Radiosensitivity enhancement of human thyroid carcinoma cells by the inhibitors of histone deacetylase sodium butyrate and valproic acid.

Radiotherapy is one of the leading treatments for clinical cancer therapy. External beam radiotherapy has been proposed as an adjuvant treatment for patients bearing differentiated thyroid cancer refractory to conventional therapy. Our purpose was to study the combined effect of HDAC inhibitors (HDACi) and ionizing irradiation in thyroid cancer cell lines (Nthy-ori 3-1, WRO, TPC-1 and 8505c). HDACi radiosensitized thyroid cancer cells as evidenced by the reduction of survival fraction, whereas they had no effect in the normal cells. HDACi enhanced radiation-induced cell death in WRO cells. Gamma-H2AX foci number increased and persisted long after ionizing exposure in the HDACi-treated cells (WRO and TPC-1). Moreover, the expression of the repair-related gene Ku80 was differentially modulated only in the cancer cells, by the compounds at the protein and/or mRNA levels. We present in vitro evidence that HDACi can enhance the radiosensitivity of human thyroid cancer cells.

2-Iodohexadecanal inhibits thyroid cell growth in part through the induction of let-7f microRNA.

UNLABELLED: It is well known that pituitary TSH exerts the major task in the regulation of thyroid function. However, this gland is capable of certain degree of autonomy, independently of TSH control. Iodine plays an important role in thyroid physiology and biochemistry. The thyroid is capable of producing different iodolipids such as 2-iodohexadecanal (2-IHDA). It was shown that this iodolipid mimic some of the inhibitory effects of excess iodide on several thyroid parameters. OBJECTIVES: To identify the miRNAs regulated by 2-IHDA in rat thyroid cells and likely characterize their role in thyroid cell proliferation and function. RESULTS: FRTL-5 cells were grown in the presence of TSH and treated with 2-IHDA. Among the miRNAs up-regulated by 2-IHDA we focused on miR-let-7f and miR-138. When we transfected the miRNAs, miR-let-7f but not miR-138 overexpression inhibited proliferation of FRTL 5 cells, while miR-let-7f inhibition restored cell growth in 2-IHDA treated cultures. Analysis of cell cycle by flow cytometric DNA analysis revealed that miR-let-7f inhibition reduced the percentage of 2-IHDA treated cells in G1 phase and an increased of the percentage of cells in S phase was observed upon anti-let-7f transfection. The expresion of Cyclin D1 and Cyclin D3 were reduced after the transfection of miR-let-7f and miR-138, respectively. In in vivo studies we observed that miR-let-7f and miR-138 were up regulated by 2-IHDA during goiter involution. CONCLUSION: These results suggest that the inhibitory effects of 2-IHDA on FRTL-5 thyroid cell proliferation are mediated in part through the induction of let-7f microRNA.

Inhibitory effects of 2-iodohexadecanal on FRTL-5 thyroid cells proliferation.

UNLABELLED: Although thyroid gland function is mainly under the control of pituitary TSH, other factors, such as iodine, play a role in this process. The thyroid is capable of producing different iodolipids such as 6-iodo-deltalactone and 2-iodohexadecanal (2-IHDA). It was shown that these iodolipids mimic some of the inhibitory effects of excess iodide on several thyroid parameters. OBJECTIVES: To study the effect of 2-IHDA on cell proliferation and apoptosis in FRTL-5 cells. RESULTS: FRTL-5 cells were grown in the presence of TSH and treated with increasing concentrations of KI and 2-IHDA (0.5, 5, 10 and 33 µM) for 24, 48 and 72 h. Whereas KI inhibited cell proliferation only at 33 µM after 72 h of treatment, 2-IHDA inhibited in a time and concentration dependent manner. Analysis of cell cycle by flow cytometric DNA analysis revealed an accumulation of cells in G1 phase induced by 2-IHDA. The expression of cyclin A, cyclin D1 and cyclin D3 were reduced after treatment with 2-IHDA whereas CDK4 and CDK6 proteins were not modified. 2-IHDA induced a dynamic change in cytoplasmic to nuclear accumulation of p21 and p27 causing these proteins to be accumulated mostly in the nucleus. We also observed evidence of a pro-apoptotic effect of 2-IHDA at highest concentrations. No significant effect of KI was observed. CONCLUSION: These results suggest that the inhibitory effects of 2-IHDA on FRTL-5 thyroid cell proliferation are mediated by cell cycle arrest in G1/S phase and cell death by apoptosis.

