Valproic acid radiosensitizes anaplastic thyroid cells through a decrease of the DNA damage repair capacity.

BACKGROUND: Anaplastic thyroid cancer (ATC) represents a rare lethal human malignancy with poor prognosis. Multimodality treatment, including radiotherapy, is recommended to improve local control and survival. Valproic acid (VA) is a clinically available histone deacetylase inhibitor with a well-documented side effect profile. In this study, we aim to investigate the combined effect of VA with photon irradiation in vitro. METHODS: Anaplastic thyroid cancer cells (8505c) were used to investigate the radiosensitizing effect of VA. RESULTS: VA sensitized cells to photon irradiation. VA increased radiation-induced apoptosis and radiation-induced DNA damage measured by γH2AX foci induction. Furthermore, VA prolonged γH2AX foci disappearance over time in irradiated cells and decreased the radiation-induced levels of mRNA of key DNA damage repair proteins of the homologous recombination (HR) and the nonhomologous end joining (NHEJ) pathways. CONCLUSIONS: VA at a clinically safe dose enhance the radiosensitivity of 8505c cells through an increase in radiation-induced apoptosis and a disruption in the molecular mechanism of HR and NHEJ DNA damage repair pathways.

Comportamiento morfológico y electroquímico de un recubrimiento Dip Coating policaprolactona-quitosano-colágeno sobre Ti6Al4V / Morphological and electrochemical behavior of polycaprolactone-chitosan-collagen film fabricated by Dip Coating on Ti6Al4V

Resumen: En este trabajo se presenta, la caracterización mediante las técnica de Infrarrojo, Microscopía de Fuerza Atómica, Microscopía Electrónica de Barrido y ángulo de contacto de los recubrimientos poliméricos de la mezcla binaria de policaprolactona-quitosano y su modificación tras la adición de colágeno que fueron depositados mediante la técnica de Dip Coating sobre la aleación de Ti6Al4V; además, se evaluó mediante la técnica de Espectroscopía de Impedancia Electroquímica la aleación Ti6Al4V recubierta por las mezclas de polímeros a cero días de inmersión en Fluido Corporal Simulado y la capacidad de adsorción de calcio a 21 días de inmersión. De esta manera, se encontraron efectos representativos sobre el papel del colágeno para el aumento de la rugosidad superficial, mayores valores en la resistencia a la polarización del Ti6Al4V, mejor comportamiento en los parámetros de energía libre, adsorción atómica de calcio y la consolidación de una nueva interfase asociada a la monocapa de calcio simulada mediante circuitos equivalentes y observada por Microscopía Electrónica de Barrido.

Abstract: This paper presents the characterization by the infrared technique, atomic force microscopy, scanning electron microscopy and contact angle of the polymer coatings of the binary mixture of polycaprolactone-chitosan and its modification after addition of collagen were deposited by the technique of Dip Coating on Ti6Al4V alloy; also by the technique of Electrochemical Impedance Spectroscopy were evaluated the Ti6Al4V alloy coated by polymer blends zero days immersion in Simulate Bode Fluid and of adsorptivity calcium to 21 days immersion. Thus, representative effects on the role of collagen to increase the surface roughness, higher values in the polarization resistance of Ti6Al4V, better behavior parameters free energy, atomic adsorption of calcium and the consolidation of a found new interface associated with the monolayer calcium simulated by equivalent circuits and observed by Scanning Electron Microscopy.

Automated image analysis for monitoring oxidative burst in macrophages.

OBJECTIVE: To evaluate oxidative bursts induced by phorbol myristate acetate in phagocytes at the single-cell level by automated image analysis. STUDY DESIGN: The generation of reactive oxygen species was quantitatively expressed by means of histograms displaying the percentage of cells corresponding to each of the total optical densities measured. RESULTS: Macrophage subpopulations were quantitatively defined. This method allows detailed analysis of the amount of formazan per cell and the sites of deposition of blue precipitate in each cell. CONCLUSION: Image analysis is a reliable quantitative, single-cell assay for studying various cellular characteristics associated with macrophage functions.

