The dynamic face of cadmium-induced Carcinogenesis: Mechanisms, emerging trends, and future directions

Cadmium (Cd) is a malleable element with odorless, tasteless characteristics that occurs naturally in the earth's crust, underground water, and soil. The most common reasons for the anthropological release of Cd to the environment include industrial metal mining, smelting, battery manufacturing, fertilizer production, and cigarette smoking. Cadmium-containing products may enter the environment as soluble salts, vapor, or particle forms that accumulate in food, soil, water, and air. Several epidemiological studies have highlighted the association between Cd exposure and adverse health outcomes, especially renal toxicity, and the impact of Cd exposure on the development and progression of carcinogenesis. Also highlighted is the evidence for early-life and even maternal exposure to Cd leading to devastating health outcomes, especially the risk of cancer development in adulthood. Several mechanisms have been proposed to explain how Cd mediates carcinogenic transformation, including epigenetic alteration, DNA methylation, histone posttranslational modification, dysregulated non-coding RNA, DNA damage in the form of DNA mutation, strand breaks, and chromosomal abnormalities with double-strand break representing the most common DNA form of damage. Cd induces an indirect genotoxic effect by reducing p53's DNA binding activity, eventually impairing DNA repair, inducing downregulation in the expression of DNA repair genes, which might result in carcinogenic transformation, enhancing lipid peroxidation or evasion of antioxidant interference such as catalase, superoxide dismutase, and glutathione. Moreover, Cd mediates apoptosis evasion, autophagy activation, and survival mechanisms. In this review, we decipher the role of Cd mediating carcinogenic transformation in different models and highlight the interaction between various mechanisms. We also discuss diagnostic markers, therapeutic interventions, and future perspectives.

Identification and characterization of a novel nematode pan allergen (NPA) from Wuchereria bancrofti and their potential role in human filarial tropical pulmonary eosinophilia (TPE)

BACKGROUND

Tropical pulmonary eosinophilia (TPE) is a chronic respiratory syndrome associated with Lymphatic Filariasis (LF), a tropical parasitic infection of the human, transmitted by mosquitoes. The larval form of LF (microfilariae) are trapped in the lungs of TPE subjects have a major role in initiating the TPE syndrome. To date, there are no reports on the potential allergen that is responsible for generating parasite-specific IgE in TPE.

METHODOLOGY/PRINCIPAL FINDINGS

In this project, we screened a cDNA expression library of the microfilarial stages of Wuchereria bancrofti with monoclonal IgE antibodies prepared from subjects with clinical filarial infections. Our studies identified a novel molecule that showed significant sequence similarity to an allergen. A blast analysis showed the presence of similar proteins in a number of nematodes parasites. Thus, we named this molecule as Nematode Pan Allergen (NPA). Subsequent functional analysis showed that NPA is a potent allergen that can cause release of histamine from mast cells, induce secretion of proinflammatory cytokines from alveolar macrophages and promote accumulation of eosinophils in the tissue, all of which occur in TPE lungs.

CONCLUSIONS/SIGNIFICANCE

Based on our results, we conclude that the NPA protein secreted by the microfilariae of W. bancrofti may play a significant role in the pathology of TPE syndrome in LF infected individuals. Further studies on this molecule can help design an approach to neutralize the NPA in an attempt to reduce the pathology associated with TPE in LF infected subjects.

MALAT-1 Is a Key Regulator of Epithelial-Mesenchymal Transition in Cancer: A Potential Therapeutic Target for Metastasis

Metastasis-associated lung adenocarcinoma transcript-1 (MALAT-1) is a long intergenic non-coding RNA (lncRNA) located on chr11q13. It is overexpressed in several cancers and controls gene expression through chromatin modification, transcriptional regulation, and post-transcriptional regulation. Importantly, MALAT-1 stimulates cell proliferation, migration, and metastasis and serves a vital role in driving the epithelial-to-mesenchymal transition (EMT), subsequently acquiring cancer stem cell-like properties and developing drug resistance. MALAT-1 modulates EMT by interacting with various intracellular signaling pathways, notably the phosphoinositide 3-kinase (PI3K)/Akt and Wnt/β-catenin pathways. It also behaves like a sponge for microRNAs, preventing their interaction with target genes and promoting EMT. In addition, we have used bioinformatics online tools to highlight the disparities in the expression of MALAT-1 between normal and cancer samples using data from The Cancer Genome Atlas (TCGA). Furthermore, the intricate interplay of MALAT-1 with several essential targets of cancer progression and metastasis renders it a good candidate for therapeutic interventions. Several innovative approaches have been exploited to target MALAT-1, such as short hairpin RNAs (shRNAs), antisense oligonucleotides (ASOs), and natural products. This review emphasizes the interplay between MALAT-1 and EMT in modulating cancer metastasis, stemness, and chemoresistance in different cancers.

Photoactivation of pheophorbide-a utilizing 670 nm LEDs elicits cancer suppressive effects in androgen-independent prostate cancer cellular models

OBJECTIVES

Prostate cancer (PCa) is the most commonly diagnosed cancer and the second leading cause of cancer death in men in the USA. Photodynamic therapy (PDT) is a state-of-the-art treatment that combines high selectivity with minor side effects. Pheophorbide-a (Pheo) is a natural pigment with a photosensitizer property. Our study delved into the impact of Pheo alone or Pheo-PDT combination on the androgen-independent metastatic prostate cancer (AIPC) cell lines DU-145 and C4-2. Furthermore, an in-depth examination has been conducted on the photocytotoxicity mechanism of Pheo-PDT in these specific cell lines.

METHODS

In vitro studies were conducted using the AIPC cell lines. DU-145 and C4-2 cells were treated with Pheo at different concentrations for 60 min alone, or Pheo treatment followed by exposure to 670 nm illumination (60 mW/cm2 in 88 s pulses), producing 5 J/cm2 via portable light-emitting diode.

KEY FINDINGS

Our results show that Pheo-PDT substantially inhibits cell viability, anchorage-independent growth, and migration capacities and induces autophagy and apoptosis via the over-production of reactive oxygen species that mediates endoplasmic reticulum stress in AIPC cell lines.

CONCLUSIONS

Our study highlights the potential benefits of Pheo-PDT in metastatic hormone-insensitive PCa cell lines. It paves the way for treating localized and locally advanced PCa as a possible candidate for castration-resistant prostate cancer.

Gene Expression and DNA Methylation as Prognostic Markers in Metastatic Castration-Resistant Prostate Cancer: Analysis of Circulating Tumor Cells and Paired Plasma-Derived Exosomes

Prostate cancer (PCa) is the most prevalent cancer among men and is the second leading cause of cancer-related death in the United States [...].

MicroRNAs in Prostate Cancer: Implications for Treatment Response and Therapeutic Targets

Cancer resistance to treatment is very common, represents one of the most significant challenges in the last few decades, and continues to impede all efforts to cure cancer [...].

Androgen Receptor Signaling in Prostate Cancer Genomic Subtypes

Prostate cancer (PCa) constitutes a significant cause of mortality, with over 37,000 new deaths each year [...].

Neferine Targets the Oncogenic Characteristics of Androgen-Dependent Prostate Cancer Cells via Inducing Reactive Oxygen Species

Castration resistance poses a significant challenge in the management of advanced prostate cancer (PCa), with androgen deprivation therapy (ADT) or chemotherapy being the primary treatment options. However, these approaches often lead to significant side effects and the development of therapeutic resistance. Therefore, it is crucial to explore novel treatment options that can efficiently target PCa, improve patient survival, and enhance their quality of life. Neferine (Nef), a bioactive compound derived from plants, has emerged as a promising candidate for cancer treatment due to its ability to induce apoptosis, autophagy, and cell cycle arrest. In this study, we investigated the potential anticancer effects of Nef in androgen receptor (AR)-positive LNCaP and VCaP cells, representative models of androgen-dependent PCa. Our findings demonstrate that Nef effectively inhibits cell growth, proliferation, and the tumorigenic potential of androgen-dependent PCa cells. Furthermore, Nef treatment resulted in the excessive production of reactive oxygen species (ROS), leading to the activation of key markers of autophagy and apoptosis. These results suggest that Nef has the potential to target the oncogenic characteristics of androgen-dependent PCa cells by exploiting the potency of ROS and inducing autophagy and apoptosis in AR-positive PCa cells. These findings shed light on the therapeutic potential of Nef as a novel treatment option with reduced side effects for androgen-dependent prostate cancer. Further investigations are warranted to assess its efficacy and safety in preclinical and clinical settings.

Eprinomectin: a derivative of ivermectin suppresses growth and metastatic phenotypes of prostate cancer cells by targeting the β-catenin signaling pathway

PURPOSE

Prostate cancer (PCa) is the second leading cause of cancer death among men in the USA. The emergence of resistance to androgen deprivation therapy gives rise to metastatic castration-resistant prostate cancer. Eprinomectin (EP) is a member of a family of drugs called avermectins with parasiticide and anticancer properties. The pupose of this study was to evaluate the anticancer effects of EP against metastatic PCa using cellular models.  METHODS: In this study, we have investigated the effect of EP's anticancer properties and delineated the underlying mechanisms in the DU145 cellular model using several assays such as cell viability assay, colony formation assay, wound-healing assay, immunofluorescence, apoptosis assay, cell cycle analysis, and immunoblotting.

RESULTS

Our results indicate that EP significantly inhibits the cell viability, colony formation, and migration capacities of DU145 cells. EP induces cell cycle arrest at the G0/G1 phase, apoptosis via the activation of different caspases, and autophagy through the increase in the generation of reactive oxygen species and endoplasmic reticulum stress. In addition, EP downregulates the expression of cancer stem cell markers and mediates the translocation of β-catenin from the nucleus to the cytoplasm, indicating its role in inhibiting downstream target genes such as c-Myc and cyclin D1.

CONCLUSION

Our study shows that EP has tremendous potential to target metastatic PCa cells and provides new avenues for therapeutic approaches for advanced PCa.

