The Multifaceted Roles of NRF2 in Cancer: Friend or Foe?

Physiological concentrations of reactive oxygen species (ROS) play vital roles in various normal cellular processes, whereas excessive ROS generation is central to disease pathogenesis. The nuclear factor erythroid 2-related factor 2 (NRF2) is a critical transcription factor that regulates the cellular antioxidant systems in response to oxidative stress by governing the expression of genes encoding antioxidant enzymes that shield cells from diverse oxidative alterations. NRF2 and its negative regulator Kelch-like ECH-associated protein 1 (KEAP1) have been the focus of numerous investigations in elucidating whether NRF2 suppresses tumor promotion or conversely exerts pro-oncogenic effects. NRF2 has been found to participate in various pathological processes, including dysregulated cell proliferation, metabolic remodeling, and resistance to apoptosis. Herein, this review article will examine the intriguing role of phase separation in activating the NRF2 transcriptional activity and explore the NRF2 dual impacts on tumor immunology, cancer stem cells, metastasis, and long non-coding RNAs (LncRNAs). Taken together, this review aims to discuss the NRF2 multifaceted roles in both cancer prevention and promotion while also addressing the advantages, disadvantages, and limitations associated with modulating NRF2 therapeutically in cancer treatment.

Discovery of New 2-Phenylamino-3-acyl-1,4-naphthoquinones as Inhibitors of Cancer Cells Proliferation: Searching for Intra-Cellular Targets Playing a Role in Cancer Cells Survival.

A series of 2-phenylamino-3-acyl-1,4-naphtoquinones were evaluated regarding their in vitro antiproliferative activities using DU-145, MCF-7 and T24 cancer cells. Such activities were discussed in terms of molecular descriptors such as half-wave potentials, hydrophobicity and molar refractivity. Compounds 4 and 11 displayed the highest antiproliferative activity against the three cancer cells and were therefore further investigated. The in silico prediction of drug likeness, using pkCSM and SwissADME explorer online, shows that compound 11 is a suitable lead molecule to be developed. Moreover, the expressions of key genes were studied in DU-145 cancer cells. They include genes involved in apoptosis (Bcl-2), tumor metabolism regulation (mTOR), redox homeostasis (GSR), cell cycle regulation (CDC25A), cell cycle progression (TP53), epigenetic (HDAC4), cell-cell communication (CCN2) and inflammatory pathways (TNF). Compound 11 displays an interesting profile because among these genes, mTOR was significantly less expressed as compared to control conditions. Molecular docking shows that compound 11 has good affinity with mTOR, unraveling a potential inhibitory effect on this protein. Due to the key role of mTOR on tumor metabolism, we suggest that impaired DU-145 cells proliferation by compound 11 is caused by a reduced mTOR expression (less mTOR protein) and inhibitory activity on mTOR protein.

Quality of life in patients undergoing minimally invasive surgery.

OBJECTIVE: Current evidence has shown how laparoscopic surgery results in shorter hospital stay, faster recovery, and better aesthetic results. However, we do not have information on populations in Latin America and the impact that the social environment has on quality of life in patients with gynecological cancer undergoing minimally invasive surgery. To assess quality of life of patients undergoing minimally invasive surgery in a gynecologic oncology department over time and to establish the relationship with patient and treatment variables. METHODS: This cross-sectional study evaluated the quality of life of women undergoing minimally invasive surgery from August 2019 to July 2021. The FACT-G (Functional Assessment of Cancer Therapy-General) scale encompasses global quality of life and four domains of physical, social, emotional, and functional components. This scale was applied to measure quality of life in the preoperative, early operative, and late postoperative periods. Additionally, mixed models were used to compare quality of life based on demographic and clinical factors after minimally invasive surgery. RESULTS: A total of 158 patients were analyzed. Belonging to a higher socioeconomic stratum (3 vs 1) had a positive impact on the global quality of life in patients undergoing surgery with an increase of 7.6 points (p=0.011). Also, a lower Charlson Index had a positive impact of 0.393 points for the physical component of quality of life (p=0.031). For the social component of quality of life, having a partner and being part of a higher socioeconomic stratum (3 and 2 vs 1) resulted in an increase of 2.11 (p=0.005), 4.06 (p<0.05), and 2.55 (p=0.004) points, respectively. Belonging to a higher socioeconomic stratum (3 vs 1) resulted in an increase of 2.03 points (p=0.031) for the functional component of quality of life. Finally, the complexity of the procedure, or whether the procedure was ambulatory or not did not impact quality of life. CONCLUSIONS: Lower Charlson Index, having a partner, or having higher socioeconomic status are all associated with higher quality of life of patients undergoing minimally invasive surgery.

