Carcinogen 7,12-dimethylbenz[a]anthracene-induced mammary tumorigenesis is accelerated in Smad3 heterozygous mice compared to Smad3 wild type mice.

Previous studies based on cell culture and xenograft animal models suggest that Smad3 has tumor suppressor function for breast cancer during early stages of tumorigenesis. In this report, we show that DMBA (7,12-dimethylbenz[a]anthracene), a chemical carcinogen, induces mammary tumor formation at a significantly higher frequency in the Smad3 heterozygous mice than in the Smad3 wild type mice. This is the first genetic evidence showing that Smad3 inhibits mammary tumor formation in a mouse model.

Parametrial fat tissue from high fat diet-treated SKH-1 mice stimulates transformation of mouse epidermal JB6 cells.

Unlabelled: Our previous studies indicated that decreasing visceral adipose tissue by surgical removal of the parametrial fat pads inhibited UVB-induced carcinogenesis in SKH-1 mice fed a high fat diet (HFD), but not a low fat diet (LFD) indicating that the parametrial fat tissue from mice fed a HFD played a role in skin carcinogenesis.

Objective: In the present study, we sought to investigate how a HFD may influence the intrinsic properties of the parametrial fat tissue to influence UVB-induced skin tumor formation.

Methods And Results: Immunohistochemical staining, adipokine array, and flow cytometry showed that parametrial fat tissue from mice fed a HFD had a higher density of macrophage-fused dead adipocytes (crown-like structures), more adipokines, and stimulated the production of more reactive oxygen species compared with parametrial fat tissue from mice fed a LFD.

PDE2 is a novel target for attenuating tumor formation in a mouse model of UVB-induced skin carcinogenesis.

Our previous studies demonstrated that the topical application of caffeine is a potent inhibitor of UVB-induced carcinogenesis and selectively increases apoptosis in tumors but not in non-tumor areas of the epidermis in mice that are at a high risk for developing skin cancer. While this effect is mainly through a p53 independent pathway, the mechanism by which caffeine inhibits skin tumor formation has not been fully elucidated. Since caffeine is a non-specific phosphodiesterase inhibitor, we investigated the effects of several PDE inhibitors on the formation of sunburn cells in mouse skin after an acute exposure to ultraviolet light B (UVB).

Inverse relationship between p53 and phospho-Chk1 (Ser317) protein expression in UVB-induced skin tumors in SKH-1 mice.

Immunohistochemical evaluation of serial stored paraffin sections from 42 keratoacanthomas and 11 squamous cell carcinomas demonstrated that skin tumors from UVB-exposed mice showed an inverse relationship (>95%) between p53 protein expression and phospho-Chk1 (Ser317), but not phospho-Chk1 (Ser345) protein expression. Tumors expressing high levels and large areas of p53 protein had no detectable phospho-Chk1 (Ser317), whereas tumors expressing high levels and large areas of phospho-Chk1 (Ser317) protein had no detectable p53. Squamous cell carcinomas that demonstrated heterogeneous p53 and phospho-Chk1 (Ser317) protein expression within the same tumor showed that areas expressing p53 were negative for phospho-Chk1 (Ser317) immunostaining while areas expressing phospho-Chk1 (Ser317) were negative for p53.

Oral caffeine during voluntary exercise markedly inhibits skin carcinogenesis and decreases inflammatory cytokines in UVB-treated mice.

Ultraviolet B (UVB)-pretreated SKH-1 mice were treated with water, caffeine (0.1 mg/ml), voluntary running wheel exercise (RW) or caffeine together with RW for 14 wk. Treatment of the mice with caffeine, RW, or caffeine plus RW decreased skin tumors per mouse by 27%, 35%, and 62%, respectively, and the tumor volume per mouse was decreased by 61%, 70%, and 85%, respectively.

Mechanisms of Caffeine-Induced Inhibition of UVB Carcinogenesis.

Sunlight-induced non-melanoma skin cancer is the most prevalent cancer in the United States with more than two million cases per year. Several studies have shown an inhibitory effect of caffeine administration on UVB-induced skin cancer in mice, and these studies are paralleled by epidemiology studies that indicate an inhibitory effect of coffee drinking on non-melanoma skin cancer in humans. Strikingly, decaffeinated coffee consumption had no such inhibitory effect.

