Abstract 1409: Identification of microRNA upregulated in pediatric precursor-B cell acute lymphoblastic leukemia patients with post-induction MRD positivity
Authors: Bauchat Andrea , Raney Lauren , Garai Jone , Li Li , Craver Randall , Zabaleta Jovanny 
Published: September 2020

Abstract
Background and goal: MicroRNAs (miRNA) are small non-coding RNA that regulate post-transcriptional gene expression, influencing cell proliferation, differentiation and death. Extensive research has demonstrated that deregulation of miRNA-associated pathways may participate in the development of cancers. Precursor-B cell acute lymphoblastic leukemia (pre-B ALL) is the most common pediatric malignancy. Over decades, medical advances have helped the risk stratification and treatment modalities for these patients resulting in better favorable prognosis. Unfortunately, approximately 5-10% of standard risk patients and 15-20% of high or very-high risk patients will experience disease relapse. One of the factors involved in risk stratification is the minimal residual disease (MRD) status from bone marrow testing at the end of the initial induction phase of chemotherapy. MRD positivity escalates the risk and may signify some degree of therapy resistance. The aim of this study is to evaluate expression levels of miRNAs in MRD positive samples as compared to MRD negative.
Methods: Bone marrow samples of 14 pre-B cell ALL pediatric patients with MRD positivity (n=5) and MRD negative (n=9) at the end of induction chemotherapy were analyzed. Next-generation sequencing technology was utilized to study the miRNAs profiles of these samples (smallRNA-seq) and to identify potential mRNA targets of selected miRNAs overexpressed in NALM6 B-ALL cell lines for 72 hours (RNA-seq). Analysis was done in Partek Flow and with the web-based tool InteractiVenn.
Results: Twelve miRNAs were upregulated in patients with MRD positivity compared to those who were MRD negative (p values &lt; 0.05). To investigate the potential role of these mRNAs in pre-B ALL cells, we selected 3 of those miRNAs (hsa-miR-34a-5p, -33b-5p, and -210-3p) to transfect the pre-B-ALL cell line NALM6. We identified 145 potential direct target genes for hsa-miR-33b-5p, 79 potential targets for hsa-miR-34a5-p and 142 potential targets for hsa-miR-210-3p. Thirty-five genes were common among all treatments including IL31A, PDZK1 and INSL3. Individual (per miRNA) pathways associated with these genes included immune response, metabolism and cell signaling. One common pathway associated with the differential expression profile of these overexpressed miRNAs was alcohol intake, known to have deleterious consequences in the fetus and inducing, among other things, transgenerational epigenetic alterations that may be associated with malignancy.
Conclusions: Our work identifies potential biomarkers of MRD positivity after induction chemotherapy and identifies pathways associated with this phenomenon. Future plans include the manipulations of several of these pathways to determine their role in the proliferation and aggressiveness of pre-B ALL leukemia cell with the idea of devising new treatment options for those patients with post-induction MRD positivity.
Citation Format: Andrea Bauchat, Lauren Raney, Jone Garai, Li Li, Randall Craver, Jovanny Zabaleta. Identification of microRNA upregulated in pediatric precursor-B cell acute lymphoblastic leukemia patients with post-induction MRD positivity [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 1409.