Fig 2: PLK1 regulates proliferation and survival in MLL-AF4+ leukemic cells(A and B) PLK1 expression in human FL and CB HSC/MPPs (A) and murine FL and BM LMPPs (B). RNA-seq data are shown as mean ± SD; each dot represents a sample.(C) qPCR of PLK1 expression in human FL and CB HSC/MPPs and infant MLL-AF4+ ALL blasts (MA4+). FL, n = 3; CB, n = 2; MA4+, n = 5. Data are shown as mean + SD.(D and E) PLK1 expression in the RNA-seq datasets by (D) Agraz-Doblas et al. (2019) and (E) Andersson et al. (2015). MA4, MLL-AF4; MA4-R, relapsed; MA9, MLL-AF9; MLL wild type (WT), MLL germline B-ALL; iALL, infant B-ALL; pALL, pediatric B-ALL.(F) Cell cycle profile of SEM cells. Red, SEM cells vehicle-treated control; blue, SEM cells treated with 50 nM volasertib for 24 h; orange, SEM cells treated with 50 nM volasertib for 48 h.(G) Cell cycle profile of cells treated with 50 nM of volasertib after 24 h. Data are shown as mean ± SD. Student’s t test was performed.(H) Viability of cells treated with 50 nM of volasertib. Data are shown as mean ± SD. ANOVA was performed.(I) qPCR of PLK1 expression in SEM and RS4;11 cells; n = 3. Data are shown as mean + SD. Student’s t test was performed.(J) Viability of RS4;11 cells treated with 50 nM volasertib for 72 h. Data are shown as mean +SD. Student’s t test was performed.(K) CD34+ FL and CB cells treated with 50 nM volasertib for 48 h (FL, n = 3; CB, n = 3). Data are shown as mean ± SD. Student’s t test was performed.NS, not significant. *p < 0.05, **p < 0.01, ***p < 0.001, ****p < 0.0001. See also Table S4.

Fig 3: FL-derived HSC/MPPs are characterized by an over-proliferative and oncogenic nature(A) Experimental design. HSC/MPPs were sorted as CD34+CD38-CD45RA-.(B) GSEA of genes overrepresented in FL HSC/MPPs.(C) GO of processes overrepresented in FL HSC/MPPs. n = number of genes overrepresented for a specific process.(D) Heatmap of genes linked previously with cancer or leukemia identified in the top 25 DE genes.(E) Expression of MYC and MYCN in FL and CB HSC/MPPs. RNA-seq data are shown as mean ± SD; each dot represents a sample.(F) GSEA of genes overrepresented in FL HSC/MPPs.(G) Expression of TOP2A and PARP1 in FL and CB HSC/MPPs. RNA-seq data are shown as mean ± SD; each dot represents a sample.(H) Heatmap of tumor suppressor genes overrepresented in the CB samples.(I) GSEA of genes overrepresented in CB HSC/MPPs.(J) GO of processes overrepresented in CB HSC/MPPs.(K) GSEA of genes overrepresented in CB HSC/MPPs.(L) Heatmap of DE genes between HSC/MPPs and LMPPs, which are in common with SEM cell MLL-AF4-spreading targets.FDR, false discovery rate; FPKM, fragments per kilobase of transcript per million mapped reads; NES, normalized enrichment score. *p < 0.05, **p < 0.01, ***p < 0.001, ****p < 0.0001. See also Figure S1 and Table S1.