Inhibition of UVB-induced nonmelanoma skin cancer: a path from tea to caffeine to exercise to decreased tissue fat.

Oral administration of green tea, black tea, or caffeine (but not the decaffeinated teas) inhibited ultraviolet B radiation (UVB)-induced skin carcinogenesis in SKH-1 mice. Studies with caffeine indicated that its inhibitory effect on the ATR/Chk1 pathway is an important mechanism for caffeine's inhibition of UVB-induced carcinogenesis. The regular teas or caffeine increased locomotor activity and decreased tissue fat.

Surgical removal of the parametrial fat pads stimulates apoptosis and inhibits UVB-induced carcinogenesis in mice fed a high-fat diet.

Removal of the parametrial fat pads (partial lipectomy) from female SKH-1 mice fed a high-fat diet inhibited UVB-induced carcinogenesis, but this was not observed in mice fed a low-fat chow diet. Partial lipectomy in high-fat-fed mice decreased the number of keratoacanthomas and squamous cell carcinomas per mouse by 76 and 79%, respectively, compared with sham-operated control mice irradiated with UVB for 33 wk. Immunohistochemical analysis indicated that partial lipectomy increased caspase 3 (active form) positive cells by 48% in precancerous epidermis away from tumors, by 68% in keratoacanthomas, and by 224% in squamous cell carcinomas compared with sham-operated control mice.

Effects of high-fat diets rich in either omega-3 or omega-6 fatty acids on UVB-induced skin carcinogenesis in SKH-1 mice.

Our previous studies reported that caffeine or voluntary exercise decreased skin tumor multiplicity, in part, by decreasing fat levels in the dermis. These data suggest that tissue fat may play an important role in regulating ultraviolet light (UV) B-induced skin tumor development. In the present study, we explored the effects of high-fat diets rich in either omega-3 or omega-6 fatty acids on UVB-induced skin carcinogenesis.

Caffeine decreases phospho-Chk1 (Ser317) and increases mitotic cells with cyclin B1 and caspase 3 in tumors from UVB-treated mice.

Oral administration of caffeine to mice inhibits UVB-induced carcinogenesis, and these results are paralleled by epidemiology studies indicating that caffeinated coffee and tea intake (but not decaffeinated beverage intake) is associated with decreased incidence of nonmelanoma skin cancer. Topical applications of caffeine to the skin of SKH-1 mice that had previously been treated with UVB inhibited subsequent skin tumor development and stimulated apoptosis in tumors but not in nontumor areas of the epidermis. This study sought to determine the basis of these differential effects on tumor versus nontumor sites that can be induced by caffeine, long after all UVB treatment has ceased.

Oral administration of caffeine during voluntary exercise markedly decreases tissue fat and stimulates apoptosis and cyclin B1 in UVB-treated skin of hairless p53-knockout mice.

Treatment of p53(-/-) mice orally with caffeine, voluntary exercise or their combination for 2 weeks prior to a single irradiation with UVB (i) decreased the weight of the epididymal fat pads by 22, 40 and 56%, (ii) decreased the thickness of the dermal fat layer by 10, 26 and 42%, (iii) increased the number of apoptotic sunburn cells by 29, 100 and 489%, (iv) increased the number of caspase-3-positive cells by 33, 117 and 667% and (v) increased the number of mitotic cells with cyclin B1-positive staining by 40, 210 and 510%, respectively. Pearson's correlation coefficient indicated a statistically significant inverse relationship between the level of tissue fat and the number of mitotic cells with cyclin B1 in p53(-/-) mice but not in p53(+/+) littermates. Western blot analysis indicated that treatment of p53(-/-) mice with caffeine together with exercise increased the level of cyclin B1 significantly more than in p53(+/+) mice.

Gemini vitamin D analogues inhibit estrogen receptor-positive and estrogen receptor-negative mammary tumorigenesis without hypercalcemic toxicity.

Numerous preclinical, epidemiologic, and clinical studies have suggested the benefits of vitamin D and its analogues for the prevention and treatment of cancer. However, the hypercalcemic effects have limited the use of 1alpha,25(OH)(2)D(3), the hormonally active form of vitamin D. To identify vitamin D analogues with better efficacy and low toxicity, we have tested >60 novel Gemini vitamin D analogues with a unique structure of two side chains for growth inhibition of breast cancer cells.

