Proteomic Profiling on apoptotic effect of keto-boswellic acid


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Fahad AL Zadjali1,Asma Bani Oraba1
1Sultan Qaboos University

Abstract

Background

Acetyl 11-keto-b-boswellic acid (AKBA) is a natural-triterpene that has anti-inflammatory effect via targeting 5-lipoxygenase. At higher dose it selectively exerts selective toxicity toward multiple tumor cell lines and spares normal epithelial cells. Multiple cellular targets of AKBA were proposed and usually major key players in cancer cell apoptotis. Yet, specific apoptotic mechanism of AKBA is not yet known. We aimed to identify apoptotic mechanism of AKBA via proteomic profiling on breast cancer MCF-7 cells.  

Method

MCF-7 cells were treated with 50 μM AKBA for 24 hr before lysis. Proteins were extracted and were subjected to isolectrical focusing into 7 fractions. Each fraction was run into nano-HPLC inline with Orbitrap Q Exactive instrument. Proteomic profile of more than 4000 proteins were detected. Variance stablizing normalization was used to normalize the signal ratio. Difference in the protein abundance between control and AKBA treatment groups was analyzed using  t-test. Statistical significances were adjusted for multiple comparison using False Detection Rate (FDR) at 5%.  Fold change was calculated from the ratio between treated/control. We used the fold 1.6 as cut-off value used generally in proteomic. 

Results

Proteomic profiling revealed majority of downregulate dproteins were mitochondrial proteins. Down regulated proteins (NDUFV1, NDUFA2, MRPL45, MRPL14, MRPL21, MRPL37) are cellular component of mitochondrial envelope, mitochondrial membrane and mitochondrial inner membrane. They linked to mitochondrial pathway translational initiation, translational elongation, translational termination, mitochondrion organization and mitochondrial translation. Up regulated protein are involved in autophagy and mitophagy pathway (FUNDC1, SQSTM1, ULK1).

Conclusion

Porteomic data show that AKBA upregulates autophagy pathway along with downregulation of mitochondria. This suggest that cellular mechanism of tumor cell toxicity driven by AKBA is mediated via mitophagy-induced apoptosis.