Novel Pomegranate-Nanoparticles Ameliorate Cisplatin-Induced Nephrotoxicity and Improves Cisplatin Anti-Cancer Efficacy in Ehrlich Carcinoma Mice Model.

Cisplatin (CISP) is one of the most widely used anti-cancer chemotherapeutic agents with remarkable efficacy against various types of cancers. However, it has been associated with nephrotoxicity amongst other undesirable side effects. Pomegranate (PE) is a potent antioxidant and anti-inflammatory agent effective against cancer, with a superior benefit of not being associated with the common toxicities related to the use of conventional chemotherapeutic agents. However, the application of PE is limited by its reduced solubility and decreased bioavailability. We investigated the potential of a novel nanoparticle (NP) enclosing PE to enhance its solubility and improve its bioavailability, and efficacy to prevent CISP-associated nephrotoxicity in a mice model of Ehrlich solid carcinoma (ESC). All mice were grouped into four cohorts: (I) control, (II) tumor, (III) CISP, and (IV) CISP + PE-NPs. The data obtained demonstrated that PE-NPs was beneficial in potently ameliorating CISP-induced nephrotoxicity in ESC mice. PE-NPs significantly attenuated CISP-induced oxidative stress and lipid peroxidation in the kidney via improving activities of antioxidants (SOD, GSH, and CAT). Additionally, PE-NPs considerably decreased CISP-induced inflammation in the kidney by decreasing the levels of NF-kB, IL-1ß, and TNF-α. Notably, PE-NPs did not assuage the antitumor efficacy of CISP as revealed by histological assessment and tumor weight data. In summary, PE-NPs may be a potent alternative anticancer therapy devoid of nephrotoxicity.

Novel oral nano-hepatic targeted anti-PCSK9 in hypercholesterolemia.

Proprotein convertase subtilisin/kexin type 9 is a protease enzyme secreted by liver that downregulates hepatic low-density lipoprotein receptor (LDLR) by binding and chaperoning LDLR to lysosomes for degradation, causing hypercholesteremia. The development of anti-PCSK9 therapeutics attracted considerable attention for the management of cardiovascular disease risk. However, only subcutaneous injectable PCSK9 monoclonal antibodies have been FDA approved. Oral administration of small-molecule PCSK9 inhibitors has the potential to become a practical therapeutic option if achievable. In the present work, we used nanotechnological approaches to develop the first small oral molecule nano-hepatic targeted anti-PCSK9. Using high-throughput optimization and a series of evaluations, a stable water-dispersible 150-200 nm nano-encapsulated drug (named P-4) conjugated with hepatic targeting moiety was synthesized and characterized (named P-21). Pharmacodynamic (PD), pharmacokinetic (PK) and bioavailability studies were conducted using a high fat diet nutritionally induced hypercholesterolemia mouse model to evaluate the efficacy of P-21 as an anti-PCSK9 LDL-cholesterol lowering hepatic targeted nanodrug. The PD results demonstrate that P-21 in a dose-dependent manner is highly effective in lowering LDL-C by 50-90%. PK results show the maximum plasma concentration (Cmax) of P-4 was observed after 30 min of administration with 31% oral bioavailability and had a sustained longer half-life up to 24 h. In vivo safety studies in rats showed no apparent adverse effects, normal chemical biomarkers and normal histopathological findings in all P-21 treated groups at different escalating doses. Compared to the FDA-approved monoclonal antibodies, P-21 offers a more efficient, and practical treatment protocol for targeting uncontrolled hypercholesterolemia in reducing the risk of cardiovascular diseases. The present study introduced a nano-targeted drug delivery approaches for PCSK9/LDLR antagonist.

A Novel Nanoformulation of Ellagic Acid is Promising in Restoring Oxidative Homeostasis in Rat Brains with Alzheimer's Disease.

