Over expression of ubiquitin-conjugating enzyme E2O in bone marrow mesenchymal stromal cells partially attenuates acute myeloid leukaemia progression

RSK2-mediated phosphorylation and degradation of UBE2O inhibits hepatocellular carcinoma growth and resistance to radiotherapy

Radioresistance poses the main challenge in radiation therapy (RT) for liver cancer, with the DNA Damage response (DDR) being a crucial component of this resistance. Ubiquitin-conjugating enzyme E2O (UBE2O) has been implicated in regulating tumor proliferation, cholesterol metabolism, and drug resistance. However, the role of the ubiquitin-conjugating enzyme E2O (UBE2O) in DDR of liver cancer remains to be fully explored. We discovered an elevated expression of UBE2O within liver cancer tissues, which was notably associated with unfavorable prognoses in hepatocellular carcinoma (HCC) patients. Furthermore, we found that the suppression of UBE2O can effectively reduce the growth and resistance to radiotherapy of HCC cells in vitro and in vivo. Moreover, p90 ribosomal S6 kinase2 (RSK2) was confirmed as a novel interacting kinase of UBE2O, which mediated the phosphorylation and degradation of UBE2O at the Thr838 site. RSK2 inhibition promotes tumor proliferation and resistance to radiotherapy of HCC cells in vitro and in vivo, and these effects are abrogated upon UBE2O knockdown. Collectively, our work revealed that UBE2O promotes tumor progression and resistance to radiotherapy, which was negatively regulated by RSK2 for phosphorylation and degradation, indicating that the RSK2/UBE2O axis provides a potential radiosensitization target for HCC patients.

LncRNA SNHG5 induces CAFs-like phenotype and autophagy of AML-MSCs via PTBP1/ATG5 axis to confer chemoresistance of AML cells

BACKGROUND

Acute myeloid leukemia (AML) is still a threaten to human health due to its high occurrence and poor prognosis. Mesenchymal stem cells (MSCs) in bone marrow microenvironment (BMM) play a critical role in the development of AML. This study elucidated the interaction between MSCs and AML cells and its underlying mechanism.

METHOD

MSCs were isolated, identified, and co-cultured with AML cells. qRT-PCR, Western blotting and immunofluorescence were used to determine molecule expression. Cell viability and apoptosis were determined by CCK-8 and flow cytometry. Exosomes were isolated and characterized, and PKH26 was used for monitoring exosome internalization. RNA-FISH was used to determine the localization of SNHG5. RIP, RNA-pull down and ChIP assays were used to evaluate the molecular interaction.

RESULTS

SNHG5 expression was up-regulated and positively correlated with cancer-associated fibroblasts (CAFs)-related biomarkers in AML-MSCs. AML cells-derived exosomes delivered SNHG5 to enhance its expression in MSCs. SNHG5 overexpression induced CAFs-like phenotype and autophagy in HD-MSCs that led to daunorubicin resistance of AML cells. Mechanistically, SNHG5 stabilized autophagy related 5 (ATG5) mRNA by interaction with polypyrimidine tract-binding protein 1 (PTBP1).

CONCLUSION

AML cells-derived exosomal lncRNA SNHG5 triggered CAFs-like phenotype and autophagy of AML-MSCs via interaction with PTBP1 to increase ATG5 mRNA stability, thereby leading to chemoresistance of AML cells.

The Ubiquitin-Conjugating Enzyme E2 O (UBE2O) and Its Therapeutic Potential in Human Leukemias and Solid Tumors

Protein degradation is a biological phenomenon essential for cellular homeostasis and survival. Selective protein degradation is performed by the ubiquitination system which selectively targets proteins that need to be eliminated and leads them to proteasome degradation. In this narrative review, we focus on the ubiquitin-conjugating enzyme E2 O (UBE2O) and highlight the role of UBE2O in many biological and physiological processes. We further discuss UBE2O's implications in various human diseases, particularly in leukemias and solid cancers. Ultimately, our review aims to highlight the potential role of UBE2O as a therapeutic target and offers new perspectives for developing targeted treatments for human cancers.

Exosome-shuttled FTO from BM-MSCs contributes to cancer malignancy and chemoresistance in acute myeloid leukemia by inducing m6A-demethylation: A nano-based investigation

Although bone marrow mesenchymal stem cells (BM-MSCs)-derived exosomes have been reported to be closely associated with acute myeloid leukemia (AML) progression and chemo-resistance, but its detailed functions and molecular mechanisms have not been fully delineated. Besides, serum RNA m6A demethylase fat mass and obesity-associated protein (FTO)-containing exosomes are deemed as important indicators for cancer progression, and this study aimed to investigate the role of BM-MSCs-derived FTO-exosomes in regulating the malignant phenotypes of AML cells. Here, we verified that BM-MSCs-derived exosomes delivered FTO to promote cancer aggressiveness, stem cell properties and Cytosine arabinoside (Ara-C)-chemoresistance in AML cells, and the underlying mechanisms were also uncovered. Our data suggested that BM-MSCs-derived FTO-exo demethylated m6A modifications in the m6A-modified LncRNA GLCC1 to facilitate its combination with the RNA-binding protein Hu antigen R (HuR), which further increased the stability and expression levels of LncRNA GLCC1. In addition, LncRNA GLCC1 was verified as an oncogene to facilitate cell proliferation and enhanced Ara-C-chemoresistance in AML cells. Further experiments confirmed that demethylated LncRNA GLCC1 served as scaffold to facilitate the formation of the IGF2 mRNA binding protein 1 (IGF2BP1)-c-Myc complex, which led to the activation of the downstream tumor-promoting c-Myc-associated signal pathways. Moreover, our rescuing experiments validated that the promoting effects of BM-MSCs-derived FTO-exo on cancer aggressiveness and drug resistance in AML cells were abrogated by silencing LncRNA GLCC1 and c-Myc. Thus, the present firstly investigated the functions and underlying mechanisms by which BM-MSCs-derived FTO-exo enhanced cancer aggressiveness and chemo-resistance in AML by modulating the LncRNA GLCC1-IGF2BP1-c-Myc signal pathway, and our work provided novel biomarkers for the diagnosis, treatment and therapy of AML in clinic.