This work is focussed on the analysis of breast tumour physiology by pharmacokinetic modelling of dynamic contrast enhanced MRI (DCE-MRI) data. DCEMRI consists of the intravenous bolus injection of a small molecular weight contrast agent into the patient followed by the rapid acquisition of MR images across both breasts. Due to the leaky nature of the lesion microvasculature there is a greater uptake of contrast agent within the tumour than in the surrounding tissues. The dynamic contrast enhanced MR signal curve can be fitted by compartmental analysis providing information linked to the tumour’s permeability and flow. The effect of the DCE-MRI acquisition parameters on the accuracy of the estimated pharmacokinetic quantities was investigated together with the assumptions lying behind the pharmacokinetic model used for the fitting. Contrast enhanced MRI data were also examined using a fractal measure of tumour heterogeneity with the aim of assessing whether this could be a potential predictor of the tumour response to chemotherapy. Among the factors believed to play an important role in terms of tumour treatment is an increased interstitial fluid pressure (IFP) in the central areas of some large tumours. Here DCE-MRI data were analyzed in a way to see whether it could provide any information related to IFP distribution across tumour volumes. Finally, when performing quantitative DCE-MRI, particular care needs to be taken in the choice of an arterial input function (AIF) which accurately describes the passage of the contrast agent bolus at the lesion location. Here a new approach was proposed and demonstrated for the estimation of a tumour capillary input function together with lesion pharmacokinetic parameters. This was achieved by optimizing the capillary input function with a measure of the patient’s cardiac output, a parameter which is expected to vary depending on the patient’s pathology/physiology.

Thesis (M.Sc.(Biochemistry)) -- University of Limpopo, 2019. / Retinoblastoma binding protein 6 (RBBP6) is the protein encoded by the Retinoblastoma Binding Protein 6 (RBBP6) gene that is located in chromosome 16p12.2. There is a growing list of newly discovered RBBP6 hypothetical splice variants but there are only three RBBP6 splice variants that are well documented. RBBP6 has been previously implicated in the regulation of cell cycle and apoptosis but little is known about the expression and regulation of the human RBBP6 splice variants during cell cycle progression and breast cancer development. This study was aimed at determining the expression pattern of RBBP6 alternatively spliced variants during arsenic trioxide-induced cell cycle arrest and apoptosis in breast cancer MCF-7 cells. It was also aimed at determining RBBP6 specific microRNAs and how they are regulated in MCF-7 breast cancer cells. MCF-7 cells were maintained and subjected to arsenic trioxide-induced cell cycle arrest and apoptosis. The MTT (3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide) and the Muse™ Count & Viability assays were used to evaluate the effect of arsenic trioxide on the viability of MCF-7 cells. Cell cycle arrest using 11 μM arsenic trioxide and apoptosis using 32 μM arsenic trioxide were analysed using the MUSE® Cell Analyzer, light and fluorescence microscopy. Arsenic triode-induced apoptosis was analysed using the Muse™ Annexin V & Dead Cell Kit, MultiCaspase and MitoPotential assays using the Muse™ MultiCaspase Kit and Muse™ MitoPotential Kit. Arsenic trioxide-induced cell cycle arrest was analysed using the Muse™ Cell Cycle Kit. Semi-quantitative analysis of RBBP6 variants was carried out using the conventional Polymerase Chain Reaction (PCR), while the quantitative analysis was done using the Real-Time Quantitative PCR. The localization of RBBP6 isoforms was done using Immunocytochemistry (ICC). Web based Bioinformatics tools were used to identify RBBP6-specific microRNAs. The MTT results showed that arsenic trioxide decreased the viability of the MCF-7 cells in a dose-dependent manner. The Muse™ Cell Cycle analysis showed that 11 μM of arsenic trioxide induced G2/M cell cycle arrest in MCF-7 cells, while the Muse™ Annexin V & Dead Cell assay showed that 32 μM of arsenic trioxide induced the extrinsic apoptotic pathway in MCF-7 breast cancer cells. Using the conventional PCR, the MCF-7 cells were found to express the RBBP6 variant 1 transcript but lacks the expression of variant 2 and 3 transcripts, contrary to the kidney embryonic Hek 293 cells that exhibited the expression of RBBP6 variant 1, 2 and 3. Additionally, arsenic trioxide downregulated RBBP6 variant 1 in breast cancer cells during cell cycle arrest and apoptosis. The Real-Time PCR confirmed that MCF-7 cells lowly express RBBP6 variant 3. On the other hand, the ICC analysis showed that RBBP6 isoform 1 is localized and highly expressed in MCF-7 breast cancer cells. The Web based Bioinformatics tools showed that RBBP6 variant 1 specific microRNAs are down regulated in MCF-7 breast cancer cells. These results together showed that As2O3 is effective against MCF-7 cells and also regulated the expression of RBBP6 variants, especially, variant 1. This study showed that there are RBBP6 variants that are involved in breast cancer progression and there are those that may be involved in breast cancer suppression. Targeting these RBBP6 variants for therapeutic development is a promising strategy. In conjunction with RBBP6 expression, arsenic trioxide should be further explored as a breast cancer drug.