BACKGROUND: Aluminum toxicity induces neurodegenerative changes in the brain and results in Alzheimer's disease (AD). OBJECTIVE: Here, the aim was to evaluate the antioxidant therapeutic effects of ellagic acid (EA) and EA-loaded nanoparticles (EA-NP) in an aluminum chloride-induced AD rat model. METHODS: The nanoparticles' loading of EA was 0.84/1 w/w. The in vitro release kinetics of EA from EA-NP in fetal bovine serum showed 60% release in the first 1-5 hours, followed by sustained release at 60-70% over 6-24 hours. Six groups were implemented; group 1 served as the control, group 2 received EA, group 3 received EA-NP, group 4 was the AD rat model administered AlCl3 (50 mg/kg) for 4 weeks, groups 5 (AD+EA) and 6 (AD+EA-NP) were treated with EA and EA-NP, respectively, for 2 weeks after AlCl3 was stopped. The neurotoxicity in the rat brain was examined by measuring the brain antioxidant biomarkers catalase, glutathione, and total antioxidant activity and lipid peroxidation (thiobarbituric acid, TBA). Histopathological studies using hematoxylin and eosin, cresyl violet, silver stains, and the novel object recognition test were examined. RESULTS: Data revealed significant increase of antioxidant biomarkers and decreased TBA in the EA-NP group. The pathological hallmarks of AD-vacuolation of the neurons, chromatolysis, neurofibrillary tangles, and the senile plaques in brains of the AD rat model were decreased and restoration of Nissl granules was noted. The calculated discrimination index in the behavioral test increased more in cases treated with EA-NP. CONCLUSION: The treatment of AD with EA-NP was more effective than EA in alleviating the oxidative neurotoxic effects on AD rat brains.

The potential role of pomegranate and its nano-formulations on cerebral neurons in aluminum chloride induced Alzheimer rat model.

The oxidative stress leading to degenerative changes in the brain of Alzheimer's disease (AD) is evident. Our aim was to evaluate the therapeutic and protective effects of pomegranate extract (PE) and pomegranate extract-loaded nanoparticles (PE nano) in an AlCl 3-induced AD rat model. Nanoparticles were synthesized with a PE load of 0.68% w/w, and 70 male Wistar rats were divided into 7 groups: Group I was the control, Group II received PE., Group III received PE nano for 2 weeks, Group IV received AlCl 3 (50 mg/kg) daily orally for 4 weeks, Group V received PE for 2 weeks, Group VI received PE nano for 2 weeks, and Groups V and VI were started after AlCl 3 administration was stopped. Group VII received PE for 2 weeks and was stopped before AlCl 3 was administered. The Results revealed that the discrimination index in the novel object recognition test was the least in AD rat model but increased in cases protected with PE treated with PE nano. Similar results were shown based on calculating the brain weight/body weight percent. The biomarkers of antioxidant activity (catalase, glutathione and total antioxidant activity) in brain homogenate were significantly increased in groups treated with either PE or PE nano. The thiobarbituric acid reactive substance measured to estimate lipid peroxidation was significantly increased in AD rat model and decreased in groups protected with PE or treated with PE nano. Histopathological studies using hematoxylin and eosin, cresyl violet, and silver stains revealed hyaline degeneration, chromatolysis, and hallmarks of AD; neurofibrillary tangles and the senile plaques in brains of AD rat model. Restoration of the histological architecture, Nissl granules, and minimal appearance of hallmarks of AD characterized brains treated with PE or PE nano. In conclusion, PE was more effective as a protectant than a therapeutic measure in alleviating the antioxidant, lipid peroxidative effects and histopathological hallmarks in AD brains. But, the therapeutic PE-loaded nanoparticles increased the efficacy of active components and produced similar results as the protective PE.

Functionalized nano-targeted moieties in management of prostate cancer.

Multimodal properties of nanoparticles, such as simultaneously carrying drugs and/or diagnostic probes for site-specific delivery, make them excellent carriers for diagnosis and treatment of prostate cancer. Advantages are high permeability and selectivity to malignant cells to reduce systemic toxicity of chemotherapeutic drugs. Based on a review of current literature, the lack of efficient and highly specific prostate cancer cell targeting moieties is hindering successful in vivo prostate cancer-targeted drug delivery systems. Highly specific nano-targeting moieties as drug delivery vehicles might improve chemotherapeutic delivery via targeting to specific receptors expressed on the surface of prostate cancer cells. This review describes nano-targeting moieties for management of prostate cancer and its cancer stem cells. Descriptions of targeting moieties using anti-prostate-specific membrane antigen, aptamer, anti-cluster of differentiation 24/44, folic acid and other targeting strategies are highlighted. Current research results are promising and may yield development of next-generation nanoscale theragnostic targeted modalities for prostate cancer treatment.

αvß3 Integrin Antagonists Enhance Chemotherapy Response in an Orthotopic Pancreatic Cancer Model.

