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Expression and localization of sterile alpha motif domain containing 5 is associated with cell type and malignancy of biliary tree

View Article: PubMed Central - PubMed

ABSTRACT

Cholangiocarcinoma (CC) is a type of relatively rare neoplasm in adenocarcinoma. The characteristics of CCs as well as biliary epithelial cells are heterogeneous at the different portion of the biliary tree. There are two candidate stem/progenitor cells of the biliary tree, i.e., biliary tree stem/progenitor cell (BTSC) at the peribiliary gland (PBG) of large bile ducts and liver stem/progenitor cell (LPC) at the canals of Hering of peripheral small bile duct. Although previous reports suggest that intrahepatic CC (ICC) can arise from such stem/progenitor cells, the characteristic difference between BTSC and LPC in pathological process needs further investigation, and the etiology of CC remains poorly understood. Here we show that Sterile alpha motif domain containing 5 (SAMD5) is exclusively expressed in PBGs of large bile ducts in normal mice. Using a mouse model of cholestatic liver disease, we demonstrated that SAMD5 expression was upregulated in the large bile duct at the hepatic hilum, the extrahepatic bile duct and PBGs, but not in proliferating intrahepatic ductules, suggesting that SAMD5 is expressed in BTSC but not LPC. Intriguingly, human ICCs and extrahepatic CCs exhibited striking nuclear localization of SAMD5 while the normal hilar large bile duct displayed slight-to-moderate expression in cytoplasm. In vitro experiments using siRNA for SAMD5 revealed that SAMD5 expression was associated with the cell cycle regulation of CC cell lines. Conclusion: SAMD5 is a novel marker for PBG but not LPC in mice. In humans, the expression and location of SAMD5 could become a promising diagnostic marker for the cell type as well as malignancy of bile ducts and CCs.

No MeSH data available.


Expression profiles of SAMD5 in human HCC and CC cell lines.(A) the relative expression of SAMD5 gene in four CC cell lines (HuH28, TFK1, RBE and TKKK) and one HCC cell line (HuH7) to normal biliary epithelial cell (BEC) by quantitative RT-PCR. SAMD5 mRNA was increased in all CC cell lines, but not expressed in HuH7. (n = 3; *P <0.05, compared to BEC) Data are mean ± standard error. n.d.: not detected (B). Immunocytochemical images of SAMD5 for CC cell lines. SAMD5 is visualized and localized at the nuclei of TKKK and RBE. Bars = 50 μm. (C and D) Images of exogenously introduced FLAG-tagged SAMD5 in HuH7 (C) and HuH28 (D) by Immunocytochemical staining. Overexpressed SAMD5 translocated to the nuclei of each cell. Bars = 50 μm.
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pone.0175355.g005: Expression profiles of SAMD5 in human HCC and CC cell lines.(A) the relative expression of SAMD5 gene in four CC cell lines (HuH28, TFK1, RBE and TKKK) and one HCC cell line (HuH7) to normal biliary epithelial cell (BEC) by quantitative RT-PCR. SAMD5 mRNA was increased in all CC cell lines, but not expressed in HuH7. (n = 3; *P <0.05, compared to BEC) Data are mean ± standard error. n.d.: not detected (B). Immunocytochemical images of SAMD5 for CC cell lines. SAMD5 is visualized and localized at the nuclei of TKKK and RBE. Bars = 50 μm. (C and D) Images of exogenously introduced FLAG-tagged SAMD5 in HuH7 (C) and HuH28 (D) by Immunocytochemical staining. Overexpressed SAMD5 translocated to the nuclei of each cell. Bars = 50 μm.

Mentions: To further investigate the role of SAMD5 in CC cells, the expression level of SAMD5 gene in four CC cell lines (HuH28, TFK1, RBE and TKKK) and one HCC cell line (HuH7) relative to normal BEC was examined. Quantitative RT-PCR revealed that SAMD5 mRNA was increased in all CC cell lines compared to BEC, but not expressed in HuH7 (Fig 5A). The IHC staining of SAMD5 demonstrated that intense signals of SAMD5 were detected in the nuclei of TKKK, RBE and TFK1 (Fig 5B and S3 Fig). These results indicated that SAMD5 is localized in the nuclei of CC cell lines as well as CC specimens.


