The biliary tract is a general term for the bile duct, gallbladder, and papilla of the duodenum, which are channels for bile. Hence, malignant tumors occurring in these areas are called biliary tract cancer. Additionally, Cholangiocarcinoma is one of the advanced cancer types that appears as a symptom after it blocks the bile duct and is difficult to cure. The cause of bile duct cancer is still not understood. However, it has recently been reported that the long-term use of dichloromethane and dichloropropane, the chemicals used in the printing business, increases the incidence of bile duct cancer.

It is also well-known that side effects and pains accompany cancer treatments, and treatment with fewer side effects is required. On a positive note, Fucoidan has no side effects, and numerous studies have reported that Fucoidan has antitumor effects.

In this blog, I would like to inform the study by Pathanin Chantree et al., “Anticancer Activity of Fucoidan via Apoptosis and Cell Cycle Arrest on Cholangiocarcinoma Cell.”

The study aimed to investigate the cytotoxic effects and associated cell death mechanisms induced by Fucoidan extracted from Fucus vesiculosus on CL-6 cholangiocarcinoma cells.

First, CL-6 and OUMS (human chondrosarcoma cell line) cells were treated with 0, 100, 200, and 300 μg/mL fucoidan. MTT assay was used to determine cytotoxicity. As a result, they found that cytotoxicity in CL-6 cells did not affect normal OUMS cells. Next,  they examined apoptosis and cell cycle distribution using flow cytometry-based assays. After treatment with Fucoidan for 24 hours, the cell viability of CL-6 cells decreased from 50 to 400 μg/mL in a concentration-dependent manner compared to the untreated group (See Figure 1A).

The effect of Fucoidan on mitochondrial membrane potential in CL-6 cells was measured using JC-1 staining. As a result, mitochondrial depolarization is indicated by a decrease in the ratio of red and green fluorescence intensities. Treatment with increasing concentrations of Fucoidan reduced the number of red-fluorescent CL-6 cells in a concentration-dependent manner. The results revealed a significant reduction in the JC-1 ratio (See Figure 2E).

These results suggest that Fucoidan altered the mitochondrial membrane potential and induced apoptosis in CL-6 cells. Studies of cell cycle-associated proteins were examined by Western blot analysis. As a result, relative viable cell numbers were reduced in his CL-6 treated cells, while no effect was observed in OUMS normal cells.

Additionally, treated cells were arrested in the G0/G1 phase due to the downregulation of cyclin D1 and CDK4. The apoptotic effect at the protein expression level of Fucoidan in CL-6 cells was also evaluated. Next, the expression levels of apoptosis- and anti-apoptosis-related proteins were determined. For apoptotic markers, the relative expression levels of cleaved PARP increased significantly in a concentration-dependent manner. Results for the apoptotic proteins, Bax, and cleaved caspase-3 suggested significant expression level concentration-dependent increases.

On the contrary, the expression of the anti-apoptotic protein Bcl-2 was significantly reduced. (See Figures 3A and C) Also, the ratio of Bax to Bcl-2 was significantly increased (See Figure 3E). Western blot studies revealed upregulation of apoptotic markers, including Bax, cleaved PARP, and cleaved caspase-3, downregulation of cl-2 was an anti-apoptotic identification. The result is that Fucoidan uses antitumor properties against CL-6 Cholangiocarcinoma cells, indicated by induction of apoptosis and cell cycle arrest.

The study revealed that Fucoidan might exert cytotoxicity on CL-6 Cholangiocarcinoma via induction of apoptosis and cell cycle arrest.

Source: Asian Pac J Cancer Prev. 2021 Jan; 22(1): 209–217       Doi: 10.31557/APJCP.2021.22.1.209