Thesis (M.S.)--West Virginia University, 2005. / Title from document title page. Document formatted into pages; contains vii, 51 p. : ill. Includes abstract. Includes bibliographical references.

Genistein, daidzein, and resveratrol are polyphenolic plant compounds called phytoestrogens (PEs) because they are capable of binding and activating estrogen receptor (ER) isoforms due to structural similarity to estrogen (E2). The central hypothesis governing these investigations is that PEs can bind to plasmamembrane ERs, cross-talk with epidermal growth factor receptor (EGFR), and signal downstream to an array of molecular pathways including those involved in cell motility. This is relevant to breast cancer metastasis as PEs have been shown to have both preventative and promotional effects on breast cancer cells. The data herein investigates the role of E2, genistein, daidzein, and resveratrol in cell migration, actin cytoskeleton organization, focal adhesion assembly, as well as EGFR, focal adhesion kinase (FAK), and Rho family GTPase activation in ER (+/-) human breast cancer cells. We report that E2 and EGF increase cell migration, induce Rac-dependent lamellipodia formation, increase focal adhesion assembly, and increase EGFR, FAK, and Rac activity in ER[beta] (+) cells. We report that genistein and daidzein also increase cell migration, Rac-dependent lamellipodia formation, focal adhesion assembly, and FAK activity in ER[beta] (+) cells. Resveratrol demonstrates a biphasic concentration-dependent effect on the same signaling pathways. Resveratrol at 5 [micromolar] increases cell migration, lamellipodia formation, and increases FAK and Rac activity in ER[beta] (+) cells similar to E2. Conversely, resveratrol at 50 [micromolar] inhibits cell migration/invasion, blocks E2/EGFinduced migration, induces sustained and unpolarized filopodia, decreases focal adhesion assembly, increases EGFR activity, and decreases FAK, Cdc42, and Rac activity in ER[beta] (+) cells. The induction of filopodia by 50 [micromolar] resveratrol is partially Rho GTPaseindependent and can be observed in serum and on extracellular matrices. The induction by 50 [micromolar] resveratrol of a global, sustained extension of filopodia in conjunction with inhibition of focal adhesion assembly, as well as FAK, Cdc42, and Rac activity is hypothesized to negatively affect breast cancer cell motility. Ultimately, the elucidation of these cell structures and signaling mechanisms in response to PEs will help to determine a preventive or promotional role for plant compound-based therapies in breast cancer metastasis. / text

3T MRI provides higher signal-to-noise ratio images compared to lower field machines. However, a major drawback of 3T MRI is a higher B1 transmission-field inhomogeneity across the field-of-view compared to imaging at lower fields. B1-field mapping was performed on volunteers using a Philips 3.0T MR scanner and a typical head-first prone patient positioning technique. The B1-field transmitted in the breasts was found to be reduced towards the right side of the body. In some volunteers, the B1-field was reduced to about one-half of the nominal field in the right breast. To minimize the B1 inhomogeneity artefacts, a saturation recovery snapshot FLASH (SRSF) imaging sequence was proposed. Different saturation techniques were assessed. The best saturation efficiency was produced by Hoffmann’s saturation method. By using Hoffmann’s SRSF sequence, the error in the enhancement ratio (ER) can be reduced to about one half compared to imaging obtained using typical FLASH sequence in the presence of a 50% B1-field reduction. Other techniques i.e. bilateral power optimization and a dedicated patient support system were also tested. Both of these approaches produced substantial reductions of the B1 inhomogeneity seen with the standard technique. To address the effects of the native T1 (T10) of different tissues on DCE-MRI, novel enhancement factor indices calculated using SRSF sequence images were introduced and assessed. Computer simulations and gel phantom experiments showed that less error was observed in the indices calculated compared to the ER calculated using the conventional and widely used FLASH sequence. Furthermore, the effect of B1-field inhomogeneity on the novel indices is also reduced. One of the indices proposed is directly related to the contrast agent concentration. The theory and results presented show that the SRSF pulse sequence and the quantification techniques proposed have the potential to improve the accuracy of breast DCE-MRI at 3T.

Thesis (M.S.)--University of Texas Health Science Center at Houston, School of Public Health, 2008. / Source: Masters Abstracts International, Volume: 46-05, page: 2719. Adviser: Asha Kapadia. Includes bibliographical references.

