Endocrinol Metab.  2014 Dec;29(4):561-566. 10.3803/EnM.2014.29.4.561.

Partial Hepatectomy in Acetylation-Deficient BubR1 Mice Corroborates that Chromosome Missegregation Initiates Tumorigenesis

• Lee YK
• Park I
• Lee H

• KMID: 2384255
• DOI: http://doi.org/10.3803/EnM.2014.29.4.561

Abstract

BACKGROUND
Aneuploidy has been suggested as one of the major causes of cancer from the time of Boveri. In support of this notion, many studies have shown that cancer cells exhibit aneuploidy. However, there are evidences that do not support the aneuploidy hypothesis. We have previously reported that the spindle assembly checkpoint protein BubR1 is acetylated in mitosis and that the acetylation of BubR1 is crucial for checkpoint maintenance and chromosome-spindle attachment. Mice heterozygous for acetylation-deficient BubR1 (K243R/+) spontaneously develop cancer with chromosome instability. As K243R/+ mice develop hepatocellular carcinoma, we set out to test if chromosome mis-segregation was the cause of their liver cancer.
METHODS
Primary hepatocytes in the regenerating liver after partial hepatectomy (PH) were analyzed and compared for various mitotic parameters.
RESULTS
Primary hepatocytes isolated from K243R/+ mice after PH displayed a marked increase of chromosome misalignment, accompanied by an increase of micronuclei. In comparison, the number of nuclei per cell and the centrosome numbers were not different between wild-type and K243R/+ mice. Taken together, chromosome mis-segregation provokes tumorigenesis in mouse liver.
CONCLUSION
Our results corroborate that PH provides a reliable tool for assessing mitotic infidelity and cancer in mice.

Keyword

Partial hepatectomy; Neoplasms; Mitosis; Hepatocytes; Liver neoplasms; Aneuploidy

MeSH Terms

Acetylation
Aneuploidy
Animals
Carcinogenesis*
Carcinoma, Hepatocellular
Centrosome
Chromosomal Instability
Hepatectomy*
Hepatocytes
Hydrogen-Ion Concentration
Liver
Liver Neoplasms
M Phase Cell Cycle Checkpoints
Mice*
Mitosis

Figure

• 

  Fig. 1 (A) Proliferation capacity in regenerating hepatocytes measured by counting the mitotic cells (mitotic index) or Ki-67-positive cells (B) at the indicated time points after partial hepatectomy (PH). The values in the graph are the mean of three independent experiments (mean±SEM). (C) The regenerating liver sections were stained with H&E (upper panel) and an antibody directed against Ki-67 (lower panel). Mitotic cells are marked in the brackets. Scale bar, 50 µm.

• 

  Fig. 2 (A) Chromosome misalignments (left) and lagging chromosomes (right) in regenerating K243R/+ hepatocytes. Scale bar, 10 µm. (B) The incidence of congression defects and lagging chromosomes compared with that of wild type (independent-samples t test) are represented as bar graphs.

• 

  Fig. 3 Number of centrosomes in liver sections analyzed by anti-γ-tubulin, phalloidin, and diamidino-2-phenylindole immunostaining.

• 

  Fig. 4 (A) Comparison of the number of nuclei in the regenerating hepatocytes of WT and K243R/+ mice. The graph represents the analysis of hepatocytes from three of each WT and K243R/+ mice, subjected to partial hepatectomy (PH). The exact number of hepatocytes counted in each group is shown in the table. (B) Model showing how the PH experiment contributed to the understanding of the mouse hepatocellular carcinoma development with chromosome instability in K243R/+ mice.

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