Evidence for multiple inducible cytochrome P450 isozymes in SENCAR mouse skin by pyridine.

Pyridine, an amphipathic solvent, is widely used in industry and is also a constituent of tobacco and its smoke. Since, in addition to inhalation and ingestion, pyridine is also readily absorbed through skin, we assessed the effect of skin application of pyridine on monooxygenase activities and cytochrome P450 (CYP) isozymes and CYP mRNA levels in the skin of SENCAR mice. Compared to controls, a single topical application of pyridine (30 or 50 mg/100 g body weight) resulted in induction of cutaneous 7-ethoxyresorufin O-deethylase, 7-pentoxyresorufin O-depentylase, and erythromycin N-demethylase activities.

Green tea and skin--anticarcinogenic effects.

Because of its special aroma, green tea is a popular beverage consumed by some human populations worldwide. In recent years, many laboratory studies have shown that in a variety of animal tumor bioassay systems the administration of green tea, specifically the polyphenolic fraction isolated from green tea leaves (green tea polyphenols), affords protection against cancer induction. In mouse skin tumor bioassay systems, topical application of green tea polyphenols to skin has been shown to result in protection against a) 3-methylcholanthrene-induced skin tumorigenicity, b) 7,12-dimethylbenz(a)anthracene (DMBA)-induced skin tumor initiation, c) 12-O-tetradecanoylphorbol-13-acetate and other tumor promoters caused tumor promotion in DMBA-initiated skin, and d) benzoyl peroxide- and 4-nitroquinoline N-oxide caused enhanced malignant progression of nonmalignant lesions.

Phospholipase activation triggers apoptosis in photosensitized mouse lymphoma cells.

Photodynamic therapy (PDT), an experimental cancer treatment employing a photosensitizer and visible light, is a highly efficient inducer of apoptosis (or programmed cell death) in mouse L5178Y lymphoma cells, resulting in extensive DNA fragmentation within 1-2 h. The major targets for PDT are in cellular membranes, and we now find that PDT sensitized by aluminum phthalocyanine causes the rapid (< 1 min) activation of phospholipase C and the breakdown of membrane phosphoinositides, as well as a similarly rapid release of Ca2+ from intracellular pools. A phospholipase C inhibitor, U73122, blocks the rapid transient increases in both inositol-1,4,5-trisphosphate and intracellular Ca2+ levels as well as the subsequent fragmentation of nuclear DNA, whereas the analogue U73343 is much less effective against all of the aforementioned responses.

Apoptosis during photodynamic therapy-induced ablation of RIF-1 tumors in C3H mice: electron microscopic, histopathologic and biochemical evidence.

Very little is known about the applicability of the metabolic and biochemical events observed in cell culture systems to in vivo tumor shrinkage following photodynamic therapy (PDT). The purpose of this study was to assess whether PDT induces apoptosis during tumor ablation in vivo. We treated radiation-induced fibrosarcoma (RIF-1) tumors grown in C3H/HeN mice with PDT employing three photosensitizers, Photofrin-II, chloroaluminum phthalocyanine tetrasulfonate, or Pc IV (a promising phthalocyanine developed in this laboratory).

Inhibition of both stage I and stage II skin tumor promotion in SENCAR mice by a polyphenolic fraction isolated from green tea: inhibition depends on the duration of polyphenol treatment.

The polyphenolic fraction isolated from green tea (GTP) is a potent inhibitor of phorbol ester 12-O-tetradecanoyl-phorbol-13-acetate (TPA)-induced tumor promotion in mouse skin. In this study, we assessed the effect of GTP on both stage I and stage II skin tumor promotion, and also analyzed the effect of duration of GTP treatment on skin tumor promotion in SENCAR mice. Topical application of GTP (6 mg/animal) concurrently with each application of either TPA (3.

Protection against malignant conversion of chemically induced benign skin papillomas to squamous cell carcinomas in SENCAR mice by a polyphenolic fraction isolated from green tea.

Progression of benign tumors to malignant cancer is critical since cancerous lesions are capable of metastatic spread and eventually causing death. Inhibitors of the conversion process, therefore, would likely be useful as cancer chemopreventive agents. In this study, we assessed the protective effect of topical application of a polyphenolic fraction isolated from green tea (GTP) against spontaneous as well as benzoyl peroxide (BPO)- and 4-nitroquinoline-N-oxide (4-NQO)-enhanced malignant conversion of chemically induced skin papillomas in SENCAR mice.

