Jamboor K. Vishwanatha

Significant differences in global genomic DNA methylation by gender and race/ethnicity in peripheral blood

Reduced levels of global DNA methylation are associated with genomic instability and are independent predictors of cancer risk. Little is known about the environmental determinants of global DNA methylation in peripheral blood. We examined the association between demographic and lifestyle factors and levels of global leukocyte DNA methylation in 161 cancer-free subjects enrolled in the North Texas Healthy Heart Study aged 45–75 years in 2008. We used in-person interviews for demographics and lifestyle factors, a self-administrated Block food frequency questionnaire for diet, and bioelectrical impedance analysis and CT-scan for body composition. We measured genomic DNA methylation using bisulfite conversion of DNA and pyrosequencing for LINE-1. Body composition measures including body mass index, waist circumference, areas of subcutaneous fat and visceral fat, percent of fat mass and fat-free mass were not associated with global genomic DNA methylation after controlling the effect of age, gender and race/ethnicity. Instead, female gender was significantly associated with a reduced level of global methylation (β = -2.77, 95% CI: -4.33, -1.22). Compared to non-Hispanic whites, non-Hispanic blacks (β = -2.02, 95% CI: -3.55, -0.50) had significantly lower levels of global methylation. No association was found with age, cigarette smoking, alcohol drinking and dietary intake of nutrients in one-carbon metabolism. Global leukocyte DNA methylation differs by gender and race/ethnicity, suggesting these variables need to be taken into consideration in studies of global DNA methylation as an epigenetic marker for cancer.

Visceral fat, waist circumference, and BMI: impact of race/ethnicity.

Objective: BMI and waist circumference are used to define risk from excess body fat. Limited data in women suggest that there may be racial/ethnic differences in visceral adipose tissue (VAT) at a given BMI or waist circumference. This study tested the hypothesis that racial/ethnic differences exist in both men and women in the relationship of anthropometric measures of body composition and computed tomography (CT)‐determined VAT or subcutaneous adipose tissue (SAT).

Physical activity and global genomic DNA methylation in a cancer-free population

Changes in DNA methylation may represent an intermediate step between the environment and human diseases. Little is known on whether behavioral risk factors may modify gene expression through DNA methylation. To assess whether DNA methylation is associated with different levels of physical activity, we measured global genomic DNA methylation using bisulfite converted DNA and real time PCR (MethyLight) for LINE-1 in peripheral blood of 161 participants aged 45-75 years enrolled in the North Texas Healthy Heart Study and levels of physical activity using an accelerometer (Actigraph GT1M Monitor). We found that individuals with physical activity 26-30 min/day had a significantly higher level of global genomic DNA methylation compared to those with physical activity ≤ 10 min/day (β=2.52, 95%CI: 0.70, 4.35) However, the association was attenuated and became statistically insignificant after multivariate adjustment (β=1.24, 95%CI:-0.93, 3.40). There were some suggestions of a positive association between physical activity and global genomic DNA methylation in non-Hispanics (β=1.50, 95%CI: -0.08, 3.08) that warrants further investigation.

Alendronate coated poly-lactic-co-glycolic acid (PLGA) nanoparticles for active targeting of metastatic breast cancer

Delivery of therapeutic agents to bone is crucial in several diseases such as osteoporosis, Pagets disease, myeloproliferative diseases, multiple myeloma as well as skeletal metastasizing cancers. Prevention of cancer growth and lowering the cancer induced bone resorption is important in the treatment of bone metastasizing cancers. Keeping in mind the low diffusivity and availability of cell surface targets on cancer cells, we designed a targeted system to deliver chemotherapeutic agents to the bone microenvironment as an approach to tissue targeting using alendronate (Aln). We co-encapsulated curcumin and bortezomib in the PLGA nanoparticles to further enhance the therapeutic efficiency and overall clinical outcome. These multifunctional nanoparticles were characterized for particle size, morphology and drug encapsulation. The particles were spherical with smooth surface and had particle size of 235 ± 70.30 nm. We validated the bone targeting ability of these nanoparticles in vitro. Curcumin and bortezomib are known to have synergistic effect in inhibition of growth of cancer; however there was no synergism in the anti-osteoclastogenic activity of these agents. Surprisingly, curcumin by itself had significant inhibition of osteclastogenic activity. In vivo non-invasive bioimaging showed higher localization of Aln-coated nanoparticles to the bone compared to control groups, which was further confirmed by histological analysis. Aln-coated nanoparticles protected bone resorption and decreased the rate of tumor growth as compared to control groups in an intraosseous model of bone metastasis. Our data show efficient attachment of Aln on the surface of nanoparticles which could be used as a drug carrier for preferential delivery of multiple therapeutic agents to bone microenvironment.

