using genetic and chemical inhibition of STAT3 and EP4, we have sought to define the STAT3/NF-κB/EP4 signaling axis. Our results indicate that inhibition of STAT3 via knockdown (STAT3 KD) using shRNA does not affect the proliferative ability or viability of PanCA cell lines when compared to non-transfected control (NTC) cells. Even though proliferation and viability were un-affected, STAT3 KD increased Cox-2 levels in a KRAS mutant cell line (Capan-2) and inhibited Cox-2 in a KRAS WT cell line (BxPC-3). Inhibition of EP4 increased STAT3 and NF-κB activity in KRAS mutant cell lines while decreasing activity in the KRAS WT cell line. Furthermore, EP4 inhibition increased protein levels of IL-6 and dual inhibition of STAT3 and EP4 yielded increased NF-κB activity and decreased Cox-2 levels. Converse experiments in cells treated with IL-6 revealed inhibited EP4 expression and decreased NF-κB activity. This may be the reason behind the increased STAT3 activity noted in EP4 inhibited KRAS mutant cells and supports the notion that EP4 may be protective against PanCA development. Taken together, these data suggests a feedback loop in regulating the STAT3/NF-κB/EP4 signaling cascade and that STAT3/NF-κB signaling axis members are differentially regulated upon STAT3 or EP4 inhibition possibly depending on KRAS status. Supported by Initiative for Maximizing Student Development (IMSD) Training Grant (R25 GM095480; NMJB), NCCIH (R01 AT007448; APK), and VA-MERIT Award (I01 BX 000766; APK) Citation Format: Amanda R. Munoz, James W. Freeman, Addanki P. Kumar. Elucidating the mechanism of the STAT3/NF-κB/EP4 signaling axis in pancreatic cancer. [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 4564.

Abstract 3047: Sensitization of prostate cancer to chemo-radiation by ribosomal protein S6 inhibition

Abstract Radiation Therapy (RT) is curative for most localized prostate cancer (PCA) patients, but is limited by dose-related toxicities and radioresistance. Administration of Nexrutine® (Nx), an inexpensive supplement from Phellodendron amurense bark extract prior to RT inhibited progression to poorly differentiated carcinoma in transgenic adenocarcinoma of the mouse prostate (TRAMP) mice. However, the precise molecular mechanism underlying Nx-mediated tumor growth inhibitory effects in combination with RT is unclear. Using global transcriptome profiling coupled with GeneSpring analysis, we have identified significant modulation of number of signaling pathways including genes involved in mTOR and NFκB signaling. Based on these data, we hypothesized that downregulation of ribosomal protein S6 (rpS6) sensitizes prostate tumor to overcome radioresistance. PCA cell lines had higher levels of total and p-rpS6 compared to non-tumorigenic prostate cell lines. Using clonogenic assays, we observed that pretreatment of Nx for 8h could potentiate the effect of low dose RT in LNCaP (AR positive with WT p53), PC-3 (AR negative & p53 null) and PC-3 AR (AR expressing & p53 null) cells. The combinatorial effect depicted strong synergism and had similar effects as high dose RT. Notably, we observed increased activation of Akt/mTOR/NFκB signaling molecules after treatment of PC-3 cells with RT, which was either abrogated (p-rpS6, p-NFκB & p-p70S6K) or decreased (p-Akt) in cells pretreated with Nx prior to RT. Also, Nx pretreatment inhibited the levels of HIF1-α and CyclinD1, which are downstream targets of rpS6. Using immunofluorescence assay, we saw that the combination treatment increased the γH2AX foci compared to 2 Gy alone, indicating increased DNA damage. This is associated with increased protein levels of key G2/M regulatory proteins including Wee-1, p-cdc2 levels and decreased Chk1, p-cdc25C resulting in prolonged RT-induced G2/M arrest. The combination treatment also caused a significant increase in apoptosis, which was evidenced by increased cleaved PARP levels, subG1 levels and Annexin/PI staining. Strikingly, knockdown of rpS6 sensitized PC-3 cells to RT and reversed the observed effects of Nx, indicating the importance of rpS6 in mediating these changes. Remarkably, p-mTOR, p70S6K, NFκB, Ki67 & Cyclin D1 were decreased in the prostate tissue of mice receiving the combination compared to RT alone. Recently, a phase 0/1 clinical trial of Nx in PCA patients receiving RT decreased PSA levels and was well-tolerated. Interestingly, tumor tissue from Nx treated patients showed decreased rpS6 staining intensity compared to the normal tissue. Collectively, our data suggests that Nx has radiosensitizing effect in a range of PCA cell lines and could prevent progression to advanced PCA by inhibiting rpS6. Supported by NCCAM (R01 AT-007448) & VA-MERIT Award (I01 BX 000766) Citation Format: Suleman S. Hussain, Carolina B. Livi, Nikos Papanikolaou, Daniel C. Chan, Rita Ghosh, Addanki P. Kumar. Sensitization of prostate cancer to chemo-radiation by ribosomal protein S6 inhibition. [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 3047.