Assessment of biological effectiveness of boron neutron capture therapy in primary and metastatic melanoma cell lines.

PURPOSE: In order to optimize the effectiveness of Boron Neutron Capture Therapy (BNCT), Relative Biological Effectiveness (RBE) and Compound Biological Effectiveness (CBE) were determined in two human melanoma cell lines, M8 and Mel-J cells, using the amino acid p-boronophenylalanine (BPA) as boron carrier. MATERIALS AND METHODS: The effects of BNCT on the primary amelanotic cell line M8 and on the metastatic pigmented melanoma cell line Mel-J were studied using colony formation assay. The RBE values were determined using both a gamma ray source, and the neutron beam from the Nuclear Reactor of the National Atomic Energy Commission (RA-3). For the determination of the RBE, cells were irradiated with increasing doses of both sources, between 1 and 8 Gy; and for the determination of CBE factors, the cells were pre-incubated with BPA before irradiation. Afterwards, the cell surviving fraction (SF) was determined for each treatment. RESULTS: Marked differences were observed between both cell lines. Mel-J cells were more radioresistant than the M8 cell line. The clonogenic assays showed that for a SF of 1%, the RBE values were 1.3 for M8 cells and 1.5 for Mel-J cells. Similarly, the CBE values for a 1% SF were 2.1 for M8 and 3 for Mel-J cell lines. For the endpoint of 0.1% of SF the RBE values obtained were 1.2 for M8 and 1.4 for Mel-J cells. Finally, CBE values calculated for a 0.1% were 2 and 2.6 for M8 and Mel-J cell lines respectively. In order to estimate the uptake of the non-radioactive isotope Boron 10 ((10)B), a neutron induced autoradiographic technique was performed showing discrepancies in (10)B uptake between both cell lines. CONCLUSIONS: These obtained in vitro results are the first effectiveness factors determined for human melanoma at the RA-3 nuclear reactor and show that BNCT dosimetry planning for patients could be successfully performed using these new factors.

Protective effect of an antithyroid compound against γ-radiation-induced damage in human colon cancer cells.

We have previously reported the radioprotective effect of propylthiouracil (PTU) on thyroid cells. The aim of the present study was to analyze whether tumor cells and normal cells demonstrate the same response to PTU. Human colon carcinoma cells were irradiated with γ-irradiation with or without PTU. We evaluated the clonogenic survival, intracellular reactive oxygen species levels, catalase, superoxide dismutase and glutathione peroxidase activities, and apoptosis by nuclear cell morphology and caspase-3 activity assays. Cyclic AMP (cAMP) levels were measured by radioimmunoassay. PTU treatment increased surviving cell fraction at 2 Gy (SF2) from 56.9 ± 3.6 in controls to 75.0 ± 3.5 (p < 0.05) and diminished radiation-induced apoptosis. In addition, we observed that the level of antioxidant enzymes' activity was increased in cells treated with PTU. Moreover, pretreatment with PTU increased intracellular levels of cAMP. Forskolin (p < 0.01) and dibutyryl cAMP (p < 0.05) mimicked the effect of PTU on SF2. Co-treatment with H89, an inhibitor of protein kinase A, abolished the radioprotective effect of PTU. PTU reduces the toxicity of ionizing radiation by increasing cAMP levels and also possibly through a reduction in apoptosis levels and in radiation-induced oxidative stress damage. We therefore conclude that PTU protects both normal and cancer cells during exposure to radiation in conditions mimicking the radiotherapy.

6 Iodo-δ-lactone: a derivative of arachidonic acid with antitumor effects in HT-29 colon cancer cells.

BACKGROUND: IL-δ (5-hydroxy-6 iodo-8,11,14-eicosatrienoic delta lactone) an iodinated arachidonic acid (AA) derivative, is one of the iodolipids biosynthesized by the thyroid. Although IL-δ regulates several thyroid parameters such as cell proliferation and goiter growth it was found that this iodolipid inhibits the growth of other non thyroid cell lines. OBJECTIVES: To study the effect of IL-δ on cell proliferation and apoptosis in the colon cancer cell line HT-29. RESULTS: Treatment with IL-δ reduced cell viability in a concentration-dependent manner: 1µM 20%, 5µM 25%, 10µM 31%, 50µM 47% and caused a significant decrease of PCNA expression (25%). IL-δ had pro-apoptotic effects, evidenced by morphological features of programmed cell death such as pyknosis, karyorrhexis, cell shrinkage and cell blebbing observed by fluorescence microscopy, and an increase in caspase-3 activity and in Bax/Bcl-2 ratio (2.5 after 3h of treatment). Furthermore, IL-δ increased ROS production (30%) and lipid peroxidation levels (19%), suggesting that apoptosis could be a result of increased oxidative stress. A maximum increase in c-fos and c-jun protein expression in response to IL-δ was observed 1h after initiation of the treatment. IL-δ also induced a tumour growth delay of 70% compared to the control group in NIH nude mice implanted with HT-29 cells. CONCLUSION: Our study shows that IL-δ inhibits cell growth and induces apoptosis in the colon cancer cell line, HT-29 and opens the possibility that IL-δ could be a potential useful chemotherapy agent.

