Transcript-Level Dysregulation of BCL2 Family Genes in Acute Myeloblastic Leukemia

Simple Summary The BCL2 family comprises pro- and anti-apoptotic proteins whose cellular abundance, modifications, and interactions determine the cell fate. Its contribution to pathogenesis of acute myeloid leukemia (AML) was not widely studied and none of the studies published before presented a complex picture of BCL2 family gene expression. Therefore, we decided to analyze the AML transcriptome sequencing data to outline this picture and look for relations between the expression of particular BCL2 family members and the genes encoding interacting proteins, presence of mutations, and clinical features. Our findings should not only shed light on apoptosis- and oncogenesis-related processes, but may also be implemented in clinical practice. Prognostic significance, association with response to therapy and potential application in the selection of therapeutic targets are of particular importance. The expression of apoptosis-related BCL2 family genes, fine-tuned in normal cells, is dysregulated in many neoplasms. In acute myeloid leukemia (AML), this problem has not been studied comprehensively. To address this issue, RNA-seq data were used to analyze the expression of 26 BCL2 family members in 27 AML FAB M1 and M2 patients, divided into subgroups differently responding to chemotherapy. A correlation analysis, analysis of variance, and Kaplan-Meier analysis were applied to associate the expression of particular genes with other gene expression, clinical features, and the presence of mutations detected by exome sequencing. The expression of BCL2 family genes was dysregulated in AML, as compared to healthy controls. An upregulation of anti-apoptotic and downregulation of pro-apoptotic genes was observed, though only a decrease in BMF, BNIP1, and HRK was statistically significant. In a group of patients resistant to chemotherapy, overexpression of BCL2L1 was manifested. In agreement with the literature data, our results reveal that BCL2L1 is one of the key players in apoptosis regulation in different types of tumors. An exome sequencing data analysis indicates that BCL2 family genes are not mutated in AML, but their expression is correlated with the mutational status of other genes, including those recurrently mutated in AML and splicing-related. High levels of some BCL2 family members, in particular BIK and BCL2L13, were associated with poor outcome.

Automated summary

The dysregulated expression of BCL2 family genes in acute myeloid leukemia (AML) is characterized by an upregulation of anti-apoptotic genes and a downregulation of pro-apoptotic genes. High expression of BCL2L1 was observed in patients resistant to chemotherapy. BCL2L1 is identified as a key player in apoptosis regulation in different types of tumors.