Yogeshwer Shukla

Cypermethrin exposure leads to regulation of proteins expression involved in neoplastic transformation in mouse skin

Cypermethrin, a synthetic pyrethroid insecticide is shown to exert carcinogenic effects in rodents; however, its underlying mechanism remains elusive. Here, we showed the effect of cypermethrin on protein expression involved in neoplastic transformation in mouse skin. Comparative protein expression profiles between untreated control and cypermethrin‐treated mouse skin were explored using 2‐DE. A total of 27 spots that were statistically significant (p<0.05) and differentially expressed in response to cypermethrin exposure were identified by MALDI‐TOF/TOF and LC‐MS/MS. Among them, six up‐regulated proteins (carbonic anhydrase 3 (Ca 3), Hsp‐27, S100A6, galectin‐7, S100A9, S100A11) and one down‐regulated protein (superoxide dismutase [Cu‐Zn] (Sod 1)) are associated with cancer‐related key processes. These selected dysregulated proteins were further validated in 2‐DE gels of mouse skin treated with known tumorigens (benzo‐[a]‐pyrene, 12‐O‐tetradecanoyl‐phorbol‐13‐acetate and mezerein), respectively. Comparative studies showed that Ca 3, S100A6, S100A9, S100A11 and Sod 1 are specific for stages of development and progression of tumors whereas Hsp‐27 and galectin‐7 are specific for tumor promotion stage by cypermethrin in mouse skin. Furthermore, these chosen proteins confirmed by Western blotting and immunofluorescence staining were consistent with changes in 2‐DE check. This proteomic investigation for the first time provides key proteins that will contribute in understanding the mechanism behind cypermethrin‐induced neoplastic transformation.

What Is New for an Old Molecule? Systematic Review and Recommendations on the Use of Resveratrol

Background Resveratrol is a natural compound suggested to have beneficial health effects. However, people are consuming resveratrol for this reason without having the adequate scientific evidence for its effects in humans. Therefore, scientific valid recommendations concerning the human intake of resveratrol based on available published scientific data are necessary. Such recommendations were formulated after the Resveratrol 2010 conference, held in September 2010 in Helsingør, Denmark. Methodology Literature search in databases as PubMed and ISI Web of Science in combination with manual search was used to answer the following five questions: 1Can resveratrol be recommended in the prevention or treatment of human diseases?; 2Are there observed “side effects” caused by the intake of resveratrol in humans?; 3What is the relevant dose of resveratrol?; 4What valid data are available regarding an effect in various species of experimental animals?; 5Which relevant (overall) mechanisms of action of resveratrol have been documented? Conclusions/Significance The overall conclusion is that the published evidence is not sufficiently strong to justify a recommendation for the administration of resveratrol to humans, beyond the dose which can be obtained from dietary sources. On the other hand, animal data are promising in prevention of various cancer types, coronary heart diseases and diabetes which strongly indicate the need for human clinical trials. Finally, we suggest directions for future research in resveratrol regarding its mechanism of action and its safety and toxicology in human subjects.

Resveratrol and cellular mechanisms of cancer prevention

The use of novel and improved chemopreventive and chemotherapeutic agents for the prevention and treatment of cancer is on the rise. Natural products have always afforded a rich source of such agents. Epidemiological evidence suggests that a higher flavonoid intake is associated with low cancer risk. Accumulating data clearly indicate that the induction of apoptosis is an important component in the chemoprevention of cancer by naturally occurring dietary agents. Resveratrol, a naturally occurring polyphenol, demonstrates pleiotropic health benefits, including antioxidant, anti‐inflammatory, antiaging, cardioprotective, and neuroprotective activities. Because of these properties and their wide distribution throughout the plant kingdom, resveratrol is envisioned as a potential chemopreventive/curative agent. Currently, a number of preclinical findings from our lab and elsewhere suggest resveratrol to be a promising natural weapon in the war against cancer. Remarkable progress in elucidating the molecular mechanisms underlying the anticancer properties of resveratrol has been achieved. Here, we focus on some of the myriad pathways that resveratrol targets to exert its chemopreventive role and advocate that resveratrol holds tremendous potential as an efficient anticancer drug of the future.

