A Pilot Study Evaluating Organochlorine and Organophosphate Pesticide Exposure in Children and Adolescents of Mexican Descent Residing in Hidalgo County, Texas.

Children and adolescents of Mexican descent residing in Hidalgo County (TX) were evaluated for exposure to organochlorine (OC) and organophosphate (OP) pesticides. A convenience sample of 60 participants enrolled in our pilot study. The lipid-adjusted serum concentrations of nine OC metabolites and creatinine-adjusted urinary concentrations of six OP metabolites were measured and compared with data from the Centers for Disease Control and Prevention's Fourth Report on Human Exposure to Environmental Chemicals. Descriptive statistics were used to summarize the concentration levels for each metabolite. Study participants were aged 5-18 years. For most of the OC and OP metabolites, our findings showed that participants had concentration levels within the distributional range of the national data. However, notable outlying levels (greater than the 95th percentile in the Fourth Report) were identified for the following OC metabolites: gamma-hexachlorocyclohexane, p,p'-dichlorodiphenyldichloroethene, and p,p'-dichlorodiphenyltrichloroethane. Among the children aged 5-11 years, one child had an outlying value for the OP metabolite: dimethylphosphate. Our findings on the levels of OC and OP pesticide exposure enhances the credibility of national estimates, and can serve as baselines for children and adolescents of Mexican descent residing in Lower Rio Grande Valley. Furthermore, our study contributes to the lacunae of knowledge regarding environmental exposures and presses further investigation of outlying OC and OP exposure levels.

Associations between body size and serum estradiol and sex hormone-binding globulin levels in premenopausal African American women.

CONTEXT: African American (AA) women have the highest rates of premenopausal breast cancer; however, it is unclear whether body size contributes to the hormonal patterns potentially associated with increased breast cancer risk in these women. OBJECTIVE: To characterize the association between body size and serum levels of estradiol and sex hormone-binding globulin (SHBG) levels in a sample of premenopausal AA women. DESIGN: A total of 164 premenopausal AA women who were not pregnant or breastfeeding were recruited for this study. Serum samples were collected during the early follicular phase, and trained staff collected body size measurements. Multiple linear regression models were performed to assess potential associations. MAIN OUTCOME MEASURES: Serum estradiol and SHBG levels. RESULTS: Many (81%) of the women enrolled were overweight or obese. Both waist-to-hip ratio (WHR) (ß = 2.68, P = .008) and waist circumference (WC) (ß = 2.02, P = .046) were positively associated with higher levels of estradiol. All measures of body was significantly and inversely associated with SHBG levels (all P < .05). CONCLUSIONS: Premenopausal AA women with higher WHR or larger WC may have higher levels of estradiol and lower levels of SHBG. Thus, WHR or WC may be better indicators for assessing hormonal patterns implicated in breast cancer pathogenesis in these women.

Effective killing of leukemia cells by the natural product OSW-1 through disruption of cellular calcium homeostasis.

3ß,16ß,17α-Trihydroxycholest-5-en-22-one 16-O-(2-O-4-methoxybenzoyl-ß-D-xylopyranosyl)-(1→3)-2-O-acetyl-α-L-arabinopyranoside (OSW-1) is a natural product with potent antitumor activity against various types of cancer cells, but the exact mechanisms of action remain to be defined. In this study, we showed that OSW-1 effectively killed leukemia cells at subnanomolar concentrations through a unique mechanism by causing a time-dependent elevation of cytosolic Ca(2+) prior to induction of apoptosis. A mechanistic study revealed that this compound inhibited the sodium-calcium exchanger 1 on the plasma membrane, leading to an increase in cytosolic Ca(2+) and a decrease in cytosolic Na(+). The elevated cytosolic Ca(2+) caused mitochondrial calcium overload and resulted in a loss of mitochondrial membrane potential, release of cytochrome c, and activation of caspase-3. Furthermore, OSW-1 also caused a Ca(2+)-dependent cleavage of the survival factor GRP78. Inhibition of Ca(2+) entry into the mitochondria by the uniporter inhibitor RU360 or by cyclosporin A significantly prevented the OSW-1-induced cell death, indicating the important role of mitochondria in mediating the cytotoxic activity. The extremely potent activity of OSW-1 against leukemia cells and its unique mechanism of action suggest that this compound may be potentially useful in the treatment of leukemia.

