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Biomedical subjects

Esther Castaño

Publications and source records attributed to Esther Castaño.

12 recordsLinked to original sources
PubMed2006

Regulation of Akt/PKB by phosphatidylinositol 3-kinase-dependent and -independent pathways in B-cell chronic lymphocytic leukemia cells: role of protein kinase C{beta}.

Apoptosis of B cell chronic lymphocytic leukemia (B-CLL) cells is regulated by the PI-3K-Akt pathway. In the present work, we have analyzed the mechanisms of Akt phosphorylation in B-CLL cells. Freshly isolated cells present basal Akt phosphorylation, which is PI-3K-dependent, as incubation with the PI-3K inhibitor LY294002 decreased Ser-473 and Thr-308 phosphorylation in most samples analyzed (seven out of 10). In three out of 10 cases, inhibition of protein kinase C (PKC) inhibited basal Akt phosphorylation. Stromal cell-derived factor-1alpha, IL-4, and B cell receptor activation induced PI-3K-dependent Akt phosphorylation. PMA induced the phosphorylation of Akt at Ser-473 and Thr-308 and the phosphorylation of Akt substrates, independently of PI-3K in B-CLL cells. In contrast, PKC-mediated phosphorylation of Akt was PI-3K-dependent in normal B cells. Finally, a specific inhibitor of PKCbeta blocked the phosphorylation and activation of Akt by PMA in B-CLL cells. Taken together, these results suggest a model in which Akt could be activated by two different pathways (PI-3K and PKCbeta) in B-CLL cells.

Apoptosis↗
PubMed2006

TaqMan PCR assay in the control of RNA normalization in human post-mortem brain tissue.

The brain tissue obtained after death is subjected to several circumstances that can affect RNA integrity. The present study has been directed to reveal possible pitfalls and to control RNA normalization in post-mortem samples in order to recognize the limitations and minimize errors when using TaqMan PCR technology. This has been carried out in samples of the frontal cortex in a series of control and diseased cases covering Parkinson's disease, dementia with Lewy bodies pure form and common form, and Alzheimer's disease. Special attention has been paid to the value of the agonal state, post-mortem delay and pH of the nervous tissue as approximate predictors of the quality of RNA, as well as to the use of the Bioanalyzer to confirm RNA preservation. In addition, since possible disease-modified mRNAs have to be normalized with ideal unaltered RNAs, TaqMan human endogenous control plates have been used to determine the endogenous control most appropriate for the study. beta-glucuronidase (GUS) and beta-actin were good endogenous controls because their expression levels showed a small variation across a representative number of control and pathological cases. RNA stability was also analysed in a paradigm mimicking cumulative delay in tissue processing. GUS mRNA levels were not modified although beta-actin mRNA levels showed degradation at 22 h. Finally, the control of RNA degradation for the normalization of genes of interest was also tested. mRNA expression levels for superoxide dismutase 1 (SOD1) and metalloproteinase domain 22 (ADAM22) were examined at several artificial post-mortem times, and their expression levels compared with those for putative controls beta-actin and GUS. In our paradigm, the expressions of SOD1 and ADAM22 were apparently not modified when normalized with beta-actin. Yet their expression levels were reduced with post-mortem delay when values were normalized with GUS. Taken together, these observations point to practical consequences in TaqMan PCR studies. Short post-mortem delays and acceptable pH of the brain are not sufficient to rule out RNA degradation. The selection of adequate endogenous controls is pivotal in the study. beta-actin and GUS are found to be good endogenous controls in these pathologies, although GUS but not beta-actin expression levels are preserved in samples with long post-mortem delay.

Aged↗
PubMed2006

MDM2 antagonists activate p53 and synergize with genotoxic drugs in B-cell chronic lymphocytic leukemia cells.

B-cell chronic lymphocytic leukemia (B-CLL) is characterized by the accumulation of long-lived CD5(+) B lymphocytes. Several drugs currently used in the therapy of B-CLL act, at least partially, through activation of the p53 pathway. Recently, nongenotoxic small-molecule activators of p53, the nutlins, have been developed that inhibit p53-MDM2 binding. We have investigated the antitumor potential of nutlin-3 in B-CLL and find that it can activate the p53 pathway and effectively induce apoptosis in cells with wild-type p53, including cells with dysfunctional ataxia telangiectasia mutated, but not mutant p53. Nutlin-3 stabilized p53 and induced p53 target genes, including MDM2, p21(CIP1), PUMA, BAX, PIG3, and WIG1. Nutlin-3 synergized with the genotoxic drugs doxorubicin, chlorambucil, and fludarabine, but not with acadesine, which induces p53-independent apoptosis. Normal human T cells showed lower sensitivity to nutlin-3 than B-CLL cells and no synergism with the genotoxic drugs. These results suggest that MDM2 antagonists alone or in combination with chemotherapeutic drugs may offer a new treatment option for B-CLL.