Abstract 1797: Downregulation of ribosomal protein S6 overcomes radioresistance in prostate cancer

Abstract Radiation Therapy (RT) is a definitive treatment for early-localized prostate cancer (PCA), but is associated with side effects which impair quality of life in addition to development of radioresistance. PI3K/Akt/mTOR signaling is one of the contributors to therapeutic resistance, including radioresistance. Ribosomal protein S6 (rpS6), a downstream effector of PI3K/Akt/mTOR signaling, mediates radioresistance by increasing protein synthesis, cell survival and epithelial mesenchymal transition. Also, increased activation of rpS6 is correlated with poor survival in PCA. Therefore, downregulation of rpS6 could decrease RT induced toxic side effects by sensitizing tumor cells. Based on published evidence demonstrating tumor growth inhibitory activities, we tested if Nexrutine® (Nx), an inexpensive OTC herbal supplement from Phellodendron amurense bark extract, could potentiate RT by inhibiting rpS6 activation. Using clonogenic assays, low dose RT in combination with Nx was found to have similar inhibition of surviving fraction compared to high dose RT in androgen independent PC-3 cells. Isobologram analysis of these data depicted strong synergism. In addition, increased activation of Akt/NFKB signaling molecules was observed in PC-3 cells exposed to radiation. The observed radiation-induced increase in these signaling molecules was either abolished (p-rpS6, p-NFKB and p-p70S6K) or decreased (p-Akt) in cells pretreated with Nx (8 hours) prior to RT. Additionally, Nx pretreatment prolonged the G2/M arrest caused by RT in PC-3 cells. Strikingly, knockdown of rpS6 in PC-3 cells reversed the observed effects of Nx, indicating the importance of rpS6 in mediating these changes. Furthermore, administration of Nx in combination with RT inhibited prostate tumor progression in transgenic adenocarcinoma of the mouse prostate (TRAMP) mice with no prominent toxicity. Notably, immunohistochemical analysis revealed decreased levels of p-mTOR, p70S6K, NFKB, Ki67 and Cyclin D1 in the prostate in combination group of animals compared to monotherapy. Taken together, our data suggest that Nx sensitizes PCA cells by down regulating rpS6 and delays progression to lethal disease. Remarkably, in a recent phase 0/1 study patients (81%) receiving Nx showed decreased PSA levels with no signs of grade 3 toxicity. Thus, Nx shows immense potential for use as an adjuvant in combination with conventional therapy for effective clinical management of PCA. Supported by NCCAM (R01 AT-007448) and VA-MERIT Award (I01 BX 000766; APK) Citation Format: Suleman S. Hussain, Paul Rivas, Roble G. Bedolla, Nikos Papanikolaou, Robert L. Reddick, Brad H. Pollock, Daniel C. Chan, Rita Ghosh, Addanki P. Kumar. Downregulation of ribosomal protein S6 overcomes radioresistance in prostate cancer. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 1797. doi:10.1158/1538-7445.AM2015-1797

Extracting the Benefit of Nexrutine® for Cancer Prevention.

The current standard of care for prostate cancer includes hormone therapy, radiation therapy and radical prostatectomy, each with its own set of undesirable side effects. In this regard there is an unmet need to develop strategies that can prevent or delay the development of clinical prostate cancer. One potential area involves the use of natural compounds involving botanicals. Along these lines we have found that Nexrutine®, a dietary supplement derived from Phellodendron amurense bark extract, has prostate cancer prevention activity. The "extract" nature of this botanical, which constitutes a blend of several active protoberberine alkaloids, allows it to target several pathways deregulated in prostate cancer simultaneously. In this review, we will emphasize the prospective translational benefit of Nexrutine® as a chemopreventive agent for prostate cancer management. The potential of Nexrutine® was first identified and has subsequently been most exhaustively studied with reference to prostate cancer. Therefore the focus of this review is on the use of Nexrutine® in prostate cancer. In addition we have summarized the emerging evidence regarding the use of Nexrutine® in other tumor models to demonstrate the potential benefits of Nexrutine®.

Palmatine inhibits growth and invasion in prostate cancer cell: Potential role for rpS6/NFκB/FLIP.