Lipid Raft Endocytosis and Exosomal Transport Facilitate Extracellular Trafficking of Annexin A2

Annexin A2 (AnxA2), a Ca2+-dependent phospholipid-binding protein, is known to associate with the plasma membrane and the endosomal system. Within the plasma membrane, AnxA2 associates in a Ca2+dependent manner with cholesterol-rich lipid raft microdomains. Here, we show that the association of AnxA2 with the lipid rafts is influenced not only by intracellular levels of Ca2+ but also by N-terminal phosphorylation at tyrosine 23. Binding of AnxA2 to the lipid rafts is followed by the transport along the endocytic pathway to be associated with the intralumenal vesicles of the multivesicular endosomes. AnxA2-containing multivesicular endosomes fuse directly with the plasma membrane resulting in the release of the intralumenal vesicles into the extracellular environment, which facilitates the exogenous transfer of AnxA2 from one cell to another. Treatment with Ca2+ ionophore triggers the association of AnxA2 with the specialized microdomains in the exosomal membrane that possess raft-like characteristics. Phosphorylation at Tyr-23 is also important for the localization of AnxA2 to the exosomal membranes. These results suggest that AnxA2 is trafficked from the plasma membrane rafts and is selectively incorporated into the lumenal membranes of the endosomes to escape the endosomal degradation pathway. The Ca2+-dependent exosomal transport constitutes a novel pathway of extracellular transport of AnxA2.

A forensic path to RGC-5 cell line identification: lessons learned.

In 2001, a transformed cell line RGC-5 was developed from the rat retina that was thought to be of retinal ganglion cell origin. Since that time many investigators have used this line in a wide variety of studies to understand better retinal ganglion cell activity, cell signaling, and neuroprotection. Recently, a publication emerged that claimed that this RGC-5 cell line was derived from mouse and not rat, and other studies also indicated the expression of certain proteins that typically were not associated with retinal ganglion cells. This certainly came as a shock not only to the originators of this cell line, but also to others who have been using this as an in vitro model of rat retinal ganglion cells. As a result, we undertook experiments to determine if the RGC-5 cell line currently in use may have been mischaracterized. We, indeed, found that the RGC-5 cell line was of mouse and not rat origin, as was claimed originally in the original research report. We further determined whether these cells were of retinal ganglion origin. Our findings showed conclusively that RGC-5 cells were, indeed, of mouse origin and, using additional cytogenetic profile testing, karyotyping, and genetic and protein profiling, we concluded that these cells were not of retinal ganglion cell origin, but were the cell line 661W, a mouse SV-40 T antigen transformed photoreceptor cell line. The 661W cell line also was present in the laboratory of the originating laboratory and probably resulted in cross-contamination. The present study reviews some of the errors that were made in misidentifying the RGC-5 cell line and offers some insight as to how this may have happened, and ways one can avoid mischaracterization of a potentially important cell line.

Scale up, optimization and stability analysis of Curcumin C3 complex-loaded nanoparticles for cancer therapy

BackgroundNanoparticle based delivery of anticancer drugs have been widely investigated. However, a very important process for Research & Development in any pharmaceutical industry is scaling nanoparticle formulation techniques so as to produce large batches for preclinical and clinical trials. This process is not only critical but also difficult as it involves various formulation parameters to be modulated all in the same process.MethodsIn our present study, we formulated curcumin loaded poly (lactic acid-co-glycolic acid) nanoparticles (PLGA-CURC). This improved the bioavailability of curcumin, a potent natural anticancer drug, making it suitable for cancer therapy. Post formulation, we optimized our process by Reponse Surface Methodology (RSM) using Central Composite Design (CCD) and scaled up the formulation process in four stages with final scale-up process yielding 5 g of curcumin loaded nanoparticles within the laboratory setup. The nanoparticles formed after scale-up process were characterized for particle size, drug loading and encapsulation efficiency, surface morphology, in vitro release kinetics and pharmacokinetics. Stability analysis and gamma sterilization were also carried out.ResultsResults revealed that that process scale-up is being mastered for elaboration to 5 g level. The mean nanoparticle size of the scaled up batch was found to be 158.5 ± 9.8 nm and the drug loading was determined to be 10.32 ± 1.4%. The in vitro release study illustrated a slow sustained release corresponding to 75% drug over a period of 10 days. The pharmacokinetic profile of PLGA-CURC in rats following i.v. administration showed two compartmental model with the area under the curve (AUC0-∞) being 6.139 mg/L h. Gamma sterilization showed no significant change in the particle size or drug loading of the nanoparticles. Stability analysis revealed long term physiochemical stability of the PLGA-CURC formulation.ConclusionsA successful effort towards formulating, optimizing and scaling up PLGA-CURC by using Solid-Oil/Water emulsion technique was demonstrated. The process used CCD-RSM for optimization and further scaled up to produce 5 g of PLGA-CURC with almost similar physicochemical characteristics as that of the primary formulated batch.

