19667728
Protection against malignant conversion in SENCAR mouse skin by all trans retinoic acid: inhibition of the ras p21-processing enzyme farnesyltransferase and Ha-ras p21 membrane localization.
Many studies have shown that all trans retinoic acid (RA) exhibits significant protective effects against mouse skin tumor promotion and spontaneous as well as enhanced malignant conversion. In a recently completed study, we showed that under treatments in which papillomas on SENCAR mouse skin are induced at low and high probabilities to convert to malignant carcinomas, RA affords significant protection against both tumor promotion and subsequent malignant conversion. More than 95% of these mouse skin papillomas and carcinomas have been shown to contain point mutation at the 61 codon of Ha-ras oncogene. The ras oncogene encodes a p21 protein that, in its mutated form, transforms mammalian cells only when p21 is at the inner surface of the plasma membrane, by a series of enzymatic reactions in which the initial step is catalyzed by farnesyltransferase (FTase). In this study, we assessed whether the protective effect of RA against malignant conversion involves the inhibition of ras p21 processing in those tumors that contain the activated ras oncogene. The FTase activity and the levels of cytosolic and membrane-bound Ha-ras p21 were determined in all papillomas and carcinomas obtained from acetone- or RA-treated animals. No matter how the data were analyzed and what comparisons were considered, in all the protocols used, compared with controls, papillomas and carcinomas obtained from RA-treated groups showed significantly decreased (P < 0.01-0.001) FTase activity. Furthermore, the tissue samples from RA-treated groups in different protocols also showed significantly diminished membrane localization of Ha-ras p21, with a concomitant increase in cytosolic Ha-ras p21 levels. The analysis of these data also showed that in all the protocols used, the increased FTase activity and membrane localization of Ha-ras p21 were associated with the induction of papillomas and their subsequent malignant conversion to squamous cell carcinomas. Taken together, these results indicate a strong correlation between the inhibition of ras p21 farnesylation because of a decrease in FTase activity by RA and its protective effect against malignant conversion of papillomas to carcinomas. Based on the results of this study, it is tempting to suggest that clinical trials evaluating the preventive or therapeutic potential of retinoids may be directed more toward those clinical malignancies that are known to contain the activated ras oncogene.
37464296
Introduction to Special Issue on Molecular Basis for Cancer Prevention with Bioactive Food Components in Nutrition and Cancer--an International Journal.
The advance of technology and understanding of the process of cancer development suggests that the reported lesser incidence and death due to cancer in countries other than the Western and European countries might also be due to under- diagnosed and under-represented cases. Further, increases in life span as well as ignorance about the disease puts populations in South and South East Asian countries at higher risk to develop cancer. With the increasing rate of cancer incidence every year in non -Western countries, cancer is estimated to become the deadliest disease in coming decades. Conventional chemo- and radio-therapies during the past three decades have not been able to contain the disease, and also have serious side effects. Many natural agents, especially small molecules from plants are non-toxic, easily available and may have anticancer potential. Thus, screening phytochemicals as anticancer agents could be a better approach in cancer prevention and treatment. This chemoprevention approach may have translational significance for prevention and treatment of cancer. 
 
Therefore to emphasize the potential role of phytochemicals in cancer prevention and therapy, it was our privilege to host the International Symposium on Recent Advances in Cancer Research: Therapeutics to Chemoprevention, at Central University of Gujarat (CUG), Gandhinagar. The conference was co-organized by the University of Colorado Denver, USA; University of Pittsburgh, USA; University of Oklahoma, USA, during 8–9 February, 2012. Modern biological strategies, specifically the latest developments for the targeted prevention and treatment of cancer via dietary, natural and synthetic agents were discussed in detail. The symposium also emphasized the translational aspect of cancer chemoprevention strategies for various cancers. 
 
The symposium deliberations include the ideas for combinatorial chemoprevention by phytochemicals as a promising approach for cancer control and emerging trends for the use of herbal radio-modulators to sensitize the cancer cells for apoptotic cell death. Many bioactive phytochemicals such as silibinin, benzyl isothiocyanate, anthocyanidins, nexrutine, tocopherol, etc. were discussed for their in vivo efficacy in animal tumor models, associated mechanisms and translational potential. Targeting tumor microenvironment with small molecules was found promising and having translational potential for prostate and breast cancer chemoprevention. 
 
The novel work and ideas presented at the symposium were helpful in guiding the research orientation of scientists, especially the young researchers who will be benefitted at all levels of their career development. Since chemoprevention of cancer is becoming an attractive approach for controlling cancer, we felt that the deliberations of this symposium should reach to the wider section of the researchers. Therefore, it was planned to bring out a special issue on Molecular Basis for Cancer Prevention with Bioactive Food Components in Nutrition and Cancer – An International Journal. We appreciate the researchers for contributing their novel work and ideas to this special issue. We are grateful to the Editor of Nutrition and Cancer – An International Journal, for his initiative to bring out this special issue on this relevant topic. We believe that this volume will be enlightening for the researchers working in the area of cancer chemoprevention.
