Protective and nonprotective human immunoglobulin M monoclonal antibodies to Cryptococcus neoformans glucuronoxylomannan manifest different specificities and gene use profiles

The features of protective murine antibodies to the Cryptococcus neoformans capsular polysaccharide glucuronoxylomannan (GXM) have been rigorously investigated; however, the characteristics of protective human antibodies to GXM have not been defined. We produced monoclonal antibodies (MAbs) from XenoMouse mice (transgenic mice that express human immunoglobulin M [IgM], IgG2, and kappa) which were immunized with a C. neoformans serotype D strain 24067 GXM-diphtheria toxoid conjugate. This study reports the specificity and efficacy of three human IgM MAbs, G14, G15, and G19, generated from these mice. Each MAb was specific for GXM, but G14 and G19 had different specificity based on their binding to serotype A strain H99 and SB4 GXMs, to which G15 did not bind. Nucleic acid sequence analysis revealed that G15 uses V(H)3-64 in the germ line configuration. G14 and G19 use V(H)6-1, which has somatic mutations. All of the MAbs use V kappa DPK22/A27. Studies of MAb efficacy in BALB/c mice showed that administration of 0.1 mg, but not 1 or 0.01 mg, of G15 prolonged survival against lethal C. neoformans strain 24067 challenge, whereas G14 and G19 were not protective at any dose. This panel of MAbs illustrates that serotype D GXM has epitopes that elicit human antibodies that can be either protective or nonprotective. Our findings suggest that V(H) gene use may influence GXM specificity and efficacy, and they provide insights into the possible contribution that V(H) gene use may have in resistance and susceptibility to cryptococcosis.     

Immunogenicity and efficacy of Cryptococcus neoformans capsular polysaccharide glucuronoxylomannan peptide mimotope-protein conjugates in human immunoglobulin transgenic mice

Peptide mimotopes of capsular polysaccharides have been proposed as antigens for vaccines against encapsulated pathogens. In this study, we determined the antibody response to and efficacy of P13, a peptide mimetic of the Cryptococcus neoformans capsular polysaccharide glucuronoxylomannan (GXM), in mice that produce human antibodies. P13 was conjugated to tetanus toxoid (TT) or diphtheria toxoid (DT) and administered subcutaneously in Alhydrogel with or without CpG to mice transgenic for human immunoglobulin loci (XenoMouse mice) and expressing either immunoglobulin G2 (IgG2) (G2 mice) or IgG4 (G4 mice). Mice were vaccinated and revaccinated two or three times. The serum antibody responses of the mice to GXM and P13 and antibody idiotype expression were analyzed by an enzyme-linked immunosorbent assay. The results showed that both P13-TT and P13-DT were antigenic, inducing a mimetic response to P13 in both G2 and G4 mice, and immunogenic, inducing a mimotope response including VH3 (idiotype)-positive antibodies to GXM in G2 but not G4 mice. CpG led to higher titers of IgG to P13 and GXM in P13-TT-vaccinated G2 mice. C. neoformans challenge of P13-protein conjugate-vaccinated and control G2 mice induced anamnestic IgG- and VH3-positive responses to GXM and was associated with a significantly decreased risk of death and a prolongation of survival in P13-DT-vaccinated mice compared to phosphate-buffered saline-treated or protein carrier-vaccinated mice. These findings reveal that P13 elicited a human antibody response with VH3 expression in human immunoglobulin transgenic mice that has been observed for human antibodies to GXM and support the concept that peptide mimotope-based vaccines may hold promise for the treatment of C. neoformans infections.     

Terpenoids and breast cancer chemoprevention

Cancer chemoprevention is defined as the use of natural or synthetic agents that reverse, suppress or arrest carcinogenic and/or malignant phenotype progression towards invasive cancer. Phytochemicals obtained from vegetables, fruits, spices, herbs and medicinal plants, such as terpenoids, carotenoids, flavanoids, phenolic compounds, and other groups of compounds have shown promise in suppressing experimental carcinogenesis in various organs. Recent studies have indicated that mechanisms underlying chemopreventive action may include combinations of anti-oxidant, anti-inflammatory, immune-enhancing, and anti-hormone effects. Further, modification of drug-metabolizing enzymes, and influences on cell cycling and differentiation, induction of apoptosis, and suppression of proliferation and angiogenesis that play a role in the initiation and secondary modification of neoplastic development, have also been under investigation as possible mechanisms. This review will highlight the biological effects of terpenoids as chemopreventive agents on breast epithelial carcinogenesis, and the utility of intermediate biomarkers as indicators of premalignancy. Selected breast chemoprevention trials are discussed with a focus on strategies for trial design, and clinical outcomes. Future directions in the field of chemoprevention are proposed based on recently acquired mechanistic insights into breast carcinogenesis.     

