The t(8;9)(p22;p24) Is a Recurrent Abnormality in Chronic and Acute Leukemia that Fuses PCM1 to JAK2

Abstract

In this study, we show that CK2 (casein kinase II, CKII) participates in apoptotic responses following ionizing radiation (IR). Using HeLa human cervical carcinoma cells, we find that transfection of small interfering RNA against the CK2 α and/or α′ catalytic subunits results in enhanced apoptosis following IR damage as measured by flow cytometry techniques, compared with a control small interfering RNA. Within 2 to 6 hours of IR, CK2 α partially localizes to perinuclear structures, whereas a marked nuclear localization of α′ occurs. Treatment with a pan-caspase inhibitor or transfection of ARC (apoptosis repressor with caspase recruitment domain) suppresses the apoptotic response to IR in the CK2-reduced cells, indicating involvement of caspases. Additionally, we find that CK2 α and/or α′ reduction affects cell cycle progression independent of IR damage in this human cell line. However, the G₂-M checkpoint following IR is not affected in CK2 α- and/or α′-reduced cells. Thus, our data suggest that CK2 participates in inhibition of apoptosis and negatively regulates caspase activity following IR damage.