RESUMEN
Purpose We aimed to document the acceptability (enrollment rate) and feasibility (phone call delivery rate) of implementing a behavioral PA intervention over 12 weeks, in addition to documenting its effects on patient-reported outcomes and physical functioning. This study also describes the costs of carrying out a behavioral PA intervention. A total of 40 participants were randomized in a 1:1 ratio. The tailored behavioral PA intervention was developed based on the most recent PA guidelines in pediatric oncology and on the COM-B framework to enact PA behavior changes. The prescription (frequency, intensity, time and type (FITT)) was adjusted each week during the weekly support calls. The control group did not receive the intervention. 26 males and 14 females (13.6 years old on average and 2.9 years post-cancer treatment on average) participated in our study. The acceptability rate was 90.9% and the feasibility rate was > 85%. We found that 85% improved PA frequency, 80% improved PA intensity, 100% improved PA time, and 50.0% achieved the recommended PA guidelines. No adverse events were reported over the duration of the intervention. Physical function improved with longer 6-minute walk distances in the intervention group (465.8 ± 74.5 m) than in the control group (398.7 ± 92.9 m) (p = 0.016). PROs scores for all participants were within the limits of the normal range. The estimated cost per participant of carrying out this intervention was USD $126.57. Our 12-week behavioral PA intervention, based on the COM-B framework, was found to be acceptable, feasible and safe in childhood cancer survivors. This study is an important step in the right direction to make exercise standard practice in pediatric oncology.
RESUMEN
Ikaros is a DNA-binding protein that regulates gene expression and functions as a tumor suppressor in B-cell acute lymphoblastic leukemia (B-ALL). The full cohort of Ikaros target genes have yet to be identified. Here, we demonstrate that Ikaros directly regulates expression of the small GTPase, Rab20. Using ChIP-seq and qChIP we assessed Ikaros binding and the epigenetic signature at the RAB20 promoter. Expression of Ikaros, CK2, and RAB20 was determined by qRT-PCR. Overexpression of Ikaros was achieved by retroviral transduction, whereas shRNA was used to knockdown Ikaros and CK2. Regulation of transcription from the RAB20 promoter was analyzed by luciferase reporter assay. The results showed that Ikaros binds the RAB20 promoter in B-ALL. Gain-of-function and loss-of-function experiments demonstrated that Ikaros represses RAB20 transcription via chromatin remodeling. Phosphorylation by CK2 kinase reduces Ikaros' affinity toward the RAB20 promoter and abolishes its ability to repress RAB20 transcription. Dephosphorylation by PP1 phosphatase enhances both Ikaros' DNA-binding affinity toward the RAB20 promoter and RAB20 repression. In conclusion, the results demonstrated opposing effects of CK2 and PP1 on expression of Rab20 via control of Ikaros' activity as a transcriptional regulator. A novel regulatory signaling network in B-cell leukemia that involves CK2, PP1, Ikaros, and Rab20 is identified.