Activation of the sonic hedgehog signaling pathway occurs in the CD133 positive cells of mouse liver cancer Hepa 1-6 cells.
BACKGROUND
The important role of cancer stem cells in carcinogenesis has been emphasized in research. CD133+ cells have been mentioned as liver cancer stem cells in hepatocellular carcinoma (HCC). Some researchers have proposed that the sonic hedgehog (Shh) pathway contributes to hepatocarcinogenesis and that the pathway activation occurs mainly in cancer stem cells. We investigated whether the activation of the Shh pathway occurs in CD133+ cells from liver cancer.


METHODS
We used magnetic sorting to isolate CD133+ cells from mouse cancer Hepa 1-6 cells. To examine the clonogenicity, cell culture and soft agar colony formation assay were performed between CD133+ and CD133- cells. To study the activation of the Shh pathway, we examined the mRNA expressions of Shh, patched homolog 1 (Ptch-1), glioma-associated oncogene homolog 1 (Gli-1), and smoothened homolog (Smoh) by real-time polymerase chain reaction of both CD133+ and CD133- cells.


RESULTS
The number (mean ± standard deviation) of colonies of CD133+ cells and CD133- cells was 1,031.0 ± 104.7 and 119.7 ± 17.6 respectively. This difference was statistically significant (P < 0.001). Their clonogenicity was 13.7% ± 1.4% and 1.6% ± 0.2% respectively with a statistically significant difference found (P < 0.001). CD133+ cells and CD133- cells were found to have statistically significant differences in Shh mRNA and Smoh mRNA (P = 0.005 and P = 0.043 respectively).


CONCLUSIONS
CD133+ Hepa 1-6 cells have a significantly higher colony proliferation and clonogenicity. The Shh pathway is activated in these cells that harbor stem cell features, with an underexpression of Shh mRNA and an overexpression of Smoh mRNA. Blockade of the Shh signaling pathway may be a potential therapeutic strategy for hepatocarcinogenesis.
Department of Surgery, Far Eastern Memorial Hospital, Taipei, Taiwan, Republic of China.
Kuo-Shyang
KS
Jeng
I-Shyan
IS
Sheen
Wen-Juei
WJ
Jeng
Ming-Che
MC
Yu
Hsin-I
HI
Hsiau
Fang-Yu
FY
Chang
Hsin-Hua
HH
Tsai
CD133+ cells; Hepa 1–6; hepatocellular carcinoma; liver cancer; sonic hedgehog; stem cells