膀胱肿瘤化学防治的研究进展

膀胱癌是泌尿外科最常见的恶性肿瘤织一 ,由于复发率较高 ,死亡率逐年上升 ,防止肿瘤发生、发展和侵袭转移是降低膀胱癌高复发率和死亡率的关键。随着人们对膀胱肿瘤发生的分子生物学机制研究的深入 ,相关生物学标志物的相继问世以及某些化学药品和食品防癌作用的发现 ,尤其是癌症化学防治取得的一定的成功 ,使得防止和逆转膀胱肿瘤癌前病变成为可能 ,为此 ,本文对膀胱肿瘤化学防治近年的研究进展进行综述 ,为预防和控制膀胱肿瘤提供指导     

Inhibitory Effect of Cryptoporic Acid E, a Product from Fungus Cryptoporus volvatus, on Colon Carcinogenesis Induced with N-Methyl-N-Nitrosourea in Rats and with 1,2-Dimethylhydrazine in Mice

The antitumorigenic effect of cryptoporic acid E (CPA-E), a dimeric drimane sesquiterpenoid isolated from the fungus Cryptoporus volvatus , on colon carcinogenesis was investigated. Female F344 rats given an intrarectal instillation of 2 mg of N-methyl-N-nitrosourea 3 times weekly in weeks 1 and 2 were fed diet containing 0.2% CPA-E from week 3. Femal ICR mice given 15 weekly intraperitoneal injections of 10 mg of 1,2-dimethylhydrazine/kg body weight during weeks 1 to 15 were fed diet containing 0.06% CPA-E from week 1. The experiment was terminated at week 35 for rats and at week 25 for mice. The incidence and the number of tumors per animal were reduced in CPA-E-fed animals compared to the controls: 31% vs. 75% (P<0.05) and 0.4±0.2 (SEM) vs. 0.9 ± 0.2 (0.1> P >0.05) in rats, and 31% vs. 63% (0.1>P>0.05) and 0.4±0.2 vs. 2.4 ± 0.8 (P<0.05) in mice (16 animals in each group). Intrarectal deoxycholic acid-induced colonic mucosal ornithine decarboxylase activity was significantly lowered in CPA-E-fed animals compared to controls. This shows an antipromoting activity of CPA-E against colon carcinogenesis. Thus, it was concluded that CPA-E inhibits colon cancer development in both rats and mice treated with 2 different colon carcinogens.     

Cyclooxygenase-2 expression: a potential prognostic and predictive marker for high-grade ductal carcinoma in situ of the breast

AIMS: To study cyclooxygenase-2 (COX-2) expression in ductal carcinoma in situ (DCIS) of the breast and its association with histological features. COX-2, an inducible prostaglandin synthase, has been shown to be important in mammary carcinogenesis, being associated with increased tumour size and unfavourable outcome in breast cancer. Animal studies indicate that COX-2 inhibition is effective in the prevention and treatment of mammary cancers. METHODS AND RESULTS: Fifty-one cases of DCIS diagnosed during 1990-2000 were reviewed. Immunohistochemistry for COX-2 was performed and the COX-2 staining scores were correlated with histological features. The majority of cases [41 of 51 (80%)] had positive COX-2 staining, of which 13 cases (25%) had strong staining. High nuclear grade DCIS was significantly associated with increased COX-2 staining (P = 0.04). CONCLUSIONS: High-grade lesions are known to be associated with a higher recurrence rate following excision and are often oestrogen receptor negative, and as such, may be less responsive to adjuvant tamoxifen therapy. There is a need to examine further the role of COX-2 expression in DCIS, as both a prognostic and predictive factor.     

