Spontaneous Prophage Induction Contributes to the Production of Membrane Vesicles by the Gram-Positive Bacterium Lacticaseibacillus casei BL23.

The formation of membrane vesicles (MVs) by Gram-positive bacteria has gained increasing attention over the last decade. Recently, models of vesicle formation have been proposed and involve the digestion of the cell wall by prophage-encoded or stress-induced peptidoglycan (PG) hydrolases and the inhibition of PG synthesis by ß-lactam antibiotics. The impact of these mechanisms on vesicle formation is largely dependent on the strain and growth conditions. To date, no information on the production of vesicles by the lactobacilli family has been reported. Here, we aimed to characterize the MVs released by the Gram-positive bacteria Lacticaseibacillus casei BL23 and also investigated the mechanisms involved in vesicle formation. Using electron microscopy, we established that the size of the majority of L. casei BL23 vesicles ranged from 50 to 100 nm. Furthermore, we showed that the vesicles were released consistently throughout the growth of the bacteria in standard culture conditions. The protein composition of the vesicles released in the supernatant was identified and a significant number of prophage proteins was detected. Moreover, using a mutant strain harboring a defective PLE2 prophage, we were able to show that the spontaneous and mitomycin-triggered induction of the prophage PLE2 contribute to the production of MVs by L. casei BL23. Finally, we also demonstrated the influence of prophages on the membrane integrity of bacteria. Overall, our results suggest a key role of the prophage PLE2 in the production of MVs by L. casei BL23 in the absence or presence of genotoxic stress. IMPORTANCE The last few decades have demonstrated that membrane vesicles (MVs) produced by microorganisms can have a wide variety of functions. This diversity places MVs at the crossroads of major research topics in current microbiology such as antibiotic resistance, horizontal gene transfer, cell communication, biofilm development, bacteriophage resistance, and pathogenesis. In particular, vesicles produced by probiotic strains have been shown to play a significant role in their beneficial effects. Thus, the study of vesicle biogenesis is a key element for promoting and improving their release. Overall, our results suggest a key role of spontaneous and mitomycin-triggered prophage induction in MV production by the Gram-positive bacteria Lacticaseibacillus casei BL23. This phenomenon is of great interest as prophage-induced MVs could potentially influence bacterial behavior, stress resistance, and vesicle functions.

Genetic landscape of a large cohort of Primary Ovarian Insufficiency: New genes and pathways and implications for personalized medicine.

BACKGROUND: Primary Ovarian Insufficiency (POI), a public health problem, affects 1-3.7% of women under 40 yielding infertility and a shorter lifespan. Most causes are unknown. Recently, genetic causes were identified, mostly in single families. We studied an unprecedented large cohort of POI to unravel its molecular pathophysiology. METHODS: 375 patients with 70 families were studied using targeted (88 genes) or whole exome sequencing with pathogenic/likely-pathogenic variant selection. Mitomycin-induced chromosome breakages were studied in patients' lymphocytes if necessary. FINDINGS: A high-yield of 29.3% supports a clinical genetic diagnosis of POI. In addition, we found strong evidence of pathogenicity for nine genes not previously related to a Mendelian phenotype or POI: ELAVL2, NLRP11, CENPE, SPATA33, CCDC150, CCDC185, including DNA repair genes: C17orf53(HROB), HELQ, SWI5 yielding high chromosomal fragility. We confirmed the causal role of BRCA2, FANCM, BNC1, ERCC6, MSH4, BMPR1A, BMPR1B, BMPR2, ESR2, CAV1, SPIDR, RCBTB1 and ATG7 previously reported in isolated patients/families. In 8.5% of cases, POI is the only symptom of a multi-organ genetic disease. New pathways were identified: NF-kB, post-translational regulation, and mitophagy (mitochondrial autophagy), providing future therapeutic targets. Three new genes have been shown to affect the age of natural menopause supporting a genetic link. INTERPRETATION: We have developed high-performance genetic diagnostic of POI, dissecting the molecular pathogenesis of POI and enabling personalized medicine to i) prevent/cure comorbidities for tumour/cancer susceptibility genes that could affect life-expectancy (37.4% of cases), or for genetically-revealed syndromic POI (8.5% of cases), ii) predict residual ovarian reserve (60.5% of cases). Genetic diagnosis could help to identify patients who may benefit from the promising in vitro activation-IVA technique in the near future, greatly improving its success in treating infertility. FUNDING: Université Paris Saclay, Agence Nationale de Biomédecine.

Prophylactic surgery plus hyperthermic intraperitoneal chemotherapy (HIPEC CO2) versus standard surgery in colorectal carcinoma at high risk of peritoneal carcinomatosis: short-term and long-term outcomes from the CHECK study - protocol for a randomised, multicentre, phase 3 trial.

