Ounpuu 2017 MiP2017
Rapidly accumulating evidence suggests that environmental factors including nutrients strongly influence the development of colon cancer . In human intestine, dietary fibers from cereals, fruits and vegetables undergo fermentation by anaerobic microbiota leading to the production of short-chain fatty acids (SCFAs). Butyrate, one of the most abundant SCFA, is the main energy source for normal colonocytes while in colon cancer cells it inhibits cell growth and induces differentiation. In our previous work, we have found that colorectal cancer displays altered energy metabolism . Remarkable changes have been identified in phosphotransfer system where creatine kinase (CK) network was significantly downregulated while adenylate kinase (AK) was upregulated. Since butyrate is able to alter the cellular metabolism of cancer cells, we hypothesize that treatment with butyrate may reverse changes in cellular bioenergetics of colon cancer cells.
Colorectal cancer cell line (Caco-2) was treated with 1mM sodium butyrate for 48h. The differentiation was determined by alkaline phosphatase (ALP) activity. Mitochondrial respiration was measured by high-resolution respirometry in permeabilized cells. In addition, the enzymatical activities of three main enzymes involved in the transport of energy-rich phosphoryl (AK, CK and hexokinase (HK)) were measured in differentiated and non-differentiated Caco-2 cells.
Treatment of Caco-2 cells with butyrate was accompanied by reduced proliferation and a 7-fold increase in ALP activity. As observed by confocal microscopy, treated cells displayed a tendency to grow in a monolayer and were more elongated compared to cells cultured in the absence of butyrate. Although the mitochondrial respiration remained unaltered, differentiated cells had a more fragmented mitochondrial network with smaller mitochondrial clusters. The activity of HK was slightly increased in differentiated cells, which may indicate an increased level of glycolysis. Treatment of cells with butyrate also resulted in significantly increased CK activity. On the contrary, the total activity of AK was reduced due to decreased AK1 activity.
In conclusion, treatment with 1mM butyrate caused a fragmentation of the mitochondrial network during the differentiation process of Caco2 cells and reestablished CK/AK homeostasis similar to normal large intestine tissue.
Labels: MiParea: Respiration, Exercise physiology;nutrition;life style, mt-Medicine, Pharmacology;toxicology Pathology: Cancer
Preparation: Permeabilized cells
- National Inst Chemical Physics Biophysics, Tallinn, Estonia. – email@example.com
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- Chekulayev V, Mado K, Shevchuk I, Koit A, Kaldma A, Klepinin A, Timohhina N, Tepp K, Kandashvili M, Ounpuu L, Heck K, Truu L, Planken A, Valvere V, Kaambre T (2015) Metabolic remodeling in human colorectal cancer and surrounding tissues: alterations in regulation of mitochondrial respiration and metabolic fluxes. Biochem Biophys Rep, 4:111-25.