[Truncated abstract] Clinical and pathological predictors of survival for stage II and III colon cancer patients treated with or without chemotherapy: a population-based study. Aim: Using a population-based cohort of colorectal cancer (CRC), the major aims of this study were to: 1. Identify clinico-pathological markers that can be used to define a subset of stage II colon cancer patients with excellent prognosis and who therefore do not require referral for adjuvant chemotherapy; 2. Investigate whether there is a survival benefit from the use of adjuvant chemotherapy in a population-based cohort of stage II colon cancer; 3. Investigate stage III colon cancer patients for evidence of predictive markers for response to 5FU chemotherapy; 4. Investigate CRC for age-related differences in clinico-pathological and molecular features. Hypotheses to be tested: 1. A subset of good prognosis stage II colon cancers can be defined using routine pathological markers; 2. Females colon cancer patients gain more survival advantage from 5FU chemotherapy than males; 3. Tumours from young CRC patients have different molecular characteristics to those from older patients; 4. The underlying molecular characteristics of tumour can impact upon the response to 5FU chemotherapy. Methods: The study cohort consisted of 5,971 cases diagnosed between 1993 and 2003 representing over 90% of the CRCs diagnosed in the state of Western Australia. Results: The major findings of this translational research into colon cancer can be summarized as follows: The morphological features of serosal and vascular invasion allow for prognostic stratification of stage II colon cancer into

Thesis (MScMedSc (Obstetrics and Gynaecology))--Stellenbosch University, 2008. / BACKGROUND: The cryopreservation and transplantation of ovarian tissue have been shown to restore ovarian function temporarily and may also preserve the fertility of young female cancer patients until after their sterilizing cancer treatment. Since tissue samples are large and morphologically complex, the cryopreservation methodology is difficult to optimize and standardise. Ovarian tissue cryopreservation is therefore, still in its experimental stages and is not a routine option offered to cancer patients. OBJECTIVES: Our main aim was to initiate, develop and implement a practical ovarian tissue cryopreservation and re-transplantation protocol which would restore ovarian function, and possibly fertility, in young female cancer patients undergoing sterilizing cancer therapies in South Africa. The objective of this study was to improve the slow cryopreservation protocol for human ovarian tissue. The ultrastructural effects after cryopreservation with two well-known cryoprotectants, dimethyl sulfoxide (DMSO) and 1,2-propylene glycol (PROH), on early human follicles were investigated and compared to identify and the better cryoprotectant. MATERIALS AND METHODS: A single group experimental study design was used. The participants consisted cancer patients of the Gynaecological Oncology Unit of Tygerberg Hospital who entered on a basis of voluntary informed consent. Ovarian tissue was obtained by laparoscopic oophorectomy. After dissection of the ovary(ies), some fresh cortical tissue was sent for metastatic analysis and a few strips taken as fresh control. Remaining dissected ovarian cortical tissue sections of each patient were equally divided into the two cryoprotectant groups. Five resulting groups could be compared: i) fresh tissue (control group); tissue equilibrated in ii) DMSO; or iii) PROH and tissue equilibrated and cryopreserved in iv) DMSO or v) PROH. Five tissue samples per patient were therefore fixed for standard histological haematoxylin and eosin (HE) staining and transmission electron microscopy (TEM). Tissue samples showing early follicles on HE slides were sent for TEM processing. Ultrastructural studies on micrographs of primordial and primary follicles were assessed according to a scoring system which gave an indication of follicular health. Appropriate statistical tests were applied to analyse the mean scores where P≤0.05 was considered as statistically significant. RESULTS: No significant overall cryopreservation treatment effect was evident in any of the follicular ultrastructures evaluated. This result indicated that the cryopreservation protocol used did not induce significant damage to the cortex tissue compared to the fresh control group. Comparison of the effect of PROH and DMSO on the follicular ultrastructures showed that PROH tend to induce more extensive damage, especially after cryopreservation. Correlation studies showed significant positive relationships between the majority of the evaluated ultrastructures, especially between the oocyte and granulosa cell layer and basal membrane. The stromal cells and extracellular matrix did not correlate well with other structures. Correlations indicated that the granulosa cells, oocyte and basal lamina are affected similarly and that the damage in one of these structures may be representative of the damage in the other structures. CONCLUSION: The main aim of the study was achieved since results showed that no significant damage was induced by the cryopreservation protocols. Ovarian tissue cryopreserved in this study has shown to restore endocrine function temporarily after heterotopic autotransplantation in menopausal patients. From the electron microscopy evaluations, DMSO showed better cryopreservation results. The DMSO cryopreservation protocol was also more time efficient and has shown the most successful outcomes in the literature. The stromal tissue seemed to be affected differently by cryopreservation compared to the primordial follicle ultrastructures. Younger patients are needed for future studies since a larger initial follicular reserve may allow for larger follicle sample sizes.

