University of Khartoum

Tumor Metabolism and Cancer Chemotherapy Resistance

Tumor Metabolism and Cancer Chemotherapy Resistance

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Title: Tumor Metabolism and Cancer Chemotherapy Resistance
Author: Alfarouk, Khalid Omer
Abstract: Background Cancer is a cell or group of cells that proliferate and interact with each other and with their surroundings microenvironment in a pattern completely different from that of normal cells, which threats human survival. It is widely assumed that chemotherapy can eliminate these cells in order to increase patients' survival. However, soon, those cells begin to resist the chemotherapy as a result of their genetic and environmental variability. Compared to the environmental resistance, evolutionary resistance is more costly in terms of energy consumption and synthesis of either new or upregulate the already existed proteins, which negatively affect the rate of division. We aimed to study the biological screening of both resistant and sensitive cell lines, in order to measure and compare their metabolic rates and selection of suitable agents that alter their metabolism and so will stop or delay the evolution of resistance. We also aimed taking biopsy from patients and studying the diversity of those tumor cells that reside within the tumor microenvironment. We also aimed to examine the impact of the tumor environment in production of a heterogeneous population and possible heritable variations. This study may offer new treatment modality to evade cancer chemotherapy resistance. Material and Methods This study used digital pathology whole slide image acquisition and advanced image analysis algorithms. We examined the spatial distribution of ER + and ER- cells, vascular density, vessel area, and tissue necrosis within histological sections of 24 breast cancer specimens. These data were correlated with the patients ER status and molecular pathology report findings. Preparation of MCF-7 Wt (sensitive cell line) and Dox. (expressing P-gp) Pellets: Cells were fixed in formalin, then stirred into suspension using liquefied Histogel (from Thermo Scientific). The cells- liquid Histogel mix was dispensed into a mold for solidifying followed by chilling at 4°C until hardened. Cells were then removed from the mold and placed in labeled/marked tissue cassette and processed following standard histological techniques. Image Acquisition and Analysis: Cell pellet slides stained against each biomarker were scanned using the Aperio™ (Vista, CA) ScanScope XT with a 200x/0.75NA lens. Immunopositivity of each biomarker was quantitatively scored using commercial algorithms from the Positive Pixel Count v9 Aperio Toolbox®. The staining intensity for strong (3+), moderate (2+), weak (1+) and negative (0) pixels were thresholded by the 0-255 8bit dynamic range value (220; 175; 100; respectively). Measurement of Metabolism: Oxygen consumption and acid production (as a surrogate for glycolysis) was measured using the Seahorse XF96 analyzer. This instrument can measure the metabolism of living cells in real-time. Oxidative capacity was measured by detecting oxygen consumption after treating cells with Rotenone and Antimycin followed by FCCP. Glycolytic capacity was measured by detecting proton production after treating cells with glucose followed by Oligomycin A treatment. Results Our data showed that resistant cell linesoverexpress: Carbonic anhydrase IX (CA9) and Carbonic anhydrase-XII (CA12) which contributed to tumor invasiveness and cellular migration. MMP7 played a crucial role in cellular migration. LC3 correlate with cellular invasiveness. P-gpwas associated with Epithelial-Mesenchymal Transition (EMT) and hence increased metastatic potential. ANOVA analyses revealed a close correlation between vascular area and ER expression and between high fractional necrosis and absent ER expression (R2 = 39%; p < 0.003 and R2 = 46%; p < 0.001), respectively). ER expression did not correlate with tumor grade or size. Conclusion We provided evidence that resistant tumor cells are more metastatic. Therefore, administration of standard (conventional) chemotherapy may decrease survival of the patient by accelerating metastasis. We concluded that estrogen receptors (ER) expression can be understood as an evolutionary process and linked to variations in estrogen delivery by temporal and spatial heterogeneity in blood flow. This correlation suggests strategies to promote intratumoral blood flow. A cyclic introduction of estrogen in the treatment schedule could be explored as a counter-intuitive approach to increase the efficacy of anti-estrogen drugs.
URI: http://khartoumspace.uofk.edu/123456789/16979
Date: 2015-11-11


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