Skip to main page content
Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
. 2011 Dec 15;11:129.
doi: 10.1186/1472-6882-11-129.

Boswellia Sacra Essential Oil Induces Tumor Cell-Specific Apoptosis and Suppresses Tumor Aggressiveness in Cultured Human Breast Cancer Cells

Affiliations
Free PMC article

Boswellia Sacra Essential Oil Induces Tumor Cell-Specific Apoptosis and Suppresses Tumor Aggressiveness in Cultured Human Breast Cancer Cells

Mahmoud M Suhail et al. BMC Complement Altern Med. .
Free PMC article

Abstract

Background: Gum resins obtained from trees of the Burseraceae family (Boswellia sp.) are important ingredients in incense and perfumes. Extracts prepared from Boswellia sp. gum resins have been shown to possess anti-inflammatory and anti-neoplastic effects. Essential oil prepared by distillation of the gum resin traditionally used for aromatic therapy has also been shown to have tumor cell-specific anti-proliferative and pro-apoptotic activities. The objective of this study was to optimize conditions for preparing Boswellea sacra essential oil with the highest biological activity in inducing tumor cell-specific cytotoxicity and suppressing aggressive tumor phenotypes in human breast cancer cells.

Methods: Boswellia sacra essential oil was prepared from Omani Hougari grade resins through hydrodistillation at 78 or 100 °C for 12 hours. Chemical compositions were identified by gas chromatography-mass spectrometry; and total boswellic acids contents were quantified by high-performance liquid chromatography. Boswellia sacra essential oil-mediated cell viability and death were studied in established human breast cancer cell lines (T47D, MCF7, MDA-MB-231) and an immortalized normal human breast cell line (MCF10-2A). Apoptosis was assayed by genomic DNA fragmentation. Anti-invasive and anti-multicellular tumor properties were evaluated by cellular network and spheroid formation models, respectively. Western blot analysis was performed to study Boswellia sacra essential oil-regulated proteins involved in apoptosis, signaling pathways, and cell cycle regulation.

Results: More abundant high molecular weight compounds, including boswellic acids, were present in Boswellia sacra essential oil prepared at 100 °C hydrodistillation. All three human breast cancer cell lines were sensitive to essential oil treatment with reduced cell viability and elevated cell death, whereas the immortalized normal human breast cell line was more resistant to essential oil treatment. Boswellia sacra essential oil hydrodistilled at 100 °C was more potent than the essential oil prepared at 78 °C in inducing cancer cell death, preventing the cellular network formation (MDA-MB-231) cells on Matrigel, causing the breakdown of multicellular tumor spheroids (T47D cells), and regulating molecules involved in apoptosis, signal transduction, and cell cycle progression.

Conclusions: Similar to our previous observations in human bladder cancer cells, Boswellia sacra essential oil induces breast cancer cell-specific cytotoxicity. Suppression of cellular network formation and disruption of spheroid development of breast cancer cells by Boswellia sacra essential oil suggest that the essential oil may be effective for advanced breast cancer. Consistently, the essential oil represses signaling pathways and cell cycle regulators that have been proposed as therapeutic targets for breast cancer. Future pre-clinical and clinical studies are urgently needed to evaluate the safety and efficacy of Boswellia sacra essential oil as a therapeutic agent for treating breast cancer.

