Dietary factors have been implicated in the etiology of colon cancer. The salient components of high-risk diets are thought to be high intakes of meat, especially beef, and fat, especially animal fat, and low intakes of fiber. Low-risk diets are thought to be high in fiber, and low in meat and animal fat. The present study examines the effects of short-term consumption of diets hypothesized to increase or decrease the risk for colon cancer on mutagenic activity of feces. Whether the fecal mutagens responsible for the mutagenic activity observed in the study are directly involved in the etiology of colon cancer is not known. However, most known mutagens are potentially carcinogenic, and fecal mutagenic activity may be an indicator of risk for colon cancer. Six healthy adult subjects consumed the following diets in sequence a baseline diet for one week, a low-risk lacto-ovo vegetarian, high fiber diet for two weeks, and a high-risk, high meat, low fiber diet for two weeks. Quantitative daily food intake records were kept, and daily bowel habits were recorded. Fecal samples were collected at the end of each diet period. Analyses were performed of the diets for food and nutrient intake, and of feces for percent dry weight and pH. Mutagenic activity of the fecal samples was assayed using the fluctuation test for mutagens. The subjects' habitual diets, although omnivorous, were found to closely resemble a low-risk diet pattern. Analysis of the vegetarian and high meat diets confirmed that the subjects had consumed foods which respectively represented the components of high-risk and low-risk diets. The overall fecal mutagenic activity obtained with samples on the high meat diet was higher than with the vegetarian or baseline diets using Salmonella typhimurium TA 98 and TA 100. The trend towards higher mutagenicity on the high meat diet over the vegetarian diet was consistent for all six subjects using TA 100, and for five of the six using TA 98. The vegetarian and baseline diets resulted in similar overall mutagenic activity. Analysis of the fecal sample parameters using the Kruskal-Wallis one-way analysis of variance showed no significant differences among fecal samples from the three diet periods with respect to wet weight, dry weight, percent dry weight, pH or number of daily bowel movements. However, a sign-test analysis showed a significant trend (p<0.05) towards fewer bowel movements on the high meat diet than on the vegetarian diet. There were significant differences among subjects for all of the fecal sample parameters (p<0.01 or p<0.001). Spearman rank correlations were significantly positive between mutagenic activities using bacterial strains Salmonella typhimurium TA 98 and TA 100 for the baseline diet (p<0.01) and the vegetarian diet (p<0.05). There were also significant positive correlations (p<0.001) between pH and fecal mutagenicity on the high meat' diet using tester strain TA 100, and between wet weight and dry weight. The results of this study indicate that the overall mutagenic activity of human feces can be increased over a period of two weeks by the consumption of a diet high in meat and low in fiber, which is considered to be a high-risk diet for colon cancer. / Land and Food Systems, Faculty of / Graduate

Mutagens in feces have been suggested to be an indicator for risk of colon cancer. Groups consuming vegetarian diets are known to have lower mortality from colon cancer. The purpose of this study was to assess mutagenic activity in feces of persons habitually consuming vegetarian or non-vegetarian diets and to try to identify dietary factors or other health habits which contributed to fecal mutagenicity. Eleven strict vegetarians, six ovo-lacto vegetarians and twelve non-vegetarians, all from the Greater Vancouver area, participated in this study. Data on certain demographic variables and health habits, as well as dietary intake (food frequency and food records), were taken. One fecal sample was collected from each subject for the study. Aqueous extracts of the feces were prepared and analyzed for mutagens using the fluctuation test with Salmonella typhimurium TA100 and TA98. Levels of mutagenicity on each organism were then statistically correlated with frequency of consumption of food groups, nutrient intake, demographic data and health habits. Ovo-lacto vegetarians and strict vegetarians, as groups, had significantly lower levels of fecal mutagens than non-vegetarians in the TA100 assay. With TA98, only the strict vegetarians had lower levels of mutagens compared to the non-vegetarians. The presence of several different mutagenic compounds was indicated. Significant negative correlations were found with mutagenicity on TA98 for all subjects with the following dietary variables: fruits and juices, fiber and iron. Similar negative correlations were found for total carbohydrate and Southgate fiber intakes and mutagenicity on TA100. Within the group of non-vegetarians, there were negative correlations with mutagenicity on TA98 and total protein and with mutagenicity on TA100 and calcium. With the demographic variables and health habits, no clear pattern emerged to indicate factors which would predict lowered mutagenicity for all subjects. It is concluded that vegetarians have lower levels of fecal mutagenicity and that several dietary factors are likely to contribute to this phenomenon. / Land and Food Systems, Faculty of / Graduate

The water solubility of drug molecules plays an important role in consideration of formulation development to treat a wide range of diseases. In this project, two kinds of drug delivery systems, cyclodextrins and liposomes, were developed for insoluble drug delivery to treat Alzheimer's disease (AD) and colorectal cancer (CRC), respectively. AD is an irreversible neurodegenerative disorder associated with the accumulation of amyloid-beta (A??) fibrils. Approximately 10% of people aged 65 and above have AD. Crocetin (CRT) is an active compound isolated from the fruits of gardenia (Gardenia jasminoides Ellis) and the stigmas of saffron (Crocus sativus L.). It has been reported to show various neuroprotective activities. However, poor water solubility and bioavailability are the major obstacles in developing pharmaceutical formulations of CRT. To address the issues, CRT liposomal formulations and CRT-cyclodextrin inclusion complexes were developed and evaluated. CRT-cyclodextrin inclusion complexes significantly increased the water solubility of CRT from the range ??g/mL to mg/mL. The CRT-??