Hoffelder, Diane R. (2002) THE CONSEQUENCES OF MITOTIC SEGREGATION DEFECTS IN ORAL CANCER CELLS AND THEIR CONTRIBUTION TO CHROMOSOMAL INSTABILITY. Master's Thesis, University of Pittsburgh.
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| Video (QuickTime) (Movie 2: Anaphase bridge 1) - Supplemental Material Download (20Mb) | |
| Video (QuickTime) (Movie 3: Anaphase bridge 2) - Supplemental Material Download (13Mb) | |
| Video (QuickTime) (Movie 4: Multipolar spindle) - Supplemental Material Download (8Mb) | |
| Video (QuickTime) (Movie 5: Daughter cells with defective division) - Supplemental Material Download (2723Kb) | |
| Video (QuickTime) (Movie 6: Anaphase bridge leading to formation of a micronucleus) - Supplemental Material Download (9Mb) | |
| Video (QuickTime) (Movie 7: Anaphase bridge and micronucleus) - Supplemental Material Download (2763Kb) | |
| Video (QuickTime) (Movie 8: Micronucleus movement) - Supplemental Material Download (6Mb) | |
| Video (QuickTime) (Movie 9: Montage of micronucleus movement) - Supplemental Material Download (14Mb) |
Abstract
Mitotic segregation defects such as multipolar spindles, anaphase bridges, and micronuclei have long been observed in cancer cells, but it is not known whether these defects lead to aneuploidy or even contribute to tumorigenesis. We visualize living oral squamous carcinoma cells with stable expression of GFP-histone H2B fusion. Expression of this fusion protein labels chromosomes clearly and does not disrupt the cell cycle, alter the doubling time or produce any defects previously unseen in fixed cells. These carcinoma cells survive the formation of anaphase bridges and micronuclei and complete a second cell division in the same amount of time as unaffected cells. Micronuclei were formed after every division that contained an anaphase bridge in cells we examined. Most often, each daughter cell contained a micronucleus. These results suggest that the chromosome breaks at multiple points along its length and breaking may not be due to a "tug of war" between spindle poles. The movement of micronuclei was very dynamic compared to the nuclei during interphase and micronuclei do not appear to be transcriptionally active. Using long-term live cell imaging we were also able to observe the fate of these cells through two divisions and have determined the length of each phase of mitosis. Anaphase bridges and lagging metaphase chromosomes both lengthen mitosis, suggesting that the mitotic spindle checkpoints are at least partially active in cells. The mitotic delays occurred during metaphase in these defective cells. We have also analyzed centrosomal components including the mitotic apparatus protein, NUMA. No correlations were found between protein expression of NuMA and gene amplification or segregation defects. In summary, we have shown that cells continue to proliferate after the occurrence of mitotic defects and these defects contribute to chromosomal instability.
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| Item Type: | University of Pittsburgh ETD | |||||||||||||||
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| Title: | THE CONSEQUENCES OF MITOTIC SEGREGATION DEFECTS IN ORAL CANCER CELLS AND THEIR CONTRIBUTION TO CHROMOSOMAL INSTABILITY | |||||||||||||||
| Status: | Unpublished | |||||||||||||||
| Abstract: | Mitotic segregation defects such as multipolar spindles, anaphase bridges, and micronuclei have long been observed in cancer cells, but it is not known whether these defects lead to aneuploidy or even contribute to tumorigenesis. We visualize living oral squamous carcinoma cells with stable expression of GFP-histone H2B fusion. Expression of this fusion protein labels chromosomes clearly and does not disrupt the cell cycle, alter the doubling time or produce any defects previously unseen in fixed cells. These carcinoma cells survive the formation of anaphase bridges and micronuclei and complete a second cell division in the same amount of time as unaffected cells. Micronuclei were formed after every division that contained an anaphase bridge in cells we examined. Most often, each daughter cell contained a micronucleus. These results suggest that the chromosome breaks at multiple points along its length and breaking may not be due to a "tug of war" between spindle poles. The movement of micronuclei was very dynamic compared to the nuclei during interphase and micronuclei do not appear to be transcriptionally active. Using long-term live cell imaging we were also able to observe the fate of these cells through two divisions and have determined the length of each phase of mitosis. Anaphase bridges and lagging metaphase chromosomes both lengthen mitosis, suggesting that the mitotic spindle checkpoints are at least partially active in cells. The mitotic delays occurred during metaphase in these defective cells. We have also analyzed centrosomal components including the mitotic apparatus protein, NUMA. No correlations were found between protein expression of NuMA and gene amplification or segregation defects. In summary, we have shown that cells continue to proliferate after the occurrence of mitotic defects and these defects contribute to chromosomal instability. | |||||||||||||||
| Date: | 16 July 2002 | |||||||||||||||
| Date Type: | Completion | |||||||||||||||
| Defense Date: | 30 April 2002 | |||||||||||||||
| Approval Date: | 16 July 2002 | |||||||||||||||
| Submission Date: | 07 May 2002 | |||||||||||||||
| Release Date: | 16 July 2002 | |||||||||||||||
| Access Restriction: | No restriction; Release the ETD for access worldwide immediately. | |||||||||||||||
| Patent pending: | No | |||||||||||||||
| Institution: | University of Pittsburgh | |||||||||||||||
| Thesis Type: | Master's Thesis | |||||||||||||||
| Refereed: | Yes | |||||||||||||||
| Degree: | MS - Master of Science | |||||||||||||||
| URN: | etd-05072002-121540 | |||||||||||||||
| Uncontrolled Keywords: | anaphase bridge; GFP histone; mitosis; oral cancer; segregational defects | |||||||||||||||
| Schools and Programs: | Dietrich School of Arts and Sciences > Biological Sciences | |||||||||||||||
| Date Deposited: | 10 Nov 2011 14:43 | |||||||||||||||
| Last Modified: | 02 Feb 2013 01:16 | |||||||||||||||
| Other ID: | http://etd.library.pitt.edu:80/ETD/available/etd-05072002-121540/, etd-05072002-121540 | |||||||||||||||
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