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At least 649 records · Page 36Linked to original sources
PubMed2007

Can biomarkers help us understand the nutritional and lifestyle factors important in cancer prognosis?

In attempting to discover the causes of cancer, investigators have recognized that biomarkers can confirm biological plausibility, enhance relative risks, and serve as surrogate endpoints in observational and intervention studies. In the arena of cancer survival, the potential value of biomarkers is increasingly appreciated. A broad range of histological, cellular, and molecular markers have been identified among persons diagnosed with cancer. Molecular and cellular markers are being used to stage disease, predict prognosis, and target therapeutic interventions. Biomarkers in survivors can also help us to understand factors that influence prognosis by both elucidating pertinent biological pathways and sharpening risk estimates. However, as in the case of incident cancer, the use of biomarkers as surrogate endpoints postdiagnosis is problematic because of the potential existence of alternative pathways to recurrence and death that bypass the surrogate endpoint. In evaluating potential surrogates, an understanding of the causal structure underlying the interrelations of exposures, surrogate, and recurrence or death is essential. Three questions can help to shed light on this structure: 1) What is the relation of the surrogate endpoint to recurrence or death? 2) What is the relation of the intervention (or exposure) to the surrogate? 3) To what extent does the surrogate endpoint mediate the relation between intervention (exposure) and recurrence or death? To address these questions, it is imperative to integrate biomarker studies into ongoing pharmacotherapeutic and lifestyle intervention studies with recurrence or mortality as explicit endpoints.

Biomarkers, Tumor↗
PubMed2006

Minimally invasive pharmacokinetic and pharmacodynamic technologies in hypothesis-testing clinical trials of innovative therapies.

Clinical trials of new cancer drugs should ideally include measurements of parameters such as molecular target expression, pharmacokinetic (PK) behavior, and pharmacodynamic (PD) endpoints that can be linked to measures of clinical effect. Appropriate PK/PD biomarkers facilitate proof-of-concept demonstrations for target modulation; enhance the rational selection of an optimal drug dose and schedule; aid decision-making, such as whether to continue or close a drug development project; and may explain or predict clinical outcomes. In addition, measurement of PK/PD biomarkers can minimize uncertainty associated with predicting drug safety and efficacy, reduce the high levels of drug attrition during development, accelerate drug approval, and decrease the overall costs of drug development. However, there are many challenges in the development and implementation of biomarkers that probably explain their disappointingly low implementation in phase I trials. The Pharmacodynamic/Pharmacokinetic Technologies Advisory committee of Cancer Research UK has found that submissions for phase I trials of new cancer drugs in the United Kingdom often lack detailed information about PK and/or PD endpoints, which leads to suboptimal information being obtained in those trials or to delays in starting the trials while PK/PD methods are developed and validated. Minimally invasive PK/PD technologies have logistic and ethical advantages over more invasive technologies. Here we review these technologies, emphasizing magnetic resonance spectroscopy and positron emission tomography, which provide detailed functional and metabolic information. Assays that measure effects of drugs on important biologic pathways and processes are likely to be more cost-effective than those that measure specific molecular targets. Development, validation, and implementation of minimally invasive PK/PD methods are encouraged.

Antineoplastic Agents↗
PubMed1998

The relationship between BcI2, Bax and p53: consequences for cell cycle progression and cell death.

