Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0596263 (carcinogenesis)
 64,820 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Piroxicam inhibited induction of transitional cell carcinoma in mouse urinary bladder by N-butyl-N-(4-hydroxybutyl)-nitrosamine. At 15 mg piroxicam/kg diet, tumor incidence was reduced 82% (P < 0.0001) compared with carcinogen controls. At 30 mg piroxicam/kg diet, tumor incidence was reduced 70% (P < 0.001). Results at the higher dose level suggested that piroxicam also may have inhibited invasion slightly. Combination treatment with 2-difluoromethyl-ornithine (DFMO) or all-trans-N-(4-hydroxyphenyl)retinamide (4-HPR) or both agents did not improve the chemopreventive potential of piroxicam. However, the three-agent combination of 30 mg piroxicam/kg, 1200 mg DFMO/kg and 313 mg 4-HPR/kg diet was highly effective. Tumor incidence was reduced 91% (P < 0.0001) compared with carcinogen controls. Unfortunately, the high efficacy was somewhat compromised by a significant decrease in survival and body weight gain in mice receiving the combination of agents compared with the carcinogen control.
Carcinogenesis 1993 Jul
PMID:Chemoprevention of OH-BBN-induced bladder cancer in mice by piroxicam. 833 Mar 71

The main objectives were to determine the modulating effects of all-trans retinoic acid on the number, size and multiplicity of aberrant crypt foci as well as the in vivo expression of the genes c-myc and c-fos. These foci, which are hypothesized to be the pre-malignant lesions of colon cancer, were induced in Sprague-Dawley rats with a single injection of azoxymethane. Rats were fed either a control diet (AIN-76) or the control diet to which had been added 75 mg/kg or 150 mg/kg all-trans retinoic acid. Within 4 weeks, we observed that the diets containing all-trans retinoic acid reduced the total number and multiplicity of aberrant crypt foci in the colon. However, all-trans retinoic acid increased the size of the lesions that persisted, possibly due to a greater proportion of lesions with dilated crypts. In situ hybridization and immunohistochemistry were performed on the colons for the in vivo analysis of gene expression in these lesions. The expression of myc-specific mRNA and protein in aberrant crypt foci significantly decreased with both levels of all-trans retinoic acid. In contrast, fos-specific mRNA and protein in aberrant crypt foci significantly increased when 150 mg/kg all-trans retinoic acid was added to the diet. The most important findings of this investigation are that intervention with all-trans retinoic acid in the pre-malignant stage of colon carcinogenesis is effective in decreasing the number and growth of aberrant crypt foci and altering the expression of the c-myc and c-fos genes.
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PMID:Effects of all-trans retinoic acid as a potential chemopreventive agent on the formation of azoxymethane-induced aberrant crypt foci: differential expression of c-myc and c-fos MRNA and protein. 844 5

Although previous epidemiological studies have indicated that beta-carotene is an important agent for the chemical prevention against carcinogenesis, a recent prospective study has strikingly suggested that supplementation with beta-carotene significantly increased the incidence of some types of cancer (The alpha-Tocopherol and beta-Carotene Cancer Prevention Study Group, New Engl. J. Med., 330 (1994) 1031-1035). To analyze the discrepancy of this problem, the authors analyze the effects of beta-carotene on biochemical and biological events associated with carcinogenesis by in vitro experiments. (1) All-trans beta-carotene enhanced the proliferation and DNA synthesis of BALB/c 3T3 cells induced by a tumor promoter, 12-O-tetradecanoyl-phorbol-13-acetate (TPA) and fetal bovine serum, although beta-carotene itself did not show mitogenic activity. (2) All-trans beta-carotene caused a remarkable stimulation for the early induction of ornithine decarboxylase (ODC) activity after the stimulation of TPA and fetal bovine serum. (3) All-trans beta-carotene exhibited significant antimutagenic activity which suppresses umu C gene expression in Salmonella typhimurium (TA 1535/pSK 1002) induced by a typical mutagen, 2-aminoanthracene (2-AA). These experimental results suggest that all-trans beta-carotene might cause beneficial and harmful effects on different phases of carcinogenesis.
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PMID:All-trans beta-carotene enhances mitogenic responses and ornithine decarboxylase activity of BALB/c 3T3 fibroblast cells induced by tumor promoter and fetal bovine serum but suppresses mutagen-dependent umu C gene expression in Salmonella typhimurium (TA 1535/pSK 1002). 856 24

