Hamid Behrouj - Department of Biochemistry, School of Medicine, Shiraz University of Medical Sciences, Shiraz, Iran
Pooneh Mokarram - Department of Biochemistry, School of Medicine, Shiraz University of Medical Sciences, Shiraz, Iran

Objective(s): Oncogenic RAS mutations occur in nearly ۵۰% of colorectal cancer cases and are usually dependent on the autophagy mechanism to maintain tumorigenesis. We have recently demonstrated that CK۱α controls autophagy machinery possibly through the AKT/p-ß-catenin (S۵۵۲) signaling in colorectal cancer cells harboring RAS mutation. It has been found that a lipid-protein complex comprising oleic acid binds to human α-lactalbumin, known as HAMLET (human α -lactalbumin made lethal to tumor cells), targets a broad range of kinases including CK۱α. Therefore, this study was designed to investigate the effects of BAMLET (bovine α -lactalbumin made lethal to tumor cells, the bovine counterpart of HAMLET) on CK۱α expression, AKT/Phospho-ß-catenin (S۵۵۲) pathway, and autophagy flux in RAS-mutated human colorectal HCT ۱۱۶ cells.Materials and Methods: For this purpose, HCT۱۱۶ cells were treated with BAMLET and casein kinase ۱ inhibitor (D۴۴۷۶), and quantitative real-time polymerase chain reaction (RT-qPCR) and western blot analysis were used to measure the proteins and genes of the AKT/Phospho-ß-catenin (S۵۵۲) pathway and autophagy. Apoptosis was measured by flow-cytometry. Results: We found that BAMLET significantly reduced cell viability and decreased the expression of CK۱α. Additionally, BAMLET inhibited autophagy flux and enhanced the ability of CK۱α inhibitor D۴۴۷۶ to impair autophagy flux, which was accompanied by an increase in the apoptosis percentage. We also observed that BAMLET empowered D۴۴۷۶ to down-regulate the AKT/Phospho-ß-catenin (S۵۵۲) axis. Conclusion: BAMLET hampers autophagy flux and leads to apoptosis induction, possibly, by reducing the expression of CK۱α and attenuation of the AKT/Phospho-ß-catenin (S۵۵۲) axis.

AKT/p-ß-catenin (S۵۵۲), Autophagy, BAMLET, CK۱α, RAS