Functional analysis of [methyl-3H]choline uptake in glioblastoma cells: Influence of anti-cancer and central nervous system drugs

• Published in: Biochemical pharmacology 2014-04, Vol.88 (3), p.303-312
• Main Authors: Taguchi, Chiaki, Inazu, Masato, Saiki, Iwao, Yara, Miki, Hara, Naomi, Yamanaka, Tsuyoshi, Uchino, Hiroyuki
• Format: Article
• Language: English
• Subjects: Antigens, CD - genetics; Antigens, CD - metabolism; Antineoplastic Agents - pharmacology; Astrocytes - metabolism; Cell Line, Tumor; Cell Survival - drug effects; Central Nervous System Agents - pharmacology; Choline; Choline - metabolism; Choline PET; Extracellular Space - chemistry; Glioblastoma - metabolism; Glioblastoma cells; Humans; Hydrogen-Ion Concentration; Membrane Glycoproteins - genetics; Membrane Glycoproteins - metabolism; Membrane Transport Proteins - genetics; Membrane Transport Proteins - metabolism; Organic Cation Transport Proteins - genetics; Organic Cation Transport Proteins - metabolism; Radiopharmaceuticals - metabolism; RNA, Messenger - metabolism; Symporters - genetics; Symporters - metabolism; Transporter; Tritium
• ISSN: 0006-2952; 1873-2968
• DOI: 10.1016/j.bcp.2014.01.033

Positron emission tomography (PET) and PET/computed tomography (PET-CT) studies with 11C- or 18F-labeled choline derivatives are used for PET imaging in glioblastoma patients. However, the nature of the choline transport system in glioblastoma is poorly understood. In this study, we performed a functional characterization of [methyl-3H]choline uptake and sought to identify the transporters that mediate choline uptake in the human glioblastoma cell lines A-172 and U-251MG. In addition, we examined the influence of anti-cancer drugs and central nervous system drugs on the transport of [methyl-3H]choline. High- and low-affinity choline transport systems were present in A-172 cells, U-251MG cells and astrocytes, and these were Na+-independent and pH-dependent. Cell viability in A-172 cells was not affected by choline deficiency. However, cell viability in U-251MG cells was significantly inhibited by choline deficiency. Both A-172 and U-251MG cells have two different choline transporters, choline transporter-like protein 1 (CTL1) and CTL2. In A-172 cells, CTL1 is predominantly expressed, whereas in U-251MG cells, CTL2 is predominantly expressed. Treatment with anti-cancer drugs such as cisplatin, etoposide and vincristine influenced [methyl-3H]choline uptake in U-251MG cells, but not A-172 cells. Central nervous system drugs such as imipramine, fluvoxamine, paroxetine, reboxetine, citalopram and donepezil did not affect cell viability or [methyl-3H]choline uptake. The data presented here suggest that CTL1 and CTL2 are functionally expressed in A-172 and U-251MG cells and are responsible for [methyl-3H]choline uptake that relies on a directed H+ gradient as a driving force. Furthermore, while anti-cancer drugs altered [methyl-3H]choline uptake, central nervous system drugs did not affect [methyl-3H]choline uptake.