Novel agents are desperately needed for improving the quality of life and 5-year survival to more than 30% for metastatic castrate-resistant prostate cancer. Previously we showed that Nexrutine, Phellodendron amurense bark extract, inhibits prostate tumor growth in vitro and in vivo. Subsequently using biochemical fractionation we identified butanol fraction contributes to the observed biological activities. We report here that palmatine, which is present in the butanol fraction, selectively inhibits growth of prostate cancer cells without significant effect on non-tumorigenic prostate epithelial cells. By screening receptor tyrosine kinases in a protein kinase array, we identified ribosomal protein S6, a downstream target of p70S6K and the Akt/mTOR signaling cascade as a potential target. We further show that palmatine treatment is associated with decreased activation of NFκB and its downstream target gene FLIP. These events led to inhibition of invasion. Similar results were obtained using parent extract Nexrutine (Nx) suggesting that palmatine either in the purified form or as one of the components in Nx is a potent cytotoxic agent with tumor invasion inhibitory properties. Synergistic inhibition of rpS6/NFκB/FLIP axis with palmatine may have therapeutic potential for the treatment of prostate cancer and possibly other malignancies with their constitutive activation. These data support a biological link between rpS6/NFκB/FLIP in mediating palmatine-induced inhibitory effects and warrants additional preclinical studies to test its therapeutic efficacy.

Abstract 4216: Antitumor effect of Nexrutine, a phellodendron amurense bark extract, in multiple myeloma

Abstract Multiple myeloma (MM), a clonal malignancy of plasma cells, is the second most common adult hematological malignancy with approximately 15,000 new cases diagnosed annually. Despite recent advances in its clinical management, morbidity and mortality associated with MM remain high and there is a need for continuing development of novel anti-myeloma agents. Nexrutine, a non-toxic herbal extract from the bark of Chinese tree Phellodendron amurense, has been shown to exert significant anti-tumor effects in animal models of prostate cancer and is currently being evaluated in phase I/II clinical trials in patients with prostate cancer. In this study, we investigated the potential anti-tumor effect of nexrutine in MM. Exposure to nexrutine (3-100µg/ml) reduced viability of murine 5TGM1 and human RPMI 8226 MM cells in a dose- and time-dependent manner, independent of cell cycle disruption. Loss of cell viability was due primarily to apoptosis as indicated by >2-fold increase in annexin V+, 7AAD- cells and increased DNA fragmentation detectable by 24 hours. Previous studies showed that down-regulation of short-lived anti-apoptotic protein myeloid cell leukemia-1 (Mcl-1), in part by caspase-dependent cleavage of the full-length protein (Mcl-1L) to generate smaller (pro-apoptotic) Mcl-1 fragments, plays a major role in execution of apoptosis in MM cells. Nexrutine-induced apoptosis in MM cells was associated with reduced levels of Mcl-1L, caspase activation as indicated by a large increase in the active 17kDa cleavage product of procaspase 3 and an increase in pro-apoptotic Mcl-1 cleavage product. Nexrutine also inhibited the mammalian target of rapamycin (mTOR) and this was accompanied by accumulation of LC3-II, a marker of autophagosomes, in autophagy-competent MM cells. However, treatment of MM with cells with either pepstatin A and E64D that target lysosomal proteases involved in autophagy or with chloroquine, a lysosomotrophic autophagy inhibitor also resulted in cytotoxicity and these autophagy inhibitors did not rescue nexrutine-induced loss of viability in MM cells suggesting that autophagy plays a role constitutively in MM cell survival. Finally, we evaluated potential in vivo anti-tumor efficacy of nexrutine in the well-characterized preclinical model of MM in which 5TGM1 cells are inoculated intravenously in syngeneic naïve female C57BL/KaLwRij mice. Administration of nexrutine (400µg/mouse p.o. by gavage 6 days/week for 5 weeks) to tumor-bearing mice reduced serum levels of the monoclonal IgG2bκ paraprotein, a surrogate for tumor progression and overall tumor burden. Collectively, our results indicate an anti-myeloma effect of nexrutine and support further extensive preclinical testing and early phase clinical trial of this non-toxic herbal extract in MM. Our data also indicate that a combination of nexrutine and one or more autophagy inhibitors would result in enhanced anti-tumor effect in MM. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 4216. doi:10.1158/1538-7445.AM2011-4216

Natural Products: Potential for Developing Phellodendron amurense Bark Extract for Prostate Cancer Management

Our ability to detect and treat most primary cancers has improved dramatically given the advances in our understanding of cancer biology. However, with increased life expectancy and our inability to treat or cure advanced stages of cancers, the number of cancer-related deaths is expected to double in the next decade. Epidemiological studies suggest that dietary factors are an important aspect that influences cancer risk. Despite a lack of scientific evidence in most cases, cancer patients have whole-heartedly accepted the concept of "alternative medicine" using natural compounds and spent more than $1B a year on herbal supplements. Given the significant toxicity-associated problems with current long-term standard of care, scientifically validated natural supplements can serve as novel and effective alternative strategies for effective cancer management. We will discuss the utility of natural products in modulating critical signaling pathways for effective cancer prevention with special emphasis on prostate cancer and their potential translational benefit.