Pancreatic cancer decreases survival time and quality of life because of drug resistance and peripheral neuropathy during conventional treatment. This study was undertaken to investigate whether αvß3 integrin receptor antagonist compounds NDAT and XT199 can suppress the development of cisplatin resistance and cisplatin-induced peripheral neuropathy in an orthotopic pancreatic SUIT2-luc cancer cell mouse model. Anticancer effects of these compounds and their combination with cisplatin were assessed in this tumor mouse model with bioluminescent signaling and histopathology, and a cytokine assay was used to examine expression of inflammatory cytokines IL-1ß, IL-6, IL-10, and TNF-α from plasma samples. To determine the neuroprotective effects of the compounds on cisplatin-induced peripheral neuropathy, behavioral hind-limb posture of the mice was evaluated. The combination therapy of NDAT or XT199 with cisplatin elicited greater inhibition of tumor growth and increased tumor necrosis compared to cisplatin alone. NDAT and XT199 in combination with cisplatin significantly decreased expression of pro-inflammatory cytokines IL-1ß, IL-6, and TNF-α and significantly increased expression of anti-inflammatory cytokine IL-10 in comparison to cisplatin alone. Cisplatin-treated groups showed stocking-glove hind-limb posture, whereas NDAT and XT199 with cisplatin-treated groups displayed normal hind-limb posture. Results clearly suggest that NDAT and XT199 treatment with cisplatin that inactivates NF-κB may contribute to increased antitumor and anti-inflammatory efficacy as well as alleviate cisplatin-mediated loss of motor function in this pancreatic tumor mouse model.

Viramidine-Loaded Galactosylated Nanoparticles Induce Hepatic Cancer Cell Apoptosis and Inhibit Angiogenesis.

Current estimates indicate that hepatocarcinoma is the leading cause of death globally. There is interest in utilizing nanomedicine for cancer therapy to overcome side effects of chemo-interventions. Ribavirin, an antiviral nucleoside inhibitor, accumulates inside red blood cells, causing anemia. Its analog, viramidine, can concentrate within hepatocytes and spare red blood cells, thus limiting anemia. Hepatocarcinoma cells have a large number of asialoglycoprotein receptors on their membranes that can bind galactosyl-terminating solid lipid nanoparticles (Gal-SLN) and internalize them. Here, viramidine, 5-fluorouracil, and paclitaxel-loaded Gal-SLN were characterized inside cells. Cytotoxicities of free-drug, nano-void, and drug-loaded Gal-SLN were evaluated using HepG2 cells; over 3 days, cell viability was measured. To test the mechanistic pathway, we investigated in vitro apoptosis using flow cytometry and in ovo angiogenesis using the CAM assay. Results showed that 1 and 2 µM of the viramidine-encapsulated Gal-SLN had the highest cytotoxic effect, achieving 80% cell death with a steady increase over 3 days, with induction of apoptosis and reduction of necrosis and angiogenesis, compared to free-drugs. Gal-SLN application on breast cancer MCF-7 cells confirmed its specificity against liver cancer HepG2 cells. We conclude that viramidine-encapsulated Gal-SLN has anticancer and anti-angiogenic activities against hepatocarcinoma.

Triazole Modified Tetraiodothyroacetic Acid Conjugated to Polyethylene Glycol: High Affinity Thyrointegrin αvß3 Antagonist with Potent Anticancer Activities in Glioblastoma Multiforme.

Discovery of bioactive molecules that target integrins has implicated their role in tumor angiogenesis, tumor growth, metastasis, and other pathological angiogenesis processes. Integrins are members of a family of cell surface receptors that play a critical role in the angiogenesis process. Tetraiodothyroacetic acid (tetrac), a deaminated derivative of l-thyroxine (T4), is a "thyrointegrin" antagonist that blocks the actions of l-triiodothyronine (T3) and T4 with an interaction site that is located at or near the RGD recognition site identified on integrin αvß3's binding pocket (thyrointegrin αvß3 receptors). We have enhanced the biological activity of a tetrac-based inhibitor via significantly improving its αvß3 receptor binding affinity by introducing a triazole ring on the outer ring of tetrac and covalently conjugating to polymer to increase the product's hydrophilicity via PEGylation. The product, P-bi-TAT, was restricted from nuclear translocation and demonstrated high blood brain barrier permeability and retention in contrast to the non-PEG conjugated derivative. Results of biological activity indicated that this macromolecule new chemical entity P-bi-TAT has greater than 400-fold potent integrin αvß3 affinity versus the parent compound tetrac and has potent anticancer/anti-angiogenesis efficacy against glioblastoma multiforme (GBM). P-bi-TAT administered subcutaneously once daily for 21 days at 1-10 mg/kg mouse body weight resulted in a dose-dependent suppression of GBM tumor growth and viability as monitored with IVIS imaging (P < 0.001). GBM tumors had >95% volume loss and maximal loss of GBM cell viability during the 21 days ON-treatment experiment as well as in the 21 days ON followed by 21 days OFF-treatment experiment (P < 0.001). In conclusion, P-bi-TAT is a promising lead clinical candidate effective in the treatment of human GBM.