The retinoids are reported to chemoprevent second aerodigestive tract cancers in patients with prior lung or head and neck cancers. Since those retinoids already examined in clinical trials do not induce major clinical responses in lung cancers, it is hypothesized that the beneficial chemoprevention activity in lung neoplasias occurs within 'fields' of carcinogen-transformed epithelial cells. To begin to investigate this retinoid action during lung carcinogenesis, the BZR-T33 ras transformed human bronchial epithelial cell line that grows in an anchorage independent manner was examined. This study reports, as compared to controls, that all-trans-retinoic acid (RA)-treatment suppresses BZR-T33 proliferation in monolayer cultures and in anchorage independent and cloning efficiency growth assays. RA induces RAR-gamma 2 > RAR gamma 1 in BZR-T33 cells but expression at the total cellular RNA level of RAR alpha and RXR alpha is not augmented by RA-treatment. RAR beta mRNA expression is repressed before and after RA-treatment and is only detected using a reverse transcription polymerase chain reaction (RT-PCR) assay. To determine directly which of these expressed retinoid receptors signals growth suppression, each receptor was individually transfected into BZR-T33 cells using episomal vector in colony efficiency assays. RAR gamma over-expression in the presence or absence of RA-treatment did not suppress BZR-T33 growth more than controls. In contrast, over-expression of the other examined retinoid receptors inhibited BZR-T33 cellular cloning efficiency prior to RA-treatment and in this decreasing order after RA-treatment: RAR alpha > RAR beta > RXR alpha. The findings reported here reveal that RA suppresses proliferation and cloning efficiency in this transformed human bronchial epithelial cell through specific retinoid receptors. Further work is needed to evaluate the role of RA or its nuclear receptors in inhibiting even earlier steps in lung carcinogenesis.
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PMID:Growth suppression of transformed human bronchial epithelial cells by all-trans-retinoic acid occurs through specific retinoid receptors. 857 Jan 87

Cervical cancer is the second most common malignancy in women worldwide and remains a significant health problem for women, especially minority and underserved women. Despite an understanding of the epidemiologic risks, the screening Papanicolaou smear, and morbid and costly treatment, overall survival remains 40%. New strategies, based on the clinical and molecular aspects of cervical carcinogenesis, are desperately needed. Chemoprevention refers to the use of chemical agents to prevent or delay the development of cancer in healthy populations. Chemoprevention studies have several unique features that distinguish them from classic chemotherapeutic trials; these features touch on several disciplines and weave knowledge of the biology of carcinogenesis into the trial design. In the design of chemoprevention trials, four factors are important: high risk cohorts must be identified; suitable medications must be selected; study designs should include Phases I, II, and III; and studies should include the use of surrogate end point biomarkers. Surrogate end point biomarkers are sought because the cancer develops over a long period of time, and studies of chemopreventives would require a huge number of subjects followed for many years. Surrogate end point biomarkers serve as alternative end points for examination of the efficacy of chemopreventives in tissue. High risk cohorts include women with cervical intraepithelial neoplasia (CIN) or squamous intraepithelial lesions (SIL). Nutritional studies have helped define micronutrients of interest (folate, carotenoids, vitamin C, vitamin E). Other medications of interest include retinoids (4-hydroxyphenylretinamide [4-HPR], retinyl acetate gel, topical all-trans-retinoic acid), polyamine synthesis inhibitors (alpha-difluoromethylornithine [DFMO]), and nonsteroidal anti-inflammatory drugs (ibuprofen). Phase I chemoprevention studies of the cervix have tested retinyl acetate gel and all-trans-retinoic acid. Phase II trials of all-trans-retinoic acid, beta-carotene, and folic acid have been and are being carried out, whereas Phase III trials of all-trans-retinoic acid have been completed and have shown significant regression of CIN 2 but not CIN 3. Phase I studies of DFMO and Phase II studies of DFMO and 4-HPR are underway. Surrogate end point biomarkers under study include (1) quantitative cytology and histopathology; (2) human papillomavirus type testing; (3) biologic measures of proliferation, regulation, differentiation, and genomic instability; and 4) fluorescence spectroscopic emission. Clinical trials with biologic end points will contribute to our understanding of the neoplastic process and hence aid us in developing new preventive and therapeutic strategies.
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PMID:Chemoprevention trials and surrogate end point biomarkers in the cervix. 863 87