Abstract 5389: Enhanced inhibition of proliferation of pancreatic cancer cells by combination of gemcitabine and phellodendron amurense bark extract: target identification

Abstract Enhanced inhibition of proliferation of pancreatic cancer cells by combination of Gemcitabine and Phellodendron amurense bark extract: target identification Jingjing Gong, James W Freeman and Addanki P Kumar Department of Urology, School of Medicine, The University of Texas Health Science Center, 7703 Floyd Curl Drive, San Antonio, TX-78229 Pancreatic cancer (PanCA) is a leading cause of cancer-related death in the world due to rapid disease progression and high invasiveness. In addition, development of therapeutic resistance to chemotherapeutic agents is one of the challenges for developing effective strategies for PanCA. Phellodendron amurense is a widely used Chinese herbal medicine that has been used as antidiarrheal, astringent anti-inflammatory agent. Recent studies from our laboratory demonstrated that this extract inhibits prostate cancer cell proliferation through modulation of multiple targets including Akt, transcription factors cyclic-AMP response element binding protein (CREB) and NFκB and their downstream targets such as Cyclin D1 and Cox-2. Given the published data showing activation of these signaling molecules during PanCA development, we explored the utility of Nexrutine (Nx, Phellodendron amurense bark extract) alone and in combination with Gemcitabine (standard of care for PanCA) in PanCA to examine if it can either enhance the effects of Gemcitabine or overcome chemoresistance. Human pancreatic cancer cells that differ in the status of K-Ras (BxPC-3 with wild type K-Ras and CaPan-2, MIA PaCa-2, AsPC-1 with mutant K-Ras) and non tumorigenic HPNE-Ras cells were tested for growth inhibition, apoptosis, necrosis, Cox-2 expression and activity following treatment with Nx. Our data indicate that Nx can significantly inhibit proliferation of these five cell lines with IC50 varying from 50-100 µg/ml depending on the cell type. Results also indicate that Nx inhibits proliferation of PanCA cells through induction of apoptosis and necrosis. Further we have identified that anti-proliferation effects of Nx is associated with reduction in the level (Cox-2) and activity (PGE2 and PGF2α) in multiple PanCA cell lines. Interestingly PGE2 receptor EP2 is also modulated in response to Nx treatment suggesting an important role for PGE2-mediated signaling in Nx-induced inhibition of pancreatic cancer cell growth. In addition, in vitro, Nx increased the inhibitory effect of Gemcitabine on cell proliferation in MIA PaCa-2 and CaPan-2 but not in AsPC-1 pancreatic cancer cells. These results indicate that molecular targeting of multiple signaling pathways in combination with Gemcitabine may improve the sensitivity probably by increased apoptosis and inhibition of invasion along with down regulation of PGE2/Cox-2 signaling (Supported by pilot funds from Cancer Therapy and Research Center, San Antonio, TX). Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 5389.

Regulation of Cox-2 by Cyclic AMP Response Element Binding Protein in Prostate Cancer: Potential Role for Nexrutine

We recently showed that NexrutineR, a Phellodendron amurense bark extract, suppresses proliferation of prostate cancer cell lines and tumor development in the transgenic adenocarcinoma of mouse prostate (TRAMP) model. Our data also indicate that the antiproliferative effects of NexrutineR are mediated in part by Akt and Cyclic AMP response element binding protein (CREB). Cyclooxygenase (Cox-2), a pro-inflammatory mediator, is a CREB target that induces prostaglandin E2 (PGE2) and suppresses apoptosis. Treatment of LNCaP cells with NexrutineR reduced tumor necrosis factor α-induced enzymatic as well as promoter activities of Cox-2. NexrutineR also reduced the expression and promoter activity of Cox-2 in PC-3 cells that express high constitutive levels of Cox-2. Deletion analysis coupled with mutational analysis of the Cox-2 promoter identified CRE as being sufficient for mediating NexrutineR response. Immunohistochemical analysis of human prostate tumors show increased expression of CREB and DNA binding activity in high-grade tumors (three-fold higher in human prostate tumors compared to normal prostate; P = .01). We have identified CREB-mediated activation of Cox-2 as a potential signaling pathway in prostate cancer which can be blocked with a nontoxic, cost-effective dietary supplement like NexrutineR, demonstrating a prospective for development of NexrutineR for prostate cancer management.