Each cell is under constant surveillance to maintain the integrity of its genome. Genomic lesions in a cell must be repaired before the onset of DNA replication and cell division. In the scenario that the genomic lesion is not repairable, the damaged cells are disposed in an orderly manner known as programmed cell death or apoptosis. Apoptosis and cell cycle progression are two intimately linked phenomena. Uncontrollable cell proliferation perturbs the cellular homeostasis and this can lead to malignancies, as well as organ dysfunction and developmental abnormalities. The biological pathway controlling cell fate is sequentially organized at the molecular level. Recent studies have made important contributions in advancing our knowledge of the mechanisms of cell cycle control and apoptosis regulation. A oncogene-derived protein, Bcl2, confers negative control in the pathway of cellular suicide machinery. A Bcl2-homologous protein, Bax, promotes cell death by competing with Bcl2. While Bax-Bax homodimers act as apoptosis inducers, Bcl2-Bax heterodimer formation evokes a survival signal for the cells. Both Bcl2 and Bax are transcriptional targets for the tumour suppressor protein, p53, which induces cell cycle arrest or apoptosis in response to DNA damage. In all, the coordinate performance of these molecules is crucial for controlling life and death of a cell.

Animals↗
PubMed2000

SURVEY AND SUMMARY: Saccharomyces cerevisiae basic helix-loop-helix proteins regulate diverse biological processes.

Basic helix-loop-helix (bHLH) proteins are among the most well studied and functionally important regulatory proteins in all eukaryotes. The HLH domain dictates dimerization to create homo- and heterodimers. Dimerization juxtaposes the basic regions of the two monomers to create a DNA interaction surface that recognizes the consensus sequence called the E-box, 5'-CANNTG-3'. Several bHLH proteins have been identified in the yeast Saccharomyces cerevisiae using traditional genetic methodologies. These proteins regulate diverse biological pathways. The completed sequence of the yeast genome, combined with novel methodologies allowing whole-genome expression studies, now offers a unique opportunity to study the function of these bHLH proteins. It is the purpose of this review to summarize the current knowledge of bHLH protein function in yeast.

Amino Acid Sequence↗
PubMed2003

Scansite 2.0: Proteome-wide prediction of cell signaling interactions using short sequence motifs.

Scansite identifies short protein sequence motifs that are recognized by modular signaling domains, phosphorylated by protein Ser/Thr- or Tyr-kinases or mediate specific interactions with protein or phospholipid ligands. Each sequence motif is represented as a position-specific scoring matrix (PSSM) based on results from oriented peptide library and phage display experiments. Predicted domain-motif interactions from Scansite can be sequentially combined, allowing segments of biological pathways to be constructed in silico. The current release of Scansite, version 2.0, includes 62 motifs characterizing the binding and/or substrate specificities of many families of Ser/Thr- or Tyr-kinases, SH2, SH3, PDZ, 14-3-3 and PTB domains, together with signature motifs for PtdIns(3,4,5)P(3)-specific PH domains. Scansite 2.0 contains significant improvements to its original interface, including a number of new generalized user features and significantly enhanced performance. Searches of all SWISS-PROT, TrEMBL, Genpept and Ensembl protein database entries are now possible with run times reduced by approximately 60% when compared with Scansite version 1.0. Scansite 2.0 allows restricted searching of species-specific proteins, as well as isoelectric point and molecular weight sorting to facilitate comparison of predictions with results from two-dimensional gel electrophoresis experiments. Support for user-defined motifs has been increased, allowing easier input of user-defined matrices and permitting user-defined motifs to be combined with pre-compiled Scansite motifs for dual motif searching. In addition, a new series of Sequence Match programs for non-quantitative user-defined motifs has been implemented. Scansite is available via the World Wide Web at http://scansite.mit.edu.

Algorithms↗
PubMed2004

The initiative role of XPC protein in cisplatin DNA damaging treatment-mediated cell cycle regulation.

XPC is an important DNA damage recognition protein involved in DNA nucleotide excision repair. We have studied the role of the XPC protein in cisplatin treatment-mediated cell cycle regulation. Through the comparison of microarray data obtained from human normal fibroblasts and two individual XPC-defective cell lines, 486 genes were identified as XPC-responsive genes in the cisplatin treatment (with a minimal 1.5-fold change) and 297 of these genes were further mapped to biological pathways and gene ontologies. The cell cycle and cell proliferation-related genes were the most affected genes by the XPC defect in the cisplatin treatment. Many other cellular function genes were also affected by the XPC defect in the treatment. Western blot hybridization results revealed that the XPC defect reduced the p53 responses to the cisplatin treatment. The ability to activate caspase-3 was also attenuated in the XPC cells with the treatment. These results suggest that the XPC protein plays a critical role in initiating the cisplatin DNA damaging treatment-mediated signal transduction process, resulting in activation of the p53 pathway and cell cycle arrest that allow DNA repair and apoptosis to take place. These results reveal an important role of the XPC protein in the cancer prevention.