-cyclodextrin inclusion complex (1:3 molar ratio of CRT/??-cyclodextrin) was chosen for further studies as it showed the highest encapsulation efficiency (94.73 ?? 0.86%). The formulation had no toxicity to neuronal cells nor AD model cells within the experimental concentration range (0.625 to 100 ??M of CRT). It could downregulate the expression of C-terminus fragments and decrease both intracellular and extracellular levels of A??, which are hallmarks of AD. It also showed dose-dependent neuroprotective and antioxidant effects against H2O2-induced cell death. Pharmacokinetics and biodistribution studies showed that this CRT-??-cyclodextrin inclusion complex was suitable for intravenous administration. The formulation significantly increased the bioavailability of CRT and facilitated CRT crossing the blood-brain barrier to enter the brain. Similar to AD, CRC is increasingly prevalent with aging populations. Approximately 60% of CRC patients are aged 70 and above. Halofuginone (HF) is an active pharmaceutical ingredient (API) originated from Chinese quinine (Dichroa febrifuga Lour.) and artesunate (ART) is a semi-synthetic derivative of artemisinin (ATS) extracted from annual wormwood (Artemisia annua L.). Both APIs show anticancer activities by inhibiting the growth of CRC. However, low aqueous stability limits their applications. Liposome formulation with surface functionalization by CPP2 cell-penetrating peptide was developed to deliver HF and ART for targeted CRC therapy. CPP2 is a peptide that can selectively penetrate colon cancer cells. The liposomal drug formulations had uniform particle size (about 100 nm), high encapsulation efficiency (over 80%) and good stability upon 14 days of storage. In cellular uptake study, CPP2-modified liposome showed stronger permeability and selectivity to colon cancer lines without inducing lysosomal degradation. CPP2 surface-modified liposomal drugs demonstrated greater anticancer activities than free form of drugs or conventional liposomal drugs. Combinations of HF and ART formulations notably decreased cancer cell viability as compared to single formulation alone, which indicated that HF and ART formulations exhibited synergistic anticancer effects at specific ratios. To conclude, the drug delivery systems, cyclodextrins and peptide-modified liposomes, which were developed for AD and CRC treatment, successfully improved the aqueous solubility of insoluble APIs extracted from Chinese medicinal plants.

Thesis (Ph.D. (Biochemistry)) -- University of Limpopo, 2021 / Cancer remains one of the leading causes of morbidity and mortality worldwide with an estimated 9.9 million deaths in 2020. Cancer treatment regimens such as chemotherapy and radiotherapy have over the years fallen short due to drug resistance, toxicity, damage to normal healthy cells and tissues surrounding the treatment area. Moreover, they have shown very limited survival benefits for most advanced staged cancers such as colorectal cancer, which in 2020 was responsible for 3 728 deaths with a 6.8% incidence rate. Despite the many efforts in developing alternative chemotherapeutic strategies, cancer of the colon and cancer, in general, remains a burden. For centuries, plants and plant derivatives have been exploited for their nutritional and medicinal properties and now serve as chemical scaffolds or templates for designing and synthesising products with pharmacological importance. Herbal medicines are claimed to enhance therapeutic effects and are often used in combination with chronic medication. However, the concurrent use of herbal medicines and synthetic drugs may affect the pharmacokinetic profile of therapeutic drugs or trigger unexpected and undesirable effects. This study aimed to characterise the leaf extracts (crude water and crude methanol) of Momordica balsamina and investigate their potential anticancer activity on HT-29 colon cancer cells. The study also aimed to asses the effect of the extracts on drug metabolising enzymes (CYP450), specifically those which metabolise 5-Fluorouracil (5-FU) prodrugs or are inhibited by 5-FU since it is one of the first-line treatments for colon cancer. Dried powdered leaves were extracted using water and absolute methanol to obtain crude water and crude methanol extracts, respectively. For characterisation, the extracts were spotted on thin-layer chromatography (TLC) plates and further screened using chemical tests. The ferric ion reducing power assay and Liquid chromatographymass spectrometry were used to determine the antioxidant activity of the extracts and to identify prominent or abundant compounds in each extract, respectively. To assess the cytotoxic effect of the extracts and 5-FU, HT-29 colon cancer cells and C2C12 muscle cells, which were used as a model for normal cells, were exposed to concentrations that ranged from 0 to 2000 µg/ml for the water (H2O) extract, 0 to 300 µg/ml for the methanol (MeOH) extract or 0 to 100 µg/ml of 5-FU for 24 and 72 hours, and subjected to the MTT assay. The effect of the extracts on the efficacy of 5-FU was xxi assessed using the MTT assay by combined treatments of the extract and 5-FU. Genotoxicity of the extracts was assessed on the C2C12 cells using the Muse™ MultiColour DNA Damage kit. The generation of intracellular reactive oxygen species (ROS) was assessed by flow cytometry using the DCFH-DA assay. The JC-1 and acridine orange (AO)/propidium iodide (PI) staining assays were used to assess the effect of the extracts on the mitochondrial potential as well as cell and nuclear morphology, respectively. Apoptosis was quantified by flow cytometry using annexin V/PI and caspase activation assessed using the Caspase-8 and Caspase-9 colourimetric assay kits. The pro-apoptotic mechanism(s) was determined by assessing the expression profiles of selected apoptosis regulatory proteins using the human apoptosis antibody array kit. Cell cycle analysis by flow cytometry was conducted to determine the effect of the extract on the cell division cycle. Moreover, to determine the potential of herb-drug interactions, the Vivid® CYP450 Screening kits and P-gp-GloTM Assay Systems with P-glycoprotein were used to assess the effect on the activity of drug metabolising enzymes and drug transportation, respectively. The results showed that the MeOH extract possessed fewer polar compounds, higher ferric