Composite Pheochromocytoma Presenting as Severe Lactic Acidosis and Back Pain: A Case Report

Pheochromocytoma is a rare, catecholamine secreting tumor arising from chromaffin cells. Presentation of this tumor is highly variable, the most common being hypertension, tachycardia, sweating, and headache. Lactic acidosis and back pain are rare complications of this tumor. We report a 51-year-old gentleman with composite pheochromocytoma, which is rarer than pheochromocytoma, presenting as severe back pain and lactic acidosis.

A pilot, randomized, double-blind, placebo-controlled trial to assess the safety and efficacy of a novel Boswellia serrata extract in the management of osteoarthritis of the knee

A double-blind, placebo-controlled human trial was conducted to evaluate the safety and efficacy of a standardized oral supplementation of Boswellin®, a novel extract of Boswellia serrata extract (BSE) containing 3-acetyl-11-keto-β-boswellic acid (AKBBA) with β-boswellic acid (BBA). A total of 48 patients with osteoarthritis (OA) of the knee were randomized and allocated to the BSE and placebo groups for intervention. Patients were administered BSE or placebo for a period of 120 days. The trial results revealed that BSE treatment significantly improved the physical function of the patients by reducing pain and stiffness compared with placebo. Radiographic assessments showed improved knee joint gap and reduced osteophytes (spur) confirming the efficacy of BSE treatment. BSE also significantly reduced the serum levels of high-sensitive C-reactive protein, a potential inflammatory marker associated with OA of the knee. No serious adverse events were reported. This is the first study with BSE conducted for a period of 120 days, longer than any other previous clinical trial on patients with OA of the knee. The findings provide evidence that biologically active constituents of BSE, namely, AKBBA and BBA, act synergistically to exert anti-inflammatory/anti-arthritic activity showing improvement in physical and functional ability and reducing the pain and stiffness.

Antitumor activity of melinjo (Gnetum gnemon L.) seed extract in human and murine tumor models in vitro and in a colon-26 tumor-bearing mouse model in vivo

Melinjo (Gnetum gnemon L.) seed extract (MSE) and its active ingredient gnetin C (GC), a resveratrol dimer, have been shown to possess a broad spectrum of pharmacological activities. In this study, we investigated the antitumor activity of MSE and GC using human and murine tumor cell culture models in vitro. The antitumor activity of GC was compared with trans-resveratrol (tRV), a stilbenoid polyphenol. Our results show that MSE and GC at clinically achievable concentrations significantly inhibited the proliferation of pancreatic, prostate, breast, and colon cancer cell types (P < 0.05), without affecting normal cells. Interestingly, GC exerts enhanced antitumor activity than that of tRV (P < 0.05). MSE and GC significantly induced apoptosis in all the cancer cells, indicating MSE and GC inhibit tumor cell growth by inducing apoptosis (P < 0.001). Our findings provide evidence that MSE might induce apoptosis in cancer cells via caspase-3/7-dependent and -independent mechanisms. However, GC might trigger both early and late stage apoptosis in cancer cells, at least in part by activating caspase 3/7-dependent mechanisms. Furthermore, the antitumor efficacy of MSE observed in vitro was also validated in a widely used colon-26 tumor-bearing mouse model. Oral administration of MSE at 50 and 100 mg/kg per day significantly inhibited tumor growth, intratumoral angiogenesis, and liver metastases in BALB/c mice bearing colon-26 tumors (P < 0.05). In conclusion, our findings provide evidence that MSE and GC have potent antitumor activity. Most importantly, we provide the first evidence that MSE inhibits tumor growth, intratumoral angiogenesis, and liver metastasis in a colon-26 tumor-bearing mice.

Abstract 325: Multiple myeloma in a physiologically relevant Me-HA -3D Hydrogel: Discovering new phenotypes of drug resistance

Background: Extracellular matrix (ECM) characteristics, including stiffness, geometry, chemistry, and spatial interaction with the neighboring cells and soluble factors are key components for cancer cell survival in a pathogenic tissue microenvironment (TME). However, poor performance of 2D in vitro systems and animal models for metastatic cancer types demands physiologically relevant well controlled 3D platforms to quantitatively assess (a) metastatic cancer stem cell survival (b) oncogenic mechanisms and (c) drug resistant phenotypes and (d) new drug efficacy. Advances in the “state of the art” 3D platforms with difference in matrix stiffness and viscoelastic properties are showing promising results in identifying changes in drug resistant phenotypes, cell behavior and gene expression profiles. Preliminary findings by us and others using 3D matrices for human multiple myeloma (MM) reveal promising results on cancer /stromal cell interactions. In this study we have shown that Hyaluronic acid (HA) based 3D hydrogel support human metastatic MM cancer cells survival and thus reveal new oncogenic mechanisms of drug resistant cancer stem cells.

Experimental approaches: Bone marrow derived CD138 positive cells and BMSCs were isolated from MM patient samples (with IRB approval) using magnetically labeled CD138 MicroBeads (autoMACS Pro Starting Kit). Bone marrow stromal cells (BMSCs) were cultured as described by us earlier. Cell viability measurements and quantitative RT-PCR for c-myc and other related gene targets were performed using total RNA. Me-HA-3D hydrogels were created containing either fibronectin/collagen/laminin or ME-HA mixture of Matrigel/fibronectin/laminin in different ratios. Cells were grown as surface seeded or encapsulated in Me-HA gels, and analyzed between 4 and 21 days in the conditioned medium. Cell proliferation analysis was performed by both MTS and live dead cell assays using CFSE stain.

Results: The overall cell viability by surface coating and in encapsulated gel was found to be higher than 80% for up to 21 days in all the conditions including changes in the UV cross linking time and gel stiffness. Colony forming units (CFU) of the mononuclear cells were higher (27%) at 21 days compared to the 4 days 3% (p&gt;0.001). Spheroids were found on the surface of the hydrogels with PC-3 cells as well as inside the encapsulated hydrogels specifically for MM, and were higher in numbers (&gt;30%) compared to that in surface coating (5%) p&gt;0.001. qRT-PCR analysis determined c-myc, cyclin D1, E-cadherin, and ZEB-1 showed&gt;4 fold increase (p&gt;0.001) in encapsulated cells compared to that in cells transfected with siRNA for c-myc, suggesting c-myc mediated cell survival in 3D.

Summary: Me-HA hydrogels are found to be suitable platform for the first time to identify new metastatic cancer phenotypes types and to investigate drug resistance mechanisms.

Citation Format: Bhagavathi A. Narayanan, Bin Duan, Narayanan K. Narayanan, Jonathan Butcher Butcher, Amitabha Mazumder. Multiple myeloma in a physiologically relevant Me-HA -3D Hydrogel: Discovering new phenotypes of drug resistance. [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 325. doi:10.1158/1538-7445.AM2015-325

Abstract 2800: Dietary black raspberries (BRBs) inhibit tumor progression in PTEN-deficient mouse model of prostate cancer

Black raspberries (BRBs) a natural food demonstrated to have anti-oxidant, anti-inflammatory and anti-cancer activities,have been shown to inhibit oral, esophageal, mammary gland and colon cancers in rodents. Several human trials have been completed to date to assess the efficacy of BRB formulations for cancer prevention. However, the chemopreventive potential of BRBs against prostate cancer, the most commonly diagnosed malignancy and the second leading cause of death among men in the United States, is yet to be reported. Among the murine models, PTEN-mutant mice develop tumors in situ that faithfully mimic the intratumor heterogeneity observed during the progression of human prostate cancer. Therefore, we utilized this clinically relevant PTEN-mutant mouse model to evaluate the chemopreventive potential of BRBs against prostate cancer.

Genotyped 5-week-old male PTEN-mutant mice, randomly assigned to control and treatment groups (n = 12 mice/group), were fed AIN-93G diet (control) or AIN-93G diet supplemented with BRBs (5 or 10%) for 23 weeks. Age-matched non-transgenic mice (wild-type) served as experimental controls (n = 6). Animal weight and food consumption were measured during the treatment period, and the mice were euthanized at 28 weeks of age. Prostate tissues were harvested, weighed and fixed in 10% formalin for histopathological analysis. Histological, cell proliferation (Ki-67 staining) and apoptosis (TUNEL) analyses were performed to determine the chemopreventive potential of BRBs.