Abstract 4975: Anti-cancer effect of a probiotic bacteria-derived compound, 1,4-Dihydroxy-2-naphthoic acid in prostate cancer

Cancer incidence has been increasing globally and the major cause for mortality associated with this disease is due to metastasis development. Followed by skin and lung cancer, prostate cancer (PCa) is one of the most common cancers prevailing among older men in the United States. Although androgen deprivation therapy (ADT) is the mainstay treatment for PCa, most patients undergoing ADT eventually develop metastatic PCa. Moreover, other treatment options, such as chemotherapy and radiotherapy, have toxic side effects and are ineffective in controlling advanced PCa. Hence, there arises a need for identifying alternative agents with possibly fewer side effects. The gut biome plays a significant role in regulating many bodily functions like digestion, immunity, and including cancer prevention. Probiotics, commonly known as 'good bacteria,' are living microorganisms that provide health promoting benefits. A probiotic metabolite, 1,4-Dihydroxy-2-naphthoic acid (DHNA), is an anti-inflammatory aryl hydrocarbon receptor (Ahr) agonist which is yet to be explored for its anticancer activity. Inhibiting the inflammatory signaling axis and activating Ahr by DHNA could be a promising strategy to counteract metastatic PCa. Cell viability assays revealed that 1,4-DHNA is highly toxic in metastatic prostate cancer cell lines such as DU145 and PC3 compared to normal prostate epithelial cells like RWPE-1 and human prostate stromal myofibroblast cell line, WPMY-1, with an approximate IC50 value of 5 µM in DU145 and PC3 and about 20 µM and 75 µM in WPMY-1 and RWPE-1 respectively. DHNA reduced the colony forming abilities of BPH-Cd, PC3, and DU145 in clonogenic assay and suppressed the BPH-Cd spheroid growth in spheroid formation assay, revealing its anti-tumorigenic potential. Trans-well migration assay using BPH-Cd, PC3, and DU145 showed a decrease in cell migration, hinting at the drug's anti-metastatic ability. G2/M phase arrest in cell cycle analysis and dose-dependent increase in apoptosis of DHNA-treated DU145, PC3, and LNCaP cell lines reiterated its anti-cancer potential. Western blot results in PC3 and DU145 showed significant dose-dependent inhibition of protooncogene β-catenin expression. Downregulation of cell cycle proteins like cyclin D1 and increased expression of effector caspase, cleaved caspase 7 support cell death promoting effects of DHNA via an intrinsic apoptotic pathway. Our pre-clinical data suggest that DHNA can be a potential drug for inhibiting both prostate tumor growth and metastasis. Further research is warranted to ascertain the anti-metastatic and underlying anti-cancer mechanisms to help translate the findings to clinical use.

Citation Format: Shreeja Srinivas Bitla, Gnanasekar Munirathinam. Anti-cancer effect of a probiotic bacteria-derived compound, 1,4-Dihydroxy-2-naphthoic acid in prostate cancer. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 4975.

Complete Tolerogenic Adjuvant Stimulates Regulatory T Cell Response to Immunization

We have determined in mice the minimum composition required for forming a vaccine adjuvant that stimulates a regulatory T (Treg) cell response to immunization, and we named the adjuvant "complete tolerogenic adjuvant." This new kind of adjuvant may let us use the well-proven "Ag with adjuvant" form of immunization for inducing Treg cell-mediated Ag-specific immunosuppression. The minimum composition consists of dexamethasone, rapamycin, and monophosphoryl lipid A at a mass ratio of 8:20:3. By dissecting the respective role of each of these components during immunization, we have further shown why immunosuppressive and immunogenic agents are both needed for forming true adjuvants for Treg cells. This finding may guide the design of additional, and potentially more potent, complete tolerogenic adjuvants with which we may form numerous novel vaccines for treating immune diseases.

Abstract 690: An anti-leprosy drug, clofazimine, targets Wnt/β-catenin pathway in cadmium-transformed benign prostatic hyperplasia cells

Prostate cancer (PCa) is one of the most prevalent cancers among men in America, being second only to skin cancer. Every year 1.6 million men are diagnosed with PCa and 366,000 men die of PCa. PCa is associated to various risk factors that include old age, ethnicity, family history, lifestyle, diet, environmental and occupational exposures. Cadmium (Cd), a well-known metal carcinogen is one of the most copious occupational and environmental pollutant found in air, soil, dietary products, and tobacco. Cd is implicated in the carcinogenesis of PCa, but the mechanism remains elusive. To explore new targets for Cd induced PCa, chronic exposure of 10µM of Cd for over a year induced malignant transformation of benign prostatic hyperplasia (BPH1) cells which was used as a cellular model in this study. The Cd transformed BPH1 cells named as BPH-Cd were confirmed for tumorigenic characteristics by performing clonogenic assay, spheroid growth assay and wound healing experiments. BPH-Cd cells were further subjected to genomic analysis to identify signaling networks that are deregulated in the carcinogenesis of Cd. Our data suggested that one of the potential underlying mechanism of Cd carcinogenesis may be due to the upregulation of Wnt-3A and β-catenin pathway. In addition, Cd also activated stemness-related genes such as ALDHA1, NANOG and Oct1. Next, to determine whether targeting Wnt/β-catenin pathway in BPH-Cd could disrupt the oncogenic potential of these cells, Clofazimine, a FDA-approved anti-leprosy drug known to inhibit broad range of Wnt-dependent cancers were explored in this study. Cell viability assay indicated the inhibition of cell growth of BPH-Cd cells by Clofazimine in a dose-dependent manner with an IC50 value of 5µM. Furthermore, Clofazimine robustly inhibited the tumorigenesis of BPH-Cd as observed in colony formation assay. Of note, In-vitro 3D spheroid assay suggested that Clofazimine decreased the size of spheroids with increasing doses. Clofazimine also showed cell cycle arrest by flow cytometry in G2/M phase in BPH-Cd cells. Confocal imaging of Wnt-3A suggested a decrease in the intensity of expression with increasing doses of clofazimine in BPH-Cd treated cells. Western blot analysis of Clofazimine treated BPH-Cd cells showed downregulation of CDK2, increase in cleaved PARP-1 and upregulation of p21. Importantly, Clofazimine also displayed potent anti-cancer effects on hormone driven (androgen-dependent) LNCaP human prostate cancer cells by inhibiting the cell viability, clonogenic ability and inducing G2/M cell cycle arrest in this cell line. Taken together, our study suggests that Clofazimine could be a potential chemopreventive and anti-prostate cancer agent which warrants further evaluation for its clinical application.

Citation Format: Rifika Jain, Gnanasekar Munirathinam. An anti-leprosy drug, clofazimine, targets Wnt/β-catenin pathway in cadmium-transformed benign prostatic hyperplasia cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 690.

Oncopreventive and oncotherapeutic potential of licorice triterpenoid compound glycyrrhizin and its derivatives: Molecular insights

Licorice (Glycyrrhiza glabra) is a well-known natural herb used to treat different ailments since ancient times. Glycyrrhizin (GL), which is the primary triterpenoid compound of licorice extract, has been known to have broad-spectrum pharmacological effects. GL is cleaved into glucuronide and the aglycone, glycyrrhetinic acid (GA), which exists in two stereoisomeric forms: 18α- and 18β-GA. It is well documented that GL and GA have great potential as anti-inflammatory, anticancer, antiviral, anti-diabetic, antioxidant, and hepatoprotective agents. Studies undertaken during the coronavirus disease 2019 pandemic suggest that GL is effective at inhibiting the viral replication of severe acute respiratory syndrome coronavirus 2. The anticancer effects of GL and GA involve modulating various signaling pathways, such as the phosphatase and tensin homolog/phosphatidylinositol 3-kinase/protein kinase B pathway, the mitogen-activated protein kinase, and the mammalian target of rapamycin/signal transducer and activator of transcription 3, which are mainly involved in regulating cancer cell death, oxidative stress, and inflammation. The potential of GL and GA in preventing cancer development and suppressing the growth and invasion of different cancer types has been reviewed in this paper. This review also provides molecular insights on the mechanism of action for the oncopreventive and oncotherapeutic effects of GL and its derivative, GA, which could help develop more specific forms of these agents for clinical use.

Berry derived constituents in suppressing viral infection: Potential avenues for viral pandemic management

Berries are acknowledged as a rich source of major dietary antioxidants and the fact that berry phenolics exhibit antioxidant property is widely accepted. Berries are abundant in Vitamin C and polyphenols such as anthocyanins, flavonoids, and phenolic acids. Polyphenols are found to have several therapeutic effects such as anti-inflammatory, antioxidant, and antimicrobial properties. Increasing studies are focusing on natural products and their components for alternative therapeutics against viral infections. In particular, berries such as elderberry, blueberry, raspberry, and cranberry have proven to be effective against viral infections. Of note, the decoction of Honeysuckle (Lonicera japonica) has been shown to treat viral epidemic diseases. Owing to the rich source of various antiviral constituents, berries could be an alternative source for managing viral infections. In this review, we provide insights into how berry derived components inhibit viral infection and their clinical usefulness in viral disease management.

Can diallyl trisulfide, a dietary garlic-derived compound, activate ferroptosis to overcome therapy resistance in prostate cancer?

BACKGROUND

Therapy resistance is the underlying reason for poor outcome in prostate cancer (PCa) patients. Diallyl trisulfide (DATS) is an organosulfur compound present in garlic. DATS has been shown to target PCa cells by induction of apoptosis, increase in the production of reactive oxygen species, degradation of ferritin protein and increase in the labile iron (Fe) pool.

AIM

We hypothesize that DATS could induce ferroptosis, an Fe-dependent, unique non-apoptotic form of regulated cell death to eliminate therapy resistance encountered by PCa patients.

METHODS

In vitro and in vivo studies should be performed to test the hypothesis.

RESULTS

As per the hypothesis, DATS would eliminate apoptotic resistance via inducing ferroptosis.

CONCLUSION

Since apoptosis resistance has been reported to be the underlying mechanism of therapy resistance in PCa, DATS could be used to effectively target PCa cells by overcoming apoptosis resistance and inducing ferroptosis-mediated cell death of PCa cells.