6837472
Apoptosis is an early event during phthalocyanine photodynamic therapy-induced ablation of chemically induced squamous papillomas in mouse skin.
Photodynamic therapy (PDT) is a promising new modality to treat malignant neoplasms including superficial skin cancers. In our search for an ideal photosensitizer for PDT, Pc 4, a silicon phthalocyanine, has shown promising results both in in vitro assays and in implanted tumors. In this study we assessed the efficacy of Pc 4 PDT in the ablation of murine skin tumors; and the evidence for apoptosis during tumor ablation was also obtained. The Pc 4 was administered through tail vein injection to SENCAR mice bearing chemically induced squamous papillomas, and 24 h later the lesions were illuminated with an argon ion-pumped dye laser tuned at 675 nm for a total light dose of 135 J/cm2. Within 72-96 h, almost complete tumor shrinkage occurred; no tumor regrowth was observed up to 90 days post-PDT. As evident by nucleosome-size DNA fragmentation, appearance of apoptotic bodies in hematoxylin and eosin staining and direct immunoperoxidase detection of digoxigenin-labeled genomic DNA in sections, apoptosis was clearly evident 6 h post-PDT at which time tumor shrinkage was less than 30%. The apoptotic bodies, as evident by the condensation of chromatin material around the periphery of the nucleus and increased vacuolization of the cytoplasm, were also observed in electron microscopic studies of the tumor tissues following Pc 4 PDT. The extent of apoptosis was greater at 15 h than at 6 and 10 h post-PDT. Taken together, our results clearly show that Pc 4 may be an effective photosensitizer for PDT of nonmelanoma skin cancer, and that apoptosis is an early event during this process.
35457752
Nordihydroguaiaretic acid, an inhibitor of lipoxygenase, also inhibits cytochrome P-450-mediated monooxygenase activity in rat epidermal and hepatic microsomes.
Nordihydroguaiaretic acid (NDGA), a plant lignan and phenolic antioxidant, is a known lipoxygenase inhibitor. In this study, we investigated the effect of NDGA on rat epidermal and hepatic monooxygenase activity and its interaction with rat hepatic microsomal cytochrome P-450. The addition of NDGA to epidermal microsomes prepared from control and 3-methylcholanthrene (3-MC)-pretreated rats and hepatic microsomal preparations from control, 3-MC-pretreated, and phenobarbital (PB)-pretreated rats resulted in a concentration-dependent inhibition of aryl hydrocarbon hydroxylase (AHH) and 7-ethoxyresorufin O-deethylase (ERD) activities. The 50% inhibitory dose for NDGA ranged from 4.1 x 10(-5) to 13.1 x 10(-5) M for AHH and ERD activities in these microsomal preparations. The addition of NDGA to hepatic microsomes prepared from PB-pretreated rats resulted in spectral changes characterized by absorbance maxima at 380 nm and minima at 414 nm, typical of type I binding difference spectra. It also showed time- and concentration-dependent inhibition of the binding of carbon monoxide to dithionite or NADPH-reduced cytochrome P-450. We speculate that perhaps hydroxyl groups present in NDGA play an important role in inhibiting the monooxygenase activity and suggest that NDGA may have potential as an antimutagen and/or anticarcinogen. Furthermore, caution must be exercised in elucidating the role of lipoxygenase in metabolic pathways based solely on the criterion of inhibition by NDGA.
5785486
Identification of the site of photocross-linking formed in the absence of magnesium nucleotide from SH2 (Cys-697) in myosin subfragment 1 labeled with 4'-maleimidylbenzophenone.
The site of photocross-linking between Cys-697 (SH2), prelabeled with 4'-[14C]maleimidylbenzophenone, and the 50-kDa segment of myosin S1 on irradiation in the absence of nucleotide has been determined by isolation of the 20-50-kDa adduct and subsequent tryptic proteolysis. Isolation and partial sequencing of the radioactively labeled peptide indicate that the site of cross-linking is Arg-239. This result indicates that, in the absence of nucleotide, Arg-239 resides at about 1.0 nm from SH2 and, on the basis of the recent work of Sutoh and Hiratsuka (Sutoh, K. and Hiratsuka T. (1988) Biochemistry 27, 2964-2969) places Arg-239 at no more than 1.45 nm from either Lys-184 or Lys-189 of the nucleotide-binding "glycine-rich" loop prior to the binding of nucleotide.