Accumulating evidences that carcinogenesis requires multiple gene alterations of oncogenes and tumor suppressor genes have recently emerged. In addition, genes related to invasion and metastasis are also important in understanding development of colorectal cancer. In this study, clinical significance and application of tumor suppressor genes and invasion related genes such as APC (adenomatous polyposis coli), DCC (deleted in colorectal carcinoma) tumor suppressor genes and invasion related gene, matrilysin were studied. In the mouse tumor induced by mutagen contained in cooked food, PhIP (2-amino-1-methyl-6- phenylimidazo [4,5-b] pyridine), nonsense mutations of APC gene that is similar to human colorectal cancer have been observed. These results suggested the quite interesting issue of mutagen contained in daily food having etiological role of colorectal cancer. DCC gene alteration, decreased expression of DCC mRNA was detected in 60% of advanced colorectal cancer. In all cases with liver metastasis, DCC expression was absent or markedly decreased, a finding that detection of DCC expression have an clinical importance that predicts metastatic potential of colorectal cancer. Matrilysin, the member of MMPs (matrix metalloproteinases) which degrade matrix components such as type IV collagen, laminin or fibronectin. In most of colorectal cancer, matrilysin was overexpressed in tumor cells. Matrilysin-transfected colorectal cancer cells showed more invasive ability in vitro and gained metastatic potential in SCID mice. Suppression of matrilysin expression by treated with all-trans retinoic acid (ATRA) or introduction of anti-sense matrilysin decreased the invasive ability in vitro. This result suggests that matrilysin plays an important role in invasion and metastasis and have a possibility of new anti-invasion therapy.
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PMID:[Genetic diagnosis of colorectal cancer]. 872 69

The retinoids are a pharmacologic class based on the vitamin A or retinol. The most known related derivatives are the all-trans (ATRA), 13 and 9 Cis retinoic acids. The antitumor and differenciative activities have been demonstrated in: in vitro, in vivo and clinical studies. In head and neck cancers, the clinical phase III trials in chemoprevention of second primary tumors have shown discordant results related to the type of retinoic acid. Nuclear retinoic acid receptors are members of the steroid-thyroid and vitamin D3 superfamily of nuclear receptors which regulate differenciation proliferation and apoptosis in cooperation with mediated proteins of the apoptosis (especially p53 protein). A thorough knowledge on the earlier mechanisms involved in carcinogenesis of squamous cell carcinomas would lead to futur reversal therapy with the reversal of pathologic to normal tissues by the restauration of mechanisms of the physiologic control. This futur clinical trial research could provide cancer prevention and control by the induction of cellular differentiation rather than proliferation (retinoids) and/or the expression of tumor-suppressor genes (p53 protein transfection). Finally, the retinoids treatment should be performed in control studies because of the toxicity at high doses.
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PMID:[Current knowledge on the action of retinoids in carcinoma of the head and neck]. 873 61