INTRODUCTION: Up to one-fifth of patients with colorectal cancer will develop peritoneal metastases, frequently without other districts' involvement. Despite the recent unsuccesses of hyperthermic intraperitoneal chemotherapy (HIPEC) for colorectal cancer peritoneal metastases treatment, the rationale in the prophylactic setting remains strong. Several clinical and pharmacokinetic data suggest that the efficacy of intraperitoneal chemotherapy is highest when the disease is microscopic. However, robust evidence demonstrating whether the addition of HIPEC for high-risk colorectal cancers offers better control of local recurrence is lacking. METHODS AND ANALYSIS: This is a multicentre randomised phase 3 trial comparing prophylactic surgery plus HIPEC CO2 with mitomycin, over standard surgical excision in patients with colorectal cancer at high risk of peritoneal carcinomatosis; 388 patients will be included in this study. The primary objective is to compare the efficacy of prophylactic surgery (radical colorectal resection, omentectomy, appendectomy, round ligament of the liver resection and bilateral adnexectomy) plus HIPEC CO2 with mitomycin and standard surgery in terms of local recurrence-free survival. The main secondary endpoints are disease-free survival (DFS), overall survival (OS) and safety. The primary endpoint will be described with a cumulative incidence function and will be analysed with Grey test to take account of the competing risks. DFS and OS will be described with the Kaplan-Meier method. ETHICS AND DISSEMINATION: This trial has been evaluated by the Italian Medicines Agency, local ethics committees and will be submitted to the Ministry of Health to notify the start of the trial according to the regulation of trials on devices with CE mark/certification.The results will be submitted for presentation at academic meetings and for publication in a peer-reviewed journal, whatever the findings. TRIAL REGISTRATION NUMBER: NCT03914820.

Cytotoxicity, crosslinking and biological activity of three mitomycins.

While interstrand crosslinks (ICLs) have been considered as one type of DNA damage in the past, there is mounting evidence suggesting that these highly cytotoxic lesions are processed differently by the cellular machinery depending upon the ICL structure. In this study, we examined the crosslinking ability of three mitomycins, the structure of the ICLs they produce and the cytotoxicity of the drugs toward three different cell lines. The drugs are: mitomycin C (1), decarbamoylmitomycin C (2), and a mitomycin-conjugate (3) whose mitosane moiety is linked to a N-methylpyrrole carboxamide. We found that, overall, both MC and compound 3 show strong similarities regarding their alkylation of DNA, while DMC alkylating behavior is markedly different. To gain further insight into the mode of action of these drugs, we performed high throughput gene expression and gene ontology analysis to identify gene expression and cellular pathways most impacted by each drug treatment in MCF-7 cell lines. We observed that the novel mitomycin derivative (3) specifically causes changes in the expression of genes encoding proteins involved in cell integrity and tissue structure. Further analysis using bioinformatics (IPA) indicated that the new derivative (3) displays a stronger downregulation of major signaling networks that regulate the cell cycle, DNA damage response and cell proliferation when compared to MC and DMC. Collectively, these findings demonstrate that cytotoxic mechanisms of all three drugs are complex and are not solely related to their crosslinking abilities or the structure of the ICLs they produce.

Determination of the Protein-Protein Interactions within Acyl Carrier Protein (MmcB)-Dependent Modifications in the Biosynthesis of Mitomycin.

Mitomycin has a unique chemical structure and contains densely assembled functionalities with extraordinary antitumor activity. The previously proposed mitomycin C biosynthetic pathway has caused great attention to decipher the enzymatic mechanisms for assembling the pharmaceutically unprecedented chemical scaffold. Herein, we focused on the determination of acyl carrier protein (ACP)-dependent modification steps and identification of the protein-protein interactions between MmcB (ACP) with the partners in the early-stage biosynthesis of mitomycin C. Based on the initial genetic manipulation consisting of gene disruption and complementation experiments, genes mitE, mmcB, mitB, and mitF were identified as the essential functional genes in the mitomycin C biosynthesis, respectively. Further integration of biochemical analysis elucidated that MitE catalyzed CoA ligation of 3-amino-5-hydroxy-bezonic acid (AHBA), MmcB-tethered AHBA triggered the biosynthesis of mitomycin C, and both MitB and MitF were MmcB-dependent tailoring enzymes involved in the assembly of mitosane. Aiming at understanding the poorly characterized protein-protein interactions, the in vitro pull-down assay was carried out by monitoring MmcB individually with MitB and MitF. The observed results displayed the clear interactions between MmcB and MitB and MitF. The surface plasmon resonance (SPR) biosensor analysis further confirmed the protein-protein interactions of MmcB with MitB and MitF, respectively. Taken together, the current genetic and biochemical analysis will facilitate the investigations of the unusual enzymatic mechanisms for the structurally unique compound assembly and inspire attempts to modify the chemical scaffold of mitomycin family antibiotics.

