SIAH-1 interacts with alpha-tubulin and degrades the kinesin Kid by the proteasome pathway during mitosis

SIAH-1, a human homologue of the Drosophila seven in absentia (Sina), has been implicated in ubiquitin-mediated proteolysis of different target proteins through its N-terminal RING finger domain. SIAH-1 is also induced during p53-mediated apoptosis. Furthermore, SIAH-1-transfected breast cancer cell line MCF-7 exhibits an altered mitotic process resulting in multinucleated giant cells. Now, using the two-hybrid system, we identified two new SIAH interacting proteins: Kid (kinesin like DNA binding protein) and alpha-tubulin. We demonstrate that SIAH is involved in the degradation of Kid via the ubiquitin-proteasome pathway. Our results suggest that SIAH-1 but not its N-terminal deletion mutant, affects the mitosis by an enhanced reduction of kinesin levels. Our results imply, for the first time, SIAH-1 in regulating the degradation of proteins directly implicated in the mitotic process.     

Expression of p53 and p53/47 are controlled by alternative mechanisms of messenger RNA translation initiation

P53 controls the growth and survival of cells by acting in response to a multitude of cellular stresses. It is, however, not yet fully understood how different p53 activation pathways result in either cell cycle arrest or apoptosis. We and others have described an N-terminally truncated p53 protein (p53/47) originating from a second translation initiation site in the p53 messenger RNA (mRNA), which can interact with p53 and impose altered stability and transactivation properties to p53 complexes. Here we show that cap-dependent and cap-independent mechanisms of initiation govern the translation of the p53 mRNA. Changes in synthesis of full-length p53 or p53/47 are regulated through distinct cell stress-induced pathways acting through separate regions of the p53 mRNA. We also show that some cytotoxic drugs require the presence of full-length p53 to induce apoptosis, whereas for others p53/47 is sufficient. This indicates that by harbouring alternative translation initiation sites, the p53 mRNA gives rise to different levels of the p53 isoforms which help to orchestrate the cell biological outcome of p53 activation in response to different types of cell stress. This sheds new light into the way p53 can integrate and differentiate a large multiplicity of changes in the cellular environment.     

Understanding hard-core drug use among urban Puerto Rican women in high-risk neighborhoods

The objectives of the current study were to determine the incidence and prevalence of hard-core drug (HCD) use and to explore the predictors of HCD use in a three-wave longitudinal study of women ages 18-35 living in urban areas of high drug traffic in Puerto Rico. Prevalence of HCD use was determined by positive self-report or positive toxicological tests for crack, cocaine, or heroine at baseline and follow-up periods. Incidence density was calculated using Poisson methods. Predictors of HCD use were identified using the generalized estimating equation (GEE) approach. Prevalence rates fluctuated between 16.3 at baseline and 12.6 and 14.6 at subsequent waves. Incidence of crack/cocaine or heroine ranged from 7.4 to 6.3 per 100 person years. Low education, unemployment, current alcohol use, and severe partner violence predict incident HCD use. Therefore, prevention programs for HCD use must consider strategies to promote social mobility and empowerment and to mitigate violence against women.     

In vitro activities of transition metal derivatives of ketoconazole and clotrimazole against a wild type strain of Saccharomyces cerevisiae in absence or presence of human neutrophils

In vitro activities of a series of gold, copper and ruthenium clotrimazole (CTZ, CAS 23593-75-1) and ketoconazole (KTZ, CAS 65277-42-1) derivatives were investigated individually and in combination with human neutrophils (PMNs) against a wild type strain of Saccharomyces cerevisiae. For 11 out of 12 tested metal complexes, the minimal inhibitory concentrations (MICs) at which 100 % of yeast growth was inhibited ranged from 0.75 to 3.0 micromol/L. The complex RuCl3(CTZ)3 x 2CH3OH (1f) (MIC = 0.75 micromol/L) was, although modestly, the only one able to increase the fungistatic activity of the parental drug (MIC = 1 micromol/L). On the other hand, at a sub-MIC concentration (0.5 micromol/L), the complexes [Cu(KTZ)Cl2]2 x 2H2O (2c) and RuCl2(KTZ)2 (2e) displayed synergistic fungicidal effects with PMNs whereas phagocytic capacity was enhanced by complexes [Cu(KTZ)3Cl2] (2b) and RuCl2(KTZ)2 (2e). The findings suggest that the metal-based agents may give rise to drugs with improved antifungal properties.     