High hepatitis B virus infection in B-cell lymphoma tissue and its potential clinical relevance.

Our previous studies found that patients with B-cell non-Hodgkin lymphoma (NHL) had a higher incidence of hepatitis B virus (HBV) infection in serum than patients with T-cell NHL or other cancers. We sought to identify a possible role of HBV infection in B-cell NHL tumorigenesis and to understand its underlying clinical relevance. Fresh and paraffin-embedded primary tumor tissue from patients with NHL as well as from those with other lymphatic system diseases were investigated by PCR and immunohistochemistry. Many more patients with B-cell lymphoma whose serum was positive for hepatitis B surface antigen (HBsAg) were also positive for HBV-DNA than were those with T-cell NHL or other lymphatic system diseases whose serum was positive for HBsAg, in both fresh (55 vs. 15.4%) and paraffin-embedded (38.3 vs. 11.8%) tissue. Positive expression of the HBV-associated proteins HBsAg and hepatitis B core antigen was found in B-cell NHL lymphocytes and endothelial cells. Only 8.3% of patients with B-cell NHL who were negative for HBsAg but positive for other HBV markers were positive for HBV-DNA in tumor tissue. These results suggest that chronic HBV infection in lymph nodes could be associated with B-cell lymphoma.

Stromal control of cystine metabolism promotes cancer cell survival in chronic lymphocytic leukaemia.

Tissue stromal cells interact with leukaemia cells and profoundly affect their viability and drug sensitivity. Here we show a biochemical mechanism by which bone marrow stromal cells modulate the redox status of chronic lymphocytic leukaemia (CLL) cells and promote cellular survival and drug resistance. Primary CLL cells from patients exhibit a limited ability to transport cystine for glutathione (GSH) synthesis owing to a low expression level of Xc-transporter. In contrast, bone marrow stromal cells effectively import cystine and convert it to cysteine, which is then released into the microenvironment for uptake by CLL cells to promote GSH synthesis. The elevated level of GSH enhances leukaemia cell survival and protects them from drug-induced cytotoxicity. Furthermore, disabling this protective mechanism significantly sensitizes CLL cells to drug treatment in the stromal environment. This stromal-leukaemia interaction is critical for CLL cell survival and represents a key biochemical pathway for effectively targeting leukaemia cells to overcome drug resistance in vivo.

A randomized parallel-group dietary study for stages II-IV ovarian cancer survivors.

OBJECTIVE: Few studies have examined the dietary habits of ovarian cancer survivors. Therefore, we conducted a study to assess the feasibility and impact of two dietary interventions for ovarian cancer survivors. METHODS: In this randomized, parallel-group study, 51 women (mean age, 53 years) diagnosed with stages II-IV ovarian cancer were recruited and randomly assigned to a low fat, high fiber (LFHF) diet or a modified National Cancer Institute diet supplemented with a soy-based beverage and encapsulated fruit and vegetable juice concentrates (FVJCs). Changes in clinical measures, serum carotenoid and tocopherol levels, dietary intake, anthropometry, and health-related quality of life (HRQOL) were assessed with paired t-tests. RESULTS: The recruitment rate was 25%, and the retention rate was 75% at 6 months. At baseline, 28% and 45% of women met guidelines for intake of fiber and of fruits and vegetables, respectively. After 6 months, total serum carotenoid levels and α- and ß-carotene concentrations were significantly increased in both groups (P<0.01); however, ß-carotene concentrations were increased more in the FVJC group. Serum ß-cryptoxanthin levels, fiber intake (+5.2g/day), and daily servings of juice (+0.9 servings/day) and vegetables (+1.3 servings/day) were all significantly increased in the LFHF group (all P<0.05). Serum levels of albumin, lutein and zeaxanthin, retinol, and retinyl palmitate were significantly increased in the FVJC group (all P<0.05). No changes in cancer antigen-125, anthropometry, or HRQOL were observed. CONCLUSION: Overall, this study supports the feasibility of designing dietary interventions for stages II-IV ovarian cancer survivors and provides preliminary evidence that a low fat high fiber diet and a diet supplemented with encapsulated FVJC may increase phytonutrients in ovarian cancer survivors.