Role of distinct subpopulations of peritoneal macrophages in the regulation of reactive oxygen species release.

It has been reported in vitro that during the respiratory burst of phagocytic cells the superoxide anion production per cell shows a negative relation with the cell density. This process has been described as autoregulation. The aim of this work was to analyze the superoxide anion production in thioglycollate-elicited peritoneal macrophage exudates to evaluate the importance of the peritoneal cavity environment in the autoregulation process. 12-O-tetradecanoylphorbol-13-acetate (PMA) was used to stimulate the respiratory burst and superoxide anion production was measured evaluating the intracellular formazan deposits that precipitate as a result of nitro blue tetrazolium (NBT) reduction. We have demonstrated a negative correlation between superoxide anion production and cell density in the peritoneal cavity in macrophages challenged with PMA. The response of individual cells was analyzed by means of an image analyzer, measuring the amount of formazan per cell and cell-size changes during the process of activation. The results revealed that the decrease in individual cell response as a function of higher cell densities were due to a significant increase in the amount of basal reaction macrophages. Concomitantly, the number of reactive cells remained unchanged irrespective of the cell density of the population. A direct correlation between cell size and superoxide anion production was observed. This phenomenon was demonstrated in SENCAR and Balb/c strains. However, macrophages from SENCAR mice showed greater superoxide anion production than those from Balb/c. The differences between strains could be associated to the increased sensitivity to PMA tumor promotion of SENCAR mice. Based on this property, macrophages from SENCAR mice were stimulated with opsonized zymosan, a particulate stimulus that reflects the interaction macrophage-microorganism during the phagocytic process. This data will contribute to the knowledge of infection control. We conclude that variations in basal reaction cells modulates the macrophage activation response when excess macrophages are recruited to the peritoneum. This is demonstrated using different stimuli, thus suggesting that this response may be applied to a wide variety of stimuli-macrophage interactions. The differences between strains may be associated to the increased sensitivity to PMA tumor promotion of SENCAR mice.

Increased apoptosis during papilloma development in mice susceptible to tumor progression.

Programmed cell death (apoptosis) is known to occur not only during normal development and tissue remodeling but also during neoplasia. Despite the suggested role of apoptosis in preventing the proliferation of malignant cells, a positive correlation between tumor progression and the presence of apoptotic cells has been found in different types of cancer, including epithelial tumors. In normal mouse skin, the role of apoptosis is not completely understood, and it has been suggested that terminal differentiation may be a special case of apoptosis. In the work reported here, we counted apoptotic cells in mouse skin tumors generated with a two-stage chemical carcinogenesis protocol. We analyzed papillomas from outbred SENCAR mice at different times during promotion, and to better determine the correlation between apoptosis and tumor progression, we compared papillomas generated from two inbred strains derived from the SENCAR stock that differ in their susceptibility to tumor progression. Our results showed that in mouse skin chemical carcinogenesis, the number of apoptotic cells was greater in papillomas that may have been in the process of progressing to squamous cell carcinomas. This conclusion is also supported by the fact that papillomas from SENCAR P/Bt. mice, a tumor progression-susceptible strain derived from outbred SENCAR mice, had more apoptotic cells than papillomas from progression-resistant SSIN mice.

[Rapidly progressive dementia caused by tumor microembolism in the central nervous system]. / Demencia de evolución rapidamente progresiva producida por microembolias tumorales en el sistema nervioso central.

Brain tumoral microembolism is a very unusual etiology of cerebral vascular disease in patients with cancer. The clinical course is characterized by diffuse encefalopathy with associated neurologic deficits. We report a 72-year-old male patient, who developed rapidly progressive dementia associated with diffuse myoclonic jerks, without neurologic deficit, whose brain biopsy showed microscopic emboli of adenocarcinoma of unknown origin in capillary vessels. We did not find metastasis in other organs. We suggest that this entity should be included in the differential diagnoses of the subacute dementias.

Nucleolar organizer regions as a marker of incipient transformation in a model of experimental carcinogenesis.