Apoptosis and cell cycle disturbances induced by coumarin and 7-hydroxycoumarin on human lung carcinoma cell lines

Coumarin and 7-hydroxycoumarin have anti-tumour actions in vitro and in vivo. There are no previous reports on the cytostatic and apoptotic actions of coumarin and 7-hydroxycoumarin in non-small cell lung carcinoma (NSCLC) cell lines. Here we report on: (1) the inhibition of cell proliferation, (2) the phase in which cell cycle arrest occurs, and (3) the induction of apoptosis. Inhibition of cell proliferation was determined by 3H-thymidine incorporation. The effects on cell cycle phases were determined at 100 microg/ml of coumarin or 7-hydroxycoumarin using propidium iodide and flow cytometry. Higher concentrations were used to study apoptosis, detected by: (1) morphological cell changes, (2) subG1 peak detection and (3) Annexin-V assay. Peripheral blood mononuclear cells (PBMC) stimulated with phytohemagglutinin were used as controls. The actions of these compounds depended on drug concentrations and on histological cell type. Coumarin and 7-hydroxycoumarin inhibited cell growth by inducing cell cycle arrest in the G1 phase in all the lung carcinoma cell lines. Apoptosis required large concentrations of the coumarin compounds and was observed in adenocarcinomas. Apoptosis was not associated with intra-nucleosomal DNA fragmentation. Apoptosis was not observed in squamous lung carcinoma cell lines, but an increase in G1 cell cycle arrest was detected. In PBMC, only large concentrations of the coumarin compounds elicited a cystostatic action. Coumarins in combination with other anti-neoplastic drugs might increase the effectiveness of NSCLC treatments.     

Cytotoxic T lymphocytes in cancer and autoimmunity

Cytotoxic T lymphocytes (CTLs) are cells of the immune system that recognize and kill cells that have been infected with intracellular pathogens, allogenic cells or tumor cells. It has been reported that CTLs participate in the pathogenesis of some autoimmune diseases. After stimulation with the antigen, CTLs undergo an activation process highly regulated, which leads to the cell to acquire an effector or memory function. In this review, we indicate the cellular markers associated with the different stages of CTL-differentiation (naive, memory and effector); we indicate the distinct models of CTLs differentiation; also, the mechanisms of CTLs cytotoxicity are mentioned. Furthermore, we describe the participation of CTLs in cancer and autoimmunity; the implications of CTLs in the progression of these diseases are discussed.     

Factors associated with local recurrence after skin-sparing mastectomy and immediate breast reconstruction for invasive breast cancer

OBJECTIVE: To examine the incidence of local recurrence (LR) and factors associated with it in a population of patients who underwent skin-sparing mastectomy (SSM) and immediate reconstruction for invasive carcinoma. SUMMARY BACKGROUND DATA: The efficacy of SSM has been challenged by concerns about increased risks of LR. METHODS: A consecutive series of 173 patients (176 cancers) with invasive carcinoma underwent SSM and immediate breast reconstruction (June 1986 to December 1997). Data were analyzed by the Kaplan-Meier method, the log-rank statistic test, and the Cox proportional hazards model. RESULTS: Mean patient age was 47 +/- 9 years (27% were 40 or younger). The AJCC stages were 1 = 43%, 2 = 52%, and 3 = 5%. Thirty percent of tumors were poorly differentiated. With a median follow-up of 73 months, the LR rate was 4.5%. The mean local relapse-free interval was 26 months. Seventy-five percent of patients who presented with LR developed distant metastases and died of disease within a mean of 21 months. On univariate analysis, factors associated with higher LR rate were tumor stage 2 or 3, tumor size larger than 2 cm, node-positive disease, and poor tumor differentiation. Actuarial 1-, 3-, and 5-year overall survival rates were 98%, 94%, and 88%, respectively. On multivariate analysis, factors associated with decreased survival were advanced stage, presence of LR, and absence of hormone therapy. LR was a highly significant predictor of tumor-related death. CONCLUSIONS: There is a low incidence of LR after SSM, and it is associated with advanced disease at presentation. LR is an independent risk factor for tumor-related death.