Novel Targeted Nano-Parthenolide Molecule against NF-kB in Acute Myeloid Leukemia.

The targeted nano-encapsulation of anticancer drugs can improve drug delivery and the selective targeting of cancer cells. Nuclear factor kappa B (NF-kB) is a regulator for different biological responses, including cell proliferation and differentiation. In acute myeloid leukemia (AML), constitutive NF-κB has been detected in more than 50% of cases, enabling leukemic cells to resist apoptosis and stimulate uncontrolled proliferation. We evaluated NF-kB expression in bone marrow samples from 103 patients with AML using quantitative real time polymerase chain reaction (RT-PCR) and found that expression was increased in 80.5% (83 out 103) of these patients with AML in comparison to the control group. Furthermore, overexpressed transmembrane glycoprotein (CD44) on leukemic cells in comparison to normal cells is known to play an important role in leukemic cell engraftment and survival. We designed poly lactide co-glycolide (PLGA) nanoparticles conjugated with antiCD44 and encapsulating parthenolide (PTL), a nuclear factor kappa B (NF-kB) inhibitor, in order to improve the selectivity and targeting of leukemic cells and to spare normal cells. In vitro, in leukemic cell lines Kasumi-1, KG-1a, and THP-1, proliferation was decreased by 40% (** p < 0.01) with 5 µM PLGA-antiCD44-PTL nanoparticles in comparison to the same concentration of free PTL (~10%). The higher uptake of the nanoparticles by leukemic cells was confirmed with confocal microscopy. In conclusion, PLGA-antiCD44-PTL nanoparticles improved the bioavailability and selective targeting of leukemic cells, thus holding promise as a drug delivery system to improve the cure rate of AML.

Pharmacokinetics, Biodistribution, and Anti-Angiogenesis Efficacy of Diamino Propane Tetraiodothyroacetic Acid-conjugated Biodegradable Polymeric Nanoparticle.

The anti-angiogenic agent, diamino propane tetraiodothyroacetic acid (DAT), is a thyro-integrin (integrin αvß3) antagonist anticancer agent that works via genetic and nongenetic actions. Tetraiodothyroacetic acid (tetrac) and DAT as thyroid hormone derivatives influence gene expression after they transport across cellular membranes. To restrict the action of DAT to the integrin αvß3 receptors on the cell surface, we used DAT-conjugated PLGA nanoparticles (NDAT) in an active targeting mode to bind to these receptors. Preparation and characterization of NDAT is described, and both in vitro and in vivo experiments were done to compare DAT to NDAT. Intracellular uptake and distribution of DAT and NDAT in U87 glioblastoma cells were evaluated using confocal microscopy and showed that DAT reached the nucleus, but NDAT was restricted from the nucleus. Pharmacokinetic studies using LC-MS/MS analysis in male C57BL/6 mice showed that administration of NDAT improved the area under the drug concentration curve AUC(0-48 h) by 4-fold at a dose of 3 mg/kg when compared with DAT, and Cmax of NDAT (4363 ng/mL) was 8-fold greater than that of DAT (548 ng/mL). Biodistribution studies in the mice showed that the concentrations of NDAT were higher than DAT/Cremophor EL micelles in heart, lung, liver, spleen, and kidney. In another mouse model using female NCr nude homozygous mice with U87 xenografts, tumor growth was significantly decreased at doses of 1 and 3 mg/kg of NDAT. In the chick chorioallantoic membrane (CAM) assay used to measure angiogenesis, DAT (500 ng/CAM) resulted in 48% inhibition of angiogenesis levels. In comparison, NDAT at low dose (50 ng/CAM) showed 45% inhibition of angiogenesis levels. Our investigation of NDAT bridges the study of polymeric nanoparticles and anti-angiogenic agents and offers new insight for the rational design of anti-angiogenic agents.

Chitosan-based nanoformulated (-)-epigallocatechin-3-gallate (EGCG) modulates human keratinocyte-induced responses and alleviates imiquimod-induced murine psoriasiform dermatitis.