Nucleolar organizer regions stained selectively with a silver colloid technique (AgNOR) were evaluated during the process of tumour promotion in the skin of mice. Tumour promotion and control skin samples were processed for identification of AgNOR by light microscopy and submitted to a morphometric study of the following AgNOR-related variables: nuclear area (V.NUC); AgNOR number per nucleus (N.NOR); single AgNOR area (V.NOR); total AgNOR area per nucleus (TV.NOR) and proportion of nucleus occupied by AgNOR (TV.NOR/V.NUC). N.NOR exhibited significant differences between control and tumour tissue, but in the promotion period, N.NOR did not exhibit a significant rise until week 24. V.NOR and TV.NOR rose significantly as early as 2 weeks after the onset of promotion when the cells fail to exhibit unusual microscopic features. The significant increase in AgNOR material at the beginning of the promotion period reveals the potential value of the variables assessed in the early quantitative evaluation of cellular alterations which could be linked to the probability of tumour development. Rise in AgNOR material would indicate transcriptional activation leading to an increase in protein synthesis and, ultimately, to the expression of an altered phenotype.

Mast cell phenotypic changes in skin of mice during benzoyl peroxide-induced tumor promotion.

The behavior of the mast cell population was analyzed during the sequential changes that normal mice skin undergoes during experimental two-stage carcinogenesis. Our study reveals that the number of mast cells increased during the promotion period but that this alteration is confined to the 30-microns-wide strip below the epidermis. A different mast cell phenotype appeared in this area, compatible with an MMC-like phenotype. During the carcinogenesis process, the mast cell population is comprised of two distinct subpopulations that appeared simultaneously in the same tissue, i.e. connective tissue mast cells, normally found in the skin of mice, and the newly formed mucosal mast cell-like cells, currently found in gastrointestinal mucosa.

Inhibition of benzoyl peroxide-induced tumor promotion and progression by copper(II)(3,5-diisopropylsalicylate)2.

The ability of a biomimetic superoxide dismutase agent, copper(II)(3,5-diisopropylsalicylate)2 (CuDIPS), to modulate benzoyl peroxide (BzPo)-induced tumor promotion and progression in mouse skin multistage carcinogenesis was evaluated. The results showed a significant inhibition of tumor incidence by CuDIPS pretreatment during promotion-progression. Different types of tumors were developed: papillomas, keratoacanthomas and squamous cell carcinomas. There was a significant increase in the keratoacanthoma-papilloma ratio when the period of treatment with BzPo was prolonged, which was inhibited by CuDIPS pretreatment. CuDIPS induced a significant inhibition of malignant conversion. Our results suggest that reactive oxygen species could be important in BzPo-induced promotion and progression.

Differential oxidative stress induced by two different types of skin tumor promoters, benzoyl peroxide and 12-O-tetradecanoylphorbol-13-acetate.

The oxidative stress induced in vivo by benzoyl peroxide (BzPo) or 12-O-tetradecanoylphorbol-13-acetate (TPA) was evaluated in terms of chemiluminescence (CL) emitted by SENCAR mouse skin, a non-invasive method that allows an estimation of overall oxidative stress. The ability of a biomimetic superoxide dismutase, copper(II)(3,5-diisopropylsalicylate)2 (CuDIPS), to inhibit that response was also evaluated. A single application of BzPo to mouse skin resulted in a dose-dependent increase in CL up to 0.083 mumol. Sequential treatment with BzPo in a dose used for tumor promotion resulted in a fall in CL induced by the second topical application. There were no differences between initiated and non-initiated mice in their responses to BzPo-induced CL. CuDIPS, an inhibitor of tumor promotion, was an effective inhibitor of CL in all the protocols evaluated. Conversely, ZnDIPS and DIPS did not inhibit CL. Phenolic antioxidants induced partial inhibition of CL. Unlike BzPo treatment, a single application of TPA up to 105 nmol did not induce an increase in CL, but the second topical application with TPA in a dose used for tumor promotion resulted in a small but significant increase in CL. However, these values of CL were much smaller than the CL induced by BzPo. Our results show a differential response of the skin in terms of the oxidative stress induced by BzPo or TPA.