Tetraiodothyroacetic acid (tetrac) and nanoparticulate tetrac arrest growth of medullary carcinoma of the thyroid

CONTEXT

Tetraiodothyroacetic acid (tetrac) blocks angiogenic and tumor cell proliferation actions of thyroid hormone initiated at the cell surface hormone receptor on integrin alphavbeta3. Tetrac also inhibits angiogenesis initiated by vascular endothelial growth factor and basic fibroblast growth factor.

OBJECTIVE

We tested antiangiogenic and antiproliferative efficacy of tetrac and tetrac nanoparticles (tetrac NP) against human medullary thyroid carcinoma (h-MTC) implants in the chick chorioallantoic membrane (CAM) and h-MTC xenografts in the nude mouse.

DESIGN

h-MTC cells were implanted in the CAM model (n = 8 per group); effects of tetrac and tetrac NP at 1 microg/CAM were determined on tumor angiogenesis and tumor growth after 8 d. h-MTC cells were also implanted sc in nude mice (n = 6 animals per group), and actions on established tumor growth of unmodified tetrac and tetrac NP ip were determined.

RESULTS

In the CAM, tetrac and tetrac NP inhibited tumor growth and tumor-associated angiogenesis. In the nude mouse xenograft model, established 450-500 mm(3) h-MTC tumors were reduced in size over 21 d by both tetrac formulations to less than the initial cell mass (100 mm(3)). Tumor tissue hemoglobin content of xenografts decreased by 66% over the course of administration of each drug. RNA microarray and quantitative real-time PCR of tumor cell mRNAs revealed that both tetrac formulations significantly induced antiangiogenic thrombospondin 1 and apoptosis activator gene expression.

CONCLUSIONS

Acting via a cell surface receptor, tetrac and tetrac NP inhibit growth of h-MTC cells and associated angiogenesis in CAM and mouse xenograft models.

Tetraidothyroacetic acid (tetrac) and tetrac nanoparticles inhibit growth of human renal cell carcinoma xenografts

Renal cell carcinoma is the most lethal of the common urologic malignancies, with no available effective therapeutics. Tetrac (tetraiodothyroacetic acid) is a deaminated analogue of L-thyroxine (T(4)) that blocks the pro-angiogenesis actions of T(4) and 3, 5, 3'-triiodo-L-thyronine as well as other growth factors at the cell surface receptor for thyroid hormone on integrin alphavbeta3. Since this integrin is expressed on cancer cells and also on endothelial and vascular smooth cells, the possibility exists that Tetrac may act on both cell types to block the proliferative effects of thyroid hormone on tumor growth and tumor-related angiogenesis. To test this hypothesis, we determined the effect of Tetrac on tumor cell proliferation and on related angiogenesis of human renal cell carcinoma (RCC). We used two models: tumor cell implants in the chick chorioallantoic membrane (CAM) system and xenografts in nude mice. To determine the relative contribution of the nuclear versus the plasma membrane action of Tetrac, we compared the effects of unmodified Tetrac to Tetrac covalently linked to poly (lactide-co-glycolide) as a nanoparticle (Tetrac NP) that acts exclusively at the cell surface through the integrin receptor. In the CAM model, Tetrac and Tetrac NP (both at 1 microg/CAM) arrested tumor-related angiogenesis and tumor growth. In the mouse xenograft model, Tetrac and Tetrac NP promptly reduced tumor volume (p<0.01) when administered daily for up to 20 days. Animal weight gain was comparable in the control and treatment groups. Overall, the findings presented here provide evidence for the anti-angiogenic, and anti-tumor actions of Tetrac and Tetrac NP and suggest their potential utility in the treatment of renal cell carcinoma.

Nanoparticle-targeted delivery of nonanticoagulant heparin and doxorubicin in doxorubicin-resistant breast cancer

