In Vivo Effectiveness of Orlistat in the Suppression of Human Colorectal Cancer Cell Proliferation

Background/Aim: Fatty acid synthase (FASN) provides palmitate for cell membrane formation in colorectal cancer (CRC) cells, however, palmitate is also available in the blood of CRC patients. The aim of this study was to examine whether orlistat, a FASN inhibitor, is able to attenuate CRC cell growth despite the availability of extracellular palmitate. Materials and Methods: Palmitate concentrations were measured in serum from CRC patients and healthy controls. HT-29 CRC cells were treated with orlistat and palmitate. Results: Treatment of CRC cells with orlistat caused a dose-dependent inhibition of cell proliferation. In turn, delivery of extracellular palmitate at doses lower than those found in the serum of CRC patients reversed inhibition by orlistat concentrations of up to 10 mu M. Conclusion: Inhibition of CRC cell proliferation by orlistat is reversed by palmitate which is present at high levels in the serum. Therefore, orlistat may be effective in vivo only at high concentrations.