Caspase-2, the most evolutionarily conserved member of the
caspase family, has been shown to be involved in apoptosis induced by various stimuli. Our recent work indicates that
caspase-2 has putative functions in
tumor suppression and protection against cellular stress. As such, the loss of
caspase-2 enhances lymphomagenesis in Eµ-Myc transgenic mice, and
caspase-2 KO (Casp2(-/-)) mice show characteristics of
premature aging. However, the extent and specificity of
caspase-2 function in
tumor suppression is currently unclear. To further investigate this,
ataxia telangiectasia mutated KO (Atm(-/-)) mice, which develop spontaneous thymic
lymphomas, were used to generate Atm(-/-)Casp2(-/-) mice. Initial characterization revealed that
caspase-2 deficiency enhanced growth retardation and caused synthetic perinatal lethality in Atm(-/-) mice. A comparison of
tumor susceptibility demonstrated that Atm(-/-)Casp2(-/-) mice developed
tumors with a dramatically increased incidence compared with Atm(-/-) mice. Atm(-/-)Casp2(-/-)
tumor cells displayed an increased proliferative capacity and extensive
aneuploidy that coincided with elevated oxidative damage. Furthermore, splenic and thymic T cells derived from premalignant Atm(-/-)Casp2(-/-) mice also showed increased levels of
aneuploidy. These observations suggest that the
tumor suppressor activity of
caspase-2 is linked to its function in the maintenance of
genomic stability and suppression of oxidative damage. Given that ATM and
caspase-2 are important components of the DNA damage and
antioxidant defense systems, which are essential for the maintenance of
genomic stability, these
proteins may synergistically function in
tumor suppression by regulating these processes.