iron-reducing power, and a relative abundance of flavonol glycosides, cucurbitane-type triterpenoid aglycones, and cucurbitane-type glycosides than the H2O extract. The MeOH extract was further selectively cytotoxic to the HT-29 colon cancer cells at 24 hours of treatment and selectively induced genotoxicity in HT-29 cells. The H2O extract, however, was not cytotoxic to the HT-29 cells at all the tested concentrations at 24 and 72 hours of treatment. Analysis of nuclear and cell morphology suggested that the decrease in the percentage viability of MeOH extracttreated cells was associated with apoptotic cell death. Apoptosis was further confirmed by the loss of mitochondrial potential, increase in ROS production, caspase-8 and -9 activities as well as Annexin-V/PI-stained cells. Cell cycle analysis revealed cell cycle arrest at the S phase in MeOH extract-treated cells. Analysis of protein expression profiles revealed that the extract modulated various proteins that play a role in the promotion or inhibition of apoptosis. Moreover, the MeOH extract was shown to inhibit the activity of CYPs 1A2, 2A6, 2C8, and 2C9, while the H2O extract showed no significant inhibitory effects on the activity of all tested CYPs and 5-FU only significantly inhibited the activity of CYP2C9. However, combinatory treatments with 5-FU and the MeOH extract were shown to have no additive or diminishing effects on the efficacy of 5-FU on the activity of all the tested CYP enzymes. Treatment with 5FU (0.008 – 32 μg/ml) and the H2O extract (0.02 – 200 μg/ml) was shown to stimulate the ATPase activity of P-gp, while the MeOH extract significantly inhibited its activity with concentrations of 0.2, 2, and 20 μg/ml. In conclusion, the MeOH extract selectively induced cancer cell toxicity, genotoxicity as well as S phase cell cycle arrest and apoptosis via the intrinsic and extrinsic pathways. The anticancer activity of the MeOH leaf extract of M. balsamina as well as its antioxidant potential may be attributed to the presence and relative abundance of flavonol glycosides, cucurbitane-type triterpenoid aglycones, and cucurbitane-type glycosides. Although the MeOH extract may potentially reverse the effects of P-gp multidrug resistance by decreasing its activity, its inhibition of the activity of CYPs 1A2, 2A6, 2C8 and, 2C9, which are involved in the metabolism of more than 80% of the drugs in clinical use may suggest that co-administration of the MeOH extract may still result in increased plasma levels of drugs, thereby resulting in toxicity. The H2O extract, although not pro-apoptotic as the MeOH extract may still have the potential to be developed as a nutraceutical as it was shown to exhibit no adverse drug interactions and because this species is known to possess a wide variety of nutritional and medicinal values. / South African Medical Research Council (SAMRC) Research Capacity Development Initiative.

Indiana University-Purdue University Indianapolis (IUPUI) / Men’s adherence to masculinity norms has been implicated as a risk factor for unhealthy behaviors (e.g., drinking to intoxication, having unprotected sex with multiple, simultaneous partners) and lack of engagement in healthy behaviors (e.g., blood pressure screening, cholesterol screening, wearing protective clothing while in the sun, receipt of annual medical and dental exams) (Boman & Walker, 2010; Courtenay, 2000a, 2000b, 2011; Hammond, Matthews, & Corbie-Smith, 2010; Iwamoto, Cheng, Lee, Takamatsu, & Gordon, 2011; Locke & Mahalik, 2005; Mahalik, Lagan, & Morrison, 2006; Mahalik et al., 2003; Nicholas, 2000; Pachankis, Westmaas, & Dougherty, 2011; Pleck, Sonenstein, & Ku, 1993; Wade, 2009). Masculinity has been defined as behaviors, beliefs, and personality characteristics associated more often with men than women as well as characteristics and behaviors that society prescribes and reinforces in men (Thompson, Pleck, & Ferrera, 1992). Rooted in geographical, cultural, and temporal environments, diverse masculinities have emerged throughout the United States and the world (Connell, 1995; Courtenay, 2011). Traditional masculinity beliefs and behaviors in the United States include the sturdy oak (men should be tough, self-reliant, stoic, and confident), no sissy stuff (men should avoid feminine characteristics and behaviors), the big wheel (men should strive for success and status), and give ‘em hell (men should embrace aggressiveness, daring, and violence) (Brannon, 1976). Numerous qualitative studies have suggested that some men find cancer screening examinations involving the rectum (i.e., endoscopy for colorectal cancer [CRC] screening or digital rectal examination [DRE] for prostate cancer screening) an affront to their masculinity (see Table 1 for quotations from these studies) (Bass et al., 2011; Beeker, Kraft, Southwell, & Jorgensen, 2000; Getrich et al., 2012; Goldman, Diaz, & Kim, 2009; Harvey & Alston, 2011; Holt et al., 2009; Jilcott Pitts et al., 2013; Jones, Devers, Kuzel, & Woolf, 2010; Rivera-Ramos & Buki, 2011; Thompson, Reeder, & Abel, 2011; Wackerbarth, Peters, & Haist, 2005; Winterich et al., 2009). However, to the author’s knowledge, no quantitative studies have considered the role of masculinity in CRC screening adherence. Unfortunately, current CRC screening rates fall below the 70.5% Healthy People 2020 screening objective (U.S. Department of Health and Human Services, 2012).Research is needed to better understand relationships between men’s masculinity norms and CRC screening adherence so that interventions may be developed to reduce barriers to screening, improve screening rates, and, ultimately, decrease men’s mortality from CRC. The present study will address this gap in the literature by examining the masculinity norms and CRC screening adherence of male veterans aged 51-75 years who are at average CRC risk (Levin et al., 2008). First, the prevalence of CRC, its risk factors and warning signs as well as CRC screening techniques, screening rates, and characteristics of individuals who are adherent and non-adherent to CRC screening guidelines are summarized. Next, the concept of masculinity, theoretical and empirical support for studying masculinity norms within the context of CRC screening, and potential relationships between masculinity norms and colorectal cancer screening behaviors are described. Finally, the study methods, results, and future directions and limitations of this research are described.