Synthesis of Oligonucleotides containing the cis-Interstrand Crosslink Produced by Mitomycins in their Reaction with DNA.

Mitomycin C (MC) an antitumor drug and decarbamoylmitomycin C (DMC), a derivative of MC lacking the carbamoyl moiety, are DNA alkylating agents which can form DNA interstrand crosslinks (ICLs) between deoxyguanosine residues located on opposing DNA strands. MC forms primarily deoxyguanosine adducts with a 1"-R stereochemistry at the guanine-mitosene bond (1"-α, trans) whereas DMC forms mainly adducts with a 1"-S stereochemistry (1"-ß, cis). The crosslinking reaction is diastereospecific: trans-crosslinks are formed exclusively at CpG sequences, while cis-crosslinks are formed only at GpC sequences. Until now, oligonucleotides containing 1"-ß-deoxyguanosine adducts or ICL at a specific site could not be synthesized, thus limiting the investigation of the role played by the stereochemical configuration at C1'' in the toxicity of these compounds. Here, a novel biomimetic synthesis to access these substrates is presented. Structural proof of the adducted oligonucleotides and ICL were provided by enzymatic digestion to nucleosides, high resolution mass spectral analysis, CD spectroscopy and UV melting temperature studies. Finally, a virtual model of the 25-mer 1"-ß ICL synthesized was created to explore the conformational space and structural features of the crosslinked duplex.

Synthesis of Mitomycin C and decarbamoylmitomycin C N6 deoxyadenosine-adducts.

Mitomycin C (MC), an anti-cancer drug, and its analog, decarbamoylmitomycin C (DMC), are DNA-alkylating agents. MC is currently used in the clinics and its cytotoxicity is mainly due to its ability to form Interstrand Crosslinks (ICLs) which impede DNA replication and, thereby, block cancer cells proliferation. However, both MC and DMC are also able to generate monoadducts with DNA. In particular, we recently discovered that DMC, like MC, can form deoxyadenosine (dA) monoadducts with DNA. The biological role played by these monoadducts is worthy of investigation. To probe the role of these adducts and to detect them in enzymatic digests of DNA extracted from culture cells treated by both drugs, we need access to reference compounds i.e. MC and DMC dA-mononucleoside adducts. Previous biomimetic methods used to generate MC and DMC mononucleoside adducts are cumbersome and very low yielding. Here, we describe the diastereospecific chemical synthesis of both C-1 epimers of MC and DMC deoxyadenosine adducts. The key step of the synthesis involves an aromatic substitution reaction between a 6-fluoropurine 2'-deoxyribonucleoside and appropriately protected stereoisomeric triaminomitosenes to form protected-MC-dA adducts with either an S or R stereochemical configuration at the adenine-mitosene linkage. Fluoride-based deprotection methods generated the final four reference compounds: the two stereoisomeric MC-dA adducts and the two stereoisomeric DMC-dA adducts. The MC and DMC-dA adducts synthesized here will serve as standards for the detection and identification of such adducts formed in the DNA of culture cells treated with both drugs.

In vitro characterization of MitE and MitB: Formation of N-acetylglucosaminyl-3-amino-5-hydroxybenzoyl-MmcB as a key intermediate in the biosynthesis of antitumor antibiotic mitomycins.

Mitomycins, produced by several Streptomyces strains, are potent anticancer antibiotics that comprise an aziridine ring fused to a tricyclic mitosane core. Mitomycins have remarkable ability to crosslink DNA with high efficiency. Despite long clinical history of mitomycin C, the biosynthesis of mitomycins, especially mitosane core formation, remains unknown. Here, we report in vitro characterization of three proteins, MmcB (acyl carrier protein), MitE (acyl AMP ligase), and MitB (glycosyltransferase) involved in mitosane core formation. We show that 3-amino-5-hydroxybenzoic acid (AHBA) is first loaded onto MmcB by MitE at the expense of ATP. MitB then catalyzes glycosylation of AHBA-MmcB with uridine diphosphate-N-acetylglucosamine (UDP-GlcNAc) to generate a key intermediate, GlcNAc-AHBA-MmcB, which contains all carbon and nitrogen atoms of the mitosane core. These results provide important insight into mitomycin biosynthesis.

Synergistic Anti-Cancer Effects of AKT and SRC Inhibition in Human Pancreatic Cancer Cells.

