Abstract 3585: KIF11 silencing or inhibition induces chromosome instability

Abstract

Abstract Chromosome Instability (CIN) is defined as an increase in the rate at which whole chromosomes or large parts are gained or lost. CIN is not only associated with virtually all tumor types, but it is associated with aggressive tumors, the acquisition of multi-drug resistance and consequently poor patient prognosis. Despite these associations, the genes and molecular defects that contribute to CIN are only poorly understood. Recently, we performed a high content screen that identified KIF11, a microtubule associated motor protein, as a candidate CIN gene. Here, we couple RNAi-based gene silencing with biochemistry and cell biology to show that diminished KIF11 expression and/or function induce CIN. HCT116 cells were employed, as they are a karyotypically stable colorectal cancer cell line of epithelial origin that has been used for similar CIN studies. KIF11 was either silenced (both individual and pooled siRNA duplexes) or inhibited (Monostrol) and expression levels were determined by Western blots. To determine whether KIF11 silencing or inhibition affects DNA content, two phenotypes frequently associated with CIN, namely increases in nuclear area and micronucleus formation were evaluated. Fluorescence microscopy was employed on DAPI-counterstained samples and revealed statistically significant increases both nuclear area and micronucleus formation following KIF11 silencing and inhibition relative to controls. Next, flow cytometry was performed on propidium iodide labeled samples to assess whether increases in DNA content were associated with the changes in nuclear area. As predicted, increases in the proportion of cells with >G2/M DNA content occurred within the KIF11 silenced populations. Finally, mitotic chromosome spreads were generated and chromosomes were manually enumerated from 100 spreads per condition/control. Subsequent Kolmogorov-Smirnov tests identified statistically significant increases in the cumulative distribution frequencies of mitotic chromosome numbers within the spreads generated from the KIF11 silenced cells relative to controls. To extend our findings beyond the colorectal cancer cell context employed above, analogous studies were performed in hTERT cells (karyotypically stable fibroblast cell line) with very similar results. Collectively, these data indicate that KIF11 expression and function are normally required to maintain genome integrity. They further suggest that the loss of KIF11 expression and/or function may be a contributing factor in the etiology of tumorigenesis in colorectal cancer and perhaps other tumor types as well. Citation Format: Yasamin Asbaghi, Zelda Lichtensztejn, Laura Thompson, Kirk McManus. KIF11 silencing or inhibition induces chromosome instability. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 3585.