No description available.

Commercial and homemade diets are currently used to treat many canine patients with acquired disorders of the colon. Clinically, the efficacy of diets has been found to be unpredictable. Only one study to date has evaluated the effect of diet on the colonic mucosa. This study showed that diet did not observably alter the colonic mucosa of normal dogs, when biopsy samples were evaluated by light microscopy. The effect of diet on colonic ultrastructure in the dog, using transmission electron microscopy, has not previously been investigated. To determine the effect of diet on colonic ultrastructure, cell height, cell area, microvillus height, number of microvilli/apex width and basement membrane width were measured. Ten cells per animal were evaluated. Six dogs were assigned to the control group and fed the control diet for the duration of the study. Six dogs were fed each of the three test diets at four week intervals. The test diets used included a high fiber diet, a hypoallergenic diet and a highly digestible diet. These diets were selected because they are the diets most often recommended for the canine patient with colonic disorders. The value for cell height for the highly digestible group was significantly greater than the other groups, as measured by ANOV A and Duncan's multiple comparison test. No other significant differences were found. The biological relevance of a significantly different value for cell height alone is difficult to evaluate, as other parameters that would indicate an alteration in maturation or proliferation of the colonic epithelial cells did not change. value for cell height alone is difficult to evaluate, as other parameters that would indicate an alteration in maturation or proliferation of the colonic epithelial cells did not change. Therefore, we conclude that commercial diets do not have an effect on the colonic ultrastructure of normal dogs. Although no effect of diet was found, this study does provide morphologic measurements that can be used as a basis for future ultrastructural studies of the colonic mucosa. / Master of Science

TCP-1是一种新型的定向于肿瘤血管的多肽，通过小鼠体内的噬菌体展示技术筛选得到。在之前的研究中，我们已证明TCP-1具有定向于肿瘤血管并有效靶向运输抗肿瘤药物和显像剂的特性。本研究的目的是进一步研究在原位结肠癌模型中定向运输抗肿瘤药物肿瘤坏死因子(TNFα)，以及在结肠癌临床样本中运输显像剂异硫氰酸荧光素(FITC)的能力。并对TCP-1与肿瘤坏死因子的融合蛋白TCP-1/TNFα的抗肿瘤机制进行阐述。 / 本研究中，我们首先尝试用TCP-1作为载体，将增强绿色荧光蛋白靶向运输至肿瘤血管。结果证明TCP-1可以成功将蛋白运输到在肿瘤血管而非其它正常的组织器官上。TCP-1还可以靶向运输肿瘤坏死因子并增强其抗肿瘤作用。和肿瘤坏死因子比较，融合蛋白TCP-1/TNFα处理组的凋亡细胞数量增多，肿瘤微血管数目减少，并且无明显毒副作用。与结肠癌的一线化疗药物5-氟尿嘧啶(5-FU)联合给药后，与TNFα与5-FU联合给药相比较，融合蛋白TCP-1/TNFα联合5-FU在以下方面具有更明显的作用：抑制肿瘤生长，增加肿瘤细胞凋亡和抑制肿瘤细胞增殖，促进肿瘤血管正常化，升高瘤内免疫细胞以及减轻骨髓和脾内的免疫抑制反应。经检测TCP-1的靶向运输增加了瘤内的TNFα以及5-FU的浓度。这些都表明TCP-1不但可以靶向运输TCP-1/TNFα至肿瘤血管，还可以增加CD8+细胞的浸润增加瘤内免疫反应以及增加血管对抗肿瘤药物的通透性。以上都对抗肿瘤起到重要作用。 / 在临床的结肠癌样本中，TCP-1对肿瘤血管的结合能力也得到了证实。48.98%的结肠癌样本对TCP-1的结合为阳性。统计学分析显示TCP-1的结合与结肠癌的分期和肿瘤位置有关，对于N2期，位于乙状结肠的肿瘤的结合尤为明显。本研究的主要目的是将分离鉴定出的TCP-1发展成为结肠癌的生物标记，并且作为运输抗肿瘤药物和显像剂的载体应用于结肠癌的诊断和治疗中。鉴于TCP-1的靶向运输特点，将会有机会研发更多的抗肿瘤药物，同时增强传统化疗药的抗肿瘤作用。这些都可以优化肿瘤治疗的方案。综上所述，TCP-1是一种在结肠癌治疗诊断中具有广阔前景的多肽。 / TCP-1 is a novel vasculature-targeting peptide. It was discovered through the in vivo phage library selection in mice. It was demonstrated that TCP-1 peptide exhibited a homing ability to the neovasculature of colon tumors and was capable of efficiently delivering imaging agents and chemotherapeutic drugs to this target site. The current study is to further investigate the targeting ability of TCP-1 to deliver a known immunomodulator, tumor necrosis factor α (TNFα) as an example of anti-cancer drug in an orthotopic colorectal cancer (CRC) model and fluorescein isothiocyanate (FITC) as imaging agent for testing the binding capacity for tumors in colorectal cancer patients. The mechanisms for the action of this novel biologic TCP-1/TNFα in the treatment of colon cancer in mice were also defined. / In this study, we observed that TCP-1 peptide delivered enhanced green fluorescent protein (EGFP) only to tumor blood vessel other than normal organs after TCP- 1/EGFP injection. This was not observed after EGFP injection. This finding showed that TCP-1 can deliver biologic protein to the tumor blood vessels. Furthermore, results from TNFα or TCP-1/TNFα targeted delivery experiments showed that TCP- 1/TNFα displayed stronger anti-cancer effects than TNFα alone on the induction of apoptosis and reduction in number of microvessels in the tumors, without significant effect in systemic toxicity. In the combined