PURPOSE: To investigate the effect of combined inhibition of protein kinase B (AKT) and SRC on the growth and metastatic potential of human pancreatic cancer cells. MATERIALS AND METHODS: AKT and SRC were inhibited using 10-DEBC and PP2, respectively. The expression of their messenger RNAs were down-regulated by specific small interfering RNA (siRNA). Changes in pancreatic cancer cell growth and metastatic potential were determined using a cell viability assay and a xenotransplant model of pancreatic cancer, as well as cell migration and invasion assays. Signal proteins were analyzed by Western blot. RESULTS: The inhibitors 10-DEBC and PP2 suppressed cell proliferation in a dose-dependent fashion in pancreatic cancer cell lines MIA PaCa-2 and PANC-1. The simultaneous inhibition of AKT and SRC at low concentrations resulted in a significant suppression of cell proliferation. Knockdown of AKT2 and SRC using siRNAs also significantly decreased cell proliferation. In a pancreatic cancer model, combined treatment with 10-DEBC and PP2 also significantly suppressed the growth of pancreatic cancer. Application of 10-DEBC with PP2 significantly reduced the metastatic potential of pancreatic cancer cells by inhibiting migration and invasion. The combined inhibition suppressed the phosphorylation of mTOR and ERK in pancreatic cancer cells. CONCLUSION: Combined targeting of AKT and SRC resulted in a synergistic efficacy against human pancreatic cancer growth and metastasis.

Isolation and Rationale for the Formation of Isomeric Decarbamoylmitomycin C- N6-deoxyadenosine Adducts in DNA.

Mitomycin C (MC) is an anticancer agent that alkylates DNA to form monoadducts and interstrand cross-links. Decarbamoylmitomycin C (DMC) is an analogue of MC lacking the carbamate on C10. The major DNA adducts isolated from treatment of culture cells with MC and DMC are N2-deoxyguanosine (dG) adducts and adopt an opposite stereochemical configuration at the dG-mitosene bond. To elucidate the molecular mechanisms of DMC-DNA alkylation, we have reacted short oligonucleotides, calf thymus, and M. luteus DNA with DMC using biomimetic conditions. These experiments revealed that DMC is able to form two stereoisomeric deoxyadenosine (dA) adducts with DNA under bifuntional reduction conditions and at low temperature. The dA-DMC adducts formed were detected and quantified by HPLC analysis after enzymatic digestion of the alkylated DNA substrates. Results revealed the following rules for DMC dA alkylation: (i) DMC dA adducts are formed at a 48- to 4-fold lower frequency than dG adducts, (ii) the 5'-phosphodiester linkage of the dA adducts is resistant to snake venom diesterase, (iii) end-chain dA residues are more reactive than internal ones in duplex DNA, and (iv) nucleophilic addition by dA occurs on both faces of DMC and the ratio of stereoisomeric dA adducts formed is dependent on the end bases located at the 3' or 5' position. A key finding was to discover that temperature plays a determinant role in the regioselectivity of duplex DNA alkylation by DMC: at 0 °C, both dA and dG alkylation occur, whereas at 37 °C, DMC preferentially alkylates dG residues.

Interdependent Sequence Selectivity and Diastereoselectivity in the Alkylation of DNA by Decarbamoylmitomycin†C.

Mitomycin C (MC), an antitumor drug, and decarbamoylmitomycin C (DMC), a derivative of MC, alkylate DNA and form deoxyguanosine monoadducts and interstrand crosslinks (ICLs). Interestingly, in mammalian culture cells, MC forms primarily deoxyguanosine adducts with a 1"-R stereochemistry at the guanine-mitosene bond (1"-α) whereas DMC forms mainly adducts with a 1"-S stereochemistry (1"-ß). The molecular basis for the stereochemical configuration exhibited by DMC has been investigated using biomimetic synthesis. Here, we present the results of our studies on the monoalkylation of DNA by DMC. We show that the formation of 1"-ß-deoxyguanosine adducts requires bifunctional reductive activation of DMC, and that monofunctional activation only produces 1"-α-adducts. The stereochemistry of the deoxyguanosine adducts formed is also dependent on the regioselectivity of DNA alkylation and on the overall DNA CG content. Additionally, we found that temperature plays a determinant role in the regioselectivity of duplex DNA alkylation by mitomycins: At 0 °C, both deoxyadenosine (dA) and deoxyguanosine (dG) alkylation occur whereas at 37 °C, mitomycins alkylate dG preferentially. The new reaction protocols developed in our laboratory to investigate DMC-DNA alkylation raise the possibility that oligonucleotides containing DMC 1"-ß-deoxyguanosine adducts at a specific site may be synthesized by a biomimetic approach.

The evolving role of DNA inter-strand crosslinks in chemotherapy.

DNA crosslinking agents make up a broad class of chemotherapy agents that target rapidly dividing cancer cells by disrupting DNA synthesis. These drugs differ widely in both chemical structure and biological effect. In cells, crosslinking agents can form multiple types of DNA lesions with varying efficiencies. Inter-strand crosslinks (ICLs) are considered to be the most cytotoxic lesion, creating a covalent roadblock to replication and transcription. Despite over 50 years in the clinic, the use of crosslinking agents that specialize in the formation of ICLs remains limited, largely due to high toxicity in patients. Current ICL-based therapeutics have focused on late-stage and drug-resistant tumors, or localized treatments that limit exposure. In this article, we review the development of clinical crosslinking agents, our understanding of how cells respond to different lesions, and the potential to improve ICL-based chemotherapeutics in the future.