Protection against radiation-induced damage of 6-propyl-2-thiouracil (PTU) in thyroid cells.

Many epidemiologic studies have shown that the exposure to high external radiation doses increases thyroid neoplastic frequency, especially when given during childhood or adolescence. The use of radioprotective drugs may decrease the damage caused by radiation therapy and therefore could be useful to prevent the development of thyroid tumors. The aim of this study was to investigate the possible application of 6-propyl-2-thiouracil (PTU) as a radioprotector in the thyroid gland. Rat thyroid epithelial cells (FRTL-5) were exposed to different doses of γ irradiation with or without the addition of PTU, methimazole (MMI), reduced glutathione (GSH) and perchlorate (KClO4). Radiation response was analyzed by clonogenic survival assay. Cyclic AMP (cAMP) levels were measured by radioimmunoassay (RIA). Apoptosis was quantified by nuclear cell morphology and caspase 3 activity assays. Intracellular reactive oxygen species (ROS) levels were measured using the fluorescent dye 2',7'-dichlorofluorescein-diacetate. Catalase, superoxide dismutase and glutathione peroxidase activities were also determined. Pretreatment with PTU, MMI and GSH prior to irradiation significantly increased the surviving cell fraction (SF) at 2 Gy (P < 0.05), while no effect was observed with KClO4. An increase in extracellular levels of cAMP was found only in PTU treated cells in a dose and time-dependent manner. Cells incubated with agents that stimulate cAMP (forskolin and dibutyril cAMP) mimicked the effect of PTU on SF. Moreover, pretreatment with the inhibitor of protein kinase A, H-89, abolished the radioprotective effect of PTU. PTU treatment diminished radiation-induced apoptosis and protected cells against radiation-induced ROS elevation and suppression of the antioxidant enzyme's activity. PTU was found to radioprotect normal thyroid cells through cAMP elevation and reduction in both apoptosis and radiation-induced oxidative stress damage.

Biochemical changes during goiter induction by methylmercaptoimidazol and inhibition by delta-iodolactone in rat.

BACKGROUND: We have demonstrated that the administration of delta-iodolactone (i.e., 5-iodo-delta lactone) of arachidonic acid (IL-delta), a mediator in thyroid autoregulation, prevents goiter induction by methylmercaptoimidazol (MMI) in rats. Other studies have shown that transforming growth factor beta-1 (TGF-beta1) mimics some of the actions of excess iodide, but its participation in autoregulation is disputed. The present studies were performed to test the hypotheses that IL-delta decreases thyroid growth by inhibition of cell proliferation and/or by stimulation of apoptosis due to oxidative stress, that TGF-beta is stimulated by an excess of iodide and by IL-delta, and that c-Myc and c-Fos expression are upregulated during goiter induction and downregulated during goiter inhibition. METHODS: Rats were treated with MMI alone or together with iodide or IL-delta. Thyroid weight, cell number, cell proliferation, apoptosis, and oxidative stress were determined. Proliferating cell nuclear antigen (PCNA), TGF-beta1, TGF-beta3, c-Myc, and c-Fos were measured by Western blot. RESULTS: MMI caused a progressive increase in thyroid weight accompanied by an increase in cell number, asymmetry of the ploidy histograms, and PCNA, c-Fos, and c-Myc expression. In addition, an early increase of apoptosis was observed. Peroxides as well as glutathione peroxidase and catalase activities were also increased in goitrous animals. The inhibitory action of IL-delta on goiter formation was accompanied by the inhibition of cell proliferation evidenced by a significant decrease in cell number, PCNA expression, and asymmetry of the ploidy histograms. A transient stimulation of apoptosis after 7 days of treatment was also observed. MMI administration stimulated TGF-beta1 but not TGF-beta3 synthesis. IL-delta alone caused a slight increase of TGF-beta3 but not TGF-beta1, whereas potassium iodide (KI) stimulated both isoforms and MMI reversed KI effect on TGF-beta1 expression but not on TGF-beta3. CONCLUSIONS: The goiter inhibitory action of IL-delta is due to the inhibition of cell proliferation and the transient stimulation of apoptosis. This latter action does not involve oxidative stress. TGF-beta1 does not play a role in the autoregulatory pathway mediated by IL-delta. Iodide stimulates TGF-beta3 without the need of being organified. These results suggest that there may be more than one pathway involved in the autoregulatory mechanism.