Valeriana pilosa Roots Essential Oil: Chemical Composition, Antioxidant Activities, and Molecular Docking Studies on Enzymes Involved in Redox Biological Processes.

Valeriana pilosa is usually employed in Peruvian folk medicine in the form of infusion to treat stomach pain, and has antispasmodic, relaxing, sleep-promoting, and sedative properties, as well as is an anti-inflammatory. In this study, Valeriana pilosa essential oil (VPEO) was obtained by hydrodistillation, analyzed by GC and GC/MS, and 47 compounds were identified. Major oil components were α-patchoulene (5.8%), α-humulene (6.1%), seychellene (7.6%), and patchoulol (20.8%). Furthermore, we assessed the in vitro antioxidant activities, molecular docking, and Ligand Efficiency studies on enzymes involved in cellular redox pathways such as CYP2C9, catalase, superoxide dismutase, and xanthine oxidase. Essential oil antioxidant activities were assessed by FRAP, ABTS•+, and DPPH• radical scavenging activity. VPEO displays high antioxidant activity as compared to essential oils of Valeriana jatamansi and Valeriana officinalis oil roots. In addition, molecular docking and ADMET prediction was employed to compare the absorption, metabolism, and toxicity properties of Valeriana pilosa compounds. In the molecular docking studies, limonene, p-cimene, carvone, α-cubebene, cyclosativene, α-guaiene, allo-aromadendrene, valencene, and eremophyllene were the compounds with the best docking score on CYP2C9 and xanthine oxidase. Thus, volatile components of Valeriana pilosa could be associated with the detected antioxidant activity, acting as putative inhibitors of CYP2C9 and xanthine oxidase.

Antifungal Activity and In Silico Studies on 2-Acylated Benzo- and Naphthohydroquinones.

The high rates of morbidity and mortality due to fungal infections are associated with a limited antifungal arsenal and the high toxicity of drugs. Therefore, the identification of novel drug targets is challenging due to the several resemblances between fungal and human cells. Here, we report the in vitro antifungal evaluation of two acylphenols series, namely 2-acyl-1,4-benzo- and 2-acyl-1,4-naphthohydroquinones. The antifungal properties were assessed on diverse Candida and filamentous fungi strains through the halo of inhibition (HOI) and minimal inhibitory concentration (MIC). The antifungal activities of 2-acyl-1,4-benzohydroquinone derivatives were higher than those of the 2-acyl-1,4-naphthohydroquinone analogues. The evaluation indicates that 2-octanoylbenzohydroquinone 4 is the most active member of the 2-acylbenzohydroquinone series, with MIC values ranging from 2 to 16 µg/mL. In some fungal strains (i.e., Candida krusei and Rhizopus oryzae), such MIC values of compound 4 (2 and 4 µg/mL) were comparable to that obtained by amphotericin B (1 µg/mL). The compound 4 was evaluated for its antioxidant activity by means of FRAP, ABTS and DPPH assays, showing moderate activity as compared to standard antioxidants. Molecular docking studies of compound 4 and ADMET predictions make this compound a potential candidate for topical pharmacological use. The results obtained using the most active acylbenzohydroquinones are promising because some evaluated Candida strains are known to have decreased sensitivity to standard antifungal treatments.

