LYG-202 Augments Tumor Necrosis Factor-α-Induced Apoptosis via Attenuating Casein Kinase 2-Dependent Nuclear Factor-κB Pathway in HepG2 Cells

Abstract

Tumor necrosis factor-␣ (TNF-␣) is being used as an antineoplastic agent in treatment regimens of patients with locally advanced solid tumors, but TNF-␣ alone is only marginally active. In clinical use, it is usually combined with other chemical agents to increase its tumor response rate. Our previous studies reported that LYG-202 (5-hydroxy-8-methoxy-7-(4-(4-methylpiperazin-1-yl)butoxy)-2-phenyl-4H-chromen-4-one), a synthesized flavonoid with a piperazine substitution, has antiproliferative, antiangiogenic, and proapoptotic activities in multiple cancer cell lines. Here we evaluated the antineoplastic effect of TNF-␣ and analyzed the mechanism underlying its combination with LYG-202. Our results indicated that LYG-202 significantly increased the cytostatic and proapoptotic activity of TNF-␣ in HepG2 cells and heightened the protein level of apoptosis-related genes including caspase-3, caspase-8/9, cleaved poly(ADPribose) polymerase, and Bid. The fact that LYG-202 had a fitness score similar to that of the casein kinase 2 (CK2) inhibitor naphthyridine-8-carboxylate (CX-4945) implied to us that it may serve as a potential candidate for CK2 inhibitor, and the kinase activity assay suggested that LYG-202 significantly inhibited CK2 activity. Moreover, the electrophoretic mobility shift assay and luciferase assay showed that LYG-202 blocked the TNF-␣-induced nuclear factor-B (NF-B) survival signaling pathway primarily by inactivating protein kinase CK2. In murine xenograft models, we also found that LYG-202 enhanced TNF-␣ antineoplastic activity and inhibited CK2 activity and NF-B-regulated antiapoptotic gene expression. All these results showed that LYG-202 enhanced TNF-␣-induced apoptosis by attenuating the CK2-dependent NF-B pathway and probably is a promising agent in combination with TNF-␣.

Upregulation of CASP9 through NF-κB and Its Target MiR-1276 Contributed to TNFα-Promoted Apoptosis of Cancer Cells Induced by Doxorubicin

“…In the present study, we showed that TNFα alone can induce the upregulation of CASP9 through a NF-κB-mediated FFL, but that it did not induce the apoptosis of the detected cells at the dose of 30 ng/mL. This observation was consistent with previous findings that low doses (10,20 or 50 ng/mL) of TNFα have no effect on cell survival [13,24,31]. NF-κB was therefore considered as having an anti-apoptotic role in TNFα signaling [10,11].…”

“…We also observed that TNFα significantly promoted the apoptosis of HeLa and HepG2 cells induced by DOX. This study, in conjunction with other observations [13,24,31], therefore indicated that TNFα can serve as a sensitizer to conventional chemotherapeutic agents to kill cancer cells by promoting their apoptosis. However, the molecular mechanism underlying this process remains unclear.…”

“…NF-κB was therefore considered as having an anti-apoptotic role in TNFα signaling [10,11]. However, TNFα promotes the apoptosis of cells induced by chemotherapeutic drugs [13,24,31]. The pro-apoptotic target genes of NF-κB induced by TNFα were considered to play a critical role in the process of the increased apoptosis, such as TRAIL [13].…”

Identification of novel NF‐κB transcriptional targets in TNFα‐treated HeLa and HepG2 cells

“…(Cai et al, 1998;Jiang and Wang, 2004;Mohamad et al, 2005). Like the previous study (Schmelz et al, 2004;Xu et al, 2006;Chen et al, 2012), the HeLa and HepG2 cells induced by TNFa treatment did not subject to apoptosis in this study ( Figure S2). Like the previous study (Schmelz et al, 2004;Xu et al, 2006;Chen et al, 2012), the HeLa and HepG2 cells induced by TNFa treatment did not subject to apoptosis in this study ( Figure S2).…”

“…The cytochrome c released from mitochondria to cytoplasm initiate the activation cascade of caspases, which results in cell apoptosis (H€ uttemann et al, 2011;Sun et al, 2012). Like the previous study (Schmelz et al, 2004;Xu et al, 2006;Chen et al, 2012), the HeLa and HepG2 cells induced by TNFa treatment did not subject to apoptosis in this study ( Figure S2). However, the CYCS was upregulated by NF-kB in these TNFainduced cells.…”