Exploring NCX4040, an Aspirin Derivative, as a Potential Treatment for Benign Prostatic Hyperplasia

Benign Prostatic hyperplasia (BPH) is a leading cause of lower urinary tract symptoms which affects men above 50 years of age. Chronic inflammation and abnormal proliferation of stromal and epithelial cells are implicated in BPH disease onset. The symptoms of BPH include back pain and difficulty in emptying bladder. Finasteride, sildenafil and tamsulosin are some of the drugs used to ease difficulty urinating and relax the muscles of the gland. Transurethral resection of the prostate or laser surgery can be performed to treat severe symptoms. However, these therapies have deleterious effects such as low blood pressure, ejaculatory dysfunction, and lump formation. Hence, there is an unmet need for potential drugs against BPH. Nonsteroidal anti-inflammatory drugs (NSAIDs) have proven to be effective in cancers but their applicability in BPH condition is yet to be fully explored. Aspirin, one of the NDSAIDs, has anti-tumor and anti-inflammatory properties at higher doses. NCX4040, a nitric oxide releasing derivative of aspirin, could prove to be effective against BPH, since it can inhibit abnormal cell proliferation and serve as a vasodilator. We hypothesize that NCX4040 would be an effective drug to treat BPH. BPH-1 epithelial and WPMY-1 stromal cells were used as in vitro models of BPH. MTT assay was performed to check the inhibitory effect of NCX4040 and blocking agents like catalase and N-acetyl-L-cysteine (NAC) were explored on cells after treatment. Clonogenic assay was done to explore the colony formation ability of cells. Spheroid assay was performed to analyze the anti-proliferative effect of NCX4040. Annexin V/PI and cell cycle analysis was performed to check for apoptosis and cell cycle arrest in the cells. Western blot was done to assess the signaling molecules altered by NCX4040 in BPH-1 cells. Confocal immunofluorescence was employed to analyze the dynamics of actin filaments after treatment in cells. Our studies revealed that NCX4040 inhibited the cell viability of BPH-1 and WPMY-1 in a dose dependent manner with IC50 predicted at 5µM and 2.5µM respectively. Of note, catalase and NAC blocked the effect of NCX4040 on prostate cells. Colony formation assay result implied a gradual decrease in the number of colonies of cells treated with NCX4040 with 2.5µM and 5µM doses. Spheroid assay in BPH-1 cells showed inhibitory effects after treatment. Cell cycle analysis by flowcytometry inferred that cell cycle arrest at G2/M phase and annexin V analysis indicated that activation of apoptosis in cells following treatment. Phalloidin staining showed decrease in the actin filament intensity in cells. At the molecular level, NCX4040 downregulated the expression of key markers such as RhoA, p65, COX-2, PCNA, Cyclin D3, and PDE-5 in BPH-1 cells. Taken together, NCX4040 could be used as a potential agent to manage BPH with minimal side effects, which needs further evaluation in animal models.

Eprinomectin, a novel semi-synthetic macrocylic lactone is cytotoxic to PC3 metastatic prostate cancer cells via inducing apoptosis

Prostate Cancer (PCa) is the second most common cancer among men in United States after skin cancer. Conventional chemotherapeutic drugs available for PCa treatment are limited due to toxicity and resistance issues. Therefore, there is an urgent need to develop more effective treatment for advanced PCa. In this current study, we focused on evaluating the anti-cancer efficacy of Eprinomectin (EP), a novel avermectin analog against PC3 metastatic PCa cells. EP displayed robust inhibition of cell viability of PC3 cells in addition to suppressing the colony formation and wound healing capabilities. Our study showed that EP targets PC3 cells via inducing ROS and apoptosis activation. EP treatment enforces cell cycle arrest at G0/G1 phase via targeting cyclin-dependent kinase 4 (CDK4) and subsequent induction of apoptosis in PC3 cells. At the molecular level, EP effectively inhibited the expression of various cancer stem cell markers such as ALDH1, Sox-2, Nanog, Oct3/4 and CD44. Interestingly, EP also inhibited the activity of alkaline phosphatase, a maker of pluripotent stem cells. Of note, EP treatment resulted in the translocation of β-catenin from the nucleus to the cytoplasm indicating that EP antagonizes Wnt/β-catenin signaling pathway. Western blotting analysis revealed that EP downregulated the expression of key cell cycle markers such as cyclin D1, cyclin D3, CDK4, and c-Myc. In addition, EP inhibited the anti-apoptotic markers such as Mcl-1, XIAP, c-IAP1 and survivin in PC3 cells. On the other hand, EP treatment resulted in the activation of pH2A.X, Bad, caspase-9, caspase-3 and cleavage of PARP1. Taken together, our data suggests that EP is a potential agent to treat advanced PCa cells via modulating apoptosis signaling.

Abstract 4023: Elevating the reactive oxygen species threshold in prostate cancer stem cells using VK3-OCH3 as a strategy to target prostate cancer

Prostate cancer (PCa) is the second most leading cause of cancer related deaths in American men. Although several cancer treatments are available, these have a number of drawbacks and can leave the patient with cardiotoxicity, loss of libido and infertility. Androgen deprivation therapy (ADT) is a standard promising therapy for metastatic PCa patients. However, patients within 18-24 months suffer from relapse and progress into castration resistant prostate cancer (CRPC). Experimental evidences suggest that, cancer stem cells (CSC) which constitute as a subpopulation of cancer cells, play a pivotal role in carcinogenesis, metastasis and chemoresistance to therapies. Therefore, targeting CSC can decrease the PCa recurrence rates and can help to offer better treatment options. Elevating the reactive oxygen species (ROS) threshold has been shown to be an effective strategy to eliminate CSC. Hence, in the present study, we hypothesized that VK3-OCH3, a menadione derivative, as a potential ROS enhancer in prostate cancer stem cell line (PCSC). After conducting a cell viability assay with different vitamin K (VK) analogs, our data revealed that VK3-OCH3 was more effective against PCSC compared to other VK analogs. Subsequently, colony formation assay and Trans-well migration assays revealed that VK3-OCH3 exhibits anti-tumorigenic and anti-metastatic properties against PCSC. Further studies showed that antioxidants such as NAC and GSH antagonized the effects of VK3-OCH3 on PCSC survival inhibition, suggesting the activation of oxidative stress by VK3-OCH3 in PCSC. In addition, our data revealed that VK3-OCH3 imparts oxidative stress by increasing the ROS levels which were determined using a ROS probe (DCFDA) by fluorescence analysis. VK3-OCH3 treatment also induced marked elevations in mitochondrial ROS generation in PCSC by FACS analysis which correlated with significant apoptotic cell death in these cells. Furthermore, we tested the effect of VK3-OCH3 on cell cycle progression using FACS and observed a significant G0 cell cycle arrest. By using an oncogene array, it was found that survivin, an apoptotic inhibitor, was downregulated by VK3-OCH3, which was further confirmed by Western blot analysis. Our subsequent confocal studies showed that, VK3-OCH3 downregulates the expression levels of EMT markers such as vimentin and TCF-8. Real time data also revealed that there is a modulation in gene expression of beta-catenin upon VK3-OCH3 treatment in PCSC. Of note, VK3-OCH3 treated PCSCs had a significant reduction in stem cell markers such as CD44 and ALDH1. In conclusion, our results suggest that VK3-OCH3 could be used as a potential ROS targeted anti-CSC strategy in treating PCa.

Citation Format: Mona Vudutha, Somaiah Chinnapaka, Pranav Volety, Gnanasekar Munirathinam. Elevating the reactive oxygen species threshold in prostate cancer stem cells using VK3-OCH3 as a strategy to target prostate cancer [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 4023.

Repurposing antidepressant sertraline as a pharmacological drug to target prostate cancer stem cells: dual activation of apoptosis and autophagy signaling by deregulating redox balance

Cancer stem cells play a major role in tumor initiation, progression, and tumor relapse of prostate cancer (PCa). Recent studies suggest that Translationally Controlled Tumor Protein (TCTP) is a critical survival factor of stem cells including cancer stem cells. Here, we aimed to determine whether the TCTP inhibitor sertraline (STL) could target prostate cancer stem cells (PCSC). In colony formation, spheroidogenesis, angiogenesis, and wound healing assays STL showed a robust inhibition of tumorigenic (colony growth), angiogenic (endothelial tube formation) and metastatic (wound healing and migration) potential of PCSC. Interestingly, antioxidants such as N-acetyl cysteine (NAC), Glutathione (GSH) and catalase effectively blocked the cytotoxicity effect of STL on PCSC implicating oxidative stress as the underlying anti-PCSC targeting mechanism. Cell cycle analysis showed a robust G₀ arrest in PCSC exposed to STL. Notably, STL induced both apoptosis and autophagy by activating free radical generation, hydrogen peroxide formation (H₂O₂), lipid peroxidation (LPO) and depleted the levels of glutathione (GSH). Moreover, surface marker expression analysis using confocal revealed that STL significantly down regulates the expression levels of aldehyde dehydrogenase 1 (ALDH1) and cluster of differentiation 44 (CD44) stem cell markers. Furthermore, in western blot analysis, STL treatment applied in a dose-dependent manner, caused a marked decrease in TCTP, phospho TCTP, anti-apoptotic markers survivin and cellular inhibitor of apoptosis protein 1 (cIAP1) expression as well as a significant increase in cleaved caspase3 and cleaved Poly [ADP-ribose] polymerase 1 (PARP-1) expression. Of note, STL also significantly down regulated the stem cell markers (ALDH1 and CD44) and epithelial to mesenchymal transition (EMT) markers such as transcription factor 8 (TCF8) and lymphoid enhancer-binding factor-1 (LEF1) expression levels. Concurrently, STL increased the levels of autophagy markers such as light chain (LC3), Beclin1 and autophagy-related gene (ATG5). Taken together, our study suggests that STL could be an effective therapeutic agent in eliminating prostate cancer stem cells.

HMGB1-Neutralizing IgM Antibody Is a Normal Component of Blood Plasma

Extracellular high-mobility group box 1 (HMGB1) is a prototypic damage-associated molecular pattern. Although a homeostatic level of extracellular HMGB1 may be beneficial for immune defense, tissue repair, and tissue regeneration, excessive HMGB1 is linked to inflammatory diseases. This prompts an intriguing question: how does a healthy body control the level of extracellular HMGB1? In this study, in the plasma of both healthy humans and healthy mice, we have identified an anti-HMGB1 IgM autoantibody that neutralizes extracellular HMGB1 via binding specifically to a 100% conserved epitope, namely HMW4 (HMGB1_98-112). In mice, this anti-HMW4 IgM is produced by peritoneal B-1 cells, and concomitant triggering of their BCR and TLR4 by extracellular HMGB1 stimulates the production of anti-HMW4 IgM. The ability of extracellular HMGB1 to induce its own neutralizing Ab suggests a feedback loop limiting the level of this damage-associated molecular pattern in a healthy body.