PTEN-mutant mice fed control or BRB (5 or 10%) diets had steady body weight gain, 16 to 18 g during the 23-week treatment. BRB diets were well tolerated as none of the animals fed BRBs exhibited any observable toxicity. PTEN-mutant mice (control) had increased prostate weight (ave. = 248 mg) relative to wild-type mouse prostate (ave. = 90 mg), and 5 and 10% BRB diets significantly (p&lt;0.01) decreased the prostate weights to ave. = 116 and 162 mg, respectively, compared to control. In addition, 5% BRBs significantly (p&lt;0.05) reduced the prostate weights compared to 10% BRBs. Histological examination of dorsolateral prostate (DLP) revealed that 98% of PTEN-mutant mice fed control diet developed invasive adenocarcinomas, whereas both 5 and 10% BRB diets significantly reduced tumor incidence and the progression of PIN lesions to invasive adenocarcinomas by 64% (p&lt;0.0001) and 43% (p&lt;0.001), respectively. Interestingly, 5% BRBs appear to be more effective than 10% BRBs (p&lt;0.01). Both 5 and 10% BRBs significantly reduced tumor cell proliferation rates and induced apoptosis, p&lt;0.0001 and p&lt;0.001, respectively. Furthermore, mice fed both 5 and 10% BRBs contained more normal appearing prostates (free from PIN lesions and adenocarcinomas), when compared to control mice (54 and 33% compared to 3%, respectively). In conclusion, our data indicate that BRBs may have significant potential for prostate cancer prevention and/or treatment.

Citation Format: Narayanan K. Narayanan, Gary D. Stoner, Daniel S. Peiffer, Karen Galdanes, Eric Larios, Alu Mark, Lisa Maziniski, Luis Chiriboga, Maarten C. Bosland. Dietary black raspberries (BRBs) inhibit tumor progression in PTEN-deficient mouse model of 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 2800. doi:10.1158/1538-7445.AM2015-2800

Abstract B57: Gnetin C, a novel resveratrol dimer, targets pancreatic cancer metabolism

Background: Pancreatic ductal adenocarcinoma (PDAC) is aggressively invasive and treatment-resistant malignancy, and is the fourth leading cause of cancer deaths in the United States. The pancreatic cancer cells alter specific metabolic pathways to meet their tremendous energy and biomass demands which contribute to the progression and dissemination of this disease. More importantly, the oncogenic signaling enables cancer cells to reprogram the cellular metabolism that afford growth and proliferative advantages over normal cells and, thus, may contribute to pancreatic cancer pathophysiology. There is an increasing interest to investigate the oncogenic signaling that controls the metabolic reprogramming of cancer cells.

Objectives: Mammalian Target of Rapamycin (mTOR), a central downstream target of Akt, is a highly conserved protein kinase, and is frequent activated in PDAs. Earlier studies reported that mTOR, a master regulator of cell growth and proliferation downstream of oncogenic signaling pathways, controls specific aspects of cellular metabolism through the induction of metabolic gene expression. In our earlier microarray studies, we observed differential expression of genes associated with glucose and lipid metabolic pathways, with concomitant increase in mTOR expression. However, the mechanism and critical link between mTOR and the pancreatic cancer metabolism has not been fully understood.

Methodology: In the present study, we evaluated the effectiveness of Melinjo (Indonesian name; Gnetum gnemon L.) seed extract (MSE) and gnetin C (GC), a resveratrol dimer found abundantly in MSE in human (Aspc-1 and PANC-1) and mouse (Pan-02) pancreatic cancer cells. MSE has been reported to exert antioxidant, lipase and amylase inhibition, anti-metabolic syndrome effects and anticancer activities. A recent clinical study reported that MSE decreased serum uric acid and increased HDL cholesterol levels in humans, suggesting that MSE may improve lipid metabolism. To test the anti-tumor activities, pancreatic cancer cells were treated with various concentrations of MSE (0 - 400μg/ml) and GC (0 – 100μM) for 48 h. MTS cell proliferation and apoptotic assays were performed to determine the cell growth inhibition and induction of apoptosis. Trans-resveratrol (RES) that is abundant in grapes and wine was used to compare the effects of GC. Real-time PCR was performed to evaluate the effect of a MSE or GC on mTOR and its downstream targets, as well selected glucose and lipid metabolic pathway genes. Western blot was performed to confirm their expression at the protein level.

Results and conclusion: Human (ASPC-1 and PANC-1), and mouse (Pan-02) pancreatic cancer cells treated with MSE, GC and RES showed a dose-dependent decrease in cancer cell proliferation. The IC50 values of MSE, GC and RES related to their anti-proliferative effects revealed that GC, the major metabolite of MSE has superior anti-proliferative properties than resveratrol. Further, flow cytometry analysis showed a pre-G1 peak of apoptosis (&gt;10%) with GC. We observed that GC significantly downregulated mTOR complex, namely (mTORC1 and mTOC2). mTORC1 is a sensor of systemic and local levels of nutrients that regulates cancer cell proliferation and survival. mTORC2 is associated with the ribosome and insulin-stimulated oncogenic PI3K signaling. We also found that GC downregulated p-ribosomal protein S6 (p-RPS6), a downstream target of mTOR that plays important role in both neoplastic and inflammatory processes. In addition, GC also downregulated glycogen synthase kinase 3 alpha and beta (GSK3α and β) that is linked to glycogen metabolism and 3-hydroxy-3-methylglutaryl-CoA synthase 1 (HMGCS1), which is associated with lipids and lipoproteins metabolism (cholesterol biosynthesis). Further analysis on key genes of the lipid metabolism is in progress. Given the preliminary evidence that GC has superior anti-proliferative activities and its ability to inhibit mTOR and metabolic/lipid pathway genes can be expected to yield more potent therapies against this deadly disease. The future goal will be to test the potentials of GC on the antitumor efficacy and the effect on metabolic pathway targets in preclinical animal models of pancreatic cancer.

Citation Format: Narayanan K. Narayanan, Kazuhiro Kunimasa, Di Tian, Lori Horton, Igor Dolgaev, Adriana Heguy, George Miller, Amit Tiwari, Bhagavathi A. Narayanan. Gnetin C, a novel resveratrol dimer, targets pancreatic cancer metabolism. [abstract]. In: Proceedings of the AACR Special Conference on Pancreatic Cancer: Innovations in Research and Treatment; May 18-21, 2014; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2015;75(13 Suppl):Abstract nr B57.

Abstract 4049: Stromal Wnt/β-catenin antagonism with DKK1 promotes clonal expansion of multiple myeloma is identified using hyaluronic acid based 3D hydrogel

Multiple myeloma (MM), an incurable cancer with 3- to 5-year survival is characterized by monoclonal immunoglobulin (Ig), lytic bone lesions and monoclonal plasma cells (PCs) in the bone marrow (BM). Because clonal expansion of primary MM cells outside their BM microenvironment has been unsuccessful, most pre-clinical studies have used MM cell lines derived from leukemic-phase cells that have escaped BM dependence. Therefore it is likely that BM niches maintain MM cancer stem cells (MM-CSCs) in a quiescent, drug-resistant state. To date, pre-clinical models do not take into account adhesion-mediated drug resistance and none allows for testing of drug efficacy on MM-CSC populations. Mouse models of MM are inadequate for pre-clinical use because they cannot faithfully recapitulate human disease. Recently, a stromal spheroid co-culture model and various scaffolds have been developed to recreate the 3D environment of the BM. To adequately investigate underlying mechanisms of B-cell development and the stromal influence on MM pathogenesis, there is a great need for a 3D cell culture system. In the present study, we used hyaluronic acid based 3D hydrogel for surface seeding and encapsulation of human multiple myeloma (BMMCs) and the bone marrow stromal cells (BMSCs) to investigate MM clonal migration and the new phenotype exhibiting cellular changes associated with Wnt/βcatenin signaling. For the first time we report, (a) hyaluronic acid HA-based 3D hydrogels with difference in the matrix composition and stiffness provide a suitable substratum for migration and clonal expansion of human primary BMMCs; (b) Homogenous encapsulation of 5x105 BMMCs showed development of small colonies identified as multiple thin, flat cells emanating from a central cluster of rounded cells as colony forming units (CFUs). We observed an increase in CFUs in hydrogel with medium stiffness of Me-HA at 14 days (ranging from 16 to 17%, p&lt;0.05) and at 21 days (ranging from 26 to 27%, p&lt;0.01) in contrast to that in 2D or in a commercial matrigel; (c) immunofluorescence detection of cytoplasmic and nuclear expression of β-catenin showed a higher expression (&gt;4 fold) in the 3D encapsulated differentiating cells compared to that in the non-differentiating single cells; (d) our findings using ELISA assays for sDKK1 showed a gradual increase in DKK1 with a maximum at 21 days (p&lt;0.001), suggesting the possible influence of stromal BMSCs on DKK1 production in contrast to earlier reports of DKK1 inhibiting Wnt signaling. Our findings support the use of 3D (ex vivo system) hydrogel for MM to dissect the Wnt-β-catenin/DKK1 signaling activities and further to screening for drug targets in bone-related human multiple myeloma.