Apoptosis↗
PubMed2005

E-RNAi: a web application to design optimized RNAi constructs.

RNA interference (RNAi) has become a powerful genetic approach to systematically dissect gene function on a genome-wide scale. Owing to the penetrance and efficiency of RNAi in invertebrates, model organisms such as Drosophila melanogaster and Caenorhabditis elegans have contributed significantly to the identification of novel components of diverse biological pathways, ranging from early development to fat storage and aging. For the correct assessment of phenotypes, a key issue remains the stringent quality control of long double-stranded RNAs (dsRNA) to calculate potential off-target effects that may obscure the phenotypic data. We here describe a web-based tool to evaluate and design optimized dsRNA constructs. Moreover, the application also gives access to published predesigned dsRNAs. The E-RNAi web application is available at http://e-rnai.dkfz.de/.

Animals↗
PubMed2006

ODB: a database of operons accumulating known operons across multiple genomes.

Operon structures play an important role in co-regulation in prokaryotes. Although over 200 complete genome sequences are now available, databases providing genome-wide operon information have been limited to certain specific genomes. Thus, we have developed an ODB (Operon DataBase), which provides a data retrieval system of known operons among the many complete genomes. Additionally, putative operons that are conserved in terms of known operons are also provided. The current version of our database contains about 2000 known operon information in more than 50 genomes and about 13 000 putative operons in more than 200 genomes. This system integrates four types of associations: genome context, gene co-expression obtained from microarray data, functional links in biological pathways and the conservation of gene order across the genomes. These associations are indicators of the genes that organize an operon, and the combination of these indicators allows us to predict more reliable operons. Furthermore, our system validates these predictions using known operon information obtained from the literature. This database integrates known literature-based information and genomic data. In addition, it provides an operon prediction tool, which make the system useful for both bioinformatics researchers and experimental biologists. Our database is accessible at http://odb.kuicr.kyoto-u.ac.jp/.

Databases, Nucleic Acid↗
PubMed2006

The International Gene Trap Consortium Website: a portal to all publicly available gene trap cell lines in mouse.

Gene trapping is a method of generating murine embryonic stem (ES) cell lines containing insertional mutations in known and novel genes. A number of international groups have used this approach to create sizeable public cell line repositories available to the scientific community for the generation of mutant mouse strains. The major gene trapping groups worldwide have recently joined together to centralize access to all publicly available gene trap lines by developing a user-oriented Website for the International Gene Trap Consortium (IGTC). This collaboration provides an impressive public informatics resource comprising approximately 45 000 well-characterized ES cell lines which currently represent approximately 40% of known mouse genes, all freely available for the creation of knockout mice on a non-collaborative basis. To standardize annotation and provide high confidence data for gene trap lines, a rigorous identification and annotation pipeline has been developed combining genomic localization and transcript alignment of gene trap sequence tags to identify trapped loci. This information is stored in a new bioinformatics database accessible through the IGTC Website interface. The IGTC Website (www.genetrap.org) allows users to browse and search the database for trapped genes, BLAST sequences against gene trap sequence tags, and view trapped genes within biological pathways. In addition, IGTC data have been integrated into major genome browsers and bioinformatics sites to provide users with outside portals for viewing this data. The development of the IGTC Website marks a major advance by providing the research community with the data and tools necessary to effectively use public gene trap resources for the large-scale characterization of mammalian gene function.

