Bezielle (BZL101)-induced oxidative stress damage followed by redistribution of metabolic fluxes in breast cancer cells: a combined proteomic and metabolomic study.
Klawitter J, Klawitter J, Gurshtein J, Corby K, et al. Int J Cancer. 2011 Dec 15;129(12):2945-57. doi: 10.1002/ijc.25965. Epub 2011 Apr 20.
Bezielle (BZL101) is an orally administered aqueous extract of Scutellaria barbata for treatment of advanced and metastatic breast cancer. Phase I trials showed promising tolerability and efficacy. In our study, we used a combined proteomic-metabolomic approach to investigate the molecular pathways affected by Bezielle in ER-positive BT474 and ER-negative SKBR3 cell lines. In both, Bezielle inhibited cell proliferation, induced cell death and G2 cycle arrest by regulating the mediator proteins Jab1, p27(Kip1) and p21(Cip1) .
In addition, it stimulated reactive oxygen species production, hyperactivation of PARP and inhibition of glycolysis. Bezielle's ability to induce oxidative stress was associated with the changes in expression of redox potential maintaining enzymes: glutathione- and thioredoxin-related proteins and peroxiredoxins. In regards to cell metabolism, decreased expression of ?-enolase was associated with a reduction of de novo (13) C-lactate formation. Reduced Krebs cycle activity as evidenced by the reduced expression of ?-ketoglutarate dehydrogenase and succinyl-CoA synthetase led to decreased intracellular succinate concentrations.
By inhibiting glucose metabolism, cells reacted by lowering the expression of glucose transporters and resulting in decreased intracellular glucose concentration. Decreased expression of fatty acid synthase and reduced concentration of phosphocholine indicated considerable changes in phospholipid metabolism. Ultimately, by inhibiting the major energy-producing pathways, Bezielle caused depletion of ATP and NAD(H). Both cell lines were responsive, thus suggesting that Bezielle has the potential to be effective against ER-negative breast cancers.
In conclusion, Bezielle's cytotoxicity toward cancer cells is primarily based on inhibition of metabolic pathways that are preferentially activated in tumor cells thus explaining its specificity for cancer cells.
Identification and analysis of the active phytochemicals from the anti-cancer botanical extract Bezielle.
Chen V, Staub RE, Baggett S, Chimmani R, Tagliaferri M, Cohen I, Shtivelman E. PLoS One. 2012;7(1):e30107. doi: 10.1371/journal.pone.0030107. Epub 2012 Jan 17.
Bezielle is a botanical extract that has selective anti-tumor activity, and has shown a promising efficacy in the early phases of clinical testing. Bezielle inhibits mitochondrial respiration and induces reactive oxygen species (ROS) in mitochondria of tumor cells but not in non-transformed cells. The generation of high ROS in tumor cells leads to heavy DNA damage and hyper-activation of PARP, followed by the inhibition of glycolysis. Bezielle therefore belongs to a group of drugs that target tumor cell mitochondria, but its cytotoxicity involves inhibition of both cellular energy producing pathways. We found that the cytotoxic activity of the Bezielle extract in vitro co-purified with a defined fraction containing multiple flavonoids. We have isolated several of these Bezielle flavonoids, and examined their possible roles in the selective anti-tumor cytotoxicity of Bezielle. Our results support the hypothesis that a major Scutellaria flavonoid, scutellarein, possesses many if not all of the biologically relevant properties of the total extract. Like Bezielle, scutellarein induced increasing levels of ROS of mitochondrial origin, progressive DNA damage, protein oxidation, depletion of reduced glutathione and ATP, and suppression of both OXPHOS and glycolysis. Like Bezielle, scutellarein was selectively cytotoxic towards cancer cells. Carthamidin, a flavonone found in Bezielle, also induced DNA damage and oxidative cell death. Two well known plant flavonoids, apigenin and luteolin, had limited and not selective cytotoxicity that did not depend on their pro-oxidant activities. We also provide evidence that the cytotoxicity of scutellarein was increased when other Bezielle flavonoids, not necessarily highly cytotoxic or selective on their own, were present. This indicates that the activity of total Bezielle extract might depend on a combination of several different compounds present within it.
In vitro antitumor mechanisms of various Scutellaria extracts and constituent flavonoids.
Parajuli P, Joshee N, Rimando AM, Mittal S, Yadav AK. Planta Med. 2009 Jan;75(1):41-8. doi: 10.1055/s-0028-1088364. Epub 2008 Nov 24.
Scutellaria is a traditional herbal remedy with potential anti-cancer activity. The purpose of this study was to evaluate anticancer mechanisms of thirteen Scutellaria species and analyze their leaf, stem and root extracts for levels of common biologically active flavonoids: apigenin, baicalein, baicalin, chrysin, scutellarein, and wogonin. Malignant glioma, breast carcinoma and prostate cancer cells were used to determine tumor-specific effects of Scutellaria on cell proliferation, apoptosis and cell cycle progression, via the MTT assay and flow cytometry-based apoptosis and cell cycle analysis. The extracts and individual flavonoids inhibited the proliferation of malignant glioma and breast carcinoma cells without affecting primary or non-malignant cells. The flavonoids exhibited different mechanisms of anti-tumor activity as well as positive interactions. The antitumor mechanisms involved induction of apoptosis and cell cycle arrest at G1/G2. Of the extracts tested, leaf extracts of S. angulosa, S. integrifolia, S. ocmulgee and S. scandens were found to have strong anticancer activity. This study provides basis for further mechanistic and translational studies into adjuvant therapy of malignant tumors using Scutellaria leaf tissues.
Inhibitory effects of a chemically standardized extract from Scutellaria barbata in human colon cancer cell lines, LoVo.
Goh D, Lee YH, Ong ES. J Agric Food Chem. 2005 Oct 19;53(21):8197-204.
Scutellaria barbata (SB) is a medicinal plant that contains flavonone compounds such as scutellarein, scutellarin, carthamidin, isocarthamidin, and wogonin. A functional proteomic approach was used to study the inhibitory effects of a chemically standardized extract from SB in human colon adrencarcinoma, LoVo. In this work, a stable isotope was not used in the proposed method developed. The whole cell lysates from the control and treated cells were digested with trypsin, and the peptides were separated by two-dimensional (cation-exchange and reversed-phase) liquid chromatography and tandem mass spectrometry. The differentially expressed proteins identified using the current approach supported the data obtained from cell-cycle analysis with flow cytometry. With flow-cytometry analysis, a significant increase in the sub G1 phase was observed with a higher dose of extract from SB. Our results suggest that the chemically standardized extract from SB can induce cell death in the human colon cancer cell line. Our current work showed that the proposed platform provided a rapid approach to study the molecular mechanism because of the inhibitory effects of different doses of the botanical extracts on LoVo cell lines. This included a network of proteins involved in metabolism, regulation of the cell cycle, and transcription-factor activity.