Terrie G. Flatt

Background: MicroRNAs (miRNAs) function as post-transcriptional gene expression regulators and influence the development and progression of several cancers, yet their roles in pediatric sarcomas remain poorly defined. Methods: RNA extracted from formalin-fixed paraffin-embedded tumor tissue scrolls of 108 pediatric tumors, including 32 osteosarcoma (OS), 26 Ewing’s sarcoma (EWS), and 50 rhabdomyosarcoma (RMS) cases, were analyzed for microRNA expression using the NanoString multiplex nCounter platform that yielded information on 827 human miRNAs. The expression of candidate miRNAs was validated with in situ hybridization (miRNA-ISH) and QuPath quantification on tissue microarray slides comprising an independent set of 48 OS, 17 EWS, and 104 RMS adult and pediatric cases collectively. Results: The differential expression analysis of nCounter data identified 23 miRNAs enriched in RMS, 33 in EWS, and 45 in OS (>3 fold change and p < 0.01). miR-206 was most strongly associated (>55 fold change, p < 1 × 10⁻⁹) with RMS and demonstrated the highest sensitivity and specificity in distinguishing RMS from EWS and OS; this finding was also confirmed by miRNA-ISH. A combined signature of differentially expressed miRNAs reliably separated alveolar from embryonal RMS. The expression of miR-9-5p in EWS and miR-140-5p in OS discriminated among the different tumors and correlated with adverse patient outcome. The nCounter assay exhibited greater sensitivity than miRNA-ISH in detecting miR-206 and miR-140-5p expression. Conclusions: Collectively, these findings demonstrate that distinct miRNA profiles can differentiate pediatric sarcoma types and subtypes and offer clinically relevant insights into tumor biology, prognosis, and potential diagnostic application.

The perinucleolar compartment (PNC) is a small nuclear body that plays important role in tumorigenesis. PNC prevalence correlates with poor prognosis and cancer metastasis. Its expression in pediatric Ewing sarcoma (EWS) has not previously been documented. In this study, we analyzed 40 EWS tumor cases from Caucasian and Hispanic patients for PNC prevalence by immunohistochemical detection of polypyrimidine tract binding protein and correlated the prevalence with dysregulated microRNA profiles. EWS cases showed staining ranging from 0 to 100%, which were categorized as diffuse (≥77%, n = 9, high PNC) or not diffuse (p = 0.017) and in patients who relapsed with metastatic disease (n = 4; p = 0.011). High PNC was associated with significantly shorter disease-free survival and early recurrence compared to those with low PNC. Using NanoString digital profiling, high PNC tumors revealed upregulation of eight and downregulation of 18 microRNAs. Of these, miR-320d and miR-29c-3p had the most significant differential expression in tumors with high PNC. In conclusion, this is the first study that demonstrates the presence of PNC in EWS, reflecting its utility as a predictive biomarker associated with tumor metastasis, specific microRNA profile, Hispanic ethnic origin, and poor prognosis.

Purpose: Rhabdomyosarcoma (RMS) exhibits a complex prognostic algorithm based on histologic, biologic and clinical parameters. The embryonal (ERMS) and spindle cell-sclerosing RMS (SRMS) histologic subtypes warrant further studies due to their heterogenous genetic background and variable clinical behavior. NanoString digital profiling methods have been previously highlighted as robust novel methods to detect protein and microRNA expression in several cancers but not in RMS. Methods/Patients: To identify prognostic biomarkers, we categorized 12 ERMS and SRMS tumor cases into adverse (n = 5) or favorable (n = 7) prognosis groups and analyzed their signaling pathways and microRNA profiles. The digital spatial profiling of protein and microRNA analysis was performed on formalin-fixed, paraffin-embedded (FFPE) tumor tissue using NanoString technology. Results: The detectable expression of several component members of the PI3K/AKT, MAPK and apoptosis signaling pathways was highlighted in RMS, including INPP4B, Pan-AKT, MET, Pan-RAS, EGFR, phospho-p90 RSK, p44/42 ERK1/2, BAD, BCL-XL, cleaved caspase-9, NF1, PARP and p53. Compared to cases with favorable prognosis, the adverse-prognosis tumor samples had significantly increased expression of INPP4B, which was confirmed with traditional immunohistochemistry. The analysis of microRNA profiles revealed that, out of 798 microRNAs assessed, 228 were overexpressed and 134 downregulated in the adverse prognosis group. Significant over-expression of oncogenic/tumor suppressor miR-3144-3p, miR-612, miR-302d-3p, miR-421, miR-548ar-5p and miR-548y (p < 0.05) was noted in the adverse prognosis group. Conclusion: This study highlights the utility of NanoString digital profiling methods in RMS, where it can detect distinct molecular signatures with the expression of signaling pathways and microRNAs from FFPE tumor tissue that may help identify prognostic biomarkers of interest. The overexpression of INPP4B and miR-3144-3p, miR-612, miR-302d-3p, miR-421, miR-548y and miR-548ar-5p may be associated with worse overall survival in ERMS and SRMS.

The authors report a case of a 13-year-old female with recurrent Burkitt lymphoma who was heavily pretreated with chemotherapy. During chemotherapy for relapse, she developed serious aspergillus infection of the palate and sinuses. Despite 10 microg/kg of filgrastim for 5 days, peripheral blood CD34(+) cells remained <or=1/microL. Hematopoietic progenitor cells were subsequently successfully mobilized with a combination of AMD3100 and filgrastim without tumor or fungus contamination. After transplantation, the patient achieved complete engraftment without exacerbation of fungal infection. This is the first case report of a pediatric patient with relapsed Burkitt lymphoma with mobilization of hematopoietic progenitor cells by AMD3100 without any adverse reactions.