Animals↗
PubMed1996

Clinical significance of cyclin D1 expression in patients with node-positive breast carcinoma treated with adjuvant therapy.

BACKGROUND: Experimental and clinical studies suggest that cyclin D1 is involved in transformation and tumour progression. However, there is little and contradictory data on the clinical significance of cyclin D1 in human invasive breast carcinoma. PATIENTS AND METHODS: We investigated whether the determination of cyclin D1 has prognostic value in a series of 180 patients with node-positive breast carcinoma and treated with adjuvant therapy with a median follow-up exceeding 6 years. We assessed cyclin D1 expression using the CDS-6 monoclonal antibody and a highly sensitive immunohistochemical technique. RESULTS: We found that most of the evaluable tumours (117 of 167; 70.1%) presented nuclear cyclin D1 staining and that its expression was significantly associated with both the hormone receptors (P = 0.009 and P = 0.005 for ER and PgR, respectively). Furthermore, 29 (17%) of 167 tumours had a weak (15 cases) or strong (9 cases) cytoplasmic cyclin D1 staining. In a subgroup of cases we also studied the amplification of the cyclin D1 gene and a moderate agreement between cyclin D1 nuclear overexpression assessed immunohistochemically and the gene amplification was found. In univariate analysis, cyclin D1 nuclear positivity was significantly associated with improved 6-year relapse-free survival (RFS) (P = 0.004), but not with overall survival (OS) (P = 0.12). The results of the Cox multivariate analysis (final model) indicate that cyclin D1 expression (P = 0.0049) as well as the number of involved nodes (P < 0.001) and tumour size (P = 0.036) are significant prognostic indicators for RFS. Only the number of involved nodes retained significance (P < 0.001) for OS in our series. The joint assessment of the variables considered in the final model of the multivariate analyses had a moderate prognostic capability as determined using the Harrell c statistic (c = 0.66 and 0.64 for RFS and OS, respectively). CONCLUSIONS: The patients with node-positive breast cancer who have a higher likelihood of gaining benefit from adjuvant therapy are those with tumours with cyclin D1 nuclear expression, small size and less than 3 metastatic nodes. Further studies are needed to verify the prognostic value of cyclin D1 in relation to different adjuvant treatments and to deepen the biological pathways that regulate its activation/ suppression in human breast carcinoma.

Adult↗
PubMed2001

Assessment of cisplatin-induced nephrotoxicity by microarray technology.

Microarrays are a new technology used to study global gene expression and to decipher biological pathways. In the current study, microarrays were used to examine gene expression patterns associated with cisplatin-mediated nephrotoxicity. Sprague-Dawley rats received either single or seven daily ip doses of cisplatin (0.5 or 1 mg/kg/day) or the inactive isomer transplatin (1 or 3 mg/kg/day). Histopathological evaluation revealed renal proximal tubular necrosis in animals that received cisplatin for 7 days, but no hepatotoxic findings. Microarray analyses were performed using rat specific arrays containing 250 toxicity-related genes. Prominent gene expression changes were observed only in the kidneys of rats that received cisplatin for 7 days. Mechanistically, the gene expression pattern elicited by cisplatin (e.g., Bax upward arrow and SMP-30 downward arrow) suggested the occurrence of apoptosis and the perturbation of intracellular calcium homeostasis. The induction of multidrug resistance genes (MDR1 upward arrow, P-gp upward arrow) and tissue remodeling proteins (clusterin upward arrow, IGFBP-1 upward arrow, and TIMP-1 upward arrow) indicated the development of cisplatin resistance and tissue regeneration. Select gene expression changes were further confirmed by TaqMan analyses. Gene expression changes were not observed in the liver following cisplatin administration. In contrast to these in vivo findings, studies using NRK-52E kidney epithelial cells and clone-9 liver cells suggested that liver cells were more sensitive to cisplatin treatment. The discrepancies between the in vivo and in vitro results suggest that caution should be taken when extrapolating data from in vivo to in vitro systems. Nonetheless, the current study elucidates the biochemical pathways involved in cisplatin toxicity and demonstrates the utility of microarrays in toxicological studies.