Well-designed and conducted Phase II clinical trials are very important to cancer chemoprevention drug development. Three critical aspects govern the design and conduct of these trials--well-characterized agents, suitable cohorts, and reliable biomarkers for measuring efficacy that can serve as surrogate endpoints for cancer incidence. Requirements for the agent are experimental or epidemiological data showing chemopreventive efficacy, safety on chronic administration, and a mechanistic rationale for the chemopreventive activity observed. Agents that meet these criteria for chemoprevention of cervical cancer include antiproliferative drugs (e.g., 2-difluoromethylornithine), retinoids, folic acid, antioxidant vitamins and other agents that prevent cellular oxidative damage. Because of the significant cervical cancer risk associated with human papilloma virus (HPV) infection, agents that interfere with the activity of HPV products may also prove to be effective chemopreventives. In endometrium, unopposed estrogen exposure has been associated with cancer incidence. Thus, pure antiestrogens and progestins may be chemopreventive in this tissue. Ovarian cancer risk is correlated to ovulation frequency; therefore, oral contraceptives are potentially chemopreventive in the ovary. Recent clinical observations also suggest that retinoids, particularly all-trans-N-4-hydroxyphenylretinamide, may be chemopreventive in this tissue. The cohort should be suitable for measuring the chemopreventive activity of the agent and the intermediate biomarkers chosen. In the cervix, patients with cervical intraepithelial neoplasia (CIN) and in endometrium, patients with atypical hyperplasia, fit these criteria. Defining a cohort for a Phase II trial in the ovary is more difficult. This tissue is less accessible for biopsy; consequently, the presence of precancerous lesions is more difficult to confirm. The criteria for biomarkers are that they fit expected biological mechanisms (i.e., differential expression in normal and high-risk tissue, on or closely linked to the causal pathway for the cancer, modulated by chemopreventive agents, and short latency compared with cancer), may be assayed reliably and quantitatively, measured easily, and correlate to decrease cancer incidence. They must occur in sufficient incidence to allow their biological and statistical evaluation relevant to cancer. Since carcinogenesis is a multipath process, single biomarkers are difficult to validate as surrogate endpoints, perhaps appearing on only one or a few of the many possible causal pathways. Panels of biomarkers, particularly those representing the range of carcinogenesis pathways, may prove more useful as surrogate endpoints. It is important to avoid solely on biomarkers that do not describe cancer but represent isolated events that may or may not be on the causal pathway or otherwise associated with carcinogenesis. These include markers of normal cellular processes that may be increased or expressed during carcinogenesis. Chemoprevention trials should be designed to evaluate fully the two or three biomarkers that appear to be the best models of the cancer. Additional biomarkers should be considered only if they can be analyzed efficiently and the sample size allows more important biomarkers to be evaluated completely. Two types of biomarkers that stand out regarding their high correlation to cancer and their ability to be quantified are measures of intraepithelial neoplasia and indicators of cellular proliferation. Measurements made by computer-assisted image analysis that are potentially useful as surrogate endpoint biomarkers include nuclear polymorphism comprising nuclear size, shape (roundness), and texture (DNA distribution patterns); nucleolar size and number of nucleoli/nuclei; DNA ploidy, and proliferation biomarkers such as S-phase fraction and PCNA...
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PMID:Strategies for phase II cancer chemoprevention trials: cervix, endometrium, and ovary. 874 72

Because the retinoic acid (RA) signaling pathway regulates cell proliferation and differentiation, inactivation of genes integral to the pathway represents a potential mechanism of carcinogenesis. We have studied in human breast cancer cells (T47D, MCF-7, ZR75-1, MDA-MB-231, and BT20) the expression of a subset of retinoid signaling genes that are themselves transcriptionally up-regulated by RA, the cellular retinol binding protein type I (CRBPI) and the RA receptors (RARs) alpha2, beta2, and gamma2. We find that constitutive expression of these genes is low or undetectable, and that expression levels are seldom responsive to 24 h treatment with 1 microM all-trans or 9-cis RA (Northern blot analysis). This is in contrast to breast fibroblasts, which show RA-dependent expression of all four genes under the same conditions. Moreover, normal human breast epithelial cells express CRBPI and RARbeta2 at the mRNA level, suggesting that loss of expression of these genes is tied to malignant transformation. RARbeta2, but not CRBPI, was also expressed in RA-treated MTSV1-7 cells, an immortalized but nontumorigenic luminal epithelial cell line. Lack of CRBPI and RARbeta2 expression in cancer cells was not due to general impairment of RA signaling, as shown by RA activation of a RARE3-tk-CAT reporter in a subclone of MDA-MB-231 cells that did not express either CRBPI or RARbeta2. These results suggest that at least two independent defects in the expression of proteins that function in retinoid signaling may be involved in breast carcinogenesis.
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PMID:Defective expression of cellular retinol binding protein type I and retinoic acid receptors alpha2, beta2, and gamma2 in human breast cancer cells. 880 Nov 68

Retinoids regulate terminal differentiation of various cells and morphogenesis of various organs. Disorders of such regulations induce cellular and structural anomalies, and lead directly to carcinogenesis. According to these physiological roles of retinoids, many experimental studies have been conducted to test, and successfully demonstrate, the effect of retinoids for the treatment of cancers or the prevention of carcinogenesis. In clinical studies, however, retinoid therapy has not been established as a first choice treatment for solid tumors, although the effect of all-trans retinoic acid for acute promyelocytic leukemia is excellent. Primary cancer chemoprevention in general populations using beta-carotene has failed in all but one of four recently reported trials. In contrast, secondary chemoprevention by retinoids is promising for cancers such as head and neck cancer, uterine cervical cancer and hepatoma.
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PMID:[Prevention and treatment of solid tumors with retinoids]. 888 31


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