Protection against ultraviolet B radiation-induced effects in the skin of SKH-1 hairless mice by a polyphenolic fraction isolated from green tea.

In prior studies we and others have shown that oral feeding of a polyphenolic fraction isolated from green tea (GTP) or water extract of green tea affords protection against ultraviolet B (UVB) radiation-induced carcinogenesis in SKH-1 hairless mice (Wang et al., Carcinogenesis 12, 1527-1530, 1991). It is known that exposure of murine skin to UVB radiation results in cutaneous edema, depletion of the antioxidant-defense system and induction of ornithine decarboxylase (ODC) and cyclooxygenase activities.

Purification and characterization of NADPH-cytochrome P-450 reductase from rat epidermis.

NADPH-cytochrome P-450 oxidoreductase (P-450 red) transfers reducing equivalents from NADPH to cytochrome P-450 (P-450) in the monooxygenase system. Detergent solubilized proteins from the membrane fraction of neonatal rat epidermis were purified by 2',5'-ADP-agarose affinity column chromatography. The purified protein showed an apparent homogeneity on sodium dodecylsulfate-polyacrylamide gel electrophoresis and molecular weight was estimated to be 78 kDa.

Differences in inducibility of cytochrome P-4501A1, monooxygenases and glutathione S-transferase in cutaneous and extracutaneous tissues after topical and parenteral administration of beta-naphthoflavone to rats.

1. The effect of topical and parenteral administration of beta-NF to rats on cytochrome P-4501A1, monooxygenases and glutathione S-transferase enzyme activities in various tissues were studied. 2.

Protective effects of green tea polyphenols administered by oral intubation against chemical carcinogen-induced forestomach and pulmonary neoplasia in A/J mice.

Our studies and others have shown the cancer chemopreventive effects of chronic administration of green tea in several animal tumor models. In this study, the administration of a polyphenolic fraction isolated from green tea (GTP) by oral intubation at a dose of 5 mg in 0.2 ml water 30 min prior to challenge with carcinogen, afforded significant protection against both diethylnitrosamine (DEN)- and benzo(a)pyrene (BP)-induced forestomach and lung tumorigenesis in A/J mice.

Photodynamic therapy of human squamous cell carcinoma in vitro and in xenografts in nude mice.

Photodynamic therapy (PDT) of cancer is an experimental tumor therapy which is based on the combined use of a systematically administered photosensitizer to a tumor-bearing host and local illumination of the lesion by a high-intensity visible light source, typically a tunable argon dye laser. Human squamous cell carcinoma (HSCC) is the most frequently encountered malignancy of the head and neck. In this study, responses of HSCC cells to PDT were examined in in vitro and in vivo systems.

Photodynamic effects of new silicon phthalocyanines: in vitro studies utilizing rat hepatic microsomes and human erythrocyte ghosts as model membrane sources.

Photodynamic therapy (PDT) of cancer is a modality that relies upon the irradiation of tumors with visible light following selective uptake of a photosensitizer by the tumor tissue. There is considerable emphasis to define new photosensitizers suitable for PDT of cancer. In this study we evaluated six phthalocyanines (Pc) for their photodynamic effects utilizing rat hepatic microsomes and human erythrocyte ghosts as model membrane sources.

Glutathione S-transferases of human skin: qualitative and quantitative differences in men and women.

Glutathione S-transferase (GST) isozymes of male and female leg skin have been characterized. GST activities and protein have been quantified in a number of male and female skin samples and the results indicate that as compared to the male skin, female skin contains a higher amount of GST activity as well as protein. Both male and female leg skin contain three GST isozymes with pI values 9.

Protection against N-nitrosodiethylamine and benzo[a]pyrene-induced forestomach and lung tumorigenesis in A/J mice by green tea.

In recent years we and others have shown the cancer chemopreventive effects of green tea in several animal tumor models. In this study we assessed the cancer chemopreventive effects of water extract of green tea (WEGT) and the polyphenolic fraction (GTP) isolated from WEGT against N-nitrosodiethylamine (DEN)- and benzo[a]pyrene (BP)-induced forestomach and lung tumorigenesis in A/J mice. The protective effects, both in forestomach and lungs, were evident by a decrease in number of tumors and the percentage of mice with tumors when WEGT and GTP were fed to animals during initiation, post-initiation and entire period of tumorigenesis protocols.

Protection against 12-O-tetradecanoylphorbol-13-acetate-caused inflammation in SENCAR mouse ear skin by polyphenolic fraction isolated from green tea.

