1. 2-Deoxy-d-glucose Promotes Buforin IIb-Induced Cytotoxicity in Prostate Cancer DU145 Cells and Xenograft Tumors
Yangke Wanyan, Xixi Xu, Kehang Liu, Huidan Zhang, Junai Zhen, Rong Zhang, Jumei Wen, Ping Liu, Yuqing Chen Molecules. 2020 Dec 7;25(23):5778. doi: 10.3390/molecules25235778.
Inhibition of the glycolytic pathway is a critical strategy in anticancer therapy because of the role of aerobic glycolysis in cancer cells. The glycolytic inhibitor 2-Deoxy-d-glucose (2-DG) has shown potential in combination with other anticancer agents. Buforin IIb is an effective antimicrobial peptide (AMP) with broad-spectrum anticancer activity and selectivity. The efficacy of combination treatment with 2-DG and buforin IIb in prostate cancer remains unknown. Here, we tested the efficacy of buforin IIb as a mitochondria-targeting AMP in the androgen-independent human prostate cancer cell line DU145. Combining 2-DG with buforin IIb had a synergistic toxic effect on DU145 cells and mouse xenograft tumors. Combination treatment with 2-DG and buforin IIb caused stronger proliferation inhibition, greater G1 cell cycle arrest, and higher apoptosis than either treatment alone. Combination treatment dramatically decreased L-lactate production and intracellular ATP levels, indicating severe inhibition of glycolysis and ATP production. Flow cytometry and confocal laser scanning microscopy results indicate that 2-DG may increase buforin IIb uptake by DU145 cells, thereby increasing the mitochondria-targeting capacity of buforin IIb. This may partly explain the effect of combination treatment on enhancing buforin IIb-induced apoptosis. Consistently, 2-DG increased mitochondrial dysfunction and upregulated Bax/Bcl-2, promoting cytochrome c release to initiate procaspase 3 cleavage induced by buforin IIb. These results suggest that 2-DG sensitizes prostate cancer DU145 cells to buforin IIb. Moreover, combination treatment caused minimal hemolysis and cytotoxicity to normal WPMY-1 cells. Collectively, the current study demonstrates that dual targeting of glycolysis and mitochondria by 2-DG and buforin IIb may be an effective anticancer strategy for the treatment of some advanced prostate cancer.
2. Interactions of the novel antimicrobial peptide buforin 2 with lipid bilayers: proline as a translocation promoting factor
S Kobayashi, K Takeshima, C B Park, S C Kim, K Matsuzaki Biochemistry. 2000 Jul 25;39(29):8648-54. doi: 10.1021/bi0004549.
Buforin 2 is an antimicrobial peptide discovered in the stomach tissue of the Asian toad Bufo bufo gargarizans. The 21-residue peptide with +6 net charge shows antimicrobial activity an order of magnitude higher than that of magainin 2, a membrane-permeabilizing antimicrobial peptide from Xenopus laevis [Park, C. B., Kim, M. S., and Kim, S. C. (1996) Biochem. Biophys. Res. Commun. 218, 408-413]. In this study, we investigated the interactions of buforin 2 with phospholipid bilayers in comparison with magainin 2 to obtain insight into the mechanism of action of buforin 2. Equipotent Trp-substituted peptides were used to fluorometrically monitor peptide-lipid interactions. Circular dichroism measurements showed that buforin 2 selectively bound to liposomes composed of acidic phospholipids, assuming a secondary structure similar to that in trifluoroethanol/water, which is an amphipathic helix distorted around Pro(11) with a flexible N-terminal region [Yi, G. S., Park, C. B., Kim, S. C., and Cheong, C. (1996) FEBS Lett. 398, 87-90]. Magainin 2 induced the leakage of a fluorescent dye entrapped within lipid vesicles coupled to lipid flip-flop. These results have been interpreted as the formation of a peptide-lipid supramolecular complex pore [Matsuzaki, K. (1998) Biochim. Biophys. Acta 1376, 391-400]. Buforin 2 exhibited much weaker membrane permeabilization activity despite its higher antimicrobial activity. In contrast, buforin 2 was more efficiently translocated across lipid bilayers than magainin 2. These results suggested that the ultimate target of buforin 2 is not the membrane but intracellular components. Furthermore, buforin 2 induced no lipid flip-flop, indicating that the mechanism of translocation of buforin 2 is different from that of magainin 2. The role of Pro was investigated by use of a P11A derivative of buforin 2. The derivation caused a change to magainin 2-like secondary structure and membrane behavior. Pro(11) was found to be a very important structural factor for the unique properties of buforin 2.
3. Buforin IIb induces androgen-independent prostate cancer cells apoptosis though p53 pathway in vitro
Yangyang Han, Ming Lu, Jinsong Zhou Toxicon. 2019 Oct;168:16-21. doi: 10.1016/j.toxicon.2019.06.016. Epub 2019 Jun 20.
Prostate cancer (PCa) is one of the most common male cancer types, androgen-independent prostate cancer possesses poor prognosis. Buforin IIb, an attractive antibacterial peptide derived from histone H2A, showed selective cytotoxicity against most cancer cell lines. However, the molecular mechanism of buforin IIb on prostate cancer cell has still not been determined. In this study, we found buforin IIb significantly inhibited the prostate cancer cells proliferation, Furthermore, buforin IIb-induced cell apoptosis through downregulation of pro-caspase 3/8/9, poly (ADP-ribose) polymerase PARP and anti-apoptotic Bcl-2 and upregulation of pro-apoptotic Bax. In addition, buforin IIb increased the expression of tumor suppressor p53 and its target genes - p21, fas, noxa and puma. The cytotoxicity of buforin IIb on PC-3 and Du-145 cells is decreased by p53 knockdown. In conclusion, our results indicated that buforin IIb induced PC-3 and Du-145 cell apoptosis and could be considered as a potential drug for prostate cancer.