Sequence-Dependent Diastereospecific and Diastereodivergent Crosslinking of DNA by Decarbamoylmitomycin C.

Mitomycin C (MC), a potent antitumor drug, and decarbamoylmitomycin C (DMC), a derivative lacking the carbamoyl group, form highly cytotoxic DNA interstrand crosslinks. The major interstrand crosslink formed by DMC is the C1'' epimer of the major crosslink formed by MC. The molecular basis for the stereochemical configuration exhibited by DMC was investigated using biomimetic synthesis. The formation of DNA-DNA crosslinks by DMC is diastereospecific and diastereodivergent: Only the 1''S-diastereomer of the initially formed monoadduct can form crosslinks at GpC sequences, and only the 1''R-diastereomer of the monoadduct can form crosslinks at CpG sequences. We also show that CpG and GpC sequences react with divergent diastereoselectivity in the first alkylation step: 1"S stereochemistry is favored at GpC sequences and 1''R stereochemistry is favored at CpG sequences. Therefore, the first alkylation step results, at each sequence, in the selective formation of the diastereomer able to generate an interstrand DNA-DNA crosslink after the "second arm" alkylation. Examination of the known DNA adduct pattern obtained after treatment of cancer cell cultures with DMC indicates that the GpC sequence is the major target for the formation of DNA-DNA crosslinks in vivo by this drug.

Análisis de impacto presupuestal de 21 tecnologías para el manejo quimioterapéutico del cáncer en Colombia / Budget impact analysis of 21 technologies for the chemotherapeutic management of cancer in Colombia

INTRODUCCIÓN: El análisis de impacto presupuestal (AIP) de los medicamentos quimioterapéuticos para el tratamiento de cáncer en Colombia, se desarrolló en el marco del mecanismo técnicocientífico para la ampliación progresiva del Plan de Beneficios en Salud con cargo a la UPC (PBSUPC) y la definición de la lista de exclusiones, establecido en el artículo 15 de la Ley 1751 de 2015. La quimioterapia tiene un gran impacto en el tratamiento oncológico, la cual es indispensable por su valor terapéutico en varios tipos de cáncer. Esta tecnología puede ser usada sola o junto con otros tratamientos, tales como la cirugía o la radioterapia. La quimioterapia engloba a una gran variedad de fármacos y su objetivo es destruir las células tumorales con el fin de lograr la reducción de la enfermedad, los medicamentos empleados en este tipo de tratamiento se les denomina fármacos antineoplásicos. Cada tipo de tumor canceroso tiene una determinada sensibilidad a estos medicamentos, por lo tanto, es frecuente que el mismo fármaco se pueda emplear en el tratamiento de distintos tumores, variando las dosis o asociándolo a otros fármacos distintos. La quimioterapia puede ser administrada con fines curativos o para aliviar los síntomas y prolongar la supervivencia. La forma de administración de la quimioterapia es por ciclos y esto se logra alternando los periodos de tratamiento con periodos de descanso. Un ciclo es, por lo tanto, el periodo de administración del tratamiento y el de descanso hasta la siguiente administración. El objetivo de este análisis de impacto presupuestal (AIP) es estimar el esfuerzo financiero necesario para la adopción de la quimioterapia en el tratamiento de pacientes con cáncer en Colombia, en un horizonte temporal de tres años. Este documento está conformado por cuatro secciones: en la primera se identifican las tecnologías a evaluar, en la segunda sección se especifica la perspectiva, horizonte temporal y la población sobre la cual se realizó el AIP; en la sección tres se detallan los costos utilizados en el modelo, además de los escenarios planteados por los investigadores; por último, en la sección cuatro se exponen los resultados en los diferentes escenarios planteados. Este documento describe la metodología desarrollada para realizar el análisis de impacto presupuestal de 21 tecnologías para el manejo quimioterapéutico del cáncer en Colombia Este informe, sigue los lineamientos propuestos en el Manual para la Elaboración de Análisis de Impacto Presupuestal y en Manual de Participación y Deliberación publicados por IETS. A continuación, se muestran los detalles del ejercicio poblacional, de costeo y de la modelación de escenarios. Posteriormente, se presenta una interpretación de los resultados y los análisis de incertidumbre sobre los mismos. INSUMOS Y MÉTODOS: Esta sección presenta los supuestos, parámetros y métodos utilizados para el modelo de estimación del impacto presupuestal describiendo la siguiente información: Perspectiva: La perspectiva de este AIP es la del tercer pagador el cual en nuestro contexto es el Sistema General de Seguridad Social en Salud (SGSSS). Horizonte temporal: El horizonte temporal de este AIP en el caso base corresponde a un año. Adicionalmente se reportan las estimaciones del impacto presupuestal para los años 2 y 3, bajo el supuesto de inclusión en el PBS en el año 1. Población total: Para el desarrollo de este AIP se parte de la población general afiliada al SGSSS colombiano sin distinción de sexo o edad. Las estimaciones de los años 1 a 3 se calcularon de acuerdo al comportamiento del crecimiento demográfico estimado por el DANE. RESULTADOS: Se muestra el resultado consolidado para las ventiun tecnologías objeto del Análisis de Impacto Presupuestal. La tecnología que genera un mayor impacto es Oxaliplatino, con un valor por persona de $2.363.250,76 usada en 3170 pacientes, para un total de $7.491.504.923,90. El Megestrol es la tecnología con menor impacto, con un costo por persona de $ 383.791,06 y siendo usada en 34 pacientes, tiene un valor total de $ 13.048.896,00. La tretinoina es la tecnología más económica por paciente, con un valor de $ 97.996,50, es usada en 242 personas para un total de $ 23.715.153,00. DISCUSIÓN: En la práctica actual existe un volumen amplio de recobros en el caso de estos medicamentos por usos UNIRS. En algunos casos, los cambios en el mercado farmacéutico, ya sea por el retiro de medicamentos o la llegada de ellos, hace que se modifique indicaciones ya existentes en los registros y que pueden llegar a impactar estos usos, por ejemplo aquellos casos en los que existe la indicación antineplásico y se cambian por indicaciones especificas, que pueden no considerar condiciones de salud de baja incidencia. Como se ha caracterizado con anterioridad, el mercado de tecnologías sanitarias que se encuentran incluidas al plan de beneficios en salud con cargo a la UPC difiere sustancialmente al mercado de tecnologías sanitarias aún no financiadas por dicho mecanismo. La existencia de las Empresas Administradoras de Planes de Beneficios (EAPB) presume la existencia de un actor que al maximizar su beneficio, es un buen negociador que en cumplimiento de los principios del SGSSS, llega a un precio de equilibrio que maximiza el beneficio social. En cambio, los medicamentos que son sujetos a recobros al ADRES presume un precio fuera de aquel nivel en donde se maximiza al beneficio social, en la medida que no hay una función clara de monopsonio que coteje y negocie un precio de adquisición. En algunos casos puede llegar asumir sobrecostos que las EAPB al ser intermediarias, no tienen incentivos para efectuar un adecuado control.