Earlier studies conducted in our laboratory have shown that a polyphenolic fraction isolated from green tea (GTP) possesses anti-skin tumor initiating and anti-skin tumor promoting activity in the two-stage skin tumorigenesis protocol in SENCAR mouse. We have also shown that topical application of GTP inhibits tumor promoter-caused induction of epidermal ornithine decarboxylase activity in SENCAR mice in a dose-dependent manner, and that its oral feeding in drinking water to SKH-1 hairless mice enhances antioxidant and phase II enzyme activity in liver, lung, small bowel and skin. In this study, we show that single or multiple applications of GTP on SENCAR mouse ear prior to or after the application of 12-O-tetradecanoylphorbol-13-acetate (TPA) afford significant protection (P < 0.

Chemical carcinogens increase IL-1 alpha and IL-6 gene transcripts in human keratinocytes.

Using reverse transcriptase-linked polymerase chain reaction, the effect of polycyclic aromatic hydrocarbons (PAHs) on IL-1 alpha, IL-1 beta and IL-6 gene expression in cultured human keratinocytes was studied. Exposure to beta-naphthoflavone and benz(a)anthracene resulted in a higher copy number of IL-1 alpha and IL-6 mRNA while lower level of IL-1 beta mRNA was detected in these cells. These data suggest that, like ultraviolet B (UVB) radiation, ubiquitous environmental carcinogenic PAHs are potent inducers of IL-1 alpha and IL-6 cytokines and, unlike UVB, they downregulate IL-1 beta in human keratinocytes.

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.

ras gene activation and aberrant expression of keratin K13 in ultraviolet B radiation-induced epidermal neoplasias of mouse skin.

Both papillomas and squamous cell carcinomas (SCC) induced in mouse epidermis by initiation with 7,12-dimethylbenz[a]anthracene (DMBA) and promotion with 12-O-tetradecanoylphorbol-13-acetate (TPA) exhibit aberrant expression of a type I keratin, K13, that is normally characteristic of terminal differentiation of internal stratified epithelia. There is evidence that the aberrant expression of K13 depends on the presence of an activated ras gene in mouse epidermal keratinocytes (Sutter et al., Mol Carcinog 4:467-476, 1991).

Inhibition of 12-O-tetradecanoylphorbol-13-acetate-caused tumor promotion in 7,12-dimethylbenz[a]anthracene-initiated SENCAR mouse skin by a polyphenolic fraction isolated from green tea.

Our laboratory has been studying cancer chemopreventive effects of polyphenolic fraction isolated from green tea (GTP). In prior studies we have shown that (a) GTP possesses antigenotoxic effects in various test systems; (b) topical application of GTP protects against UV radiation and chemical carcinogen-induced tumorigenesis in murine skin; and (c) feeding of GTP in drinking water p.o.

Glutathione S-transferase-dependent conjugation of leukotriene A4-methyl ester to leukotriene C4-methyl ester in mammalian skin.

The glutathione S-transferase (GST)-dependent conjugation of reduced glutathione (GSH) with leukotriene A4 (LTA4)-methyl ester in rodent and human skin was investigated. Incubation of [3H]LTA4-methyl ester (1 nmole, approximately 200,000 dpm) with cytosol prepared from rat, mouse and human skin or with affinity purified GST from rat skin cytosol in the presence of GSH resulted in the formation of LTC4-methyl ester. Maximum enzyme activity was observed in rat skin followed by mouse and human skin.

Carcinogen-specific mutational pattern in the p53 gene in ultraviolet B radiation-induced squamous cell carcinomas of mouse skin.

We have examined 35 epidermal tumors induced in mice of four different strains by chronic exposure to ultraviolet B radiation for the presence of aberrations in the p53 tumor suppressor gene. Polymerase chain reaction products from p53 exons 5 to 8 were screened by single-strand conformation polymorphism analysis and sequencing. Base substitutions were found in seven tumors (20%).

Immunogenetic influences on the initiation stage of the cutaneous chemical carcinogenesis pathway.

While it is generally agreed that environmental exposure to solar radiation and to certain classes of chemicals are the major causes of nonmelanoma skin cancer, it is also believed that genetic polymorphisms regulating immunological responses are important determinants of individual susceptibility to skin cancer. However, little is known about their interactions with the chemical carcinogenesis pathway prior to the actual development of tumors. This issue was examined by comparing susceptibility to skin cancer in C3H/HeN and C3H/HeJ mice, two strains that differ only at the lipopolysaccharide genetic locus, which serves as a regulator of a number of immunological activities.