Effects of human serum albumin complexed with free fatty acids on cell viability and insulin secretion in the hamster pancreatic β-cell line HIT-T15

• Published in: Life sciences (1973) Vol. 88; no. 17; pp. 810 - 818
• Main Authors: Tuei, Vivian C., Ha, Ji-Sook, Ha, Chung-Eun
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier Inc 25.04.2011
• Subjects: ADIFAB; amino acids; Animals; apoptosis; Apoptosis - drug effects; bovine serum albumin; caspases; Cell Line; Cell Survival - drug effects; Cell viability; Cricetinae; cyclosporine; Cytoprotection - drug effects; Dose-Response Relationship, Drug; Fatty Acids, Nonesterified - metabolism; Fatty Acids, Nonesterified - pharmacology; Free fatty acid; free fatty acids; hamsters; HIT-T15 cell; Human serum albumin; Humans; In vitro protein expression; Insulin - metabolism; Insulin Secretion; Insulin-Secreting Cells - drug effects; Insulin-Secreting Cells - metabolism; Insulin-Secreting Cells - physiology; islets of Langerhans; Linoleic Acid - pharmacology; Mesocricetus; mutants; mutation; oleic acid; Oleic Acid - pharmacology; Palmitic Acid - pharmacology; Serum Albumin - pharmacology; Site-directed mutagenesis; Stearates - pharmacology; stearic acid; HIT-T15 cell; Human serum albumin; Site-directed mutagenesis; Cell viability; ADIFAB; Free fatty acid; In vitro protein expression; Insulin secretion
• ISSN: 0024-3205; 1879-0631
• DOI: 10.1016/j.lfs.2011.02.022

The effects of human serum albumin (HSA) complexed with various free fatty acids (FFAs) on ß-cells have not been studied in detail. In this study, we examined the effects of HSA and its mutants on FFA-induced cell viability changes and insulin secretion from the hamster pancreatic insulinoma cell line, HIT-TI5. Cells were exposed to different FFAs in the presence of HSA or its mutants and/or bovine serum albumin (BSA) for 24 h. Cell viability, apoptosis, insulin secretion, and unbound FFA (FFA u) levels were determined. In the presence of 0.1 mM HSA, palmitate and stearate induced significant cell death at 0.1 mM or higher, whereas myristate, palmitoleate, oleate, elaidate, linoleate, linoelaidate, and conjugated linoleate showed minimal changes on cell viability. Furthermore, oleate and linoleate were clearly cytoprotective against palmitate-induced cell death. The apoptosis inhibitors, cyclosporin A (csA) and the caspase inhibitor ZVAD-FMK, did not completely prevent FFA-induced cell death, although ZVAD-FMK blocked apoptosis with no differences in the presence of either HSA or BSA. In addition, insulin secretion from the cells was significantly reduced in the presence of HSA/oleate complexes. We also found differential effects of HSA mutants complexed with FFAs on cell viability. In summary, our results showed that saturated FFAs induced more cell death than unsaturated FFAs. Furthermore, modified HSA/FFA interactions caused by mutations of key amino acids involved in the binding of FFA to HSA resulted in changes in cell viability, suggesting a possible role of HSA polymorphism on FFA-induced changes in cellular functions.