School of Science Division of Life Science 35 In Depth Characterization of Novel Cell Cycle Regulators in Cancer Cells Supervisor: POON Randy Yat Choi / LIFS Student: YIN Zekai / BIOT-AB Course: UROP 2100, Summer DCB (Dihydrocytochalasin B) is an actin inhibitor that prevents the polymerization of actin filaments, which are essential for forming the contractile ring during cytokinesis. This disruption prevents the cell from dividing properly into two daughter cells, resulting in the formation of binucleate cells. In this study, I investigated whether the cell cycle of human retinal pigment epithelial-1 (RPE-1) cells lacking p53 is affected by DCB and determined the effective concentration of DCB required to induce binucleate cells. Different concentrations of DCB were tested using live-cell imaging analysis. My results indicated that DCB extends the cell cycle duration of the daughter cells derived from binucleate RPE-1 cells lacking p53. In Depth Characterization of Novel Cell Cycle Regulators in Cancer Cells Supervisor: POON Randy Yat Choi / LIFS Student: ZHUANG Boyi / BCB-IRE Course: UROP 1100, Fall This study explored the relationship between Superoxide Dismutase 2 (SOD2) depletion and cell death during mitotic arrest. SOD2 depletion, combined with nocodazole-induced mitotic arrest, led to accelerated cell death during mitotic arrest compared to SOD2-sufficient cell lines. N-acetylcysteine (NAC) as a ROS scavenger led to decelerated cell death in sufficient SOD2 cells but had no significant effect on SOD2 cells. Caspase inhibitor z-VAD-FMK decelerates cell death but still significantly accelerates cell death in SOD2depleted cells. Combined with discovering distinct cell death morphology in LCI under z-VAD-FMK, added cells suggest that different cell death pathways may be involved in SOD2 depletion-induced cell death during mitotic arrest. The initial hypothesis is the involvement of ferroptosis, which is still under investigation. Targeting Mitotic Regulators in Cancer Cells for Potential Treatment Supervisor: POON Randy Yat Choi / LIFS Student: LAI Haocheng / BCB Course: UROP 3100, Fall Multipolar division often leads to chromosome segregation errors and genomic instability, which is an important characteristic of cancer cell formation. The arrangement and quantity of centrosomes are one of the important factors affecting the cell division mode - bipolar or multipolar division. In binuclear cells, due to the abnormal number of centrosomes, the spatial arrangement of centrosomes becomes the decisive factor determining the type of cell division. Therefore, inducing different types of cells into binucleated cells and observing the centrosome distribution pattern of these binucleated cells in the Metaphase can infer the division pattern tendency of this cell during binucleation, and thus determine the genomic stability of this cell. This experiment will first use DCB to induce the production of RPE1-p53knock and H1299 binuclear cells. Then, G2 synchronization and metaphase arrest will be performed using RO3306 and MG132, and the mitotic patterns of binuclear cells will be observed using immunostaining to label chromosomes and centrosomes, to obtain their division pattern tendencies and compare their genomic stability. We will also review the experimental methods and propose potential improvement methods.
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