Metabolic alterations in cancer cells and therapeutic implications.

Cancer metabolism has emerged as an important area of research in recent years. Elucidation of the metabolic differences between cancer and normal cells and the underlying mechanisms will not only advance our understanding of fundamental cancer cell biology but also provide an important basis for the development of new therapeutic strategies and novel compounds to selectively eliminate cancer cells by targeting their unique metabolism. This article reviews several important metabolic alterations in cancer cells, with an emphasis on increased aerobic glycolysis (the Warburg effect) and glutamine addiction, and discusses the mechanisms that may contribute to such metabolic changes. In addition, metabolic alterations in cancer stem cells, mitochondrial metabolism and its influence on drug sensitivity, and potential therapeutic strategies and agents that target cancer metabolism are also discussed.

The Warburg effect and its cancer therapeutic implications.

Increased aerobic glycolysis in cancer, a phenomenon known as the Warburg effect, has been observed in various tumor cells and represents a major biochemical alteration associated with malignant transformation. Although the exact molecular mechanisms underlying this metabolic change remain to be elucidated, the profound biochemical alteration in cancer cell energy metabolism provides exciting opportunities for the development of therapeutic strategies to preferentially kill cancer cells by targeting the glycolytic pathway. Several small molecules capable of inhibiting glycolysis in experimental systems have been shown to have promising anticancer activity in vitro and in vivo. This review article provides a brief summary of our current understanding of the Warburg effect, the underlying mechanisms, and its influence on the development of therapeutic strategies for cancer treatment.

A unique vertebrate histone H1-related protamine-like protein results in an unusual sperm chromatin organization.

Protamine-like proteins constitute a group of sperm nuclear basic proteins that have been shown to be related to somatic linker histones (histone H1 family). Like protamines, they usually replace the chromatin somatic histone complement during spermiogenesis; hence their name. Several of these proteins have been characterized to date in invertebrate organisms, but information about their occurrence and characterization in vertebrates is still lacking. In this sense, the genus Mullus is unique, as it is the only known vertebrate that has its sperm chromatin organized by virtually only protamine-like proteins. We show that the sperm chromatin of this organism is organized by two type I protamine-like proteins (PL-I), and we characterize the major protamine-like component of the fish Mullus surmuletus (striped red mullet). The native chromatin structure resulting from the association of these proteins with DNA was studied by micrococcal nuclease digestion as well as electron microscopy and X-ray diffraction. It is shown that the PL-I proteins organize chromatin in parallel DNA bundles of different thickness in a quite distinct arrangement that is reminiscent of the chromatin organization of those organisms that contain protamines (but not histones) in their sperm.

OSW-1: a natural compound with potent anticancer activity and a novel mechanism of action.

The naturally occurring compound 3beta,16beta,17alpha-trihydroxycholest-5-en-22-one 16-O-(2-O-4-methoxybenzoyl-beta-D-xylopyranosyl)-(1-->3)-(2-O-acetyl-alpha-L-arabinopyranoside) (OSW-1) is found in the bulbs of Ornithogalum saudersiae and is highly cytotoxic against tumor cell lines. Using various human cancer and nonmalignant cell lines, we investigated the anticancer activity and selectivity of OSW-1 and its underlying mechanisms of action. OSW-1 exhibited extremely potent cytotoxic activity against cancer cells in vitro. Nonmalignant cells were statistically significantly less sensitive to OSW-1 than cancer cells, with concentrations that cause a 50% loss of cell viability 40-150-fold greater than those observed in malignant cells. Electron microscopy and biochemical analyses revealed that OSW-1 damaged the mitochondrial membrane and cristae in both human leukemia and pancreatic cancer cells, leading to the loss of transmembrane potential, increase of cytosolic calcium, and activation of calcium-dependent apoptosis. Clones of leukemia cells with mitochondrial DNA defects and respiration deficiency that had adapted the ability to survive in culture without mitochondrial respiration also were resistant to OSW-1. In vitro analysis revealed that OSW-1 effectively killed primary leukemia cells from chronic lymphocytic leukemia patients with disease refractory to fludarabine. The promising anticancer activity of OSW-1 and its unique mechanism of action make this compound worthy of further investigation for its potential to overcome drug resistance.