Hidradenoma papilífero de la vulva con componente de carcinoma in situ: reporte de caso y revisión de la bibliografía / Papilliferous hidradenoma of the vulva with carcinoma in situ component: case report and literature review

Resumen ANTECEDENTES: El cáncer de vulva es relativamente raro, representa menos del 1% de los tumores malignos de la mujer; su incidencia aumenta con la edad. La variedad más frecuente es el carcinoma escamoso (80 al 90%), seguido del melanoma. En este reporte se revisa un carcinoma de origen glandular, como el hidradenoma papilífero del tipo glándula mamaria (mammary-like) de la vulva. CASO CLÍNICO: Paciente de 50 años, con una lesión papular en la vulva de dos años de evolución, con crecimiento lento y progresivo, ocasional sensación de masa y dolor, con colposcopia negativa, sin antecedentes de patología mamaria y con una biopsia previa que reportó hidradenoma papilífero vulvar. Se trató con resección completa de la lesión, con anestesia regional, con bordes libres, no se identificó algún componente infiltrante. En la actualidad permanece sin evidencia de recaída ni requerimiento de tratamientos adicionales durante el seguimiento. CONCLUSIÓN: El hidradenoma papilífero es una lesión benigna, poco frecuente, relacionada con las glándulas anogenitales de tipo mammary-like, con buen pronóstico. El tratamiento recomendado es la escisión quirúrgica, que casi siempre es curativa.

Abstract BACKGROUND: Vulvar cancer is relatively rare, representing less than 1% of malignant tumors in women; its incidence increases with age. The most frequent variety is squamous cell carcinoma (80 to 90%), followed by melanoma. In this report we review a carcinoma of glandular origin, such as papilliferous hydradenoma of the vulva of the mammary gland (mammary-like) type. CLINICAL CASE: We present a 50-year-old patient with 2 years evolution of a papular lesion on the vulva with slow and progressive growth, intermitent sensation of mass and pain, with negative colposcopy, no history of breast pathology and with a previous biopsy that reported vulvar papilliferous hydradenoma. She was treated with complete resection of the lesion under regional anesthesia, with free margins, without identifying an infiltrating component and currently without evidence of relapse or requirement of additional treatments. CONCLUSION: Papilliferous hidradenoma is a rare benign lesion related to the mammary-like anogenital glands, with a good prognosis and its recommended treatment is surgical excision, which is generally curative.

Vitamin C (Ascorbate) and Redox Topics in Cancer.

Significance: Vitamin C (ascorbate), in regard to its effectiveness against malignancies, has had a controversial history in cancer treatment. It has been shown that in vitro and in vivo anticancer efficacy of ascorbate relies on its pro-oxidant effect mainly from an increased generation of reactive oxygen species (ROS). A growing understanding of its anticancer activities and pharmacokinetic properties has prompted scientists to re-evaluate the significance of ascorbate in cancer treatment. Recent Advances: A recent resurge in ascorbate research emerged after discovering that, at high doses, ascorbate preferentially kills Kirsten-Ras (K-ras)- and B-raf oncogene (BRAF)-mutant cancer cells. In addition, some of the main hallmarks of cancer cells, such as redox homeostasis and oxygen-sensing regulation (through inhibition of hypoxia-inducible factor-1 alpha [HIF-1α] activity), are affected by vitamin C. Critical Issues: Currently, there is no clear consensus from the literature in regard to the beneficial effects of antioxidants. Results from both human and animal studies provide no clear evidence about the benefit of antioxidant treatment in preventing or suppressing cancer development. Since pro-oxidants may affect both normal and tumor cells, the extremely low toxicity of ascorbate represents a main advantage. This guarantees the safe inclusion of ascorbate in clinical protocols to treat cancer patients. Future Directions: Current research could focus on elucidating the wide array of reactions between ascorbate and reactive species, namely ROS, reactive nitrogen species as well as reactive sulfide species, and their intracellular molecular targets. Unraveling these mechanisms could allow researchers to assess what could be the optimal combination of ascorbate with standard treatments.

