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Davis P.J.,Albany Medical College | Davis P.J.,Albany College of Pharmacy and Health Sciences | Glinsky G.V.,Stanford University | Lin H.-Y.,Taipei Medical University | And 7 more authors.
Frontiers in Endocrinology | Year: 2014

Integrin αvβ3 is generously expressed by cancer cells and rapidly dividing endothelial cells. The principal ligands of the integrin are extracellular matrix proteins, but we have described a cell surface small molecule receptor on αvβ3 that specifically binds thyroid hormone and thyroid hormone analogues. From this receptor, thyroid hormone (L-thyroxine, T4; 3,5,3'-triiodo-L thyronine, T3) and tetraiodothyroacetic acid (tetrac) regulate expression of specific genes by a mechanism that is initiated nongenomically. At the integrin, T4 and T3 at physiological concentrations are pro-angiogenic by multiple mechanisms that include gene expression, and T4 supports tumor cell proliferation. Tetrac blocks the transcriptional activities directed by T4 and T3 at αvβ3, but, independently of T4 and T3, tetrac modulates transcription of cancer cell genes that are important to cell survival pathways, control of the cell cycle, angiogenesis, apoptosis, cell export of chemotherapeutic agents and repair of double-strand DNA breaks. We have covalently bound tetrac to a 200 nm biodegradable nanoparticle that prohibits cell entry of tetrac and limits its action to the hormone receptor on the extracellular domain of plasma membrane αvβ3. This reformulation has greater potency than unmodified tetrac at the integrin and affects a broader range of cancer-relevant genes. In addition to these actions on intracellular kinase mediated regulation of gene expression, hormone analogues at αvβ3 have additional effects on intracellular protein-trafficking (cytosol compartment to nucleus), nucleoprotein phosphorylation and generation of nuclear coactivator complexes that are relevant to traditional genomic actions of T3. Thus, previously unrecognized cell surface-initiated actions of thyroid hormone and tetrac formulations at αvβ3 offer opportunities to regulate angiogenesis and multiple aspects of cancer cell behavior. © 2014 Davis, Glinsky, Lin, Leith, Hercbergs, Tang, Ashur-fabian, Incerpi and Mousa.

Davis P.J.,Albany Medical College | Davis P.J.,Albany College of Pharmacy and Health Sciences | Lin H.-Y.,Albany College of Pharmacy and Health Sciences | Lin H.-Y.,Taipei Medical University | And 11 more authors.
OncoTargets and Therapy | Year: 2014

The extracellular domain of integrin avB3 contains a receptor for thyroid hormone and hormone analogs. The integrin is amply expressed by tumor cells and dividing blood vessel cells. The proangiogenic properties of thyroid hormone and the capacity of the hormone to promote cancer cell proliferation are functions regulated nongenomically by the hormone receptor on avB3. An L-thyroxine (T4) analog, tetraiodothyroacetic acid (tetrac), blocks binding of T4 and 3,5,3'-triiodo-L-thyronine (T3) by avB3 and inhibits angiogenic activity of thyroid hormone. Covalently bound to a 200 nm nanoparticle that limits its activity to the cell exterior, tetrac reformulated as Nanotetrac has additional effects mediated by avB3 beyond the inhibition of binding of T4 and T3 to the integrin. These actions of Nanotetrac include disruption of transcription of cell survival pathway genes, promotion of apoptosis by multiple mechanisms, and interruption of repair of double-strand deoxyribonucleic acid breaks caused by irradiation of cells. Among the genes whose expression is suppressed by Nanotetrac are EGFR, VEGFA, multiple cyclins, catenins, and multiple cytokines. Nanotetrac has been effective as a chemotherapeutic agent in preclinical studies of human cancer xenografts. The low concentrations of avB3 on the surface of quiescent nonmalignant cells have minimized toxicity of the agent in animal studies. © 2014 Davis et al.

Avivi A.,Haifa University | Nevo E.,Haifa University | Cohen K.,Hematology Institute and Blood Bank | Cohen K.,Tel Aviv University | And 8 more authors.
Endocrine Research | Year: 2014