Chapter One provides a general introduction into the biology and chemistry of nitric oxide, with particular focus on the role of nitric oxide in cardiovascular disease, cancer and hypoxia. It also details the types of organic functional groups used as nitric oxide donors, with detailed discussion of nitrate esters, furoxans and sydnonimines. Chapter Two discusses prostate cancer. It provides an overview into the development of prostate cancer, prostate cancer staging, and treatment. The key molecular aspects of prostate cancer are detailed, and the types of treatment available outlined. Chapter Three details the synthesis and activity of NCX-1102, a nitric oxide-donating analogue of the non-steroidal anti-inflammatory drug sulindac, and the synthetic work in the preparation of analogues of NCX-1102, using nitrate esters, furoxans and sydnonimines as nitric oxide-donating functional groups. The compounds prepared were tested against a prostate cancer cell line (PC3) and the cytotoxicity results are presented. Chapter Four describes the synthesis of nitric-oxide donating analogues of abiraterone, a CYP17 inhibitor for the treatment of prostate cancer. The results of cytotoxicity assays against PC3 cells are detailed. Chapter Five discusses the application of nitric oxide-donating functional groups in tandem with biologically active motifs. The synthesis of nitric oxide-donating amino acids, and their application to the preparation of nitric oxide-donating RGD peptides and prostate-specific membrane antigen inhibitors is presented, along with representative biological evaluation. Chapter Six introduces possible future work for the continuation of the project, suggesting the synthesis of fluorinated sydnonimines, prostate-specific membrane antigen inhibitors combined with for prostate cancer imaging and a “tool-box” of nitric oxide-donating bioconjugation reagents.

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.

Leung, Jackie. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2009. / Includes bibliographical references (leaves 117-131). / Abstract also in Chinese. / Abstract --- p.i / 論文摘要 --- p.iii / Acknowledgement --- p.iv / List of publications --- p.vi / List of Tables --- p.vi / List of Figures --- p.vi / Table of Contents --- p.ix / Chapter Chapter 1: --- Introduction --- p.1 / Chapter 1.1. --- Liver cancer --- p.1 / Chapter 1.1.1. --- Hepatocellular Carcinoma (HCC) --- p.2 / Chapter 1.2. --- Lung Cancer --- p.5 / Chapter 1.3. --- Pteris semipinnata L --- p.8 / Chapter 1.4. --- Extract of PsL: 5F --- p.10 / Chapter 1.5. --- Animal models in chemotherapy researches --- p.13 / Chapter 1.5.1. --- Model of HCC --- p.13 / Chapter 1.5.2. --- Model of lung cancer --- p.15 / Chapter 1.6. --- Apoptosis: Significance of programmed cell death --- p.17 / Chapter 1.6.1. --- The extrinsic pathway --- p.18 / Chapter 1.6.2. --- The intrinsic pathway --- p.19 / Chapter 1.7. --- Apoptotic molecules related to this study --- p.22 / Chapter 1.7.1. --- Bcl-2 family --- p.22 / Chapter 1.7.1.1. --- Bax --- p.22 / Chapter 1.7.1.2. --- Bcl-2 --- p.23 / Chapter 1.7.2. --- Nuclear factor kappa B --- p.25 / Chapter 1.7.3. --- Inducible nitric oxide synthase --- p.27 / Chapter 1.8. --- Side-effects of chemotherapy --- p.29 / Chapter 1.8.1. --- Chemotherapy and liver dysfunction --- p.30 / Chapter 1.8.2. --- Nephrotoxicity of chemotherapeutic agents --- p.31 / Chapter 1.9. --- Aim of study --- p.33 / Chapter Chapter 2: --- Materials and Methodology --- p.34 / Chapter 2.1. --- Animals --- p.34 / Chapter 2.1.1. --- HCC model --- p.34 / Chapter 2.1.2. --- Lung cancer model --- p.35 / Chapter 2.2. --- Tumors induction --- p.36 / Chapter 2.2.1. --- HCC induction in C3H/HeJ mice --- p.36 / Chapter 2.2.2. --- Lung cancer induction in A/J mice --- p.37 / Chapter 2.3. --- 5F preparation --- p.38 / Chapter 2.4. --- 5F treatment --- p.39 / Chapter 2.5. --- Harvest of samples and tissues --- p.41 / Chapter 2.6. --- Tumor assessment --- p.43 / Chapter 