Yamada Chiharu, Okada Kentaro, Odaira Koya, Tokoro Mahiru, Iwamoto Eisuke, Sanada Masashi, Noura Mina, Okamoto Syuichi, Yasuda Takahiko, Tsuzuki Shinobu, Kiyoi Hitoshi, Hayakawa Fumihiko
Division of Cellular and Genetic Sciences, Department of Integrated Health Sciences, Nagoya University Graduate School of Medicine, Nagoya, Japan.
Clinical Research Center, National Hospital Organization Nagoya Medical Center, Nagoya, Japan.
Cancer Med. 2024 Jul;13(14):e7471. doi: 10.1002/cam4.7471.
ZNF384-fusion (Z-fusion) genes were recently identified in B-cell acute lymphoblastic leukemia (B-ALL) and are frequent in Japanese adult patients. The frequency is about 20% in those with Philadelphia chromosome-negative B-ALL. ZNF384 is a transcription factor and Z-fusion proteins have increased transcriptional activity; however, the detailed mechanisms of leukemogenesis of Z-fusion proteins have yet to be clarified.
We established three transfectants of cell lines expressing different types of Z-fusion proteins, and analyzed their gene expression profile (GEP) by RNA-seq. We also analyzed the GEP of clinical ALL samples using our previous RNA-seq data of 323 Japanese ALL patients. We selected upregulated genes in both Z-fusion gene-expressing transfectants and Z-fusion gene-positive ALL samples, and investigated the binding of Z-fusion proteins to regulatory regions of the candidate genes by ChIP-qPCR.
We selected six commonly upregulated genes. After the investigation by ChIP-qPCR, we finally identified CREB5 and RGS1 as direct and common target genes. RGS1 is an inhibitor of CXCL12-CXCR4 signaling that is required for the homing of hematopoietic progenitor cells to the bone marrow microenvironment and development of B cells. Consistent with this, Z-fusion gene transfectants showed impaired migration toward CXCL12.
We identified CREB5 and RGS1 as direct and common transcriptional targets of Z-fusion proteins. The present results provide novel insight into the aberrant transcriptional regulation by Z-fusion proteins.
ZNF384融合（Z-融合）基因最近在B细胞急性淋巴细胞白血病（B-ALL）中被发现，在日本成年患者中很常见。在费城染色体阴性的B-ALL患者中，其频率约为20%。ZNF384是一种转录因子，Z-融合蛋白具有增强的转录活性；然而，Z-融合蛋白白血病发生的详细机制尚未阐明。
我们建立了表达不同类型Z-融合蛋白的三种细胞系转染子，并通过RNA测序分析它们的基因表达谱（GEP）。我们还使用之前对323名日本ALL患者的RNA测序数据，分析了临床ALL样本的GEP。我们选择了在表达Z-融合基因的转染子和Z-融合基因阳性的ALL样本中均上调的基因，并通过染色质免疫沉淀定量PCR（ChIP-qPCR）研究Z-融合蛋白与候选基因调控区域的结合情况。
我们选择了六个共同上调的基因。通过ChIP-qPCR研究后，我们最终确定CREB5和RGS1为直接且共同的靶基因。RGS1是CXCL12-CXCR4信号通路的抑制剂，而该信号通路是造血祖细胞归巢至骨髓微环境和B细胞发育所必需的。与此一致的是，Z-融合基因转染子对CXCL12的迁移能力受损显示。
我们确定CREB5和RGS1为Z-融合蛋白的直接且共同的转录靶标。目前的结果为Z-融合蛋白异常转录调控提供了新的见解。