Antigens, CD↗
PubMed2005

Reduced ubiquitin C-terminal hydrolase-1 expression levels in dementia with Lewy bodies.

Parkinson disease (PD) and dementia with Lewy bodies (DLB) are characterized by the accumulation of abnormal alpha-synuclein and ubiquitin in protein aggregates conforming Lewy bodies and Lewy neurites. Ubiquitin C-terminal hydrolase-1 (UCHL-1) disassembles polyubiquitin chains to increase the availability of free monomeric ubiquitin to the ubiquitin proteasome system (UPS) thus favoring protein degradation. Since mutations in the UCHL-1 gene, reducing UPS activity by 50%, have been reported in autosomal dominant PD, and UCHL-1 inhibition results in the formation of alpha-synuclein aggregates in mesencephalic cultured neurons, the present study was initiated to test UCHL-1 mRNA and protein levels in post-mortem frontal cortex (area 8) of PD and DLB cases, compared with age-matched controls. TaqMan PCR assays, and Western blots demonstrated down-regulation of UCHL-1 mRNA and UCHL-1 protein in the cerebral cortex in DLB (either in pure forms, not associated with Alzheimer disease: AD, and in common forms, with accompanying AD changes), but not in PD, when compared with age-matched controls. Interestingly, UCHL-1 mRNA and protein expressions were reduced in the medulla oblongata in the same PD cases. Moreover, UCHL-1 protein was decreased in the substantia nigra in cases with Lewy body pathology. UCHL-1 down-regulation was not associated with reduced protein levels of several proteasomal subunits, including 20SX, 20SY, 19S and 11Salpha. Yet UCHL-3 expression was reduced in the cerebral cortex of PD and DLB patients. Together, these observations show reduced UCHL-1 expression as a contributory factor in the abnormal protein aggregation in DLB, and points UCHL-1 as a putative therapeutic target in the treatment of DLB.

Aged↗
PubMed2005

[Basal cell carcinoma overlying a dermatofibroma].

The epidermis over a dermatofibroma may show changes that range from simple hyperplasia to the proliferation of basaloid cells, which can become morphologically indistinguishable from basal cell carcinoma. The existence of a true basal cell carcinoma overlying a dermatofibroma is infrequent. These basaloid proliferations have usually been considered to be the result of the inductive effect of the fibrohistiocytic proliferation of the dermatofibroma on the epithelial cells of the hair follicle; therefore, it would be a reactive phenomenon and not truly neoplastic. We describe a case of dermatofibroma that presented with a basaloid proliferation identical in appearance to a basal cell carcinoma on the overlying epidermis.

Basal Cell Carcinoma↗
PubMed2004

Amyloid-beta deposition in the cerebral cortex in Dementia with Lewy bodies is accompanied by a relative increase in AbetaPP mRNA isoforms containing the Kunitz protease inhibitor.

Deposition of amyloid-beta, the fibrillogenic product of the cell surface protein AbetaPP (amyloid-beta protein precursor), occurs in the cerebral cortex of patients with Dementia with Lewy bodies (DLB). Amyloid deposition, basically in the form of senile plaques, occurs not only in the common form (DLBc), which is defined by changes consistent with diffuse Lewy body disease accompanied by Alzheimer's disease (AD), but also in the pure form (DLBp), in which neurofibrillary tangles are absent. The present study analyses the expression of AbetaPP mRNA isoforms with (AbetaPP751 and AbetaPP770) and without (AbetaPP695) the Kunitz-type serine protease inhibitor (KPI) domain, in the cerebral cortex in DLBc (n=4), DLBp (n=4), Parkinson's disease (PD, n=5), AD (n=3 stages I-IIA, and n=4 stage VC of Braak and Braak), amyloid angiopathy (AA, n=2) and progressive supranuclear palsy (PSP, n=4) compared with age-matched controls (n=6). For this purpose, TaqMan RT-PCR assay was used on frozen post-mortem samples of the frontal cortex (area 8) obtained with short post-mortem delays (8.29+/-4.57 h) and strict RNA preservation (A260/280 of 1.78+/-0.15). A 3.66-fold, 6.67-fold, 4.28-fold and 5.24-fold increases, in the (AbetaPP751+AbetaPP770)/AbetaPP695 mRNA ratio were found in DLBc, DLBp, AD stage VC and AA, respectively, when compared with controls. No modifications in the ratio were found in PD, AD stage I-IIA and PSP. These findings suggest that alternative splicing of the AbetaPP mRNA may play a role in betaA4 amyloidogenesis in DLBp, DLBc, AD stage VC and Amyloid angiopathy.