Comparative Error-Free and Error-Prone Translesion Synthesis of N(2)-2'-Deoxyguanosine Adducts Formed by Mitomycin C and Its Metabolite, 2,7-Diaminomitosene, in Human Cells.

Mitomycin C (MC) is a cytotoxic and mutagenic antitumor agent that alkylates DNA upon reductive activation. 2,7-Diaminomitosene (2,7-DAM) is a major metabolite of MC in tumor cells, which also alkylates DNA. MC forms seven DNA adducts, including monoadducts and inter- and intrastrand cross-links, whereas 2,7-DAM forms two monoadducts. Herein, the biological effects of the dG-N(2) adducts formed by MC and 2,7-DAM have been compared by constructing single-stranded plasmids containing these adducts and replicating them in human embryonic kidney 293T cells. Translesion synthesis (TLS) efficiencies of dG-N(2)-MC and dG-N(2)-2,7-DAM were 38 ± 3 and 27 ± 3%, respectively, compared to that of a control plasmid. This indicates that both adducts block DNA synthesis and that dG-N(2)-2,7-DAM is a stronger replication block than dG-N(2)-MC. TLS of each adducted construct was reduced upon siRNA knockdown of pol η, pol κ, or pol ζ. For both adducts, the most significant reduction occurred with knockdown of pol κ, which suggests that pol κ plays a major role in TLS of these dG-N(2) adducts. Analysis of the progeny showed that both adducts were mutagenic, and the mutation frequencies (MF) of dG-N(2)-MC and dG-N(2)-2,7-DAM were 18 ± 3 and 10 ± 1%, respectively. For both adducts, the major type of mutation was G → T transversions. Knockdown of pol η and pol ζ reduced the MF of dG-N(2)-MC and dG-N(2)-2,7-DAM, whereas knockdown of pol κ increased the MF of these adducts. This suggests that pol κ predominantly carries out error-free TLS, whereas pol η and pol ζ are involved in error-prone TLS. The largest reduction in MF by 78 and 80%, respectively, for dG-N(2)-MC and dG-N(2)-2,7-DAM constructs occurred when pol η, pol ζ, and Rev1 were simultaneously knocked down. This result strongly suggests that, unlike pol κ, these three TLS polymerases cooperatively perform the error-prone TLS of these adducts.