Animals↗
PubMed2002

Differential toxicogenomic responses to 2,3,7,8-tetrachlorodibenzo-p-dioxin in malignant and nonmalignant human airway epithelial cells.

In humans, exposure to high levels of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) is associated with chronic obstructive pulmonary disease and lung cancer. While several studies have shown that the lung is a target organ for TCDD toxicity, little is known on the specific biological pathways altered by TCDD. Studies have shown that the transcriptional response of TCDD (in vivo and in vitro) is complex, and exhibits cell type and tissue specificity. Thus, the purpose of this study was to look at global and concentration-dependent effects of TCDD on gene expression in human lung cells. Gene expression profiling of both a nontumorigenic (HPL1A) and a malignant, tumorigenic lung cell line (A549) was performed by microarray dual fluorescence hybridizations in cells treated with increasing concentrations of TCDD (0, 0.1, 1, 10 nM) for 24 h. Real time RT-PCR was used to verify alterations in specific genes. Results showed that 68 out of 2091 genes were changed in each cell line, and 15 of those genes were found altered in both cell lines. Common gene responses altered by TCDD were identified and included known xenobiotic metabolizing genes, genes known to alter cell cycle, as well as genes that are involved with cell signaling and that mediate cell motility or communication. Cell line specific differences in gene expression were found that indicate the nonmalignant HPL1A cells are retinoic acid responsive. In addition, TCDD altered specific immunomodulatory genes in the HPL1A cells. These data show that TCDD alters multiple integrated networks of signaling pathways associated with pulmonary disease, particularly that of lung cancer.

Algorithms↗
PubMed2003

Characteristic expression profiles induced by genotoxic carcinogens in rat liver.

When applied in toxicological studies, the recently developed gene expression profiling techniques using microarrays, which brought forth the new field of toxicogenomics, facilitate the interpretation of a toxic compound's mechanism of action. In this study, we investigated whether genotoxic carcinogens at doses known to induce liver tumors in the 2-year rat bioassay deregulate a common set of genes in a short-term in vivo study and, if so, whether these deregulated genes represent defined biological pathways. Rats were dosed with the four genotoxic hepatocarcinogens dimethylnitrosamine (4 mg/kg/day), 2-nitrofluorene (44 mg/kg/day), aflatoxin B1 (0.24 mg/kg/day), and 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK, 20 mg/kg/day). After treatment for up to 14 days, the expression profiles of the livers were analyzed on Affymetrix RG_U34A microarrays. Among the significantly upregulated genes were a set of target genes of the tumor suppressor protein p53, indicating a DNA damage response. Such a response was expected and, therefore, confirmed the validity of our approach. In addition, the gene expression changes suggest a specific detoxification response, the activation of proliferative and survival signaling pathways, and some cell structural changes. These responses were strong throughout the 14 day time course for 2-nitrofluorene and aflatoxin B1; in the case of dimethylnitrosamine and NNK, the effects were weakly detectable at day 1 and then increased with time. For dimethylnitrosamine and aflatoxin B1, which caused observable inflammation in vivo, we found a corresponding upregulation of inflammatory genes at the same time points. Thus, by the toxicogenomic analysis of short-term in vivo studies, we identified genes and pathways commonly deregulated by genotoxic carcinogens, which may be indicative for the early events in tumorigenesis and, thus, predictive of later tumor development.

Animals↗
PubMed2004

Gene expression profiling of rat livers reveals indicators of potential adverse effects.