Molecular targets of curcumin for cancer therapy: an updated review

In recent years, natural edible products have been found to be important therapeutic agents for the treatment of chronic human diseases including cancer, cardiovascular disease, and neurodegeneration. Curcumin is a well-known diarylheptanoid constituent of turmeric which possesses anticancer effects under both pre-clinical and clinical conditions. Moreover, it is well known that the anticancer effects of curcumin are primarily due to the activation of apoptotic pathways in the cancer cells as well as inhibition of tumor microenvironments like inflammation, angiogenesis, and tumor metastasis. In particular, extensive studies have demonstrated that curcumin targets numerous therapeutically important cancer signaling pathways such as p53, Ras, PI3K, AKT, Wnt-β catenin, mTOR and so on. Clinical studies also suggested that either curcumin alone or as combination with other drugs possess promising anticancer effect in cancer patients without causing any adverse effects. In this article, we critically review the available scientific evidence on the molecular targets of curcumin for the treatment of different types of cancer. In addition, we also discuss its chemistry, sources, bioavailability, and future research directions.     

Prognostic significance of positive surgical margins in patients with extraprostatic carcinoma after radical prostatectomy

BACKGROUND: A significant number of prostate adenocarcinoma patients undergoing radical prostatectomy are found to have microscopic extraprostatic disease extension. A majority of these patients have focal extraprostatic extension limited to one or both sides of the prostate. In addition, positive surgical margins are a common pathologic finding in this patient subgroup. In the current study, the authors evaluated the impact of positive surgical margins as an independent predictive factor for prostate specific antigen (PSA) progression in patients with pT3a/b N0M0 carcinoma. METHODS: The Mayo Clinic prostate cancer registry list provided 1202 patients with pT3a/b NO prostate carcinoma (no seminal vesicle or regional lymph node involvement) who underwent a radical prostatectomy between 1987-1995. To reduce confounding variables, patients who received preoperative therapy or adjuvant therapy were excluded, resulting in 842 patients who were eligible for analysis. RESULTS: A total of 354 patients (42%) had > or = 1 positive surgical margins whereas 488 patients (58%) demonstrated no margin involvement. The sites of margin positivity were as follows: apex (n = 163), base (n = 47), posterior prostate (n = 227), and anterior prostate (n = 11). A total of 111 patients had > or = 2 positive surgical margins. The 5-year survival free of clinical recurrence and/or biochemical failure (postoperative PSA level > 0.2 ng/mL) for patients with no positive surgical margins was 76% and was 65% for patients with 1 positive surgical margin (P = 0.0001). There was no significant difference in biochemical disease progression between patients with 1 versus those with > or = 2 surgical margins (65% vs. 62%). Multivariate analysis revealed that positive surgical margins were a significant predictor (P = 0.0017) of clinical disease recurrence and biochemical failure (relative risk, 1.55; 95% confidence interval, 1.18-2.04) after controlling for preoperative PSA, Gleason score, and DNA ploidy. CONCLUSIONS: In the current study, positive surgical margins were found to be a significant predictor of disease recurrence in patients with pT3a/b NO prostate carcinoma, a finding that is independent of PSA, Gleason score, and DNA ploidy. The benefit of adjuvant therapy in optimizing recurrence-free survival remains to be tested.     

Vanadium-mediated suppression of diethylnitrosamine-induced chromosomal aberrations in rat hepatocytes and its correlation with induction of hepatic glutathione and glutathione S-transferase

