104P - Choline transporter-like protein 1 is a novel molecular target for the treatment of hepatocellular carcinoma

Background

Hepatocellular carcinoma (HCC), the most common type of primary liver cancer, has a high incidence and mortality rate, and it is desirable to develop new therapeutic agents to overcome unmet medical needs. Choline is essential for the synthesis of phospholipids, the main component of cell membranes, and abnormal choline accumulation in cancer cells is strongly correlated with malignant tumor growth. Recently, choline transporter-like protein 1 (CTL1), which is highly expressed in cancer cells, has attracted attention as a novel target molecule in cancer therapy. In this study, we analyzed the functional expression of choline transporters in human HCC cells and investigated the antitumor effects of CTL1 inhibitors.

Methods

The characteristics of [³H]choline uptake were examined using a highly differentiated human HCC cell line, HuH-7.Expression analysis of choline transporters was performed by RT-PCR and Western blotting. Cell viability and caspase-3/7 activity were measured using the CellTiter-Glo Luminescent Cell Viability Assay and Caspase-Glo 3/7 Assay System, respectively.

Results

CTL1 was highly expressed in HuH-7 cells and localized to the cell membrane. [³H]Choline uptake was Na⁺-independent and pH-dependent, via a single transport system. Annexin V-positive cells were observed when cells were cultured in choline-deficient conditions. CTL1 inhibitors decreased cell viability, increased caspase-3/7 activity, and inhibited migration of HuH-7 cells. CTL1 inhibitors activated the sphingomyelinase/ceramide pathway, and ceramide inhibited cell survival and increased caspase-3/7 activity.

Conclusions

The transport of extracellular choline is mediated by CTL1 in HuH-7 cells, and inhibition of CTL1 function induces apoptosis, suggesting that CTL1 may be a new target molecule for cancer therapy. Furthermore, CTL1 inhibitors induced apoptotic cell death through the ceramide pathway, suggesting that it may be a novel therapeutic agent for liver cancer. It also has an inhibitory effect on the migration of HuH-7 cells and is expected to suppress lymph node metastasis in HCC patients.

Clinical trial identification

Editorial acknowledgement

Legal entity responsible for the study

Tokyo Medical University.

Funding

Has not received any funding.

Disclosure

All authors have declared no conflicts of interest.