therapy with 5-fluorouracil (5-FU), a standard drug for colon cancer treatment, pretreatment with low dose (1 ng TNFα /mouse) of TNFα or TCP-1/TNFα potentiated the anti-cancer action of 5-FU. In this regard, TCP-1/TNFα could significantly reduce tumor size and weight, increase number of apoptotic cells, inhibit tumor cell proliferation, normalize tumor blood vessels, facilitate infiltration of immune cells to tumor mass and attenuate immunosuppression in bone marrow and spleen. Moreover, TCP-1 could significantly increase intratumoral levels of TNFα and 5-FU. It was also suggested that TCP-1 could selectively deliver TNFα to the tumor blood vessels and modulate the immune response by increasing CD8+ cells infiltration to tumors and increase vascular permeability to 5-FU. These observations may be the key actions to reduce tumor growth. / The binding ability of TCP-1 was also detected in clinical samples from colorectal cancer patients in which 24/49 (48.98%) tumor tissues were positive with TCP-1 binding signal. Statistical analysis showed that TCP-1 had a strong and significant binding with colorectal cancer at the N2 stage among the different colorectal cancer stages (P=0.028) and location in the colon at the sigmoid (P<0.001). / Our study also focused on the isolation and identification of the binding molecule of TCP-1 in order to develop it into a biomarker for CRC and using TCP-1 as a carrier in delivering anti-cancer drugs and imaging agents to colon tumors for cancer therapy and diagnosis. With the homing property of TCP-1 on colon tumor blood vessels, new types of anti-cancer drugs will be developed and their combinations with conventional chemotherapy drugs will optimize the therapeutic outcome and improve regimen of treatment for CRC. Taken together, TCP-1 peptide appears to be a promising agent in molecular imaging and drug delivery for CRC diagnosis and therapy. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Lu, Lan. / Thesis (Ph.D.) Chinese University of Hong Kong, 2014. / Includes bibliographical references (leaves 157-177). / Abstracts also in Chinese. / Lu, Lan.

丹参是一种著名的传统中药，富含丹酚酸和丹参酮。其中，丹参酮的潜在抗肿瘤作用近年来引起众多关注。本研究评价了主要的丹参酮及其衍生物对结肠癌细胞的细胞毒性。结果显示DHTS具有最强的抗结肠癌活性和显著的肿瘤特异性细胞毒性，其细胞毒性主要由于凋亡诱导而不是引起坏死。初步的构效关系分析提示丹参酮母环结构中的A环和B环增加的离域性有助于提高其对结肠癌细胞的细胞毒性，而非二维结构及较小的D环也是进行结构改造的可能方向。 / 基于以上发现，本研究进一步探讨了DHTS的体内外抗肿瘤活性及内在机制。本研究发现DHTS的促凋亡活性并不依赖于p53的表达，而依赖于caspase活性及线粒体介导的细胞质中氧自由基 ROS及钙离子的聚集。DHTS可引起浓度及时间依赖caspase-9/-3/-7的活化而并未显著引起caspase-8的活化，这一现象发生于同样以浓度及时间依赖方式进行的线粒体中cytochrome c及AIF转位之后。在DHTS诱导的结肠癌细胞凋亡中，cytochrome c及caspase介导的凋亡通路及AIF介导的凋亡通路均被激活并显示出两条通路之间的交叉调控。 / 此外，线粒体在DHTS的促凋亡活性中的作用在本研究中被深入探讨。本研究发现线粒体可能是DHTS的一个直接靶点, 而氧化磷酸化复合体III则更可能是其作用位点。DHTS可以引起迅速而明显的线粒体功能障碍，随之引起细胞质中大量的氧自由基及钙离子聚集，诱导凋亡的产生。 / 与体外结果一致，本研究证实了DHTS对免疫缺陷小鼠中的结肠癌移植廇也具有明显的抗肿瘤作用。与溶媒对照组比较，DHTS治疗组中移植廇的增长显著被减缓，在治疗终点时的廇体积与重量也显著被降低。TUNEL检测确认DHTS诱导移植廇中癌细胞的显著凋亡。免疫荧光检测也发现DHTS诱导caspase-3及caspase-7在移植廇中癌细胞的明显活化。 / 综上所述，本研究提供了丹参酮抗结肠癌活性的一些初步构效关系的信息，为提高丹参酮抗结肠癌活性的结构改造提供一定的参考。更重要的是，本研究证明了DHTS的体内外抗结肠癌活性并探讨了其作用机制及可能靶点，为DHTS作为新的应用于抗结肠癌药物或辅助治疗用药提供了临床前研究证据。 / Salvia miltiorrhiza Bunge, also known as Danshen, rich in phenolic acid and tanshinones, has been widely used to treat various kinds of diseases including heart diseases and hepatitis in China with minimal side effects. Among the tanshinones, tanshinone I, tanshinone IIA, cryptotanshinone and dihydrotanshinone I are the major bioactive constituents in this herb. In this study, the anti-colon cancer potential of five tanshinones and six derivatives of tanshinone IIA were evaluated in several colon cancer cell lines. It was found that apoptosis but not necrosis contributed significantly to the cytotoxicity of the tanshinones. Dihydrotanshinone I (DHTS) was confirmed to be the most potent and selective anti-cancer compound among the tanshinones tested in this study. Preliminary SAR (structure activity relationship) of tanshinones reveals that the increase of delocalizability of A and B rings in the chemical structure of the tanshinones enhances their cytotoxicity on cancer cells, while compounds with a non-planar and small sized D ring region are better choices for anti-cancer effect. / The underlying mechanisms of the anti-colon cancer activity of DHTS were further studied. It was found that apoptosis induced by DHTS was p53 independent but caspase dependent, which was closely related to intracellular accumulation of ROS (reactive oxidant stress) and calcium mediated by mitochondria. A