Melanoma primario de cuello uterino: Reporte de caso / Primary malignant melanoma of the cervix: Case report

Resumen El melanoma primario de mucosas representa el 1% de todos los cánceres. Su localización en cuello uterino es rara y existen menos de 100 casos reportados en la literatura hasta la fecha. Los datos son limitados en cuanto su estadificación y tratamiento y su pronóstico es malo con tasas de supervivencia del 10% a 5 años. Se presenta el caso clínico de una paciente de 82 años con sangrado vaginal, con evidencia de una lesión melanótica en cuello uterino, la biopsia de la lesión reportó compromiso por tumor maligno pobremente diferenciado, con inmuno perfil que confirma melanoma maligno. Los estudios de extensión no mostraron enfermedad metastásica a distancia, se presentó el caso en junta multidisciplinaria de ginecología oncológica por lo que se indicó tratamiento con radioterapia pélvica externa exclusiva con intención paliativa para control de síntomas, teniendo en cuenta: la edad, las comorbilidades y el estado funcional ECOG (Eastern Cooperative Oncology Group) 3; luego de 10 meses de seguimiento la paciente falleció.

Abstract Primary mucosal melanoma represents 1% of all cancers, the location in the cervix is rare, there are less than 100 cases reported in the literature to date, the data is limited in terms of staging and treatment, its prognosis is poor with survival rates of 10% at 5 years. We present a clinical case of a primary melanoma of the cervix in an 82-year-old patient with vaginal bleeding with evidence of a melanotic lesion in the cervix. The biopsy of the lesion reported poorly differentiated malignant tumor involvement, with an immuno-profile that favors melanoma. Extension studies were performed that did not show distant metastatic disease, the case was presented in a multidisciplinary oncological gynecology meeting, indicating treatment with exclusive external pelvic radiotherapy with palliative intention for symptom control taking into account patient comorbidities and ECOG functional status. (Eastern Cooperative Oncology Group) 3, after 10 months of follow-up the patient died.

New 2-Acetyl-3-aminophenyl-1,4-naphthoquinones: Synthesis and In Vitro Antiproliferative Activities on Breast and Prostate Human Cancer Cells.

The reaction of 2-acyl-1,4-naphthoquinones with N,N-dimethylaniline and 2,5-dimethoxyaniline, promoted by catalytic amounts of CeCl3·7H2O under "open-flask" conditions, produced a variety of 2-acyl-3-aminophenyl-1,4-naphthoquinones structurally related to the cytotoxic 2-acetyl-3-phenyl-1,4-naphthoquinone, an inhibitor of the heat shock chaperone protein Hsp90. The members of the 2-acyl-3-aminophenyl-1,4-naphthoquinone series were isolated in good yields (63-98%). The cyclic voltammograms of the 2-acyl-3-aminophenyl-1,4-naphthoquinone exhibit two one-electron reduction waves to the corresponding radical-anion and dianion and two quasireversible oxidation peaks. The first and second half-wave potential values (E 1/2) of the members of the series are sensitive to the push-pull electronic effects of the substituents in the naphthoquinone scaffold. Furthermore, the in vitro antiproliferative properties of these new quinones were evaluated on two human cancer cells DU-145 (prostate) and MCF-7 (mammary) and a nontumorigenic HEK-293 (kidney) cell line, using the MTT colorimetric method. Two members, within the series, exhibited interesting cytotoxic activities on human prostate and mammary cancer cells.

In Vitro Inhibition of Hsp90 Protein by Benzothiazoloquinazolinequinones Is Enhanced in The Presence of Ascorbate. A Preliminary In Vivo Antiproliferative Study.

