Browsing by Subject "aneuploidy"

Now showing 1 - 4 of 4
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    Advanced Maternal Age and the Risk of Major Congenital Anomalies
    (Thieme, 2017-02) Goetzinger, Katherine R.; Shanks, Anthony L.; Odibo, Anthony O.; Macones, George A.; Cahill, Alison G.; Department of Obstetrics and Gynecology, IU School of Medicine
    Objective This study aims to determine if advanced maternal age (AMA) is a risk factor for major congenital anomalies, in the absence of aneuploidy. Study Design Retrospective cohort study of all patients with a singleton gestation presenting for second trimester anatomic survey over a 19-year study period. Aneuploid fetuses were excluded. Study groups were defined by maternal age ≤ 34 and ≥ 35 years. The primary outcome was the presence of one or more major anomalies diagnosed at the second trimester ultrasound. Univariable and multivariable logistic regression analyses were used to estimate the risk of major anomalies in AMA patients. Results Of 76,156 euploid fetuses, 2.4% (n = 1,804) were diagnosed with a major anomaly. There was a significant decrease in the incidence of major fetal anomalies with increasing maternal age until the threshold of age 35 (p < 0.001). Being AMA was significantly associated with an overall decreased risk for major fetal anomalies (adjusted odds ratio: 0.59, 95% confidence interval: 0.52–0.66). The subgroup analysis demonstrated similar results for women ≥ 40 years of age. Conclusion AMA is associated with an overall decreased risk for major anomalies. These findings may suggest that the “all or nothing” phenomenon plays a more robust role in embryonic development with advancing oocyte age, with anatomically normal fetuses being more likely to survive.
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    The Fanconi anemia signaling network regulates the mitotic spindle assembly checkpoint
    (2014) Enzor, Rikki S.; Clapp, D. Wade; Broxmeyer, Hal E.; Haneline, Laura S.; Srour, Edward F.
    Fanconi anemia (FA) is a heterogenous genetic syndrome characterized by progressive bone marrow failure, aneuploidy, and cancer predisposition. It is incompletely understood why FA-deficient cells develop gross aneuploidy leading to cancer. Since the mitotic spindle assembly checkpoint (SAC) prevents aneuploidy by ensuring proper chromosome segregation during mitosis, we hypothesized that the FA signaling network regulates the mitotic SAC. A genome-wide RNAi screen and studies in primary cells were performed to systematically evaluate SAC activity in FA-deficient cells. In these experiments, taxol was used to activate the mitotic SAC. Following taxol challenge, negative control siRNA-transfected cells appropriately arrested at the SAC. However, knockdown of fourteen FA gene products resulted in a weakened SAC, evidenced by increased formation of multinucleated, aneuploid cells. The screen was independently validated utilizing primary fibroblasts from patients with characterized mutations in twelve different FA genes. When treated with taxol, fibroblasts from healthy controls arrested at the mitotic SAC, while all FA patient fibroblasts tested exhibited weakened SAC activity, evidenced by increased multinucleated cells. Rescue of the SAC was achieved in FANCA patient fibroblasts by genetic correction. Importantly, SAC activity of FANCA was confirmed in primary CD34+ hematopoietic cells. Furthermore, analysis of untreated primary fibroblasts from FA patients revealed micronuclei and multinuclei, reflecting abnormal chromosome segregation. Next, microscopy-based studies revealed that many FA proteins localize to the mitotic spindle and centrosomes, and that disruption of the FA pathway results in supernumerary centrosomes, establishing a role for the FA signaling network in centrosome maintenance. A mass spectrometry-based screen quantifying the proteome and phospho-proteome was performed to identify candidates which may functionally interact with FANCA in the regulation of mitosis. Finally, video microscopy-based experiments were performed to further characterize the mitotic defects in FANCA-deficient cells, confirming weakened SAC activity in FANCA-deficient cells and revealing accelerated mitosis and abnormal spindle orientation in the absence of FANCA. These findings conclusively demonstrate that the FA signaling network regulates the mitotic SAC, providing a mechanistic explanation for the development of aneuploidy and cancer in FA patients. Thus, our study establishes a novel role for the FA signaling network as a guardian of genomic integrity.
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    MCAK Inhibitors Induce Aneuploidy in Triple-Negative Breast Cancer Models
    (MDPI, 2023-06-23) Smith, John C.; Husted, Stefan; Pilrose, Jay; Ems-McClung, Stephanie C.; Stout, Jane R.; Carpenter, Richard L.; Walczak, Claire E.; Biochemistry and Molecular Biology, School of Medicine
    Standard of care for triple-negative breast cancer (TNBC) involves the use of microtubule poisons such as paclitaxel, which are proposed to work by inducing lethal levels of aneuploidy in tumor cells. While these drugs are initially effective in treating cancer, dose-limiting peripheral neuropathies are common. Unfortunately, patients often relapse with drug-resistant tumors. Identifying agents against targets that limit aneuploidy may be a valuable approach for therapeutic development. One potential target is the microtubule depolymerizing kinesin, MCAK, which limits aneuploidy by regulating microtubule dynamics during mitosis. Using publicly available datasets, we found that MCAK is upregulated in triple-negative breast cancer and is associated with poorer prognoses. Knockdown of MCAK in tumor-derived cell lines caused a two- to five-fold reduction in the IC50 for paclitaxel, without affecting normal cells. Using FRET and image-based assays, we screened compounds from the ChemBridge 50 k library and discovered three putative MCAK inhibitors. These compounds reproduced the aneuploidy-inducing phenotype of MCAK loss, reduced clonogenic survival of TNBC cells regardless of taxane-resistance, and the most potent of the three, C4, sensitized TNBC cells to paclitaxel. Collectively, our work shows promise that MCAK may serve as both a biomarker of prognosis and as a therapeutic target.
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    P190B RhoGAP Regulates Chromosome Segregation in Cancer Cells
    (MDPI, 2012-04-25) Hwang, Melissa; Peddibhotla, Sirisha; McHenry, Peter; Chang, Peggy; Yochum, Zachary; Park, Ko Un; Sears, James Cooper; Vargo-Gogola, Tracy; Biochemistry and Molecular Biology, School of Medicine
    Rho GTPases are overexpressed and hyperactivated in many cancers, including breast cancer. Rho proteins, as well as their regulators and effectors, have been implicated in mitosis, and their altered expression promotes mitotic defects and aneuploidy. Previously, we demonstrated that p190B Rho GTPase activating protein (RhoGAP) deficiency inhibits ErbB2-induced mammary tumor formation in mice. Here we describe a novel role for p190B as a regulator of mitosis. We found that p190B localized to centrosomes during interphase and mitosis, and that it is differentially phosphorylated during mitosis. Knockdown of p190B expression in MCF-7 and Hela cells increased the incidence of aberrant microtubule-kinetochore attachments at metaphase, lagging chromosomes at anaphase, and micronucleation, all of which are indicative of aneuploidy. Cell cycle analysis of p190B deficient MCF-7 cells revealed a significant increase in apoptotic cells with a concomitant decrease in cells in G1 and S phase, suggesting that p190B deficient cells die at the G1 to S transition. Chemical inhibition of the Rac GTPase during mitosis reduced the incidence of lagging chromosomes in p190B knockdown cells to levels detected in control cells, suggesting that aberrant Rac activity in the absence of p190B promotes chromosome segregation defects. Taken together, these data suggest that p190B regulates chromosome segregation and apoptosis in cancer cells. We propose that disruption of mitosis may be one mechanism by which p190B deficiency inhibits tumorigenesis.