e11599

Background: In comparison to low molecular weight heparin (LMWH), non-anticoagulant heparin (NACH), originally developed in our laboratory, has minimal effects on hemostasis. Encapsulation of chemotherapeutic agents and NACH in biodegradable nanoparticles has tremendous potential in improving survival among the breast cancer patients. Furthermore, custom-made nanoparticles with a targeted moiety on the surface would enable us to increase the efficacy and decrease the adverse effects of doxorubicin. Methods: PLGA-PEG nanoparticles co-encapsulating NACH and doxorubicin were synthesized by double emulsion solvent evaporation method. The in vitro efficacy of these nanoparticles was examined in MCF-7 doxorubicin resistant (MCF-7R) cells using MTT cell viability assay. Confocal microscopy was used to examine the uptake of αvβ3 antibody conjugated nanoparticles in human dermal microvascular endothelial cells (HDMEC), which are known to over express αvβ3 integrins. Results: Size measurement by DLS revealed that these nanoparticles co-encapsulating doxorubicin and heparins to be 200–300 nm in size. Data from the MTT assays in MCF-7R cells showed synergy between NACH and doxorubicin when encapsulated in PLGA-PEG nanoparticles. Confocal imaging in HDMEC cells indicates that these nanoparticles have the potential to be used for site specific delivery to the tumor neovascularization. In vivo data in nude mice xenograft (MCF-7R) are shown in the table below (doses of doxorubicin and NACH injected subcutaneously were 0.625 mg/kg and 2.5 mg/kg body weight, respectively). Significant decrease in tumor weight was observed in the mice xenograft, when treated with αvβ3 conjugated nanoparticles co-encapsulating doxorubcin or to greater extent doxorubicin and NACH compares to its non encapsulated counterparts. Conclusions: These data indicated distinct improvement in the anti-tumor efficacy using αvβ3site directed delivery doxorubicin and NACH encapsulted in PLGA-PEG nanoparticles.

[Table: see text]

No significant financial relationships to disclose.

ORMOSIL nanoparticles as a non-viral gene delivery vector for modeling polyglutamine induced brain pathology

Studies have shown the presence of expanded polyQ containing proteins in brain cells related to Huntington disease (HD) and other poly-glutamine disorders. We report the use of organically modified silica (ORMOSIL) nanoparticles as an efficient non-viral gene carrier in an effort to model brain pathology associated with those disorders induced by expanded polyQ peptides. In experiment 1, plasmids expressing Hemaglutinin-tagged polypeptides with 20 glutamine repeats (Q20) or with extended 127-glutamine repeats (Q127) were complexed with ORMOSIL nanoparticles and injected twice (2 weeks apart) into the lateral ventricle of the mouse brain. Fourteen days post-injection of Q127, immunocytochemistry revealed the presence of the characteristic nuclear and cytoplasmic Q127 aggregates in numerous striatal, septal and neocortical neuronal cells as well as ubiquitin-containing aggregates indicative of the neuronal pathology. The mice receiving Q127 showed a marked increase in the reactive GFAP (+) astrocytes in striatum, septum and brain cortex, further indicating the neurodegenerative changes, accompanied by motor impairments. In experiment 2, plasmids Q20 or Q127 were complexed with ORMOSIL and were injected into the brain lateral ventricle or directly into the striatum of adult rats. In both routes of transfection, Q127 induced the appearance of reactive GFAP (+) astrocytes and activated ED1 antigen expressing microglia. An increase in the size of the lateral ventricle was also observed in rats receiving Q127. In transgenic mouse polyQ models, extensive pathologies occur outside the nervous system and the observed brain pathologies could reflect developmental effects of the toxic polyQ proteins. Our experiments show that the nervous tissue restricted expression of poly Q-extended peptides in adult brain is sufficient to evoke neuropathologies associated with HD and other polyQ disorders. Thus, nanotechnology can be employed to model pathological and behavioral aspects of genetic brain diseases in mice as well as in other species, providing a novel research tool for in vivo testing of single or multi-gene therapies.

Polycarboxylic acid nanoparticles for ophthalmic drug delivery: an ex vivo evaluation with human cornea

In ophthalmic drug delivery, a major problem is retaining an adequate concentration of a therapeutic agent in the pre-corneal area. Polycarboxylic acid carriers such as polyacrylic acid and polyitaconic acid in sub-colloidal, nanoparticulate hydrogel form have a strong potential for sustained release of a drug in ocular delivery. Formulations have been prepared of brimonidine loaded in polycarboxylic (polyacrylic and polyitaconic) acid nanoparticles for potential ophthalmic delivery. These particles were prepared by a reverse micro-emulsion polymerization technique with sizes in the range of 50 nm. The loading efficiencies of the drug brimonidine in the particles were shown to be between 80-85% for polyacrylic acid nanoparticles and between 65-70% for polyitaconic nanoparticles. The loading efficiency was also found to be pH dependent. In a preliminary biocompatibility test, human corneal epithelial cells incubated with polyacrylic acid nanoparticles were found to retain their viability, whereas polyitaconic acid nanoparticles were found to be toxic. Two-photon laser scanning microscopic studies of the fluorescently labelled polyacrylic acid nanoparticles and human cornea shows that they are adhesive on the corneal surface. The polyacrylic acid nanoparticles demonstrated a controlled release of the opthalmological drug (Brimonidine) through the human cornea as compared to that of the commercial formulation, Alphagan.