2.7. --- Investigation of apoptosis and cell proliferation --- p.44 / Chapter 2.8. --- Immunohistochemistry --- p.47 / Chapter 2.9. --- Biochemical test --- p.51 / Chapter 2.9.1. --- Liver Function Tests (LFT) --- p.52 / Chapter 2.9.1.1. --- Aspartate aminotransferase (AST) & Alanine aminotransferase (ALT) --- p.52 / Chapter 2.9.2. --- Renal Function Test (RFT) --- p.53 / Chapter 2.9.2.1. --- Serum creatinine level (CRE) --- p.53 / Chapter 2.9.2.2. --- Blood Urea Nitrogen index (BUN) --- p.54 / Chapter 2.10. --- Statistical analysis --- p.55 / Chapter Chapter 3: --- Results --- p.56 / Chapter 3.1. --- Anti-tumor effect of 5F is dose- dependent --- p.56 / Chapter 3.2. --- 5F reduces cell proliferation and induces apoptosis in-vivo --- p.60 / Chapter 3.3. --- Effects of 5F on apoptotic signaling molecules --- p.68 / Chapter 3.3.1. --- 5F up-regulates pro-apoptotic Bax and Bak --- p.68 / Chapter 3.3.2. --- 5F down-regulates anti-apoptotic NF-kappa B and Bcl-2 --- p.76 / Chapter 3.3.3. --- 5F up-regulated iNOS in HCC but not in lung cancer --- p.88 / Chapter 3.3.4. --- Regulation on Erk1/2 was associated with treatment of 5F --- p.93 / Chapter 3.4. --- Side-effect studies of 5F --- p.97 / Chapter Chapter 4: --- Discussion --- p.105 / Chapter Chapter 5: --- Conclusion --- p.116 / Bibliography --- p.117

University of Macau / Institute of Chinese Medical Sciences

Background According to the Hong Kong Cancer Registry, breast cancer is a leading causes of cancer death in among females in Hong Kong. Local data indicate breast cancer has increased over the years. Previous studies have shown that socioeconomic factors can affect incidence of breast cancer, survival rates and access to treatments. However, there is little literature regarding how socioeconomic status (SES) potentially affects local breast cancer patients. Moreover, there have been no formal studies concerning the economic burden of expensive drugs and treatments among Hong Kong women facing breast cancer. Objectives: The objectives of this study are 1) to investigate the presence of an association between demographical SES and the patient’s usage of targeted therapy, and 2) to briefly discuss how well government drug subsidies can protect patients from catastrophic payments due to expensive trastuzumab. Methods: This dissertation will use a data set from a survey called “The effect of decision aids on treatment decision making for breast cancer surgery: A randomized controlled trial”. The survey targets Cantonese-speaking Chinese females attending one of the forty public hospitals under the Hospital Authority (except for the Queen Elizabeth Hospital). Cross-tabulations and logistic regressions are used to determine the association between SES and patients’ status on using targeted therapy. Results: Bivariate analyses show that associations between SES and those using targeted therapy are only present for certain independent variables including age, education attainment and medical insurance coverage four months and ten months after surgery. The logistic regression indicates that the variables, besides medical insurance coverage, are unable to predict whether the patient chooses targeted therapy or not. Conclusion: To conclude, associations between SES and targeted therapy usage (i.e. either the patient is currently receiving or waiting for therapy) is weak. Even though associations between SES and health outcomes (such as survival and mortality) are well-established, previous studies have commented that the mechanism behind this association is difficult to disentangle. In addition, the association appears weak in this study probably due to the small sample side, complicated interactions between SES and treatment choice, and insufficient information. Second, after comparing the Samaritan Fund and Community Care Fund financial criteria with the monthly household income of females in my data set, it is noticeable that the middle class could be at risk to financial burdens when paying for expensive drugs. / published_or_final_version / Public Health / Master / Master of Public Health

