Hematopoietic stem cells (HSCs) are responsible for the production of blood cells throughout the human lifespan. Single HSCs can give rise to at least eight distinct blood-cell lineages. Together, hematopoiesis, erythropoiesis, and angiogenesis coordinate several biological processes, i.e., cellular interactions during development and proliferation, guided migration, lineage programming, and reprogramming by transcription factors. Any dysregulation of these processes can result in hematological disorders and/or malignancies. Several studies of the molecular mechanisms governing HSC maintenance have demonstrated that protein regulation by the ubiquitin proteasomal pathway is crucial for normal HSC function. Recent studies have shown that reversal of ubiquitination by deubiquitinating enzymes (DUBs) plays an equally important role in hematopoiesis; however, information regarding the biological function of DUBs is limited. In this review, we focus on recent discoveries about the physiological roles of DUBs in hematopoiesis, erythropoiesis, and angiogenesis and discuss the DUBs associated with common hematological disorders and malignancies, which are potential therapeutic drug targets.

The osteoblast differentiation capacity of mesenchymal stem cells must be tightly regulated, as inadequate bone mineralization can lead to osteoporosis, and excess bone formation can cause the heterotopic ossification of soft tissues. The balanced protein level of Msh homeobox 1 (MSX1) is critical during normal osteogenesis. To understand the factors that prevent MSX1 protein degradation, the identification of deubiquitinating enzymes (DUBs) for MSX1 is essential. In this study, we performed loss-of-function-based screening for DUBs regulating MSX1 protein levels using the CRISPR/Cas9 system. We identified ubiquitin-specific protease 11 (USP11) as a protein regulator of MSX1 and further demonstrated that USP11 interacts and prevents MSX1 protein degradation by its deubiquitinating activity. Overexpression of USP11 enhanced the expression of several osteogenic transcriptional factors in human mesenchymal stem cells (hMSCs). Additionally, differentiation studies revealed reduced calcification and alkaline phosphatase activity in USP11-depleted cells, while overexpression of USP11 enhanced the differentiation potential of hMSCs. These results indicate the novel role of USP11 during osteogenic differentiation and suggest USP11 as a potential target for bone regeneration.

Hematopoietic stem cells (HSCs) are responsible for the production of blood cells throughout the human life span. Single HSCs can give rise to at least eight distinct blood cell lineages. Together, hematopoiesis, erythropoiesis and angiogenesis coordinate several biological processes, such as cellular interactions in development and proliferation, guided migration, lineage programming and reprogramming by transcription factors. Any dysregulation of these processes may result in hematological disorders and/or malignancies. Several studies of the molecular mechanisms governing HSC maintenance have demonstrated that protein regulation by the ubiquitin proteasomal pathway is crucial for normal HSC function. Recent studies have shown that the reversal of ubiquitination by deubiquitinating enzymes (DUBs) plays an equally important role in hematopoiesis; however, there is only limited additional information regarding the biological function of DUBs. In this review, we focus on recent discoveries that have led to a better understanding of the physiological roles of DUBs in hematopoiesis, erythropoiesis and angiogenesis. In addition, we discuss the DUBs associated with common hematological disorders and malignancies, which may potentially be therapeutic drug targets.

Background: Osimertinib is a third-generation epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor (TKI) with high efficacy in treating patients with advanced non-small cell lung cancer (NSCLC) harboring EGFR-activating mutations. Although osimertinib is a frontline anticancer agent for NSCLC, several patients inevitably develop tumor recurrence caused by osimertinib resistance. The activation of anexelekto (AXL) or fibroblast growth factor receptor 1 (FGFR1) is reported as a major factor driving osimertinib resistance in NSCLC. Thus, targeting AXL and FGFR1 offers the potential to overcome osimertinib resistance. Methods: In this study, we generated osimertinib-resistant cell lines from EGFR-mutant NSCLC cell lines in vitro and investigated the biological significance of AX-0085 on these cell lines by conducting transcriptomic analyses. Results: The expression of several genes associated with MAPK, ERK, and FGF receptor signaling pathways, including AXL, was altered upon AX-0085 treatment of osimertinib-resistant cells. Furthermore, AX-0085 treatment effectively blocked AXL and FGFR1 activation and sensitized osimertinib-resistant cells. Additionally, AX-0085 inhibited AXL and FGFR1-dependent oncogenic events, including cell proliferation, clonogenicity, and migration. Conclusions: The dual inhibition of AXL and FGFR1 by AX-0085 can overcome acquired osimertinib resistance, supporting its potential as a therapeutic strategy for treating patients with osimertinib-resistant tumors.