Silencing heme oxygenase-1 increases the sensitivity of ABC-DLBCL cells to histone deacetylase inhibitor in vitro and in vivo

The role of chidamide in the treatment of B-cell non-Hodgkin lymphoma: An updated systematic review

B-cell non-Hodgkin lymphoma (B-NHL) is a lymphoid malignancy derived from B-cells that remains difficult to treat. Moreover, relapses and refractory cases are common. Abnormalities in epigenetic mechanisms, such as imbalanced histone acetylation affecting certain genes, contribute to relapses and refractory cases. Chidamide (tucidinostat) is a novel histone deacetylase inhibitor that can reverse this epigenetic imbalance and has been approved for the treatment of T-cell malignancies. However, the use of chidamide for B-NHL remains limited, and the lack of relevant literature exacerbates this limitation. We conducted this review to summarize the anticancer activity of chidamide against B-NHL and its clinical applications to overcome drug resistance. This systematic review was conducted according to the PRISMA 2020 guidelines, using some keyword combinations from MEDLINE and EBSCO. The inclusion and exclusion criteria were also defined. Of the 131 records retrieved from databases, 16 were included in the review. Nine articles revealed that chidamide limited tumor progression by modifying the tumor microenvironment, stopping the cell cycle, inducing apoptosis and autophagy, and enhancing complement-dependent and antibody-dependent cell-mediated cytotoxicities.According to seven other studies, administering chidamide in combination with another existing therapeutic regimen may benefit not only patients with relapsed/refractory B-NHL, but also those with newly diagnosed B-NHL. Chidamide plays many important roles in limiting B-NHL progression through epigenetic modifications. Thus, combining chidamide with other anticancer drugs may be more beneficial for patients with newly diagnosed and relapsed/refractory B-NHL.

Sirt1 gene confers Adriamycin resistance in DLBCL via activating the PCG-1α mitochondrial metabolic pathway

Sirt1 is closely related to cells aging, and Sirt1 also plays an important role in diffuse large B-cell lymphoma (DLBCL). However, its mechanism remains unclear. Therefore, we investigated the mechanism of Sirt1 mediated drug-resistance in DLBCL, while the recombinant lentivirus was used to regulate Sirt1 gene expression in DLBCL cell lines. Subsequently, the effect of Sirt1 on DLBCL resistance to Adriamycin was analyzed in vitro. The results show that Sirt1 overexpression confers Adriamycin resistance in DLBCL cell lines. However, inhibition of Sirt1 sensitized DLBCL cell lines to Adriamycin cytotoxicity. Additionally, tumor-bearing mice were used to verify that Sirt1 overexpression confers Adriamycin resistance in vivo after chemotherapy. In addition, we used second-generation sequencing technology and bioinformatics analysis to find that Sirt1 mediated drug-resistance is related to the Peroxisome proliferator-activated receptor (PPAR) signaling pathway, especially to PGC-1α. Interestingly, the mitochondrial energy inhibitor, tigecycline, combined with Adriamycin reversed the cellular resistance caused by Sirt1 overexpression in vivo. Moreover, western blotting and CO-IP assay reconfirmed that Sirt1-mediated drug-resistance is associated with the increased expression of PGC1-α, which induce mitochondrial biogenesis. In summary, this study confirms that Sirt1 is a potential target for DLBCL treatment.

Deletion of HO-1 blocks development of B lymphocytes in mice

B lymphocytes, a key cluster of cells composing the immune system, can protect against abnormal biological factors. Heme oxygenase-1 (HO-1) plays important roles in cell proliferation and immune regulation, but its effects on the development and growth of B lymphocytes are still unknown. Herein, the count of B lymphocytes in HO-1 gene knockout (HO-1^+/-) mice was significantly lower than that of the HO-1 gene wild-type (HO-1^WT) mice. Meanwhile, the cell count of HO-1^+/- mice did not recover after irradiation for one week, due to the G0/G1 phase arrest of Pro-B cells and the augmented apoptosis of Pre-B cells. Up-regulation of HO-1 by lentivirus attenuated the Pro-B cell cycle arrest and Pre-B cell apoptosis. To understand the molecular mechanism by which HO-1 knockout blocked B lymphocyte development, protein-to-protein interaction network and Western blot were used. The PI3K/AKT signaling pathway mediated the regulatory effects of HO-1 on B lymphocytes. In conclusion, HO-1 is a crucial transcriptional repressor for B cell development.

Effect of BCLAF1 on HDAC inhibitor LMK-235-mediated apoptosis of diffuse large B cell lymphoma cells and its mechanism

Diffuse large B-cell lymphoma (DLBCL) is the most common type of adult lymphoma. It is a group of malignant tumors with a large number of clinical manifestations and prognoses. Therefore, it is necessary to explore its unknown potential therapeutic targets. Histone deacetylase inhibitor (HDACi) is a novel drug for the treatment of DLBCL, however pan-HDACis cannot be ignored because of their clinical efficacy. By contrast, specific HDACi is well-tolerated, and LMK-235 is a novel HDACi that is a specific inhibitor of HDAC4 and HDAC5. In this study, we investigated the up-regulation of BCLAF1 through NF-κB signaling pathways in LMK-235, mediating the apoptosis of two diffuse large B-cell lymphoma cell lines, OCI-LY10 and OCI-LY3. Further studies showed that BCLAF1 expression was increased in DLBCL cells after treatment with the NF-κB inhibitor Bay11-7082. The combination of Bay11-7082 and siRNA si-HDAC4 significantly increased BCLAF1 expression and further increased apoptosis. These results indicate that BCLAF1 plays an important role in LMK-235-mediated apoptosis and may be a potential target for the treatment of diffuse large B-cell lymphoma.