Altered erythropoiesis and decreased number of erythrocytes in children with neuroblastoma

Abstract

Neuroblastoma (NB) is a pediatric tumor presenting at diagnosis either as localized or metastatic disease, which mainly involves the bone marrow (BM). The physical occupancy of BM space by metastatic NB cells has been held responsible for impairment of BM function. Here, we investigated whether localized or metastatic NB may alter hematopoietic lineages' maturation and release of mature cells in the periphery, through gene expression profiling, analysis of BM smears, cell blood count and flow cytometry analysis. Gene ontology and disease-associated analysis of the genes significantly under-expressed in BM resident cells from children with localized and metastatic NB, as compared to healthy children, indicated anemia, blood group antigens, and heme and porphyrin biosynthesis as major functional annotation clusters. Accordingly, in children with NB there was a selective impairment of erythrocyte maturation at the ortho-chromic stage that resulted in reduced erythrocyte count in the periphery, regardless of the presence of metastatic cells in the BM. By considering all NB patients, low erythrocyte count at diagnosis associated with worse survival. Moreover, in the subset of metastatic patients, low erythrocyte count, hemoglobin and hematocrit and high red cell distribution width at follow-up also associated with worse outcome. These observations provide an alternative model to the tenet that infiltrating cells inhibit BM functions due to physical occupancy of space and may open a new area of research in NB to understand the mechanism(s) responsible for such selective impairment.

Keywords: bone marrow; erythrocytes; microenvironment; neuroblastoma; survival.

Figure 1

(A) Percentages of myeloid, erythroid and lymphoid cell populations present in BM smears, (B) percentages of pro-erythroblasts, baso-erythroblasts, polychromatophilic and orthocromic erythroblasts present in BM smears from NB patients with stage L (grey dots, N=20) and stages M and Ms (black dots, N=50) and healthy children (open dots, N=11).

Figure 2

(A) Percentages of monocytes and granulocytes, (B) percentages of stage II and III erythroblasts present in BM samples from NB patients (closed dots, N=11 for panel A and N=15 for panel B) and healthy subjects (open dots, N=10).

Figure 3. Peripheral cell blood counts obtained from patients with stage L (gray dots, N=64), stage M and Ms (black dots, N=51) and healthy children (open dots, N=32)

(A) erythrocytes, (B) neutrophils, (C) platelets, (D) monocytes and (E) lymphocytes.

Figure 4

Overall survival curves obtained by stratifying the CBC cohort of NB patients (N=115) with number of (A) neutrophils, (B) monocytes, (C) erythrocytes and (D) platelets in PB samples above and below the cut-off value determined for each cell population by ROC curves (5.7×10⁹/L for neutrophils, 0.4×10⁹/L for monocytes, 3.3×10¹²/L for erythrocytes and 400×10⁹/L for platelets).

Figure 5

Overall survival plots obtained by stratifying stage M NB patients (N=29) with hemoglobin (panels A and B), hematocrit (panels C and D) and RDW values (panels E and F) above and below the cut-off value determined by ROC curves at end of cure (11.3 g/dL, 33.7% and 14.4%, panels A, C and E, respectively) or at follow-up (12.1 g/dL, 35.3% and 15.7 %, panels B, D, and F, respectively).