BACKGROUND: Psoriasis is a chronic and currently incurable inflammatory skin disease characterized by hyperproliferation, aberrant differentiation, and inflammation, leading to disrupted skin barrier function. The use of natural agents that can abrogate these effects could be useful for the treatment of psoriasis. Earlier studies have shown that treatment of keratinocytes and mouse skin with the green tea polyphenol (-)-epigallocatechin-3-gallate (EGCG) mitigated inflammation and increased the expression of caspase-14 while promoting epidermal differentiation and cornification. However, bioavailability issues have restricted the development of EGCG for the treatment of psoriasis. MATERIALS AND METHODS: To overcome these limitations, we employed a chitosan-based polymeric nanoparticle formulation of EGCG (CHI-EGCG-NPs, hereafter termed nanoEGCG) suitable for topical delivery for treating psoriasis. We investigated and compared the efficacy of nanoEGCG versus native or free EGCG in vitro and in an in vivo imiquimod (IMQ)-induced murine psoriasis-like dermatitis model. The in vivo relevance and efficacy of nanoEGCG formulation (48 µg/mouse) were assessed in an IMQ-induced mouse psoriasis-like skin lesion model compared to free EGCG (1 mg/mouse). RESULTS: Like free EGCG, nanoEGCG treatment induced differentiation, and decreased proliferation and inflammatory responses in cultured keratinocytes, but with a 4-fold dose advantage. Topically applied nanoEGCG elicited a significant (p<0.01) amelioration of psoriasiform pathological markers in IMQ-induced mouse skin lesions, including reductions in ear and skin thickness, erythema and scales, proliferation (Ki-67), infiltratory immune cells (mast cells, neutrophils, macrophages, and CD4+ T cells), and angiogenesis (CD31). We also observed increases in the protein expression of caspase-14, early (keratin-10) and late (filaggrin and loricrin) markers of differentiation, and the activator protein-1 factor (JunB). Importantly, a significant modulation of several psoriasis-related inflammatory cytokines and chemokines was observed compared to the high dose of free EGCG (p<0.05). Taken together, topically applied nanoEGCG displayed a >20-fold dose advantage over free EGCG. CONCLUSION: Based on these observations, our nanoEGCG formulation represents a promising drug-delivery strategy for treating psoriasis and possibly other inflammatory skin diseases.

Taribavirin and 5-Fluorouracil-Loaded Pegylated-Lipid Nanoparticle Synthesis, p38 Docking, and Antiproliferative Effects on MCF-7 Breast Cancer.

PURPOSE: Breast cancer is the second most common cause of mortality in women in the United States. Targeted delivery of antitumor breast cancer drugs as a drug-delivery strategy may allow direct delivery into the tumor. Currently, chemotherapy is one of the principle strategies for cancer treatment, but it can have toxic side effects. Nanotechnology attempts to resolve these challenges by loading drugs in nanoparticles, such as solid lipid nanoparticles (SLN). In response to the breast cancer drug 5-fluorouracil (5-FU), p38MAPK signaling has been investigated since the 1990s. Ribavirin, a nucleotide derivative, inhibits p38MAPK in infected hepatocytes. A ribavirin prodrug, taribavirin (TBV), was recently synthesized to concentrate in the liver and have minimal concentration in red blood cells. METHODS: In this study, TBV and 5-FU-pegylated SLNs were prepared and characterized. The in vitro cytotoxicity was evaluated against MCF-7 breast cancer cells. Using molecular docking experiments, 5-FU and TBV were docked on p38MAPK protein. RESULTS: The TBV nanoformulation had the highest cytotoxic effects, achieving IC50 = 0.690 µM after 24 h, compared with free TBV, which also achieved a good cytotoxic effect (IC50 = 0.756 µM). However, there was a detectable cytotoxic effect and an undetectable IC50 of 5-FU nanoparticles and free 5-FU on MCF-7 cells. CONCLUSIONS: The effect of TBV nanoparticles on MCF-7 cells may be due to its inhibitory effect against p38MAPK protein, where it fits inside the active pocket site of the p38 protein molecular surface, with a minimum binding affinity of -5.5 kcal/mol (rmsd of 1.07), and it formed strong hydrogen bonds with amino acids ASP'168, ILE'166, HIS'148, and ILE'147. Further studies are warranted to investigate the mechanistic details of the proposed approach.

Particle coatings but not silver ions mediate genotoxicity of ingested silver nanoparticles in a mouse model.