Dietary retinoids and carotenoids in rodent models of mammary tumorigenesis

In this review of the scientific literature the relationship between retinoids, carotenoids, and mammary carcinogenesis is examined. Several retinoids have shown promise as chemopreventive agents against chemically induced mammary carcinogenesis in mice and especially in rats. The most promising retinoids are retinyl acetate (RA) and N-(4-hydroxyphenyl)retinamide (4-HPR, fenretinide). In rats, dietary administration of these retinoids reduced tumor incidence and multiplicity, and increased the latency of DMBA or MNU-induced mammary cancers. In mice, 4-HPR reduced the number of hyperplastic alveolar nodules and the number of tumors in MTV- and MTV+ mice, respectively. Among retinoids, 4-HPR is at present the most promising analogue, due to its ability to concentrate in the mammary gland. The combination of 4-HPR with tamoxifen not only is more effective in suppressing breast cancer than either agent alone, but also inhibits the appearance of subsequent cancers following the surgical removal of the first tumor. These studies suggest that retinoids, like tamoxifen, may be applicable to the prevention of contralateral breast cancer in women who underwent breast cancer surgery. It is also becoming evident that differentiation therapy and chemoprevention can become attractive alternative approaches to intensive cytotoxic chemotherapy. The role of carotenoids in the prevention of mammary carcinogenesis, however, is ambiguous. Poor absorption and low levels of carotenoids that reach the target tissues complicate interpretation of data in rodent models of mammary carcinogenesis. Very few animal studies are presently available in which purified carotenoids were found effective against mammary carcinogenesis. These results do not justify undertaking clinical evaluation of individual carotenoids against breast cancer at this time.     

亚硒酸钠和维甲酸对MNNG诱导人全血白细胞非程序DNA合成的影响

本文应用非程序ＤＮＡ合成（ＵＤＳ）试验，观察了亚硒酸钠（Ｎａ２ＳｅＯ３）和维甲酸（ＲＡ）单独和联合作用对致癌物ＭＮＮＧ诱发的人全血白细胞ＤＮＡ损伤的影响。结果表明，Ｎａ２ＳｅＯ３和ＲＡ均具有抗诱变作用；当Ｎａ２ＳｅＯ３（０．１μｇ／ｍｌ）和ＲＡ（０．１μｇ／ｍｌ）联合作用时，也可明显降低ＭＮＮＧ诱发的ＵＤＳ值，其联合抑制作用大于Ｎａ２ＳｅＯ３的单独作用。实验结果还显示，Ｎａ２ＳｅＯ３作为抗癌剂，它在高剂量时又呈现遗传毒性。     

金蒲抑瘤片在实验诱发大鼠肝癌过程中的作用

目的探讨金蒲抑瘤片对黄曲霉毒素B1(aflatoxin B1,AFB1)致肝癌作用的影响。方法实验动物随机分为高剂量、低剂量和对照组。用AFB1处理各组动物,高、低剂量组大鼠在接受AFB1期间分别喂含量为9.3和2.3g/kg的金蒲抑瘤片混合饲料,对照组喂基础饲料。8周后处死动物,观察各组动物肝组织内γ-谷氨酰转肽酶阳性肝细胞增生(γ-glu-tamyltranspeptidase-positive hyperplastic livercell,γ-GT)灶的数量和大小。结果高、低剂量金蒲抑瘤片均能减少AFB1诱发的γ-GT灶的数量和大小高、低剂量组的数量分别为0.90和3.72个/cm2,均低于对照组6.10个/cm2,抑制率分别为85%和39%,高剂量组与对照组相比差异有统计学意义,t=2.597,P=0.028。高、低剂量组的大小分别为0.24和1.94mm2/个,均低于对照组2.36mm2/个,抑制率分别为90%和17%,但差异无统计学意义,P>0.05。结论金蒲抑瘤片有减少AFB1诱发大鼠肝γ-GT灶的数量和大小的作用,而高剂量金蒲抑瘤片的减少趋势更强。     

Inhibition of cell cycle and induction of apoptosis by 2‐oxoheksyl isothiocyanate and alyssin in cell lines carrying various inherited BRCA1 mutations

An important aspect of the chemopreventive activity of isothiocyanates (ITC) is their ability to induce cell growth inhibition and apoptosis. In this study, the effect of two sulforaphane analogues, 2‐oxoheksyl isothiocyanate and alyssin, on lymphoblastoid cells, derived from people carrying four different germ‐line mutations in BRCA1 gene, was tested and compared to the effect on wild type cells. The mutations studied were: C61G; 3819del5; 4153delA, and 5382INSC. Changes in cell viability and density after 2‐oxoheksyl isothiocyanate and alyssin treatment were evaluated, as well as cell cycle progression, mitochondrial membrane potential changes, and phosphatidylserine externalization. Both isothiocyanates were shown to reduce cell viability and density in all cell lines tested, as well as the change in cell cycle phase's distribution. The response of cells to two ITC tested was various, as well as mutation type‐modulated. We found that change of cellular maintenance by chemopreventive agents can be modulated by single allele BRCA1 mutation. Drug Dev. Res. 65:84–92, 2005. © 2005 Wiley‐Liss, Inc.     