Interrelationships between the pancreas and the thyroid.

PURPOSE OF REVIEW: To review advances in understanding of the relationships between the thyroid gland and endocrine function of the pancreas. RECENT FINDINGS: Recent advances reviewed here are the association of certain thyroid diseases with diabetes mellitus, the possible contribution of insulin resistance to thyroid pathology, insulin and glucose metabolism in states of thyroid dysfunction and insulin requirements in diabetic patients with thyroid disease. SUMMARY: Appreciation of associations between the functions of the thyroid gland and endocrine pancreas provides certain insights into clinical management of these conditions.

6 Iodo-delta-lactone reproduces many but not all the effects of iodide.

BACKGROUND: Iodide has direct effects on thyroid function. Several iodinated lipids are biosynthesized by the thyroid and they were postulated as intermediaries in the action of iodide. Among them 6 iodo-delta-lactone (IL-delta) has been identified and proposed to play a role in thyroid autoregulation. The aim of this study was to compare the effect of iodide and IL-delta on several thyroid parameters. METHODS: Thyroid bovine follicles were incubated with the different compounds during three days. RESULTS: KI and IL-delta inhibited iodide uptake, total protein and Tg synthesis but only KI had an effect on NIS and Tg mRNAs levels. Both compounds inhibited Na+/K+ ATPase and deoxy-glucose uptake. As PAX 8, FOXE 1 and TITF1 are involved in the regulation of thyroid specific genes their mRNA levels were measured. While iodide inhibited the expression of the first two, the expression of TITF1 was stimulated by iodide and IL-delta had no effect on these parameters. CONCLUSION: These findings indicate that IL-delta reproduces some but not all the effects of excess iodide. These observations apply for higher micromolar concentrations of iodide while no such effects could be demonstrated at nanomolar iodide concentrations.

Role of transforming growth factor beta in the regulation of thyroid function and growth.

Transforming growth factor beta (TGF-beta) exists in nature as three isoforms. They exert their effects by binding to a type II receptor located at the cell membrane. The TGF-beta-type II receptor complex then recruits type I receptor, and this new complex stimulates the phosphorylation of Smads 2 and 3, which are subsequently transferred to the nucleus, where they regulate gene transcription. The thyroid gland expresses the TGF-beta1 gene mRNA and synthesizes the protein, which under physiologic conditions regulates thyroid growth and function. Different studies have demonstrated that TGF-beta1 inhibits cell proliferation and a number of functional parameters. These include cyclic adenosine monophosphate (AMP) formation, iodine uptake and organification, hormone secretion, and the expression of thyroglobulin, thyroid peroxidase, and Na(+)/I(-) symporter. The expression of the TGF-beta1 gene and protein may be stimulated by iodine under normal conditions. Since TGF-beta1 mimics some of the inhibitory actions of iodine, its participation in thyroid autoregulation has been proposed; however, this concept is still debated. In thyroid tumors, the inhibitory action of TGF-beta1 on cell proliferation is progressively lost as the tumor becomes more undifferentiated. The alterations in the signaling pathway of TGF-beta1 are not the same in tumors from different species. Even within the same species, such as the pig thyroid, the results may be different depending on whether monolayers or follicular suspensions are employed. The data suggest that it is not entirely possible to apply the results obtained in animal studies to normal or pathological human thyroid tissue. More studies are required to provide the information needed to develop treatments, based on targeting the signaling pathway of TGF-beta1, for undifferentiated thyroid cancer and other thyroid diseases.

Boron neutron capture therapy in cancer: past, present and future.

