Centromeres and Ovarian Cancer

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The composition, organization, and function of centromeric DNA remain one of the last frontiers of genomics. This proposal “Centromeres and Ovarian Cancer” will investigate the role centromere DNA sequences play in the correct function of centromeres and chromosome segregation in ovarian cancer, and its contribution to ovarian cancer progression. The centromere is the functional unit responsible for the faithful segregation of chromosomes. Failure to properly partition chromosomes to daughter cells results in genome instability and aneuploidy (gain or loss of chromosomes), a hallmark of cancers. Functional centromere structures are made of centromere epigenetic marks that bind to the underlying DNA sequence. During cell division, the microtubules interact with these centromeric structures and pull chromosomes apart. Although centromere identity and function rely on epigenetic mechanisms, recent studies suggest that centromere sequences have functional roles as well. However, human centromere sequences have not been assembled into linear contigs due to their high content of repetitive DNA, and thus, the precise composition, organization, and function of centromeric DNA remain to be elucidated. We will investigate the role centromere DNA sequences play in centromere function and chromosome segregation in ovarian cancer. To overcome the virtual absence of centromere sequence in the Human Genome Project, the P.I. has devised rapid, quantitative PCR- based methods and innovative Next Generation Sequencing tools to study specifically the centromeric DNA elements of each human chromosome at the molecular level. Using these pioneering technologies, we discovered that the genomes of ovarian cancer cells exhibit severe loss of centromere sequences in specific chromosomes, in particular chromosome 17, when compared to healthy matched-tissue. We hypothesize that these specific centromere mutations play a key role in centromere formation and function, and lead to chromosome 17 missegregation and genome instability seen in ovarian cancer. The proposed research will use mutant ovarian and fallopian tube cell lines with centromere deletions generated using CRISPR Cas9. We will investigate whether centromere loss alters the ability of centromeric epigenetic marks to form centromere/kinetochore structures. We will address whether loss of centromeric material in these mutant cells affects genome stability, chromosome segregation and transformation. This information will begin to provide a better understanding of the role’s centromere sequences play in cell division and cancer genetics. These studies will enhance our knowledge of centromeres and chromosomal biology and could potentially result in novel methodologies to study genetic defects in cancers.