Citation Format: Bhagavathi A. Narayanan, Bin Duan, Jonathan T. Butcher, Amitabha Mazumder, Narayanan K. Narayanan. Stromal Wnt/β-catenin antagonism with DKK1 promotes clonal expansion of multiple myeloma is identified using hyaluronic acid based 3D hydrogel. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 4049. doi:10.1158/1538-7445.AM2014-4049

Characterization of multiple myeloma clonal cell expansion and stromal Wnt/β-catenin signaling in hyaluronic acid-based 3D hydrogel

BACKGROUND

Emerging interest on three-dimensional (3D) cell culture models to replace two-dimensional cultures of cancer cells and their xenografts in immunocompromised animal hosts prompted us to investigate the use of new biodegradable gels to recapitulate the physiological conditions of the microenvironment of multiple myeloma (MM) cells.

MATERIALS AND METHODS

In the present study, for the first time, we used a new 3D model of hyaluronic acid (HA)-based hydrogels with difference in their matrix composition and stiffness.

RESULTS

We demonstrated that hyaluronic acid (HA)-based hydrogels perfectly accommodate MM cells; confirmed by cell survival, migration, colony forming units and expression of cell adhesion proteins of the Wnt signaling pathways over a period of time.

CONCLUSION

This study provides the first 3D microenvironment data that HA-based hydrogels could provide with a suitable 3D substratum for MM cells to comprehensively analyze phenotypic changes and the influence of bone marrow stromal stem cells on Wnt/β catenin signaling in response to targeted drug treatments.

Abstract B27: Tripterine induced cell cycle arrest and apoptosis is associated with modulation of PI3K-AKT-mTOR pathway in human pancreatic cancer cell

Pancreatic cancer is the most common cancer among men and women; the fourth leading cause of cancer death in the United States and the fifth leading cause of cancer death worldwide. This disease has a poor prognosis with a 5-year overall survival rate of less than 20%. Multiple mechanisms have been postulated for the development of benign and malignant pancreatic diseases. However, the nature and origin of the precursor cells for pancreatic cancer have not yet been delineated. Based on several molecular mechanism(s) proposed for pancreatic cancer, the phosphoinositide 3-kinase (PI3K)/Akt pathway is found to be constitutively activated and the mammalian target of rapamycin (mTOR) kinase is reported to be an important mediator for its signaling. The phosphoinositide 3-kinase-AKT-mammalian target of rapamycin (PI3K-AKT-mTOR) pathway is a frequently hyper activated pathway in cancer and is important for tumor cell growth and survival. The development of targeted therapies against mTOR pathway led to the approval of drugs including everolimus and temsirolimus, for the treatment pancreatic and other cancer types. However, the effectiveness and response among high risk patients still remains unclear. Epidemiologic and laboratory studies suggest that plant-derived bioactive food components reverse or prevent the development and progression of early-stage disease before it becomes aggressive and malignant. Lately, naturally occurring non-toxic dietary compounds are increasingly used as a novel strategy for the prevention of more aggressive cancers. Previous reports from our laboratory suggest that prolonged exposure of cancer cells to natural agents may effectively modulate mTOR signaling and promote anti-proliferative effects. In the present study, we evaluated the effectiveness of celastrol in human (AsPC-1) and mouse (Pan-02) pancreatic cancer cells. Celastrol is a plant extract isolated from the root extract of Tripterygium Wilfordi (Thunder of God vine -TGV) and Celastrus Regelii, is also known as tripterine, a multiple bioactive natural product. Recent studies suggest that celastrol may exhibit antioxidant, anti-inflammatory, anticancer, and insecticidal activities. However, a significant lack of information on the bioavailability and the effect on specific molecular targets of celastrol is unknown and is therefore limiting its use for future clinical trials. our preliminary findings on the oral administration of celastrol (10mg/KgBW) and TGV separately to C57BL/6 black mice showed no toxicity or animal death (n=24). Subsequent analysis of serum samples showed bioavailability of celastrol with a retention time between 12 to 15 minutes. Human pancreatic cancer cells AsPC-1, and mouse pancreatic cancer cell Pan-02, treated with celastrol showed a significant decrease in cell proliferation (&gt;4 fold) after 24h with a dose of 20ug/ml (confirmed by MTS assay). In order to determine whether the cell growth inhibition is associated with an effect on cell cycle, we conducted flow cytometry analysis for DNA content. Pan-02 cells treated with celastrol at an optimum dose of 10ug/ml showed cell cycle arrest at the G1 phase. Further analysis of the flow cytometry data showed a pre-G1 peak of apoptosis (&gt;10%). Based on the findings on celastrol inducing cell cycle arrest and apoptosis, we extended our studies to determine the effect on the downstream targets of PI3K-AKT-mTOR pathways. RT-PCR analysis for AKT using specific primers with RNA isolated from pancreatic cancer cells showed a decrease in the mRNA (&gt;2 fold). Further studies are in progress to confirm a specific dose dependent effect celastrol and TGV on the downstream targets of the PI3K-AKT-mTOR and cell cycle regulatory proteins including cyclin D1 in pancreatic cancer cells. The future goal will be to test the efficacy of celastrol and TGV in preclinical animal models of pancreatic cancer. Overall, our findings suggest the potential molecular targets of celastrol in pancreatic cancer cells.

Citation Format: Di Tian, Bhagavathi Narayanan, Amitabha Mazumder, George Miller, Narayanan K. Narayanan. Tripterine induced cell cycle arrest and apoptosis is associated with modulation of PI3K-AKT-mTOR pathway in human pancreatic cancer cell. [abstract]. In: Proceedings of the Twelfth Annual AACR International Conference on Frontiers in Cancer Prevention Research; 2013 Oct 27-30; National Harbor, MD. Philadelphia (PA): AACR; Can Prev Res 2013;6(11 Suppl): Abstract nr B27.

Antagonistic effect of small-molecule inhibitors of Wnt/β-catenin in multiple myeloma

BACKGROUND

Development and progression of multiple myeloma is dependent on the bone marrow (BM) microenvironment, and within the BM, a number of factors are secreted, including the Wnt ligands. Bone marrow stromal cells (BMSC) secrete Wnt ligands that activate Wnt signaling in multiple myeloma. The canonical Wnt pathway which is mediated through the transcriptional effector β-catenin (β-cat) is commonly de-regulated in many cancers. Cells with active β-cat-regulated transcription (CRT) are protected against apoptosis; conversely, inhibition of CRT may prevent cell proliferation.

MATERIALS AND METHODS

In this study, we tested the efficacy of recently described inhibitors of CRT (iCRTs; oxazole and thiazole) for their selective antagonistic effect on Wnt-β-cat response in MM cells MM.1, U266, BMSC and primary BMMC obtained from patient samples (n=16).

RESULTS

We demonstrated that iCRTs we used, block Wnt/β-cat reporter activity, down regulate β-cat expression and inhibit cell proliferation in a dose-dependent manner with an optimal dose closer to 15 μM. Our data further indicate that iCRTs do not influence the expression of the upstream components of the Wnt pathway DKK1 at the optimal dose, suggesting that iCRTs may specifically target β-cat in MM cells. Additionally, iCRT-treatment of MM cells, co-cultured with BMSC, showed an inhibitory effect on VEGF and cell migration.

CONCLUSION

This study provides the first in vitro data evaluation of newly-described iCRTs as potential Wnt-β-cat/VEGF pathway antagonists in multiple myeloma.

Modulation of PGE2-induced EP4 expression on snail signaling and the impact on epithelial-mesenchymal transition: significance of EP4 antagonism

BACKGROUND

Although significant accumulation of prostaglandin E(2) (PGE(2)) in the human prostate cancer tissues has been reported, there is lack of substantial evidence regarding the key role of PGE(2)-induced E-prostanoid-4 receptor (EP4) on Snail, a master regulator of epithelial mesenchymal transition (EMT). In this study, we investigated a novel connection between PGE(2)-induced EP4 and Snail (encodes DNA binding zinc finger protein that acts as transcriptional repressor) signaling in prostate cancer.

MATERIALS AND METHODS

To investigate the key role of serum PGE(2), EP4, p-Akt and Snail in prostate cancer progression, we used prostate-specific phosphatase and tensin homolog (PTEN)-knockout (PTEN-KO) mice of different age groups from 4 to 28 weeks. To determine the EP4-specific interaction with Snail in prostate cancer, we used cell-based assays, including siRNA knockdown, and treatment with EP4 antagonist.