Undifferentiated thyroid cancer (UTC) is a very aggressive tumor with no effective treatment, since it lacks iodine uptake and does not respond to radio or chemotherapy. The prognosis of these patients is bad, due to the rapid growth of the tumor and the early development of metastasis. Boron neutron capture therapy (BNCT) is based on the selective uptake of certain boron non-radioactive compounds by a tumor, and the subsequent irradiation of the area with an appropriate neutron beam. 10B is then activated to 11B, which will immediately decay releasing alpha particles and 7Li, of high linear energy transfer (LET) and limited reach. Clinical trials are being performed in patients with glioblastoma multiforme and melanoma. We have explored its possible application to UTC. Our results demonstrated that a cell line of human UTC has a selective uptake of borophenylalanine (BPA) both in vitro and after transplantation to nude mice. Treatment of mice by BNCT led to a complete control of growth and cure of 100% of the animals. Moreover dogs with spontaneous UTC also have a selective uptake of BPA. At the present we are studying the biodistribution of BPA in patients with UTC before its application in humans.

Boron neutron capture therapy in cancer: past, present and future

Undifferentiated thyroid cancer (UTC) is a very aggressive tumor with no effective treatment, since it lacks iodine uptake and does not respond to radio or chemotherapy. The prognosis of these patients is bad, due to the rapid growth of the tumor and the early development of metastasis. Boron neutron capture therapy (BNCT) is based on the selective uptake of certain boron non-radioactive compounds by a tumor, and the subsequent irradiation of the area with an appropriate neutron beam. 10B is then activated to 11B, which will immediately decay releasing alpha particles and 7Li, of high linear energy transfer (LET) and limited reach. Clinical trials are being performed in patients with glioblastoma multiforme and melanoma. We have explored its possible application to UTC. Our results demonstrated that a cell line of human UTC has a selective uptake of borophenylalanine (BPA) both in vitro and after transplantation to nude mice. Treatment of mice by BNCT led to a complete control of growth and cure of 100 percent of the animals. Moreover dogs with spontaneous UTC also have a selective uptake of BPA. At the present we are studying the biodistribution of BPA in patients with UTC before its application in humans.

O câncer indiferenciado de tiróide (CIT) é um tumor muito agressivo sem tratamento efetivo, uma vez que não capta iodo e não responde à radio ou quimioterapia. O prognóstico desses pacientes é ruim, devido ao rápido crescimento do tumor e surgimento precoce de metástases. A terapia por captura de nêutrons de boro (TCNB) é baseada na captação seletiva de certos compostos de boro não-radioativos pelo tumor, e à subsequente irradiação da área com um feixe de nêutrons apropriado. O 10B é então ativado para 11B, cujo decaimento imediato libera partículas alfa e 7Li, de alta transferência linear de energia (TLE) e alcance limitado. Ensaios clínicos estão sendo conduzidos em pacientes com glioblastoma multiforme e melanoma, e nós estamos explorando sua possível aplicação no CIT. Nossos resultados demonstram que uma linhagem celular do CIT humano mostra captação seletiva de borofenilalanina (BPA) tanto in vitro como após transplante em camundongos "nude". O tratamento de camundongos com TCNB leva a um controle completo do crescimento tumoral e à cura em 100 por cento dos animais. Além disso, cães com CIT espontâneo também apresentam captação seletiva de BPA. No momento, estamos estudando a biodistribuição de BPA em pacientes com CIT, antes de sua aplicação em humanos.

[Triiodothyroacetic acid in euthyroid goiter. New data on its mechanisms of action. Comparison with L-thyroxin]. / Intérêt de l'acide triiodothyroacétique pour le traitement du goître euthyroïdien. Nouvelles données sur son mode d'action. Comparaison avec la L-thyroxine.

Euthyroid goiter is usually treated with THS-inhibiting doses of L-thyroxin (L-T4), which can have troublesome adverse effects. It has been suggested that triiodothyroacetic acid (Triac), a TSH suppressor, might have fewer peripheral effects and better tolerability than T4. We therefore compared the risk-benefit ratios of the two drugs. Thirty-six women with euthyroid goiter (no thyroid cancer) were randomized to receive either Triac (19.6 ug/kg) (n=19) or L-T4 (1.7 ug/kg) (n=17) for 11 months. Goiter volume, lumar and femoral bone mineral density, and serum osteocalcin, deoxypyridinoline, TSH, free T4, and total cholesterol, high-density cholesterol (HDL), low-density cholesterol (LDL), and triglycerides were determined before and after treatment. Student's test and X2 analysis were used. TSH values (microunits/ml) in the Triac and T4 groups were respectively 1.91 +/- 0.6 (basal) and 0.18 +/- 01 (after) and 2.1 +/- 2.5 (basal) and 0.18 +/- 0.3 (after). Thyroid volume fell by 37.9 +/- 35.4% in the Triac group and by 14.5 +/- 39.5% in the L-T4 group (p=0.069). Goiter volume fell by at least 50% in 42% of patients treated with Triac and in 17.7% of patients treated with L-T4 (p=0.15). Triac was associated with fewer adverse events. Changes in bone mineral density, serum deoxypyridinoline, serum osteocalcin and the lipid profile did not differ between the treatment arms. However, the Apo B level fell more strongly on Triac than on T4. These results show that Triac is more effective than L-T4 on goiter size, while having similar peripheral effects.