Neferine, an alkaloid from lotus seed embryo targets HeLa and SiHa cervical cancer cells via pro-oxidant anticancer mechanism

Apoptosis and autophagy are important processes that control cellular homeostasis and have been highlighted as promising targets for novel anticancer drugs. This study aims to investigate the inhibitory effects and mechanisms of Neferine (Nef), an alkaloid from the lotus seed embryos of Nelumbo nucifera (N. nucifera), as a dual inducer of apoptosis and autophagy through the reactive oxygen species (ROS) activation in cervical cancer cells. Nef and N. nucifera extract suppressed the cell viability of HeLa and SiHa cells in a dose-dependent manner. Importantly, Nef showed minimal toxicity to normal cells. Furthermore, Nef inhibited anchorage-independent growth, colony formation and migration ability of cervical cancer cells. Nef induces mitochondrial apoptosis by increasing pro-apoptotic protein bax, cytochrome-c, cleaved caspase-3 and caspase-9, poly-ADP ribose polymerase (PARP) cleavage, DNA damage (pH₂ AX) while downregulating Bcl-2, procaspase-3 and procaspase-9, and TCTP. Of note, apoptotic effect by Nef was significantly attenuated in the presence of N-acetylcysteine (NAC), suggesting pro-oxidant activity of this compound. Nef also promoted autophagy induction through increasing beclin-1, atg-4, atg-5 and atg-12, LC-3 activation, and _P 62/SQSTM1 as determined by western blot analysis. Collectively, these results demonstrate that Nef is a potent anticancer compound against cervical cancer cells through inducing apoptosis and autophagic pathway involving ROS.

Quantitative imaging of the receptor for advanced glycation end-products in prostate cancer

PURPOSE

Current screening and monitoring of prostate cancer (PCa) is insufficient, producing inaccurate diagnoses. Presence of the receptor for advanced glycation end-products (RAGE) is associated with signature characteristics of PCa development such as cell proliferation, anchorage-independent growth, angiogenesis, migration, invasion, and poor patient survival. Therefore, we developed a preclinical multimodal imaging strategy targeted at RAGE to diagnose and monitor PCa.

METHODS

In this work, RAGE-targeted multimodal nanoparticles (64Cu-Cy5-G4-CML) were synthesized and rendered functional for nuclear and optical imaging using previously established methods. The probe's binding affinity and targeting specificity was assessed in androgen-dependent (LNCaP) and androgen-independent (DU145) prostate cancer cells using flow cytometry and confocal microscopy. In vivo PET-CT imaging was used to evaluate RAGE levels in DU145 and LNCaP xenograft models in mice. Then, tumors were excised post-imaging for histological staining and autoradiography to further assess RAGE levels and targeting efficiency of the tracer. Finally, RAGE levels from human PCa samples of varying Gleason Scores were evaluated using Western blot and immunohistochemical staining.

RESULTS

PCa cell culture studies confirmed adequate RAGE-targeting with 64Cu-Cy5-G4-CML with K_D between 360 and 540 nM as measured by flow cytometry. In vivo PET-CT images of PCa xenografts revealed favorable kinetics, rapid blood clearance, and a non-homogenous, enhanced uptake in tumors, which varied based on cell type and tumor size with mean uptake between 0.5 and 1.4%ID/g. RAGE quantification of human samples confirmed increased RAGE uptake corresponding to increased Gleason scoring.

CONCLUSIONS

Our study has shown that RAGE-targeted cancer imaging is feasible and could significantly impact PCa management.

Nitro aspirin (NCX4040) induces apoptosis in PC3 metastatic prostate cancer cells via hydrogen peroxide (H2O2)-mediated oxidative stress

Non-steroidal anti-inflammatory drugs (NSAID) have shown promise as anticancer agents by inducing cell death apart from their antipyretic, anti-inflammatory and anti-thrombogenic effects. In our current study, we investigated the oxidative stress mediated cell death mechanism of a NSAID derivative NCX4040 (a nitric oxide (NO) releasing form of aspirin) in castration-resistant prostate cancer (CRPC) PC3 cell line. Our data revealed that NCX4040 is more potent than its parent compound aspirin or NO releasing compound DETA NONOate. NCX4040 significantly induced hydrogen peroxide formation with ensuing oxidative stress and mitochondrial depolarization resulting in lipid peroxidation, cell cycle arrest, inhibition of colony growth and induction of apoptosis in PC3 cells. Moreover, NCX4040 inhibited migration potential of PC3 cells by depolymerizing F-actin and promoting anoikis. Interestingly, elevated levels of NADPH oxidase 1 (NOX1), superoxide dismutase (SOD) 1 and 2 were observed upon NCX4040 treatment. However, down regulation of anti-apoptotic markers B-cell lymphoma 2 (Bcl2) and anti-oxidant thioredoxin reductase 1 (TXNRD1) expression were observed. In addition, NCX4040 down regulated cyclin D1 expression in PC3 cells further supporting the anticancer effect of NCX4040. Western blot analysis revealed that significant down regulation of key anti-apoptotic markers such as cellular inhibitor of apoptosis protein-1 (cIAP1), X-linked inhibitor of apoptosis (XIAP), survivin, and Cellular-Myc (c-Myc). On the other hand, NCX4040-treated cells showed upregulation of phosho histone H2AX (pH2AX), cleaved caspase3 and cleaved Poly [ADP-ribose] polymerase 1 (PARP1). Taken together, our data demonstrate that NCX4040 treatment enhances free radical formation which in turn induces oxidative stress leading to mitochondrial mediated cell death in metastatic PC3 cells.

Abstract 2974: Preclinical evaluation of Ozanimod for prostate cancer treatment

Prostate cancer (PCa) is the second leading cause of cancer-related death in men of United States, after lung cancer. There are various treatment options such as surgery, radiation therapy, chemotherapy, and androgen deprivation therapy are availabale for PCa. However, invariably patients develop resistance to these therapies, resulting in the manifestation of aggressive and recurrent PCa. Hence, there is an urgent need for an effective treatment strategy for managing PCa. Previous studies have identified that the sphingosine 1-phosphate receptor (S1PR) as a potential target to treat prostate cancer. Ozanimod (OZM) is a selective sphingosine 1- phosphate receptor 1 (S1PR1) and (S1PR5) modulator, which is in phase 3 clinical trial for patients with relapsing multiple sclerosis and ulcerative colitis. The objective of this study is to determine the anticancer effects of OZM, an S1PR modulator using LNCaP, PC-3, and DU-145 as cellular models of PCa. These PCa cell lines were subjected to cell viability, colony formation and wound healing assays as endpoints to assess the anticancer effects of OZM. The cell viability assay results revealed that OZM had a differential effect on PCa cell lines with LNCaP cells being the most sensitive and DU-145, PC-3 showing similar sensitivities to OZM treatment. Furthermore, OZM treatment inhibited the colony formation characteristics of PCa cell lines in-vitro when compared with control in all the three cell lines. In wound healing assay, the migratory characteristics of PCa cell lines were inhibited by OZM in a dose dependent manner. These findings suggested that OZM has both tumor growth suppression and metastasis inhibition potential. Furthermore, Annexin V and Propidium Iodide staining assay revealed that OZM

induces apoptosis in PC-3 and DU-145 cells. Following these findings, human apoptotic array study using LNCaP cells showed that anti-apoptotic protein molecules such as c-IAP1, clusterin, and livin were downregulated by OZM treatment in addition to inhibition of HIF-1α expression. The mechanistic study conducted using LNCaP cells by Western blot analysis revealed that OZM treatment upregulated BiP expression while downregulated PERK, IRE-1α which are protein markers associated with endoplasmic reticulum (ER) stress pathway. Furthermore, our results showed that c-myc was down-regulated and MAD, MAX transcription factors were upregulated when treated with OZM. Based on these findings, we suggest that OZM treatment modulates ER stress pathway and anti-apoptotic proteins leading to prostate tumor suppression. In conclusion, OZM might be a potential chemotherapeutic agent for treating both indolent and aggressive PCa.

Citation Format: Reshmii Venkatesan, Somaiah Chinnapaka, John Schappert, Gnanasekar Munirathinam. Preclinical evaluation of Ozanimod for prostate cancer treatment [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 2974.

Abstract 2960: NCX4040, a nitric oxide (NO) donating form of aspirin as a potential treatment for prostate cancer

Nonsteroidal anti-inflammatory drugs (NSAIDs) have been shown to be beneficial in preventing various types of cancers including prostate cancer (PCa). Of all the NSAIDs in use, Aspirin appears to be one of the promising anticancer agents for PCa management. However, experimental and epidemiological studies indicated that larger doses of Aspirin and long term supplementation is required to achieve anticancer effect with accompanied side effects. Therefore, our study focused on evaluating Aspirin derivative, namely NCX4040 which is a NO releasing form of Aspirin as a potent alternative for PCa treatment while minimizing the side effects. In the present study, we assessed the anticancer effects of NCX4040 on PC-3, a bone metastatic PCa cell line employing various in-vitro cellular assays. In our preliminary studies, we compared the effects of NCX4040 with that of Aspirin and NO releasing compound DETA/NO on PC-3 cells using MTT as read out. These results showed that NCX4040 is highly potent in inhibiting the viability of PC-3 cells when compared to Aspirin or DETA/NO treatments. Hence, further studies were focused on characterizing the anticancer properties as well as the underlying anticancer mechanism of NCX4040. Of note, our results showed that NCX4040 robustly inhibited the colony forming ability of PC-3 cells in-vitro implicating its antitumorigenic potential. In addition to inhibiting colony formation of PC-3 cells, NCX4040 also suppressed the Transwell matrigel invasion of PC-3 cells suggesting the antimetastatic effects of NCX4040. The observed antimetastatic effect of NCX4040 in PC-3 PCa cells appears to be via targeting actin cytoskeleton as confirmed by confocal microscopic analysis using phalloidin stain. Following these findings, we performed cell cycle analysis to determine whether NCX4040 enforces cell cycle arrest in PC-3 cells. These results showed that NCX4040 induced robust G0 cell cycle arrest in a dose dependent manner. Moreover, flow cytometry analysis using Annexin V and PI staining revealed that NCX4040 induced potent apoptotic cell death in PC-3 cells. To delineate the underlying anticancer mechanism of NCX4040, PC-3 cells treated with NCX4040 was subjected to apoptotic protein array analysis. Results of this study inferred that NCX4040 down regulated the expression of key anti-apoptotic proteins such as Survivin, XIAP and IAPs. In conclusion, our study suggests that NCX4040 is a promising alternative agent for PCa treatment.

Citation Format: SOMAIAH CHINNAPAKA, Gnanasekar Munirathinam. NCX4040, a nitric oxide (NO) donating form of aspirin as a potential treatment for prostate cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 2960.