Vanadium, a dietary micronutrient, has recently been found to possess a potent antitumor activity during chemically induced rat liver carcinogenesis. In the present study, attempts have been made to understand the basic mechanism of the antitumor response of vanadium by monitoring its effect on chromosomal aberrations (CA) in rat liver cells during the early preneoplastic steps of diethylnitrosamine (DENA)-induced hepatocarcinogenesis. Supplementary vanadium at 0.5 ppm was found to afford a unique protection against DENA-evoked CA 96 h after DENA injection. Concurrent administration of glutathione (GSH) at 200 mg/kg 2 h before DENA treatment potentiated the suppressive effect of vanadium against CA when the rats were sacrificed 96 h after the carcinogenic insult. Pretreatment nf rate with buthionine sulfoximine (890 mg/kg) and/or diethylmaleate (600 mg/kg) 0.5 or 2 h prior to DENA injection resulted in a significant inhibition of vanadium-mediated protection of CA with a concomitant fall in hepatic GSH level. Rats given injection of bromosulfophthalein (250 mg/kg), a substrate inhibitor of glutathione S-transferase (GST), 0.5 h before DENA treatment displayed a prominent suppression of the protective effect of vanadium on DENA-induced CA. Long-term supplementation of vanadium also triggered protective effect against the induction of CA 15, 30 or 45 days following DENA treatment which was maximally observed on structural aberrations followed by numerical aberrations. At these time points, vanadium was found to lower the mitotic index of hepatic cells which was otherwise elevated with DENA alone. Vanadium restored DENA-dependent decrement in the ratio of polychromatic erythrocytes (PCE) to normochromatic erythrocytes (NCE) in rat liver cells. The DENA-induced increased frequency of micronucleated PCE as well as NCE was also attenuated following vanadium supplementation. The anticlastogenic effect of vanadium was found to be parallel to its ability to induce the activity of hepatic GST with a concurrent induction of hepatic GSH pool which were rather decreased in DENA control group. The results of this study, thus, provide evidence that vanadium-dependent induction of GSH-mediated GST-catalyzed detoxificational capacity of the host is presumably related to its suppressive effect against CA. This may explain, in part, the antitumor efficacy of this trace element.     

c-Jun N-terminal kinases mediate reactivation of Akt and cardiomyocyte survival after hypoxic injury in vitro and in vivo

Akt is a central regulator of cardiomyocyte survival after ischemic injury in vitro and in vivo, but the mechanisms regulating Akt activity in the postischemic cardiomyocyte are not known. Furthermore, although much is known about the detrimental role that the c-Jun N-terminal kinases (JNKs) play in promoting death of cells exposed to various stresses, little is known of the molecular mechanisms by which JNK activation can be protective. We report that JNKs are necessary for the reactivation of Akt after ischemic injury. We identified Thr450 of Akt as a residue that is phosphorylated by JNKs, and the phosphorylation status of Thr450 regulates reactivation of Akt after hypoxia, apparently by priming Akt for subsequent phosphorylation by 3-phosphoinositide-dependent protein kinase. The reduction in Akt activity that is induced by JNK inhibition may have significant biological consequences, as we find that JNKs, acting via Akt, are critical determinants of survival in posthypoxic cardiomyocytes in culture. Furthermore, in contrast to selective p38-mitogen-activated protein kinase inhibition, which was cardioprotective in vivo, concurrent inhibition of both JNKs and p38-mitogen-activated protein kinases increased ischemia/reperfusion injury in the heart of the intact rat. These studies demonstrate that reactivation of Akt after resolution of hypoxia and ischemia is regulated by JNKs and suggest that this is likely a central mechanism of the myocyte protective effect of JNKs.     

Pathological Changes in Acute Coronary Syndromes: The Role of Statin Therapy in the Modulation of Inflammation,Endothelial Function and Coagulation

Considerable progress has been made in our understanding of the pathophysiology of coronary artery disease (CAD), their acute presentations as acute coronary syndromes (ACS) and the role of LDL cholesterol. In particular there is clear evidence that atherosclerosis is far from being a process that leads to an amorphous flow limiting lesion on an angiogram, but rather involves a complex interplay between the endothelium, inflammatory cells and the coagulation cascade occurring throughout the coronary vascular bed. While a culprit flow limiting lesion may be effectively treated by a drug eluting stent or coronary bypass surgery, this will have little impact on the global molecular processes that determine recurrent plaque instability at non-culprit sites. The search for systemic long term therapy, which is safe and effective and reduces the changes in inflammation, endothelial function and thrombosis that are the hallmark of ACS, has pushed statins to the forefront. A number of recent clinical trials have shown the benefits of early statin therapy in the treatment of ACS. In addition to their effects on LDL cholesterol, statins have a number of properties collectively referred to as pleiotropic effects, which enable them to modulate the adverse biological changes that are associated with ACS. The purpose of this review is to acquaint the reader with the biological changes that accompany ACS, highlight how these pathways may be modulated for clinical benefit by statins and identify potential novel targets for future therapy.Abbreviated abstract. Acute coronary syndromes are associated with pathological changes in inflammation, endothelial function, and coagulation, and many of these are attenuate by statins in a lipid independent manner. In light of recent clinical trials showing the early benefit of statin therapy in ACS, this review discusses how the pleiotropic effects of statins may result in early clinical benefit.