Magister Scientiae (Medical Bioscience) - MSc(MBS) / There is increasing concern worldwide by researchers with regards to the assessing of safety and therapeutic consumption of the plants used in traditional medicine. Date palm pollen (DPP) and flax seed have been used traditionally to improve fertility in Libya. DPP extracts have shown several reproductive beneficial effects. In vivo, studies have revealed the ability of DPP to increase sperm concentrations, ameliorate the testicular toxicity induced by cadmium and lead, raise testosterone, as well as LH and FSH hormone levels. Flax seed phytochemical analysis showed lots of valuable components such as lignans and α linolenic acid to which were attributed its positive health effects like antitumor, antioxidant and protective effects against coronary heart diseases. Moreover, flax lignans have both estrogenic and antiestrogenic potential. This study was aimed at testing the effects of Libyan DPP and flax seed on the Sertoli (TM4) cell line and human breast adenocarcinoma (MCF - 7) cell line. Different concentrations (0.01, 0.1, 1, 10, 100 and 1000 μg/ml) of ethanolic extracts of DPP and flax seed, respectively, were used to assess the morphology of TM4 and MCF - 7 cells after 24 and 72 hours exposure. Mitochondrial dehydrogenase activity as a marker of cell viability was measured by MTT assay after 24 and 72 hours exposure. Apoptotic effects were assessed by flow cytometeric APO percentage assay. TM4 cell production of Inhibin - B hormone and GGT enzyme activity under the effects of DPP or flax seed was determined by use of ELISA kits. Transepithelial electrical resistance (TEER) assay were used to detect the effect of DPP or flax seed on TM4 cell monolayer integrity. Finally the plants potential phytoestrogenic activity was determined by use of E - SCREEN assay in MCF – 7 breast cancer cells. Higher concentrations of DPP significantly increased the activity of mitochondrial dehydrogenase enzyme of TM4 cells after 24 hours associated with increasing cell number as detected in a microphotograph. Flax seed concentrations less than 100 μg/ml reduced TM4 cell viability but there were no morphological changes visible after 24 hours. MCF - 7 cells viability was reduced after 24 and 72 hours treatment with DPP and flax seed. DPP concentrations beyond 1 μg/ml significantly raised the TEER of TM4 monolayer over 72 hours while flax seed treatments caused a significant increase only after 72 hours of exposure. TM4 cells GGT activity increased significantly after exposure to higher concentrations of DPP and all flax seed concentrations. Significant stimulatory effects of all the concentrations of DPP or flax seed on TM4 inhibin - B hormone productions have been detected. Apoptotic studies showed no significant changes. E - SCREEN assay resulted in significant reduction in MCF - 7 proliferation rate under the effect of low concentrations of DPP or flax seed. Higher concentrations of the plant extracts, however, stated to increase MCF – 7 cell proliferation, this exerts weak estrogenic activities. In conclusion, the main finding of this study is that DPP and flax seed showed stimulatory effects on TM4 cells proliferation. The resistivity of TM4 cells monolayer which reflect the integrity of blood – testis barrier (BTB) was also significantly increased as well as inhibin - B production and GGT enzyme activity. In addition DPP and flax seed respectively showed inhibitory effects on MCF - 7 cells viability. This study indicated that DPP or flax seed may enhance spermatogenesis through their stimulatory action on Sertoli cells. Moreover, both plants could reduce breast cancer cells viability. However, further investigations are required to elucidate the exact mechanisms behind these obtained findings.

Resistance to chemotherapeutics is a widespread phenomenon in cancer cells that may counteract the successful therapy of many patients. In resistant cells, higher level of ABC transporters, among others, often can be detected. This high level of ABC transporters represents a suspected mechanism of acquired cancer resistance. We studied the molecular mechanism of resistance to taxanes in cancer cells using SK-BR-3 and MCF-7 breast cancer cell lines. We analyzed the effect of paclitaxel on apoptosis induction in the originally sensitive cells of these lines as compared to their counterpart resistant cells, developed by gradual adaptation to paclitaxel. In resistant cells of the SK-BR-3 and MCF-7 lines, we did not detected ongoing induction of apoptosis but we did detect significantly increased expression of ABCB1 transporter after paclitaxel application. By silencing the expression of the transport via employment of small interfering RNA (siRNA), we tested the role of the ABCB1 transporter in cells resistant to paclitaxel. We found that resistant cells with silenced expression of the ABCB1 transporter had a statistically significant increase of sensitivity to paclitaxel as compared to control resistant cells with high expression of this transporter. Along with increased sensitivity, we demonstrated...

Thesis (M.Sc.)--Memorial University of Newfoundland, Faculty of Medicine, 2000. / Typescript. Bibliography: leaves 92-100.

Previous studies have shown that the upregulation of CD151 and β1 is associated with poor prognosis in many cancers such as breast cancer. Studies have provided evidence that these proteins are associated with the adhesion and migration of tumor cells. In this study, a microfluidic flow chamber was utilized to determine how CD151 and β1 affected the firm and initial adhesion of metastatic breast cancer cells to a planar endothelial monolayer under shear stress. This system mimicked the adhesion of metastatic breast cancer cells to the endothelial cells of the circulatory system. CD151 and β1 increased the firm adhesion of metastatic breast cancer cells onto an endothelial monolayer when subjected to high shear stresses. CD151 and β1 increased the initial adhesion of metastatic breast cancer cells onto an endothelial monolayer. A transwell assay was utilized to determine how CD151 and β1 affected random migration through different matrixes and random transendothelial migration. CD151 and β1 decreased the random migration of metastatic breast cancer cells through matrices. Additionally, background information is provided related to the metastatic cascade, how it can be modeled with microfluidics, and how CD151 and β1 have been known to effect cancer and metastasis.