Abstract 2958: Evaluating the therapeutic effects of methylene blue against prostate cancer

Prostate cancer (PCa) is the second most commonly occurring cancer among men and the fourth most commonly occurring cancer overall. According to American Cancer Society, in the year 2018, it was estimated that there will be 164,690 new cases and 29,430 deaths from PCa. The treatment options currently available for PCa are found to be ineffective with varied side effects and complications associated with the development of resistance among patients. Therefore, there is an unmet need to find a safe and potent agent to treat PCa. In our study, we focused on studying the anticancer potential of Methylene Blue (MB) which belongs to the class of phenothiazinium salt. MB has been widely used to treat the condition of methemoglobinemia, emerging studies have shown that it has been effectively used as a photosensitizer in the treatment of cancer by means of photodynamic therapy (PDT). Our initial analysis showed that MB effectively reduced the viability of androgen-dependent (LNCaP) and androgen-independent (PC3 and DU145) PCa cells. Further experimental evaluations showed that MB inhibited the colony forming ability of PCa cells in-vitro suggesting its tumor suppressive potential. In addition, our studies showed that MB treatment disrupted the migration potential of PCa cells in a wound healing assay indicating the anti-metastatic function of MB. Moreover, confocal and FACS analysis using Annexin V FITC and propidium iodide staining revealed that MB effectively targeted the PCa cell lines by inducing apoptotic cell death. To delineate the underlying anticancer mechanism of MB, apoptosis protein array was performed employing LNCaP cells, and the results of which showed that key apoptotic molecules such as Bax, TRAIL

R2/D5, and phospho p53 (Serine 15, Serine 46, Serine 392) were robustly upregulated in LNCaP cells following MB treatment. In conclusion, our findings suggest that MB induces apoptosis in PCa cells and thus could serve as a potential anticancer agent for treating both hormone-dependent and -independent PCa.

Citation Format: Priyadarshini Thiruvalluvan Shanthi, Abigail Foes, Gnanasekar Munirathinam. Evaluating the therapeutic effects of methylene blue against prostate cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 2958.

Multimodal imaging of the receptor for advanced glycation end-products with molecularly targeted nanoparticles

The receptor for advanced glycation end-products (RAGE) is central to multiple disease states, including diabetes-related conditions such as peripheral arterial disease (PAD). Despite RAGE's importance in these pathologies, there remains a need for a molecular imaging agent that can accurately assess RAGE levels in vivo. Therefore, we have developed a multimodal nanoparticle-based imaging agent targeted at RAGE with the well-characterized RAGE ligand, carboxymethyllysine (CML)-modified human serum albumin (HSA).

Methods: A multimodal tracer (⁶⁴Cu-Rho-G4-CML) was developed using a generation-4 (G4) polyamidoamine (PAMAM) dendrimer, conjugated with both rhodamine and copper-64 (⁶⁴Cu) chelator (NOTA) for optical and PET imaging, respectively. First, ⁶⁴Cu-Rho-G4-CML and its non-targeted analogue (⁶⁴Cu-Rho-G4-HSA) were evaluated chemically using techniques such as dynamic light scattering (DLS), electron microscopy and nuclear magnetic resonance (NMR). The tracers' binding capabilities were examined at the cellular level and optimized using live and fixed HUVEC cells grown in 5.5-30 mM glucose, followed by in vivo PET-CT imaging, where the probes' kinetics, biodistribution, and RAGE targeting properties were examined in a murine model of hindlimb ischemia. Finally, histological assessment of RAGE levels in both ischemic and non-ischemic tissues was performed.

Conclusions: Our RAGE-targeted probe demonstrated an average size of 450 nm, a Kd of 340-390 nM, rapid blood clearance, and a 3.4 times greater PET uptake in ischemic RAGE-expressing hindlimbs than their non-ischemic counterpart. We successfully demonstrated increased RAGE expression in a murine model of hindlimb ischemia and the feasibility for non-invasive examination of cellular, tissue, and whole-body RAGE levels with a molecularly targeted tracer.

Abstract 2873: Targeting RAGE for prostate cancer treatment

Prostate cancer (PCa) is the second most common cancer among men and is the third leading cause of cancer-related death in the United States. In 2017 alone, an estimated 161,360 men will be diagnosed with PCa and approximately 26,730 deaths will result from this disease in the United States. The most common methods for PCa treatment include surgery, radiotherapy, and hormone therapy. These treatment options unfortunately have serious drawbacks such as the possibility of organ damage, adverse side effects, and eventual PCa resistance to treatment. Due to the severe threat that PCa poses across the male population, it is vital that more effective and safe treatment options are explored. Previous research has indicated that the receptor for advanced glycation end products (RAGE) plays a vital role in the survival of prostate cancer cells, indicating that RAGE could be a potential therapeutic target. In the present study, we focused on targeting RAGE using two different antagonists, RAGE aptamer and azeliragon as potential alternative therapies for PCa. Confocal microscopy assays initially confirmed that RAGE aptamer expression strongly binds to VCaP cells while azeliragon treatment decreased the expression of RAGE in these cells. MTT cell viability assays indicated that RAGE aptamer and azeliragon decrease PCa cell proliferation in a dose-dependent manner for VCaP and DU-145 cell lines respectively. Cell cycle analysis suggested that RAGE aptamer and azeliragon-treated DU-145 cells enforced cellular G0/G1 phase arrest in a dose-dependent manner. Annexin V FITC and ROS immunofluorescence assays showed that RAGE aptamer and azeliragon induce apoptosis potentially by inducing oxidative stress in PCa cells. Apoptosis activation in RAGE aptamer and azeliragon-treated VCaP cells was confirmed by the detection of PARP-1 cleavage through western blotting. Taken together, our findings suggest that RAGE aptamer and azeliragon may be a promising alternative form of therapy for PCa patients.

Citation Format: Kyle J. Ernzen, Subramanyam Dasari, Gnanasekar Munirathinam. Targeting RAGE for prostate cancer treatment [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 2873.

Abstract 2905: Deciphering and blocking the mechanisms of cadmium induction of TCTP in prostate cancer cells

While cadmium is a well-known lung carcinogen, its role in prostate cancer is yet to be understood. Recently, a meta-analysis study showed that cadmium did not increase the risk of prostate cancer. It is not known whether cadmium exposure at environmentally relevant concentrations increases aggressiveness of already existing prostate cancer. Although our lab previously showed that the 75th percentile of cadmium concentration in prostate cancer was associated with biochemical recurrence, more evidence is needed to substantiate this finding. We also showed evidence that cadmium promotes prostate cancer cells migration and invasion via inducing the expression of translationally controlled tumor protein (TCTP). Furthermore, it was demonstrated that cadmium induces the phosphorylation of p38, and that the p38 inhibitor SB203580 (SB) blocks the effects of cadmium on migration and invasion. In this study, we aimed to delineate the signaling events upon cadmium treatment; whether p38 or TCTP is upstream. We addressed this via inhibition of p38 using SB203580 and by inducing TCTP degradation via dihydroartemisinin (DHA) followed by measurement of TCTP expression and phosphorylation of p38 respectively. p38 inhibition led to the increased expression of TCTP on both mRNA and protein levels. Pretreatment with DHA led to less TCTP expression and less phosphorylation of p38. We also aimed to understand the effect of cadmium on cell proliferation, survival and migration. While DHA lowered the colony count and EdU incorporation, cadmium did not alter these functions. In addition, DHA abrogated the cadmium-mediated migration of PC3-Inv prostate cancer cell line. Furthermore, we aimed to determine the effect of nanomolar cadmium concentrations on the phosphorylation of PlK1, which is well established to be upstream of TCTP. Our results demonstrated that nanomolar concentrations of cadmium resulted in increased phosphorylation of PlK1 in both PC3 and LNCaP cells. Altogether, our results suggest that environmentally relevant exposures of cadmium induce TCTP expression through several pathways, and that there is a feedback mechanism between p38 and TCTP.

Citation Format: Rama Saad, Gnanasekar Munirathinam, Theresa Kucynda, Marta Ribeiro, Paul Lindholm, Andre Balla. Deciphering and blocking the mechanisms of cadmium induction of TCTP in prostate cancer cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 2905.

Abstract 3978: Therapeutic evaluation of eprinomectin against advanced prostate cancer

Prostate Cancer (PCa) is the second most common cancer among men in United States after skin cancer. According to the American Cancer Society, in 2017 alone there will be 16,130 new cases of PCa and 26,730 deaths from PCa. Conventional chemotherapeutic drugs available for PCa treatment are limited due to toxicity and resistance issues. Therefore, there is an urgent need to develop more potent treatment for advanced PCa. Eprinomectin (EP) belongs to the class of avermectins which are lactone derivatives with potent anti-helminthic and anti-cancer properties. EP has been widely used to treat parasitic diseases in cattle and is found to be less toxic than the other avermectin class of drugs. The goal of our current study is to test the anti-cancer efficacy of EP on PCa cells. Initially cell viability assays were performed on PCa cell lines such as PC3, DU145, LNCaP, VCaP, and 22RV1 to assess the anti-cancer efficacy of EP. Among all the PCa cell lines tested, PC3 and DU145 showed more sensitivity to EP. Specifically, cell viability assays indicated that EP reduced the viability of PC3 and DU145 PCa cells by 50% at 25μM concentration. Next, in soft agar assay, EP effectively inhibited the anchorage independent growth of prostate cancer cells in vitro. Furthermore, wound healing assay results suggested that EP targeted the migratory property of PC3 and DU145 cell lines. In addition, apoptosis assay using Annexin-FITC and propidium iodide staining revealed that EP targets PC3 and DU145 cells by inducing apoptosis. Cell cycle analysis showed that EP arrested the PC3 and DU145 cells in G0 phase of the cell cycle. Interestingly, our results also showed that EP targets the PCa cells by inducing oxidative stress. Real time PCR analysis showed that EP effectively inhibited the expression of various cancer stem cell markers such as ALDH1, Sox-2, Nanog, Oct3/4 and CD44. In PC3 and DU145 cell lines, EP effectively inhibited the activity of Alkaline Phosphatase suggesting that EP could target pluripotent stem cells. In addition, treatment of PC3 and DU145 cells with EP resulted in the translocation of ß-catenin from the nucleus to the cytoplasm indicating that EP antagonizes Wnt/ß-catenin signaling pathway. Furthermore, EP also decreased the expression of the downstream target genes of ß-catenin such as cyclin D1 and c-Myc in PC3 and DU145 cells. EP also downregulated the expression of other key cell cycle markers such as cyclin D3, CDK4 and anti-apoptotic markers such as Bcl-2, Bcl-XL, XIAP, c-IAP2 and survivin in PC3 and DU145 cells. On the contrary, treating PC3 and DU145 cells with EP resulted in the activation of DNA damage marker, pH2AX and upregulation of pro apoptotic marker, Bad with concomitant activation of Caspase-9 and Caspase-3. Based on our results, EP appears to potently target advanced PCa cells by inhibiting tumorigenic and metastatic properties of advanced PCa cells in vitro. Further in vivo and preclinical studies are warranted to test the efficacy of EP on PCa.