Indiana University-Purdue University Indianapolis (IUPUI) / Carboxylesterases (CES) are enzymes that metabolize a wide variety of compounds including esters, thioesters, carbamates, and amides. In humans there are three known carboxylesterase genes CES1, CES2, and CES3. Irinotecan (CPT-11) and capecitabine are important chemotherapeutic prodrugs that are used for the treatment of colorectal cancer. Of the three CES isoenzymes, CES2 has the highest catalytic efficiency for irinotecan activation. There is large inter-individual variation in response to treatment with irinotecan. Life-threatening late-onset diarrhea has been reported in approximately 13% of patients receiving irinotecan. Several studies have reported single nucleotide polymorphisms (SNPs) for the CES2 gene. However, there has been no consensus on the effect of different CES2 SNPs and their relationship to CES2 RNA expression or irinotecan hydrolase activity. Three CES2 mRNA transcripts of approximately 2kb,3kb, and 4kb have been identified by multi-tissue northern analysis. The expressed sequence tag (EST) database indicates that CES2 undergoes several splicing events that could generate up to six potential proteins. Four of the proteins CES2, CES2458-473, CES2+64, CES21-93 were studied to characterize their expression and activity. Multi-tissue northern analysis revealed that CES2+64 corresponds to the 4kb and 3kb transcripts while CES21-93 is located only in the 4 kb transcript. CES2458-473 is an inactive splice variant that accounts for approximately 6% of the CES2 transcripts in normal and tumor colon tissue. There is large inter-individual variation in CES2 expression in both tumor and normal colon samples. Characterization of CES2+64 identified the protein as normal CES2 indicating that the signal peptide is recognized in spite of the additional 64 amino acids at the N-terminus. Sub-cellular localization studies revealed that CES2 and CES2+64 localize to the ER, and CES21-93 localizes to the cytoplasm. To date CES2 SNP data has not provided any explanation for the high inter-individual variability in response to irinotecan treatment. Multi-tissue northern blots indicate that CES2 is expressed in a tissue specific manner. We have identified the CES2 variants which correspond to each mRNA transcript. This information will be critical to defining the role of CES2 variants in the different tissues.

Thesis (PhD)--Stellenbosch University, 2000. / ENGLISH ABSTRACT: Pentoxifylline enhances the toxicity of radiation and has emerged as an effective modulator of the radiation response of tumour cells. The molecular mechanisms involved in the enhancement of radiotoxicity by pentoxifylline have not yet been elucidated. Cell cycle blocks, DNA repair and programmed cell death (apoptosis) are all pert of the cellular response to DNA damage and as such must be considered as targets of the drug. In this study, the influence of pentoxifylline on radiosensitisation, G2 block abrogation, DNA repair inhibition and the induction of apoptosis have been investigated in 8e11 and MeWo melanoma and 4197 and 4451 squamous cell carcinoma (SCC) cell lines. The influence of pentoxifylline on radiation-induced apoptosis in Jurkat J5 T-lymphocytic leukemia cells has also been assessed. Hela cervical carcinoma cells were used to investigate the molecular events involved in the abrogation of the G2 block by pentoxifylline. It is shown that pentoxifylline preferentially sensitises the TP53 mutant MeWo and 4451 cell lines and enhances radiotoxicity by factors of up to 14.5. In the MeWo melanoma, but not in the 4451 SCC cell line, radiosensitisation is accompanied by inhibition of DNA repair. No significant enhancement of radiation-induced apoptosis was observed in MeWo melanoma and 4451 SCC cells. However, Jurkat J5 cells showed an increase in apoptosis after irradiation in the presence