Biology subjects

Oh, B.-C.

Publications and source records attributed to Oh, B.-C..

3 recordsLinked to original sources

bioRxiv2025

Linoleic acid metabolite, 13-S-hydroxyoctadecadienoic acid, suppresses cancer cell growth by inhibiting mTOR

Mechanistic target of rapamycin (mTOR) is a key protein kinase that integrates various internal and external signals to control biological events including cell growth. Whereas substantial efforts were made to elucidate protein subunits interacting with mTOR, endogenous metabolite-mTOR interactions remain largely unknown. Using affinity protein purification and mass spectrometry, we identified direct binding of mTOR to 13-S-hydroxyoctadecadienoic acid (13-S-HODE) which is an oxygenated metabolite of linoleic acid, a polyunsaturated essential fatty acid. Interaction of 13-S-HODE with the catalytic ATP-binding domain of mTOR prevented its kinase activity in an ATP-competitive manner. Furthermore, either 13-S-HODE treatment or expression of arachidonate 15-lipoxygenase (ALOX15), an enzyme responsible for 13-S-HODE production, reduced mTOR signaling, thereby suppressing the growth of cancer cells as well as tumor xenografts. Our results highlight the importance of 13-S-HODE serving as a tumor suppressive, mTOR-inhibiting metabolite that links polyunsaturated fatty acid metabolism and the mTOR signaling in controlling cancer cell growth.

biochemistry↗

bioRxiv2021

Lomitapide, a cholesterol-lowering drug, is an anticancer agent that induces autophagic cell death via inhibiting mTOR

Autophagy is a biological process that maintains cellular homeostasis and regulates the internal cellular environment. Hyperactivating autophagy to trigger cell death has been a suggested therapeutic strategy for cancer treatment. Mechanistic target of rapamycin (mTOR) is a crucial protein kinase that regulates autophagy; therefore, using a structure-based virtual screen analysis, we identified lomitapide, a cholesterol-lowering drug, as a potential mTOR complex 1 (mTORC1) inhibitor. Our results showed that lomitapide directly inhibits mTORC1 in vitro and induces autophagy-dependent cancer cell death by decreasing mTOR signaling, thereby inhibiting the downstream events associated with increased LC3 conversion in various cancer cells (e.g., HCT116 colorectal cancer cells) and tumor xenografts. Lomitapide also significantly suppresses the growth and viability along with elevated autophagy in patient-derived colorectal cancer organoids. Furthermore, a combination of lomitapide and immune checkpoint blocking antibodies synergistically inhibits tumor growth in murine MC-38 or B16-F10 pre-clinical syngeneic tumor models. These results elucidates the direct, tumor-relevant immune-potentiating benefits of mTORC1 inhibition by lomitapide, which complement the current immune checkpoint blockade. This study highlights the potential repurposing of lomitapide as a new therapeutic option for cancer treatment.

cancer biology↗

bioRxiv2019

High-phytate/low-calcium diet is a risk factor for crystal nephropathies, renal phosphate wasting, and bone loss

Phosphate overload contributes to mineral bone disorders associated with crystal nephropathies. Phytate, the major form of phosphorus in plant seeds, is known as an indigestible and negligible in humans. However, the mechanism and adverse effects of high-phytate intake on Ca2+ and phosphate absorption and homeostasis are unknown. Here we show that excessive intake of phytate with a low-Ca2+ diet fed to rats contributed to the development of crystal nephropathies, renal phosphate wasting, and bone loss through tubular dysfunction secondary to dysregulation of intestinal calcium and phosphate absorption. Moreover, Ca2+ supplementation alleviated the detrimental effects of excess dietary phytate on bone and kidney through excretion of undigested Ca2+-phytate, which prevented a vicious cycle of intestinal phosphate overload and renal phosphate wasting while improving intestinal Ca2+ bioavailability. Thus, we demonstrate that phytate is digestible without a high-Ca2+ diet and a risk factor for phosphate overloading and developing crystal nephropathies and bone disease.

physiology↗