ABSTRACT
BACKGROUND: Long non-coding RNAs (lncRNAs) play a variety of cellular roles, including regulation of transcription and translation, leading to alterations in gene expression. Some lncRNAs modulate the expression of chromosomally adjacent genes. Here, we assess the roles of the lncRNA CASC15 in regulation of a chromosomally nearby gene, SOX4, and its function in RUNX1/AML translocated leukemia. RESULTS: CASC15 is a conserved lncRNA that was upregulated in pediatric B-acute lymphoblastic leukemia (B-ALL) with t (12; 21) as well as pediatric acute myeloid leukemia (AML) with t (8; 21), both of which are associated with relatively better prognosis. Enforced expression of CASC15 led to a myeloid bias in development, and overall, decreased engraftment and colony formation. At the cellular level, CASC15 regulated cellular survival, proliferation, and the expression of its chromosomally adjacent gene, SOX4. Differentially regulated genes following CASC15 knockdown were enriched for predicted transcriptional targets of the Yin and Yang-1 (YY1) transcription factor. Interestingly, we found that CASC15 enhances YY1-mediated regulation of the SOX4 promoter. CONCLUSIONS: Our findings represent the first characterization of this CASC15 in RUNX1-translocated leukemia, and point towards a mechanistic basis for its action.
Subject(s)
Core Binding Factor Alpha 2 Subunit/genetics , Leukemia, Myeloid, Acute/genetics , RNA, Long Noncoding/genetics , SOXC Transcription Factors/genetics , Animals , Cell Line, Tumor , Cell Proliferation/genetics , Child , Gene Expression Profiling/methods , Gene Expression Regulation, Neoplastic/genetics , Humans , Mice , Precursor Cell Lymphoblastic Leukemia-Lymphoma/genetics , Prognosis , Promoter Regions, Genetic/genetics , Translocation, Genetic/genetics , YY1 Transcription Factor/geneticsABSTRACT
UNLABELLED: Long noncoding RNAs (lncRNA) have been found to play a role in gene regulation with dysregulated expression in various cancers. The precise role that lncRNA expression plays in the pathogenesis of B-acute lymphoblastic leukemia (B-ALL) is unknown. Therefore, unbiased microarray profiling was performed on human B-ALL specimens, and it was determined that lncRNA expression correlates with cytogenetic abnormalities, which was confirmed by qRT-PCR in a large set of B-ALL cases. Importantly, high expression of BALR-2 correlated with poor overall survival and diminished response to prednisone treatment. In line with a function for this lncRNA in regulating cell survival, BALR-2 knockdown led to reduced proliferation, increased apoptosis, and increased sensitivity to prednisolone treatment. Conversely, overexpression of BALR-2 led to increased cell growth and resistance to prednisone treatment. Interestingly, BALR-2 expression was repressed by prednisolone treatment and its knockdown led to upregulation of the glucocorticoid response pathway in both human and mouse B cells. Together, these findings indicate that BALR-2 plays a functional role in the pathogenesis and/or clinical responsiveness of B-ALL, and that altering the levels of particular lncRNAs may provide a future direction for therapeutic development. IMPLICATIONS: lncRNA expression has the potential to segregate the common subtypes of B-ALL, predict the cytogenetic subtype, and indicate prognosis.