A series of benzo[g]benzothiazolo[2,3-b]quinazoline-7,12-quinones were prepared from 2-acylnaphthohydroquinones and 2-aminobenzothiazoles and were evaluated for their in vitro antiproliferative activity. After screening using the MTT reduction assay, their IC50 values were calculated on a panel of cancer cells (T24, DU-145, MCF-7). Current standard anticancer drugs were included as control, and their calculated IC50 values were 7.8 and 23.5 µM for 5-fluorouracil and tamoxifen, respectively. Non-cancer cells (AG1523) were included to assess cancer cell sensitivity and drug selectivity. Four members of the series, with IC50 values from 0.11 to 2.98 µM, were chosen for further assays. The selected quinones were evaluated regarding their effects on cancer cell proliferation (clonogenic assay) and on Hsp90 and poly(ADPribose)polymerase (PARP) protein integrity. The most active compound (i.e., 15) substantially inhibited colony forming unit (CFU) formation at 0.25 µM. In the presence of ascorbate, it induced an oxidative cleavage of Hsp90 but had no effect on PARP protein integrity. In an in vivo animal model, it discreetly increased the mean survival time (m.s.t.) of tumor-bearing mice. In light of these results, compound 15 represents a potential lead-molecule to be further developed.

Cancer Cell Sensitivity to Redox-Cycling Quinones is Influenced by NAD(P)H: Quinone Oxidoreductase 1 Polymorphism.

BACKGROUND: Cancer cell sensitivity to drugs may be associated with disturbed antioxidant enzymes expression. We investigated mechanisms of resistance by using oxidative stress-resistant MCF-7 breast cancer cells (Resox cells). Since nicotinamide adenine dinucleotide phosphate (NAD(P)H): quinone oxidoreductase-1 (NQO1) is modified in tumors and oxidative stress-resistant cells, we studied its role in cells exposed to ß-lapachone, menadione, and doxorubicin. METHODS: Normal mammary epithelial 250MK, MCF-7, and Resox cells were employed. NQO1 expression and enzyme activity were determined by quantitative polymerase chain reaction (RT-PCR), immunoblotting, and biochemical assays. Dicoumarol and gene silencing (siRNA) were used to modulate NQO1 expression and to assess its potential drug-detoxifying role. MTT (3-(4,5-dimethylthia-zolyl-2)-2,5-diphenyltetrazolium bromide) or clonogenic assays were used to investigate cytotoxicity. NQO1 variants, NQO1*1 (wt), and NQO1*2 (C609T), were obtained by transfecting NQO1-null MDA-MB-231 cell line. RESULTS: Resox cells have higher NQO1 expression than MCF-7 cells. In 250MK cells its expression was low but enzyme activity was higher suggesting a variant NQO1 form in MCF-7 cells. MCF-7 and Resox cells are heterozygous NQO1*1 (wt)/ NQO1*2 (C609T). Both NQO1 polymorphism and NQO1 overexpression are main determinants for cell resistance during oxidative stress. NQO1 overexpression increases cell sensitivity to ß-lapachone whereas NQO1*2 polymorphism triggers quinone-based chemotherapies-sensitivity. CONCLUSIONS: NQO1 influences cancer cells redox metabolism and their sensitivity to drugs. We suggest that determining NQO1 polymorphism may be important when considering the use of quinone-based chemotherapeutic drugs.

Half-Wave Potentials and In Vitro Cytotoxic Evaluation of 3-Acylated 2,5-Bis(phenylamino)-1,4-benzoquinones on Cancer Cells.

A broad range of 3-acyl-2,5-bis(phenylamino)-1,4-benzoquinones were synthesized and their voltammetric values, as well as in vitro cancer cell cytotoxicities, were assessed. The members of this series were prepared from acylbenzoquinones and phenylamines, in moderate to good yields (47-74%), through a procedure involving a sequence of two in situ regioselective oxidative amination reactions. The cyclic voltammograms of the aminoquinones exhibit two one-electron reduction waves to the corresponding radical-anion and dianion, and two quasi-reversible oxidation peaks. The first and second half-wave potential values (E1/2) of the members of the series were sensitive to the push-pull electronic effects of the substituents around the benzoquinone nucleus. The in vitro cytotoxic activities of the 3-acyl-2,5-bis(phenylamino)-1,4-benzoquinones against human cancer cells (bladder and prostate) and non-tumor human embryonic kidney cells were measured using the MTT colorimetric method. The substitution of both aniline groups, by either methoxy (electron donating effect) or fluorine (electron withdrawal effect), decreased the cytotoxicity in the aminoquinones. Among the members of the unsubstituted phenylamino series, two of the 18 compounds showed interesting anti-cancer activities. A preliminary assay, looking for changes in the expression of selected genes, was performed. In this context, the two compounds increased TNF gene expression, suggesting an association with an inflammatory-like response.

