Kinetic analysis of butyrate transport in human colon adenocarcinoma cells reveals two different carrier-mediated mechanisms.

Abstract

Butyrate has antitumorigenic effects on colon cancer cells, inhibits cell growth and promotes differentiation and apoptosis. These effects depend on its intracellular concentration, which is regulated by its transport. We have analysed butyrate uptake kinetics in human colon adenocarcinoma cells sensitive to the apoptotic effects of butyrate (BCS-TC2, Caco-2 and HT-29), in butyrate-resistant cells (BCS-TC2.BR2) and in normal colonic cells (FHC). The properties of transport were analysed with structural analogues, specific inhibitors and different bicarbonate and sodium concentrations. Two carrier-mediated mechanisms were detected: a low-affinity/high-capacity (K(m)=109+/-16 mM in BCS-TC2 cells) anion exchanger and a high-affinity/low-capacity (K(m)=17.9+/-4.0 microM in BCS-TC2 cells) proton-monocarboxylate co-transporter that was energy-dependent and activated via PKCdelta (protein kinase Cdelta). All adenocarcinoma cells analysed express MCT (monocarboxylate transporter) 1, MCT4, ancillary protein CD147 and AE2 (anion exchanger 2). Silencing experiments show that MCT1, whose expression increases with butyrate treatment in butyrate-sensitive cells, plays a key role in high-affinity transport. Low-affinity uptake was mediated by a butyrate/bicarbonate antiporter along with a possible contribution of AE2 and MCT4. Butyrate treatment increased uptake in a time- and dose-dependent manner in butyrate-sensitive but not in butyrate-resistant cells. The two butyrate-uptake activities in human colon adenocarcinoma cells enable butyrate transport at different physiological conditions to maintain cell functionality. The high-affinity/low-capacity transport functions under low butyrate concentrations and may be relevant for the survival of carcinoma cells in tumour regions with low glucose and butyrate availability as well as for the normal physiology of colonocytes.

• Authors: Emilio Lecona, Nieves Olmo, Javier Turnay, Angélica Santiago-Gómez, Isabel López de Silanes, Myriam Gorospe, M Antonia Lizarbe
• Journal: The Biochemical journal (Biochem J) Vol. 409 Issue 1 Pg. 311-20 (Jan 01 2008) ISSN: 1470-8728 [Electronic] England
• PMID: 17760565 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• Anion Transport Proteins
• Anions
• Antiporters
• Butyrates
• Cell Cycle Proteins
• DNA Primers
• MCTS1 protein, human
• Oncogene Proteins
• RNA, Small Interfering
• SLC4A Proteins
• Basigin
• Protein Kinase C
• Glucose

Topics

• Adenocarcinoma (metabolism)
• Anion Transport Proteins (biosynthesis)
• Anions
• Antiporters (biosynthesis)
• Basigin (biosynthesis)
• Biological Transport
• Butyrates (metabolism, pharmacokinetics)
• Cell Cycle Proteins (biosynthesis)
• Cell Line, Tumor
• Colonic Neoplasms (metabolism)
• DNA Primers (chemistry)
• Glucose (metabolism)
• Humans
• Kinetics
• Oncogene Proteins (biosynthesis)
• Protein Kinase C (metabolism)
• RNA, Small Interfering (metabolism)
• SLC4A Proteins