46117096
ras protein p21 processing enzyme farnesyltransferase in chemical carcinogen-induced murine skin tumors.
Farnesylation of ras protein p21 is crucial for the protein's membrane localization, which is essential for its cell-transforming activity, which in turn is thought to be critical for the ultimate induction of cancer. The cytosolic enzyme farnesyltransferase plays a major role in posttranslational modification of p21, but the level of farnesyltransferase activity in mammalian tumors and its relationship to the processing of cytosolic p21 that leads to tumorigenesis are unknown. We report here that farnesyltransferase activity was significantly higher in chemical carcinogen-induced benign skin papillomas in SENCAR mice than in the epidermises of control animals. The enzyme is primarily epidermal in origin, and kinetic studies with cytosol from epidermis and papillomas showed that the reaction was linear with respect to time, substrate concentration, and protein content. Skin papillomas showed significantly elevated levels of both cytosolic and membrane-bound Ha-ras p21, whereas far lesser cytosolic and almost negligible amounts of membrane-bound p21 were present in the epidermis of control mice. There was a positive correlation between increased enzyme activity in papilloma cytosol and the processing of overexpressed cytosolic Ha-ras p21 for its localization to membrane.
21255298
Effects of statins on renal function.
This report reviews data on the development of proteinuria in patients with chronic kidney disease who are treated with 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitors (statins) for dyslipidemia. Although subgroup analyses of statin trials have shown cardiovascular benefits in subjects with chronic kidney disease, concern about statin-induced proteinuria remains high. Experimental studies have suggested that the proteinuria seen with statin treatment results from the inhibition of receptor-mediated endocytosis, the likely mechanism of protein uptake in proximal tubular cells. Transient proteinuria may signify little more than the effective inhibition of cholesterol synthesis at this site. The blockade of protein trafficking in tubular cells is thought to reduce inflammation, slow fibrosis, and diminish proteinuria in the long term. Post hoc analyses of large clinical trials in subjects without overt renal disease have generally supported this notion, showing that statins most benefit patients with the greatest baseline renal deficits. Statins have also been shown to preserve glomerular filtration rate and reduce proteinuria in subjects with nondiabetic renal disease. In conclusion, in the absence of prospective, randomized trials in renally impaired patients, the collective evidence indicates that statin therapy may slow the decrease in renal function that generally attends atherosclerotic disease. The incidence of proteinuria with potent statins is only 1% to 2% when these drugs are given in recommended doses. Several large trials are currently under way to examine the safety and efficacy of statins in renally compromised patients at high risk for cardiovascular disease.
39974976
Antiproteinuric effect of oral paricalcitol in chronic kidney disease.
BACKGROUND
Proteinuria is a marker of cardiovascular and renal disease in patients with chronic kidney disease (CKD), and reduction in proteinuria has been associated with improved cardiovascular and renal outcomes. While active vitamin D and its analogs have been shown to have renal protective effects in animals, these hormones have not been shown to reduce proteinuria in CKD patients.


METHODS
In three double-blind, randomized, placebo-controlled studies to evaluate the safety and efficacy of oral paricalcitol, 220 CKD stage 3 and 4 patients with secondary hyperparathyroidism (SHPT) were randomized to oral paricalcitol (N= 107, mean dose 9.5 microg/week) or placebo (N= 113) and followed for up to 24 weeks. In conjunction with other safety measures, proteinuria was measured by dipstick and read by an automated reader at the beginning and end of trial. We subsequently analyzed the dipstick data to evaluate the effect of paricalcitol on proteinuria.


RESULTS
At baseline, proteinuria was present in 57 patients randomized to oral paricalcitol and 61 patients randomized to placebo (NS). At the final visit, 29/57 (51%) of the paricalcitol patients compared to 15/61 (25%) placebo patients had reduction in proteinuria, P= 0.004 (odds for reduction in proteinuria 3.2 times greater for paricalcitol patients, 95% CI 1.5-6.9). For the patients who had both proteinuria at baseline and parathyroid hormone (PTH) suppression (end point defined as 2 consecutive > or =30% decreases in iPTH from baseline), 27/51 (53%) patients had a reduction in the proteinuria in the paricalcitol group and 0/7 (0%) had a reduction in proteinuria in the placebo group. Reduction of proteinuria favored patients on paricalcitol, regardless of age, sex, race, diabetes mellitus, hypertension, or use of therapies to block the renin-angiotensin-aldosterone system (RAAS).


CONCLUSION
Our results demonstrate that the reduction in proteinuria was associated with paricalcitol treatment, and the reduction in proteinuria was independent of concomitant use of agents that block the RAAS. Paricalcitol as a potential pharmacologic means of reducing proteinuria in CKD patients warrants further investigation.
