Figure 3. WHSC1 is a unique oncogene in B-ALL.

A, mutational diagram illustrating the mutations of WHSC1. B, representative Sanger sequence tracings that show somatic E1099K mutation in 4 patients (upper and middle panel, diagnosis and the matched remission sample, respectively) and 2 ALL cell lines (RS4;11, SEM, lower panel). C, elevation of WHSC1 mRNA in B-ALL samples or B-ALL cell lines compared with normal B-cells (data were retrieved from GSE48558). ****, p<0.0001. D, patients whose ALL cells at diagnosis had higher levels of WHSC1, also had a higher likelihood to undergo relapse (GSE11877, 207 Pediatric ALL. Censored: Patients in clinical remission, or with a second malignancy, or with a toxic death as a first event were censored at the date of last contact). **, p<0.01. E, aberrant WHSC1 expression was associated with high risk leukemia and early occurrence of relapse: very early relapse (within 18 months after initial diagnosis); early relapse (>18 months after initial diagnosis but <6 months after cessation of frontline treatment); late relapse (>6 months after cessation of frontline treatment). Data were retrieved from GSE4698 (60 childhood ALL (28)). **, p<0.01. F, western blot shows the silencing effect of CRISPR-Cas9 sgRNA targeting WHSC1. G, H, silencing of WHSC1 by either shRNA or CRISPR-Cas9 guide RNAs markedly reduced the clonogenic growth of B-ALL cells RS4;11 (cell line carrying WHSC1 E1099K mutation) in methylcellulose assay. Non-target, Non-target shRNA Control. EV, empty vector control. **, p<0.01, ***, p<0.001. I, J, silencing of WHSC1 impairs in vivo cell growth of RS4;11. *, p<0.05.