RESULTS

An interaction between EP4 with Snail was evident in prostate-specific PTEN-KO mice that showed an elevated level of PGE(2) in the serum and of EP4, p-Akt and Snail in the tissues. Prostate cancer cells transfected with EP4-siRNA and treatments with EP4 antagonist suggest a link between EP4, and Snail activation, potentially via p-Akt. Cells treated with EP4 antagonist exhibited a significant decrease in Snail, mesenchymal markers and cell migration, and cell cycle arrest with a gain in E-cadherin levels.

CONCLUSION

Our findings provide key evidence that support there being a role of PGE(2)/EP4/p-Akt in Snail signaling and conferring cell survival advantage. Cancer progression via EMT can be reversed by an EP4 antagonist in this model of prostate cancer.

Genome-wide analysis and identification of genes related to expansin gene family in indica rice

In this study, we carried out genome-wide analyses to explore expansin gene family in the genome of indica rice. Reference nucleotides were chosen as query sequences for searches in the indica rice genome database. Clones having genomic sequences similar to expansin were taken and converted to amino acid sequences. Putative sequences were subjected to PROSITE and Pfam databases, and 21 signature-sequences-related expansin gene family was obtained. The presence of transmembrane domains was also predicted for all 21 expansin proteins. A phylogenetic tree was generated from the alignments of the proteins sequences to examine the phylogenetic relationship of indica rice expansin proteins.

Abstract 4032: Elevated level of let-7a and mir-30c microRNAs in human prostate cancer

MicroRNAs (miRNAs) are endogenously expressed non-coding RNAs that negatively regulate the expression of protein coding genes at the translational level. Evidence from recent studies suggests that cancer development is associated with deregulation of specific set of miRNAs that determines the cancer characteristics. Recently, miRNA profiling has been shown to identify cancer specific miRNA signatures that are specific to different cellular origin. However, the functional significance of specific miRNAs in prostate cancer developmental stages remains to be investigated. Further, identification and characterization of tumor derived miRNAs using advanced and reliable techniques may benefit early detection and prevention strategies. In this study, to identify potential miRNAs in human prostate cancer tissue specimens, we used 15 human prostate cancer tissue microarrays (TMAs) with 36 cores in each representing different stages of the cancer. We detected the expression of miRNA let-7a and mir-30c by performing locked nucleic acid-in-situ hybridization (LNA-ISH) (EXIQON, Vedbaek, Denmark). To obtain maximal sensitivity of miRNA expression signal, we used double (3′ and 5″) digoxigenin-labeled LNA probes (MiRCURY LNA) of 20uM each after optimizing with lower and higher dilutions. Oversaturation was avoided by reducing the temperature (30-35°C) and the time of exposure (24h). As a negative control the tissues were hybridized either with mismatch or no probe. We determined the expression level of the miRNAs in (a) precancerous single acinus or small group of acini and (b) in the regions of prostatic adenocarcinoma or high grade PIN. Our findings indicated abundant expression of both let-7a and mir-30c localized only in the nucleus of the cells in HGPIN, in contrary to that in the early PIN lesions, where let-7 and mir-30c miRNAs were localized both in the cytoplasm, as well as in the nucleus. Interestingly, not all the acini showed a positive staining for let-7, suggesting the possibility of down regulation of let-7 in the non-neoplastic regions. Finally, the difference in the expression of let-7a and mir-30c in the stroma vs. tumor acini were compared and quantified to predict their functional significance related to tumor proliferation. Although the findings on the expression of let-7a and mir-30c were consistent in more than 20% of the TMAs examined, we observed weak or no signal in several of the tumor acini (5%) suggesting a heterogeneous expression pattern. Overall, our findings suggest that examining the expression level of miRNAs in the nucleus vs. cytoplasm of tumor cells at different stages of prostate cancer is critical to determine the functional status of let-7a and mir30c. Most importantly, monitoring a shift in their expression pattern will provide significant opportunities to define diagnostically useful miRNA as biomarkers.

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 4032.

Abstract 1475: Molecular mechanisms of “SNAIL” activation in invasive bladder cancer of p53/Rb double knockout mice exposed to chemical carcinogen BBN

Epithelial-mesenchymal transition (EMT) plays a central role in empowering tumor cells to acquire invasive properties. It appears that EMT is not a random process but is highly regulated by transcription regulators. Of particular interests are the transcription repressors that inhibit the expression of cell-cell junction proteins, such as E-cadherin. Recent in vitro studies indicate that increased signaling of “Snail” the transcription repressor per se is sufficient to confer an invasive phenotype on otherwise non-invasive cells. Despite these recent advances, relatively little is known about the mechanisms of Snail activation in invasive bladder cancer. In this study, using p53 and Rb double knockout mice exposed the carcinogen BBN, we examined the expression levels of “Snail” and E-cadherin protein in bladder cancer tissues. Findings from both immunohistochemical and immunofluorescence staining revealed overexpression of Snail in the stromal as well as in the tumor regions. Although a complete loss of E-cadherin was not evident in all the tumors examined, most of the sections analyzed showed a moderate to weak expression of E-cadherin. This is consistent with the findings from Western blot analysis of the protein lysate from human bladder cancer cells with varying status of p53 and Rb. To explore the mechanism of Snail activation leading invasive bladder cancer, we transfected the human bladder cancer cells with siRNAs for Snail, p53 and Rb. Our findings were consistent with the in vivo studies, in that Western blot analysis revealed only a moderate inhibition of E-cadherin in p53 or Rb knockout cells. However, the Snail knockout cells showed less invasiveness (migration) compared to the control, and was associated with a significant inhibition of E-cadherin expression. To investigate further on the possible role of TGFβ on Snail activation, we treated the bladder cancer cells with TGFβ for 12h and examined the effect on Smad 4 and 7, Snail and E-cadherin expression. Activation of Snail was associated the expression of vimentin, a typical marker of mesenchymal cells, and cytokeratins of epithelial cells suggesting TGFβ mediated Snail activation. Finally, we extended our analysis to determine the role of noncoding microRNAs that act as post-transcriptional repressors. To this end we performed microRNA profiling of J82 and HT1376 bladder cancer cells using human miRNA arrays. Findings on differential expression of potential microRNA network involved in the regulation of TGFβ, Snail and E-cadherin expression associated with urothelial tumor plasticity are discussed. Overall findings from these studies suggest possible mechanism(s) of Snail activation and E-cadherin regulation in invasive bladder cancer for the first time and may pave the way for novel therapeutic approaches.

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 1475.

Abstract LB-422: A novel mechanism for the anti-cancer effects of licofelone against testosterone and estradiol-17ß-induced prostate carcinogenesis: Selective modulation of the cross-talk between estrogen receptor and NF-κB

The chemopreventive and therapeutic potential of licofelone, an anti-inflammatory drug, has been reported in preclinical models against the cancers of the colon, breast, pancreas, and bladder, including prostate cancer (PCa). In contrast to nonsteroidal anti-inflammatory drugs (NSAIDs) and selective cyclooxygenase-2 (COX-2) inhibitors, licofelone exerts significantly less adverse effects under chronic use, and is currently undergoing phase III trials for osteoarthritis. However, the anticancer mechanism of licofelone is unclear. To elucidate the molecular mechanisms of licofelone, we used a short-term Noble (NBL) rat PCa model. Male NBL rats at 10 weeks of age were randomly assigned to control and three experimental groups (n=18 per group), and they were fed a semi-purified AIN-93M diet containing 0, 100, 200, and 300ppm of licofelone. After 2 weeks on control and licofelone diets, hormonal implants, the silastic tubing packed with testosterone (T) and estradiol-17 (E2), were placed subcutaneously in rats under anesthesia. Empty silastic implants (n=5 rats) served as vehicle control, and were fed semi-purified AIN-93M diet only. Dietary regimen was resumed immediately after the hormonal implantation, and all rats were sacrificed at the end of 16 weeks. To examine the anti-cancer activities of licofelone, histological, cell proliferation (ki67 staining), and apoptosis (TUNEL assay) analyses were performed using rat dorsolateral prostate (DLP) tissues. Serum T and E2 levels were measured using radioimmunoassay (RIA) kits. The levels of TNF-α, PGE2, and LTB4 in DLP tissues were analyzed using enzyme immunoassay EIA) kits. Real-time PCR, Western blot and immunohistochemical methods were used to determine the molecular targets at the mRNA and protein levels. Dietary administration of licofelone in NBL rats did not induce any toxic effect or weight loss. A 16-week hormonal treatment contributed chronic inflammation, and developed prostate intraepithelial neoplasia (PIN) in 88% of the rats (n=18). Histological analysis revealed that licofelone treatment suppressed PIN lesions significantly, in a dose-dependent manner; suppressed 21% at 100ppm, 47% at 200ppm, and 68% at 300ppm compared to the untreated control (p&lt;0.001). Further, licofelone at 300ppm significantly decreased the rate of tumor cell proliferation by 68%, and enhanced apoptosis by 8-fold in contrast to the untreated controls. T + E2 treatment-induced production of critical inflammatory mediators were significantly decreased by licofelone treatment at 300ppm (p&lt;0.001); prostaglandin E2 (PGE2) was reduced from 674 to 128 pg/mg protein, leukotriene B4 (LTB4) from 169 to 17 pg/mg protein, and tumor necrosis factor alpha (TNF-α) from 540 to 84 pg/mg protein. However, licofelone treatment had a minimal effect on COX-2 expression at the mRNA and protein level, and COX-1 level was not altered. These findings provide evidence that licofelone effectively suppressed the hormone-induced prostate carcinogenesis in NBL rats, independent of COX-2. Since estrogen receptors (ERα and ERß) are the main mediators of estrogen action in the prostate, it is plausible that a positive interaction between ERα and NF-κB (NF-κB) may trigger the transcriptional activation of pro-inflammatory NF-κB signal transduction pathway and may lead to cancer progression. To test this hypothesis, we further examined the expression of ERα, ERß, and NF- Bp65 expression in PIN lesions of the DLP. Our findings revealed that licofelone treatment at 300ppm significantly downregulated ERα and NF-κBp65 expression, whereas ERß expression was upregulated compared to untreated control (p&lt;0.001). In summary, our findings suggest that licofelone modulated several pro-inflammatory targets, and effectively suppressed the hormone-induced PIN development in Noble rats, without significantly affecting COX-2. Most interestingly, our findings are the first to report evidence that licofelone may selectively bind to ERα, and inhibit ERα-mediated activation of NF-κB signaling in prostate carcinogenesis. Further studies are in progress to confirm this unique molecular mechanism of licofelone binding to ER in PCa chemoprevention (Supported by NIH/NCI R03 CA133929 grant to N. Narayanan).