Targeting hsp90 family members: A strategy to improve cancer cell death.

A crucial process in biology is the conversion of the genetic information into functional proteins that carry out the genetic program. However, a supplementary step is required to obtain functional proteins: the folding of the newly translated polypeptides into well-defined, three-dimensional conformations. Proteins chaperones are crucial for this final step in the readout of genetic information, which results in the formation of functional proteins. In this review, a special attention will be given to the strategies targeting hsp90 family members in order to increase cancer cell death. We argue that disruption of hsp90 machinery and the further client protein degradation is the main consequence of hsp90 oxidative cleavage taking place at the N-terminal nucleotide-binding site. Moreover, modulation of Grp94 expression will be discussed as a potential therapeutic goal looking for a decrease in cancer relapses.

Chemical composition, in vitro cytotoxic and antioxidant activities of the essential oil of Peruvian Minthostachys mollis Griseb / Composición química, actividades citotóxicas y antioxidantes in vitro del aceite esencial de Minthostachys mollis Griseb peruano

The composition of the essential oil obtained by hydrodistillation from Minthostachys mollis Griseb (Lamiaceae) aerial parts was determined by GC and GC/MS. Menthone (13.2%), pulegone (12.4%), cis-dihydrocarvone (9.8%) and carvacrol acetate (8.8%) were the main essential oil components. The cytotoxic activity of the essential oil was in vitro measured using the MTT colorimetric assay. IC50 values were calculated on healthy non-tumor cells (HEK-293) and three human cancer cell lines (T24, DU-145 and MCF-7). In such latter cells, the estimated values were around 0.2 mg/mL. In addition, the antioxidant activity was determined by interaction with the stable free radical 2,2"-diphenyl-1-picrylhydrazyl. The essential oil was almost devoid of antioxidant activity indicating that its anti-proliferative action relies on other unknown mechanism.

La composición del aceite esencial obtenido por hidrodestilación a partir de partes aéreas de Minthostachys mollis Griseb (Lamiaceae) se determinó mediante GC y GC/MS. Mentona (13.2%), pulegona (12.4%), junto con cis-dihidrocarvona (9.8%) y acetato de carvacrol (8.8%) fueron los principales componentes del aceite esencial. La actividad citotóxica del aceite esencial se midió in vitro utilizando el ensayo colorimétrico MTT tanto en células sanas no tumorales (HEK-293) como en tres líneas celulares de cáncer humano (T24, DU-145 y MCF-7). Los valores de IC50 calculados fueron de alrededor de 0.2 mg/mL. Además, se determinó la actividad antioxidante por su interacción con el radical libre 2,2"-difenil-1-picrilhidrazilo. El aceite esencial tiene baja actividad antioxidante, lo que indica que su acción antiproliferativa depende de otro mecanismo desconocido.

In Vitro Inhibition of Helicobacter pylori Growth by Redox Cycling Phenylaminojuglones.

Infection by Helicobacter pylori increases 10 times the risk of developing gastric cancer. Juglone, a natural occurring 1,4-naphthoquinone, prevents H. pylori growth by interfering with some of its critical metabolic pathways. Here, we report the design, synthesis, and in vitro evaluation of a series of juglone derivatives, namely, 2/3-phenylaminojuglones, as potential H. pylori growth inhibitors. Results show that 5 out of 12 phenylaminojuglones (at 1.5 µg/mL) were 1.5-2.2-fold more active than juglone. Interestingly, most of the phenylaminojuglones (10 out of 12) were 1.1-2.8 fold more active than metronidazole, a known H. pylori growth inhibitor. The most active compound, namely, 2-((3,4,5-trimethoxyphenyl)amino)-5-hydroxynaphthalene-1,4-dione 7, showed significant higher halo of growth inhibitions (HGI = 32.25 mm) to that of juglone and metronidazole (HGI = 14.50 and 11.67 mm). Structural activity relationships of the series suggest that the nature and location of the nitrogen substituents in the juglone scaffold, likely due in part to their redox potential, may influence the antibacterial activity of the series.

