The Splicing Factor RBM17 Affect the Development of MDS through Metabolic Regulation

Myelodysplastic syndromes (MDS) showed a decrease in trisomy, mainly in the elderly. A Hematopoietic stem cell transplant is the only cure for myelodysplastic syndrome. However, only a small number of patients can benefit from it because of the complications or the older age. At present, the first-line therapeutic drugs are limited and new therapeutic targets need to be found. Here, we show that splicing factors RBM17 can affect the occurrence and development of MDS by regulating the proliferation and senescence of HSPC cells, which may be a novel therapeutic target.

In order to find new therapeutic targets, we collected bone marrow cells from 3 healthy volunteers and 3 untreated MDS patients for single cell sequencing. In the MDS group, the proportion of HSPC subsets was unbalanced, and the differentiation of MDS-HSPC into myeloid and lymphoid lineage was also impaired. In addition, signaling pathways associated with cell biological functions, such as DNA replication, were reduced in MDS patients. Compared to the normal group's HSC(hematopoietic stem cell) and MPP( multipotent progenitor), upregulated genes of HSC and MPP in MDS are mainly enriched in “cell burial effect” and “Wnt signaling pathway”. The downregulated genes are mainly enriched in OXPHOS and DNA repair, indicating that MDS-HSPC are in an aging state.

Alternative splicing is an important post-transcriptional regulatory mode, which affects the development of many kinds of tumors. Splicing factors also play a role in hematological diseases, with high expression of RBM17 maintaining the stem cell properties of leukemic (AML) cells. At present, there is less research on splicing factors in MDS, and we found that the expression of RBM17 was significantly decreased in HSPC cells of MDS patients. RBM17 showed similar gene expression trends in other MDS datasets (GSE58831, GSE43399). We further divided MDS patients in the GSE58831 dataset into those with high or low expression of RBM17 by means. K-M analysis showed that the survival time of MDS patients with low expression of RBM17 was significantly decreased.

To further validate the expression level of RBM17 in MDS cell lines, we performed PCR assay with AML cell line K562 as control. The high expression level of RBM17 in AML has been verified. Compared with the control group, the expression of RBM17 in MUTZ-1 cells was significantly decreased, and the expression of RBM17 in SKM-1 cells was also decreased.

We next analyzed the possible mechanism of action of RBM17 in MDS. By comparing the differentially expressed genes in MDS-HSPC, we found that the expression of proliferation-related genes (such as CDK1) were decreased and HK2 was increased. Furthermore, EP300 is upregulated in MDS-HSPCs, whereas HDAC1 and HDAC3 were downregulated. The abnormal expression of HK2, EP300, HDAC1 and HDAC3 was related to histone lactate. The expression level of RBM17 was positively correlated with HK2 and EP300, and negatively correlated with HDAC1 and HDAC3. We hypothesized that RBM17 could inhibit the proliferation of MDS-HSPC cells by promoting glycolysis and histone lactate, and promote cell senescence.

Our study shows that RBM17 expression is decreased in MDS-HSPC cells. The low expression of RBM17 may increase the production of intracellular lactate and activate histone Kla by inducing the expression of HK2, then inhibit the expression of proliferation-related genes and promote the expression of senescence-related genes.

No relevant conflicts of interest to declare.