The chemokine, CCL5, is a key mediator for the recruitment of immune cells into tumors and tissues. Akt/NF-κB signaling is significantly activated by CCL5. However, the role of NF-κB inactivation in apoptosis induced by negative regulation of CCL5 remains unclear. Here, we analyzed the effect of cordycepin on NF-κB activity in SKOV-3 cells and found that cordycepin-mediated inhibition of NF-κB signaling induced apoptosis in SKOV-3 cells via the serial activation of caspases. In addition, immune-blotting analysis showed that CCL5 is highly expressed in SKOV-3 cells. In addition to activating caspases, we show that, cordycepin prevents TNF-α-induced increase in CCL5, Akt, NF-κB, and c-FLIPL activation and that CCL5 siRNA could inhibit Akt/NF-κB signaling. Moreover, cordycepin negatively regulated the TNF-α-mediated IκB/NF-κB pathway and c-FLIPL activation to promote JNK phosphorylation, resulting in caspase-3 activation and apoptosis. Also, we show that c-FLIPL is rapidly lost in NF-κB activation-deficient. siRNA mediated c-FLIP inhibition increased JNK. SP600125, a selective JNK inhibitor, downregulated p-JNK expression in cordycepin-treated SKOV-3 cells, leading to suppression of cordycepin-induced apoptosis. Thus, these results indicate that cordycepin inhibits CCL5-mediated Akt/NF-κB signaling, which upregulates caspase-3 activation in SKOV-3 cells, supporting the potential of cordycepin as a therapeutic agent for ovarian cancer.

Houttuynia cordata Thunb (H cordata), a medicinal plant, has anticancer activity, as it inhibits cell growth and induces cell apoptosis in cancer. However, the potential anti-cancer activity and mechanism of H cordata for human liver cancer cells is not well understood. Recently, we identified hypoxia-inducible factor (HIF)-1A, Forkhead box (FOX)O3, and MEF2A as proapoptotic factors induced by H cordata, suggesting that HIF-1A, FOXO3, and MEF2A contribute to the apoptosis of HepG2 hepatocellular carcinoma cells. FOXO3 transcription factors regulate target genes involved in apoptosis. H cordata significantly increased the mRNA and protein expression of HIF-1A and FOXO3 and stimulated MEF2A expression in addition to increased apoptosis in HepG2 cells within 24 hours. Therefore, we determined the potential role of FOXO3 on apoptosis and on H cordata–induced MEF2A in HepG2 cells. HIF-1A silencing by siRNA attenuated MEF2A and H cordata–mediated FOXO3 upregulation in HepG2 cells. Furthermore, H cordata–mediated MEF2A expression enhanced caspase-3 and caspase-7, which were abolished on silencing FOXO3 with siRNA. In addition, H cordata inhibited growth of human hepatocellular carcinoma xenografts in nude mice. Taken together, our results demonstrate that H cordata enhances HIF-1A/FOXO3 signaling, leading to MEF2A upregulation in HepG2 cells, and in parallel, it disturbs the expression of Bcl-2 family proteins (Bax, Bcl-2, and Bcl-xL), which results in apoptosis. Taken together, these findings demonstrate that H cordata promotes the activation of HIF-1A–FOXO3 and MEF2A pathways to induce apoptosis in human HepG2 hepatocellular carcinoma cells and is, therefore, a promising candidate for antitumor drug development.

Diabetes mellitus is a complex and heterogeneous disease, which has β-cell dysfunction at its core. Glucotoxicity affects pancreatic islets, causing β-cell apoptosis. However, the role of JNK/β-catenin signaling in glucotoxic β-cell apoptosis is not well understood. Recently, we identified tetraspanin-2 (TSPAN2) protein as a proapoptotic β-cell factor induced by glucose, suggesting that TSPAN2 might contribute to pancreatic β-cell glucotoxicity. To investigate the effects of glucose concentration on TSPAN2 expression and apoptosis, we used reverted immortalized RNAKT-15 human pancreatic β cells. High TSPAN2 levels up-regulated phosphorylated (p) JNK and induced apoptosis. p-JNK enhanced the phosphorylation of β-catenin and Dickkopf-1 (Dkk1). Dkk1 knockdown by small interfering (si)RNA up-regulated nuclear β-catenin, suggesting that it is a JNK/β-catenin-dependent pathway. siRNA-mediated TSPAN2 depletion in RNAKT-15 cells increased nuclear β-catenin. This decreased BCL2-associated X protein (Bax) activation, leading to marked protection against high glucose–induced apoptosis. Bax subfamily proteins induced apoptosis through caspase-3. Thus, TSPAN2 might have induced Bax translocation and caspase-3 activation in pancreatic β cells, thereby promoting the apoptosis of RNAKT-15 cells by regulating the JNK/β-catenin pathway in response to high glucose concentrations. Targeting TSPAN2 could be a potential therapeutic strategy to treat glucose toxicity-induced β-cell failure.—Hwang, I.-H., Park, J., Kim, J. M., Kim, S. I., Choi, J.-S., Lee, K.-B., Yun, S. H., Lee, M.-G., Park, S. J., Jang, I.-S. Tetraspanin-2 promotes glucotoxic apoptosis by regulating the JNK/β-catenin signaling pathway in human pancreatic β cells.

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The ubiquitous transcription factor, NF-κB, has been reported to inhibit apoptosis and induce drug resistance in cancer cells. Cordyceps militaris extract (CME) is involved in the regulation of the NF-κB signaling pathway. However, the detailed role of CME in the suppression of the NF-κB signaling pathway is unclear. We found that CME dose-dependently inhibited tumor necrosis factor-α (TNF-α)-induced NF-κB activation in TK-10 human renal cell carcinoma. CME prevented NF-κB from translocating to the nucleus, which resulted in the downregulation of GADD45B, upregulation of MKK7, and phosphorylation of JNK (p-JNK). The increased activation of Bax led to pronounced CME-induced apoptosis, which occurred through caspase-3. Furthermore, the siRNAmediated knockdown of GADD45B inhibited MKK7 expression, whereas the siRNA-mediated inhibition of MKK7 downregulated p-JNK and the JNK inhibitor, SP600125, inhibited Bax expression. Thus, these results indicated that CME inhibited the activation of GADD45B via the inhibition of NF-κB activation, which upregulated the MKK7-JNK signaling pathway to induce apoptosis in TK-10 cells. Thus, this study reveals a novel anticancer function of CME.