Related Experiment Videos
The absence of Msh2 alters abelson virus pre-B-cell transformation by influencing p53 mutation
J Jenab-Wolcott1, D Rodriguez-Correa, A H Reitmair
1Departments of Pathology, Tufts University School of Medicine, Boston, Massachusetts 02111, USA.
Abstract:
Defects in DNA mismatch repair predispose cells to the development of several types of malignant disease. The absence of Msh2 or Mlh1, two key molecules that mediate mismatch repair in eukaryotic cells, increases the frequency of mutation and also alters the response of some cells to apoptosis and cell cycle arrest. To understand the way these changes contribute to cancer predisposition, we examined the effects of defective mismatch repair on the multistep process of pre-B-cell transformation by Abelson murine leukemia virus. In this model, primary transformants undergo a prolonged apoptotic crisis followed by the emergence of fully transformed cell lines. The latter event is correlated to a loss of function of the p53 tumor suppressor protein and down-modulation of the p53 regulatory protein p19Arf. Analyses of primary transformants from Msh2 null mice and their wild-type littermates revealed that both types of cells undergo crisis. However, primary transformants from Msh2 null animals recover with accelerated kinetics, a phenomenon that is strongly correlated to the appearance of cells that have lost p53 function. Analysis of the kinetics with which p53 function is lost revealed that this change provides the dominant stimulus for emergence from crisis. Therefore, the absence of mismatch repair alters the molecular mechanisms involved in transformation by affecting a gene that controls apoptosis and cell cycle progression, rather than by affecting these processes directly.
Insights
Defects in DNA mismatch repair, like Msh2 absence, accelerate cancer development by promoting p53 mutations. This DNA repair deficiency drives tumor formation more rapidly than direct effects on apoptosis or cell cycle arrest.
Area of Science:
- Molecular Biology
- Cancer Biology
- Genetics
Background:
- DNA mismatch repair (MMR) is crucial for genomic stability.
- Defects in MMR, such as Msh2 or Mlh1 absence, increase mutation rates and affect cell cycle control.
- MMR deficiency is linked to various cancers.
Purpose of the Study:
- To investigate how MMR defects influence cancer predisposition.
- To examine the role of MMR in the multistep transformation of pre-B cells induced by Abelson murine leukemia virus.
- To understand the molecular mechanisms underlying accelerated cancer development in MMR-deficient cells.
Main Methods:
- Utilized a pre-B cell transformation model using Abelson murine leukemia virus.
- Compared Msh2 null mice with wild-type littermates.
- Analyzed apoptotic crisis, cell cycle arrest, p53 tumor suppressor protein function, and p19Arf expression.
Main Results:
- Both Msh2 null and wild-type cells undergo apoptotic crisis during transformation.
- Msh2 null transformants recover from crisis with accelerated kinetics.
- Accelerated recovery in Msh2 null cells strongly correlates with the loss of p53 function, which emerges as the dominant stimulus for crisis resolution.
Conclusions:
- Absence of DNA mismatch repair accelerates cancer transformation by promoting p53 loss-of-function mutations.
- MMR deficiency impacts cancer predisposition by altering the molecular mechanisms of transformation, specifically affecting p53 regulation.
- This study highlights the critical role of MMR in maintaining genomic integrity and preventing oncogenesis through p53 pathway integrity.