This study tested the hypothesis that gene expression profiling can reveal indicators of subtle injury to the liver induced by a low dose of a substance that does not cause overt toxicity as defined by conventional criteria of toxicology (e.g., abnormal clinical chemistry and histopathology). For the purpose of this study we defined this low dose as subtoxic, i.e., a dose that elicits effects which are below the detection of conventional toxicological parameters. Acetaminophen (APAP) was selected as a model hepatotoxicant because (1) considerable information exists concerning the mechanism of APAP hepatotoxicity that can occur following high doses, (2) intoxication with APAP is the leading cause of emergency room visits involving acute liver failure within the United States, and (3) conventional clinical markers have poor predictive value. Rats treated with a single dose of 0, 50, 150, or 1500 mg/kg APAP were examined at 6, 24, or 48 h after exposure for conventional toxicological parameters and for gene expression alterations. Patterns of gene expression were found which indicated cellular energy loss as a consequence of APAP toxicity. Elements of these patterns were apparent even after exposure to subtoxic doses. With increasing dose, the magnitude of changes increased and additional members of the same biological pathways were differentially expressed. The energy loss suggested by gene expression changes was confirmed at the 1500 mg/kg dose exposure by measuring ATP levels. Only by ultrastructural examination could any indication of toxicity be identified after exposure to a subtoxic dose of APAP and that was occasional mitochondrial damage. In conclusion, this study provides evidence that supports the hypothesis that gene expression profiling may be a sensitive means of identifying indicators of potential adverse effects in the absence of the occurrence of overt toxicity.

Acetaminophen↗
PubMed2005

Evaluation of polycyclic aromatic hydrocarbons in the activation of early growth response-1 and peroxisome proliferator activated receptors.

Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous environmental and food contaminants with known or suspected carcinogenic properties. In this study, we have evaluated whether PAHs activate the early growth response (EGR-1) gene and bind to peroxisome proliferator-activated receptor alpha (PPAR alpha) and delta (PPAR beta/delta) in cell culture systems. Luciferase reporter systems were employed and several PAHs were evaluated for their ability to activate EGR-1 and PPARs. Some PAHs enhanced EGR-1 expression and activated PPAR alpha and PPAR beta. Among them, benz(a)anthracene was found to act as a relatively potent activator of PPAR alpha and PPAR beta/delta, and to significantly enhance EGR-1 transcription. These in vitro assays were confirmed by Western blot analysis, using cell lysates of tissue samples from mouse trapped at a highly contaminated Superfund site in the Chattanooga Creek floodplain in Chattanooga, Tennessee. We have found that a PPAR target gene, glycogen synthase kinase-3beta (GSK-3beta), was down-regulated and EGR-1 was up-regulated in the mouse samples of Chattanooga Creek. In addition, select PAHs repressed GSK-3beta and induced CYP4A in FaO rat hepatoma cells. In conclusion, PAHs activate PPAR alpha and PPAR beta/delta, and up-regulate EGR-1 expression in vitro as well as in vivo. These data may provide a diversity of PAH activity in several biological pathways.

Animals↗
PubMed1999

Expression of high-affinity receptors for TGF-beta during rat cranial suture fusion.

The etiology of craniosynostosis is unknown. The elucidation of the biological pathways responsible for this disorder has been hampered by an inability to evaluate cranial sutures before, during, and after cranial suture fusion. The programmed fusion of the rat posterofrontal (PF) suture postnatally provides an excellent model to study the molecular events that occur during cranial suture fusion. Previous experiments have implicated transforming growth factor beta (TGF-beta) growth factors in the regulation of PF suture fusion. The purpose of these experiments was to localize the expression of high-affinity receptors for these growth factors during cranial suture fusion. Four rats were sacrificed on postnatal days 8, 12, 17, and 40 (N = 16). The PF and sagittal sutures were harvested and prepared for immunohistochemical localization of TGF-beta receptor 1 and receptor 2 (Tbeta-RI, Tbeta-RII) protein. Results indicate that immunostaining for Tbeta-RI and Tbeta-RII is markedly increased in the dura mater and osteoblasts of the sutural margin of the PF suture during active suture fusion (on postnatal days 12, 17, and 40) compared with the osteoblasts and dura mater underlying the patent sagittal suture. These results, in combination with the authors' previous findings as well as studies supporting a role for TGF-beta molecules in the regulation of osteogenesis, implicate TGF-beta signaling in the regulation of suture fusion. The possible mechanisms of ligand-receptor interaction are discussed.