Expression and localization of sterile alpha motif domain containing 5 is associated with cell type and malignancy of biliary tree
Expression profiles of SAMD5 in human HCC and CC cell lines.(A) the relative expression of SAMD5 gene in four CC cell lines (HuH28, TFK1, RBE and TKKK) and one HCC cell line (HuH7) to normal biliary epithelial cell (BEC) by quantitative RT-PCR. SAMD5 mRNA was increased in all CC cell lines, but not expressed in HuH7. (n = 3; *P <0.05, compared to BEC) Data are mean ± standard error. n.d.: not detected (B). Immunocytochemical images of SAMD5 for CC cell lines. SAMD5 is visualized and localized at the nuclei of TKKK and RBE. Bars = 50 μm. (C and D) Images of exogenously introduced FLAG-tagged SAMD5 in HuH7 (C) and HuH28 (D) by Immunocytochemical staining. Overexpressed SAMD5 translocated to the nuclei of each cell. Bars = 50 μm.
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Related In: Results  -  Collection

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pone.0175355.g005: Expression profiles of SAMD5 in human HCC and CC cell lines.(A) the relative expression of SAMD5 gene in four CC cell lines (HuH28, TFK1, RBE and TKKK) and one HCC cell line (HuH7) to normal biliary epithelial cell (BEC) by quantitative RT-PCR. SAMD5 mRNA was increased in all CC cell lines, but not expressed in HuH7. (n = 3; *P <0.05, compared to BEC) Data are mean ± standard error. n.d.: not detected (B). Immunocytochemical images of SAMD5 for CC cell lines. SAMD5 is visualized and localized at the nuclei of TKKK and RBE. Bars = 50 μm. (C and D) Images of exogenously introduced FLAG-tagged SAMD5 in HuH7 (C) and HuH28 (D) by Immunocytochemical staining. Overexpressed SAMD5 translocated to the nuclei of each cell. Bars = 50 μm.
Mentions: To further investigate the role of SAMD5 in CC cells, the expression level of SAMD5 gene in four CC cell lines (HuH28, TFK1, RBE and TKKK) and one HCC cell line (HuH7) relative to normal BEC was examined. Quantitative RT-PCR revealed that SAMD5 mRNA was increased in all CC cell lines compared to BEC, but not expressed in HuH7 (Fig 5A). The IHC staining of SAMD5 demonstrated that intense signals of SAMD5 were detected in the nuclei of TKKK, RBE and TFK1 (Fig 5B and S3 Fig). These results indicated that SAMD5 is localized in the nuclei of CC cell lines as well as CC specimens.

View Article: PubMed Central - PubMed

ABSTRACT

Cholangiocarcinoma (CC) is a type of relatively rare neoplasm in adenocarcinoma. The characteristics of CCs as well as biliary epithelial cells are heterogeneous at the different portion of the biliary tree. There are two candidate stem/progenitor cells of the biliary tree, i.e., biliary tree stem/progenitor cell (BTSC) at the peribiliary gland (PBG) of large bile ducts and liver stem/progenitor cell (LPC) at the canals of Hering of peripheral small bile duct. Although previous reports suggest that intrahepatic CC (ICC) can arise from such stem/progenitor cells, the characteristic difference between BTSC and LPC in pathological process needs further investigation, and the etiology of CC remains poorly understood. Here we show that Sterile alpha motif domain containing 5 (SAMD5) is exclusively expressed in PBGs of large bile ducts in normal mice. Using a mouse model of cholestatic liver disease, we demonstrated that SAMD5 expression was upregulated in the large bile duct at the hepatic hilum, the extrahepatic bile duct and PBGs, but not in proliferating intrahepatic ductules, suggesting that SAMD5 is expressed in BTSC but not LPC. Intriguingly, human ICCs and extrahepatic CCs exhibited striking nuclear localization of SAMD5 while the normal hilar large bile duct displayed slight-to-moderate expression in cytoplasm. In vitro experiments using siRNA for SAMD5 revealed that SAMD5 expression was associated with the cell cycle regulation of CC cell lines. Conclusion: SAMD5 is a novel marker for PBG but not LPC in mice. In humans, the expression and location of SAMD5 could become a promising diagnostic marker for the cell type as well as malignancy of bile ducts and CCs.

No MeSH data available.