of the drug. In irradiated Hela cervical carcinoma cells, pentoxifylline affects the expression of the two components of the mitosis promoting factor (MPF), namely cyclin 81 and p34cdC2, and rapidly restores cyclin 81/p34cdC2 ratios to control levels. Analysis of cyclin 81 expression in whole cells and isolated nuclei furthermore reveals an influence of the drug on the subcellular translocation of the MPF. It is concluded that G2 block abrogation is not the only mechanism involved in the radiosensitisation of tumour cells by pentoxifylline, but that DNA repair inhibition plays a role in certain cell types. Although pentoxifylline induces apoptosis in Jurkat J5 thymocytes, radiation-induced apoptosis plays no role in the radiosensitisation of the two TP53 mutant melanoma and sec cell lines. Abrogation of the G2 block by pentoxifylline, which sensitises tumour cells to a second irradiation or chemotherapeutic challenge, involves a modulation of the levels of cyclin 81 and p34cdC2, and the subcellular location of the MPF. These results are of utmost importance for the clinical potential of pentoxifylline as a dose modifier in cancer therapy. / AFRIKAANSE OPSOMMING: Pentoxifylline verhoog die toksisiteit van bestraling en het dus na vore getree as 'n effektiewe modulator van die sellulêre stralingsrespons in kankerselle. Die molekulêre meganismes betrokke by die verhoging van stralingstoksisiteit deur pentoxifylline is egter nog nie duidelik nie. Blokkering van die selsiklus, die herstel van ONS skade en geprogrammeerde seldood (apoptose) vorm almal deel van die sellulêre respons ná bestraling en word as sulks beskou as potensiële teikens van die middel. In hierdie studie is die invloed van pentoxifylline op stralings-sensitiwiteit, G2 blok verwydering, die vertraging van ONS herstel en die indusering van apoptose ondersoek in die Be11 en MeWo melanoom en 4197 en 4451 plaveisel-sel karsinoom sellyne. Die invloed van pentoxifylline op stralings-geïnduseerde apoptose in Jurkat J5 T-limfosiete is ook bestudeer. Hela servikale karsinoom selle is gebruik om die molekulêre gebeurtenisse rondom die verwydering van die G2 blok deur pentoxifylline te ondersoek. Dit word aangetoon dat pentoxifylline by voorkeur die radiosensitiwiteit van die TP53 mutante MeWo en 4451 sellyne verhoog, en stralingstoksisiteits verhogingsfaktore van tot 14.5 genereer. Hierdie effek gaan gepaard met die vertraging van ONS herstel in die MeWo melanoom, maar nie in die 4451 plaveisel-sel karsinoom sellyn nie. Die meting van apoptose toon geen noemenswaardige verhoging van stralings-geïnduseerde apoptose in MeWo melanoom óf in 4451 plaveisel-sel karsinoom selle nie. Jurkat J5 T-limfosiete toon egter wel 'n verhoging in apoptose wanneer bestraling in die teenwoordigheid van pentoxifylline gedoen word. In Hela servikale karsinoom selle affekteer pentoxifylline die uitdrukking van die twee komponente van die mitose promoverings faktor (MPF), naamlik siklien B1 en p34CdC2 , en restoreer die siklien 81/p34cdC2 verhoudings vinnig na normale vlakke. Ontleding van die siklien 81 uitdrukking in heel selle en in geïsoleerde selkerne toon verder dat die middelook die sub-sellulêre ligging van die MPF affekteer. Die gevolgtrekking word gemaak dat G2 blok verwydering nie die enigste meganisme is waardeur pentoxifylline radiosensitiwiteit verhoog nie, maar dat die vertraging van ONS herstel in sommige seltipes 'n rol speel. Alhoewel pentoxifylline apoptose verhoog in T-limfosiete, speel dit nie 'n rol in die verhoogde radiotoksisiteit wat waargeneem is in die TP53 mutante melanoom en plaveisel-sel karsinoom sellyne nie. Verwydering van die G2 blok deur pentoxifylline, wat selle meer sensitief kan maak vir 'n tweede stralings- of chemoterapie aanslag, behels die modulasie van siklien 81 en p34cdc2 vlakke en die sub-sellulêre ligging van die MPF. Hierdie resultate is van uiterste belang vir die kliniese aanwending van pentoxifylline as 'n dosis-modifiseerder in kankerterapie.