Synthesis of Mitomycin C and Decarbamoylmitomycin C N(2) deoxyguanosine-adducts.

Mitomycin C (MC) and Decarbamoylmitomycin C (DMC) - a derivative of MC lacking the carbamate on C10 - are DNA alkylating agents. Their cytotoxicity is attributed to their ability to generate DNA monoadducts as well as intrastrand and interstrand cross-links (ICLs). The major monoadducts generated by MC and DMC in tumor cells have opposite stereochemistry at carbon one of the guanine-mitosene bond: trans (or alpha) for MC and cis (or beta) for DMC. We hypothesize that local disruptions of DNA structure from trans or cis adducts are responsible for the different biochemical responses produced by MC and DMC. Access to DNA substrates bearing cis and trans MC/DMC lesions is essential to verify this hypothesis. Synthetic oligonucleotides bearing trans lesions can be obtained by bio-mimetic methods. However, this approach does not yield cis adducts. This report presents the first chemical synthesis of a cis mitosene DNA adduct. We also examined the stereopreference exhibited by the two drugs at the mononucleotide level by analyzing the formation of cis and trans adducts in the reaction of deoxyguanosine with MC or DMC using a variety of activation conditions. In addition, we performed Density Functional Theory calculations to evaluate the energies of these reactions. Direct alkylation under autocatalytic or bifunctional conditions yielded preferentially alpha adducts with both MC and DMC. DFT calculations showed that under bifunctional activation, the thermodynamically favored adducts are alpha, trans, for MC and beta, cis, for DMC. This suggests that the duplex DNA structure may stabilize/oriente the activated pro-drugs so that, with DMC, formation of the thermodynamically favored beta products are possible in a cellular environment.

Modification of cellular DNA by synthetic aziridinomitosenes.

Two synthetic aziridinomitosenes (AZMs), Me-AZM and H-AZM, structurally related to mitomycin C (MC) were evaluated for their anticancer activity against six cancer cell lines (HeLa, Jurkat, T47D, HepG2, HL-60, and HuT-78) and tested for their DNA-modifying abilities in Jurkat cells. Cytotoxicity assays showed that Me-AZM is up to 72-fold and 520-fold more potent than MC and H-AZM, respectively. Me-AZM also demonstrated increased DNA modification over MC and H-AZM in alkaline COMET and Hoechst fluorescence assays that measured crosslinks in cellular DNA. Me-AZM and H-AZM treatment of Jurkat cells was found to sponsor significant DNA-protein crosslinks using a K-SDS assay. The results clearly indicate that the AZM C6/C7 substitution pattern plays an important role in drug activity and supports both DNA-DNA and DNA-protein adduct formation as mechanisms for inducing cytotoxic effects.

Decarbamoyl mitomycin C (DMC) activates p53-independent ataxia telangiectasia and rad3 related protein (ATR) chromatin eviction.

Interstrand crosslinks induce DNA replication fork stalling that in turn activates the ATR-dependent checkpoint and DNA repair on nuclear chromatin. Mitomycin C (MC) and Decarbamoyl Mitomycin C (DMC) induce different types of DNA crosslinks with DMC being a more cytotoxic agent. We previously reported that the novel DMC induced ß-interstrand DNA crosslinks induce a p53-independent form of cell death. The p53-independent DMC cytotoxicity associates with the activation, and subsequent depletion, of Chk1. In this study we further dissect the novel DMC signal transduction pathway and asked how it influences chromatin-associated proteins. We found that treatment with DMC, but not MC, stimulated the disassociation of ATR from chromatin and re-localization of ATR to the cytoplasm. The chromatin eviction of ATR was coupled with the formation of nuclear Rad51 foci and the phosphorylation of Chk1. Furthermore, DMC but not MC, activated expression of gadd45α mRNA. Importantly, knocking down p53 via shRNA did not inhibit the DMC-induced disassociation of ATR from chromatin or reduce the activation of transcription of gadd45α. Our results suggest that DMC induces a p53-independent disassociation of ATR from chromatin that facilitates Chk1 checkpoint activation and Rad51 chromatin recruitment. Our findings provide evidence that ATR chromatin eviction in breast cancer cells is an area of study that should be focused on for inducing p53-independent cell death.