Death receptors: Targets for cancer therapy

Apoptosis is the cells intrinsic program to death, which plays an important role in physiologic growth control and homeostasis. Apoptosis can be triggered by death receptors (DRs), without any adverse effects. DRs are the members of tumor necrosis factor (TNF) receptor superfamily, known to be involved in apoptosis signaling, independent of p53 tumor-supressor gene. Selective triggering of DR-mediated apoptosis in cancer cells is a novel approach in cancer therapy. So far, the best characterized DRs are CD95 (Fas/Apo1), TNF-related apoptosis-inducing ligand receptor (TRAILR) and tumor necrosis factor receptor (TNFR). Among these, TRAILR is emerging as most promising agent for cancer therapy, because it induces apoptosis in a variety of tumor and transformed cells without any toxicity to normal cells. TRAIL treatment in combination with chemotherapy or radiotherapy enhances TRAIL sensitivity or reverses TRAIL resistance by regulating downstream effectors. This review covers the current knowledge about the DRs, summarizes main signaling in DRs and also summarizes the preclinical approaches of these DRs in cancer therapy.

Lupeol: connotations for chemoprevention.

The perception of chemoprevention lies still in its infancy. Intervention, to slow down, arrest or reverse the process of carcinogenesis, by the use of either natural or synthetic substances individually or in combination therapy has emerged as a promising and pragmatic medical approach to reduce cancer risk. Pentacyclic lupane-type triterpenes exemplified by lupeol [lup-20(29)-en-3b-ol], are principally found in common fruit plants such as olive, mango, fig, etc. Although, lupeol exhibits an array of biological activities like anti-inflammatory, anti-arthritic, anti-mutagenic and anti-malarial activity both in in vitro and in vivo systems yet, extensive exploration in regard to establish its role as chemopreventive compound is warranted. Interest in developing lupeol based potent anti-neoplastic agents, has led to the discovery of a host of highly active derivatives exhibiting greater potencies and better therapeutic indices. This review asserts on the chemopreventive prospects of lupeol and reveals potential chemoprevention drug targets, central to which are the cell cycle regulatory pathway genes and tries to explain the mechanism operating behind its action.

Antimutagenic potential of curcumin on chromosomal aberrations in Wistar rats.

Curcumin, a yellow pigment commonly used as a spice and food coloring agent is obtained from rhizomes of Curcuma longa and is a major chemopreventive component of turmeric. In the present set of investigations the antimutagenic potential of curcumin has been evaluated using in vivo chromosomal aberration assay in Wistar rats. Cyclophosphamide (CP), a well-known mutagen was given by intraperitoneal (i.p.) injection at the dose of 40 mg/kg body weight (b.w.). Curcumin was given at the dose of 100 and 200 mg/kg b.w. through gastric intubation for seven consecutive days prior to CP treatment. The animals were sacrificed at the sampling time of 24 h after treatment and their bone marrow tissue was analyzed for chromosomal damage and mitotic index. In CP treated animals a significant induction of chromosomal aberration was recorded with decrease in mitotic index. However, in curcumin-supplemented animals, no significant induction in chromosomal damage or change in mitotic index was recorded. In different curcumin-supplemented groups, a dose dependent significant decrease in CP induced clastogenicity was recorded. The incidence of aberrant cells was found to be reduced by both the doses of curcumin when compared to CP treated group. The anticytotoxic potential of curcumin towards CP was also evident as the status of mitotic index was found to show increment. The study revealed the antigenotoxic potential of curcumin against CP induced chromosomal mutations.

Resveratrol induces apoptosis involving mitochondrial pathways in mouse skin tumorigenesis

Resveratrol, a plant constituent enriched in the skin of grapes, is one of the most promising agents for chemoprevention. In the present study, resveratrol-induced apoptosis in 7, 12-dimethylbenz[a]anthracene (DMBA)-initiated and 12-O-tetradecanoylphorbol-13-acetate (TPA) promoted, mouse skin tumors. The chemopreventive effects of resveratrol in terms of delayed onset of tumorigenesis, cumulative number of tumors and average number of tumors/mouse were recorded. Resveratrol treatment resulted in regression of tumors (28%) after withdrawal of the TPA treatment. Induction of apoptosis by resveratrol in DMBA-TPA induced skin tumors was recorded by the appearance of a sub-G1 fraction (30%) using flow cytometry and an increase in the number of apoptotic cells by terminal deoxynucleotidyl transferase mediated dUTP nick end labeling (TUNEL) assay. Western blot analysis combined with multivariable flow cytometry, showed that resveratrol application induces the expression of the p53 and pro-apoptotic Bax, with concomitant decrease in anti-apoptotic protein Bcl-2. Alteration in Bax/Bcl2 ratio by resveratrol treatment resulted in apoptosis, which was associated with the release of cytochrome c and induction of apoptotic protease-activating factor-1(APAF-1). Further, this effect was found to result in cleaved fragments of caspase-9,-3, and poly (ADP-ribose) polymerase (PARP). These findings demonstrate for the first time that resveratrol induces apoptosis through activation of p53 activity in mouse skin tumors, thereupon suggesting its chemopreventive activity, through the modulation of proteins involved in mitochondrial pathway of apoptosis.