The Israeli blind subterranean mole rat (Spalax ehrenbergi superspecies) lives in sealed underground burrows under extreme, hypoxic conditions. The four Israeli Spalax allospecies have adapted to different climates, the cool-humid (Spalax galili, 2n=52 chromosomes), semihumid (S. golani, 2n=54) north regions, warm-humid (S. carmeli, 2n=58) central region and the warm-dry S. judaei, 2n=60) southern regions. A dramatic interspecies decline in basal metabolic rate (BMR) from north to south, even after years of captivity, indicates a genetic basis for this BMR trait. We examined the possibility that the genetically-conditioned interspecies BMR difference was expressed via circulating thyroid hormone. An unexpected north to south increase in serum free thyroxine (FT4) and total 3, 5, 3′-triiodo-L-thyronine (T3) (p<0.02) correlated negatively with previously published BMR measurements. The increases in serum FT4 and T3 were symmetrical, so that the T3:FT4 ratio-interpretable as an index of conversion of T4 to T3 in nonthyroidal tissues-did not support relative decrease in production of T3 as a contributor to BMR. Increased north-to-south serum FT4 and T3 levels also correlated negatively with hemoglobin/hematocrit. North-to-south adaptations in spalacids include decreased BMR and hematocrit/hemoglobin in the face of increasing thyroid hormone levels, arguing for independent control of hormone secretion and BMR/hematocrit/hemoglobin. But the significant inverse relationship between thyroid hormone levels and BMR/hematocrit/hemoglobin is also consistent with a degree of cellular resistance to thyroid hormone action that protects against hormone-induced increase in oxygen consumption in a hostile, hypoxic environment. © 2014 Informa Healthcare USA, Inc. All rights reserved.

Cohen K.,Meir Medical Center | Cohen K.,Tel Aviv University | Ellis M.,Meir Medical Center | Ellis M.,Hematology Institute and Blood Bank | And 5 more authors.
Molecular Cancer Research | Year: 2011

Experimental and clinical observations suggest that thyroid hormone [L-thyroxine (T 4) and 3,5,3′-triiodo-L-thyronine (T 3)] can support cancer cell proliferation. T 3 and T 4 promote both tumor cell division and angiogenesis by activating mitogen-activated protein kinase (MAPK) via binding to a hormone receptor on the αvβ3 integrin, overexpressed on many cancer cells. We have studied the responsiveness of several MM cell lines to T 3 and T 4 and characterized hormonal effects on cell survival, proliferation, and MAPK activation. Overnight T 3 (1-100 nmol/L) and T 4 (100 nmol/L) incubation enhanced, up to 50% (P < 0.002), MM cell viability (WST-1 assay) and increased cell proliferation by 30% to 60% (P < 0.01). Short exposure (10 minutes) to T 3 and T 4 increased MAPK activity by 2.5- to 3.5-fold (P < 0.03). Pharmacologic MAPK inhibition blocked the proliferative action of T 3 and T 4. Antibodies to the integrin αvβ3 dimer and αv and β3 monomers (but not β1) inhibited MAPK activation and subsequent cell proliferation in response to thyroid hormone, indicating dependence upon this integrin. Moreover, tetraiodothyroacetic acid (tetrac), a non-agonist T 4 analogue previously shown to selectively block T 3/T 4 binding to αvβ3 receptor site, blocked induction of MAPK by the hormones in a dose-dependent manner. This demonstration of the role of thyroid hormones as growth factors for MM cells may offer novel therapeutic approaches. ©2011 AACR.

Dror A.A.,Tel Aviv University | Lenz D.R.,Tel Aviv University | Shivatzki S.,Tel Aviv University | Cohen K.,Tel Aviv University | And 4 more authors.
Mammalian Genome | Year: 2014

Thyroid hormone is essential for inner ear development and is required for auditory system maturation. Human mutations in SLC26A4 lead to a syndromic form of deafness with enlargement of the thyroid gland (Pendred syndrome) and non-syndromic deafness (DFNB4). We describe mice with an Slc26a4 mutation, Slc26a4 loop/loop, which are profoundly deaf but show a normal sized thyroid gland, mimicking non-syndromic clinical signs. Histological analysis of the thyroid gland revealed defective morphology, with a majority of atrophic microfollicles, while measurable thyroid hormone in blood serum was within the normal range. Characterization of the inner ear showed a spectrum of morphological and molecular defects consistent with inner ear pathology, as seen in hypothyroidism or disrupted thyroid hormone action. The pathological inner ear hallmarks included thicker tectorial membrane with reduced β-tectorin protein expression, the absence of BK channel expression of inner hair cells, and reduced inner ear bone calcification. Our study demonstrates that deafness in Slc26a4 loop/loop mice correlates with thyroid pathology, postulating that sub-clinical thyroid morphological defects may be present in some DFNB4 individuals with a normal sized thyroid gland. We propose that insufficient availability of thyroid hormone during inner ear development plays an important role in the mechanism underlying deafness as a result of SLC26A4 mutations. © 2014 Springer Science+Business Media New York.

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