Effect of 4-(N,N-dimethylamino)phenethyl Alcohol on Degree of Conversion and Cytotoxicity of Photo-Polymerized CQ-Based Resin Composites

The aim of this study was to evaluate the degree of conversion (DC) and the cytotoxicity of photo-cured experimental resin composites containing 4-(N,N-dimethylamino)phenethyl alcohol (DMPOH) combined to the camphorquinone (CQ) compared with ethylamine benzoate (EDAB). The resin composites were mechanically blended using 35 wt% of an organic matrix and 65 wt% of filler loading. To this matrix was added 0.2 wt% of CQ and 0.2 wt% of one of the reducing agents tested. 5x1 mm samples (n=5) were previously submitted to DC measurement and then pre-immersed in complete culture medium without 10% (v/v) bovine serum for 1 h or 24 h at 37 °C in a humidifier incubator with 5% CO2 and 95% humidity to evaluate the cytotoxic effects of experimental resin composites using the MTT assay on immortalized human keratinocytes cells. As a result of absence of normal distribution, the statistical analysis was performed using the nonparametric Kruskal-Wallis to evaluate the cytotoxicity and one-way analysis of variance to evaluate the DC. For multiple comparisons, cytotoxicity statistical analyses were submitted to Student-Newman-Keuls and DC analysis to Tukey's HSD post-hoc test (=0.05). No significant differences were found between the DC of DMPOH (49.9%) and EDAB (50.7%). 1 h outcomes showed no significant difference of the cell viability between EDAB (99.26%), DMPOH (94.85%) and the control group (100%). After 24 h no significant difference were found between EDAB (48.44%) and DMPOH (38.06%), but significant difference was found compared with the control group (p>0.05). DMPOH presented similar DC and cytotoxicity compared with EDAB when associated with CQ.

O objetivo deste estudo foi avaliar o grau de conversão (GC) e a citotoxicidade de resinas compostas experimentais utilizando o álcool 4-(N,N-dimetilamino) fenil etílico (DMPOH) associado à canforoquinona (CQ) como sistema fotoiniciador (SF) comparado à versão comercial utilizando o benzoato de etilamina (EDAB). Para tanto, as resinas compostas experimentais foram mecanicamente misturadas utilizando (em peso): 35% de matriz orgânica e 65% em peso de partículas de carga. Posteriormente, foram adicionados 0,2% de CQ e 0,2% de um dos agentes redutores testados. Amostras de 5 x 1 mm (n=5) foram previamentes submetidas à análise de GC e posteriormente, esterilizadas e colocadas no meio de cultura completo sem soro fetal bovino estéril por 1 h ou 24 h a 37 °C em encubadora com 5% de CO2 and 95% de umidade para avaliar os efeitos citotóxicos das resinas compostas experimentais utilizando o método MTT emcélulas células humanas imortalizadas de queratinócitos. Os dados de citotoxicidade foram submetidos à análise estatística de Kruskal-Wallis e de GC à análise de variância com um fator. Em virtude da ausência de normalidade, a análise estatística da citotoxicidade foi realizada utilizando-se o teste não-paramétrico de Kruskal-Wallis. Para o GC, os dados foram submetidos à análise de variaância de 1 fator. Posteriormente para múltiplas comparações, os dados de citotoxicidade foram submetidos ao teste Student-Newman-Keuls e o GC ao teste de Tukey's HSD post-hoc (=0.05). Não foi observada diferença estatística entre o GC de DMPOH (49,9%) e EDAB (50,7%). Para os resultados de 1 h não houve diferença na viabilidade celular entre EDAB (99,26%), DMPOH (94,85%) e o grupo controle (100%). Após 24 h, nenhuma diferença estatística foi encontrada entre EDAB (48,44%) e DMPOH (38,06%), entretanto, diferença significativa foi encontrada em relação ao grupo controle (p>0,05). O DMPOH apresentou GC e citotoxicidade semelhante à EDAB quando associado à CQ.

Ground reaction forces during level ground walking with body weight unloading

Background: Partial body weight support (BWS) systems have been broadly used with treadmills as a strategy for gait training of individuals with gait impairments. Considering that we usually walk on level ground and that BWS is achieved by altering the load on the plantar surface of the foot, it would be important to investigate some ground reaction force (GRF) parameters in healthy individuals walking on level ground with BWS to better implement rehabilitation protocols for individuals with gait impairments. Objective: To describe the effects of body weight unloading on GRF parameters as healthy young adults walked with BWS on level ground. Method: Eighteen healthy young adults (27±4 years old) walked on a walkway, with two force plates embedded in the middle of it, wearing a harness connected to a BWS system, with 0%, 15%, and 30% BWS. Vertical and horizontal peaks and vertical valley of GRF, weight acceptance and push-off rates, and impulse were calculated and compared across the three experimental conditions. Results: Overall, participants walked more slowly with the BWS system on level ground compared to their normal walking speed. As body weight unloading increased, the magnitude of the GRF forces decreased. Conversely, weight acceptance rate was similar among conditions. Conclusions: Different amounts of body weight unloading promote different outputs of GRF parameters, even with the same mean walk speed. The only parameter that was similar among the three experimental conditions was the weight acceptance rate. .