Incorporation of silver nanoparticles (AgNPs) in toothpaste, food containers, dietary supplements and other consumer products can result in oral exposure to AgNPs and/or silver ions (Ag+) released from the surface of AgNPs. To examine whether ingestion of AgNPs or Ag+ results in genotoxic damage and whether AgNP coatings modulate the effect, we exposed mice orally to 20 nm citrate-coated AgNPs, polyvinylpyrrolidone (PVP)-coated AgNPs, silver acetate or respective vehicles at a 4 mg/kg dose (equivalent to 800x the EPA reference dose for Ag) for 7 days. Genotoxicity was examined in the systemic circulation and bone marrow at 1, 7, and 14 days post-exposure. We found that citrate-coated AgNPs induced chromosomal damage in bone marrow and oxidative DNA damage and double strand breaks in peripheral blood. These damages persisted for at least 14 days after exposure termination. Because oxidative DNA damage and strand breaks are repaired rapidly, their presence after exposure cessation indicates that citrate-coated AgNPs persist in the body. In contrast, PVP-coated AgNPs and silver acetate did not induce DNA or chromosomal damage at any time point measured. To determine whether coating-dependent genotoxicity is related to different AgNP changes in the gastrointestinal tract, we examined AgNP behavior and fate in an in vitro gastrointestinal digestion model using UV-visible spectroscopy and DLS. Citrate-coated AgNPs were more susceptible to agglomeration than PVP-coated AgNPs in digestive juices with or without proteins. In summary, AgNPs but not Ag+ are genotoxic following oral ingestion. Nanoparticle coatings modulate gastrointestinal transformation and genotoxicity of AgNPs, where higher agglomeration of AgNPs in gastrointestinal juices is associated with higher genotoxicity in tissues. Since genotoxicity is a strong indicator of cancer risk, further long-term studies focusing on cancer are warranted.

Nanoparticulate Tetrac Inhibits Growth and Vascularity of Glioblastoma Xenografts.

Thyroid hormone as L-thyroxine (T4) stimulates proliferation of glioma cells in vitro and medical induction of hypothyroidism slows clinical growth of glioblastoma multiforme (GBM). The proliferative action of T4 on glioma cells is initiated nongenomically at a cell surface receptor for thyroid hormone on the extracellular domain of integrin αvß3. Tetraiodothyroacetic acid (tetrac) is a thyroid hormone derivative that blocks T4 action at αvß3 and has anticancer and anti-angiogenic activity. Tetrac has been covalently bonded via a linker to a nanoparticle (Nanotetrac, Nano-diamino-tetrac, NDAT) that increases the potency of tetrac and broadens the anticancer properties of the drug. In the present studies of human GBM xenografts in immunodeficient mice, NDAT administered daily for 10 days subcutaneously as 1 mg tetrac equivalent/kg reduced tumor xenograft weight at animal sacrifice by 50%, compared to untreated control lesions (p < 0.01). Histopathological analysis of tumors revealed a 95% loss of the vascularity of treated tumors compared to controls at 10 days (p < 0.001), without intratumoral hemorrhage. Up to 80% of tumor cells were necrotic in various microscopic fields (p < 0.001 vs. control tumors), an effect attributable to devascularization. There was substantial evidence of apoptosis in other fields (p < 0.001 vs. control tumors). Induction of apoptosis in cancer cells is a well-described quality of NDAT. In summary, systemic NDAT has been shown to be effective by multiple mechanisms in treatment of GBM xenografts.

Downregulation of Bmi1 in breast cancer stem cells suppresses tumor growth and proliferation.

Targeting cancer stem cells during initial treatment is important to reduce incidence of recurrent disease. Bmi1 has been associated with cancer stem cell self-renewal and aggressive disease. The purpose of this study was to determine the effects of downregulation of Bmi1 in breast cancer stem cells in order to target and eliminate the stem cell population in the tumor mass. Bmi1 was downregulated using two approaches in the mouse breast cancer stem cell line FMMC 419II-a small molecule inhibitor (PTC 209) and stable transfection with a Bmi1 shRNA plasmid. The functional effect of Bmi1 downregulation was tested in vitro and in vivo. Each approach led to decreased Bmi1 expression that correlated with an inhibition of cancer stem cell properties in vitro including cell cycle arrest and reduced mammosphere forming potential, and a decrease in tumor mass in vivo after either intra-tumoral or systemic nanoparticle-targeted delivery of anti-Bmi1. These results show that inhibiting Bmi1 expression in breast cancer stem cells could be important for the complete elimination of tumor and potentially preventing disease relapse.