Resveratrol and Black Tea Polyphenol Combination Synergistically Suppress Mouse Skin Tumors Growth by Inhibition of Activated MAPKs and p53

Cancer chemoprevention by natural dietary agents has received considerable importance because of their cost-effectiveness and wide safety margin. However, single agent intervention has failed to bring the expected outcome in clinical trials; therefore, combinations of chemopreventive agents are gaining increasing popularity. The present study aims to evaluate the combinatorial chemopreventive effects of resveratrol and black tea polyphenol (BTP) in suppressing two-stage mouse skin carcinogenesis induced by DMBA and TPA. Resveratrol/BTP alone treatment decreased tumor incidence by ∼67% and ∼75%, while combination of both at low doses synergistically decreased tumor incidence even more significantly by ∼89% (p<0.01). This combination also significantly regressed tumor volume and number (p<0.01). Mechanistic studies revealed that this combinatorial inhibition was associated with decreased expression of phosphorylated mitogen-activated protein kinase family proteins: extracellular signal-regulated kinase 1/2, c-Jun N-terminal kinase 1/2, p38 and increased in total p53 and phospho p53 (Ser 15) in skin tissue/tumor. Treatment with combinations of resveratrol and BTP also decreased expression of proliferating cell nuclear antigen in mouse skin tissues/tumors than their solitary treatments as determined by immunohistochemistry. In addition, histological and cell death analysis also confirmed that resveratrol and BTP treatment together inhibits cellular proliferation and markedly induces apoptosis. Taken together, our results for the first time lucidly illustrate that resveratrol and BTP in combination impart better suppressive activity than either of these agents alone and accentuate that development of novel combination therapies/chemoprevention using dietary agents will be more beneficial against cancer. This promising combination should be examined in therapeutic trials of skin and possibly other cancers.

Carcinogenic and cocarcinogenic potential of cypermethrin on mouse skin

Cypermethrin (CYM), a synthetic pyrethroid insecticide, is used widely because of its high bio-efficacy and low mammalian toxicity. In the present set of investigations, CYM has been evaluated for its carcinogenic and co-carcinogenic (tumour initiating and tumour promoting) potential in mouse skin model of carcinogenesis. The results revealed that CYM possess complete carcinogenic as well as tumour initiating and promoting potential in both the sexes of Swiss albino mice. At the end point, i.e. 32 weeks in a single dose (10 mg/kg body weight (wt.), once only), initiated mice, 9 out of 12 surviving males, and 10 out of 14 surviving females developed benign tumours, while a higher incidence of tumourigenesis was recorded in multiple dose-initiated (10 mg/kg body wt., total nine applications) group, where 7 out of 9 surviving male and 10 out of 13 surviving female mice developed tumours at the site of topical exposure. The application of CYM as a tumour promoter on 7,12-dimethylbenz(a)anthracene initiated animals induced tumour incidence in about 4 out of surviving 10 male and 5 out of surviving 13 female Swiss albino mice. CYM when tested for complete carcinogenic activity induced tumour formation in both male and female animals at all the three tested dose levels.

Clastogenic effects of glyphosate in bone marrow cells of swiss albino mice.

Glyphosate (N-(phosphonomethyl) glycine, C3H8NO5P), a herbicide, used to control unwanted annual and perennial plants all over the world. Nevertheless, occupational and environmental exposure to pesticides can pose a threat to nontarget species including human beings. Therefore, in the present study, genotoxic effects of the herbicide glyphosate were analyzed by measuring chromosomal aberrations (CAs) and micronuclei (MN) in bone marrow cells of Swiss albino mice. A single dose of glyphosate was given intraperitoneally (i.p) to the animals at a concentration of 25 and 50 mg/kg b.wt. Animals of positive control group were injected i.p. benzo(a)pyrene (100 mg/kg b.wt., once only), whereas, animals of control (vehicle) group were injected i.p. dimethyl sulfoxide (0.2 mL). Animals from all the groups were sacrificed at sampling times of 24, 48, and 72 hours and their bone marrow was analyzed for cytogenetic and chromosomal damage. Glyphosate treatment significantly increases CAs and MN induction at both treatments and time compared with the vehicle control (P < .05). The cytotoxic effects of glyphosate were also evident, as observed by significant decrease in mitotic index (MI). The present results indicate that glyphosate is clastogenic and cytotoxic to mouse bone marrow.