High-mobility group protein�B1 silencing promotes susceptibility of retinoblastoma cells to chemotherapeutic drugs through downregulating nuclear factor-κB

Abstract

The aim of the present study was to investigate the effects of high-mobility group protein B1 (HMGB1) silencing on the susceptibility of retinoblastoma (RB) cells to chemotherapeutic drugs and the underlying molecular mechanisms. Western blot analysis revealed that vincristine (VCR), etoposide (ETO) and carboplatin (CBP) significantly increased the expression of HMGB1 in Weri‑Rb-1 and Y79 cells compared with the untreated control (P<0.01). siRNA HMGB1 and siRNA negative control (NC) were transfected to Y79 cells by Lipofectamine™ 2000 and, following VCR treatment, the expression of HMGB1 and nuclear factor-κB (NF-κB) was analyzed. siRNA HMGB1 transfection silenced HMGB1 expression. The cytotoxicity of VCR to cells with and without siRNA HMGB1 was investigated by methyl thiazolyl tetrazolium (MTT) assay. siRNA HMGB1 markedly reduced the IC50 value of VCR to RB cells through downregulating the expression of NF-κB, similar to pyrrolidinedithiocarbamate (PDTC). Moreover, following siRNA HMGB1, siRNA NC and ammonium PDTC treatment, the apoptosis of RB cells with VCR incubation was evaluated by Hoechst staining, and the expression of cleaved caspase-3, cleaved poly(ADP-ribose) polymerase (PARP), Beclin 1 and p62 were determined with western blot analysis. The LC3 puncta were determined with immunofluorescence assay. The results demonstrated that VCR treatment significantly downregulated the expression of cleaved caspase-3, cleaved PARP and p62, and upregulated the expression of Beclin 1 in RB cells (P<0.01). Similar to the NF-κB inhibitor PDTC, siRNA HMGB1 significantly promoted apoptosis and suppressed autophagy of VCR‑treated RB cells through reversing the effects of VCR on these signaling molecules (P<0.01). Therefore, HMGB1 silencing promoted the susceptibility of RB cells to chemotherapeutic drugs through downregulating NF-κB.

<p>MicroRNA-665 inhibits the oncogenicity of retinoblastoma by directly targeting high-mobility group box 1 and inactivating the Wnt/&beta;-catenin pathway</p>

“…42 HMGB1 increases oncogene activity in the genesis and development of RB, and it is involved in the regulation of RB cell proliferation, autophagy, apoptosis, the cell cycle, viability, metastasis, and chemotherapy sensitivity. [43][44][45][46] In the present study, we demonstrated that miR-665 directly targets HMGB1 and inactivates the Wnt/β-catenin pathway to inhibit the various malignant behaviors of RB in vitro and in vivo. These findings suggest that miR-665-mediated silencing of HMGB1 and inactivation of the Wnt/β-catenin pathway may represent an effective therapeutic approach for patients with RB.…”

Investigation of Key Signaling Pathways Associating miR-204 and Common Retinopathies

“…HMGB1 plays a very important role in division and invasion of cancer cells. Therefore, several studies have been performed to inhibit the function of HMGB1 by siRNAs and miRNAs, and all have shown that inhibition of HMGB1 increases the induction of apoptosis and decreases cell division, progression, and invasion of Y79 cells [ 23 , 43 , 44 ]. Limited studies have examined PolA1 in retinoblastoma.…”

Targeting HMGB1 in the Treatment of Non-Small Cell Lung Adenocarcinoma

“…It directly interacts with the two shallow concave surfaces formed by the arms of the HMGB1 box regions [47]. Glycyrrhizin inhibits HMGB1 accumulation in the extracellular space, and prevents its interaction with proinflammatory receptors like TLR4, TLR2, and RAGE receptors [82][83][84][85]. Diseases where inflammation is a major factor in pathogenesis such as oncogenic transformation, bacterial infection, or diet-induced symbiosis are also sensitive to treatment with glycyrrhizin [46,49,52,53].…”

“…Histone deacetylases (HDAC) inhibitors are a class of compounds that increase the acetylation of lysine residues on histone proteins by inhibiting the activity of HDAC enzymes. In cancer, HDAC inhibitors inhibit the proliferation of tumor cells in culture and in-vivo by inducing apoptosis and cell cycle arrest [85]. Cellular localization of HMGB1 is dictated by the presence or absence of acetyl groups on the protein.…”