Citation Format: Angela Lincy Prem Antony Samy, Syed M. Ali, Subramanyam Dasari, Gnanasekar Munirathinam. Therapeutic evaluation of eprinomectin against advanced prostate cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 3978.

Polygodial analog induces apoptosis in LNCaP prostate cancer cells

Prostate cancer (PCa) is the second leading cause of death in American men. The chemotherapeutic treatment strategies are generally not effective and can lead to side effects. Hence, there is an urgent need to identify novel chemotherapeutic agents. The aim of this study was to synthesize and evaluate the therapeutic effects of a synthetic analog of polygodial (PG), a pungent constituent abundantly present in mountain pepper, water pepper and dorrigo pepper, on LNCaP PCa cell line and its anti-cancer mechanisms in a preclinical study. We evaluated the anti-cancer potential of the PG analog namely DRP-27 using various assays such as cell viability by MTT assay, anchorage independent growth by soft agar assay, reactive oxygen species generation by 2',7'-dichlorofluorescein probe-based fluorescence assay, and apoptosis by Annexin-V and TUNEL assays respectively. Western blot analysis was performed to identify the molecular mechanism of DRP-27-induced cell death. Our results showed that DRP-27 significantly inhibited LNCaP cell proliferation in a dose-dependent manner at 48 h treatment in vitro. In addition, DRP-27 potently inhibited anchorage-independent growth of these cells. Flow cytometry, Annexin-V and TUNEL assays confirmed that DRP-27 induces apoptosis in LNCaP cells. DRP-27 also induced the activation of intracellular reactive oxygen species. Western blot analysis revealed that DRP-27 downregulated the expression of survivin, while activating Bax and DNA damage marker pH₂AX in LNCaP cells. In conclusion, our study suggests that DRP-27 might be an effective anti-cancer agent for PCa.

Photosensitizers in prostate cancer therapy

The search for new therapeutics for the treatment of prostate cancer is ongoing with a focus on the balance between the harms and benefits of treatment. New therapies are being constantly developed to offer treatments similar to radical therapies, with limited side effects. Photodynamic therapy (PDT) is a promising strategy in delivering focal treatment in primary as well as post radiotherapy prostate cancer. PDT involves activation of a photosensitizer (PS) by appropriate wavelength of light, generating transient levels of reactive oxygen species (ROS). Several photosensitizers have been developed with a focus on treating prostate cancer like mTHPC, motexafin lutetium, padoporfin and so on. This article will review newly developed photosensitizers under clinical trials for the treatment of prostate cancer, along with the potential advantages and disadvantages in delivering focal therapy.

Vitamin K2, a menaquinone present in dairy products targets castration-resistant prostate cancer cell-line by activating apoptosis signaling

The aim of this study was to evaluate the therapeutic effects of vitamin K2 (VK2) on castration-resistant prostate cancer (CRPC) and its anti-cancer mechanisms in a pre-clinical study using a VCaP cell line (ATCC^® CRL-2876™) which was established from a vertebral bone metastasis from a patient with hormone refractory prostate cancer. Our data showed that VK2 significantly inhibited CRPC VCaP cell proliferation in a dose-dependent manner at 48 h treatment in vitro. In addition, VK2 reduced the migration potential of VCaP cells and inhibited anchorage-independent growth of these cells. Our results also showed that VK2 induces apoptosis in VCaP cells. Furthermore, VK2 enforced growth arrest in VCaP cells by activating cellular senescence. Notably, VK2 treatment elevated the levels of reactive oxygen species in VCaP cells. Western blot analysis revealed that VK2 downregulated the expression of androgen receptor, BiP, survivin, while activating caspase-3 and -7, PARP-1 cleavage, p21 and DNA damage response marker, phospho-H2AX in VCaP cells. In conclusion, our study suggests that VK2 might be a potential anti-cancer agent for CRPC by specifically targeting key anti-apoptotic, cell cycle progression and metastasis-promoting signaling molecules.

Abstract 119: Vitamin K2 targets castration-resistant prostate cancer VCaP cells by reactive oxygen species mediated apoptotic cell death

Prostate Cancer (PCa) is the second most common cancer in western countries especially in US population, in which castration-resistant prostate cancer (CRPC) is the major cause for patient mortality. Current treatment options available for CRPC are not efficient and have undesirable side effects. Hence there is an urgent need to develop non-toxic and effective treatment strategies for CRPC. Vitamin K2 (VK2), a natural menaquinone has several medicinal values including anti-cancer activity and anti-osteoporosis effect. The aim of this study is to evaluate the therapeutic effects of Vitamin K2 (VK2) and its anti-cancer mechanism against CRPC. In this study, we have used VCaP cell line (ATCC) which is established from a patient with hormone refractory prostate cancer. VCaP cells were treated with various concentrations of VK2 to evaluate its effects on cell viability by MTT assay, anchorage independent growth by soft agar assay, cellular senescence by beta-galactosidase staining assay and cancer cell migration by wound healing assay. We have also assessed the VK2-induced production of intracellular reactive oxygen species (ROS) using DCF (2′,7′-dichlorofluorescein) probe based fluorescence assay. VK2 induced apoptosis was detected by Annexin-V FITC and TUNEL assays. Western blot analysis was utilized to uncover the anti-proliferative and anti-metastatic mechanisms of VK2 against CRPC. Our results showed that VK2 significantly inhibits the proliferation of VCaP cells in a dose dependent manner at 48 hrs treatment in vitro. MTT data also showed that anti-proliferative effects of VK2 were significantly abrogated in the presence of anti-oxidant N-acetyl cysteine (NAC) and caspase inhibitor Z-VAD-FMK suggesting that ROS and caspase activation as the underlying anti-cancer mechanisms of VK2 in CRPC cells. In addition, VK2 reduced the migration potential of VCaP cells in wound healing assay and inhibited anchorage independent growth of these cells when compared to untreated cells. Annexin-V and TUNEL assays confirmed that VK2 induces apoptosis in VCaP cells. Our results also suggested that the VK2 has the ability to enforce growth arrest in CRPC cells by activating cellular senescence. Western blot analysis revealed that VK2 downregulated the expression of BiP, survivin, MMP-2, and PCNA while activating PARP-1, p21 and DNA damage response marker, phospho-H2AX in VCaP cells. Furthermore, VCaP cells treated with VK2 resulted in the activation of Caspase-3 and-7 apoptotic mediators. These results correlated with translocation of Bax and Cytochrome C to cytoplasm following VK2 treatment in VCaP cells as determined by confocal immunofluorescence analysis. In conclusion our study suggests that VK2 might be an effective anti-proliferative and anti-metastatic agent for CRPC by specifically targeting key anti-apoptotic, cell cycle progression and metastasis promoting signaling molecules.

Citation Format: Subramanyam Dasari, Maarten C. Bosland, Andre Kajdacsy- Balla, Gnanasekar Munirathinam. Vitamin K2 targets castration-resistant prostate cancer VCaP cells by reactive oxygen species mediated apoptotic cell death [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 119. doi:10.1158/1538-7445.AM2017-119

Abstract 1592: Anti-cancer evaluation of various solvent extracts of blue honeysuckle berry (Lonicera caerulea L.) against prostate cancer cells

Prostate cancer (PCa) is the second most common cancer among men in the United Sates. It is estimated 1 in 6 men will be diagnosed with PCa and approximately 180,890 new cases are predicted in 2016 alone. Standard treatments for PCa include surgery, radiation, chemotherapy and hormonal therapy or a combination of these treatments. However, factors like patient health, drug resistance, specificity, and toxicity can result in poor disease prognosis. In order to overcome these limitations and improve patient prognosis, there is an urgent need to identify new anti-cancer agents with minimal side effects. Current studies are being focused on natural products and their components for alternative therapeutics. Blue Honeysuckle (Lonicera caerule L.) a berry native to northeast Asia, is known to be rich in Vitamin C and polyphenols such as anthocyanins, flavonoids, and phenolic acids. Polyphenols are found to have several therapeutic effects such as anti-inflammatory, antioxidant and antimicrobial properties. Our present study used sequential solvent extracts of Blue Honeysuckle (BHS) berry using Hexane, Ethyl Acetate, Methanol, and Water respectively. These fractions were used to assess various therapeutic effects of BHS on DU 145, PC-3, C4-2 and LNCaP PCa cell lines. The goal was to identify the most potent BHS fraction that is effective against PCa using pre-clinical studies. MTT assays were used to identify the anti-proliferative effects of various BHS fractions. The above indicated PCa cells were treated with different doses (10-150 µg/mL) of BHS factions over various time periods (24, 48, 72 hr). Our data revealed that Hexane extract (HE) exhibited the highest inhibition of cell viability in a time and dose-dependent manner. HE fraction showed to have an IC50 of 89.6 μg/mL for DU 145, 117.4 μg/mL for PC-3, 163.3 μg/mL for C4-2 and 140.84 for LNCaP cells. Moreover, BHS HE fraction showed a decrease in migration capacity and colony formation ability of PCa cells in vitro. Cellular senescence assay was performed to assess β-Galactosidase activity in PCa cells treated with BHS HE extract. All the PCa cell lines treated with 100 µg/mL of BHS HE showed increased senescence. Western blotting was performed to identify the potential anti-cancer mechanism of BHS against PCa using DU 145 and PC-3 cell lines. Results from this study indicated that DU 145 and PC-3 cell lines after 24 hr treatment with 100 μg/mL of various BHS fractions especially BHS HE showed an increase in apoptosis (Caspase 3,8,9 and PARP-1) and autophagy (LC3 A/B) markers. Furthermore, cell cycle analysis of DU 145 and PC-3 cells treated with BHS HE extract showed increased apoptotic cells. Further analysis of apoptotic and autophagy pathways modulated by BHS treatments are required to illustrate its potential underlying anti-cancer mechanisms in PCa. In conclusion, results from our study warrant further evaluation of BHS berry for potential PCa management.