concentration- and time-dependent activation of caspase-9,-3,-7 but not caspase-8 by DHTS in HCT116 cells was detected after the translocation of cytochrome c and AIF (apoptosis inducing factor) from mitochondria. In this process, the crosstalk between the caspase-dependent and caspase-independent pathways was firstly shown in the apoptotic mechanism of DHTS. To this end, the release of cytochrome c happened first and the translocation of apoptosis inducing factor (AIF) was prevented by a pan caspase inhibitor. In the meantime, the release of cytochrome c and activation of caspase-9 and PARP (poly-ADP-ribose polymerase) cleavage were decreased after AIF knockdown. Especially, mitochondrion was suggested to be the direct target of DHTS and OXPHOS complex III but not OXPHOS complex I was probably the acting site of DHTS. / In accordance with the results obtained in vitro, the potential anti-colon cancer activity of DHTS was also observed in nude mice with xenograft tumors and the compound did not produce any observable systemic toxicity. DHTS efficiently delayed tumor growth by decreasing the tumor size and weight through the induction of apoptosis in cancer cells but not by inhibition of cell proliferation. In the same tissues, a distinct activation of caspase-3 and caspase-7 in tumor cells was also detected by immunofluorescence assay. / Collectively, the present study provides preliminary information about the SAR of the anti-colon cancer activity for tanshinones. It also confirms that DHTS is a promising compound for anti-cancer action both in vitro and in vivo. In addition, this study gives us a better understanding regarding the mechanisms of how DHTS induces apoptosis in cancer cells. All these findings could provide solid pre-clinical evidence to propel the development and application of DHTS and perhaps its derivatives as novel therapeutic or adjuvant agents for the treatment of colon cancer. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Wang, Lin. / Thesis (Ph.D.) Chinese University of Hong Kong, 2013. / Includes bibliographical references (leaves 122-132). / Abstracts also in Chinese. / Wang, Lin.

CFTR基因突變或者功能缺失是否導致包括胃腸道在內的各種組織惡性腫瘤的發生風險增加目前仍然是一個充滿爭議的問題。同時，眾所周知，緊密連接分子在腫瘤發生和轉移的過程發揮了關鍵的作用。本論文首次發現了CFTR基因與一種緊密連接分子AF-6/afadin的在人類結直腸腫瘤中的表達水平呈高度相關，并研究了CFTR和AF-6/afadin之間潛在的相互作用及其在結直腸腫瘤轉移中的功能。 / 論文的第一部份首先用實時定量PCR和免疫組織化學的方法比較了CFTR在結直腸腫瘤和正常組織的表達情況，發現CFTR表達水平在腫瘤組織中有顯著的下降。令人感興趣的是，我們同時發現CFTR和AF-6/afadin在腫瘤組織中的表達呈高度正相關，并由此展開了後續的體外實驗，研究對CFTR與AF-6/afadin之間可能的相互聯繫。利用免疫螢光染色和免疫共沉澱的方法，我們發現了這兩種蛋白分子共表達在結直腸腫瘤細胞的接觸面，并存在相互作用。用CFTR突變蛋白的免疫共沉澱實驗進一步發現，這種相互作用需要CFTR分子在細胞膜表面的正確定位及其PDZ結構域結合位點。實驗還發現與CFTR的相互作用加強了AF-6/afadin與細胞骨架蛋白系統的結合。在結直腸腫瘤細胞中CFTR基因敲减导致了AF-6/afadin蛋白定位混亂，從細胞連接位點轉移到細胞漿內，并因此破壞了上皮細胞的緊密性。極性生長細胞的跨上皮電阻降低而滲透性增強的實驗結果證實了CFTR基因敲減導致的上皮細胞緊密性的破壞。同時，AF-6/afadin蛋白水平也隨著CFTR基因敲減而降低，但mRNA水平未發生明顯的改變。蛋白降解系統的抑製劑逆轉了CFTR基因敲減細胞中AF-6/afadin蛋白的減少，提示CFTR基因敲減增加了AF-6/afadin的蛋白降解。這些實驗結果揭示了通過與細胞連接分子AF-6/afadin的相互作用以及調節，CFTR可能在上皮細胞極性的調節以及腫瘤發展過程中起重要作用。 / 論文的第二部份研究了CFTR和AF-6/afadin在結直腸腫瘤細胞上皮細胞間充質化（EMT）和轉移過程中的功能及機制。我們之前的工作已經揭示抑制CFTR的功能可以誘導結直腸腫瘤LIM1863細胞的EMT過程。本研究在另外三株不同的結直腸腫瘤細胞（SW480，SW1116和HRT-18）中進一步證實了抑制CFTR誘導的EMT過程。細胞形態轉變，上皮細胞標誌物的下調，間充質細胞標誌物的上調以及受損的上皮細胞緊密性均證實了對CFTR的抑制可以在這三種細胞中成功誘導EMT的發生。我們發現在以上所有細胞EMT的過程中，AF-6/afadin的蛋白表達水平都發生了顯著的下調。在HRT-18細胞中過表達AF-6/afadin，可以逆轉由CFTR抑製劑誘導的上皮細胞標誌分子的下調和間充質標誌分子的上調，表明抑制CFTR誘導的EMT過程是由AF-6/afadin參與介導的。此外，CFTR基因敲減導致結直腸腫瘤細胞的惡性表型強化，包括減弱的細胞粘附性，增強的貼壁依賴性生長、侵襲和遷移。另外，CFTR基因敲減激活了ERK的磷酸化，過表達AF-6/afadin可以阻斷ERK途徑的激活。CFTR基因敲減而增強的細胞侵襲性也可以被外源性AF-6/afadin或者ERK途徑的抑製劑U0126完全逆轉，提示作為AF-6/afadin的下游靶信號，ERK介導了CFTR在腫瘤侵襲中的作用。更重要的是，我們分析了CFTR和AF-6/afadin的表達水平與結直腸癌病人腫瘤進展的關係，發現在嚴重TNM腫瘤分期或者有腫瘤遠處轉移的病人中CFTR的表達水平顯著低於輕型分期或未发生转移的病人中的水平，而且CFTR和/或AF-6/afadin低表達的病人的預後更差。這些實驗結果顯示CFTR的缺失可能通過抑制AF-6/afadin和激活ERK通路而與EMT和結直腸癌癥轉移的過程高度相關。 / 綜上所述，本研究揭示了以往未報道過的CFTR在結直腸腫瘤發病機理中的功能，提示CFTR可以用作一種新的腫瘤的潛在預後指標。 / The question whether mutation or dysfunction of CFTR increases the risk of malignancies in various tissues, including the gastrointestinal tract, remains highly controversial. Meanwhile, it is well-known that adherens junctions play critical roles in the process of cancer development and metastasis. In this thesis we found for the first time a highly correlation between expression levels of CFTR and an adherens junction molecule AF-6/afadin in human colorectal tumours, and investigated the potential interaction between CFTR and AF-6/afadin and their functional roles in the metastasis of colorectal cancer. / In the first section of this thesis, we started our studies with comparing the expression of CFTR between human colorectal tumours and normal colorectal tissues. Real time quantitative PCR and immunohistochemistry results revealed a dramatically reduced CFTR level in the cancer tissues. Intriguingly, we noticed a highly positive correlation between CFTR and AF-6/afadin expression in tumours, which prompted the further in vitro investigation of possible interaction between CFTR and AF-6/afadin. Using immunofluoresent staining and co-immunoprecipitation, we found that the two proteins were colocalized at cell-cell junctions and interacted with each other in colorectal cancer cell lines. Further Co-IP experiments performed with CFTR mutations revealed that this protein interaction requires the proper localization of CFTR in cell membrane and its PDZ-interacting domain. Moreover the interaction with CFTR strengthens the binding of AF-6/afadin to the cytoskeleton system. Knockdown of CFTR in colorectal cancer cells resulted in the disorganized localization of AF-6/afadin protein from junctional sites to the cytoplasm and impaired epithelial tightness, which was confirmed by significantly reduced transepithelial resistance and increased permeability of polarized cells. Meanwhile, the protein level of AF-6/afadin was down-regulated in CFTR-knockdown cells, while no significant changes were detected at the mRNA level. Protein degradation inhibitor reversed the repression of AF-6/afadin protein in CFTR knockdown cells, suggesting the protein degradation of AF-6/afadin was increased by CFTR knockdown. These data revealed that CFTR interacts with and regulates the cell adhesion molecular AF-6/afadin in colorectal cells, which may be important in the regulation of epithelial cell polarity and cancer development. / In the second section of this thesis, we studied the functional roles and mechanisms of CFTR and AF-6/afadin in the epithelial-mesenchymal transition (EMT) and metastasis of human colorectal cancer cells. Our previous work has revealed inhibition of CFTR can induce EMT in a colorectal cancer cell line, LIM1863. This study further confirmed the induction of EMT by inhibiting CFTR in several other colorectal cancer cell lines (SW480, SW1116 and HRT-18), which was evaluated by morphological changes, down-regulation of epithelial markers or up-regulation of mesenchymal markers, and impaired epithelial cell tightness. In all these cell lines, we found that the protein levels of AF-6/afadin were significantly reduced. Over-expression of AF-6/afadin in HRT-18 cells reversed the down-regulated epithelial markers and up-regulated mesenchymal markers induced by CFTR inhibition, indicating that the CFTR inhibition-induced EMT is mediated by AF-6/afadin. Moreover, knockdown of CFTR in HRT-18 or RKO cells resulted in enhanced malignant phenotypes, including decreased cell adhesion, increased anchorage-independent cell growth, invasion, and migration. In addition, extracellular signal-regulated kinase (ERK) phosphorylation was activated by CFTR knockdown, which was abolished by over-expression of AF-6/afadin. The enhanced invasiveness of CFTR knockdown cells was also completely inhibited by either exogenous AF-6/afadin or ERK inhibitor, U0126, suggesting that ERK, the downstream target of AF-6/afadin, is involved in mediating the effect of CFTR in cancer invasion. More importantly, we analyzed the association of CFTR and AF-6/afadin expression levels with tumour progression of patients with colorectal cancer, and revealed that CFTR expression was significantly lower in patients with more severe TNM stage or with metastasis to distant organs than those with milder stage or with no metastasis. The prognosis was poorer in patients with lower expression of CFTR and/or AF-6/afadin than those with higher expressions. These data showed that dysfunction of CFTR is highly associated with EMT and colorectal cancer metastasis, probably via repression of AF-6/afadin and activation of ERK pathways. / In summary, the present study has revealed a previously undefined role of CFTR in the pathogenesis of colorectal cancer and indicated its potential as a new prognostic indicator. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Sun, Tingting. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2012. / Includes bibliographical references (leaves 113-127). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstract also in Chinese. / Abstract --- p.i / 中文摘要 --- p.iv / Publications --- p.vi / Conference Abstract --- p.vii / Declaration --- p.viii / Acknowledgements --- p.x / List of Figures --- p.xi / List of Tables --- p.xiii / List of Abbreviations --- p.xiv / Chapter Chapter 1 --- General Introduction --- p.1 / Chapter 1.1. --- Colorectal Cancer --- p.1 / Chapter 1.1.1. --- Structure of Human Normal Colon and Rectum Epithelium --- p.1 / Chapter 1.1.2. --- Staging of Colorectal Cancer --- p.3 / Chapter 1.1.3. --- Metastasis of Colorectal Cancer --- p.3 / Chapter 1.1.4. --- K-Ras mutation and It Downstream Pathways in Colorectal Cancer Metastasis --- p.11 / Chapter 1.1.5. --- Prognosis of Colorectal Cancer --- p.14 / Chapter 1.2. --- Epithelial Cell Junctional Complexes --- p.14 / Chapter 1.2.1. --- Junctional Complexes and Epithelial Cell Polarity --- p.15 / Chapter 1.2.2. --- Classic Cadherin-catenin Complex --- p.17 / Chapter 1.2.3. --- Novel Nectin-afadin Complex --- p.19 / Chapter 1.2.4. --- Cell Polarity and Cancer Progression --- p.23 / Chapter 1.3. --- Cystic Fibrosis Transmembrane Conductance Regulator (CFTR) --- p.24 / Chapter 1.3.1. --- Structure of CFTR --- p.24 / Chapter 1.3.2. --- Mutations of CFTR --- p.24 / Chapter 1.3.3. --- Functions of CFTR --- p.26 / Chapter 1.3.4. --- Cancer Risk of CF Patients --- p.33 / Chapter 1.4. --- Hypothesis and Aims --- p.34 / Chapter Chapter 2 --- Materials and Methods --- p.35 / Chapter 2.1. --- Materials --- p.35 / Chapter 2.1.1. --- Reagents and Chemicals --- p.35 / Chapter 2.1.2. --- Antibodies --- p.35 / Chapter 2.1.3. --- Primers --- p.35 / Chapter 2.1.4. --- Solutions and Buffers --- p.35 / Chapter 2.1.5. --- Human Specimens --- p.36 / Chapter 2.2. --- Methods --- p.36 / Chapter 2.2.1. --- Cell Culture --- p.36 / Chapter 2.2.2. --- Transfection --- p.36 / Chapter 2.2.3. --- Selection of Stable Clones --- p.40 / Chapter 2.2.4. --- RNA Extraction and RT-PCR --- p.40 / Chapter 2.2.5. --- Quantitative Real Time PCR --- p.41 / Chapter 2.2.6. --- Protein Extraction and Western Blotting --- p.42 / Chapter 2.2.7. --- Immunostaining --- p.45 / Chapter 2.2.8. --- In vitro Cell Functional Assays --- p.46 / Chapter 2.2.9. --- Epithelial Tightness Measurement --- p.48 / Chapter 2.2.10. --- Statistical Analysis --- p.49 / Chapter Chapter 3 --- Interaction of CFTR with AF-6/afadin and Its Importance in Maintaining Colorectal Epithelial Cell Polarity --- p.50 / Chapter 3.1. --- Introduction --- p.50 / Chapter 3.2. --- Objectives --- p.53 / Chapter 3.3. --- Experimental plan --- p.54 / Chapter 3.4. --- Results --- p.55 / Chapter 3.4.1. --- The expression of CFTR and AF-6/afadin is decreased and positively correlated in human colorectal cancer --- p.55 / Chapter 3.4.2. --- CFTR colocalizes and interacts with AF-6/afadin in human colorectal cancer cells --- p.58 / Chapter 3.4.3. --- PDZ binding motif and membrane localization of CFTR are necessary for the interaction between CFTR and AF-6/afadin --- p.64 / Chapter 3.4.4. --- Knockdown of CFTR interferes with cell junction formation in colorectal cancer cells --- p.66 / Chapter 3.5. --- Discussion --- p.71 / Chapter Chapter 4 --- CFTR as a Suppressor and Prognosis Indicator of Metastasis in Human Colorectal Cancer --- p.77 / Chapter 4.1. --- Introduction --- p.77 / Chapter 4.2. --- Objectives --- p.80 / Chapter 4.3. --- Experimental plan --- p.81 / Chapter 4.4. --- Results --- p.82 / Chapter 4.4.1. --- CFTR inhibition-induced EMT in colorectal cancer cells involves AF-6/afadin --- p.82 / Chapter 4.4.2. --- Knockdown of CFTR aggravates malignant phenotype of colorectal cancer cells --- p.86 / Chapter 4.4.3. --- AF-6/afadin mediates the effect of CFTR on cell invasion in colon cancer through ERK --- p.91 / Chapter 4.4.4. --- CFTR and AF-6/afadin expression is correlated with the prognosis of colorectal cancer --- p.97 / Chapter 4.5. --- Discussion --- p.100 / Chapter Chapter 5 --- General Discussion and Conclusion --- p.105 / Chapter 5.1. --- The diversified roles of CFTR in epithelial cells --- p.105 / Chapter 5.2. --- The unfolding relationship between CFTR and cancer development --- p.107 / Chapter 5.3. --- Future studies --- p.109 / Chapter 5.4. --- Conclusions --- p.112 / Reference List --- p.113 / Chapter Appendix A --- Reagents and Chemicals --- p.128 / Chapter Appendix B --- Antibody List --- p.131 / Chapter Appendix C --- Primer List --- p.132 / Chapter Appendix D --- Solution Recipe --- p.133