Targeting events in melanoma carcinogenesis for the prevention of melanoma

Melanoma is one of the few tumors that have increased in incidence over the last few decades. Strategies devoted solely to protecting against ultraviolet radiation have, at best, had a modest impact on the development of melanoma. Chemoprevention is an under-explored approach that could significantly decrease the morbidity and mortality from this deadly cancer. However, the scientific and logistical challenges of performing clinical studies in chemoprevention require innovative approaches to prove the effectiveness of putative preventive agents. There are several pharmacological and nutriceutical agents that are mechanistically linked to events in melanoma carcinogenesis that are candidates for advanced human studies. We will review the data for several promising agents, including statins, curcumin, resveratrol, silymarin and green tea, and discuss some importance issues and concepts that should be considered in any melanoma chemoprevention strategy.     

Colon cancer: preventive agents and the present status of chemoprevention

Background: Colorectal cancer (CRC) is one of the most common cancers worldwide and a prevalent cause of morbidity and mortality. CRC has a natural history of transition from a precursor lesion, ie adenomatous polyp to cancer, that spans over 10 to 15 years providing an extended opportunity for intervention and cancer prevention. Suppression of the carcinogenic process by use of pharmacological or natural agents is the cornerstone of chemoprevention. Objectives: The aim of this review was to give an up-to-date overview on the different agents that had been studied, over the last decade, as chemopreventive agents and the current status of chemoprevention. Methods: Articles were identified by searches of PubMed and the Internet and reviewed. All articles and other referenced materials were retrieved using the keywords “colon cancer”, “adenoma”, “chemoprevention”, “non steroidal anti-inflamatory drugs”, “aspirin”, “HMG-CoA reductase inhibitors”, “bile acids”, “Difluoromethylornithine”, “hormone replacement therapy”, “mesalamine”, “curcumin”, and “calcium”. Papers were published between 1960 and 2008, with older references selected for historical significance. Only papers published in English were reviewed. Results: Recent preclinical as well as clinical trials have provided data on the potential benefit of a number of drugs and nutritional elements in the field of CRC prevention. Currently, only celecoxib is FDA approved for chemoprevention of CRC and only for high-risk patients with Familial Adenomatous Polyposis (FAP). This is mainly due to cardiovascular toxicity reported in individuals with a personal history of sporadic adenomas. Aspirin and sulindac have also repeatedly demonstrated efficacy in this setting. However, due to increased risk of associated GI toxicity their benefit will have to be weighed against their risk. Combination therapy, using lower doses of each medication, is drawing a great deal of attention and many studies utilizing a variety of chemopreventive agents are presently under study. Promising results have recently been published using sulindac and DFMO. Conclusion: Many agents have shown positive results in the field of chemoprevention however, the ideal chemopreventive agent remains to be discovered with great emphasis on need not to harm. Combining different agents may maximize effectiveness while limiting drug toxicity.     

The impact of diet and nutrition in the prevention and progression of hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is the third leading cause of cancer mortality worldwide. There is growing evidence for a chemopreventive role of nutrition in the development of HCC in at risk populations. Bibliographical searches were performed in PubMed for the terms ‘nutrition and hepatocellular carcinoma’, ‘nutrition and liver cancer’, ‘nutrition and hepatic cancer’, ‘diet and hepatocellular carcinoma’, ‘diet and liver cancer’. High dietary sugar intake should be discouraged in at risk populations. Coffee, polyphenols, vanadium, dietary fibre, fruits and vegetables show encouraging results in terms of chemoprevention. Red meat intake may be associated with increased risk of HCC. The evidence for fatty acids is inconclusive, but they might exert anti-cancer effects. Inconclusive results are available on vitamins, selenium probiotics and prebiotics. There is increasing evidence that diet may play an important role in the development of HCC, and may also have a chemopreventive role in at risk populations.