Citation Format: Syed M. Ali, Alex Ourth, Chun-Tao Che, Mian-Ying Wang, Gnanasekar Munirathinam. Anti-cancer evaluation of various solvent extracts of blue honeysuckle berry (Lonicera caerulea L.) against prostate cancer cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 1592. doi:10.1158/1538-7445.AM2017-1592

Vitamin K and its analogs: Potential avenues for prostate cancer management

Epidemiological studies have demonstrated a relationship between cancer incidence and dietary habits. Especially intake of certain essential nutrients like vitamins has been shown to be beneficial in experimental studies and some clinical trials. Vitamin K (VK) is an essential nutrient involved in the blood clotting cascade, and there are considerable experimental data demonstrating its potential anticancer activity in several cancer types including prostate cancer. Previous in vitro and in vivo studies have focused mainly on anti-oxidative effects as the underlying anticancer mechanism of VK. However, recent studies reveal that VK inhibits the growth of cancer cells through other mechanisms, including apoptosis, cell cycle arrest, autophagy, and modulation of various transcription factors such as Myc and Fos. In the present review, we focus on the anticancer effect of dietary VK and its analogs on prostate cancer, with an emphasis on the signaling pathways that are activated following exposure to these compounds. This review also highlights the potential of VK and its derivatives as an adjuvant treatment in combination with other vitamins or with chemotherapeutic drugs. Based on our recent results and a review of the existing literature, we present evidence that VK and its derivatives can potentially be explored as cancer therapy, especially for prostate cancer.

Hepatoma-derived growth factor: A survival-related protein in prostate oncogenesis and a potential target for vitamin K2

Hepatoma-derived growth factor (HDGF) is a heparin-binding growth factor, which has previously been shown to be expressed in a variety of cancers. HDGF overexpression has also previously been correlated with a poor prognosis in several cancers. The significance of HDGF in prostate cancer, however, has not been investigated. Here, we show that HDGF is overexpressed in both androgen-sensitive LNCaP cells and androgen-insensitive DU145, 22RV1, and PC-3 cells. Forced overexpression enhanced cell viability of RWPE-1 cells, whereas HDGF knockdown reduced cell proliferation in human prostate cancer cells. We also show that HDGF may serve as a survival-related protein as ectopic overexpression of HDGF in RWPE cells up-regulated the expression of antiapoptosis proteins cyclin E and BCL-2, whereas simultaneously down-regulating proapoptotic protein BAX. Western blot analysis also showed that HDGF overexpression modulated the activity of phospho-AKT as well as NF-kB, and these results correlated with in vitro migration and invasion assays. We next assessed the therapeutic potential of HDGF inhibition with a HDGF monoclonal antibody and vitamin k₂, showing reduced cell proliferation as well as inhibition of NF-kB expression in HDGF overexpressed RWPE cells treated with a HDGF monoclonal antibody and vitamin K₂. Collectively, our results suggest that HDGF is a relevant protein in prostate oncogenesis and may serve as a potential therapeutic target in prostate cancer.

Abstract 1672: Photodynamic therapy using photosensitizer and light emitting diodes (LEDs) demonstrates oncolytic activity against prostate cancer

Prostate cancer (PCa) affects over 2 million Americans and its treatment options include surgery, anti-hormonal drugs for androgen sensitive tumors, and radiotherapy. However, patients undergoing androgen deprivation therapy develop resistance leading to development of castration resistant or androgen independent PCa. It is clear there is an urgent need to find an effective treatment strategy to manage aggressive PCa. An alternative treatment is the use of photodynamic therapy (PDT), which involves the activation of a photosensitizer by a defined wavelength of light in the presence of oxygen, generating transient concentrations of reactive oxygen species. We hypothesize that PDT via a photosensitizer (pheophorbide) in combination with light emitting diodes (LEDs) [670 nm] will demonstrate oncolytic activity against PCa cells, thus suggesting an alternative, less toxic cancer treatment. To test our hypothesis, we used C4-2 and DU-145 PCa cell lines as an in vitro model in this study. To explore the anti-cancer effects of PDT on PCa, cell viability assay and wound healing assay were performed. Western blotting was employed to identify the signaling molecules modulated by PDT. Our cell viability assay results demonstrated significant oncolytic activity against PCa cell lines using PDT with pheophorbide as a photosensitizer combined with 670 nm LEDs in as little as an 88 second pulse with increased lytic activity correlating with elevated energy intensities. We also observed variability in cell line PDT susceptibility; wherein, C4-2 cells were more susceptible than DU-145 PCa cells. The wound healing assay results with pheophorbide and 670 nm LEDs demonstrated significant inhibition of migration abilities of both C4-2 and DU-145 PCa cells. These findings implicate the anti-metastatic activity of PDT on PCa. Further, our mechanistic analysis showed activation of BiP/GRP78, an endoplasmic reticulum (ER) chaperone, in C4-2 as well as DU-145 PCa cells. This suggests that the anti-cancer activity of PDT with pheophorbide and 670 nm LEDs is via ER stress. In conclusion, our results show PDT using pheophorbide and 670 nm LEDs as a promising therapeutic strategy for PCa.

Citation Format: Taher Gheewala, Troy Skwor, Gnanasekar Munirathinam. Photodynamic therapy using photosensitizer and light emitting diodes (LEDs) demonstrates oncolytic activity against prostate 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 1672.

Abstract 4804: Polygodial: A potential sesquiterpene dialdehyde for castration-resistant prostate cancer treatment

Major cause for prostate cancer mortality is due to the development of castration-resistant prostate cancer (CRPC) which usually develops when prostate cancer patients undergo standard androgen deprivation therapy. Treatment options currently available for CRPC are not very efficient and have many side effects. Hence, there is an urgent need to identify effective treatment strategies for CRPC. Natural compounds have previously shown to be an effective alternative treatment strategy for cancer. Polygodial (PG) an active constituent of mountain pepper belonging to sesquiterpene dialdehyde family has shown to have several pharmacological benefits including anti-bacterial, anti-fungal, anti-inflammatory, and anti-cancer properties. The objective of this study is to determine the therapeutic effects of PG against CRPC in a pre-clinical study. Cell lines used in this study were androgen dependent LNCaP and CRPC C4-2, DU145, and PC-3 cells. MTT, soft agar, and wound healing assays were performed to evaluate the effects of PG respectively on cell survival, anchorage independent growth, and migration characteristics of prostate cancer cells. PC-3 cells were utilized to determine the anti-cancer mechanisms of PG. Cell viability assay results showed PG effectively inhibited cell proliferation of CRPC C4-2, DU145 and PC-3 cell lines as compared to androgen dependent LNCaP cells. PG treatment significantly reduced the colony growth of CRPC cells in soft agar plates as compared to controls which correlates with its inhibitory effect on anchorage independent growth of these cells. In addition, PG also reduced the migration potential of CRPC cells in a wound healing assay. Inhibition of anchorage independent growth and motility of PCa cells by PG suggests its tumor suppressive and anti-metastatic potential. Western blot analysis showed that PG treatment downregulated the expression of a key cell survival molecule, High mobility group box1 (HMGB1) while promoting PARP-1 cleavage in PC-3 cells. Interestingly, our results also showed that BiP/GRP78, a marker of endoplasmic reticulum (ER) stress was upregulated following PG treatment in PC-3 cells. These findings suggest that PG enforces its tumor suppressive action by inhibiting HMGB1 signaling axis with concurrent activation of ER stress pathway in CRPC cells. Taken together, our study shows that PG might be an effective chemotherapeutic natural compound especially for CRPC.

Citation Format: Akshita P. Pillai, Subramanyam Dasari, Bhavani Patel, Souresh Banerjee, Alexander V. Kornienko, Gnanasekar Munirathinam. Polygodial: A potential sesquiterpene dialdehyde for castration-resistant prostate cancer treatment. [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 4804.

The western-type diet induces anti-HMGB1 autoimmunity in Apoe(-/-) mice

BACKGROUND AND AIMS

Anti-HMGB1 autoimmunity plays a role in systemic lupus erythematosus (SLE). Because SLE increases atherosclerosis, we asked whether the same autoimmunity might play a role in atherogenesis.

METHODS

We looked for the induction of HMGB1-specific B and T cell responses by a western-type diet (WTD) in the Apoe(-/-) mouse model of atherosclerosis. We also determined whether modifying the responses modulates atherosclerosis.

RESULTS

In the plasma of male Apoe(-/-) mice fed WTD, the level of anti-HMGB1 antibodies (Abs) was detected at ∼50 μg/ml, which was ∼6 times higher than that in either Apoe(-/-) mice fed a normal chow or Apoe(+/+) mice fed WTD (p ≤ 0.0005). The Abs were directed largely toward a novel, dominant epitope of HMGB1 named HMW4; accordingly, compared with chow-fed mice, WTD-fed Apoe(-/-) mice had more activated HMW4-reactive B and T cells (p = 0.005 and p = 0.01, respectively). Compared with mock-immunized mice, Apoe(-/-) mice immunized with HMW4 along with an immunogenic adjuvant showed proportional increases in anti-HMW4 IgG and IgM Abs, HMW4-reactive B-1 and B-2 cells, and HMW4-reactive Treg and Teff cells, which was associated with ∼30% increase in aortic arch lesions (p ≤ 0.01) by two methods. In contrast, Apoe(-/-) mice immunized with HMW4 using a tolerogenic adjuvant showed preferential increases in anti-HMW4 IgM (over IgG) Abs, HMW4-reactive B-1 (over B-2) cells, and HMW4-specific Treg (over Teff) cells, which was associated with ∼40% decrease in aortic arch lesions (p ≤ 0.03).

CONCLUSIONS

Anti-HMGB1 autoimmunity may potentially play a role in atherogenesis.

Synthetic and Biological Studies of Sesquiterpene Polygodial: Activity of 9-Epipolygodial against Drug-Resistant Cancer Cells

Polygodial, a terpenoid dialdehyde isolated from Polygonum hydropiper L., is a known agonist of the transient receptor potential vanilloid 1 (TRPV1). In this investigation a series of polygodial analogues were prepared and investigated for TRPV1-agonist and anticancer activities. These experiments led to the identification of 9-epipolygodial, which has antiproliferative potency significantly exceeding that of polygodial. 9-Epipolygodial was found to maintain potency against apoptosis-resistant cancer cells as well as those displaying the multidrug-resistant (MDR) phenotype. In addition, the chemical feasibility for the previously proposed mechanism of action of polygodial, involving the formation of a Paal-Knorr pyrrole with a lysine residue on the target protein, was demonstrated by the synthesis of a stable polygodial pyrrole derivative. These studies reveal rich chemical and biological properties associated with polygodial and its direct derivatives. These compounds should inspire further work in this area aimed at the development of new pharmacological agents, or the exploration of novel mechanisms of covalent modification of biological molecules with natural products.