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 LB-422.

Liposome encapsulation of curcumin and resveratrol in combination reduces prostate cancer incidence in PTEN knockout mice

Increasing interest in the use of phytochemicals to reduce prostate cancer led us to investigate 2 potential agents, curcumin and resveratrol as preventive agents. However, there is concern about the bioavailability of these agents pertinent to the poor absorption and thereby limiting its clinical use. With the view to improve their bioavailability, we used the liposome encapsulated curcumin, and resveratrol individually and in combination in male B6C3F1/J mice. Further, we examined the chemopreventive effect of liposome encapsulated curcumin and resveratrol in combination in prostate-specific PTEN knockout mice. In vitro assays using PTEN-CaP8 cancer cells were performed to investigate the combined effects curcumin with resveratrol on (i) cell growth, apoptosis and cell cycle (ii) impact on activated p-Akt, cyclin D1, m-TOR and androgen receptor (AR) proteins involved in tumor progression. HPLC analysis of serum and prostate tissues showed a significant increase in curcumin level when liposome encapsulated curcumin coadministered with liposomal resveratrol (p < 0.001). Combination of liposomal forms of curcumin and resveratrol significantly decreased prostatic adenocarcinoma in vivo (p < 0.001). In vitro studies revealed that curcumin plus resveratrol effectively inhibit cell growth and induced apoptosis. Molecular targets activated due to the loss of phosphatase and tensin homolog (PTEN) including p-Akt, cyclin D1, mammalian target of rapamycin and AR were downregulated by these agents in combination. Findings from this study for the first time provide evidence on phytochemicals in combination to enhance chemopreventive efficacy in prostate cancer. These findings clearly suggest that phytochemicals in combination may reduce prostate cancer incidence due to the loss of the tumor suppressor gene PTEN.

Inflammatory processes of prostate tissue microenvironment drive rat prostate carcinogenesis: preventive effects of celecoxib

BACKGROUND

Prostate tissue microenvironment is susceptible to several risk factors including carcinogens, dietary factors, hormones, cytokines and growth factors that could induce chronic inflammation. Because of the difference in the serum levels and the intrinsic ability of monocytes/macrophages to cause harm, the transcriptional responses triggered by inflammatory stimuli must be controlled. Unfortunately, an in-depth association between prostate cancer and potential mediators of inflammation has not been completely investigated.

METHODS

To determine whether activated macrophage (infiltrating monocytes), iNOS and NF-kappaB are primary mediators of inflammation, besides COX-2, in prostate carcinogenesis, we examined tissue sections of rat prostate tumor induced by N-methyl-N-nitrosourea (MNU) plus testosterone in a follow-up study. We performed H&E and immunohsitochemical staining of the prostate tissue to detect specific markers of inflammation.

RESULTS

We report an increase in infiltrating monocyte, iNOS, NF-kappaBp65, VEGF and TNF-alpha at the early and advanced stages of tumor growth in MNU plus testosterone treated rats. Monocyte infiltration was often found in the stromal and perivascular regions of the DL prostate. We conclude for the first time that prostate cancer induced by MNU plus testosterone partly involves mediators of inflammation which could trigger the process of carcinogenesis and cause loss of apoptosis. Selective COX-2 inhibitor celecoxib at a dose of 500 mg/kg/bw administered for 52 weeks reduced infiltrating monocytes, inhibited iNOS, NF-kappaB p65 expression, induced apoptosis and tumor growth inhibition.

CONCLUSION

Carcinogen plus testosterone induced prostate carcinogenesis showing activation of macrophage, iNOS and NF-kappaBp65 could be prevented by celecoxib or related anti-inflammatory agents.

Exisulind in combination with celecoxib modulates epidermal growth factor receptor, cyclooxygenase-2, and cyclin D1 against prostate carcinogenesis: in vivo evidence

PURPOSE

Nonsteroidal anti-inflammatory drugs mediate anticancer effects by modulating cyclooxygenase-2 (COX-2)-dependent and/or COX-2-independent mechanism(s); however, the toxicity issue is a concern with single agents at higher doses. In this study, we determined the combined effect of celecoxib, a COX-2 inhibitor, along with exisulind (sulindac sulfone/Aptosyn) at low doses in prostate cancer.

EXPERIMENTAL DESIGN

We used a sequential regimen of N-methyl-N-nitrosourea + testosterone to induce prostate cancer in Wistar-Unilever rats. Following carcinogen treatment, celecoxib and exisulind individually and their combination at low doses were given in NIH-07 diet for 52 weeks. We determined the incidence of prostatic intraepithelial neoplasia, adenocarcinomas, rate of tumor cell proliferation, and apoptosis. Immunohistochemical and Western blot analysis were done to determine COX-2, epidermal growth factor receptor (EGFR), Akt, androgen receptor, and cyclin D1 expression. Serum prostaglandin E2 and tumor necrosis factor-alpha levels were determined using enzyme immunoassay/ELISA assays.

RESULTS

The rats that received celecoxib in combination with exisulind at low doses showed a significant decrease in prostatic intraepithelial neoplasia and adenocarcinomas as well as an enhanced rate of apoptosis. An overall decrease in COX-2, EGFR, Akt, androgen receptor, and cyclin D1 expression was found associated with tumor growth inhibition. Reduced serum levels of COX-2 protein, prostaglandin E2, and tumor necrosis factor-alpha indicated anti-inflammatory effects. A strong inhibition of total and phosphorylated form of EGFR (Tyr(992) and Tyr(845)) and Akt (Ser(473)) was significant in rats given with these agents in combination.

CONCLUSIONS

In this study, we show for the first time that the combination of celecoxib with exisulind at low doses could prevent prostate carcinogenesis by altering key molecular events.

Anticancer effects of licofelone (ML-3000) in prostate cancer cells

BACKGROUND

Licofelone, a potent antiinflammatory agent has been reported to interfere with the cyclooxygenase-2 (COX-2) and 5-lipoxygenase (5-LOX) signaling pathways with few side-effects. However, the underlying mechanism of licofelone against human cancer is not understood.

MATERIALS AND METHODS

Human and mouse prostate cancer cells were exposed to licofelone in a time- and dose-dependent manner. Cell growth/cell viability, apoptosis, and expression of COX-2 and 5-LOX at the gene and protein levels were investigated.

RESULTS

For the first time, it was demonstrated that licofelone inhibited prostate cancer cell growth and significantly down-regulated COX-2 and 5-LOX expression. A weak inhibitory effect on COX-1 protein was also observed.

CONCLUSION

Licofelone inhibited COX-2 and 5-LOX simultaneously and prevented overall cancer cell growth by enhancing apoptosis in both androgen-dependent and androgen-independent prostate cancer cells. Validating the dual role of licofelone in animal models of prostate cancer is critical for promoting its use as a potential chemopreventive or therapeutic agent.

