RAB3D/MDM2/β-catenin/c-MYC axis exacerbates the malignant behaviors of acute myeloid leukemia cells in vitro and in vivo

TARDBP drives T-cell acute lymphoblastic leukemia progression by binding MDM2 mRNA, involving β-catenin pathway

T-cell acute lymphoblastic leukemia (T-ALL) is a dangerous hematological malignancy. The trans-activation response DNA binding protein (TARDBP), an RNA/DNA binding protein, is involved in the growth and metastasis of multiple cancers. However, TARDBP has not been reported in T-ALL. It was found that TARDBP was highly expressed in pediatric T-ALL samples by microarray GSE26713 (log2 fold change >1, p < .05). Herein, TARDBP was silenced and overexpressed by lentivirus transduction in T-ALL cell lines, including Jurkat and Molt4 cells. In vitro, silencing TARDBP inhibited T-ALL cell proliferation and cycle progression and accelerated cell apoptosis, while overexpressing TARDBP induced the opposite effects. In addition, we investigated whether the β-catenin pathway could be activated by TARDBP in T-ALL cells. Moreover, XAV-939, a β-catenin inhibitor, was capable of suppressing the malignant phenotypes in TARDBP-overexpressed T-ALL cells. In vivo, TARDBP-silenced or TARDBP-overexpressed T-ALL cells were injected into mice. We found that TARDBP promoted T-ALL cell growth in the spleens and bone marrows of mice. On the basis of GSE26713, there was a significant correlation between TARDBP and mouse double minute 2 (MDM2). The RIP-PCR assay demonstrated that TARDBP bound MDM2 mRNA in T-ALL cells. The rescue experiments further revealed the roles of the TARDBP/MDM2 axis in T-ALL cell phenotypes, which was also reflected by mRNA-seq. In aggregate, we explored a promising biomarker, TARDBP, for T-ALL treatment. The underlying mechanisms might involve the interaction with MDM2 mRNA and the regulation of the β-catenin pathway.

LRRC1 knockdown downregulates MACF1 to inhibit the malignant progression of acute myeloid leukemia by inactivating β-catenin/c-Myc signaling

Acute myeloid leukemia (AML) is a hematologic disease associated with genetic abnormalities. This study aimed to explore the role of leucine-rich repeat-containing protein 1 (LRRC1) in the malignant activities of AML and to reveal the molecular mechanism related to microtubule actin cross-linking factor 1 (MACF1). GEPIA database was used to analyze the expression of LRRC1 in bone marrow tissues of AML patients and the correlation between LRRC1 expression and survival analysis. LRRC1 was knocked down to assess the change of AML cell proliferation, cell cycle and apoptosis using CCK-8 assay and flow cytometry. Besides, the contents of extracellular acidification and oxygen consumption rates were measured to evaluate the glycolysis. Additionally, the interaction between LRRC1 and MACF1 predicted by MEM database and was verified by co-immunoprecipitation (Co-IP) assay. Then, MACF1 was overexpressed to conduct the rescue experiments. Expression of proteins in β-catenin/c-Myc signaling was detected by western blot. Finally, AML xenograft mouse model was established to observe the impacts of LRRC1 silencing on the tumor development. Notably upregulated LRRC1 expression was observed in bone marrow tissues of AML patients and AML cells, and patients with the higher LRRC1 expression displayed the lower overall survival. LRRC1 depletion promoted cell cycle arrest and apoptosis and inhibited the glycolysis. Co-IP confirmed the interaction between LRRC1 and MACF1. MACF1 upregulation relieved the impacts of LRRC1 knockdown on the malignant activities of AML cells. Moreover, LRRC1 silencing inhibited the development of xenograft tumor growth of HL-60 cells in nude mice, suppressed MACF1 expression and inactivated the β-catenin/c-Myc signaling. Collectively, LRRC1 knockdown suppressed proliferation, glycolysis and promoted apoptosis in AML cells by downregulating MACF1 expression to inactivate β-catenin/c-Myc signaling.