Tumorigenic effect of some commonly used moisturizing creams when applied topically to UVB-pretreated high-risk mice.

Irradiation of SKH-1 mice with UVB (30 mJ cm(-2)) twice a week for 20 weeks resulted in mice with a high risk of developing skin tumors over the next several months in the absence of further irradiation with UVB (high-risk mice). Topical applications of 100 mg of Dermabase, Dermovan, Eucerin Original Moisturizing Cream (Eucerin), or Vanicream once a day, 5 days a week for 17 weeks to these high-risk mice increased significantly the rate of formation of tumors and the rate of increase in tumor size per mouse. Additional studies indicated that treatment of high-risk mice with Dermabase, Dermovan, Eucerin, or Vanicream for 17 weeks increased the total number of histologically characterized tumors by 69% (average of two experiments; P<0.

Effect of caffeine on the ATR/Chk1 pathway in the epidermis of UVB-irradiated mice.

Administration of caffeine was shown in earlier studies to enhance UVB-induced apoptosis and inhibit UVB-induced carcinogenesis in hairless SKH-1 mice. Here, we describe a potential mechanism for these in vivo effects. A single irradiation of mouse skin with UVB activated the ataxia-telangiectasia mutated- and Rad3-related (ATR) pathway, causing a severalfold increase in keratinocytes with phospho-Chk1 (Ser(345)) and a marked decrease in mitotic keratinocytes with cyclin B1 compared with baseline.

Effect of caffeine on UVB-induced carcinogenesis, apoptosis, and the elimination of UVB-induced patches of p53 mutant epidermal cells in SKH-1 mice.

Oral administration of green tea or caffeine to SKH-1 mice during UVB irradiation for several months inhibited the formation of skin cancer. Similar effects were observed when green tea or caffeine was given to tumor-free UVB-initiated mice with a high risk of developing skin tumors in the absence of further UVB irradiation (high risk mice). Mechanistic studies indicated that topical application of caffeine stimulated UVB-induced apoptosis as well as apoptosis in UVB-induced focal hyperplasia and tumors in tumor-bearing mice.

Voluntary exercise together with oral caffeine markedly stimulates UVB light-induced apoptosis and decreases tissue fat in SKH-1 mice.

Treatment of SKH-1 mice orally with caffeine (0.1 mg/ml in the drinking water), voluntary running wheel exercise, or a combination of caffeine and exercise for 2 weeks (i) decreased the weight of the parametrial fat pads by 35, 62, and 77%, respectively; (ii) decreased the thickness of the dermal fat layer by 38, 42, and 68%, respectively; (iii) stimulated the formation of UVB-induced apoptotic sunburn cells in the epidermis by 96, 120, and 376%, respectively; and (iv) stimulated the formation of UVB-induced caspase 3 (active form)-positive cells in the epidermis by 92, 120, and 389%, respectively (average of two experiments). Oral administration of caffeine (0.

Stimulatory effect of voluntary exercise or fat removal (partial lipectomy) on apoptosis in the skin of UVB light-irradiated mice.

Earlier studies indicated that high dietary fat and obesity are associated with an increased risk of cancer at several organ sites in experimental animals and in humans. In a recent study we found that voluntary running wheel exercise decreased body fat and inhibited ultraviolet B light (UVB)-induced carcinogenesis in the epidermis of SKH-1 mice. In the present study we demonstrate that voluntary running wheel exercise stimulated UVB-induced apoptosis in the epidermis by a p53-independent mechanism, and voluntary exercise also stimulated apoptosis in UVB-induced tumors in tumor-bearing mice.

Caffeine and caffeine sodium benzoate have a sunscreen effect, enhance UVB-induced apoptosis, and inhibit UVB-induced skin carcinogenesis in SKH-1 mice.

Topical application of caffeine sodium benzoate (caffeine-SB) immediately after UVB irradiation of SKH-1 mice enhanced UVB-induced apoptosis by a 2- to 3-fold greater extent than occurred after the topical application of an equimolar amount of caffeine. Although topical application of caffeine-SB or caffeine enhanced UVB-induced apoptosis, both substances were inactive on non-UVB-treated normal skin. Topical application of caffeine-SB or caffeine (each has UVB absorption properties) 0.

Inhibitory effects of voluntary running wheel exercise on UVB-induced skin carcinogenesis in SKH-1 mice.