Docosahexaenoic acid in combination with celecoxib modulates HSP70 and p53 proteins in prostate cancer cells

The role of cyclooxygenase-2 (COX-2) and the mechanism by which it influences the development and behavior of prostate cancer is unclear. Selective COX-2 inhibitors may be effective against prostate cancer via COX-2-independent mechanisms. But administration of high doses of COX-2 inhibitors over longer period of time may not be devoid of side effects. There is increasing interest in using COX-2 inhibitors in combination with other chemopreventive agents to overcome the issue of toxicity. However, the molecular mechanisms underlying their combined actions are not well understood. Therefore, the present study was designed to determine the effects of low doses of docosahexaenoic acid (DHA) in combination with celecoxib on the molecular targets at the proteins level in rat prostate cancer cells. Two-dimensional gel electrophoresis, in combination with mass spectrometry analysis, was used for protein identification. Western blot analysis confirmed the proteins identified. Paraffin-embedded tissue sections from the rat prostate tumor were used to detect base level expression of heat shock protein 70 (HSP70) and p53. The rate of cancer cell growth was inhibited more effectively (p < 0.01) by DHA in combination with celecoxib at lower doses (2.5 microM each). A total number of twelve proteins were differentially expressed by the combined action of DHA and celecoxib at low doses. It was interesting to note that these agents activated both HSP70 and p53 proteins. Activation of HSP70 by the combined actions of DHA and celecoxib in the presence of wild-type p53 reveals a unique COX-2 independent mode of action against prostate cancer.

RNA interference–mediated cyclooxygenase-2 inhibition prevents prostate cancer cell growth and induces differentiation: modulation of neuronal protein synaptophysin, cyclin D1, and androgen receptor

Cyclooxygenase-2 (COX-2) plays an important role in tumor development and progression. Inconsistent reports on the expression of COX-2 in early versus advanced prostate cancer raised the question on whether COX-2 inhibition affects prostate carcinogenesis. Evidence from recent studies indicates that prostate carcinogenesis depends on the altered expression of several factors including androgen receptor signaling, proinflammatory, and cell cycle regulatory genes. Very often, the outcome of androgen ablation treatment is not effective and, eventually, the cancer becomes androgen independent followed by activation of several survival genes and transcription factors. Most importantly, the extent of the influence of COX-2 on the regulation of the androgen receptor, cyclin D1, and other factors involved in cancer growth is not known. Using RNA interference-mediated COX-2 inhibition in metastatic prostate cancer cells, this study has shown that the silencing of COX-2 at the mRNA level can induce cell growth arrest and down-regulate androgen receptor and cyclin D1. We have further shown for the first time that COX-2 knockdown prostate cancer cells depict morphologic changes associated with enhanced expression of differentiation markers, particularly the neuronal protein synaptophysin along with activation of p21((Waf1/Cip1)) and p27((Kip1)). In summary, our findings determined the role of COX-2 in prostate carcinogenesis and its control on COX-2-independent targets. Second, abrogation of COX-2 and activation of synaptophysin provide evidence for the control of COX-2 on the expression of a neuronal protein. Finally, our findings provide evidence of COX-2-independent targets promoting cell growth arrest and differentiation in cells lacking COX-2 expression at the mRNA level.

Adenocarcina of the mouse prostate growth inhibition by celecoxib: downregulation of transcription factors involved in COX-2 inhibition

BACKGROUND

Epidemiological studies have shown a decreased risk of prostate cancer among men who regularly take aspirin or other non-steroidal anti-inflammatory drugs (NSAIDs). In this study, we examined a dose-dependent effect of a cyclooxygenase-2 (COX-2) inhibitor, celecoxib against transgenic adenocarcinoma of the mouse prostate.

METHODS

Efficacy of four different doses in parts per million of celecoxib, such as 200 ppm, 400 ppm, 600 ppm, and 1,000 ppm representing very low, moderate, and high doses, respectively were tested against adenocarcinoma of the mouse prostate using a transgenic adenocarcinoma of the mouse prostate (TRAMP) model assay.

RESULTS

Dietary supplement of celecoxib at doses of 400 ppm, 600 ppm, and 1,000 ppm are most effective against mPIN (mouse prostatic intraepithelial neoplasia) and adenocarcinoma of the prostate. Tumor growth inhibition by celecoxib was associated with increased rate of apoptosis. At 1,000 ppm, a complete inhibition of the PIN lesions was extended to limit the growth of adenocarcinoma (from 85% to 15%) and metastasis of the mouse prostate. The chemopreventive effect was significant (P<0.01) at 400 ppm, 600 ppm, and 1,000 ppm doses compared to that at the lowest dose of 200 ppm and control. A dose-dependent effect on tumor growth inhibition was associated with reduced expression of NF-kappaBp65 and COX-2.

CONCLUSIONS

Dietary supplementation of celecoxib at different doses provides evidence for the suppression of prostate adenocarcinoma tumor growth in a dose-dependent manner. Suppression of adenocarcinoma by celecoxib further limits the growth of metastatic prostate cancer.

Regression of mouse prostatic intraepithelial neoplasia by nonsteroidal anti-inflammatory drugs in the transgenic adenocarcinoma mouse prostate model

PURPOSE

Epidemiologic studies have revealed a decreased risk of colon cancer among people who have regularly taken cyclooxygenase (COX)-2 inhibitors such as aspirin or other nonsteroidal anti-inflammatory drugs (NSAIDs). Whereas the selective COX-2 inhibitor celecoxib and exisulind, a metabolic product of sulindac, have gained increasing attention as efficacious chemopreventive agents against colon and prostate cancer, not much is known about the underlying molecular targets and mechanisms. Moreover, the side effects of NSAIDs are a major obstacle for large-scale application to the prevention of cancer in humans; for example, in the United States in 1998, there were 16,550 deaths from NSAID-induced gastrointestinal complications. The toxicity associated with these compounds is raising concerns, and more needs to be known about their mode of action and molecular targets.

EXPERIMENTAL DESIGN

We used the transgenic mouse prostate (TRAMP) model, which exhibits similarities with human prostate cancer, including epithelial origin, progression from the PIN stage to adenocarcinoma, and metastasis by a transgene that is hormonally regulated by androgens. In addition to histologically analyzing the PIN lesions of the dorsolateral prostate from TRAMP mice, we delineated the molecular targets and mechanisms of celecoxib and exisulind against mouse PIN lesions. We performed Western blot analysis of the total protein lysate from the tissues of mouse PIN lesions to measure the level of expression of androgen receptor, vascular endothelial growth factor, nuclear factor-kappaB p65, BclII, AKT (total and phosphorylated Ser473), p53, cyclin-dependent kinase inhibitor p21WAF1/CIP1, p27, BAX, and caspase-3 to demonstrate the COX-2-independent mechanism involved in the inhibition of PIN lesions of the dorsolateral prostate by both celecoxib and exisulind.

RESULTS

We found for the first time that (a) both celecoxib and exisulind as dietary supplements induce strong inhibitory effects against prostate cancer at doses of 800 and 500 ppm, respectively, after 16 weeks; (b) the histologic analysis of the dorsolateral prostate after 2 weeks of treatment indicated a reduction of PIN lesions from 75% to 19% with celecoxib and to 16% with exisulind; (c) more importantly, those few PINs and adenocarcinomas in the groups treated with celecoxib or exisulind showed more apoptotic cells, lower levels of proliferating cell nuclear antigen, and a lower number of mitotic cells. To understand the molecular mechanisms involved in the inhibition of PIN lesions, first, we examined the expression of molecular targets involved in angiogenesis and inflammatory processes. It was clearly evident from Western blot analysis of the total protein lysate derived from the dorsolateral prostate tissues with PIN lesions that expression of androgen receptor, vascular endothelial growth factor, nuclear factor-kappaB p65, and BclII is down-regulated more effectively by celecoxib. Down-regulation of AKT protein (total and phosphorylated at Ser473) signaling by celecoxib clearly indicates an inhibition of the survival gene and the pathological process that could otherwise lead to adenocarcinoma.

CONCLUSIONS

Overall, the findings from this study clearly show the effectiveness of celecoxib and exisulind in reducing the PIN lesions by modulating a cascade of molecular targets involved in COX-2-dependent and -independent mechanisms. Whereas these agents are already in clinical trial or in use as chemopreventive agents, findings from this study demonstrate the difference in their mode of action, thus helping us to understand the side effects.

