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Crosstalk between hedgehog and Wnt pathways in gastric cancer cell differentiation

Authors
 김지현 
Issue Date
2009
Description
Dept. of Medicine/박사
Abstract
[한글]위암은 조직학적 형태에 따라 다른 생물학적 행태를 가지고 있다고 알려져 있으며, 다른 생물학적 행태에 대한 차별적 신호전달체계가 존재할 수 있다. 본 연구의 목적은 위암 세포에서 조직학적 분화도에 따른 Hedgehog (Hh)과 Wnt 신호전달의 차이를 분석하고자 하였다. 위암세포주로 AGS, MKN-45를 사용하였으며, 실험실적 분화에 대한 양적 대조군으로 대장암 세포주인 HT-29를 사용하였다. 암세포의 분화는 sodium butyrate와 all-trans retinoid acid로 유도하였다. Hh 신호분석을 위하여 sonic hedgehog (SHh), Patched (Ptc)-1, glioma-associated oncogene (Gli)-1을 측정하였으며, Wnt 신호분석을 위하여 핵내 β-catenin을 측정하였다. 위암환자들의 파라핀 조직을 통하여 생체조직의 Hh과 Wnt 신호전달을 분석하였고, Hh과 Wnt 신호전달의 상호작용은 secreted frizzled-related protein (sFRP-1)으로 분석하였다. 위암세포도 대장암세포와 비슷한 양상으로 실험실적 분화가 유도되었는데, 분화되는 동안 Hh신호전달은 활성화되었으나, Wnt 신호전달은 억제되는 양상을 보였다. Gli-1을 과발현 시켰을 때 sFRP-1의 전사가 증가하였으며, Gli-1를 억제하였을 때에는 sFRP-1의 전사가 감소하였고, 이는 chromatin immunoprecipitation (Chip) assay를 통하여 Gli-1이 sFRP-1의 전사를 조절함을 알 수 있었다. Wnt 신호전달에 있어서는 Gli-1의 과발현시 핵내 β-catenin 발현이 감소하였으나, Gli-1을 억제하였을 때 핵내 β-catenin 발현이 회복되었다. 위암환자 조직에서 시행한 면역화학염색에서는 SHh, Gli-1 단백이 고분화 선암에서 저분화 선암보다 강하게 발현되었으며, 핵내 β-catenin 단백은 저분화 선암에서 고분화 선암보다 강하게 발현되었다. 결론적으로 위암세포가 분화하는 동안 Hh신호전달은 활성화되고 Wnt신호전달은 억제되었다. 이와 같이 분화 특이 신호전달변화가 암의 진행이나 전이와 관련된 신호전달과 같이 분석이 된다면 위암의 분자생물학적 이질성을 이해하는 데에 도움이 될 것이다.
[영문]Gastric cancer has different biological behaviors to the histological type. Thus, the different histological growth patterns of gastric cancers may involve the activation of distinct signaling pathways necessary for the growth and survival of cancer cells. This study investigated the differentiation-specific signal changes between hedgehog (Hh) and Wnt signaling pathways in AGS and MKN-45 gastric cancer cells, and HT 29 colon cancer cells were used as positive controls for differentiation in vitro. Differentiation was induced by sodium butyrate and all-trans retinoid acid. Sonic hedgehog (SHh), patched (Ptc)-1, and glioma-associated oncogene (Gli)-1 were analyzed for Hh signaling, and nuclear β-catenin was analyzed for Wnt signaling. Paraffin-embedded tissues from human gastric cancers were used to evaluate the expression of SHh, Gli-1, and β-catenin in vivo. Secreted frizzled related protein (sFRP)-1 was analyzed as a regulator between Hh and Wnt signaling. As results, expression of Hh signaling was increased during differentiation. In contrast, the expression of Wnt signaling was decreased during differentiation. Ectopic expression of Gli-1 increased the level of the sFRP-1 transcript, whereas the inhibition of Gli-1 reduced the level of the sFRP-1 transcript. Chromatin immunoprecipitation assay indicated that Gli-1 was involved in the transcriptional regulation of sFRP-1. Ectopic expression of Gli-1 decreased the expression of nuclear β-catenin, and the inhibition of Gli-1 recovered the level of nuclear β-catenin. SHh- and Gli-1-positive immunoexpression was higher in well differentiated than in poorly differentiated tissues. However, nuclear β-catenin-positive immunoexpression was lower in well differentiated compared to poorly differentiated tissues. In conclusion, the activation of the Hh pathway and suppression of the Wnt pathway by Hh signaling occurred during gastric cancer cell differentiation. It is suggested that the analysis of differentiation-specific signal changes, combined with signals related to the process of tumor progression or migration, may be a clue in discovering the molecular heterogeneity of gastric cancers.
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Appears in Collections:
1. College of Medicine (의과대학) > Dept. of Internal Medicine (내과학교실) > 3. Dissertation
Yonsei Authors
Kim, Jie-Hyun(김지현) ORCID logo https://orcid.org/0000-0002-9198-3326
URI
https://ir.ymlib.yonsei.ac.kr/handle/22282913/124494
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