[Boron neutron capture therapy applied to undifferentiated thyroid carcinoma]. / Tratamiento del cancer por captura neutronica de boro su aplicacion al carcinoma indiferenciado de tiroides.

Undifferentiated thyroid carcinoma (UTC) is an aggressive tumor with a poor prognosis due to the lack of an effective treatment. Boron neutron capture therapy (BNCT) is based on the selective uptake of boron by the tumor and its activation by a neutron beam, releasing lithium-7 and an alpha particle that will kill the tumor cells by their high linear energy transfer (LET). In previous studies we have shown a selective uptake of borophenylalanine (10BPA) in a human UTC cell line (ARO) and in NIH nude mice implanted with this cell line. When these animals were injected with BPA and irradiated with an appropriated neutron beam, we observed a 100% of tumor growth control and a 50% of histological cure when the initial tumor volume was 50 mm3 or less. Further studies with BOPP (tetrakis-carborane carboxylate ester of 2,4-bis-(alpha, beta-dihydroxyethyl)-deutero-porphyrin IX) showed that when this porphyrin was injected 5-7 days before BPA, and the animals were sacrificed 60 min after the i.p. injection of BPA, a significant increase in boron uptake by the tumor was found (45-38 ppm with both compounds vs. 20 ppm with BPA alone). The application of BNCT using the combination of boron compounds showed a 100% of complete remission in tumors with initial volumes under 50 mm3. Dogs suffer spontaneous UTC, with a similar biological behavior to the human tumor, and a selective uptake of BPA. These results open the possibility of applying BNCT to UTC.

Tratamiento del cáncer por captura neutrónica de boro: su aplicación al carcinoma indiferenciado de tiroides / Boron neutron capture therapy applied to undifferentiated thyroid carcinoma

El cáncer indiferenciado de tiroides es un tumor muy agresivo, de muy mal pronóstico y sin tratamiento efectivo. La terapia por captura neutrónica de boro (BNCT) podría ser una alternativa para el tratamiento de esta enfermedad. Se basa en la captación selectiva de boro por el tumor y su activación por un haz de neutrones. El boro activado libera un núcleo de litio-7 y una partícula alfa, las cuales tienen una alta transmisión linear de energía (linear energy transfer, LET) y un alcance de 5-9 µm, destruyendo el tumor. En estudios previos hemos mostrado que la línea celular humana de cáncer indiferenciado de tiroides (ARO) tiene una captación selectiva de borofenilalanina (10BPA) tanto in vitro como después de ser implantada en ratones NIH nude. También demostramos en estos animales inyectados con BPA e irradiados con un haz de neutrones térmicos, un 100% de control sobre el crecimiento tumoral y un 50% de cura histológica. En trabajos posteriores mostramos que la porfirina 10BOPP tetrakis-carborane carboxylate ester de 2,4-bis-(a,b-dihydroxyethyl)-deutero-porphyrin IX) cuando es inyectada 5-7 días antes que el BPA se obtiene una concentración tumoral de boro de aproximadamente el doble que el BPA solo (45-38 ppm vs. 20 ppm). La posterior irradiación con neutrones mostró un 100% de remisión completa en animales con tumores cuyo volumen pre-tratamiento era de 50 mm3 o menor. Los perros padecen CIT espontáneo, con un comportamiento biológico similar al humano, y una captación selectiva de BPA, abriendo la posibilidad de su tratamiento por BNCT