Thesis (PhD)--Stellenbosch University, 2003. / ENGLISH ABSTRACT: The "classic" prostate cell lines, DU145, PC-3 and LNCaP, have served as a valuable cell biological model for research into prostate cancer. However, their relevance may be limited because they derive from metastatic, and not from primary normal and tumour epithelium. The cell lines (1532T, 1535T, 1542T, 1542N and BPH-l) have been derived from primary benign and malignant human tumour prostate epithelium and may be more representative. Using these cell lines I have examined the role of basic cell damage responses (repair, checkpoint activation, apoptosis and associated signalling proteins, and the influence of androgen status) in cell inactivation, and its relevance to treatment. Numerous studies have suggested that loss of p53 function leads to resistance to chemotherapeutic agents and irradiation. It is shown here that the p53-inactive cell lines are, in fact, the most sensitive to chemotherapeutic agents such as etoposide, vinblastine and estramustine, whilst the p53 wild-type cell line, LNCaP, is the most radiosensitive. Notwithstanding the effects of p53 degradation by the HPV -16 E6 viral protein, the results on chemosensitivity raises the possibility that different chemotherapeutic agents may have different p53-dependent effects in different tumour cells. Androgen deprivation is demonstrated to sensitise prostate cancer cells to chemotherapeutic agents and it is shown that the hormone independent cell lines are the most chemosensitive. The LNCaP cell line displayed an increased resistance to apoptosis induced by etoposide and gamma irradiation, suggesting that androgens are capable of protection against both these DNA damaging agents. The major factors determining radiosensitivity in human tumour cell lines are known to be DNA double-strand break (dsb) induction and repair. In the prostate cell lines I find that cellular radiosensitivity correlates with the number of DNA double-strand breaks measured within 2 hours of irradiation, and that the more radioresistant cell lines show better repair competence. Conclusions as to the influence of androgen dependence on radiosensitivity and repair are not possible at this stage since only the LNCaP cell line was androgen sensitive. The fact that the 2 hour repair period can separate radiosensitive from radioresistant cells in 2 groups of human tumour cell lines highlights the role of non-homologous end-joining repair. This has implications for therapy, and is consistent with the clinical observation that prostate tumours can be successfully controlled by low dose rate-brachytherapy. To evaluate the role of apoptosis, cells were exposed to TD50 concentrations of chemotherapeutic drugs, and 60Co y-irradiation. Apoptosis was found to be low, overall, and ranged from 0.1% - 12.1%,3.0% - 6.0% and 0.1% - 8.5% for etoposide, estramustine and vinblastine, respectively. The percentage of cells undergoing druginduced apoptosis was, on average, higher in the tumour cell lines than in the normal cell lines. Gamma irradiation-induced apoptosis levels ranged from 1.3% - 7%. The LNCaP cell line yielded the lowest percentage of apoptotic cells after exposure. The l532T cell line yielded the highest percentage of apoptotic cells after exposure. Apoptotic propensity did not rank the cell lines according to their radiosensitivity. Immunoblotting demonstrated that the apoptosis-associated proteins, bax and bcl-2, are expressed at a basal level in all the cell lines tested, but no increase was detected after exposure to TD50 doses of etoposide, vinblastine and estramustine. The ratio of bax and bcl-2 also was not altered by DNA damage. No evidence was found that a correlation may exist between reproductive cell death and the expression of genes which control apoptosis. My results show that apoptosis is not a major mechanism of drug- or radiation-induced cell death in prostate cell lines. In conclusion, loss of p53 function and loss of androgen dependence was not found to be correlated with resistance of tumours to chemotherapeutic drugs. Cellular radiosensitivity was found to be correlated with the number of DNA double-strand breaks remaining after 2 hours of repair. The more radioresistant cell lines showed better repair competence. Apoptosis and genes affecting apoptosis, such as p53 