Identification of genes and molecular pathways involved in the progression of premalignant oral epithelia

An early interventional effort in oral premalignancy requires novel molecular targets and diagnostic biomarkers to delay or reverse incidences of malignant progression. Microarray-based transcriptional profiling in disease states provides global insight into the causal biomolecular processes and novel pathways involved. In this study, we investigated transcript profiles in precancerous oral lesions to identify nearly 1,700 genes as significantly overexpressed or underexpressed and a primarily affected metabolic pathway that may be responsible for irreversible transition to progressive stages of oral cancer. For the first time, we show a convergence of several genes and pathways known for their oncogenic capabilities, in progression of premalignant oral epithelial tissues. This study consequently provides a molecular basis for persistent proinflammatory conditions in oral premalignant tissues. We found that lipocalin-type prostaglandin D2 synthase (PTGDS), a key enzyme in the arachidonic acid metabolism pathway, as repressed in premalignant stages. We show the protective role of these enzyme-derived metabolites in inhibiting cell proliferation using an in vitro oral cancer progression model. We have also confirmed the overexpression of two invasion-related biomarkers, psoriasin (PSOR1) and versican (CSPG2), in oral premalignant and malignant archival tissues. Our results clearly indicate that pharmacologic intervention with anti-inflammatory prostaglandin D2–like analogues may help prevent or delay oral epithelial carcinogenesis because of metabolic restoration of a negative feedback regulatory loop through its several cognate receptors or target molecules. Further studies directed toward a multitude of possible protective mechanisms of this lipocalin-type enzyme or its products in oral cancer progression are warranted.

Surface functionalization of PLGA nanoparticles by non-covalent insertion of a homo-bifunctional spacer for active targeting in cancer therapy

This work reports the surface functionalization of polymeric PLGA nanoparticles by non-covalent insertion of a homo-bifunctional chemical crosslinker, bis(sulfosuccinimidyl) suberate (BS3) for targeted cancer therapy. We dissolved BS3 in aqueous solution of PVA during formulation of nanoparticles by a modified solid/oil/water emulsion solvent evaporation method. The non-covalent insertion of BS3 was confirmed by Fourier transform infrared (FTIR) spectroscopy. Curcumin and annexin A2 were used as a model drug and a cell specific target, respectively. Nanoparticles were characterized for particle size, zeta potential and surface morphology. The qualitative assessment of antibody attachment was performed by transmission electron microscopy (TEM) as well as confocal microscopy. The optimized formulation showed antibody attachment of 86%. However, antibody attachment was abolished upon blocking the functional groups of BS3. The availability of functional antibodies was evaluated by the presence of a light chain fraction after gel electrophoresis. We further evaluated the in vitro release kinetics of curcumin from antibody coated and uncoated nanoparticles. The release of curcumin is enhanced upon antibody attachment and followed an anomalous release pattern. We also observed that the cellular uptake of nanoparticles was significantly higher in annexin A2 positive cells than in negative cells. Therefore, these results demonstrate the potential use of this method for functionalization as well as to deliver chemotherapeutic agents for treating cancer.

Combinatorial nanoparticles for cancer diagnosis and therapy.

Nanotechnology when engineered together with biotechnology opens a fascinating field with applications in diverse areas such as drug targeting and delivery, medical imaging, biosensing, biomaterials and nanotechnology. Conjugating nanoparticles with biomolecules like QD-herceptin conjugates or QD-aptamer (Apt)-DOX conjugates provides many opportunities for improving many of the current challenges in cancer diagnosis and therapy. This paper reviews combinatorial nanoparticles designed and formulated for cancer imaging and therapy, including inorganic nanoparticles (quantum dots, iron oxide particles, gold nanoparticles and silica and carbon nanoparticles), polymeric nanoparticles (PLGA, PLGA-PEG, PAMAM), liposomes and lipid nanoparticles. These nanoparticles are multifunctional in nature and combine two or more functions like targeting, imaging and therapy. In this review, we have classified these combinatorial targeted nanoparticles into inorganic, polymeric and liposome based nanosystems.