Glucose-regulated protein of 94 kDa contributes to the development of an aggressive phenotype in breast cancer cells.

Grp94 plays an essential role in protein assembly. We previously suggested that Grp94 overexpression is involved in tumor aggressiveness. However, the underlying mechanisms remain unknown. Since many tumors display high Grp94 levels, we investigated the effects of tumor microenvironment on the regulation of this chaperone expression. First, we found out that hypoxia did not change Grp94 expression in the human tumor cell lines MCF-7 (breast cancer) and HepG2 (liver cancer). Second, glucose deprivation significantly increased Grp94 protein levels. Subsequently, we focused in the putative role of Grp94 in the acquisition of an aggressive phenotype by cancer cells. Using a more aggressive cancer cell model (MDA-MB-231 breast tumor cells), we found out that Grp94 knockdown using siRNA decreased the invasive capacity of cancer cells. Moreover, cells with decreased Grp94 levels displayed an enhanced sensitivity of tumor cells to doxorubicin, a standard drug in the treatment of breast cancer. Taken together, our results suggest that the expression of Grp94 is linked to tumor aggressiveness. Therefore, targeting Grp94 could be an effective way to inhibit tumor growth improving chemotherapy outcome.

Evaluation of Potential Mechanisms Controlling the Catalase Expression in Breast Cancer Cells.

Development of cancer cell resistance against prooxidant drugs limits its potential clinical use. MCF-7 breast cancer cells chronically exposed to ascorbate/menadione became resistant (Resox cells) by increasing mainly catalase activity. Since catalase appears as an anticancer target, the elucidation of mechanisms regulating its expression is an important issue. In MCF-7 and Resox cells, karyotype analysis showed that chromosome 11 is not altered compared to healthy mammary epithelial cells. The genomic gain of catalase locus observed in MCF-7 and Resox cells cannot explain the differential catalase expression. Since ROS cause DNA lesions, the activation of DNA damage signaling pathways may influence catalase expression. However, none of the related proteins (i.e., p53, ChK) was activated in Resox cells compared to MCF-7. The c-abl kinase may lead to catalase protein degradation via posttranslational modifications, but neither ubiquitination nor phosphorylation of catalase was detected after catalase immunoprecipitation. Catalase mRNA levels did not decrease after actinomycin D treatment in both cell lines. DNMT inhibitor (5-aza-2'-deoxycytidine) increased catalase protein level in MCF-7 and its resistance to prooxidant drugs. In line with our previous report, chromatin remodeling appears as the main regulator of catalase expression in breast cancer after chronic exposure to an oxidative stress.

Catalase down-regulation in cancer cells exposed to arsenic trioxide is involved in their increased sensitivity to a pro-oxidant treatment.