Earlier studies showed that oral administration of green tea or caffeine to SKH-1 mice inhibited ultraviolet B light (UVB)-induced skin carcinogenesis, decreased dermal fat thickness and increased locomotor activity. In the present study, the effects of voluntary running wheel exercise on thickness of dermal fat as well as on UVB-induced tumorigenesis in SKH-1 mice were studied in UVB-initiated high-risk and UVB-induced complete carcinogenesis models. In the high-risk model, animals were exposed to UVB (30 mJ/cm(2)) 3 times/week for 16 weeks.

Effect of administration of caffeine or green tea on the mutation profile in the p53 gene in early mutant p53-positive patches of epidermal cells induced by chronic UVB-irradiation of hairless SKH-1 mice.

Irradiation of SKH-1 mice with UVB light for 20 weeks resulted in a large number of patches of epidermal cells, which was visualized with an antibody that recognizes mutated p53 protein. Oral treatment of mice with caffeine (0.4 mg/ml) or green tea (6 mg tea solids/ml) as the drinking fluid during UVB irradiation decreased the number of patches by approximately 40%.

Patches of mutant p53-immunoreactive epidermal cells induced by chronic UVB Irradiation harbor the same p53 mutations as squamous cell carcinomas in the skin of hairless SKH-1 mice.

Treatment of SKH-1 hairless mice with UVB (30 mJ/cm(2)) twice a week for 20 weeks results in the formation of cellular patches, long before the appearance of tumors, that are visualized in epidermal sheets with an antibody (PAb240) recognizing mutated p53 protein. Direct sequencing analysis of the whole coding region of the p53 gene (exons 2-11) detected one or two mutations in 64.4% of 104 analyzed patches and no mutations in nonstained adjacent normal controls.

Administration of green tea or caffeine enhances the disappearance of UVB-induced patches of mutant p53 positive epidermal cells in SKH-1 mice.

Irradiation of female SKH-1 hairless mice with UVB (30 mJ/cm2) twice a week for 10-20 weeks resulted in the formation of a large number of cellular patches (>8 adjacent cells/patch) that are recognized with an antibody (Pab240) which recognizes mutated but not wild-type p53 protein. These patches are not recognized by an antibody (Pab1620) to wild-type p53 protein. The patches, which are considered putative early cellular markers of the beginning of tumor formation, started appearing after 4-6 weeks of UVB treatment, and multiple patches were observed after treatment for 10 weeks.

Stimulatory effect of topical application of caffeine on UVB-induced apoptosis in the epidermis of p53 and Bax knockout mice.

Shaved male or female p53(-/-) C57BL/6J mice and their wild-type littermates were irradiated once with UVB (60 mJ/cm(2)). The UVB-induced increase in apoptotic sunburn cells in p53(-/-) mice at 6-10 h after exposure to UVB was only 10-30% of that observed after treatment of p53(+/+) mice with UVB. Topical applications of caffeine immediately after UVB irradiation in female p53(+/+) or p53(-/-) mice enhanced the UVB-induced increase in apoptotic sunburn cells 6 h later by 127% and 563%, respectively.

Stimulatory effect of oral administration of green tea and caffeine on locomotor activity in SKH-1 mice.

Administration of green tea or caffeine was shown previously to inhibit ultraviolet B light-induced carcinogenesis in SKH-1 mice, and this effect was associated with a reduction in dermal fat. In the present study, oral administration of 0.6% green tea (6 mg tea solids/ml) or 0.

Inhibitory effects of tea and caffeine on UV-induced carcinogenesis: relationship to enhanced apoptosis and decreased tissue fat.

Oral administration of green tea or caffeine to hairless SKH-1 mice for 2 weeks stimulated UV-induced increases in apoptotic sunburn cells in the epidermis, and a similar effect was observed when caffeine was applied topically immediately after UV. In mice pretreated with UV for 22 weeks (high-risk mice without tumors), topical applications of caffeine 5 days a week for 18 weeks with no further UV treatment inhibited carcinogenesis and stimulated apoptosis in the tumors. Oral administration of green or black tea to UV-pretreated high-risk mice for 23 weeks inhibited skin tumorigenesis, decreased the size of the parametrial fat pads and decreased the thickness of the dermal fat layer away from tumors and directly under tumors.