Undifferentiated thyroid carcinoma (UTC) is an aggressive tumor with a poor prognosis due to the lack of an effective treatment. Boron neutron capture therapy (BNCT) is based on the selective uptake of boron by the tumor and its activation by a neutron beam, releasing lithium-7 and an alpha particle that will kill the tumor cells by their high linear energy transfer (LET). In previous studies we have shown a selective uptake of borophenylalanine (10BPA) in a human UTC cell line (ARO) and in NIH nude mice implanted with this cell line. When these animals were injected with BPA and irradiated with an appropriated neutron beam, we observed a 100% of tumor growth control and a 50 % of histological cure when the initial tumor volume was 50 mm3 or less. Further studies with BOPP (tetrakis-carborane carboxylate ester of 2,4-bis-(a, b-dihydroxyethyl)-deutero-porphyrin IX) showed that when this porphyrin was injected 5-7 days before BPA, and the animals were sacrificed 60 min after the i.p. injection of BPA, a significant increase in boron uptake by the tumor was found (45-38 ppm with both compounds vs. 20 ppm with BPA alone). The application of BNCT using the combination of boron compounds showed a 100% of complete remission in tumors with initial volumes under 50 mm3. Dogs suffer spontaneous UTC, with a similar biological behavior to the human tumor, and a selective uptake of BPA. These results open the possibility of applying BNCT to UTC

Tratamiento del cáncer por captura neutrónica de boro: su aplicación al carcinoma indiferenciado de tiroides / Boron neutron capture therapy applied to undifferentiated thyroid carcinoma

El cáncer indiferenciado de tiroides es un tumor muy agresivo, de muy mal pronóstico y sin tratamiento efectivo. La terapia por captura neutrónica de boro (BNCT) podría ser una alternativa para el tratamiento de esta enfermedad. Se basa en la captación selectiva de boro por el tumor y su activación por un haz de neutrones. El boro activado libera un núcleo de litio-7 y una partícula alfa, las cuales tienen una alta transmisión linear de energía (linear energy transfer, LET) y un alcance de 5-9 Am, destruyendo el tumor. En estudios previos hemos mostrado que la línea celular humana de cáncer indiferenciado de tiroides (ARO) tiene una captación selectiva de borofenilalanina (10BPA) tanto in vitro como después de ser implantada en ratones NIH nude. También demostramos en estos animales inyectados con BPA e irradiados con un haz de neutrones térmicos, un 100% de control sobre el crecimiento tumoral y un 50% de cura histológica. En trabajos posteriores mostramos que la porfirina 10BOPP tetrakis-carborane carboxylate ester de 2,4-bis-(a,b-dihydroxyethyl)-deutero-porphyrin IX) cuando es inyectada 5-7 días antes que el BPA se obtiene una concentración tumoral de boro de aproximadamente el doble que el BPA solo (45-38 ppm vs. 20 ppm). La posterior irradiación con neutrones mostró un 100% de remisión completa en animales con tumores cuyo volumen pre-tratamiento era de 50 mm3 o menor. Los perros padecen CIT espontáneo, con un comportamiento biológico similar al humano, y una captación selectiva de BPA, abriendo la posibilidad de su tratamiento por BNCT (AU)

Undifferentiated thyroid carcinoma (UTC) is an aggressive tumor with a poor prognosis due to the lack of an effective treatment. Boron neutron capture therapy (BNCT) is based on the selective uptake of boron by the tumor and its activation by a neutron beam, releasing lithium-7 and an alpha particle that will kill the tumor cells by their high linear energy transfer (LET). In previous studies we have shown a selective uptake of borophenylalanine (10BPA) in a human UTC cell line (ARO) and in NIH nude mice implanted with this cell line. When these animals were injected with BPA and irradiated with an appropriated neutron beam, we observed a 100% of tumor growth control and a 50 % of histological cure when the initial tumor volume was 50 mm3 or less. Further studies with BOPP (tetrakis-carborane carboxylate ester of 2,4-bis-(a, b-dihydroxyethyl)-deutero-porphyrin IX) showed that when this porphyrin was injected 5-7 days before BPA, and the animals were sacrificed 60 min after the i.p. injection of BPA, a significant increase in boron uptake by the tumor was found (45-38 ppm with both compounds vs. 20 ppm with BPA alone). The application of BNCT using the combination of boron compounds showed a 100% of complete remission in tumors with initial volumes under 50 mm3. Dogs suffer spontaneous UTC, with a similar biological behavior to the human tumor, and a selective uptake of BPA. These results open the possibility of applying BNCT to UTC (AU)

Tratamiento del cáncer por captura neutrónica de boro: su aplicación al carcinoma indiferenciado de tiroides / Boron neutron capture therapy applied to undifferentiated thyroid carcinoma