Adult↗
PubMed2002

Keratinocyte dysplasia: an usual finding after transplantation or chemotherapy.

BACKGROUND: Keratinocyte dysplasia is a histologic abnormality that has rarely been described in the first weeks after chemotherapy or transplantation. The purpose of this study was to determine the prevalence of early keratinocyte dysplasia after chemotherapy or transplant and to analyze the relationship between dysplasia and chemotherapeutic agents, transplantation or development of acute graft vs. host disease (GvHD). METHODS: A computer search for transplant patients was performed in the Departments of Hematology, Oncology and Surgery. Only patients with a skin biopsy taken within the first days of transplantation or chemotherapeutic treatment were included in the analysis. RESULTS: Forty-four patients were included, of these 19 were women and 25 were men. Thirty-four (77.3%) of 44 biopsies showed keratinocyte dysplasia. This dysplasia was severe in 18 cases (40.9%). Cyclophosphamide was more likely to be associated with severe keratinocyte maturation disturbances (OR = 5.51) (p < 0.01) whereas cytarabine was associated with a lower risk (OR = 0.19) (p < 0.05). CONCLUSIONS: Severe keratinocyte dysplasia is a usual histologic finding in patients who have received chemotherapy and/or transplantation (40.9%). Cyclophosphamide is the main chemotherapeutic agent significantly associated with a higher risk of severe dysplasia (OR = 5.51). Causes other than GvHD or preconditioning treatment may be involved in the keratinocyte dysplasia, as it can be also found in transplanted patients who have not received chemotherapy and/or have not developed GvHD.

Adolescent↗
PubMed2002

Lichenoid nail changes as sole external manifestation of graft vs. host disease.

A 56-year-old-man who had refractory anemia with an excess of blasts underwent an allogeneic peripheral blood stem cell transplantation (PBSCT) from his brother after preparation with melphalan and fludarabin. He received GvHD (graft-vs.-host disease) prophylaxis with cyclosporine from day -1 at a daily dose of 5 mg/kg of body weight. The daily dosage was tapered gradually from day +20. On post-PBSCT day 68 he developed acute cutaneous GvHD grade 3 and acute gastrointestinal GvHD grade 2-3, which was resolved with a daily dose of 1 mg/kg of body weight of prednisone. The patient was discharged in good clinical condition and without signs of GvHD, and he started tapering his immunosuppressive treatment. By day 160 he developed oral lichen planus-like changes, with several reticulate white lesions on the oral mucosa. A biopsy specimen was microscopically consistent with lichenoid GvHD (Fig. 1). By day 150 after PBSCT, when he was being treated with CsA 100 mg once daily and prednisone 10 mg once daily, his fingernails started to grow abnormally and gradually became dystrophic and painful. Two months later his toenails became similarly affected. Although affecting all finger and toe nails, the lesions were especially important in both thumbs. Physical examination revealed multiple findings on his nails (Fig. 2): thickening, fragility, onycholysis, longitudinal striations, and even pterygium. The micological cultures were negative. A biopsy specimen showed an sparse papillary dermis lymphoid infiltrate with focal exocytosis and presence of isolated multiple necrotic keratinocytes (Fig. 3). These findings were interpreted as a lichenoid GvHD with oral and nail involvement. The patient did not have other associated cutaneous lesions. He did not develop signs or symptoms consistent with hepatic GvHD. In May 2000 thalidomide was added to the immunosuppressive therapy, at a daily dose from 100 to 300 mg according to tolerance (constipation, sedation, ...). The lesions on the oral mucous showed a substantial improvement, but the nail changes remained more or less stable. Thalidomide was discontinued after 7 months because the patient displayed numbness and tingling in the hands and feet consistent with a peripheral neuropathy. Twenty days later he stopped taking thalidomide and the oral lichenoid lesions worsened, resulting in difficulty in eating. He also developed periungueal erythema, swelling and intense pain after minimal trauma. The daily dose of prednisone increased to 20-30 mg with moderate improvement. However, the dose could not be increased because of the secondary immunosuppressive effects. Twenty-three months post-PBSCT the patient remains with intense oral and nail lichenoid lesions.

Graft vs Host Disease↗