This Article Full Text Full Text (PDF) Supplementary Data, Kolar, et al. Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Kolar, S. S. N. Articles by Chapkin, R. S. Search for Related Content PubMed PubMed Citation Articles by Kolar, S. S. N. Articles by Chapkin, R. S. Related Collections Preclinical Intervention Preclinical Intervention: In Vitro: Drugs, Mechanisms

Docosahexaenoic Acid and Butyrate Synergistically Induce Colonocyte Apoptosis by Enhancing Mitochondrial Ca²⁺ Accumulation

¹ Faculty of Nutrition, ² Department of Veterinary Integrative Biosciences, and ³ Center for Environmental and Rural Health, Texas A&M University, College Station, Texas

Requests for reprints: Robert S. Chapkin, Department of Nutrition and Food Science, Kleberg Biotechnology Center, MS 2253, Texas A&M University, College Station, TX 77843-2253. Phone: 979-845-0448; Fax: 979-862-2378; E-mail: r-chapkin{at}tamu.edu.

We have previously shown that butyrate, a short-chain fatty acid fiber fermentation product, induces colonocyte apoptosis via a nonmitochondrial, Fas-mediated, extrinsic pathway. Interestingly, fermentable fiber when combined with fish oil containing docosahexaenoic acid (DHA, 22:6n-3) exhibits an enhanced ability to induce apoptosis and protect against colon tumorigenesis. To determine the molecular mechanism of action, the effect of DHA and butyrate cotreatment on intracellular Ca²⁺ homeostasis was examined. Mouse colonocytes were treated with 50 µmol/L DHA or linoleic acid (LA) for 72 h ± butyrate (0–10 mmol/L) for the final 24 h. Cytosolic and mitochondrial Ca²⁺ levels were measured using Fluo-4 and Rhod-2. DHA did not alter basal Ca²⁺ or the intracellular inositol trisphosphate (IP₃) pool after 6 h butyrate cotreatment. In contrast, at 12 and 24 h, DHA- and butyrate-treated cultures exhibited a 25% and 38% decrease in cytosolic Ca²⁺ compared with LA and butyrate. Chelation of extracellular Ca²⁺ abolished the effect of thapsigargin on the IP₃-releasable Ca²⁺ pool. DHA and butyrate cotreatment compared with untreated cells increased the mitochondrial-to-cytosolic Ca²⁺ ratio at 6, 12, and 24 h by 73%, 18%, and 37%, respectively. The accumulation of mitochondrial Ca²⁺ preceded the onset of apoptosis. RU-360, a mitochondrial-uniporter inhibitor, abrogated mitochondrial Ca²⁺ accumulation and also partially blocked apoptosis in DHA and butyrate cotreated cells. Collectively, these data show that the combination of DHA and butyrate, compared with butyrate alone, further enhances apoptosis by additionally recruiting a Ca²⁺-mediated intrinsic mitochondrial pathway. [Cancer Res 2007;67(11):5561–8]

This article has been cited by other articles:

				S. S. N. Kolar, R. Barhoumi, E. S. Callaway, Y.-Y. Fan, N. Wang, J. R. Lupton, and R. S. Chapkin Synergy between docosahexaenoic acid and butyrate elicits p53-independent apoptosis via mitochondrial Ca2+ accumulation in colonocytes Am J Physiol Gastrointest Liver Physiol, November 1, 2007; 293(5): G935 - G943. [Abstract] [Full Text] [PDF]