Analysis of the stability and function of nucleoplasmin through cysteine mutants.

Xenopus laevis nucleoplasmin is a pentameric nuclear chaperone. The relation between the structure and the multifunctional aspects of the molecule has not yet been clearly established. In the course of analysing a C-terminally His-tagged recombinant version of the region equivalent to the trypsin resistant core (r-NP142) of the molecule, we found that this domain exhibited a substantially decreased oligomerization potential. To better understand the role of the three cysteines of nucleoplasmin on its pentameric functional structure, we have selectively mutated these residues to serine and generated three mutants (C15S, C35S, and C45S) both for the complete recombinant nucleoplasmin (r-NP) and the truncated r-NP142 non-tagged forms. We demonstrate that there are no disulphide bridges stabilizing either the monomer or the pentamer. Neither C15S nor C35S has any structural effects, while the mutation C45S abolishes the ability of r-NP142 to pentamerize. This structural impairment suggests that hydrophobic interactions of Cys 45 are critical for the stability of the protein. Our studies allow to analyse for the first time the structural and functional properties of nucleoplasmin in its monomeric form.

Interaction of nucleoplasmin with core histones.

Nucleoplasmin is one of the most abundant proteins in Xenopus laevis oocytes, and it has been involved in the chromatin remodeling that takes place immediately after fertilization. This molecule has been shown to be responsible for the removal of the sperm-specific proteins and deposition of somatic histones onto the male pronuclear chromatin. To better understand the latter process, we have used sedimentation velocity, sedimentation equilibrium, and sucrose gradient fractionation analysis to show that the pentameric form of nucleoplasmin binds to a histone octamer equivalent consisting of equal amounts of the four core histones, H2A, H2B, H3, and H4, without any noticeable preference for any of these proteins. Removal of the histone N-terminal "tail" domains or the major C-terminal polyglutamic tracts of nucleoplasmin did not alter these binding properties. These results indicate that interactions other than those electrostatic in nature (likely hydrophobic) also play a critical role in the formation of the complex between the negatively charged nucleoplasmin and positively charged histones. Although the association of histones with nucleoplasmin may involve some ionic interactions, the interaction process is not electrostatically driven.

Nucleoplasmin interaction with protamines. Involvement of the polyglutamic tract.

Different recombinant forms of nucleoplasmin including truncations at the carboxyl-terminal end of the molecule (r-NP121, r-NP142) have been expressed and purified. All of them were found to oligomerize, forming pentameric complexes which, according to their hydrodynamic properties, can be modeled by oblate ellipsoids of constant width. In this model, the highly charged carboxyl ends appear to be arranged around a pentameric core along the plane defined by the major axes of the ellipsoid. Importantly, all the recombinant forms appear to be able to decondense protamine-containing sperm nuclei. However, although the stoichiometry with which protamines bind to these forms appears to be constant (2.5 mol of protamine/mol of nucleoplasmin pentamer), the efficiency with which they remove protamines from the sperm DNA decreases in the following order: o-NP > r-NP142 > or = r-NP >> r-NP121. Therefore, the main polyglutamic tract of nucleoplasmin (which is absent in r-NP121), while enhancing the efficiency of protamine removal, is not indispensable for sperm chromatin decondensation in the biological model we have used.