El cáncer indiferenciado de tiroides es un tumor muy agresivo, de muy mal pronóstico y sin tratamiento efectivo. La terapia por captura neutrónica de boro (BNCT) podría ser una alternativa para el tratamiento de esta enfermedad. Se basa en la captación selectiva de boro por el tumor y su activación por un haz de neutrones. El boro activado libera un núcleo de litio-7 y una partícula alfa, las cuales tienen una alta transmisión linear de energía (linear energy transfer, LET) y un alcance de 5-9 Am, destruyendo el tumor. En estudios previos hemos mostrado que la línea celular humana de cáncer indiferenciado de tiroides (ARO) tiene una captación selectiva de borofenilalanina (10BPA) tanto in vitro como después de ser implantada en ratones NIH nude. También demostramos en estos animales inyectados con BPA e irradiados con un haz de neutrones térmicos, un 100% de control sobre el crecimiento tumoral y un 50% de cura histológica. En trabajos posteriores mostramos que la porfirina 10BOPP tetrakis-carborane carboxylate ester de 2,4-bis-(a,b-dihydroxyethyl)-deutero-porphyrin IX) cuando es inyectada 5-7 días antes que el BPA se obtiene una concentración tumoral de boro de aproximadamente el doble que el BPA solo (45-38 ppm vs. 20 ppm). La posterior irradiación con neutrones mostró un 100% de remisión completa en animales con tumores cuyo volumen pre-tratamiento era de 50 mm3 o menor. Los perros padecen CIT espontáneo, con un comportamiento biológico similar al humano, y una captación selectiva de BPA, abriendo la posibilidad de su tratamiento por BNCT (AU)

Undifferentiated thyroid carcinoma (UTC) is an aggressive tumor with a poor prognosis due to the lack of an effective treatment. Boron neutron capture therapy (BNCT) is based on the selective uptake of boron by the tumor and its activation by a neutron beam, releasing lithium-7 and an alpha particle that will kill the tumor cells by their high linear energy transfer (LET). In previous studies we have shown a selective uptake of borophenylalanine (10BPA) in a human UTC cell line (ARO) and in NIH nude mice implanted with this cell line. When these animals were injected with BPA and irradiated with an appropriated neutron beam, we observed a 100% of tumor growth control and a 50 % of histological cure when the initial tumor volume was 50 mm3 or less. Further studies with BOPP (tetrakis-carborane carboxylate ester of 2,4-bis-(a, b-dihydroxyethyl)-deutero-porphyrin IX) showed that when this porphyrin was injected 5-7 days before BPA, and the animals were sacrificed 60 min after the i.p. injection of BPA, a significant increase in boron uptake by the tumor was found (45-38 ppm with both compounds vs. 20 ppm with BPA alone). The application of BNCT using the combination of boron compounds showed a 100% of complete remission in tumors with initial volumes under 50 mm3. Dogs suffer spontaneous UTC, with a similar biological behavior to the human tumor, and a selective uptake of BPA. These results open the possibility of applying BNCT to UTC (AU)

Biodistribution of boron compounds in an animal model of human undifferentiated thyroid cancer for boron neutron capture therapy.

Undifferentiated thyroid carcinoma (UTC) is a rapidly growing, highly invasive malignant tumor that currently lacks any effective treatment. Boron neutron capture therapy (BNCT) has been investigated recently for some types of tumors including glioblastoma multiforme and malignant melanoma. In previous studies we have shown the selective uptake of p-boronophenylalanine (BPA) by undifferentiated thyroid cancer cells in vitro and in vivo, as well as the histologic cure of 50% of the nude mice transplanted with human UTC cells when treated with BPA and an appropriate neutron beam. The present studies were performed to further optimize this treatment through the investigation of a boronated porphyrin, both alone and in combination with BPA. In vitro studies with cells in culture showed that BOPP (tetrakis-carborane carboxylate ester of 2,4-bis-(alpha,beta-dihydroxyethyl)-deutero-porphyrin IX) is localized intracellularly, with a highest concentration in the 11500g (mitochondrial-enriched pellet) fraction. When BOPP was administered alone to NIH nude mice transplanted with UTC human cells, no significant tumor uptake or selectivity in our in vivo model was observed. In contrast, when BOPP was injected 5-7 days before BPA and the animals were sacrificed 60 min after administration of BPA, a significant increase in boron uptake by the tumor was found (38-45 ppm with both compounds vs 20 ppm with BPA alone). On day 5 the tissue boron selectivity ratios were tumor/blood approximately 3.8 and tumor/distal skin approximately 1.8. Other important ratios were tumor/thyroid approximately 6.6 and tumor/lung approximately 2.9. These results open the possibility of improving the efficacy of BNCT for the treatment of this so far "orphan" tumor.