BACKGROUND: Pro-oxidant drugs have been proposed for treating certain cancers but the resistance developed by cancer cells to oxidative stress limits its potential use in clinics. To understand the mechanisms underlying resistance to oxidative stress, we found that the chronic exposure to an H2O2-generating system (ascorbate/menadione, Asc/Men) or catalase overexpression (CAT3 cells) increased the resistance of cancer cells to oxidative stress, likely by increasing the antioxidant status of cancer cells. METHODS: Modulation of catalase expression was performed by either protein overexpression or protein down-regulation using siRNA against catalase and aminotriazole as pharmacological inhibitor. The former approach was done by transfecting cells with a plasmid construct containing human catalase cDNA (CAT3 cells, derived from MCF-7 breast cancer cell line) or by generating resistant cells through chronic exposure to an oxidant injury (Resox cells). Cell survival was monitored by using the MTT reduction assay and further calculation of IC50 values. Protein expression was done by Western blots procedures. The formation of reactive oxygen species was performed by flow cytometry. The transcriptional activity of human catalase promoter was assessed by using transfected cells with a plasmid containing the - 1518/+ 16 promoter domain. RESULTS: Using Resox and CAT3 cells (derived from MCF-7 breast cancer cell line) as models for cancer resistance to pro-oxidative treatment, we found that arsenic trioxide (ATO) remarkably sensitized Resox and CAT3 cells to Asc/Men treatment. Since catalase is a key antioxidant enzyme involved in detoxifying Asc/Men (as shown by siRNA-mediated catalase knockdown) that is overexpressed in resistant cells, we hypothesized that ATO might regulate the expression levels of catalase. Consistently, catalase protein level is decreased in Resox cells when incubated with ATO likely by a decreased transcriptional activity of the catalase promoter. CONCLUSIONS: Our findings support the proposal that ATO should be administered in combination with pro-oxidant drugs to enhance cancer cell death in solid tumors.

Targeting Akt as strategy to kill cancer cells using 3-substituted 5-anilinobenzo[c]isoxazolequinones: A preliminary study.

Several new 3-substituted 5-anilinobenzo[c]isoxazolequinones were synthesized from 1,4-benzoquinone and alkyl- or arylcarbaldehydes by a three-step synthetic sequence. The new compounds (3a-h) were tested in vitro in normal human fibroblasts and two cancer cell lines for their cytotoxic activity. The range of IC50 values obtained for the compounds was from 3.4 to 74.2µM. Five members of the series (3b, 3d, 3e, 3f, 3g) were further selected and evaluated as inhibitors of the Hsp90 chaperoning function taking Akt as example of Hsp90 client proteins. We also evaluated the changes of intracellular levels of GSH and ATP as markers of cellular metabolic status in response to these compounds in T24 cells. One of such isoxazolquinones (3b) decreased the expression of Akt, PARP and Hsp90. Compounds 3b and 3d decreased the amount of ATP but caused no effect on GSH levels. These compounds also activated caspase-3 but an apoptosis-like type of cell death was unlike since PARP protein was not cleaved and caspase activation was substantially lower than its activation induced by staurosporine, a known caspase-3 activator in T24 cells. Taken together, preliminary results led to the discovery of an original lead compound (3b) which can be used as model to obtain new Akt inhibitors.

Clonidine administration during intraoperative monitoring for pediatric scoliosis surgery: Effects on central and peripheral motor responses.

OBJECTIVE: To study the effect of clonidine administrated as a co-analgesic during scoliosis surgery, on the neuromonitoring of spinal motor pathways. METHODS: Using standardized intraoperative monitoring, we compared the time course of peripherally and transcranially electrically evoked motor potentials (TcEMEPs) before and after injection of a single bolus of clonidine in children under total intravenous anesthesia (TIVA). MEP data were obtained from 9 patients and somatosensory evoked potentials (SSEPs) were obtained from 2 patients. The potential effect of clonidine on mean blood pressure (BP) was controlled. RESULTS: TcEMEPs from upper and lower limbs rapidly showed significant drops in amplitude after the injection of clonidine. Amplitudes reached minimal values within five minutes and remained very weak for at least 10-20minutes during which monitoring of the central motor pathways was severely compromised. SSEPs were not altered during maximal amplitude depression of the TcEMEPS. CONCLUSIONS: This is the first report showing that clonidine severely interferes with neuromonitoring of the spinal cord motor pathways. The results are discussed in light of the literature describing the effects of dexmedetomidine, another α-2 adrenergic agonist. The experimental and literature data point to central mechanisms taking place at both the spinal and cerebral levels. Therefore, clonidine as well as other α-2 adrenergic agonists should be used with extreme caution in patients for whom neuromonitoring of the motor pathways is required during surgery.