Activation of the hedgehog pathway in human hepatocellular carcinomas.
Liver cancers, the majority of which are hepatocellular carcinomas (HCCs), rank as the fourth in cancer mortality worldwide and are the most rapidly increasing type of cancer in the United States. However, the molecular mechanisms underlying HCC development are not well understood. Activation of the hedgehog pathway is shown to be involved in several types of gastrointestinal cancers. Here, we provide evidence to indicate that hedgehog signaling activation occurs frequently in HCC. We detect expression of Shh, PTCH1 and Gli1 in 115 cases of HCC and in 44 liver tissues adjacent to the tumor. Expression of Shh is detectable in about 60% of HCCs examined. Consistent with this, hedgehog target genes PTCH1 and Gli1 are expressed in over 50% of the tumors, suggesting that the hedgehog pathway is frequently activated in HCCs. Of five cell lines screened, we found Hep3B, Huh7 and PLC/PRF/5 cells with detectable hedgehog target genes. Specific inhibition of hedgehog signaling in these three cell lines by smoothened (SMO) antagonist, KAAD-cyclopamine, or with Shh neutralizing antibodies decreases expression of hedgehog target genes, inhibits cell growth and results in apoptosis. In contrast, no effects are observed after these treatments in HCC36 and HepG2 cells, which do not have detectable hedgehog signaling. Thus, our data indicate that hedgehog signaling activation is an important event for development of human HCCs.
Huang
Shuhong
S
Department of Pharmacology and Toxicology, Sealy Center for Cancer Cell Biology, University of Texas Medical Branch, 301 University Boulevard, Galveston, TX 77555-1048, USA.
He
Jing
J
Zhang
Xiaoli
X
Bian
Yuehong
Y
Yang
Ling
L
Xie
Guorui
G
Zhang
Kefei
K
Tang
Wendell
W
Stelter
Arwen A
AA
Wang
Qian
Q
Zhang
Hongwei
H
Xie
Jingwu
J
D006528:Carcinoma, Hepatocellular / Q000378:metabolism*; D002470:Cell Survival / Q000502:physiology; D002478:Cells, Cultured; D015870:Gene Expression; D053823:Hedgehog Proteins; D006801:Humans; D017403:In Situ Hybridization; D020287:In Situ Nick-End Labeling; D008113:Liver Neoplasms / Q000378:metabolism*; D015513:Oncogene Proteins / Q000378:metabolism; D000072079:Patched Receptors; D000072081:Patched-1 Receptor; D012333:RNA, Messenger / Q000032:analysis; D011956:Receptors, Cell Surface / Q000378:metabolism; D043562:Receptors, G-Protein-Coupled / Q000037:antagonists & inhibitors; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction / Q000502:physiology; D000072086:Smoothened Receptor; D015534:Trans-Activators / Q000378:metabolism*; D000071676:Zinc Finger Protein GLI1
D053823:Hedgehog Proteins; D015513:Oncogene Proteins; C000606236:PTCH1 protein, human; D000072079:Patched Receptors; D000072081:Patched-1 Receptor; D012333:RNA, Messenger; D011956:Receptors, Cell Surface; D043562:Receptors, G-Protein-Coupled; C509239:SHH protein, human; C491023:SMO protein, human; D000072086:Smoothened Receptor; D015534:Trans-Activators; D000071676:Zinc Finger Protein GLI1