Choline transporter-like protein 1 in tongue squamous cell carcinoma - implications for cell proliferation and differentiation

Sep 23, 2026

Uploaded by Aran

Choline transporter-like protein 1 (CTL1) shows moderate to high expression across multiple cancer types, yet its role in oral squamous cell carcinoma (OSCC) remains insufficient. This study analyzes CTL1 expression and subcellular localization in OSCC cell lines using immunocytochemistry and western blotting, and evaluates proliferation effects via a choline uptake inhibitor. In vivo and ex vivo staining of rat and human tissues demonstrates strong CTL1 expression, with higher levels in well-differentiated tumors, linking CTL1 to OSCC proliferation and differentiation and supporting its value as a progression marker.

LanguageEnglish

CategoryHealthcare

FormatPDF

Pages13

Reading Time33 min

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CTL1 expression and localization in OSCC

In vitro evidence in OSCC cell lines

Proliferation assays using choline uptake inhibition

In vivo and ex vivo tumor expression patterns

Differential expression in well- vs poorly-differentiated tumors

Choline metabolism and its relevance to cancer progression

Choline uptake, membrane synthesis, and cholinergic phenotype

Diagnostic and clinical imaging relevance

[www. nature.com/scientificreports](www. nature.com/scientificreports) OPEN Choline transporter-like protein 1 in tongue squamous cell carcinoma: implications for cell proliferation and differentiation Nao Hashimoto1􀀍, Kei Nakajima2􀀍, Yoshihiko Akashi2, Katsutoshi Kokubun2 , Keisuke Sugahara1, Akira Katakura1 & Kenichi Matsuzaka2 Studies have indicated moderate to high choline transporter-like protein 1 (CTL1) expression in colon, pancreatic, breast, lung, and glioma cancers. However, studies on CTL1 in oral squamous cell carcinoma (OSCC), a highly invasive cancer, remain limited. We aimed to investigate the expression and localization ofCTL1 in OSCC and its association with cell proliferation. Using in vitro experiments, we evaluated CTL1 expression and localization in the OSCC cell lines HSC-3 and HSC- 4 by immunocytochemistry and western blotting. A cell proliferation assay was performed using hemicolinium-3, a choline uptake inhibitor. Using in vivo and ex vivo experiments, we assessed CTL1 expression in rat and human tongue cancer tissues by immunohistochemical and immunofluorescent staining. Here, we show that CTL1 is strongly expressed intracellularly and localized in organelles of HSC-3 and HSC-4 cells. CTL1 significantly accumulated around the nucleus in Ki67-positive cells with proliferative potential, suggesting increased production and transport ofCTL1. Conversely, the number of cells in the HC-3 treated group in both HSC-3 and HSC-4 cells decreased. These results suggest that intracellular production ofCTL1 is further increased in Ki67-positive cells, and choline uptake may lead to cell proliferation. In vivo and ex vivo experiments revealed high CTL1 expression in tongue cancer, with stronger expression in well-differentiated tumors than that in poorly-differentiated ones. Our study demonstrates that CTL1 is associated with OSCC proliferation and tumor differentiation. These findings suggest that CTL1 may function as a potential marker for tumor differentiation and progression of OSCC. Oral squamous cell carcinoma (OSCC) is a highly invasive cancer with frequent lymph node metastasis. Tumor proliferation and differentiation influence tumor grade and prognosis, with differentiation status crucial in assessing growth rate and metastatic potential1. While oral surgeons can detect suspicious oral lesions, delayed diagnosis due to infrequent checkups often results in OSCC being detected at stage III or later in tertiary care settings. Limited awareness of oral cancer further contributes to late presentation. Surgical resection remains the primary treatment for OSCC, but extensive procedures in advanced cases impose significant physical, social, and psychological burdens, reducing patients’ quality of life. While molecular-targeted therapies, such as cetuximab (an epidermal growth factor receptor inhibitor) and immune checkpoint inhibitor anti-programmed death-1 (PD-1) monoclonal antibody (nivolumab and pembrolizumab), have shown promise for OSCC2, the availability of effective targeted therapies remains limited, indicating the need for novel treatment strategies. Dysregulated choline metabolism has become a key factor in cancer proliferation3,4. Choline, an essential nutrient of dietary origin, is crucial for synthesizing membrane phospholipids, including phosphatidylcholine (PtdCho) and sphingomyelin. High choline uptake and PtdCho biosynthesis are necessary for new membrane synthesis5. Elevated levels of metabolic intermediates such as phosphocholine (PCho) and total choline (tCho), which are generated in choline phospholipid metabolism, are commonly observed in cancer cells3. These changes result from increased choline kinase alpha (CKα) activity, enhanced choline transport, and upregulated PtdCho-specific phospholipase C and D4. Consequently, enhanced transport of free extracellular choline into cancer cells is the dominant cause of the cholinergic phenotype because it may be the rate-limiting st

FAQs

How did the study assess CTL1 expression in oral squamous cell carcinoma?

It used in vitro immunocytochemistry and western blotting in OSCC cell lines (HSC-3 and HSC-4), and applied immunohistochemical and immunofluorescent staining in rat and human tongue cancer tissues.

What relationship did the study find between CTL1 and cell proliferation in OSCC?

CTL1 strongly accumulated around the nucleus in Ki67-positive cells, and CTL1-associated choline uptake corresponded with decreased cell numbers when CTL1-related uptake was inhibited, supporting a role in proliferation.

How did CTL1 expression differ between tumor differentiation states?

In vivo and ex vivo experiments showed higher CTL1 expression in well-differentiated tongue tumors compared with poorly differentiated ones.

Sep 23, 2026

Uploaded by Aran