Deficiencies in Chfr and Mlh1 synergistically enhance tumor susceptibility in mice
Zheng Fu, Kevin Regan, Lizhi Zhang, Michael H. Muders, Stephen N. Thibodeau, Amy French, Yanhong Wu, Scott H. Kaufmann, Wilma L. Lingle, Junjie Chen, Donald J. Tindall
Zheng Fu, Kevin Regan, Lizhi Zhang, Michael H. Muders, Stephen N. Thibodeau, Amy French, Yanhong Wu, Scott H. Kaufmann, Wilma L. Lingle, Junjie Chen, Donald J. Tindall
View: Text | PDF
Research Article Oncology

Deficiencies in Chfr and Mlh1 synergistically enhance tumor susceptibility in mice

Abstract

Genetic instability, which leads to an accumulation of various genetic abnormalities, has been considered an essential component of the human neoplasic transformation process. However, the molecular basis of genomic instability during tumorigenesis remains incompletely understood. Growing evidence indicates that checkpoint with forkhead and ring finger domains (CHFR), a recently identified mitotic checkpoint protein, plays an important role in maintaining chromosome integrity and functions as a tumor suppressor. In this study, we used high-throughput technology to conduct gene expression profiling of human colon cancers and found that loss of CHFR expression frequently occurred in colon cancers with high microsatellite instability (MSI-H). Downregulation of CHFR expression was closely associated with overexpression of Aurora A, an important mitotic kinase. Mice with deficiencies in both Chfr and Mlh1 (the gene that encodes the DNA mismatch-repair protein Mlh1) displayed dramatically higher incidence of spontaneous tumors relative to mice deficient for only one of these genes. These results suggest that defects in both Chfr and Mlh1 synergistically increase predisposition to tumorigenesis.

Authors

Zheng Fu, Kevin Regan, Lizhi Zhang, Michael H. Muders, Stephen N. Thibodeau, Amy French, Yanhong Wu, Scott H. Kaufmann, Wilma L. Lingle, Junjie Chen, Donald J. Tindall

×

Figure 3

Deficiencies in both Chfr and Mlh1 increase spontaneous tumor incidence in mice.

Options: View larger image (or click on image) Download as PowerPoint
Deficiencies in both Chfr and Mlh1 increase spontaneous tumor incidence ...
(A) Western blot of cell lysates from MEFs with indicated genotypes was performed using anti-Chfr and anti-Mlh1 antibodies, respectively. Anti–β-actin was used as a loading control. (B) Kaplan-Meier survival curve of Chfr–/–Mlh1–/– (n = 32), Chfr–/–Mlh1+/– (n = 38), Chfr–/–Mlh1+/+ (n = 30), Chfr+/+Mlh1–/– (n = 33), Chfr+/+Mlh1+/– (n = 30), Chfr+/+Mlh1+/– (n = 30), and Chfr+/+Mlh1+/+ (n = 32) mice over a period of 24 months. *P < 0.0001, compared with Chfr+/+Mlh1+/+ mice; **P = 0.0002, compared with Chfr+/+Mlh1–/– mice, determined by log-rank test. (C) Tumors from Chfr–/–Mlh1–/– mice. We included examples of spontaneous lymphomas present in pancreas, liver, and spleen from the same Chfr–/–Mlh1–/– mouse and a spontaneous colon cancer from another Chfr–/–Mlh1–/– mouse as well as the H&E-stained sections from those tumors. Original magnification, ×400 (H&E-stained sections from liver, spleen, and pancreas); ×100 (left) and ×400 (right) (H&E-stained section from colon). N, normal; A, adenoma; T, adenocarcinoma. (D) CD4 and CD8 cell surface expression of cells from a representative spontaneous lymphoma was assessed by flow cytometry. Numbers in each quadrant indicate percentage of the total population. (E) Examination of Chfr expression in mouse lymphomas. RNA and protein from lymphomas with indicated genotypes were subjected to real-time RT-PCR (top panel) and Western blot (bottom panel), respectively. Thin lines in the bottom panel indicate that the samples were run on separate gels and the bands were spliced together at indicated positions. Results shown are mean ± SD. Experiment was performed independently 3 times. *P < 0.001, compared with Chfr+/+Mlh1+/– tumors and determined by ANOVA.