Figures

Figure 1
Figure 1
Human breast cell growth. Human breast cancer cells and immortalized normal breast epithelial cells (1x103) were seeded in triplicate in their culture media, and quantified for their growth between 1 and 4 days following cell seeding. Cell numbers were calculated from standard curves with known numbers of cells. Results are presented as mean ± SEM from 4 independent experiments. * indicates statistical differences between normal and malignant cells at P < 0.05.
Figure 2
Figure 2
Breast cell viability in response to Boswellia sacra essential oil exposure. Human breast cells (5x103) were seeded in each well of 96-well tissue culture plates in triplicate. Following adherence, cells were treated with Boswellia sacra essential oil hydrodistilled at (A) 78 oC or (B) 100 oC for 12 hours. Cell viability was determined using the colometric XTT assay at 24 hours after essential oil treatment. Data are presented as mean ± SEM from at least 4 independent experiments. * indicates statistical differences between essential oil-treated breast cancer cells and immortalized breast cells (P < 0.05).
Figure 3
Figure 3
Quantitative analysis of Boswellia sacra essential oil-induced human breast cancer cell death. Human breast cell lines were seeded in each well of 96-well tissue culture plates at the concentration of 5x103 cells/well in triplicate. Following overnight adherence, cells were treated with either Boswellia sacra essential oil hydrodistilled at (A) 78 oC or (B) 100 oC. Cell death was determined at 3 hours following essential oil exposure by the LDH cytotoxicity detection kit. Data were presented as mean average numbers of dead cells ± SEM from at least 3 independent experiments. * indicates statistical differences of cell death between cancer cells and immortalized breast cells (P < 0.05).
Figure 4
Figure 4
Boswellia sacra essential oil-induced apoptosis in human breast cancer cells. Human breast cancer MDA-MB-231 cells were seeded at the concentration of 5x105 cells/60 mm tissue culture plates for adherence and subjected essential oils (1:800 and 1:1,200 dilutions of 78 and 100 oC, respectively) treatment. Both genomic DNA and total cellular proteins were isolated at specific time points as indicated. (A) Essential oil-induced genomic DNA fragmentation. (B) Essential oil-activated pro- and cleavage of caspases. Experiments were repeated at least twice and representative results are presented.
Figure 5
Figure 5
Assessment of anti-invasive activity of Boswellia sacra essential oil. Matrigel basement membrane matrix (100 μl) was transferred to each well of 96-well culture plates and allowed to polymerize at 37 oC. MDA-MB-231 cells (4 × 104) were resuspended in 100 µl growth media and added on the top of the polymerized Matrigel (A and B). In separate wells, cells were either mixed with 100 µl of 78 oC essential oil at (C) 1:800 or (D) 1:600 dilution, or 100 oC essential oil at (E) 1:1,500 or (F) 1:1,200 dilution and layered on the top of Matrigel. Formation of vascular-like networks was assessed at 24 hours following oil treatment. The capabilities of MDA-MB-231 cells in forming networks of tubes and Boswellia sacra essential oil in suppressing the cellular network formation on Matrigel are observed at 100× magnification. Experiments were repeated at least 3 times and representative images are presented.
Figure 6
Figure 6
Capability of Boswellia sacra essential oil in suppressing multicellular spheroid growth. Breast cancer T47 cells (1 × 104) were seeded into each well of the 96-well NanoCulture® plates. Following the formation of spheroids, cells were either (A) left untreated or treated with 78 oC essential oil at (B) 1:800 or (C) 1:600 dilution, or 100 oC essential oil at (D) 1:1,500 or (E) 1:1,200 dilution. Spheroids images were captured at 24 hours following essential oil treatment at 100x magnification. Experiments were repeated at least 3 times and representative images are presented.
Figure 7
Figure 7
Boswellia sacra essential oil-regulated signaling molecules activation and cell cycle-related proteins expression in human breast cancer cells. Breast cancer cells were seeded at the concentration of 5 × 105 cells/60 mm tissue culture plate. After adherence, cells were treated with either 1:800 dilution of 78 oC or 1:1,200 dilution of 100 oC essential oil. Total cellular proteins were isolated between 0 (untreated control) and 4 hours following essential oils treatment. Western blot analysis was performed to determine levels of Akt and ERK1/2 phosphorylation as well as cyclin D1 and cdk4 proteins expression. Expression of β-actin was also determined in parallel and used as a protein loading control. Experiments were repeated at least twice for each cell line and representative results are presented.

Similar articles

See all similar articles

Cited by 32 articles

See all "Cited by" articles

References

    1. Maloney GA. Gold, frankincense, and myrrh : an introduction to Eastern Christian spirituality. New York: Crossroads Pub. Co; 1997.
    1. Banno N, Akihisa T, Yasukawa K, Tokuda H, Tabata K, Nakamura Y, Nishimura R, Kimura Y, Suzuki T. Anti-inflammatory activities of the triterpene acids from the resin of Boswellia carteri. J Ethnopharmacol. 2006;107:249–253. doi: 10.1016/j.jep.2006.03.006. - DOI - PubMed
    1. Langmead L, Rampton DS. Review article: complementary and alternative therapies for inflammatory bowel disease. Aliment Pharmacol Ther. 2006;23:341–349. doi: 10.1111/j.1365-2036.2006.02761.x. - DOI - PubMed
    1. Chevrier MR, Ryan AE, Lee DY, Zhongze M, Wu-Yan Z, Via CS. Boswellia carterii extract inhibits TH1 cytokines and promotes TH2 cytokines in vitro. Clin Diagn Lab Immunol. 2005;12:575–580. - PMC - PubMed
    1. Sharma ML, Khajuria A, Kaul A, Singh S, Singh GB, Atal CK. Effect of salai guggal ex-Boswellia serrata on cellular and humoral immune responses and leucocyte migration. Agents Actions. 1988;24:161–164. doi: 10.1007/BF01968095. - DOI - PubMed

MeSH terms

Feedback