A combination of docosahexaenoic acid and celecoxib prevents prostate cancer cell growth in vitro and is associated with modulation of nuclear factor-kappaB, and steroid hormone receptors

Epidemiological studies have provided evidence that high intake of saturated fat and/or animal fat increases the risk of prostate cancer, but on the other hand, diets rich in omega-3 polyunsaturated fatty acids (n-3 PUFAs), present in fish oils were found to reduce the risk. There are indications of an increased expression of immunoreactive PPARgamma in prostatic intraepithelial neoplasia (PIN) and prostate cancer, suggesting that PPARgamma ligands may exert their own potent anti-proliferative effect against prostate cancer. The experimental evidence for the role of cyclooxygenase-2 (COX-2) in prostate carcinogenesis is well established through several investigations. It clearly suggests the need for development of strategies to inhibit COX-2 mediated prostate carcinogenesis. However, administration of high doses of COX-2 inhibitors, such as celecoxib, over longer periods may not be devoid of side effects. We assessed the efficacy of DHA and celecoxib individually and in combination at low doses in three prostate cancer cell lines (LNCaP, DU145 and PC-3) measuring cell growth inhibition and apoptosis, and on the levels of expression of COX-2, nuclear factor-kappaB (NF-kappaBp65), and nuclear receptors, such as PPARgamma and retinoid X receptors (RXR), all of which presumably participate in prostate carcinogenesis. A 48-h incubation of prostate cancer cells with 5 microM each of DHA or celecoxib induced cell growth inhibition and apoptosis, and altered the expression of the above molecular parameters. Interestingly, the modulation of these cellular and molecular parameters was more pronounced in cells treated with low doses of DHA and celecoxib (2.5 microM each) in combination than in cells treated with the higher doses of individual agents. In conclusion, the present study demonstrates for the first time that a combination of lower doses of the n-3 PUFA, and DHA with the selective COX-2 inhibitor celecoxib effectively modulates the above cellular and molecular parameters that are relevant to prostate cancer. This raises the intriguing prospect that the use of low doses of a COX-2 inhibitor in combination with an n-3 PUFA could be a highly promising strategy for prostate cancer chemoprevention while minimizing undesired side effects.

Effects of a combination of docosahexaenoic acid and 1,4-phenylene bis(methylene) selenocyanate on cyclooxygenase 2, inducible nitric oxide synthase and beta-catenin pathways in colon cancer cells

Epidemiological and preclinical studies suggest that diets that are rich in n-3 polyunsaturated fatty acids (PUFAs) and selenium (Se) reduce the risk of colon cancer. Studies conducted in our laboratory have indicated that synthetic organoselenium 1,4-phenylene bis(methylene) selenocyanate (p-XSC) is less toxic and more effective than inorganic Se and selenomethionine, the major Se compound in natural selenium yeast. Through cDNA microarray analysis, we have demonstrated earlier that the n-3 PUFA docosahexaenoic acid (DHA), modulated more than one signaling pathway by altering several genes involved in colon cancer growth. There is increasing interest in the use of combinations of low doses of chemopreventive agents that differ in their specific modes of action as this approach can minimize toxicity and increase efficacy in model assays. In the present study we assessed the efficacy of DHA and p-XSC individually and in combination at low doses in CaCo-2 colon cancer cells, using cell growth inhibition and apoptosis as measures of chemopreventive efficacy. On the basis of western blot and RT-PCR analysis, we also determined the effects of DHA and p-XSC on the levels of expression of cyclooxygenase-2, inducible nitric oxide synthase, cyclin D1, beta-catenin and nuclear factor kappaB, all of which presumably participate in colon carcinogenesis. A 48 h incubation of CaCo-2 cells with 5 microM each DHA or p-XSC induced cell growth inhibition and apoptosis and altered the expression of the above molecular parameters. Interestingly, the modulation of these cellular and molecular parameters was more pronounced in cells treated with low doses of DHA and p-XSC (2.5 microM each) in combination than in cells treated with these agents individually at higher concentrations (5.0 microM each). These findings are viewed as highly significant since they will provide the basis for the development of combinations of low dose regimens of DHA and p-XSC in preclinical models against colon carcinogenesis and, ultimately, in human clinical trials.

Resveratrol-induced cell growth inhibition and apoptosis is associated with modulation of phosphoglycerate mutase B in human prostate cancer cells: two-dimensional sodium dodecyl sulfate-polyacrylamide gel electrophoresis and mass spectrometry evaluation

Several studies provide evidence for the anti-carcinogenic activity of resveratrol, a phytoalexin present in grapes and berries, but the precise mechanisms involved in the modulation of prostate carcinogenesis by resveratrol remain to be elucidated. The inhibitory effects induced by resveratrol in human prostate cancer cells impact diverse cellular mechanisms associated with tumor initiation, promotion, and progression. In our earlier studies with prostate cancer cells using cDNA microarray analysis, we indicated the importance of p53-mediated molecular targets of resveratrol. The present study based on two-dimensional sodium dodecyl sulfate-polyacrylamide gel electrophoresis (2D-SDS-PAGE) followed by mass spectrometry analysis of human prostate cells that have been treated with resveratrol clearly identifies the role of phosphoglycerate mutase B. For the first time, we report on phosphoglycerate mutase B in the resveratrol-treated prostate cancer cells LNCaP, DU145, and PC-3 at the transcription level. Our observations raise the possibility of its effect on metabolic enzymes in cancer cells without affecting the normal cells.

Elucidation of molecular targets of mammary cancer chemoprevention in the rat by organoselenium compounds using cDNA microarray

We employed cDNA microarray analysis to identify, in mammary adenocarcinomas induced by 7,12-dimethylbenz[a] anthracene (DMBA) in the rat, target genes as potential biomarkers for cancer chemoprevention by 1,4-phenylenebis(methylene)selenocyanate (p-XSC). Confirmation of selected genes was conducted by reverse transcription polymerase chain reactions (RT-PCR). The glutathione conjugate, p-XSeSG, a putative metabolite of p-XSC was also employed to test our hypothesis that p-XSeSG is a more effective cancer chemopreventive agent in the mammary cancer model than p-XSC. Mammary adenocarcinomas were induced by a single oral administration of 5 mg DMBA in 0.2 ml olive oil per rat at 50-55 days of age. Consistent with our previous reports, dietary p-XSC at a non-toxic dose (10 p.p.m. as selenium) significantly inhibited adenocarcinoma development, independent of feeding duration. Moreover, p-XSeSG appears to be just as effective as p-XSC when fed after DMBA administration, but was significantly less effective than p-XSC in inhibiting the induction of mammary adenocarcinomas when it was fed before DMBA and continued until termination. To delineate the molecular basis for cancer chemoprevention by organoselenium compounds, we focused our analysis on differential expression of genes known to be involved in DMBA metabolism, as well as those related to cell cycle, cell proliferation and apoptosis. p-XSC and p-XSeSG were significantly and equally effective in inhibiting levels of expression of genes associated with cytochrome P450 isoforms, but the former was more active than the latter in up-regulating the expression of those related to certain phase II enzymes. p-XSC and p-XSeSG were significantly more effective in the up-regulation of pro-apoptotic genes, such as p21CIP1/WAF1, p27KIP1, APO-1 and Caspase-3, while down-regulating cell growth regulatory genes, such as c-myc, cyclin D1, cyclin D2 and proliferating cell nuclear antigen (PCNA). To our knowledge, this is the first report that provides insights into the effects of p-XSC and p-XSeSG at the molecular level that may account for mammary cancer chemoprevention in vivo in the rat.

Suppression of N-methyl-N-nitrosourea/testosterone-induced rat prostate cancer growth by celecoxib: effects on cyclooxygenase-2, cell cycle regulation, and apoptosis mechanism(s)

PURPOSE

This study was aimed at examining the mechanisms underlying the chemopreventive effect of celecoxib against prostate cancer. We focused our attention on events at the cellular level to show the ability of celecoxib to inhibit prostate cancer growth, by inducing cell cycle arrest and apoptosis. Moreover, we attempted to demonstrate the expression of genes involved in the downstream events related to cyclooxygenase-2 (COX-2) regulation and apoptosis.

EXPERIMENTAL DESIGN

To determine the level of COX-2 expression, we used paraffin-embedded tumor tissue sections and cancer cells (I-26) derived from N-methyl-N-nitroso-urea/testosterone-induced rat dorsolateral prostate, and we used immunofluorescence detection and Western blot analyses with anti-COX-2 monoclonal antibodies. We conducted clonogenic cell survival assays to demonstrate cell growth inhibition at very low doses of celecoxib. Flow cytometric analysis demonstrated the effects on the cell cycle. Reverse transcription-PCR and Western blot analyses were performed to show the effect of celecoxib on the downstream events of COX-2 and apoptosis-related targets.