19182304
Strategies for successful patient oriented research: why did I (not) get funded?
Writing grants that are subsequently funded is an integral part of the process of patient-oriented research. A catalogue of common deficiencies that are identified in the grant review process can yield valuable insights into the process of grant writing. This article provides the authors' opinion on the common pitfalls in the current patient-oriented research applications that if identified before submission can lead to a stronger application. The authors participated in the review of clinical research grants to the National Kidney Foundation and catalogued the weaknesses of the grants that were reviewed and discussed. The top five reasons identified with grants were problems with study design (76%); statistical issues (34%); general issues such as ownership of the work, mentor, and environment (29%); weak hypothesis (24%); and problems with the research question, such as novelty or lack of creation of new data (24%). Patient-oriented research grants that have strong mentoring, are hypothesis driven, and have a strong study design that addresses sample size, analysis, and confounding factors have an increased chance of yielding high-quality research and, therefore, successful funding.
24112706
A Randomized Controlled Trial of Oral versus Intravenous Iron in Chronic Kidney Disease
Background: It is unknown whether intravenous iron or oral iron repletion alone can correct anemia associated with chronic kidney disease (CKD). We conducted a randomized multicenter controlled trial in adult anemic, iron-deficient non-dialysis CKD (ND-CKD) patients (≧stage 3) not receiving erythropoiesis-stimulating agents (ESAs). Methods: The participants were randomized to receive either a sodium ferric gluconate complex (intravenous iron) 250 mg i.v. weekly × 4 or ferrous sulfate (oral iron) 325 mg t.i.d. × 42 days. Hemoglobin (Hgb), ferritin and transferrin saturation (TSAT) were measured serially, and the Kidney Disease Quality of Life (KDQoL) questionnaire was administered on days 1 and 43. The primary outcome variable was change from baseline (CFB) to endpoint in Hgb values. Results: Seventy-five patients were analyzed (intravenous iron n = 36, oral iron n = 39). CFB in Hgb was similar in the two groups (intravenous iron 0.4 g/dl vs. oral iron 0.2 g/dl, p = n.s.). However, the increase in Hgb was only significant with intravenous iron (p < 0.01). In comparison to oral iron, intravenous iron achieved greater improvements in ferritin (232.0 ± 160.8 vs. 55.9 ± 236.2 ng/ml, p < 0.001) and TSAT (8.3 ± 7.5 vs. 2.9 ± 8.8%, p = 0.007). Intravenous iron caused greater improvements in KDQoL scores than oral iron (p < 0.05). The most common side effect reported with intravenous iron was hypotension, while constipation was more common with oral iron. Conclusions: Oral and intravenous iron similarly increase Hgb in anemic iron-depleted ND-CKD patients not receiving ESAs. Although in comparison to oral iron, intravenous iron may result in a more rapid repletion of iron stores and greater improvement in quality of life, it exposes the patients to a greater risk of adverse effects and increases inconvenience and cost.
11132742
Proinflammatory effects of iron sucrose in chronic kidney disease.
Inflammation is a central component of progressive chronic kidney disease (CKD). Iron promotes oxidative stress and inflammatory response in animals and promotes progressive CKD. Parenteral iron provokes oxidative stress in patients with CKD; however, its potential to provoke an inflammatory response is unknown. In 20 veterans with CKD, 100 mg iron sucrose was administered intravenously over 5 min and urinary excretion rate and plasma concentration of monocyte chemoattractant protein-1 (MCP-1) were measured at timed intervals over 24 h. Patients were then randomized to placebo or N-acetyl cysteine (NAC) 600 mg b.i.d. and the experiment was repeated at 1 week. Iron sucrose markedly increased plasma concentration and urinary excretion rate of MCP-1 at baseline and at 1 week visits (P < 0.0001 for time effect). Urinary excretion peaked at 30 min and plasma concentration at 15 min. Plasma MCP-1 concentration fell from 164 +/- 17.7 to 135 +/- 17.7 pg/ml with NAC, whereas it remained unchanged from 133 +/- 12.5 to 132 +/- 17.7 pg/ml with placebo (P=0.001 for visit x antioxidant drug interaction). There was a reduction in MCP-1 urinary excretion rate from visit 1 to 2. At the baseline visit, the urinary excretion rate averaged 305 +/- 66 pg/min and at the second visit 245 +/- 67 pg/min (mean difference 60 +/- 28 pg/min, P = 0.030). There was no improvement in urinary MCP-1 excretion with NAC. In conclusion, iron sucrose causes rapid and transient generation and/or release of MCP-1 plasma concentration and increases urinary excretion rate, and systemic MCP-1 level but the urinary excretion rate is not abrogated with the antioxidant NAC. These results may have implications for the progression of CKD with parenteral iron.