Animals↗
PubMed2002

Interferon gamma modulates trauma-induced muscle wasting and immune dysfunction.

OBJECTIVE: To test the effect of burn injury in mice congenitally deficient in interferon gamma (IFN-gamma) and as well as in wild-type animals treated with IFN-gamma neutralizing antibody. SUMMARY BACKGROUND DATA: The mechanisms underlying muscle wasting following burn trauma are incompletely characterized, although the hypercatabolic state is a consequence of increased proteasomal degradation. Concurrently, burn injury results in an immunocompromised state, and subsequent infections are the leading cause of morbidity and mortality in these patients. IFN-gamma, best conceptualized as a macrophage activating protein, modulates a variety of biologic pathways potentially relevant to muscle wasting and immune dysfunction. METHODS: Mice received either a 20% total body surface area burn or a control sham treatment. At days 1, 2, and 7 following treatment, skeletal muscle, peripheral blood, and spleen were harvested from both groups. Protein synthesis and degradation rates were measured. Lymphocyte subpopulation expression of major histocompatibility complex I (MHC I) molecules was assessed by flow cytometry, and proliferation capacity was measured using mixed lymphocyte reaction. RESULTS: IFN-gamma is critically involved in burn-induced weight loss; moreover, absence of IFN-gamma virtually abolished skeletal muscle hypercatabolism following burn injury. Lymphocyte proliferation and MHC I expression in the setting of burn trauma are also normalized in the absence of IFN-gamma. Both antigen presentation and proliferation functions are independently affected. CONCLUSIONS: IFN-gamma plays a fundamental role in mediating the hypercatabolic state of multiple cell types following burn trauma.

Animals↗
PubMed2003

Tomato and garlic can modulate azoxymethane-induced colon carcinogenesis in rats.

Tomato (Lycopersicon esculentum) and garlic (Allium cepa) are important constituents of the human diet. Compounds like diallyl sulfides, diallyl disulfides and quercetin, which are active components of garlic, have known anti-inflammatory, antimutagenic activities. Similarly, active components in tomato, such as kaempferol and chlorogenic acid, have antimutagenic activities and lycopene is the most active oxygen quencher with potential chemopreventive activities. In view of this, an endeavour was made to evaluate the anticarcinogenic effect, if any, of tomato and garlic consumption individually and in combination on azoxymethane-induced colonic precancerous lesion, the aberrant crypt foci in animal model. Sprague-Dawley rats (4-5 weeks old) were injected with azoxymethane (15 mg/kg b.w.) and orally administered with 2% (w/v) of tomato, garlic and a combination of both. After 12 weeks of first azoxymethane injection, colons were assessed for aberrant crypt foci and compared with the carcinogen control group. Lipid peroxidation level and glutathione-S-transferase (GST) activity were assessed in liver as well as in colon. Furthermore, in situ cell proliferation and apoptosis were estimated using the Brdu incorporation method and TUNEL method respectively. It was observed that aberrant crypt foci were reduced in all treated groups (by 32.11% in garlic, by 76.14% in tomato and by 55.96% in the combination group). Among treated groups, GST activity was found to be induced in both liver and colon, whereas considerable reduction in lipid peroxidation level was observed in liver as well as in colon with respect to the carcinogen control group. Significant reduction in Brdu labelling index and increase in apoptotic index in colon was noted in the treated groups. These results suggest that tomato and garlic suspensions have a protective effect on colon carcinogenesis, which is mediated by modulation of different biological pathways during carcinogenesis.

Animals↗