and members of the bcl-2 family, do not seem to contribute significantly to the sensitivity of prostate cancer cells to anticancer drugs and irradiation. / AFRIKAANSE OPSOMMING: Die klassieke prostaat sellyne, DU145, PC-3 en LNCaP, het 'n waardevolle bydrae gemaak in die sel biologiese model in prostaat kanker. Die toepaslikheid daarvan mag egter beperk wees, aangesien hierdie sellyne afkomstig is van metastatiese, en nie van primêr normale en tumor epiteel nie. Die sellyne 1532T, 1535T, 1542T, 1542N en BPH-I is afkomstig van primêre benigne en maligne menslike prostaat tumor epiteel en mag moontlik meer verteenwoordigend wees. Deur van hierdie sellyne gebruik te maak, is die rolondersoek van die reaksie op basiese selskade (d.w.s. herstel, beheerpunt aktivering, apoptose en verwante sein proteïene, en die invloed van androgeen status) tydens die proses van sel inaktivering, asook die toepaslikheid ten opsigte van behandeling. Volgens verskeie studies lei die verlies aan p53 funksie tot weerstandigheid teen chemoterapeutiese middels en bestraling. Die resultate van hierdie studie toon dat die p53-onaktiewe sellyne egter die sensitiefste is vir chemoterapeutiese middels, soos etoposied, vinblastien en estramustien, terwyl die p53 natuurlike-tipe sellyn, LNCaP, die meeste radiosensitief is. Ten spyte van die invloed van p53 afbraak deur die HPV -16 E6 virale proteïen, dui die resultate van chemosensitiwiteit op die moontlikheid dat verskillende chemoterapeutiese middels verskillende p53-afhanklike effekte op verskillende tumorselle mag hê. Dit is bewys dat onttrekking van androgeen prostaat kankerselle sensitiseer teen chemoterapeutiese middels en dat hormoon-onafhanklike sellyne die hoogste chemosensitiwiteit vertoon. Die LNCaP sellyn vertoon 'n verhoogde weerstandigheid teen apoptose wat deur etoposied en y-bestraling geïnduseer is, wat 'n aanduiding is dat androgene beskerming kan bied teen beide hierdie DNA beskadigingsfaktore. Die belangrikste faktore wat die radiosensitiwiteit in menslike tumorselle bepaal, IS bekend dat dit die dubbelbande van DNA verbreek en herstel. Hierdie studie het aangetoon dat in prostaat sellyne die sellulêre radiosensitiwiteit korreleer met die aantal DNA dubbelband verbrekings binne 2 uur na bestraling, en dat die meer radioweerstandige sellyne beter herstelvermoë vertoon. Gevolgtrekkings oor die invloed van androgeen se afhanklikheid van radiosensitiwiteit en herstel kan egter nie op hierdie stadium gemaak word nie, aangesien slegs die LNCaP sellyn androgeenafhanklik was. Die feit dat die 2 uur herstelperiode 'n skeiding kan maak tussen radiosensitiewe en radioweerstandige selle in twee groepe menslike tumor sellyne, onderstreep die rol van herstel van nie-homoloë endverbindings. Dit hou implikasies in vir terapie, en stem ooreen met die kliniese waarnemings dat prostaat tumore suksesvol gekontroleer kan word deur lae intensiteit dosis bragiterapie. Ten einde die rol van apoptose te ondersoek, is selle blootgestel aan TD50 konsentrasies chemoterapeutiese middels, asook 60Co y-bestraling. Apoptose was oor die algemeen laag, en het gestrek van 0.1% tot 12.1%,3.0% tot 6.0% en 0.1% tot 8.5% vir etoposied, estramustien en vinblastien onderskeidelik. Die persentasie selle wat middel geïnduseerde apoptose ondergaan het, was gemiddeld hoër in tumor sellyne as in normale sellyne. Die waardes van apoptose geïnduseer deur y-bestraling het gewissel van 1.3% tot 7.0%. Die LNCaP sellyn het die laagste persentasie apoptotiese selle na bestraling gelewer, terwyl die 1532 r sellyn die hoogste persentasie gelewer het. Die volgorde van die radiosensitiwiteit van die sellyne was nie waarneembaar in hulle geneigdheid tot apoptose nie. Immunoblots het aangetoon dat die apoptose-geassosieerde proteïene, bax en bcl-2, uitgeskei word teen 'n basisvlak in al die sellyne wat getoets is, maar dat geen verhoogde uitskeiding waarneembaar was na blootstelling aan TD50 dosisse etoposied, vinblastien en estramustien nie. Die verhouding van bax en bcl-2 is ook nie beïnvloed deur DNA beskadiging nie. Dit blyk daarom dus onwaarskynlik dat daar 'n korrelasie bestaan tussen reproduktiewe seldood en die uitskeiding van gene wat apoptose beheer. Die resultate dui daarop dat apoptose me 'n belangrike meganisme vir middel- of bestralingsgeïnduseerde seldood in prostaat sellyne is nie.