Wittig derivatization of sesquiterpenoid polygodial leads to cytostatic agents with activity against drug resistant cancer cells and capable of pyrrolylation of primary amines

Many types of cancer, including glioma, melanoma, non-small cell lung cancer (NSCLC), among others, are resistant to proapoptotic stimuli and thus poorly responsive to current therapies based on the induction of apoptosis in cancer cells. The current investigation describes the synthesis and anticancer evaluation of unique C12-Wittig derivatives of polygodial, a sesquiterpenoid dialdehyde isolated from Persicaria hydropiper (L.) Delabre. These compounds were found to undergo an unprecedented pyrrole formation with primary amines in a chemical model system, a reaction that could be relevant in the biological environment and lead to the pyrrolation of lysine residues in the target proteins. The anticancer evaluation of these compounds revealed their promising activity against cancer cells displaying various forms of drug resistance, including resistance to proapoptotic agents. Mechanistic studies indicated that compared to the parent polygodial, which displays fixative general cytotoxic action against human cells, the C12-Wittig derivatives exerted their antiproliferative action mainly through cytostatic effects explaining their activity against apoptosis-resistant cancer cells. The possibility for an intriguing covalent modification of proteins through a novel pyrrole formation reaction, as well as useful activities against drug resistant cancer cells, make the described polygodial-derived chemical scaffold an interesting new chemotype warranting thorough investigation.

Abstract 1766: Effects of lovastatin on the PRL-3 cascade of events in prostate cancer

Phosphatase of Regenerating Liver 3 (PRL-3) has recently been demonstrated to play a role in the cellular processes associated with cancer metastasis and has been suggested as a potential new target for cancer therapies. Several pre-clinical evaluations targeting PRL-3 have shown great promise for cancer treatment. Statins are a class of drugs that inhibit 3-hydroxy-3-methyl-glutaryl-CoA reductase (HMGCR) and have been shown to have anti-cancer properties in a variety of cancer types including prostate cancer (PC); previous work has shown that one of the anti-cancer effects of statins is the inhibition of protein prenylation, a post translational modification that allows proteins to associate with the plasma membrane. Prenylation of PRL-3 plays a critical role in cell membrane localization and metastatic process; therefore, targeting PLR-3 prenlyation may be an attractive strategy. In our recent work, we have identified that PRL-3 is highly expressed in aggressive prostate cancer cells and is critical for the motility behavior. Our hypothesis is that lovastatin treatment will reduce the metastatic properties of PC cells by inhibiting prenylation of PRL-3 and therefore reduce the oncogenic effects of the PRL-3 cascade of events required for PC metastasis.

Advanced PC cell line, DU145 was used in this study to characterize PRL-3 function. Cell viability assays showed that lovastatin has dose dependent effects on DU145. Western Blot analysis was then used to analyze expression levels of PRL-3 and its downstream proteins in DU145 cells treated with lovastatin. Cellular localization of PRL-3 following lovastatin treatments was also conducted using Western blot analysis. Following this, migration assays were performed using Boyden chamber to determine whether lovastatin has anti-migration effects in PC cells. Immunoprecipitation (IP) analyses were also performed to determine whether PRL-3 and Translationally Controlled Tumor Protein (TCTP) [a mediator of PRL-3 function] are binding partners using respective antibodies.

Our studies have shown lovastatin decreases the expression of PRL-3 resulting in the inhibition of DU145 cell proliferation; furthermore, a reduction in TCTP expression has also been observed in treated cells versus control cells. Specifically, lovastatin decreases the membrane localization of both PRL-3 and TCTP in DU145 cells. Moreover, IP results show that PRL-3 and TCTP are potential binding partners and this interaction may be critical for PC metastasis. Finally our results show that lovastatin has the ability to decrease the motility of DU145 PC cells in vitro. Taken together, our results for the first time show that lovastatin can target PRL-3 by interfering with prenylation and preventing the membrane location of PRL-3 and its downstream effector, TCTP in advanced prostate cancer cells. Targeting PRL-3 warrants further studies to develop PRL-3 as a therapeutic target for PC.

Citation Format: Allison K. Palmer, Gnanasekar Munirathinam. Effects of lovastatin on the PRL-3 cascade of events 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 1766. doi:10.1158/1538-7445.AM2015-1766

Abstract 5484: Dehydroleucodine: A potential sesquiterpene lactone for targeting castration-resistant prostate cancer

Prostate cancer (PCa) patients undergoing standard androgen deprivation therapy eventually develop aggressive castration-resistant prostate cancer (CRPC) for which there is no effective treatment currently available. Hence, there is an urgent need to identify effective treatment strategy for lethal CRPC. Previous studies have shown naturally occurring sesquiterpene lactones (SLs) are promising anti-cancer agents and few SLs are under clinical trials for cancer treatment. Evaluation of additional SLs may prove to be valuable as an adjunct or stand alone treatment especially for CRPC. Dehydroleucodine (DhL), a sesquiterpene lactone isolated from Artemisia douglasiana has several pharmacological benefits such as anti-inflammatory, anti-ulcer and anti-oxidant effects. However, the anti-cancer effects of DhL are not well known. In this study, we have evaluated the effects of DhL against castration-sensitive (LNCaP) and CRPC (PC-3) cells in a pre-clinical study. Our cell viability assay results showed that DhL had pronounced inhibition on PC-3 cell proliferation compared to that of LNCaP cells. Therefore, our subsequent studies focussed on elucidating the effects and mechanism of action of DhL using PC-3 CRPC cells. Our investigations showed that in addition to inhibiting the cell proliferation of PC-3 cells, DhL also abrogated the clonogenic potential of PC-3 cells by activating apoptotic markers such as caspase-3 and PARP-1 and cell cycle inhibitors p21 and p27 respectively. Furthermore, our mechanistic study has identified DhL downregulates the expression of NF-kB (p65) in PC-3 cells which may be contributing to the anti-cancer effects of DhL in these cells. Interestingly, our studies also showed that DhL inhibited the osteoclastogenesis mediated by PC-3 in vitro as determined by tartarate-resistant acid phosphatase (TRAP) assay suggesting that DhL may be beneficial in preventing the bone destruction caused by metastatic CRPC. Taken together, our study warrants further investigation of DhL as a promising natural agent for effective treatment and management of CRPC.

Citation Format: Souresh Banerjee, Gnanasekar Munirathinam. Dehydroleucodine: A potential sesquiterpene lactone for targeting castration-resistant prostate cancer. [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 5484. doi:10.1158/1538-7445.AM2014-5484

Cutting edge: Dexamethasone potentiates the responses of both regulatory T cells and B-1 cells to antigen immunization in the ApoE(-/-) mouse model of atherosclerosis

The immunosuppressant dexamethasone was shown to preferentially deplete CD4+ effector T cells while sparing regulatory T cells (Tregs) in vivo. In the current study, we show that it also preferentially depletes B-2 cells while sparing B-1 cells. In the ApoE(-/-) mouse model of atherosclerosis, in which both Tregs and B-1 cells are thought to play an atheroprotective role, we show that HSP60-targeted immunization in the presence of dexamethasone raises Ag-reactive Tregs and B-1 cells concomitantly and reduces the severity of atherosclerosis. These results indicate that dexamethasone is an adjuvant that potentiates both the Treg and B-1 responses to immunogens. This study shows that B-1 cells with a specificity for a disease-relevant Ag can be raised in vivo by immunization.

HMGB1 in hormone-related cancer: a potential therapeutic target

High-mobility group box 1 (HMGB1) is a dynamic nuclear protein participating in transcription, chromatin remodelling, and DNA recombination and repair processes. Accumulating evidence indicates that its function now extends beyond the nucleus, notably its extracellular role in inflammation. HMGB1 is implicated as a late mediator of sepsis and is also believed to promote atherosclerosis and other inflammatory diseases such as rheumatoid arthritis and systemic lupus erythematosus. Interestingly, deregulation of HMGB1 is shown to be associated with the hallmarks of cancer development. Moreover, several clinical studies have shown that HMGB1 is a promising biomarker for a variety of cancer types. In this review, we provide novel insights into the role and mechanisms of HMGB1, in particular, to hormone-related cancers and its potential to serve as a therapeutic target.

Large extracellular loop of tetraspanin as a potential vaccine candidate for filariasis

Lymphatic filariasis affects nearly 120 million people worldwide and mass preventive chemotherapy is currently used as a strategy to control this infection. This has substantially reduced the incidence of the infection in several parts of the world. However, a prophylactic vaccine would be more effective in preventing future infections and will supplement the mass chemotherapy efforts. Unfortunately, there is no licensed vaccine available currently to prevent this infection. Molecules expressed on the surface of the parasite are potential candidates for vaccine development as they are exposed to the host immune system. In this study we show that the large extracellular loop of tetraspanin (TSP LEL), a protein expressed on the cuticle of Brugia malayi and Wuchereria bancrofti is a potential vaccine candidate. Our results showed that BmTSP LEL is expressed on the surface of B. malayi infective third stage larvae (L3) and sera from human subjects who are putatively immune to lymphatic filariasis carry high titer of IgG1 and IgG3 antibodies against BmTSP LEL and WbTSP LEL. We also showed that these antibodies in the sera of human subjects can participate in the killing of B. malayi L3 in an antibody dependent cell-mediated cytotoxicity mechanism. Vaccination trials in mice showed that close to 64% protection were achieved against challenge infections with B. malayi L3. Immunized animals showed high titer of anti-WbTSP LEL IgG1, IgG2a and IgG2b antibodies in the sera and IFN-γ secreting cells in the spleen. Onchocerca volvulus another filarial parasite also expresses TSP LEL. Cross-reactivity studies showed that IgG1 antibody in the sera of endemic normal subjects, recognize OvTSP LEL. Similarly, anti-OvTSP LEL antibodies in the sera of subjects who are immune to O. volvulus were also shown to cross-react with rWbTSP LEL and rBmTSP LEL. These findings thus suggested that rTSP LEL can be developed as a potential vaccine candidate against multiple filarial infections.