RESULTS

The summary of our findings indicates that (a). these cells from chemically induced rat prostate tumors express COX-2 at both the mRNA and the protein level; (b). celecoxib significantly reduces COX-2 expression in these cancer cells; and (c). celecoxib induces cell cycle arrest at the G(1)-S phase transition point and modifies cell cycle regulatory proteins such as cyclin D1, retinoblastoma (Rb), and phosphorylated Rb, cyclin E, p27(KIP1), and p21(WAF1/CIP1). Furthermore, celecoxib inhibits DNA synthesis and induces apoptosis. Most importantly, celecoxib-induced apoptosis was associated with down-regulation of COX-2, nuclear factor kappaBp65, and with activation of peroxisome proliferator-activated receptor gamma, apoptosis activating factor-1, and caspase-3.

CONCLUSION

Results from the present study clearly indicate that celecoxib exerts its anticancer effect partly through COX-2-independent mechanisms in addition to the known primary function of COX-2 inhibition.

Differential expression of genes induced by resveratrol in LNCaP cells: P53-mediated molecular targets

Prostate cancer prevention by key elements present in human nutrients derived from plants and fruits has been confirmed in various cell cultures and tumor models. Resveratrol (RE), a phytoalexin, induces remarkable inhibitory effects in prostate carcinogenesis via diverse cellular mechanisms associated with tumor initiation, promotion and progression. Earlier studies have shown that RE alters the expression of genes involved in cell cycle regulation and apoptosis, including cyclins, cdks, p53 and cdk inhibitors. However, most of the p53-controlled effects related to the role of RE in transcription either by activation or repression of a sizable number of primary and secondary target genes have not been investigated. Our study examined whether RE activates a cascade of p53-directed genes that are involved in apoptosis mechanism(s) or whether it modifies the androgen receptor and its co-activators directly or indirectly and induces cell growth inhibition. We demonstrate by DNA microarray, RT-PCR, Western blot and immunofluorescence analyses that treatment of androgen-sensitive prostate cancer cells (LNCaP) with 10(-5) M RE for 48 hr downregulates prostate-specific antigen (PSA), AR co-activator ARA 24 and NF-kB p65. Altered expression of these genes is associated with an activation of p53-responsive genes such as p53, PIG 7, p21(Waf1-Cip1), p300/CBP and Apaf-1. The effect of RE on p300/CBP plays a central role in its cancer preventive mechanisms in LNCaP cells. Our results implicate activation of more than one set of functionally related molecular targets. At this point we have identified some of the key molecular targets associated with AR and p53 target genes. These findings point to the need for further extensive studies on AR co-activators, such as p300, its central role in post-translational modifications such as acetylation of p53 and/or AR by RE in a time- and dose-dependent manner at different stages of prostate cancer that will fully elucidate the role of RE as a chemopreventive agent for prostate cancer in humans.

Modulation of inducible nitric oxide synthase and related proinflammatory genes by the omega-3 fatty acid docosahexaenoic acid in human colon cancer cells

Epidemiological and preclinical studies demonstrate that consumption of diets high in omega-3 polyunsaturated fatty acids reduces the risk of colon cancer. Inhibition of colon carcinogenesis by omega-3 polyunsaturated fatty acids is mediated through modulation of more than one signaling pathway that alters the expression of genes involved in colon cancer growth. In our earlier studies on global gene expression with cDNA microarrays, we have shown that treatment of CaCo-2 colon cancer cells with docosahexaenoic acid (DHA) down-regulated the prostaglandin family of genes, as well as cyclooxygenase 2 expression and several cell cycle-related genes, whereas it up-regulated caspases 5, 8, 9, and 10 that are associated with apoptosis. It is known that nitric oxide activates the cyclooxygenase 2 enzyme, which plays a pivotal role in the progression of colon cancer via prostaglandin synthesis and angiogenesis. The present study was undertaken to examine the multifaceted role of DHA in the expression of inducible nitric oxide synthase (iNOS) and of related proinflammatory genes, as those have been shown to play a role in tumor progression. In addition, we aimed to identify associated target genes by DNA microarray, reverse transcription-PCR analysis, and cellular localization of iNOS expression in CaCo-2 cells. Results of this study demonstrate that treatment with DHA down-regulates iNOS in parallel with a differential expression and down-regulation of IFNs, cyclic GMP, and nuclear factor kappa B isoforms. More importantly, our findings clearly demonstrate the up-regulation of cyclin-dependent kinase inhibitors p21((Waf1/Cip1)) and p27, differentiation-associated genes such as alkaline phosphatases, and neuronal differentiation factors. These finding strongly suggest that the antitumor activity of DHA may be attributed, at least in part, to an effect on iNOS regulatory genes. In addition, our results indicate the presence of specific gene expression profiles in human colon cancer that can be used as molecular targets for chemopreventive agents.

Interactive gene expression pattern in prostate cancer cells exposed to phenolic antioxidants

Dietary phenolic compounds are known to elicite vital cellular responses such as cell cycle arrest, apoptosis and differentiation by activating a cascade of molecular events. As there is an increasing interest to improve the efficacy of these compounds for use as potential chemopreventive agents, we wanted to understand the impact of phenolic compounds on target genes in prostate cancer. In this study we used human cDNA microarrays with 2400 clones consisting of 17 prosite motifs to characterize alterations in gene expression pattern in response to the phenolic antioxidants ellagic acid (EA) and resveratrol (RE). Over a 48-hr exposure of androgen - sensitive LNCaP cells to EA and RE, a total of 593 and 555 genes respectively, showed more than a two fold difference in expression. A distinct set of genes in both EA-and RE-treated cells may represent the signature profile of phenolic antioxidant-induced gene expression in LNCaP cells. Although extensive similarity was found between effects of EA - and RE - responsive genes in prostate cancer cells, out of 246 genes with overlapping responses, 25 genes showed an opposite effect. Quantitative RT-PCR was used to verify and validate the differential expression of selected genes identified from cDNA microarrays. In-depth analysis of the data from this study provided insight into the alterations in the p53 - responsive genes, p300, Apaf-1, NF-kBp50 and p65 and PPAR families of genes, suggesting the activation of multiple signaling pathways that leads to growth inhibition of LNCaP cells. This is a first study to look for changes in a large number of human genes in response to dietary compounds.

Docosahexaenoic acid regulated genes and transcription factors inducing apoptosis in human colon cancer cells

Epidemiological and preclinical studies demonstrate that consumption of diets high in omega-3 fatty acids (n-3 PUFAs) reduce the risk of colon cancer. Docosahexaenoic acid (DHA), a long chain polyunsaturated fatty acid (PUFAs) is a major constituent of nutrients rich in n-3 PUFAs. There are studies to indicate that colon tumor inhibition by n-3 PUFA-rich diets is, in part, mediated through modulation of signaling pathways that alter gene expression which are involved in colon tumor growth. In the present study using CaCo-2 colon cancer cell lines we examined the effects of DHA on the genetic precursors of human colon cancer at the transcription level using DNA oligonucleotide arrays. Our results indicated that DHA inhibits the growth of CaCo-2 cells and induces apoptosis. For gene expression analysis using DNA microarrays, total RNA extracted from DHA treated CaCo-2 cells was converted to cDNA, labeled with Cy5-dCTP (DHA-treated) and Cy3-dCTP (untreated cells) and used as probes for hybridization in human chip spotted with 3,800 oligonucleotides consisting of 156 functional categories. The expression profiles of genes indicated a reprogramming pattern of previously known and unknown genes and transcription factors that provided clues to the possible functional mechanism of DHA. An average of (ratios from triplicate experiments) 504 out of 3,800 genes expressed after 48 h of DHA treatment. Altered expression on the transcription factors includes down regulation of nine members of the RNA II polymerases, transcription co-repressor associated protein and enhancer binding proteins such as AP2, in addition to changes in the expression of zinc finger group of transcription factors. Activation of cytochrome c which triggers caspases was associated with the elevated expression of pro-apoptotic caspases 10, 13, 8, 5 and 9 in DHA treated cells. Activation of cyclin-dependent kinase inhibitors such as p21 (waf1/cip1), p27, p57, p19 and growth arrest specific proteins by more than 2-fold is consistent with the induction of apoptosis and inactivation of antiapototic Bcl-2 family of genes. Inactivation of prostaglandin family of genes, lipoxygenases and altered expression of peroxisome proliferators (PPARalpha and gamma) by DHA seem to indicate a lipid peroxidation-induced apoptosis in addition to effect reflected on the modification of cell cycle regulatory genes. These findings support the conclusion that a genomewide expression profiling of human colon cancer precursor genes and transcription factors provides a set of novel regulatory mechanism(s) to determine the chemopreventive efficacy of DHA and thus to prevent the inflammation and neoplasia.